In daily use, we can find that some OPP protective films have residual pressure-sensitive adhesive on the protected surface during use, which is not easy to remove. Therefore, this problem has to make the most difficult problem for protective film manufacturers and users-the problem of adhesive residue-not only affects the appearance, but also causes material contamination. So why does OPP protective film have this problem? what is the reason? The source manufacturer of the protective film and everyone briefly talk about it. OPP protective film usually has three kinds of residual glue. One is cohesive damage: it is protected, with pressure-sensitive adhesive on the surface and substrate, and the surface of the protective film coating loses its luster; the other is sticky damage: it is protected, and there are more rubber residues on the surface. The substrate can be seen on the surface of the coating; the third is the migration residue: it is protected, and there is a small amount of pressure-sensitive adhesive residue on the surface, and the surface gloss of the protective film coating remains good. One of the more common reasons is that the peel strength of the OPP protective film has changed after a period of time. After the protective film is attached to the material to be protected, it will take a while to remove it. The short one takes only a few minutes, and the long one takes more than a year, mostly in 3-12 months. During this period, the peel strength of the protective film tends to increase with time, which is usually fast first, then slow, and finally stable. When the peel strength rises to exceed the cohesive strength or adhesive force, cohesive failure or adhesion failure will occur, resulting in adhesive residue. Another reason is the aging of the OPP protective film, which is composed of plastic substrates and pressure-sensitive adhesives, both of which belong to high polymers. Its aging mechanism mainly includes heat aging and ultraviolet aging. After the aging of the protective film, the macromolecular chains of the substrate and the pressure-sensitive adhesive are broken, the average molecular weight is reduced, the cohesive strength is reduced, and then cohesive failure occurs.