Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1985-05-20
1986-06-24
Nielsen, Earl
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523414, 523420, 525504, 528111, 528121, 528123, 2041817, C08G 5960, C08L 6310
Patent
active
045968446
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a water-dispersible self-hardenable resin composition, and more particularly to a self-hardenable resin composition, which as a low-temperature hardenability, and is adapted for a cationic electrodeposition painting wherein a material to be painted is used as a cathode.
BACKGROUND ART
The cationic electrodeposition painting is superior to the commonly used anionic electrodeposition painting in rust resistance of painted material, and has recently been increasingly used in the field of painting for automobile and other fields.
There have been proposed various resin compositions to be used for such cationic electrodeposition painting. However, practically used resin compositions are water-dispersible resin compositions disclosed, for example, in Japanese Patent Laid-open Specification Nos. 51,924/73 and 126,225/76, which are produced by a method wherein an epoxy resin consisting of a bisphenol A/epichlorohydrin condensate is reacted with a primary amine or secondary amine, the aminated epoxy resin is reacted with a partially blocked polyisocyanate, and the reaction product is made into water dispersible.
However, such blocked polyisocyanate type hardenable cationic electrodeposition paint has serious drawbacks that the paint is higher in baking temperature and is larger in the amount of generating tar than the conventional anionic electrodeposition paint.
DISCLOSURE OF THE INVENTION
The inventors have made various investigations in order to solve the above described problems, and found out that, when amine-imido group is pendantly introduced into a polyamine resin having amino groups and/or imino groups, the amine-imido group is thermally decomposed and rearranged at a low temperature (not lower than 120.degree. C., preferably 140.degree.-160.degree. C.) to split a tertiary amine and to form an isocyanate group according to the following formula ##STR1## and the resulting isocyanate group is reacted with hydroxyl group and/or amino or imino group in the resin to form a three-dimensional structure, whereby an infusible and insoluble hardened paint film is obtained, and the amine-imido group is neutralized with an acid to form a quarternary ammonium base, whereby a stable aqueous dispersion of cationic resin is formed and this aqueous cationic resin dispersion can be utilized in the cationic electrodeposition painting. As the result, the present invention has been accomplished.
That is, the feature of the present invention lies in a self-hardenable resin composition consisting mainly of a Michael type addition reaction product consisting of 65-95% by weight (in solid basis) of a polyamine resin having amino groups and/or imino groups and 35-5% by weight of an ethylenically unsaturated compound having an amine-imido group.
The polyamine resin having amino groups and/or imino groups to be used in the present invention (hereinafter, this resin is merely called as polyamine resin) includes, for example, a reaction product of a polyepoxide with a ketimine-blocked amino group-containing polyamine, a reaction product of a polyepoxide with a primary amine, and the like.
The polyepoxide is a compound having at least one 1,2-epoxy functional group, and includes, for example, polyglycidyl ether of polyphenol (which is obtained by etherifying polyphenol with epichlorohydrin or dichlorohydrin in the presence of an alkali) and the like.
As the polyphenol, there can be used, for example, bisphenol A [i.e., 2,2-bis(4-hydroxyphenyl)-propane], 1,1-bis(4-hydroxyphenyl)ethane, 2-methyl-1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-t-butylphenyl)propane, bis(2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene and the like.
As the polyphenol, there can be further used oxyalkylated products of polyphenol (for example, addition products of ethylene oxide or propylene oxide to polyphenol), novolac type phenolic resin, and polyphenolic resins like these oxyalkylated products of polyphenol, and novolac type phenolic resin.
As other polyepoxide, there can be used, for example
REFERENCES:
patent: 3888827 (1975-06-01), Matueda et al.
patent: 3914335 (1975-10-01), Tugukuni et al.
patent: 3925349 (1975-12-01), Gaske
patent: 4151148 (1979-04-01), Chasin et al.
patent: 4198331 (1980-04-01), Buchwalter et al.
patent: 4476271 (1984-10-01), Kano et al.
Manabe Syuichi
Ohsawa Akira
Nielsen Earl
Nippon Oil and Fats Company
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