In the production process of plastics, the friction between molten polymer molecules and the friction with processing equipment needs to be considered during molding processing, which will increase the viscosity of the polymer melt, reduce the fluidity, and affect the quality of the surface of the product. Therefore, in the processing process, lubricants need to be added to improve the melt fluidity, improve the demoulding effect of plastic parts, and improve the processing performance of plastics. This article will introduce readers to the commonly used organic lubricants - paraffin, microcrystalline paraffin, liquid paraffin, PE wax.
Paraffin wax is mainly composed of straight-chain alkanes, containing only a small amount of branched chains, and is widely used as lubricants and release agents for various plastics. Its external lubrication effect is strong, which can make the surface of the product shiny. Its disadvantages are poor compatibility with PVC, low thermal stability, and easy to affect the transparency of products. It is mainly used in UPVC extrusion products, and the dosage is generally 0.5~1.5 parts, and too much dosage has an impact on the strength of the product.
Microcrystalline paraffin wax is mainly composed of branched-chain alkanes, naphthenes, and some linear alkanes. The molecular weight is 500~1000, that is, C3e~C72 alkane, which can be used as an external lubricant for PVC and other plastics, and the lubrication effect and thermal stability are better than that of general paraffin, and it is non-toxic. The disadvantage is that the gel speed is slow, which affects the transparency of the product.
Liquid paraffin wax is commonly known as "white oil", suitable for PVC, PS and other internal lubricants, good lubrication effect, non-toxic, suitable for injection molding, extrusion molding, etc., but the compatibility with polymers is poor, so the dosage should not be too much.
PE wax is PE with a molecular weight of 1500~5000, and partially oxidized low-molecular-weight PE is called oxidized PE wax, which can be used as a lubricant for PVC and other uses. It has a stronger internal lubricating effect than other hydrocarbon lubricants, is suitable for extrusion and calendering, improves processing efficiency, prevents the adhesion of films and other materials, and facilitates the dispersion of fillers or pigments in polymer matrices. The performance of PE wax is similar to that of PP wax.