Blow molding process of transparent plastics

Due to the high light transmittance of transparent plastics, the surface quality of plastic products must be strictly required, and there should be no streaks, pores, and whitening. Haze, black spots, discoloration, poor gloss and other defects, so the material and equipment are affected in the entire blow molding process. Mold, and even product design, must pay great attention to and put forward strict or even extra requirements. Secondly, because most of the transparent plastics have high melting point and poor mobility, in order to ensure the surface quality of the product, it is often necessary to finely adjust the technical parameters such as high machine temperature, injection pressure, injection speed, etc., so that the plastic injection can not only fill the mold, but also not. Internal stress will result in product deformation and cracking. Therefore, the Shanghai blow molding factory has to carry out strict operations in terms of material preparation, equipment and mold requirements, injection molding processing skills and product material handling.

(1) Preparation and monotony of materials Because any impurities contained in the plastic can affect the transparency of the product, it can also be stored and transported. During the feeding process, it is necessary to pay attention to the sealing to ensure that the material is clean. In particular, the material contains moisture, which will cause the material to deteriorate after heating, so it must be monotonous, and during injection molding, it is necessary to use a monotonous hopper for feeding. It should also be noted that in the monotonous process, the input air should preferably be filtered and dehumidified to ensure that it does not contaminate the material. Monotonic technology of transparent plastic: material technology monotonic temperature (℃) monotonic time (h) material layer thickness (mm) filler pmma70～802～430～40pc120～130>6<30 select hot air circulation monotone pet140～1803～4 select continuous monotone Feeding equipment is better.

(2) Cleaning of barrel, screw and accessories In order to prevent material contamination and the existence of old materials or impurities in the depression of screw and accessories, especially resin with poor thermal stability, screw cleaning is used before use and after shutdown. Clean the parts with the cleaning agent, so that no impurities are stuck. When there is no screw cleaning agent, you can use pe, ps and other resins to clean the screw. When temporarily shutting down, in order to prevent the material from staying at high temperature for a long time, resulting in degradation, the temperature of the monotonic machine and the barrel should be lowered, such as the barrel temperature of pc, pmma, etc. should be lowered to below 160 ℃. (The hopper temperature should drop below 100°C with respect to pc).