Water dispersible acrylic based graft copolymers, a method of manufacture and aqueous paints

Provided are aqueous paints with which paint films which have excellent paint film properties such as water resistance and resistance to chemical attack, and excellent finished appearance are obtained, and which have excellent painting operability and storage stability. The invention further provides water dispersible acrylic based graft copolymers, aqueous paints incorporating same and a method to make such paints, wherein an unsaturated bond-containing acrylic based copolymer (a) obtained by reacting an acrylic based copolymer (a1) of acid value 35-120 mg.KOH/gram, hydroxy group value 50-150 mg.KOH/gram, glass transition temperature -20.degree.-+50.degree. C. and number average molecular weight 4500-9000 and an unsaturated monomer mixture (a2), which has functional groups which can react with hydroxy groups, in a mol ratio of a2/a1=0.4-1.5, and a monomer composition (b) compounded in such a way that the acid value is not more than 15 and the hydroxy group value is 50-150 are reacted in the proportions by weight of a/b=10/90-60/40 to produce the claimed water dispersible acrylic based graft copolymer.

FIELD OF THE INVENTION 
The invention concerns novel water dispersible acrylic based graft 
copolymers which are useful as the paint film-forming components of 
aqueous paints, having main chains which form a stabilized layer and side 
chains which form a diffused layer, a method for their manufacture, and 
aqueous paints which contain the aforementioned water dispersible acrylic 
based graft copolymers. 
BACKGROUND OF THE INVENTION 
Aqueous paints are excellent in terms of environmental protection and 
worker safety and so they are taking over from the solvent type paints. 
For example, a change from the solvent type metallic paints in which large 
amounts of organic solvent are used to aqueous metallic paints in which 
water is used for the solvent is in progress in the field of the metallic 
paints which are used to paint the outer panels of automobiles. 
Random polymers which have carboxyl groups in the amounts required to make 
them compatible with water exist as aqueous resins which can be used 
generally in aqueous paints or aqueous paint compositions, and aqueous 
dispersions in which these polymers are dispersed in an aqueous medium and 
neutralized with a basic substance are being used as aqueous paints. 
However, although the aqueous paints which consist of such an aqueous 
dispersion, for example the aqueous paints comprising an aqueous 
dispersion of acrylic based random polymer, have good pigment dispersion 
properties and paint fluidity and form paint films which have an excellent 
gloss and smoothness and they are suitable for providing a beautiful 
finish, the acrylic based polymers have a high acid value and so the water 
resistance of the paint film is low. Furthermore, the viscosity of an 
aqueous dispersion is high and so, when the aqueous paints obtained from 
them are adjusted to a viscosity which is suitable for painting, the solid 
fraction concentration becomes very low, and defects such as runs, holes 
and unevenness, for example, are liable to arise in the paint film during 
painting and during drying. 
Aqueous paint compositions which contain acrylic based graft copolymers 
comprising hydrophilic components and hydrophobic components have been 
proposed for providing some improvement in these respects. For example, 
the manufacture of an acrylic based graft copolymer of acid value 15-40 
and glass transition temperature -10.degree. C.-70.degree. C. by 
polymerizing an unsaturated group-containing acrylic based polymer of acid 
value 40-200, obtained by reacting a glycidyl group-containing unsaturated 
monomer with a carboxy functional acrylic based polymer, and a monomer 
composition in which .alpha.,.beta.-ethylenic unsaturated carboxylic acid 
and other copolymerizable unsaturated monomers have been compounded in 
such a way that the acid value is not more than 30, the difference in the 
acid values of the two reaction components being 25-200, and aqueous paint 
compositions which contain aqueous dispersions of the acrylic based graft 
copolymers obtained as resin components, have been disclosed in Japanese 
Patent Kokai 56-49760. 
