Special resin for polyvinyl chloride and with low polymerization degree

Abstract

The invention relates to special resin for polyvinyl chloride and with a low polymerization degree. The special resin is mainly prepared from the following raw materials: 100 parts of vinyl chloride monomer, 115 to 130 parts of deionized water, 0.005 to 0.02 part of a neutralizing agent, 0.04 to 0.068 part of a dispersing agent A, 0.017 to 0.036 part of a dispersing agent B, 0.014 to 0.034 part of a surfactant, 0.014 to 0.026 part of an initiator A and 0.012 to 0.02 part of an initiator B. The obtained PVC resin with an average polymerization degree of 650-850 is high in internal porosity and uniform in porosity, the diffusivity of the special resin to small molecular substances is improved, and the PVC resin can be widely applied to the production process of the special resin for gas-solid-phase-process chlorination of PVC.

Description

technical field [0001] The invention relates to the technical field of polymer chemical industry, in particular to a special resin for polyvinyl chloride with a low degree of polymerization. Background technique [0002] Chlorinated polyvinyl chloride (CPVC) is obtained by further chlorination of polyvinyl chloride (PVC), and is a new type of polymer elastomer material between rubber and plastic. After the PVC resin is chlorinated, the irregularity of the molecular bond increases, the polarity increases, the solubility of the resin increases, and the chemical stability improves, thereby improving the material's heat resistance, acid, alkali, salt, oxidant, etc. Corrosion. Compared with PVC, CPVC has greatly improved its heat resistance, corrosion resistance, flame retardant and self-extinguishing properties, and mechanical properties. It is widely used in building materials, electrical, chemical, metallurgy, medicine, coatings and other fields. Applications. [0003] At pr...

AI Technical Summary

Problems solved by technology

In the chlorinated polyvinyl chloride process produced by the gas-solid phase method, the chlorine gas molecules in the gas phase enter through the internal pores of the particles and undergo grafting reactions with the PVC molecular chains. The grafting rate and grafting uniformity are affected by the abundance of pores and the uniformity of pores. At the same time, the heat of grafting reaction is removed by circulating vulcanized chlorine gas to produce polyvinyl chloride resin. By adjusting the stirring speed of the polymerization tank and the type and amount of dispersant, the polyvinyl chloride resin can be significantly changed macroscopically. The particle shape of vinyl resin can adjust the particle size distribution and the roundness of the shape, and the internal void structure is also improved, but it is difficult to complete the regulation of the deep micro-nano structure of the resin. The specificity of ethylene production and application is not strong, especially in the process, heat removal is difficult, which will cause poor thermal stability of chlorinated polyvinyl chloride resin

[0009]The production temperature of polyvinyl chloride resin with low degree of polymerization is high, the thermal movement of molecules is intense, and the growth rate of polyvinyl chloride molecular chain is fast, so it is necessary to control the number of free radicals required for chain initiation. Reduce the initiation rate, usually the process of adding the initiator at one time will cause the initial initiator to decompose the free radical concentration, resulting in too fast reaction rate, too fast precipitation to form compact particles, reduce the porosity of PVC particles, and improve the appearance of PVC particles Density, affecting sulfidation of process materials and diffusion of chlorine