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Chlorinated Polyethylene ( abbreviated as CPE ) is a kind of amorphous white powder elastomer chlorinated from high density Polyethylene (HDPE). Production methods mainly include Solution Method, Suspension Method, Suspension Solvent Method and Fluid Bed Method.
1. Solution Method
Make high density Polyethylene ( HDPE) with some certain properties dissolve in some polar solvents like CCl4 and chlorobenzene after being heated, and then chloride reaction between these two materials under the action of radical initiator, temperature of 90-100℃ without oxygen, normal pressure of 0.686MPa. When the chlorine content of product is stable, you may get amorphous elastic product after elutriation recycling and drying. This method is easy to control and produced Chlorinated Polyethylene CPE is stable and pure. But solvents used in the reaction is pollutional and hard to recycle. The power consumption is also huge. So this method is rarely used in the industry.
2. Suspension Method
Add high density Polyethylene powder with molecular weight of 100,000~150,000 and particle size of 60 mesh into water medium containing certain amount of emulsifier, dispersent and initiator ( like benzoyl peroxide and azodiisobutyronitrile ) and then heat them to around 80℃. After the emulsification process finished, chlorination reaction shall proceed under the temperature of 115~120℃and normal pressure of 0.98MPa without oxygen. The dosage of chlorine gas and chlorination time shall be controlled and then CPE resin with certain chlorine content will be produced. You may get Chlorinated Polyethylene CPE with certain crystallinity and elasticity after neutralization, washing, filtration, centrifugation and drying.
3. Suspension Solvent Method
Add certain amount of solvent in suspension medium. And the chlorination process is the same as Suspension Method.
4. Fluid Bed Method
Polyethylene powder with high dispersion will be chlorinated in fluid bed under the exposure to γ-ray or ultraviolet ray, so it is also called gas-phase method. The process of this method is hard to control.