| abstract |
Dialkyl sulfonic acid catalysts such as dialkylnbenzene sulfonic acids, dialkyl naphthalene sulfonicnacids, salts of dialkyl benzene sulfonic acids and saltsnof dialkyl naphthalene sulfonic acids, are used tonprepare emulsions containing particles ofnorganopolysiloxanes having an average particle diameternin the emulsion of at least one micron (µm). A silanolnendblocked siloxane is used as an oligomer and has thenstructuren nwherein R1 to R6 are alkyl or aryl groups, for example,nmethyl, ethyl, propyl, butyl, pentyl, hexyl and phenyl;nand n has a value such as to provide oligomers with anviscosity ranging from 20 to 100,000 centipoise (mPa·s).nThe emulsified oligomer is then polymerized with thencatalyst to form an organopolysiloxane polymer having anviscosity which can be as high as 10 million centipoisen(mPa·s). |