CS243186B1 - Method of organo-siloxane resins - Google Patents

Abstract

Method for producing organosiloxane resins by silylation of a silicic acid solution in polar and non-polar solvents. Silylation is carried out with monofunctional and difunctional organochlorosilanes of the general formula R1R2R3S1CI and R1R2SÍCI2, where R1R2R3 denotes methyls or vinyls, with at least one of the substituents Rj, R2 or R3 having to be vinyl. The individual components are allowed to react in proportions of 20 to 50 wt. % SiO2, 50 to 70 wt. % monofunctional organochlorosilanes and 1 to 20 wt. % difunctional organosilanes. Organosiloxane resins prepared according to the invention contain 0.5 to 10 wt. % vinyl groups. Aromatic solvents are used as non-polar solvents, aliphatic alcohols or ketones are polar solvents. Resins can be used as an additive to addition-curing mixtures to improve the mechanical properties of their vulcanizates.

Description

(54) A method for producing organosiloxane resins

Process for the production of organosiloxane resins by silylating a solution of silicic acid in an environment of polar and non-polar solvents. The silylation is carried out with one or two functional organochlorosilanes of the general formula R1R2R3S1Cl and R1R2SiCl2, where R1R2R3 is methyl or vinyl, with at least one of R1, R2 or R3 being vinyl. The components are reacted in proportions of 20 to 50 wt. SiO2, up to 70 wt. % of one-functional organochlorosilanes and 1 to 20 wt. bifunctional organosilanes. The organosiloxane resins prepared according to the invention contain 0.5 to 10 wt. vinyl groups. Aromatic solvents are used as non-polar solvents, aliphatic alcohols or ketones are polar solvents.

The resins can be used as an addition to vulcanizing compositions in an addition manner to improve the mechanical properties of their vulcanizates.

The present invention relates to a process for the preparation of organosiloxane resins having unsaturated groups which can be added to the vulcanizing compositions in an addition manner in order to improve the mechanical properties of their vulcanizates. In the addition vulcanization process, a spatial network is formed by the addition of hydrogen of a crosslinking agent of polymethylhydrogensiloxane to the double bond of vinyl groups of polymers or resins.

The prior art process for the production of organosiloxane resins is accomplished by cosdrolysis and polycondensation of the organochlorosilane mixture, with a higher content of four-functional tetrachlorosilane in the reaction mixture forming a heterogeneous mixture of insoluble cross-linked resin and linear polydiorganosiloxane. Higher resin content The four-functional components can only be prepared in this way using tetralkoxysilane instead of tetrachlorosilane, as described, for example, in U.S. Patent Nos. 2,850,356 (Goodwin JT), Germany No. 1,244,401 (Modic FJ) or USSR No. 254,079. (Abromos LA).

According to the invention, these processes are overcome by a process for the production of organosiloxane resins with unsaturated groups. It is based on the fact that a silicic acid solution, for example a water glass solution, consisting of a sodium silicate solution having a SiO ₂ : Na ₂ O 3

3.5 acidified with mineral acids, subjected to silylation with mono- and bi-functional organoohorsilanes of the general formula R 1 R ₂ R ₃ SiCl and ^R 3 ^R 3 SiCl 3, where ^R 3 ^R 2 ^R 3 denotes methyl or vinyl, with at least one of R 1, R ₂ or R 3 being vinyl; the polar and non-polar solvents such as aliphatic alcohols and ketones or aromatic solvents, the individual components being reacted in proportions of 20 to 50 wt. SiO ₂ , 50 to 70 wt. % of one-functional organochlorosilanes and 1 to 2 wt. bifunctional organochlorosilanes.

According to a further feature of the invention, the vinyl group content of the resins is 0.5 to 10% by weight.

The advantage of the process for the production of the organosiloxane resins according to the invention is, in particular, that it enables the preparation of organosiloxane resins with a high concentration of four-functional siloxane units in a simple manner.

