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How to improve the transparency of PP products? 7 points all over the face!
- Aug 02, 2018 -
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  2. 1.Matrix resin itself

The transparency of the matrix resin itself has a great influence on the transparency of PP products. In order to improve the transparency of PP, a small amount of polyacrylate resin with good compatibility and good transparency can be added.

2, nucleating agent

It can significantly increase the crystallization rate, increase the crystallization rate and crystallinity.

(1) inorganic nucleating agent is mainly composed of ultrafine talc powder and SiO2, including calcium carbonate, mica powder, inorganic pigments and fillers, which have low price and rich source, but have a certain influence on the gloss and transparency of the products.

(2) organic nucleating agent organic nucleating agent is a low molecular weight organic substance with nucleating action. It is represented by sorbitol and its derivatives, which has good compatibility with the matrix resin, which can significantly improve the transparency and gloss of the products.

(3) after the dosage of the nucleating agent on sorbitol, after the dosage of nucleating agent is more than 0.3%, the effect of transparency improvement is not obvious or even decreased, but when the amount is less than 0.2%, the number of nucleation is insufficient and the transparency is not increased enough. It can be seen that the dosage of nucleating agent is best between 0.2-0.3%. Therefore, the suitable nucleating agent content can improve the transparency of PP better.

3. Molding temperature

When the temperature is too high, the low molecular weight substances in the nucleating agent will produce decomposition and volatilization, reduce the effective components in the nucleating agent and reduce the improvement effect of transparency, and the higher temperature will destroy the original nucleation in PP, reduce the heterogenous nucleation center and reduce the modification effect; and the temperature is too low, the dispersity of the nucleating agent is not Well, the effect of transparency is poor. Therefore, choosing a suitable molding temperature is particularly important for improving transparency.

4, toughening agent

Toughening agent and PP can not be soluble each other, refractive index is different, will occur at the interface of refraction, thus affecting the transparency of the goods. With the increase of toughening content, the area of the interfacial area is more intense, and the transmittance of the products is worse.

5. Process parameters

The optimum processing temperature, cooling temperature, injection pressure and other process parameters are also helpful to the transparency of PP.

Processing temperature: under the conditions of processing, the lower the processing temperature, the smaller the crystallization size, and the better transparency; the cooling temperature, the lower the cooling temperature, the crystallinity will be reduced, and the transparency will be better.

Injection pressure, injection time and holding time affect the orientation of molecules. The orientation will affect the crystallization of the molecules, so the transparency can be improved to a certain extent by shortening the injection and holding time and reducing the pressure without affecting the performance and appearance of the products.

6. Molding process

Comparing the injection, drawing and blowing processes, the injection and blowing processes are found to be most beneficial to the transparency of the products.

7. Mold

The higher the smoothness of the mold, the better the transparency of the product.