PE wax - a tool to solve the problem of insufficient pvc stability
Due to the poor thermal stability of PVC, it is necessary to add corresponding stabilizers to repair the defects of PVC chains and timely absorb the HCL produced by PVC dechlorination. At the same time, due to the processing characteristics of PVC with high viscosity and large shear, it is necessary to add a corresponding lubricant such as polyethylene wax when adding a stabilizer.
Polyethylene wax, ie, PE wax, low molecular weight polyethylene, is directly polymerized from ethylene. The products synthesized by different synthetic processes and catalytic systems have different molecular weight, molecular weight distribution and molecular chain structure, and the performance of the corresponding products. There will also be significant differences. PE wax is usually a white powder with an average molecular weight of generally 1500-5000 and a melting point of 100-120 degrees. It has excellent external lubrication effect in PVC processing, which can effectively improve the fluidity, yield, dispersion, surface brightness and mold release of PVC processing. Due to its high molecular weight, high melting point and high temperature stability, it exhibits excellent external lubrication under high temperature and high shear conditions.
Polyethylene wax products can effectively improve the thermal stability of PVC and the fluidity of processing, increase the extrusion efficiency of PVC products, improve the surface gloss of products, and effectively reduce the appearance of PVC products processing.
At present, most of the PE waxes on the domestic market are divided into several types:
1. Ethylene is polymerized into PE wax. The PE wax produced by this method has good external lubrication performance, high gloss, narrow molecular weight distribution and very stable quality, and represents products such as Honeywell's A-C series.
2. The by-product of the ethylene polymerization process, commonly known as the sub-brand wax, is purified by the refining process. The product has low viscosity, high melting point, excellent external lubrication performance and low price, but the quality varies with raw materials and processes. Certain fluctuations, due to the characteristics of the refining process, there will inevitably be more low melting point components in the product.
3. PVC thermal stability medium and low molecular weight polyethylene cracking products, commonly known as cracking wax, the cracking process is simple and easy to operate, but the molecular weight distribution of the product has a certain fluctuation with the production process, the quality is relatively good, there will still be a small part of the low Melting point component.