(1) Calcium stearate:
White powder, melting point 148-155℃, non-toxic, excellent lubricity and processability, no vulcanization pollution, combined with basic lead salt and lead soap, can increase the gelation speed, the dosage is generally 0.1-0.4PHR.
(2) Oxidized polyethylene wax
White or light yellow powder or particles. Although oxidized polyethylene wax contains a small amount of polar groups, it is still incompatible with PVC, but it has high lubrication efficiency, which can improve the lubricity between polymer and metal, increase extrusion efficiency, and improve The dispersibility of the colorant gives the product good transparency and gloss. The dosage is 0.1-0.5PHR.
(3) Stearic acid
White or light yellow particles, melting point 70-71°C. Slowly volatilize at 90-100℃, used as
External Lubricant in hard PVC processing, the dosage is generally 0.2-0.5PHR, and it has the effect of preventing chromatographic scaling, but if the dosage is too large, it will bloom.
(4) Glyceryl stearate
Powder, melting point 85-87℃, has excellent heat resistance and fluidity, can increase the amount of filler, and can promote plasticization. Used together with waxes can improve the thermal stability of PVC-U. The general dosage is 0.2-0.6PHR.
In practice, people have found that when two or more lubricants are used in combination, they have different effects than when used alone. In the formula of profiled materials, most of them adopt the compounding method
(5) Paraffin
It has a melting point of 57-63°C and does not contain polar groups. It is a typical external lubricant. Because of its low melting point, easy evaporation and low melt viscosity, it can only provide lubrication in a narrow range. It is suitable for single and twin screw extruders. The general dosage is 0.1-0.8PHR. This product has poor transparency and whitening easily.
(6) Polyethylene wax
White powder with a softening point of about 100-117°C. Due to its relatively large molecular weight, high melting point, and low volatility, it also shows obvious lubricating effects at higher temperatures and shear rates. It is suitable for single and twin-screw extrusion of rigid PVC, the usual amount is 0.1-0.5PHR.
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