Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
1999-01-11
2001-04-24
Nakarani, D. S. (Department: 1773)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S450000, C428S451000, C524S413000, C524S497000, C524S588000, C524S837000, C524S839000, C525S902000, C106S287120
Reexamination Certificate
active
06221498
ABSTRACT:
This application claims the benefit under 35 U.S.C. §371 of prior PCT International Application No. PCT/JP98/01071 which has an International filing date of Mar. 13, 1998 which designated the United States of America, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an antifouling silicone emulsion coating-composition which can form a coat excellent in antifouling properties, antifogging properties, transparency, weather resistance, durability etc., a process for the producing the same, and an article applied with said composition.
2. Background of the Invention
It is known that upon exposure of a photo-semiconductor to: UV rays, active oxygen is generated (photo-catalysis). Because active oxygen can oxidize and decompose organic materials, an article having a photo-semiconductor layer or a photo-semiconductor-containing coat formed on the surface of a substrate is expected to have the self-washing effect of decomposing carbon-type dirt components (e.g. carbon fractions contained in an exhaust gas from automobiles or nicotine in tobacco, etc.) adhered to its surface; the deodorizing effect of decomposing foul-odor components represented by amine compounds and aldehyde compounds; and the anti-microbial effect of preventing generation of microbial components represented by
E. coli
and yellow staphylococci. Upon exposure of a photo-semiconductor-containing coat to UV rays, dirt such as water-repellant organic materials etc. adhering to the surface of the coat is decomposed and removers by the photo-semiconductor, so that there is the effect that the contact angle of water to the surface of the coat is lowered and the surface of the coat is readily wetted with water (see e.g. Japanese Patent Publication Laid-Open No. 83,106/1986, WO 96/29375 etc.). From this effect, the antifogging effect by which glass and mirrors in indoor members are hardly fogged with water drops while dirt adhered to outdoor members is washed away with rain water is expected.
Fine particles of titanium oxide made anatase crystals by thermal treatment at the producing time, or a water dispersion thereof, are or is commercially available. Thermal treatment at 300° C. or more is, however, required to form a titanium oxide layer having sufficient strength on the surface of a substrate by sintering such fine particles at particle interface. The substrate is limited to the one having thermal resistance.
The method of fixing photo-catalytic titanium oxide on the surface of a substrate whose thermal resistance is less than 300° C. is known as, for example, a method of fixing fine particles of titanium oxide in the form of said anatase crystals by use of a low-temperature setting binder. However, if titanium oxide is fixed in an organic type binder, active oxygen will also decompose the organic binder. Durability cannot be expected with respect to the organic binder composite.
On the other hand, an inorganic binder is hardly decomposed with active oxygen. The inorganic low-temperature setting binder includes, for example, a silicone coating material.
SUMMARY OF THE INVENTION
However, as the photo-semiconductor is generally a metallic oxide, dispersion medium-therefor is required to be water to readily disperse the photo-semiconductor. If transparency is required for a desired coat, the particle size of the photo-semiconductor should also be ultrafine particles of 0.1 &mgr;m or less in average diameter. However, because the conventional silicone coating material is an organic solvent type, it is difficult to disperse the photo-semiconductor uniformly in the silicone coating material. The photo-semiconductor is readily aggregated and precipitated so that it is hard for the resulting coat to sufficiently achieve the desired photo-catalytic performance. In addition, said coat has low transparency and readily turns opaque. Its utilities are limited.
Accordingly, an object of the present invention is to provides an antifouling silicone emulsion coating-composition which can be cured at lower temperatures than 300° C., has a photo-semiconductor uniformly dispersed therein, and can form a coat excellent in transparency, weather resistance, durability etc. in addition to various characteristics derived from the photo-catalysis of a photo-semiconductor, such as antifouling properties, antifogging properties etc.
Another object of the present invention is to provide a process for producing the composition, and an antifouling article applied with the said composition.
MEANS TO SOLVE THE PROBLEMS
The antifouling silicone emulsion coating-composition of the present invention comprises the following components (A), (B), (C) and (D), wherein an amount of the component (C) incorporated is in the range of 5 to 80% by weight relative to the total solid contents in the composition;
(A) Partially hydrolyzed organosiloxane with a weight-average molecular weight of 600 to 5000 (determined using a polystyrene calibration curve), represented by the average formula (I): R
2
aSiOb(OR
1
)c(OH)d wherein R
1
and R
2
represent a monovalent hydrocarbon group; a, b, c and d are numerals satisfying the following relationships: a+2b+c+d=4, 0a≦3, 0<b<2, 0<c<4, and 0<d<4;
(B) Nonionic surface active agent or anionic surface active agent;
(C) Photo-semiconductor.
(D) Water.
The above component (D) is preferably titanium oxide.
The above component (C) is preferably fine particles with an average primary particle diameter of 0.001 to 0.03 &mgr;m.
The antifouling silicone emulsion coating-composition of the present invention can also contain colloidal silica.
The antifouling silicone emulsion coating-composition of the present invention can also contain the following component (E). (E) Straight-chain polysiloxane diol containing hydroxyl groups at both terminals, represented by the average formula (II): HO(R
3
2
SiO)nH wherein R
3
represents a monovalent hydrocarbon group, and n is a numeral of 3≦n≦50.
The antifouling silicone emulsion coating-composition of the present invention can also contain at least one organic resin selected from the group consisting of alkyd resin, epoxy resin, acrylic resin, acrylic silicone resin, phenol resin, fluorine resin, polyester resin, chlorinated rubber resin, urethane resin and melamine resin.
The above organic resin is preferably the following component (F). (F) Acrylic resin which is a copolymer of monomers represented by the general formula (III): CH
2
═CR
4
(COOR
5
) wherein R
4
represents a hydrogen atom and/or a methyl group, said monomers comprising a first (meth) acrylate wherein R
5
is a substituted or unsubstituted C1 to C9 monovalent hydrocarbon group, a second (meth)acrylate wherein R
5
is at least one group selected from the group consisting of an epoxy group, a glycidyl group and a hydrocarbon group containing an epoxy group and/or a glycidyl group, and a third (meth)acrylate wherein R
5
is a hydrocarbon group containing an alkoxysilyl group and/or a halogenated silyl group.
In the present specification, the (meth)acrylate means to acrylate and/or methacrylate.
The antifouling silicone emulsion coating-composition of the present invention may also contain a pigment.
The first process for producing an antifouling silicone emulsion coating-composition according to the present invention comprises the step of mixing an emulsion containing the above components (A), (B) and (D) with a powder of the above component (C) and/or a dispersion having said powder dispersed in the above component (D).
The second process for producing an antifouling silicone emulsion coating-composition according to the present invention comprises the step of removing an organic solvent from a mixture of the above components (A) and (C) and the organic solvent to obtain a desolvated material and the step of mixing said desolvated material with the above components (B) and (D).
The third process for producing an antifouling silicone emulsion coating-composition according to the present invention compri
Goto Akiharu
Ikenaga Junko
Inoue Minoru
Kishimoto Hirotsugu
Takahama Koichi
Birch & Stewart Kolasch & Birch, LLP
Matsushita Electric & Works Ltd.
Nakarani D. S.
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