Chlorinated Polyvinyl Chloride Pipe

日期:2022/9/19 8:57:22 / 阅读: / 来源:本站

                                                                                                                                                           Chlorinated Polyvinyl Chloride Pipe
Chlorinated polyvinyl chloride (VC) polyvinyl chloride resin is made by chlorination modification, and polyvinyl chloride resin is the main raw material for the production of chlorinated polyvinyl chloride resin. The difference between chlorinated polyoxyethylene and polyvinyl chloride is that the chlorine content of the former is higher than that of the latter, the chlorine content of vinyl chloride resin is about 57%, and the chlorine content of chlorinated polyvinyl chloride resin is 60%. %~75%. At present, the content standard of chlorine in domestic chlorinated polyvinyl chloride resin
The regulation is 61%~65%. The extrusion molding formula of chlorinated polyvinyl chloride pipe is based on chlorinated polyvinyl chloride as the main raw material, plus a certain proportion of stabilizers, lubricants and other auxiliary materials. (1) Characteristics and uses of chlorinated polyvinyl chloride pipes ①Characteristics of chlorinated polyvinyl chloride pipes
a. Tensile strength, flexural strength, flexural modulus and bearing pressure of chlorinated polyvinyl chloride pipes
The force is higher than that of polyethylene pipe, polyvinyl chloride pipe and polypropylene pipe.
b. Chemical resistance, heat resistance and weather resistance are higher than PVC pipes. c. When transporting drinking water, it is not affected by chlorine gas in the water to ensure the quality of drinking water. d. Excellent flame retardancy, no dripping when burning, slow burning diffusion and no gas.
.Good flexibility, easy to install, can be connected with solvent.
Chlorinated PVC pipes are suitable for storage and heat transfer of chemical solutions and various waste liquids. If there is a proportion of graphite filler in the raw material of the forming CPVC pipe, it can also be used for the internal application of the heat pipe CPVC
Water, temperature up to 120 ℃, life expectancy up to 40 years. It has only started in recent years, and it is mostly used in cold and hot water transportation pipelines for a long time. (2) When the raw material for polyethylene molding contains chlorine, some auxiliary materials are mixed. The amount is greater than 61%, and the viscosity is About 110mL/g water-phase suspension method chlorinated polyvinyl chloride tree The following requirements should be paid attention to in the selection of auxiliary raw materials stabilizers, lubricants, impact modifiers, fillers and other auxiliary materials.
①The selected auxiliary materials should have good compatibility with CPVC resin.
②The amount of chemical, weather and flame retardant additives.
③Choose auxiliary materials that can improve the thermal stability and impact resistance of CPVC resin to prevent the decomposition of CPVC molten material under high temperature conditions.
④ The additives should be able to improve the fluidity of the CPVC melt and reduce the gel time and temperature, so as to reduce the adhesion of the melt to the equipment parts and the surface of the mold.
⑤ It can promote the plasticization of CPVC materials, reduce the melt pressure, facilitate the molding of the melt, and reduce the stress generated during cooling and shaping.
⑥ The performance of the additives is relatively stable, and it is not easy to migrate.
⑦CPVC pipe forming materials for conveying drinking water should be added with non-toxic additives in the formula, and the hygiene indicators of raw materials should comply with GB/T17219-1998 standards.
⑧In the formula of CPVC pipe forming materials, the mass part of the main raw material CPVC resin can be 100, or a certain mass part of PVCSG5 resin can be added, and the sum of the two raw material mass parts is 100. For example, if the mass part of CPVC resin is 90 in the formula of the material for forming the pipe, the mass part of the PVC resin is 10; if the mass part of the PVC resin in the formula is 40, the mass part of the CPVC resin is 60. As the mass of PVC resin in the formula increases, the Vicat softening temperature will also increase with the increase of the mass of PVC resin.
and decline.
Reference example of raw material combination formula for chlorinated polyvinyl chloride extrusion molding.
Excellent plastic molding process
Barium Stearate (BaSt)
More than 60%. Count 110ml/8 paraffin
Xinhua Scenery Section B (CPVC content
100 calcium carbonate (CaCO,)
left and right) Tricity lead sulfate (3PbO) carbon black
Hard Stores (P6S) 1.5
(3) The extrusion molding process conditions of the type ethylene pipe are similar, and the slight difference is that the extrusion molding equipment is used.
① The quality requirements of the spare parts are higher; the control requirements for the fluctuation range of the process temperature are stricter.
Forming the tube blank→Vacuum sizing, cooling and shaping-cooling water tank to cool down the tube-traction-printing a trademark
Cut a pipe end and flare → Inspection → Packer warehouse
②Equipment selection High-speed mixer is used for mixing raw materials, and the required speed is 800-1000r/min. The upper cover is equipped with an exhaust device, and the speed is adjustable. After the raw materials are evenly mixed, they are used in a mixer for cooling. The rotation speed is low, and the temperature can be cooled by circulating cooling water. Plasticizing raw materials can be used single-screw extruder or twin-screw extruder. The temperature of the screw can be adjusted by circulating oil, and the equipment should be equipped with a better exhaust device; it is more appropriate to use circulating water or circulating oil to cool the barrel, and pay attention to the fluctuation of the process temperature control at ±5 °C. It is more suitable to use ordinary parallel twin-screw extruder to extrude CPVC powder. No perforated plate is added between the barrel of the extruder and the forming die; the working place of the screw
