| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject polyurethane foam capable of maintaining a high communicating property, even when charged in a large amount, by jointly using a specific polyetherpolyol and a urea compound. SOLUTION: This method for producing a rigid polyurethane foam comprises reacting (A) a polyol component having an average hydroxyl group value of 180-450 and a terminal primary hydroxyl group content of <=10% and comprising (n) kinds of polyols different in hydroxyl group values, respectively, and satisfying the inequality [Mi is the molar fraction of a polyol Ai which is the No. i polyol among the polyols [(n) is 2-10] consisting of (n) kinds of the polyols A1 -An ; HLBi is the HLB of the polyol Ai by Griffin method] with (B) a polycyanate in the presence of (C) water, (D) a urea compound (preferably urea), (E) a foam stabilizer and, if necessary, (F) a catalyst. The foam excellent in the communicating property, high in hardness and free from contraction can thereby be obtained by the use of only water as a foaming agent without using a foaming agent such as a fluorocarbon which disrupts the ozonosphere. |
