Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-12-01
2003-01-28
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S429000, C427S164000, C427S165000, C427S387000, C106S287160, C528S010000, C528S020000, C528S042000
Reexamination Certificate
active
06511753
ABSTRACT:
This application claims the benefit of PCT Application Serial No. PCT/JP99/02985 filed Jun. 3, 1999, which is now abandoned, the teachings of which are incorporated herein by reference.
TECHNICAL FIELD
The present invention relates to a water repellent product comprising a water repellent film formed on a surface of a base substrate such as glass, ceramic, plastic, metal or the like.
BACKGROUND ART
Technologies have been known in which an undercoat layer such as silica or the like is formed between a base substrate and a water repellent layer for the purpose of improving the bonding strength between the base substrate and the water repellent film, when the water repellent film is formed on a surface of the base substrate such as a glass plate or other base substrates, and for preventing the diffusion of an alkaline component from base substrate to a product coated with a water repellent film and increasing the durability of the water repellent film, when the base substrate contains an alkaline component.
As methods for forming the undercoat layer and the water repellent film, there have been known a method in which a two-layer film structure is produced by forming a water repellent film after forming an undercoat film such as silica or the like on a base substrate, and a method in which a mixed solution composed of an undercoat component and a water repellent component is formed to be film on a base substrate to produce a single layer film acting as the undercoat layer and the water repellent layer. The latter method is superior in productivity because of fewer film making steps, and includes those disclosed in Japanese Patent Publication No. 24554 of 1988, Japanese Laid-open Patent Publication No. 215235 of 1986, 68477 of 1989, 338137 and 359086 of 1992 and 239653 of 1996.
The Japanese Patent Publication No. 24554 of 1988 discloses a water repellent surface treatment agent formed by modifying a silanol oligomer (20- to 40-mer) with a fluoroalkylsilane.
The Japanese Laid-open Patent Publication No. 215235 of 1986 discloses a low-reflection rate glass having water repellent properties and soil-resistant properties produced by applying on a surface of a base substrate a solution in which a fluoroalkyl group-containing silane compound and a silane coupling agent are hydrolytically reacted using acetic acid and a catalyst composed of an organic tin compound in an alcoholic solvent to form a copolycondensate, and then heat-curing.
The Japanese Laid-open Patent Publication No. 68477 of 1989 discloses a process for producing a water repellent steel sheet which comprises applying an alcoholic solution containing an alkoxide of silicon and a fluoroalkylsilane on a surface of the steel sheet and then heating.
The Japanese Laid-open Patent Publication No. 338137 of 1992 discloses a water repellent glass which comprises applying a solution formed by mixing a silicon alkoxide, a substituted silicon alkoxide in which a part of the alkoxyl group is replaced by a fluoroalkyl group, alcohol, water and an acid (or a base) on a surface of a glass substrate and then calcining.
The Japanese Laid-open Patent Publication No. 359086 of 1992 discloses a process for producing a water repellent glass which is calcinated after a coating solution formed by mixing a fluoroalkylsilane or alkylsilane into vehicle which is obtained by being hydrolytically reacted polycondensated under coexisting with water, alcohol and catalyst is applied on a surface of a glass.
The Japanese Laid-open Patent Publication No. 239653 of 1996 discloses a water repellent product produced by treating with a composition in which a mixture of a perfluoroalkylalkylsilane and a completely hydrolyzable silane (for example, tetrachlorosilane) is dissolved in a solvent, preferably a non-aqueous solvent.
Since, in the methods disclosed in the Japanese Patent Publication No. 24554 of 1988, Japanese Laid-open Patent Publication Nos. 215235 of 1986 and 338137 and 359086 of 1992, a polycondensate and a copolycondensate are formed in a solution for coating before applying by hydrolyzing a fluoroalkyl group-containing silane and a silicon alkoxide utilizing a catalytic reaction in an alcoholic solution, where the compactness of the water repellent film is low. Therefore, in order to improve the compactness, a calcination step is required which is a factor in increasing costs.
In the method disclosed in the Japanese Laid-open Patent Publication No. 68477 of 1989, since reactivity is inferior due to the absence of a catalyst, the compactness of the water repellent film is low. Therefore, in order to improve the compactness, a calcination step is required which is a factor in increasing costs.
In the method disclosed in the Japanese Laid-open Patent Publication No.239653 of 1996, blending and storage of a coating liquid should be carried out in a water-free environment because of extremely high reactivity of a chlorosilyl group in chlorosilane used in the composition for coating and this is a factor in increasing costs. In addition, the surface of the water repellent film formed by this method is inferior in scratching resistance. Furthermore, in all the water repellent products produced by the prior art methods described above, the rolling property of water drops representing the dynamic water-repellent performance can not be said satisfactory.
The purpose of the present invention is to produce a water repellent product having a good rolling property of water drops, a high scratching resistance(abrasion resistance) and a high weatherability with an excellent productivity and without requiring a calcination step at high temperatures.
DISCLOSURE OF THE INVENTION
Accordingly, the present invention is a process for producing a product coated with a water repellent film which comprises applying on a base substrate a coating liquid containing a silicon alkoxide (A), a fluoroalkyl group-containing silane compound (B) and an acid (C) dissolved in a solvent and drying; said process for producing a product coated with a water repellent film being characterized in that said coating liquid contains:
(A) 0.01-2% by weight (based on SiO
2
equivalent: MW=60) of a said silicon alkoxide or a hydrolysate thereof
(B) 0.00001-0.15% by weight (based on SiO
2
equivalent: MW=60) of a said fluoroalkyl group-containing silane compound
(C) 0.003-3 normality of said acid, and
(D) 0-20% by weight of water
Furthermore, the present invention is a process for producing a product coated with a water repellent film which comprises applying on a base substrate a coating liquid containing a silicon alkoxide, a fluoroalkyl group-containing silane compound and an acid dissolved in a solvent and drying; said process for producing a product coated with a water repellent film being characterized in that said coating liquid contains the silicon alkoxide existing in the form of a monomer (including hydrolysate) or a polymer that is less 20-mer.
The language “% by weight (converted to silica)” used throughout the specification is intended to mean that the component of the coating liquid is present at a % by weight based on a SiO
2
equivalent: MW=60.
In the present invention, the silicon alkoxide (component A) used in the coating liquid described above may include tetramethoxysilane, tetramethoxysilane, tetrapropoxysilane, tetrabutoxysilane and the like. Among them, those having relatively small molecular weight, for example, tetraalkoxysilane composed of alkoxyl groups having 3 or less carbon atoms are apt to form a compact film and therefore are preferably used. In addition, polymers of these tetraalkoxysilane having an average degree of polymerization of 5 or less may also be used.
As the fluoroalkyl group-containing silane compound used in the present invention, silane compounds containing a fluoroalkyl group and having an alkoxyl group, an acyloxy group or silane compound containing hydrolysate group such as a chlorine group can be preferably used. Examples include compounds represented by the following chemical formulas (1). Single substance or a combination
Kamitani Kazutaka
Sunada Takashi
Teranishi Toyoyuki
Alexander John B.
Conlin David G.
Dawson Robert
Edwards & Angell LLP
Feely Michael J
LandOfFree
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