NL7906469A - CURABLE MIXTURES OF CHLOROPRENE POLYMER AND ETHENE COPOLYMER. - Google Patents

Description

- 1 - * * + N.O. 28,071 E.I. du Pont de Nemours and Company, in WILMINGTON, Delaware, USA St. America

Curable mixtures of chloroprene polymer and ethylene conolymer.

The present invention relates to curable blends and more particularly to improved curable blends of chloroprene polymer and ethylene copolymer.

Elastomers are often mixed with softening agents and plasticizers to extend their utility for various end uses. Many of these emollients are liquids that can volatilize upon exposure of the compound to elevated temperatures or that can be extracted when the compound is contacted with solvents or oils. More permanent polymeric liquid plasticizers are relatively expensive.

Research Report No. 13816 of October 1975 describes that the oil resistance of chlorosulfonated polyethylene was found to be significantly improved for blends in which a terpolymer (30 to 4-5 wt% terpolymer based on the elastomer) of ethylene / carbon monoxide / vinyl acetate was used instead of ethylene / vinyl acetate copolymer. It is also stated in this report 20 that sealants of excellent adhesion and rubberiness were obtained with blends of an ethylene / carbon monoxide / vinyl acetate terpolymer with butyl rubber.

US Pat. No. 3,780,14-0 discloses terpolymers of ethylene / carbon monoxide / monomer and mixtures thereof with a compatible amount of at least one solid organic polymer. Various termonomers are described, such as unsaturated mono- and dicarbanzic acids, esters of such acids, vinyl esters of saturated carboxylic acids, vinyl alkyl ethers, acrylonitrile, etc. Solid organic polymers are described as having preferably polar properties for obtaining molecular compatibility Scale. Such polymers can be polyamides; cellulose-derived polymers; vinyl halide polymers; α-olefin based polymers such as polyethylene, polypropylene, chlorosulfonated polyethylene; ethylene-vinyl ester copolymers; styrene polymers; acrylonitrile polymers and copolymers of at least 40% acrylonitrile and other ethylenically unsaturated comonomers such as vinyl acetate, vinyl chloride and isobutylene; acrylic polymers, polyesters; Polyurethanes; polycarbonates; phenol polymers; polysulfones, epoxy resins; chlorinated polyethers; alkyd resins; acetal resins; ABS resins; silicone resins; tar; Wash; etc.

U.S. Patent 2,495-286 discloses 20 copolymers of ethylene and carbon monoxide with one or more additional polymerizable organic compounds such as other olefins, butadienes, vinyl and vinylidene compounds, vinyl esters, styrene, acrylic and methacrylic acids and their esters, etc. 25

U.S. Patent 5,875-494 discloses curable mixtures and vulcanizates of 100 parts of an ethylene / alkyl acrylate or alkyl methacrylate copolymer or an ethylene / alkyl acrylate or methacrylate terpolymer, wherein the termonomer may include carbon monoxide containing 1 to 30 parts of a butadiene / acrylonitrile polymer. The termonomer is present in an amount no greater than about 10% by weight of the terpolymer.

According to the present invention there is provided a hard hair mixture of (a) 100 parts of a chloroprene polymer and (b) about 3 to 100 parts of an ethylene copolymer selected from the group consisting of ethylene / carbon monoxide / X and ethylene / sulfur dioxide / X copolymers, in which comonomer X is (I) a vinyl ester of an alkanoic acid, the acid containing 1 to 18 carbon atoms, (II) an alkyl acrylate or methacrylate, the alkyl group 1 to 5 being 18 carbon atoms (III) an alkyl vinyl ether, wherein the alkyl group contains 1 to 4 carbon atoms, (IV) acrylonitrile or methacrylonitrile, or combinations of the aforementioned comonomers, wherein the ethylene copolymer is about 3 to 25 wt% carbon monoxide or sulfur dioxide, about 10 contains up to 65% by weight of comonomer X and about 30 to 75% by weight of ethylene.

