Abstract: A rubber composition having excellent adhesion to steel cords comprising:(a) 100 parts by weight of at least one rubber selected from the group consisting of natural rubber, synthetic rubber and a blend thereof;(b) from about 0.01 to 1 part by weight of elemental cobalt contained in at least one cobalt oxyketone complex represented by formulae (I) or (II): ##STR1## wherein X.sub.1 -X.sub.4 and Y.sub.1 -Y.sub.10 are as defined in the specification; and(c) from about 0.2 to 10 parts by weight of a bismaleimide compound represented by formula (III): ##STR2## wherein Z represents a hydrocarbon group containing 2 to 10 carbon atoms. The rubber composition has excellent adhesion to steel cord, excellent thermoresistability, and is suitable for use in tire, belt, hose and vibration insulating rubber.

Abstract: A rubber-cord composite body used for cord reinforcing rubber articles is produced by embedding fiber cords treated with an epoxy compound and further with a particular resorcin-formaldehyde-rubber latex adhesive into a particular rubber composition containing 0.5.about.10 parts by weight of each of a bismaleimide compound and sulfur.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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<d<1.2.