CA1340066C - Graft copolymers and blends thereof with polyolefins - Google Patents
Graft copolymers and blends thereof with polyolefinsInfo
- Publication number
- CA1340066C CA1340066C CA000617058A CA617058A CA1340066C CA 1340066 C CA1340066 C CA 1340066C CA 000617058 A CA000617058 A CA 000617058A CA 617058 A CA617058 A CA 617058A CA 1340066 C CA1340066 C CA 1340066C
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- polymers
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- polyolefin
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Abstract
A novel graft copolymer capable of imparting to a polyolefin when blended therewith high tensile modulus and high sag resistance without increasing melt viscosity, and a method of making the same. The graft copolymer is a polyolefin having a relatively high weight-average molecular weight methacrylate polymer grafted thereto. The graft copolymer is formed by dissolving or swelling a non-polar polyolefin in an inert hydrocarbon solvent, heating to dissolve the polyolefin, and while stirring the mixture, adding a methacrylate monomer, together with an initiator to produce a constant, low concentration of radicals, to form a graft copolymer with a high molecular weight polymer chain covalently bonded or grafted to the polyolefin backbone. The graft copolymer can be separated from the solvent, isolated by volatilizing the solvent, for example in a devolatilizing extruder, and extruded into a desired shape such as a sheet, tube or the like. This graft copolymer can be blended with a polyolefin matrix. The blend exhibits improved physical properties in the melt, upon cooling, and in the solid state, and is useful in cast and oriented films, solid extruded rod and profile, foamed rod, profile and sheet, blown bottles and the like. The graft copolymer further improves compatibility in a wide range of polymer blends.
Description
Field of the Invention This invention relates broadly to a novel graft copolymer car~b'c of imparting to a polyolefin, when blended therewith, high tensile modulus and high resistance to sagging without increasing melt viscosity, and to a nl~tl.od of making the same.
More particularly, the invention relates to a polymerized olefin having gra~ted thereto, by covalent bonding, a polymeric methacrylate chain of relatively high molecular weight. The methacrylate chain has a weight average ~,,e'scul~r weight ~Mw) o~ at least 20,000 and o advant~geolJsly between about 30,000 and 150,000.
In the Illethod of manufacturing the grafted copolymer, a non-polar polyolefin, pr~fer~ly polypropylene or polyethylene, is introduced into an inert hy~ll~a,l,on solvent which dissolves (or swells) the polyolefin, by heating to a temperature at which the polyolefin is dissolved. While agitating the solution, methyl ..,ell,acrylate (MMA) monomer, together with an initiator which generates a constant, low radical flux conce,)l-dl,on sufficient to initiate polymerization of the monomer at the temperature of the solution and the formation of the covalent bond, is gradually added. The polyolefin with a side-chain grafted thereto is thereafter separated from the solvent by volatilizing the solvent, preferably in a devo~iliung extruder. The graft polymer is then blended with a sùitable polyolefin such as polypropylene or polyethylene, and extruded into a desired shape.
*
)Ofi6 RACK~ROUN~ OF THF INVFNTION
Non-polar polyolefins, especially polypropylene and polyethylene and mixtures in various low-density, high-density, and linear low-density form, are major articles of commerce for a wide variety of uses.
Nevertheless, there exist speciqlty needs for which the marketplace has not provided a s~tisf~tory answer. Among these are to overcome the difficulty of thermoforming and processing of the polyolefin, especially unfilled, in a molten or semi-molten form (substantially above its melting point); the polymer tends to sag readily under its own weight because it o exhibits an undesirably low stiffness, and to form shapes of grossly non-uniform thicknesses upon thermoforming. Attempts to correct same by increasing the molecul~r weight lead to difficulties in processing the higher molecular weight polymer not encountered with the lower molecular weight grades.
For the jSO~ACt;C polymer of butene-1, known also as polybutylene, the low melting point has made difficult the crystallizing of the polymer after processing and obtaining the enhanced performance and handling properties crystallization imparts. S~tisfqctory nucleators have not appeared in the marketplace.
Means have also been sought to improve the toughness or impact slren,Jtl, of polypropyl~ne, for inslance. Use of copolymers or ethylene-propylene rubber modified polypropylene has improved toughness, but at the cost of even lower sliffl,ess values, and lower values of heat distortion res;s~ance. It would be desirable to combine impact pelf~.r-"ance of the copolymers with stiflness and heat distortion behavior of the hGIJlGpolylller polyprupylene resin.
Grafting of ",Gno",ers car~hle of vinyl polymerization, such as styrene, methyl methacrylate, and the like, onto polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymers, and 134~066 ethylene-propylene-diene terpolymers has been studied almost since the disoovery of routes to practical preparation of such backbones.
Grafting onto solid polymer by vapor-phase polymerization, by reaction in an extnuder, by peroxidation of the olefinic backbone, and grafting onto pendant double bonds are all routes which have been attempted.
There still exists a need for a route which allows for grafts of relatively high molecular weight, with relatively good grafting efficiency (i.e., lowered formation of unattached polymer molecules), freedom from gel, and a practical means for preparing and isolating the graft polymer in o an efficient and lower-cost manner.
Blends of two or more polymers have often been made, for example in attempts to combine desirable properties of the individual polymers into the blend, to seek unique properties in the blend, or to produce less costly polymer products by including less expensive or scrap polymers in th~ blend. CG",pali~le polymers tend to form blends that contain small do",ains of the individual polymers; in the case of ~miscible~ polymers these occur at the molecular scale, resulting in properties usually considered characteristic of a single polymer. These may include occurrence of a sTngle glass-transition temperature and optical clarity. Such blends are frequently termed ~alloys.~ Coi"pa~ible polymers that are not strictly miscible, as described above, nevertheless tend to form blends with p,upe,lies that approach those of the miscible blends. Such properties as tensile strength, which rely upon adhesion of the domains to om3 another, tend not to be degraded when compatible polymers are blended.
Unfortunately many polymers are poorly compatible with one another. Poor compatibility cannot necess~rily be predicted accurately for a given polymer ~,i"binalion, but in general it may be expected when non-polar polymers are blended with more polar polymers. Poor coi"palibility in a blend is apparent to those skilled in the art, and often 13~0066 evidences itself in poor tensile strength or other physical properties, espeaally when compared to the component polymers of the blend.
Mic..scop-c evidencs of poor compatibility may also be present, in the form of large, poorly adhered domains of one or more polymer components in a matrix of another polymer component of the blend.
More than one glass-transition temperature may be observed, and a blend of otherwise l-dnsparent polymers may be opaque because the domain sizes are large enough to scatter visible light.
Much research has been directed toward finding ways to increase o the compatibility of poorly compatible polymers when blended.
Appr(,acl.es that have been used include adding to the blend polymers which show compatibility with the other, mutually incompatible polymers; such add~d polymers act as a bridge or interface between the incompatible components, and often decrease domain size.
Chlorinated polyethybne has been used as such an additive polymer, especially in blends of polyolefins with other, poorly compatible polymers.
Graft polymers, as of incompatible polymers A onto B, are known to aid in blending po~rmers A and B. Such graft polymers may also serve to aid in blsnding other inc~n,pa~il,le polymers C and D, where A
and C are compatibll~ and B and D are compatible.
What has also been difficult to predict in polymer science is the extent to which such a graft polymer will be effective in enhancing desirable properties of the blend over those of the incompatible blend alone. Consequently, those skilled in the art have had to treat each combination of graft polymer and other co",ponent polymers of a given blend as a special ~ ase, and determine experimentally whether an . improve..,enl in such prupeities as tensile strength could be obtained by adding a specific graft polymer to a specific blend.
13~0066 pFI FVANT ART
U.S. Patent No. 4,094,927 describes copolymers of higher alkyl methacrylates with (meth)acrylic acid as melt strength additives, foam st~bili~ers, and pr~cEs~ing aids for polypropylene. Such polymers, however, are not fully compatible with polypropylene and the additive will tend to plate out and foul equipment during such operations as melt calendering.
U.S. Patent No. 4,409,345 describes polyolefin modified with a polymerizable unsaturated carboxylic ester in affording improved o processing of mixtur~s of polypropylene, high density polyethylene, and finely divided vegetable fibers. The patent appears only to demonstrate reinfor~i"ent by the fibers which are bonded to the polyolefin by the graft copolymer. All examples are limited to ~grafts" of maleic anhydride or acrylic acid, wherein the material grafted is of a molecular weight co,.esponding to a small number of monomer units.
South African Patent No. 826,440 describes "improved melt viscosity~ (higher melt viscosity under low shear conditions while retaining the low melt viscosily at high shear rheology behavior of the un".Gdi~led polypropylene) and improved thermoforming characteristics for blends of polypropylene with certain salts of acid-modified propylene polymers.
U.S. Patent No. 4,370,450 describes modification of polypropylene with polar vinyl monomers by polymerization in aqueous suspension containi~ a swelling agent at temperatures above 85~C
with a radical chain initiator having a half-life of at least 2 hours in the temperature range 80-135~C. The patent does not describe direct solution ~r~fling, stating such yields ~only relatively low degrees of grafting~. HydlocarLons are listed as examples of swelling agents.
~ 13~066 U.S. Patent No. 4,161,452 dsscribes only grafts of unsaturated carboxylic acids or anhydrides and esters of (meth)acrylic acid onto ethylene/propylene copolymers in solution in the presence of a free-radical initiator c~ls of hydrogen abstraction at temperatures between 60 and 220~C. An oil soluble polymer is required.
U.S. Patent No. 4,595,726 describes graft copolymers of C2-C6 alkyl methacrylates onto polypropylene via a solvent-free vapor-phase pol~",eri~dliGn wherein the molecular weight of the graft and the number of grafted chains are controlled to yield the desired (although undefined) length and number of chains for utility in adhesive applications between polypropylene and more polar substrates. The patent .,' scloses that similar grafts can be made from methyl methacrylate, but do not exhibit the desired adhesive properties. The patent requires polymerization bebw the softening point of polypropylene, which is not defined in their patent, which is known to be lowered by the presGnce of monomers, and for which no temperature higher than 1 40~C is exemplified, and in the absence of solvent. There is no indication or suqgestion that a relatively high molecular weight chain is covalently grafted to the polyolefin. Moreover, the radical flux ~eneral~l appears to be too high to form a high molecular weight, e.g.
greater than 20,000, chain.
U.S. Patent No. 4,692,992 describes grafting at temperatures between 60 and 160~C while maintaining the olefin polymer dissolved in a solvent which is a mixture of a hydrocarbon and a ketonic solvent, 7~ the grafted polymer pr~r~pit~';ng upon cooling the reacted mixture below 40~C. Re~ction conditions for achieving high molecu'~r weight or the ~anla~e in ~onducting the reaction in the presence only of a solvent of low chain t~nsfer activity are not ~~isclosed.
U.S. Patent No. 3.86~,~6~ only describes melting of polyolefins in an extnuder, followed by grafting of unsaturated acids to achieve ~ 1340066 ~improved rheology~ as defined in South African Patent No. 826440, supra.
U.S. Patent No. 3,886,227 disclQses (but does not exemplify for the esters) grafting of unsaturated acids and esters to form a material useful as a modifying agent for polypropylene. The grafting is conducted in an extn~der, and they also disclose that the molecular weight of ths bacl~L.one polypropylene polymer be lowered by degradation durins the gralling process, conducted at a temperature above 200~C. It describes blending with polypropylene and the resulting modification found, such as nucleation, lack of warpage on molding, and the like. Although improvement in heat distortion temperature is noted, there is no d;cclQsure of improved rheological performance at the temperatures required for thermoforming and the like.
Japanese Kokai 59-164347 describes grafts of unsaturated acids or their derivatives (including esters) at very iow graft levels (10-5 to 10-8 9 equivalents per gram of polyolefin), blends of the grafts with polyolefins, and their use in affecting surface tension in the molten state of the polyolsfin while not affecting high-shear viscosity, making the blends useful in, e.g. blow molding of bottles.
Kallitis et al., Fl Ir. Polymer J. . 27,117 (1987) describes ethylene-propylene polymers as nucleating agents for polybutylene. They do not describe or suggest the utility of the polypropylene/methacrylic grafts of this invention.
More particularly, the invention relates to a polymerized olefin having gra~ted thereto, by covalent bonding, a polymeric methacrylate chain of relatively high molecular weight. The methacrylate chain has a weight average ~,,e'scul~r weight ~Mw) o~ at least 20,000 and o advant~geolJsly between about 30,000 and 150,000.
In the Illethod of manufacturing the grafted copolymer, a non-polar polyolefin, pr~fer~ly polypropylene or polyethylene, is introduced into an inert hy~ll~a,l,on solvent which dissolves (or swells) the polyolefin, by heating to a temperature at which the polyolefin is dissolved. While agitating the solution, methyl ..,ell,acrylate (MMA) monomer, together with an initiator which generates a constant, low radical flux conce,)l-dl,on sufficient to initiate polymerization of the monomer at the temperature of the solution and the formation of the covalent bond, is gradually added. The polyolefin with a side-chain grafted thereto is thereafter separated from the solvent by volatilizing the solvent, preferably in a devo~iliung extruder. The graft polymer is then blended with a sùitable polyolefin such as polypropylene or polyethylene, and extruded into a desired shape.
*
)Ofi6 RACK~ROUN~ OF THF INVFNTION
Non-polar polyolefins, especially polypropylene and polyethylene and mixtures in various low-density, high-density, and linear low-density form, are major articles of commerce for a wide variety of uses.
Nevertheless, there exist speciqlty needs for which the marketplace has not provided a s~tisf~tory answer. Among these are to overcome the difficulty of thermoforming and processing of the polyolefin, especially unfilled, in a molten or semi-molten form (substantially above its melting point); the polymer tends to sag readily under its own weight because it o exhibits an undesirably low stiffness, and to form shapes of grossly non-uniform thicknesses upon thermoforming. Attempts to correct same by increasing the molecul~r weight lead to difficulties in processing the higher molecular weight polymer not encountered with the lower molecular weight grades.
For the jSO~ACt;C polymer of butene-1, known also as polybutylene, the low melting point has made difficult the crystallizing of the polymer after processing and obtaining the enhanced performance and handling properties crystallization imparts. S~tisfqctory nucleators have not appeared in the marketplace.
Means have also been sought to improve the toughness or impact slren,Jtl, of polypropyl~ne, for inslance. Use of copolymers or ethylene-propylene rubber modified polypropylene has improved toughness, but at the cost of even lower sliffl,ess values, and lower values of heat distortion res;s~ance. It would be desirable to combine impact pelf~.r-"ance of the copolymers with stiflness and heat distortion behavior of the hGIJlGpolylller polyprupylene resin.
Grafting of ",Gno",ers car~hle of vinyl polymerization, such as styrene, methyl methacrylate, and the like, onto polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymers, and 134~066 ethylene-propylene-diene terpolymers has been studied almost since the disoovery of routes to practical preparation of such backbones.
Grafting onto solid polymer by vapor-phase polymerization, by reaction in an extnuder, by peroxidation of the olefinic backbone, and grafting onto pendant double bonds are all routes which have been attempted.
There still exists a need for a route which allows for grafts of relatively high molecular weight, with relatively good grafting efficiency (i.e., lowered formation of unattached polymer molecules), freedom from gel, and a practical means for preparing and isolating the graft polymer in o an efficient and lower-cost manner.
Blends of two or more polymers have often been made, for example in attempts to combine desirable properties of the individual polymers into the blend, to seek unique properties in the blend, or to produce less costly polymer products by including less expensive or scrap polymers in th~ blend. CG",pali~le polymers tend to form blends that contain small do",ains of the individual polymers; in the case of ~miscible~ polymers these occur at the molecular scale, resulting in properties usually considered characteristic of a single polymer. These may include occurrence of a sTngle glass-transition temperature and optical clarity. Such blends are frequently termed ~alloys.~ Coi"pa~ible polymers that are not strictly miscible, as described above, nevertheless tend to form blends with p,upe,lies that approach those of the miscible blends. Such properties as tensile strength, which rely upon adhesion of the domains to om3 another, tend not to be degraded when compatible polymers are blended.
Unfortunately many polymers are poorly compatible with one another. Poor compatibility cannot necess~rily be predicted accurately for a given polymer ~,i"binalion, but in general it may be expected when non-polar polymers are blended with more polar polymers. Poor coi"palibility in a blend is apparent to those skilled in the art, and often 13~0066 evidences itself in poor tensile strength or other physical properties, espeaally when compared to the component polymers of the blend.
Mic..scop-c evidencs of poor compatibility may also be present, in the form of large, poorly adhered domains of one or more polymer components in a matrix of another polymer component of the blend.
More than one glass-transition temperature may be observed, and a blend of otherwise l-dnsparent polymers may be opaque because the domain sizes are large enough to scatter visible light.
Much research has been directed toward finding ways to increase o the compatibility of poorly compatible polymers when blended.
Appr(,acl.es that have been used include adding to the blend polymers which show compatibility with the other, mutually incompatible polymers; such add~d polymers act as a bridge or interface between the incompatible components, and often decrease domain size.
Chlorinated polyethybne has been used as such an additive polymer, especially in blends of polyolefins with other, poorly compatible polymers.
Graft polymers, as of incompatible polymers A onto B, are known to aid in blending po~rmers A and B. Such graft polymers may also serve to aid in blsnding other inc~n,pa~il,le polymers C and D, where A
and C are compatibll~ and B and D are compatible.
What has also been difficult to predict in polymer science is the extent to which such a graft polymer will be effective in enhancing desirable properties of the blend over those of the incompatible blend alone. Consequently, those skilled in the art have had to treat each combination of graft polymer and other co",ponent polymers of a given blend as a special ~ ase, and determine experimentally whether an . improve..,enl in such prupeities as tensile strength could be obtained by adding a specific graft polymer to a specific blend.
13~0066 pFI FVANT ART
U.S. Patent No. 4,094,927 describes copolymers of higher alkyl methacrylates with (meth)acrylic acid as melt strength additives, foam st~bili~ers, and pr~cEs~ing aids for polypropylene. Such polymers, however, are not fully compatible with polypropylene and the additive will tend to plate out and foul equipment during such operations as melt calendering.
U.S. Patent No. 4,409,345 describes polyolefin modified with a polymerizable unsaturated carboxylic ester in affording improved o processing of mixtur~s of polypropylene, high density polyethylene, and finely divided vegetable fibers. The patent appears only to demonstrate reinfor~i"ent by the fibers which are bonded to the polyolefin by the graft copolymer. All examples are limited to ~grafts" of maleic anhydride or acrylic acid, wherein the material grafted is of a molecular weight co,.esponding to a small number of monomer units.
South African Patent No. 826,440 describes "improved melt viscosity~ (higher melt viscosity under low shear conditions while retaining the low melt viscosily at high shear rheology behavior of the un".Gdi~led polypropylene) and improved thermoforming characteristics for blends of polypropylene with certain salts of acid-modified propylene polymers.
U.S. Patent No. 4,370,450 describes modification of polypropylene with polar vinyl monomers by polymerization in aqueous suspension containi~ a swelling agent at temperatures above 85~C
with a radical chain initiator having a half-life of at least 2 hours in the temperature range 80-135~C. The patent does not describe direct solution ~r~fling, stating such yields ~only relatively low degrees of grafting~. HydlocarLons are listed as examples of swelling agents.
~ 13~066 U.S. Patent No. 4,161,452 dsscribes only grafts of unsaturated carboxylic acids or anhydrides and esters of (meth)acrylic acid onto ethylene/propylene copolymers in solution in the presence of a free-radical initiator c~ls of hydrogen abstraction at temperatures between 60 and 220~C. An oil soluble polymer is required.
U.S. Patent No. 4,595,726 describes graft copolymers of C2-C6 alkyl methacrylates onto polypropylene via a solvent-free vapor-phase pol~",eri~dliGn wherein the molecular weight of the graft and the number of grafted chains are controlled to yield the desired (although undefined) length and number of chains for utility in adhesive applications between polypropylene and more polar substrates. The patent .,' scloses that similar grafts can be made from methyl methacrylate, but do not exhibit the desired adhesive properties. The patent requires polymerization bebw the softening point of polypropylene, which is not defined in their patent, which is known to be lowered by the presGnce of monomers, and for which no temperature higher than 1 40~C is exemplified, and in the absence of solvent. There is no indication or suqgestion that a relatively high molecular weight chain is covalently grafted to the polyolefin. Moreover, the radical flux ~eneral~l appears to be too high to form a high molecular weight, e.g.
greater than 20,000, chain.
U.S. Patent No. 4,692,992 describes grafting at temperatures between 60 and 160~C while maintaining the olefin polymer dissolved in a solvent which is a mixture of a hydrocarbon and a ketonic solvent, 7~ the grafted polymer pr~r~pit~';ng upon cooling the reacted mixture below 40~C. Re~ction conditions for achieving high molecu'~r weight or the ~anla~e in ~onducting the reaction in the presence only of a solvent of low chain t~nsfer activity are not ~~isclosed.
U.S. Patent No. 3.86~,~6~ only describes melting of polyolefins in an extnuder, followed by grafting of unsaturated acids to achieve ~ 1340066 ~improved rheology~ as defined in South African Patent No. 826440, supra.
U.S. Patent No. 3,886,227 disclQses (but does not exemplify for the esters) grafting of unsaturated acids and esters to form a material useful as a modifying agent for polypropylene. The grafting is conducted in an extn~der, and they also disclose that the molecular weight of ths bacl~L.one polypropylene polymer be lowered by degradation durins the gralling process, conducted at a temperature above 200~C. It describes blending with polypropylene and the resulting modification found, such as nucleation, lack of warpage on molding, and the like. Although improvement in heat distortion temperature is noted, there is no d;cclQsure of improved rheological performance at the temperatures required for thermoforming and the like.
Japanese Kokai 59-164347 describes grafts of unsaturated acids or their derivatives (including esters) at very iow graft levels (10-5 to 10-8 9 equivalents per gram of polyolefin), blends of the grafts with polyolefins, and their use in affecting surface tension in the molten state of the polyolsfin while not affecting high-shear viscosity, making the blends useful in, e.g. blow molding of bottles.
Kallitis et al., Fl Ir. Polymer J. . 27,117 (1987) describes ethylene-propylene polymers as nucleating agents for polybutylene. They do not describe or suggest the utility of the polypropylene/methacrylic grafts of this invention.
2~; Reike and Moore, in U. S. Patent No. 2,987,501, disclQse grafts of poly",er~ of vinyl monomers onto polyethylene or polypropylene by oxidizing the polyolefln with fuming nitric acid or nitrogen tetroxide, followed by heating the activated polyolefin with the vinyl monomer.
The reference exemplifies grafting methyl methacrylate onto polyethylene and polypropylene.
Japanese Kokai 223250/87 discloses compatibilizing a polyolefin and a polyamide using a reaction product of an unsaturated carboxylic acid or its derivative grafted onto a mixture of polyolefin and polyamide, that is, the reaction product is formed in the presence of a mixture of two or more polymers. The amount of acid or derivative reacted with the trunk polymers is less than 10%, and it is clear from the only examples present, which utilize unsaturated acids which do not homopolymerize, that what is attached or grafted are low-molecular-weight moieties,. They ~lisclose reaction conditions, including relatively low levels of unsaturated acid and relatively high levels of peroxide, which would lead one away from achieving the molecular weights of the grafted chains disclosed below as part of the present invention. A particular modifier disclosed by this reference, formed by reacting two non-polymerizable acids with a mixture of four tnunk polymers, affects the compatibility of the polyamide and polyolefin. However, the comparative data suggest that a reaction of the acids onto polypropylene alone is not an effective compatibilizer for the two resins, and shows that graft polymers of low levels of low molecular unsaturated acids or derivatives are not effective in compatibilizing polyamides with polyolefins.
Japanese Kokai 86040/87 directed to polymer adhesives, disclQses an olefin polymer adhesive modified with a carboxylic or carboxylic anhydride group, further reacted with a polyolefin having alcohol functionality, and still further rea~ed with an aromatic acid halide.
RolJtevin et al., in An~ewandl~ M~kromolekular Chemie. Vol. 162, page 175 (1988), disclose the pr~pardtiGn of a graft polymer of poly(methyl "-ell,acrylats) onto a polyethylene trunk by ozonQlysis of a low-density polyethylene followed by heating the activated polyethylene in the presence of methyl methacrylate. They disclose grafts of methyl 1~4û066 methacrylate having a number-average molecular weight up to 21400, and the use of such grafts as polymeric emulsifiers or compatibilizers for mixtures of low-density polyethylene and poly(vinyl chloride). They report that the compat~lbilized mixture has a distinct increase in the stress required to break it, and a decrease in the domain sizes in the blend.
They also report appr~ciable degradation of the polyethylene molecular weight when it is ozonized prior to grafting. This reference does not deal with higher molecu'~ weights, nor does it provide any indication that the graft polymer might be effective in reducing sag of a polyolefin matrix 0 polymer or otherwise imparting desirable rheological effects to a polymer.
Thus, the art has described means for preparing grafts of methyl methacrylate homo- and copolymers upon polyolefin substrates, but has not recognized the advantages of the polymerization process herein described for a rapid, ~fficient procluction of novel high molecular weight grafts without gel and with ease of product isolation. The art teaches that certain grafts may be blended with polyolefins, but has not recognized the unexrected utility of the novel graft polymers of this invention as having positive effects on both low-shear melt and solid-state properties,-0 e.speci-~ly with little or no effect on the high-shear performance. The art also has not recognized or identified the positive effects on sag resistance i"lpa,led by the present grafts.
It is thus an object of this invention to provide an improved process for the manufacture of novel graft polymers of methacrylic esters onto polyolefin subsl-dles. Another object is to provide graft copolymers of at least one chain of methacrylate polymer of relatively high molecular weight, i.e. at least ~0,000, onto a polyolefin homo- or copolymer subslldle. Yet another object is to provide such graft copolymers which serve as co"~p~tibil; ;r,~ agents for blends of polymers which are o otherwise poorly compatible. It is a further object to provide blends of the graR copolymer with a polyolefin matrix which exhibit improved physical performance in the melt, upon cooling, and in the sold state.
Further objects and advantages of this invention will appear as this specification progresses.
SUMMARY OF THF INVFNTION
Broadly, the aforesaid objects and advantages are accomplished by grafting onto a non-polar polyolefin trunk in solution, at least one chain which is of a polymer having a weight average molecular weight greater than about 20,000, and present in a weight ratio with the polyolefin of from about 1:9 to 4:1. The graft polymer is derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2 S C~CH3)COOR, where R may be alkyl, aryl, substituted or unslJbstitute~l and less than 20%, based on the total monomer weight, of an acrylic or styrenic monomer copolymerizable with the methacrylic ester. This is accomplished by adding the methacrylate monomers to a solution of the polyolefin together with an initiator which generates a conslant, low radical concent-dlion, or radical ~flux", at the solution - -temperature. These radicals initiate polymerization of the monomer and cause for"u~liGn of a covalent bond with the trunk.
The resulting copolymer product, hereinafter referred to as concenl~dte, may be blended with polyolefin either as a result of the manner by which it is made, or aRer it is made. It may be extruded into a desired shape either directly, or after pell~ti7~tion. In either case, the resulting l~l~nded product exhibits a relatively high tensile modulus and high sag r~sis~nce without an increase in melt viscosity, as compared ~ with similar un~.dn~l polymers, viz: polyolefins without a high molecular weight chain or chains covalently bonded thereto.
.,. .... . , .. " , . , . , .. ,, ,.~ .. .. .. ... .. ... ... ... . ...
13~00fi~
The concentrate may also be blended with other polymers than polyolefins, and particularly with mixtures of two or more polymers which are poorly compatible with one another, and which may or may not include polyolefins, to improve the compatibility of the resulting S mixture.
The invention also relates to a process of making such a copolymer having a relatively high weight-average molecular weight (Mw) polymer chain. Briefly, the process according to this invention involves dissolving or swelling the polyolefin in an inert hydrocarbon solvent, and heating to dissolve the polyolefin, i.e. at least about 1 40~C. While agitating the solution, a monomer is introduced, together with an initiator which generates a constant, low radical flux at the temperature of the solution; the radicals initiate polymerization of the monomer and formation of a covalent bond therewith on the polyolefin trunk. The reacted mixture may be allowed to solidify by removal of the solvent. The resultant product, the concentrate, consists of the polyolefin with the chain grafted thereto, unreacted polymer, i.e. polyolefin without the chain, and ungrated methacrylic ester polymer. It may be pelletized, blended with another polyolefin and extruded into desired shape. Alternatively the reaction mixture may be extruded directly in a devolatilizing extruder to volatilize the solvent and residual monomer, and thereafter blended with a polyolefin and extruded to form article in such form as sheets, tubes and the like.
According to one aspect of the present invention there is provided a graft copolymer capable of imparting to a polyolefin when blended therewith a relatively high tensile modulus and high resistance to sagging without increasing melt viscosity, the copolymer comprising:
13409~
(a) a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene), copolymers of said olefins with each other, and one or more copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic ester, and (meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and (b) at least one methacrylate chain grafted with a covalent bond to said trunk having a weight ratio with said trunk of from about 1:9 to about 4:1, said chain being a polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain having a weight average molecular weight of from about 20,000 to 200,000.
The present invention also provides a polymer blend comprising (a) a polyolefin; and (b) a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene), copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and ~meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted lla 1340~6b alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight-average molecular weight of from about 20,000 to 200,000, and ~eing present in a weight ratio with said trunk of from about 1:9 to about 4:1; said polyolefin (a) being the matrix for the blend.
The present invention further provides a process for preparing a graft copolymer concentrate capable of imparting to a polyolefin when blended therewith relatively high tensile modulus and high resistance to sagging without increasing the melt-viscosity, comprising the steps of:
(a) introducing a non-polar polyolefin selected from the group consisting of polypropylene, polyethylene, polybutylene, poly(4-methylpentene), copolymers of said olefins, and one or more copolymers of said olefins with one or more 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid into a reactor vessel containing an inert solvent, said polyolefin having a weight average molecular weight between about 50,000 and 1,000,000;
(b) heating the polyolefin mixture to a temperature at which the polyolefin dissolves;
(c) adding with agitation at least about 80%, based on the total monomer weight, of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl or substituted aryl or alkaryl and not more than about 20%
based on the total monomer weight of an acrylic or styrenic monomer copolymerizable with the methacrylic ester to the polyolefin solution in the reactor vessel;
llb 13~006~
(d) adding to the mixture in the reactor vessei an initiator which produces a low and constant radical flux for a time sufficient to produce a methacrylate chain polymer having a weight average molecular weight of between about 20,000 and 200,000 which S is covalently bonded to the polyolefin; and (e) removing the solvent to isolate the graft copolymer concentrate.
Extruded and molded products, optionally including various additives, formed from polymer blends as defined above in which the polyolefin constituent is polypropylene, are also provided by the present invention.
The foregoing aspects of the invention are also disclosed, and are claimed, in Canadian Patent Application No. 593,171 filed March 9, 1989, of which the present application is a divisional.
According to a further aspect of the present invention there is provided a method for improving the compatibility of a blend of one or more non-polar polymers with one or more polar polymers which comprises incorporating into the blend from about 0.2 to about 10 parts per hundred parts of the blend of a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene), copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, llc 134006~
substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight average molecular weight of from about 20,000 to 200,000, and being present in a weight ratio with said trunk of from about l :9 to about 4:1 .
The present invention still further provides a blend of one or more polar polymers with one or more non-polar polymers and a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene) copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight average molecular weight of from about 20,000 to 200,000, and being present in a weight ratio with said trunk of from about 1:9 to about 4:1, the compatibility of the blend being superior to that of a blend of the non-polar polymers and polar polymers in the absence of the graft copolymer.
lld 13 10û6fi DETAILED DESCRIPTION
In the following, LDPE is low-density polyethylene, usually branched, of density of about 0.91 to about 0.94 g/cc; HDPE is high-density polyethylene of a density above about 0.95 g/cc; LLPDE is linear low-density polyethylene of density of about 0.91 to about 0.95 g/cc;
EPDM includes rubber terpolymers of ethylene, propylene, and a non-lle 13~006~
conjugated diene monomer, such as 1,4-hexadiene or ethylidenenorbornene.
The term ~polar substrate~ or ~non-polar polymer, as used herein, is difficult to define in quantitative terms. By ~non-pola~ is meant polymers which are predominantly formed from monomer units of mono-or di-olefins. ~Polar~, as generally under:iloo(J in the polymer art, would refer to monomers or polymers which contain an oxygen, nitrogen, or sulfur-containing functionality. Thus, methyl methacrylate, acrylonitrile, and vinyl phenyl sulfone are ~polar~ monomers, whereas polypropylene is a ~non-polar~ polymer.
The polymers to be modified in the grafting process include the non-polar olefin polymers and copolymers. Included are polypropylene, polyethylene (HDPE, LDPE, and LLDPE), polybutylene, ethylene-propylene copolymers at all ratios of ethylene and propylene, EPDM
terpolymers at all ratios of ethylene and propylene and with diene monomer contents up to 10%, poly(l-butene), polymethylpentene, ethylene-vinyl acetale copolymers with vinyl acetate contents up to 25%, ethylene-methyl acrylate copolymers, ethylene-methyl methacrylate copolymers, and ethybne-ethyl acrylate copolymers. Also included are -mi-xtures of these polymers in all ratios.
Usable graft copolymers include those with ratios of polyolefin:acrylic polymer or copolymer that vary from 20:80 to 80:20.
The molQc~ r weight of the polyolefin polymer which forms the tnunk of the graft copolymer should be high enough to give a large amount of non-polar polymer when grafted, but low enough so that most of the graft copolymer has one acrylic polymer chain grafted to each polyolefin trunk chain. A polyolefin tnunk having a molecular weight of about 200,000-800,000 Mw is especi~lly preferred, but polyolefins having a molecular weight of about 50,000-200,000 can be used with some 13~1 0066 beneficial effect. In general, a graft copolymer imparts greater melt-rheology improvement to a high-."ol~c~ r-weight polyolefin. This is especi-"y true when the polyolefin tnunk of the graft copolymer is of relatively low molecular weight.
