Thermosetting polyurethane elastomer composition, polyurethane elastomer and method for its production

A polyurethane elastomer obtained by reacting and curing an isocyanate-terminated prepolymer (i) obtained by reacting a polyoxyalkylene polyol (c) having as an oxyalkylene group an oxypropylene group at least 70% by mass, the polyoxyalkylene polyol having an average number of hydroxyl groups of over 2, a total degree of unsaturation of less than 0.05 meq/g and a number-average molecular weight of from 4000 to 20000, with a polyisocyanate compound, and

• a curing agent (ii) comprising as curing components a polyoxytetramethylene polyol (a) and a chain extender (b) having two active-hydrogen-containing groups and having a number-average molecular weight of not more than 500,
• wherein a relation of a hardness (H) by a type A durometer defined by JIS K 6253 and a tensile strength (X) (MPa) defined by JIS K 6251 is represented by X>H/10.

A method for producing a polyurethane elastomer, which comprises reacting and curing an isocyanate-terminated prepolymer (i) obtained by reacting a polyoxyalkylene polyol (c) having as an oxyalkylene group an oxypropylene group at least 70% by mass, the polyoxyalkylene polyol having an average number of hydroxyl groups of over 2, a total degree of unsaturation of less than 0.05 meq/g and a number-average molecular weight of from 4000 to 20000, with a polyisocyanate compound, and

• a curing agent (ii) comprising as curing components a polyoxytetramethylene polyol (a) and a chain extender (b) having two active-hydrogen-containing groups and having a number-average molecular weight of not more than 500,
• wherein a relation of a hardness (H) by a type A durometer defined by JIS K 6253 and a tensile strength (X) (MPa) defined by JIS K 6251, of the resulting polyurethane elastomer is represented by X>H/10.