Selection principle of pvc lubricant

Plastic products, the impact of lubrication of many factors. Such as the type of polymer, polymerization methods, molding methods, processing machinery, processing conditions, the interaction between various additives and so on. Selection of lubricants should be considered. In addition, the performance required for the product must also be considered. PVC lubricant dosage, PVC pipe processing and performance of greater impact. To this end the following PVC pipe to illustrate the selection of lubricants. Lubrication system depends largely on the choice of mutual matching, generally should follow the following principles.

Principle one

Pay attention to the lubrication of the formula inside and outside the balance, to adapt to the early, mid and late stages of the material lubrication requirements, to achieve the lubrication balance of consistency and long-term. Too much lubricant, extrusion speed, material prone, plasticization is not good. Lubricants and more, a large amount of extrusion material plasticization is good, but the initial lubrication is not good extrusion torque is too large. When the lack of lubrication later, it will lead to the screw homogenization section, compression section, die section lubrication inadequate, severe material shear, affecting the profile surface quality and intrinsic properties, will cause serious decomposition. Lubricants are generally combined with the melting point and processing temperature to determine the lubricants in the formula of early, mid and late lubricity.

Principle two

To meet the needs of the premise, the lubricant should be maintained at a minimum dosage. Although lubricants play an important role in the formulation, not the greater the amount, the better. Internal and external lubrication is balanced within a certain limit. Due to the limited compatibility of lubricants with PVC resins, adding too much will adversely affect the PVC system. Many processing and thermal stability problems are likely caused by excessive lubricant.

Principle three

Selection of lubrication should pay attention to the formula stabilizer, processing aids, modifiers, fillers and other effects on the lubrication. The balance of the lubrication system is not a simple balance between the lubricants, but rather the lubrication balance of the entire formulation system. Different stable system formulations require different lubricants, lubricants in the formula to play the role of lubrication is not the same. For example, in the lead-salt stabilizer system, the greater the polarity of the lubricant, the better the compatibility with PVC and the less pronounced in the organotin stable system. This is due to organic tin itself has a plastic effect. Rare earth stabilizer because of its special structure of rare earth cable, and the synergistic effect of the lubricant more obvious, easy to PVC gel, plasticizing can reduce the time and improve melt flow.

Understanding this is helpful when we choose a few products.