Melt flow rate (mfr) is well known to correlate well with weight-average molecular weight. The preferred range of mfr values for the polyolefin trunks used in preparing the graft copolymers of the present invention are from about 20 to about 0.6 9/10 minutes as measured by ASTM Standard Method D-1238.
o The preferred monomer is methyl methacrylate. As much as 100%
of this, or of other 2 to 4 carbon alkyl methacrylates, can be used. Up to 20% of high alkyl, such as dodecyl and the like, aryl, such as phenyl and the like, alkaryl, and such as benzyl and the like, and/or cycloalkyl, such as cyclohexyl and the like, ~"etl,aclylates can be used. In addilion, up to 20% (preferably less than 10%) of the f~l'owing monomers can be incGr~.oratecl with the methacrylate esters which form the major portion of the monomer: methac~lic acid, methacrylamide, hydroxyethyl methacrylate, hydroxypropyl methacrylate, alkoxyalkyl methacrylates, such as ethoxyethyl methacrylate and the like, alkylthioalkyl methacrylates, such as ethylthioethyl methacrylate and the like, methacrylamide, t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoprupyl methacrylamide, glycidyl methacrylate, methacryloxypropyltriethoxysilane, acrylate monomers (such as ethyl acrylate, butyl acrylate and the like), styrene, acrylonitrile, ~5 acrylamide, acrylic acid, acryloxypropionic acid, vinyl pyridine, andN-vinylpyrrolidone. In ~Jdilion, as much as 5% of maleic anhydride or itaconic acid may b~l~s~d. It is i.,.pG,l~nt that the chain transfer of the poly".eri7ins~ chains to its own polymer bc minimal relative to transfer with the polyolefin chain$ forthe efficient production of homogeneous non-gelled graft polymer in good yield.
13~006~
The molecular weight of the acrylic graft as measured by the weight average molecular weight of the ungrafted co-prepared acrylic polymer may be about 20,000 to 200,000. The preferred range is 30,000 to 150,000.
The process of graft polymerizing the monomer leads to the production of ungrafl~ and grafted material. The amount of grafted ",a~erial is in the range of 5% to 50% of the total acrylic polymer or copolymer produced The graft copolymer is prepared in a process that polymerizes the monomer in the presence of the non-polar polyolefin.
The process is conducted in a solvent which swells or dissolves the non-polar polymer. The solvent is also one that has no or low chain transfer ability. Examples include non-branched and branched aliphatic hydrocarbons, chloro~enzene, benzene, t-butylbenzene, anisole, cyclohexane, naph~l,as, and dibutyl ether. Preferably, the solvent is easy to remove by extrusion devolatilization, and therefore has a boiling point below 200~C, preferably below about 1 50~C. To avoid excessive -pressure, a boiling point above about 100~C is also preferred.
The final solilds content (which includes polyolefin and acrylic polymer) depends on the viscosity and the ability to mix well. The 0 practical limits are 20% to 70% but the solids content can be as high as is consistent with good mixing for economy. Preferably, the solids content falls in the range of about 35% to about 60%.
A gradual addition or multicharge addition of the monomer is preferred. Optionally, the monomer charge need not be the same throughout, for exampb, the last 0-20% may contain all of the monomer used in minor amount to concenl-d~e that monomer in one portion of the polymer.
The temperature during the polymerization can be in the range 110 to 200~C but the p,~fer.~d range is 130 to 1 75~C. Especially ~ . , ~" , ~ .
134 006b preferred is 145 to 1 60~C. The pressure can be atmospheric to superatmospheric, or as high as 2100 kPa or whatever is necess~ry to keep the reaction mixture in the liquid phase at the polymerization temperature.
The unreacted monomer concentration should be kept low during the reaction. This is controlled by balancing the radical flux and the monomer teed cohdilions.
For polymerization, oil-soluble thermal free-radical initiators are used. Those that work in this process are those with a one hour half life o at about 60~ to about 200~C. The preferred ones have a one hour half life in the range 90 to 170~C. Suitable free radical initiators include peroxy initiators such as t-butyl peroxypivalate, lauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethyl hexanoate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, acetyl peroxide, succinic acid peroxide, t-butyl psr~.,1uate, benzyl peroxide, t-butyl peroxyisobutyrate, t-butyl peroxymaleic acid, I-hydroxy-l-hydroperoxydicyclohexyl peroxide, 1 ,I-bis(t-butylperoxy)-3,3,~trimethylcyclohexane, t-butyl peroxycrotonate, 2,2-bis(t-butylperoxybutane), t-butylperoxy isopropyl carbonate, 2,5-dimethyl-2,5-bis(benzoylperoxy)-hexane, t-butyl peracetate, methyl ethyl ~o ketone peroxide, di-t-butyl diperoxypl,~ ldle, t-butyl perbenzoate, dicumyl peroxide, 2,5,dimethyl-2,5-di(t-butylperoxy)hexane, 2,4-pentanedione peroxide, di-t-butyl peroxide, 2,5,-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di(hydroperoxy)hexane. t-butyl hydroperoxide, t-butyl cumyl peroxide, p-menthane hydroperoxide and ~o-bis-isobutyronitrile.
The initiator is introduced together with the monomer during the poly",eri~dt;on in a manner to maintain a fairly cor,slanl radical flux during most of the polymerization. This is done to achieve the correct 1340~66 high moleeul~r weight, a high graft efficiency, the desired molecular weight distribution, and treedom from gel.
Radical flux can be defined as the calculated rate of formation of free r~dic~lc~ expressed in equivalent of radicals per liter per minute.
While not being capable of being measured experimentally, this may be ~cul~ted from the known rate of decomposition of the free radical initiator present at any time. and its instantaneous concentration.
Decomposition rates for initiators are determined from published literature, and the conoentration is either a known constant, as in continuous feed of initiator, or can be calculated (for a single charge of initiator) from the known decomposition rate constant and the time elapsed since feed.
Good results are achieved when a uniform radical flux is maintained and the radkal flux is calcu~ted to be in the range 0.00001 to 0.0005 equivalents of radicals per liter per minute. The preferred range is 0.00002 to 0.0002 equivalents of radicals per liter per minute.
The radical flux is dependent on the specific initiator utilized, its concentration and rate of decomposition, and the reaction temperature chosen. The rate of Jeco",posilion can be found in t~hu~ted data, such as in ~The PolYmQr H~ll.ook', 2nd Edition, ed. Brandn~p and Imr~ergut, Wiley and Sons, New York (197~), or provided by the manufacturer.
Even if the exact rate c~"s~nl at the te",perdl~Jre of interest is not known, often activation ener~ies are s~ppl ed from which the rate can be celcul~ted. The radical flux is:
Radical flux = 2(kd)(60)(1) where kd is that rate ¢onsla,l~ for decoi"posilion of the particular initiator in units of inverse secon.Js, and I the concentration of the ir.itialor in moUliter. In a batch reaction, I steadily decreases from IO. the initial charge, and the radical flux is not conslant. When initiator is continuously 13~00t;~
fed, a r~plcul~tion must be made to determine the instantaneous concenlr~ion of initiator, but the value is much more constant than in a batch r~ac~ion, espec;~y with careful control of initiator feed.
The process may be run in a semi-continuous or continuous manner. Monomer, solvent, and initiator may be added by means similar to those described above. Polymer may be separately dissolved in solvent and added at a rate essentially equivalent to that of product removal, or polymer may be melted and added as a solid to the reaction by means of an extruder.
ARer the polyrn~ alion, a hold time may be used. Then the mixture is devolatilized to remove solvent and any unreacted monomer.
Acceptabls devolatilizing devices include a devolatilizing extruder, a rotary film evaporator, or any other convenient stripping device as known in the art. The poly."e,~tiGn reaction mixture may be conveyed to the devolatilization apparatus as a batch or continuously.
Prior to, during, or aRer the devolatilization step, appropriate additives may be admixed into the sraR copolymer solution/suspension which are desired to be present in the isolated graR copolymer. If such additives do not affect the grafting reaction, they may be added prior to, during, or after the polymerization proc~ss. Such additives may also be added when the graR copolymer is blended with the matrix polymer.
Such additives may indude st~hili~ers against light or heat, such as benzo~ oles, hindered amines, alkyl polysulfides such as dialkyl disulfides, and the like, lubricants, or plasticizers; flame retardants; and ~5 the like. rlef6rleJ is the aclJi~ion of a disulfida, such as di-n-dodecyl disu!fide or di-t~16.,-yl disulfide and the like at levels between about 0.001% to about 0.05% by weight of graft polymer, based on the wsight of graR copoly.l-er plus matrix polymer, to slabi' ~e the acrylic portion of the graR copolymer against thermal degradation during melt processing while admixing into the matrix or blending and extruding.
, ... . , . ",; ", .... . ... . .
- 134006~
A second class of stabilizer is the tris(polyalkylhydroxybenzyl)-s-triazinetriones. rlef~, .ad is tris-(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-(1H, 3H, 5H)-trione, at levels from about 0.001 to about 0.1%
by weight, based on the total polymer weight.
Stability may also be imparted to the acrylic portion of the graft copolymer by including an alkylthioalkyl (meth)acrylate, preferably ethylthioethyl ,netl,ac~ylate, with the acrylic monomer or monomers during the graft polymerization.
The product is then isolated by stranding, cooling, chopping, o drying, and bagging, or other known collection techniques.
The polyolefin and the graft copolymer concentrate may be blended by mixing the dry feed materials and extruding either directly to form a film, sheet or the like, or by collecting the blend and reprocessing it into the Jesi~ed article, or by adding the polyolefin in the course of the devolatilization.
Polyolefins are often produced with one or more stabilizers to prevent degradation of the polymer appearance or physical properties during processing and/or end use. Such st~bili~ers may include metal salts such as metal stearates, which act as acid acceptors, hindered ~ phenols, which act as anti-oxidants, and sulfur-containing organic esters or derivatives, added as heat st~bili~ers. Examples of such additives, which are usually prupliatary to the supplier, are metal stearates, 2,6-dimethylpt.snolic compounds, and ll. ~d;~sters of long-chain alcohols.
Polyolefins may also contain light st~hi~i~ers, such as hindered amines, benzot,ia~oles, and the like. All of the polyolefins used in the present examples are thought to contain small amounts of these proprietary ct?~ srs.
One way to specify the blend composition is that at least about 0.2% of the total formulation (polyolefin plus graft copolymer) should be 1340U6~
chemically grafted acrylic polymer or copolymer within the molecular weight limits specitied. The maximum amount is about 10% gratted acrylic polymer, with up to about 5% grafted acrylic polymer being preferred tor cost optimization and opti~ alion of most properties of the blend.
Optionally, the blend of concentrate and polyolefin may be further modified by the introduction of fillers, both inorganic and organic, fibers, impact modifiers, colorants, stabilizers, flame retardants, andlor blowing agents.
o Blowing agents may be gases, such as nitrogen or carbon dioxide, admixed with the polymer melt in the extruder and allowed to expand upon extrusion. More often, blowing agents are solids which liberate gases, usually nitrogen, at a specific melt temperature, and which are mixed into the melt, or blended from a pre-compoundsd mixture of the blowing agent disp~r~ed in a polymeric matrix. The melt temperatures for the polyolefins are typically in the range of about 200 to about 230~C, although other temperatures may be used, depending on the specific blowing agent. Solid blowing agents include azo compounds such as ~o~';c~rbonamides, ~oisobutyronitriles, hydroazo compounds, or compounds containing the nitroso group.
The blend of the graft copolymer and polyolefin is useful in thermoforming, film malcing (especially blowing and extruding), blow molding, fiber spinning, acid and basic dyeing, foaming, extrusion (sheet, pipe, and profile), coextrusion (multilayer film, sheet, preforms, and pa,isons, with or without the use of tie layers), hot melt adhesives, calendering, and extrusion coating (for the preparation of polymer~fabric, carpet, foil, and othsr mu~ti'ayar constructions). Such graft copolymers, espec;~lly with small amounts ot copolymerized acid functionality, are useful when blended with polyolefins for Tmproved printability. The grafts 134006~
themselves may be used as tie layers be~/eon otherwise incompatible polymers.
In extrusion, the graft copolymer is useful, especially with LLDPE, at red~ction of melt fracture without an effect on the melt flow rate. Uniike the additives of U.S. Patent No. 4,094,297, the present additives do not plate out when the modified polyolefin is extruded for extended times.
When polypropybne is modified with the graft copolymers of the present invention, it may be employed in the manufacture of many useful objects, such as extn~sion- or injection-blown bottles for packaging of o foodstuffs, aqueous solutions such as intravenous feeds, hot-filled items such as ketchup, or extruded articles in profile form such as clips, scrapers, window and door casings and the like. The foamed articles may be used as substitutes for wood in moldings, for packaging materials, for insulation or sound-deadening materials, for food containers, and other rigid-article app' ~'ions. Films may be used in many protective or wrapping appl ~tions, such as for food packaging, blister packaging of consumer goods, and the like.
The graft copolymers of the present invention are useful in preparing polyolefin fibers, espec;ally polypropylene fibers; they are especially useful when the graft copolymer is formed from a polypropylene trunk. Polypropylene is relatively easy to process into fibers having high strength and toughness.
Polypropylene fibers show certain deficiencies which include difficulty in dyeing and poor long-term dimensional stability. Grafts ~5 containing fun~ional sites capable of accepting dye may be prepared bythe present prucess-by incGr~.or~ting low levels ot dye-accepting monomers, such as .,.~lha~rylic acid, din,elhylaminoethyl methacrylate, N-vinylpyridine, and the like. The improved sag resistance noted for the 134006~
present graft polymers in a polypropylene matrix should correspond to improvements in creep resistance of the fiber.
Polypropylene rnay be formed into fibers by slitting tape from extruded film to form large-denier, coarse fibers, by extruding monofilaments into lar~e-denier fibers with a controlled cross-sectional size, or by extruding multifilaments through a spinnerette to produce bundles of small-denier fibers. In all cases, the fibers may be draw-textured. As an example, small-denier polypropylene fiber bundles may be extruded from a 25.4-mm, singls-screw extruder having a screw o length-to-diameter ratio of 24:1, such as that supplied by Killion Extruders Corp. of Cedar Grove, New Jersey and equipped with a static mixer, metering pump and spinnerette assembly with multiple orifices.
Using such equipment the extruded polypropylene would be passed thought a cooling bath and then over a series of godets (metal rolls with heating or cooling capability) to orient the polymer or quench existing orientation.
Polypropylene fibers may be used for, among other things, strapping, netting (including fish nets), slit tape, rope, twine, bags, carpet backing, foamed ribbon, upholstery, russ, pond liners, awnings, ~0 sv~;-"---ing-pool covers, tarpaulins, lawn-furniture webbing, shades, bristles, sutures, c;gar~tle filters, nonwoven fabrics, such as for tea bags, bed sheets, banJages, diaper liners and the like, and for doll hair, apparel and the like.
The graft copolymer of the present invention may also be used to improve the compatibility of polymers in blends where they would otherwise be poorly c~i),patible. The graft copolymer is incorporated into such blends, preferabiy at levels of from about 0.2 to about 10 %, p~,afe,~bly from about 0.5 to about 5%, and more preferably from about 0.8 to about 2.5%, to ach ~ve the desired improvement in co,-,~.alibTlity.
0 Higher levels of the graft copolymer may be used, but increases above 13~006~
the preferred level generally show only small improvements in compatibility.
As noted above, compatibility is not easily predicted. As a general rule non-polar polymers are poorly compatible with more polar polymers, but poorly compatible blends may also be found experimentally among polar-polar or non-polar-non-polar blends. Examples of the non-polar polymers are olefinic polymers such as high- and low-density polyethylene and linear low-density polyethylene, polypropylene including atactic polypropylene, poly-1-butene, poly-iso-butylene, ethylene-propylene rubber, ethylene-acrylic acid copolymer, ethylene-propylene-diene terpolymer rubber, ethylene-vinyl acetate copolymer, poly (ethylene-propylene), polymethylpentenes, and ionomers such as polymers of ethylene with metal-salt-neutralized acrylic acid.
Relatively more polar polymers, called polar polymers for the purposes of this clisclQsure, include acrylonitrile-butadiene-styrene polymer, acetal polymers, polyarylates, acrylic-styrene copolymers, acrylonitrile-styrene-acrylic polymers, acrylonitrile-styrene polymers modified with ethylene-propylene rubber, cellulosics, polyester-polyether block copolymers, polyesters such as polybutylene terephll,alate and polyethylene terephtl,alate, and includin~ liquid-crystal polyesters, polyetheramides, polyetheretherketones, polyetherimides, polyethersulfones, ethylene-vinyl alcohol copolymers, polyvinyl chloride, ch!orinated polyvinyl chloride, polyvinylidene chloride and fluoride, styrene polymers such as polystyrene, high-impact polystyrene, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-maleic anhydride copolymers, alkyl-substituted styrenes copolymerized with styrene alone or witl~ ~he additional ",GnGI"ers listed for styrene, polyphenylene ether, polyphenylene suffide, polysulfone, polyurethane, polyamides, i.e., nylons such as nylon 6, nylon 6-6, nylon 6-9, nylon 6-10, nylon 6-12, nylon 11, nylon 12, amorphous nylons, polyamideimide, .. . . . ~ . . . O
13~006fi polycaprolactone, polyglutarimide, poly(methyl methacrylate), other C1 to C8 poly(alkyl (meth)acrylates) and polycarbonates. The acrylic polymers referred to above are polymers containing at least 50 weight percent, and preferably at least 80 weight percent, of mers of acrylic acid and/or methacrylic acid (referred to collectively as (meth)acrylic acid) or their esters, preferably their alkyl esters and more preferably their alkyl esters in which the alkyl group contains from one to eight, preferably one to four, carbon atoms. The remaining mers are those from one or more monomers copolymerizable with-the (meth)acrylic acid or ester by free-o radical polymerization, preferably vinylaromatic monomers, vinyl esters or vinyl nitriles, and more preferably mers of styrene or ac~lonitrile.
In the examples which follow, polymer concentrates and polymer blends were tested using standard procedures which are summarized below.
Unr~7acted ,nûnomer in the reaction mixture prior to solvent removal or subse~uent to extnJder devolatilization was determined using a gas chromatographic technique.
The coll~cted volatiles were analyzed by gas chromatography on a 25 meter CP wax 57 CB wall coated open tubular fused silica column O at 40~C. A co"",a-ison of the major signals for the solvent with the MMA
signal was used to det~rmine the amount of residual monomer in the reactor and ll,er~fore give a measure of conversion immediately. A more accurate measure of conversion was obtained by a C,H,O analysis of the graft copolymer. The carbon content was used to calculate EPDM or polypropylene content by inte-l.olating between the carbon content of EPDM (85.49%) or,~ol~,crupylene (85.87%) and acrylic polymer (60.6%).
The graft copGly..,ers are analyzed by solvent exl,d~iGn to remove the ungr~led (meth)ac ylic portion, whose ",ols~r weight is then determined by gel permeation chromatographic techniques. A technique for separating the graft copolymer from ungrafted polyolefin is not available. For concentrates, 0.8-1.3 ~ of polymer was placed in a centrifuge tube with 17 cm3 of xylene. The tube was shaken overnight.
Then the tube was placed in an oil bath set at 1 38~C. The tubes were periodically taken from the bath and shaken until all polymer had dissolved. The fact that all dissolved indicates that no crosslinking occurred. The tubes were cooled during which time the polypropylene conlaining substances pre.,ipit~le. Then the tubes were centrifuged at 15,000 rpm for 2 hours and the xylene solution was removed with care not to remove any floats. The molecular weight of the acrylic polymer extracted by the xylene was cleter",ined by gel permeation chromaloyraphy. The procedure was repeated on the resulting plug to extract addil;Gnal (meth)acrylate. The value labelled % graft is the portion of the (meth)acrylic polymer forrned which remains with the polyolefin plug after repeated exlldctiGn. The c~i"pGsilion is determined from the carbon analysis of this plu~.
The polypropylene concentrate and any additives were blended in the melt on a 7.6 cm by 17.8 cm electric mill with a minimum gap of 3.8 mm set at 1 90~C. Onc~ the material had fluxed, it was mixed an ad.JitiGnal 3 minutes. Higher temperatures were used for higher viscosity materials (tor example, mfrs0.5-2 material was done at 195-21 0~C).
While still hot, the "~alerial was either compression molded or cut into small chunks (about 1-2 cm in each dimension) for granulation (5 mm screen). It is of inleresl that the additives of the present invention contribute to easy release from hot metal surfaces, such as mill rolls, Jl laako Rheocord'bowls, etc.
Millin~ of polyethylene was done in a similar manner except that the HDPE blends wer~ milled at 200~C and the LLDPE blends were milled at 170~C.
* Trademark 13400fi~
A 2.5 cm Killion extruder was used for extrusion blending. A two stage screw was used at 150 rpm with all three zones set for 190~C. The one-strand die was also set at the same te",pe,~dl.lre. A vacuum vent was used. The s~rand was cooled in water and pelletized. The extrusion 7 rate was 4.5 kg per hour.
Melt blending in a"Haake Rheocord"(a batch melt mixer) was done on 50 9 samples at 190~C or at 210~C and 100 rpm in air. Mixing was continued for three minutes after peak torque was reached. Sample size was 50 grams.
The polyolefin blends were compression molded in an electrically heated Carver press 15 x 15 cm o~'Farrel'press 30.5 x 30.5 cm. The samples were molded between aluminum plates with an appropriate spacer to provide the r~quired thickness 0.25-3.8 mm. In one method the hot melt was taken directly from the mill roll and placed between two aluminum sheets. This was then placed in the press set at 1 90~C and pressed at high pressure (68-91 metric tonnes for the Farrel ~ress and 6820 kg for the"Carverpress). After three minutes the mold was placed in an unheated press at high pressure for three minutes. In the other proceJure, granulated rnaterial or pellets pro~uced from an extrusion ~o Haake or milling operation were dried and then compression n,olded.
The pr~ce~ure used was the same as for molding a melt except that a 5 minute preheat was us~d while ",ain~aining a slight pressure on the press. This was followed by the high pressure molding in the hot and cold pr~sses. A hot press of 1 90~C was usually sufficient for mfr=4 polypropylenes but hi~her viscosity polypropylenes would split during sag testing unless high~r ~"olJing temperatures were used (195-210~C).
Polyethylene was rllDlJeJ in a simJlar manner except that HDPE
was ~"olde~l at 170~C and LLDPE at 150~C.
* Trademark (each instance) 13~01~66 Injection molding of polypropylene was performed on a Newbury *
injection molding machine in an ASTM tamily mold. Material to be molded was dried for 16 hours at 60~C. The first barrel zone was set for 204~C, and the other two barrel zones and the nozzle were set for 21 8~C.
The ram time was set for 3 seconds and the cycle of 15 seconds for injection and 45 seconds overall was used. The injection pressure was 2100 kPa and the back pressure was 690 kPa. The screw speed was 100 rpm. Both mold platens were set for 60~C.
The sag tests are performed on a cGnlpression molded sheet 10 x 0 10 x 0.15 cm. This sheet was clamped in a frame with a 7.6-cm-square opening. There were metal rulers ~tlached to the front and back of the frame for use in measuring sag. The frame and sheet were placed in a hot, forced air oven (typically at 190~C). The amount of sag of the center of the sheet was then recorded as a function of time. Typically, the sag was first r~cG,Jed at 2.5 cm but for slow sag~;og materials sags as low as 16 mm were recorded. Data was recGnlsd up to 10.2 cm of sag or for 30 minutes, whichever oceurred first.
The terrn ~slope~ refers to the slope of a plot of the natural logarithm of the sag in centimeters versus time, resulting in a straight line.
A high slope indicates that the material sags quickly while a low slope indicates that it sags slowly. The advantage of comparing slopes in this manner is that it eliminates any di~erenc~s in oven cooling when the sample is introduced (due to differences in the time the oven is open, room te",peratures, etc.).
Crude thel",o~orl~,ing was done in the laboratory to illustrate this melt sl~n~t, effect. A sheet of polypropylene or modified polypropylene was heated in a forced air oven at 1 90~C, removed from the oven, placed over a female mold, and subjected to vacuum.
* Trademark '' 1~4006~
The capillary flow data were measured on a Sieglaff McKelvey rheometer. The flows were recorded at ten shear rates (1 to 100-reciprocal seconds) at each temperature. The data was fit to the power law, i.e., viscosity=k(temperature)X(shear rate)Y, and the values at 1 and 1000 reciprocal seconds were calculated from this best fit equation. The parallel plate viscosity refers to measurements on the"Rheometrics"*
Dynamic Spectrometer, recorded at a strain of 5%.
Differential scanning calorimeter (DSC) measurements of melting and nucleation were performed on a duPont instrument. A value of 59 caUg was used for the heat of cryst~ tion and per cent crystallinity was corrected for the presence of the melt additive. The nuclsetion temperature was measured in an experiment in which the polypropylene was melted at 200~C for 2 minutes and then cooled at 1 0~C/min. The temperature at which peak cryst~ tion occurred is called the nucleation temperatur~. The isothermal crystallization time was recorded by cooling the molten polypropylene quickly to 1 27~C and the exotherm recorded with time.
The physical properties of the polypropylene homopolymer and ~medium impact~ copolymer are determined on extruded and injection molded samples, although similar results have been observed in milled and compression molded samples. In certain examples below are described speci~ ed equipment for preparing foamed shset, rod or profile, extnuded rod or tubing, fibers, cast film, monoaxially oriented and biaxially oriented film, and injection blow-molded bottles or hollow containers.
The examples are intended to illustrate the present invention and not to limit it except as it is limited by the claims. All percentages are by weight unless otherwise specified and all reagents are of good commercial quality unbss otherwise specified.
* Trad~nark 13~0366 This example illustrates preparation of a Graft Copolymer (GCP) of Polypropylene (PP), Methyl Methacrylate (MMA) and Ethyl Acrylate (EA).
A polypropylene-acrylic graft copolymer is made by polymerizing a 5% ethyl acrylate (EA) - 95% methyl methacrylate (MMA) monomer mixture in the presdn~3 of polypropylene (weight ratio of polypropylene:monomer_ 0.67:1). Radicals are generated from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00010 moles per liter per minute (radical flux). Monomer and initiator are fed over 60 minutes and the theoretical (100% conversion) solids at the end of the reaction is 55%.
A 6.6 liter reactor e~ipped with a double he~ical agitator (115 rpm) was charged with 1780 9 of an inert hydrocarbon solvent mixture of 2-methylalkanes havin~ 6-12 C-atoms and 880 ~3 polypropylene (mfr=4) and heatsd to 1 75~C. After 2 hours the te",perdl-Jre was decreased to 1 55~C and ths batch was stirred for 1 additional hour. Over a two minute period two solutions were added. The first consisted of 1.04 9 of di-t-butyl peroxide in 21 9 ot the hy.Jroca~6Gn solvent. The second consisted of 0.06 g of di-t-butyl peroxide in 2.1 9 of sthyl acrylate and 42 9 of methyl ",ell,ac.ylate. For the next 58 minut~s at the same feed rate a feed of 1.87 9 ot di-t-butyl psroxide and 62 9 of sthyl acrylate in 1215 9 of methyl methacrylats was added at the same feed rate as the second feed. This feed schedule results in a radical flux of 0.00010 during the feed time.
After the feed was complete the reaction was held at 1 55~C for an additional 15 minutes. Then it was devolalilized by passing through a 30-mm"Wem~r-l~ g derer'~Ktruder with two vacuum vents at 200-250~C.
The conce~ltldle product (concenl,dte) is a mixture wherein the elemental analysis showed that the composition is 56% (meth)acrylate. Extractive results showsd 15.9% of the polymerized (meth)acrylic monomers were grafted, and ths Mw of ths (meth)acrylic polymer was 91,300. The * Trademark 1~40!~f~6 concentrate may be blended with other thermoplastic polymers such as polypropylene.
The following Table shows the efficiency of the above concentrate blended at different levels in improving sag resistance of a polypropylene homopolymer having a melt flow rate (mfr=4) of four.
T~RI F I
Wt. % of sag sample sag at concentrate slope, thickness 17 min time to in blend min-1 ( mm) (cm) sa~ 2.5cm 0 0.18 1.75 2.29 39 min 1.5 0.12 1.45 6.10 6.0 2.5 0.12 1.70 4.57 6.8 3.3 0.06 1.78 3.05 11.4 5.0 0.045 1.73 1.27 13.1 7.5 0.030 1.75 1.02 FXAMPI FS ~ - 51 A poly,urupylene acrylic graft copolymer i5 made by polyme~zing a 5% ethyl acrylate (EA,l - 95% methyl methacrylate (MMA) monomer mixture in the presence of polypropylene (weight ratio of polypropylens.,nonoi"er = 0.67:1). Radicals were generated from di-tertiary-butyl peruxic~e (DTBPO) at the rate of 0.00010 moles per liter per minute (radical flux). Monomer and initiator were fed over 60 minutes and the II eo,~t;cal (100% conversion) solids at the end of the reaction was 52.5Yo.
A 6.6 liter reactor equipped with a pitched-blade turbine ~git~or (375 rpm) was charg~l with 1880 9 hydrocarbon solvent and 840 9 13~006~
polypropylene and heated to 1 55~C. The mixture was stirred for 3 hours. Over a two minute period two solutions were added. The first consisled of 1.06 9 of di-t-butyl per~xiJ~ in 21 9 of hydrocarbon solvent, as in Example 1. The second consisted of 0.06 9 of di-t-butyl peroxide in 2.1 g of ethyl acrylate and 40 9 of methyl methacrylate. Forthe next 58 minutes a feed of 1.87 9 of di-t-butyl peroxide and 61 9 of ethyl acrylate in 1157 9 of methyl methacrylate was added at the same feed rate as the second feed. This feed schedule should produce a radical flux of 0.00010 during the feed time. After the feed was complete, the reaction was held at 1 70~C for an additional 15 minutes. Then it was devolatilized by passing through a 30 rnm'~lVerner-Pfleiderel"extruder with vacuum vents at 200-250~C. The concentrate showed that the co",posilion is 51% acrylate.
Additional polypropylene-acrylic graft copolymers (Examples 2-51 ) were p~pare.J by the pr~cedure of this Example and evaluated as 3.5% blends in polypropylene (mfr=4) as melt strength additives. The following Table illustrates the polymerization conditions for the concentrate and the p~rcent acrylic polymer present in the concenl-~le with the sag ~s;slancc of the blend with the polypropylene.
In the following Table ll, DTBPO is di(t-butyl)peroxide, TBPB is t-butyl perLen Gale, and DDBH is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.
* Tradel[ ark 1~40~fi~
TaRI F li sag % feed rad- %EA
slope acrylic init- solids polymer time, ical in Ex. ~in-1 in ~nc i~QC % ternp.~C m~ flux MMA
Con~ 0.15-0.18 -- ---- ---- ------ --- ---- ---0.03-0.05 56 DTBPO 55 155 60 0.00010 5 2 0.06 51 DTBPO 52.5 155 60 0.00010 5 3 0.06 52 DTBPO 55 155 60 0.00010 5 4 0.045 55 DTBPO 55 150 60 0.00010 5 0.08 57 DTBPO 55 145 60 0.00010 5 6 0.05 57 DTBPO 57 150 60 0.00010 5 7 0.10 49 DTBPO 55 150 60 0.00007 5 8 0.06 53 DTBPO 55 150 60 0.00015 5 9 0.06 55 DTBPO 55 150 60 0.00010 10 0.11 53 DTBPO 55 150 60 0.00010 0 11 0.056 48 DTBPO 55 155 60 0.00010 10 12 0.07 51 DTBPO 50 150 60 0.00010 5 13 0.11 58 DTBPO 55 145 120 0.00007 5 14 0.10 57 TBPB 55 145 120 0.00007 5 0.09 56 TBPB 55 150 120 0.00010 5 16 0.12 54 TBPB 55 150 120 0.00007 5 17 0.13 55 TBPB 55 150 120 0.00015 5 18 0.06 55 DTBPO 55 150 120 0.00007 5 19 0.06 49 TBPB 55 150 60 0.00010 5 0.10 51 TBPB 55 150 120 0.00010 5 21 0.14 57 TBPB 56 150 120 0.00010 5 22 0.13 5~ TBPB 55 150 60 0.00010 5 23 0.15 55 TBPB 55 150 120 0.00010 0 24 0.15 56 DDBH 55 150 120 0.00010 5 1 3 ~ O ~ fi b TARI F ll (continued) sag ~/O feed rad- %EA
slope acrylic init-solids polymer time, ical in Ex. ~3i~ in c~nc j~Q~ % temD.~C min fl~ MMA
0.14 57 TBPB 55 150 120 0.00015 5 26 0.09 51 TBPB 55 150 60 0.00010 5 27 0.15 54 DDBH 55 150 120 o.ooo10 o 28 0.11 51 DDBH 55 155 120 0.00010 5 29 0.10 53 DTBPO 50 150 120 0.00007 5 0.10 54 DTBPO 50 150 120 0.00005 5 31 0.15 53 DTBPO 50 150 120 0.00005 5 32 0.10 51 DTBPO 55 150 120 0.00007 5 33 0.12 55 TBPB 55 150 120 0.00007 5 34 0.18 55 DDBH 55 150 120 0.00007 5 0.07 53 DTBPO 55 150 120 0.00005 5 36 0.09 51 DTBPO 55 150 120 0.00010 5 37 0.14 51 TBPB 55 150 120 0.00005 5 38 0.10 37 DTBPO 55 155 60 0.00010 5 39 0.11 43 DTBPO 55 155 120 0.00007 5 0.08 48 DTBPO 55 155 120 0.00005 5 41 0.10 47 DTBPO 55 155 120 0.00007 5 42 0.07 48 DTBPO 55 155 60 0.00010 5 43 0.10 43 DTBPO 55 155 120 0.00005 5 44 0.10 50 DTBPO 55 155 120 0.00007 5 0.10 54 DTBPO 55 t 50 120 0.00010 5 46 0.10 54 DTBPO 55 150 120 0.00007 5 47 0.07 54 DTBPO 55 150 120 0.00005 5 48 0.08 56 DTBPO 55 150 120 0.00007 5 49 0.08 55 DTBPO 55 145 120 0.00007 5 TABlFll(co~inued) " ,"" , , .. ~ . ,. ~ . ~ .. .. .. .... . . .. . . . . .
