CA1333826C - Peroxide-free grafting of homopolymers and copolymers of ethylene having densities equal to or greater than 0.930 g/cm_, and use of the graft copolymers for the preparation of ionomers or adhesion promoters - Google Patents
Peroxide-free grafting of homopolymers and copolymers of ethylene having densities equal to or greater than 0.930 g/cm_, and use of the graft copolymers for the preparation of ionomers or adhesion promotersInfo
- Publication number
- CA1333826C CA1333826C CA000551584A CA551584A CA1333826C CA 1333826 C CA1333826 C CA 1333826C CA 000551584 A CA000551584 A CA 000551584A CA 551584 A CA551584 A CA 551584A CA 1333826 C CA1333826 C CA 1333826C
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- Prior art keywords
- peroxide
- ethylene
- grafted
- maleic anhydride
- weight
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
- C09J151/06—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F255/00—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
- C08F255/02—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00 on to polymers of olefins having two or three carbon atoms
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Graft Or Block Polymers (AREA)
- Adhesives Or Adhesive Processes (AREA)
Abstract
In a process for the per-oxide-free grafting of ethylenically unsaturated carboxy-lic acids, carboxylic anhydrides and/or their derivatives to a homopolymer or copolymer of ethylene having a den-sity equal to or greater than 0.930 g/cm3, the monomers to be grafted are used in a concentration of from 0.01 to 0.5% by weight and the grafting reaction is carried out at from 210 to 300°C in a conventional extruder or mixer in the absence of a free radical initiator. The graft copolymers are used for the preparation of ionomers and adhesion promoters.
Description
` 1 333826 - 1 - O.Z. 0050/38790 Peroxide-free grafting of homopolymers and copolymers of ethylene having densities equal to or greater than 0.930 g/cm3, and use of the graft copolymers for the preparation of ionomers or adhesion promoters The present invention relates to a process for the peroxide-free grafting of ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their derivatives onto ethylene polymers having densities equal to or greater than 0.930 g/cm3.
Graft copolymers can be prepared by reacting the base materials with peroxides or subjecting them to high mechanical loads, producing free radicals in this way and bringing them into contact with suitable monomers. According to 8ritish Patent 679,562, the free radicals can be produced by means of high speed stirrers, shaking, milling, kneading, ultrasonic vibra-tions or passage through filters or capillary tubes at high linear velocities. This results in degradation of the polymer and the formation of reactive radicals at which the graft reaction can take place. When the graft reaction is carried out in a Diskpack screwless extruder using polyethylene as a base polymer and maleic anhydride as the monomer to be grafted ~cf. Protassow et al., Plaste und Kautschuk 23 (3) (1976), 185-187], crosslinking reactions are observed.
According to the same publication, the lack of initiators results in no reaction at all taking place if a conventional extruder is to be used for the re-action.
However, grafting can also be carried out in conventional extruders if suitable initiators, such as organic peroxides, are added to the reaction mixture and the reaction is carried out in a special reaction zone, for example that described in U.S. Patents 3,862,265, 3,953,655 and 4,001,172. In this process too, however, polymer degradation takes place and, in the case of poly-ethylene as the base polymer, there is furthermore a ~ 33~8?6 - 2 - O.Z. 0050/38790 danger of crosslinking.
In order to prevent degradation of the polymer, special process engineering measures are necessary, as described in U.S. Patents 3,177,269, 3,177,270 and 3,270,090.
If maleic anhydride is used as the unsaturated compound to be grafted, in a concentration of 0.051-1.26% by weight, based on the base polymer polyethylene, according to U.S. Patent 4,147,740 virtually complete conversion of the maleic anhydride takes place. Complete conversion of the maleic anhydride is particularly advan-tageous, owing to the high toxicity of free unbound maleic anhydride.
According to U.S. Patent 4,147,740, an important precondition for the complete incorporation of maleic anhydride is the use of peroxides; in particular, the lower the maleic anhydride concentration, the greater must be the ratio of peroxide concentration to the maleic anhydride concentration. At a maleic anhydride concen-tration of 1.26% by weight, based on the base polym`er,a peroxide concentration which is about one tenth of the maleic anhydride concentration is still sufficient; at low maleic anhydride concentrations, the use of a peroxide concentration corresponding to the maleic anhydride con-centration is still insufficient for achieving completeconversion of the maleic anhydride. This is achieved only with a five-fold peroxide excess.