Glycidyl group-containing unsaturated monomers are first reacted with a 
carboxy functional acrylic based copolymer in the method for the 
manufacture of the abovementioned acrylic based graft copolymers and the 
glycidyl groups undergo ring-opening addition with the carboxyl groups, 
and then the monomer composition is graft polymerized. However, in this 
method, the glycidyl groups only react specifically with carboxyl groups 
and so graft copolymers cannot be obtained from acrylic based copolymers 
which do not contain carboxyl groups, and so aqueous paints cannot be 
obtained. Furthermore, improvement in the painting operability is 
desirable with the aqueous paints which contain the abovementioned acrylic 
based graft copolymers. 
SUMMARY OF THE INVENTION 
The aim of this present invention is to provide novel and useful water 
dispersible acrylic based graft copolymers, which can be used as paint 
film-forming resins (principal resins) in aqueous paints, with which 
aqueous paints which can form films which have excellent paint film 
performance in terms of water resistance and resistance to chemical 
attack, for example, at this time and which have an excellent finished 
appearance, and which are excellent in terms of painting operability and 
storage stability, can be obtained. 
A second aim of the invention is to provide a method of manufacture with 
which the abovementioned acrylic based graft copolymers can be 
manufactured efficiently and easily using acrylic based copolymers which 
contain hydroxy groups as starting materials. 
A third aim of the invention is to provide aqueous paints which contain the 
abovementioned acrylic based graft copolymers, with which paint films 
which have excellent paint film performance in terms of water resistance 
and resistance to chemical attack, for example, and which have an 
excellent finished appearance can be formed, and which have excellent 
painting operability and storage stability. 
The present inventions are the water dispersible acrylic based graft 
copolymers, a method for their manufacture and aqueous paints indicated 
below. 
(1) Water dispersible acrylic based graft copolymer, characterized in that 
it is a graft copolymer obtained by reacting (a) an unsaturated 
bond-containing acrylic based copolymer, obtained by reacting an acrylic 
based copolymer (a1), being a copolymer of .alpha.,.beta.-ethylenic 
unsaturated monomers, of acid value 35-120 mg.KOH/gram, hydroxy group 
value 50-150 mg.KOH/gram, glass transition temperature 
-20.degree.-+50.degree. C. and number average molecular weight 4500-9000, 
and an .alpha.,.beta.-ethylenic unsaturated monomer (a2), which has 
functional groups which can react with hydroxy groups, in the proportions 
(a2)/(a1) (mol ratio)=0.4-1.5, and (b) a monomer composition in which 
copolymerizable unsaturated monomers have been compounded in such a way 
that the acid value is not more than 15 mg.KOH/gram and the hydroxy group 
value is 50-150 mg.KOH/gram, in the proportions (a)/(b) (ratio by 
weight)=10/90-60/40, having an acid value of 10-30 mg.KOH/gram, a hydroxy 
group value of 50-150 mg.KOH/gram, a glass transition temperature of 
-20.degree.-+50.degree. C. and a number average molecular weight of 
10000-100000. 
(2) Method for the manufacture of a water dispersible acrylic based graft 
copolymer, characterized in that (a) an unsaturated bond-containing 
acrylic based copolymer obtained by reacting an acrylic based copolymer 
(a1), being a copolymer of .alpha.,.beta.-ethylenic unsaturated monomers, 
of acid value 35-120 mg.KOH/gram, hydroxy group value 50-150 mg.KOH/gram, 
glass transition temperature -20.degree.-+50.degree. C. and number average 
molecular weight 4500-9000, and an .alpha.,.beta.-ethylenic unsaturated 
monomer (a2), which has functional groups which can react with hydroxy 
groups, in the proportions (a2)/(a1) (mol ratio)=0.4-1.5, and (b) a 
monomer composition in which copolymerizable unsaturated monomers have 
been compounded in such a way that the acid value is not more than 15 
mg.KOH/gram and the hydroxy group value is 50-150 mg.KOH/gram, are reacted 
in the proportions (a)/(b) (ratio by weight)=10/90-60/40 to manufacture a 
water dispersible acrylic based graft copolymer which has an acid value of 
10-30 mg.KOH/gram, a hydroxy group value of 50-150 mg.KOH/gram, a glass 
transition temperature of -20.degree.-+50.degree. C. and a number average 
molecular weight of 10000-100000. 
