RU2794094C1 - Method for producing polyorganosiloxane varnish - Google Patents

Abstract

FIELD: paints and varnishes.

SUBSTANCE: methods for producing polymethylphenylsiloxane varnish and modified derivatives based on it, which can be used as film formers, water repellents of various materials, binders for blend compositions and paints and varnishes. A method for producing polyorganosiloxane varnish, including esterification of methyltrichlorosilane in a mixture with 20 wt.% phenyltrichlorosilane in a water-butanol-xylene solution, removal of the resulting hydrogen chloride, hydrolysis of the esterification products, separation of the organic layer and distillation of excess solvent, characterized in that the product of hydrolysis - silanol, before distilling off the solvent, diisocyanate is introduced into the organic layer in the amount of 0.05-0.15 mol of diisocyanate per 1 mol of the starting methyltrichlorosilane, while esterification is carried out at a molar ratio of methyltrichlorosilane:butanol:water 1:2.5:0.6, hydrolysis is carried out with a solution containing 15-17 wt.% hydrogen chloride, 1-4 wt.% butanol, up to 100 wt.% water.

EFFECT: increasing the physical and mechanical properties of the lacquer film.

1 cl, 2 tbl, 10 ex

Description

The invention relates to methods for producing oligoorganosiloxanes, namely polymethylphenylsiloxane varnish, as well as modified derivatives based on it, which can be used as film formers, water repellents of various materials, binders for composite compositions and paints and varnishes.

A known method for producing polyphenylsiloxane varnish by esterification of phenyltrichlorosilane and butyl alcohol, taken in a molar ratio of 1:3:3, partial hydrolytic condensation of the obtained tributoxyphenylsilane and subsequent transesterification of polybutoxyphenylsiloxane with diphenylolpropane. This method allows you to get polyphenylsiloxane with a polymerization time of 6 min at 250°C (Khananashvili L.M., Andrianov K.A. Technology of organoelement monomers and polymers. M: Chemistry. 1985, S. 251-254). The disadvantage of this method is the large amount of acidic wastewater generated after washing the hydrolysis products with water, which require neutralization.

Known low-waste method for producing commercial polymethylsiloxane esterification of methyltrichlorosilane in a hydrocarbon solvent, hydrolysis of esterification products, separation of the organic layer and distillation of excess solvent, in order to reduce production waste and reduce the curing temperature of the lacquer film, the esterification is carried out with a water-isobutanol-xylene solution containing 3.0 -5.0 wt. % water, 45.0-50.0 wt. % isobutanol, the rest is xylene, at a molar ratio of methyltrichlorosilane: isobutanol: water 1: 1.7-2.3: 0.4-0.75, hydrogen chloride released during esterification is removed, and hydrolysis is carried out with hydrochloric acid solution of alkali metal chloride or ammonium containing 5.0-8.0 wt. % hydrogen chloride, 10.0-15.0. wt. % alkali metal or ammonium chloride, the rest is water (Patent RU1792946, class C 08 G - 77/06, 1993). The disadvantages of this method are the low bending plasticity of the lacquer film and the low impact strength of the film; the lack of compatibility of polymethylsiloxane varnish with traditional paint and varnish resins, which reduces the possibility of its use to create paints and varnishes for various purposes; the use of a hydrolyzing mixture containing a solution of hydrogen chloride with metal chlorides leads to severe salt corrosion of the equipment.

A known method for producing polyphenylsiloxane resin by hydrolytic esterification of phenyltrichlorosilane with excess water in the presence of isobutyl or butyl alcohol in toluene at 50-60°C with a further gradual increase to 80-95°C, polycondensation of the resulting product and distillation of excess solvent. To improve the performance properties, the solution of polyphenylsiloxane resin is modified with triethanolamine at 90-110°C (Patent RU 2170744, class C08G 77/06, C08L 83/06, 2001). The disadvantage of this method is the relatively long drying time of the obtained resin at room temperature (48 hours).

The closest in technical essence to the proposed invention is a method for producing a polyorganosiloxane varnish, including the esterification of methyltrichlorosilane mixed with phenyltrichlorosilane in a water-butanol-xylene solution, removal of the resulting hydrogen chloride, hydrolysis of the esterification products, separation of the organic layer and distillation of excess solvent. Patent RU2108347, class. C08G 77/06, 1998). The disadvantage of this method is the lack of elasticity, low adhesive strength, instability to the action of water and gasoline.

The problem to which the invention is directed is to create a simple method for obtaining polymethylphenylsiloxane varnish and its modified derivatives with improved physical and mechanical properties of the varnish film.

The technical result of the invention is the production of polyorganosiloxane varnish and its urethane derivatives with high physical and mechanical properties of the varnish film.

The technical result is achieved in that the method for producing polyorganosiloxane varnish includes the esterification of methyltrichlorosilane in a mixture with 20 wt. % phenyltrichlorosilane in water-butanol-xylene solution, removal of the resulting hydrogen chloride, hydrolysis of esterification products, separation of the organic layer and distillation of excess solvent. The proposed method differs from the prototype in that diisocyanate is introduced into the organic layer before the solvent is distilled off to the hydrolysis product, silanol, while the esterification is carried out at a molar ratio of methyltrichlorosilane: buganol: water: diisocyanate equal to 1:2.5:0.6:0.05 - 0.15, and the hydrolysis is carried out with a solution containing 15-17 wt. % hydrogen chloride, 1 - 4 wt. % butanol, up to 100 wt. % water.

