Typically, two or more two lubricant or lubricating system PVC composition, for reducing the migration to the surface of the article of force, thereby improving the dispersibility of the lubricant, a lubricant equilibrium inside and outside.
Variety of commonly used lubricants:
According to the composition of the lubricant can be divided into: saturated hydrocarbons, metal soaps, aliphatic amides, fatty acids, fatty acid esters and fatty alcohols.
Saturated hydrocarbons can be classified into non-polar hydrocarbons (such as polyethylene wax and polypropylene wax) and polar hydrocarbons (such as chlorinated paraffin, oxidized polyethylene, etc.) by polarity.
According to the molecular weight, it can be divided into: liquid paraffin (C16~C21), paraffin wax (C26~C32), microcrystalline paraffin (C32~C70) and low molecular weight polyethylene (molecular weight 1000~10000), etc.
Metal soaps are both excellent heat stabilizers and lubricants. They have both internal and external lubrication, and the different varieties have slightly different weights.
The commonly used metal soaps are added to the lubricant as follows:
PbSt 0.2~1.0phr LiSt 0.6phr
CaSt 0.2~1.5phr ZnSt 0.15phr
BaSt 0.2~1.0phr
Aliphatic amides include two types of mono-fatty acid amides and di-fatty amides. Mono-fatty amides are mainly internally lubricated. The main varieties are stearic acid amide, erucic acid amide, ricinoleic acid amide, etc.; The main varieties are N, N'-ethylene bis stearamide, N, N'-ethylene ricinoleamide and the like.
The fatty acids mainly include
(1) stearic acid, which is the second most widely used lubricant after metal soap. When used in PVC, it has internal lubrication. When the amount is large, it acts as an external lubricant. Generally, the amount of stearic acid added is less than 0.5 parts.
(2) Hydroxy stearic acid, which has good compatibility with PVC, exhibits internal lubrication, but has poor thermal stability.
The fatty acid esters mainly include
(1) butyl stearate, and the appearance is a colorless or light yellow oily liquid. It is mainly lubricated in PVC and has an external lubricating effect, and the dosage is 0.5 to 1.5 parts.
(2) Glyceryl monostearate, code GMS, has a white waxy solid appearance, is an excellent internal lubricant of PVC, has little effect on transparency, and is added in an amount less than 1.5 parts, and can be used together with stearic acid.
(3) Ester wax and saponified wax, mainly refers to the post-order product made by the process of bleaching with montan wax as the main raw material. The bleaching wax has S wax and L wax, the esterified wax has E wax and EG wax, and the saponified wax has O wax and OP wax. Mainly used for hard PVC, the dosage is 0.1~0.3 parts.
The fatty alcohols mainly have
(1) stearyl alcohol, and the appearance is white fine beads, which has internal lubrication and is transparent. Use 0.2~0.5 parts in PVC.
(2) Pentaerythritol, PVC high temperature lubricant, dosage 0.2~0.5 parts.
With the expansion of PVC products, strict requirements have been placed on the hygiene, transparency and processability of plastic additives, thus promoting the development and application of new lubricants. Among them, ester lubricants have developed rapidly and the dosage ratio has been increasing. In Germany's Henkel Loxol G series lubricants, there are both stearyl stearate (G30), oleic acid monoglyceride (G10) and castor oil. Acid monoglyceride (G11), as well as stearic acid monoglyceride (GMS). Dicarboxylic acid higher alcohol esters such as bis(stearyl alcohol) adipate have been used as excellent internal lubricants. The oligomeric complex ester of fatty acid and polyol has a large molecular weight, is resistant to extraction, and does not bloom. It has both internal and external lubricity and is the development direction and development focus. Its representative products are Genkel's G70, G70S, G71, G72, G74 and so on. Since the mid-1980s, China's plastic additives research institutes have successfully developed a variety of complex ester lubricants. The main varieties that have been produced and applied are LC-1, LC-2, LC-4, LC-6. LC-7, RH-60, WH-70, RW-100, ZB-16, ZB-74, H-16, H-74, and the like. On this basis, further developed a multi-functional synergistic additive for PVC (such as composite heat stabilizer / lubricant, etc.).
It should be noted that lubricants have been added to more complex heat stabilizers. In the production of PVC products, it should be used reasonably according to the product specifications and reference formula of the composite heat stabilizer. If there is no special process requirement, no additional lubricant will be added to avoid any problems such as “over-lubrication”.
In rigid PVC plastics, excessive lubricant can result in reduced strength and process operation. Peeling occurs in the case of injection products, especially in the vicinity of the gate. For injection products, the total amount of stearic acid and paraffin is generally from 0.5 to 1 part: the extruded product generally does not exceed one part.
In soft product formulations, too much lubricant can cause blooming and affect the strength of the product and high frequency soldering and printability. If the lubricant is too small, the roller will stick. For the blown film, too little lubricant will stick to the die, and the plastic will be coked in the mold. At the same time, in order to improve the stickiness of the blown film, a small amount of internal lubricant monoglyceride is added. When producing PVC soft products, the amount of lubricant added is generally less than 1 part.
As the professional PVC additives supplier, Novista Group provides PVC internal and external lubricants, which will be used for PVC products, such as pipes, fittings, sheets, boards, profiles, films...
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