Improving the transparency of PP products during injection molding of plastic shell molds

1. The matrix resin itself
The transparency of the matrix resin itself has a significant impact on the transparency of PP products. To improve the transparency of PP, a small amount of polyacrylate resin with good transparency and compatibility can be added.
2. Nucleating agent
It can significantly improve the crystallization rate, increase the crystallization rate and crystallinity ratio.
(1) Inorganic nucleating agents are mainly composed of ultrafine talc powder and SiO2, as well as calcium carbonate, mica powder, inorganic pigments and fillers. They are inexpensive and come from a variety of sources, but have a certain impact on the gloss and transparency of products.
(2) Organic nucleating agents are low relative molecular weight organic compounds with nucleation effects, represented by sorbitol and its derivatives. They have good compatibility with matrix resins and can significantly improve the transparency and surface gloss of products.
(3) In terms of the amount of nucleating agent, when the amount of nucleating agent exceeds 0.3%, the transparency improvement effect is not significant and may even decrease; But when the dosage is less than 0.2%, the nucleation quantity is insufficient and the transparency increase is insufficient. From this, it can be seen that the optimal amount of nucleating agent is between 0.2 and 0.3%. Therefore, an appropriate amount of nucleating agent can better improve the transparency of PP.
3. Forming temperature
If the temperature is too high, the low molecular weight substances in the nucleating agent will decompose and evaporate, reducing the effective components in the nucleating agent and the improvement effect of transparency. Moreover, if the temperature is too high, it will destroy the original crystal nucleus in PP, reduce the heterogeneous nucleation center, and reduce the modification effect; If the temperature is too low, the dispersibility of the nucleating agent is poor, and the transparency effect is poor. Therefore, choosing an appropriate molding temperature is particularly important for improving transparency.

4. Toughening agent
Toughening agents, as they are not miscible with PP and have different refractive indices, can refract at the interface, thereby affecting the transparency of the item. As the toughening content increases, the area of the mutual interface becomes stronger, and the transparency of the product becomes worse.
5. Process parameters
The ideal processing temperature, cooling temperature, injection pressure and other process parameters also greatly contribute to the transparency of PP.
Processing temperature: When the processing conditions are met, the lower the processing temperature, the smaller the crystal size, and the better the transparency; Cooling temperature: The lower the cooling temperature, the lower the crystallinity and the better the transparency.

Injection pressure, injection time, and holding time can affect the orientation of molecules. And orientation can affect the crystallization of molecules, so shortening the injection and pressure holding time and reducing pressure can improve its transparency to a certain extent without affecting the performance and appearance of the product.Plastic shell mold--Electronic Digital Product Mold,Plastic Shell Mold for electronic products,Electronic product mold,electronic shell Plastic Injection Mold, plastic injection mould.