Furthermore, according to the present invention, there are provided compositions consisting of the aforementioned curable mixtures combined with a peroxide or sulfur curing system. Furthermore, vulcanized products are also provided according to the present invention, obtained by heating the combination of the aforementioned curable mixtures and peroxide and sulfur curing systems. 20

It has been found that the modification of curable blends of chloroprene polymers with an ethylene / carbon monoxide or sulfur dioxide copolymer containing at least one other softening copolymerizable comonomer such as a vinyl ester, alkyl acrylate or methacrylate, acrylonitrile, etc., results in vulcanizates with improved processability, increased ozone resistance and reduced cost.

As a result of the aforementioned improved properties, these modified vulcanizates can be used in extruded forms, such as pipes, sealing rings and electrical cable coatings; in composite structures, such as fiber-reinforced hoses, tapes and coated sheets; in shoe soles, including cellular materials and various shaped articles, such as seals and O-rings.

7906469 * 5 "* 4

The solid chloroprene polymer (neoprene), which is the main component of the blends of the present invention, is a known product. This product can be produced, for example, by emulsion polymerization using a free radical-forming catalyst. 5

Several publications provide extensive discussion of this technology, see, for example, "Polychloro-prene Eubber," by P.E, Johnson, in "Eubber Chemistry and Technology," £ 4. July 3-August, 1976; Encyclopedia of Polymer Science and Technology, Part 3; "The Neoprenes," 10 by E.M. Murray and D.C. Thompson (Elastomer Chemicals Department, Du Pont Company, technical literature). Besides the homopolymers of chloroprene, copolymers, in particular those with 2,3-dichloro-1,3-butadiene, are suitable in the compositions according to the invention. Suitable chloroprene polymers are commercially available for practical purposes.

The ethylene copolymer modifier of the present invention is an ethylene / carbon monoxide or sulfur dioxide copolymer containing at least one additional plasticizing copolymerizable comonomer, such as (a) vinyl esters of an alkane carboxylic acid, wherein the acid is 1 to 18 carbon atoms, for example, vinyl formate, vinyl acetate and vinyl stearate, (b) alkyl acrylates or methacrylates, the alkyl group containing 1 to 18 carbon atoms, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, ethylhexyl acrylate, ( c) an alkyl vinyl ether, wherein the alkyl group contains 1 to 4 carbon atoms, (d) acrylonitrile, methacrylonitrile or combinations of the aforementioned comonomers.

The carbon monoxide or sulfur dioxide component of the ethylene copolymer of the present invention should be present in an amount of about 3 to 25% by weight, preferably about 6 to 15% by weight. 35

The additional plasticizing, copolymerizable 7906469 comonomer component of the ethylene copolymer of the present invention may be present in an amount of from 10 to 65 wt%, preferably from about 20 to 35 wt%.

The amount of ethylene in the copolymer should be about 30 to 75% by weight, preferably about 50 to 70% by weight.

In these copolymers, copolymerized carbon monoxide or sulfur dioxide imparts a high degree of polarity to the polymer without unduly reducing the ethylene content of the polymer. For example, 10 1 wt% copolymerized carbon monoxide imparts a polarity to the polymer equal to 3 to 5 wt% of a representative comonomer X, for example, vinyl acetate, methyl acrylate or 2-ethylhexyl acrylate. This property is important for several reasons: (a) at a relatively high ethylene content, such polymers have sufficient polarity to be compatible with the neoprene rubber and (b) at a given polarity level are copolymers containing copolymerized carbon monoxide or sulfur dioxide less tacky than those containing only ethylene and comonomer X and thus are easier to process due to reduced adhesion to the surfaces of the process equipment.

The amount of ethylene copolymer in the blends of the present invention is about 3 to 100 parts, preferably about 5 to 50 parts, per 100 parts of chloropene polymer.

The chloroprene polymer and the ethylene copolymer can be evenly mixed with any of the conventional mixers, such as a roll mill, extruder, Banbury mixer, or other internal mixers, which are capable of mixing the materials without excessive heating of the mixture . Other constituents, known and common in elastomeric compounds, may also be added. Solid additives include reinforcing agents, fillers, pigments and resins. Examples of such products are carbon black, sulfur dioxide, calcium carbonate and titanium dioxide, hydrocarbon resins and phenolic resins. Liquid additives include process oils and plasticizers, both monomer and polymer, and liquid neoprene rubber.

Other products, such as stabilizers, antioxidants, anti-ozone agents, lubricants, release agents and additives that improve certain properties of the compound, can be added in minor amounts.

