HEAT-SEALING POLYPROPYLENE FILM Russian patent published in 2019 - IPC B32B7/02 B32B27/08 B32B27/32 B65D65/40 

FIELD: laminated products or materials.

SUBSTANCE: invention relates to a biaxially oriented multilayer polypropylene film, to versions of using such a film, as well as to versions of a package. Biaxially oriented multilayer polypropylene film consists of at least three layers representing the base layer, the first intermediate layer I, and the first heat-sealed coating layer I, which is applied on the intermediate layer I. Base layer contains at least 50 wt. % propylene polymers having melting point of 150 to 170 °C. First intermediate layer I contains at least 40 wt. % soft polyolefin and, if necessary, mixed with each other various soft polyolefins, which when measured by DSC method give curve of 2nd heating, which continuously rises from 20 to 70 °C. Thickness of first intermediate layer I ranges from 1.0 to 12 mcm. Heat-sealable coating layer I is characterized by welding start temperature ≤ 115 °C. Thickness of first heat-sealed coating layer I ranges from 0.5 to 2.5 mcm. All layers of the film essentially do not contain a cavity. Film density is not more than 5 % less than design density of film. Said film is used to make laminate containing another biaxially oriented polypropylene film and metallized film. Biaxially oriented polypropylene film is used to make a packing bag. According to the first version, the package is characterized by bursting pressure of at least 200 mbar. According to the second version, the package is characterized by an average pressure loss of less than 15 mbar, where pressure loss is noted in 30 s.

EFFECT: invention enables to obtain a film with high welding and barrier properties, particularly in respect to oxygen and water vapor.

18 cl, 2 dwg, 1 tbl, 9 ex