CA1333825C - Peroxide-free grafting of homo-polymers and copolymers of ethylene having densities less 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 homo-polymers and copolymers of ethylene having densities less than 0.930 g/cm_, and use of the graft copolymers for the preparation of ionomers or adhesion promotersInfo
- Publication number
- CA1333825C CA1333825C CA000551399A CA551399A CA1333825C CA 1333825 C CA1333825 C CA 1333825C CA 000551399 A CA000551399 A CA 000551399A CA 551399 A CA551399 A CA 551399A CA 1333825 C CA1333825 C CA 1333825C
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- Prior art keywords
- ethylene
- peroxide
- grafted
- maleic anhydride
- polymer
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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)
- Laminated Bodies (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 less 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 copoly-mers are used for the preparation of ionomers and adhe-sion promoters.
Description
`` 1 33S825 - 1 - O.Z. OOS0/38791 Peroxide-free grafting of homopolymers and copolymers of ethylene having densities less 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 less 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 ~ay and - bringing them into contact with suitable monomers.
According to Pritish Patent 679,562, the free radicals can be produced by means of high speed stirrers, shaking, milling, kneading, ultrasonic vibrations or passage through filters or capillary tubes at high linear vel-ocities. This results in degradation of the polymer the formation of reactive radicals, at which the graft reac-tion can take place. ~hen the graft reaction is carriedout in a Diskback screwless extruder using polyethylene as a base polymer and maleic anhydride as the monomer to be grafted Ccf. 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 ~' 1 33382~
Graft copolymers can be prepared by reacting the base materials with peroxides or subjecting them to high mechanical loads, producing free radicals in this ~ay and - bringing them into contact with suitable monomers.
According to Pritish Patent 679,562, the free radicals can be produced by means of high speed stirrers, shaking, milling, kneading, ultrasonic vibrations or passage through filters or capillary tubes at high linear vel-ocities. This results in degradation of the polymer the formation of reactive radicals, at which the graft reac-tion can take place. ~hen the graft reaction is carriedout in a Diskback screwless extruder using polyethylene as a base polymer and maleic anhydride as the monomer to be grafted Ccf. 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 ~' 1 33382~
- 2 - O.Z. 0050/38791 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 ~ 5 3,Z70,090.
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 the 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 lo~er the maleic anhydride concentration, the greater must be the ratio of peroxide concentration to the maleic anhydride concentration. At a maleic anhydride concen-Z0 tration of 1.26X by weight, based on the base polymer,a peroxide concentration ~hich 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, vhich 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 ., ~ . .. . . . . . .... .. . . . .... . . . . . . . . .
t 333825 - 3 - O.Z. 0050/38791 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 lo~ 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 the maleic anhydride.
If, on the other hand, free radicals 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 po~ymers. 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 screvless extruder, the base polymer is like-wise considerably degraded; in addition, crosslinkingreactions may also occur in the presence of maleic an-hydride.
It iSthe object of the present invention to pro-vide a process for the peroxide-free grafting of unsatura-ted carboxyl;c 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 is as complete as possible.
~' - 3a - I 333825 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 less than 0.930 g/cm3 in a conventional extruder or mixer under from l 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 c~letely or as completely as possible at from 210 to 300 C
Particularly suitable ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their /
/
'n ~ 4 ~ O.Z. 0050/38791 derivat;ves 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 hav;ng densities less than 0.930 g/cm3 are, in particular, low density poly-ethylene (LDPE), low density ethylene/vinyl acetate co-polymers, lo~ density ethylene/acrylate copolymers and linear lo~ density polyethylene (LLDPE). The densities were determined according to DIN 53,479; they are prefer-ably from 0.930 to û.966, in particular from 0.914 to 0.928, g/cm3.
