DE2418705A1 - OIL-RESISTANT AND AGING-RESISTANT ELASTOMERS - Google Patents

Description

EGG. DU PONT DE NEMOURS AND COMPANY 10th and Market Streets, Wilmington, Delaware I9898, V. St. A.

oil-resistant and aging-resistant elastomers

The present invention relates to a method for accelerating the vulcanization of peroxide-cured ethylene / acrylic acid ester polymers or ethylene / vinyl acetate polymers by adding butadiene / acrylonitrile polymers to the polymers mentioned, as well as the resulting polymer blends. Such vulcanizates have good aging resistance and oil resistance,

Oil-resistant and aging-resistant elastomers are important in such areas of application as the sheathing of automotive ignition cables. These cables get pretty much that exposed to high temperatures of motor vehicle engines and also frequently come into contact with engine oils. To others Areas of application for oil-resistant and aging-resistant elastomers include, for example, hoses and seals and engine suspension frames.

409847/0764

Lewis-ΙΑ

Ethylene / alkyl acrylate polymers or ethylene / vinyl acetate polymers can be used in such fields of application, but they can but often only with difficulty vulcanize to a sufficiently high degree, to reach acceptable limits of oil and heat resistance.

There is a need for aging resistant and oil resistant Elastomers that are suitable for these and similar fields of application.

According to the present invention it has now been found that the Addition of butadiene / acrylonitrile polymers to certain ethylene / acrylic acid ester polymers or ethylene / vinyl acetate polymers accelerate the peroxide curing of the latter. It will thus curable mixtures

(1) a butadiene / acrylonitrile polymer containing about 25 to 50 percent by weight acrylonitrile, and

(2) an ethylene / acrylic acid ester polymer or ethylene / vinyl acetate polymer provided, wherein the proportion of (1) is about 1 to 30 parts by weight per 100 parts by weight of (2) .

The ethylene-containing polymer should be at least 3 »6 moles of ethylene each contain 1000 g of the ethylene-containing polymer, and it can

(a) an ethylene / alkyl acrylate or ethylene / alkyl methacrylate copolymer, wherein the alkyl group contains 1 to 4 carbon atoms and the proportion of the acrylic ester about 2.5 to 8.0 Mol of ester groups per kg of the copolymer,

(b) a terpolymer of ethylene with an alkyl acrylate or methacrylate, the alkyl group having 1 to A carbon atoms contains, and a third copolymerizable monomer, which can be, for example, one of the following monomers:

409847/0764

Lewis-IA

(I) a C 1-6 alkyl monoester or diester of a

Butenedioic acid,
(II) acrylic acid,
(III) methacrylic acid, (IV) carbon monoxide,

(V) acrylonitrile,
(VI) a vinyl ester,
(VII) an alkyl acrylate or alkyl methacrylate, the alkyl group having at least 5 carbon atoms, and

(VIII) maleic anhydride; or

(c) ethylene / vinyl acetate copolymers containing at least 35 wt. JS Contain vinyl acetate.

In the above described terpolymers the proportion of the Acrylsäureesters is equivalent to about 2.5 to 8.0 mol Estergruppen per kg of the polymer, and the proportion of the third monomer is not higher than about 10 wt -.% Of the polymer.

These blends are made in the presence of a peroxide curing system vulcanized, and the mixtures usually also contain an antioxidant system.

The butadiene / acrylonitrile polymers, which form one of the constituents of the mixtures according to the invention, are known substances. They can be prepared, for example, by the copolymerization of butadiene with acrylonitrile initiated by free radicals, either in solution or in emulsion by methods belonging to the prior art. These substances should be of such molecular weights that they show Mooney viscosities (ML-M, 100.0 ⁰ C) from about 20 to 120th It is not intended to limit suitable butadiene / acrylonitrile polymers to dipolymers; Namely, terpolymers such as carboxylated butadiene / acrylonitrile polymers can also be used. They are produced by means of mixed polymer

409847/0764

Lewis-IA

sizing of butadiene, acrylonitrile and a polymerizable Carboxylic acid, for example acrylic acid or methacrylic acid. For all practical purposes, suitable butadiene / Acrylonitrile polyesters are commercially available.

