Introduction of synthesis process of chlorinated polyethylene

Chlorinated polyethylene (CPE) was prepared by rectifying and chlorinating high density polyethylene (HDPE).

(1) The high-density polyethylene powder with certain characteristics was heated and dissolved in carbon tetrachloride, chlorobenzene and other polar solvents by solution method. Under the action of free radical initiator (such as azodiisobutyronitrile, etc.), the reaction of chlorination was carried out under the condition of no oxygen at 90-100 ℃ and atmospheric pressure to 0.686mpa. After the chlorine content of the product is qualified, it is recovered by water analysis, and then dehydrated and dried to obtain the non crystalline and elastic product. The method is easy to control and can produce stable pure chlorinated polyethylene, but the solvent is easy to cause pollution, the recovery process is complex, the energy consumption is large and rarely used in industry.

(2) Suspension method High density polyethylene powder with molecular weight of 100000-150000 and particle size of 60 mesh sieve was added into water medium containing certain amount of emulsifier, dispersant and initiator (such as benzoyl peroxide and diisobutyronitrile azo). The temperature was raised to about 80 ℃ under agitation. After emulsification, the temperature was raised to 115-120 ℃, and chlorination was carried out under normal pressure to 0.98mpa and oxygen-free conditions. By controlling the amount of chlorine and the time of chlorination, a resin with a certain amount of chlorine is prepared. After neutralization, washing, filtration, centrifugal dehydration and drying, the products with certain crystallinity and elasticity can be obtained.

(3) Adding a certain amount of solvent into the suspension medium of the suspension solvent method, the chlorination operation is the same as that of the suspension method.

(4) The fluidized bed method uses highly dispersed polyethylene powder, which is chlorinated by chlorine in the fluidized bed under the irradiation of γ - ray or ultraviolet ray, so it is also called gas phase method. The process is difficult to control.