The use of such high peroxide concentrations leads to undesirable crosslinking, which reduces the flow and processability of the graft polymers. The undesir-able degradation and crosslinking reactions due to the use of peroxide can frequently be suppressed only by special process engineering measures, as described in, for example, U.S. Patents 3,177,269, 3,177,270 and 3,270,090. These restrict the flexibility of the pro-cess.
Furthermore, the use of peroxide has an adverse :` 1 333826 .
- 3 - O.Z. 0050~3~790 effect on the color and odor of the polymers. In ad-dition, the adhesion to polar substances, for example metals, decreases. Finally, the use of peroxides is in principle unacceptable from a safety point of view.
According to the prior art, however, the use of peroxides is absolutely essential for obtaining any graft reaction at all. Precisely at low maleic anhydride con-centrations, which are within a range of industrial in-terest, relatively high peroxide concentrations are required in order to achieve complete conversion of the maleic anhydride. However, complete maleic anhydride conversions are desirable for economic reasons and even more so for reasons relating to occupational hygiene, owing to the high toxicity of maleic anhydride.
If, on the other hand, free r-adicals are pro-duced by a purely thermal method, ie. without the use of peroxide, degradation reactions take place which reduce the viscosity of the base polymers. These degraded poly-mers exhibit poor adhesion to metals, even when the poly-mers are grafted with maleic anhydride, using the ther-mally produced free radicals.
If the free radicals required for the graft re-action are produced mechanochemically, for example in a Diskpack screwless extruder, the base polymer is like-wise considerably degraded; in addition, crosslinkingreactions may also occur in the presence of maleic an-hydr;de.
It is an object of the present invention to pro-vide a process for the peroxide-free grafting of unsatura-ted carboxylic acids, anhydrides and their derivatives,in which no degradation and no crosslinking of the ethy-lene polymer takes place. At the same time, the conver-sion of the monomers should be as complete as possible.
~ ..
'A~
- 3a -1 3338~6 In accordance with the invention, this object is achieved by a process for grafting ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their derivatives to a homopolymer or copolymer of ethylene having a density equal to or greater than 0.930 g/cm in a conventional extruder or mixer under from 1 to 500 bar in the absence of a free radical catalyst, wherein the monomer to be grafted is mixed, in a concentration of from 0.01 to 0.25~ by weight, based on the ethylene polymer, with the ethylene polymer which has been melted at 140C or higher, and the grafting reaction is carried out completely or as completely as possible at from 210 to 300C.
Particularly suitable ethylenically unsaturated carboxylic acids, carbo //
IB
Graft copolymers can be prepared by reacting the base materials with peroxides or subjecting them to high mechanical loads, producing free radicals in this way and bringing them into contact with suitable monomers. According to 8ritish Patent 679,562, the free radicals can be produced by means of high speed stirrers, shaking, milling, kneading, ultrasonic vibra-tions or passage through filters or capillary tubes at high linear velocities. This results in degradation of the polymer and the formation of reactive radicals at which the graft reaction can take place. When the graft reaction is carried out in a Diskpack screwless extruder using polyethylene as a base polymer and maleic anhydride as the monomer to be grafted ~cf. Protassow et al., Plaste und Kautschuk 23 (3) (1976), 185-187], crosslinking reactions are observed.
According to the same publication, the lack of initiators results in no reaction at all taking place if a conventional extruder is to be used for the re-action.
However, grafting can also be carried out in conventional extruders if suitable initiators, such as organic peroxides, are added to the reaction mixture and the reaction is carried out in a special reaction zone, for example that described in U.S. Patents 3,862,265, 3,953,655 and 4,001,172. In this process too, however, polymer degradation takes place and, in the case of poly-ethylene as the base polymer, there is furthermore a ~ 33~8?6 - 2 - O.Z. 0050/38790 danger of crosslinking.
In order to prevent degradation of the polymer, special process engineering measures are necessary, as described in U.S. Patents 3,177,269, 3,177,270 and 3,270,090.
If maleic anhydride is used as the unsaturated compound to be grafted, in a concentration of 0.051-1.26% by weight, based on the base polymer polyethylene, according to U.S. Patent 4,147,740 virtually complete conversion of the maleic anhydride takes place. Complete conversion of the maleic anhydride is particularly advan-tageous, owing to the high toxicity of free unbound maleic anhydride.