Although the proportion of acrylonitrile in the polymers is up to 50% by weight. - is%, an amount ratio of 25 to 41 weight is -.% Preferred because such polymers result in an optimum vulcanization acceleration.

The preferred proportion of the butadiene / acrylonitrile polymer in the compositions according to the invention is 5 to 15 parts each 100 parts of the second component, the ethylene / acrylic acid ester polymer.

That. Ethylene-containing polymers can be a simple mixed polymer of ethylene with methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, a butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, a butyl methacrylate or vinyl acetate Methods are made. These copolymers should have a melt index within the range from 0.1 to 70 at 190 ⁰ C and preferably of 0.5 to 15 as measured by ASTM method no. D-1238-52T, or ASTM method D-1238 virtually equivalent -70.

The terpolymer of ethylene with an acrylic acid ester and a third monomer can be used as a third monomer Contain esters of fumaric acid or maleic acid, in which the alcohol content is, for example, methyl, ethyl, propyl, Isopropyl, various isomers of butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl and like. can be. The third monomer can also be, inter alia, a vinyl ester, for example vinyl acetate or vinyl butyrate. It can also be an acrylic acid ester, for example

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Lewis-IA

wise different isomeric forms of pentyl, hexyl, heptyl, Octyl, nonyl, decyl, undecyl, dodecyl, pentadecyl and Octadecyl acrylates and methacrylates. Is not appropriate it is to use as the third monomer an acrylic acid ester in which the alcohol content is more than 18 carbon atoms contains.

The ethylene-containing polymers, which represent the second component of the compositions according to the invention, contain at least 3 »6 mol of ethylene per 1000 g of the polymer and 2.5 to 8 mol of acrylic ester groups - depending on which ester is used per kg of the polymer or in the case of ethylene / vinyl acetate polymers 35 to 80 wt -.% vinyl acetate. In the vulcanized state, such polymers have the optimal combination of flexibility at low temperatures and oil resistance.

The compositions according to the invention are vulcanized in the presence of peroxide curing systems which consist of a peroxide and optionally a coagent. Suitable peroxides are those that decompose rapidly within the range of 150 to 250 ⁰ C. These include, for example, dicumyl peroxide, 2,5-bis- (t-butylperoxy) -2,5-dimethylhexane and w, ei-bis- (t-butylperoxy) diisopropylbenzene. In a typical vulcanizing mass, there are about 0.5 to 5 parts by weight of peroxide per 100 parts of polymer mixture. The peroxide can be adsorbed on an inert carrier such as calcium carbonate, carbon black or kieselguhr; however, the weight of the wearer is not included in the above range.

The coagent can be, for example, N, N ^t - (m-phenylene) -dimaleic acid amide, trimethylolpropane trimethyl acrylate, tetraallyloxyethane, triallyl cyanurate, tetramethylene acrylate or polyethylene oxide glycol dimethacrylate. The amount of coagent is about 0 to 5 parts by weight per 100 parts of the polymer mixture, about 1 to 3 parts per 100 being preferred.

_ cj _

409847/0764

Lewis-IA

The coagents usually contain polyunsaturates Groups such as allyl or acrylic acid esters. Although its mode of action is not known with certainty, it can be assumed that they react with the radical initially formed on the polymer backbone to form a more stable radical, the Coupling reactions with the formation of cross-links enters into more easily than chain cleavage reactions.

The inventive vulcanizates can also have a Antioxidant system based on a phosphoric ester antioxidant, a hindered phenolic antioxidant, one Contain amine antioxidant or a mixture of two or more of these compounds. The phosphoric ester compound can, for example be:

Tri- (mixed mono- and -dinonylphenyl) phosphite, tris- (3 »5 ~ Di-t-butyl-lj-hydroxyphenyl) phosphate, high molecular weight poly (phenolic phosphonate) and

6- (3,5 ~ Di-1-butyl-iJ-hydroxy) -benzyl-6H-dibenz / c ^ je7 / T, 27oxyphosphorine-6-oxide.

