PURPOSE: To maintain good thermal conductivity of expanded insulating material for a long period of time by bonding a film to the surface of expanded insulating material to be put into the gap between an outer box and an inner box to prevent fluorocarbon component etc., in the material from being replaced by air.
CONSTITUTION: A thermally insulated box such as a refrigerator comprises an outer box 1 of matal, an inner box 2 of plastics, and expanded insulating material 3 such as slab-shaped urethane foam incorporated into the gap between the boxes 1, 2. In a thermally insulated box of this sort, a film having low permeability to gas such as air, and moisture is bonded to the surface of the material 3. As a result, fluorocarbon component etc., in the material 3 is prevented from being replaced by the air and hence thermal conductivity of the material 3 is not deteriorated even after extended use.
SASAKI TAKAO
YOSHINO SHOJI
