| 摘要 |
PURPOSE:To improve heat insulating property and adhesive property by a method wherein at least three kinds of polyether polyol initiators having different molecular weights and different numbers of functional group are employed while a predetermined mixture is used as foaming agent. CONSTITUTION:A gap between an outer casing and an inner casing is filled with hard polyurethane foam formed by reacting polyol and isocyanate under the existence of a foaming agent. In this case, the initiator of polyol is the mixture. of 20-70 pts.wt. of aliphatic initiator having average functional groups of 2-4, 15-60 pts.wt. of initiator having average number of functional groups 3-5 and 65 pts.wt. of aliphatic amin initiator having 3-5 average functional groups. A predetermined polyol, obtained by adding the mixture with alkylene oxide, is employed. The mixture of monochlorodifluoromethane, 1-chloro-1, and 1-difluoroethane is employed as a foaming agent while foaming molding is effected by setting the mixing ratio of the same within a predetermined range whereby the heat insulating box body can be obtained. |