(3) Aqueous paint, characterized in that it contains the acrylic based 
graft copolymer disclosed in (1) above. 
DETAILED DESCRIPTION OF THE INVENTION 
The water dispersible acrylic based graft copolymers of this invention 
(referred to hereinafter simply as acrylic based graft copolymers) are 
graft copolymers wherein a hydrophilic unsaturated bond-containing acrylic 
based copolymer (a) which is hydrated when dispersed in an aqueous medium 
and forms a stabilized layer forms the main chains, and a monomer 
component (b) is polymerized on this main chain and hydrophobic side 
chains which form a dispersed layer when dispersed are graft copolymerized 
via bonds such as urethane bonds for example. 
In this invention, the terms "(meth)acrylic acid" and "(meth)acrylate" 
signify "acrylic acid and/or methacrylic acid" and "acrylate and/or 
methacrylate" respectively. 
The acrylic based copolymer (a1) from which the unsaturated bond-containing 
acrylic based copolymer (a) is formed will be described first of all. The 
acrylic based copolymer (a1) is manufactured using hydroxy 
group-containing .alpha.,.beta.-ethylenic unsaturated monomers and 
carboxyl group-containing .alpha.,.beta.-ethylenic unsaturated monomers as 
essential components, with other copolymerizable unsaturated monomers 
which can be used, as required, along with these .alpha.,.beta.-ethylenic 
unsaturated monomers, by means of the known solution polymerization method 
in the presence of a suitable polymerization initiator. Toluene, methyl 
isobutyl ketone, ethylene glycol monobutyl ether (butyl cellosolve), 
propylene glycol monopropyl ether or propylene glycol monoethyl ether, for 
example, can be used as the reaction medium. 
Hydroxyalkyl esters of (meth)acrylic acid, such as 2-hydroxyethyl 
(meth)acrylate, 2-hydroxypropyl (meth)acrylate and 3-hydroxypropyl 
(meth)acrylate; the monoethers with polyether polyols such as 
polypropylene glycol of hydroxy group-containing .alpha.,.beta.-ethylenic 
unsaturated monomers such as 2-hydroxyethyl (meth)acrylate; and lactone 
modified .alpha.,.beta.-ethylenic unsaturated monomers in which 1-10 mol 
of a lactone such as .epsilon.-caprolactone or .gamma.-butyrolactone has 
been added to the hydroxyalkyl ester of (meth)acrylic acid, can be cited 
as examples of the hydroxy group-containing .alpha.,.beta.-ethylenic 
unsaturated monomer. These may be used individually, or they may be used 
in combinations of two or more types. 
Esters: for example the C.sub.1 -C.sub.18 alkyl esters of (meth)acrylic 
acid, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl 
(meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, hexyl 
(meth)acrylate, octyl (meth)acrylate, and lauryl (meth)acrylate; the 
alkoxyalkyl esters of (meth)acrylic acid, such as methoxybutyl 
(meth)acrylate, methoxyethyl (meth)acrylate and ethoxybutyl 
(meth)acrylate; and the amides of acrylic acid or methacrylic acid: for 
example the amides of (meth)acrylic acid such as 
N-methylol(meth)acrylamide and N-isobutoxymethylol(meth)acrylamide; and 
vinyl aromatic compounds such as styrene, .alpha.-methylstyrene and 
vinyltoluene, for example, can be cited as other copolymerizable 
unsaturated monomers which can be used, as required. 