According to U.S. Patent 4,147,740, an important precondition for the complete incorporation of maleic anhydride is the use of peroxides; in particular, the lower the maleic anhydride concentration, the greater must be the ratio of peroxide concentration to the maleic anhydride concentration. At a maleic anhydride concen-tration of 1.26% by weight, based on the base polym`er,a peroxide concentration which is about one tenth of the maleic anhydride concentration is still sufficient; at low maleic anhydride concentrations, the use of a peroxide concentration corresponding to the maleic anhydride con-centration is still insufficient for achieving completeconversion of the maleic anhydride. This is achieved only with a five-fold peroxide excess.
The use of such high peroxide concentrations leads to undesirable crosslinking, which reduces the flow and processability of the graft polymers. The undesir-able degradation and crosslinking reactions due to the use of peroxide can frequently be suppressed only by special process engineering measures, as described in, for example, U.S. Patents 3,177,269, 3,177,270 and 3,270,090. These restrict the flexibility of the pro-cess.
Furthermore, the use of peroxide has an adverse :` 1 333826 .
- 3 - O.Z. 0050~3~790 effect on the color and odor of the polymers. In ad-dition, the adhesion to polar substances, for example metals, decreases. Finally, the use of peroxides is in principle unacceptable from a safety point of view.
According to the prior art, however, the use of peroxides is absolutely essential for obtaining any graft reaction at all. Precisely at low maleic anhydride con-centrations, which are within a range of industrial in-terest, relatively high peroxide concentrations are required in order to achieve complete conversion of the maleic anhydride. However, complete maleic anhydride conversions are desirable for economic reasons and even more so for reasons relating to occupational hygiene, owing to the high toxicity of maleic anhydride.
If, on the other hand, free r-adicals are pro-duced by a purely thermal method, ie. without the use of peroxide, degradation reactions take place which reduce the viscosity of the base polymers. These degraded poly-mers exhibit poor adhesion to metals, even when the poly-mers are grafted with maleic anhydride, using the ther-mally produced free radicals.
If the free radicals required for the graft re-action are produced mechanochemically, for example in a Diskpack screwless extruder, the base polymer is like-wise considerably degraded; in addition, crosslinkingreactions may also occur in the presence of maleic an-hydr;de.
It is an object of the present invention to pro-vide a process for the peroxide-free grafting of unsatura-ted carboxylic acids, anhydrides and their derivatives,in which no degradation and no crosslinking of the ethy-lene polymer takes place. At the same time, the conver-sion of the monomers should be as complete as possible.
~ ..
'A~
- 3a -1 3338~6 In accordance with the invention, this object is achieved by a process for grafting ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their derivatives to a homopolymer or copolymer of ethylene having a density equal to or greater than 0.930 g/cm in a conventional extruder or mixer under from 1 to 500 bar in the absence of a free radical catalyst, wherein the monomer to be grafted is mixed, in a concentration of from 0.01 to 0.25~ by weight, based on the ethylene polymer, with the ethylene polymer which has been melted at 140C or higher, and the grafting reaction is carried out completely or as completely as possible at from 210 to 300C.
Particularly suitable ethylenically unsaturated carboxylic acids, carbo //
IB
- 4 - O.Z. OOS0/38790 derivatives are the conventional compounds such as maleic acid, fumaric acid, itaconic acid, acrylic acid, acrylic anhydride, methacrylic acid, crotonic acid, maleic an-hydride and itaconic anhydride. Preferred compounds are maleic acid, fumaric acid and in particular maleic an-hydride.
For the purposes of the present invention, homo-polymers and copolymers of ethylene having densities equal to or greater than 0.930 g/cm3 are, in p~rticular, high density polyethylene (HDPE), high density ethylene/vinyl acetate copolymers, high density ethylene/acrylate co-polymers and medium density polyethylene (MDPE). The den-sities were determined according to DIN 53,479; they are preferably from 0.930 to 0.966, in particular from 0.935 to 0.965, g/cm3.
In the novel process, the monomers to be grafted are used in concentrations of from 0.01 to 0.25% by weight, based on the ethylene polymer, and mixed with the ethy-lene polymer which has been melted at 140C or higher, and the graft reaction is carried out at from 210 to 300C, for example in a conventional extruder under from 1 to 500 bar, in the absence of a free radical initiator.
