Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2001-12-17
2003-10-21
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S012000, C528S026000, C528S016000, C528S043000, C528S032000, C524S588000, C524S858000, C524S863000, C502S171000
Reexamination Certificate
active
06635735
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a coating composition and, more particularly, to a coating composition which can be prepared in accordance with the sol-gel process and provides a coating film having excellent physical properties when the coating composition is applied to the surface of metal, wood, paper, cloth, glass, ceramics, concrete or a synthetic resin by spray coating and cured at a low temperature in the range of the room temperature to about 200° C.
BACKGROUND ART
Heretofore, a coating material forming a coating layer having a high hardness and exhibiting excellent weatherability, water resistance, chemical resistance and adhesion at a low cost has been desired and many proposals have been made. As an inorganic coating material, complexes composed of sols of oxides and organosilanes which provide organo-polysiloxanes by hydrolysis and polycondensation have mainly been examined.
For example, in Japanese Patent Application Laid-Open No. Showa 57(1982)-165429, a coating process using an aqueous composition which contains a dispersion containing colloidal silica in a solution prepared by dissolving a partial condensate of a silanol into a mixture of an aliphatic alcohol and water, a buffered latent catalyst for silanol condensation and a &bgr;-hydroxyketone compound is proposed as a process for forming a coating layer which is cured in a short time and provides fastness and scratch resistance to the surface of plastic base materials. In Japanese Patent Application Laid-Open No. Showa 62(1987)-32157, a coating composition prepared by mixing an organoalkoxysilane, an alcohol or a glycol, colloidal alumina, an acid and a filler insoluble in water is proposed as a coating composition for forming a coating layer exhibiting excellent heat resistance on the surface of metal, cement and glass. In these coating compositions, alcohols are added in a great amount as hydrophilic organic solvents and water is contained in a great amount as the dispersion medium of the sol. Therefore, these coating compositions have a drawback in that the concentrations of solid substances is small and, moreover, the rates of hydrolysis and polycondensation are very great and stability in storage is poor.
In Japanese Patent Application Laid-Open No. Showa 63(1988)-117074, a coating composition containing a condensate of an organoalkoxysilane, colloidal silica, water and a hydrophilic organic solvent is proposed as a coating composition which exhibits excellent storage stability and forms a coating layer having a high hardness and exhibiting excellent physical properties on the surface of metal, ceramics and glass. This coating composition has a drawback in that the composition tends to cause condensation of water on the surface due to a decrease in the temperature by vaporization of the hydrophilic organic solvent during spray coating. Aggregation of fine silica particles takes place due to the condensation of water and it is difficult that a uniform coating layer is obtained. In Japanese Patent Application Laid-Open No. Heisei 4 (1992)-175388, a coating composition containing, as the essential components, a solution of an oligomer of an organosilane in which silica is dispersed, a polyorganosiloxane having silanol group in the molecule and a catalyst is proposed as a coating composition which is applied to the surface of metal, concrete and plastic base materials, can be cured at a low temperature and can form a coating layer having a high hardness and exhibiting excellent heat resistance and weatherability. This coating composition has a drawback in that the pot life is short after a curing catalyst is added.
In Japanese Patent Application Laid-Open No. Heisei 3 (1991)-31380, a coating composition containing 30 to 90% by weight of a colloidal silica which has the surface modified with an alkoxysilane compound having 2 or more alkoxyl groups and 70 to 10% by weight of a condensate of an organotrialkoxysilane is proposed as a silicone coating composition which forms a thick coating layer having a high hardness and exhibiting excellent heat resistance, wear resistance, chemical resistance, weatherability and gloss on the surface of metal, ceramics, glass and cement and can be stored for a long time. This coating composition has a drawback in that, since water is added in combination with the alkoxysilane and/or condensates having low molecular weights thereof when the surface of the colloidal silica in this coating composition is modified, hydrolysis and polycondensation of the alkoxysilane and/or the condensates having low molecular weights thereof are promoted in the solution and the efficiency of modification of the surface of the colloidal silica decreases. Moreover, since this coating composition does not contain curing catalysts, it takes a long time before the formed coating film is dried sufficiently so that the coating layer can be touched by hands and, therefore, handling of the coated article is difficult.
The present invention has an object of providing a coating composition which exhibits excellent storage stability after addition of a curing agent, suppresses aggregation of fine silica particles during spray coating and forms a coating layer having a high hardness and exhibiting excellent weatherability, water resistance, chemical resistance and adhesion.
DISCLOSURE OF THE INVENTION
As the result of intensive studies by the present inventors to overcome the above drawbacks, it was found that a coating composition comprising a dispersion in an alcohol of fine silica particles which had the hydrophobic surface modified with a hydrocarbon group, a solution comprising a silicone oligomer which was obtained by the reaction of an alkoxysilane with water and a curing agent had a long pot life after addition of the curing agent, suppressed aggregation of fine silica particles during spray coating and formed a coating layer exhibiting excellent physical properties. The present invention has been completed base on this knowledge.
The present invention provides:
(1) A coating composition which comprises:
(A) an alcohol dispersion which comprises silica having a hydrophobic surface and dispersed in an alcohol dispersion medium and has a content of silica in a solid substance of 80% by weight or more;
(B) a solution comprising a silicone oligomer which is obtained by a reaction of an alkoxysilane with water and has an average structural unit represented by:
R
1
n
SiO
x/2
(OH)
y
(OR
2
)z
wherein R
1
represents an alkyl group having 1 to 3 carbon atoms, phenyl group or vinyl group, a plurality of R
1
may represent a same group or different groups when the plurality of R
1
are present, R
2
represents an alkyl group having 1 to 3 carbon atoms, a plurality of R
2
may represent a same group or different groups when the plurality of R
2
are present and n, x, y and z represent numbers satisfying relations of: 0.8≦n≦1.7, 2<x<3.2, y>0, z>0 and y+z=4−n−x; and
(C) a curing agent;
(2) A coating composition described in (1), wherein a content of component (A) is 10 to 70% by weight as a solid substance and a content of component (B) is 90 to 30% by weight as a solid substance each based on a total amount of component (A) and component (B) as solid substances and a content of component (C) is 1 to 40 parts by weight per 100 parts by weight of a total amount of component (A) and component (B) as solid substances;
(3) A coating composition described in (1), wherein the silica having a hydrophobic surface in component (A) is obtained by a reaction of fine silica particles with an organoalkoxysilane or an organohalosilane each having a structure represented by:
R
3
m
SiX
4−m
wherein R
3
represents an alkyl group having 1 to 3 carbon atoms, phenyl group or vinyl group, m represents 1, 2 or 3, a plurality of R
3
may represent a same group or different groups when m represents 2 or 3 and X represents Cl, OCH
3
or OC
2
H
5
;
(4) A coating composition described in (1), wherein the silica having a hydrophobic surface in component (A) is obtained by a re
Wakabayashi Hajimu
Zhang Zuyi
Dawson Robert
Nihon Yamamura Glass Co., Ltd.
Peng Kuo-Liang
Young & Thompson
LandOfFree
Coating composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coating composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coating composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3116102