| 摘要 |
PURPOSE: Provided is a method of emulsion polymerization of siloxane oligomers in which the particle size of siloxane polymer formed in the emulsion can be decreased by decreasing the amount or concentration of ionic surfactant, such as anionic surfactant or cationic surfactant, used in preparing the emulsion. CONSTITUTION: The method of preparing emulsions containing particles of siloxane polymers comprises: (I) forming a mixture containing (a) a cyclosiloxane or mixture of cyclosiloxanes, (b) an ionic surfactant or mixture of ionic surfactants, (c) no nonionic surfactant, (d) water, and (e) a siloxane polymerization catalyst, with the provisos (i) that the cyclosiloxane is not mechanically emulsified before addition to mixture (I); (ii) that before, or at the point when, the cyclosiloxane contacts the catalyst, the cyclosiloxane is present in mixture (I) as droplets having an average diameter greater than 10 micron/10,000 nanometer; and (iii) mixture (I) is maintained at a temperature necessary to obtain the desired polymer particle size prior to, or at the time, when the catalyst and cyclosiloxane both become present in mixture (I); and (II) heating and agitating mixture (I) at said temperature to obtain polymerization and to consume the droplets of siloxane oligomer to form an emulsion of siloxane polymer particles.
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