CPP vacuum aluminizing film process points

日期:2019/6/13 8:06:04 / 阅读: / 来源:本站

CPP vacuum aluminizing film process points
(1) Extrusion. When the cast film is formed, the uniform distribution of the melt, the subsequent processing, and the homogeneity required for the use of the film are determined by the uniform temperature of the melt at the T-die of the extruder. The PP pellets enter the extruder and, after a certain temperature and time, are melted and plasticized under the action of the rotary shearing force of the screw, and are metered into the filter.
The homogeneity and purity of the carcass are critical to the subsequent process and product quality. The foreign matter and the unmelted particles in the melt appear as spots, crystal dots, etc. on the film. Therefore, two stations are used in the production. The system solves the problem of melt purity. At the same time, it can increase the melt pressure, enhance the shearing effect, and facilitate the plasticization of the resin evenly and completely.
The extruder adopts 5 temperature sensors to systematically measure the temperature of different melt zones and evaluate the function of the homomixing device. In addition, the melt pressure display is used to show the molten material entering the machine head under different host speeds, heating temperatures and filtration conditions. In this case, it is necessary to manufacture high-quality films.
(2) Flow molding. The highest crystallization temperature of PP is 90 ° C, the molten material is extruded from the lip of the coat hanger die, flowing to the rotating quenching and setting roll surface, and the material of the compressed air knife cold surface and air co-cooling up to 250 ° C Cold to room temperature, forming a small, almost transparent film of crystallites, which is the key to molding. In addition to the adjustment of the die gap of the T-die, the cooling device also plays an important role. This process not only cools the film, but also ensures uniform film thickness and prevents the base film from shrinking. There is an optimum flow point between the flowing film and the quenching setting roll, so that the film is applied at the most reasonable angle, while reducing the time of exposure to the air, preventing the crystallinity of the film from increasing and causing the light transmittance to decrease.


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