Heat insulating body

A heat insulating body comprising a rigid polyurethane foam of open cell structure formed by foaming a mixture comprising an organic polyisocyanate, a polyol, a catalyst, a foam stabilizer, a blowing agent, and as a cell-interconnecting agent, 0.1 to 5.0 parts by weight of a powdery divalent metal salt of a saturated monocarboxylic acid, the organic polyisocyanate used in forming the rigid polyurethane foam being a purified diphenylmethane diisocyante, a modified product of purified diphenylmethane diisocyanate, and a prepolymerized purified tolylene diisocyanate obtained by the preliminary reaction of purified tolylene diisocyanate and polyol, used each alone or as a mixture thereof, and has an amine equivalent of 120 to 180, and the polyol used in forming the rigid polyurethane foam being a polyol containing 70% by weight or more of a polyether polyol having a hydroxyl value of 300 to 550 mg KOH/g obtained by the addition polymerization of an alkylene oxide to an aromatic diamine, and a vessel formed of metal-plastics laminate film enveloping said rigid polyurethane foam, the whole system being evaucated to reduce the internal pressure and then hermetically sealed.