COATING COMPOSITIONS FOR HYDROPHOBIC FILMS AND ARTICLES HAVING HYDROPHOBIC SURFACES
This invention relates to a coating composition. The coating composition may include hydrophobized silica particles, a film-forming binder, and a solvent. The hydrophobized silica particles comprise porous silica particles having a pore diameter of about 80 or more which have been treated to form a hydrophobic coating on a surface of the porous silica particles.
1 . A coating composition, comprising:
hydrophobized silica particles;
a film-forming binder; and
a solvent;
wherein the hydrophobized silica particles comprise porous silica particles having a pore diameter of about 80 Å or more which have been treated to form a hydrophobic coating on a surface of the porous silica particles.
2 . The coating composition of claim 1 , wherein a weight ratio of the hydrophobized silica particles to the film-forming binder in the coating composition is at least about 1:2.5.
3 . The coating composition of claim 1 , wherein the solvent comprises one or more organic solvents or water.
4 . The coating composition of claim 1 , wherein a BET surface of the porous silica particles is less than about 800 m 2 /g.
5 . The coating composition of claim 4 , wherein the BET surface of the porous silica particles is less than about 750 m 2 /g.
6 - 7 . (canceled)
8 . The coating composition of claim 1 , wherein the hydrophobic coating on the surface of the porous silica particles is formed by contacting the porous silica particles with a hydrophobic silane or siloxane that contains at least one reactive functional group that undergoes a chemical reaction with surface silanol groups of the porous silica particles.
9 . The coating composition of claim 8 , wherein the hydrophobic silane or siloxane preferably has a weight averaged molecular weight of at least 200 daltons.
10 . (canceled)
11 . The coating composition of claim 8 , wherein the hydrophobic silane or siloxane is octadecyl trimethoxysilane, perfluorooctyltrimethoxysilane, polydimethoxysilane, or silanol terminated polydimethylsiloxane, more preferred is polydimethoxysilane.
12 - 15 . (canceled)
16 . The coating composition of claim 11 , wherein the hydrophobic silane is polydimethoxysilane.
17 . The coating composition of claim 1 , wherein the film-forming binder comprises one or more selected from the group consisting of C 2 -C 6 polyolefins; homopolymers of ethylenically unsaturated monomers containing C 8 -C 36 alkyl groups; and copolymers of ethylenically unsaturated monomers containing C 4 -C 36 alkyl groups, C 1 to C 36 alkyl vinyl ethers, vinyl esters of C 1 to C 36 carboxylic acids, and ethylenically unsaturated comonomers copolymerizable therewith; natural waxes; and synthetic waxes.
18 . The coating composition of claim 1 , wherein the film-forming binder comprises a fluorine-containing polymer and the solvent comprises one or more organic solvents.
19 . The coating composition of claim 18 , wherein the fluorine-containing polymer is polytetrafluoroethylene, polyhexafluoropropene, tetrafluoroethylene hexafluoropropene copolymer, alkoxy fluoroethylene copolymer, ethylene-tetra fluoroethylene copolymer, or a combination thereof.
20 . The coating composition of claim 18 , further comprising a cross-linker for crosslinking the film-forming binder.
21 . (canceled)
22 . The coating composition of claim 18 , wherein the film-forming binder further comprises a gelation agent.
23 . The coating composition of claim 1 , wherein the film-forming binder comprises an aqueous wax emulsion or an aqueous emulsion of a hydrophobic polymer and the solvent comprises water.
24 . The coating composition of claim 23 , wherein the coating composition is prepared by dispersing the hydrophobized silica particles in water in a presence of a surfactant to form a suspension of the hydrophobized silica particles, and then mixing the wax emulsion or the emulsion of the hydrophobic polymer with the suspension of the hydrophobized silica particles.
25 . The coating composition of claim 1 , wherein the film-forming binder is present in an amount of about 1% to about 30% by weight of the coating composition.
26 . The coating composition of claim 1 , wherein the coating composition is in a form of aerosol further comprising at least one propellant.
27 . A hydrophobic film formed from the coating composition of claim 1 , wherein the hydrophobic film exhibits a static contact angle for deionized water at room temperature equal to or greater than about 140° and a rolling rating of at least 1 in a scale of 0-3.
28 . The hydrophobic film of claim 27 , wherein the hydrophobic film is produced by a method selected from the group consisting of spin coating, dip coating, spray coating, roller coating, drawdown, brush coating, and a mixture thereof.
29 . An article, comprising at least one difficult-to-wet surface which is composed essentially of a coating composition, the coating composition comprising:
hydrophobized silica particles;
a film-forming binder; and
a solvent,
wherein the hydrophobized silica particles comprise porous silica particles having a pore diameter of about 80 Å or more which have been treated to form a hydrophobic coating on a surface of the porous silica particles.
30 . The article of claim 29 , wherein the difficult-to-wet surface exhibits a static contact angle for deionized water at room temperature equal to or greater than about 140° and a rolling rating of at least 1 in a scale of 0-3.
31 . The article of claim 30 , wherein the article preferably comprises a material selected from the group consisting of glass, metal, plastics, wood, concrete, fabrics, cellulosic materials, and paper.