In the novel process, the monomers to be grafted are used in concentrations of from 0.01 to 0.2s%by ~eight, based on the ethylene polymer, and mixed with the ethy-lene polymer ~hich 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 wei~ht. The tempera-ture 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 acid, anhydri,des and their derivatives was carried out in a conventional twin-screu extruder, for example ~DSK 53 from ~erner ~ Pf~eiderer. Ho~ever, other reac-tors known from the prior art, for example a Orabender*
reactor, may also be used. The ethylene polymer and, if required, also the monomer to be grafted ~ere melted at 140C or higher, mixed thoroughly and then reacted at elevated temperatures, ie. from 210 to 300C, preferably r L~
* trade,names 1 ~33~5 ~ 5 ~ O.Z. OOS0/38791 from 210 to 280C, particularly preferably from 210 to 260C. In 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 O.OS to û.20, Z 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 ~,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 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 2û 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.~ecause 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 without the - 6 - O.Z 0050/38791 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 ~hich 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 SPatents 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 ~ith organic 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 ~ith or-ganic acids are particularly suitable.
100 parts by ~eight of LLDPE (copolymer of 93%
by ~eight of ethylene and 7% by weight of butene; melt flo~ index = 4.5 9/10 min, determined in all experiments according to ASTM-D-1238-65T at 190C and under a load of 2.16 kg; density = 0.920 g/cm3, determined in all experiments according to DIN 53,479) ~ere melted at 140C
in a ZDSK 53 t~in-scre~ extruder from ~erner ~ Pfleiderer.
0.25 part by weight of liquid aleic anhydride ~as pumped into the melt and mixed ~ith the base polymer, and the reaction ~as carried out at 260C. Unconverted maleic anhydride ~as removed from the polymer melt by devolatili-zation under reduced pressure.
The mean residence time of the grafting componentsin the extruder ~as 2 minutes, and the polymer throughput . .
~ 333825 ~ 7 ~ O.Z. 0050/38791 was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride ~as 96%.
The grafted polymer (melt flow index = 4.0 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 ~eight of V 2910 k (ethylene/vinyl acetate copolymer from BASF; melt flow index = 4.3 9/10 min, density = 0.928 g/cm3) were melted at 140C in a ZDSK 53 t~in-screw extruder from ~erner & Pfleiderer.
0.25 part by weight of liquid maleic anhydride was pumped into the melt and mixed ~ith the base polymer, and the reaction was carried out at 220C. Unconverted maleic anhydride was removed from the polymer melt by devolatil-ization 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 ~as 92%.
The grafted polymer (melt flow index = 3.0 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 V 2910 k (ethylene/vinyl acetate copolymer from UASF; melt flov index = 4.3 9/10 min, density = 0.928 g/cm3, were melted at 140C in a ZDSK 53 twin-screw extruder from ~erner & Pfleiderer. 0.25 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the ethylene polymer, and the reac-tion was carried out at 260C. Unconverted maleic anhy-dride was removed from the polymer melt by devolatiliza-tion 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.
... . .
~ ~33825 - 8 - 0.Z. 0050/38791 The yield of grafted maleic anhydride was 98%.
The grafted polymer (melt flow index = 3.0 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 LLDPE (copolymer of 93%
by weight of ethylene and 7Z by weight of butene; melt flow index = 4.5 9/10 min, density = 0.920 g/cm3, were melted at 140C in a ZDSK 53 twin-screw extruder from ~erner ~ 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 240C.
Unconverted 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 98%.
The grafted polymer (melt fLo~ index = 4.0 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metals, and was furthermore completely color-less and odorless.
Polyethylene ~as grafted ~ith 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/epoxy resin adhesion promoter/
polyethylene laminated sheets, and the peeling strength ~as determined by a test based on DIN 30,670. Table 1 - sho~s that the product grafted ~ithout peroxide (Example 5) has very much higher adhesion than the product grafted ~ith the use of peroxide (Comparative Experiment).
~ 9 ~ O.Z. 0050/38791 Dicumyl Yield of Product Adhesion Color Odor peroxide grafted melt flow laminated [% by maleic index sheet wt.] anhyd- 2 16 N/2 cm ride ~9/ strip - [% by 10 min] width wt.]
