Pituitous silicone emulsions
The present invention provides methods for preparing emulsions of silicone fluids having pituitous rheological properties. The present invention also provides emulsions of a silicone fluid having pituitous rheological properties and composition comprising the emulsions. The compositions include, but are not limited to, personal care compositions and compositions for hair shampoo, hair conditioner, hair treatment composition, or skin care product.
1. A method for preparing an emulsion of a silicone fluid having pituitous rheological properties, the process comprising:
(A) forming an oil-in-water emulsion by:
(i) combining a carrier fluid, a linear SiH-containing organopolysiloxane having less than 1 wt % of T and Q units and having a degree of polymerization of from 8 to 500 and an alkenyl-containing organopolysiloxane having a degree of polymerization of from 500-10,000 to form a mixture,
(ii) adding a surfactant to the mixture, and
(iii) adding water and mixing to form an oil-in-water emulsion, wherein the mixture of the carrier fluid, the SiH-containing organopolysiloxane and the alkenyl-containing organopolysiloxane forms an oil phase of the oil-in-water emulsion; and
(B) reacting the SiH-containing organopolysiloxane and the alkenyl-containing organopolysiloxane in the oil phase of the emulsion formed in (A)(iii) in the presence of a hydrosilylation catalyst to form an emulsion of a silicone fluid that does not comprise gels and has pituitous rheological properties and wherein the emulsion comprises from 40 to 95 wt % of said silicone fluid.
2. The method of claim 1 , wherein the alkenyl-containing organopolysiloxane is vinyl terminated.
3. The method of claim 1 , wherein the alkenyl-containing organopolysiloxane is dimethyl vinyl terminated.
4. The method of claim 1 , wherein the SiH-containing organopolysiloxane has 2 to 10 pendant SiH sites.
5. The method of claim 1 , wherein the oil phase comprises from 40% to 80% by weight of the emulsion formed in (A)(iii).
6. The method of claim 1 , wherein the surfactant is non-ionic, cationic, or anionic.
7. The method of claim 6 , wherein the surfactant comprises from 0.01% to 10% by weight of the emulsion formed in (A)(iii).
8. The method of claim 1 , wherein the molar ratio of vinyl:SiH is from 0.01 to 10.
9. The method of claim 1 , wherein the carrier fluid comprises 5% to 80% by weight of the emulsion of a silicone fluid having pituitous rheological properties.
10. The method of claim 1 , wherein the carrier fluid is a silicone fluid, an organic solvent, an organic oil, or any combination thereof.
11. The method of claim 1 , wherein the silicone fluid comprises a branched organopolysiloxane.
12. The method of claim 1 , where the pituitous rheological properties of the silicone fluid are determined from a plot of normal stress in Pascals vs a perpendicular shear rate in sec-1 wherein the plot has an average slope that is greater than 3.6.
13. The method of claim 1 , wherein the emulsion of a silicone fluid having pituitous rheological properties further comprises a silicone resin and/or silicone elastomer.
14. The method of claim 1 , wherein the emulsion comprises from 50 to 95 wt % of said silicone fluid.
15. The method of claim 1 , wherein the emulsion comprises from 60 to 95 wt % of said silicone fluid.
16. The method of claim 1 , wherein the linear SiH-containing organopolysiloxane and linear an alkenyl-containing organopolysiloxane both have less than 0.1 wt % of T and Q units.
17. The method of claim 1 , wherein the linear SiH-containing organopolysiloxane has a degree of polymerization of from 25-400.
18. The method of claim 1 , wherein the alkenyl-containing organopolysiloxane is linear and has less than 1 wt % of T and Q units.