The hindered phenolic compounds can be, for example, the following:

^, Jl-Butyliden-bis-Cö-t-butyl-m-cresol),

1,3,5-trimethyl-2,4,6-tris- (3 »5-di-t-buty1-4-hydroxybenzyl) -

benzene,

2,6-di-t-butyl-edimethylamino-p-cresol and 4,4'-thio-bis (3-methyl-6-t-butylphenol.

Suitable amine antioxidants include but are not limited to the following: polymerized 2,2,4-trimethyl-1,2-dehydroquinoline; N-phenyl-N '- (p-toluenesulfonyl) -p-phenylenediamine; N, N ^r -di (ßnaphthyl) -p-phenylenediamine, the product of the reaction at low

- 6 409847/0764

Lewis-ΙΑ

riger temperature of phenyl- (ß-naphthyl) -amine with acetone; and ^l \, 4 '-bis (o £, O £ -Dimethy lbenzy 1) diphenylamine.

The proportion of the antioxidant compound in the vulcanizing The mass is about 0.1 to 5 parts per 100 parts of polymer, the preferred proportion being 0.5 to 2.5.

The antioxidant is required for masses that should be resistant to heat aging. The effect of the antioxidant is usually below the preferred range very low and below the broad range given above too low for practical purposes. Little additional improvement is observed above the higher limits, and even unfavorable effects can occur in the hardening state. The weight ratio of the phenolic or alaine antioxidant to the phosphorus compound in the mixtures is about 0.5 to 3; the preferred ratio is about 1.

The preferred antioxidant compositions contain tri- (mixed mono- and dinonylphenyl) phosphite in a mixture with either · ^ jA'-bis-CGijOt-dimethyl-benzyD-diphenylamine or 4,4'-butylidene-bis- (6-t-butyl-m-cresol).

It is often desirable to add fillers to reduce costs and improve mechanical properties. A typical vulcanized mass usually contains about 15 to 40 % by volume of fillers, for example carbon black, barium sulfate, magnesium silicate or silica. Other conventional fillers can also be used. The preferred proportion of the fillers is 20 to 25 % by volume and also depends on the reinforcing effect of the individual fillers. Below the lower limit, the improvement in the tensile strength properties is very slight, while above the upper limit the heat aging resistance of the polymer is adversely affected.

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Lewis-IA

As used here, the word "filler" means whether it is used in the singular or plural, a filler or a mixture of fillers in one Dimensions.

The constituents of the vulcanizing compound are thoroughly mixed, for example on a rubber mill or in a Banbury mixer. The resulting rubber mixture can be according to any convenient one. Method, for example in a press, in a Y / asserdampfrohr, a fluidized bed or a molten metal, molded or extruded and cured 0.2 to 50 minutes at 150 to 230 ⁰ C. The preferred curing conditions are from 0.5 to 5 minutes at 180-205 ⁰ C.

The vulcanizates obtained from the inventive polymer mixtures have good compression set properties ( "compression set resistance"), good flexibility at low temperature (for example at -30 ⁰ C), good heat resistance at high temperatures (for example at 150 to 220 ⁰ C) and good oil resistance on.

The present invention will now be illustrated by way of certain representative embodiments by way of the following examples of the invention. In the examples, all parts, proportions and percentages are, if not otherwise stated, based on weight.

Table I shows the composition of the examples

1 to Ik described rubber materials in parts for each component. The rubber materials of Examples 1,

2 and ¹ I through Ik were mixed on an I ₃ SZ cm χ 20.3 cm (3 by 8 inch) rubber mill at room temperature for 10 minutes. First, the ethylene / acrylic acid ester polymer, butadiene / acrylonitrile polymer and fillers were mixed together, and the

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Antioxidants and hardeners were added towards the end of the mixing cycle. The resulting materials were press cured at 180 ° C for 30 minutes under a pressure of 45 »0 kg / cm (640 psi) into 1.905 mm (75 mil) plaques; the molds were hot both when filled and when emptied. Test specimens were cut from these plates. The volume in ASTM no. 3-Ö1 at ^{1150 0} C for 3 days was determined according to ASTM method D-471. The tensile strength (T _n

in kg / cm) and the elongation (E _ß in %) were determined according to ASTM method D-412. The melt indices of the ethylene / acrylic ester starting copolymers were determined according to ASTM method D-1238-52T.

