Resin composition for aqueous coating containing glycidyl amines

A resin composition for aqueous coating, comprising as main components PA1 (A) a resin having hydroxyl groups and cationic groups, and PA1 (B) a compound having, in the molecule, at least two glycidyl groups each in a glycidylamino group represented by the following formula ##STR1## (R is a group selected from a hydrogen atom and a glycidyl group) directly bonding to carbon atoms of the aromatic ring. This composition is excellent in storage stability, low-temperature curability, etc. and is useful in cationic electrocoatings, in particular.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a resin composition for aqueous coating 
useful in cationic electro-coatings, in particular. 
2. Description of the Related Art 
Cationic electrocoatings each comprising, as the main components, a 
polyamine resin (e.g. amino-epoxy resin adduct) and a blocked 
polyisocyanate compound have been used in a large amount for their 
excellence in corrosion resistance, etc. These cationic electro-coatings, 
however, have various problems as listed below and solutions thereof are 
required strongly. 
(1) The film of such a cationic electrocoating begins to cure at a 
temperature of 170.degree. C. or more, which is too high. 
(2) When the film of the cationic electro-coating is heated at high 
temperatures, the blocked polyisocyanate compound causes thermal 
decomposition and generates a resinous tar and soot, which allows the top 
coating film to give rise to yellowing, bleeding and insufficient curing, 
gives significantly reduced weather resistance and tends to cause 
whitening. 
(3) The cationic electrocoating generally uses an organotin compound as a 
catalyst for lowering the initial temperature of curing. This compound 
poisons, in some cases, catalysts for exhaust gas combustion used in 
passenger cars. 
Resins for self-crosslinking electrocoatings using no curing agent are also 
known and were proposed in, for example, GB-B-1327071, BG-B-1306101, 
BG-B-1306102, U.S. Pat. No. 4,001,101 and GB-B-1411249. None of these 
resins can satisfy both of the bath stability and film curability of 
electrocoating. Specifically, most common epoxy compounds of glycidyl 
ether type, for example, bisphenol A diglycidyl ether and novolac phenyl 
polyglycidyl ether, have excellent curability but inferior bath stability. 
A composition using, as the curing agent, an epoxy resin having an 
alicyclic skeleton and/or a bridged alicyclic skeleton, which has been 
proposed by the present applicant in EP-A-356970, achieved most of the 
objects intended therein but is insufficient in film properties when 
baking was conducted at low temperatures for a short period of time. 
The present inventors made an extensive study with a main aim of developing 
a resin composition for aqueous coating useful particularly in cationic 
electro-coatings, which uses neither blocked polyisocyanate compound nor 
organotin compound and which is free from the above-mentioned problems 
when an epoxy resin having an alicyclic skeleton and/or a bridged 
alicyclic skeleton is used as a curing agent. As a result, the present 
inventors found that a compound having, in the molecule, at least two 
glycidyl groups each in a glycidylamino group represented by general 
formula (I) (shown later) directly bonding to carbon atoms of the aromatic 
ring, is very useful as a curing agent for a resin having hydroxyl groups 
and cationic groups and can solve all of the above-mentioned problems. The 
finding has led to the completion of the present invention. 
The curing agent identified by the present inventors does not substantially 
react, in an electro-coating bath at room temperature, with an acidic 
component (e.g. neutralizing agent), the hydroxyl group(s) of a base 
resin, etc. and resultantly gives excellent storage stability to the bath 
and further, as compared with the above-mentioned epoxy resin (curing 
agent) having an alicyclic skeleton and/or a bridged alicyclic skeleton, 
gives excellent low-temperature curability to the base resin. Moreover, 
the composition provided by the present invention requires neither blocked 
polyisocyanate compound nor organotin compound and is free from the 
above-mentioned problems caused by the use thereof. 
SUMMARY OF THE INVENTION 
The present invention provides a resin composition for aqueous coating, 
comprising as main components 
(A) a resin having hydroxyl groups and cationic groups, and 
(B) a compound having, in the molecule, at least two glycidyl groups each 
in a glycidylamino group represented by the following formula (I) 
##STR2## 
(R is a group selected from a hydrogen atom and a glycidyl group) directly 
bonding to carbon atoms of the aromatic ring. 
The present invention further provides a resin composition for aqueous 
coating, comprising the above component (A), the above component (B) and, 
as a curing agent, (C) at least one compound selected from the group 
consisting of lead compounds, zirconium compounds, cobalt compounds, 
aluminum compounds, manganese compounds, copper compounds, zinc compounds, 
iron compounds,bismuth compounds and nickel compounds. 
The present invention furthermore provides a cationic electrocoating 
containing the above resin composition for aqueous coating and a coated 
article which is coated with the cationic electrocoating. 
The electrocoating film formed by a cationic electrocoating composed mainly 
of the resin composition of the present invention for aqueous coating can 
be cured at a temperature of about 250.degree. C. or less. When the resin 
composition contains a curing catalyst (C), said film can be sufficiently 
cured as a temperature at low as about 70.degree.-160.degree. C. The 
mechanisms for these curing reactions are not yet clarified but are 
presumed to be as follows. The glycidyl groups in the component (B) cause 
ring opening, followed by (1) etherification with the hydroxyl group(s) 
[preferably, primary hydroxyl groups] in the component (A) and (2) bonding 
with each other to form ether bonds; thus, a crosslinked structure is 
formed. 
The main technical advantages provided by the resin composition of the 
present invention for aqueous coating, are as follows. 
(1) Film curing is possible at a temperature of 160.degree. C. or less 
using no tin catalyst. Therefore, all the problems caused by the use of a 
tin catalyst can be eliminated. 
(2) No blocked polyisocyanate compound is required. Therefore, all the 
problems caused by the use of a blocked polyisocyanate compound can be 
eliminated. 
(3) Since there is no volume contraction due to thermal decomposition, a 
coating film having good surface smoothness can be formed. 
(4) Since neither urethane bond nor aromatic urea bond is formed in the 
crosslinking curing reaction, the corrosion resistance is not impaired. 
(5) The coating film is excellent in corrosion resistance, curability, etc. 
(6) Gives an electrocoating bath of excellent stability. 
(7) Film curing takes place quickly even under the baking conditions of low 
temperature and short time, whereby a coating film of excellent properties 
is formed. 
DETAILED DESCRIPTION OF THE INVENTION 
The components constituting the resin composition for aqueous coating 
according to the present invention are described in more detail below. 
Component (A): a resin having hydroxyl group(s) and cationic groups in the 
molecule 
This resin is not particularly restricted as long as it has hydroxyl 
groups, particularly primary hydroxyl groups capable of reacting with the 
epoxy groups (glycidyl groups) of the component (B) and cationic groups 
necessary for the formation of a stable aqueous dispersion, and can be 
selected from a wide range. Specific examples of the resin are as follows. 
(1) A product obtained by reacting a polyepoxy resin with a cationizing 
agent. 
(2) A polycondensate between a polycarboxylic acid and a polyamine (U.S. 
Pat. No. 2,450,940). 
