Stearic acid

Stearic acid is white or slightly yellow solid bead-like particles, slightly fatty odor, non-toxic, becomes colorless and transparent liquid after melting, insoluble in water, melting point is 70-71 degrees, under 90-100 degrees Slowly volatilize, mainly internal lubrication, the general addition amount is 0.2-0.5 parts, it is not easy to be too large, otherwise it is easy to spray frost, it is a polar group, and it has good compatibility with PVC resin, which can improve the lubricating effect of the melt. . However, stearic acid passes through the hydrogen chain between the molecules, which reduces the polarity of stearic acid and enhances the external lubrication effect. Therefore, stearic acid can be regarded as an internal lubricant or an internal and external lubricant. ​

Monoglycerides

The chemical name of glycerol monostearate is Glycerin monostearate (Glycerinmonostearate), referred to as monoglyceride (GMS), with a molecular weight of 358. Odorless, non-toxic yellowish waxy solid or flakes, containing a small amount of diester and triester, the melting point is 53 degrees, has good compatibility with polyvinyl chloride resin, as a polyvinyl chloride plastic extrusion. The internal lubricant can improve the free flow and non-stickiness of PVC molecules, and has a good dispersing effect.

n-Butyl stearate

N-butyl stearate is obtained by esterification of stearic acid and butanol with p-toluenesulfonic acid as a catalyst. It is a light yellow oily body with a slightly fatty smell; molecular weight 340.6, freezing point 18-22 degrees, flash point 188 degrees, soluble in most organic solvents, insoluble or slightly soluble in glycerol, ethylene glycol, methanol and some amines . It has plasticizing effect and excellent internal lubricating effect in the initial stage, and has good dispersibility, heat resistance and transparency. However, the continuous lubricating effect is low, and it is often used in combination with stearic acid. When the filler is added too much, it can be added appropriately.

Calcium stearate​

Calcium stearate is white fine powder without obvious mechanical impurities. Insoluble in water, soluble in hot ethanol and ether, decomposed into stearic acid and corresponding calcium salt in case of mineral acid. It is water absorbent in the air, so you can pay attention to moisture-proof during storage and transportation. No sulfide pollution, good long-term thermal stability. Melting point 150-155 degrees, non-toxic, internal lubrication has the effect of heat stabilizer, moderate external lubricant and melting accelerator. The appropriate dosage is 0.1-0.4 part, and when it exceeds 0.6 part, the external sliding effect is strengthened.

Barium stearate

Cadmium stearate is white or slightly yellow powder, insoluble in water, soluble in hot ethanol and ether, can absorb water in the air, and decompose into stearic acid and corresponding cadmium salts in case of strong acid. It can be used as a heat-resistant, light and transparent stabilizer in the processing of polyvinyl chloride resin to improve the transparency of the product, improve the light stability, and prevent the precipitation and adhesion. >

Barium stearate

Barium stearate is white powder with no obvious mechanical impurities, excellent thermal stability, both lubricity, minimal initial coloration, excellent light stability and weather resistance; good transparency, not easy to precipitate during processing; When used together with barium stearate, epoxy compound or phosphite, it has obvious synergistic effect. Melting point 160 degrees, external lubrication, dosage 0.5-1.0.

The lubricating order of various types of stearate is: lead stearate, zinc stearate, cadmium stearate, magnesium stearate, calcium stearate, barium stearate.

Paraffin

Paraffin is a straight-chain alkane-hydroxy mixture with a relative density of 0.87-0.92 and a melting point of about 57-63 degrees. It is soluble in gasoline, chloroform, dimethylbenzene and other solvents, insoluble in water, free of polar groups, and polychlorinated. Ethylene has poor compatibility and is a typical external lubricant.

Paraffin wax has low melting point, easy precipitation, many times of mold cleaning, low melt viscosity and low lubrication efficiency. In the production of plastic door and window profiles, try not to use paraffin, or use paraffin and stearic acid together, which can reduce volatility and improve lubrication. The general dosage is 0.1-0.8. The optimal dosage is 0.05-0.2. In the organic tin formulation, high melting point paraffin, such as Sasol wax or refined wax with a melting point of 75 degrees, can be used for external lubrication. In the presence of calcium stearate, stearic acid can also be used to replace paraffin to exert external lubrication.

