SULPHUR-VULCANISABLE POLYMER COMPOSITIONS

Abstract: A sulphur-vulcanisable polymer composition which comprises a sulphur vulcanisation system and a hydrogen­ ated copolymer, containing 0.5 to 1 mole % unsaturation, of a C₄₋₆ conjugated diene and a C₃₋₅ α,β-unsaturated nitrile.

Description: This invention relates to sulfur vulcanizable polymer compositions comprising a hydrogenated copolymer of a conjugated diene and an a,8-unsaturated nitrile and a sulfur vulcanization system, the vulcanizates of which compositions exhibit a good combination of resistance to oils, ozone and elevated temperature aging under oxidizing conditions. More particularly, the invention relates to compositions wherein the amount of remaining carbon-carbon double bond unsaturation in the hydrogenated copolymer is very low, i.e. from less than about 1 to about 0.05 mole per cent of the copolymer. The effects of oxidizing conditions on vulcanizates obtained from polymers having carbon-carbon double bond unsaturation have long been a problem, particularly in applications where the vulcanizates are exposed to elevated temperatures for extended periods of time. A variety of approaches have been developed in the art in an attempt to solve this problem. It is known that the carbon-carbon double bonds of such polymers activate the vulcanizate to oxidative attack. One obvious solution to the problem of oxidative attack is to use polymers with few or no carbon-carbon double bonds. Examples of such polymers include butyl rubber (copolymers of isobutylene and isoprene) which typically contain about 0.5 - 3.0 mole per cent of carbon-carbon double bond unsaturation, and ethylene-propylene copolymers which contain no sucb unsaturation. Certain applications, such as the various hoses and seals in the engine compartment of automobiles, require vulcanized polymers with a combination of oil resistance, ozone resistance and resistance to oxidative attack in air at elevated temperatures for extended periods of time. Vulcanizates of copolymers of conjugated dienes and a,ss-unsaturated nitriles, such as an acrylonitrile-butadiene- copolymer, commonly known as nitrile rubber or NBR, are well known for their oil resistance. However, they contain carbon-carbon double bond unsaturation and therefore are susceptible to oxidative attack unless subjected to special compounding procedures for the production of oxidation resistant vulcanizates. In order to reduce the amount of carbon-carbon double bond unsaturation in NBR and yet retain the copolymer's oil resistance which is thought to be provided by the nitrile functional groups in the copolymer, methods bave been developed to selectively hydrogenate the carbon-carbon double bond unsaturation of NBR witbout hydrogenating the nitrile groups as sbown, for example, in British patent 1,558,491. Butyl rubber may be vulcanized using sulfur vulcanization systems which include accelerators such as thiuram or dithiocarbamate compounds. Etbylene-propylene copolymers, which contain no unsaturation, cannot be vulcanized by conventional sulfur systems. Frencb Patent 2,421,923 teaches the sulfur vulcanization of partially hydrogenated copolymers of acrylonitrile and a conjugated diene containing 2 - 25 per cent and preferably 5 - 20 per cent by weight of unsaturated diene units based on the total weight of copolymer using morpboline or thiuram compounds as accelerators. U.S. Patent 4,350,796 teaches that a rubber composition, comprising a mixture of (1) a partially hydrogenated elastomer from an unsaturated nitrile monomer and a conjugated diene monomer wberein the degree of bydrogenation of the conjugated diene