How To Select Lubricants In PVC Formula

Selection of lubricants in PVC formula adjustment, there are many types of lubricants, and each specific product has specific characteristics. Being familiar with the performance advantages and disadvantages of each specific lubricant product and how to use it will help us better design excellent formulas.

1. Molecular structure of lubricants:

Understanding the molecular structure of the lubricant used, including functional groups, chain lengths, single and double bonds, branched chains, isomerization, etc., will help to make a preliminary judgment on the performance of the lubricant. When examining a lubricant, the molecular structure can only be a preliminary judgment of the performance, and it should not be too hasty and arbitrary.

2. Polarity of lubricant:

PVC is a polar material. Whether the lubricant is a polar or non-polar substance can be roughly used as a definition of internal lubrication and external lubrication. If it is the same polar material, but the polarity is greatly different from PVC, it will not be well soluble.

3. Heat resistance of lubricant:

The heat resistance of lubricants has always been an important indicator ignored by most production technicians! The use environment of lubricants is in high-temperature materials, machine screws, barrels, and molds. If the lubricant has been decomposed by heat or the material properties have changed at the temperature of use, it will not be able to play a lubricating role.
So we often see that if lubricants with poor heat resistance are used, such as stearic acid, paraffin, PE wax with low melting point, etc., there is often insufficient lubrication in the later stage of processing, resulting in processing difficulties, or poor surface gloss of the product. This is because the decomposition fails and the lubrication is insufficient in the later stage. If we add PE wax with good heat resistance, ester external lubricant or high-quality heat-resistant oxygen PE wax at this time, the problem can be solved.

4. Lubricant volatility resistance:
Lubricants have good lubrication effects and good heat resistance, but most of them are vaporized and volatilized during processing, so this lubricant is not a good lubricant. TIANSHI polyethylene wax lubricant has a high melting point, does not smoke, and has low volatility. It is the leader among commonly used PVC lubricants.

5. Melting point of lubricant:

The melting point of lubricant is often used by many technicians as the only criterion for judging lubricants. In fact, this is a misunderstanding. As an indicator in various evaluations of lubricants, melting point has certain limitations and inaccuracies. PE waxes made by the same cracking method have higher melting points, higher molecular weights, and better heat resistance. However, if they are both PE waxes, low-melting-point polymerization-made PE waxes may have better heat resistance than high-melting-point PE waxes, and the latter are better lubricants.

Using multiple lubricants in PVC formulas, interpenetrating each other, and compensating for temperature differences can not only reduce the total amount of lubricants used, but also widen the processing range of PVC formula materials, improve the uniformity of PVC melt structure, improve the mechanical properties and appearance quality of materials, and ensure lubrication balance during material extrusion.