An overload protection device should be provided. In the mold structure, the shrinkage angle of the mandrel is required to be less than 60°; the length of the section is about 2 times the diameter of the outgoing pipe. At the same time, this section must have a heating and cooling device that can control the temperature of the mandrel to keep the temperature in this section stable. Make the inner wall of the pipe smooth. In order to improve the corrosion resistance of the mandrel, the working surface of each melt channel in the mandrel and the mold should be chrome plated.
③Molding process operation and temperature control
a. CPVC resin should be dried in an oven at 80°C for (2~4) hours before being put into production to remove moisture from the raw materials.
b. The measured raw materials are put into a high-speed mixer (rotation speed is about 900r/min) for mixing and stirring, and the material temperature reaches about 115°C.
c. The high-temperature material after high-speed compounding is cooled in the low-speed mixer until the material temperature reaches
6 The extruder extrusion raw material is in molten state and the process temperature is as follows 2
180°C; molding die temperature 185~190°C. Extrusion temperature of screw extruder: 160 ℃ in the feeding section of the barrel, 170 ℃ in the plasticizing section:
Homogenizing section 175~180℃; forming mold 175~190℃. Extrusion temperature of twin-screw extruder: 188~195℃ in the feeding section of the machine. Plasticizing section
188°C,
The working temperature of Xinsa is 160~170℃. The temperature of screw circulating oil is 100-120℃.
4. Compared with polyethylene pipe molding, it is more difficult to mold polyvinyl chloride. Due to the high melt viscosity of chlorinated polyvinyl chloride (about 2 times larger than that of C resin), poor fluidity, molding is more difficult, and the melt during the production process is more difficult. It is easy to decompose, so the extrusion molding production of chlorinated polyvinyl chloride resin
Pay attention to the following questions. country
①The chlorinated polyvinyl chloride resin must be dried before being put into production.
It is sieved once, and then put into the hopper of the extruder for production. Dry treatment in the British box for 2~4h, and if necessary, the raw materials after high-speed mixing should also use a 40-mesh sieve
②In the raw material formula of forming pipe, attention should be paid to the selection and release of stabilizers and other processing aids, which should focus on improving the fluidity of the body and improving the thermal stability of the raw materials. If necessary, mix the formula materials first, take a small sample for testing, and put it in an oven at 230 °C for 2 hours. If there is no obvious discoloration and decomposition, it means that the selection of auxiliary materials is more reasonable.
③ The extrusion process temperature of chlorinated polyvinyl chloride pipe is slightly higher than that of PVC pipe. However, it should be noted that the temperature control fluctuation cannot be greater than ±5 °C.
④In the production of CPVC pipes, if there is any equipment failure, signs of possible decomposition or smoke coming out of the mold mouth, the feeding into the barrel should be stopped immediately, and the CPVC in the barrel and the mold should be removed with PVC resin, and then the machine should be stopped to remove it. Fault.
⑤ The HCI gas released when the CPVC melt is decomposed is harmful to the human body. Pay attention to the ventilation of the production workshop.
6. The extruder barrel, screw and the melt flow surface in the molding die for the production of CPVC resin should be treated with anticorrosion to prolong the service life of the equipment parts.
⑦ The top cover of the kneader for mixing and stirring raw materials should have an exhaust port (use a 400-mesh copper mesh or cloth bag to seal the exhaust port) to facilitate the evaporation of water vapor.
⑧The extruder for CV pipe type is concerned with the performance conditions such as exhaust gas and process temperature control stability during operation of the extruder barrel. If these two conditions do not meet the production requirements, the extrusion molding of CPVC pipe will increase the difficulty. , even if it is impossible to produce 9. When producing CPVC pipes, the screw should be cooled by circulating oil; the inner rod of the mold should have heating and cooling devices, and the stability of the process temperature of these two parts should be reasonably adjusted and controlled during the work to improve the molten material. The fluidity ensures the molding quality of the product (the control of the temperature of the mandrel has a great influence on the molding quality of the inner wall of the pipe).
⑩When the inner wall of the formed pipe is uneven, an acrylate processing aid (also a methyl methacrylate copolymer) should be added to the raw material formula or appropriately added to improve the melting temperature of the CPVC and PVC resins mixed close; at the same time pay attention to the stability control of the mandrel temperature. 1 In the formulation of CPVC pipe extrusion molding materials, CPVC and PVC greases can be mixed. However, it should be noted that the Vicat softening temperature of the mixed resin will decrease as the amount of PVC resin added increases. For example, when PVC is 10 parts and CPVC is 90 parts in the formula, the softening temperature of Vicat is about 110 ℃; when PVC is 20 parts and CPVC is 80 parts, the softening temperature of Vicat is about 105 ℃; PVC resin and CPVC resin are each At 50 parts, the softening temperature of Vicat is about 90℃

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