Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-07-11
1999-10-19
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525190, 524407, 524418, 524430, 524435, 524495, C08L 7102
Patent
active
059690488
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a colored coating composition which is suitable for an automotive top coating composition and a coil coating composition.
BACKGROUND OF THE INVENTION
A solid color coating composition containing an aminoplast as a curing agent has been conventionally widely known. However, in the case of a coating composition containing as a curing agent only an aminoplast, a crosslinked portion of a coated film has poor acid resistance, and the coated film is damaged by acid rain which has recently become a serious problem.
The present inventors have already suggested a curable resin composition comprising a polymer having a specific halfester group and a polymer having a hydroxyl group and an epoxy group, in Japanese Patent Laid-Open Publication No. Hei 3-287650. This composition is excellent in acid resistance and is not damaged by acid rain, since it uses an acid anhydride curing system. However, the coating system suggested by these inventors is basically designed to obtain a clear coating. Therefore, a solid color coating composition containing a pigment has not been investigated.
In the case of solid color, excellent appearance, high mar resistance and the like are required as well as the above-described acid resistance. Further, it is important that the coating composition is high solid. On the other hand, to obtain high mar resistance together with the acid resistance, it is indispensable to make a crosslinked coated film having high density. As a result, a problem occurs that stress strain is concentrated in the interface of a coated film in curing with thermosetting, and consequently adhesion to an undercoat becomes poor.
The present invention has been made to solve the above-described conventional problems, and the object thereof is to provide a solid color coating composition which suffices scratch resistance, acid resistance, storage stability and excellent appearance.
SUMMARY OF THE INVENTION
The present invention provides a colored coating composition comprising carboxylate group, which is obtained by reacting: unsaturated monomer, with unsaturated monomer; with an amount so that a molar ratio of the acid anhydride group to the hydroxyl group becomes 1/10 to 1/1; group, which is obtained by copolymerizing: unsaturated monomer represented by the formula: ##STR1## [wherein R is a hydrogen atom or a methyl group, and X is an organic chain represented by the formula: ##STR2## (wherein Y is a linear or branched alkylene group having 2 to 8 carbon atoms, m is an integer of 3 to 7 and q is an integer of 0 to 4) or an organic chain represented by the formula: ##STR3## (wherein R is an hydrogen atom or a methyl group and n is an integer of 2 to 50)] and unsaturated monomer, and optionally unsaturated monomer; the components (a) to (d) is based on the weight of total solid in the colored coating composition), derived from said pigment-dispersing agent and an acid total amount AP and a base total amount BP which are derived from said pigment suffice, the following relations:
DETAILED DESCRIPTION OF THE INVENTION
Dispersion stabilization of a pigment is an important subject in the art of coating production. It can be said that good pigment dispersing can be achieved by preventing re-flocculation after dispersing and by stabilizing the dispersion. In a conventional polyester/melamine-based coating composition or acryl/melamine-based coating composition for automobiles, dispersion stabilization of a pigment has been attained by adsorption of a resin utilized for dispersion to the pigment. When attention is paid to an acid/epoxy curing system such as for example the art of the instant application, however, a resin having an acid group carries too much absorbable functional groups, and causes bridging flocculation between the pigments. On the other hand, in a resin containing an epoxy group, functional groups which can be introduced are restricted, therefore, the number of functional groups which can generally achieve dispersion stability by adsorbing a pigm
REFERENCES:
patent: 5270392 (1993-12-01), Okude et al.
patent: 5378275 (1995-01-01), Shiraga et al.
Fujita Takayuki
Ito Etsuyuki
Terada Tsuyoshi
Tsujioka Hideaki
Cain Edward J.
Nippon Paint Co. Ltd.
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