-10 Com- 0.025 95 1 6 60 Yellow Strongly of para- decomposi-tive tion pro-Experi- ducts of the ment peroxide 15 Exam- - 96 4.0 170 Color- None ple 5 less The product obtained in the Comparative Experi-ment ;s difficult to process (great reduction in the meLt flow ;ndex), 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 polyethylene was grafted with maleic anhydride under the same conditions as in Example 2, except that 0.4, 0.75 or 1.25 parts by weight of maleic anhydride were used for grafting. Table 2 shows that the grafting yields become poorer with increasing maleic anhydride concentration.
- 10 - O.Z. 0050/38791 MaLeic anhydride Product Yield of concentration used melt flo~ grafted [% by weight] index maleic 2.16 anhydride Cg/10 min] C%]
Comparative Experiment A 0.4 2.5 65 10 Comparative Experiment El 0.75 2.8 50 Comparative Experiment C 1.25 3.0 32 Example 6 0.25 3.0 92 However, poor yields of maleic anhydride are un-desirable for economic reasons as well as reasons relat-ing to occupational hygiene.
The polyethylene was grafted with maleic anhydride under the same conditions as in Example 6, except that the reaction was carried out at 280C. Table 2 shows that the grafting yields become poorer with increasing maleic anhydride concentration.
Maleic anhydride Product Yield of concentration used melt flow grafted C~ by weight] index maleic 2.16 anhydride tg/10 min] t%]
Comparative Experiment A 0.4 1.9 78 Comparative Experiment B 0.75 2.0 60 - Comparative Experiment C 1.25 2.1 50 Example 6 0.25 2.0 99 1~ 33`382~
- 11 - O.Z. 0050/38791 Ho~ever, poor yields of maleic anhydride are un-desirable for economic reasons as ~ell as reasons relat-ing to occupational hygiene.
-
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 ~ 5 3,Z70,090.
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 the 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 lo~er the maleic anhydride concentration, the greater must be the ratio of peroxide concentration to the maleic anhydride concentration. At a maleic anhydride concen-Z0 tration of 1.26X by weight, based on the base polymer,a peroxide concentration ~hich 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, vhich 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 ., ~ . .. . . . . . .... .. . . . .... . . . . . . . . .
t 333825 - 3 - O.Z. 0050/38791 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 lo~ 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 the maleic anhydride.
If, on the other hand, free radicals 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 po~ymers. 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 screvless extruder, the base polymer is like-wise considerably degraded; in addition, crosslinkingreactions may also occur in the presence of maleic an-hydride.
It iSthe object of the present invention to pro-vide a process for the peroxide-free grafting of unsatura-ted carboxyl;c 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 is as complete as possible.
~' - 3a - I 333825 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 less than 0.930 g/cm3 in a conventional extruder or mixer under from l 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 c~letely or as completely as possible at from 210 to 300 C
Particularly suitable ethylenically unsaturated carboxylic acids, carboxylic anhydrides and/or their /
/
'n ~ 4 ~ O.Z. 0050/38791 derivat;ves 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 hav;ng densities less than 0.930 g/cm3 are, in particular, low density poly-ethylene (LDPE), low density ethylene/vinyl acetate co-polymers, lo~ density ethylene/acrylate copolymers and linear lo~ density polyethylene (LLDPE). The densities were determined according to DIN 53,479; they are prefer-ably from 0.930 to û.966, in particular from 0.914 to 0.928, g/cm3.
In the novel process, the monomers to be grafted are used in concentrations of from 0.01 to 0.2s%by ~eight, based on the ethylene polymer, and mixed with the ethy-lene polymer ~hich 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 wei~ht. The tempera-ture 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 acid, anhydri,des and their derivatives was carried out in a conventional twin-screu extruder, for example ~DSK 53 from ~erner ~ Pf~eiderer. Ho~ever, other reac-tors known from the prior art, for example a Orabender*
reactor, may also be used. The ethylene polymer and, if required, also the monomer to be grafted ~ere melted at 140C or higher, mixed thoroughly and then reacted at elevated temperatures, ie. from 210 to 300C, preferably r L~
* trade,names 1 ~33~5 ~ 5 ~ O.Z. OOS0/38791 from 210 to 280C, particularly preferably from 210 to 260C. In 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 O.OS to û.20, Z 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 ~,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 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 2û 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.~ecause 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 without the - 6 - O.Z 0050/38791 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 ~hich 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 SPatents 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 ~ith organic 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 ~ith or-ganic acids are particularly suitable.