13~0~6~
sag % feed rad- %EA
slope acrylic init- solids polymer time, ical in Ex. min-~ in eonc I~QC . % temp.~C m~ f!~ MMA
0.09 56 DTBPO 55 145 120 0.00005 5 51 0.08 55 DTBPO 55 145 120 0.00010 5 Control = PP with no concentldle The r~lclJl~ted percent of grafted acrylic polymer and the molecular weight (Mw) of ungrafted acrylic material are tabulated below in Table lll on certain samples where the ungrafted acrylic polymer was separated from the concentrate by extraction.
T~RI F 111 % Acrylic Polymer Fx~m~le Gr~fted to PP ~
2 12.3 107,000 10.6 119,000 11 29.8 71,800 14.8 . 43~000 46 10.7 62,600 47 21.7 87,300 Note: (Mw = weight average molecular weight) ~ This example shows a larger seale prepardlion of a polypropylene-acrylie ~raît copolymer made by poly...6rl~ing a 5% ethyl aerylate (EA) - 95%
methyl mt~hacryla~e (MMA) monomer mixture in the pr~senee of polypropylene (weight ratio of polypropylene:monomer . 0.67:1). Fl~di&~ls were generated 1~4006~
from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.000065 moles per liter per minute (radical flux). Monomer and initiator were fed over 122 minutes and the theoretical (100% conversion) solids at the end of the reaction was 47%.
A 380 liter reactor equipped with a back-slope turbine agitator was charged with 102.3 kg of the hydrocarbon solvent and 36.4 kg of mfr=4 polypropylene homopolymer and heated to 150~C over 4 hours. Two solutions were added over a twenty minute period. The first consisted of 82 9 of di-tertiary-butyl peroxide in 826 9 of the hydrocarbon solvsnt. The second consisted of 454 g of EA and 8.6 kg of MMA. Addition of the first solution was then continuedo at a lower rate to feed an additional 82 g of di-tertiary-butyl peroxide and 826 9 of the hydrocarbon solvent over 90 minutes. At the same time the monomer addition of 2.3 kg of EA and 47.5 kg of MMA was continued over 102 minutes (ending 12 minutes aft~r the initiator feed had finished). The reaction was heldat 150~C foran ~drlitional 15 minutes. Then an additional 23 kg of hydrocarbon solvent was pumped in over 30 minutes. The reaction mixture was then devol~ ed by passin~ through a 20-mm Welding Engineers twin-screw extruder at 200 rpm and 200-250~C over 14 hours. This concentrate is Ex. 52.
Similar preparations labelled 53 and 54 were synthesized with changes in feed time and radical flux as in~ te~l The following Table IV shows the improvement in sag ~s;stance when concenl,dtes of Example 52, 53 and 54 are blended with polypropylene of mfr=4:
134Q06n T~Rl F IV
% Weight Conc Sag Fraction in Slope Acrylic Init- Polymer Feed Rad.
~, Blend min~ conc. iator Sglids temp Time Flux Con. none 0.19 --52 2.5 0.1 1 0.6 DTBPO 47 1 50 122 0.000065 3.5 0.10 53 3.5 0. 11 0.6 DTBPO 45 150 90 0.00007 ~.0 0.10 54 3.~ 0.15 0.6 DTBPO 49 150 78 0.00008 5.0 0.09 FxAMPl F 55 This example and Table V demonstrate the unexpected advantage of the concentrate of Exampb 4 in the improvement of sag resistance for both high density polyethylene (HDPE) and linear low density polyethylene (LLDPE). Data for HDPE are for polymers of two different mfr values (4 and 8) and are obtained at 1 ~0~C, The LLDPE
values are on a single resin having a density of 0.917 g/cc, but at two different t~mperatures. Comparison molded polyethylene samples prepared for this test hsd a significarlt inel~ase in gloss over the unmodified control.
1340~6~
TARI F V
Time to Sag. Minutes PoyethyleneWt-%~rlitive Te~ ~C 508 mm 76? mm HDPE, mfr=8 0 150 8.7 9.3 2 10.2 11.9 3 5 15.8 30.0 31.4 HDPE, mfr=4 0 150 8.0 9.0 3.5 10.5 12.0 26.0 --LLDPE mfr=2 0 170 5.3 6.0 17.7 21.4 LLDPE, mfr=2 0 180 4.6 5.2 8.5 10.0 AMpl F 56 A polyethylene-acrylic graft copolymer concentrate was s~n~hesi~ed in a manner similar to that previously described for polypropylene-acrylic ~raft copolymers. The polyethylene-acrylic graft copolymer concentratl3 was made by polymerizing a 100% methyl ~o methacrylate (MMA) monomer mixture in the presence of polyethylene (weight ratio of polyethylene:monomer . 0.5:1). Radicals were gener~led from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00010 moles per liter per minute (radical flux). Mono",er and initiator were fed over 60 minutes ar~d the theor~lical (100% conversion) solids at the end of the r~aclion was 55%.
A 6.6 liter reactor e~uirped with a double helical agitator (115 rpm) was charged with 1760 9 hydrocarbon solvent and 725 9 1~40~6fi polyethylene (mfr-4 density=0.95) and heated to 1 50~C. The mixture was stirred for 3 hours. Over a two minute period two solutions were added. The first consisted of 1.63 g of di-t-butyl peroxide in 48 g of methyl "~el~acrylate. For the next 58 minutes a feed of 1.73 g of di-t-butyl peroxide in 1401 9 of methyl methacrylate was added at the same feed rate as the second feed. This feed schedule should produce a radical flux of 0.00010 during the feed time. After the feed was complete the reaction was held at 1 50~C for an additional 15 minutes.
Then it was devolati';zed by passing through a 30-mm Werner-o Pfleiderer extruder with vacuum vsnts at 200-250~C The elemental analysis showed that the concentrate contained 64% (meth~acrylate.
This example shows that both polyethylene-acrylic graft polymer and polypropylene-acrylic graft polymer concenll~te were effective at reducing the sag of HDPE. The blend of concenlldte with HDPE mfr=4 and density=0.95 was milled at 220~C and the hot material from the mill was molded at 21 0~C. Sags were measured by the same pr~cedure used for polypropylen~ sheet except that an oven temperature of 150~C
was used.
T~RI F Vl Concentrate Sag Slope 25.4 mm Sag 76.2 mm Sag of Fx~rnple %Conc. ~_ (min! (min) Control none 0.57 7.4 9.4 56 5% 0.27 9.0 13.0 56 10% 0.1110.0 19.8 4 5% <0.015 15.0 30 min to 31.7 mm 134006~
This example shows that the polyethylene and polypropylene graft copolymer concentrates are effective in improving sag resistance of HDPE while ungrafted acrylic polymer of similar MW iS not. Addition of as much as 5% of a commercial acrylic molding powder poly(methyl methacrylate) Mw 105 000 designaled ~A~) showed no decrease in sag rate while 3% poly(methyl methacrylate) present as the graft copolymer concentrate resulted in large reductions of sag rate.
The specific concentrate used in part of this study was synthesized in the following manner. The polypropylene-acrylic graft copolymer was made by pol~""eri~iny a 5~/O ethyl acrylate (EA) - 95% methyl methacrylate (MMA) monomer mixture in the presence of polypropylene of mfr=0.4 (weight ratio of polypropylene:monomer= 0.67:1). Radicals were generated from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00007 moles per liter per minute (radical flux). Monomer and initiator were fed over 120 minutes and the theoretical (100% conversion) solids at the end of the r~actbn was 55%.
A 6.6 liter reactor equipperl with a pitched-blade turbine agitator (375 rpm) was charged with 1780 9 of the hydrocarbon solvent and 880 9 polypropylene (mfr=0.4) and heated to 1 60~C. The mixture was stirred for 2 hours and then the temperature was decreased to 1 50~C for one hour. Over a two minute period two solutions were added. The first consisted of 1.22 9 Of di-t-butyl peroxide in 20 9 of the hydluca,bon solvent. The second ~nsi.~ted of 0.0002 mg of ,nonGi"ethyl ether of hydroquinone (MEHQ) and 0.05 9 of di-t-butyl peroxide in 1.1 9 of ethyl acrylate and 21 9 of mllthyl ",elhac~ylate. Forthe next 118 minutes a feed of 13 rng MEHQ and 2.70 9 of di-t-butyl peroxide in 66 9 of ethyl acrylate and 1253 9 of methyl ",ell,aclylate was added at the same feed 13400~
rate as the second feed. This feed schedule should produce a radical flux of 0.00007 during the feed time. After the feed was complete the reaction was held at 150~C for an additional 15 minutes. Then it was devol~ti';~ed by passing through a 30 mm Wemer-Pfleiderer extruder with two vacuum vents at 200-250~C. The elemental analysis showed that the concentrate contained 53% (meth)acrylate.
The blends of HDPE (mfr=7, density=0.95) and graft copolymer concentrate was milled at 200~C and the hot materials were formed into sheets from the mill at 170~C. Sa~s w~lre measured by the same o procedure used for polypropylene sheet except that an oven temperature of 150~C was used.
TARI F Vll Concentrate Sag Slope25.4 mm 50.8mm Fxs~le 1 ~vel min-~ .cz~5~ ¢min) ~ rnin) Control none 0.59 7.4 8.7 A 3.0% 0.58 7.1 8.3 A 5.0% 0.54 7.6 9.0 56 5.0% 0.27 -- 10.3 4 2.0% 0.28 8.2 10.2 4 3.5% 0.056 9.4 15.8 4 5.0% 0.038 10.4 31.4 58 3.5% 0.37 7.4 9.2 58 5.0% 0.30 8.1 10.0 .~ . . , . ., ., . "~. . . . ..
The concentrate of Example 4 was blended with LLDPE and the results of evaluating the sag resistance improvements are shown below in Table Vlll. The blenJ of modifier and LLDPE was milled at 170~C and the hot material from the mill was milled at 150~C. Sag resistance was measured by the same procedure used for polypropylene sheet at the temperature listed.
~A~ is an LLDPE having an mfr=2.3 and a density of 0.92, recommended for casting and extruding applications.
~B~ is an LLDPE having an mfr=1 and a density of 0.92, recommended for blow molding and extn~sion applications.
T~RI F Vlll Sag Sag Slope25.4 mm 101.6 mm npF ConcentPte Temo. ~1 sa~ (min~ sa~ (min) A none 1 80~C 0.58 3.4 5.6 A 5% Ex. 4 180~C 0.24 5.2 10.6 A none 1 70~C 0.54 3.9 6.4 A 5% Ex. 4 170~C 0.096 9.5 23.0 B none 1 50~C --- 7.8 15.6 B 5% Ex. 4 1 50~C --- 33.7 min at 19 mm FxAMpl F 60 This example illllsl,dtes improved sag modilicalion and increased nuc'a~ion te",p6r~tur~ for polybutylene, when blended with the concenll~te. Polybut~rJene, injection grade, mfr~4, with and without 2.44 wt. % of the concentr~le of Example 20 were milled at 1 90~C and ... ~, . , . . ,~ ..... . .....
1 3 4D0~ 6 pressed into plnqlJes of about 1.7 mm thickness. Times were measured for various distances of sag at 1 45~C. DSC curves were used (heaVcool time = 20~C/min). A higher crystallization temperature relates to increased speed of nucleation and solidification of the heated polymer.
T~RI F IX
Weight Percent rlme to ~C~9 ~nin:~e~ nsc Tem~er~tllre. oc Concentr~te ~5.4mm 50.~mm 101.6mm ~!~ Cryst~llize Control (0) 5:20 7:50 10:23 128 45 2.44 wt % 7:24 15:53 ~30 129 55 This example describes the preparalion of a concentrate of polypropylene-acrylic graft copolymer made by polymerizing 5% ethyl acrylate (EA) - 95% methyl methacrylate (MMA) monomer mixture in the presence of an equal amount of polypropylene. Radicals were gel)erdted from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00017 moles per liter per minute (radical flux). Monomer and initiator were fed over 30 minutes and the lheore~ical (100% conversion) solids at the end Of the rea~tion was 50%.
A 6.6 liter reactor eq~ipped with a double helical agitator (115 rpm) was chalged with 1980 9 of the hydrocarbon solvent and heated to 1 70~C. 1000 9 of polyprupylene (mfr,5) was fed to the reactor via a melt extruder set ar 200~C at a rate of about 10 ~ per minute. After 45 minutes hold at 170~C the a~hJitiûn of .,.ono",er and initiator solutions was begun. Over a two minute period two solutions were added. The first consisled of 0.44 9 of di-t-butyl peroxide in 21 9 of the h~d~ûca,Lon 13400fi~
solvent. The second consisted ot 0.11 9 of di-t-butyl peroxide in 1.3 9 of ethyl acrylate and 65 g of methyl methacrylate. For the next 28 minutes a feed of 1.59 9 of di-t-butyl peroxide and 19 9 of ethyl acrylate in 914 9 of methyl methacrylate was added at the same feed rate as the second feed. This feed schedule should produce a radical flux of 0.00017 during the feed. After the feed was complets the reaction was held at 170~C for an additional 15 minutes. Then it was devol~ ed by passing through a 3~mm Werner Pfleiderer extruder with vacuum vents at 200-250~C. The elemental analysis (carbon content) showed o that the concentrate contained 35% (meth)acrylate.
A sheet of polypropylene (mfr=4) with and without the concentrate of this example was heated in a forced air oven to 1 90~C removed from the oven and immediately placed over a female mold and subjected to vacuum. The top and bottom comer measurements were the average of the 8 measw~",ent~ in mm at the corner of each of the four side faces of the box. The top and bottom center measurements were the average of the 4 measurements in mm at the center of the edge of the 4 faces of the box. These measurements are summarized in Table X and demonstrate smaller wall thickness vall~iGns when the concentrate is present.
TARI FX
WAI I THICKNFSS VARIATI~N IN THFRMoFoRMFn PARTS
Top Top Bottom Bottom Poly~ro~ylene Center Corner Cent_~ Corner unmodified 1.14 mm 0.88 mm 0.75 mm 0.025 mm 5%Ex. 61 0.97mm 0.97 mm 0.35 mm 0.21 mm 134Q~fi~
This example demonstl~led the unexpected higher nucleation temperature and shorter time for crystn" ~tion imparted by addition of the polymeric concentrate of Examples 1 and 52 to polypropylene of mfrz4. The nuc'3~tion temperature was measured while cooling at 10~C/min, the melting temperature was measured while heating at 20~C/min and the crystallization time was measured isothermally at 127~C or 130~C. The extent of crystallization was reported for both cooling and melting measurements. Coi"palison was made with o ungrafted PMMA of similar Mw.
TABI F Xl Temp. of crystallization (~C) 127 127 130 130 130 130 130 Percent Concentrate 0 5 0 1.1 2.2 3.9 7.8 PolymerConcentrate of Example - 52 - 52 52 PMMAPMMA
Cry~ ;Gn Time, min. 16.3 3.6 24.5 3.7 3.0 8.1 10.6 rlua'a~tionTemperature,~C 105 112 107 118 118 112 110 % Crystallinity 39 40 41 46 42 42 41 Melting Temperature, ~C 165 166 169 170 168 170 168 % Crystallinity 41 44 44 44 46 46 44 This example demonsl.c.led the lower equilibrium torque and improvement in time to flux for blends of the concentrate of Example 1 with polypropylene of mfr=4 using the Haake Rheocordl'*The test conditions are described above. Peak torque at flux was also re~uce~l * Trademark 1340U6~
T~RI F Xll Wt.-%
Concentrate in Time to flux Equilibrium Torque Poly~roDylene (seconds) (meter-~r~ms ~t 21 5c o 109 695 FXAMpl F 64 This example shows that a propylene-acrylic graft copolymer concentrate may be used to improve the sag resistance of an acrylic sheet. About 20 parts of the graft polymer of Example 1 was milled with 100 parts of a commercial acrylic molding powder of Mw 105,000 and cG,-,pression molded. Sag tests indicated that the sheet containing the concentrate may be heated to about 5-10~C higher before flow equivalent to that of the unmodified sheet was observed.
FxAMpl FS 65 - 66 Graft copolymer concentrates were prepared according to the process clesc~ibed in Examples 52-54, using the conditions shown in Table Xlll.
1~40066 TARI F Xlll Monomer Feed Concentrate % AcrylicInit- Time Radical of FY~nlDle InCon~ Solids Tem~. ~C (min) ~!~
A 55 DTBPO 50% 150 120 0.00010 B 55 DTBPO 50% 150 120 0.00007 Concentrates A and B were blendsd together at a weight ratio of 2.8:1 to form concentrate C. As indicated in Table XIV, concentrate C
was blended at the 4~~ level with polypropylene and the indicated amounts of di-t-dodecyl disulhde (DTDDS) and extruded. The sag 0 results for these blends are given in Table XIV below.
T~RI F XIV
Fx~mDle % Conc~ntr~te nTDDSSa~ Slope in min-4 none 0.07 66 4 0.03% 0.05 67 4 0.3% 0.03 Stabilizing the concentrate during processing, as by using the DTDDS, is seen to produce even more significant improvement in melt strength.
~ This example further de",Gnsl.d~es that the graft copolymer has little effect on the high-$hear vi5cosi~y but a pronounced effect on law-shear viscosil~ in polypropylene.
1 3 4 0 0 fi ~
The graft copolymer of Example 1 was admixed at the five weight-percent levei with an injection-moldin~ grade of propylene hoi.,opolymer, mfr.4, as in Example 63. Capillary and parallel-plate viscosities were measured at various temperatures under conditions described above, under both low and high shear conditions. The results shown in Table XV below demonstrate the increase in low shear viscosity, especially at temperatures below about 210 ~C, with essentially no effect on viscosity at high shear rate.
TARI F XV
Conditions~ w Shear High Shear AmountofGraftPolymer: o % 5 % o % 5%
Test Terr~per~ture Capillary Viscosity (a) 180 ~C94000 133000 1900 2000 Capillary Viscosity~a~ 190 ~C80000 110000 1900 1600 Capillary Viscosity (a) 210 ~C57000 75000 1200 1 100 Parallel Plate Viscosity(b) 190 ~C63000 99000 2100 2100 Parallel Plate Viscosity (b) 210 ~C54000 58000 1800 1800 Parallel Plate Viscosity (b) 230 ~C37000 39000 ~ 500 1400 Shear Conditions:
a: Low Shear=1.0 sec-1; high shear5 1000 se~
b: Low Shear=0.1 sec-~; high shear= 500 sec-~
FxAMpl F 68 This example shows irnproved stabilization to weight loss on heating by use of a disulfide or a sub~tuted tri~ine st~hili7er. A
polypropylene-acrylic graft copolymer similar to that of Example 4 was blended with 5~h ' >ers on the mill roll. The graft copolymer (98 grams) was fluxed on the mill at 1 95~C. The stahili7er (2 grams) was added and blended in for 2 minutes. The material was removed from the mill, cut into chunks, and granulated. One or more of these stabilized versions were then let down in a similar manner in additional graft copolymer to produce graft copolymer stabilized at the 100-5000 ppm level. The results on the TGA of stabilkation are shown in the table.
Weight loss (%) is the temperature at which the particular percent weight loss is observed, utilizing i DuPont ThermoGravimetric Analyzer *
at a heating rate of 20~C in nitrogen. Although none of the stabilizers O were deleterious to stability, only those designated 2 and 7 exhibited significant stability advantages.
The stabilizers studied were:
1. DLTDP (dilauryl thiodipropionate);
2. TNPP (trisnonylphenyl phosphite);
3. " Irganox"1010 (tetrakis(methylene(3,5-di-t-butyl-4-hydroxy-hydrocinnamate))methane);
4. DTDDS (di-t-dodecyldisulfide);
5. " Irgafo~'168 (tris-(2,4-di-t-butylphenyl)phosphite);
The reference exemplifies grafting methyl methacrylate onto polyethylene and polypropylene.
Japanese Kokai 223250/87 discloses compatibilizing a polyolefin and a polyamide using a reaction product of an unsaturated carboxylic acid or its derivative grafted onto a mixture of polyolefin and polyamide, that is, the reaction product is formed in the presence of a mixture of two or more polymers. The amount of acid or derivative reacted with the trunk polymers is less than 10%, and it is clear from the only examples present, which utilize unsaturated acids which do not homopolymerize, that what is attached or grafted are low-molecular-weight moieties,. They ~lisclose reaction conditions, including relatively low levels of unsaturated acid and relatively high levels of peroxide, which would lead one away from achieving the molecular weights of the grafted chains disclosed below as part of the present invention. A particular modifier disclosed by this reference, formed by reacting two non-polymerizable acids with a mixture of four tnunk polymers, affects the compatibility of the polyamide and polyolefin. However, the comparative data suggest that a reaction of the acids onto polypropylene alone is not an effective compatibilizer for the two resins, and shows that graft polymers of low levels of low molecular unsaturated acids or derivatives are not effective in compatibilizing polyamides with polyolefins.
Japanese Kokai 86040/87 directed to polymer adhesives, disclQses an olefin polymer adhesive modified with a carboxylic or carboxylic anhydride group, further reacted with a polyolefin having alcohol functionality, and still further rea~ed with an aromatic acid halide.
RolJtevin et al., in An~ewandl~ M~kromolekular Chemie. Vol. 162, page 175 (1988), disclose the pr~pardtiGn of a graft polymer of poly(methyl "-ell,acrylats) onto a polyethylene trunk by ozonQlysis of a low-density polyethylene followed by heating the activated polyethylene in the presence of methyl methacrylate. They disclose grafts of methyl 1~4û066 methacrylate having a number-average molecular weight up to 21400, and the use of such grafts as polymeric emulsifiers or compatibilizers for mixtures of low-density polyethylene and poly(vinyl chloride). They report that the compat~lbilized mixture has a distinct increase in the stress required to break it, and a decrease in the domain sizes in the blend.
They also report appr~ciable degradation of the polyethylene molecular weight when it is ozonized prior to grafting. This reference does not deal with higher molecu'~ weights, nor does it provide any indication that the graft polymer might be effective in reducing sag of a polyolefin matrix 0 polymer or otherwise imparting desirable rheological effects to a polymer.
Thus, the art has described means for preparing grafts of methyl methacrylate homo- and copolymers upon polyolefin substrates, but has not recognized the advantages of the polymerization process herein described for a rapid, ~fficient procluction of novel high molecular weight grafts without gel and with ease of product isolation. The art teaches that certain grafts may be blended with polyolefins, but has not recognized the unexrected utility of the novel graft polymers of this invention as having positive effects on both low-shear melt and solid-state properties,-0 e.speci-~ly with little or no effect on the high-shear performance. The art also has not recognized or identified the positive effects on sag resistance i"lpa,led by the present grafts.
It is thus an object of this invention to provide an improved process for the manufacture of novel graft polymers of methacrylic esters onto polyolefin subsl-dles. Another object is to provide graft copolymers of at least one chain of methacrylate polymer of relatively high molecular weight, i.e. at least ~0,000, onto a polyolefin homo- or copolymer subslldle. Yet another object is to provide such graft copolymers which serve as co"~p~tibil; ;r,~ agents for blends of polymers which are o otherwise poorly compatible. It is a further object to provide blends of the graR copolymer with a polyolefin matrix which exhibit improved physical performance in the melt, upon cooling, and in the sold state.
Further objects and advantages of this invention will appear as this specification progresses.
SUMMARY OF THF INVFNTION
Broadly, the aforesaid objects and advantages are accomplished by grafting onto a non-polar polyolefin trunk in solution, at least one chain which is of a polymer having a weight average molecular weight greater than about 20,000, and present in a weight ratio with the polyolefin of from about 1:9 to 4:1. The graft polymer is derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2 S C~CH3)COOR, where R may be alkyl, aryl, substituted or unslJbstitute~l and less than 20%, based on the total monomer weight, of an acrylic or styrenic monomer copolymerizable with the methacrylic ester. This is accomplished by adding the methacrylate monomers to a solution of the polyolefin together with an initiator which generates a conslant, low radical concent-dlion, or radical ~flux", at the solution - -temperature. These radicals initiate polymerization of the monomer and cause for"u~liGn of a covalent bond with the trunk.
The resulting copolymer product, hereinafter referred to as concenl~dte, may be blended with polyolefin either as a result of the manner by which it is made, or aRer it is made. It may be extruded into a desired shape either directly, or after pell~ti7~tion. In either case, the resulting l~l~nded product exhibits a relatively high tensile modulus and high sag r~sis~nce without an increase in melt viscosity, as compared ~ with similar un~.dn~l polymers, viz: polyolefins without a high molecular weight chain or chains covalently bonded thereto.
.,. .... . , .. " , . , . , .. ,, ,.~ .. .. .. ... .. ... ... ... . ...
13~00fi~
The concentrate may also be blended with other polymers than polyolefins, and particularly with mixtures of two or more polymers which are poorly compatible with one another, and which may or may not include polyolefins, to improve the compatibility of the resulting S mixture.
The invention also relates to a process of making such a copolymer having a relatively high weight-average molecular weight (Mw) polymer chain. Briefly, the process according to this invention involves dissolving or swelling the polyolefin in an inert hydrocarbon solvent, and heating to dissolve the polyolefin, i.e. at least about 1 40~C. While agitating the solution, a monomer is introduced, together with an initiator which generates a constant, low radical flux at the temperature of the solution; the radicals initiate polymerization of the monomer and formation of a covalent bond therewith on the polyolefin trunk. The reacted mixture may be allowed to solidify by removal of the solvent. The resultant product, the concentrate, consists of the polyolefin with the chain grafted thereto, unreacted polymer, i.e. polyolefin without the chain, and ungrated methacrylic ester polymer. It may be pelletized, blended with another polyolefin and extruded into desired shape. Alternatively the reaction mixture may be extruded directly in a devolatilizing extruder to volatilize the solvent and residual monomer, and thereafter blended with a polyolefin and extruded to form article in such form as sheets, tubes and the like.
According to one aspect of the present invention there is provided a graft copolymer capable of imparting to a polyolefin when blended therewith a relatively high tensile modulus and high resistance to sagging without increasing melt viscosity, the copolymer comprising:
13409~
(a) a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene), copolymers of said olefins with each other, and one or more copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic ester, and (meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and (b) at least one methacrylate chain grafted with a covalent bond to said trunk having a weight ratio with said trunk of from about 1:9 to about 4:1, said chain being a polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain having a weight average molecular weight of from about 20,000 to 200,000.
The present invention also provides a polymer blend comprising (a) a polyolefin; and (b) a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene), copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and ~meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted lla 1340~6b alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight-average molecular weight of from about 20,000 to 200,000, and ~eing present in a weight ratio with said trunk of from about 1:9 to about 4:1; said polyolefin (a) being the matrix for the blend.
The present invention further provides a process for preparing a graft copolymer concentrate capable of imparting to a polyolefin when blended therewith relatively high tensile modulus and high resistance to sagging without increasing the melt-viscosity, comprising the steps of:
(a) introducing a non-polar polyolefin selected from the group consisting of polypropylene, polyethylene, polybutylene, poly(4-methylpentene), copolymers of said olefins, and one or more copolymers of said olefins with one or more 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid into a reactor vessel containing an inert solvent, said polyolefin having a weight average molecular weight between about 50,000 and 1,000,000;
(b) heating the polyolefin mixture to a temperature at which the polyolefin dissolves;
(c) adding with agitation at least about 80%, based on the total monomer weight, of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl or substituted aryl or alkaryl and not more than about 20%
based on the total monomer weight of an acrylic or styrenic monomer copolymerizable with the methacrylic ester to the polyolefin solution in the reactor vessel;
llb 13~006~
(d) adding to the mixture in the reactor vessei an initiator which produces a low and constant radical flux for a time sufficient to produce a methacrylate chain polymer having a weight average molecular weight of between about 20,000 and 200,000 which S is covalently bonded to the polyolefin; and (e) removing the solvent to isolate the graft copolymer concentrate.
Extruded and molded products, optionally including various additives, formed from polymer blends as defined above in which the polyolefin constituent is polypropylene, are also provided by the present invention.
The foregoing aspects of the invention are also disclosed, and are claimed, in Canadian Patent Application No. 593,171 filed March 9, 1989, of which the present application is a divisional.
According to a further aspect of the present invention there is provided a method for improving the compatibility of a blend of one or more non-polar polymers with one or more polar polymers which comprises incorporating into the blend from about 0.2 to about 10 parts per hundred parts of the blend of a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene), copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, llc 134006~
substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight average molecular weight of from about 20,000 to 200,000, and being present in a weight ratio with said trunk of from about l :9 to about 4:1 .
The present invention still further provides a blend of one or more polar polymers with one or more non-polar polymers and a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene) copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight average molecular weight of from about 20,000 to 200,000, and being present in a weight ratio with said trunk of from about 1:9 to about 4:1, the compatibility of the blend being superior to that of a blend of the non-polar polymers and polar polymers in the absence of the graft copolymer.
lld 13 10û6fi DETAILED DESCRIPTION
In the following, LDPE is low-density polyethylene, usually branched, of density of about 0.91 to about 0.94 g/cc; HDPE is high-density polyethylene of a density above about 0.95 g/cc; LLPDE is linear low-density polyethylene of density of about 0.91 to about 0.95 g/cc;
EPDM includes rubber terpolymers of ethylene, propylene, and a non-lle 13~006~
conjugated diene monomer, such as 1,4-hexadiene or ethylidenenorbornene.
The term ~polar substrate~ or ~non-polar polymer, as used herein, is difficult to define in quantitative terms. By ~non-pola~ is meant polymers which are predominantly formed from monomer units of mono-or di-olefins. ~Polar~, as generally under:iloo(J in the polymer art, would refer to monomers or polymers which contain an oxygen, nitrogen, or sulfur-containing functionality. Thus, methyl methacrylate, acrylonitrile, and vinyl phenyl sulfone are ~polar~ monomers, whereas polypropylene is a ~non-polar~ polymer.
The polymers to be modified in the grafting process include the non-polar olefin polymers and copolymers. Included are polypropylene, polyethylene (HDPE, LDPE, and LLDPE), polybutylene, ethylene-propylene copolymers at all ratios of ethylene and propylene, EPDM
terpolymers at all ratios of ethylene and propylene and with diene monomer contents up to 10%, poly(l-butene), polymethylpentene, ethylene-vinyl acetale copolymers with vinyl acetate contents up to 25%, ethylene-methyl acrylate copolymers, ethylene-methyl methacrylate copolymers, and ethybne-ethyl acrylate copolymers. Also included are -mi-xtures of these polymers in all ratios.
Usable graft copolymers include those with ratios of polyolefin:acrylic polymer or copolymer that vary from 20:80 to 80:20.
The molQc~ r weight of the polyolefin polymer which forms the tnunk of the graft copolymer should be high enough to give a large amount of non-polar polymer when grafted, but low enough so that most of the graft copolymer has one acrylic polymer chain grafted to each polyolefin trunk chain. A polyolefin tnunk having a molecular weight of about 200,000-800,000 Mw is especi~lly preferred, but polyolefins having a molecular weight of about 50,000-200,000 can be used with some 13~1 0066 beneficial effect. In general, a graft copolymer imparts greater melt-rheology improvement to a high-."ol~c~ r-weight polyolefin. This is especi-"y true when the polyolefin tnunk of the graft copolymer is of relatively low molecular weight.
Melt flow rate (mfr) is well known to correlate well with weight-average molecular weight. The preferred range of mfr values for the polyolefin trunks used in preparing the graft copolymers of the present invention are from about 20 to about 0.6 9/10 minutes as measured by ASTM Standard Method D-1238.
o The preferred monomer is methyl methacrylate. As much as 100%
of this, or of other 2 to 4 carbon alkyl methacrylates, can be used. Up to 20% of high alkyl, such as dodecyl and the like, aryl, such as phenyl and the like, alkaryl, and such as benzyl and the like, and/or cycloalkyl, such as cyclohexyl and the like, ~"etl,aclylates can be used. In addilion, up to 20% (preferably less than 10%) of the f~l'owing monomers can be incGr~.oratecl with the methacrylate esters which form the major portion of the monomer: methac~lic acid, methacrylamide, hydroxyethyl methacrylate, hydroxypropyl methacrylate, alkoxyalkyl methacrylates, such as ethoxyethyl methacrylate and the like, alkylthioalkyl methacrylates, such as ethylthioethyl methacrylate and the like, methacrylamide, t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoprupyl methacrylamide, glycidyl methacrylate, methacryloxypropyltriethoxysilane, acrylate monomers (such as ethyl acrylate, butyl acrylate and the like), styrene, acrylonitrile, ~5 acrylamide, acrylic acid, acryloxypropionic acid, vinyl pyridine, andN-vinylpyrrolidone. In ~Jdilion, as much as 5% of maleic anhydride or itaconic acid may b~l~s~d. It is i.,.pG,l~nt that the chain transfer of the poly".eri7ins~ chains to its own polymer bc minimal relative to transfer with the polyolefin chain$ forthe efficient production of homogeneous non-gelled graft polymer in good yield.
13~006~
The molecular weight of the acrylic graft as measured by the weight average molecular weight of the ungrafted co-prepared acrylic polymer may be about 20,000 to 200,000. The preferred range is 30,000 to 150,000.
The process of graft polymerizing the monomer leads to the production of ungrafl~ and grafted material. The amount of grafted ",a~erial is in the range of 5% to 50% of the total acrylic polymer or copolymer produced The graft copolymer is prepared in a process that polymerizes the monomer in the presence of the non-polar polyolefin.
