Due to the high transmittance, transparent roll molded products must have strict surface quality requirements, without any spots, pores, or whitening. Defects such as haze, black spots, discoloration, and poor gloss affect the raw materials and equipment throughout the injection molding process. The design of molds and even products must pay great attention to and put forward strict or even special requirements.

Secondly, due to the high melting point and poor fluidity of transparent roll molded products, in order to ensure the surface quality of the product, it is often necessary to make slight adjustments to process parameters such as machine temperature, injection pressure, and injection speed, so that the mold can be filled during roll molding without generating internal stress and causing product deformation and cracking. Therefore, strict operations must be carried out in terms of raw material preparation, equipment and mold requirements, rolling molding process, and product raw material processing.

1、 The preparation and drying of materials may affect the transparency of the product due to the presence of any impurities in the plastic, thus affecting storage and transportation. During the feeding process, attention must be paid to sealing to ensure that the raw materials are clean. Especially if the raw materials contain moisture, heating them can cause them to deteriorate, so they must be dried and a drying hopper must be used for feeding during injection molding. It should also be noted that during the drying process, the input air should be filtered and dehumidified to ensure that it does not contaminate the raw materials. Its drying process, such as the drying process of transparent rolling plastic products: material process drying temperature (℃) drying time (h) material layer thickness (mm) remarks pmma70-802-430-40pc120-130>6<30 use hot air circulation drying pet 140-1803-4 use continuous drying and feeding device is preferred.

2、 The cleaning of the barrel, screw and its accessories is to prevent contamination of raw materials and the presence of old materials in the recesses of the screw and its accessories

Impurities, especially resins with poor thermal stability, exist. Therefore, screw cleaning agents should be used to clean all parts before use and after shutdown to prevent impurities from sticking. When there is no screw cleaning agent, resins such as PE and PS can be used to clean the screws.

When the machine is temporarily shut down, in order to prevent the raw materials from staying at high temperatures for a long time and causing a drop in temperature, the temperature of the dryer and machine barrel should be lowered. For example, the temperature of machine barrels such as PC and PMMA should be lowered to below 160 ℃. The temperature of the hopper should be reduced to below 100 ℃ for PC.

3、 In mold design, attention should be paid to the following points (including product design) in order to prevent poor reflux flow or uneven cooling that may cause poor plastic molding, surface defects, and deterioration. Generally, in mold design, the following points should be noted:

A=The wall thickness should be as uniform as possible, and the demolding angle should be sufficiently large;

B=The transition part should be gradual. Smooth transition to prevent sharp corners. Sharp edges, especially PC products, must not have any gaps;

C=Gate. The runner should be as wide and short as possible, and the gate position should be set according to the contraction and condensation process. If necessary, a cold material well should be added;

D=The surface of the mold should be smooth and have low roughness (preferably less than 0.8);

E=exhaust hole. The groove must be sufficient to timely discharge air and gas from the melt;

F=Except for PET, the wall thickness should not be too thin, generally not less than 1mm.