FILM FOR RETORT PACKING MATERIAL

PURPOSE:To obtain a colorless transparent film for a retort packing material excellent in gas barrier properties and enhanced in heat resistance, strength and flexibility by laminating the first film wherein an SiOx layer and an SiO2 film are successively laminated to the single surface of a base material composed of a flexible plastic film and the second film composed of a flexible plastic film through an adhesive layer. CONSTITUTION:As a raw material for forming a membrane layer, one having high vapor pressure is pref. and SiO is suitable. Next, in order to form the SiOx layer 2 mixed with the structure of a base material, energy of several ten-several hundred eV is applied to film forming particles in an oxygen free atmosphere. Further, when an SiO2 film 1 is formed on the SiO2 layer 2 by vacuum vapor deposition using SiO as a raw material, O2 gas is usually introduced into the atmosphere in order to enhance the degree of oxidation. As the adhesive for laminating the first and second films, an aliphatic urethane adhesive hard to change in its hue and enhancing weatherability is proper. An adhesive layer 4 is formed by applying this adhesive to the first or second film and superposing two films one upon another to cure the adhesive under heating.