The process is conducted in a solvent which swells or dissolves the non-polar polymer. The solvent is also one that has no or low chain transfer ability. Examples include non-branched and branched aliphatic hydrocarbons, chloro~enzene, benzene, t-butylbenzene, anisole, cyclohexane, naph~l,as, and dibutyl ether. Preferably, the solvent is easy to remove by extrusion devolatilization, and therefore has a boiling point below 200~C, preferably below about 1 50~C. To avoid excessive -pressure, a boiling point above about 100~C is also preferred.
The final solilds content (which includes polyolefin and acrylic polymer) depends on the viscosity and the ability to mix well. The 0 practical limits are 20% to 70% but the solids content can be as high as is consistent with good mixing for economy. Preferably, the solids content falls in the range of about 35% to about 60%.
A gradual addition or multicharge addition of the monomer is preferred. Optionally, the monomer charge need not be the same throughout, for exampb, the last 0-20% may contain all of the monomer used in minor amount to concenl-d~e that monomer in one portion of the polymer.
The temperature during the polymerization can be in the range 110 to 200~C but the p,~fer.~d range is 130 to 1 75~C. Especially ~ . , ~" , ~ .
134 006b preferred is 145 to 1 60~C. The pressure can be atmospheric to superatmospheric, or as high as 2100 kPa or whatever is necess~ry to keep the reaction mixture in the liquid phase at the polymerization temperature.
The unreacted monomer concentration should be kept low during the reaction. This is controlled by balancing the radical flux and the monomer teed cohdilions.
For polymerization, oil-soluble thermal free-radical initiators are used. Those that work in this process are those with a one hour half life o at about 60~ to about 200~C. The preferred ones have a one hour half life in the range 90 to 170~C. Suitable free radical initiators include peroxy initiators such as t-butyl peroxypivalate, lauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethyl hexanoate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, acetyl peroxide, succinic acid peroxide, t-butyl psr~.,1uate, benzyl peroxide, t-butyl peroxyisobutyrate, t-butyl peroxymaleic acid, I-hydroxy-l-hydroperoxydicyclohexyl peroxide, 1 ,I-bis(t-butylperoxy)-3,3,~trimethylcyclohexane, t-butyl peroxycrotonate, 2,2-bis(t-butylperoxybutane), t-butylperoxy isopropyl carbonate, 2,5-dimethyl-2,5-bis(benzoylperoxy)-hexane, t-butyl peracetate, methyl ethyl ~o ketone peroxide, di-t-butyl diperoxypl,~ ldle, t-butyl perbenzoate, dicumyl peroxide, 2,5,dimethyl-2,5-di(t-butylperoxy)hexane, 2,4-pentanedione peroxide, di-t-butyl peroxide, 2,5,-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di(hydroperoxy)hexane. t-butyl hydroperoxide, t-butyl cumyl peroxide, p-menthane hydroperoxide and ~o-bis-isobutyronitrile.
The initiator is introduced together with the monomer during the poly",eri~dt;on in a manner to maintain a fairly cor,slanl radical flux during most of the polymerization. This is done to achieve the correct 1340~66 high moleeul~r weight, a high graft efficiency, the desired molecular weight distribution, and treedom from gel.
Radical flux can be defined as the calculated rate of formation of free r~dic~lc~ expressed in equivalent of radicals per liter per minute.
While not being capable of being measured experimentally, this may be ~cul~ted from the known rate of decomposition of the free radical initiator present at any time. and its instantaneous concentration.
Decomposition rates for initiators are determined from published literature, and the conoentration is either a known constant, as in continuous feed of initiator, or can be calculated (for a single charge of initiator) from the known decomposition rate constant and the time elapsed since feed.
Good results are achieved when a uniform radical flux is maintained and the radkal flux is calcu~ted to be in the range 0.00001 to 0.0005 equivalents of radicals per liter per minute. The preferred range is 0.00002 to 0.0002 equivalents of radicals per liter per minute.
The radical flux is dependent on the specific initiator utilized, its concentration and rate of decomposition, and the reaction temperature chosen. The rate of Jeco",posilion can be found in t~hu~ted data, such as in ~The PolYmQr H~ll.ook', 2nd Edition, ed. Brandn~p and Imr~ergut, Wiley and Sons, New York (197~), or provided by the manufacturer.
Even if the exact rate c~"s~nl at the te",perdl~Jre of interest is not known, often activation ener~ies are s~ppl ed from which the rate can be celcul~ted. The radical flux is:
Radical flux = 2(kd)(60)(1) where kd is that rate ¢onsla,l~ for decoi"posilion of the particular initiator in units of inverse secon.Js, and I the concentration of the ir.itialor in moUliter. In a batch reaction, I steadily decreases from IO. the initial charge, and the radical flux is not conslant. When initiator is continuously 13~00t;~
fed, a r~plcul~tion must be made to determine the instantaneous concenlr~ion of initiator, but the value is much more constant than in a batch r~ac~ion, espec;~y with careful control of initiator feed.
The process may be run in a semi-continuous or continuous manner. Monomer, solvent, and initiator may be added by means similar to those described above. Polymer may be separately dissolved in solvent and added at a rate essentially equivalent to that of product removal, or polymer may be melted and added as a solid to the reaction by means of an extruder.
ARer the polyrn~ alion, a hold time may be used. Then the mixture is devolatilized to remove solvent and any unreacted monomer.
Acceptabls devolatilizing devices include a devolatilizing extruder, a rotary film evaporator, or any other convenient stripping device as known in the art. The poly."e,~tiGn reaction mixture may be conveyed to the devolatilization apparatus as a batch or continuously.
Prior to, during, or aRer the devolatilization step, appropriate additives may be admixed into the sraR copolymer solution/suspension which are desired to be present in the isolated graR copolymer. If such additives do not affect the grafting reaction, they may be added prior to, during, or after the polymerization proc~ss. Such additives may also be added when the graR copolymer is blended with the matrix polymer.
Such additives may indude st~hili~ers against light or heat, such as benzo~ oles, hindered amines, alkyl polysulfides such as dialkyl disulfides, and the like, lubricants, or plasticizers; flame retardants; and ~5 the like. rlef6rleJ is the aclJi~ion of a disulfida, such as di-n-dodecyl disu!fide or di-t~16.,-yl disulfide and the like at levels between about 0.001% to about 0.05% by weight of graft polymer, based on the wsight of graR copoly.l-er plus matrix polymer, to slabi' ~e the acrylic portion of the graR copolymer against thermal degradation during melt processing while admixing into the matrix or blending and extruding.
, ... . , . ",; ", .... . ... . .
- 134006~
A second class of stabilizer is the tris(polyalkylhydroxybenzyl)-s-triazinetriones. rlef~, .ad is tris-(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-(1H, 3H, 5H)-trione, at levels from about 0.001 to about 0.1%
by weight, based on the total polymer weight.
Stability may also be imparted to the acrylic portion of the graft copolymer by including an alkylthioalkyl (meth)acrylate, preferably ethylthioethyl ,netl,ac~ylate, with the acrylic monomer or monomers during the graft polymerization.
The product is then isolated by stranding, cooling, chopping, o drying, and bagging, or other known collection techniques.
The polyolefin and the graft copolymer concentrate may be blended by mixing the dry feed materials and extruding either directly to form a film, sheet or the like, or by collecting the blend and reprocessing it into the Jesi~ed article, or by adding the polyolefin in the course of the devolatilization.
Polyolefins are often produced with one or more stabilizers to prevent degradation of the polymer appearance or physical properties during processing and/or end use. Such st~bili~ers may include metal salts such as metal stearates, which act as acid acceptors, hindered ~ phenols, which act as anti-oxidants, and sulfur-containing organic esters or derivatives, added as heat st~bili~ers. Examples of such additives, which are usually prupliatary to the supplier, are metal stearates, 2,6-dimethylpt.snolic compounds, and ll. ~d;~sters of long-chain alcohols.
Polyolefins may also contain light st~hi~i~ers, such as hindered amines, benzot,ia~oles, and the like. All of the polyolefins used in the present examples are thought to contain small amounts of these proprietary ct?~ srs.
One way to specify the blend composition is that at least about 0.2% of the total formulation (polyolefin plus graft copolymer) should be 1340U6~
chemically grafted acrylic polymer or copolymer within the molecular weight limits specitied. The maximum amount is about 10% gratted acrylic polymer, with up to about 5% grafted acrylic polymer being preferred tor cost optimization and opti~ alion of most properties of the blend.
Optionally, the blend of concentrate and polyolefin may be further modified by the introduction of fillers, both inorganic and organic, fibers, impact modifiers, colorants, stabilizers, flame retardants, andlor blowing agents.
o Blowing agents may be gases, such as nitrogen or carbon dioxide, admixed with the polymer melt in the extruder and allowed to expand upon extrusion. More often, blowing agents are solids which liberate gases, usually nitrogen, at a specific melt temperature, and which are mixed into the melt, or blended from a pre-compoundsd mixture of the blowing agent disp~r~ed in a polymeric matrix. The melt temperatures for the polyolefins are typically in the range of about 200 to about 230~C, although other temperatures may be used, depending on the specific blowing agent. Solid blowing agents include azo compounds such as ~o~';c~rbonamides, ~oisobutyronitriles, hydroazo compounds, or compounds containing the nitroso group.
The blend of the graft copolymer and polyolefin is useful in thermoforming, film malcing (especially blowing and extruding), blow molding, fiber spinning, acid and basic dyeing, foaming, extrusion (sheet, pipe, and profile), coextrusion (multilayer film, sheet, preforms, and pa,isons, with or without the use of tie layers), hot melt adhesives, calendering, and extrusion coating (for the preparation of polymer~fabric, carpet, foil, and othsr mu~ti'ayar constructions). Such graft copolymers, espec;~lly with small amounts ot copolymerized acid functionality, are useful when blended with polyolefins for Tmproved printability. The grafts 134006~
themselves may be used as tie layers be~/eon otherwise incompatible polymers.
In extrusion, the graft copolymer is useful, especially with LLDPE, at red~ction of melt fracture without an effect on the melt flow rate. Uniike the additives of U.S. Patent No. 4,094,297, the present additives do not plate out when the modified polyolefin is extruded for extended times.
When polypropybne is modified with the graft copolymers of the present invention, it may be employed in the manufacture of many useful objects, such as extn~sion- or injection-blown bottles for packaging of o foodstuffs, aqueous solutions such as intravenous feeds, hot-filled items such as ketchup, or extruded articles in profile form such as clips, scrapers, window and door casings and the like. The foamed articles may be used as substitutes for wood in moldings, for packaging materials, for insulation or sound-deadening materials, for food containers, and other rigid-article app' ~'ions. Films may be used in many protective or wrapping appl ~tions, such as for food packaging, blister packaging of consumer goods, and the like.
The graft copolymers of the present invention are useful in preparing polyolefin fibers, espec;ally polypropylene fibers; they are especially useful when the graft copolymer is formed from a polypropylene trunk. Polypropylene is relatively easy to process into fibers having high strength and toughness.
Polypropylene fibers show certain deficiencies which include difficulty in dyeing and poor long-term dimensional stability. Grafts ~5 containing fun~ional sites capable of accepting dye may be prepared bythe present prucess-by incGr~.or~ting low levels ot dye-accepting monomers, such as .,.~lha~rylic acid, din,elhylaminoethyl methacrylate, N-vinylpyridine, and the like. The improved sag resistance noted for the 134006~
present graft polymers in a polypropylene matrix should correspond to improvements in creep resistance of the fiber.
Polypropylene rnay be formed into fibers by slitting tape from extruded film to form large-denier, coarse fibers, by extruding monofilaments into lar~e-denier fibers with a controlled cross-sectional size, or by extruding multifilaments through a spinnerette to produce bundles of small-denier fibers. In all cases, the fibers may be draw-textured. As an example, small-denier polypropylene fiber bundles may be extruded from a 25.4-mm, singls-screw extruder having a screw o length-to-diameter ratio of 24:1, such as that supplied by Killion Extruders Corp. of Cedar Grove, New Jersey and equipped with a static mixer, metering pump and spinnerette assembly with multiple orifices.
Using such equipment the extruded polypropylene would be passed thought a cooling bath and then over a series of godets (metal rolls with heating or cooling capability) to orient the polymer or quench existing orientation.
Polypropylene fibers may be used for, among other things, strapping, netting (including fish nets), slit tape, rope, twine, bags, carpet backing, foamed ribbon, upholstery, russ, pond liners, awnings, ~0 sv~;-"---ing-pool covers, tarpaulins, lawn-furniture webbing, shades, bristles, sutures, c;gar~tle filters, nonwoven fabrics, such as for tea bags, bed sheets, banJages, diaper liners and the like, and for doll hair, apparel and the like.
The graft copolymer of the present invention may also be used to improve the compatibility of polymers in blends where they would otherwise be poorly c~i),patible. The graft copolymer is incorporated into such blends, preferabiy at levels of from about 0.2 to about 10 %, p~,afe,~bly from about 0.5 to about 5%, and more preferably from about 0.8 to about 2.5%, to ach ~ve the desired improvement in co,-,~.alibTlity.
0 Higher levels of the graft copolymer may be used, but increases above 13~006~
the preferred level generally show only small improvements in compatibility.
As noted above, compatibility is not easily predicted. As a general rule non-polar polymers are poorly compatible with more polar polymers, but poorly compatible blends may also be found experimentally among polar-polar or non-polar-non-polar blends. Examples of the non-polar polymers are olefinic polymers such as high- and low-density polyethylene and linear low-density polyethylene, polypropylene including atactic polypropylene, poly-1-butene, poly-iso-butylene, ethylene-propylene rubber, ethylene-acrylic acid copolymer, ethylene-propylene-diene terpolymer rubber, ethylene-vinyl acetate copolymer, poly (ethylene-propylene), polymethylpentenes, and ionomers such as polymers of ethylene with metal-salt-neutralized acrylic acid.
Relatively more polar polymers, called polar polymers for the purposes of this clisclQsure, include acrylonitrile-butadiene-styrene polymer, acetal polymers, polyarylates, acrylic-styrene copolymers, acrylonitrile-styrene-acrylic polymers, acrylonitrile-styrene polymers modified with ethylene-propylene rubber, cellulosics, polyester-polyether block copolymers, polyesters such as polybutylene terephll,alate and polyethylene terephtl,alate, and includin~ liquid-crystal polyesters, polyetheramides, polyetheretherketones, polyetherimides, polyethersulfones, ethylene-vinyl alcohol copolymers, polyvinyl chloride, ch!orinated polyvinyl chloride, polyvinylidene chloride and fluoride, styrene polymers such as polystyrene, high-impact polystyrene, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-maleic anhydride copolymers, alkyl-substituted styrenes copolymerized with styrene alone or witl~ ~he additional ",GnGI"ers listed for styrene, polyphenylene ether, polyphenylene suffide, polysulfone, polyurethane, polyamides, i.e., nylons such as nylon 6, nylon 6-6, nylon 6-9, nylon 6-10, nylon 6-12, nylon 11, nylon 12, amorphous nylons, polyamideimide, .. . . . ~ . . . O
13~006fi polycaprolactone, polyglutarimide, poly(methyl methacrylate), other C1 to C8 poly(alkyl (meth)acrylates) and polycarbonates. The acrylic polymers referred to above are polymers containing at least 50 weight percent, and preferably at least 80 weight percent, of mers of acrylic acid and/or methacrylic acid (referred to collectively as (meth)acrylic acid) or their esters, preferably their alkyl esters and more preferably their alkyl esters in which the alkyl group contains from one to eight, preferably one to four, carbon atoms. The remaining mers are those from one or more monomers copolymerizable with-the (meth)acrylic acid or ester by free-o radical polymerization, preferably vinylaromatic monomers, vinyl esters or vinyl nitriles, and more preferably mers of styrene or ac~lonitrile.
In the examples which follow, polymer concentrates and polymer blends were tested using standard procedures which are summarized below.
Unr~7acted ,nûnomer in the reaction mixture prior to solvent removal or subse~uent to extnJder devolatilization was determined using a gas chromatographic technique.
The coll~cted volatiles were analyzed by gas chromatography on a 25 meter CP wax 57 CB wall coated open tubular fused silica column O at 40~C. A co"",a-ison of the major signals for the solvent with the MMA
signal was used to det~rmine the amount of residual monomer in the reactor and ll,er~fore give a measure of conversion immediately. A more accurate measure of conversion was obtained by a C,H,O analysis of the graft copolymer. The carbon content was used to calculate EPDM or polypropylene content by inte-l.olating between the carbon content of EPDM (85.49%) or,~ol~,crupylene (85.87%) and acrylic polymer (60.6%).
The graft copGly..,ers are analyzed by solvent exl,d~iGn to remove the ungr~led (meth)ac ylic portion, whose ",ols~r weight is then determined by gel permeation chromatographic techniques. A technique for separating the graft copolymer from ungrafted polyolefin is not available. For concentrates, 0.8-1.3 ~ of polymer was placed in a centrifuge tube with 17 cm3 of xylene. The tube was shaken overnight.
Then the tube was placed in an oil bath set at 1 38~C. The tubes were periodically taken from the bath and shaken until all polymer had dissolved. The fact that all dissolved indicates that no crosslinking occurred. The tubes were cooled during which time the polypropylene conlaining substances pre.,ipit~le. Then the tubes were centrifuged at 15,000 rpm for 2 hours and the xylene solution was removed with care not to remove any floats. The molecular weight of the acrylic polymer extracted by the xylene was cleter",ined by gel permeation chromaloyraphy. The procedure was repeated on the resulting plug to extract addil;Gnal (meth)acrylate. The value labelled % graft is the portion of the (meth)acrylic polymer forrned which remains with the polyolefin plug after repeated exlldctiGn. The c~i"pGsilion is determined from the carbon analysis of this plu~.
The polypropylene concentrate and any additives were blended in the melt on a 7.6 cm by 17.8 cm electric mill with a minimum gap of 3.8 mm set at 1 90~C. Onc~ the material had fluxed, it was mixed an ad.JitiGnal 3 minutes. Higher temperatures were used for higher viscosity materials (tor example, mfrs0.5-2 material was done at 195-21 0~C).
While still hot, the "~alerial was either compression molded or cut into small chunks (about 1-2 cm in each dimension) for granulation (5 mm screen). It is of inleresl that the additives of the present invention contribute to easy release from hot metal surfaces, such as mill rolls, Jl laako Rheocord'bowls, etc.
Millin~ of polyethylene was done in a similar manner except that the HDPE blends wer~ milled at 200~C and the LLDPE blends were milled at 170~C.
* Trademark 13400fi~
A 2.5 cm Killion extruder was used for extrusion blending. A two stage screw was used at 150 rpm with all three zones set for 190~C. The one-strand die was also set at the same te",pe,~dl.lre. A vacuum vent was used. The s~rand was cooled in water and pelletized. The extrusion 7 rate was 4.5 kg per hour.
Melt blending in a"Haake Rheocord"(a batch melt mixer) was done on 50 9 samples at 190~C or at 210~C and 100 rpm in air. Mixing was continued for three minutes after peak torque was reached. Sample size was 50 grams.
The polyolefin blends were compression molded in an electrically heated Carver press 15 x 15 cm o~'Farrel'press 30.5 x 30.5 cm. The samples were molded between aluminum plates with an appropriate spacer to provide the r~quired thickness 0.25-3.8 mm. In one method the hot melt was taken directly from the mill roll and placed between two aluminum sheets. This was then placed in the press set at 1 90~C and pressed at high pressure (68-91 metric tonnes for the Farrel ~ress and 6820 kg for the"Carverpress). After three minutes the mold was placed in an unheated press at high pressure for three minutes. In the other proceJure, granulated rnaterial or pellets pro~uced from an extrusion ~o Haake or milling operation were dried and then compression n,olded.
The pr~ce~ure used was the same as for molding a melt except that a 5 minute preheat was us~d while ",ain~aining a slight pressure on the press. This was followed by the high pressure molding in the hot and cold pr~sses. A hot press of 1 90~C was usually sufficient for mfr=4 polypropylenes but hi~her viscosity polypropylenes would split during sag testing unless high~r ~"olJing temperatures were used (195-210~C).
Polyethylene was rllDlJeJ in a simJlar manner except that HDPE
was ~"olde~l at 170~C and LLDPE at 150~C.
* Trademark (each instance) 13~01~66 Injection molding of polypropylene was performed on a Newbury *
injection molding machine in an ASTM tamily mold. Material to be molded was dried for 16 hours at 60~C. The first barrel zone was set for 204~C, and the other two barrel zones and the nozzle were set for 21 8~C.
The ram time was set for 3 seconds and the cycle of 15 seconds for injection and 45 seconds overall was used. The injection pressure was 2100 kPa and the back pressure was 690 kPa. The screw speed was 100 rpm. Both mold platens were set for 60~C.
The sag tests are performed on a cGnlpression molded sheet 10 x 0 10 x 0.15 cm. This sheet was clamped in a frame with a 7.6-cm-square opening. There were metal rulers ~tlached to the front and back of the frame for use in measuring sag. The frame and sheet were placed in a hot, forced air oven (typically at 190~C). The amount of sag of the center of the sheet was then recorded as a function of time. Typically, the sag was first r~cG,Jed at 2.5 cm but for slow sag~;og materials sags as low as 16 mm were recorded. Data was recGnlsd up to 10.2 cm of sag or for 30 minutes, whichever oceurred first.
The terrn ~slope~ refers to the slope of a plot of the natural logarithm of the sag in centimeters versus time, resulting in a straight line.
A high slope indicates that the material sags quickly while a low slope indicates that it sags slowly. The advantage of comparing slopes in this manner is that it eliminates any di~erenc~s in oven cooling when the sample is introduced (due to differences in the time the oven is open, room te",peratures, etc.).
Crude thel",o~orl~,ing was done in the laboratory to illustrate this melt sl~n~t, effect. A sheet of polypropylene or modified polypropylene was heated in a forced air oven at 1 90~C, removed from the oven, placed over a female mold, and subjected to vacuum.
* Trademark '' 1~4006~
The capillary flow data were measured on a Sieglaff McKelvey rheometer. The flows were recorded at ten shear rates (1 to 100-reciprocal seconds) at each temperature. The data was fit to the power law, i.e., viscosity=k(temperature)X(shear rate)Y, and the values at 1 and 1000 reciprocal seconds were calculated from this best fit equation. The parallel plate viscosity refers to measurements on the"Rheometrics"*
Dynamic Spectrometer, recorded at a strain of 5%.
Differential scanning calorimeter (DSC) measurements of melting and nucleation were performed on a duPont instrument. A value of 59 caUg was used for the heat of cryst~ tion and per cent crystallinity was corrected for the presence of the melt additive. The nuclsetion temperature was measured in an experiment in which the polypropylene was melted at 200~C for 2 minutes and then cooled at 1 0~C/min. The temperature at which peak cryst~ tion occurred is called the nucleation temperatur~. The isothermal crystallization time was recorded by cooling the molten polypropylene quickly to 1 27~C and the exotherm recorded with time.
The physical properties of the polypropylene homopolymer and ~medium impact~ copolymer are determined on extruded and injection molded samples, although similar results have been observed in milled and compression molded samples. In certain examples below are described speci~ ed equipment for preparing foamed shset, rod or profile, extnuded rod or tubing, fibers, cast film, monoaxially oriented and biaxially oriented film, and injection blow-molded bottles or hollow containers.
The examples are intended to illustrate the present invention and not to limit it except as it is limited by the claims. All percentages are by weight unless otherwise specified and all reagents are of good commercial quality unbss otherwise specified.
* Trad~nark 13~0366 This example illustrates preparation of a Graft Copolymer (GCP) of Polypropylene (PP), Methyl Methacrylate (MMA) and Ethyl Acrylate (EA).
A polypropylene-acrylic graft copolymer is made by polymerizing a 5% ethyl acrylate (EA) - 95% methyl methacrylate (MMA) monomer mixture in the presdn~3 of polypropylene (weight ratio of polypropylene:monomer_ 0.67:1). Radicals are generated from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00010 moles per liter per minute (radical flux). Monomer and initiator are fed over 60 minutes and the theoretical (100% conversion) solids at the end of the reaction is 55%.
A 6.6 liter reactor e~ipped with a double he~ical agitator (115 rpm) was charged with 1780 9 of an inert hydrocarbon solvent mixture of 2-methylalkanes havin~ 6-12 C-atoms and 880 ~3 polypropylene (mfr=4) and heatsd to 1 75~C. After 2 hours the te",perdl-Jre was decreased to 1 55~C and ths batch was stirred for 1 additional hour. Over a two minute period two solutions were added. The first consisted of 1.04 9 of di-t-butyl peroxide in 21 9 ot the hy.Jroca~6Gn solvent. The second consisted of 0.06 g of di-t-butyl peroxide in 2.1 9 of sthyl acrylate and 42 9 of methyl ",ell,ac.ylate. For the next 58 minut~s at the same feed rate a feed of 1.87 9 ot di-t-butyl psroxide and 62 9 of sthyl acrylate in 1215 9 of methyl methacrylats was added at the same feed rate as the second feed. This feed schedule results in a radical flux of 0.00010 during the feed time.
After the feed was complete the reaction was held at 1 55~C for an additional 15 minutes. Then it was devolalilized by passing through a 30-mm"Wem~r-l~ g derer'~Ktruder with two vacuum vents at 200-250~C.
The conce~ltldle product (concenl,dte) is a mixture wherein the elemental analysis showed that the composition is 56% (meth)acrylate. Extractive results showsd 15.9% of the polymerized (meth)acrylic monomers were grafted, and ths Mw of ths (meth)acrylic polymer was 91,300. The * Trademark 1~40!~f~6 concentrate may be blended with other thermoplastic polymers such as polypropylene.
The following Table shows the efficiency of the above concentrate blended at different levels in improving sag resistance of a polypropylene homopolymer having a melt flow rate (mfr=4) of four.
T~RI F I
Wt. % of sag sample sag at concentrate slope, thickness 17 min time to in blend min-1 ( mm) (cm) sa~ 2.5cm 0 0.18 1.75 2.29 39 min 1.5 0.12 1.45 6.10 6.0 2.5 0.12 1.70 4.57 6.8 3.3 0.06 1.78 3.05 11.4 5.0 0.045 1.73 1.27 13.1 7.5 0.030 1.75 1.02 FXAMPI FS ~ - 51 A poly,urupylene acrylic graft copolymer i5 made by polyme~zing a 5% ethyl acrylate (EA,l - 95% methyl methacrylate (MMA) monomer mixture in the presence of polypropylene (weight ratio of polypropylens.,nonoi"er = 0.67:1). Radicals were generated from di-tertiary-butyl peruxic~e (DTBPO) at the rate of 0.00010 moles per liter per minute (radical flux). Monomer and initiator were fed over 60 minutes and the II eo,~t;cal (100% conversion) solids at the end of the reaction was 52.5Yo.
A 6.6 liter reactor equipped with a pitched-blade turbine ~git~or (375 rpm) was charg~l with 1880 9 hydrocarbon solvent and 840 9 13~006~
polypropylene and heated to 1 55~C. The mixture was stirred for 3 hours. Over a two minute period two solutions were added. The first consisled of 1.06 9 of di-t-butyl per~xiJ~ in 21 9 of hydrocarbon solvent, as in Example 1. The second consisted of 0.06 9 of di-t-butyl peroxide in 2.1 g of ethyl acrylate and 40 9 of methyl methacrylate. Forthe next 58 minutes a feed of 1.87 9 of di-t-butyl peroxide and 61 9 of ethyl acrylate in 1157 9 of methyl methacrylate was added at the same feed rate as the second feed. This feed schedule should produce a radical flux of 0.00010 during the feed time. After the feed was complete, the reaction was held at 1 70~C for an additional 15 minutes. Then it was devolatilized by passing through a 30 rnm'~lVerner-Pfleiderel"extruder with vacuum vents at 200-250~C. The concentrate showed that the co",posilion is 51% acrylate.
Additional polypropylene-acrylic graft copolymers (Examples 2-51 ) were p~pare.J by the pr~cedure of this Example and evaluated as 3.5% blends in polypropylene (mfr=4) as melt strength additives. The following Table illustrates the polymerization conditions for the concentrate and the p~rcent acrylic polymer present in the concenl-~le with the sag ~s;slancc of the blend with the polypropylene.
In the following Table ll, DTBPO is di(t-butyl)peroxide, TBPB is t-butyl perLen Gale, and DDBH is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.
* Tradel[ ark 1~40~fi~
TaRI F li sag % feed rad- %EA
slope acrylic init- solids polymer time, ical in Ex. ~in-1 in ~nc i~QC % ternp.~C m~ flux MMA
Con~ 0.15-0.18 -- ---- ---- ------ --- ---- ---0.03-0.05 56 DTBPO 55 155 60 0.00010 5 2 0.06 51 DTBPO 52.5 155 60 0.00010 5 3 0.06 52 DTBPO 55 155 60 0.00010 5 4 0.045 55 DTBPO 55 150 60 0.00010 5 0.08 57 DTBPO 55 145 60 0.00010 5 6 0.05 57 DTBPO 57 150 60 0.00010 5 7 0.10 49 DTBPO 55 150 60 0.00007 5 8 0.06 53 DTBPO 55 150 60 0.00015 5 9 0.06 55 DTBPO 55 150 60 0.00010 10 0.11 53 DTBPO 55 150 60 0.00010 0 11 0.056 48 DTBPO 55 155 60 0.00010 10 12 0.07 51 DTBPO 50 150 60 0.00010 5 13 0.11 58 DTBPO 55 145 120 0.00007 5 14 0.10 57 TBPB 55 145 120 0.00007 5 0.09 56 TBPB 55 150 120 0.00010 5 16 0.12 54 TBPB 55 150 120 0.00007 5 17 0.13 55 TBPB 55 150 120 0.00015 5 18 0.06 55 DTBPO 55 150 120 0.00007 5 19 0.06 49 TBPB 55 150 60 0.00010 5 0.10 51 TBPB 55 150 120 0.00010 5 21 0.14 57 TBPB 56 150 120 0.00010 5 22 0.13 5~ TBPB 55 150 60 0.00010 5 23 0.15 55 TBPB 55 150 120 0.00010 0 24 0.15 56 DDBH 55 150 120 0.00010 5 1 3 ~ O ~ fi b TARI F ll (continued) sag ~/O feed rad- %EA
slope acrylic init-solids polymer time, ical in Ex. ~3i~ in c~nc j~Q~ % temD.~C min fl~ MMA
0.14 57 TBPB 55 150 120 0.00015 5 26 0.09 51 TBPB 55 150 60 0.00010 5 27 0.15 54 DDBH 55 150 120 o.ooo10 o 28 0.11 51 DDBH 55 155 120 0.00010 5 29 0.10 53 DTBPO 50 150 120 0.00007 5 0.10 54 DTBPO 50 150 120 0.00005 5 31 0.15 53 DTBPO 50 150 120 0.00005 5 32 0.10 51 DTBPO 55 150 120 0.00007 5 33 0.12 55 TBPB 55 150 120 0.00007 5 34 0.18 55 DDBH 55 150 120 0.00007 5 0.07 53 DTBPO 55 150 120 0.00005 5 36 0.09 51 DTBPO 55 150 120 0.00010 5 37 0.14 51 TBPB 55 150 120 0.00005 5 38 0.10 37 DTBPO 55 155 60 0.00010 5 39 0.11 43 DTBPO 55 155 120 0.00007 5 0.08 48 DTBPO 55 155 120 0.00005 5 41 0.10 47 DTBPO 55 155 120 0.00007 5 42 0.07 48 DTBPO 55 155 60 0.00010 5 43 0.10 43 DTBPO 55 155 120 0.00005 5 44 0.10 50 DTBPO 55 155 120 0.00007 5 0.10 54 DTBPO 55 t 50 120 0.00010 5 46 0.10 54 DTBPO 55 150 120 0.00007 5 47 0.07 54 DTBPO 55 150 120 0.00005 5 48 0.08 56 DTBPO 55 150 120 0.00007 5 49 0.08 55 DTBPO 55 145 120 0.00007 5 TABlFll(co~inued) " ,"" , , .. ~ . ,. ~ . ~ .. .. .. .... . . .. . . . . .
13~0~6~
sag % feed rad- %EA
slope acrylic init- solids polymer time, ical in Ex. min-~ in eonc I~QC . % temp.~C m~ f!~ MMA
0.09 56 DTBPO 55 145 120 0.00005 5 51 0.08 55 DTBPO 55 145 120 0.00010 5 Control = PP with no concentldle The r~lclJl~ted percent of grafted acrylic polymer and the molecular weight (Mw) of ungrafted acrylic material are tabulated below in Table lll on certain samples where the ungrafted acrylic polymer was separated from the concentrate by extraction.
T~RI F 111 % Acrylic Polymer Fx~m~le Gr~fted to PP ~
2 12.3 107,000 10.6 119,000 11 29.8 71,800 14.8 . 43~000 46 10.7 62,600 47 21.7 87,300 Note: (Mw = weight average molecular weight) ~ This example shows a larger seale prepardlion of a polypropylene-acrylie ~raît copolymer made by poly...6rl~ing a 5% ethyl aerylate (EA) - 95%
methyl mt~hacryla~e (MMA) monomer mixture in the pr~senee of polypropylene (weight ratio of polypropylene:monomer . 0.67:1). Fl~di&~ls were generated 1~4006~
from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.000065 moles per liter per minute (radical flux). Monomer and initiator were fed over 122 minutes and the theoretical (100% conversion) solids at the end of the reaction was 47%.
A 380 liter reactor equipped with a back-slope turbine agitator was charged with 102.3 kg of the hydrocarbon solvent and 36.4 kg of mfr=4 polypropylene homopolymer and heated to 150~C over 4 hours. Two solutions were added over a twenty minute period. The first consisted of 82 9 of di-tertiary-butyl peroxide in 826 9 of the hydrocarbon solvsnt. The second consisted of 454 g of EA and 8.6 kg of MMA. Addition of the first solution was then continuedo at a lower rate to feed an additional 82 g of di-tertiary-butyl peroxide and 826 9 of the hydrocarbon solvent over 90 minutes. At the same time the monomer addition of 2.3 kg of EA and 47.5 kg of MMA was continued over 102 minutes (ending 12 minutes aft~r the initiator feed had finished). The reaction was heldat 150~C foran ~drlitional 15 minutes. Then an additional 23 kg of hydrocarbon solvent was pumped in over 30 minutes. The reaction mixture was then devol~ ed by passin~ through a 20-mm Welding Engineers twin-screw extruder at 200 rpm and 200-250~C over 14 hours. This concentrate is Ex. 52.
