| 摘要 |
PROBLEM TO BE SOLVED: To maintain fixed oxygen permeability rate and moisture permeability just before using by forming an outer bag covering member arranging an extendable polypropylene film including petroleum resin on both sides of a poly vinyl alcohol film or an ethylene-vinyl acetate copolymer saponification film. SOLUTION: A ventilable inner bag containing calorific composition for heating by contacting with oxygen in air is tightly sealed in an unventilable outer bag formed of a covering member sticking plural films to form a calorific bag. Either a poly vinyl alcohol(PVA) film or an ethylene vinyl acetate copolymer saponification (EVOH) film 6 is disposed to one layer in middle layers in an outer bag covering member. Normally, at least one layer of an extendable polypropylene film 7 including petroleum resin is disposed at both sides of the middle layer film, preferably at one layer between the middle layer film 6 and a surface layer 8, and at one layer between the middle layer film 6 and a back layer 9.
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