Aqueous coating composition

Disclosed is an aqueous coating composition which keeps in high nonvolatile contents during coating operation and is capable of being effectively applied even under a relatively high humidity condition. The coating composition imparts high orientation of metallic pigment particles to the cured film. The aqueous coating composition of the present invention comprises a specific acryl polymer varnish (a) and a specific urethane oligomer dispersion.

FIELD OF THE INVENTION 
The present invention relates to an aqueous coating composition which has 
good application properties and, when cured, had good surface appearance. 
In particularly, it relates to an aqueous metallic coating composition 
which, when coated and cured, has superior orientation of aluminum 
pigment. 
BACKGROUND OF THE INVENTION 
The paint layer of motorcars is generally composed of three layers, i.e. an 
undercoat layer, an intermediate coat layer and an overcoat layer. The 
overcoat layer is formed by coating a metallic base paint containing a 
metallic pigment on an intermediate coated plate and then coating a clear 
paint thereon without baking or curing the metallic base coating (i.e. by 
so-called "wet-on-wet" method), followed by baking or curing the metallic 
base coating and clear coating (i.e. by so-called "two coat one bake" 
method). 
The metallic base paint used in this method can exhibit excellent surface 
appearance in case where flake-like metallic pigment, such as aluminum 
pigment, is uniformly orientated therein. 
Japanese Kokai Publication 58-168664 discloses an aqueous paint which 
contains an aqueous polyurethane dispersant. However, a problem has 
occurred in surface appearance because the metallic pigment is not 
uniformly orientated. 
Japanese Kokai Publication 1-287183 discloses an aqueous metallic base 
paint which contains an acrylic emulsion, a urethane emulsion and a 
cross-linking agent. Since the paint is an aqueous dispersion, 
environmental pollution problems do not come about in comparison with 
solvent type paint, but a problem often occurs in orientation of a 
metallic pigment and a surface appearance is not always satisfactory. 
SUMMARY OF THE INVENTION 
The present inventors already proposed an aqueous metallic coating 
composition using an amide group-containing aqueous acrylic resin (see 
U.S. application Ser. No. 07/509,508 now U.S. Pat. No. 5,039,343. An 
improvement has been made on the proposed coating composition and the 
present invention provides an aqueous coating composition which keeps in 
high nonvolatile contents during coating operation and capable of being 
effectively applied even under a relatively high humidity condition. Of 
course, the coating composition imparts high orientation of metallic 
pigment particles to the cured film. The aqueous coating composition of 
the present invention comprises; 
(a) an aqueous varnish of a film-forming polymer having a number average 
molecular weight of 6,000 to 50,000, prepared by copolymerizing 5 to 40% 
by weight of amide group-containing ethylenic monomers, 3 to 15% by weight 
of acidic group-containing ethylenic monomers, 10 to 40% by weight of 
hydroxyl group-containing ethylenic monomers and the balance of the other 
ethylenic monomers, and a portion of the acid groups is neutralized, 
(b) an aqueous dispersion of a urethane oligomer in an aqueous medium 
containing a primary and/or secondary polyamine, prepared by reacting 
hydroxyl-terminated diol compounds having a molecular weight of 100 to 
5,000, diisocyanate compounds and active-hydrogen containing hydrophilic 
compounds under isocyanate-rich conditions, followed by dispersing the 
reaction product in the aqueous medium; 
the polymer varnish (a) being present in an amount of 95 to 10 wt % (solid) 
and the oligomer dispersion being present in an amount of 5 to 90 wt % 
(solid) in the composition.

DETAILED DESCRIPTION OF THE INVENTION 
The amide group-containing ethylenic monomers used for obtaining said 
film-forming polymer (a) according to the present invention are generally 
(meth)acrylamides. Examples of the (meth)acrylamides are acrylamide, 
methacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, 
N,N-dibutylacrylamide, N,N-dibutylmethacrylamide, N,N-dioctylacrylamide, 
N,M-dioctylmethacrylamide, N-monobutylacrylamide, 
N-monobutylmethacrylamide, N-monooctylacrylamide, 
N-monooctylmethacrylamide and the like. Acrylamide or methacrylamide is 
preferably used. 
