| 摘要 |
A method of producing rigid polyurethane foam by reacting a polyisocyanate with a polyol in the presence of a catalyst, a blowing agent and a foam stabilizer according to the present invention is characterized by using as the polyol a mixture comprising: (a) a tolylenediamine polyol having four functional groups and a hydroxyl value of 350 to 500, (b) an aromatic polyester polyol having 2.2 to 3.6 functional groups on the average and a hydroxyl value of 200 to 550, (c) a sugar polyol having eight functional groups and a hydroxyl value of 350 to 480, and (d) glycerol, trimethylolpropane or a triethanolamine polyol each having three functional groups and a hydroxyl value of 400 to 700, wherein the sum of polyols (a) and (b) is 65 to 75 % by weight, said polyol (a) being at least 30 % by weight and said polyol (b) being at least 15 % by weight, and the sum of polyols (c) and (d) is 35 to 25 % by weight, said polyol (c) being at least 15 % by weight and said polyol (d) being at least 10 % by weight. |