Grafting is preferably carried out at a concen-tration of from 0.05 to 0.20 % by weight. The temperature is preferably from 210 to 280C, in particular from 210 to 260C.
In another preferred process, the monomer to be grafted is admixed in the liquid state.
Peroxide-free grafting of the unsaturated carboxy-lic acids, anhydrides and their derivatives was carried out in a conventional twin-screw extruder, for example ZDSK 53 from Werner & Pfleiderer. However, other reac-tors known from the prior art, for example a Brabender reactor, may also be used. The ethylene polymer and, if required, also the monomer to be grafted were melted at 140C or higher, mixed thoroughly and then reacted at elevated temperatures, ie. from 210 to 300C, preferably ~r.
* trade names : - 1 333826 ~ 5 - 0.~. 0050/38790 from Z10 to Z~0C, particularly preferably from Z10 to Z60C. ln this procedure, it is unimportant whether the monomer to be grafted is introduced into the reactor before or after the ethylene polymer is melted. The mono-mers to be grafted were used in a concentration of from 0.01 to 0.25, preferably from 0.05 to 0.20, ~ by weight, based on the ethylene polymer. It was found that the yields of grafted monomer were higher the lower the con-centrations of the monomers to be grafted. This finding is surprising since, according to U.S. Patent 4,147,740, it is supposed to be more difficult to achieve high grafting yields the lower the concentration of monomers to be grafted. This shows that the reaction which forms the basis of this invention is completely different from 1S graft reactions carried out using peroxide. In a pre-ferred procedure, the monomer to be grafted is mixed with the ethylene polymer in the liquid state. For this purpose, it may be melted beforehand.
The novel process on the one hand ensures a high Z0 conversion of the monomer to be grafted and on the other hand leads to neither significant crosslinking nor degra-dation of the base polymer.
The graft copolymers prepared according to the invention are suitable for the production of hollow ar-ticles, coating and coextrusion, powder coating, etc.0ecause of their low residual monomer content, they are also useful for the food sector.
The products have good adhesion to nylon, poly-vinyl alcohol, polystyrene, polycarbonate, polyolefins, epoxy resins and metals, eg aluminum and iron.
The adhesion of these graft copolymers prepared without the use of peroxide is higher than that of pro-ducts grafted with the use of peroxide. In the case of the products prepared according to the invention, the flow is scarcely reduced in comparison with the base poly-mer. In contrast to the graft copolymers prepared with the use of peroxide, the products prepared w1thout the i ~ .
? ~33826 - 6 - O.Z. 0050/38790 use of peroxide can readily be processed. The films ob-tained from these products have a substantially lower speck content than films obtained from graft products prepared with the use of peroxide. The products obtained from the peroxide-free graft reaction are furthermore completely colorless and odorless.
The use of similar graft copolymers which con-sist of ethylene polymers and grafted unsaturated car-boxylic acids or carboxylic anhydrides for the prepara-tion of adhesion promoters and adhesives is known perse and described in, for example, British Patent 2,081,723 and U.S. Patent 4,487,885. Furthermore, the use of simi-lar graft copolymers for the preparation of ionomers is so well known from the literature that further descrip-tion at this point is superfluous (cf. for example U.S.Patents 3,264,272 or 3,437,718). In the preparation of the ionomers, the free carboxyl groups of the graft co-polymer obtained according to the invention are reacted with inorganic bases or salts to give the corresponding salts. Alkali metal compounds and salts of the alkali metals, of the alkaline earth metals or of zinc with or-ganic acids are particularly suitable.
100 parts by weight of MDPE (copolymer of 97.5%
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, determined in all experiments according to ASTM-D-1238-65T at 190C and under a load of 2.16 kg; density = 0.9358 gtcm3, determined in all experiments according to DIN 53,479) were melted at 140C
in a ZDSK 53 twin-screw extruder from Werner ~ Pfleiderer.
0.25 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 260C. Unconverted maleic anhydride was removed from the polymer melt by devolatili-zation under reduced pressure.
The mean residence time of the grafting componentsin the extruder was 2 minutes, and the polymer throughput 1 3338~6 ~ 7 - O.Z. OO5Q/38790 was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.5 g/10 min) had improved adhesion to polar substances, such as epoxy resins or metaLs, and was furthermore completely color-less and odorless.
