RU2000104467A - METHOD FOR PRODUCING POLYorganorganosiloxanes by Hydrolysis of Organohalosilanes - Google Patents

Claims (16)

1. The method of producing polyorganosiloxanes by hydrolysis of organohalosilanes of the formula (I) RaR ¹ bSiXc, in which R, R ¹ are the same or different radicals and are hydrogen or linear or branched C ₁ -C ₆ alkyls, C ₆ -C ₁₂ aryls, alkylaryls or aralkyls, X is halogen, and a + b + c = 4, and 0 <c <4; characterized in that at least three successive hydrolysis steps (1), (2), (3) are carried out, in which the reaction medium has an increasing hydrolysis effect on the organohalosilanes of formula (I), and, if necessary, at least one coalescence step ( 4), while stage (1) is hydrolysis under pressure in the presence of a saturated aqueous solution of S ₁ hydrogen halide, at pressure and temperature of the reaction medium, and a liquid consisting of water is used as a water source in stage (3 ₁ ) of deep hydrolysis water that does not contain or practically does not contain dissolved substances, and / or from one or more aqueous solutions of hydrogen halide.  2. The method according to p. 1, characterized in that it is carried out in a continuous mode. 3. The method according to p. 2, characterized in that the stage (1) hydrolysis under pressure consists of at least one hydrolysis (1 ₁ ) organohalosilanes of the formula I, leading to the formation of a crude hydrolyzate having at least three phases, which are :
1 - gas phase formed by gaseous hydrogen halide under pressure,
2 - siloxane fluid product F ₁ , consisting mainly of linear α, ω-dihalogenated linear oligomers and, possibly, to a lesser extent, cyclic oligomers,
3 - the aqueous phase, including a saturated solution of S ₁ hydrogen halide;
at least one gas / liquid separation (1 ₂ ) to form gaseous hydrogen halide under pressure, and a mixture F ₁ / S _{1 ′} ;
at least one liquid / liquid separation (1 ₃ ) to obtain a product F ₁ and a solution S _{1 ′} , wherein S _{1 ′ is} mainly recycled to stage (1 ₁ );
if necessary, at least one purification (1 ₄ ) of the gas obtained in stage (1 ₂ ), preferably by condensation;
and if necessary, at least one additional degassing of the product F ₁ obtained in stage (1 ₃ ), preferably, decompression. 4. The method according to p. 3, characterized in that the stage (1 ₁ ) of the hydrolysis is carried out with stirring in at least one closed reactor at a temperature of from 10 to 70 ^o C and at a controlled pressure of gaseous hydrogen halide, greater than or equal to 0.10 MPa, preferably from 0.15 to 1 MPa; while the mass ratio of the phases when applying RM1 = aqueous phase / organohalosilane of the formula (I) is greater than or equal to 2, preferably from 3 to 15. 5. The method according to p. 3 or 4, characterized in that the duration of the hydrolysis reaction of stage (1 ₁ ) is from 30 to 5 minutes, preferably from 1 to 2 minutes. 6. The method according to any one of paragraphs. 1-5, characterized in that stage (2) includes at least one wet hydrolysis (2 ₁ ), carried out with stirring, at a temperature of 10 - 50 ^o C, at which the siloxane fluid product F ₁ leaving stage (1) is subjected to the action of a concentrated aqueous solution S _21, the solute of which is the hydrogen halide, the concentration of this solute in S ₂₁ constitutes a part of the reference saturation concentration (Csr) of the same solute in an aqueous solution under the same conditions of temperature and pressure at this part of it is 45-75%, preferably 50-72% of Csr, and the mass ratio of the feed phases RM2 = aqueous phase / fluid F ₁ is adjusted product to a value higher than or equal to 1.5, preferably from 2 to 10 so in order to ensure the hydrolysis of the ≡SiX bonds of the siloxane product F ₁ at a level of at least 95%, preferably at least 98%, and thereby obtain a siloxane product F ₂ , consisting mainly of linear α, ω-dihydroxylated or α , ω-dihalogenated oligomers and possibly to a lesser extent cyclic oligomers. 7. The method according to p. 6, characterized in that the duration of the reaction of wet hydrolysis (2 ₁ ) is from 4 to 20 minutes, preferably 7-12 minutes 8. The method according to p. 6 or 7, characterized in that stage (2) further includes at least one separation operation (2 ₂ ), preferably by decantation of the flowing siloxane product F ₂ leaving step (2 ₁ ), and concentrated aqueous solution S ₂₂ , and this solution is mainly at least partially recycled to the hydrolysis step under pressure (1 ₁ ) of step (1) and / or to the wet hydrolysis step (2 ₁ ) of step (2) as an addition of hydrolysis water . 9. The method according to any one of paragraphs. 1-8 or p. 6, characterized in that stage (3) includes at least one treatment (3 ₁ ) by deep hydrolysis of the siloxane fluid product F ₂ obtained in stage (2), and the amount of F ₂ water and / or S ₃ and, if necessary, S ₄ used in step (3 ₁ ) are adjusted so that the mass ratio of the phases when feeding PM3 = aqueous phase / flowing product F ₂ (acidic silox) is greater than or equal to 1.5, preferably ranged from 2 to 10, and the specified processing (3 ₁ ) thus allows to complete the hydrolysis of residual bonds ≡Si-X of the product F ₂ , which is then converted into a siloxane fluid product F ₃ , consisting mainly of linear α, ω-dihydroxylated oligomers and, to a lesser extent, of cyclic oligomers. 10. The method according to p. 9, characterized in that stage (3 ₁ ) occurs at a temperature above or equal to 60 ^o C, preferably 70-100 ^o C and even more preferably 80-90 ^o C. 11. The method according to p. 9, characterized in that stage (3) includes, in addition, at least one separation operation (3 ₂ ), preferably by decantation of the siloxane fluid product F ₃ leaving stage (3 ₁ ), and aqueous phase, and this last, after receipt, at least partially recycled to at least the stage (3 ₁ ) and, if necessary, the stage (2 ₁ ). 12. The method according to any one of paragraphs. 1-11, characterized in that it includes a step (4) of coalescence of the product F ₃ leaving step (3 ₂ ), which consists mainly in passing the product F ₃ through a porous material so as to remove droplets of the acidic aqueous phase contained in this product and obtain, on the one hand, a flowable siloxane product F ₄ , consisting mainly of linear α, ω-dihydroxylated oligomers with a residual halogen content of less than or equal to 10 parts per million, preferably 2 parts per million, and to a lesser extent from cyclic oligomers, On the other hand, an aqueous phase S ₄ which, if desired, recycled to the preceding step, preferably in step (3 _1).  13. The method according to p. 12, characterized in that the porous material is selected from the following group consisting of precipitated silicas, porous woven or non-woven carriers, preferably based on glass fibers, polymer fibers, zeolites, and mixtures thereof. 14. The method according to any one of paragraphs. 9-13, characterized in that the siloxane fluid products F ₃ and F ₄ have a viscosity at 25 ^° C, lower or equal to 50 MPa • s, preferably 40 MPa • s, and even more preferably from 25 to 35 MPa • s.  15. The method according to any one of paragraphs. 1-14, characterized in that the halogen X = CL. 16. The method according to p. 15, characterized in that the source organohalosilane is Me ₂ SiCl ₂ , MeHSiCl ₂ or Me ₃ SiCl.