Containers for food service

A container for food service capable of withstanding heating in a microwave oven comprising a bottom wall portion and a peripheral side wall portion, said bottom portion having an upwardly arcuate configuration in cross section and being connected to said side portion, there being a leg-like portion defined by the bottom portion which joins the peripheral side wall portion, said container being formed of a laminated sheet comprising at least one foamed layer of polystyrene and at least one layer of crystallized polyethylene terephthalate film, said polyethylene terephthalate film being laminated on said foamed sheet on the surface of said foamed sheet which forms the interior of said container, the polyetylene terephthalate film being formed from non-stretched polyethylene terephthalate film, said polyethylene terephthalate film having a crystal structure formed during a crystallization period, with said crystal structure having substantially the same characteristics as that of a non-stretched polyethylene terephthalate film in a polyethylene terephthalate film/polystyrene lamination having been subjected to a low temperature, non-crystallization container forming process and subsequent heat treatment at more than 110.degree. C.