CORE MATERIAL FOR THERMAL INSULATING MATERIAL AND ITS PREPARATION AND VACUUM THERMAL INSULATING MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a vacuum thermal insulating material that is free from environmental problem such as waste treatment and does not suffer deterioration of performance even in use for a long time. SOLUTION: A top chamber 6 on which a top jig 4 is fitted is set on a bottom chamber 7 on which a bottom jig 5 is fitted in such a way that an outer skin material 2 comprising a kraft paper and with gas permeability in which a foamable urethane raw material is cast is stored in the top jig 4 and the bottom jig. A hermetic space 9 even formed between the top chamber 6 and the bottom chamber 7 and the hermetic chamber 9 is connected with a vacuum pump 10 through a pipe 12. In addition, the inside of the hermetic space 9 is evacuated by suction force of the vacuum pump and both jigs 4 and 5 are held at a specified temp. or higher by means of heaters 8 provided above the top jig 4 and below the bottom jig 5. A urethane foam with an open-cell structure with less remaining parts of closed cells is obtd. by action of vacuum and heating when it is foamed.