Method for removing solvent from chlorinated polyvinyl chloride solution

Abstract

The present invention discloses a solvent removal method which can remove solvent from CPVC chlorinated solution. According to the discipline that the solvent chlorobenzol and the water forms azeotrope in the chlorinated solution, the method adopts the method combining gas-phase spray desolventize and cross-current stripping elutriation desolventize and forms the ''gas-phase spray and cross-current stripping elutriation coupling'' desolventization process of CPVC chlorinated solution. The method overcomes the defects of the prior elutriation process, such as bad desolventization effect, high solvent unit consumption and serious environmental pollution. If the chlorobenzol desolventization process provided by the present invention is adopted, the residual chlorobenzol of resin in the exit is less than or equal to 4.6wt percents, the chlorobenzol content in the discharged hot water is less than or equal to 20ppm and the chlorobenzol concentration of the gas phase in the exit is less thanor equal to 600ppm.

Description

technical field [0001] The invention relates to a process for removing solvent from polymer solution, in particular to a method for removing solvent from chlorinated polyvinyl chloride solution, which is used in the field of polymer material production. Background technique [0002] The production of chlorinated polyvinyl chloride resin by the solvent method is to dissolve the PVC resin in a solvent for chlorination. The solvent used is chlorobenzene or a mixed solvent composed of low-boiling halogenated hydrocarbons. The chlorinated liquid produced after the chlorination reaction The solvent needs to be removed to obtain the chlorinated polyvinyl chloride resin product. The reported process of "removing solvent" from chlorinated polyvinyl chloride chlorinated liquid all adopts water analysis process. According to the different dispersion modes of chlorinated liquid, water analysis process is divided into two types: one is direct water Analysis method, such as the desolvati...

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Problems solved by technology

Judging from the existing reports on the "solvent removal" process of chlorinated polyvinyl chloride chlorinated liquid, the hot water in the "direct water analysis method" provides most of the heat required for the evaporation of the solvent, and the hot water is still carried by the outflow of the resin. solvent, the solvent vapor and hot water removed during the water analysis process flow in parallel, the solvent and hot water can only form a first-order azeotropic evaporation, and the residual solvent in the hot water flowing out of the water analysis tower is relatively high, reaching 170mg / L Above, during the liquid-solid separation, the solvent evaporates in large quantities, which not only increases the unit consumption of the solvent, but also causes serious air pollution; in the "emulsion water analysis method", the difference in the quality of the chlorinated liquid obtained by each batch of chlorination reaction leads to The emulsification conditions are difficult to control accurately, and because surfactants are added to the chlorinated solution in this method, the surfactants cannot be removed from the resin during water analysis, which affects the quality of the product

From the existing documents, no report identical or similar to the subject of the present invention has been found

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