CN1218809A - Process for preparing sodium methyl-silicate - Google Patents

Abstract

Methyl trichlorosilane of density over 98.5% and hydrochloric acid undergo reaction of hydrolysis and polycondensation under certain conditions to produce methyl silicic acid which further undergoes substitution reaction with sodium hydroxide under specific conditions to produce sodium methyl silicate. The process of the present invention has fast and full hydrolysis and polycondensation, and sodium methyl silicate yield over 75%.

Description

Process for preparing sodium methyl silicate

The invention relates to a preparation process of sodium methylsilicate.

The current general method for producing sodium methyl silicate is as follows: the hydrolysis reaction of certain proportion of monomethyl trichlorosilane and dimethyl dichlorosilane is carried out at the temperature of less than 40 ℃ to generate methyl silicic acid, and then the methyl silicic acid and NaOH are subjected to substitution reaction at the temperature of 80-90 ℃ to generate the methyl sodium silicate. The hydrolysis temperature of the method is required to be less than 40 ℃, so that the further polymerization of the active silicic acid can be prevented, but the temperature is low, the reaction is influenced to a certain extent, the reaction is insufficient, the reaction time is long, and when the substitution reaction is carried out at 80-90 ℃, the reaction temperature is high, the reaction is too violent, the control cannot be carried out, and the yield is low.

The invention aims to provide a preparation process of sodium methyl silicate, which has the advantages of sufficient reaction, short reaction time and high yield.

The preparation process of the sodium methylsilicate comprises the following steps:

(1) under the action of 18-22% hydrochloric acid of a polymerization inhibitor, performing hydrolytic polycondensation on monomethyltrichlorosilane with the concentration of more than or equal to 98.5%, controlling the reaction temperature to be 28-32 ℃, reacting for 1-2 hours, and reacting monomethyltrichlorosilane and hydrochloric acid in a volume ratio of 1: 6-7 to obtain methylsilicic acid;

(2) filtering, and separating the methylsilicic acid from the hydrochloric acid;

(3) washing, namely rinsing the methyl silicic acid with water;

(4) filtering again;

(5) and adding equivalent sodium hydroxide into the methyl silicic acid, and performing substitution reaction for 0.5-1.5 hours at the temperature of 80-90 ℃ to obtain the sodium methyl silicate.

The principle of the preparation process of the sodium methylsilicate comprises the following steps:

the preparation process of the sodium methyl silicate adopts 18-22% hydrochloric acid as a polymerization inhibitor, so that the hydrolysis and polycondensation reaction of the methyl trichlorosilane is fast and sufficient, the energy is saved, the yield of the sodium methyl silicate is greatly improved, and the yield is more than 75%.

The present invention will be described in detail with reference to the following examples:

example 1:

(1) under the action of 20% hydrochloric acid of polymerization inhibitor, mono-methyl trichlorosilane with concentration of 98.5% is subjected to hydrolytic polycondensation reaction at 29-30 ℃ for 1.5 hours, and the volume ratio of mono-methyl trichlorosilane to hydrochloric acid is 1: 7;

(2) reacting to obtain resin-shaped methyl silicic acid, filtering, and separating hydrochloric acid;

(3) rinsing the methylsilicic acid with water;

(4) filtering again;

(5) and adding equivalent sodium hydroxide into the methyl silicic acid, controlling the temperature to be 80-85 ℃ for substitution reaction, and reacting for 1.5 hours to obtain the sodium methyl silicate, wherein the yield is 78.6%.

Example 2:

(1) carrying out hydrolysis polycondensation reaction on 25% hydrochloric acid and 98.5% monomethyl trichlorosilane for 1.5 hours at the temperature of 30-32 ℃, wherein the volume ratio of the monomethyl trichlorosilane to the hydrochloric acid is 1: 6;

the rest of the process was the same as in example 1, and the yield of sodium methyl silicate was 75.6%.

Claims (1)

1. A preparation process of sodium methylsilicate is characterized by comprising the following steps:

(1) under the action of 18-22% hydrochloric acid of a polymerization inhibitor, performing hydrolytic polycondensation on monomethyltrichlorosilane with the concentration of more than or equal to 98.5%, controlling the reaction temperature to be 28-32 ℃, reacting for 1-2 hours, and reacting monomethyltrichlorosilane and hydrochloric acid in a volume ratio of 1: 6-7 to obtain methylsilicic acid;

(2) filtering, and separating the methylsilicic acid from the hydrochloric acid;

(3) washing, namely rinsing the methyl silicic acid with water;

(4) filtering again;

(5) and adding equivalent sodium hydroxide into the methyl silicic acid, and performing substitution reaction for 0.5-1.5 hours at the temperature of 80-90 ℃ to obtain the sodium methyl silicate.