units is 50 to 98 mole per cent and (2) a vinyl chloride resin, may be vulcanized with sulfur. The patent teaches that if the degree of hydrogenation exceeds 98 mole per cent, then sulfur vulcanization becomes too slow to be practical. One skilled in the art would not consider that it would be possible to use a sulfur vulcanization system for the vulcanization of hydrogenated copolymers of conjugated dienes and nitriles which contain very low amounts of carbon-carbon double bond unsaturation. Surprisingly, it has now been discovered that bydrogenated copolymers of conjugated dienes and unsaturated nitriles which contain from less than about 1 to about 0.05 mole per cent, based on the copolymer, of carbon-carbon double bond unsaturation, may be vulcanized using a wide variety of sulfur vulcanization systems to produce vulcanizates with a good combination of resistance to oils, ozone, and oxidative attack in air at elevated temperatures for extended periods of time. Accordingly, the present invention provides a sulfur vulcanizable polymer composition comprising (i) a copolymer of a C46 conjugated diene and a C35 a,(3-unsaturated nitrile, the carbon-carbon double bond unsaturation of said copolymer baving been selectively hydrogenated such that the remaining unsaturation is from less than about 1 to about 0.05 mole per cent of said copolymer, and (ii) a sulfur vulcanization system. The present invention also provides a process for preparing a sulfur vulcanizable polymer composition comprising admixing (i) a copolymer of a C46 conjugated diene and a C35 a,ss-unsaturated nitrile, the carbon-carbon double bond unsaturation of said copolymer baving been selectively hydrogenated sucb that the remaining unsaturation is from less than about 1 to about 0.05 mole per cent of said copolymer, and (ii) a sulfur vulcanization system. Tbe present invention further provides a vulcanizate prepared by vulcanizing an admixture of (i) a copolymer of a C4-6 conjugated diene and a C3-5 &alpha;,ss-unsaturated nitrile, the carbon-carbon double bond unsaturation of said copolymer baving been selectively bydrogenated sucb that the remaining unsaturation is from less than about 1 to about 0.05 mole per cent of said copolymer, and (ii) a sulfur vulcanization system. In the copolymers used in the present invention, suitable C46 conjugated dienes include butadiene, isoprene, piperylene and dimethylbutadiene. Butadiene is preferred. Suitable C35 nitriles include acrylonitrile and methacrylonitrile. Solid copolymers of butadiene and acrylonitrile are preferred. These copolymers generally contain from about 15 to about 50 per cent and preferably from about 25 to about 45 per cent by weight of acrylonitrile. Tbe copolymers may be selectively hydrogenated using the process described in Britisb Patent 1,558,491, or other processes known to the art. The amount of carbon-carbon double bond unsaturation remaining following hydrogenation must be controlled. It bas been found that if the remaining unsaturation is less than about 1 mole per cent of the copolymer, then the vulcanizates obtained from the copolymers have high resistance to ozone, good oil resistance, and also retain elastomeric properties when exposed to oxidative conditions at elevated temperatures for extended periods of time. Sufficient unsaturation must remain to provide enough sites in the copolymer for reaction witb the sulfur vulcanization system to allow a sufficient degree of crosslinking upon vulcanization and thereby provide suitable properties of the vulcanizate. It has been found that a practical minimum amount of retained unsaturation is about 0.05 mole per