Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-10-08
2004-12-07
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S233000, C525S244000, C525S294000, C525S301000, C525S262000, C525S329100, C525S329300, C525S338000, C525S339000, C525S340000
Reexamination Certificate
active
06828385
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel crosslinked polymers, to processes for preparing the novel crosslinked polymers and to uses thereof.
BACKGROUND OF THE INVENTION
Polymers of conjugated dienes and unsaturated nitriles, i.e. nitrile rubbers are known. It is also known to hydrogenate these. This improves the heat-aging properties of the polymer. When doing so care is needed to ensure that only hydrogenation of carbon-carbon double bonds occurs. Hydrogenation of the nitrile moieties is to be avoided, as any reduction of the nitrile groups has an undesired and deleterious effect on the properties of the nitrile rubber; in particular it reduces the oil resistance of the nitrile rubber.
It has been proposed to include various additional copolymerizable monomers in nitrile rubbers. Among the copolymerizable monomers mentioned are alpha,beta-unsaturated mono- and dicarboxylic acids. These can be incorporated into the polymer backbone, but difficulty has been encountered when polymers containing carboxyl groups are hydrogenated. Particularly if the degree of hydrogenation is high, the carboxyl groups have undergone reduction or other side reactions, which has resulted in an unsatisfactory product.
To avoid the problem of hydrogenation of the carboxyl groups it has been proposed to prepare a nitrile rubber composed of a conjugated diene and an unsaturated nitrile, to partially hydrogenate this nitrile rubber and thereafter to add alpha,beta-unsaturated acid; see U.S. Pat. No. 5,157,083. This approach has not proven satisfactory. As the acid is added after the formation of the nitrile rubber, the acid moieties are not distributed randomly or alternately along the backbone of the polymer. Terpolymerization of a conjugated diene, unsaturated nitrile and unsaturated acid results in a polymer in which the &agr; and &bgr; carbon atoms of the acid form part of the main carbon backbone of the polymer. In contrast, polymerization of conjugated diene and nitrile results in a polymer that has some carbon-carbon double bonds in a vinyl side chain, from 1,2-polymeriztion of butadiene, and some carbon-carbon double bonds in the main polymer backbone, from 1,4-polymerization of butadiene. These double bonds in the main polymer backbone may be in the cis or in the trans configuration. When the polymer undergoes hydrogenation, the vinyl groups undergo hydrogenation first, followed by the double bonds in the cis configuration. Therefore, the partially hydrogenated polymer to which the &agr;,&bgr;-unsaturated acid is added contains mostly or entirely double bonds in the main polymer backbone and in the trans configuration. Reaction with the unsaturated acid results in a product in which the &agr; and &bgr; carbon atoms of the acid are not in the main carbon backbone of the polymer. Accordingly, the chemical structure of a polymer made in this latter way differs from the chemical structure of the statistical polymers that is formed by the terpolymerization of a conjugated diene, an unsaturated nitrile and an unsaturated acid, where the monomers are statistically or randomly distributed throughout the polymer chain.
European Patent Application No. 933381 discloses carboxylated nitrile-group-containing highly saturated copolymer rubber, and discusses three processes for adding maleic anhydride to a nitrile-group-containing highly saturated copolymer rubber. The European application refers to “a highly saturated copolymer rubber”, but it is believed that some degree of unsaturation in the rubber is required, to serve as reaction sites for addition of the maleic anhydride. Disadvantages of all three processes for adding maleic anhydride are mentioned, and it is disclosed that no satisfactory industrial process has been found. Furthermore, the product of the addition, i.e., the maleic anhydride-nitrile-group-containing polymer is said to be unsatisfactory in various properties, including “abrasion resistance and tensile strength which are required for belts and hoses.”
Preparing a carboxylated, hydrogenated nitrile rubber by first preparing a nitrile rubber, then hydrogenating and thereafter adding an unsaturated acid results in an expensive production process. Furthermore, it is difficult to control the amount of acid that adds to the polymer so the quality of the product is uncertain. A product made in this way was introduced commercially but has since been withdrawn from the market.
The reactive sites of hydrogenated nitrile rubber are the double bonds. Japanese Patent JP 08035562 A2 (Chemical Abstracts 1996:265058) addresses the uses of polycarbodiimide pulp and hydrogenated nitrile rubbers reactive to a carbodiimide group. The reaction occurs between the polymer's double bonds and not a carboxylic acid monomer.
Carbodiimides are disclosed as a curative in thermoplastic blends of polyester, polycarbonates and the like in the presence of nitrile rubbers in WO 99/29773-A1. The thermoplastic blend exhibits no rubbery properties present in this invention.
SUMMARY OF THE INVENTION
A process has now been discovered that permits the simultaneous crosslinking and derivation of an, optionally hydrogenated, polymer whose backbone contains units derived from at least one conjugated diene monomer, units derived from at least one unsaturated nitrile monomer and units derived from at least one unsaturated carboxylic acid monomer in the presence of a coupling/condensing agent. This permits the preparation of a novel polymeric material that is an, optionally hydrogenated, polymer containing units derived from at least one conjugated diene monomer, units derived from at least one unsaturated nitrile monomer and units derived from at least one derived unsaturated acid monomer. It has also been found that this novel polymeric material has unexpected and valuable properties.
Accordingly, in one aspect, the present invention provides an, optionally hydrogenated, polymer containing units derived from at least one conjugated diene monomer, units derived from at least one unsaturated nitrile monomer and units derived from at least one derivatized unsaturated acid monomer.
In another aspect, the present invention provides a process for the simultaneous crosslinking and derivation of an, optionally hydrogenated, polymer comprising units derived from at least one conjugated diene monomer, units derived from at least one unsaturated nitrile monomer and units derived from at least one derived unsaturated acid monomer which includes subjecting the polymer to a crosslinking process in the presence of at least one coupling/condensing agent.
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patent: 5157083 (1992-10-01), Aonuma et al.
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Chemical Abstracts 1996:265058 & JP 08035562.
Kautschuk + Gummi Kunststoffe, vol. 42, (month unavailable) 1989, D. Brück, pp. 107-110, “IR-Spectrometric Determination of the Proportions of Acrylonitrile, Butadiene and Hydrogenated Butadiene in Hydrogenated Acrylonitrile-Butadiene Rubbers” (Part 1).
Kautschuk + Gummi Kunststoffe, vol. 42, (month unavailable) 1989, D. Brück, pp. 194-197, IR-Spectrometric Determination of the Proportions of Acrylonitrile, Butadiene and Hydrogenated Butadiene in Hydrogenated Acrylonitrile-Butadiene Rubbers (HNBR) (Part 2).
Organic Chemistry, (month unavailable) 1987, K. Peter C. Vollhardt, pp. 747-789.
Elastomers & Rubber Compounding Materials, (month unavailable) 1989, I. Franta et al, pp. 325-494, “Compounding materials and special purpose additives”.
Gamlin Janet N.
Guo Sharon X.
Akorli Godfried R.
Asinovsky Olga
Bayer Inc.
Seidleck James J.
Senk Jennifer R.
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