1. Interface chemistry theory
The melt of PVC is regarded as a phase system, and the
PVC External Lubricant or internal /
External Lubricant is regarded as a surfactant. The performance and characteristics of lubricant in production are explained by the theory of interface chemistry.
The non-polar PE wax, paraffin wax and other pure slip agents are regarded as non-polar substances at both ends.
Products such as ester lubricants, oxidized polyethylene wax, etc., which have polarity at one end and non polarity at the other end, are regarded as surfactants.
2. Similar dissolving principle
Two substances with similar structure or polarity (solute and solvent) can dissolve each other, which is an important principle of similar solubility in chemistry. In the theory of guiding the use of humectants, the principle of similar solubility is the most widely used. Regarding PVC melt as a solvent system, lubricant melt is solute.
Similar solubility leads to the concept of solubility and saturation. Any substance has a certain solubility in another substance. If it exceeds the saturation of dissolution, it will not dissolve and precipitate. Similarly, the total amount of any substance of the same kind has a certain solubility in another substance. If the total amount exceeds the saturation, it will precipitate.
When we design the formula, we focus on this guiding theory. As long as we meet the production and product performance, we try to reduce the total amount of all lubricants, including the total amount of the same kind of lubricants, so that we can effectively reduce or avoid precipitation.
3. Laminar slip model
It is assumed that the motion behavior of the film formed between the melt surface and the metal surface by different types of PVC external lubricants conforms to the model theory of fluid laminar flow and surface slip.
From this practice, it can be concluded that the synergistic use of different kinds of external lubricants is better than the single use of the same kind of PVC Lubricants.
The effect of ester and wax compound lubricant is better than that of single wax lubricating system or single ester lubricating system!
