PROCESS FOR PREPARING ORGANOPOLYSILOXANES BRANCHED SEVERAL TIMES AND WHICH CONTAIN SILICIUM-FUNCTIONAL GROUPS, AND THE PRODUCT THUS OBTAINED

摘要

In the preparation of multi-branched equilibrated mixed acyloxy-containing and chlorine-containing organo polysiloxanes by reacting a chlorosilane of the formula RaSiCl4-a wherein a=0 or 1, with at least one organosiloxane containing units of the formula R2R'SiO1/2, RR'SiO, R'SiO3/2 and/or SiO2 wherein R is hydrogen or an aliphatic, aromatic, saturated or unsaturated, optionally halogen-substituted or cyano-substituted monovalent hydrocarbon radical with up to 8 C atoms and R' is chlorine, hydroxyl, hydrogen or an aliphatic, aromatic, saturated or unsaturated, optionally halogen-substituted or cyano-substituted monovalent hydrocarbon radical with up to 8 C atoms, in proportions such that the number of all the SiCl groups is always at least 1.5 times greater than the number of SiOH groups, in the presence of (a) fluoroalkanesulphonic acid or salt thereof and (b) relative to the chlorine atoms bonded to silicon, at least 1.1 times the molar amount of a concentrated monobasic carboxylic acid, the improvement which comprises adding a portion of the carboxylic acid in a first stage, and in a second stage adding the balance of the carboxylic acid along with water in the amount required to achieve the desired degree of branching. Advantageously the fluoroalkanesulphonic acid is a perfluoroalkanesulphonic acid containing up to 8 carbon atoms, and it or its salt is employed in about 0.05 to 1.5% by weight of chlorosilane plus organosilane, the carboxylic acid is acetic acid, the reaction is carried out at a temperature up to about 135 DEG C., the organosilane comprises a cyclosiloxane of the formula (RR'=SiO)3-5, and about half the acetic acid is added in each stage.