100 parts by weight of MDPE (copolymer of 97.5%
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, density = 0.9358 g/cm3) were melted at 140C in a ZDSK 53 twin-screw extruder from Werner & Pfleiderer. 0.15 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 220C. Uncon-verted maleic anhydride was removed from the polymer melt by devolatilization under reduced pressure.
The mean residence time of the grafting components in the extruder was 2 minutes, and the polymer throughput was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.9 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metals, and was furthermore completely color-less and odorless.
100 parts by weight of MDPE (copolymer of 97.5%
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, density = 0.9358 g/cm3) were melted at 140C in a ZDSK 53 twin-screw extruder from Werner & Pfleiderer. 0.10 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 220C. Uncon-verted maleic anhydride was removed from the polymer melt by devolatilization under reduced pressure.
The mean residence time of the grafting components in the extruder was 2 minutes, and the polymer throughput was 10 kg/h at 150 rpm.
I .~338~6 - 8 - 0.Z. 0050l38790 The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.8 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metaLs, and was furthermore completely color-less and odorless.
100 parts by weight of MDPE (copolymer of 97.5~
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, density = 0.9358 g/cm3) were melted at 140C in a ZDSK 53 twin-screw extruder from Werner & Pfleiderer. 0.05 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 2Z0C. Uncon-verted maleic anhydride was removed from the polymer melt by devolatilization under reduced pressure.
The mean residence time of the grafting components in the extruder was 2 minutes, and the polymer throughput was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.8 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metals, and was furthermore completely color-less and odorless.
MDPE was grafted with maleic anhydride under the same conditions as in Example 1, except that the maleic anhydride was mixed with 0.025 part by weight of dicumyl peroxide. The resulting products were pressed to give 2.7 mm thick iron/adhesion promoter/MDPE laminated sheets, and the peeling strength was determined by a test based on DIN 30,670. Table 1 shows that the product grafted without peroxide (Example 5) has very much higher ad-hesion than the product grafted with the use of peroxide (Comparative Experiment).
! 333~26 ~ 9 ~ O.Z. 0050/38790 Dicumyl Yield of Product Adhesion Color Odor peroxide grafted melt flow laminated [% by maleic index sheet wt.] anhyd- 2.16 N/2 cm ride Cg/ strip C% by 10 min] width wt.]
Com- 0.025 97 1.1 70 Yellow Strongly of para- decomposi-tive tio~ pro-Experi- ducts of the ment peroxide Exam- - 99 3.5 150 Color- None ple 5 less The product obtained in the Comparative Experi-ment is difficult to process (great reduction in the melt flow index), is yellow and smells strongly of the decom-position products of the peroxide. Films produced from this product have a high speck content. Products ob-tained according to Example 5 do not have these disadvan-tages.
The MDPE was grafted with maleic anhydride un-der the same conditions as in Example 1, except that 0.4, 0.75 or 1.25 parts by weight of maleic anhydride were used for grafting. Table 2 shows that t e grafting yields become poorer with increasing maleic anhydride concentration.
- 10 - O.Z. 0050/38790 Maleic anhydride Product Yield of concentration used melt flow grafted [% by weight] index maleic 2.16 anhydride [9/10 min] ~%]
Comparative Experiment A 0.4 3.6 80 10 Comparative Experiment B 0.75 3.5 50 Comparative Experiment C 1.25 3.7 27 Example 6 0.25 3.5 99 However, poor yields of grafted maleic anhydride are undesirable for economic reasons as well as reasons relat-ing to occupational hygiene.
For the purposes of the present invention, homo-polymers and copolymers of ethylene having densities equal to or greater than 0.930 g/cm3 are, in p~rticular, high density polyethylene (HDPE), high density ethylene/vinyl acetate copolymers, high density ethylene/acrylate co-polymers and medium density polyethylene (MDPE). The den-sities were determined according to DIN 53,479; they are preferably from 0.930 to 0.966, in particular from 0.935 to 0.965, g/cm3.
In the novel process, the monomers to be grafted are used in concentrations of from 0.01 to 0.25% by weight, based on the ethylene polymer, and mixed with the ethy-lene polymer which has been melted at 140C or higher, and the graft reaction is carried out at from 210 to 300C, for example in a conventional extruder under from 1 to 500 bar, in the absence of a free radical initiator.
