US 4,735,835 AGranted

Seam covered welded can

AssigneeToyo Seikan Kaisha, Ltd.

InventorsKazuo Taira, Sachiko Ishikawa, Hisakazu Yasumuro, Kenji Matsuno, Hiroshi Matsubayashi

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Abstract

Disclosed is a welded can having at least the inner face side of a weld seam covered with a composite film of a thermoplastic resin, wherein the thermoplastic resin composite film comprises (I) an innermost layer, located on the inner face side of the can, of a thermoplastic polyester having a molecularly oriented crystal and comprising a dibasic acid component content of at least 90 mole % of terephthalic acid and a diol component containing at least 90 mole % of ethylene glycol, said innermost layer (I) overlayer (II) a seam-contacting layer, located on the seam side, of a thermoplastic copolyester containing in the chain molecule a dibasic acid component containing 40 to 95 mole % of terephthalic acid and 0 to 40 mole % of isophthalic acid and a diol component containing ethylene glycol and butane diol in a total amount of 65 to 100 mole % at a molar ratio of from 5/95 and 80/20 or a blend of such copolyesters, and the composite film comprising the layers (I) and (II) has an elasticity modulus of 5 to 220 kg/mm.sup.2 at a temperature lower by 20.degree. C. than the softening temperature of the resin of the layer (II).

Claims17

Dependent claims

A welded can with at least the inner surface of the weld seam having a composite film covering comprising a first layer (II) contacting the seam of a thermoplastic copolyester comprising a dibasic acid component composed of 40 to 95 mole % of terephthalic acid and 5 to 60 mole % of a dibasic acid other than terephthalic acid, with the proviso that isophthalic acid is present in an amount of 0 to 40 mole % based on the dibasic acid component, and a diol component composed of 65 to 100 mole % of ethylene glycol and butane diol and 0 to 35 mole % of a diol other than ethylene glycol and butane diol, said ethylene glycol and butane diol being present at molar ratio of from 5/95 to 80/20, or a blend of such copolyesters, and an overlying second layer (I) which is the innermost layer on the can, comprising a thermoplastic polyester having a molecularly oriented crystal and comprising a dibasic acid component composed of 90 to 100 mole % of terephthalic acid and 0 to 10 mole % of a dibasic acid other than terephthalic acid and a diol component composed of 90 to 100 mole % of ethylene glycol and 0 to 10 mole % of a diol other than ethylene glycol, said composite film covering having an elasticity modulus of 5 to 220 kg/mm.sup.2 at a temperature lower by than 20.degree. C. than the softening temperature of the resin of the first layer (II).

Dependencies are inferred from the claim text.