PRODUCTION OF RIGID POLYURETHANE FOAM

PURPOSE:To produce a rigid polyurethane foam containing fine cells and having excellent filling property, heat-insulation property and low-temperature dimensional stability without causing the ozonosphere destruction by mixing an organic polyisocyanate, a polyol, a specific foaming agent, a catalyst, a surfactant and an assistant. CONSTITUTION:This rigid polyurethane foam containing uniformly distributed fine cells and having excellent physical properties such as heat-insulation property and low-temperature dimensional stability can be produced using a foaming agent free from the ozonosphere destruction problem by compounding an organic polyisocyanate (e.g. diphenylmethane diisocyanate), a polyol (e.g. tolylenediamine- propylene oxide adduct of polyether polyol), 1,3-dioxolan as a foaming agent, a catalyst (e.g. dibutyltin dilaurate), a surfactant and other assistants such as flame-retardant, plasticizer, filler, stabilizer and colorant, quickly stirring and mixing the components and immediately filling in an aluminum box to effect the free expansion of the mixture.