| 摘要 |
PURPOSE:To obtain a low-density flexible polyurethane foam without detriment to the physical properties of the foam by using a specific polyisocyanate mixture in producing the foam using water as a sole blowing agent. CONSTITUTION:In producing a flexible polyurethane foam by reacting a mixture of an active hydrogen compd., a blowing agent, and other additives with an org. polyisocyanate compd., water is used as the blowing agent and a polyisocyanate mixture comprising an NCO-terminated prepolymer contg. 10-45wt.% NCO and obtd. by reacting a polyester polyol having an average mol.wt. of 500-10000 with tolylene diisocyanate (A), diphenylmethane diisocyanate contg. 5-60wt.% mixture of 2,2'- and 2,4'-isomer or an NCO-terminated prepolymer obtd. by reacting this diisocyanate with a polyether polyol having an average mol.wt. of 500-30000 (B), and a polyphenylmethane polyisocyanate contg. 25-65wt.% diphenylmethane diisocyanate contg. 0.5-20wt.% mixture of 2,2'- and 2,4'-isomer (c) in a wt. ratio of A/B/C of (1:10:89) to (20:70:10) is used as the org. polyisocyanate compd. |