The acid groups of the acid group-containing ethylenic monomers include a 
carboxylic group and a sulfonic group. Carboxylic group-containing 
monomers include styrene derivatives (for example, 3-vinylsalicylic acid, 
3-vinylacetylsalicylic acid and the like); and (meth)acrylic acid 
derivatives (for example, acrylic acid, methacrylic acid, crotonic acid, 
isocrotonic acid and the like). In addition, sulfonic group-containing 
ethylenic monomers include p-vinylbenzenesulfonic acid, 
2-acrylamidepropanesulfonic acid and the like. The acid group-containing 
ethylenic monomers may be diesters, such as half esters, half amides and 
half thioesters. The monomers include half esters, half amides and half 
thioesters of maleic acid, fumaric acid and itaconic acid. Alcohols for 
forming the half esters have 1 to 12 carbon atoms and include methanol, 
ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, 
dimethylamino ethanol, diethylamino ethanol, acetol, allyl alcohol, 
propargyl alcohol and the like. Preferred are butanol, dimethylamino 
ethanol, dimethylamino ethanol, acetol, allyl alcohol and propagyl 
alcohol. Mercaptanes for forming half thioesters have 1 to 12 carbon atoms 
and include ethyl mercaptane, propyl mercaptane, butyl mercaptane and the 
like. Amines for forming half amides have 1 to 12 carbon atoms and include 
ethylamine, diethylamine, butylamine, dibutylamine, cyclohexylamine, 
aniline, naphthylamine and the like. Among them, half thioesters have a 
little problem in odor and half esters and half amides are preferably 
used. Reactions, such as half esterification, half thioesterification and 
half amidization, are carried out at temperatures of room temperature to 
120.degree. C. according to the usual methods and with tertiary amines as 
a catalyst under certain circumstances. 
The hydroxylic group-containing ethylenic monomers include 2-hydroxyethyl 
acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 
2-hydroxypropyl methacrylate, 2,4-dihydroxy-4'-vinyl benzophenone, 
N-(2-hydroxyethyl) acrylamide, N-(2-hydroxyethyl) methacrylamide and the 
like. 
The film-forming polymers according to the present invention are obtained 
by copolymerizing the above described monomers with other ethylenic 
monomers by the known methods. The other ethylenic monomers include 
styrene, alpha-methylstyrene, acrylic esters (e.g. methyl acrylate, ethyl 
acrylate, butyl acrylate or 2-ethylhexyl acrylate), methacrylic esters 
(e.g. methyl methacrylate, ethyl methacrylate, butyl methacrylate, 
isobutyl methacrylate and p-butyl methacrylate) and the like. The amide 
group-containing ethylenic monomers used for the preparation of the 
film-forming polymers are used in a quantity of 5 to 40% by weight, 
preferably 8 to 30% by weight. If they are used in a quantity less than 5% 
by weight, a disadvantage occurs in that flake-like metallic pigments have 
poor orientation and thus a surface appearance is poor while if they are 
used in a quantity exceeding 40% by weight, the obtained film has poor 
water resistance. The acid group-containing ethylenic monomers are used in 
a quantity of 3 to 15% by weight, preferably 5 to 13% by weight. If they 
are used in a quantity less than 3% by weight, an aqueous dispersibility 
is deteriorated while if they are used in a quantity exceeding 15% by 
weight, the film is deteriorated in water resistance. The hydroxylic 
group-containing ethylenic monomers are used in a quantity of 10 to 40% by 
weight, preferably 13 to 30% by weight. If they are used in a quantity 
less than 10% by weight, the film is deteriorated in curing ability while 
if they are used in a quantity exceeding 40% by weight, the film is 
deteriorated in water resistance. The obtained polymers have a number 
average molecular weight of 6,000 to 50,000, preferably 8,000 to 30,000. 
If it is less than 6,000, they are insufficient in operating ability and 
curing ability while if it exceeds 50,000, a nonvolatile content during 
coating is excessively reduced and thus a workability is deteriorated. In 
addition, a molecular weight was measured by the GPC method. 