The acrylic based copolymer (a1) is obtained using the monomers by carrying 
out solution polymerization in the usual way in the presence of a known 
polymerization initiator, such as azobisisobutyronitrile, benzyl peroxide, 
t-butyl peroxybenzoate, t-butyl peroxide, t-butyl peroxy-2-ethylhexanoate, 
for example. This reaction is carried out in such a way that the acrylic 
based copolymer (a1) which is formed has an acid value of 35-120 
mg.KOH/gram, and preferably of 60-120 mg.KOH/gram, a hydroxy group value 
of 50-150 mg.KOH/gram, and preferably of 60-120 mg.KOH/gram, a glass 
transition temperature of -20.degree.-+50.degree. C., and preferably of 
-20.degree.-+25.degree. C., and a number average molecular weight of 
4500-9000, and preferably of 4800-8500. 
In cases where the acid value of the acrylic based copolymer (a1) is less 
than 35 mg.KOH/gram the copolymer is inadequate as a stabilizing layer, 
and the acrylic based graft copolymers obtained readily coagulate in an 
aqueous medium and the storage stability is poor, while in cases were it 
exceeds 120 mg.KOH/gram the copolymer is highly hydrophilic and the water 
resistance of a paint film which has been formed with an aqueous paint 
which contains the acrylic based graft copolymer obtained is poor. 
In cases where the hydroxy group value of the acrylic based copolymer (a1) 
is less than 50 mg.KOH/gram there are too few crosslinking points between 
the acrylic based graft copolymer which is obtained and the amino resin 
which is used as a hardener and so the resistance to chemical attack of 
the paint film which is obtained is poor, while in cases where it exceeds 
150 mg.KOH/gram it imparts a hydrophilic nature to the acrylic based graft 
copolymer which is obtained and the water resistance of a paint film which 
has been formed from an aqueous paint containing this graft copolymer is 
poor. 
In cases where the glass transition temperature of the acrylic based 
copolymer (a1) is less than -20.degree. C. the acrylic based graft 
copolymer obtained fuses easily in an aqueous medium and the storage 
stability of the aqueous dispersion is poor, while in those cases where it 
exceeds +50.degree. C. the softening temperature of the acrylic based 
graft copolymer obtained is high and so the smoothness is poor when an 
aqueous paint in which it is included is formed into a paint film. 
In cases where the number average molecular weight of the acrylic based 
copolymer (a1) is less than 4500 it is impossible to form a satisfactory 
stabilized layer and the storage stability of an aqueous dispersion of the 
acrylic based graft copolymer obtained is poor, while in cases where it 
exceeds 9000 the viscosity of an aqueous dispersion of the acrylic based 
graft copolymer obtained is high and the paint solid fraction of an 
aqueous paint which has been prepared with this is low, and the run 
properties are poor. 
The unsaturated bond-containing acrylic based copolymer (a) is obtained by 
reacting an .alpha.,.beta.-ethylenic unsaturated monomer (a2) which has 
functional groups which can react with hydroxy groups with the 
above-mentioned acrylic based copolymer (a1). 
.alpha.,.alpha.-Dimethylisopropenylbenzylisocyanate and 
methacryloylisocyanate, for example, can be cited as actual examples of 
the component (a2). 
The reaction of (a1) and (a2) is carried out under conditions such that the 
mol ratio of (a2)/(a1) is 0.4-1.5, and preferably 0.8-1.2. Moreover, the 
number of mol of the acrylic based copolymer (a1) is determined by 
calculation from the number average molecular weight calculated as 
polystyrene measured in the usual way by means of gel permeation 
chromatography. 
In cases where the amount of (a2) compounded with respect to the acrylic 
based copolymer (a1), as a mol ratio, is less than 0.4, the grafting 
reaction with the (b) component is inadequate and it is difficult to 
disperse the acrylic based graft copolymer which is obtained in an aqueous 
medium, or the storage stability of the aqueous dispersion which is 
obtained is poor, while gelling occurs in cases where it exceeds 1.5 and 
it is impossible to produce an acrylic based graft copolymer. 
The reaction of (a1) and (a2) is preferably carried out in the presence of 
a catalyst such as dibutyltin diacetate, dibutyltin dilaurate or 
dibutyltin diacetonate for example. 
