Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-11-14
2003-12-09
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C525S100000, C525S474000, C525S476000, C525S478000, C528S014000, C528S028000, C528S041000
Reexamination Certificate
active
06660394
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a coating composition and a hardened film obtained therefrom, and more particularly to a coating composition excellent in weather resistance and stain resistance, and further excellent in long-term durable adhesion, and a hardened film obtained therefrom.
BACKGROUND OF THE INVENTION
There have been recent demands for coating compositions which are excellent in heat resistance, water resistance, stain resistance, organic chemical resistance, acid resistance, alkali resistance, corrosion resistance, wear resistance, weather resistance, moisture resistance and adhesion, and which are capable of forming coating films high in hardness.
As coating compositions partially satisfying such demands, there are proposed a composition comprising a partial condensation product of an organosilane, a dispersion of colloidal silica and a silicon-modified acrylic resin (see Japanese Patent Application Laid-Open No. 135465/1985), a composition comprising a condensation product of an organosilane, a chelate compound of a zirconium alkoxide and a hydrolytic silyl group-containing vinyl resin (see Japanese Patent Application Laid-Open No. 1769/1989), a composition comprising a condensation product of an organosilane, colloidal alumina and a hydrolytic silyl group-containing vinyl resin (see U.S. Pat. No. 4,904,721), and a composition comprising a hydrolysate of an organosilane, a metal chelate compound and a hydrolytic or partially condensable silyl group-containing vinyl resin.
However, when coating films are formed by use of the coating compositions described in Japanese Patent Application Laid-Open No. 135465/1985 and U.S. Pat. No. 4,904,721, the luster of the coating films is lowered by irradiation of ultraviolet rays for a long period of time.
The composition described in Japanese Patent Application Laid-Open No. 1769/1989, which contains the condensation product of the organosilane, the chelate compound of the zirconium alkoxide and the hydrolytic silyl group-containing vinyl resin in a hydrophilic organic solvent, is insufficient in storage stability, so that an increase in solid content is liable to cause gelation for a short period time.
Further, these compositions are accompanied by hardening reaction in the course of coating film formation. Accordingly, heat treatment at high temperature or for a long period of time is required, which raises problems with regard to practicability. When this heat treatment is conducted under conditions of high temperature and a short time, the resulting coating films are generally liable to become poor in adhesion to substrates or undercoat layers, or insufficient in hardness. In particular, adhesion of foreign matter such as water onto the coating films immediately after formation of the coating films presents the problem of significantly impairing the adhesion of the coating films.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned problems in the prior art, and an object of the invention is to provide a coating composition completing the hardening reaction of a coating film at low temperature for a short period of time, high in hardness immediately after hardening, and having water resistance, weather resistance, organic chemical resistance, acid resistance, alkali resistance, wear resistance and durable adhesion.
Another object of the invention is to provide a hardened film obtained therefrom.
The present invention provides a coating composition which is an aqueous dispersion comprising a polymer (hereinafter also referred to as a “specific polymer”) containing (a) a hydrolysate of an organosilane represented by the following general formula and/or a condensation product thereof (hereinafter also referred to as “component (a)”) and (b) a vinyl polymer (hereinafter also referred to as “component (b)”) containing a silyl group having a silicon atom bound to a hydrolytic group and/or a hydroxyl group, and further comprising (c) an oxazoline derivative (hereinafter also referred to as “component (c)”) as a crosslinking agent:
R
1
n
Si(OR
2
)
4−n
(1)
wherein R
1
represents an organic group having 1 to 8 carbon atoms, R
2
represents an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 6 carbon atoms, and n is an integer of from 0 to 2.
It is preferred that the above-mentioned coating composition comprises a specific polymer dispersed in an aqueous medium, which polymer contains component (a) and component (b), and further comprises component (c) as a crosslinking agent.
It is preferred that the above-mentioned component (a) is a mixture of a compound represented by general formula CH
3
Si(OR
2
)
3
(wherein R
2
has the same meaning as defined above) and a compound represented by general formula R
1
Si(OR
2
)
3
(wherein R
1
represents an organic group having 2 to 8 carbon atoms, and R
2
has the same meaning as defined above), and the content of the compound represented by CH
3
Si(OR
2
)
3
in the mixture is preferably from 40% to 100% by weight.
It is more preferred that the mixture contains the compound represented by CH
3
Si(OR
2
)
3
in an amount of 50% to 100% by weight.
The above-mentioned component (b) preferably has at least two or more silyl groups at terminals or on side chains of a molecular chain of the vinyl polymer, the silyl groups each having a silicon atom bound to a hydrolytic group and/or a hydroxyl group.
It is preferred that the vinyl polymer containing the Silyl group having a silicon atom bound to a hydrolytic group and/or a hydroxyl group, the above-mentioned component (b), has a functional group that can be chemically bound to a hydrophilic functional group and/or an oxazoline group.
Further, component (c) is preferably a copolymer obtained by emulsion polymerization or suspension polymerization of a copolymerizable oxazoline monomer and another copolymerizable monomer.
The average particle size of the above-mentioned component (c) is preferably from 0.01 &mgr;m to 0.5 &mgr;m.
Further, the hardened film of the invention is obtained by coating a substrate with the coating composition of the invention and hardening the coating composition.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be explained in detail.
Coating Composition
Component (a)
Component (a) is a hydrolysate of an organosilane represented by the above-mentioned general formula (1) (hereinafter also referred to as “organosilane (1)”) and/or a condensation product thereof.
In the above-mentioned general formula (1), the organic group of 1 to 8 carbon atoms represented by R
1
includes, for example, an alkyl group such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl or n-octyl; an acyl group such as acetyl, propionyl or butyryl; a &ggr;-chloropropyl group, a &ggr;-bromopropyl group, a 3,3,3-trifluoropropyl group, a &ggr;-glycidoxypropyl group, a &ggr;-(meth)acryloxypropyl group, a &ggr;-mercaptopropyl group, a &ggr;-aminopropyl group, a &ggr;-dimethylaminopropyl group, a 2-(3,4-epoxycyclohexyl)ethyl group, a vinyl group or a phenyl group.
The alkyl group of 1 to 5 carbon atoms represented by R
2
includes, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group or an n-pentyl group.
Specific examples of such organosilanes (1) include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, methyl silicate, ethyl silicate, methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, &ggr;-chloropropyltrimethoxysilane, &ggr;-chloropropyltriethoxysilane, 3,3,3-trifluoropropylmethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, &ggr;-glycidoxypropyltrimethoxysilane, &ggr;-glycidoxypropyltriethoxysilane; &ggr;-methacryloxypropyltrimethoxysilane, &ggr;-methacryloxypropyltriethoxysilane, &ggr;-mercaptopropyltrimethoxysilane, &ggr;-mercaptopropyltriethoxysilane, 3,4-epoxycyclohexyl
Ando Michiaki
Ishizuki Kenji
Shiho Hiroshi
Shimada Mibuko
Shimizu Tatsuya
Dawson Robert
JSR Corporation
Keehan Christopher M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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