Generally, esters, soaps or polyhydroxy partial esters and amide compounds of stearic acid: butyl stearate, glycerol monooleate, monoglyceride stearate, hydroxystearic acid, stearic acid and Oleamide, calcium stearate.
2. Internal and external lubricants
Stearic acid, stearyl alcohol, montanic acid and its derivatives (soap, ester), glyceryl trihydroxystearate, OPE bis-stearamide.
3. External lubricant
OPE wax, PE wax, paraffin wax, lead stearate, dibasic lead stearate, low molecular polymer of stearic acid and polyhydric alcohol dibasic acid.
4. When polyolefins are processed in polyolefin plastics, their lubricating effect is diametrically opposite to that in PVC. The molecular structure of paraffin wax and PE wax is similar to that of polyolefin, and the polarity is very weak; the compatibility is large, so internal lubrication is used. effect. The amides have higher polarity and lower compatibility with polyolefins, and play an external lubricating role, which is similar to the use of external lubricants for PVC-U. seepage phenomenon. The high temperature flow of polyolefin is much better than that of polyvinyl chloride, and the use of lubricants is limited, and sometimes it can be processed without lubricants at all.
5. Relatively speaking, 5m polystyrene is more polar than polyethylene, has a certain degree of compatibility with internal and external lubricants, and has better formula elasticity. Polystyrene is provided to users in the form of granules, which already contain various additives. The commonly used lubricants to increase fluidity are butyl stearate and liquid paraffin. Add a small amount of zinc stearate or amide wax to improve mold release.
6. Thermoplastic engineering plastics such as polyamides, polycarbonates, polyesters, polyurethanes, etc. are generally injection molded products. Their operating temperature and pressure are generally high, their fluidity is also poor, and the processing temperature is generally high, so lubricants with high volatility are not suitable for use. The resin itself is generally easy to be hydrolyzed or sensitive to acid and alkali, so general metal soaps are not suitable for use. Usually, additives are also required to have extremely low exudation or leaching, and transparency, so lubricants with low compatibility or small molecular weight are not suitable for use. Generally, internal and external lubricants with large molecular weight are used, such as high-quality lubricants. of pentaerythritol stearic acid or montan wax type lubricants.
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