The rubber material of Example 3 was produced by mixing the constituents in a dwarf Banbury mixer at 50 to 60 ^° C. for 10 minutes. Test specimens were then produced and tested as described above.

Table II shows the results of the tests carried out on the vulcanized compositions of Examples 1-14.

409847/0764

Table I.

Example 1 '2 3 4 5 6 7 § 9 10 11 12 13 14

Ethylene / acrylic acid-x
■ ester polymer ^a '100 100 100 100 100 100 100 - - -

Ethylene / acrylic acid. ν

ester polymer - - - - - - - 100 100 -

Ethylene / acrylic acid \

ester polymer ^; - - - - - - - - - 100 100 100

Ethylene / acrylic acid jv
J ^. ester polymer '___.-__.___, -, _ - ioO 100

? j? Butadiene / acryloni-

O ₀ ι trile mixed polymer χ

j>M> res ^{e </} ~ 10 IQ - 10 - 10 - 10 - 10 -

^ Butadiene / acryloni-

_o tril-mixed polymer- «>

j ^ butadiene / acrylni- *

tril-Terpolymeres ° -

FEF carbon black 10 10 10 50 50 10 10 50 55 50 55 55

MT-Russ

BaSO ₁ ,

anhydrous

10 10 10 50 50 10 10 50 55 50 - - - - • 40 40 - - - 110 110 61 - - - - - - - - - 18.3 - - - - - - - 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

- 10 10 10 61 61 18th , 3 18.3 1 1 1 1

Tris nonylphenyl

phosphite ■ 11111111111111 ^

4,4'-butylidene-bis-

(6-t-butyl-m-cresol) _________

1,3,5-trimethyl- · «-J

2,4,6-tris- (3,5-di-, ---. ----- lii-- q>

t-butyl-4-hydroxy-. · On

benzyD-benzene '■

Table I (port setting) ■

Example Jl 2 3 4 5 6 7 8 9_ 10 11 12 13 14 K '

Dicumyl peroxide --_., .-,.-_----- ,. G

(40 % on CaCO ₃ ) 5 5 5 5 5 · S ^ 5t> ^ t? 55! 3>

N, N '- (m-phenylene) - 2222222222 2 2 2 2 dimaleinimide

³ ^ a) ethylene / 51 % methyl acrylate / 3.9 % ethyl hydrogen maleate; Melt index 0.95 ο

cd · b) ethylene / 50 % methyl acrylate; Melt index 0.6

c) ethylene / 53 % ethyl acrylate / 2.3 % ethyl hydrogen maleate; Melt index 0.48

^ d) ethylene / 55 % methyl acrylate / 3.5 % ethyl hydrogen maleate; Melt index 1.2

° e) butadiene / 4l % acrylonitrile, powder form; Mooney Viscosity 115

cd f) butadiene / 41 % acrylonitrile, rubber form; Mooney viscosity 80

g) butadiene / 26.5 % acrylonitrile / acrylic acid, rubber form; Mooney viscosity 42 to 58.

Tabel

II

example

Properties of the vulcanizate

^T B

^E B

% Volume

swelling

After aging, 14 days / 177 ° C

% T ", hold- ^a

% Ε «, hold- ^D

1 2 3 4th 5 6th 7th 8th 9 10 11 12th 13th 14th 79.5 92.1 98.4 135.7 154.7 108.6 109.2 144.1 148.1 130 129.2 111.8 93.2 83.0 610 530 565 390 340 415 420 315 260 410 290 300 630 540 98 87 81 89 77 92 84 127 102 183 120 126 91 85 15th 80 107 39 58 31 67 35 48 42 60 67 43 102 2 30th 30th 15th 24 24 24 25th 38 24 36 43 9 22nd

tr

(D 3! ΗΝ I

ro

CX) O

Lewis-IA

The values given above show that the vulcanizates containing butadiene / acrylonitrile mixed polymer have a higher value Achieved hardening state, which was reflected in a lower oil swelling. This can be seen when you have two Vulcanizates of the same polymer with the same filler type and the same filler loading with and without the butadiene / Comparing acrylonitrile copolymers, for example Example 2 with 1, 5 with 4, 7 with 6, 9 with 8, 11 or 12 with 10 and 14 with 13. These results were obtained whether the Ethylene / acrylic acid ester polymers were a terpolymer or a mixed polymer, and whether the filler was the big one Part of it was the non-reinforcing BaSOh, the highly reinforcing FEF soot or the less well reinforcing MT soot.

