High-quality PVC products, how to choose lubricants

Whether it is in plastic wrap, plastic shoes, leather products, or films, cables, and plastic bags, you can see PVC (polyvinyl chloride). As one of the five general-purpose plastics, PVC has high strength, non-flammability, weather resistance, and excellent geometric stability. PVC pipes occupy the leading position in the market share of plastic pipes by virtue of their light weight, corrosion resistance, high compressive strength, safety and convenience. Driven by the new infrastructure, PVC products continue to usher in a peak period of development in the fields of water supply and drainage, agriculture, electricity and communications. Environmental protection and high-quality products have become the key for manufacturers to win the market.

How to complete the high-quality advancement of PVC products? In addition to raw materials, processing equipment, and processing technology, the lubricant with good genes—wax may be an important breakthrough that you have overlooked!

During the processing and plasticizing process of heat-sensitive PVC materials, 80% of the heat required comes from the friction and shear heat between raw materials and screws. It is these hot spots that lead to the risk of PVC degradation. How to control the friction between screw/sleeve and PVC to delay plasticization, so as to achieve good external lubrication effect? How to improve the friction between PVC particles to promote plasticization, so as to improve the internal lubrication effect? Which wax to add for the best balance of internal and external lubrication?

Saturated hydrocarbons can be divided into non-polar hydrocarbons (such as polyethylene wax and polypropylene wax) and polar hydrocarbons (such as chlorinated paraffin, oxidized polyethylene, etc.) according to polarity. Saturated hydrocarbons can be divided into liquid paraffin (C16-C21), solid paraffin (C26-C32), microcrystalline paraffin (C32-C70) and low molecular weight polyethylene (molecular weight 1000-10000), etc., mainly used in PVC Non-toxic external lubricant:

(1) Liquid paraffin: Commonly known as white oil, it is a colorless and transparent liquid, which can be used as a transparent external lubricant for PVC. The dosage is about 0.5 parts, and the dosage will seriously affect the coloring.

(2) Solid paraffin, also known as natural paraffin, is a white solid and can be used as an external lubricant for PVC. The dosage is 0.1-1.0 parts. If the dosage is too large, it will affect the transparency.

(3) Microcrystalline paraffin, also known as high melting point paraffin, has a white or light yellow solid appearance and is called microcrystalline paraffin because of its fine crystals. Lubricating effect and thermal stability are better than other paraffins. The amount used in PVC is small, generally 0.1-0.3 parts.

(4) Low-molecular-weight polyethylene, also known as polyethylene wax, has a white or light yellow solid powder appearance and poor transparency. It can be used as an external lubricant for PVC extrusion and calendering, and the dosage is generally less than 0.5 parts.

(5) Oxidized polyethylene wax is a partial oxidation product of polyethylene wax, and its appearance is white powder. It has excellent internal and external lubrication, good transparency, and the dosage is 0.2--1.0 parts.

(6) Chlorinated paraffin, good compatibility with PVC, poor transparency, good effect when used in combination with other lubricants, the dosage is less than 0.5 parts.