An adhesive that forms a strong bond by melting with heat and curing with moisture, and combines fast bonding and high strength.

(1) PU dye is a blue solution, when in contact with polyurethane adhesive, it can dye the polyurethane adhesive layer into blue, in the soft packaging industry, PU dye can be used to determine which layer of the polyurethane adhesive layer is attached to the peeled composite film, which helps to analyze the cause of poor peel strength. (2) Infrared spectral test: reflected infrared test basic spectrum, accumulate the basic spectral database of different raw material film materials, and compare and analyze to judge which layer of glue is on the film.

A: (1) PU dye is a blue solution, when in contact with polyurethane adhesive, it can dye the polyurethane adhesive layer into indigo, in the soft packaging industry, PU dye can be used to determine which layer of the polyurethane adhesive layer is attached to the peeled composite film, which helps to analyze the cause of poor peel strength.
(2) Infrared spectral test: reflected infrared test basic spectrum, accumulate the basic spectral database of different raw material film materials, and compare and analyze to judge which layer of glue is on the film.

A: (1) The thickness of the composite film is inconsistent, resulting in inconsistent shrinkage.
(2) The heat sealing temperature is too high or the heat sealing time is too long.
(3) Insufficient cooling, the heat sealing part is wrinkled.
(4) Insufficient maturation time, temperature, or residual solvent influence.
(5) The surface or inner substrate film has poor heat resistance, shrinks and wrinkles.
(6) Improper tension matching control of the composite substrate during the composite process, resulting in residual stress after maturation and shaping, especially when the composite film thickness is thin, such failures are more likely to occur.