Due to limitations in technology, production equipment, and raw materials, pre-coated films (mostly hot melt adhesives) produced by domestic equipment still have quality defects. Since the production process is a process similar to that of the coating film, the colloid is dissolved in an organic solvent, and the rubber is roll coated on the substrate film by a concave anilox roll, so that the solvent volatilization is insufficient, and the odor is generated during operation. After the film is coated, the solvent evaporates and the surface is easy to foam.
At the same time, since the hot melt adhesive is blended by several kinds of polymer materials, in the process of using the laminating machine, the temperature control is not good, which will cause degradation and cross-linking of the high molecular polymer in the hot melt adhesive, so that the surface of the film is poor. Some pre-coated film colloids easily adhere to the outer surface of the substrate, resulting in poor winding. Since the adhesive layer is thin and the surface is not activated, defects such as insufficient adhesion to the printed matter are likely to occur. Since the hot melt adhesive is composed of several kinds of materials, the transparency after coating is significantly worse than that of the low temperature pure resin type precoat film.