The hydroxyl-terminated diol compounds have a molecular weight of 100 to 
5,000, which are used for the preparation of said aqueous dispersion (b) 
according to the present invention, are typically polyether diols or 
polyester diols. The compounds include polymers or copolymers of alkylene 
oxides (ethylene oxide, propylene oxide, methylene oxide and the like) 
and/or heterocyclic ethers (tetrahydrofuran and the like). Typical 
examples of the compounds are polyethylene glycol, polypropylene glycol, 
polyethylene-propylene glycol, polytetramethylene ether glycol, 
polyhexamethylene ether glycol and polyoctamethylene ether glycol; 
polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, 
polyneopentyl adipate, poly-3-methylpentyl adipate, polyethylene-butylene 
adipate and polyneopentyl-hexyl adipate; polylactone diol, for example 
polycarprolactone diol and poly-3-methylvalerolactone diol; polycarbonate 
diol; and mixtures thereof. Preferred is polycarbonate diol, in view of 
water resistance and adhesive properties of the cured film. 
The diisocyanate compounds used in the present invention include aliphatic 
diisocyanantes, for example hexamethylene diisocyanate, 
2,2,4-trimethylhexane diisocyanate and lysine diisocyanate; alicyclic 
diisocyanates having 4 to 18 carbon atoms, for example 1,4-cyclohexane 
diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5-trimethylcyclohexane 
(isophoron diisocyanate), 4,4'-dicyclohexylmethane diisocyanate, 
methylcyclohexylene diisocyanate and 
isopropylidenecyclohexyl-4,4'-diisocyanate; modified compounds of the 
diisocyanates; and mixtures thereof. Preferred are hexamethylene 
diisocyanate, isophoron diisocyanate. 
The active-hydrogen containing hydrophilic compounds are compounds which 
have at least one active hydrogen (e.g. a hydroxyl group) in a molecule 
and having a hydrophilic group (e.g. a carboxylic group) and includes 
dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutyric acid 
and the like. Preferred are dimethylolpropionic acid. 
In case of the preparation of the hydrophilic group-containing oligomers 
according to the present invention, a reaction is conducted under 
isocyanate-rich conditions, for example at NCO/OH equivalent ratio within 
a range of 1.1 to 1.9. The reaction easily occurs by mixing all compounds. 
The reaction may be conducted in a solvent if necessary. The obtained 
hydrophilic group-containing oligomers are dispersed in an aqueous medium 
which contains the primary and/or secondary polyamine. In this dispersing 
process, the hydrophilic group in the hydrophilic group-containing 
oligomers is neutralized. Examples of the polyamines are (ethylenediamine, 
1,2-propylenediamine, 1,3-propylenediamine, isophoronediamine, 
propane-2,2-cyclohexylamine, N,N-dimethyl-o-phenylenediamine, 
N,N'-dimethyl-o-phenylenediamine, N,N'-di-p-tolyl-m-phenylenediamine, 
p-aminodiphenylamine, hydradine, substituted hydradine (e.g. 
dimethylhydradine and 1,6-hexamethylenebis-hydradine), 
N-beta-aminoethylethanolamine and the like. 
The aqueous coating composition of the present invention can be used for 
any type coating usages, but usually is used for a thermosetting aqueous 
coating composition in combination with a curing agent. The curing agent 
is generally a melamine resin. The melamine resin is preferably a 
water-soluble melamine resin, including Cymel-303 available from Mitsui 
Toatsu Chemicals Inc. and Sumimal N-W available from Sumitomo Chemical Co. 
Ltd. and the like but it is not specially limited by them. Also a 
water-insoluble melamine resin can be used. The melamine resin is used in 
a quantity of 5 to 60% by weight based on the film-forming polymer (a) (as 
measured in solid content). If the melamine resin is used in an excessive 
small quantity, curing ability is insufficient, while, if it is used in an 
excessive large quantity, the cured film is too hard and thus fragile. 
The aqueous coating composition of the present invention may usually 
contain metallic pigments (for example aluminum pigments, bronze pigments, 
mica, gold pigments and silver pigments). The metallic pigments are added 
in a quantity of 2 to 100 parts by weight based on 100 parts by weight 
(solid) of the aqueous coating composition. In addition, various kinds of 
additives (for example an ultraviolet inhibitor, an anti-foamant and a 
surface-regulating agent) and usual inorganic pigments may be added in the 
aqueous coating composition according to the present invention. 
