Aqueous silicone emulsion for imparting water repellency
Aqueous silicone emulsions are disclosed containing a phenyl silsesquioxane resin, an alkoxysilane, a hydroxy terminated polydialkylsiloxane, and an emulsion of an aminofunctional polysiloxane. The silicone emulsions are useful for imparting water repellency to various surfaces, and in particular, inorganic building surfaces.
1. An aqueous silicone emulsion composition comprising;
10-50 wt % of A) a phenyl silsesquioxane resin,
2-15 wt % B) an alkoxysilane,
2-15 wt % C) a hydroxy terminated polydialkylsiloxane comprising the average formula
[R 9 2 Si(OH)O 1/2 ][R 9 2 SiO 2/2 ] z [SiR 9 2 (OH)O 1/2 ],
where R 9 is an alkyl group having 1-6 carbon atoms and z is greater than one,
0.5-10 wt % D) an emulsifier, and
1-10 wt % of E) an emulsion of an aminofunctional polysiloxane, and sufficient water to sum to 100 wt %.
2. The aqueous silicone emulsion composition of claim 1 wherein the phenyl silsesquioxane resin comprises at least 40 mole % of siloxy units having the formula
(R′ 2 SiO 2/2 ) x and (C 6 H 5 SiO 3/2 ) y ,
where x and y have a value of 0.05 to 0.95, and
R′ is a monovalent hydrocarbon group having 1 to 8 carbon atoms.
3. The aqueous silicone emulsion composition of claim 1 wherein the alkoxysilane is of the formula R 8 a Si(OR 9 ) (4-a) , where R 8 is an alkyl group having 1-30 carbon atoms, R 9 is an alkyl group having 1-6 carbon atoms, and the subscript a is 1 or 2.
4. The aqueous silicone emulsion composition of claim 1 wherein the emulsifier is a combination of polyoxyethylene fatty alcohols having a combined HLB of 11-15.
5. The aqueous silicone emulsion composition of claim 1 wherein the emulsion of an aminofunctional polysiloxane is prepared by emulsion polymerization of cyclosiloxanes and an amino functional alkoxy silane.
6. A composition for imparting water repellency to a surface comprising the aqueous silicone emulsion composition of claim 1 .
7. A method for imparting water repellency to a surface comprising applying a coating of the aqueous silicone emulsion composition of claim 1 to a surface.
8. The method of claim 7 wherein the surface is an inorganic substrate selected from the group of concrete, mortar, brick, stone, gypsum, stucco, terra cotta, adobe, plaster, limestone, marble, porcelain, and tile.
9. The aqueous silicone emulsion composition of claim 1 wherein the emulsion contains;
30-45 wt % of A) the phenyl silsesquioxane resin,
6-15 wt % of B) the alkoxysilane,
10-15 wt % or C) the hydroxy terminated polydialkylsiloxane,
1-5 wt % of D) the emulsifier, and
4-8 wt % of E) the emulsion of an aminofunctional polysiloxane, and sufficient water to sum to 100 wt %.
10. A process for preparing an aqueous silicone emulsion composition, said process comprising;
I) combining
10-50 wt % A) a phenyl silsesquioxane resin,
2-15 wt % B) an alkoxysilane,
2-15 wt % C) a hydroxy terminated polydialkylsiloxane comprising the average formula
[R 9 2 Si(OH)O 1/2 ][R 9 2 SiO 2/2 ] z [SiR 9 2 (OH)O 1/2 ],
where R 9 is an alkyl group having 1-6 carbon atoms and z is greater than one,
0.5-10 wt % D) an emulsifier,
and water to form a dispersion,
II) shearing the dispersion to form an emulsion,
III) admixing
1-10 wt % E) an emulsion of an aminofunctional polysiloxane to the emulsion, and sufficient water to sum to 100 wt % is used in the process.
11. An aqueous silicone emulsion composition prepared according to the process of claim 10 .
12. The process of claim 10 wherein
30-45 wt % of A) the phenyl silsesquioxane resin,
6-15 wt % of B) the alkoxysilane,
10-15 wt % of C) the hydroxy terminated polydialkylsiloxane,
1-5 wt % of D) the emulsifier, and
4-8 wt % of E) the emulsion of an aminofunctional polysiloxane, and sufficient water to sum to 100 wt % is used in the process.