Thermoplastic vulcanizates of olefin rubber and polyolefin resin
AssigneeMonsanto Company
InventorsAubert Y. Coran, Balbhadra Das, Raman P. Patel
Life of this patent
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Abstract
Thermoplastic vulcanizates, comprising blends of olefin rubber and thermoplastic olefin resin in which the rubber is completely cured, exhibit superior physical properties including improved tensile strength.
Claims52
A thermoplastic elastomeric composition comprising a blend of about 25 to about 85 parts by weight of crystalline thermoplastic polyolefin resin and about 75 to about 15 parts by weight of vulcanized monoolefin copolymer rubber per 100 parts total weight of said resin and rubber, and extender oil up to 300 parts by weight per 100 parts by weight of rubber provided that, when the amount of resin is greater than 75 parts by weight, extender oil must be present in an amount sufficient to satisfy the equation (W.sub.o + W.sub.R)/W.sub.P is equal to or greater than 0.33 wherein W.sub.o is the weight of extender oil, W.sub.R is the weight of rubber and W.sub.p is the weight of resin, wherein the rubber in said blend is a polymer of monomers comprising ethylene or propylene, and at least one other alpha olefin of the formula CH.sub.2 .dbd. CHR in which R is alkyl of 1-12 carbon atoms and from none to a minor portion of at least one copolymerizable diene in the form of small dispersed particles essentially of a size of about 50 microns or below and is vulcanized to the extent that no more than about three percent of the rubber is extractable in cyclohexane at 23.degree. C. or that the cross-link density determined on the same monoolefin copolymer rubber as in the blend is greater than about 7 .times. 10.sup.-5 moles per ml of rubber, the composition being processable in an internal mixer to a product which, upon transferring, with the resin in the molten state, to the rotating rolls of a rubber mill forms an essentially continuous sheet.
A thermoplastic elastomeric composition comprising a blend of
- (a) about 25-75 parts by weight of crystalline thermoplastic polyolefin resin and
- (b) about 75-25 parts by weight of vulcanized monoolefin copolymer rubber, the rubber being a polymer of monomers comprising ethylene or propylene, and at least one other alpha olefin of the formula CH.sub.2 .dbd. CHR in which R is alkyl of 1 to 12 carbon atoms and from none to a minor portion of at least one copolymerizable diene, and being sufficiently small dispersed particles vulcanized to the extent that the blend has a tensile strength at least about 60 Kg./sq.cm. greater than that of the unvulcanized blend, the composition being processable in an internal mixer to a product which, upon transferring, with the resin in the molten state, to the rotating rolls of a rubber mill forms an essentially continuous sheet.
The method of preparing useful compositions which comprises blending vulcanized rubber particles essentially of a size of about 50 microns or below, said rubber being a polymer of monomers comprising ethylene or propylene, and at least one other alpha olefin of the formula CH.sub.2 .dbd. CHR in which R is alkyl of 1 to 12 carbon atoms and from none to a minor portion of at least one copolymerizable diene, and molten thermoplastic polyolefin resin which is crystalline in the non-molten state, in amounts sufficient to render the resultant blend elastomeric and processable as a thermoplastic;
- said rubber being further characterized in that the rubber has been vulcanized, prior to blending, to the extent that said resultant blend has a tensile strength at least about 60 Kg./sq.cm. greater than the same blend except the rubber in the blend is unvulcanized, said composition being processable in an internal mixer to a product which, upon transferring, with said resin in the molten state, to the rotating rolls of a rubber mill forms an essentially continuous sheet.
A process of making a thermoplastic filled elastomeric composition which comprises blending
- (a) about 25-75 parts by weight of crystalline thermoplastic polyolefin resin and
- (b) about 75-25 parts by weight of a homogeneous mixture of unvulcanized but vulcanizable monoolefin copolymer rubber and filler at a temperature sufficient to melt said resin, adding vulcanizing ingredients to the blend of (a) and (b) to form a vulcanizable blend,
- then masticating the blend continuously at vulcanization temperature until the rubber, a polymer of monomers comprising ethylene or propylene, and at least one other alpha olefin of the formula CH.sub.2 .dbd. CHR in which R is alkyl of 1 to 12 carbon atoms and from none to a minor portion of at least one copolymerizable diene, is sufficiently small dispersed particles vulcanized to the extent that the blend has a tensile strength at least 60 Kg./sq.cm. greater than that of the unvulcanized blend, said composition being processable in an internal mixer to a product which, upon transferring, with said resin in the molten state, to the rotating rolls of a rubber mill forms an essentially continuous sheet.
