Water repellent organosilicon materials
View Patent ↗A process for increasing the hydrophobicity of a porous product by treating the product, or a composition providing for the product, with a water repellent material, characterized in that the porous product or a composition providing the product, is treated with an aqueous suspension of microcapsules where the microcapsules comprise a water repellent organosilicon core material selected from an organosilane, a partially condensed organosilane and a branched siloxane resin, and a shell of a silicon-based network polymer comprising silica units.
1. A process for increasing the hydrophobicity of a porous product by treating the product, or a composition providing for the product, with a water repellent material, characterised in that the porous product or a composition providing the product is treated with an aqueous suspension of microcapsules where the microcapsules comprise a water repellent organosilicon core material selected from the group consisting of an organosilane, a partially condensed organosilane, and a branched siloxane resin, and a shell of a silicon-based network polymer comprising silica units wherein the product is selected from the group consisting of cementitious substrates, cementious compositions, clay-based bricks, clay-based compositions, gypsum-based substrates, lime-based substrates, and wood-based substrates.
2. A process according to claim 1 wherein the water repellent organosilicon core material is an organosilane comprising at least one silicon-bonded alkyl group having 1 to 30 carbon atoms, or a partial condensation product of such an organosilane.
3. A process according to claim 2 wherein the water repellent organosilicon core material is an alkyltrialkoxysilane in which each alkoxy group has 1 to 4 carbon atoms.
4. A process according to claim 2 wherein the silicon-bonded alkyl group is an octyl group.
5. A process according to claim 1 wherein the water repellent organosilicon core material is a siloxane resin comprising siloxane units of the formula RSiO 3/2 where R represents an alkyl group.
6. A process according to claim 5 wherein the groups R in the siloxane units of the formula RSiO 3/2 comprise alkyl groups having 1 to 30 carbon atoms.
7. A process according to claim 1 wherein the water repellent organosilicon core material is a siloxane resin comprising siloxane units of the formula RSiO 3/2 where R represents an aryl group.
8. A process according to claim 1 where the microcapsules are obtained by the addition of tetraalkoxysilane to an aqueous emulsion of a water repellent organosilicon material selected from the group consisting of an organosilane, a partially condensed organosilane, and a branched siloxane resin, whereby the tetraalkoxysilane condenses and polymerises at the interface of droplets in the emulsion to form microcapsules.
9. A process according to claim 8 where a quaternised aminoalkylalkoxysilane is added to the aqueous emulsion before or simultaneously with the tetraalkoxysilane.
10. A process according to claim 1 wherein microcapsules comprising a water repellent organosilicon core material selected from the group consisting of an organosilane, a partially condensed organosilane, and a branched siloxane resin, and a shell of a silicon-based network polymer comprising silica units are added to the cementitious composition and the composition is shaped and hardened to form a cementitious product.
11. A process according to claim 10 for making a water repellent aerated cement product, wherein the microcapsules are added to a foamable cementitious composition.
12. A process according to claim 1 wherein microcapsules comprising a water repellent organosilicon core material selected from the group consisting of an organosilane, a partially condensed organosilane, and a branched siloxane resin, and a shell of a silicon-based network polymer comprising silica units are added to the clay based composition and the composition is shaped and hardened to form a brick or tile product.