PURPOSE: To produce the titled ball which suffers little cracking, deformation, and surface abrasion even after repeated use, by expansion-molding a specified polyol and isocyanate component together with water and a non-reactive blowing agent.
CONSTITUTION: The following components are expansion-molded so that the specific gravity of the product may be 4W10 times that in case of free expansion: (A) 100pts.wt. polyol mixture of an average OH value of 100W180mgKOH/ g, containing (a) 5W8wt%W ≤80mgOH/g, (b) 0W90wt% polymer-polyol other than component (a) and (c) 5W30wt% low-MW polyol of an OH value ≥400mg KOH/g in a combined amount of (a) to (c) of 80W100%, (B) 0.1W10pts.wt. water, (C) a non-reactive blowing agent which evolves gas by the heat of reaction, and (D) an isocyanate component having an average NCO%, per total isocyanate component, of 15W28%, and containing 50W100% prepolymer (NCO content 15W 28%) obtained from diphenyl-methane diisocyanate and a polyol of a functionality of 2W3.
SATAKE SEIJI
MASUJIMA IWAO
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