100 parts by ~eight of LLDPE (copolymer of 93%
by ~eight of ethylene and 7% by weight of butene; melt flo~ index = 4.5 9/10 min, determined in all experiments according to ASTM-D-1238-65T at 190C and under a load of 2.16 kg; density = 0.920 g/cm3, determined in all experiments according to DIN 53,479) ~ere melted at 140C
in a ZDSK 53 t~in-scre~ extruder from ~erner ~ Pfleiderer.
0.25 part by weight of liquid aleic anhydride ~as pumped into the melt and mixed ~ith the base polymer, and the reaction ~as carried out at 260C. Unconverted maleic anhydride ~as removed from the polymer melt by devolatili-zation under reduced pressure.
The mean residence time of the grafting componentsin the extruder ~as 2 minutes, and the polymer throughput . .
~ 333825 ~ 7 ~ O.Z. 0050/38791 was 10 kg/h at 150 rpm.
The yield of grafted maleic anhydride ~as 96%.
The grafted polymer (melt flow index = 4.0 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 ~eight of V 2910 k (ethylene/vinyl acetate copolymer from BASF; melt flow index = 4.3 9/10 min, density = 0.928 g/cm3) were melted at 140C in a ZDSK 53 t~in-screw extruder from ~erner & Pfleiderer.
0.25 part by weight of liquid maleic anhydride was pumped into the melt and mixed ~ith the base polymer, and the reaction was carried out at 220C. Unconverted maleic anhydride was removed from the polymer melt by devolatil-ization 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 ~as 92%.
The grafted polymer (melt flow index = 3.0 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 V 2910 k (ethylene/vinyl acetate copolymer from UASF; melt flov index = 4.3 9/10 min, density = 0.928 g/cm3, were melted at 140C in a ZDSK 53 twin-screw extruder from ~erner & Pfleiderer. 0.25 part by weight of liquid maleic anhydride was pumped into the melt and mixed with the ethylene polymer, and the reac-tion was carried out at 260C. Unconverted maleic anhy-dride was removed from the polymer melt by devolatiliza-tion 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.
... . .
~ ~33825 - 8 - 0.Z. 0050/38791 The yield of grafted maleic anhydride was 98%.
The grafted polymer (melt flow index = 3.0 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 LLDPE (copolymer of 93%
by weight of ethylene and 7Z by weight of butene; melt flow index = 4.5 9/10 min, density = 0.920 g/cm3, were melted at 140C in a ZDSK 53 twin-screw extruder from ~erner ~ 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 240C.
Unconverted 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 98%.
The grafted polymer (melt fLo~ index = 4.0 9/10 min) had improved adhesion to polar substances, such as epoxy resins or metals, and was furthermore completely color-less and odorless.
Polyethylene ~as grafted ~ith 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/epoxy resin adhesion promoter/
polyethylene laminated sheets, and the peeling strength ~as determined by a test based on DIN 30,670. Table 1 - sho~s that the product grafted ~ithout peroxide (Example 5) has very much higher adhesion than the product grafted ~ith the use of peroxide (Comparative Experiment).
~ 9 ~ O.Z. 0050/38791 Dicumyl Yield of Product Adhesion Color Odor peroxide grafted melt flow laminated [% by maleic index sheet wt.] anhyd- 2 16 N/2 cm ride ~9/ strip - [% by 10 min] width wt.]
-10 Com- 0.025 95 1 6 60 Yellow Strongly of para- decomposi-tive tion pro-Experi- ducts of the ment peroxide 15 Exam- - 96 4.0 170 Color- None ple 5 less The product obtained in the Comparative Experi-ment ;s difficult to process (great reduction in the meLt flow ;ndex), 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 polyethylene was grafted with maleic anhydride under the same conditions as in Example 2, except that 0.4, 0.75 or 1.25 parts by weight of maleic anhydride were used for grafting. Table 2 shows that the grafting yields become poorer with increasing maleic anhydride concentration.