cent of the copolymer. Tbus, the amount of remaining carbon-carbon double bond unsaturation in the copolymer should be from less than about 1 to about 0.05 mole per cent of the copolymer, preferably from about 0.6 to about 0.05 mole per cent, and most preferably from about 0.1 to about 0.05 mole per cent. The sulfur vulcanization system used herein comprises organic sulfur compounds known as accelerators. The amounts of the accelerators which are used are those which have been used in the art for the sulfur vulcanization of conventional non-hydrogenated diene-nitrile copolymers. Tbe total weight of accelerators used is from about 0.2 to about 6 parts by weight per 100 parts by weight of copolymer. Tbe accelerators are selected from thiuram, ditbiocarbamate, sulfenamide, thiazole and morpholine compounds, bis-(3-(triethyloxysilyl)propyl) tetrasulfide, and mixtures thereof with one another. Suitable thiuram compounds include thiuram monosulfides, disulfides, and polysulfides. Preferred tbiuram monosulfides and disulfides include the tetra(C1-4-alkyl) tbiuram monosulfides and disulfides. Preferred thiuram polysulfides include dipentamethylene tbiuram tetrasulfide and hexasulfide. Suitable dithiocarbamate compounds include the di(Cl 5-alkyl) dithiocarbamates of zinc, bismutb, nickel, cadmium, copper, lead, selenium and tellurium. Zinc dimethyl and zinc dietbyl dithiocarbamate are preferred. Suitable sulfenamide compounds include the N-alkyl-, N-cycloalkyl- and N,N-dialkyl-2-benzotbiazyl sulfenamides, N-oxydietbylene-2-benzotbiazyl sulfenamide and the thiocarbamyl sulfenamides. N-cyclobexyl-2-benzotbiazyl sulfenamide and N-oxydietbyleneditbiocarbamyl N'-oxydietbylene sulfenamide are preferred. Suitable tbiazole compounds include mercaptobenzotbiazole and its derivatives. Mercaptobenzothiazole and benzothiazyl disulfide are preferred. Tbe preferred morpboline compound is 4,4 -dithiodimorpholine. Mixtures of tbese compounds known in the art of sulfur vulcanization of non-bydrogenated diene-nitrile copolymers may also be used. Tbe sulfur vulcanization system may also include elemental sulfur. The weight of elemental sulfur, when used, is from about 0.1 to about 2 parts by weight per 100 parts by weight of the copolymer. Tbe polymer compositions of the present invention may be heated to form vulcanizates using conventional procedures well known in the art. Suitable temperatures are from about 1350 to about 2000C, preferably from about 1500 to about 1700C, for periods of from about 2 minutes to about 15 hours, preferably from about 5 minutes to about 30 minutes. In the process of the present invention, the hydrogenated copolymer and the sulfur vulcanization system may be admixed in any manner known to the art for use witb conventional non-bydrogenated copolymers, for example on a two-roll rubber mill or an internal mixer. Otber compounding ingredients may also be mixed with the copolymer and vulcanization system in the usual manner. Such other compounding ingredients include vulcanization co-agents sucb as N,N -m-phenylenedimaleimide, activators such as zinc oxide and magnesium oxide, stearic acid, antioxidants, plasticizers, processing aids, reinforcing agents, fillers, promoters and retarders-in amounts well known in the art. The polymer compositions of the present invention on vulcanization exhibit an improved combination of resistance to oils, ozone, and oxidative attack in air at elevated temperatures for extended periods of time when compared to compositions heretofore known. The following examples illustrate the present invention but are not intended to be limiting. Example 1 In this and succeeding examples, the same basic procedure was followed. 