(3) A composition comprising (a) a product obtained by protonating a 
polyaddition product between a polyol and a mono- or polyamine with an 
acid and (b) a polyisocyanate compound. 
(4) A product obtained by protonating an acrylic or vinyl resin having 
hydroxyl group(s) and amino group(s), with an acid (U.S. Pat. Nos. 
3,455,806 and 3,454,482). 
(5) A product obtained by protonating an adduct between a polycarboxylic 
acid resin and an alkyleneimine with an acid (U.S. Pat. No. 3,403,088). 
More specific definitions of these resins and their production processes 
are described in, for example, U.S. Pat. Nos. 3,455,806, 3,454,482, 
GB-B-1327071, U.S. Pat. Nos. 2,450,940, 3,403,088, 3,891,529 and 
3,963,663. Therefore, the description is not repeated herein. 
In the present invention, the component (A) includes, as a preferable 
example, a resin obtained by reacting 
an epoxy resin (A-1) having, in the molecule, at least three epoxy 
group-containing functional groups each represented by the following 
formula (II) 
##STR3## 
a primary or secondary amine compound (A-2) having at least one primary 
hydroxyl group in the molecule, and 
a phenol compound (A-3) having at least one phenolic hydroxyl group in the 
molecule. 
The components (A-1), (A-2) and (A-3) used in production of a preferable 
resin (A), are described in detail below. 
Component (A-1): an epoxy resin having, in the molecule, at least three 
epoxy group-containing functional groups represented by the above formula 
(II). 
As the component (A-1), there can be used per-se-known resins described in, 
for example, U.S. Pat. No. 4,565,859 and Japanese Patent Application Kokai 
(Laid-Open) No. 135467/1987. 
The component (A-1) further includes those in which a residue of a 
polymerization-initiating component, i.e. a residue of an 
active-hydrogen-containing organic compound is bonded to the end of the 
above formula (II). As the active-hydrogen-containing organic compound 
which is a precursor of said residue, there can be mentioned, for example, 
an alcohol, a phenol, a carboxylic acid, an amine and a thiol. The alcohol 
may be a monohydric or polyhydric alcohol and can be exemplified by 
aliphatic monohydric alcohols such as methanol, ethanol, propanol, 
butanol, pentanol, hexanol, octanol and the like; aromatic monohydric 
alcohols such as benzyl alcohol and the like; and polyhydric alcohols such 
as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene 
glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 
1,4-butanediol, pentanediol, 1,6-hexanediol, neopentyl glycol, oxypivalic 
acid-neopentyl glycol ester, cyclohexanedimethanol, glycerine, 
diglycerine, polyglycerine, trimethylolpropane, trimethylolethane, 
pentaerythritol, dipentaerythritol and the like. 
As the phenol, there can be mentioned, for example, phenol, cresol, 
catechol, poyrogallol, hydroquinone, hydroquinone monomethyl ether, 
bisphenol A, bisphenol F, 4,4'-dihydroxybenzophenone, bisphenol S, a 
phenolic resin and a cresol novolac resin. 
The carboxylic acid can be exemplified by formic acid, acetic acid, 
propionic acid, butyric acid, fatty acids of animal and vegetable oils, 
fumaric acid, maleic acid, adipic acid, dodecanedioic acid, trimellitic 
acid, pyromellitic acid, polyacrylic acid, phthalic acid, isophthalic acid 
and terephthalic acid. As the carboxylic acid, there can also be used 
compounds having hydroxyl group(s) and carboxyl group(s), such as lactic 
acid, citric acid, oxycaproic acid and the like. 
As the active-hydrogen-containing organic compound, there can further be 
used a polyvinyl alcohol, a partial hydrolysis product of a polyvinyl 
acetate, starch, cellulose, cellulose acetate, cellulose acetate btyrate, 
hydroxyethyl-cellulose, an allyl polyol resin, a styrene-allyl alcohol 
copolymer resin, a styrene-maleic acid copolymer resin, an alkyd resin, a 
polyester polyol resin, a polycaprolactone polyol resin, etc. In the 
active-hydrogen-containing organic compound, unsaturated double bond(s) 
may be present in the skeleton together with the active hydrogen and the 
unsaturated double bond(s) may be epoxidized. 
The component (A-1) can be obtained, for example, by subjecting 
4-vinylcyclohexene-1-oxide alone or in the co-existence of other epoxy 
group-containing compound to ring-opening (co)polymerization by the epoxy 
group(s) contained therein, using an active-hydrogen-containing organic 
compound as an initiator to form a polyether resin, and then epoxidizing 
the vinyl groups of the 4-vinylcyclohexene-1-oxide portions present in the 
side chains of said resin, with an oxidizing agent such as peracid, 
hydroperoxide or the like to form functional groups each represented by 
formula (II). 
The above 4-vinylcyclohexene-1-oxide can be obtained, for example, by 
subjecting butadiene to dimerization to form vinylcyclohexene and then 
subjecting it to partial epoxidization with a peracid. 
The other epoxy group-containing compound is not particularly restricted as 
long as it has epoxy group(s) but, from the standpoint of production of 
the component (A-1), is preferably a compound having one epoxy group in 
the molecule. It can be exemplified by -olefin epoxides represented by the 
following formula 
##STR4## 
(m is 2-25), such as ethylene oxide, propylene oxide, butylene oxide and 
the like; oxides of unsaturated compounds, such as styrene oxide and the 
like; glycidyl ethers of hydroxyl group-containing compounds, such as 
allyl glycidyl ether, 2-ethylhexyl glycidyl ether, methyl glycidyl ether, 
butyl glycidyl ether, phenyl glycidyl ether and the like; and glycidyl 
esters of organic acids such as aliphatic acids and the like. 
The other epoxy group-containing compound further includes vinyl monomers 
each having an alicyclic oxirane group having double bond(s). They can be 
exemplified by the following. 
##STR5## 
In each of the above formulas, R.sub.1 represents a hydrogen atom or a 
methyl group; R.sub.2 represents a bivalent aliphatic saturated 
hydrocarbon group of 1-6 carbon atoms; and R.sub.3 represents a bivalent 
hydrocarbon group of 1-10 carbon atoms. 
As the bivalent aliphatic saturated hydrocarbon group of 1-6 carbon atoms, 
represented by R.sub.2, there can be mentioned straight-chain or branched 
chain alkylene groups such as methylene, ethylene, propylene, 
tetramethylene, ethylethylene, pentamethylene, hexamethylene and the like. 
As the bivalent hydrocarbon group of 1-10 carbon atoms, represented by R3, 
there can be mentioned, for example, methylene, ethylene, propylene, 
tetramethylene, ethylethylene, pentamethylene, hexamethylene, 
polymethylene, phenylene, 
##STR6## 
etc. 
As the other epoxy group-containing compound, there can further be used 
compounds represented by the following general formula (XV) 
##STR7## 
(R.sub.1 and R.sub.2 are as defined above), such as glycidyl acrylate, 
glycidyl methacrylate and the like; and compounds each having an alicyclic 
unsaturated group, represented by the following formula (XVI) 
##STR8## 
which is obtained as a by-product when vinylcyclohexene is subjected to 
partial epoxidization. There can furthermore be used 4-vinylcycloheptene 
(vinylnorbornene), etc. 