- 10 - O.Z. 0050/38791 MaLeic anhydride Product Yield of concentration used melt flo~ grafted [% by weight] index maleic 2.16 anhydride Cg/10 min] C%]
Comparative Experiment A 0.4 2.5 65 10 Comparative Experiment El 0.75 2.8 50 Comparative Experiment C 1.25 3.0 32 Example 6 0.25 3.0 92 However, poor yields of maleic anhydride are un-desirable for economic reasons as well as reasons relat-ing to occupational hygiene.
The polyethylene was grafted with maleic anhydride under the same conditions as in Example 6, except that the reaction was carried out at 280C. Table 2 shows that the grafting yields become poorer with increasing maleic anhydride concentration.
Maleic anhydride Product Yield of concentration used melt flow grafted C~ by weight] index maleic 2.16 anhydride tg/10 min] t%]
Comparative Experiment A 0.4 1.9 78 Comparative Experiment B 0.75 2.0 60 - Comparative Experiment C 1.25 2.1 50 Example 6 0.25 2.0 99 1~ 33`382~
- 11 - O.Z. 0050/38791 Ho~ever, poor yields of maleic anhydride are un-desirable for economic reasons as ~ell 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 less than 0.930 g/cm3 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 ethy-lene polymer which has been melted at 140°C or higher, and the grafting reaction completely or as completely as possible is carried out at from 210 to 300°C.
by weight, based on the ethylene polymer, with the ethy-lene polymer which has been melted at 140°C or higher, and the grafting reaction completely or as completely as possible is carried out 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.
by weight.
4. A process as claimed 1, 2 or 3, wherein the graft monomer is maleic anhydride.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19863639566 DE3639566A1 (en) | 1986-11-20 | 1986-11-20 | PEROXIDE-FREE GRAFTING FROM HOMO OR COPOLYMERISATES OF ETHYLENE WITH DENSITY LESS THAN 0.930 G / CM (ARROW HIGH) 3 (ARROW HIGH) AND USE OF THE GRAFT COPOLYMERS FOR THE PRODUCTION OF IONOMERS OR ADHESIVERS |
| DEP3639566.8 | 1986-11-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1333825C true CA1333825C (en) | 1995-01-03 |
Family
ID=6314311
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000551399A Expired - Fee Related CA1333825C (en) | 1986-11-20 | 1987-11-09 | Peroxide-free grafting of homo-polymers and copolymers of ethylene having densities less 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) | EP0269000B1 (en) |
| AT (1) | ATE92504T1 (en) |
| CA (1) | CA1333825C (en) |
| DE (2) | DE3639566A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4308591A1 (en) * | 1993-03-18 | 1994-09-22 | Basf Ag | Grafted propylene copolymers |
| GB9507321D0 (en) * | 1995-04-07 | 1995-05-31 | Exxon Chemical Patents Inc | Method to reduce gel in polyolefins |
Family Cites Families (4)
| 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 |
| 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 DE19863639566 patent/DE3639566A1/en not_active Withdrawn
-
1987
- 1987-11-09 CA CA000551399A patent/CA1333825C/en not_active Expired - Fee Related
- 1987-11-19 AT AT87117082T patent/ATE92504T1/en not_active IP Right Cessation
- 1987-11-19 DE DE8787117082T patent/DE3786886D1/en not_active Expired - Lifetime
- 1987-11-19 EP EP87117082A patent/EP0269000B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0269000A2 (en) | 1988-06-01 |
| EP0269000A3 (en) | 1990-03-21 |
| DE3786886D1 (en) | 1993-09-09 |
| DE3639566A1 (en) | 1988-06-01 |
| EP0269000B1 (en) | 1993-08-04 |
| ATE92504T1 (en) | 1993-08-15 |
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