Similar preparations labelled 53 and 54 were synthesized with changes in feed time and radical flux as in~ te~l The following Table IV shows the improvement in sag ~s;stance when concenl,dtes of Example 52, 53 and 54 are blended with polypropylene of mfr=4:
134Q06n T~Rl F IV
% Weight Conc Sag Fraction in Slope Acrylic Init- Polymer Feed Rad.
~, Blend min~ conc. iator Sglids temp Time Flux Con. none 0.19 --52 2.5 0.1 1 0.6 DTBPO 47 1 50 122 0.000065 3.5 0.10 53 3.5 0. 11 0.6 DTBPO 45 150 90 0.00007 ~.0 0.10 54 3.~ 0.15 0.6 DTBPO 49 150 78 0.00008 5.0 0.09 FxAMPl F 55 This example and Table V demonstrate the unexpected advantage of the concentrate of Exampb 4 in the improvement of sag resistance for both high density polyethylene (HDPE) and linear low density polyethylene (LLDPE). Data for HDPE are for polymers of two different mfr values (4 and 8) and are obtained at 1 ~0~C, The LLDPE
values are on a single resin having a density of 0.917 g/cc, but at two different t~mperatures. Comparison molded polyethylene samples prepared for this test hsd a significarlt inel~ase in gloss over the unmodified control.
1340~6~
TARI F V
Time to Sag. Minutes PoyethyleneWt-%~rlitive Te~ ~C 508 mm 76? mm HDPE, mfr=8 0 150 8.7 9.3 2 10.2 11.9 3 5 15.8 30.0 31.4 HDPE, mfr=4 0 150 8.0 9.0 3.5 10.5 12.0 26.0 --LLDPE mfr=2 0 170 5.3 6.0 17.7 21.4 LLDPE, mfr=2 0 180 4.6 5.2 8.5 10.0 AMpl F 56 A polyethylene-acrylic graft copolymer concentrate was s~n~hesi~ed in a manner similar to that previously described for polypropylene-acrylic ~raft copolymers. The polyethylene-acrylic graft copolymer concentratl3 was made by polymerizing a 100% methyl ~o methacrylate (MMA) monomer mixture in the presence of polyethylene (weight ratio of polyethylene:monomer . 0.5:1). Radicals were gener~led from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00010 moles per liter per minute (radical flux). Mono",er and initiator were fed over 60 minutes ar~d the theor~lical (100% conversion) solids at the end of the r~aclion was 55%.
A 6.6 liter reactor e~uirped with a double helical agitator (115 rpm) was charged with 1760 9 hydrocarbon solvent and 725 9 1~40~6fi polyethylene (mfr-4 density=0.95) and heated to 1 50~C. The mixture was stirred for 3 hours. Over a two minute period two solutions were added. The first consisted of 1.63 g of di-t-butyl peroxide in 48 g of methyl "~el~acrylate. For the next 58 minutes a feed of 1.73 g of di-t-butyl peroxide in 1401 9 of methyl methacrylate was added at the same feed rate as the second feed. This feed schedule should produce a radical flux of 0.00010 during the feed time. After the feed was complete the reaction was held at 1 50~C for an additional 15 minutes.
Then it was devolati';zed by passing through a 30-mm Werner-o Pfleiderer extruder with vacuum vsnts at 200-250~C The elemental analysis showed that the concentrate contained 64% (meth~acrylate.
This example shows that both polyethylene-acrylic graft polymer and polypropylene-acrylic graft polymer concenll~te were effective at reducing the sag of HDPE. The blend of concenlldte with HDPE mfr=4 and density=0.95 was milled at 220~C and the hot material from the mill was molded at 21 0~C. Sags were measured by the same pr~cedure used for polypropylen~ sheet except that an oven temperature of 150~C
was used.
T~RI F Vl Concentrate Sag Slope 25.4 mm Sag 76.2 mm Sag of Fx~rnple %Conc. ~_ (min! (min) Control none 0.57 7.4 9.4 56 5% 0.27 9.0 13.0 56 10% 0.1110.0 19.8 4 5% <0.015 15.0 30 min to 31.7 mm 134006~
This example shows that the polyethylene and polypropylene graft copolymer concentrates are effective in improving sag resistance of HDPE while ungrafted acrylic polymer of similar MW iS not. Addition of as much as 5% of a commercial acrylic molding powder poly(methyl methacrylate) Mw 105 000 designaled ~A~) showed no decrease in sag rate while 3% poly(methyl methacrylate) present as the graft copolymer concentrate resulted in large reductions of sag rate.
The specific concentrate used in part of this study was synthesized in the following manner. The polypropylene-acrylic graft copolymer was made by pol~""eri~iny a 5~/O ethyl acrylate (EA) - 95% methyl methacrylate (MMA) monomer mixture in the presence of polypropylene of mfr=0.4 (weight ratio of polypropylene:monomer= 0.67:1). Radicals were generated from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00007 moles per liter per minute (radical flux). Monomer and initiator were fed over 120 minutes and the theoretical (100% conversion) solids at the end of the r~actbn was 55%.
A 6.6 liter reactor equipperl with a pitched-blade turbine agitator (375 rpm) was charged with 1780 9 of the hydrocarbon solvent and 880 9 polypropylene (mfr=0.4) and heated to 1 60~C. The mixture was stirred for 2 hours and then the temperature was decreased to 1 50~C for one hour. Over a two minute period two solutions were added. The first consisted of 1.22 9 Of di-t-butyl peroxide in 20 9 of the hydluca,bon solvent. The second ~nsi.~ted of 0.0002 mg of ,nonGi"ethyl ether of hydroquinone (MEHQ) and 0.05 9 of di-t-butyl peroxide in 1.1 9 of ethyl acrylate and 21 9 of mllthyl ",elhac~ylate. Forthe next 118 minutes a feed of 13 rng MEHQ and 2.70 9 of di-t-butyl peroxide in 66 9 of ethyl acrylate and 1253 9 of methyl ",ell,aclylate was added at the same feed 13400~
rate as the second feed. This feed schedule should produce a radical flux of 0.00007 during the feed time. After the feed was complete the reaction was held at 150~C for an additional 15 minutes. Then it was devol~ti';~ed by passing through a 30 mm Wemer-Pfleiderer extruder with two vacuum vents at 200-250~C. The elemental analysis showed that the concentrate contained 53% (meth)acrylate.
The blends of HDPE (mfr=7, density=0.95) and graft copolymer concentrate was milled at 200~C and the hot materials were formed into sheets from the mill at 170~C. Sa~s w~lre measured by the same o procedure used for polypropylene sheet except that an oven temperature of 150~C was used.
TARI F Vll Concentrate Sag Slope25.4 mm 50.8mm Fxs~le 1 ~vel min-~ .cz~5~ ¢min) ~ rnin) Control none 0.59 7.4 8.7 A 3.0% 0.58 7.1 8.3 A 5.0% 0.54 7.6 9.0 56 5.0% 0.27 -- 10.3 4 2.0% 0.28 8.2 10.2 4 3.5% 0.056 9.4 15.8 4 5.0% 0.038 10.4 31.4 58 3.5% 0.37 7.4 9.2 58 5.0% 0.30 8.1 10.0 .~ . . , . ., ., . "~. . . . ..
The concentrate of Example 4 was blended with LLDPE and the results of evaluating the sag resistance improvements are shown below in Table Vlll. The blenJ of modifier and LLDPE was milled at 170~C and the hot material from the mill was milled at 150~C. Sag resistance was measured by the same procedure used for polypropylene sheet at the temperature listed.
~A~ is an LLDPE having an mfr=2.3 and a density of 0.92, recommended for casting and extruding applications.
~B~ is an LLDPE having an mfr=1 and a density of 0.92, recommended for blow molding and extn~sion applications.
T~RI F Vlll Sag Sag Slope25.4 mm 101.6 mm npF ConcentPte Temo. ~1 sa~ (min~ sa~ (min) A none 1 80~C 0.58 3.4 5.6 A 5% Ex. 4 180~C 0.24 5.2 10.6 A none 1 70~C 0.54 3.9 6.4 A 5% Ex. 4 170~C 0.096 9.5 23.0 B none 1 50~C --- 7.8 15.6 B 5% Ex. 4 1 50~C --- 33.7 min at 19 mm FxAMpl F 60 This example illllsl,dtes improved sag modilicalion and increased nuc'a~ion te",p6r~tur~ for polybutylene, when blended with the concenll~te. Polybut~rJene, injection grade, mfr~4, with and without 2.44 wt. % of the concentr~le of Example 20 were milled at 1 90~C and ... ~, . , . . ,~ ..... . .....
1 3 4D0~ 6 pressed into plnqlJes of about 1.7 mm thickness. Times were measured for various distances of sag at 1 45~C. DSC curves were used (heaVcool time = 20~C/min). A higher crystallization temperature relates to increased speed of nucleation and solidification of the heated polymer.
T~RI F IX
Weight Percent rlme to ~C~9 ~nin:~e~ nsc Tem~er~tllre. oc Concentr~te ~5.4mm 50.~mm 101.6mm ~!~ Cryst~llize Control (0) 5:20 7:50 10:23 128 45 2.44 wt % 7:24 15:53 ~30 129 55 This example describes the preparalion of a concentrate of polypropylene-acrylic graft copolymer made by polymerizing 5% ethyl acrylate (EA) - 95% methyl methacrylate (MMA) monomer mixture in the presence of an equal amount of polypropylene. Radicals were gel)erdted from di-tertiary-butyl peroxide (DTBPO) at the rate of 0.00017 moles per liter per minute (radical flux). Monomer and initiator were fed over 30 minutes and the lheore~ical (100% conversion) solids at the end Of the rea~tion was 50%.
A 6.6 liter reactor eq~ipped with a double helical agitator (115 rpm) was chalged with 1980 9 of the hydrocarbon solvent and heated to 1 70~C. 1000 9 of polyprupylene (mfr,5) was fed to the reactor via a melt extruder set ar 200~C at a rate of about 10 ~ per minute. After 45 minutes hold at 170~C the a~hJitiûn of .,.ono",er and initiator solutions was begun. Over a two minute period two solutions were added. The first consisled of 0.44 9 of di-t-butyl peroxide in 21 9 of the h~d~ûca,Lon 13400fi~
solvent. The second consisted ot 0.11 9 of di-t-butyl peroxide in 1.3 9 of ethyl acrylate and 65 g of methyl methacrylate. For the next 28 minutes a feed of 1.59 9 of di-t-butyl peroxide and 19 9 of ethyl acrylate in 914 9 of methyl methacrylate was added at the same feed rate as the second feed. This feed schedule should produce a radical flux of 0.00017 during the feed. After the feed was complets the reaction was held at 170~C for an additional 15 minutes. Then it was devol~ ed by passing through a 3~mm Werner Pfleiderer extruder with vacuum vents at 200-250~C. The elemental analysis (carbon content) showed o that the concentrate contained 35% (meth)acrylate.
A sheet of polypropylene (mfr=4) with and without the concentrate of this example was heated in a forced air oven to 1 90~C removed from the oven and immediately placed over a female mold and subjected to vacuum. The top and bottom comer measurements were the average of the 8 measw~",ent~ in mm at the corner of each of the four side faces of the box. The top and bottom center measurements were the average of the 4 measurements in mm at the center of the edge of the 4 faces of the box. These measurements are summarized in Table X and demonstrate smaller wall thickness vall~iGns when the concentrate is present.
TARI FX
WAI I THICKNFSS VARIATI~N IN THFRMoFoRMFn PARTS
Top Top Bottom Bottom Poly~ro~ylene Center Corner Cent_~ Corner unmodified 1.14 mm 0.88 mm 0.75 mm 0.025 mm 5%Ex. 61 0.97mm 0.97 mm 0.35 mm 0.21 mm 134Q~fi~
This example demonstl~led the unexpected higher nucleation temperature and shorter time for crystn" ~tion imparted by addition of the polymeric concentrate of Examples 1 and 52 to polypropylene of mfrz4. The nuc'3~tion temperature was measured while cooling at 10~C/min, the melting temperature was measured while heating at 20~C/min and the crystallization time was measured isothermally at 127~C or 130~C. The extent of crystallization was reported for both cooling and melting measurements. Coi"palison was made with o ungrafted PMMA of similar Mw.
TABI F Xl Temp. of crystallization (~C) 127 127 130 130 130 130 130 Percent Concentrate 0 5 0 1.1 2.2 3.9 7.8 PolymerConcentrate of Example - 52 - 52 52 PMMAPMMA
Cry~ ;Gn Time, min. 16.3 3.6 24.5 3.7 3.0 8.1 10.6 rlua'a~tionTemperature,~C 105 112 107 118 118 112 110 % Crystallinity 39 40 41 46 42 42 41 Melting Temperature, ~C 165 166 169 170 168 170 168 % Crystallinity 41 44 44 44 46 46 44 This example demonsl.c.led the lower equilibrium torque and improvement in time to flux for blends of the concentrate of Example 1 with polypropylene of mfr=4 using the Haake Rheocordl'*The test conditions are described above. Peak torque at flux was also re~uce~l * Trademark 1340U6~
T~RI F Xll Wt.-%
Concentrate in Time to flux Equilibrium Torque Poly~roDylene (seconds) (meter-~r~ms ~t 21 5c o 109 695 FXAMpl F 64 This example shows that a propylene-acrylic graft copolymer concentrate may be used to improve the sag resistance of an acrylic sheet. About 20 parts of the graft polymer of Example 1 was milled with 100 parts of a commercial acrylic molding powder of Mw 105,000 and cG,-,pression molded. Sag tests indicated that the sheet containing the concentrate may be heated to about 5-10~C higher before flow equivalent to that of the unmodified sheet was observed.
FxAMpl FS 65 - 66 Graft copolymer concentrates were prepared according to the process clesc~ibed in Examples 52-54, using the conditions shown in Table Xlll.
1~40066 TARI F Xlll Monomer Feed Concentrate % AcrylicInit- Time Radical of FY~nlDle InCon~ Solids Tem~. ~C (min) ~!~
A 55 DTBPO 50% 150 120 0.00010 B 55 DTBPO 50% 150 120 0.00007 Concentrates A and B were blendsd together at a weight ratio of 2.8:1 to form concentrate C. As indicated in Table XIV, concentrate C
was blended at the 4~~ level with polypropylene and the indicated amounts of di-t-dodecyl disulhde (DTDDS) and extruded. The sag 0 results for these blends are given in Table XIV below.
T~RI F XIV
Fx~mDle % Conc~ntr~te nTDDSSa~ Slope in min-4 none 0.07 66 4 0.03% 0.05 67 4 0.3% 0.03 Stabilizing the concentrate during processing, as by using the DTDDS, is seen to produce even more significant improvement in melt strength.
~ This example further de",Gnsl.d~es that the graft copolymer has little effect on the high-$hear vi5cosi~y but a pronounced effect on law-shear viscosil~ in polypropylene.
1 3 4 0 0 fi ~
The graft copolymer of Example 1 was admixed at the five weight-percent levei with an injection-moldin~ grade of propylene hoi.,opolymer, mfr.4, as in Example 63. Capillary and parallel-plate viscosities were measured at various temperatures under conditions described above, under both low and high shear conditions. The results shown in Table XV below demonstrate the increase in low shear viscosity, especially at temperatures below about 210 ~C, with essentially no effect on viscosity at high shear rate.
TARI F XV
Conditions~ w Shear High Shear AmountofGraftPolymer: o % 5 % o % 5%
Test Terr~per~ture Capillary Viscosity (a) 180 ~C94000 133000 1900 2000 Capillary Viscosity~a~ 190 ~C80000 110000 1900 1600 Capillary Viscosity (a) 210 ~C57000 75000 1200 1 100 Parallel Plate Viscosity(b) 190 ~C63000 99000 2100 2100 Parallel Plate Viscosity (b) 210 ~C54000 58000 1800 1800 Parallel Plate Viscosity (b) 230 ~C37000 39000 ~ 500 1400 Shear Conditions:
a: Low Shear=1.0 sec-1; high shear5 1000 se~
b: Low Shear=0.1 sec-~; high shear= 500 sec-~
FxAMpl F 68 This example shows irnproved stabilization to weight loss on heating by use of a disulfide or a sub~tuted tri~ine st~hili7er. A
polypropylene-acrylic graft copolymer similar to that of Example 4 was blended with 5~h ' >ers on the mill roll. The graft copolymer (98 grams) was fluxed on the mill at 1 95~C. The stahili7er (2 grams) was added and blended in for 2 minutes. The material was removed from the mill, cut into chunks, and granulated. One or more of these stabilized versions were then let down in a similar manner in additional graft copolymer to produce graft copolymer stabilized at the 100-5000 ppm level. The results on the TGA of stabilkation are shown in the table.
Weight loss (%) is the temperature at which the particular percent weight loss is observed, utilizing i DuPont ThermoGravimetric Analyzer *
at a heating rate of 20~C in nitrogen. Although none of the stabilizers O were deleterious to stability, only those designated 2 and 7 exhibited significant stability advantages.
The stabilizers studied were:
1. DLTDP (dilauryl thiodipropionate);
2. TNPP (trisnonylphenyl phosphite);
3. " Irganox"1010 (tetrakis(methylene(3,5-di-t-butyl-4-hydroxy-hydrocinnamate))methane);
4. DTDDS (di-t-dodecyldisulfide);
5. " Irgafo~'168 (tris-(2,4-di-t-butylphenyl)phosphite);
6." Westori'618 (di-stearyl ~ntaerythritol diphosphile);
7."Cyanox 1790 (tris(4-t-butyl-3-hydroxy-2,6 dimethylbenzyl)-s-tri~ine-2,4,6-(1 H,3H,5H)-trione;
8. " l~ yanox '~ 076 (G~ -de~rl 3,6-di-t-butyl-4-hydroxyhydrocinnamate);
9. TopanofCA (3:1 oondensate of 3-methyl-6-t-butylphenol with crotonaldehyde.
* Trad~nark (each instance).
' 1340066 TARI F XVI
WEIGHT LOSS
STA8ILIZER (PPM) TEMPERATURE
- - tDEGREES C~
1 % 10 %
2000 300 . 291 358 , ,, . . . .~, ,, ~ ~
1340~66 T~RI F XVI (contin~lerV
WEIGHT LOSS
STABILIZER (PPM) TEMPERATURE
- - - - (DEGREES C) 1 % 10 %
600 2000 282 325.
2000 ~ 4000 291 331 FXAMpl F 69 This example illustrates the pf~paralion of a larger amount of graft copolymer to be used in many of the following studies. The process and composition of Example 52 was followed with some variations. Several preparations were combined. In all but the last of these preparations, radicals are generated at the rate of 0.000070 moles per liter per minute (radical flux).Monomer and initiator are fed over 120 minutss and the theoretical (100%) conversion) solids at the end of the reaction is 50%.
A 380-liter reactor equipped with a pitched-blade turbine agitator was charged with 86.4 kg of the hydrocarbon solvent ana 34.5 kg of polypropylene homopolymer, mfr=4. After deoxygenating (applying vacuum to degas, followed by pressurizing with nitro~en to atmospheric pressure) through three cycles, it was pressurized to 103 kPa with nitrogen and heated to 150~C over 2 hours. A pressure of 241 kPa was maintained while the batch was held at 150~C for 3 hours. Two solutions were added over a fifteen minute period. The first consisted of 59 g of DTBPO in 841 g of the hydrocarbon solvent. The second consisted of 0.32 kg of ethyl ac~late and 6.14 kg of methyl methacrylate. Addition of the first solution was then continued at a lower rate to feed an additional 103 9 of DTBPO and 1479 9 of the hydrocarbon solvent over 105.minutes. At the same time the monomer addition of 2.26 kg of ethyl acrylate and 43.0 kg of methyl ~"elh~crylate was continued over 105 minutes.
Reaction oxotherm increased the temperature to about 160~C. After the feed was complete, 5 kg of the hydrocarbon solvent was fed into the reaction mixture.
The reaction mixture was held in the reaction kettle for an additional 30 minutes. It was then transler,ed to a second kettle which was also under pressure at 150~C. During the l-an:.ler a solution of 80 g of di-tertiary dodecyl disulfide in 320 9 of the hydrocarbon solvent was added to the second kettle.
Also during this transfer three 4.53 kg pGi tions of the hydrocarbon solvent were ~.~ . .. , .. . . .. ., ... .... ~
13~qO~
fed into the reaction kettle. Material in this second kettle was ~ed to a 20.3-mm Welding Engineers twin-screw extruder where devolatilization occurred.
During the devolatilization the next batch was prepared in the reaction kettle. It was transferrsd to the extruder feed kettle while extrusion continued.
In this manner several batches were made in a ~semi-batch" manner, that is, ba~chwise in the reactor with continuous feed to the extruder.
In the final preparation of the blend, radical flux was 0.000050 (42 g DTBPO + 858 g of th~ hydrocarbon solvent in the first feed, 73 g DTBPO +
- 1502 g of the hydrocarbon solvent in the second feed).
o The final blend, designated Example 69, was prepared by blending pellets from 13 batches prepared as described and one batch of the final variant. All samples from individual batches gave acceplable sag resistance when tested in polypropylene.
The following example illustrates that improved stability can be imparted to the graft copolymers of the present invention by copolymerization of an alkylthioalkyl ",GnG-"er, specifically ethylll,;Getl,yl methacrylate.
The stability of graft copolymers prepared with alternate monomer coi~,posilions was also ev~u~ted All were prepared according to the pruce~ure for Example 4, except that the ",onGmer composition varied and the product was isolated by evaporating solvent instead of by devolatilizing in an extruder. The monom~r compositions and the TGA results are summarized in the table below. The abbreviation EA indicates ethyl acrylate; MMA=methyl ,llath~rylate; ETEMA~ ethylthioethyl Ill~tl aclylate and MA= methyl acrylate.
Weight loss (%) is the t~illper~llJre at which the particular percenl weight loss is observed, utilizing a DuPont ThermoGravimetric Analyzer at a heating rate of 20~C in nitrogen.
13~006~
TABI F XVII
Grafted Acrylic Temperature at Which Noted Percent Weight Pol ym~r T.oss Occurs ~y TG~ ~n~lysis (~C~
1 % 2 % 5 % lO
95% MMA, 5% EA 221 274 307 333 95% MMA, 5% EA + 260 289 314 346 O.05% ETEMA
95% MMA, 5% EA + 281 305 335 360 O.25% ETEMA
* Trad~nark (each instance).
' 1340066 TARI F XVI
WEIGHT LOSS
STA8ILIZER (PPM) TEMPERATURE
- - tDEGREES C~
1 % 10 %
2000 300 . 291 358 , ,, . . . .~, ,, ~ ~
1340~66 T~RI F XVI (contin~lerV
WEIGHT LOSS
STABILIZER (PPM) TEMPERATURE
- - - - (DEGREES C) 1 % 10 %
600 2000 282 325.
2000 ~ 4000 291 331 FXAMpl F 69 This example illustrates the pf~paralion of a larger amount of graft copolymer to be used in many of the following studies. The process and composition of Example 52 was followed with some variations. Several preparations were combined. In all but the last of these preparations, radicals are generated at the rate of 0.000070 moles per liter per minute (radical flux).Monomer and initiator are fed over 120 minutss and the theoretical (100%) conversion) solids at the end of the reaction is 50%.
A 380-liter reactor equipped with a pitched-blade turbine agitator was charged with 86.4 kg of the hydrocarbon solvent ana 34.5 kg of polypropylene homopolymer, mfr=4. After deoxygenating (applying vacuum to degas, followed by pressurizing with nitro~en to atmospheric pressure) through three cycles, it was pressurized to 103 kPa with nitrogen and heated to 150~C over 2 hours. A pressure of 241 kPa was maintained while the batch was held at 150~C for 3 hours. Two solutions were added over a fifteen minute period. The first consisted of 59 g of DTBPO in 841 g of the hydrocarbon solvent. The second consisted of 0.32 kg of ethyl ac~late and 6.14 kg of methyl methacrylate. Addition of the first solution was then continued at a lower rate to feed an additional 103 9 of DTBPO and 1479 9 of the hydrocarbon solvent over 105.minutes. At the same time the monomer addition of 2.26 kg of ethyl acrylate and 43.0 kg of methyl ~"elh~crylate was continued over 105 minutes.
Reaction oxotherm increased the temperature to about 160~C. After the feed was complete, 5 kg of the hydrocarbon solvent was fed into the reaction mixture.
The reaction mixture was held in the reaction kettle for an additional 30 minutes. It was then transler,ed to a second kettle which was also under pressure at 150~C. During the l-an:.ler a solution of 80 g of di-tertiary dodecyl disulfide in 320 9 of the hydrocarbon solvent was added to the second kettle.
Also during this transfer three 4.53 kg pGi tions of the hydrocarbon solvent were ~.~ . .. , .. . . .. ., ... .... ~
13~qO~
fed into the reaction kettle. Material in this second kettle was ~ed to a 20.3-mm Welding Engineers twin-screw extruder where devolatilization occurred.
During the devolatilization the next batch was prepared in the reaction kettle. It was transferrsd to the extruder feed kettle while extrusion continued.
In this manner several batches were made in a ~semi-batch" manner, that is, ba~chwise in the reactor with continuous feed to the extruder.
In the final preparation of the blend, radical flux was 0.000050 (42 g DTBPO + 858 g of th~ hydrocarbon solvent in the first feed, 73 g DTBPO +
- 1502 g of the hydrocarbon solvent in the second feed).
o The final blend, designated Example 69, was prepared by blending pellets from 13 batches prepared as described and one batch of the final variant. All samples from individual batches gave acceplable sag resistance when tested in polypropylene.
The following example illustrates that improved stability can be imparted to the graft copolymers of the present invention by copolymerization of an alkylthioalkyl ",GnG-"er, specifically ethylll,;Getl,yl methacrylate.
The stability of graft copolymers prepared with alternate monomer coi~,posilions was also ev~u~ted All were prepared according to the pruce~ure for Example 4, except that the ",onGmer composition varied and the product was isolated by evaporating solvent instead of by devolatilizing in an extruder. The monom~r compositions and the TGA results are summarized in the table below. The abbreviation EA indicates ethyl acrylate; MMA=methyl ,llath~rylate; ETEMA~ ethylthioethyl Ill~tl aclylate and MA= methyl acrylate.
Weight loss (%) is the t~illper~llJre at which the particular percenl weight loss is observed, utilizing a DuPont ThermoGravimetric Analyzer at a heating rate of 20~C in nitrogen.
13~006~
TABI F XVII
Grafted Acrylic Temperature at Which Noted Percent Weight Pol ym~r T.oss Occurs ~y TG~ ~n~lysis (~C~
1 % 2 % 5 % lO
95% MMA, 5% EA 221 274 307 333 95% MMA, 5% EA + 260 289 314 346 O.05% ETEMA
95% MMA, 5% EA + 281 305 335 360 O.25% ETEMA
10 95% MMA, 5% MA . 254 290 317 325 FXAMPlF 71 This example illustrates that an alternative method reported for the preparation of ",elhacrylic ester//polyolefin graft copolymers does not produce a polymer us~ful in improving r~slance to sagging of polypropylene. Example2OfU.S. Patent 2,987,501 was repeated, wherei:n linear low-density polyethylene homopolymer (mfr-2.3) was immersed in fuming nitric acid for 30 minutes at 70~C removed washed with water and dried. The treated polyethylene was then suspended over retluxing methyl methacrylate for 4 hours. The polyme! was extracted with methyl ethyl ketone, as taught in the reference, to remove ungrafted poly(methyl ",ell,acrylate). The molecular weight of the unglafled polymer was det~r "ined by gel pe".,ealion chrumatG~r~phy to be Mw,430 000 Mn 1 70 000.
~ .. . .. . . . ~ . .
T~RI F XVIII
Weight of Weight before Weight after Weight polyethylene, reaction (after reaction and of polymer g. nitr~t;~n), ~. extr~ction. ~ extr~cte~
3.397 3.48 5.964 4.40 Thus, the graft copolymer formed was 43~/O PMMA and 57% PE. The total sample prior to extraction was 67% PMMA, 33% PE, and the efficiency of grd~ling of the PMMA was 63.1%.
The resultant graft polymer, from which the ungrafted polymer had not been removed, was blended at the 4% level into the polypropylene resin of mfr=4 used as a standard for testing sag ,~sistance. The graft copolymer of thisexample did not r~isF~rse well, and visible, large, undispersed fragments were seen. The sag value (0.31 ) was worse than for the ~"""odified resin (0.1~) or for resin modified with an equivalent amount of the graft copolymer of Example 69 (0.02).
The graft copolymer of this example was also milled into linear low-density polyethylene (mfr 2.3) in the mannsr taught in Example 59. Poor disper:,;on in polyethybne was also notsd, with large chunks of the undispersed modifier visible. Sag r~si-~ance was determined at 150~C as in Example 59; sag for the unmodified control (by the sag slope test) was 0.39, and for the graft copolymer of this example, 0.23. By comparison, sag when using the graft copoly",er of Exampls 4 would be expected to be well below 0.10.
1~4Qo6~
FXAMPI FS 7~ - 77 This example illustrates preparation of blends of graft copolymer with polypropylene resins to form pellets useful for hrther processing into extruded or molded articles.
The graft copolymer of Example 69, not separated from any ungrafted polypropylene or acryNc polymer, was used as 3.2-mm-long pellets cut from an extruded strand.
The polypropylene resins used were~Aristech~1-4020F (Aristech Chemical Corporation, Pittsburgh, PA),'l limontR6523 (Himont Corporation, o Wilmington, Delaware), and'l:texene 1 4S4A (Rexene Corporation, Dallas, TX).
Characteristics are shown in Table Xlll; the term ~copolymer~ in the table means a copolymer with ethylene.
The graft copoly.~,er was blended at 5% with the polypropylene resins by tumbling. The blend was then extruded into slldnds through an~Egan 60-l'*
mm, twin-screw extnuder e~luirped with screws of 32:1 length/diameter ratio;
the strands were cooled and chopped into pellets. Various feed rates and screw speeds we~ utiJized. Con.Jitions for the unmodified and modified resins used to obtain large-scale samples are summarized in Table XIV. Sag tests as described in Example 1 were conducted on several other samples of modified resin p.oc~ssed under varying conditions, and the results were comparable to those ~epo,led below in Table XIX.
* Trade~ rk (each instance).
134006~
T~RI F XIX
~l~n~.~ of PolyDropylene With Met~yl MethAcrylAte GrAft Copolymer ~nd Controls Ex. 69 ExampleGraft, Polypropylene MAtrix Res;n Sag ph r Name MFR Comnosition 72 -- Aristech TI-4020F 2 copolymer 0.23 73 5 0.02 74 -- Himont 6523 4 homopolymer0.36 0.11*
76 -- Rexene 14S4A 4 copolymer0.35 77 5 0.14 ~ Sample tore on testing; other blends processed at slightly different conditions gave sags of 0.06 to 0.09.
TARI F XX
Processing Cnn~;tions for Pre-Rlen~s of T~hle XIX
Example: 72 73 74 ~ 76 77 Modifier: -- 5% -- 5% -- 5%
Feed Rate, kg/hr (Set)90.7181.9 90. 7 181.4 181.4 181.4 Feed Rate (actual) 90.2 185 89.8 181.4 178.7 182.3 Screw Speeds 101 200 100 200 200 Drive Amps 103 121 97 111 112 112 lO Kg-m/sl 1258 3033 1184 2811 2811 2811 Head Pressure (kPa) 2137 2758 1448 2068 2275 2206 Barrel Temps. ~~C) Zone 1 163 163 163 163 163 163 Zones 2 - 8 204 204 204 204 204 204 15 Die 204 204 204 204 204 204 Melt Temp. ~C 213 222 208 216 217 217 1 - Power aiJ r' 0d to extruder screw.
This example illustrates pr~paralions of blends of graft copolymer 20 with other polypropylene resins on different compounding equipment to form pellets useful for turther processing into film or profile. The~lAmoco~*
6214 is a film grade polypropylene rssin conl~ning a clarifier. The Eastman 4E1 1~is an impact-extrusion grade, propylene-ethylene-copolymer resin used in profile extrusion. In the present case, both 1%
25 and 5% by weight of the graft copolymer described in Example 69 were used to form the blends.
* Trademark ** Trademark The two polymers were tumble blended, and the mixtures fed to an 83 mm"Wemer rfi~'derer'~o-rotating, intermeshing, twin-screw extnuder of 24/1 Ud ratio. The pellets were continuously fed to the extruder by means of an~lAcrison~loss-in weigl)l feeder~, melted and mixed in the extruder, extruded through a 33-strand die, cooled in a water trough, dried, pelletized, and packaged. The machine conditions for the individual batches are as follows:
TABI F XXI
Co~Dos;tions of Rlen~.s ~n~ M~trlx PoLymers ~x~m~le % M~;fier ~tr;x Polymer 78 -- "Eastman"4E11 Copolymer 81 -- "Amoco 6214"Homopolymer * Trademark TARI F XXII
PreparAtive Con~itions for V~rious Blen~.~ of TAhle XXI
T~m~erature. ~C
Ex.79 Zone set ~oint/ActuAl Con~;tions Z-l 229 / 229 RPM- 125 Z-2 235 / 216 TORQUE- 73-75 %
Z-4 213 / 302 VACUUM- 380 mm Hg Z-S 235 / 221 MELT TEMP.- 227~C ~STRANDS) Z-6(DIE) 227 / 227 RATE- 150 kg/hr Z-7(DIE) 238 / 241 Ex. 80 ZIQne~ set ~oi nt ~ActuAl Con~it;ons Z-2 235 / 216 TORQUE- 73-75 %
- Z-4 213 / 302 VACUUM- 3SS-380 mm Hg Z-5 235 / 232 MELT TEMP.- 20S-207~C
Z-6 241 / 241 RATE- . 218 kg/hr Ex. 82 Zo~e set point/~ctuAl Con~;tions Z-l 288 / 288 RPM- 90 Z-2 296 / 304 TQRQUE- 50-53 %
Z-4 2~2 / 316 VACUUM- 203 - 253 mm Hg Z-5 293 / 293 MELT TEMP.- 223~C
Z-6 266 / 232 RATE- 116 kg/hr 1~40066 Ex . 83 Zone set ~oi nt/~ct~l Con~itions Z-l 288 / 285 RPM- 90 Z-2 293 / 272 TORQUE- 50-56 %
Z-4 224 / 310 VACUUM- 304 - 329 mm Hg Z-5 266 / 249 MELT TEMP.- 226~C
Z-6 266 / 229 RATE- 122 kg/hr This example illustrates the use of a graR copolymer of the present invention in the preparation of bottles trom polypropylene materials.
