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US 7,745,533 B2Granted
Manufacture of stable low particle size organopolysiloxane emulsion
AssigneeWacker Chemie AG
InventorAmit Kumar Paul
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Abstract
Stable high viscosity organopolysiloxane emulsions with particle sizes up to 150 nanometer may be made in a simple and cost-effective manner employing a standard homogenizer, and optional subsequent polymerization of the organopolysiloxan at controlled temperature. A combination of non-ionic emulsifier together with an at least one anionic emulsifier is employed, having an HLB value 12-15, while maintaining a temperature up to 50° C.
Claims12
A process for the manufacture of a stable aqueous organopolysiloxane emulsion having a particle size (D50 value) up to 150 nanometers, comprising:
- i) providing a formulation comprising (a) an organopolysiloxane of the formula I:
- where R1 is hydroxyl group or a C1-8 alkoxy group, and where R, which are the same or different, are monovalent hydrocarbon radicals, and x is an integer from 1 to 100 or mixtures thereof in an amount of 20 to 80% by. wt. (b) water in an amount of 5 to 30% by wt. (c) non-ionic emulsifier(s) having an HLB in the range of 10-19 in amounts of 1 to 25% by wt. and (d) at least one anionic emulsifier selected from organic sulfonic acids having an HLB in the range of 8-19 in an amount of 1 to 15% by. wt.;
- ii) homogenizing the formulation of (i) while maintaining a temperature in the range of 10°C to 40°C so as to increase organopolysiloane polymer growth rate or rise in polymer viscosity to at least 20,000 mPa-s, and
- iii) neutralising the emulsion by alkali to a pH range of 6-8.
1 more element
Dependencies are inferred from the claim text.