Abstract: Tire filling material having high resilience produced by curing a mixture of(a) a polyoxypropylene polyol having an OH equivalent molecular weight of 900-1,800 and a functionality of 2-4,(b) a polyisocyanate, and(c) a plasticizerin the presence of a catalyst where the equivalent ratio (NCO/OH) of isocyanate groups in component (b) to hydroxyl groups in component (a) is from 0.8-2.0 and the amount of component (c) is 10-200 parts by weight per 100 parts by weight of component (a).

Abstract: A soft polyurethane elastomer containing isocyanurate ring prepared by reacting polyoxypropylene polyol having an OH equivalent molecular weight of about 500-3,000, and a functionality of about 2-5, and polyisocyanate compound in the presence of tertiary amine catalyst, and if desired further combined with organic tin catalyst. This process is advantageous in facilitation of material control during curing reaction, low exothermicity and high thermal stability of the resulting polymer. Further the properties of the polymer are improved by using ethyleneoxide addition polyoxypropylene polyol instead of the above polymer and a specific tertiary amine as a catalyst. The elastomer thus prepared is significantly suitable for tire filling material.