Patent ID: 6235834
Filing Date: 2001-05-22
Classification: C08G

Abstract:
A method of preparing an emulsion containing particles of an organopolysiloxane polymer with an average particle diameter of at least one micron (.mu.m) comprising: (i) combining a silanol endblocked siloxane oligomer, water, and a nonionic or anionic surfactant; (ii) emulsifying the silanol endblocked siloxane oligomer to form particles with an average particle diameter of at least one micron (.mu.m) by agitating or shearing the ingredients; (iii) adding a condensation specific acid catalyst; (iv) polymerizing the silanol endblocked siloxane oligomer to form an organopolysiloxane polymer; and (v) continuing polymerizing step (iv) until the resulting organopolysiloxane polymer has attained the desired increase in viscosity; the condensation specific acid catalyst being a dialkyl sulfonic acid catalyst which is selected from the group consisting of dialkyl benzene sulfonic acids of the formula R.sub.2 C.sub.6 H.sub.3 SO.sub.3 H, dialkyl naphthalene sulfonic acids of the formula R.sub.2 C.sub.10 H.sub.5 SO.sub.3 H, acidified salts of dialkyl benzene sulfonic acids of the formula R.sub.2 C.sub.6 H.sub.3 SO.sub.3 M, and acidified salts of dialkyl naphthalene sulfonic acids of the formula R.sub.2 C.sub.10 H.sub.5 SO.sub.3 M, where R represents an alkyl group having 1-20 carbon atoms, and M represents ammonium NH.sub.4.sup.+ or an alkali metal; the amount of water used for preparing the emulsion being 10-90 percent by weight based on the total weight of the emulsion.