Rhodia Chimie

Christian Bordone

Jean-Roger Desmurs

G&eacute;rard Mignani

Jos&eacute; Martins

L&eacute;on Ghosez

The invention concerns a method for preparing polyorganosiloxanes (POS) by (a) condensation polymerisation of monosilanes and/or acyclic siloxanes bearing reactive Si&mdash;OR units with R&boxH;H, or alkyl, or by (b) redistribution/condensation polymerisation of siloxane compounds based on cyclosiloxanes and/or acyclic siloxanes capable of bearing reactive Si&mdash;OR units such as defined above, Si&mdash;H or Si-alkenyl units, in the presence of an acid catalyst. Said method is characterised in that it consists in using at least a catalyst of the following formula (I) (C F SO ) A wherein: m is an integer not less than 1; n is an integer equal to 1 or 2 and A represents OH, NH or NH with: (i) n&equals;1 and A&equals;OH or (ii) n&equals;1 and A&equals;NH or (iii) n&equals;2 and A&equals;NH; provided that, when said catalyst corresponds to formula (I) (i), it is brought in the presence of an inert support in mass amount QM, expressed in weight % relative to the total mass (a) of monosilanes and/or acyclic siloxanes or (b) of the initial siloxane compounds, which is not more than 1.5. The invention also concerns a catalyst for use in the preparation of POS by said process (a) or (b) consisting of at least a compound selected among the compound of formula I(ii), the compound of formula I(iii) and mixtures thereof.

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Rillieux-La-Pape, France

Christian Bordone