The aqueous metallic coating composition of the present invention is 
remarkably superior in orientation of metal flakes and superior in surface 
appearance of the obtained film. In addition, nonvolatile contents are 
high during coating operation and the aqueous metallic paint is superior 
in also applicability. 
EXAMPLES 
The present invention will be below described in more detail with reference 
to the preferred Examples. However, the present invention is not limited 
by these Examples. 
Production of film-forming polymer (a) 
Production Example 1 
Ethylene glycol monobutyl ether of 76 parts by weight was charged in a 
reaction vessel having a capacity of 1 liter, equipped with with a 
stirrer, a temperature regulator and a condenser, and then 61 parts by 
weight of a monomer solution, which comprised 15 parts by weight of 
styrene, 63 parts by weight of methyl methacrylate, 48 parts by weight of 
2-hydroxydiethyl methacrylate, 117 parts by weight of n-butyl acrylate, 27 
parts by weight of methacrylic acid, 30 parts by weight of acrylamide and 
3 parts by weight of azobisisobutylonitrile, was added thereto and heated 
to 120.degree. C. with stirring. Then, the remaining 245 parts by weight 
of the monomer solution was added for 3 hours and the resulting mixture 
was stirred for 1 hour. Further, 28 parts by weight of 
dimethylethanolamine and 200 parts by weight of deionized water were added 
to the resulting mixture to obtain an acrylic resin varnish having 
nonvolatile content of 50%, and the acrylic resin had a number average 
molecular weight of 12,000. This resin is characterized in that its OH 
value is 70 and its acid value is 58. 
Production Example 2 
A 3 liter reaction vessel, equipped with a nitrogen gas introducing tube, a 
temperature controller, a dropping funnel, a stirrer and a decanter, was 
charged with 500 parts by weight of 2-ethoxy propanol, and heated to 
100.degree. C. A solution of 50 parts by weight of styrene, 50 parts by 
weight of methyl methacrylate, 200 parts by weight of 2-hydroxyethyl 
methacrylate, 120 parts by weight of 2-ethylhexyl methacrylate, 380 parts 
by weight of butyl acrylate, a solution of 100 parts by weight of 
monobutyl maleate and 300 parts by weight of methanol, 100 parts by weight 
of acrylamide and 30 parts by weight of azobisisobutylonitrile was added 
thereto through the dropping funnel. The addition was conducted for 3 
hours with removing methanol with the decanter at 100.degree. C. The 
resulting mixture was stirred for further 30 minutes and then a solution 
comprising 50 parts by weight of butyl acetate and 3 parts by weight of 
t-butylperoxy- 2-ethylhexanoate was added dropwise to it for 0.5 hours. 
Subsequently, the resulting mixture was held at 100.degree. C. for further 
1.5 hours to distill off 300 parts by weight of methanol, followed by 
distilling off 200 parts by weight of the solvent under a reduced 
pressure. Further, 100 g of dimethylethanolamine and 570 g of deionized 
water were added to the resulting solution to obtain a transparent and 
viscous acrylic resin water-solubilized varnish having a nonvolatile 
content of 50% and a number average molecular weight of 10,000. 
Production of urethane-containing aqueous dispersion (b) 
Production Example 3 
Synthesis of hydrophilic group-containing oligomers 
A 5 liter reaction vessel, equipped with a thermometer, a stirrer, a 
condenser and a dropping funnel, was charged with 40.2 parts by weight of 
dimethylolpropionic acid, 30 parts by weight of triethylamine and 312 
parts by weight of N-methylpyrrolidone and heated to 90.degree. C. to be 
dissolved. Then, 290 parts by weight of isophorone diisocyanate and 700 
parts by weight of polypropylene glycol (having a molecular weight of 
1,000) were added to the resulting solution and stirred for 10 minutes, 
followed by adding 1.03 parts by weight of dibutyltin dilaurate. 
Subsequently, the resulting mixture was heated to 95.degree. C. to react 1 
hour. 
Preparation of aqueous dispersion 
A 5 liter reaction vessel, equipped with a thermometer, a stirrer, a 
condenser and a dropping funnel, was charged with 1,750 parts by weight of 
deionized water and 9.2 parts by weight of hydrazine hydrate and then the 
above obtained solution of urethane prepolymer was added with stirring. 