The vulcanization of the mixtures is effected by known methods. The chemical vulcanizers can be added to a Banbury mixer, roll mill or other mixer under conditions. which prevent premature curing of the joint. While joint curing of the chloroprene polymer and the ethylene / carbon monoxide or sulfur dioxide copolymer component of this composition may provide better properties, it is not an essential part of the present invention.

Chemicals commonly used for the vulcanization of chloroprene polymers are satisfactory for curing the blends of the present invention. 25

Common hardeners include combinations of zinc and magnesium oxides, alone or with organic accelerators; a sulfur donor or sulfur / destroyer system; and peroxides. Neoprene rubber curing is known. The aforementioned literature references plus Chapter 13 of "Rubber Technology" by Maurice Morton, second edition, contains discussions of this topic. Yoorts provides technical literature from Du Pont Company's Elastomer Chemicals Department for more detailed information. Such bulletins include "Curing Systems for 35

Neoprene ", Bulletin No. SD-235, December 13, 1976; 7906469 7" Hexame thy 1 enetetramine / TMTD / Polyethylene Glycol - A Nonthiourea Cure System for Neoprene, "Bulletin SD-234-, Nov.

1976; "Na-22F - An Accelerator for Polychloroprene Bubber,"

No. 69, Bulletin E-17790.

Polychloroprene polymers behave ill differently from other diene elastomers in baring reactions. The presence of the chlorine atom deactivates the double bond of the polymer and directly limits sulfur vulcanization. Also, allyl chlorine structures in the polymer act as primary crosslinking sites by reaction with metal oxides, which are a necessary part of the curing systems, or with polyfunctional nitrogen compounds, such as finely divided hexamethylene tetramine. Thioureas, such as tetramethylthiourea and especially ethylene thiourea, are accelerators which allow shorter curing times and often provide vulcanizing properties which are otherwise not available by increasing curing time or temperature.

To improve process safety, mercaptobenzothiazyl sulfide, tetraethylthiuram disulfide or poly (ethylene ox; Lde) glycol can be used as retardant activators. The amounts of accelerator and retarder activator can be varied over a wide range depending on the particular chemical composition, the accelerator, retarder activator and the intended use of the vulcanizate. Generally, the amounts of accelerator and retardant activator will range from 0.2 to 4, preferably 0.5 to 2 parts per 100 parts of chloroprene polymer. Peroxide hardeners (100% active base) are also used in the same usage ranges.

The final composition is formed by known methods such as extrusion, injection molding, compression molding, transfer molding or calendering into a sheet or on a substrate, and cured. Heating by 55 steam, hot streams or microwaves can be used 7906469 4.

8 for curing, generally it temperatures from about 100 to 210 ° C for about 0.5 to 120 minutes.

Forewords I - III

These examples teach the use of nitrogen containing compounds to accelerate the curing of neoprene rubber preparations modified with E / VA / CO or E / MA / CO copolymers. Compositions and properties are summarized in Table A. It is noted that the compound of Example II, modified with 10 E / MA / CO, has greater scorch safety and while the ODR torque does not reach as high a level as that of the compound of example I, containing E / VA / CO, has better strength properties and is softer. 15 7906469 9

Table A

Modified enonrene compounds

Example

Components (parts) I II III

"Ifeoprene" W? 0? 0 70 E / 26.6% MA / 6.7% CO, 2.5 MI - 30 E / 23% VA / 11% CO, 35 MI 30 - 30 SEF black 35 .35 35 aromatic processing oil 10 10 low molecular weight polyethylene 2 2 2 magnesium oxide 3 3 4-zinc oxide 5 5 5 octylated diphenylamine 2 2 2 hexamethylene tetramine / binder dispersion (65/35) 1> 5 1.5 1.5 poly (ethylene oxide) glycol, mol wt. 4-000 2 2 1 tetraethylthiuram disulfide 11 - di-o-tolylguanidine - - 1

Properties of the connection

Mooney scorch test at 121 ° C, 21 30+ 18 time to rise by 5 points, min.

ODE torque at 30 min., 162 ° C, 71 * 4-4-0.3 85.2 kg. cm

Hardened for 20 min, at 162 ° C

tensile strength, MPa 13 »6 14-, 4-14-, 5 elongation,% 290 4-4-0 300 modulus at 100% tension, MPa 3» 4- 1.8 4., 3

Shore A hardness 72 63 78 (1) polychloroprene available from E.I. du Pont de

Hemours & Company, has a Mooney viscosity of 50.