The ring-opening (co)polymerization reaction be epoxy group, of 
4-vinylcyclohexene-1-oxide alone or in the co-presence of other epoxy 
group-containing compound is preferably conducted using an 
active-hydrogen-containing organic compound and further a catalyst. As the 
catalyst, there can be mentioned, for example, amines such as methylamine, 
ethylamine, propylamine, piperazine and the like; organic bases such as 
pyridine, imidazole and the like; organic acids such as formic acid, 
acetic acid, propionic acid and the like; inorganic acids such as sulfuric 
acid, hydrochloric acid and the like; alkali metal alcoholates such as 
sodium methylate and the like; alkalis such as KOH, NaOH and the like; 
Lewis acids or complexes thereof such as BF.sub.3 ZnCl.sub.2, AlCl.sub.3, 
SnCl.sub.4 and the like; organometal compounds such as triethyl aluminum, 
diethyl zinc and the like. 
The catalyst can be used in an amount of 0.001-10% by weight, preferably 
0.1-5% by weight based on the materials to be reacted. The appropriate 
temperature of the ring-opening (co)polymerization reaction is generally 
about -70.degree. C. to about 200.degree. C., preferably about -30.degree. 
C. to about 100.degree. C. The reaction can be conducted using a solvent. 
The solvent is preferably an ordinary organic solvent having no active 
hydrogen. 
By the above reaction can be obtained a polyether resin [a ring-opening 
(co)polymer] having vinyl groups in the side chains. The vinyl groups are 
epoxidized to introduce functional groups each represented by the 
above-mentioned formula (II) into the polyether resin, whereby a component 
(A-1) can be obtained. This epoxidization can be conducted using a 
peracid, a hydroperoxide or the like. As the peracid, there can be used, 
for example, performic acid, peracetic acid, perbenzoic acid and 
trifluoroperacetic acid. As the hydroperoxide, there can be used, for 
example, hydrogen peroxide, tert-butyl peroxide and cumene peroxide. The 
epoxidization reaction can be conducted using a catalyst, as necessary. 
Epoxidization of the vinyl group of 4-vinylcyclohexene-1-oxide gives a 
functional group represented by the above formula (II). When in this 
epoxidization there co-exists, as the other epoxy group-containing 
compound, the above-mentioned vinyl monomer having an alicyclic oxirane 
group, the vinyl group in the monomer is epoxidized as well but gives a 
functional group different from that of formula (II). 
The presence or absence of a solvent and reaction temperature used in the 
epoxidization reaction can be appropriately determined depending upon the 
equipment and raw materials used. 
As the component (A-1), there can also be used commercial products, for 
example, EHPE 3150 (trade name) manufactured by DAICEL CHEMICAL 
INDUSTRIES, LTD. This product is obtained by subjecting 
4-vinylcyclohexene-1-oxide to ring-opening polymerization and epoxidizing 
the vinyl groups in the resulting polymer, and has a polymerization degree 
of 4-15 on an average. 
The amount of the epoxy group-containing functional group represented by 
formula (II), in the component (A-1) is appropriately at least three in 
terms of the number of the functional group and is preferably 140-1,000, 
more preferably 170-300 in terms of epoxy equivalents. 
Component (A-2): a primary or secondary amine compound having at least one 
primary hydroxyl group in the molecule. 
This component reacts with the component (A-1) and introduces a primary 
hydroxyl group and a basic group into the component (A-1). 
The amine group in the component (A-2) reacts with the epoxy group of the 
epoxy group-containing functional group represented by formula (II), in 
the component (A-1) to form a cationic resin. This cationic resin having 
primary hydroxyl groups and basic groups, as compared with the 
above-mentioned resin formed by reaction with a conventional bisphenol A 
type epoxy resin, is much superior in dispersibility in water and throwing 
property even in a partially neutralized state or at a high pH, and the 
film formed therewith shows substantially no reduction in curability, 
corrosion resistance, etc. 
The component (A-2) can be exemplified by the following compounds. 
(1) Monoalkanolamines such as monoethanolamine, monopropanolamine, 
monobutanolamine and the like. 
(2) N-alkylalkanolamines and dialkanolamines such as N-methylethanolamine, 
N-ethylethanolamine, diethanolamine, di-n (or iso)-propanolamine, 
dibutanolamine and the like. 
(3) Adducts between monoalkanolamine and .alpha.,.beta.-unsaturated 
carbonyl compound, such as 
monoethanolamine-N,N-dimethylaminopropylacrylamide adduct, 
monoethanolamine-hydroxyethyl (meth)acrylate adduct, 
monoethanolamine-hydroxypropyl (meth)acrylate adduct, 
monoethanolamine-hydroxybutyl (meth)acrylate adduct and the like. 
(4) Monoalkanolaminoalkylamines such as hydroxyethylaminoethylamine and the 
like. 
(5) Condensates between (a) at least one compound selected from 
hydroxyethylamine, hydroxyethylhydrazine and hydroxybutrylhydrazine and 
(b) a ketone compound, for example, a dialkylketone such as dimethyl 
ketone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, 
dipropyl ketone or the like. 
(6) Amine compounds having a primary hydroxyl group, a secondary amino 
group and an amido group in the molecule, represented by the following 
general formula (XVII) 
##STR9## 
wherein n is an integer of 1-6 and R.sub.4 is a hydrocarbon chain of 4-36 
carbon atoms which may have a hydroxyl group and/or a polymerizable 
unsaturated group. 
The "alkyl" in each of the above amine compounds (1) to (5), preferably has 
1-6 carbon atoms, particularly 1-4 carbon atoms. 
The amine compound represented by the above formula (XVII) can be obtained, 
for example, by subjecting about equal moles of an 
N-hydroxyalkylalkylenediamine and a monocarboxylic acid of 5-37 carbon 
atoms to a dehydration and condensation reaction. The diamine is 
preferably, for example, a primary and secondary diamine having a primary 
hydroxyl group, such as hydroxyethylaminoethylamine, 
N-hydroxyethylpropylenediamine, N-hydroxyethylbutylenediamine, 
N-hydroxyethylpentylenediamine, N-hydroxyethylhexylenediamine or the like. 
The monocarboxylic acid includes, for example, mixed fatty acids such as 
coconut oil fatty acid, castor oil fatty acid, rice bran oil fatty acid, 
soybean oil fatty acid, tall oil fatty acid, dehydrated castor oil fatty 
acid, safflower oil fatty acid, linseed oil fatty acid, tung oil fatty 
acid and the like; caprylic acid; capric acid; lauric acid; myristic acid; 
palmitic acid; stearic acid; oleic acid; ricinoleic acid; linolic acid; 
linolenic acid; eleostearic acid; 12-hydroxystearic acid; and behenic 
acid. 