10 g samples of copolymer were mixed on a two-roll micro mill and compounded by addition of compounding ingredients in the conventional manner. The resulting polymer compositions were then cured at 1600C for the times shown. The physical properties of the. resulting vulcanizates were tben determined following ASTM standard methods as closely as possible. Tensile properties, including tensile stress (usually known as modulus) at 100 and 300 per cent elongation and at rupture (usually known as tensile strengtb) and per cent elongation at rupture, were determined according to ASTM-D412-80. Hardness properties were determined using a Type A Shore durometer according to ASTM-D2240-81. Hot air aging was carried out according to ASTM-D865-81 and oil aging in ASTM Oil No. 3 according to ASTM-D471-79. Ozone resistance was determined according to ASTM-D1149-81 on Type A specimans at 400 C, 20 per cent extension and at an ozone concentration of 50 parts per 100 million parts of air by volume. The copolymers used in this and succeeding examples are listed in Table 1. Copolymer A was a comparative solid non-bydrogenated NBR, copolymers B, C and D were comparative solid partially bydrogenated NBR's baving greater than 1 mole per cent remaining unsaturation in the copolymer, and copolymers E to-I were solid hydrogenated -NBR's useful inthe present invention. The amount of carbon-carbon double bond unsaturation in copolymers B to I was determined by proton-NMR spectroscopy and toe values are believed to be accurate to + 10 per cent of the values given. Tbe amount of unsaturation is the mole per cent of -CH2-CH=CH-CH2and/or -CH2-CH(CH=CH2)- units in the copolymer. Table 1 NBR Copolymmer % by Weigbt Mole Per Cent Carbon-Carbon Designation Acrylonitrile Double Bond Unsaturation A (comparative) 34 65.6 B (comparative) 34 5.3 C (comparative) 46 4.4 D (comparative) 34 2.0 E 34 0.57 F 40 0.55 G 40 0.51 H 34 0.47 I 34 0.06 This example compares the properties of vulcanizates of the present invention prepared from Copolymers H and I witb the properties of a comparative vulcanizate prepared from Copolymer A. The copolymers each were compounded by addition of the compounding ingredients listed in Table 2. Vulcanizates were prepared using different cure times as sbown and the physical properties were determined. Data are given in Table 3. In this and succeeding tables, the symbol (*) indicates that tbe vulcanizate had deterioriated to an extent wbere the datum could not be determined, wbile the symbol (nm) indicates the value was-not measured. Table 2 Amount (parts by weight per 100 parts by weight of Compounding Ingredient copolymer Sulfur 0.4 Mixed tetra(C1-2-alkyl) thiuram disufide 2.5 N-cyclobexyl-2-benzotbiazyl sulfenamide 2.0 N,N -m-pbenylenedimaleimide 2.0 Stearic acid 0.5 Zinc oxide 5.0 Magnesium oxide 10 Precipitated amorpbous bydrated silica 50 Polyether polytbioether plasticizer 10 Processing aid (sold under trade name TE 80 by Tecbnical Processing Inc.) 1.0 p-Cumyldiphenyl amine 2.0 Table 3 Copolymer designation A A H H I I Cure time (min.) 7 17 14 24 14 24 Physical Properties - Unaged Hardness 67 67.5 69 70 70 70 Tensile stress (MPa) - at 100% elongation 2.6 2.6 1.9 1.9 2.0 2.0 - at 300% elongation 7.1 7.1 5.4 4.9 3.7 3.9 - at rupture 12.9 12.9 22.1 21.6 20.1 19.6 Elongation, % at rupture 500 500 720 720 830 840 Physical Properties - Aged in Air at 150 C for 70 Hours Hardness 72 74 72 70 73 74 Tensile stress (MPa) - at 100% elongation 5.4 5.4 2.0 3.5 2.9 2.9 - at 3 W elongation 12.3 - 5.9 7.8 6.4 6.9 - at rupture 12.3 11.8 19.4 19.6 15.2 17.6 Elongation, % at