| 摘要 |
PURPOSE:To obtain a low-density rigid urethane foam having improved adhesiveness even when a large amount of water is used while markedly reducing the amount of a fluorohydrocarbon used by reacting a polyol mixture having a specified constitution with a polyisocyanate by using water as a blowing agent. CONSTITUTION:A polyol mixture comprising a polyol of a hydroxyl value of 300-450mgKOH/g prepared by using a 5-6C chain sugar alcohol as an initiator and another polyol and having a sugar alcohol content of 3-14wt.% and an average hydroxyl value of 300-430mgKOH/g is reacted with a polyisocyanate by using 4.0-7.0 pts.wt., per 100 pts.wt. total polyol component, water. A particularly desirable example of the another polyol in the above polyol mixture is a polyol of a hydroxyl value of 330-460mgKOH/g prepared by using tolylenediamine as an initiator, and its amount of use is desirably at most 8wt.% (in terms of tolylenediamine) based on the total polyol. |