The graft polymer of Example 69 was blended at various levels up to 5% by weight with either of two commercial polypropylenes used for blow molding of bottles. The matrix polymer of Example 84 was a l 5 propylene r~ndo"~ copolymer believed to contain 2-4 % ethylene, s~lpplisd by Fina Oil & Chemical Co., Dallas, TX, as"Fina'7231, mfr=2.
The matrix polymer of Example 86 was a propylene homopolymer, mfr=2, s~pp'isd by Quantum Chemical, USI Division, Rolling Meadows, IL as~l~orcheml7200GF. Blends were made by tumbling the resins.
Samples were injection blow molded on a"Joma~'machine, model 40, (Jomar Corporation, Pleasantville, NJ). The resin blend, in melt form, was injected into a four-cavity mold (two cavities beins blocked off) over a core pin with an air hole at the end to form an inflatable pa,ison. The mold was heated and was desi~ned to produce a pattern at the far end which will allow a cap to be attached after molding.
Temperatures of the rnold were controlbd at the bottle neck, bottle walls, and bottle bottom. The parisons were conveyed to a second * Trademark (each Lnstance).
... ... . ,".~ . . . ," .. ~ . .,.". ~ . , 13~0066 station where they were inflated to form the bottle shape, and then to a third station where th~y were cooled and removed. Bottlss, which were a 103.5 ml spice bottb, were judged versus non-modified controls for surface gloss, clanty, uniforl"ity of thickness, wall strength, and the like, as well as to the ease of molding.
T~RI F XXIII
MO1ding COnditiOnS fOr BOtt1eS
TemDeratUreS~O~.
F.XAm~1e~ÇS1n Gr~ft,% ~ ROttO~ ~
84 84 ___ 243 77.7 104 48.9 84 EX. 69~ 5% 249 82.2 110 48.9 86 86 --- 243 77.7104 48.9 87 86 EX. 69~ 5% 249 82.2 110 48.9 When boKles frorn Example 85 were compared with their controls from Example 84, a slTght improvement in gloss, notable increase in contact clarity, and noticeable improvemen1 in stiffness were observed.
Similar advanlages ov~r the control were seen with at a 1% level of the graft polymer with the rnatrix resin of Example 84. The clarity effect was not seen with bottles from Example 87 over control Example 86.
For reasons not fully understood, the same additive at 5% was dg'~terious to the formation of bottles from homopolymer or copolymer of higher melt flow rate, even with appr~,plidle adjustments in processing te,llper6~.lr~s; much of the problem was ~ssor~ed with poor dispersion of ~he ~loJifier. Such poor clisper~ion has not been 2~ seen in other compounding, pn cessin~ or testing oper~tions. A slightly stiffer bottle of improved gloss could be blown with the graft polymer additive at 0.5 weight percent, relathe to a control with no additive .
1~40066 A pre-blend (Example 73) of 5% graft copolymer with another mfr=2 high-impact copolymer yielded bottles with severe material non-unitormity. A dry blend of 0.5~~O graft copolymer with this same resin (the resin of Example 72) gave bottles with improved gloss and contact clarity.
FXAMPI F~ 88 - 94 These examples illustrate the utility of a graft polymer of the prssent invention in the preparation of polypropylene foam and foamed sheet. In the examples, a homopolymer of polypropylene (Example 72), mfr=2, a pre-blend (Example 73) of that polypropylene with a methacrylatel/polypropylene graft copolymer, and a mixture of the Example73 pre-blend with 1% talc (designat~d Example 88) were employed; into all pellets were blen.leJ Al~pa~et"40104 to incorporate a blowing agent. "A"~acel"blowing agent is a 1 0%-active, proprietary chemical blowing agent dispersed in polyethylene. It is supplied by A",pacel Corporation, 250 South Terrace Avenue, Mt. Vernon, NY
10550. When 10 parts of Ampacet are blended, there is 1 part pr~.prietaly blowing a~ent in the formulation.
The polymer mixture was processed in a 25.4-mm, single-screw extnuder produced by Killion Extruders Cor,uGr.l~ion, utilizing a 24:1 length/diameter screw of 4:1 compression ratio, and a 1-mm-diameter rod die. Extrusion cor,Jilions are summarized below. The unmodified polymer exhibited severe fluctu~tions in die pressure (6900 - 12,400 kPa); the blend containing 5 parts of the graft copolymer could be extruded at a constant die pressure. In both cases good cell unifo~ ily was observed. Uniform larger cells were noted in the graft-polymer-modified blend when the amount of active foaming ingredient * Trademark 13qO066 was increased to 2%. The presence of 1% talc in the modified polyolefin produced the best cell structure and fastest line speed.
Foam densities of the rods were measured according to ASTM
Standard Method D-792, Method A-L. Althou~h the unmodified matrix polymer produced the lowest-density toam, the modified polymer foams in general had a regular foam-cell structure.
The three ,natelials were also p,ocessed on a similar line with a 202-mm cast film die and a heated co'lQetin~ roll to yield foamed sheet;
here no significant differences in processing were seen among the three resin blends. The individual sample preparations and results are shown in Table XXIV below.
TA~I F XXIV
Type: Rod Rod Rod Sheet SheetSheet Sample:Ex. 89Ex. 90 Ex. 91 Ex. 92Ex. 93 Ex. 94 Poly~er of:F.~x. 72 ~X. 73~x. 88 F.x. 21 ~x. 73 F.X. 73 Talc, wt% -- -- 1 -- -- --Foaming agent,wt %
Extruder rpm 80 80 80 75 75 75 Melt temp.,~C 214 208 209 227 227 227 Melt pressure, 70-kg/cm2 127 127 140 56 42 42 Puller speed, 13 15 23 meters/min Sample Density, 0.469 0.6640.733 g/cm3 FXAMpl FS 95 - 98 This example illustrates the utility of a graft copolymer of polypropylene//methyl methacrylate in the preparation of blown polypropylene film. Film was blown from the control polypropylene homopolymer of Example 74, the pre-blend of Example 75 which contained 5 weight percent of the graft copolymer of Example 69, and dry blends of the polypropylene of Example 74 with 1 and with 5 parts of the graft copolymer of example 69.
Blown film was produced on a"Killion"blown film line (Killion Extruders Co., Cedar Grove, NJ), which consists of a 25.4-mm, single-screw extruder operating at a melt temperature of about 216~C., a 50-mm spiral mandrel die, air input for producing a bubble, and a Killion vertical-blown -film tower. The blown-film tower contains two nip rolls for collapsing the bubble and a means for pulling the film through the nip rolls. The die and pull speeds are adjusted to produce film about 5.6 mm thick (two thicknesses) and either 108 or 165 mm wide, the blow-up ratios being 2.125 and 3.25 respectively, at respective top nip speeds of 7.65 and 5.94 meters/minute.
T~hle XXV
Film of Materials Thickness 20 ~m~
Ex. 95 Ex. 74; no GCP 0.051 - 0.066 Ex. 96 Ex. 75; 5~/. GCP, Cmpd. 0.056 - 0.064 Ex. 97 Ex. 74; 5~h GCP, Dry Blend 0.051 - 0.058 Ex. 98 Ex. 74; 1 % GCP, Dry Blend 0.051 - 0.058 * Trad~mark ,. ..... ,, .. . .,. .. .,~., ,w,~ , ,~, ...
13400~6 Himont 6523, mfr=4, homopolymer polypropylene was blown into 0.02~mm-thick film (single layer) as Example 95 (control). The bubble was slightly lopsided, and the frostline (onset of cryst~ tion) was at an angle to the die. A lopsided bubble results in less uniforrn film thicknesses.
With 5% of the ~raft copolymer of Ex. 69 present, the bubble of Example 96 was stabilized, the frostline lovall3d, and the frostline moved closer to the die. Both 108- and 1 65-mm, lay-flat films were produced Althou~h some fluctu~tion in die pressure was noted when Fuin,ing the latter film, it had the most stable bubble.
This increase in bubble stability was also observed with the 1%
and 5% dry blends of Examples 97 and 98. No signiFicant differences in film appe~r~nce was observed between the 5~~O precompounded blends and the dry bh~nds.
l 5 The modified films had decreased film see-through clarity.
Contact clarity remained unchanged. No difference in edge-roll color was observed belw6en modified and u~,i"GdiFi~d film.
The ~openability~ of neat and ",~ilied film was tested. Although a very qual~ative test (the collapsed film is snapped between the fingers and one feels how well it opens), no difference between the unmodified and ",odil:~ resins was observed.
FXAMpl F~ 99 -104 The experime~ts illustrate the use of the graft polymer of the pr~senl invention in producing polypropylene cast film. A single-screw extruder, manufactured by Killion Co., was e~ irped with a 3.81-cm screw of 2411 length/diameter ratio, a 20.3-cm x 0.635-mm cast film die, i 13~0~fin a chill roll and a torque winder for the film, was utilized. The extruder melt temperature was 226~C. The melt was extruded through the die and onto the chill rolls, the take-up speed being ~f1justed to produce film of various thicknesses. Film thicknesses was measured, as was ~neck-in~, an undesirable shrinkage of width. hlm stiffness and edge roll color were measured qualitatively. Film thicknesses were adjusted increasin~ line speed of the torque winder and lowering the extruder output by reducing screw speed.
TARI F XXVI
Film of Starting Material Form 1 0 rY~
Ex. 99 Ex. 74 Unmodified Ex. 100 Ex. 75 Pre-blend; 6% GCP
Ex. 101 Ex. 74 and Ex. 69 Dry blend; 5% GCP
Ex. 102 Ex. 81 Unmodified Ex. 103 Ex. 82 Pre-blend; 1% GCP
Ex. 104 Ex. 83 Pre-blend; 5% GCP
GCP s graft copolymer of Example 69 Films of the composition of Example 99 were uniform and consistent at thicknesses of from 0.25 mm to below 2.5 mm. Example 100 produced ~ept~ble film of improved ed~e color and with less film neck-in. Example 101 also prod~Jced less neck-in, but did not improve edge color. Both rnodified versions yielded stiffsr films at equivalent thickness versus the control, allowing ths fllm to be wound more easily.
The opacity of the film increased with th~ addition of the graft polymer.
13~006~
With Examples 102 to 104, the neck-in differences were not noted when the graft copolymer additive was present. The films at both 1 and 5 weight percent graft copolymer were stiffer than the unmodified control (Examples 103 and 104 versus Example 102).
FxAMpl F 105 This example illustrates that biaxially oriented film can be prepared from a polypropylene rssin containing 5% of the polypropylene/methyl methacrylate graft copolymer. Under the limited conditions tested, which were optimum for the unmodified resin, no distinct advantage could be seen for the additive. At identical extrusion and MDO (machine direction orientation) conditions, the modified resins could not achieve and maintain the line speeds possib!Q with the u~""GJif;ed resin during the TDO (transverse direction orientation).
The control resin was Example 81, mfrs2.2, high-clarity homopolymer marketed for film use. Pre-compounded resins were Examples 82 and 83, containing respectively 1% and 5% of the graft copoly",er of Example 69 (under the extrusion conditions, a dry blend of-5 parts graft copolymer of Ex. 69 with the matrix resin of Example 81 gave very poor dispersion, leading to many gels and frequent film breaks). The blends were pn~cessed in a 50.8-mm, Davis-Standard single-screw extruder which conveyed the melt through a 0.48-meter die and onto a 1 .02-meter casting roll. An air knife was used to blow the extrudate onto the casting roll. The casting roll rotat~d through a water bath to completely quench the sheet. The sheet then was conveyed into the MDO, supplied by Marshall and Williams Co., Prov:dence, Rl, and co",pRsin~ a series of heated nip rolls, moving at speeds which cause monoaxial orientation.
1 3 ~ O 0 6 ~
After the MDO, the film passed through a slitter to cut the film to the proper width and then onto a winder. These rolls were used to feed the film into the TDO, whkh is an oven with three heating zones, rolls for conveying the film forward, and clamps to grip and laterally expand the film.
The tilm from Example 81 ~unmodified resin) was drawn both 4.75:1 and 5.0:1 in the MDO, and could be drawn 9:1 in the TDO. The unmodified 4.7~:1 MI~O resin could maintain a TDO line speed of 8.69 meters/minute; the un"loditied 5.0:1 MDO resin could maintain a line speed of 6.85 meters/minute .
The fiim from Example 82 (1% graft copolymer) could receive a MDO of 4.75:1 and TDO of 9:1 and maintain a 6.85-meters/minute TDO
line speed. Frequent film b,l,~l~ge was encountered at higher MDO
and higher line speeds. This biaxially oriented film appeared to be slightly more op~que than the biaxially oriented film trom Example 80.
No differsnce between the edge roll colors of film from Examples 81 and 82 was observed for MDO film.
The films from Example 83 received MDO's of 4.75:1, 5.0:1, and 5.25:1 at a TDO of 9:1. The best film was obtained with a line speed of 6.85 mete!s/minute and with the lowest MDO; tearing would occur under more ~tlssseJ condi~ions. Films from Example 83 were notice~hly more opaque and the frost line appeared sooner than with the control film of Example 81.
FXAMPl F 106 This example illu~trates a profile extrusion trial using polypropylene modified with a graft copolymer of the present invention.
A single-screw extruder was equipped with a die and apprupria~e cooling, pulling, and sizing equipment to forrn a profile in the shape of a ,,, ~ 1. ' .. .11 ' ': "' ' " '" " '--' ' " " ' .
1~4036~
solid rod with horizontal flanges. The rod diameter was 4.83 cm., flanges 2.67 cm. (extended beyond rod), and flange thickness 1.52 cm.
With un-no~litied resin ¦Tenite ~E11 copolymer, Eastman Chemical, as described in Example 78), symmetry was difficult to maintain in the profile without sag or distortion. When blends of Example 79 and 80 (1 and 5% graft copolymer, respectively) were employed, the maintenance of shape was improved.
This example illustrates the use of a graft copolymer blend of the present invention in the modification of polypropylene to produce improved plastic tubin~. The polymers used were the unmodified resins and the resins compounded with 5% of the graft copolymer of Ex. 69, as described in Examples 72 to 77.
A 25.4-mm, single-screw"~<illion'~xtruder (Killion Extruders Co., Cedar Grove, NJ) was equipped with a screw of 24/1 length/diameter ratio, a tubing die with an outer die diameter of 11.4 mm. and a variable inner diameter, leading to a 0.25-meter-long water trough for cooling, an air wipe, and a puller and cutter. Conditions and observations are shown in Table below. Ovality is the ratio of smallest outer dia,ne~er to largest outer diameter, as measured by calipers; a value of 1 means the tube is uniformly round.
When tubing of good ovality was produced from the unmodified resin, the major effect of the additive was improvement in tubing stfflness.
With the resin of Example 72, where ovality was dimcult to control at acoeptabb output rate~;, the ",odif;e-J re~in (Example 73) improved ovality as well as ~tiffl.ess * Trademark ~!
1 3 4 ~ ~ ~ ~' T~hle XXVII
Tubin~ Pre~red from PolyDro~ylene ~nd Modifierl Poly~ropylene Polymer Meit Melt Inner Ovality Temperature, Pressure, Diameter s ~C kP~) mm (~et~
Ex. 72 217 8270 8.1 0.75 Ex. 73 214 6890 8.1 0.88 (b) Ex. 74 185 9650 8.1 0.97 Ex. 75 197 6890 8.1 (c) 0.77 o Ex. 76 184 6890 8.1 (d) 0.92 Ex. 77 180 8270 8.1 (d) 0.90 (b,e) (a) Extrusion rate equivalent for paired un",odi~ied and modified resin.
(b) Modified extrudate tube stiffer.
(c) Higher melt temperature required to avoid ~sharkskin" on tubing.
(d) With this higher mfr resin, reduced meH temperature and higher puller speed led to tubing of lower outer diameter.
(e) Modified tubing more opaque.
This example illustrates the preparation of pre-compounded blends containing talc The talc used is a white, soft, platy talc of particle size less than 40 ~mj known as'Cantal'hIM-45-90 (Canada Talc Industries Limited, Madoc, Ontario). It was used at the 20% level. The polypropylene used was a homopolymer of mfr.4, known as~lHimonr*
6523. The graft copolymer was incorporated at the 5-weight-percent * Trademark 1~4006~
level and was the graft copolymer of Example 69. The compounding/prepar~lion of these samples was carried out on a 30-mm Werner rneiderer co-~olating, t~nn-screw extruder. The materials were tumble blended prior to the compounding.
TARI F XXVIII
Blend % Talc Modifier Matrix Polymer Example 108 (control) 20Cantal -- 80% Himont 6523 Example 109 20Cantal 5% Example 75%Himont6523 The preparative conditions for the blends are given in Table XXIX.
The extruder was op~.ated at 200 rpm, with no vacuum, at rates of 4.5 -4.6 kg/hour, and 8596% torque.
TAEII F XXIX
FYtrud61r 7~ne ~etting~. ~C
FY~ e 108 F~ 109 ZQQ~ set DoinU~ i set ~oinV~tual Z-8 (die) 225/ 239 225/ 239 Melt 239 243 .. ... ,. ".~. . . ..
1~40066 FXAMPi FS 1 10 -1 17 These examples teach the injection molding of polypropylene of various compositions and melt flow rates, the polypropylenes containing a graft copolymer of the present invention. In two examples, a 20% loading of platy talc is also present.
Polypropylene may be injection molded into useful objects by employing a rec;procaling-screw, injection-molding machine such as that of Arburg Masch-en Fabrik, I ossburg, Federal Republ ~ of Germany, Model 221-51-250. In the preparation of test samples, the extruder is equipped with an ASTM mold which forms the various test pieces. The conditions chosen for molding were unchanged throughout the various matrix and modified matrix polymers, and no difficulties in molding were noted. Table XXX describes the blends which are molded; Table XXXI teaches the molding conditions; Table XXXII reports modulus values, Table XX)(III Dynatup impact data, and Table XX~(IV heat distortion temperature values for the modified polymers and their controls.
In the fol'o- ,ny list of injection-molded polymers and blends, all samples contain 1 or 5 weight percent of the graft copolymer of Example 69. The polypropylene matrix resins are described in earlier examples; HP is homopolymer, CP is copolym~r, the number is the mfr value. The blends with talc are described in Examples 108 and 109.
All materials were pre-blended in the melt, except where a dry blend from powder was directly molded. (C) is an ur""odi~ied control; (CT) is a control with talc, ~t no graft copoly",er All test methods were by ASTM standard methods: flexural modulus and stress are by ASTM Standard Method D 790, heat 134006b distortion temperature under load is by ASTM Standard Metl,od D 648 and Dynatup impact is by ASTM Standard Method D 3763.
Table XXX also includes the melt flow rates (mfr) for the unmodified and pre-compounded blends. In most cases, the melt flow rate is unchanged or slightly decreased in the presence of the graft copolymer, so that the melt viscosity under these intermediate-shear conditions is not exlensively incr~ased. The melt flow rate is by ASTM
Standard Method D-1238, condition L (230~C., 298.2 kPa) and has units of grams extruded/10 minutes.
TARI F XXX 1 3 4 0 q 6 n Exam~le Matrix ~r~ft. % T~l~. % Dry-Blend? mfr 74 (C) HP, 4 -- -- -- 4.40, 4.06 HP,4 5 -- -- 6.07 110 HP,4 5 -- YES
108 (CT) HP, 4 -- 20 --109 HP, 4 5 20 --76 (C) CP, 4 -- -- -- 4.47 77 CP, 4 5 -- -- 3.75 111 CP,4 5 -- YES
72 (C) CP, 2 -- -- -- 2.37 73 CP, 2 5 -- -- 2.02 112 CP, 2 5 -- YES
78 (C) CP -- -- -- 2.92 79 CP 1 -- -- 2.04 CP 5 -- -- 2.12 81 (C) CP -- -- -- 2.33 82 CP 1 -- -- 3.81 83 CP 5 -- -- 2.16 TARI F XXXI
Injection Molding Condltions fo- Polypropylene Cylinder temper~tl Ires. ~C (settin~,lme~cl Ired) Feed -216/216 Metering -216/216 Compression -216/216 Nozzie 216/216 Mold Temperatures, ~C
Stationary -49/49 Moveable -49/49 Cycle time, seconds Injection forward -14 Mold Open -0.5 Cure -14 Total Cycle -0.5 Mold Closed -1.2 Machine readings:
Screw speed (rpm) - 400 Back pressure (kPa) -172 Injection (1st stage~(kPa) - 861 The flexural modulus data from Table XXXII indicate the stiffening effect of the graft copolymer. Results are in me~ C (mPa).
134006~
T~RI F XXXII
FLEXURAL STRESS
Example MODULUS ~at max) mP~ mP~
74 (C) 1470.6 43.8 1744.4 47.5 110 1783.1 46.9 108 (CT) 2768.0 52.0 109 2867.0 54.5 Table X)O~III summarizes Dynatup impact data (in Joules) at various temperatures for the blends and cG~nrols tested. The data indicate, in general, slightly improved impact for the pre-blended materials, a deterioration in impact sl-e"ylh on molding dry blends of graft copolymer and matrix polymer, and an increase in impact strength for the talc-modified blend also containing the graft copolymsr.
1340~6~
T~RI F XXXIII
Dynatup Impact Uoules) at TestTe",~r~ re.~C
Fxample ~.~ 15 5 -574 (C) 4.9i2.7 4.4i1.5 3.8iO.3 2.6i.41 5.7i3.4 4.6iO.8 2.7i1.5 3.4i1.09 110 3.4i1.1 2.0~0.5 1.9i1.0 1.5i.41 108 (CT) 3.0iO.5 3.4iO.8 4.2i1.6 5.0i2.5 109 1.9iO.5 4.1i2.3 4.8i1.8 5.0+2.5 76 (C) 40.0iO.5 77 43.9iO.4 111 14.0i6.4 72 (C) 37.9+1.8 73 43.1i10.3 112 32.4i9.5 78 (C) 36.7iO.4 79 36.3i1.1 37.1iO.7 81~ (C) 13.3i10.7 --- 3.3+0.8 2.7iO.2 82 4.9iO.7 ---- 3.0i1.4 3.0+0.8 83 7.6i3.7 ---- 3.3iO.8 3.5i1.1 The large standard deviation at room temperature is suspect.
Tabb XXXIV pr~senls heat distortion and hardness values for one series. The modifed polymer appedl~ to exhibit a slightly higher heat distG,tion te,-lper~ture and hardness, aîthough there are inconsislencies noted. The Rocku~611 hardness values represent 134006~
separate determinations on two samples of the material from the in~ ted example.
T~RI F XXXIV
Heat Deflection Temperature Rockwell Hardness Example ;~t ~~-:/Mi~ute ~t "C" ~ lP
411 kPa 1645 kPa 74 (C) 110.9 61.0 58.4 56.5 113.8 63.3 60.7 59.3 110 117.3 68.7 57.9 46.9 108 (CT) 128.2 76.8 57.3 64.7 109 124.7 81.9 65.4 63.7 FXAMPl F 113 This example illustrates the effect of the molecular weight of the polypropylene trunk component of the graft copolymer on the sag ",odifica~ion of polypropylenes ot various molecular weights. Graft copolymers were prepared from polypropylene of various melt flow rates. All modifiers were prepared as in Example 58. The 35 mfr polypropylene ~limont PD-701) was run at 65% solids. The 12 mfr polypropylene ~himont Pro-fax 6323) was nun at 60% solids. The 4 mfr polypropylene lHimont Pro-fax 6523) and the 0.8 mfr polypropylene '~Himont Pro-fax"6723) were run at 55% solids. The molecular weights for the polypropylene base resins, where known, are given in Table XXXV, below.
These were ev~lu~1ed as melt slr~nsJ~ll improvers at 4% by weigh in several of these same polypropylenes. Standarc~ mill and press conditions were used for all blends, except the 0.8 mfr/0.8 mfr * Trad~nark . ..
1~400fi~
polypropylene blends which were milled at 215~C and pressed at 215~C. Sag rates were measured by the standa-rd prucedures. The sag slope at 190~C is reported in Table XXXVI, below.
T~RI F XXXV
MW-~FR D~t~ for Poly~ro~ylene RAse Res;n Molecular-Weight Wei~ht-Aver~e ~lecul~r We;~ht x 10~ _ So~rce 1~ ~fr PP 4 mfr PP 0.8 mfr PP
~a) 3 4.3 7.1 (b) 2.45 3.05 3.5,4.7 (c) 0.27* 0.45~ --Source of Molecular-Weight Value: a) Supplier's data. b) Sheehan et al, J. Appl. Polymer Sci., 8, 2359 (1964). c) Mays et al, ibid., 34, 2619 (1987).
* These values are nllmh~r-~ver~e molecular weight.
TABI F XXXVI
S~ SloDe ~t 190~C for Olefin Blen~ ( min-1L
~oly~ro~y]~ne hA~e res;n (96%) m~;fier (4%) 35 mfr PP 12 ~fr PP 4 ~fr PP 0.8 mfr PP
none 1.6 0.52 0.250.099 35 mfr PP based 1.8 0.52 0.23 0.074 12 mfr PP based 1.2 0.41 0.034 < 0.02 4 mfr PP based 1.0 0.16 0.022 < 0.02 0.8 mfr PP based 0.64 0.16 0.031 << 0.02 In all cases except where a high-melt-flow base resin was modified with a graft polymer having a trunk of high-flow-rate (low-molecul-r-weight) polypropylene, sag improvement was observed. The molecular weight for the resin of mfr=35 is not accurately known; it is believed to be made by therrnal/oxidative processing of a higher molecular weight resin. Such a process would both lower the molecular weight and narrow the originally broad mol~cul~r-weight distribution.
This example illustrates the effectiveness of the graft copolymers of the present invention as comp~tibilizing agents for polymers that are otherwise poorly compatible. In this example a polyolefin, a polar polymer, and the graft copolymer of the present invention were compounded in an intermeshing, co-rotating, twin-screw extruder (Baker-Perkins MPC/V 30) with a screw length-to-diameter ratio of 10:1.
The compounder was run at 200 rpm and temperatures were adjusted to acco"""odale the polymers in the blend and achieve a good melt.
The melt temperature in the compounding zone is recorded in the second column of the table. The melt was fed directly to a 38-mm, single-screw, pelletizing extruder with a length-to-diameter ratio of 8:1.
The melt temperature in the transition zone between the compounding and the pe"s~i~ing extruder is shown in column 3 of Table XXXVIII, below. The melt was extruded into st-dr,ds through a die, cooled in a water bath, and cut into pellets.
Table XXXVII below summarizes the polymers which were used in the blends of the present example, while Table XXXIX shows that the graft copolymer has little effect upon the tensile strength of the unblended polymers, that is, it does not act to a significant degree as a toughening agent. !n the s~bse~usnl tables, Tables XL and XLI, improvement in tensile strength of the blended polymers indicates an increase in compatibility of the blended polymers with one anotl,er in the presence of the graft copolymers of the presenl invention.
l~OI~fifi Under the proper compounding conditions, an increase in comr~t;bility may also produce a decrease in the size of polymer domains in the blend. Scanning electron mic-uscopy confirms that in some of these examples, significant domain-size reductions occur when the graft copolymer is added. For example, the polypropylene domains average 2 micrometers in the 70 PMMA / 30 PP blend of example 114.
The addition of 5 phr co",palibili~er re~uced the domain size to 0.5 ~m.
The addition of 15 phr compatibilizer reduced the domain size to 0.43 ~m. Although not all of the domain sizes were reduce~, several others were reduced by 10-30% by the addilion of 5 phr compatibilizer. This is a further suggestion that the compatibilizer is acting on the inle, ~ce of the polymer domains rather than on the individual polymers.
Table XLI summarizes the compatibilizing effect of the graft copolymers upon the various polymer blends.
1~40~fi~
TABI F XXXVII
Poly~ers Used in the Blen~ ~xAm~les Other Polymer and Designation Grade Spec. Specifi-in T~hles Pro~ucer Desi~n~tion Grav. ~tions SAN Monsanto "Lustran"SAN 33 1.07 mfr=14 Styrene-Acrylonitrile ASTM D 1238 Polymer Cond.~I) PA66 DuPont "Zytel"101 1.14 mp=255~C
Nylon 6-6 (D2117) PET Eastman ~IKodapak"PET 1.4 mp=245~C
Polyethylene Kodak 7352 (DSC), Terephthalate iv=0.74 EVOH EVAL Co. "Eval" EP-E105 1.14 44 mole% E, Ethylene Vinyl of America mp=164 C, Alcohol Copolymer mfr-5 5 2160 g) PC General "Lexan"121 1.20 mfr=16.5 Polycarbonate Electric ASTM D 1238 Plastics Cond. ~O) PVC Georgia SP-7107* 1.35 PolyvinylChloride Gulf Corp.
PMMA Rohm and "Plexiglas"VM 1.18 mfr=15 Poly(Methyl Haas Co.
Methacrylate) EP Exxon "Vistalo~'719 0.89 54 Mooney Ethylene Propylene (D-1646) Copolymer HDPE Phillips "Marlex"* 0.950 mfr=4 High-Density 66 Co. HMN 5060 Polyethylene PP Himont "Pro-fax"6523 0.903 mfr=4 Polypropylene EVA DuPont "Elvax"650 0.933 12% VA
Ethylene Vinyl Acetate mfr=8 * Trademark (each instance).
,. .
l3~oo6o TARI F XXXVII (continued) Other Polymer and Designation Grade Spec. Specifi-in T~hles Pro-lucer Designation Grav. ~tions LLDPE Exxon " Escorene "* 0.926 mfr=12 Linear Low-Density LL-6202 Polyethylene PS Huntsman PS-203 1.06 mfr=8 Polystyrene Chemical (crystal) PBT General " Valox' 6120 Poly~butylene Electric terephthalate) PA6 Allied " Capron"8253 1.09 mp=21~C
Nylon 6 Signal ABS Dow " Magnum"341 1.05 mfr=5 Acrylonitrile- Chemical Butadiene-Styrene Resin PC/PBT General "Xenoy~'1101 1.21 Polycarbonate/ Electric Poly(butylene tere-phthalate alloy * Tr~A~m~rk (each instance.
134006~
T~RI F XXXVIII
m~lt t~m~er~tures (~C) co~o--nder tr~nsition The pellets were dried and injection molded on a reciprocating-screw injection molding machine'~New Britair~'Model 75) into test specimens.
~rademark l340a~fi TABI F XXXIX
~ffect of Cc~patihilizer ~n Polymer Tensile Strength Tensile St~engthq Shown in Me~PASrAl S ~PA) com~Atihilizer concentration Polymer 0 phr 5 ~hr 15 ~hr PMMA65.44 64.79 61.27 SAN 71.91 62.74 55.89 EVOH68.78 66.21 63.78 PA6664.82 64.68 66.60 PET 58.26 59.33 59.72 PVC 45.25 44.97 45.22 PC 62.63 63.05 63.70 HDPE22.59 22.66 24.14 PP 33.02 34.03 33.95 EP 4.79 5.50 5.84 LLDPE10.91 11.80 12.99 EVA 8.64 8.67 8.17 13~0~fi6 T~RI F Xl Tensile Str~ngths (MPa) of ~l~n~c of Polyolefins ~nd Pol~r Polymers 30% pol~r ~olymer 55% ~ol~r Doly~Pr 80% ~ol~r ~olymer polar poly~r Ophr ~hL l~h~ Ophr SDhr 15phr Q~hL ~hL 15phr * PMMA 25.26 27.00 30.26 31.42 38.30 39.54 50.78 53.77 55.55 * SAN 25.77 28.09 30.57 34.71 41.51 38.33 51.88 55.08 51.23 * EVOH 26.57 26.80 27.74 33.18 38.00 39.58 49.24 51.32 50.79 PA66 26.94 28.85 29.72 38.34 38.11 38.33 61.22 65.62 69.23 PET 25.97 28.61 30.98 37.70 37.93 40.09 50.23 51.72 50.91 PVC 20.89 22.92 24.86 19.91 23.67 27.34 26.18 30.72 34.87 PC 25.66 28.80 30.93 31.11 35.20 38.53 55.61 50.41 51.92 _______________________ pp ________________________ * PMMA34.02 35.37 37.81 40.23 43.45 45.84 46.40 53.70 56.6 * SAN33.67 38.76 41.05 37.67 47.65 46.08 41.11 54.12 51.81 * EVOH32.85 37.40 38.56 35.01 44.65 45.60 42.73 53.38 52.57 PA6632.06 40.29 40.38 42.72 52.17 51.10 64.71 67.84 66.15 PET32.93 33.80 35.15 39.47 43.81 43.64 37.67 53.12 54.04 PVC36.32 37.68 39.35 35.28 37.87 40.79 30.88 40.00 42.56 PC33.82 36.68 39.09 36.69 40.13 44.64 42.38 46.24 51.64 ----------------------- EP ------------------------PMMA8.20 10.87 12.51 19.99 24.17 27.81 42.47 44.59 46.93 SAN8.10 12.53 14.11 22.14 28.82 28.15 45.92 50.68 44.58 EVOH12.19 12.04 11.69 24.92 24.66 23.17 41.29 42.39 42.70 PA6613.04 13.04 12.36 27.62 27.98 26.33 40.87 48.77 43.48 PET7.94 8.40 11.13 20.22 20.43 22.27 33.72 37.00 38.87 PVC6.17 9.05 12.88 12.93 18.28 19.22 25.50 28.41 30.60 PC10.31 12.05 13.66 23.10 24.34 25.60 40.18 41.79 42.76 ., .. ~
. ~
13~00fi~
T~l F Xl (çontinl-e~) Tensile Strengths (MP~) of Rl~n~.~ of Polyolef;ns ~n~ Pol~r Polymers 30~ polar poly~r 55% ~olAr po~ym~er 80% pol~r ~olymer polar polymer Ophr 5Dhr l~hL Q~hL ~hL l~hl Q~hL 5p~r 15phr ~ ---------------- LLDPE -----------------------PMMA 15.23 18.63 20.90 24.88 30.68 32.84 48.95 55.36 54.14 SAN 15.78 21.08 22.57 26.50 35.76 36.71 47.52 56.92 48.84 EVOH 16.83 17.26 18.26 30.02 31.74 31.87 51.83 50.71 52.29 PA66 17.93 17.99 19.98 29.67 28.49 25.23 64.65 67.55 67.26 PET 15.33 18.09 20.35 25.53 28.23 30.78 45.02 46.16 42.87 PVC 14.72 14.12 15.73 12.45 18.09 20.50 25.99 30.54 33.69 PC 13.64 19.20 18.48 19.22 27.83 30.46 38.45 40.59 38.86 ~~~~~~ ------- EVA -------_-_______________ PMMA10.57 11.28 14.38 23.06 21.10 28.31 45.99 47.02 50.87 SAN12.40 13.62 15.22 27.97 27.29 29.35 48.94 52.01 46.14 EVOH13.13 13.97 16.59 32.41 28.65 35.43 50.97 50.28 48.81 PA6614.15 13.54 14.42 27.36 24.59 26.92 40.75 38.35 31.60 PET14.55 14.35 12.31 21.22 23.90 26.45 43.20 43.91 48.44 PVC7.69 8.28 10.25 13.40 14.29 18.17 19.22 23.76 28.12 PC14.05 14.54 13.52 19.78 21.79 24.85 39.26 40.55 41.46 - polar polymer levels are 20, 45,and 70% instead of 30, 55 and 80%.
