The common production methods of chlorinated polyethylene
May 09, 2019
Chlorinated polyethylene is made of polyethylene (PE) by chlorination. It has the dual advantages of plastic and rubber. It is resistant to oil, ozone, heat and oxygen, corrosion, fire, bacteria and microorganisms. Other aspects are superior to other rubbers. It can be used alone or in combination with plastics and rubber. It has outstanding advantages in the fields of waterproofing membranes, plastic doors and windows, wire and cable sheathing, hose tape, color bicycle tires, glass door and window sealing strips, etc. An ideal polymer elastic material has broad application prospects.
At present, the production process of chlorinated polyethylene CPE is divided into two categories: homogeneous chlorination process and heterogeneous chlorination process. There are three production methods according to chlorination: solvent method, aqueous phase suspension method and gas-solid phase chlorination method. The production of chlorinated polyethylene CPE should use PVC resin with loose structure and extremely thin skin layer to enlarge the surface area of PVC particles and increase the contact area with chlorine gas. In the solvent chlorination method, S-PVC is dissolved in a chlorine-containing solvent, an initiator azodiacetonitrile is added, and chlorine gas is introduced into the reaction vessel for chlorination. The carbon tetrachloride solvent method is still widely used in China, and its overall level of equipment is comparable to that of developed countries in the early 1970s. This method has a uniform reaction and is easy to process. It can be used to produce advanced corrosion-resistant coatings or used for the production of fishing nets, industrial filter cloths and other products after spinning. Disadvantages are long process flow, difficulty in solvent recovery, high production cost and easy environmental pollution. The aqueous suspension method (heterogeneous chlorination) is carried out by adding S-PVC resin to water or hydrochloric acid, stirring to form a suspension slurry, adding an initiator and other chlorination aids, and introducing chlorine gas for chlorination. The process of the method is short, the product has good heat resistance and mechanical properties, and the application range is wide; the disadvantage is that the acid waste gas generated in the production process needs to be treated.
The most common production method for chlorinated polyethylene CPE is gas-solid phase chlorination, which is a process in which S-PVC resin is directly chlorinated in the reactor under the conditions of external conditions. Ordinary ultraviolet light initiation method has a long reaction time and a high reaction temperature, and the obtained product has poor uniformity. The low-temperature plasma technology will overcome the shortcomings of the conventional gas-solid phase reaction and achieve rapid chlorination. The low-temperature plasma chlorination method is still in the development stage. This method has simple process, small equipment occupation, long service life of equipment, and basically no “three wastes” emission, which meets the requirements of national energy conservation and emission reduction. .