A process of making a thermoplastic elastomeric filled composition comprising
- (a) about 25-85 parts by weight of crystalline thermoplastic polyolefin resin,
- (b) about 75-15 parts by weight of monoolefin copolymer rubber per 100 parts total of resin and rubber, and extender oil up to 300 parts by weight per 100 parts by weight of rubber provided that, when the amount of resin is greater than 75 parts by weight, extender oil must be present in an amount sufficient to satisfy the equation (W.sub.o + W.sub.R)/W.sub.P is equal to or greater than 0.33 wherein W.sub.o is the weight of extender oil, W.sub.R is the weight of rubber and W.sub.P is the weight of resin, and
- (c) about 5-300 parts by weight filler per 100 parts total weight of resin and rubber in the final composition
- which comprises blending (a) with a preformed mixture of (b) and (c) and vulcanizing ingredients, at a temperature sufficient to melt said resin,
- then masticating the blend continuously at vulcanization temperature until the rubber, a polymer of monomers comprising ethylene or propylene, and at least one other alpha olefin of the formula CH.sub.2 .dbd. CHR in which R is alkyl of 1 to 12 carbon atoms and from none to a minor portion of at least one copolymerizable diene, is sufficiently small dispersed particles vulcanized to the extent that the blend has a tensile strength at least 60 Kg./sq.cm. greater than that of the unvulcanized blend, said composition being processable in an internal mixer to a product which, upon transferring, with said resin in the molten state, to the rotating rolls of a rubber mill forms an essentially continuous sheet.
A process of making a thermoplastic elastomeric composition which comprises preparing an unvulcanized but vulcanizable composition by blending
- (a) about 25 to about 85 parts by weight of crystalline thermoplastic polyolefin resin,
- (b) about 75 to about 15 parts by weight of monoolefin copolymer rubber per 100 parts total weight of resin and rubber, which rubber is a polymer of monomers comprising ethylene or propylene, and at least one other alpha olefin of the formula CH.sub.2 .dbd. CHR in which R is alkyl of 1-12 carbon atoms and from none to a minor amount of at least one copolymerizable diene,
- (c) one or more vulcanizing ingredients, in an amount sufficient to vulcanize the rubber to the extent that no more three three percent of the rubber is extractable in cyclohexane at 23.degree. C. or that the cross-link density determined on the same monoolefin copolymer rubber as in the composition is greater than about 7 .times. 10.sup.-5 moles per ml of rubber, and
- (d) extender oil up to 300 parts by weight per 100 parts by weight of rubber provided that, when the amount of resin is greater than 75 parts by weight, extender oil must be present in an amount sufficient to satisfy the equation (W.sub.o + W.sub.R)/W.sub.P is equal to or greater than 0.33 wherein W.sub.o is the weight of extender oil, W.sub.R is the weight of rubber and W.sub.P is the weight of resin,
- at a temperature sufficient to soften said resin then masticating the blend continuously at vulcanization temperature until the rubber is small dispersed particles of such size and vulcanized to the extent that the blend has a tensile strength at least 60 Kg./sq.cm. greater than that of the unvulcanized blend, giving a composition processable in an internal mixer to a product which, upon transferring, with the resin in the molten state, to the rotating rolls of a rubber mill forms an essentially continuous sheet.
A thermoplastic elastomeric composition comprising a blend of about 30 to about 70 parts by weight of crystalline polypropylene, about 70 to about 30 parts by weight of vulcanized monoolefin rubber, per 100 parts total weight of said polypropylene and rubber and from about 30 to about 250 parts by weight of extender oil per 100 parts by weight of said rubber, wherein the rubber in said blend is a polymer of ethylene, propylene and a minor proportion of at least one copolymerizable non-conjugated diene and is present in said blend in the form of small dispersed particles essentially of a size of about 50 microns or below and is vulcanized to the extent that the blend has a tensile strength at least about 60 Kg./sq.cm. greater than that of the unvulcanized blend and no more than 3% by weight of the rubber is extractable in cyclohexane at 23.degree. C., the composition being processable in an internal mixer to a product which, upon transferring with the polypropylene in the molten state, to the rotating rolls of a rubber mill forms an essentially continuous elastomeric sheet.
Dependencies are inferred from the claim text.