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Knowledge of lubricants - pe/ope wax

Knowledge of lubricants - pe/ope wax

2022-05-07

1. What is lubricant?

During the molding process of polymer materials, the substances added to the polymer materials in order to improve the flow performance of polymer melt and reduce or avoid the adhesion to the equipment are called lubricants: the substances coated on the surface of metal equipment in contact with products in order to avoid the adhesion to metal equipment and facilitate demoulding during the molding process of polymer materials are called release agents, also known as lubricants.

2. Function of  Polyethylene wax as internal and external lubricant

As an internal lubricant, PE wax has good compatibility with polymers. It can reduce the cohesion between polymer molecules in the polymer, so as to improve the internal friction heat generation and melt fluidity of plastic melt. As an external lubricant, PE wax mainly improves the friction between polymer melt and hot metal surface of processing equipment It has poor compatibility with polymers and is easy to migrate from the melt to the outside, so it can form a lubricating thin layer at the interface between plastic melt and metal.

3. Common lubricant for PVC - oxidized polyethylene wax

It has special properties such as low viscosity, high softening point, good hardness, good thermal stability, low high-temperature volatility, excellent dispersion of fillers and pigments, excellent external lubrication, strong internal lubrication and coupling effect, which can improve the production efficiency of plastic processing, reduce production cost, have good compatibility with polyolefin resin, good moisture resistance at room temperature and strong chemical resistance, It has excellent electrical properties. It is made of polyethylene wax after special oxidation process. The molecular chain of oxidized polyethylene wax has certain functional groups.

4. Characterization of internal and external lubrication imbalance in PVC foamed products

(1) There is less internal lubrication and more external lubrication, the plasticizing time is obviously prolonged, the plasticizing torque is reduced, the product is difficult to form and becomes brittle; There is more internal lubrication and less external lubrication, the plasticizing time is significantly shortened, there is a serious wall sticking phenomenon, the thermal stability time is shortened, and there are decomposition yellow lines on the product surface.

(2) The internal and external lubrication is insufficient, the melt viscosity is large, the plasticizing torque is large, and the melt wall sticking phenomenon is serious. There is a yellow decomposition line on the material surface, the surface smoothness is poor, and the mechanical properties of the product are reduced: the internal and external lubrication is excessive, the plasticizing torque is small, and the melt plasticization is obviously insufficient. Although the product has good smoothness, the pressure point adhesion is poor, which seriously affects the mechanical properties of the product.

5. The role of lubricants in PVC processing

When PVC lubricant plays a role outside the melt, its basic lubrication role is to reduce the interaction between particles at all levels of PVC and between PVC materials and the metal surface of processing equipment. Through external lubrication, PVC lubricant can reduce the friction heat generation between PVC particles at all levels and between PVC materials and the metal surface of processing equipment, and reduce the lubrication effect of melt adhesion to the metal surface of processing equipment.

6. Influence of lubricant in PVC pipe in the formula of non plasticized PVC pipe, the addition of lubricant will not only affect the process conditions, but also directly affect the strength of the pipe. Too much lubricant is added, which reduces the discharge speed and destroys the normal operation. Proper selection of lubricant system can produce the best processing conditions and the best physical properties of products.

7. Use of internal and external lubricants

(1) The amount of lubricant added to a system should enable the material to obtain uniform plasticization and sufficient fluidity under normal operating conditions. If the adjusted amount of external lubricant still cannot meet the requirements of material processing, a small amount of internal lubricant can be considered.

(2) There are many factors affecting the external lubricant. When using high surface active fillers, such as ultrafine calcium carbonate and active calcium, the amount of external lubricant needs to be increased due to their absorption and adsorption to the lubricant. When using impact toughening modifier, the possibility of adhering to the metal surface is large due to the high melt viscosity, so it is often necessary to increase the amount of external lubricant.

(3) The larger the contact surface area between processing equipment and materials, the more external lubricants need to be added. Therefore, more external lubricants are required for thin-walled pipes extruded with the same equipment than thick-walled pipes of the same specification. When the processing temperature is high, the melt tends to adhere to the metal surface, and more external lubricants are added.

Qingdao Sainuo Chemical Co.,Ltd. We are manufacturer for PE wax, PP wax, OPE wax, EVA wax, PEMA, EBS,Zinc/Calcium Stearate…. Our products have passed the REACH, ROHS, PAHS, FDA testing.

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