Subsequently, the resulting mixture was stirred for 30 minutes. The 
obtained composition was cloudy and stable aqueous dispersion, and had an 
acid value of 16.2 and a nonvolatile content of 33%. 
Production Example 4 
Synthesis of hydrophilic group-containing oligomers 
The same reaction vessel as Production Example 3 was charged with 40.2 
parts by weight of dimethylolpropionic acid, 30 parts by weight of 
triethylamine and 402 parts by weight of N-methylpyrrolidone and heated to 
90.degree. C. to be dissolved. Then, 290 parts by weight of isophorone 
diisocyanate and 600 parts by weight of polypropylene glycol (having a 
molecular weight of 2,000) were added to the resulting solution and 
stirred for 10 minutes, followed by adding 1.3 parts by weight of 
dibutyltin dilaurate. Subsequently, the resulting mixture was heated to 
95.degree. C. to react 1 hour. 
Preparation of aqueous dispersion 
The same reaction vessel as Production Example 3 was charged with 2,293 
parts by weight of deionized water and 11.5 parts by weight of hydrazine 
hydrate and then the above obtained solution of urethane prepolymer was 
added with stirring. Subsequently, the resulting mixture was stirred for 
30 minutes. The obtained composition was cloudy and stable aqueous 
dispersion, and had an acid value of 12.5 and a nonvolatile content of 
33%. 
Production Example 5 
A hydrophilic oligomer was prepared as generally described in Production 
Example 3, with the exception that polycarbonate diol having a number 
average molecular weight of 1,000 (available from Daicel Chemical Co., 
Ltd. as PLACCEL CD-211PL) was employed instead of polypropylene glycol. An 
aqueous dispersion also was also prepared as generally described in 
Production Example 3 to obtain urethan polymer dispersion having a 
nonvolatile content of 33% and an acid value of 16.0. 
Preparation of clear paint 
Production Example 6 
A clear paint was prepared by mixing the following ingredients in a 
stainless vessel. 
______________________________________ 
Ingredients Parts by weight 
______________________________________ 
Varnish.sup.1 100 
Uban 20 SE-60 36 
Modaflow (available from Monsant Company) 
0.5 
Resin particles.sup.2 2.2 
______________________________________ 
.sup.1 A reaction vessel, equipped with a stirrer, a temperature con- 
troller and a condenser, was charged with 70 parts by weight of 
of xylene and 20 parts by weight of n-butanol. Separately a mono- 
mer solution was prepared from 1.2 parts by weight of meth- 
acrylic acid, 26.4 parts by weight of styrene, 26.4 parts by 
weight of methyl methacrylate, 36.0 parts by weight of n-butyl 
acrylate, 10.0 parts by weight of 2-hydroxyethyl acrylate and 1.0 
part by weight of azobisisobutylonitrile. To the reaction vessel, 
20 parts by weight of the monomer solution was added and heated 
with stirring. The remaining 81.0 parts by weight of the monomer 
solution was added dropwise for 2 hours with refluxing, to which 
a solution of 0.3 parts by weight of azobisisobutylonitrile and 
10 parts by weight of xylene was added dropwise for 30 minutes. 
The resultant solution was further refluxed for 2 hours to obtain 
an acryl varnish having an OH value of 48, a number average 
molecular weight of 8,000 and a nonvolatile content of 50%. 
.sup.2 A one liter reaction vessel, equipped with a stirrer, a 
temperature controller and a condenser, was charged with 282 
parts by weight of deionized water, 10 parts by weight of a 
polyester resin (obtained note 3 hereinafter) and 0.75 parts 
by weight of dimethylethanolamine and mixed at 80.degree. C. to 
dissolve the content. A solution of 45 parts by weight of 
azobiscyanovaleric acid, 45 parts by weight of deionized water 
and 4.3 parts by weight of dimethylethanolamine was added, and 
then a monomer mixture of 70.7 parts by weight of methyl 
methacrylate, 94.2 parts by weight of n-butyl acrylate, 70.7 
parts by weight of styrene, 30 parts by weight of 2-hydroxyethyl 
acrylate and 4.5 parts by weight of ethyleneglycol dimethacrylate 
was added dropwise for 60 minutes. After completion of addition, 
a solution of 1.5 of azobiscyanovaleric acid, 15 parts by weight 
of deionized water and 1.4 parts by weight of dimetehylethanol- 
amine was added and mixed at 80.degree. C. for 60 minutes to 
obtain an emulsion having a particle size of 0.156 micron, a 
nonvolatile content of 45%, pH 7.2 and a viscosity of 92 cps 
(25.degree. C.). The obtained emulsion was spray-dried to remove 
water and redispersed in 200 parts by weight of xylene based on 
100 parts by weight of the resin particles. The obtain dispersion 
had a particle size of 0.3 micron. 
