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AssigneeToyo Seikan Kaisha, Ltd.
InventorsMuneki Yamada, Sadao Hirata, Akira Kishimoto, Shunsaku Hirata, Toru Suzuki, Fumio Kano
Estimating the term…
A packaging material having an improved gas permeation resistance, which comprises at least one layer composed of (A) an ethylene-vinyl alcohol copolymer having a vinyl alcohol content of 50 to 75 mole % and a residual vinyl ester content of up to 4 mole % based on the sum of the vinyl alcohol and vinyl ester or (B) a blend of said ethylene-vinyl alcohol copolymer with up to 150% by weight, based on said copolymer, of at least one thermoplastic polymer other than said copolymer, said ethylenevinyl alcohol copolymer having a main endothermic peak satisfying substantially the following requirement: Y.sub.1 = 1.64X + 68.0 wherein Y.sub.1 stands for the main endothermic peak temperature (.degree. C.) in the differential thermal analysis, and X stands for the vinyl alcohol content (mole %) in the ethylene-vinyl alcohol copolymer, And at least one subsidary endothermic peak satisfying substantially the following requirement: 0.67 X + 76.7 .gtoreq. Y.sub.2 .gtoreq. 0.40 X + 40.0 preferably 0.67 X + 76.7 .gtoreq. Y.sub.2 .gtoreq. 0.34 X + 88.0 wherein Y.sub.2 stands for the subsidary endothermic peak temperature (.degree. C.) in the differential thermal analysis, and X is as defined above, The ratio (Rs) of the subsidary endothermic peak area to the main endothermic peak area being at least 2.5%.
A packaging material having an improved gas permeation resistance, which comprises at least one layer composed of (A) an ethylene-vinyl alcohol copolymer having a vinyl alcohol content of 50 to 75 mole % and a residual vinyl ester content of up to 4 mole % based on the sum of the vinyl alcohol and vinyl ester or (B) a blend of said ethylene-vinyl alcohol copolymer with 25 to 150% by weight, based on said copolymer, of at least one thermoplastic polymer selected from the group consisting of polyolefins and carbonyl group-containing polymers, said ethylene-vinyl alcohol copolymer having a main endothermic peak satisfying substantially the following requirement:
A process for the preparation of packaging materials which comprises the steps of (1) forming a molded structure comprising at least one layer composed of (A) an ethylene-vinyl alcohol copolymer having a vinyl alcohol content of 50 to 75 mole % and a residual vinyl ester content of up to 4 mole % based on the sum of the vinyl alcohol and vinyl ester or (B) a blend of said copolymer with 25 to 150% by weight, based on said copolymer, of at least one thermoplastic polymer selected from the group consisting of polyolefins and carbonyl group-containing polymers, and (2) maintaining the so formed structure under temperature and time conditions satisfying the following requirements:
Dependencies are inferred from the claim text.