The reaction between the diamine and the monocarboxylic acid for obtaining 
an amine compound represented by the formula (XVII) is conducted by mixing 
the two components in about equal moles and removing a given amount of the 
generated water with an organic solvent such as toluene, methyl isobutyl 
ketone or the like. The remaining organic solvent is removed by a reduced 
pressure method or the like to obtain an intended amine compound. The thus 
obtained amine compound preferably has an amine (secondary amine) value of 
88-350, particularly 120-230 and a hydroxyl (preferably primary hydroxyl) 
value of 44-350, particularly 60-230. 
Of the compounds (1) to (6) each as the component (A-2), there are 
preferred the compounds (2), the compounds (3) and the primary 
alkanol-containing secondary amines of the compounds (6). Combined use of 
an amine compound of formula (XVII) (particularly, hydroxyethylaminoethyl 
fatty acid amide) and diethanolamine is particularly preferable because it 
can improve, for example, the smoothness and corrosion resistance of 
coating film surface. The proportions of said amine compound (preferably, 
hydroxyethylaminoethyl fatty acid amide) and diethanolamine are preferably 
30-80% by weight and 70-20% by weight, respectively, based on the total 
weight of the two components. 
Component (A-3): a phenol compound having at least one phenoic hydroxyl 
group in the molecule. 
As said phenol compound, there can be mentioned, for example, polyphenol 
compounds such as bis(4-hydroxyphenyl)-2,2-propane, 
4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, 
bis(4-hydroxyphenyl)-1,1-isobutane, 
bis(4-hydroxy-tertbutyl-phenyl)-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'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, phenol 
novolac, cresol novolac and the like. There can also be sued monophenol 
compounds such as phenol, nonylphenol, .alpha.- or .beta.-naphthol, 
p-tert-octylphenol, o- or p-phenylphenol and the like. 
In order to form a coating film of higher corrosion resistance, it is 
preferable that there be used, as the component (A-3), particularly a 
bisphenol resin derived from a bisphenol, such as bisphenol A 
[bis(4-hydroxyphenyl)-2,2-propane] bisphenol F 
[bis(4-hydroxyphenyl)-2,2-methane] or the like. Particularly suitable as 
such a bisphenol resin is one having a number-average molecular weight of 
at least 200, preferably about 800-about 3,000 and, on an average, two or 
less, preferably 0.8-1.2 phenolic hydroxyl group in the molecule, 
represented by the following general formula (XVIII): 
##STR10## 
wherein q is an integer of 0-7 on an average and R.sub.5 is a residue of 
an active-hydrogen-containing compound. 
As the active-hydrogen-containing compound which is a precursor of the 
R.sub.5 of the above formula, there can be mentioned, for example, amines 
such as secondary amine and the like; phenols such as phenylphenol, 
nonylphenol and the like; organic acids such as fatty acid and the like; 
thiols; alcohols such as alkyl alcohol, cellosolve, butyl cellosolve 
carbitol and the like; and inorganic acids. Of these compounds, most 
preferable are dialkanolamines which are each a secondary amine having a 
primary hydroxyl group; phenols such as nonylphenol, phenylphenol, phenol, 
hydroquinone monomethyl ether and the like; fatty acids such as stearic 
acid, oleic acid, soybean oil fatty acid and the like; organic acids such 
as acetic acid, formic acid, hydroxyacetic acid and the like; and so 
forth. 
The above formula (XVIII) representing the component (A-3) has R.sub.5 -- 
and --OH at the two ends. However, the component (A-3) may also contain a 
compound having only R.sub.5 -- or --OH at the Two ends. 
In the present invention, the component (A-3) can be obtained, for example, 
by reacting (a) 1 mole of a polyepoxide of bisphenol A diglycidyl ether 
type having a molecular weight of 200 or more, preferably 380-2,000, (b) 1 
mole of a polyphenol of bisphenol A type having a molecular weight of at 
least 200, preferably 200-2,000 and (c) 1 mole of an 
active-hydrogen-containing compound, for example, a secondary 
dialkanolamine in the presence of a catalyst and/or a solvent as 
necessary, at temperature of 30.degree.-300.degree. C., preferably 
70.degree.-180.degree. C. The above molar ratio is merely illustrative and 
not restrictive, and can be determined as desired. 
The component (A-3) can also be obtained by reacting the above phenolic 
compound with a polyol (e.g. dimerdiol, ethylene glycol, propylene glycol 
or butylene glycol), a polyether polyol (e.g. polyethylene glycol, 
polypropylene glycol or polybutylene glycol), a polyester polyol (e.g. 
polycaprolactone), a polycarboxylic acid, a polyisocyanate, a 
monoisocyanate, an oxide of an unsaturated compound (e.g. ethylene oxide, 
propylene oxide, butylene oxide or styrene oxide), a glycidyl ether of a 
hydroxyl group-containing compound (e.g. allyl glycidyl ether, 
polypropylene glycol diglycidyl ether, 2-ethylhexyl glycidyl ether, methyl 
glycidyl ether, butyl glycidyl ether or phenyl glycidyl ether), a glycidyl 
ester of an organic acid such as fatty acid or the like, a compound having 
an alicyclic oxirane group, or the like; or by graft-polymerizing 
.delta.-4-caprolactone, an acrylic monomer or the like to the above 
phenolic compound. 
The reaction between the component (A-1), the component (A-2) and the 
component (A-3) can be conducted by any ordinary process and the reaction 
order thereof is not particularly restricted. The reaction can be 
conducted generally at 50.degree.-300.degree. C., preferably 
70.degree.-200.degree. C. For example, the component (A-1) and the 
component (A-3) are reacted and then the component (A-2) is reacted. 
It is also possible that a polyepoxide and a polyphenol, both of which are 
raw materials of the component (A-3) having a phenolic hydroxyl group, be 
reacted in the presence of the component (A-1) and the component (A-2) to 
save the step for production of the component (A-3). 
In another possible process, part of the component (A-1) is reacted with 
the component (A-2); to the reaction mixture is added the component (A-3) 
in an amount larger than the equivalents of the unreacted epoxy groups in 
the reaction product, derived from the component (A-1), to give rise to a 
reaction; thereafter, the unreacted portion of the component (A-3) is 
reacted with a polyepoxide other than the component (A-1). 
The proportions of the components (A-1), (A-2) and (A-3) used can be 
determined as desired. 
The component (A-1), even when contained in a small amount in the present 
resin composition for cationic electrocoating, can significantly improve 
the dispersibility in water and throwing property of said cationic 
electrocoating. Hence, the amount of the component (A-1) can be 0.5-95% by 
weight, preferably 3-75% by weight, particularly preferably 5-50% by 
weight based on the total amount of the components (A-1), (A-2) and (A-3). 
The preferable amount of the component (A-3) is 1-95% by weight, preferably 
20-90% by weight, more preferably 40-80% by weight based on the total 
amount of the components (A-1), (A-2) and (A-3) in order to impart a 
bisphenol skeleton and high corrosion resistance. 
