Bridgestone Tire Company Limited

Japan Synthetic Rubber Co., Ltd.

Yutaka Iseda

Yoji Watabe

Michio Ishii

Tsutomu Matsunaga

Shiro Anzai

Noboru Ohshima

Yoshio Kaneko

Fumio Odaka

Yoshihiko Fujii

Yozo Nakata, Deceased

Shigeyuki Toki

Takeshi Kimura

Kouei Komatsu

A polyurethane composition is produced by mixing (a) 100 parts by weight of prepolymer having terminal isocyanate groups and having a number average molecular weight in the range of from 800 to 20,000, (b) 5 - 30 parts by weight of a radical polymerizable vinyl compound, and (c) 0.05 - 1.0 part by weight of a radical initiator, adding (d) a curative selected from the group consisting of polyamine and polyol, and curing the resulting mixture by heating at 70 - 140.degree. C, the equivalent ratio of the active hydrogen of (d) to the isocyanate groups of (a) being in the range of from 0.8 to 1.2.

Polyurethane composition

A polyurethane composition having high tear strength has been produced by mixing homogeneously 20 to 50 parts by weight of finely divided acidic silica particles, 100 parts by weight of isocyanate-terminated prepolymer and appropriate parts of curative, and curing the mixture in a manner well known in the prior art, where the ratio (l/d) of average chain distance (l) between adjacent crosslinking points of the cured polyurethane chains to average size (d) of finely divided silica particles is in the range of from 2.5 to 20.

Polyurethane composition having improved tear strength and process for

Polydiene polyurethanes having high tear strength are obtained by using polydiene glycols, prepared with use of lithium-based catalyst, having a number average molecular weight of 1,000 to 5,000 and functionality of 1.8 - 2.1, diisocyanates and chain-extending agents, and by controlling chemical cross-link density being 4 .times. 10.sup.-5 mole/cc and less. When the chemical cross-link density is within the above range, elongation and tensile strength in addition to tear strength of the polyurethane are improved significantly. Furthermore, when 10 - 50 parts by weight of the specified carbon black are added to 100 parts by weight of the mixture of the prepolymer, the chain-extending agent and the additive prior to curing the prepolymer, these mechanical properties of the polyurethane are improved further.

Process for preparing high tear-strength polydiene polyurethane

Reinforced rubber composites having high Young's modulus and tear energy and a highly improved creep strength are produced by melt-blending 100 parts by weight of a natural or synthetic rubber, 5-150 parts by weight of N-methoxymethylated nylon (degree of N-methoxymethylation: 10-40 mol%) in the presence of or in the absence of a filler and an antioxidant in Banbury mixer, mixing thereto 5-20 parts by weight based on 100 parts of said nylon, of a higher saturated aliphatic monobasic organic acid which is a cross-linking agent for N-methoxymethylated nylon, 0.5-20 parts by weight based on 100 parts of the rubber, of a cross-linking agent for rubber and an appropriate amount of compounding agents and simultaneously cross-linking the rubber and the N-methoxymethylated nylon.

Rubber with organic acid and methoxy methyl nylon, sulfur vulcanized

Polyether urethane elastomer composition having improved mechanical properties has been prepared by using polyfunctional isocyanate, curing agent and polyether having active hydrogen terminal groups, wherein the weight average molecular weight of said polyether is within the range of 1,000 to less than 4,500 and the molecular weight distribution curve of said polyether has at least two peaks, at least one of which is located in the higher molecular weight region and at least another one of which is located in the lower molecular weight region than the rheological critical molecular weight of said polyether and wherein the equivalent ratio (d) of active hydrogen of a curing agent to the isocyanate group of said polyfunctional isocyanate is in the range of 0.9&lt;d&lt;1.2.

Urethane elastomers prepared from polyethers having a certain molecular

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Tachikawa, Japan

Yutaka Iseda