BIAXIALLY STRETCHED, MULTI-LAYEREDED POLYAMIDE FILM AND PRODUCTION METHOD THEREOF

摘要

A method of producing a biaxially stretched, multi-layered polyamide film which includes a step of biaxially stretching a non-stretched laminate film composed of a layer mainly made of a polyamide resin and a layer mainly made of an aliphatic polyamide resin. The biaxial stretching is made by a roll/tenter successive biaxial stretching method. The polyamide resin is composed of a diamine constitutional unit mainly made of m-xylylenediamine units and a dicarboxylic acid constitutional unit mainly made of units derived from an .alpha., .omega.-aliphatic dicarboxylic acid having 6 to 12 carbon atoms. The non-stretched laminate film is cooled by a cooling roll having a temperature within a limited range and then successively and biaxially stretched. With such a production method, the biaxially stretched, multi-layered polyamide film is excellent in the gas barrier properties, pinhole resistance, flexibility, and impact resistance.