~ ......
., .. ~.. . ~ . .. , . " . .
TARI F Xl I
Effect of Compatibilizer on Tensile Strength of Blends of Polyolefins and Polar Polymers Incre~se in Tensile Stren~th ~P~) from the Co~tibilizer 30% polar polymer 55% pDlAr polym~L 80% ~olar polymer polar poly~er 5 phr15 phr5 Dhr15 phr 5 phr 15 phr PMMA 1.745.01 7.38 8.12 2.99 4.77 SAN 2.324.80 6.80 3.63 3.21 -0.64 *EVOH 0.231.17 4.81 6.39 2.08 1.54 PA66 1.902.77 -0.23 -0.01 4.40 8.00 PET 2.655.01 0.23 2.39 1.48 0.68 PVC 2.033.97 3.76 7.43 4.54 8.69 PC 3.145.27 4.10 7.42 -5.20 -3.69 ________________________ pp ________________________ *PMMA 1.353.79 3.225.61 7.29 10.22 SAN 5.097.38 9.988.41 13.02 10.70 *EVOH 4.565.72 9.6410.59 10.65 9.83 PA66 8.238.32 9.458.38 3.13 1.44 PET 0.862.22 4.344.17 15.44 16.37 PVC 1.363.03 2.595.51 9.11 11.68 PC 2.865.27 3.437.94 3.85 9.26 .. , . . . ~ ,,. , ~
1~400~6 TARI F ~ çontinued~
IncreAse in Te~sile Stren~th (~PA) fro~ the Cc~DAtihili7er 30% polAr poLYr~r 55% polAr polymer 80% pol~r polymer polar polym~r5 phr 15 phr 5 phr 15 phr 5 Dhr 15 phr _____________________--- EP --~~~~~~~~~~~~~~~~~~~~~~
PMMA2.664.30 4.18 7.82 2.12 4.46 SAN4.43 6.01 6.68 6.01 4.76 -1.34 EVOH-0.15-0.50 -0.27 -1.75 1.10 1.41 PA660.01-0.68 0.36 -1.29 7.90 2.61 PET0.46 3.19 0.21 2.05 3.29 5.16 PVC2.86 6.71 5.35 6.29 2.91 5.10 PC1.74 3.35 1.24 2.50 1.61 2.59 ~--------------------- LLDPE -----------------------PMMA3.405.67 5.80 7.96 6.42 5.19 SAN5.31 6.80 9.26 10.21 9.40 1.32 EVOH0.431.43 1.72 1.85 -1.12 0.45 PA660.062.05 -1.19 -4.44 2.90 2.61 PET2.76 5.01 2.70 5.25 1.14 -2.14 PVC-0.59 1.01 5.64 8.05 4.56 7.70 PC5.56 4.85 8.61 11.24 2.14 0.41 ----------------------- EVA ------------------------PMMA0.713.81 -1.95 5.25 1.03 4.87 SAN1.22 2.81 -0.68 1.38 3.07 -2.80 EVOH0.833.45 -3.75 3.02 -0.68 -2.16 PA66-0.610.27 -2.77 -0.44 -2.40 -9.15 PET-0.20 -2.25 2.68 5.23 0.70 5.24 PVC0.59 2.56 0.89 4.76 4.54 8.89 PC0.49 -0.53 2.01 5.07 1.30 2.20 ~ - polar polymer levels are 20, 45 and 70% instead of 30, 55 and 80%.
13iO066 T~RI F Xl ll ComD~tih~ tion Fffect E~ PP ~ ~ E~a PMMP. +++ +++l +++ +++ +++
SAN +++ +++ +++ +++ ++
EVOH ++ +++l o o ++
PA6 6 ++ +++1 + + o PET + ++l ++ ++ ++
PVC +++ +++ +++ ++l ++
1 0 PC ++ +++l + ++ +
+++ - compatibilization at all three polyolefin-polar polymer ratios (not necessarily at all comp~tibili~er levels) ++ - compatibil~ tion at two of the three polyolefin-polar polymer levels + - cG")pdlibilization at one of the two polyolefin-polar polymer levels 15 0 - no competibili~~tion seen at any polyolehn-polar polymer ratio, at any compatibilizer level (1 ) - additional evidence for compatibilization in the reduction of domain size by 1 0-80%
FxAMpl F 1 15 The compatibilizing effect on selected, additional polymer pairs was evaluated in the fol'D~:;ng example. The blends were compounded, molded and tested tor tensile strength as previously described. The results in Table XLIII again indicate that the compatibilizer has minimal or a negative effect on the polar polymers, but a positive effect on the polar / nonpolar polymer blends. A large tensile ~ afi!Jtll i,..pru~lroment is seen for the ABS / PP blend. Smaller but significant improvements are seen for the blends of PP with PA6 and with PC / PBT. With the PS blends ev~u~ted the effect was negligible.
13~0066 TABI F ~
ten~ile ~tren~th.q (~PA ) polar polymer + blendl +
15 phr 15 phr polar nonpolar polar graft graft -polymer po]y~r polymer co~oly~er hl en~l copolym~r PBT PP 43.02 45.11 36.96 38.96 PA6 PP 56.11 51.67 43.50 47.04 PS PP 45.26 40.45 38.88 37.36 PS HDPE 45.26 40.45 36.48 33.76 ABS PP 51.25 52.25 32.25 42.55 PC/PBT PP 51.77 51.79 38.99 41.88 1 - blend in all cases refers to 55 parts by weight polar polymer and 45 parts by weight nonpolar polymer.
The effect of ths graft copolymer on multi-component blends such as those ~epresentative of commingled scrap polymers are shown in Table XLIV. In all cases a siyni~icant inclease in tensile :.l,enyll, is observed when the compatibilizer is pr~senl.
l-~RI F Xl IV
Com~tibili7~tion of Multicomponent Rlend5 Tensile Pol~r Poly~rsNQ~pol~r Polymers Co~p~t;h;li2er Strength (~P~ ) E~ ~Y~ E LLDPE ~
12 7 5 33.5 33.5 9 none 16.27 12 7 5 33.5 33.5 9 5 17.67 12 7 5 33.5 33.5 9 15 21.77 12 8 - 35 35 10 none 18.62 12 8 - 35 35 10 5 19.98 12 8 - 35 35 10 15 22.16 12 - 6 36 36 10 none 17.06 12 - 6 36 36 10 5 19.21 12 - 6 36 36 10 15 21.91 FxAMpl F 1 16 This example further illustrates compatibilization of polymer blends usin~ graft copolymers of the present invention.
Blends of ethylene-vinyl alcohol copolyme;(Kuraray EP-F101A), polypropylene '~Himont'6523) and graR copolymer were milled on a 7.62-cm X 17.78-cm electric mill at 204~C to flux plus three minutes.
The stocks were pres6ed at 204~C and 103 MPa for three minutes (Carver Press, 12.7 crn X 12.7-cm X 3.175-mm mold)and at room temperature and 103 MPa for three minutes. Two graR copolymers were used in this example. The first (Graft Copolymer A) was a poly,un,pylene - acrylic graR copolymer prepared from mfr=4 polypropylene hGl"Gpolymer (100 parts) and a 93:2:5 mixture of methyl * Trad~rk .. . . ~ . .... . . .. .
,, 1340066 methacrylate:ethyl acrylate:methac~lic acid (100 parts). Polymenzation was done in Isopar E solvent at 1 60~C at 50% solids ovsr ons hour with a di-t-butyl psroxide radical flux of 0.00012. The product isolated contained 44% acryla~e. The sscond graft copolymer ~Graft Copolymer ~; B) was a polypropylene - acrylic graft copolymsr prspared from mfr=4 propylene ho"lopoly~er (100 parts) and a 95:5 mixture of methyl Ine~l,acrylate:sthyl acrylate (150 parts). Polym~rization was done in Isopar E solvent at 1 55~C at 60% solids. The feed time was 60 minutes and the radical flux was 0.00010. the product contained 53% acrylate.
Addition of the graf~ oopolymer results in an increase in tensile strength and modulus.
TA~ F ~l y Co~tihjli7~tion of FyOH ~nd Polv~ro~ylene notched graft Izod tensile tensile EVAL PPcopolymer tensile strength modulus ~ I~r~m~ rAm~r~m~) (J/~ (~p~) (~PA) 0 21 29.85 2570 51 21 48.06 3190 52 22 46.75 3270 0 18 21.37 1930 151 18 29.79 2140 152 13 30.41 2030 1 - Graft Copolymer A (see text abovs).
2 - Graft Copolymer B (see text above).
1~4006~
While the invention has been descnbed with reference to speafic exa",pl3s and applications, other ",o~lificaliGns and uses for the invention will be apparent to those skilled in the art without departing from the spirit and soope of the invention defined in the appended claimS~
. ,, . . , . . ~ .. v
~ .. . .. . . . ~ . .
T~RI F XVIII
Weight of Weight before Weight after Weight polyethylene, reaction (after reaction and of polymer g. nitr~t;~n), ~. extr~ction. ~ extr~cte~
3.397 3.48 5.964 4.40 Thus, the graft copolymer formed was 43~/O PMMA and 57% PE. The total sample prior to extraction was 67% PMMA, 33% PE, and the efficiency of grd~ling of the PMMA was 63.1%.
The resultant graft polymer, from which the ungrafted polymer had not been removed, was blended at the 4% level into the polypropylene resin of mfr=4 used as a standard for testing sag ,~sistance. The graft copolymer of thisexample did not r~isF~rse well, and visible, large, undispersed fragments were seen. The sag value (0.31 ) was worse than for the ~"""odified resin (0.1~) or for resin modified with an equivalent amount of the graft copolymer of Example 69 (0.02).
The graft copolymer of this example was also milled into linear low-density polyethylene (mfr 2.3) in the mannsr taught in Example 59. Poor disper:,;on in polyethybne was also notsd, with large chunks of the undispersed modifier visible. Sag r~si-~ance was determined at 150~C as in Example 59; sag for the unmodified control (by the sag slope test) was 0.39, and for the graft copolymer of this example, 0.23. By comparison, sag when using the graft copoly",er of Exampls 4 would be expected to be well below 0.10.
1~4Qo6~
FXAMPI FS 7~ - 77 This example illustrates preparation of blends of graft copolymer with polypropylene resins to form pellets useful for hrther processing into extruded or molded articles.
The graft copolymer of Example 69, not separated from any ungrafted polypropylene or acryNc polymer, was used as 3.2-mm-long pellets cut from an extruded strand.
The polypropylene resins used were~Aristech~1-4020F (Aristech Chemical Corporation, Pittsburgh, PA),'l limontR6523 (Himont Corporation, o Wilmington, Delaware), and'l:texene 1 4S4A (Rexene Corporation, Dallas, TX).
Characteristics are shown in Table Xlll; the term ~copolymer~ in the table means a copolymer with ethylene.
The graft copoly.~,er was blended at 5% with the polypropylene resins by tumbling. The blend was then extruded into slldnds through an~Egan 60-l'*
mm, twin-screw extnuder e~luirped with screws of 32:1 length/diameter ratio;
the strands were cooled and chopped into pellets. Various feed rates and screw speeds we~ utiJized. Con.Jitions for the unmodified and modified resins used to obtain large-scale samples are summarized in Table XIV. Sag tests as described in Example 1 were conducted on several other samples of modified resin p.oc~ssed under varying conditions, and the results were comparable to those ~epo,led below in Table XIX.
* Trade~ rk (each instance).
134006~
T~RI F XIX
~l~n~.~ of PolyDropylene With Met~yl MethAcrylAte GrAft Copolymer ~nd Controls Ex. 69 ExampleGraft, Polypropylene MAtrix Res;n Sag ph r Name MFR Comnosition 72 -- Aristech TI-4020F 2 copolymer 0.23 73 5 0.02 74 -- Himont 6523 4 homopolymer0.36 0.11*
76 -- Rexene 14S4A 4 copolymer0.35 77 5 0.14 ~ Sample tore on testing; other blends processed at slightly different conditions gave sags of 0.06 to 0.09.
TARI F XX
Processing Cnn~;tions for Pre-Rlen~s of T~hle XIX
Example: 72 73 74 ~ 76 77 Modifier: -- 5% -- 5% -- 5%
Feed Rate, kg/hr (Set)90.7181.9 90. 7 181.4 181.4 181.4 Feed Rate (actual) 90.2 185 89.8 181.4 178.7 182.3 Screw Speeds 101 200 100 200 200 Drive Amps 103 121 97 111 112 112 lO Kg-m/sl 1258 3033 1184 2811 2811 2811 Head Pressure (kPa) 2137 2758 1448 2068 2275 2206 Barrel Temps. ~~C) Zone 1 163 163 163 163 163 163 Zones 2 - 8 204 204 204 204 204 204 15 Die 204 204 204 204 204 204 Melt Temp. ~C 213 222 208 216 217 217 1 - Power aiJ r' 0d to extruder screw.
This example illustrates pr~paralions of blends of graft copolymer 20 with other polypropylene resins on different compounding equipment to form pellets useful for turther processing into film or profile. The~lAmoco~*
6214 is a film grade polypropylene rssin conl~ning a clarifier. The Eastman 4E1 1~is an impact-extrusion grade, propylene-ethylene-copolymer resin used in profile extrusion. In the present case, both 1%
25 and 5% by weight of the graft copolymer described in Example 69 were used to form the blends.
* Trademark ** Trademark The two polymers were tumble blended, and the mixtures fed to an 83 mm"Wemer rfi~'derer'~o-rotating, intermeshing, twin-screw extnuder of 24/1 Ud ratio. The pellets were continuously fed to the extruder by means of an~lAcrison~loss-in weigl)l feeder~, melted and mixed in the extruder, extruded through a 33-strand die, cooled in a water trough, dried, pelletized, and packaged. The machine conditions for the individual batches are as follows:
TABI F XXI
Co~Dos;tions of Rlen~.s ~n~ M~trlx PoLymers ~x~m~le % M~;fier ~tr;x Polymer 78 -- "Eastman"4E11 Copolymer 81 -- "Amoco 6214"Homopolymer * Trademark TARI F XXII
PreparAtive Con~itions for V~rious Blen~.~ of TAhle XXI
T~m~erature. ~C
Ex.79 Zone set ~oint/ActuAl Con~;tions Z-l 229 / 229 RPM- 125 Z-2 235 / 216 TORQUE- 73-75 %
Z-4 213 / 302 VACUUM- 380 mm Hg Z-S 235 / 221 MELT TEMP.- 227~C ~STRANDS) Z-6(DIE) 227 / 227 RATE- 150 kg/hr Z-7(DIE) 238 / 241 Ex. 80 ZIQne~ set ~oi nt ~ActuAl Con~it;ons Z-2 235 / 216 TORQUE- 73-75 %
- Z-4 213 / 302 VACUUM- 3SS-380 mm Hg Z-5 235 / 232 MELT TEMP.- 20S-207~C
Z-6 241 / 241 RATE- . 218 kg/hr Ex. 82 Zo~e set point/~ctuAl Con~;tions Z-l 288 / 288 RPM- 90 Z-2 296 / 304 TQRQUE- 50-53 %
Z-4 2~2 / 316 VACUUM- 203 - 253 mm Hg Z-5 293 / 293 MELT TEMP.- 223~C
Z-6 266 / 232 RATE- 116 kg/hr 1~40066 Ex . 83 Zone set ~oi nt/~ct~l Con~itions Z-l 288 / 285 RPM- 90 Z-2 293 / 272 TORQUE- 50-56 %
Z-4 224 / 310 VACUUM- 304 - 329 mm Hg Z-5 266 / 249 MELT TEMP.- 226~C
Z-6 266 / 229 RATE- 122 kg/hr This example illustrates the use of a graR copolymer of the present invention in the preparation of bottles trom polypropylene materials.
The graft polymer of Example 69 was blended at various levels up to 5% by weight with either of two commercial polypropylenes used for blow molding of bottles. The matrix polymer of Example 84 was a l 5 propylene r~ndo"~ copolymer believed to contain 2-4 % ethylene, s~lpplisd by Fina Oil & Chemical Co., Dallas, TX, as"Fina'7231, mfr=2.
The matrix polymer of Example 86 was a propylene homopolymer, mfr=2, s~pp'isd by Quantum Chemical, USI Division, Rolling Meadows, IL as~l~orcheml7200GF. Blends were made by tumbling the resins.
Samples were injection blow molded on a"Joma~'machine, model 40, (Jomar Corporation, Pleasantville, NJ). The resin blend, in melt form, was injected into a four-cavity mold (two cavities beins blocked off) over a core pin with an air hole at the end to form an inflatable pa,ison. The mold was heated and was desi~ned to produce a pattern at the far end which will allow a cap to be attached after molding.
Temperatures of the rnold were controlbd at the bottle neck, bottle walls, and bottle bottom. The parisons were conveyed to a second * Trademark (each Lnstance).
... ... . ,".~ . . . ," .. ~ . .,.". ~ . , 13~0066 station where they were inflated to form the bottle shape, and then to a third station where th~y were cooled and removed. Bottlss, which were a 103.5 ml spice bottb, were judged versus non-modified controls for surface gloss, clanty, uniforl"ity of thickness, wall strength, and the like, as well as to the ease of molding.
T~RI F XXIII
MO1ding COnditiOnS fOr BOtt1eS
TemDeratUreS~O~.
F.XAm~1e~ÇS1n Gr~ft,% ~ ROttO~ ~
84 84 ___ 243 77.7 104 48.9 84 EX. 69~ 5% 249 82.2 110 48.9 86 86 --- 243 77.7104 48.9 87 86 EX. 69~ 5% 249 82.2 110 48.9 When boKles frorn Example 85 were compared with their controls from Example 84, a slTght improvement in gloss, notable increase in contact clarity, and noticeable improvemen1 in stiffness were observed.
Similar advanlages ov~r the control were seen with at a 1% level of the graft polymer with the rnatrix resin of Example 84. The clarity effect was not seen with bottles from Example 87 over control Example 86.
For reasons not fully understood, the same additive at 5% was dg'~terious to the formation of bottles from homopolymer or copolymer of higher melt flow rate, even with appr~,plidle adjustments in processing te,llper6~.lr~s; much of the problem was ~ssor~ed with poor dispersion of ~he ~loJifier. Such poor clisper~ion has not been 2~ seen in other compounding, pn cessin~ or testing oper~tions. A slightly stiffer bottle of improved gloss could be blown with the graft polymer additive at 0.5 weight percent, relathe to a control with no additive .
1~40066 A pre-blend (Example 73) of 5% graft copolymer with another mfr=2 high-impact copolymer yielded bottles with severe material non-unitormity. A dry blend of 0.5~~O graft copolymer with this same resin (the resin of Example 72) gave bottles with improved gloss and contact clarity.
FXAMPI F~ 88 - 94 These examples illustrate the utility of a graft polymer of the prssent invention in the preparation of polypropylene foam and foamed sheet. In the examples, a homopolymer of polypropylene (Example 72), mfr=2, a pre-blend (Example 73) of that polypropylene with a methacrylatel/polypropylene graft copolymer, and a mixture of the Example73 pre-blend with 1% talc (designat~d Example 88) were employed; into all pellets were blen.leJ Al~pa~et"40104 to incorporate a blowing agent. "A"~acel"blowing agent is a 1 0%-active, proprietary chemical blowing agent dispersed in polyethylene. It is supplied by A",pacel Corporation, 250 South Terrace Avenue, Mt. Vernon, NY
10550. When 10 parts of Ampacet are blended, there is 1 part pr~.prietaly blowing a~ent in the formulation.
The polymer mixture was processed in a 25.4-mm, single-screw extnuder produced by Killion Extruders Cor,uGr.l~ion, utilizing a 24:1 length/diameter screw of 4:1 compression ratio, and a 1-mm-diameter rod die. Extrusion cor,Jilions are summarized below. The unmodified polymer exhibited severe fluctu~tions in die pressure (6900 - 12,400 kPa); the blend containing 5 parts of the graft copolymer could be extruded at a constant die pressure. In both cases good cell unifo~ ily was observed. Uniform larger cells were noted in the graft-polymer-modified blend when the amount of active foaming ingredient * Trademark 13qO066 was increased to 2%. The presence of 1% talc in the modified polyolefin produced the best cell structure and fastest line speed.
Foam densities of the rods were measured according to ASTM
Standard Method D-792, Method A-L. Althou~h the unmodified matrix polymer produced the lowest-density toam, the modified polymer foams in general had a regular foam-cell structure.
The three ,natelials were also p,ocessed on a similar line with a 202-mm cast film die and a heated co'lQetin~ roll to yield foamed sheet;
here no significant differences in processing were seen among the three resin blends. The individual sample preparations and results are shown in Table XXIV below.
TA~I F XXIV
Type: Rod Rod Rod Sheet SheetSheet Sample:Ex. 89Ex. 90 Ex. 91 Ex. 92Ex. 93 Ex. 94 Poly~er of:F.~x. 72 ~X. 73~x. 88 F.x. 21 ~x. 73 F.X. 73 Talc, wt% -- -- 1 -- -- --Foaming agent,wt %
Extruder rpm 80 80 80 75 75 75 Melt temp.,~C 214 208 209 227 227 227 Melt pressure, 70-kg/cm2 127 127 140 56 42 42 Puller speed, 13 15 23 meters/min Sample Density, 0.469 0.6640.733 g/cm3 FXAMpl FS 95 - 98 This example illustrates the utility of a graft copolymer of polypropylene//methyl methacrylate in the preparation of blown polypropylene film. Film was blown from the control polypropylene homopolymer of Example 74, the pre-blend of Example 75 which contained 5 weight percent of the graft copolymer of Example 69, and dry blends of the polypropylene of Example 74 with 1 and with 5 parts of the graft copolymer of example 69.
Blown film was produced on a"Killion"blown film line (Killion Extruders Co., Cedar Grove, NJ), which consists of a 25.4-mm, single-screw extruder operating at a melt temperature of about 216~C., a 50-mm spiral mandrel die, air input for producing a bubble, and a Killion vertical-blown -film tower. The blown-film tower contains two nip rolls for collapsing the bubble and a means for pulling the film through the nip rolls. The die and pull speeds are adjusted to produce film about 5.6 mm thick (two thicknesses) and either 108 or 165 mm wide, the blow-up ratios being 2.125 and 3.25 respectively, at respective top nip speeds of 7.65 and 5.94 meters/minute.
T~hle XXV
Film of Materials Thickness 20 ~m~
Ex. 95 Ex. 74; no GCP 0.051 - 0.066 Ex. 96 Ex. 75; 5~/. GCP, Cmpd. 0.056 - 0.064 Ex. 97 Ex. 74; 5~h GCP, Dry Blend 0.051 - 0.058 Ex. 98 Ex. 74; 1 % GCP, Dry Blend 0.051 - 0.058 * Trad~mark ,. ..... ,, .. . .,. .. .,~., ,w,~ , ,~, ...
13400~6 Himont 6523, mfr=4, homopolymer polypropylene was blown into 0.02~mm-thick film (single layer) as Example 95 (control). The bubble was slightly lopsided, and the frostline (onset of cryst~ tion) was at an angle to the die. A lopsided bubble results in less uniforrn film thicknesses.
With 5% of the ~raft copolymer of Ex. 69 present, the bubble of Example 96 was stabilized, the frostline lovall3d, and the frostline moved closer to the die. Both 108- and 1 65-mm, lay-flat films were produced Althou~h some fluctu~tion in die pressure was noted when Fuin,ing the latter film, it had the most stable bubble.
This increase in bubble stability was also observed with the 1%
and 5% dry blends of Examples 97 and 98. No signiFicant differences in film appe~r~nce was observed between the 5~~O precompounded blends and the dry bh~nds.
l 5 The modified films had decreased film see-through clarity.
Contact clarity remained unchanged. No difference in edge-roll color was observed belw6en modified and u~,i"GdiFi~d film.
The ~openability~ of neat and ",~ilied film was tested. Although a very qual~ative test (the collapsed film is snapped between the fingers and one feels how well it opens), no difference between the unmodified and ",odil:~ resins was observed.
FXAMpl F~ 99 -104 The experime~ts illustrate the use of the graft polymer of the pr~senl invention in producing polypropylene cast film. A single-screw extruder, manufactured by Killion Co., was e~ irped with a 3.81-cm screw of 2411 length/diameter ratio, a 20.3-cm x 0.635-mm cast film die, i 13~0~fin a chill roll and a torque winder for the film, was utilized. The extruder melt temperature was 226~C. The melt was extruded through the die and onto the chill rolls, the take-up speed being ~f1justed to produce film of various thicknesses. Film thicknesses was measured, as was ~neck-in~, an undesirable shrinkage of width. hlm stiffness and edge roll color were measured qualitatively. Film thicknesses were adjusted increasin~ line speed of the torque winder and lowering the extruder output by reducing screw speed.
TARI F XXVI
Film of Starting Material Form 1 0 rY~
Ex. 99 Ex. 74 Unmodified Ex. 100 Ex. 75 Pre-blend; 6% GCP
Ex. 101 Ex. 74 and Ex. 69 Dry blend; 5% GCP
Ex. 102 Ex. 81 Unmodified Ex. 103 Ex. 82 Pre-blend; 1% GCP
Ex. 104 Ex. 83 Pre-blend; 5% GCP
GCP s graft copolymer of Example 69 Films of the composition of Example 99 were uniform and consistent at thicknesses of from 0.25 mm to below 2.5 mm. Example 100 produced ~ept~ble film of improved ed~e color and with less film neck-in. Example 101 also prod~Jced less neck-in, but did not improve edge color. Both rnodified versions yielded stiffsr films at equivalent thickness versus the control, allowing ths fllm to be wound more easily.
The opacity of the film increased with th~ addition of the graft polymer.
13~006~
With Examples 102 to 104, the neck-in differences were not noted when the graft copolymer additive was present. The films at both 1 and 5 weight percent graft copolymer were stiffer than the unmodified control (Examples 103 and 104 versus Example 102).
FxAMpl F 105 This example illustrates that biaxially oriented film can be prepared from a polypropylene rssin containing 5% of the polypropylene/methyl methacrylate graft copolymer. Under the limited conditions tested, which were optimum for the unmodified resin, no distinct advantage could be seen for the additive. At identical extrusion and MDO (machine direction orientation) conditions, the modified resins could not achieve and maintain the line speeds possib!Q with the u~""GJif;ed resin during the TDO (transverse direction orientation).
The control resin was Example 81, mfrs2.2, high-clarity homopolymer marketed for film use. Pre-compounded resins were Examples 82 and 83, containing respectively 1% and 5% of the graft copoly",er of Example 69 (under the extrusion conditions, a dry blend of-5 parts graft copolymer of Ex. 69 with the matrix resin of Example 81 gave very poor dispersion, leading to many gels and frequent film breaks). The blends were pn~cessed in a 50.8-mm, Davis-Standard single-screw extruder which conveyed the melt through a 0.48-meter die and onto a 1 .02-meter casting roll. An air knife was used to blow the extrudate onto the casting roll. The casting roll rotat~d through a water bath to completely quench the sheet. The sheet then was conveyed into the MDO, supplied by Marshall and Williams Co., Prov:dence, Rl, and co",pRsin~ a series of heated nip rolls, moving at speeds which cause monoaxial orientation.
1 3 ~ O 0 6 ~
After the MDO, the film passed through a slitter to cut the film to the proper width and then onto a winder. These rolls were used to feed the film into the TDO, whkh is an oven with three heating zones, rolls for conveying the film forward, and clamps to grip and laterally expand the film.
The tilm from Example 81 ~unmodified resin) was drawn both 4.75:1 and 5.0:1 in the MDO, and could be drawn 9:1 in the TDO. The unmodified 4.7~:1 MI~O resin could maintain a TDO line speed of 8.69 meters/minute; the un"loditied 5.0:1 MDO resin could maintain a line speed of 6.85 meters/minute .
The fiim from Example 82 (1% graft copolymer) could receive a MDO of 4.75:1 and TDO of 9:1 and maintain a 6.85-meters/minute TDO
line speed. Frequent film b,l,~l~ge was encountered at higher MDO
and higher line speeds. This biaxially oriented film appeared to be slightly more op~que than the biaxially oriented film trom Example 80.
No differsnce between the edge roll colors of film from Examples 81 and 82 was observed for MDO film.
The films from Example 83 received MDO's of 4.75:1, 5.0:1, and 5.25:1 at a TDO of 9:1. The best film was obtained with a line speed of 6.85 mete!s/minute and with the lowest MDO; tearing would occur under more ~tlssseJ condi~ions. Films from Example 83 were notice~hly more opaque and the frost line appeared sooner than with the control film of Example 81.
FXAMPl F 106 This example illu~trates a profile extrusion trial using polypropylene modified with a graft copolymer of the present invention.
A single-screw extruder was equipped with a die and apprupria~e cooling, pulling, and sizing equipment to forrn a profile in the shape of a ,,, ~ 1. ' .. .11 ' ': "' ' " '" " '--' ' " " ' .
1~4036~
solid rod with horizontal flanges. The rod diameter was 4.83 cm., flanges 2.67 cm. (extended beyond rod), and flange thickness 1.52 cm.
With un-no~litied resin ¦Tenite ~E11 copolymer, Eastman Chemical, as described in Example 78), symmetry was difficult to maintain in the profile without sag or distortion. When blends of Example 79 and 80 (1 and 5% graft copolymer, respectively) were employed, the maintenance of shape was improved.
This example illustrates the use of a graft copolymer blend of the present invention in the modification of polypropylene to produce improved plastic tubin~. The polymers used were the unmodified resins and the resins compounded with 5% of the graft copolymer of Ex. 69, as described in Examples 72 to 77.
A 25.4-mm, single-screw"~<illion'~xtruder (Killion Extruders Co., Cedar Grove, NJ) was equipped with a screw of 24/1 length/diameter ratio, a tubing die with an outer die diameter of 11.4 mm. and a variable inner diameter, leading to a 0.25-meter-long water trough for cooling, an air wipe, and a puller and cutter. Conditions and observations are shown in Table below. Ovality is the ratio of smallest outer dia,ne~er to largest outer diameter, as measured by calipers; a value of 1 means the tube is uniformly round.
When tubing of good ovality was produced from the unmodified resin, the major effect of the additive was improvement in tubing stfflness.
With the resin of Example 72, where ovality was dimcult to control at acoeptabb output rate~;, the ",odif;e-J re~in (Example 73) improved ovality as well as ~tiffl.ess * Trademark ~!
1 3 4 ~ ~ ~ ~' T~hle XXVII
Tubin~ Pre~red from PolyDro~ylene ~nd Modifierl Poly~ropylene Polymer Meit Melt Inner Ovality Temperature, Pressure, Diameter s ~C kP~) mm (~et~
Ex. 72 217 8270 8.1 0.75 Ex. 73 214 6890 8.1 0.88 (b) Ex. 74 185 9650 8.1 0.97 Ex. 75 197 6890 8.1 (c) 0.77 o Ex. 76 184 6890 8.1 (d) 0.92 Ex. 77 180 8270 8.1 (d) 0.90 (b,e) (a) Extrusion rate equivalent for paired un",odi~ied and modified resin.
(b) Modified extrudate tube stiffer.
(c) Higher melt temperature required to avoid ~sharkskin" on tubing.
(d) With this higher mfr resin, reduced meH temperature and higher puller speed led to tubing of lower outer diameter.
(e) Modified tubing more opaque.
This example illustrates the preparation of pre-compounded blends containing talc The talc used is a white, soft, platy talc of particle size less than 40 ~mj known as'Cantal'hIM-45-90 (Canada Talc Industries Limited, Madoc, Ontario). It was used at the 20% level. The polypropylene used was a homopolymer of mfr.4, known as~lHimonr*
6523. The graft copolymer was incorporated at the 5-weight-percent * Trademark 1~4006~
level and was the graft copolymer of Example 69. The compounding/prepar~lion of these samples was carried out on a 30-mm Werner rneiderer co-~olating, t~nn-screw extruder. The materials were tumble blended prior to the compounding.
