| 主权项 |
1. A method for preparing an organopolysiloxane emulsion composition comprising the steps of:
(I) emulsifying a mixture to form a first emulsion composition, the mixture comprising (A) 100 parts by weight of an organopolysiloxane having the general formula (1):
HO(R12SiO)nH (1)wherein R1 is independently hydrogen or a substituted or unsubstituted monovalent hydrocarbon group of 1 to 20 carbon atoms and n is such a number that the organopolysiloxane may have a kinematic viscosity of 200 mm2/s to less than 2,000 mm2/s at 25° C., said organopolysiloxane having an octamethylcyclotetrasiloxane content of up to 1,000 ppm, (B) 1 to 8 parts by weight of a surfactant, and (C-1) 1 to 10,000 parts by weight of water, and
(II) optionally adding (C-2) 0 to 10,000 parts by weight of water and effecting emulsion polymerization of the first emulsion composition in the presence of (D) an acid catalyst, which is optional when component (B) is catalytic, at a temperature of lower than 40° C., thereby forming a target organopolysiloxane emulsion composition which contains an organopolysiloxane product having a viscosity of at least 300,000 mPa·s at 25° C. and an octamethylcyclotetrasiloxane content of up to 3,000 ppm and has an emulsified particle size of up to 500 nm. |
