Patent ID: 9670383
Date: 2017-06-06
CPC Classifications: B29C,B29K,B32B,B65D,C09J,Y10T

Claim:
1. A method for producing a paper-based heat sealable laminate, comprising: coating polyethylene on at least one surface of a paper substrate, and coating polyethylene terephthalate on a film of the polyethylene by an extrusion lamination process by using an extruder, wherein: the polyethylene terephthalate is a homopolyethylene terephthalate having an intrinsic viscosity of 0.72 to 0.88 dL/g, the polyethylene is a low-density polyethylene, and the surface of the film has been treated, an air gap, expressed as a distance from a lip opening of a T-die of the extruder to a surface of the coating of the polyethylene, is 25 cm or less, an extrusion temperature of the homopolyethylene terephthalate during melt extrusion in the extrusion lamination process is in a range of not lower than Tm+25° C. but lower than Tm+70° C., based on a melting point (Tm) of the homopolyethylene terephthalate, the extrusion pressure is in a range of 3.5 to 6.5 MPa, and, after the extrusion lamination with the homopolyethylene terephthalate, the laminate coated with the homopolyethylene terephthalate is cooled by the cooling rolls.