PURPOSE: To keep a highly evacuated degree of a vacuum heat-insulating layer for a long time and make light, by doing a baking treatment of a metallic inner vessel in a specified vacuum condition and simultaneously heating a synthetic resin outer vessel by utilizing the radiant heat.
CONSTITUTION: A synthetic resin made outer vessel 2 forming a thin metallic film on it is unified with a metal inner vessel 3. After the heat-insulating space layer 10 defined by the vessels is evacuated to a higher vacuum degree than 10-5Torr, and it is sealed. The vacuum degree after evacuation from the heat- insulating layer 10 can be easily and securely kept by using synthetic resin having the evacuation volume as large as 1000-10000 times than metals in the vacuum condition, only for the outer vessel 2. It is light because no powder is used in the heat-insulating layer 10. And also the baking treatment is easily and rapidly applied. A limited position on the bottom of the metallic inner vessel 3 where an absorber 5 is fixed can be selectively heated without thermal effects on the synthetic resin outer vessel 2. Accordingly, activation of the absorber 5 can be sufficiently carried out at a high activation temperature. And there is no effect on the adhesive of the opening 8 and wax having a low melting point.
YAMADA MASASHI
KOMIYA YASUHIKO