.sup.3 Preparation of polyester resin 
A 2 liter reaction vessel, equipped with a stirrer, a nitrogen 
gas introducing tube, a temperature controller, a condenser and 
a decanter, was charged with 134 parts by weight bishydroxy- 
ethyltaurine, 130 parts by weight of neopentyl glycol, 236 parts 
by weight of azelaic acid, 186 parts by weight of phthalic 
anhydride and 27 parts by weight of xylene, and heated to azeo- 
tropically remove water with xylene. After starting reflux, it was 
slowly heated to 190.degree. C. over about 2 hours and then mixing and 
dehydration continued until an acid value of the carboxylic group 
reached 145. It was then cooled to 140.degree. C. at which 314 parts 
by weight of versatic glycidyl ester (available from Shell 
Chemical Company as Cardure E 10) was added dropwise for 30 
minutes. Thereafter, mixing continued for 2 hours to terminate 
reaction. The obtained polyester resin had 59 acid value, 90 
hydroxyl value and Mn 1,054. 
Production Example 7 
A clear paint was prepared by mixing the following ingredients in a 
stainless vessel. 
______________________________________ 
Ingredients Parts by weight 
______________________________________ 
Varnish.sup.4 100 
Desmodule N-75 16.7 
______________________________________ 
.sup.4 A reaction vessel, equipped with a stirrer, a temperature con- 
troller and a condenser, was charged with 57 parts by weight of 
xylene and 6 parts by weight of n-butanol. Separately a monomer 
solution was prepared from 30.0 parts by weight of styrene, 45.2 
parts by weight of ethylhexyl methacrylate, 5.5 parts by weight 
of ethylhexyl acrylate, 16.2 parts by weight of 2-hydroxyethyl 
methacrylate, 3.1 parts by weight of methacrylic acid and 4.0 
part by weight of azobisisobutylonitrile. To the reaction vessel, 
20 parts by weight of the monomer solution was added and heated 
with stirring. The remaining 84.0 parts by weight of the monomer 
solution was added dropwise for 2 hours with refluxing, to which 
a solution of 0.5 parts by weight of azobisisobutylonitrile, 23 
parts by weight of xylene and 14 parts by weight of n-butanol was 
added dropwise for 20 minutes. The resultant solution was 
further refluxed for 2 hours to obtain an acryl varnish having 
an OH value of 70, a number average molecular weight of 3,400 
and a nonvolatile content of 50%. 
Production Example 8 
A clear paint was prepared by mixing the following ingredients in a 
stainless vessel and diluting with a thinner of butyl acetate/xylene=1/1. 
______________________________________ 
Ingredients Parts by weight 
______________________________________ 
Compound having carboxylic anhydride 
130 
Blocked amine compound.sup.6 
25 
Compound having an alkoxysilyl.sup.7 
65 
Tinubin 900 1.5 
Irukanox 1010 1.0 
______________________________________ 
.sup.5 A one liter reaction vessel, equipped with a stirrer, a 
temperature 
controller and a condenser, was charged with 120 parts by weight 
of butyl acetate and heated to 100.degree. C. Separately a monomer 
solution was prepared from 21 parts by weight of n-butyl acrylate, 
95 parts by weight of n-butyl methacrylate, 34 parts by weight of 
2-ethylhexyl methacrylate, 45 parts by weight of itaconic anhy- 
dride, 60 parts by weight of dioxane and 20 parts by weight of 
t-butylperoxy hexanoate. To the reaction vessel, the monomer 
solution was added dropwise for 3 hours and mixed for another 2 
hours to obtain an acryl resin having carboxylic anhydride groups. 
It had a number average molecular weight of 2,500 and a non- 
volatile content of 51%. 
