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Classification and formula design principles of PVC lubricants

Date:2024-4-2 9:06:31 Browse:0

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The formula of PVC is the most complex of all plastics, and the most complicated part of the PVC formula is the application of lubricants. Proficient mastery of the classification and application principles of lubricants has positive significance for the optimization of PVC formulas.


Classification and formula design principles of lubricants for PVC


PVC lubricants can be divided into two types, external lubricants and internal lubricants.


The main function of the external lubricant is that it has poor compatibility with the polymer and easily migrates out of the melt, so it can form a thin layer of lubrication at the interface between the plastic melt and the metal.


The internal lubricant has good compatibility with the polymer. It plays a role in reducing the cohesion between polymer molecules inside the polymer, thereby improving the internal friction heat generation of the plastic melt and the fluidity of the melt.


Of course, most lubricants have the dual effect of internal and external lubricants rather than a simple function. For example, when the initial processing temperature is low or the dosage is large, the external lubricating properties dominate. When the temperature rises, the compatibility of PVC is improved, and it mainly plays the role of internal lubrication when the dosage is appropriate.


PVC lubricants are also divided into low temperature lubrication, medium temperature lubrication and high temperature lubrication. 


Low-temperature lubrication plays a role in the early stages of processing, such as paraffin, stearic acid, monoglyceride, butyl stearate, stearyl alcohol, etc.; 


Medium-temperature lubrication plays a role in the middle stage of processing, such as PE wax, OPE wax, stearic acid Lead, cadmium stearate, etc.; 


High-temperature lubrication plays a lubricating role in the later stages of processing, such as calcium stearate, barium stearate, etc.


Engineers in PVC industry believe that the use of lubricants in PVC formula design should follow below principles:


1. The smaller the amount of external lubrication, the better, on the premise of ensuring that the product does not adhere to the metal surface and that the product does not have discoloration or burning;


2. Internal lubrication should be used sparingly without affecting fluidity and plasticization;


3. If you use the similar type of internal lubricants. Try to use high, medium and low temperature lubricants in conjunction with each other. External lubricants are also the same;


4. For products that require good fluidity, such as profiles, pipe fittings, etc., the amount of internal lubrication should be slightly more than external lubrication; for products that do not require a high degree of plasticization, such as pipes, the amount of external lubrication should dominate;


5. As the amount of filler increases, the lubricant should be appropriately increased accordingly. Light calcium has a high oil absorption value, while heavy calcium has a low oil absorption value. Pay attention when using it;


6. For foaming products, try to reduce the amount and dosage of lubricants such as paraffin that affect foaming. If the density is reduced or the calcium content is increased, the amount of lubrication should be appropriately increased;


7. When an imbalance of lubrication occurs, the principle is keeping one lubrication unchanged and adjusting the other lubrication. This principle should be adopted to facilitate quick identification of the cause and normal production.


As one leading manufacturer of PVC additives from China, NOVISTA provide high quality PVC additives, including PVC impact modifiers (CPE/Acrylic impact modifiers/MBS), PVC processing aids (Acylic processing aids, foaming regulators, PVC internal and external lubricants) and PVC stabilizers (One-pack Lead stabilizers / Ca-Zn stabilizers).


We can also provide debugging and substitution solutions of additive to ensure that you will use the products with high quality and good prices to reduce your production cost.


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