Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
2001-10-03
2003-12-09
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C428S418000, C525S423000, C525S438000, C528S111000, C528S114000, C528S121000, C205S316000
Reexamination Certificate
active
06660385
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a cationic paint composition and more specifically relates to a cationic electrodeposition paint composition capable of forming a cured coating film excellent in performances such as throwing power, rust preventive steel plate aptitude etc.
Cationic electrodeposition paint composition has been used mainly for undercoating of a car body as an electrodeposition paint and other wide range of applications and products having various properties have been developed up to now. For example, there has been proposed a cationic electrodeposition paint composition which contains a base resin containing an epoxy resin, which contains amino group and/or quaternary ammonium group as water-solubilizing group and is internally plasticized with a plasticizer such as polyamide, polyester, polyether etc., and is excellent in corrosion resistance and good in rust preventive steel plate aptitude and adhesion. In such a cationic electrodeposition paint composition there are compounded lead compounds or chromium compounds, for example, lead chromate, basic lead silicate, strontium chromate etc. as anticorrosive pigment. Recently, however, the use of such harmful compounds as lead compounds or chromium compounds is restricted in terms of pollution problems and the development of a cationic paint composition, excellent in corrosion resistance without compounding lead compounds or chromium compounds, has been strongly desired.
As an epoxy resin which is internally plasticized with a plasticizer tends to deteriorate the corrosion resistance of the coating film, it may be considered to improve the corrosion resistance by using as base resin an epoxy resin without containing a plasticizing modifier. There is, however, a problem that a paint composition using a non-plasticized epoxy resin has a lower rust preventive steel plate aptitude.
Moreover, it has been proposed to compound to an epoxy resin a plasticizer which does not deteriorate the corrosion resistance of the coating film, for example, polyol resin such as polyester polyol, polyether polyol, polyurethane polyol, acrylpolyol etc.; polyolefin such as polybutadiene, polyethylene etc. There are problems, however, that these materials are not compatible enough with epoxy resin and are not only poorly effective to improve the rust preventive steel plate aptitude but also deteriorate the corrosion resistance of the coating film if compounded much.
On the other hand, a throwing power is required to a cationic electrodeposition paint composition as a rust preventive countermeasure for baggy parts of a car body (locker, side-sill, pillar) etc. Particularly recently a higher throwing power is required to a cationic electrodeposition paint composition because of more complicated body structure, such as putting reinforcement to the locker part and in the side-sill from levelling up of car safety level. Therefore it has been desired to develop a cationic electrodeposition paint composition having a high throwing power, excellent in corrosion resistance and rust preventive steel plate aptitude.
The present inventors repeated intensive research works to respond to the above-mentioned requirements. As a result, this time, they have found out that a cationic electrodeposition paint composition having not only a high throwing power but also excellent in rust preventive steel plate aptitude and corrosion resistance by compounding a certain specific kind of a polyol-modified amino group-containing epoxy resin in a cationic electrodeposition paint.
Thus, according to the present invention there is provided a cationic paint composition containing as resin component a polyol-modified amino group-containing epoxy resin obtained by reacting
(a) an epoxy resin with an epoxy equivalent of 180-2,500 with
(b) an acid compound selected from the group consisting of the phenols of the following formula (1) and the carboxylic acids of the following formula (2),
wherein,
X represents a hydrogen atom or a hydrocarbon group with a carbon atom number 1-15 which may have optionally substituents selected from the group consisting of —OH, —OR, —SH and —SR,
Y represents a hydrocarbon group with a carbon atom number 1-15 which may have optionally substituents selected from the group consisting of —OH, —OR, —SH and —SR,
wherein R represents an alkyl group.
(c) a polyol compound obtained from a compound (c
1
) containing a plurality of active hydrogen groups by adding a caprolactone (c
2
) and
(d) an amino group-containing compound.
Then, the cationic paint composition provided by the present invention will be described in more detail.
(a) Epoxy resin:
As an epoxy resin (a) to be the main skeleton of the polyol-modified amino group-containing epoxy resin according to the present invention it is suitable to have an epoxy equivalent in the range of 180-2,500, preferably 200-2,000 and more preferably 400-1,500 and a number-average molecular weight of generally at least 200, preferably in the range of 400-4,000 and more preferably 800-2,500. If the epoxy equivalent of the epoxy resin is less than 180, the corrosion resistance and throwing power of the formed cationic paint composition is poor. If, on the other hand, it is more than 2,500, the rust preventive steel plate (zinc-plated steel plate) aptitude is remarkably deteriorated,
As such an epoxy resin (a), a product obtained by reacting a polyphenol compound with an epihalohydrin, for example, epichlorohydrin, is preferable from a viewpoint of corrosion resistance etc. of the coating film.
As a polyphenol compound usable for the formation of said polyepoxide compound there can be mentioned, for example, bis(4-hydroxyphenyl)-2,2-propane (bisphenol A), 4,4-dihydroxybenzophenone, bis(4-hydroxyphenyl)methane (bisphenol F), bis(4-hydroxy-phenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-tert-butyl-phenyl)-2,2-propane, bis(2-hydroxynaphthyl)-methane, tetra(4-hydroxyphenyl)-1,1,2,2-ethane, 4,4-dihydroxy-diphenylsulfone, phenol novolac, cresol novolac etc.
As an epoxy resin obtained by the reaction of polyphenol compound and epichlorohydrin, above all, a product derived from bisphenol A and illustrated by the following formula
wherein n=1-3 is preferable.
As such an epoxy resin available on the market, there can be mentioned, for example, products sold by Japan Epoxy Resin Co., Ltd. under the trade name of Epicote 828EL, 1002, 1004 and 1007.
(b) Acid compound:
Acid compound to be reacted with the above-mentioned epoxy resin (a) according to the present invention is at least one kind of compound selected from the group consisting of the phenols illustrated by the following formula (1)
wherein
X represents a hydrogen atom or a hydrocarbon group with a carbon atom number 1-15 which may have optionally substituents selected from the group consisting of —OH, —OR, —SH and —SR, wherein R represents an alkyl group, and
the carboxylic acids illustrated by the following formula (2)
wherein
Y represents a hydrocarbon group with a carbon atom number 1-15 which may have optionally substituents selected from the group consisting of —OH, —OR, —SH and —SR, wherein R represents an alkyl group.
In the above-mentioned formula (1) the hydrocarbon group with a carbon atom number 1-15 represented by X can be straight chain, branched chain or cyclic and, above all, alkyl groups with a carbon atom number 1-15, particularly 1-12, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, nonyl etc. are preferable. These groups may be substituted optionally with a group selected from the group consisting of hydroxyl group (—OH), alkoxy group (—OR), mercapto group (—SH) and alkylthio group (—SR).
As specific examples of the phenols of the above-mentioned formula (1) there can be mentioned, for example, phenol, cresol, ethylphenol, p-tert-butylphenol, nonylphenol etc. Particularly alkyl phenols are preferable.
In the above-mentioned formula (2) the hydrocarbon group with a carbon atom number 1-15 represented by Y can be straight chain, branched chain or cyclic
Kamikado Koji
Midogochi Susumu
Nishiguchi Shigeo
Tominaga Akira
Dawson Robert
Feely Michael J
Kansai Paint Co. Ltd.
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