PURPOSE: To obtain a packaged material having improved gas permeation resistance, by packing a container having an interlayer formed of a specific ethylene-vinyl alcohol copolymer with a content, and heat-treating the resultant packed container under specific conditions.
CONSTITUTION: A container is molded by using ethylene-vinyl alcohol copolymer, containing 50W75mol% vinyl alcohol and 50W25mol% ethylene, and having ≥96% saponification degree of vinyl ester or a blend thereof with a thermoplastic polymer as an interlayer, and a low water absorbing thermoplastic polymer as an inner layer and an outer layer. A content is then packed in the resultant container and heat sterilized. The heat sterilization conditions are such that the differential thermal analysis curve has a main endothermic peak temperature Y1(°C) and secondary endothermic peak temperature Y2(°C) satisfying the formulas I and II [X is vinyl alcohol content (mol%)] and ≥0.025 ratio between the area (Y2) and the area (Y1) in the treated ethylene-vinyl alcohol copolymer.
HIRATA SADAO
KISHIMOTO AKIRA
HIRATA SHIYUNSAKU
SUZUKI TOORU
KANOU TOMIO
| JP46021941A | ||||
| JPS55142034A | 1980-11-06 |