Process for preparing silanol-functional specifically branched organopolysiloxanes and products produced thereby
AssigneeWacker Silicones Corporation
InventorEugene R. Martin
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Abstract
Star- and comb-type branched organosilicon compounds containing .omega.-terminated organopolysiloxane branches are readily synthesized by the catalyzed or uncatalyzed reaction of an at least tris(organyloxy)-functional organosilicon compound with a predetermined amount of substantially linear minimally disilanol-functional organopolysiloxane. Well defined, non-resinous, liquid products of low viscosity may be obtained.
Claims19
A process for the preparation of branched organosilicon compounds having on average three or more .omega.-silanol-terminated, substantially linear organopolysiloxane branches per molecule, said process comprising reacting
- a) an organyloxy-functional compound having y organyloxy groups per molecule wherein y.gtoreq.3, with
- b) from about 75 mol percent to about 125 mol percent of L/x mols per mol of organyloxy-functional compound of minimally disilanol-functional organopolysiloxanes compound containing 6 or more siloxy moieties, L calculated from
- L=(y-1)(x)+1
- where y has been defined previously and x is the number of organyloxy compound-derived moieties in said product molecules on average, said reacting taking place until the mol ratio M of measured silanol to branched groups is in the range of
- (a).multidot.(b/c)
- where a is in the range of about 0.75.ltoreq.a.ltoreq.1.6, b is the intended mol of silanol per gram of product, and c is the mol of branched groups per gram of product.
A process for preparing branched organosilicon compounds having minimally three branches, the branches comprising substantially linear, silanol-terminated organopolysiloxane polymers containing six or more siloxy moieties, said process comprising:
- a) selecting one or more organyloxy-functional organosilicon compounds having, on average, y organyloxy groups per molecule wherein y.gtoreq.3;
- b) reacting with the organyloxy-functional silicon compounds a) L/x mol of one or more minimally disilanol-functional organopolysiloxanes per mol of organyloxy-functional compound, where x is the desired number of organyloxy-functional organosilicon compound-derived moieties in the branched organosilicon compound product, and L=(y-1)x+1;
- c) obtaining a product mixture comprising in major part star-and/or comb-branched product organopolysiloxanes having a functionality of silanol-terminated branches of 2L-yx.
Dependencies are inferred from the claim text.