Polyethylene wax/PE wax

Polyethylene wax is PE wax, which is a low molecular weight by-product of the production of polyethylene resin, also known as low molecular weight polyethylene. Foreign products are obtained by direct polymerization of ethylene, and the molecular weight is controlled by the degree of polymerization, such as Honeywell, BASF, Degussa, Mitsui and other companies. Most of the domestic enterprises use the cracking method for production, and the molecular weight is controlled by the cracking temperature and pressure. There are also manufacturers who use the starting materials and shutdown materials in the process of producing PE from large enterprises such as Sinopec and PetroChina. The quality is extremely unstable. The molecular weight and molecular weight distribution of each batch are different. The molecular weight, distribution and structure of products prepared by different methods There are differences in lubricating properties. ​

PE wax is a white powder with an average relative molecular weight of 1500-5000. The relative density is about 0.9 and the softening point is about 100-117 degrees. Due to its relatively large relative molecular weight, high melting point and low high temperature volatility, it can be used at higher temperatures and It shows obvious lubricating effect under the shear rate, and the usual dosage is 0.1-0.3 parts. It can effectively improve the fluidity, spit out and mold release of plastics. It has strong lubricating effect and strong internal lubricating effect. It has high softening point, low melting degree, strong thermal stability, good dispersibility, excellent electrical properties, non-toxic use and low cost.

Since the melting point of domestic PE wax is mostly 70-80 degrees, the molecular weight of PE wax produced by cracking method is only about 2000, which cannot meet the requirements of improving the brightness of plastic products. It is best to choose a product with a melting point of 105-115 degrees or more.

Oxidized polyethylene wax OPE wax

Oxidized polyethylene wax is OPE wax, the melting point is 115-125 degrees, external lubrication and internal lubrication. Oxidized polyethylene wax is a partial oxidation product of polyethylene wax, with certain carboxyl and hydroxyl groups on the molecular chain, and the appearance is white or light yellow fluid powder or granules. ​

However, CPE and ACR are added to the lead salt stabilizer system of the rigid PVC formula. OPE wax has great compatibility with CPE and ACR, and OPE also plays an internal lubrication role. Therefore, OPE wax has both internal and external lubrication. OPE is divided into high density and low density. High density has very efficient internal and external lubrication, which can accelerate the plasticization process, improve metal peeling, melt plasticization uniformity, dimensional stability, and high productivity; low density OPE is highly efficient. External lubricant. OPE wax molecular chains have a certain amount of hydroxyl groups, their compatibility with polar resins has been significantly improved, and they have good compatibility with rubber, plastic, paraffin and other materials, and have a relatively balanced internal and external lubrication for PVC resins. The addition of OPE wax to the transparent PVC formula is better than PE wax and other lubricants; the acid value of the lubricating oil can measure the degree of oxidation and deterioration of the lubricant during use, and has a great impact on the use of the lubricant. The larger the acid value, the faster the plasticization, and the stronger the internal lubrication effect. When the OPE acid value is above 15, it is basically completely compatible with PVC and is only used for transparent products. If the acid value is too large, the mechanical parts will be corroded, especially in the presence of water, the corrosion effect will be more obvious. Low-density non-oxidizing OPE, due to its very low acid value or basically no acid value, has poor polarity and is incompatible with polar resins. It mainly plays the role of external lubrication and delayed plasticization. High-density OPE also has high viscosity, low acid value and low viscosity, high acid value. OPE with high viscosity and low acid value is very effective for accelerating plasticization and reducing costs; OPE with low viscosity and high acid value has accelerated plasticization, super metal peeling, and excellent dispersion effect. The dosage of OPE in plastic products is 0.1-0.3.

PE wax and OPE wax have strong external lubricating effects, and have good lubricity in the middle and late stages of molding. They can be regarded as lubricants in the middle and late stages, and are suitable for the production of products with complex cross-sections.