The reaction of (a1) and (a2) can be carried out by reacting an acrylic 
based copolymer (a1), which has been manufactured separately, and the 
component (a2) in an appropriate reaction medium, or the component (a2) 
may be added to the reaction liquid in which the acrylic based copolymer 
(a1) has been manufactured and the reaction can be carried out following 
the manufacture of (a1). The same reaction media as used for the 
manufacture of (a1) can be used for the reaction medium. 
The total concentration of the component (a1) and the component (a2) in the 
reaction liquid is 30-90 percent by weight, and preferably 50-80 percent 
by weight, and the concentration of catalyst in the reaction liquid is 
0.1-5 percent by weight, and preferably 0.1-2 percent by weight. The 
reaction temperature is 20.degree.-160.degree. C., and preferably 
40.degree.-140.degree. C., and the reaction time is preferably 0.5-5 
hours. 
In the abovementioned reaction, the hydroxy groups of the acrylic based 
copolymer (a1) and the functional groups which react with the hydroxy 
groups, for example the isocyanate groups, of the component (a2) react and 
form urethane bonds, the component (a2) is added on to the acrylic based 
copolymer (a1) as a result, and the unsaturated bond-containing acrylic 
based copolymer (a) is produced. 
The monomer composition (b) which is reacted with the unsaturated 
bond-containing acrylic based copolymer (a) which has been obtained in 
this way is a composition in which copolymerizable unsaturated monomers 
have been compounded in such a way that the acid value is not more than 15 
mg.KOH/gram, and preferably not more than 10 mg.KOH/gram, and the hydroxy 
group value is 50-150 mg.KOH/gram, and preferably 60-120 mg.KOH/gram. 
The hydroxy groups containing .alpha.,.beta.-ethylenic unsaturated 
monomers, carboxyl group-containing .alpha.,.beta.-ethylenic unsaturated 
monomers and other copolymerizable monomers, for example, indicated as 
examples for the aforementioned acrylic based copolymer (a1), can be cited 
as copolymerizable unsaturated monomers. 
In cases where the acid value of the monomer composition (b) exceeds 15 
mg.KOH/gram, the acrylic based graft copolymer which is obtained becomes 
water soluble and the viscosity is increased, and the painting properties 
of an aqueous paint in which it is included are poor. Furthermore, the 
water resistance is also poor. 
In cases where the hydroxy group value of the monomer composition (b) is 
less than 50 mg.KOH/gram there are insufficient crosslinking points 
between the amino resin which is used as a hardener and the acrylic based 
graft copolymer which is obtained, and so the resistance to chemical 
attack of the paint films obtained is poor, while in cases where it 
exceeds 150 mg.KOH/gram the copolymer is very hydrophilic and the water 
resistance of the paint films obtained is poor. 
An acrylic based graft copolymer of this invention is obtained by reacting 
the aforementioned unsaturated bond-containing acrylic based copolymer (a) 
and the monomer composition (b). This reaction is carried out under 
conditions where the ratio of the unsaturated bond-containing acrylic 
based copolymer (a) and monomer composition (b), (a)/(b), (ratio by 
weight) is 10/90-60/40, and preferably 20/80-40/60. 
In cases where (a)/(b) (ratio by weight) is less than 10/90 a satisfactory 
stabilized layer is not formed and the storage stability of an aqueous 
dispersion of the acrylic based graft copolymer obtained is poor, while in 
cases where it exceeds 60/40 the viscosity of an aqueous dispersion of the 
acrylic based graft copolymer obtained becomes very high and the paint 
solid fraction of an aqueous paint which contains the acrylic based graft 
copolymer is reduced and the run properties are poor. 
The reaction of the unsaturated bond-containing acrylic based copolymer (a) 
and the monomer composition (b) can be carried out by reacting the 
component (a) which has been produced separately with the monomer 
composition (b) using the known methods of solution polymerization in an 
appropriate reaction medium, or the monomer composition (b) may be added 
to the reaction liquid in which the component (a) has been manufactured 
and the reaction may be carried out using the known methods of solution 
polymerization in an appropriate reaction medium following the manufacture 
of the component (a). The same reaction media as used for the manufacture 
of component (a) can be used for the reaction medium. 