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Control example C1 and example IY

In these examples, the utility of E / VA / CO copolymer is illustrated in the modification of chloroprene polymer.

The formulations for these examples are in parts by weight as follows: binder 100; SEP carbon black 80; atomic processing oil 30; octylated diphenylamine antioxidant 2; low molecular weight polyethylene 2; stearic acid 0.5; di-o-tolylguanidine 0.75; tetramethyl-thiuram monosulfide 0.75; sulfur 1.0 and zinc oxide 5 · Id. Control Example C1 is the binder 100 parts by weight of chloroprene polymer ("Neoprene" Tidiv, Mooney viscosity 120) and in Example IV, the binder is 75 parts by weight "Neoprene" WHV and 25 parts by weight of the VA / CO copolymer of Example 1. The properties of the vulcanizates of both these compounds are included in Table B. Examples obtained by using the E / VA / CO copolymer include reduced costs, improved processing, increased ozone resistance, and reduced permanent shape change by pressure. The binder of Example IV was prepared in the form of a base mixture, and an appropriate portion of the base mixture was then used for each composition.

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Table B

Heoprene and Neoprene - E / VA / CO vulcanizate properties

Properties C1 example _ _ IV_

Mooney viscosity, ML - 4 · 76 56

Mooney Scorch test, Δ5, minutes> 30 11 tensile strength, MPa 19> 0 17 »2 elongation,% 330 270

Shore A hardness 7 ^ 79 hardening under pressure,% 61 52 (22 hours at 100 ° C) ozone resistance bar- very little (curved loop, 24 hours at 100 ppm) cracks cracks formed surface good very good tear strength, punch "C" H / mm 4-2 35

Control example C2 and examples V and VI

These examples are a control example, a thiourea accelerated thiuram curing system and a peroxide curing system, respectively. All soil masses contain SEE carbon black, 35 parts by weight; low molecular weight polyethylene lubricant 5 parts by weight; octylated diphenyl amine antioxidant 2 parts by weight; magnesium oxide acid binding agent 4 parts and zinc oxide acid binding agent / activator 5 parts. The various binder systems and curing agents used in these examples are listed in Table C.

As can be seen from the data in Table C, the use of the E / VA / CO terpolymer in a neoprene compound gives a lower processing viscosity and a vulcanizate with lower tensile strength and greater hardness. With peroxide cure, the scorch time is twice that of a sulfur cure system for the modified compounds and is therefore safer. The tensile strength, the percent elongation and permanent shape change under pressure of the peroxide vulcanizate are better than that of the sulfur vulcanizate. 20 7906469 12

Table C

Comparison of sulfur and primary oxide curing

Example

Components (parts) 02 V VI

"Neoprene" W 100 70 70 E / 23.5% VA / 11% CO, 35 MI - 30 30 2-mercaptoimidazoline (ethylene thiourea) / ethylene / propylene rubber dispersion (75/25) 0.75 0.75 tetramethylenethiuram monosulfide 0.75 0.75 a.a'-bis (butylperoxy) diisopropyl benzene Burgess KE clay (40/60) - - 1.5 SEE black 35 55 55 low molecular weight polyethylene 2 2 2 magnesium oxide 4 4 4 zinc oxide 555 octylated diphenylamine 222

Mooney Scorch test at 121 ° C.

minimum viscosity 25 18 18 time to 5 point rise in min. 16 20 40 OBR curing bi, j 162 ° C (50 min) maximum torque, kg.cm 88.7 49 »5 50.7 time to 90% of max ., minutes 3 »5 5 * 0 5 * 5

Properties after curing (162 ° C «15 min) tensile strength, MPa 21.4 15» 8 16.5 modulus 2.9 3 »4 3» 1 elongation% 430 430 470

Shore A hardness 68 77 76 permanent shape change by pressure (hardened 162 ° C, 20 min) 22 h at 100 ° C, method B of ASTM D 595_% 39 52 40 7 906 469 13