rupture 300 280 690 700 750 800 Physical Properties - Aged in Air at 150 C for 168 Hours Hardness 90 91 77 79 77 76 Tensile stress (MPa) - at 100% elongation * * 3.9 2.0 3.9 4.4 - at 30X elongation * * 9.3 6.9 8.3 8.3 - at rupture * * 17.2 16.2 14.2 15.2 Elongation, % at rupture 25 10 600 600 640 620 Physical Properties Aged in Air at 15(PC for 500 Hours Hardness nm nm 85 85 nIl- nm Tensile stress (MPa) - at 100% elongation * * 6.4 5.9 5.9 5.9 - at 300% elongation * * 11.3 10.8 10.8 11.0 - at rupture * * 14.7 13.2 13.2 13.1 Elongation, % at rupture * * 520 500 500 450 Physical Properties - Aged in Air at 150 C for 1,000 Hours Hardness 96 94 84 85 87 87 Tensile stress (MPa) - at 100% elongation * * 2.9 2.9 9.8 9.0 - at 300% elongation * * 12.3 12.7 13.7 12.7 - at rupture * * 13.2 12.7 13.7 13.7 Elongation, % at rupture * * 350 310 300 350 It can clearly be seen that even after 1,000 hours of aging in air at 1500C, the vulcanizates prepared from Copolymers H and I retain useful elastomeric properties whereas those from comparative Copolymer A lose most of tbeir elastomeric properties at between 70 and 168 hours. Example 2 Tbis example compares properties, before and after aging, of vulcanizates obtained from polymer compositions with varying amounts of remaining carbon-carbon double bond unsaturation in the copolymer. Tbe copolymers were compounded as in Example 1 and eacb was cured at 1600C for the times shown. Physical properties were tben determined and data are shown in Table 4. copolymers A to I were as described in Example 1. It can clearly be seen from Table 4 that copolymers E to I bave mucb superior physical properties after air aging and also mucb superior ozone resistance compared to copolymers A to D. Table 4 Copolymer designation A B C D E F G H I Cure Time (min.) 8.5 6.5 8.5 5.0 22.5 23 11.5 14 12.5 Physical Properties - Unaged Hardness 64 71 71 70 67 72 68 69 71.5 Tensile stress (MPa) - at 100% elongation 2.4 3.7 2.5 3.0 1.2 1.5 2.5 1.9 1.9 - at 300% elongation 5.9 11.3 6.9 9.8 2.0 2.9 5.4 5.4 3.5 - at rupture 16.0 25.0 20.6 23.5 9.3 14.2 23.5 22.1 18.1 Elongation, % at rupture 700 490 600 510 900 880 680 720 800 Physical Properties - Aged in Air at 150 C for 70 Hours Hardness nm nm nm nm 75 79 80 72 78 Tensile stress (MPa) - at 100% elongation 5.9 7.4 5.1 5.9 2.0 2.9 4.5 2.0 2.9 - at 300% elongation - 14.7 15.2 17.2 4.4 5.9 9.3 5.9 5.9 - at rupture 12.3 20.0 20.1 21.6 16.7 17.2 20.3 19.4 16.2 Elongation, % at rupture 290 350 450 400 900 770 700 690 710 Physical Properties - Aged in Air at 150 C for 168 Hours Hardness nm nm nm nm 78 82 81.5 77 80.5 Tensile stress (MPa) - at 100% elongation - 14.7 10.3 9.3 3.7 3.7 3.5 3.9 3.5 - at 300% elongation - - - 19.1 6.9 6.9 5.6 9.3 6.6 - at rupture 18.1 20.3 18.4 19.1 14.9 16.5 9.8 17.2 14.5 Elongation, % at rupture 30 200 270 300 820 630 625 600 650 (Table 4 Continued) Copolymer designation A B C D E F G H I Physical Properties - Aged in Air at 150 C for 500 Hours Hardness 98 94.5 93 91.5 75 78 88 85 77 Tensile stress (MPa) - at 100% elongation * - - 19.6 2.4 2.5 7.8 6.4 2.5 - at 300% elongation * - - - 7.4 9.5 12.3 11.3 10.3 - at rupture * 22.1 20.0 20.6 12.6 15.0 13.9 14.7 13.4 Elongation, % at rupture * 50 90 110 610 500 450 520 495 Physical Properties - Aged in Air at 150 C for 1,000 Hours Hardness nm nm nm nm nm nm 87.5 84 nm Tensile stress (MPa) - at 100% elongation * * * * 6.5 6.7 13.7 2.9 7.8 - at 300% elongation * * * * 9.2 5.9 - 12.3 10.2 - at rupture * * 7.0 > 10.0 10.6 12.4 16.2 13.2 11.2 Elongation, % at rupture * * 20 30 530 480 220 350 400 Physical Properties - Ozone Resistance (Rating: O=no cracks, 5=severe cracking) - after 