In the component (A) of the present invention, the content of cationic 
groups is desirably a level enabling stable dispersion in water and yet 
being low. Preferably, the content is generally 3-200, particularly 5-180, 
more particularly 15-150 in terms of amine value expressed in KOH mg per g 
of solid content. Even when the content of the cationic groups is less 
than 3, dispersion in water is possible by the use of a surfactant or the 
like. In this case, however, the cationic groups is (are) desirably 
controlled so that the resulting aqueous dispersion has a pH of 4-9, 
preferably 6-7. 
Further, in the component (A), preferably the content of the primary 
hydroxyl groups formed by the reaction between the component (A-2) and the 
epoxy group-containing functional groups of formula (II) in the component 
(A-1) is generally 10-1,000, particularly 30-500, more particularly 50-200 
in terms of hydroxyl value of said primary hydroxyl groups, expressed in 
KOH mg per g of solid content, in view of the reactivity with curable 
functional groups. 
In the reaction of the components (A-1), (A-2) and (A-3) for obtaining the 
component (A) of the present invention, part of the component (A-2) may be 
replaced by other cationizing agent as necessary. As such a cationizing 
agent, there can be mentioned, for example, primary amines such as 
methylamine, ethylamine, n- or isopropylamine and the like; secondary 
amines such as diethylamine, dipropylamine, dibutylamine and the like; and 
polyamines such as ethylenediamine, diethylenetriamine, 
ethylaminoethylaine, methylaminopropylamine, dimethylaminoethylamine, 
dimethylaminopropylamine and the like. As the other cationizing agent, 
there can also be used ammonia, hydrazine, N-hydroxyethylimidazoline, etc. 
As the other cationizing agent, there can further be used compounds having 
in the molecule, a secondary hydroxyl group, a secondary amino group and 
an amido group, which can be obtained by using a primary and secondary 
diamine having a secondary hydroxyl group, in place of the primary and 
secondary diamine having a primary hydroxyl group, used in the production 
of the component (A-2) (6) and reacting said primary and secondary diamine 
with a monocarboxylic acid. 
As the other cationizing agent, there can be furthermore used tertiary 
amines such as triethylamine, triethanolamine, N,N-dimethylethanolamine, 
N-methyldiethanolamine, N,N-diethylethanolamine, N-ethyldiethanolamine and 
the like. These tertiary amines can be quaternized by protonation with an 
acid and subsequent reaction with epoxy groups. 
As the other cationizing agent, there can be used, besides the 
above-mentioned amino compounds, a salt between a sulfide (e.g. diethyl 
sulfide, diphenyl sulfide, tetramethylene sulfide or thiodiethanol) and 
boric acid, carbonic acid, an organic monocarboxylic acid or the like, and 
the epoxy groups in the resin (A) are reacted with said salt to introduce 
tertiary sulfonium salt groups. As the other cationizing agent, there can 
also be sued a salt between a phosphine (e.g. triethylphosphine, 
phenyldimethylphosphine, diphenylmethylphosphine or triphenylphosphine) 
and an acid such as mentioned above, and the epoxy groups in the resin (A) 
are reacted with said salt to introduce quaternary phosphonium salt 
groups. 
When part of the component (A-2) is replaced by other cationizing agent, 
the amount of the other cationizing agent used is not particularly 
restricted as long as the resulting component (A) has primary hydroxyl 
group(s) in the above mentioned amount (preferably, 10-1,000, particularly 
preferably 50-700). 
The component (A) has excellent dispersibility in water and, when added to 
an organic or inorganic substance which has no or only slight 
dispersiblity in water, allows the substance to have improved 
dispersibility in water. Therefore, the component (A) or the present resin 
composition for aqueous coating may be added to conventional cationic 
electrocoatings for their improvement in dispersibility in water. 
The present resin composition for aqueous coating is characterized in that 
the component (A) is used in combination with a compound (B) as a curing 
agent, having, in the molecule, at least two glycidyl groups each in a 
glycidylamino group represented by the above formula (I) directly bonding 
to a carbon atom of the aromatic ring. 
Component (B): a compound having, in the molecule, at least two glycidyl 
groups each in a glycidylamino group represented by the following formula 
(I) 
##STR11## 
(R is a group selected from a hydrogen atom and a glycidyl group) directly 
bonding to carbon atoms of the aromatic ring. 
The component (B) has an aromatic ring and glycidyl groups in the molecule. 
In the component (B), each of said glycidyl groups is introduced by the 
glycidylamino group represented by the formula (I), and the nitrogen atom 
in the formula (I) bonds directly to a carbon of the aromatic ring. 
The component (B) can be obtained generally by contacting the amino group 
(--NH.sub.2) of an aniline derivative with an epihalohydrin (preferably 
epichlorohydrin) in the presence of a catalyst such as aqueous alkali 
metal hydroxide solution or the like to give rise to a dehydrohalogenation 
(condensation) reaction. This reaction can be conducted by a per se known 
process. 
In this reaction, theoretically one mole of glycidyl group is introduced 
into the amino group by reacting 1 mole of an epihalohydrin with 1 mole of 
the amino group. The resulting amino group has one remaining hydrogen atom 
which corresponds to the R (a hydrogen atom) of the formula (I). In this 
reaction, when two moles of the epihalohydrin are reacted, two glycidyl 
groups are introduced into the amino group and one of these glycidyl 
groups corresponds to the R (a glycidyl group) of the formula (1). The 
above aniline derivative is, in a broad definition, a compound having an 
aromatic ring such as benzene ring, naphthalene ring or the like and at 
least one amino group (--NH.sub.2) directly bonding to a carbon atom of 
said aromatic ring. As the aniline derivative, there can be mentioned, for 
example, monoaniline derivatives having an aromatic ring such as benzene 
ring, naphthalene ring or the like and one amino group (--NH.sub.2) 
directly bonding to a carbon atom of the aromatic ring, such as aniline, 
o-toluidine, m-toluidine, p-toluidine, o-ethylaniline, m-ethylaniline, 
p-ethylaniline, p-cresidine, 2,4-xylidine, 3,4-xylidine, o-anisidine, 
p-anisidine, naphthylamine and the like; and dianiline derivatives having 
an aromatic ring such as benzene ring, naphthalene ring or the like and 
two amino groups (--NH.sub.2) directly bonding to carbon atoms of the 
aromatic ring, such as phenylenediamine, 2,4-toluylenediamine, 
diaminobenzanilide, dianisidine, diaminodiphenyl ether, 
3,5-diaminochlorobenzene, 3,3'-dimethylbenzidine, 1,5-naphthylenediamine 
and the like. 
The aniline derivative may also be a polycondensate obtained by reacting 
the above mono- or dianiline derivative with an aldehyde (e.g. 
formaldehyde or acetaldehyde) or a ketone (e.g. acetone, methyl ethyl 
ketone or methyl isobutyl ketone) using, as a catalyst, an inorganic acid 
(e.g. hydrochloric acid, phosphoric acid or sulfuric acid), an organic 
acid (e.g. p-toluenesulfonic acid or oxalic acid), a metal salt (e.g. zinc 
acetate) or the like to form a plurality of aromatic rings bonded with 
methylene group(s) or the like. In the above polycondensate, the number of 
the recurring unit of aromatic rings is preferably 2-40, particularly 
preferably 2-20. Such a polycondensate can be exemplified by 
diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane and 
3,3'-diethyl-4,4'-diaminodiphenylmethane. Of course, other polycondensates 
can be used. 
