| 摘要 |
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 4-10 times that in case of free expansion: (A) 100pts.wt. polyol mixture of an average OH value of 100-180mgKOH/ g, containing (a) 5-8wt%- <=80mgOH/g, (b) 0-90wt% polymer-polyol other than component (a) and (c) 5-30wt% low-MW polyol of an OH value >=400mg KOH/g in a combined amount of (a) to (c) of 80-100%, (B) 0.1-10pts.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 15-28%, and containing 50-100% prepolymer (NCO content 15- 28%) obtained from diphenyl-methane diisocyanate and a polyol of a functionality of 2-3. |