24 hours 2 0 1 0 0 0 0 0 0 48 hours 3 0 1 0 0 0 0 0 0 72 hours 5 1 1 1 0 0 0 0 0 96 hours 5 2 1 2 0 0 0 0 0 120 hours 5 3 1 3 0 0 0 0 0 144 hours 5 3 2 3 0 0 0 0 0 168 hours 5 4 2 3 0 0 0 0 0 Example 3 Tbis example illustrates the use of different sulfur vulcanization systems containing botb elemental sulfur and organic sulfur compounds to prepare vulcanizates of the present invention. Four 10 g samples of Copolymer I were compounded with the ingredients shown in Table 5. Each was cured at 1600C for the time indicated and its pbysical properties determined. The data are given in Table 6. Table 5 Amount (parts by weight per 100 parts by Compounding Ingredient weight of copolymer) Sample designation: 5-1 5-2 5-3 5-4 Sulfur 1.5 0.5 0.2 Tetrametbyl thiuram monosulfide 1.5 -- Benzotbiazyl disulfide 0.3 -- N-cyclohexyl-2-benzothiazyl sulpbenamide --- 1.0 1.0 2.0 Tetramethyl thiuram disulfide --- 2.0 1.5 Bis-[3-(trietbyloxysilyl)propyl] tetrasulfide --- --- 2.0 N-oxydiethylenedithiocarbamyl N'-oxydietbylene sulfenamide --- --- 2.5 Mixed tetra(C1,2-alkyl) thiuram disu fide --- --- --- 2.5 N,N -m-phenylenedimaleimide --- --- --- 2.0 Stearic acid 1.0 1.0 0.5 0.5 Zinc oxide 5.0 5.0 5.0 5.0 Magnesium oxide --- --- 10 10 Silica (precipitated hydrated amorpbous) 50 50 50 50 Polyether polytbioetber plasticizer 10 10 10 10 Processing aid TE 80 --- --- 1.0 1.0 p-Cumyldiphenyl amine 2.0 2.0 2.0 2.0 Table 6 Sample designation 5-1 5-2 5-3 5-4 Cure time (minutes) 16.5 16.0 21.0 12.5 Physical Properties - Unaged Hardness 67 68.5 70.5 71.5 Tensile stress (MPa) - at 100% elongation 1.5 1.5 1.9 1.9 - at 300% elongation 2.5 2.5 3.9 3.5 - at rupture 22.5 20.4 18.1 18.1 Elongation, % at rupture 860 830 820 800 Physical Properties - Aged in Air at 150 C for 70 Hours Hardness 76 76 76 78 Tensile stress (MPa) - at 100% elongation 2.9 2.5 1.9 2.9 - at 300% elongation 8.8 6.4 4.9 5.9 - at rupture 17.2 18.6 14.7 16.2 Elongation, % at rupture 620 800 820 710 Physical Properties - Aged in Air at 150 C for 168 Hours Hardness 81.5 78 77 80.5 Tensile stress (MPa) - at 100% elongation 3.9 3.0 3.0 3.5 - at 300% elongation 10.2 7.6 6.7 6.6 - at rupture 17.3 16.9 14.1 14.5 Elongation, % at rupture 560 690 710 650 Physical Properties - Aged in Air at 1500C for 500 Hours Hardness 78 74 78 77 Tensile stress (MPa) - at 100% elongation 2.9 .2.4 6.5 2.5 - at 300% elongation 13.7 11.6 11.8 10.3 - at rupture 17.0 16.5 14.5 13.4 Elongation, % at rupture 350 455 500 495 Physical Properties - Aged in Air at 150 C for 1,000 Hours Hardness nm nm nm rin Tensile stress CMPa) - at 100% elongation 12.7 9.8 6.9 7.8 - at 300% elongation - - 10.8 11.2 - at rupture 15.9 14.3 11.4 11.2 Elongation, % at rupture 180 230 400 400 Physical Properties - Ozone Resistance (Rating: Ckio cracks, 5=severe cracking - after 168 hours 0 0 0 0 Example 4 This example compares the oil resistance properties of vulcanizates of the present invention prepared from Copolymers E, F and I with those of comparative vulcanizates prepared from Copolymers A and C. Each copolymer was compounded as in Example 1. The data obtained are sbown in Table 7. Table 7 Copolymer designation A C E F I Cure time (minutes) 7 11 22.5 23 12.5 Physical Properties - Aged in - ASTM Oil No. 3 at 1500C for 70 Hours Tensile stress (MPa) - at 100% elongation 8.3 2.0 1.0 7.4 1.0 - at 300% elongation 9.3 5.9 7.4 5.4 7.4 - at rupture 9.8 19.1 6.9 13.2 8.8 Elongation, % at rupture 340 710 800 700 740 % Weigbt Cbange 8.6 11.9 19.9 7.8 21.3 Example 5 This example illustrates that compositions of the present invention containing carbon black may be cured using a sulfur vulcanization system. Two 10 g samples