Grafting is preferably carried out at a concen-tration of from 0.05 to 0.20 % by weight. The temperature is preferably from 210 to 280C, in particular from 210 to 260C.
In another preferred process, the monomer to be grafted is admixed in the liquid state.
Peroxide-free grafting of the unsaturated carboxy-lic acids, anhydrides and their derivatives was carried out in a conventional twin-screw extruder, for example ZDSK 53 from Werner & Pfleiderer. However, other reac-tors known from the prior art, for example a Brabender reactor, may also be used. The ethylene polymer and, if required, also the monomer to be grafted were melted at 140C or higher, mixed thoroughly and then reacted at elevated temperatures, ie. from 210 to 300C, preferably ~r.
* trade names : - 1 333826 ~ 5 - 0.~. 0050/38790 from Z10 to Z~0C, particularly preferably from Z10 to Z60C. ln this procedure, it is unimportant whether the monomer to be grafted is introduced into the reactor before or after the ethylene polymer is melted. The mono-mers to be grafted were used in a concentration of from 0.01 to 0.25, preferably from 0.05 to 0.20, ~ by weight, based on the ethylene polymer. It was found that the yields of grafted monomer were higher the lower the con-centrations of the monomers to be grafted. This finding is surprising since, according to U.S. Patent 4,147,740, it is supposed to be more difficult to achieve high grafting yields the lower the concentration of monomers to be grafted. This shows that the reaction which forms the basis of this invention is completely different from 1S graft reactions carried out using peroxide. In a pre-ferred procedure, the monomer to be grafted is mixed with the ethylene polymer in the liquid state. For this purpose, it may be melted beforehand.
The novel process on the one hand ensures a high Z0 conversion of the monomer to be grafted and on the other hand leads to neither significant crosslinking nor degra-dation of the base polymer.
The graft copolymers prepared according to the invention are suitable for the production of hollow ar-ticles, coating and coextrusion, powder coating, etc.0ecause of their low residual monomer content, they are also useful for the food sector.
The products have good adhesion to nylon, poly-vinyl alcohol, polystyrene, polycarbonate, polyolefins, epoxy resins and metals, eg aluminum and iron.
The adhesion of these graft copolymers prepared without the use of peroxide is higher than that of pro-ducts grafted with the use of peroxide. In the case of the products prepared according to the invention, the flow is scarcely reduced in comparison with the base poly-mer. In contrast to the graft copolymers prepared with the use of peroxide, the products prepared w1thout the i ~ .
? ~33826 - 6 - O.Z. 0050/38790 use of peroxide can readily be processed. The films ob-tained from these products have a substantially lower speck content than films obtained from graft products prepared with the use of peroxide. The products obtained from the peroxide-free graft reaction are furthermore completely colorless and odorless.
The use of similar graft copolymers which con-sist of ethylene polymers and grafted unsaturated car-boxylic acids or carboxylic anhydrides for the prepara-tion of adhesion promoters and adhesives is known perse and described in, for example, British Patent 2,081,723 and U.S. Patent 4,487,885. Furthermore, the use of simi-lar graft copolymers for the preparation of ionomers is so well known from the literature that further descrip-tion at this point is superfluous (cf. for example U.S.Patents 3,264,272 or 3,437,718). In the preparation of the ionomers, the free carboxyl groups of the graft co-polymer obtained according to the invention are reacted with inorganic bases or salts to give the corresponding salts. Alkali metal compounds and salts of the alkali metals, of the alkaline earth metals or of zinc with or-ganic acids are particularly suitable.
100 parts by weight of MDPE (copolymer of 97.5%
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, determined in all experiments according to ASTM-D-1238-65T at 190C and under a load of 2.16 kg; density = 0.9358 gtcm3, determined in all experiments according to DIN 53,479) were melted at 140C
in a ZDSK 53 twin-screw extruder from Werner ~ Pfleiderer.
0.25 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 260C. Unconverted maleic anhydride was removed from the polymer melt by devolatili-zation under reduced pressure.
The mean residence time of the grafting componentsin the extruder was 2 minutes, and the polymer throughput 1 3338~6 ~ 7 - O.Z. OO5Q/38790 was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.5 g/10 min) had improved adhesion to polar substances, such as epoxy resins or metaLs, and was furthermore completely color-less and odorless.
