| 摘要 |
PROBLEM TO BE SOLVED: To provide a rigid (isocyanurate-modified) polyurethane foam which is produced by using a polyester polyol compound which is obtained by the esterification of phthalic acid or a phthalic acid derivative; as a polyol component and a hydrofluorocarbon(HFC) as the foaming agent; is flame-retardant; has no problem or ozonosphere destruction; has no problem of the increasing inner pressure of a mixing solution to foam as described below; and has a density decreased by mixing a relatively large amount of HFC. SOLUTION: The rigid polyurethane foam can be produced by mixing the polyisocyanate component, the polyol component, the foaming agent, a catalyst and the other auxiliaries to foam, wherein said polyol component includes the polyester polyol compound synthesized by the esterification of phthalic acid and/or a phthalic acid derivative and said foaming agent contains two or more HFCs including 1,1,1,3,3-pentafluorobutane.
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