| 摘要 |
The invention relates to a metal sheet bearing a single layer of hydrated chromium oxide or a double layer consisting of an upper layer of hydrated chromium oxide and a lower layer of metallic chromium, this metal sheet being laminated with a film of polyester resin consisting of from approximately 10 to approximately 60% by weight of a butylene terephthalate polymer and approximately 40 to 90% by weight of an ethylene terephthalate polymer. The production process comprises adjusting the ratio of the densities and of the residual degree of biaxial orientation of the film into the optimum range before treatment in an autoclave. Application: production of metallic boxes suitable for autoclaving, exhibiting excellent resistance to the appearance of milky spots (stains) during the autoclaving treatment, after packaging of foodstuffs.
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