Method for hydrolyzing dimethyldichlorosilane in saturated acid

Abstract

The invention relates to a hydrolysis technology of methyl chlorosilane, in particular to a technology for hydrolyzing dimethyldichlorosilane in saturated acid and preparing high cyclosiloxane and hydrolysate with low chloride ions. The technology is characterized by comprising the following steps: mixing vaporized dimethyldichlorosilane with concentrated hydrochloric acid to perform hydrolysis reaction, sending the reaction solution to a phase separator for separation, using the separated crude hydrolysate and concentrated hydrochloric acid to perform hydrolysis reaction again, sending the reaction solution to the phase separator to separate hydrolysate and acid solution, washing the hydrolysate with water, sending the hydrolysate to the phase separator to separate polydimethylsiloxane and acid solution, sending the concentrated hydrochloric acid separated through the first hydrolysis separation to a liquid membrane reactor to separate hydrogen chloride gas, and sending concentrated hydrochloric acid back to the hydrolysis reactor for circular reaction, wherein the acid solutions separated through the other steps are also used for circular reaction. By adopting the method of the invention, the operation process is simplified, the energy consumption is reduced and the production cost is lowered.

Description

technical field [0001] The invention relates to a hydrolysis process of methylchlorosilane, in particular to a process for preparing a hydrolyzate with high content of cyclosiloxane and low chloride ion by hydrolyzing dimethyldichlorosilane in saturated acid. Background technique [0002] Dimethyldichlorosilane is an important product in the production of silicone monomers, and the polydimethylsiloxane produced by its hydrolysis is the main raw material for the production of downstream products of silicone, such as silicone oil and silicone rubber. [0003] The hydrolysis of dimethyldichlorosilane can be carried out in two ways, one is to use a large amount of water hydrolysis or azeotropic acid (about 20% hydrochloric acid) hydrolysis process, the advantage of this production process is that the polysiloxane in the hydrolyzate The content of cyclic body is high, and the hydrolyzate is easily separated from hydrochloric acid. The disadvantage is that the hydrogen chloride p...

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Problems solved by technology

[0005] CN85100433B discloses an organochlorosilane hydrolysis process, adopts a static mixer, and circulates under saturated hydrochloric acid conditions. In this hydrolysis process, the yield of hydrogen chloride is high, but the content of rings in the hydrolyzate is low, and it does not involve the linear reaction with Cl terminal groups. Siloxane treatment process

[0006] CN1090580A discloses a method for hydrolyzing organodichlorosilanes. A hydrolysis aid is added in the hydrolysis reaction so that the residual HCl in the neutralized siloxane is not emulsified and the content of the hydrolyzed species cyclosiloxane is increased. This hydrolysis process cannot directly obtain gaseous hydrogen chloride

In this method, the viscosity of the hydrolyzate is difficult to control due to the high-temperature steam treatment in the second step.

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