Water residues, a polar solvent, and a portion of the non-polar solvent are distilled off from the resulting organosiloxane resin solution to form a solution of the organosiloxane resin in the non-polar solvent.

Resins prepared in this manner containing 0.5 to 10 wt. % of vinyl groups can be added to the addition vulcanization compositions to improve the mechanical properties of their vulcanizates. Addition of 5 to 50 wt. Resins for alpha, omega-divinylpolydimethylsiloxanes are produced by pouring transparent mixtures that can be used as embedding and coating materials in electrical engineering. The tensile strength of the addition vulcanizates of these mixtures reaches 5 MPa, which is 20 times higher than the addition vulcanizates of alpha, omega-divinylpolydimethylsiloxanes without the addition of resin,

The invention is described in more detail by means of two exemplary embodiments.

Example 1

A silicic acid solution is prepared in the reaction vessel by adding dilute water glass (500 wt.% Waterglass containing 26 wt.% SiO ₂ + 800 wt.% Water) with stirring to 810 wt. d.

16.5% wt. hydrochloric acid. 500 wt. d. ethanol. 100 wt. d. trimethylchlorosilane and 140 wt. d. dimethylvinylchlorosilane and 80 wt. d. dimethyldichlorosilane in 150 wt. d. xylene. The resulting mixture was heated to reflux. hours, then diluted with 300 wt. d. xylene and distributed in a separatory funnel. After separation of the upper layer, water, ethanol and xylene are distilled off until the remaining solution of organosiloxane resin in xylene in the digester has a content of 50% by weight. dry matter. The resin contains 38.9 wt. SiO ₂ , 22.2 wt. (CHgIgSiOg 25.4 wt% (CH3) ₂ ⁼ CHSiOq, 5a)

13.6% wt. (CH ₃ ) ₂ SiO.

Example 2

The process for preparing the resin solution is the same as in Example 1. 1050 wt. d. water glass + 1 160 wt. d. water, 810 wt. d. 16.5 wt. hydrochloric acid, 980 wt. d. of isopropanol, 391 wt. d. trimethylchlorosilane + 85 wt. d. methylvinyldichlorosilane and 750 wt. d. xylene.

An organosiloxane resin solution containing 50 wt. the solids are diluted with xylene to 30 to 40 wt. of dry matter and 340 wt. d. trimethylchlorosilane. The mixture was heated to reflux for 3 hours and then partitioned in a separatory funnel. The upper layer was washed with water at 60-70 ° C until its pH was 5-7. Trimethylsilanol, water hexamethyldisiloxane and excess xylene were distilled off from the upper layer until the resin solution in the digester contained 50 wt. The resin contains 31.3 wt. SiO 2, 62.7 wt. (CH 3) 6 SiO 6 and 6 wt. CH ₂ CH ₂ = CHSiO.

Claims (2)

SUBJECT OF THE INVENTION 1. A method for producing organosiloxane resins with unsaturated groups, characterized in that a solution of silicic acid, e.g. a solution of water glass, formed by a sodium silicate solution with a ratio of SiO ₂ : Na ₂ <0 3 to 3.5 acidified with mineral acids, is subjected to silylation with monofunctional and difunctional organochlorosilanes of the general formula RjR ₂ RjSiC1 and RjR ₂ SiC1 ₂ , where RjR ₂ Rj denotes methyls or vinyls, wherein at least one of the substituents RjR ₂ ^or ° must be vinyl, in the environment of polar and non-polar solvents, such as aliphatic alcohols and ketones or aromatic solvents, wherein the individual components are allowed to react in ratios of 20 to 50 wt. % SiC> ₂ , 50 to 70 wt. % monofunctional organochlorosilanes and 1 to 20 wt%, difunctional organochlorosilanes. 2. A method for producing organosiloxane resins according to item 1, characterized in that the content of vinyl groups in the resins is 0.5 to 10 wt.%.