.sup.6 A reaction vessel, equipped with a stirrer, a condenser with a 
water separator and a thermometer, was charged with 133 g of 
diisopropanolamine and 70 g toluene, to which 76 g of isobutyl 
aldehyde was added dropwise for one hour while it was cooled 
with ice. Water was removed with refluxing for 5 hours and then 
84 g of 1,6-hexane diisocyanate and 20 g of xylene were added 
dropwise for one hour. It was reacted at 70 to 80.degree. C. for 8 
hours to obtain a blocked amine compound. 
.sup.7 Preparation of a compound having alkoxy silyl group 
A one liter reaction vessel, equipped with a stirrer, a temperature 
controller, a condenser and a decanter, was charged with 200 g of 
xylene, and heated to 120.degree. C. Separately, a monomer solution was 
prepared from 150 g of 3-methacryloxypropyltrimethoxysilane, 
20 g of n-butyl acrylate, 30 g of methyl methacrylate and 15 g 
of t-butylperoxy hexanoate. It was added dropwise to the reaction 
vessel over 3 hours, and then reacted for another 2 hours to 
obtain a polymer having an alkoxysilyl group with a number 
average molecular weight of 2,000 and a nonvolatile content 
of 52%. 
Production Example 9 
A clear paint was prepared by mixing the following ingredients in a 
stainless vessel and diluting with a thinner of butyl acetate/xylene=1/1. 
______________________________________ 
Ingredients Parts by weight 
______________________________________ 
Compound having carboxylic anhydride 
130 
Oxazolidine compound.sup.8 
13 
Compound having an alkoxysilyl.sup.7 
65 
3,4-Epoxycyclohexylmethyl- 
7 
3,4-epoxycyclohexane carboxylate 
Tinubin 900 1.5 
Irukanox 1010 1.0 
______________________________________ 
.sup.8 A reaction vessel, equipped with a stirrer, a condenser with a 
water separator and a thermometer, was charged with 200 g of 
benzene and 133 g of diisopropanolamine, to which 75 g of 
isobutyl aldehyde was added dropwise at room temperature for 
one hour. Water was removed with refluxing for 5 hours and 
benzene was removed under reduced pressure to obtain a hydro- 
xyoxazolidine compound. The water separator was detached and 
1,000 g of hexane and 103 g of triethylamine were charged in the 
reaction vessel, to which 64.6 g of dichlorodimethylsilane was 
added dropwise for 2 hours. It was then reacted at room temper- 
ature for 2 hours and white precipitate was filtered away. The 
filtrate was condensed to obtain an oxazolidine compound. 
Production Example 10 
A one liter reaction vessel, equipped with a stirrer, a temperature 
controller and a condenser, was charged with 40 parts by weight of ethoxy 
propanol. To the content, 121.7 parts by weight of a monomer solution, 
which contained 4 parts by weight of sytrene, 35.96 parts by weight of 
n-butyl acrylate, 18.45 parts by weight of ethylhexyl methacrylate, 13.92 
parts by weight of 2-hydroxyethyl methacrylate, 7.67 parts by weight of 
methacrylic acid, 40 parts by weight of a solution of 20 parts by weight 
of ethoxy propanol and 20 parts by weight of acidphosphoxy(oxypropylene) 
monomethacrylate, and 1.7 parts by weight of azobisisobutylonitrile, was 
added dropwise for 3 hours and then mixed for another one hour. The 
resultant acryl resin had an acid value of 105, OH value of 60, a number 
average molecular weight of 6,000 and a nonvolatile content of 63%. 
Preparation of aqueous coating composition 
Example 1 
Fifteen parts by weight of an aluminum pigment paste (65% aluminum content 
available from Toyo Aluminum Co., Ltd. as Alpaste 7160N) was uniformly 
mixed with 30 parts by weight of Cymel 303 (methoxylated methylol melamine 
available from Mitsui Toatsu Chemicals Inc.), with which 2 parts by weight 
of isostearyl acidphosphate (available from Sakai Chemical Co., Ltd. as 
Phophorex A-180L) was mixed to obtain an aluminum pigment solution. 
It is mixed with 112 parts by weight of the film-forming polymer of 
Production Example 1 and then mixed with 43 parts by weight of the 
urethane emulsion of Production Example 3 to obtain an aqueous metallic 
paint. 
