2013年10月25日星期五

plastic lubricant some differences

Lubricant is a broad concept. According to their different functions, the lubricant for the following three categories: (1) to reduce the friction between the particles to improve the powder flowability of the materials, also known as glidants glidants); (2) to prevent the fluorescent brightener  adhesion of raw materials to punch surface of the material, also known as anti-adhesion agent antiadherents); (3) to reduce the particle or tablet) with the friction between the die hole wall accessories, this is the real sense of the lubricant. An ideal lubricant should be both of the flow aid, anti-sticking and lubrication three roles, the lubricant in the currently available yet no such ideal lubricant, are often one or two aspects of a relatively good performance, but other effects are relatively poor.
Type of dispersant
Fatty acids, fatty amides, and esters
Stearamide and used with higher alcohol can improve lubricity and thermal stability, the amount (mass fraction) 0.3% -0.8%, the slip agent may be polyolefin; hexenyl bis hard fat acid amides, also known as ethylene bis-stearamide (EBS), the lubricant is a high melting point, the amount of 0.5% to 2%; glyceryl monostearate (GMS), glyceryl tristearate (HTG); oleic acid 0.2% to 0.5% of the amount; hydrocarbon wax solid, mp 57 ~ 70 ℃, insoluble in water, soluble in an organic solvent, the resin dispersibility, compatibility, heat stability are poor, the dosage is generally 0.5% or less
Paraffin
Although the wax is external lubricant, but straight-chain non-polar hydrocarbon, not wet the metal surface, such as polyvinyl chloride resin that does not prevent adhesion of metal walls, only, and stearic acid, calcium stearate and used, in order to achieve synergy
(Nujol): Freezing Point -15 ¯ -35 ℃, the extrusion and injection molding processing, the poor compatibility with the resin, add the amount is generally 0.3% to 0.5%, too much time, but the processing performance bad Microcrystalline wax: obtained from petroleum refining process, the  PVC profile stabilizer larger molecular weight, and has many isomers, mp 65-90 ℃, lubricity and thermal stability, but poor dispersion, the dosage is generally 0.1% -0.2%, preferably butyl stearate, higher fatty acids, metal soaps with
Metal salts of higher fatty acids, called metal soaps such as barium stearate (BaSt) for a variety of plastics, an amount of about 0.5%; zinc stearate (ZnSt) for polyolefins, ABS, etc., the amount of was 0.3%; calcium stearate (CaSt) suitable for GE Plastics, external lubrication, the amount of 0.2% ¯ 1.5%; Other stearic acid soaps such as cadmium stearate (CdSt), stearic acid Magnesium (MgSt), copper stearate (CuSt) low molecular weight waxes
Based on a variety of low molecular aluminum hydroxide  weight polyethylene wax (homopolymer or copolymer), polypropylene, polystyrene or other polymer modified as raw material, by pyrolysis, oxidation from a range of performance of different oligomers Its main products are: homopolymer, oxidized homopolymer, ethylene - acrylic acid copolymer, ethylene - vinyl acetate copolymer, low molecular weight ionomers five categories. Among the most commonly used polyethylene wax
Commonly used polyethylene wax average relative molecular mass of 1500-4000, the softening point of 102 ℃; Other specifications of polyethylene wax average relative molecular mass of 10,000 to 20,000, a softening point of 106 ℃; oxidized polyethylene wax of long-chain molecules with a certain amount of ester group or a soap, and thus the PVC, PE, PP, ABS and external lubrication more balanced, better, its transparency is good. As dispersing agent and its environment, many practical applications, selection of the appropriate dispersing agent is very important.

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