The samples containing butadiene / acrylonitrile polymer also show markedly increased retention of tensile strength after heat aging compared to the samples made from ethylene / acrylic acid ester polymer alone. Strips for tensile testing were aged in air ovens at 177 ° C. Comparing the same sets of examples as above, it can be seen that the percent retention of T _R is higher for the butadiene / acrylonitrile interpolymer blends. The difference is more noticeable in the softer materials, those containing less reinforcing fillers such as BaSOj, (Example 2 or 3 versus 1) or MT black (Example 7 versus 6), or those containing ethyl rather than methyl acrylate such as the comonomer (Example 11 or 12 versus 10) with FEF carbon black. The elongation at break (Eg) retention was usually increased when the butadiene / acrylonitrile polymer was added and again was more noticeable in the softer materials.

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4Q9847 / 076A

Lewis-ΙΑ

Example 15

This example shows the effect of the butadiene / acrylonitrile level on the properties of the original and heat-aged vulcanizate.

The rubber materials were mixed on a 7 »62 χ 20.3 cm rubber mill at room temperature for 10 minutes. First, the ethylene / alkyl acrylate copolymer, nitrile rubber, and fillers were mixed together, and the antioxidants and curing agents were added towards the end of the mixing cycle. The resulting materials were for 30 minutes and under a pressure of 45 *, O kg / cm press-cured at l80 ⁰ C to 1.905 mm plates; the molds were hot both when filled and when discharged. Test specimens were cut from the plates. The volume swelling in ASTM No. 3 ~ oil at 150 ° C. for 3 days was determined according to ASTM method D-17I. The tensile strength (T _ß in kg / cm ² ) and elongation (E _ß in %) were determined according to ASTM method D-412.

The composition of the rubber materials and the test values are given in Table III below. For comparison values for the above-mentioned ethylene / alkyl acrylate polymer are included in the table.

409847/0764

Table III

• tr » Composition · ABCD ^! %

a.) ^H *

Xthylene / acrylate polymer

Nitrile polymer 'FEF carbon black

Tris-Nonylphenyl-phosphite 4,4 ⁱ -Butyliden-bis- (6-f-butyl-m-cresol) * "" Dicumyl peroxide (40 % CaCO,)

to N, N ^! -m-phenylenedimaleimide

4> - ι Properties of the original VuI- '

-j ^ kanisats

"">. VJI

% Volume swell

After 14 days of aging at 177 ° C % Tg, retained SS Ε, -, - retained

100 100 100 100 - 5 10 15th 10 10 10 10 OK 110 110 110 1 1 1 1 1 1 1 1 VJl 5 5 5 2 2 2 2 79.5 85.1 92.1 88.6 610 545 530 ' 460 98 90 87 85 15th 74 80 87 2 24 30th 26th

a) ethylene / 51 wt -.% methyl acrylate / 3.9% Äthylhydrogenmaleat, melt index 0.95 κ> (ASTM D-1238-52T) ί-

b) butadiene / 41 wt .- # acrylonitrile, powder form; Mooney Viscosity 115.

Lewis-IA

Example 16

This example shows that butadiene / acrylonitrile rubber among unsaturated elastomers in terms of the degree of improvement in properties of both original and also heat-aged vulcanizate made from ethylene / acrylic acid ester polymers Remarkably.

Table IV below lists the composition and vulcanizate properties of various rubber materials from ethylene / acrylic acid ester polymers that use a different polymer instead of butadiene / acrylonitrile polymer included, shown. Comparing the physical properties of these rubber materials with those described in Table II for ethylene / acrylic acid ester polymers containing butadiene / acrylonitrile polymers are given, it is evident that the latter show a more pronounced improvement. This applies in particular to the elongation values after! ^ active aging at 177 C, an important quantity for elastomers. The values were as in example 15 described, received.