Methyltrichlorosilane (Tianjin Prosper Technology Co., LTD. No.20, Tianyuan Road, Saida Industrial Park, Wangwenzhuang Town, Xiqing District, Tianjin, China), phenyltrichlorosilane (TU 2437-538-05763441) are used as starting materials in the implementation of the method. -2012 with amend. 1, PJSC "Khimprom"), butyl alcohol (GOST 5208-2013 "Butyl alcohol normal technical. Specifications". JSC "Angarsk petrochemical company"), xylene (TU 38.101254-72, ANK "Bashneft") and the following diisocyanates: toluene diisocyanate (TU 113-38-95-90, Khimprodukt LLC), isophorone diisocyanate (Vestanat IPDI brand of Evonik Resource Effciency GmbH, Germany), hexamethylene diisocyanate (TU 113-03-38-104-90 , OOO "VitaKhim"). The method is carried out as follows.

Samples of methyltrichlorosilane and phenyltrichlorosilane are loaded into a five-necked reactor equipped with a stirrer, dropping funnel, reflux condenser, thermometer, barbater, and a homogeneous mixture consisting of butyl alcohol, water, and xylene is fed under the liquid layer at a rate of 2 cm ³ /min and stirred for 20 min. Then, dry nitrogen is fed through the barbater, the mass is heated to 100-120°C, and hydrogen chloride is blown off until its content in the mass is not more than 0.5 wt. %. The liberated hydrogen chloride is removed through a reflux condenser and absorbed in an absorbing flask with water to obtain concentrated hydrochloric acid. After removal of hydrogen chloride, the reaction mass is cooled to 35-45°C and, with stirring, a hydrolytic mixture is quickly added containing hydrogen chloride in the form of a solution in a mixture of butyl alcohol with water, stirred for 3-4 hours at 75-85°C, then the organic phase is separated from water. From the product of hydrolysis - (silanol) at a residual pressure of not more than 20 kPa and a temperature of not more than 120°C, butyl alcohols formed during hydrolysis and excess solvent are distilled off to obtain a solution of polymethylphenylsiloxane with a concentration of 40-55 wt. %. The hydrolysis product "silanol" is placed in a four-necked reactor and a weighed portion of the diisocyanate from the above is added with stirring, the mixture is heated to 65-70 ° C and stirred at this temperature for 1-2 hours until the end of the modification, which is determined by a "drop test" on glass plate. The lacquer film should be transparent, without turbidity. A mixture of butyl alcohol, solvent and water is distilled off from the modification product at a residual pressure of not more than 20 kPa and at a temperature not exceeding 120°C to obtain a modified polymethylphenylsiloxane with a concentration of 50-60 wt. % or up to the requirement for the content of non-volatile substances.

The implementation of the method of obtaining polymethylphenylsiloxane varnish or its modified analogues using phenyltrichlorosilane in an amount equal to 20 wt. % by weight of methyltrichlorosilane, leads to the production of polymethylphenylsiloxane with optimal acid number and film drying time.

With an increase in the concentration of water in a water-butanol-xylene solution above the indicated molar ratios, gel formation is observed during hydrolytic esterification, an increase in the amount of alcohol and a decrease in the proportion of xylene leads to unstable results in drying the film of the final product.

Carrying out the hydrolysis of a solution of oligomethylphenylbutoxysilanes with a solution of hydrogen chloride in a water-butanol-xylene mixture promotes the formation of polymethylphenylsiloxane structures that do not contain gel and are stable during storage. At a concentration of hydrogen chloride in the hydrolyzing mixture of 15-17 wt. %, the optimal drying time of the varnish film is no more than 2 hours, and with an increase in concentration above 17 wt. % gel formation is observed.

The main advantage of the method according to the invention is that carrying out the process of obtaining polymethylphenylsiloxane varnish, it was possible to obtain an organosilicon polymer with urethane fragments, which make it possible to obtain a varnish film with increased elasticity and adhesive strength, resistance to water and gasoline.

For the object of comparison in terms of the properties of the lacquer film, polymethylphenylsiloxane lacquer according to the prototype was selected and the physical and mechanical properties of the films were tested in the preparation of enamel based on polymethylphenylsiloxane lacquer and its modified analogues.

Synthesis conditions and characteristics of the obtained products are presented in table. 1. Characteristics of the lacquer film are given in table. 2.

As can be seen from the research results, the polymethylphenylsiloxane varnish with urethane fragments obtained by the proposed method has high physical and mechanical properties and can serve as the basis for creating formulations of paints and varnishes.

Claims (1)

A method for producing a polyorganosiloxane varnish, including esterification of methyltrichlorosilane in a mixture with 20 wt.% phenyltrichlorosilane in a water-butanol-xylene solution, removal of the formed hydrogen chloride, hydrolysis of the esterification products, separation of the organic layer and distillation of excess solvent, characterized in that the product of hydrolysis - silanol before the solvent is distilled off, diisocyanate is introduced into the organic layer in an amount of 0.05-0.15 mol of diisocyanate per 1 mol of the starting methyltrichlorosilane, while esterification is carried out at a molar ratio of methyltrichlorosilane:butanol:water equal to 1:2.5:0.6, and hydrolysis is carried out with a solution containing 15-17 wt.% hydrogen chloride, 1-4 wt.% butanol, up to 100 wt.% water.