The reaction of component (a) and component (b) is preferably carried out 
in the presence of a polymerization initiator. The same polymerization 
initiators cited for the manufacture of the acrylic based copolymer (a1) 
can be used. 
The total concentration of the component (a) and the monomer component (b) 
in the reaction liquid is 30-90 percent by weight, and preferably 50-80 
percent by weight, and the polymerization initiator concentration with 
respect to the total weight of monomer is 0.1-10 percent by weight, and 
preferably 0.5-5 percent by weight. The reaction temperature is 
20.degree.-160.degree. C., and preferably 40.degree.-160.degree. C., and 
the reaction time is preferably 1-10 hours. 
The acid value, hydroxy group value, glass transition temperature and 
number average molecular weight of the acrylic based graft copolymer 
obtained can be adjusted by selecting, for example, the component (a) 
which is used, the type and amount of monomer composition (b) which is 
used, and the reaction conditions such as the reaction temperature, the 
reaction time and the type and amount of polymerization initiator which is 
used. 
The abovementioned reaction involves carrying out a graft copolymerization 
by means of the radical polymerization of the monomer composition (b) on 
the unsaturated bonds in the component (a), and produces an acrylic based 
graft copolymer. 
The acrylic based graft copolymers of this invention are graft copolymers 
which have been manufactured in the way described above, and they are 
water dispersible acrylic based graft copolymers which have an acid value 
of 10-30 mg.KOH/gram, and preferably of 15-30 mg.KOH/gram, a hydroxy group 
value of 50-150 mg.KOH/gram, and preferably of 60-120 mg.KOH/gram, a glass 
transition temperature of -20.degree.-+50.degree. C., and preferably of 
-10.degree.-+25.degree. C., and a number average molecular weight of 
10000-100000, and preferably of 10000-50000. 
In cases where the acid value of the acrylic based graft copolymer is less 
than 10 mg.KOH/gram it is difficult to disperse the copolymer in an 
aqueous medium and the storage stability is poor. Furthermore, in cases 
where it exceeds 30 mg.KOH/gram the viscosity of the aqueous dispersion 
obtained is very high and the paint solid fraction of an aqueous paint in 
which it is included is low, and the run properties are poor, and so the 
appearance of the paint film is poor. Furthermore, the water resistance of 
the paint film is poor. 
In cases where the hydroxy group value of the acrylic based graft copolymer 
is less than 50 mg.KOH/gram there are insufficient crosslinking points 
between the amino resin which is used as a hardener and the acrylic based 
graft copolymer, and so the resistance to chemical attack of the paint 
films obtained is poor, while in cases where it exceeds 150 mg.KOH/gram 
the copolymer is very hydrophilic and the water resistance of the paint 
films obtained is poor. 
In cases where the glass transition temperature of the acrylic based graft 
copolymer is less than -20.degree. C. the acrylic based graft copolymer 
fuses easily in an aqueous medium and the storage stability of the aqueous 
dispersion is poor, while in those cases where it exceeds +50.degree. C. 
the smoothness is poor when an aqueous paint in which the acrylic based 
graft copolymer is included is formed into a paint film. 
In cases where the number average molecular weight of the acrylic based 
graft copolymer is less than 10000 the water resistance and resistance to 
chemical attack of paint films formed from an aqueous paint in which the 
acrylic based graft copolymer is included are poor. Furthermore, in those 
cases where it exceeds 100000 there is a possibility of gelling during the 
manufacture of an aqueous paint and this is undesirable. Furthermore, the 
smoothness of the paint films obtained is poor. 
An aqueous dispersion can be obtained after manufacturing an acrylic based 
graft copolymer of this present invention by removing the solvent, 
neutralization with a basic substance and dispersion in an aqueous 
dispersion medium. The dispersion in an aqueous dispersion medium can be 
achieved using the usual methods, for example it can be carried out by 
neutralizing at least 40% of the carboxyl groups which are present in the 
acrylic based graft copolymer using an amine, such as dimethylethanolamine 
for example. A medium which contains 40-80 percent by weight of water is 
preferred for the aqueous dispersion medium. 
