PURPOSE: To maintain good thermal conductivity of expanded insulating material for a long period of time by applying coating material onto the surfaces of expanded insulating materials to be put into the gap between an outer box and an inner box to prevent fluorocarbon component etc., in the insulating 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 materials 3 such as slab-shaped urethane foams incorporated into the gap between the boxes 1, 2. In an insulated box of this sort, coating material having low permeability to gas such as air, moisture etc., is applied onto the surfaces of the materials 3. As a result, fluorocarbon component etc., in the material 3 is not replaced by the air and hence thermal conductivity of the material 3 is not deteriorated even after extended use.
SASAKI TAKAO
YOSHINO SHOJI
