Heat-sealed closure for polyester container and container having said closure

A closure for heat-sealing a container, at least a portion to be heat-sealed of which is formed of a resin containing a thermoplastic polyester as a main component, said heat-sealable closure comprising a laminate of

• (1) a heat-sealable layer containing as a main component a copolymerized polyester resin having a softening temperature of at least 120.degree. C. and a glass transition temperature of 30.degree. to 85.degree. C.,
• (2) a metal substrate, and
• (3) an epoxy-phenol resin primer layer interposed between the heat-sealable layer (1) and the metal substrate (2), wherein the weight ratio of the epoxy resin to the phenolic resin ranges from 35:65 to 95:5, wherein the phenol component of the phenolic resin has a functionality index (F.I.), represented by the following formula, of from 1.6 to 2.8:
• F.I.=2M.sub.2 +3M.sub.3 +4M.sub.4
• wherein
• M.sub.2 represents the number of moles of a difunctional monohydric phenol per 100 g of the entire phenol components,
• M.sub.3 represents the number of moles of a trifunctional monohydric phenol per 100 g of the entire phenol components, and
• M.sub.4 represents the number of moles of a poly-nuclear dihydric phenol per 100 g of the entire phenol components, and
• wherein the epoxy resin is a condensation product between a bisphenol and an epihydrin and has an epoxy equivalent of 600 to 6000, wherein said laminate is prepared by coating the metal substrate with said epoxy-phenol resin primer, drying or half-curing the coated primer layer, applying the copolymerized polyester onto the surface of the coated primer layer, and melting the copolymerized polyester and simultaneously curing the coated primer layer.