US 8,013,059 B2 · Synthesis of hydroxylated polyorganosiloxanes by hydrolysis/condensation of halosilanes and apparatus therefor

Abstract

A method for hydrolyzing/condensing, by acid catalysis, silanes bearing hydrolyzable groups, preferably halogenosilanes and more preferably still chlorosilanes, in a polyphase reaction medium (preferably biphasic), includes contacting the silanes bearing the hydrolyzable groups with water, buffer solution and neutralizing agent, while stirring, then in separating the aqueous phase from the organic phase, which contains the hydrolysis/condensation products, namely hydroxylated polyorganosiloxanes; such method is characterized by (a) employing intensively stirring means producing, in the reaction medium, an agitation at least equivalent to that induced by a shearing corresponding to that provided by a rotor whereof the peripheral speed is not less than 8 m.s−1, preferably not less than 10 m.s−1, and more preferably still ranging between 15 and 20 m.s−1, enabling thus organic phase droplets to be formed, of d32 less than 500 μm; and (b) ensuring that the silanes/aqueous phase mass fraction is not less than 0.05, preferably not less than 0.10, and more preferably still ranging from 0.5 to 2.0.

Claims18

Dependent claims

A process for the preparation of a hydrolysis/condensation product that exhibits a level of OH (tOH)>5% with respect to the total weight of the hydrolysis/condensation product, by acid catalysis, of silanes bearing hydrolyzable substituents, in a multiphase reaction medium, the process comprising:

(1) forming a reaction medium in a continuous loop reactor comprising contacting said silanes bearing hydrolyzable substituents with water, buffer and neutralizing agent wherein said silanes are introduced into the reactor in an organic phase and the water, buffer and neutralizing agent are introduced into the reaction medium in an aqueous phase, and the aqueous phase and the organic phase are introduced into the reactor at a flow rate wherein the aqueous phase flow rate is between 3.6 and 10 times the flow rate of the organic phase, and the silanes/aqueous phase fraction by weight is greater than or equal to 0.05;
(2) stabilizing the pH of the reaction medium between 7 and 12;
(3) stirring said reaction medium with intensive stirring means to form droplets of organic phase having a Sauter mean diameter d32 of less than 500 μm;
and
(4) separating the aqueous phase from the organic phase, where the organic phase comprises the hydrolysis/condensation products,
wherein said silanes are hydrolyzed in the multiphase reaction medium before the coalescence of the organic droplets and the residence time of the reactive medium in the reactor is one minute or less.

3 more elements

Dependencies are inferred from the claim text.

Synthesis of hydroxylated polyorganosiloxanes by hydrolysis/condensation of halosilanes and apparatus therefor

Life of this patent

Synthesis of hydroxylated polyorganosiloxanes by hydrolysis/condensation of halosilanes and apparatus therefor

Life of this patent

Abstract

Claims18