| 摘要 |
PURPOSE:To obtain the biaxially oriented film of saponified ethylene-vinylacetate copolymer, excellent in mechanical property as well as gas barrier property and suitable for packing of food, medicine or the like, by a method wherein a specified unoriented film is oriented into longitudinal and transversal directions under specified conditions respectively and is fixed by heat. CONSTITUTION:The unoriented film, consisting of saponified ethylene-vinylacetate copolymer containing 35-45mol% of ethylene and having saponification degree of 98% or more, amorphous substantially and containing no water substantially, is heated within the temperature range of 50-65 deg.C and is oriented into longitudinal direction with the draw ratio of 2.5-3.5 times by a roll-type longitudinally orienting machine in first process. The film, oriented into the longitudinal direction thereof in the first process, is oriented into the transversal direction thereof by a tenter type transversally orienting machine within the temperature range of 70-95 deg.C with the draw ratio of 2.7-4.0 times in second process. The film, oriented transversally in the second process, is fixed by heat within the temperature range, whose lower limit is 110 deg.C and upper limit is a temperature lower than the melting point of material resin by 5 deg.C, in third process.
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