TARI F XXVIII
Blend % Talc Modifier Matrix Polymer Example 108 (control) 20Cantal -- 80% Himont 6523 Example 109 20Cantal 5% Example 75%Himont6523 The preparative conditions for the blends are given in Table XXIX.
The extruder was op~.ated at 200 rpm, with no vacuum, at rates of 4.5 -4.6 kg/hour, and 8596% torque.
TAEII F XXIX
FYtrud61r 7~ne ~etting~. ~C
FY~ e 108 F~ 109 ZQQ~ set DoinU~ i set ~oinV~tual Z-8 (die) 225/ 239 225/ 239 Melt 239 243 .. ... ,. ".~. . . ..
1~40066 FXAMPi FS 1 10 -1 17 These examples teach the injection molding of polypropylene of various compositions and melt flow rates, the polypropylenes containing a graft copolymer of the present invention. In two examples, a 20% loading of platy talc is also present.
Polypropylene may be injection molded into useful objects by employing a rec;procaling-screw, injection-molding machine such as that of Arburg Masch-en Fabrik, I ossburg, Federal Republ ~ of Germany, Model 221-51-250. In the preparation of test samples, the extruder is equipped with an ASTM mold which forms the various test pieces. The conditions chosen for molding were unchanged throughout the various matrix and modified matrix polymers, and no difficulties in molding were noted. Table XXX describes the blends which are molded; Table XXXI teaches the molding conditions; Table XXXII reports modulus values, Table XX)(III Dynatup impact data, and Table XX~(IV heat distortion temperature values for the modified polymers and their controls.
In the fol'o- ,ny list of injection-molded polymers and blends, all samples contain 1 or 5 weight percent of the graft copolymer of Example 69. The polypropylene matrix resins are described in earlier examples; HP is homopolymer, CP is copolym~r, the number is the mfr value. The blends with talc are described in Examples 108 and 109.
All materials were pre-blended in the melt, except where a dry blend from powder was directly molded. (C) is an ur""odi~ied control; (CT) is a control with talc, ~t no graft copoly",er All test methods were by ASTM standard methods: flexural modulus and stress are by ASTM Standard Method D 790, heat 134006b distortion temperature under load is by ASTM Standard Metl,od D 648 and Dynatup impact is by ASTM Standard Method D 3763.
Table XXX also includes the melt flow rates (mfr) for the unmodified and pre-compounded blends. In most cases, the melt flow rate is unchanged or slightly decreased in the presence of the graft copolymer, so that the melt viscosity under these intermediate-shear conditions is not exlensively incr~ased. The melt flow rate is by ASTM
Standard Method D-1238, condition L (230~C., 298.2 kPa) and has units of grams extruded/10 minutes.
TARI F XXX 1 3 4 0 q 6 n Exam~le Matrix ~r~ft. % T~l~. % Dry-Blend? mfr 74 (C) HP, 4 -- -- -- 4.40, 4.06 HP,4 5 -- -- 6.07 110 HP,4 5 -- YES
108 (CT) HP, 4 -- 20 --109 HP, 4 5 20 --76 (C) CP, 4 -- -- -- 4.47 77 CP, 4 5 -- -- 3.75 111 CP,4 5 -- YES
72 (C) CP, 2 -- -- -- 2.37 73 CP, 2 5 -- -- 2.02 112 CP, 2 5 -- YES
78 (C) CP -- -- -- 2.92 79 CP 1 -- -- 2.04 CP 5 -- -- 2.12 81 (C) CP -- -- -- 2.33 82 CP 1 -- -- 3.81 83 CP 5 -- -- 2.16 TARI F XXXI
Injection Molding Condltions fo- Polypropylene Cylinder temper~tl Ires. ~C (settin~,lme~cl Ired) Feed -216/216 Metering -216/216 Compression -216/216 Nozzie 216/216 Mold Temperatures, ~C
Stationary -49/49 Moveable -49/49 Cycle time, seconds Injection forward -14 Mold Open -0.5 Cure -14 Total Cycle -0.5 Mold Closed -1.2 Machine readings:
Screw speed (rpm) - 400 Back pressure (kPa) -172 Injection (1st stage~(kPa) - 861 The flexural modulus data from Table XXXII indicate the stiffening effect of the graft copolymer. Results are in me~ C (mPa).
134006~
T~RI F XXXII
FLEXURAL STRESS
Example MODULUS ~at max) mP~ mP~
74 (C) 1470.6 43.8 1744.4 47.5 110 1783.1 46.9 108 (CT) 2768.0 52.0 109 2867.0 54.5 Table X)O~III summarizes Dynatup impact data (in Joules) at various temperatures for the blends and cG~nrols tested. The data indicate, in general, slightly improved impact for the pre-blended materials, a deterioration in impact sl-e"ylh on molding dry blends of graft copolymer and matrix polymer, and an increase in impact strength for the talc-modified blend also containing the graft copolymsr.
1340~6~
T~RI F XXXIII
Dynatup Impact Uoules) at TestTe",~r~ re.~C
Fxample ~.~ 15 5 -574 (C) 4.9i2.7 4.4i1.5 3.8iO.3 2.6i.41 5.7i3.4 4.6iO.8 2.7i1.5 3.4i1.09 110 3.4i1.1 2.0~0.5 1.9i1.0 1.5i.41 108 (CT) 3.0iO.5 3.4iO.8 4.2i1.6 5.0i2.5 109 1.9iO.5 4.1i2.3 4.8i1.8 5.0+2.5 76 (C) 40.0iO.5 77 43.9iO.4 111 14.0i6.4 72 (C) 37.9+1.8 73 43.1i10.3 112 32.4i9.5 78 (C) 36.7iO.4 79 36.3i1.1 37.1iO.7 81~ (C) 13.3i10.7 --- 3.3+0.8 2.7iO.2 82 4.9iO.7 ---- 3.0i1.4 3.0+0.8 83 7.6i3.7 ---- 3.3iO.8 3.5i1.1 The large standard deviation at room temperature is suspect.
Tabb XXXIV pr~senls heat distortion and hardness values for one series. The modifed polymer appedl~ to exhibit a slightly higher heat distG,tion te,-lper~ture and hardness, aîthough there are inconsislencies noted. The Rocku~611 hardness values represent 134006~
separate determinations on two samples of the material from the in~ ted example.
T~RI F XXXIV
Heat Deflection Temperature Rockwell Hardness Example ;~t ~~-:/Mi~ute ~t "C" ~ lP
411 kPa 1645 kPa 74 (C) 110.9 61.0 58.4 56.5 113.8 63.3 60.7 59.3 110 117.3 68.7 57.9 46.9 108 (CT) 128.2 76.8 57.3 64.7 109 124.7 81.9 65.4 63.7 FXAMPl F 113 This example illustrates the effect of the molecular weight of the polypropylene trunk component of the graft copolymer on the sag ",odifica~ion of polypropylenes ot various molecular weights. Graft copolymers were prepared from polypropylene of various melt flow rates. All modifiers were prepared as in Example 58. The 35 mfr polypropylene ~limont PD-701) was run at 65% solids. The 12 mfr polypropylene ~himont Pro-fax 6323) was nun at 60% solids. The 4 mfr polypropylene lHimont Pro-fax 6523) and the 0.8 mfr polypropylene '~Himont Pro-fax"6723) were run at 55% solids. The molecular weights for the polypropylene base resins, where known, are given in Table XXXV, below.
These were ev~lu~1ed as melt slr~nsJ~ll improvers at 4% by weigh in several of these same polypropylenes. Standarc~ mill and press conditions were used for all blends, except the 0.8 mfr/0.8 mfr * Trad~nark . ..
1~400fi~
polypropylene blends which were milled at 215~C and pressed at 215~C. Sag rates were measured by the standa-rd prucedures. The sag slope at 190~C is reported in Table XXXVI, below.
T~RI F XXXV
MW-~FR D~t~ for Poly~ro~ylene RAse Res;n Molecular-Weight Wei~ht-Aver~e ~lecul~r We;~ht x 10~ _ So~rce 1~ ~fr PP 4 mfr PP 0.8 mfr PP
~a) 3 4.3 7.1 (b) 2.45 3.05 3.5,4.7 (c) 0.27* 0.45~ --Source of Molecular-Weight Value: a) Supplier's data. b) Sheehan et al, J. Appl. Polymer Sci., 8, 2359 (1964). c) Mays et al, ibid., 34, 2619 (1987).
* These values are nllmh~r-~ver~e molecular weight.
TABI F XXXVI
S~ SloDe ~t 190~C for Olefin Blen~ ( min-1L
~oly~ro~y]~ne hA~e res;n (96%) m~;fier (4%) 35 mfr PP 12 ~fr PP 4 ~fr PP 0.8 mfr PP
none 1.6 0.52 0.250.099 35 mfr PP based 1.8 0.52 0.23 0.074 12 mfr PP based 1.2 0.41 0.034 < 0.02 4 mfr PP based 1.0 0.16 0.022 < 0.02 0.8 mfr PP based 0.64 0.16 0.031 << 0.02 In all cases except where a high-melt-flow base resin was modified with a graft polymer having a trunk of high-flow-rate (low-molecul-r-weight) polypropylene, sag improvement was observed. The molecular weight for the resin of mfr=35 is not accurately known; it is believed to be made by therrnal/oxidative processing of a higher molecular weight resin. Such a process would both lower the molecular weight and narrow the originally broad mol~cul~r-weight distribution.
This example illustrates the effectiveness of the graft copolymers of the present invention as comp~tibilizing agents for polymers that are otherwise poorly compatible. In this example a polyolefin, a polar polymer, and the graft copolymer of the present invention were compounded in an intermeshing, co-rotating, twin-screw extruder (Baker-Perkins MPC/V 30) with a screw length-to-diameter ratio of 10:1.
The compounder was run at 200 rpm and temperatures were adjusted to acco"""odale the polymers in the blend and achieve a good melt.
The melt temperature in the compounding zone is recorded in the second column of the table. The melt was fed directly to a 38-mm, single-screw, pelletizing extruder with a length-to-diameter ratio of 8:1.
The melt temperature in the transition zone between the compounding and the pe"s~i~ing extruder is shown in column 3 of Table XXXVIII, below. The melt was extruded into st-dr,ds through a die, cooled in a water bath, and cut into pellets.
Table XXXVII below summarizes the polymers which were used in the blends of the present example, while Table XXXIX shows that the graft copolymer has little effect upon the tensile strength of the unblended polymers, that is, it does not act to a significant degree as a toughening agent. !n the s~bse~usnl tables, Tables XL and XLI, improvement in tensile strength of the blended polymers indicates an increase in compatibility of the blended polymers with one anotl,er in the presence of the graft copolymers of the presenl invention.
l~OI~fifi Under the proper compounding conditions, an increase in comr~t;bility may also produce a decrease in the size of polymer domains in the blend. Scanning electron mic-uscopy confirms that in some of these examples, significant domain-size reductions occur when the graft copolymer is added. For example, the polypropylene domains average 2 micrometers in the 70 PMMA / 30 PP blend of example 114.
The addition of 5 phr co",palibili~er re~uced the domain size to 0.5 ~m.
The addition of 15 phr compatibilizer reduced the domain size to 0.43 ~m. Although not all of the domain sizes were reduce~, several others were reduced by 10-30% by the addilion of 5 phr compatibilizer. This is a further suggestion that the compatibilizer is acting on the inle, ~ce of the polymer domains rather than on the individual polymers.
Table XLI summarizes the compatibilizing effect of the graft copolymers upon the various polymer blends.
1~40~fi~
TABI F XXXVII
Poly~ers Used in the Blen~ ~xAm~les Other Polymer and Designation Grade Spec. Specifi-in T~hles Pro~ucer Desi~n~tion Grav. ~tions SAN Monsanto "Lustran"SAN 33 1.07 mfr=14 Styrene-Acrylonitrile ASTM D 1238 Polymer Cond.~I) PA66 DuPont "Zytel"101 1.14 mp=255~C
Nylon 6-6 (D2117) PET Eastman ~IKodapak"PET 1.4 mp=245~C
Polyethylene Kodak 7352 (DSC), Terephthalate iv=0.74 EVOH EVAL Co. "Eval" EP-E105 1.14 44 mole% E, Ethylene Vinyl of America mp=164 C, Alcohol Copolymer mfr-5 5 2160 g) PC General "Lexan"121 1.20 mfr=16.5 Polycarbonate Electric ASTM D 1238 Plastics Cond. ~O) PVC Georgia SP-7107* 1.35 PolyvinylChloride Gulf Corp.
PMMA Rohm and "Plexiglas"VM 1.18 mfr=15 Poly(Methyl Haas Co.
Methacrylate) EP Exxon "Vistalo~'719 0.89 54 Mooney Ethylene Propylene (D-1646) Copolymer HDPE Phillips "Marlex"* 0.950 mfr=4 High-Density 66 Co. HMN 5060 Polyethylene PP Himont "Pro-fax"6523 0.903 mfr=4 Polypropylene EVA DuPont "Elvax"650 0.933 12% VA
Ethylene Vinyl Acetate mfr=8 * Trademark (each instance).
,. .
l3~oo6o TARI F XXXVII (continued) Other Polymer and Designation Grade Spec. Specifi-in T~hles Pro-lucer Designation Grav. ~tions LLDPE Exxon " Escorene "* 0.926 mfr=12 Linear Low-Density LL-6202 Polyethylene PS Huntsman PS-203 1.06 mfr=8 Polystyrene Chemical (crystal) PBT General " Valox' 6120 Poly~butylene Electric terephthalate) PA6 Allied " Capron"8253 1.09 mp=21~C
Nylon 6 Signal ABS Dow " Magnum"341 1.05 mfr=5 Acrylonitrile- Chemical Butadiene-Styrene Resin PC/PBT General "Xenoy~'1101 1.21 Polycarbonate/ Electric Poly(butylene tere-phthalate alloy * Tr~A~m~rk (each instance.
134006~
T~RI F XXXVIII
m~lt t~m~er~tures (~C) co~o--nder tr~nsition The pellets were dried and injection molded on a reciprocating-screw injection molding machine'~New Britair~'Model 75) into test specimens.
~rademark l340a~fi TABI F XXXIX
~ffect of Cc~patihilizer ~n Polymer Tensile Strength Tensile St~engthq Shown in Me~PASrAl S ~PA) com~Atihilizer concentration Polymer 0 phr 5 ~hr 15 ~hr PMMA65.44 64.79 61.27 SAN 71.91 62.74 55.89 EVOH68.78 66.21 63.78 PA6664.82 64.68 66.60 PET 58.26 59.33 59.72 PVC 45.25 44.97 45.22 PC 62.63 63.05 63.70 HDPE22.59 22.66 24.14 PP 33.02 34.03 33.95 EP 4.79 5.50 5.84 LLDPE10.91 11.80 12.99 EVA 8.64 8.67 8.17 13~0~fi6 T~RI F Xl Tensile Str~ngths (MPa) of ~l~n~c of Polyolefins ~nd Pol~r Polymers 30% pol~r ~olymer 55% ~ol~r Doly~Pr 80% ~ol~r ~olymer polar poly~r Ophr ~hL l~h~ Ophr SDhr 15phr Q~hL ~hL 15phr * PMMA 25.26 27.00 30.26 31.42 38.30 39.54 50.78 53.77 55.55 * SAN 25.77 28.09 30.57 34.71 41.51 38.33 51.88 55.08 51.23 * EVOH 26.57 26.80 27.74 33.18 38.00 39.58 49.24 51.32 50.79 PA66 26.94 28.85 29.72 38.34 38.11 38.33 61.22 65.62 69.23 PET 25.97 28.61 30.98 37.70 37.93 40.09 50.23 51.72 50.91 PVC 20.89 22.92 24.86 19.91 23.67 27.34 26.18 30.72 34.87 PC 25.66 28.80 30.93 31.11 35.20 38.53 55.61 50.41 51.92 _______________________ pp ________________________ * PMMA34.02 35.37 37.81 40.23 43.45 45.84 46.40 53.70 56.6 * SAN33.67 38.76 41.05 37.67 47.65 46.08 41.11 54.12 51.81 * EVOH32.85 37.40 38.56 35.01 44.65 45.60 42.73 53.38 52.57 PA6632.06 40.29 40.38 42.72 52.17 51.10 64.71 67.84 66.15 PET32.93 33.80 35.15 39.47 43.81 43.64 37.67 53.12 54.04 PVC36.32 37.68 39.35 35.28 37.87 40.79 30.88 40.00 42.56 PC33.82 36.68 39.09 36.69 40.13 44.64 42.38 46.24 51.64 ----------------------- EP ------------------------PMMA8.20 10.87 12.51 19.99 24.17 27.81 42.47 44.59 46.93 SAN8.10 12.53 14.11 22.14 28.82 28.15 45.92 50.68 44.58 EVOH12.19 12.04 11.69 24.92 24.66 23.17 41.29 42.39 42.70 PA6613.04 13.04 12.36 27.62 27.98 26.33 40.87 48.77 43.48 PET7.94 8.40 11.13 20.22 20.43 22.27 33.72 37.00 38.87 PVC6.17 9.05 12.88 12.93 18.28 19.22 25.50 28.41 30.60 PC10.31 12.05 13.66 23.10 24.34 25.60 40.18 41.79 42.76 ., .. ~
. ~
13~00fi~
T~l F Xl (çontinl-e~) Tensile Strengths (MP~) of Rl~n~.~ of Polyolef;ns ~n~ Pol~r Polymers 30~ polar poly~r 55% ~olAr po~ym~er 80% pol~r ~olymer polar polymer Ophr 5Dhr l~hL Q~hL ~hL l~hl Q~hL 5p~r 15phr ~ ---------------- LLDPE -----------------------PMMA 15.23 18.63 20.90 24.88 30.68 32.84 48.95 55.36 54.14 SAN 15.78 21.08 22.57 26.50 35.76 36.71 47.52 56.92 48.84 EVOH 16.83 17.26 18.26 30.02 31.74 31.87 51.83 50.71 52.29 PA66 17.93 17.99 19.98 29.67 28.49 25.23 64.65 67.55 67.26 PET 15.33 18.09 20.35 25.53 28.23 30.78 45.02 46.16 42.87 PVC 14.72 14.12 15.73 12.45 18.09 20.50 25.99 30.54 33.69 PC 13.64 19.20 18.48 19.22 27.83 30.46 38.45 40.59 38.86 ~~~~~~ ------- EVA -------_-_______________ PMMA10.57 11.28 14.38 23.06 21.10 28.31 45.99 47.02 50.87 SAN12.40 13.62 15.22 27.97 27.29 29.35 48.94 52.01 46.14 EVOH13.13 13.97 16.59 32.41 28.65 35.43 50.97 50.28 48.81 PA6614.15 13.54 14.42 27.36 24.59 26.92 40.75 38.35 31.60 PET14.55 14.35 12.31 21.22 23.90 26.45 43.20 43.91 48.44 PVC7.69 8.28 10.25 13.40 14.29 18.17 19.22 23.76 28.12 PC14.05 14.54 13.52 19.78 21.79 24.85 39.26 40.55 41.46 - polar polymer levels are 20, 45,and 70% instead of 30, 55 and 80%.
~ ......
., .. ~.. . ~ . .. , . " . .
TARI F Xl I
Effect of Compatibilizer on Tensile Strength of Blends of Polyolefins and Polar Polymers Incre~se in Tensile Stren~th ~P~) from the Co~tibilizer 30% polar polymer 55% pDlAr polym~L 80% ~olar polymer polar poly~er 5 phr15 phr5 Dhr15 phr 5 phr 15 phr PMMA 1.745.01 7.38 8.12 2.99 4.77 SAN 2.324.80 6.80 3.63 3.21 -0.64 *EVOH 0.231.17 4.81 6.39 2.08 1.54 PA66 1.902.77 -0.23 -0.01 4.40 8.00 PET 2.655.01 0.23 2.39 1.48 0.68 PVC 2.033.97 3.76 7.43 4.54 8.69 PC 3.145.27 4.10 7.42 -5.20 -3.69 ________________________ pp ________________________ *PMMA 1.353.79 3.225.61 7.29 10.22 SAN 5.097.38 9.988.41 13.02 10.70 *EVOH 4.565.72 9.6410.59 10.65 9.83 PA66 8.238.32 9.458.38 3.13 1.44 PET 0.862.22 4.344.17 15.44 16.37 PVC 1.363.03 2.595.51 9.11 11.68 PC 2.865.27 3.437.94 3.85 9.26 .. , . . . ~ ,,. , ~
1~400~6 TARI F ~ çontinued~
IncreAse in Te~sile Stren~th (~PA) fro~ the Cc~DAtihili7er 30% polAr poLYr~r 55% polAr polymer 80% pol~r polymer polar polym~r5 phr 15 phr 5 phr 15 phr 5 Dhr 15 phr _____________________--- EP --~~~~~~~~~~~~~~~~~~~~~~
PMMA2.664.30 4.18 7.82 2.12 4.46 SAN4.43 6.01 6.68 6.01 4.76 -1.34 EVOH-0.15-0.50 -0.27 -1.75 1.10 1.41 PA660.01-0.68 0.36 -1.29 7.90 2.61 PET0.46 3.19 0.21 2.05 3.29 5.16 PVC2.86 6.71 5.35 6.29 2.91 5.10 PC1.74 3.35 1.24 2.50 1.61 2.59 ~--------------------- LLDPE -----------------------PMMA3.405.67 5.80 7.96 6.42 5.19 SAN5.31 6.80 9.26 10.21 9.40 1.32 EVOH0.431.43 1.72 1.85 -1.12 0.45 PA660.062.05 -1.19 -4.44 2.90 2.61 PET2.76 5.01 2.70 5.25 1.14 -2.14 PVC-0.59 1.01 5.64 8.05 4.56 7.70 PC5.56 4.85 8.61 11.24 2.14 0.41 ----------------------- EVA ------------------------PMMA0.713.81 -1.95 5.25 1.03 4.87 SAN1.22 2.81 -0.68 1.38 3.07 -2.80 EVOH0.833.45 -3.75 3.02 -0.68 -2.16 PA66-0.610.27 -2.77 -0.44 -2.40 -9.15 PET-0.20 -2.25 2.68 5.23 0.70 5.24 PVC0.59 2.56 0.89 4.76 4.54 8.89 PC0.49 -0.53 2.01 5.07 1.30 2.20 ~ - polar polymer levels are 20, 45 and 70% instead of 30, 55 and 80%.
13iO066 T~RI F Xl ll ComD~tih~ tion Fffect E~ PP ~ ~ E~a PMMP. +++ +++l +++ +++ +++
SAN +++ +++ +++ +++ ++
EVOH ++ +++l o o ++
PA6 6 ++ +++1 + + o PET + ++l ++ ++ ++
PVC +++ +++ +++ ++l ++
1 0 PC ++ +++l + ++ +
+++ - compatibilization at all three polyolefin-polar polymer ratios (not necessarily at all comp~tibili~er levels) ++ - compatibil~ tion at two of the three polyolefin-polar polymer levels + - cG")pdlibilization at one of the two polyolefin-polar polymer levels 15 0 - no competibili~~tion seen at any polyolehn-polar polymer ratio, at any compatibilizer level (1 ) - additional evidence for compatibilization in the reduction of domain size by 1 0-80%
FxAMpl F 1 15 The compatibilizing effect on selected, additional polymer pairs was evaluated in the fol'D~:;ng example. The blends were compounded, molded and tested tor tensile strength as previously described. The results in Table XLIII again indicate that the compatibilizer has minimal or a negative effect on the polar polymers, but a positive effect on the polar / nonpolar polymer blends. A large tensile ~ afi!Jtll i,..pru~lroment is seen for the ABS / PP blend. Smaller but significant improvements are seen for the blends of PP with PA6 and with PC / PBT. With the PS blends ev~u~ted the effect was negligible.
13~0066 TABI F ~
ten~ile ~tren~th.q (~PA ) polar polymer + blendl +
15 phr 15 phr polar nonpolar polar graft graft -polymer po]y~r polymer co~oly~er hl en~l copolym~r PBT PP 43.02 45.11 36.96 38.96 PA6 PP 56.11 51.67 43.50 47.04 PS PP 45.26 40.45 38.88 37.36 PS HDPE 45.26 40.45 36.48 33.76 ABS PP 51.25 52.25 32.25 42.55 PC/PBT PP 51.77 51.79 38.99 41.88 1 - blend in all cases refers to 55 parts by weight polar polymer and 45 parts by weight nonpolar polymer.
The effect of ths graft copolymer on multi-component blends such as those ~epresentative of commingled scrap polymers are shown in Table XLIV. In all cases a siyni~icant inclease in tensile :.l,enyll, is observed when the compatibilizer is pr~senl.
l-~RI F Xl IV
Com~tibili7~tion of Multicomponent Rlend5 Tensile Pol~r Poly~rsNQ~pol~r Polymers Co~p~t;h;li2er Strength (~P~ ) E~ ~Y~ E LLDPE ~
12 7 5 33.5 33.5 9 none 16.27 12 7 5 33.5 33.5 9 5 17.67 12 7 5 33.5 33.5 9 15 21.77 12 8 - 35 35 10 none 18.62 12 8 - 35 35 10 5 19.98 12 8 - 35 35 10 15 22.16 12 - 6 36 36 10 none 17.06 12 - 6 36 36 10 5 19.21 12 - 6 36 36 10 15 21.91 FxAMpl F 1 16 This example further illustrates compatibilization of polymer blends usin~ graft copolymers of the present invention.
Blends of ethylene-vinyl alcohol copolyme;(Kuraray EP-F101A), polypropylene '~Himont'6523) and graR copolymer were milled on a 7.62-cm X 17.78-cm electric mill at 204~C to flux plus three minutes.
The stocks were pres6ed at 204~C and 103 MPa for three minutes (Carver Press, 12.7 crn X 12.7-cm X 3.175-mm mold)and at room temperature and 103 MPa for three minutes. Two graR copolymers were used in this example. The first (Graft Copolymer A) was a poly,un,pylene - acrylic graR copolymer prepared from mfr=4 polypropylene hGl"Gpolymer (100 parts) and a 93:2:5 mixture of methyl * Trad~rk .. . . ~ . .... . . .. .
,, 1340066 methacrylate:ethyl acrylate:methac~lic acid (100 parts). Polymenzation was done in Isopar E solvent at 1 60~C at 50% solids ovsr ons hour with a di-t-butyl psroxide radical flux of 0.00012. The product isolated contained 44% acryla~e. The sscond graft copolymer ~Graft Copolymer ~; B) was a polypropylene - acrylic graft copolymsr prspared from mfr=4 propylene ho"lopoly~er (100 parts) and a 95:5 mixture of methyl Ine~l,acrylate:sthyl acrylate (150 parts). Polym~rization was done in Isopar E solvent at 1 55~C at 60% solids. The feed time was 60 minutes and the radical flux was 0.00010. the product contained 53% acrylate.
Addition of the graf~ oopolymer results in an increase in tensile strength and modulus.
TA~ F ~l y Co~tihjli7~tion of FyOH ~nd Polv~ro~ylene notched graft Izod tensile tensile EVAL PPcopolymer tensile strength modulus ~ I~r~m~ rAm~r~m~) (J/~ (~p~) (~PA) 0 21 29.85 2570 51 21 48.06 3190 52 22 46.75 3270 0 18 21.37 1930 151 18 29.79 2140 152 13 30.41 2030 1 - Graft Copolymer A (see text abovs).
2 - Graft Copolymer B (see text above).
1~4006~
While the invention has been descnbed with reference to speafic exa",pl3s and applications, other ",o~lificaliGns and uses for the invention will be apparent to those skilled in the art without departing from the spirit and soope of the invention defined in the appended claimS~
. ,, . . , . . ~ .. v
Claims (26)
1. A method for improving the compatibility of a blend of one or more non-polarpolymers with one or more polar polymers which comprises incorporating into the blend from about 0.2 to about 10 parts per hundred parts of the blend of a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene), copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid, saidtrunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight average molecular weight of from about 20,000 to 200,000, and being present in a weight ratio with said trunk of from about 1:9 to about 4:1.
2. The method of claim 1 wherein the amount of graft copolymer incorporated into the blend is from about 0.5 to about 5 parts per hundred parts of the blend.
3. The method of claim 1 wherein the amount of graft copolymer incorporated into the blend is from about 0.8 to about 2.5 parts per hundred parts of the blend.
4. The method of claim 1 wherein the ratio of polar polymers to non-polar polymers is from about 95:5 to about 5:95.
5. The method of claim 1 wherein the ratio of polar polymers to non-polar polymers is from about 80:20 to about 20:80.
6. The method of claim 1 wherein the non-polar polymer is a polyolefin and the polar polymer is selected from the group consisting of acrylic polymers, styrene-acryonitrile polymers, ethylene-vinyl alcohol polymers, polyamides, polyesters, polycarbonates, poly(vinyl chloride), acrylonitrile-butadiene-styrene polymers, poly(vinylidene chloride), blends of polyesters with polycarbonate and blends ofpoly(vinyl chloride) with polyester.
7. The method of claim 6 wherein the polyolefin is polypropylene.
8. The method of claim 6 wherein the polyolefin is polyethylene.
9. The method of claim 1 wherein the non-polar polymer is ethylene-vinyl acetate and the polar polymer is selected from the group consisting of acrylic polymers and polyvinyl chloride.
10. The method of claim 1 wherein the non-polar polymer is a terpolymer of ethylene, propylene and a non-conjugated diene, and the polar polymer is selected from the group consisting of acrylic polymers, polyesters, poly(vinyl chloride),polycarbonates and blends of polycarbonate with polyester.
11. A blend of one or more polar polymers with one or more non-polar polymers and a graft copolymer having a non-polar polyolefin trunk selected from the group consisting of polyethylene, polypropylene, polybutylene, poly(4-methylpentene) copolymers of said olefins with each other, and copolymers of said olefins with 1-alkenes, vinyl esters, vinyl chloride, (meth)acrylic esters, and (meth)acrylic acid, said trunk having a weight average molecular weight between about 50,000 and 1,000,000; and covalently bonded to said trunk a methacrylate chain polymer derived from at least about 80% of a monomer of a methacrylic ester of the formula CH2=C(CH3)COOR, where R is alkyl, aryl, substituted alkyl, substituted aryl, or substituted alkaryl, and less than about 20% of an acrylic or styrenic monomer copolymerizable with the methacrylic ester, said methacrylate chain polymer having a weight average molecular weight of from about 20,000 to 200,000, and being present in a weight ratio with said trunk of from about 1:9 to about 4:1, the compatibility of the blend being superior to that of a blend of the non-polar polymers and polar polymers in the absence of the graft copolymer.
12. The blend of claim 11 wherein the non-polar polymer is a polyolefin and the polar polymer is selected from the group consisting of acrylic polymers, styrene-acrylonitrile polymers, ethylene-vinyl alcohol polymers, polyamides, polyesters, polycarbonates, poly(vinyl chloride), acrylonitrile-butadiene-styrene polymers, poly(vinylidene chloride), blends of polyester with polycarbonate and blends of poly(vinyl chloride) with polyester.
13. The blend of claim 12 wherein the non-polar polymer is polypropylene.
14. The blend of claim 12 wherein the non-polar polymer is polyethylene.
15. The blend of claim 14 wherein the polyethylene is high-density polyethylene.
16. The blend of claim 11 wherein the ratio of polar polymers to non-polar polymers is from about 95:5 to about 5:95.
17. The blend of claim 11 wherein the ratio of polar polymers to non-polar polymers is from about 80:20 to about 20:80.
18. The blend of claim 11 wherein the non-polar polymer is ethylene-vinyl acetate and the polar polymer is selected from the group consisting of acrylic polymers and polyvinyl chloride.
19. The blend of claim 11 wherein the non-polar polymer is a terpolymer of ethylene, propylene and non-conjugated diene, and the polar polymer is selected from the group consisting of acrylic polymers, polyesters, poly(vinyl chloride),polycarbonates and blends of poly carbonate with polyester.
20. The blend of claim 19 wherein the polar polymer is a polyester.
21. The blend of claim 20 wherein the polyester is poly(ethyleneterephthalate).
22. The blend of claim 11 wherein the non-polar polymer is high-density polyethylene and the polar polymer is selected from the group consisting of ethylene-vinyl alcohol, polyester, poly(vinyl chloride) and poly(vinylidene chloride).
23. The blend of claim 22 wherein the polar polymer is a polyester.
24. The blend of claim 23 wherein the polar polymer is poly(ethylene terephthalate).
25. The blend of claim 11 wherein the polar polymer is an acrylic polymer.
26. The blend of claim 25 wherein the acrylic polymer is a polymer of a C1-C8 ester of acrylic acid or methacrylic acid.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17464888A | 1988-03-29 | 1988-03-29 | |
| US07/315,501 US4957974A (en) | 1988-03-29 | 1989-03-01 | Graft copolymers and blends thereof with polyolefins |
| US315,501 | 1989-03-01 | ||
| US174,648 | 1989-03-01 | ||
| CA000593171A CA1340065C (en) | 1988-03-29 | 1989-03-09 | Graft copolymers and blends thereof with polyolefins |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000593171A Division CA1340065C (en) | 1988-03-29 | 1989-03-09 | Graft copolymers and blends thereof with polyolefins |
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| Publication Number | Publication Date |
|---|---|
| CA1340066C true CA1340066C (en) | 1998-09-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000617058A Expired - Fee Related CA1340066C (en) | 1988-03-29 | 1996-08-28 | Graft copolymers and blends thereof with polyolefins |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116041855A (en) * | 2023-01-03 | 2023-05-02 | 青岛海泰科新材料科技有限公司 | High-melt-strength micro-foaming polypropylene composite material and preparation method thereof |
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1996
- 1996-08-28 CA CA000617058A patent/CA1340066C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116041855A (en) * | 2023-01-03 | 2023-05-02 | 青岛海泰科新材料科技有限公司 | High-melt-strength micro-foaming polypropylene composite material and preparation method thereof |
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