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409847/0764

Table IV

Composition ABCDE φ

Ethylene / acrylate polymer ^a; ■

100 100 100 100 100 10 10 10 10 10 61 61 61 61 61 18.3 18.3 18.3 18.3 ■ 18.3 1 1 1 1 1 1 1 1 1 1 5 5 5 5 5 2 2 2 2 2 10 «,

FEF Russ

BaSO ^

anhydrous

Tris nonylphenyl phosphite

4,4'-butylidene-bis- (6-t-butyl-m-cresol)

• ρ- dicumyl peroxide (40 % on CaCO,)

ο ■?

cd Ν, Ν'-m-phenylenedimaleimide

^ · Natural rubber

^ J ^ styrene / butadiene polymer ^b ^ 10

ο ι 1,2-polybutadiene ⁰ ^ 10

cd cis-1,4-polybutadiene 10

■ ^ polychloroprene '10

Properties of the original vulcanizate

^T B

^E B

% Volume swell

After 14 days of aging at 177 ⁰ C % T _ß , retained % E ^, retained

86.4 80.4 97.6 79.4 86.4 585 605 265 490 510 104 88 73 92 89 74 79 76 80 60 7th 12th 8th 11

a) ethylene / 55% by weight methyl acrylate / 3.5 % ethyl hydrogen maleate; Melt index 1.2 (ASTM cd D-1238-52T) cn

b) SBR 1500

c) Sold as Hystl 2000 by Hystl Development Co., Redondo 3each, California

d) sold as Neoprene W by E.I. du Pont de Nemours and Company, Inc.

Lewis-ΙΑ

Example 17

This example proves that the butadiene / acrylonitrile polymer increases the curing rate and stabilizes vulcanizates made from ethylene / vinyl acetate polymers during heat aging. The preparation of samples and testing the samples were carried out as in Examples 1 to I ¹ I described.

Tabel V B. C. D. Composition (in parts by weight) A. 100 Polymer l ^a 100 100 100 Polymer 2 5 5 Nitrile polymer ⁰ 1 1 1 Tris nonylphenyl phosphite 1 1 1 1 4,4'-bis (vV, <£ -dimethylbenzyl) -
diphenylamine 1 50 50 50 SRF Russ 50 1 , 5 1.5 1.5 Polyethylene glycol 1.5 5 5 5 Dicumyl peroxide (40 % on CaCO,) 5 2 2 2 m-phenylenedimaleimide 2 Vibrating disc rheorneter 0, 1611 0.0691 0.1037 Curing speed (mkg / min .;
"in. Ib./min.") 0.0979
(8.5)

30 min rotation (mkg / min .;

"in. Ib./min.") 0.415 0.576 0.22 * 15 0.311

Properties of the original vulcanizate

T _B (kg / cm ² ) 142.3 140.7 65.0 72.0

E _B (%) 310 320 170 160

% Volume swell 201 174 116 101

After 14 days of aging at 177 ° C

% T _n , retained 69 74 70 98

% E _B , retained 66 69 12 38-

4098 £ 7% 764

Lewis-ΙΑ

a) ethylene / ^ O wt -.% vinyl acetate-type copolymer having a melt index of about 57 g / 10 minutes.

b) ethylene / vinyl acetate 62 parts by weight J5 interpolymer having a melt index of O at 190 ⁰ C and Tg -29 ⁰ C.