An aqueous dispersion obtained in this way can be used as it is as an 
aqueous paint, or it may be concentrated or diluted, or it may be formed 
into a powder and then redispersed, to make an aqueous paint. The acrylic 
based graft copolymer can be used individually as the paint film-forming 
component of an aqueous paint, but the paint film performance is further 
improved when an aqueous paint (aqueous paint composition) is prepared by 
combining this as the main component with a hardener component, and this 
is preferred. 
The use of amino resins, and especially amino resins of number average 
molecular weight not more than 1000, for the hardener is desirable. 
Examples of such amino resins include Saimeru 301, Saimeru 303, Saimeru 
325 and Saimeru 327 (trade names, manufactured by the Mitsui Sairekku 
Co.), Nikarakku MW-30 and Nikarakku MX-43 (trade names, manufactured by 
the Sanwa Chemical Co.), and Yuuban 120 (trade name, manufactured by the 
Mitsui Toatsu Co.). Moreover, the number average molecular weight of the 
amino resin is the number average molecular weight calculated as 
polystyrene measured in the usual way by means of gel permeation 
chromatography. 
Various hydrophilic organic solvents can be added, as required, to an 
aqueous paint of this present invention. Examples of such hydrophilic 
organic solvents include ethylene glycol monoethyl ether, ethylene glycol 
monobutyl ether, diethylene glycol monobutyl ether, ethylene glycol 
monohexyl ether, propylene glycol monomethyl ether, propylene glycol 
monoethyl ether and propylene glycol monobutyl ether. 
Furthermore, metallic pigments, inorganic pigments and organic pigments, 
for example, can be added, as required. No particular limitation is 
imposed upon the method by which the pigment is added, and the addition 
can be made using the methods known in the past. Moreover, additives which 
have been added to aqueous paints conventionally, such as acid catalysts 
and surface levelling agents for example, can be compounded as required. 
An aqueous paint of this present invention has very good storage stability 
and excellent painting operability, and the paint films obtained therefrom 
have excellent paint film performance in terms of water resistance, 
resistance to chemical attack, durability and smoothness. 
The aqueous paints of this invention can be used as base coats and they can 
be formulated in the same way as the usual aqueous base coats in this 
case, and they can be used ideally in the two-coat one-bake painting 
systems as known in the past where the base coat and the top coat are 
painted on using a wet-on-wet system and both are baked at the same time. 
Any method of painting, such as with a roll coater, brush painting or spray 
painting for example, can be used. The baking can be carried out for 10-60 
minutes at 60.degree.-180.degree. C., and preferably for 15-30 minutes at 
110.degree.-150.degree. C. 
In this present invention, the effects described can be obtained when the 
various numerical values described so far, for example the property values 
of the acrylic based copolymer (a1) and the monomer composition (b), the 
reaction proportions, the reaction conditions, and the physical property 
values of the acrylic based graft copolymer, are within the numerical 
value ranges which have been disclosed, and especially good results can be 
obtained when all of the numerical values are within the numerical value 
ranges which have been disclosed as preferred ranges. 
The water dispersible acrylic based graft copolymers of this invention are 
novel, and they are useful as paint film-forming resins in aqueous paints. 
The acrylic based graft copolymers of this invention are constructed with 
main chains which form a stabilized layer and side chains which form a 
dispersed layer and so they have excellent water dispersibility, and so 
when such acrylic based graft copolymers are used as paint film-forming 
resins in an aqueous paint the aqueous paint which is obtained does not 
coagulate and has excellent storage stability. Furthermore, an acrylic 
based graft copolymer of this invention is obtained by reacting in 
specified proportions the specified unsaturated bond-containing acrylic 
based copolymer (a) and the monomer composition (b), and it has specified 
physical property values, and so when such an acrylic based graft 
copolymer is used as a paint film-forming resin in an aqueous paint, the 
aqueous paint obtained has excellent painting operability and the paint 
films formed therefrom have excellent paint film performance, such as 
water resistance and resistance to chemical attack for example, and an 
excellent finished appearance. 