With respect to the component (B), part of the glycidyl groups may be 
reacted, for modification, with at least one compound selected from 
phenols such as bisphenol A, bisphenol F, phenylphenol, nonylphenol, 
phenol and the like; higher fatty acids such as dimer acids, stearic acid, 
oleic acid, soybean olifatty acid and the like; organic acids such as 
formic acid, acetic acid, hydroxyacetic acid and the like; alcohols such 
as alkyl alcohol, cellosolve, carbitol and the like; and so forth. Of 
these compounds, particularly preferable are phenols and higher fatty 
acids. In the modification, use of a catalyst such as zinc borofluoride, 
tetramethylammonium chloride or the like is preferable. 
The component (B) used in the present invention preferably has a 
number-average molecular weight as measured by vapor-pressure osmometry, 
of about 150-about 8,000, particularly 150-5,000, more particularly 
200-3,000 and epoxy equivalents of 100-2,000, particularly 100-600, more 
particularly 100-400. As the component (B), there may be used commercial 
products, for example, GAN [N,N-diglycidylaniline manufactured by Nippon 
Kayaku CO., LTD.], GOT [N,N-diglycidyl-o-toluidine manufactured by Nippon 
Kayaku CO., LTD.], MY 720 
[N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane manufactured by 
Ciba-Geigy (Japan) Limited] any MY 722 
[N,N,N'-N'-tetraglycidyl-3,3'-dimethyl-4,4'-diaminodiphenylmethane 
manufactured by Ciba-Geigy (Japan) Limited]. 
The present resin composition for aqueous coating can be prepared by 
neutralizing part or the whole part of the basic groups of the component 
(A) with an acid, mixing the resulting compound with the component (B), 
and dissolving or dispersing the mixture in water. The neutralization can 
be conducted before or after the mixing of the two components. As the acid 
used for neutralization, there can be mentioned, for example, formic acid, 
acetic acid, lactic acid, butyric acid and a cation acid. The proportions 
of the component (A) and the component (B) can be varied over a wide range 
depending upon the applications of the resulting resin composition for 
aqueous coating, but preferably are the component (A)/the component 
(B)=30/70 to 90/10, particularly 50/50 to 85/15, more particularly 60/40 
to 70/30. 
Component (C) 
This is a curing catalyst used for conducting a crosslinking reaction 
between the component (A) and the component (B) contained in the present 
resin composition, at lower temperature. 
Such a catalyst is at least one compound selected from lead compounds, 
zirconium compounds, cobalt compounds, aluminum compounds, manganese 
compounds, copper compounds, zinc compounds, iron compounds, bismuth 
compounds and nickel compounds. Specific example of the catalyst are 
chelate compounds such as zirconium acetylacetonate, cobalt 
acetylacetonate, aluminum acetylacetonate, manganese acetylacetonate, iron 
acetylacetonate and the like; chelate reaction products between a compound 
having a .beta.-hydroxyamino structure and lead (II) oxide; and 
carboxylates such as lead 2-ethylhexanoate, lead dimethylhexanoate, lead 
naphthenate, lead octenoate, lead benzoate, lead acetate, lead lactate, 
lead formate, lead glycolate, zirconium octenoate, bismuth octenoate, zinc 
octenoate and the like. 
The component (C) can be mixed with the component (A) beforehand, or can be 
added when the component (A) and the component (B) are mixed, or may be 
added when the pigment(s) (mentioned later) is (are) added. The amount of 
the component (C) used can be varied as desired, depending upon the 
applications of the resulting resin composition, but preferably is 
generally 10% by weight or less, particularly 0.2-5% by weight based on 
the total solid weight of the component (A) and the component (B). 
The present resin composition for aqueous coating is used as a main or 
auxiliary component for film formation, in an aqueous coating using water 
as a solvent or a dispersing medium. It can be used particularly 
preferably as a main or auxiliary component for film formation, in a 
cationic electrocoating. In such use, the present resin composition for 
aqueous coating can exhibit technical effects such as mentioned above. 
The present resin composition for aqueous coating and the present cationic 
electrocoating can further comprise, as necessary, various pigments. As 
the pigments, there can be specifically mentioned color pigments such as 
carbon black, titanium white, white lead, lead oxide, red iron oxide and 
the like; extender pigments such as clay, talc and the like; anticorrosion 
pigments of inorganic metal compounds, such as strontium chromate, lead 
chromate, basic lead chromate, red lead, lead silicate, basic lead 
silicate, lead phosphate, basic lead phosphate, lead tripolyphosphate, 
lead silicochromate, lead suboxide, lead sulfate, basic lead sulfate, 
chrome yellow, lead cyanamide, calcium plumbate and the like. The present 
resin composition for aqueous coating and the present cationic 
electrocoating can furthermore comprise known dispersing agents and 
anticissing agents as necessary. 
The method of electrocoating using the present cationic electrocoating is 
not strictly restricted and the application can be conducted under the 
conditions employed ordinarily. For example, the concentration (solid 
content) of the electrocoating bath can be controlled in the range of 
5-40% by weight, preferably 10-25% by weight and the pH can be controlled 
at 5-8, preferably 5.5-7. Appropriately, the bath temperature is 
20.degree.-35.degree. C., preferably 25.degree.-30.degree. C.; the current 
density is 0.005-2 A/cm.sup.2, preferably 0.01-1 A/cm.sup.2 ; the voltage 
is 10-500 V, preferably 100-300 V; and the time of flowing electricity is 
0.1-10 minutes, preferably 2-4 minutes. The film thickness of 
electrocoating is not strictly restricted but is generally 3-200.mu. in 
terms of cured film thickness. It is preferable that after coating, the 
coated article be pulled up from the electrocoating bath, water-washed, 
air-dried as necessary, and subjected to thermal curing at 
70.degree.-250.degree. C., preferably 120.degree.-160.degree. C.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Next, the present invention is described more specifically by way of 
Examples. In the Examples, parts and % are by parts by weight and % by 
weight, respectively, unless otherwise specified. 
I. Production Examples 
(I-1) Production of components (A-2) used in preparation of components (A) 
(A-2-1): 
Into a flask equipped with a stirrer, a thermometer, a dropping funnel and 
a reflux condenser were fed 288 parts of tall oil fatty acid, 104 parts of 
hydroxyethylaminoethylamine and 80 parts of toluene. They were slowly 
heated with stirring, and 18 parts of the water generated was removed. The 
remaining toluene was also removed under reduced pressure to obtain an 
amino compound having a primary hydroxyl group. The compound had an amine 
value of 149, a solidification point of 50.degree. C. and a hydroxyl value 
of 149. 
(A-2-2): 
39 parts of monoethanolamine was fed into a flask equipped with a stirrer, 
a thermometer, a dropping funnel and a reflux condenser. Thereto was 
dropwise added 100 parts of N,N-dimethylaminopropylacrylamide with the 
temperature kept at 60.degree. C. A reaction was conducted at 60.degree. 
