Packaging bag

Abstract

A packaging bag including a polyester-based multilayer film. The multilayer film includes at least: an innermost layer formed of a biaxially stretched polyethylene terephthalate film; a layer formed of polybutylene terephthalate; and/or a layer formed of a blend of polyethylene terephthalate and polybutylene terephthalate. The biaxially stretched polyethylene terephthalate film has a heat sealing portion that is amorphized or low-crystallized by laser light irradiation. The packaging bag is formed by allowing the innermost layers of the polyester-based multilayer film to be opposed to and superimposed on each other, and heat sealing the heat sealing portions.

Dependencies are inferred from the claim text.