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Protective film, iphone X mobile phone protective film-

by:YoukingTech     2021-11-09
Everyone knows that PE protective film is made of PE (polyethylene) as the base material and then coated with pressure-sensitive adhesive. Therefore, the quality of the protective film, the adhesive plays a decisive role, the first is the quality of the adhesive, and the important point is the drying control of the adhesive during the production and coating process. The drying process of the PE protective film adhesive refers to the process of volatilizing the solvent or water in the adhesive layer coated on the substrate to solidify the adhesive. Since solvent or water volatilization always takes a certain amount of time, in the production process of protective film, drying is usually the slowest step. The drying speed not only determines the production speed but also largely affects the quality of the product. Once the adhesive is coated, the solvent will evaporate quickly before it enters the dryer oven. The surface temperature of the adhesive layer is reduced due to the endothermic heat of volatilization, so the volatilization rate also decreases. When the protective film enters the oven, the solvent volatilizes what is absorbed The heat transferred from the outside is supplemented. When the heat reaches equilibrium, the surface temperature of the glue layer and the volatilization speed of the solvent are kept constant. The viscosity and other rheological properties of the PE protective film adhesive are the most important properties that affect the coating behavior of the protective film. According to the dependence of the viscosity on the shear rate, the fluid can be divided into three types: Newtonian fluid, swelling body and pseudoplastic body. The change of viscosity shear time, fluids are divided into Newtonian fluid, thixotropic body and rheological body. The greater the deviation of the rheological properties of the adhesive from the Newtonian fluid, the more likely to have various quality problems in the coating operation, especially When the adhesive exhibits the properties of an swelling body, since its viscosity will increase rapidly with the increase of the coating speed during the coating process, a greater mechanical force must be used to spread the adhesive, so the faster the coating speed, the more difficult it is to obtain Uniform coating. Increasing the temperature of the oven can of course increase the diffusion rate of the solvent. However, too high temperature tends to cause foaming of the adhesive layer and increase the risk of fire. Usually the temperature of the oven is divided into several areas: the temperature in the first area is lower, which can extend the constant-rate drying time, and the temperature in the latter areas gradually increases to increase the drying speed in the later period. In addition, part of the high boiling point solvent or liquid is added to the glue solution. Therefore, in order to produce high-quality PE protective film products, the following three conditions must be met: first, the quality of the substrate; second, the quality of the adhesive; third, the advanced production technology.
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