Example 2 and 3 
Aqueous metallic paints were obtained from the respective ingredients shown 
in Table 1 in the same manner as in Example 1. 
TABLE 1 
__________________________________________________________________________ 
Example 2 Example 3 Example 4 Example 5 Example 
__________________________________________________________________________ 
6 
Film-forming 
Production Example 2 
Production Example 1 
Production Example 1 
Production Example 
Production Example 2 
polymer (I) 
80 parts by weight 
112 parts by weight 
80 parts by weight 
112 parts by weight 
80 parts by weight 
Urethane 
Production Example 3 
Production Example 4 
Production Example 3 
Production Example 
Production Example 5 
group- 91 parts by weight 
43 parts by weight 
91 parts by weight 
43 parts by weight 
91 parts by weight 
containing 
aqueous 
suspension (II) 
__________________________________________________________________________ 
Examples 4 and 5 
Cymel 303 (methoxy methylol melamine made by Mitsui Toatsu KK) of 30 parts 
by weight was added to an aluminum pigment paste (Alpaste 7160 N 
containing metallic aluminum in a quantity of 65% made by Toyo Aluminum 
KK) of 15 parts by weight and the acrylic varnish obtained according to 
Production Example 10 of 4 parts by weight was added to the resulting 
mixture followed by uniformly mixing the resulting mixture. Subsequently, 
isostearil acid phosphate (Phosrex A-180L made by Sakai Kagaku KK) of 2 
parts by weight was added to the resulting uniform mixture followed by 
uniformly mixing the resulting mixture to obtain an aluminum pigment 
solution. Then, aqueous metallic paints were obtained from the respective 
ingredients shown in Table 1 in the same manner as in Example 1. 
Comparative Example 1 
Production of the Resin for the Aqueous Metallic Paint 
An aqueous metallic paint was produced in the same manner as in Production 
Example 1 excepting that 45 parts by weight of styrene was used and 
acrylic amide was not used. 
Preparation of the Comparative Aqueous Metallic Paint 
An aqueous metallic paint was prepared in the same manner as in Example 1 
excepting that the above described resin was used in place of the 
film-forming polymer produced according to Production Example 1. 
Comparative Example 2 
An aqueous metallic paint was produced by uniformly dispersing the aluminum 
pigment solution in the film-forming polymer obtained according to 
Production Example 1 of 140 parts by weight in the same manner as in 
Example 1. 
Evaluation of coatings 
Tests 1 to 10 
A polished mild steel plate was subjected to a degrease and chemical 
treatment, and then coated with an electrodeposition paint in an 
intermediate coating line to obtain an intermediate coated steel panel. It 
was then coated with the aqueous metallic paint as shown in Table 2, and 
then coated with the clear paint as shown in Table 2. The metallic paint 
was spray-coated at 23.degree. C. and relative humidity of 85% so as to 
obtain a 20 micron layer, and the clear paint was also spray-coated at the 
same condition so as to obtain a 30 micron layer. The metallic paint was 
coated in two stages with one minute interval and then preheated at 
80.degree. C. for 5 minutes. Then, the clear paint was coated in one stage 
and subjected to a setting for 7 minutes. The coated panel was baked at 
140.degree. C. for 30 minutes and subjected to evaluations of adhesive 
properties and water resistance. 
TABLE 2 
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No. 1 2 3 4 5 6 7 8 9 9 10 
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Aqueous metallic paint 
Ex. 1 
Ex. 1 
Ex. 1 
Ex. 1 
Ex. 2 
Ex. 3 
Ex. 4 
Ex. 5 
Ex. 6 
Comp. 
Comp. 
Ex. 1 
Ex. 2 
Clear Pro. 
Pro. 
Pro. 
Pro. 
Pro. 
Pro. 
Pro. 
Pro. 
Pro. 
Pro. 
Pro. 
Ex. 6 
Ex. 7 
Ex. 8 
Ex. 9 
Ex. 8 
Ex. 9 
Ex. 8 
Ex. 9 
Ex. 8 
Ex. 9 
Ex. 9 
Content of nonvolatile 
24% 24% 24% 24% 26% 23% 25% 24% 26% 25% 18% 
ingredients at the 
application of the 
metallic paint 
External appearance 
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X X 
Adherence .largecircle. 
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