Process for the manufacture of multifunctional polyorganosiloxanes (POSs) by dehydrocondensation and hydrosilylation, and device for carrying out this process

A process for the continuous or semi-continuous manufacture of multifunctional polyorganosiloxanes (POS)(III), from a POS (I) comprising SiH groups and according to a reaction mechanism involving a dehydrocondensation which allows functionalization by the functionality (Fo1) and a hydrosilylation of at least one unsaturated compound which is a precursor of a functionality (Fo2) on the POS (III), said process comprising the steps of:

• a) continuously supplying with reactants at least one continuous reactor A comprising a chamber (1) comprising a top chamber (3) and at least one bottom reaction chamber (2) provided with at least one plate (40) which constitutes the base of a main compartment (5) comprising an upper part and a lower part, the main compartment (5) being in communication with the top chamber (3) via its upper part, the reactants being supplied by at least one pipe (11, 12) emerging into the main compartment (5), the reactants comprising:
• at least one POS (I) containing SiH groups,
• at least one functional reactant of formula:
• HXR containing labile hydrogen, wherein X is O or S, and R is a linear or branched alkyl radical having from 1 to 15 carbon atoms, and
• a catalyst comprising a transition metal, said reactor A being the site of a dehydrocondensation leading:
• to a liquid reaction medium comprising a POS (II) having residual SiH groups and groups SiFo1(Fo1=XR),
• to reactant HXR, and
• to a gas containing hydrogen and optionally, gaseous reactant HXR,
• b) allowing a continuous removal and recovery, from the reactor A, of the gas containing hydrogen as it is formed, with evacuation means, comprising the top chamber (3),
• c) collecting the liquid reaction medium, provided that this medium contains the POS (II) containing SiH/SiFo1 groups and the catalyst, with at least one overflow member (13)in the main compartment (5), said overflow member placing said compartment in communication with the lower level of the bottom chamber (2),
• d) transferring the liquid reaction medium from the reactor A to at least one reactor B, with at least one pipe connecting the lower level of the bottom chamber (2) to the reactor B,
• e) carrying out a hydrosilylation of at least one unsaturated functional compound by the residual SiH groups of the POS (II), in the reactor B, optionally provided with stirring means (22), so as to obtain the POS (III) containing SiFo1 and SiFo2 groups, separating hydrogen as it is formed from other gases with means (24) providing the reactor B, for recovering vent gases, and
• f) recovering the POS (III) containing SiFo1/SiFo2 groups thus formed.