of Copolymer I were compounded with the ingredients sbown in Table 8, cured at 1600C and the pbysical properties of the vulcanizates determined. Data are given in Table 9. Table 8 Compounding Ingredient Amount (parts by weight per 100 parts weight of copolymer Sample designation: 8-1 8-2 p-Cumyldiphenyl amine 2.0 2.0 Sulfur 0.4 0.2 Zinc Oxide 5.0 5.0 Stearic acid 0.5 0.5 Magnesium oxide 10 10 Carbon black ASTM Type N550 40 40 Carbon black ASTM Type N762 50 50 Polyether polythioether plasticizer 20 20 Processing aid TE 80 1.0 1.0 N-cyclohexyl-2-benzothiazyl sulphenamide 2.0 1.0 Mixed tetra(C1-2-alkyl) thiuram disulfide 2.5 - Tetrametbyl thiuram disulfide - 1.5 Bis-[3-(triethyloxysilyl)propyl] tetrasulfide -- 2.0 N-oxydiethylenedithiocarbamyl-N' oxydiethylene sulfenamide -- 2.5 N,N1-m-pbenylenedimaleimide 2.0 - Table 9 Sample Designation: 8-1 8-2 Cure Time (minutes): 14.5 22.5 Physical Properties - Unaged Hardness 80 76 Tensile stress (MPa) - at 100% elongation 2.9 2.6 - at 300% elongation 5.4 4.7 - at rupture 9.3 8.2 Elongation, % at rupture 780 750 Physical Properties - Aged in Air at 1500C for 70 Hours Hardness 90 89 Tensile stress (MPa) - at 100% elongation 8.2 8.2 - at rupture 10.6 11.8 Elongation, 5 at rupture 280 280 Example 6 Tbis example illustrates that a composition of the present invention prepared from Copolymer I may be cured using a sulfur vulcanization system containing no elemental sulfur. A 10 g sample of Copolymer I was compounded with the ingredients shown in Table 10, cured at 1600 for 14 minutes and the unaged pbysical properties determined as shown in Table 11. A similar composition prepared from non-bydrogenated Copolymer A, compounded in an identical manner and cured at 1600C for 8.5 minutes is included for comparison. Table 10 Compounding-Ingredient Amount (parts by weight per 100 parts by weight of copolymer) Poly(l,2-dihydro-2,2,4- trimetbyl quinoline) 2.0 Stearic- acid 1.5 Zinc oxide 5.0 Carbon black ASTM Type N550 40 N-oxydietbylenedithiocarbamyl N'-oxydiethylene sulfenamide 3.0 Tetrametbyl thiuram disulfide 1.0 Benzotbiazyl disulfide 1.0 4,41-Ditbiodimorpholine 2.0 Table 11 Physical Propeties - Unaged Copolymer A Copolymer I Hardness 58 67 Tensile stress (MPa) - at 100 elongation 2.9 2.9 - at 300 elongation 8.3 7.4 - at rupture 19.6 24.0 Elongation, % at rupture 630 800

Claims: CLAIMS 1. A sulphur-vulcanisable polymer composition which comprises a sulphur vulcanisation system and a hydrogenated copolymer, containing 0.5 to 1 mole % unsaturation, of a C46 conjugated diene and a C35 a,ss-unsaturated nitrile. 2. A composition according to claim 1, in which the copolymer is a butadiene-acrylonitrile copolymer. 3. A composition according to claim 1 or claim 2, in which the copolymer contains from 0.05 to 0.6 mole % unsaturation. 4. A composition according to claim 3, in which the copolymer contains from 0.05 to 0.1 mole % unsaturation. 5. A composition according to any preceding claim, in. which the sulphur vulcanisation system comprises an accelerator- selected from thiuram, dithiocarbamate, sulphenamide, thiazoles, morpholines, bis(3-triethoxysi lylpropyl) tetrasulphide,and mixtures thereof. 6. A composition according to claim 5, in which the sulphur vulcanisation system additionally comprises elemental sulphur. 7. A process for preparing a vulcanisate, which comprises heating a composition according to any preceding claim at from 135 to 2000C for from 2 minutes to 15 hours.

Inventors: DUNN, JOHN ROBERT
Applicants: POLYSAR LIMITED
Application year: 1983
Main classification: C08C19
IPC codes: C08L33, G01N33, C08K3, C08L7, A61B19, C08C19, C08L21, C08K5, C08L15, C08L9