Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
2000-03-10
2001-11-06
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C204S506000, C204S508000, C523S410000, C523S414000, C523S458000, C523S459000
Reexamination Certificate
active
06312813
ABSTRACT:
The present invention relates to a cation-electrodepositable resin composition capable of forming a coating film with uniform coating surface and small film thickness difference and excellent in gloss and levelling property.
As a cationic electrodeposition paint is excellent in throwing power and forms a coating film excellent in durability, corrosion resistance etc., it is largely adopted for undercoating of metallic substrates such as motorcar body, electric appliances etc., which require such properties. And prior to the electrodeposition coating, it is widely conducted to chemically treat the surface of the substrate with zinc phosphate etc. in order to improve the anticorrosivity, adhesivity etc. of the electrodeposited coating film.
However, this chemically treated coating film often generates treatment marks, which cause uneven coating film thickness and when the surface of such uneven treated coating film is electrodeposition-coated, there generate defects of being prone to generate the film thickness difference of the electrodeposited coating film and the lowering of gloss and levelling property of the coating surface.
The main purpose of the present invention is to provide a cation-electrodepositable resin composition capable of forming a uniform electrodeposited coating film, having very small film thickness difference and excellent in gloss and levelling property on the surface of the chemically treated coating film, even if the thickness of said chemically treated coating film is uneven.
The present inventors conducted an intensive research aiming at achieving the above-mentioned purpose. As a result, this time, they have found out that a cationic electrodeposition paint, capable of forming a coating film, whose coating surface is uniform with very small film thickness difference and excellent in gloss and levelling property, can be obtained by further containing aromatic carboxylic acid in a resin composition for a cationic electrodeposition paint and completed the present invention.
Thus, the present invention provides a cation-electrodepositable resin composition characterized by containing
(A) a cationizable resin having crosslinkable functional group,
(B) a blocked polyisocyanate compound, and
(C) an aromatic carboxylic acid compound selected from benzoic acid, salicylic acid and their mixture.
Then, the cationic electrodeposition paint of the present invention will be described in detail.
Cationizable Resin Having Crosslinkable Functional Group (A)
As the cationizable resin (A) in the present invention, substances used hitherto as base resin in a cationic electrodeposition paint can be used in the same manner and there can be used, for example, resins having crosslinkable functional group such as hydroxyl group and cationizable group such as primary, secondary or tertiary amino group etc. in the molecule and as the resin skeleton there can be mentioned, for example, epoxy resin, acrylic resin, polybutadiene, alkyd resin, polyester resin etc. Above all, a polyamine resin, an epoxy resin added with amine, is generally suitable from a viewpoint of excellent corrosion resistance etc.
As an amine-added epoxy resin there can be mentioned, for example, (i) adducts of polyepoxide compound and primary mono- or polyamine, secondary mono- or polyamine, primary/secondary mixed polyamines etc. (cf. for example, U.S. Pat. No. 3,984,299 Specification); (ii) adducts of polyepoxide compound and secondary mono- or polyamine having ketiminized primary amino group (cf. for example, U.S. Pat. No. 4,017,438 Specification); (iii) products obtained by an etherification reaction between polyepoxide compound and hydroxyl compound having ketiminized primary amino group (cf. for example, Japanese Laid-open Patent Publication No. 43013/1984) etc.
Polyepoxide compound used for the preparation of amineadded epoxy resin is a compound having two or more epoxy groups in the molecule and has suitably in the range of generally at least 200, preferably 400-4000 of number-average molecular weight and generally at least 190, preferably 300-2000 of epoxy equivalent. Particularly substances obtained by reaction of polyphenol compound and epichlorohydrin are preferred. As polyphenol compounds usable for the formation of such polyepoxide compounds there can be mentioned, for example, bis(4-hydroxyphenyl)-2,2-propane, 4,4-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-tert-butylphenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene, bis(2,4-dihydroxyphenyl)methane, tetra(4-hydroxyphenyl)-1,1,2,2-ethane, 4,4-dihydroxydiphenylsulfone, phenol novolac, cresol novolac etc.
As amines addible to these polyepoxide compounds there can be mentioned, for example, amine compounds such as primary amines, secondary amines, tertiary amines, polyamines etc. As primary amine compounds here there can be mentioned, for example, methylamine, ethylamine, n-propylamine, isopropylamine, monoethanolamine, n-propanolamine, isopropanolamine etc.; as secondary amine compounds there can be mentioned, for example, diethylamine, diethanolamine, di-n-propanolamine, diisopropanolamine, N-methylethanolamine, N-ethylethanolamine etc.; and as tertiary amine compounds there can be mentioned, for example, triethylamine, triethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine, N,N-diethylethanolamine, N-ethyldiethanolamine etc.; further, as polyamines there can be mentioned, for example, ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethyalamine, methylaminopropylamine, dimethylaminoethylamine, dimethylaminopropylamine etc.
Further,it is possible to make a cationizable group by protonizing with acid a basic group formed by reacting epoxy group by using as cationizing agent basic compounds such as ammonia, hydroxylamine, hydrazine, hydroxyetylhydrazine, N-hydroxyethylimidazoline etc. As acids usable in that case, water-soluble organic carboxylic acids, for example, formic acid, acetic acid, glycolic acid, lactic acid etc. are preferred.
Blocked Polyisocyanate Compound (B)
A blocked polyisocyanate compound (B) in the present invention is a substance which acts as a curing agent for the abovementioned base resin, a cationizable resin, and generally a full-block addition reaction product of a polyisocyanate compound can be used.
A polyisocyanate compound is a compound having at least two isocyanate groups in the molecule and there can be mentioned, for example, aromatic, alicyclic or aliphatic polyisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, bis(isocyanatomethyl)cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate etc., and prepolymers with a molecular weight in the range of usually 150-5000 having terminal isocyanate group obtained by reacting excess amount of these polyisocyanate compounds with low molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, trimethylolpropane, hexanetriol, castor oil etc.
On the other hand, a blocking agent is a compound to add to an isocyanate group of a polyisocyanate compound and to temporarily block it. A blocked polyisocyanate compound formed by addition thereof is stable at normal temperature but when heated at higher temperature than dissociation temperature (for example, over 100° C.), the blocking agent dissociates and the isocyanate group regenerates and crosslinks with a crosslinkable functional group of the cationizable resin (A). As such a blocking agent there can be mentioned, for example, lactam type compounds such as &egr;-caprolactam, &ggr;-butyrolactam etc.; oxime type compounds such as methyl ethyl ketoxime, cyclohexanone oxime etc.; phenol type compounds such as phenol, p-t-butylphenol, cresol etc.; aliphatic alcohols such as n-butanol, 2-ethylhexanol etc.; aromatic alkyl alcohol type compounds such as phenylcarbitol, methyl phenylcarbitol etc.; ether alcohol type compounds such as ethylene glycol monobutyl ether etc. Among
Haneishi Hidehiko
Miyatake Shinji
Aylward D.
Dawson Robert
Kansai Paint Co. Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Cation-electrodepositable resin 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 Cation-electrodepositable resin composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cation-electrodepositable resin composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2578689