C. for 5 hours. 
(I-2) Production of components (A) 
(A-I): 
Into a flask equipped with a stirrer, a thermometer, a dropping funnel and 
a reflux condenser were fed 900 parts EHPE-3150 (trade name) as component 
(A-1) [a product of Daicel Chemical Industries, LTD. obtained by 
epoxidizing the vinyl groups of a ring-opening polymer of 
4-vinylcyclohexene-1-oxide; epoxy equivalents=180; polymerization 
degree=4-15 on an average], 200 parts of ethylene glycol monobutyl ether, 
315 parts of diethanolamine as component (A-2) and 370 parts of an amino 
compound (A-2-1). They were slowly heated with stirring for dissolution 
and reacted at 140.degree. C. After it was confirmed that epoxy 
equivalents of 1,585 were obtained, 2,052 parts of bisphenol A as 
component (A-3) was added. A reaction was conducted at 150.degree. C. for 
5 hours, and it was confirmed that no epoxy group remained. 
Then, there were added 420 parts of diethanolamine as component (A-2), 
4,370 parts of bisphenol A diglycidyl ether having epoxy equivalents of 
190 as component (A-3), 740 parts of an amino compound (A-2-1) and 2,092 
parts of ethylene glycol monobutyl ether. A reaction was conducted at 
150.degree. C. for 5 hours, and it was confirmed that no epoxy group 
remained, whereby (A-1) was obtained which had a solid content of 80%, an 
amine value of 61 and primary hydroxyl group equivalents of 540. 
(A-II): 
Into a flask equipped with a stirrer, a thermometer, a dropping funnel and 
a reflux condenser were fed 900 parts of EHPE-3150 (trade name) as 
component (A-1) [a product of Daicel Chemical Industries, LTD.; epoxy 
equivalents=180], 200 parts of ethylene glycol monobutyl ether, 420 parts 
of diethanolamine as component (A-2) and 2,052 parts of bisphenol A as 
component (A-3). They were slowly heated with stirring and reacted at 
140.degree. C. It was confirmed that no epoxy group remained. 
Then, there were added 630 parts of diethanolamine as component (A-2), 
3,990 parts of bisphenol A diglycidyl ether having epoxy equivalents of 
190 as component (A-3), 760 parts of polypropylene glycol diglycidyl ether 
having epoxy equivalents of 380 as component (A-3) and 1,988 parts-of 
ethylene glycol monobutyl ether. A reaction was conducted at 150.degree. 
C. for 5 hours, and it was confirmed that no epoxy group remained, 
whereby (A-II) was obtained which had a solid content of 0%, an amine 
value of 64 and primary hydroxyl group equivalents of 438. 
(A-III): 
Into a flask equipped with a stirrer, a thermometer, a dropping funnel and 
a reflux condenser were fed 21 parts of diethanolamine, 950 parts of 
bisphenol A diglycidyl ether having epoxy equivalents of 190, 340 parts of 
polypropylene glycol diglycidyl ether having epoxy equivalents of 340 and 
2,052 parts of bisphenol A. They were slowly heated with stirring and 
reacted at 120.degree. C. After it was confirmed that epoxy equivalents of 
980 was obtained, 479 parts of ethylene glycol monobutyl ether was added. 
While the system was kept at 100.degree. C., 158 parts of diethanolamine 
and 43 parts of an amino compound (A-2-2) were added. A reaction was 
conducted until there was no viscosity increase, whereby (A-III) was 
obtained which had a solid content of 80%, an amine value of 54 and 
primary hydroxyl group equivalents of 518. 
(I-3) Production of components (B) 
(B-1): 
Into a flask equipped with a stirrer, a thermometer and a reflux condenser 
were fed 100 parts of N,N-diglycidyl-o-toluidine (GOT, a product of Nippon 
Kayaku CO., LTD.) and 25 parts of ethylene glycol monobutyl ether. They 
were heated for dissolution, whereby (B-1) was obtained which had a solid 
content of 80% and epoxy equivalents of 117. 
(B-2): 
Into a flask equipped with a stirrer, a thermometer and a reflux condenser 
were fed 100 parts of N,N,N',N-tetraglycidyl-4,4'-diaminodiphenylmethane 
[MY 720, a product of Ciba-Geigy (Japan) Limited] and 25 parts of ethylene 
glycol monobutyl ether. They were heated for dissolution, whereby (B-2) 
was obtained which had a solid content of 80% and epoxy equivalents of 
115. 
(B-3): 
Into a flask equipped with a stirrer, a thermometer and a reflux condenser 
were fed 100 parts of 
N,N,N',N'-tetraglycidyl-3,3'-dimethyl-4,4'-diaminodiphenylmethane [MY 722, 
a product of Ciba-Geigy (Japan) Limited] and 25 parts of ethylene glycol 
monobutyl ether. They were heated for dissolution, whereby (B-3) was 
obtained which had a solid content of 80% and epoxy equivalents of 125. 
(B-4): for comparison 
Into a flask equipped with a stirrer, a thermometer and a reflux condenser 
were fed 100 parts of EHPE-3150 (trade name) [a product of Daicel Chemical 
Industries, LTD. obtained by epoxidizing the vinyl groups of a 
ring-opening polymer of 4-vinylcyclohexene-1-oxide; polymerization 
degree=4-15] and 25 parts of ethylene glycol monobutyl ether. They were 
heated for dissolution, whereby (B-4) was obtained which had a solid 
content of 80% and epoxy equivalents of 180. 
(B-5): for comparison 
Into a flask equipped with a stirrer, a thermometer and a reflux condenser 
were fed 100 parts of N,N,N',N'-tetraglycidyl-m-xylylenediamine (TETRAD-X, 
a product of Mitsubishi Gas Chemical Co., Inc.) and 25 parts of ethylene 
glycol monobutyl ether. They were heated for dissolution, whereby (B-5) 
was obtained which had a solid content of 80% and epoxy equivalents of 
101. 
(B-6): for comparison 
250 parts of MDI (4,4'-diphenylmethane diisocyanate) was fed into a flask 
equipped with a stirrer, a thermometer and a reflux condenser, and heated 
and melted at 80.degree. C. Thereto was dropwise added, at 80.degree. C. 
in 60 minutes, a mixture of 130 parts of 2-ethylhexyl alcohol and 134 
parts of diethylene glycol monoethyl ether. The resulting mixture was 
heated to 120.degree. C. After it was confirmed that there was no 
absorption by an isocyanate group by IR spectrometer, 128.5 parts of 
ethylene glycol monobutyl ether were added, whereby (B-6) was obtained 
which had a solid content of 80% and blocked isocyanate equivalents of 
257. 