100 parts by weight of MDPE (copolymer of 97.5%
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, density = 0.9358 g/cm3) were melted at 140C in a ZDSK 53 twin-screw extruder from Werner & Pfleiderer. 0.15 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 220C. Uncon-verted maleic anhydride was removed from the polymer melt by devolatilization under reduced pressure.
The mean residence time of the grafting components in the extruder was 2 minutes, and the polymer throughput was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.9 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metals, and was furthermore completely color-less and odorless.
100 parts by weight of MDPE (copolymer of 97.5%
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, density = 0.9358 g/cm3) were melted at 140C in a ZDSK 53 twin-screw extruder from Werner & Pfleiderer. 0.10 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 220C. Uncon-verted maleic anhydride was removed from the polymer melt by devolatilization under reduced pressure.
The mean residence time of the grafting components in the extruder was 2 minutes, and the polymer throughput was 10 kg/h at 150 rpm.
I .~338~6 - 8 - 0.Z. 0050l38790 The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.8 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metaLs, and was furthermore completely color-less and odorless.
100 parts by weight of MDPE (copolymer of 97.5~
by weight of ethylene and 2.5% by weight of butene; melt flow index = 4.3 9/10 min, density = 0.9358 g/cm3) were melted at 140C in a ZDSK 53 twin-screw extruder from Werner & Pfleiderer. 0.05 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the base polymer, and the reaction was carried out at 2Z0C. Uncon-verted maleic anhydride was removed from the polymer melt by devolatilization under reduced pressure.
The mean residence time of the grafting components in the extruder was 2 minutes, and the polymer throughput was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride was 99%.
The grafted polymer (melt flow index = 3.8 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metals, and was furthermore completely color-less and odorless.
MDPE was grafted with maleic anhydride under the same conditions as in Example 1, except that the maleic anhydride was mixed with 0.025 part by weight of dicumyl peroxide. The resulting products were pressed to give 2.7 mm thick iron/adhesion promoter/MDPE laminated sheets, and the peeling strength was determined by a test based on DIN 30,670. Table 1 shows that the product grafted without peroxide (Example 5) has very much higher ad-hesion than the product grafted with the use of peroxide (Comparative Experiment).
! 333~26 ~ 9 ~ O.Z. 0050/38790 Dicumyl Yield of Product Adhesion Color Odor peroxide grafted melt flow laminated [% by maleic index sheet wt.] anhyd- 2.16 N/2 cm ride Cg/ strip C% by 10 min] width wt.]
Com- 0.025 97 1.1 70 Yellow Strongly of para- decomposi-tive tio~ pro-Experi- ducts of the ment peroxide Exam- - 99 3.5 150 Color- None ple 5 less The product obtained in the Comparative Experi-ment is difficult to process (great reduction in the melt flow index), is yellow and smells strongly of the decom-position products of the peroxide. Films produced from this product have a high speck content. Products ob-tained according to Example 5 do not have these disadvan-tages.
The MDPE was grafted with maleic anhydride un-der the same conditions as in Example 1, except that 0.4, 0.75 or 1.25 parts by weight of maleic anhydride were used for grafting. Table 2 shows that t e grafting yields become poorer with increasing maleic anhydride concentration.
- 10 - O.Z. 0050/38790 Maleic anhydride Product Yield of concentration used melt flow grafted [% by weight] index maleic 2.16 anhydride [9/10 min] ~%]
Comparative Experiment A 0.4 3.6 80 10 Comparative Experiment B 0.75 3.5 50 Comparative Experiment C 1.25 3.7 27 Example 6 0.25 3.5 99 However, poor yields of grafted maleic anhydride are undesirable for economic reasons as well as reasons relat-ing to occupational hygiene.
Claims (4)
1. A process for grafting ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their derivatives to a homopolymer or copolymer of ethylene having a density equal to or greater than 0.930 g/cm in a conventional extruder or mixer under from 1 to 500 bar in the absence of a free radical catalyst, wherein the monomer to be grafted is mixed, in a concentration of from 0.01 to 0.25% by weight, based on the ethylene polymer, with the ethylene polymer which as been melted at 140°C or higher, and the grafting reaction is carried out completely or as completely as possible at from 210 to 300°C.