Control Example C5 and Examples VII and VIII

All soil compositions contained 35 parts by weight of SEF carbon black, 2 parts by weight of low molecular weight polyethylene, 4 parts by weight of magnesium oxide, 2 parts by weight of octylated diphenylamine, 5 parts by weight. din zinc oxide, 1 part by weight of poly (ethylene oxide) glycol, 1 part by weight. 5 parts of tetraethylthiuram disulfide and 1.5 parts of hexamethylene tetramine / binder dispersion (65/35). Additional ingredients in each compound are listed in Table D with data on the properties of the mixtures and their vulcanizates. The use of E / VA / CO in compounds 10 VII and VIII again shows the surprising results that ozone resistance and ASIM oil resistance No. 3 are improved over the starting neoprene compound. The compound of Example VIII, modified with dioctyl sebacate, a plasticizer at low temperature, shows a good reaction. Improvements in both impact strength at low temperatures and until stiffening are obtained.

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Table D

Comparison of processing oil and ester plasticizer modification_______

Example

Components (parts) 03 VII VIII

"ITeoprene" W 100 70 70 E / 23.5% VA / 11% CO, 35 MI - 30 30 aromatic processing oil 20 20 dioctyl sebacate - - 30 SRI black 35 35 35 low molecular weight polyethylene 222 magnesium oxide 444 zinc oxide 555 octylated diphenylamine 222 hexamethylene tetramine / binder dispersion (65/35) 1 * 5 1 * 5 1 * 5 poly (ethylene oxide) glycol, mol. 4000 111 tetraethylthiuram disulfide 111

Mooney scorch test at 121 ° C

minimum viscosity 12 8 5 time to increase of 5 points in min. 25 20 32 ODE curing. 162 ° C (30 min) maximum torque, kg.cm 55 * 3 64.5 44.9 time to 90% of max., Minutes 18 20 22

Properties after curing (162 ° C. 20 min) tensile strength, MPa 17 * 9 13 * 1 10.3 modulus at 100% tension, MPa 1.5 2.5 2.1 elongation,% 500 290 280

Shore A hardness 52 62 56 permanent shape change by pressure (162 ° 0.25 min) 22 h at 100 ° C, method B of ASTM D 395% 29 40 47 ozone exposure, 1 ppm 0, 30% elongation. 4 days__ bar- no surface area ^ ^ 7906469 15 gabel Ώ (continued)

Example

Properties 05 VII VIII

volume increase, 70 h at 100 ° C, ASIM oil no. 5% 77 60 54

oven aging, 7 days at 121 ° C

tensile strength, MPa 12.8 12.8 9.3 elongation,% 260 85 65

Shore A hardness 72 84 80

Passed solenoid brittleness test, ° C -58 -40 -60 failed, ° C -42 -46 * -60 low temp, stiffening, ASIM D 1043 modulus, MPa 25.8 ° C 2.5 2.4 2.5 -54 , 4 ° C 18.6 40.7 6.2 -40.0 ° C 165.5 172.4 7.6 -45.5 ° C - - 10.5 -51.1 ° C - - 20.7 79 0 6 4 6 9

Claims (3)

A hard-hair mixture of ethylene terpolymer and an elastomeric polymer, characterized in that. the mixture (a) contains 100 parts by weight of a chloroprene polymer and (b) about 3 to 100 parts by weight of an ethylene copolymer 5 selected from the group consisting of ethylene / carbon monoxide / X and ethylene / sulfur dioxide / X copolymers, wherein comonomer X (I) is a vinyl ester of an alkanoic acid, the acid containing 1 to 18 carbon atoms, (II) an alkyl acrylate or methacrylate, the alkyl group containing 1 to 18 carbon atoms, (III) an alkyl vinyl ether, where the alkyl group contains 1 to 4 carbon atoms, (IV) acrylonitrile or methacrylonitrile or combinations of the aforementioned comonomers, the ethylene copolymer being about 3 to 25 wt% carbon monoxide or sulfur dioxide, about 10 to 65 wt% comonomer X and contains about 30 to 75% by weight of ethylene. A composition, characterized by the presence of the curable mixture of claim 1 and a peroxide or sulfur curing system. 20 Vulcanized product, characterized in that this product is obtained by heating the composition of claim 2 for about 30 seconds to 120 minutes at about 100 to 210 ° C. ******* 7906469