(I-4) Production of pigment pastes (p-1) 
To 10 parts of each of the above-produced components (A) were added 20 
parts of titanium white (Tipaque CR 93, a product of Ishihara Sangyo 
Kaisha, Ltd.), a 2 parts of carbon black (MA-7, a product of Mitsubishi 
Chemical Industries, Ltd.), 4 parts of aluminum tripolyphosphate (K white 
84, a product of Teikoku Kako CO., LTD.), 24 parts of clay (Zeekilite, a 
product of Zeekilite Corp. Ltd.), 0.4 part of acetic acid and 39.6 parts 
of deionized water. They were kneaded. Then, 200 parts of glass beads were 
added, and the mixture was treated by a paint shaker to obtain 
pigment-dispersed pastes (p-1) each containing coarse particles of 10.mu. 
or less as measured by a particle gauge and having a solid content of 58%. 
II. Examples and Comparative Examples 
One of the components (A) and one of the components (B), both produced 
above, were mixed together with a neutralizing agent, as shown in Table 1. 
They were stirred and made into a dispersion. Thereto was added deionized 
water to adjust the solid content to 30%. To 333 parts of each of the thus 
obtained emulsions was added a mixture of 75 parts of one of the pigment 
pastes produced above and 2.6 parts of a catalyst (lead octenoate or zinc 
octenoate). Thereto was added deionized water to adjust the solid content 
to 20%, whereby various cationic electrocoatings were obtained. In 
comparative Example 4, 5.6 parts of dibutyltin dilaurate (tin content=18%) 
was further added as an additional catalyst. 
Each of these cationic electrocoatings was applied onto a zinc 
phosphate-treated steel plate and an untreated steel plate by 
electrocoating (electrocoating bath temperature=25.degree. C., 
voltage=100-250 V, time of electricity flowing=3 minutes), followed by 
water washing and baking at 170.degree. C. for 30 minutes or at 
160.degree. C. for 10 minutes to obtain a cured coated film. The 
properties of each coating film were measured and the results are shown in 
Table 2. 
TABLE 1 
__________________________________________________________________________ 
Example Comparative Example 
1 2 3 1 2 3 4 
__________________________________________________________________________ 
Component (A) 
Symbol (A-I) (A-I) (A-II) (A-I) (A-III) 
(A-II) (A-II) 
Amount 100 100 100 91.2 100 87.5 87.5 
Component (B) 
Symbol (B-1) (B-2) (B-3) (B-4) (B-5) (B-6) (B-6) 
Amount 25 25 25 33.8 25 37.5 37.5 
Neutralizing agent 
Compound name 
Acetic acid 
Formic acid 
Formic acid 
Formic acid 
Formic acid 
Formic acid 
Formic acid 
Amount 1.6 1.2 1.2 1.2 1.2 1.2 1.2 
Deionized Water 
Amount 204 207 207 207 207 207 201 
Catalyst 
Compound name 
Pb Zn Pb Pb Pb Pb Pb 
Amount 2.6 2.6 2.6 2.6 2.6 2.6 2.6 
Compound name DBTL 
Amount 5.6 
__________________________________________________________________________ 
Notes 
Pb refers to lead octenoate (Pb content = 38%) 
Zn refers to zinc octenoate (Zn content = 18%) 
DBTL refers to dibutyltin dilaurate 
(Sn content = 18%) 
TABLE 2 
______________________________________ 
Examples Comparative Example 
1 2 3 1 2 3 4 
______________________________________ 
Low-temperature 
90 92 93 77 93 77 94 
curability (1) 
Gel fraction 
Bath stability 
MEQ (2) 
Initial 27.3 27.7 27.8 26.5 27.5 27.3 27.5 
After storage 
25.6 24.9 25.5 26.0 8.8 26.4 27.7 
Particle 
diameter (3) 
Initial 0.16 0.13 0.11 0.11 0.30 0.15 0.15 
After storage 
0.15 0.13 0.12 0.14 0.32 0.15 0.15 
Heating loss (4) 
3.2 4.2 3.3 2.8 3.9 12.3 15.2 
Weather 
resistance 
Gloss (5) 90 92 93 92 85 -- 45 
retention 
Corrosion (6) 
.smallcircle. 
.smallcircle. 
.smallcircle. 
x .smallcircle. 
x .smallcircle. 
resistance 
Orgaustin Not Not Not Not Not Not pres- 
pres- pres- pres- pres- 
pres- 
pres- 
ent 
ent ent ent ent ent ent 
______________________________________ 
Test Methods 
(1) Low-temperature curability 
An electrocoating was coated on a zinc phosphate-treated steel plate (cured 
film thickness=20.mu.). Then, baking was made at 160.degree. C. for 10 
minutes. The coated plated was immersed in acetone of 30.degree. C. for 48 
hours. A reduction (%) of film weight before and after acetone immersion 
was calculated according to the following formula. 
##EQU1## 
(2) MEQ 
An emulsion having a solid content of 30%, produced in accordance with the 
compounding recipe of Table 1 was accurately weighed in an amount of about 
10 g. Potentiometric titration was conducted for the emulsion using a 
1/10N alcoholic KOH solution to determine the acid amount contained 
therein. Then, MEQ was calculated using the following formula. A case in 
which the difference of MEQ after storage from initial MEQ is smaller, is 
better. 
EQU MEQ=[(amount (ml) of 1/10N KOH solution used.times.10)]/[sample amount (g)] 
(3) Particle diameter 
Was measured using Nanosizer N-4 (trade name) manufactured by Coulter 
Electronics Inc. 
(4) Heating loss 
An electrocoating was coated on a zinc phosphate-treated steel plate 
(weight=Wo) by electrocoating under the above-mentioned conditions, so as 
to give a cured coating film of 20.mu.. The coated plate was dried in a 
vacuum dryer at 80.degree. C. for 1 hour (the weight of the coated plate 
after drying=W1). Then, baking was conducted at 180.degree. C. for 30 
minutes (the weight of the coated plate after baking=W2). The heating loss 
of the electrocoating sample was calculated using the following formula. 
EQU Heating loss (%)=[(W1-W2)/(W1-Wo)].times.100 
(5) Gloss retention 
Electrocoating was made as above (cured film thickness=20.mu.). Then, 
baking was conducted at 170.degree. C. for 20 minutes. The resulting 
coated plate was subjected to accelerated exposure for 200 hours in a 
sunshine weatherometer (light amount=1,100 Kjoule/m.sup.2.hr). Change (%) 
of gloss (60.degree. mirror reflectivity) before and after exposure was 
calculated using the following formula. Gloss measurement was made using a 
digital gloss meter (Model GM-26D, a product of Murakami Colour Research 
Laboratory). 
##EQU2## 
(6) Corrosion resistance 
Electrocoating was made as above (cured film thickness=20.mu.). Then, 
baking was conducted at 160.degree. C. for 10 minutes. The resulting 
coated plate was subjected to a salt spray test by JIS Z 2371. (Before the 
test, cut was made in the coated plate. ) After the test, the width (one 
side width) of blister developed from the cut line was measured. When the 
width was 2.0 mm or less, the corrosion resistance of the electrocoating 
sample used was rated as .largecircle.; and when the width was 5 mm or 
more, the corrosion resistance was rated as X. Incidentally, the test 
period was 1,000 hours.