2. A process as claimed in claim 1, wherein the graft monomer is admixed in the liquid state.
3. A process as claimed in claim 1, wherein the concentration of the graft monomer is from 0.05 to 0.20% by weight.
4. A process as claimed in claim 1, 2 or 3, wherein the graft monomer is maleic anhydride.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19863639564 DE3639564A1 (en) | 1986-11-20 | 1986-11-20 | PEROXIDE-FREE GRAFTING FROM HOMO OR COPOLYMERISATES OF ETHYLENE WITH DENSITY EQUAL TO OR LARGER THAN 0.930 G / CM (ARROW HIGH) 3 (ARROW HIGH) AND USE OF THE GRAFT COPOLYMERS FOR PRODUCTION IN IONOMERS OR ADHESIVES |
| DEP3639564.1 | 1986-11-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1333826C true CA1333826C (en) | 1995-01-03 |
Family
ID=6314309
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000551584A Expired - Fee Related CA1333826C (en) | 1986-11-20 | 1987-11-06 | Peroxide-free grafting of homopolymers and copolymers of ethylene having densities equal to or greater than 0.930 g/cm_, and use of the graft copolymers for the preparation of ionomers or adhesion promoters |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0268294B1 (en) |
| AT (1) | ATE92503T1 (en) |
| CA (1) | CA1333826C (en) |
| DE (2) | DE3639564A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3800307A1 (en) * | 1988-01-08 | 1989-07-20 | Basf Ag | METHOD FOR GRAFTING POLYOLEFIN MIXTURES AND USE OF THE GRAFT POOPOLYM BLEND AS ADHESIVE AND FOR PRODUCING INOMERS |
| EP0467178B1 (en) * | 1990-07-16 | 1996-10-09 | BASF Aktiengesellschaft | Grafted and crosslinked propylene copolymer |
| CA2103379C (en) * | 1992-11-19 | 2000-05-23 | Toshiyuki Tsutsui | Catalyst for olefin polymerization, process for olefin polymerization using the same, ethylene/.alpha.-olefin copolymer, graft modified ethylene/.alpha.-olefin copolymer, and ethylene copolymer composition |
| US6001941A (en) | 1992-11-19 | 1999-12-14 | Mitsui Chemicals, Inc. | Ethylene α-olefin copolymer obtained by copolymerizing ethylene with an α-olefin |
| DE4308591A1 (en) * | 1993-03-18 | 1994-09-22 | Basf Ag | Grafted propylene copolymers |
| WO1995004091A1 (en) * | 1993-07-29 | 1995-02-09 | Kawasaki Steel Corporation | Process for producing graft polyolefin |
| FI20085896A0 (en) | 2008-09-23 | 2008-09-23 | Upm Kymmene Wood Oy | Coating for wooden boards and wooden board |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1322448A (en) * | 1961-04-12 | 1963-03-29 | Union Carbide Corp | Continuous production of modified polyolefins |
| FR1393730A (en) * | 1961-08-31 | 1965-03-26 | Du Pont | New ionic hydrocarbon polymers |
| US4087588A (en) * | 1975-09-22 | 1978-05-02 | Chemplex Company | Adhesive blends |
| US4026967A (en) * | 1976-06-25 | 1977-05-31 | E. I. Du Pont De Nemours And Company | Process for making grafted polymeric material |
| JPS5929410B2 (en) * | 1976-12-29 | 1984-07-20 | 三菱油化株式会社 | Method for manufacturing laminated composite sheet with excellent gas barrier properties |
| CA1216908A (en) * | 1983-08-08 | 1987-01-20 | Mitsuzo Shida | Electrical cable construction |
-
1986
- 1986-11-20 DE DE19863639564 patent/DE3639564A1/en not_active Withdrawn
-
1987
- 1987-11-06 CA CA000551584A patent/CA1333826C/en not_active Expired - Fee Related
- 1987-11-19 AT AT87117074T patent/ATE92503T1/en not_active IP Right Cessation
- 1987-11-19 EP EP87117074A patent/EP0268294B1/en not_active Expired - Lifetime
- 1987-11-19 DE DE8787117074T patent/DE3786884D1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ATE92503T1 (en) | 1993-08-15 |
| EP0268294B1 (en) | 1993-08-04 |
| DE3639564A1 (en) | 1988-06-01 |
| EP0268294A3 (en) | 1990-03-14 |
| DE3786884D1 (en) | 1993-09-09 |
| EP0268294A2 (en) | 1988-05-25 |
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