Abstract: A laminate for forming a packaging bag including a substrate layer containing a crystalline polyester film, an adhesive layer, and a sealant layer containing the polyester film arranged in this order. The sealant layer has a ratio of a fracture elongation thereof to a thickness thereof which is 13%/um or less. The fracture elongation is a fracture elongation of the sealant layer as measured in a unit of 15mm width thereof in an MD direction.

Abstract: A laminate for forming a packaging bag, in sequence: a substrate layer; an adhesive layer; and a sealant layer, wherein the sealant layer includes a first polyester film having a crystallinity of 20 to 50% based on a first absorbance at a first wavenumber of 1409 cm?1, a second absorbance at a second wavenumber of 1370 cm?1, a third absorbance at a third wavenumber of 1340 cm?1, a first constant, and a second constant, the first to third absorbances and the first and second constants being determined based on FT-IR analysis, which uses a reflection method, on at least the first polyester film, the crystallinity of the first polyester film being expressed in accordance with the following formulas (1) and (2): I1409=p1×I1340+p2×I1370 . . . (Formula 1) and C=p1×(I1340/I1409)×100 . . . (Formula 2).

Abstract: The present disclosure relates to a method for selecting a polyester film in which the polyester film is used as a sealant layer in a multilayer body including a base material layer including a crystalline polyester film, an adhesive layer and a sealant layer in this order, the method including: a step in which FT-IR analysis is performed on the polyester film by a reflection method, and the crystallinity of the polyester film is measured by the following formula; and a step in which a first polyester film having a crystallinity of 2 to 15% is selected: I1409=p1×I1340+p2×I1370??(Formula 1) Crystallinity[%]=p1×(I1340/I1409)×100??(Formula 2)