Composite film transparency problems? What is the reason?

Many flexible packaging factory require composite membrane has higher transparency, use a large area of blank base compound film BOPP, CPP, but in a composite process, sometimes there will be a flexible packaging composite film bag of reduced transparency, serious when even will cause the composite film bags discarded. So what is the cause? How should solve? First, the composite finished product has obvious glue spots appearance defects. Second, with the glue. Not appropriate with glue program will lead to the main agent and curing agent is not fully mixing. May produce & other; Colloidal particles & throughout; Phenomenon. Third, the adhesive itself color too deep, deep yellow, yellow, red, sometimes even make soy sauce soup as dark red, on the film and the corresponding color. In demanding situations of transparency, therefore, choose high micro yellow or colorless transparent glue adhesion agent. Fourth, bake, improper temperature setting. A began to enter the path when the temperature is too high, dry too fast, causing surface layer adhesive solution concentration of local enhancement, surface crust, after the internal heat into the glue liquid layer, also make the rubber is not uniform, caused the opaque. Therefore baked road from the entrance to the exit temperature should be gradually rise, from low to high, there is a gradient, let solvent in order to continuously from internal to external evaporation. Fifth, the transparency of base material. The inner base material surface rendering & other; Sharkskin & throughout; 、“ Flow mark & throughout; And the appearance quality problems such as crystal point, will seriously affect the transparency of composite bags. Transfer to the graphic part when printing ink mist version of fouling, will significantly influence the transparency of the composite membrane.