. c) ButadienMl wt -% acrylonitrile mixing polymer powder form; Mooney Viscosity 115.

d) As "Carbowax" ^ iOOO on the market.

e) Pressure cured for 15 minutes at 177 ° C

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409847/0764

Claims (16)

Patent claims (2) a butadiene / acrylonitrile polymer that is about 25 to 50 weight percent; Contains acrylonitrile, the proportion of the butadiene / acrylonitrile polymers mentioned 1 to 30 parts by weight per 100 parts by weight of the ethylene-containing polymer mentioned and the ethylene-containing polymer is at least 3.6 mol Contains ethylene per 1000 g of the ethylene-containing polymer and is selected from the following group: (a) a ethylene / alkyl acrylate or ethylene / alkyl methacrylate copolymer, in which the alkyl group has 1 to Μ carbon atoms, the proportion of the acrylic acid ester is about 2.5 to 8 moles of ester groups per kg of the copolymer; (b) a terpolymer of ethylene with an alkyl acrylate or methacrylate in which the alkyl group has 1 to ¹ J carbon atoms, and a third monomer, namely (I) a CL-CLp alkyl monoester or diester of a Butenedioic acid, (II) acrylic acid,
(III) methacrylic acid, (IY) carbon monoxide, (V) acrylonitrile,
(VI) a vinyl ester, (VII) an alkyl acrylate or methacrylate in which the alkyl group has at least 5 carbon atoms, and
(VIII) maleic anhydride, the proportion of the acrylic acid ester being equivalent to 2.5 to 8.0 mol of ester groups per kg of the polymer and the - 20 409847/0764 The proportion of the third monomer not higher than about 10 wt. of the polymer is; and (c) ethylene / vinyl acetate copolymers containing at least 35 % by weight Contain vinyl acetate. 2. Mixture according to claim 1, characterized in that the amount of acrylonitrile in the butadiene / acrylonitrile polymer 25 to 41 wt -% by.. 3 · Mixture according to claim 1, characterized in that the The proportion of the butadiene / acrylonitrile polymer is 5 to 15 parts per 100 parts of the ethylene-containing polymer. ^. Mixture according to claim 1, characterized in that the Ethylene-containing polymers contains acrylic acid esters and the acrylic acid ester content of the ethylene polymer is equivalent to 5 to 8 moles of ester groups per kg of polymer. 5. Mixture according to claim 1, characterized in that the Ethylene polymers an ethylene / acrylic acid ester / butanedioic acid ester terpolymer is. 6. Mixture according to claim 1, characterized in that the ethylene-containing polymer is an ethylene / vinyl acetate copolymer is. 7. A composition containing a mixture according to claim 1, an antioxidant system and a peroxide curing system, the proportion of the antioxidant system being about 0.1 to 5 parts by weight per 100 parts by weight of the polymer. 8. Composition according to claim 7, characterized in that the peroxide curing system consists of a peroxide, which ^{decomposes rapidly within the temperature range from 150 to 250 0} C, and a coagent, namely N, N '- (m ~ phenylene) - dimeric acid amide, trimethylolpropane trimethyl 4Ö9 "Ö 2 ^ 70764 Lewis-IA acrylate, tetraallyloxyethane, triallyl cyanurate, tetramethylene acrylate or polyethylene oxide glycol dimethacrylate. 9. Composition according to claim 7 »characterized in that the antioxidant system is a mixture of a phosphorus compound with a hindered phenolic antioxidant or an amine antioxidant contains, wherein the weight ratio of the phenolic compound or the amine to the phosphorus compound is about 0.5 to 3. 10. Composition according to claim 9 » characterized in that both the phenolic compound or the amine and the phosphorus compound are present in approximately equal amounts by weight. 11. Composition according to claim 7, characterized in that it additionally contains 15 to kO Vol.-ί of a filler. 12. Composition according to claim 11, characterized in that the proportion of the filler is 20 to 25 vol.-Ϊ. 13 · Vulcanized product, obtained by heating a mass according to claim 11 for 0.2 to 50.0 minutes at 150 to 230 ^° C. Ik. Vulcanized product according to claim 13 »characterized in that it contains barium sulfate as a filler. 15. Vulcanized product according to claim 13, characterized in that that it contains silica and barium sulfate as fillers. 16. Vulcanized product according to claim 13, characterized in that that the antioxidant system consists essentially of tri- (mixed. -mono- and -dinonylphenyD-phosphite in a mixture with 4,4'-bis - (<v, Od-dimethylbenzyl) -diphenylamine or 4,4'-butylidene-bis- (ß-t-butyl-m-cresol) consists. 409847/0764 - 22 -