Chlorinated polyvinyl chloride (CPVC)

日期:2023/1/12 8:32:33 / 阅读: / 来源:本站

2.3.10 Chlorinated polyvinyl chloride
Chlorinated polyvinyl chloride (CPVC) resin, also known as perchloroethylene resin, is prepared by chlorination of suspension polyvinyl chloride resin, which is the main raw material for the production of chlorinated polyvinyl chloride resin. At present, chlorinated PVC resin is mainly produced by solution chlorination or suspension chlorination.
At present, there is no national quality standard for chlorinated polyvinyl chloride resin. Table 2-80 lists the enterprise standards of chlorinated polyvinyl chloride resin produced by Huludao Chemical Group Co., Ltd.
2.3.10.1 Performance characteristics
Chlorinated polyvinyl chloride is a white powder resin with relative density of 1.48~1.58 and chlorine content of 61%~68%; It has good adhesion, flame retardancy, chemical corrosion resistance and electrical insulation; The product does not deform in boiling water, the maximum service temperature is 105 ℃, the melting temperature is 110 ℃, and the shrinkage rate is (3~7) x10-3cm/cm; Rockwell hardness R117~122; With the increase of chlorine content, the tensile strength and bending strength of the products increase, but the brittleness increases; Generally, the tensile breaking strength of chlorinated PVC products is 52~62MPa, the elongation at break is 4%~65%, the compression strength is 62~152MPa, the bending strength is 100~117MPa, the tensile modulus is 2482~3280MPa, the impact strength of cantilever beam is 53~298J/m, and the linear expansion coefficient is (68~76) x10-6 ℃ - 1; Chlorinated polyvinyl chloride is easily soluble in esters, ketones, aromatic hydrocarbons and other organic solvents.
2.3.10.2 Forming method and application
Chlorinated polyvinyl chloride resin molding products are mainly chlorinated polyvinyl chloride by suspension method. The common PVC molding method can be used for processing, but the raw material in the molding process has a higher plasticizing temperature. The extrusion and injection molding process can be used for molding pipes, plates, films, wires and cables, injection molding pipe fittings, electrical switches and other products.
2.3.10.3 Key points of forming process
① The raw material is easy to absorb moisture. Before processing, dry the resin in an 80 ℃ oven for 2~4h.
② Chlorinated PVC is easier to plasticize than PVC, but the thermal stability time of the melt is shorter than that of PVC; The higher the chlorine content in the domestic CPVC resin, the easier the melt fracture occurs during processing.
③ The resin is easy to decompose during the molding process, and has great corrosion to the equipment and molding mold. It is required that the contact surface between the equipment and the molten material should have a anti-corrosion chromium coating.
④ The molten material has a high viscosity and is easy to stick to the wall during the flow process. The molten material flowing through the equipment should have high processing accuracy, smooth surface and low resistance.
⑤ When the screw is working, the oil medium shall be used for cooling and temperature control to ensure the thermal stability of the screw working temperature.
⑥ The barrel temperature should be controlled by oil or water as the heat conduction medium to reduce the temperature, and the fluctuation of barrel process temperature should be controlled to be no more than 5 ℃.
⑦ The suspension chlorinated polyvinyl chloride resin is used for molding plastic products, and the lotion chlorinated polyvinyl chloride resin is used to make coatings, varnishes and adhesives.
⑧ When forming pipes, heating rods and cooling devices capable of cooling shall be installed in the core rods in the forming mould.
⑨ CPVC, like PVC resin, is not dangerous.
At present, the domestic producers of chlorinated polyvinyl chloride resin include Beijing No.2 Chemical Co., Ltd., Shanghai Electric Chemical Co., Ltd., Yibin Tianyuan Chemical Plant and Huludao Chemical Group Co., Ltd.

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