The method of manufacture of the water dispersible acrylic based graft 
copolymers of this invention involves reacting in specified proportions 
the specified unsaturated bond-containing acrylic based copolymer (a) and 
the monomer composition (b), and so the abovementioned acrylic based graft 
copolymer can be manufactured easily and with good efficiency from an 
acrylic based copolymer (a) which contains hydroxy groups. 
An aqueous paint of this invention contains the abovementioned acrylic 
based graft copolymer as a paint film-forming agent and so the painting 
operability and storage stability are excellent, and the paint films which 
are formed have excellent paint film performance in terms of water 
resistance and resistance to chemical attack, for example, and an 
excellent finished appearance.

ILLUSTRATIVE EXAMPLES 
The invention is described in more detail below by means of illustrative 
examples, but the invention is not limited in any way by these examples. 
In the examples, the term "parts" signifies "parts by weight" unless there 
is an indication to the contrary. The method of painting and the methods 
of assessing paint film appearance, paint film performance and storage 
stability in each example were as indicated below. 
METHOD OF PAINTING 
Sheets as indicated below were used as test sheets for painting. Thus, 
cationic electrodeposition paint (trade name Akua No.4200, manufactured by 
the Nippon Yushi Co.) was electrodeposition painted so as to provide a dry 
film thickness of 20 m on a zinc phosphate treated steel sheet and baked 
for 20 minutes at a temperature of 185.degree. C., and then a mid-coat 
paint (trade name Haiepico No.100 CP Sealer, manufactured by the Nippon 
Yushi Co.) was air spray coated so as to provide a dry film thickness of 
40 m and baked for 20 minutes at 140.degree. C. to form the test sheet. 
The known two-coat one-bake system was used for painting the aqueous paint 
compositions prepared in each example onto the test sheets. That is to 
say, the aqueous paint composition was spray painted to provide a dry film 
thickness of about 15 m in a painting environment of temperature 
25.degree. C., relative humidity 75% and then it was hot dried for 10 
minutes at 80.degree. C., after which it was cooled to room temperature 
and a commercial top-coat clear paint (trade name Berukooto No. 6000, 
manufactured by the Nippon Yushi Co.) was spray painted so as to provide a 
dry film thickness of about 40 .mu.m and, after setting for 10 minutes, 
the sheet was baked for 30 minutes at 140.degree. C. The sheets for 
painting were maintained vertically throughout the whole process. 
PAINT FILM APPEARANCE 
1) 60.degree. Gloss 
Measured in accordance with JIS K 5400 (1990) 7.6: Mirror Surface Gloss. 
2) Smoothness 
The paint film was observed visually and assessed in accordance with the 
following standard levels. 
O: Good 
x: Poor 
3) Run Properties 
A hole of diameter 10 mm was opened up in the sheet for painting and an 
assessment was made on the basis of the standard levels indicated below 
from the length of the run below the hole on painting so as to provide a 
dry film thickness of 30 m. 
O: Less than 2 mm 
x: More than 2 mm 
PAINT FILM PERFORMANCE 
1) Water Resistance 
The state of the paint surface after being immersed in hot water at a 
temperature of 90.degree. C. or above for 4 hours was observed visually 
and an assessment was made on the basis of the following standard levels. 
O: No change 
x: Shrinkage occurred 
2) Resistance to Chemical Attack 
The state of the paint surface after being immersed in regular gasoline at 
a temperature of 40.degree. C. for 1 hour was observed visually and an 
assessment was made on the basis of the following standard levels. 
O: No change 
x: Shrinkage occurred 
STORAGE STABILITY 
This was assessed by means of the fractional change (%) in the viscosity, 
with respect to the initial viscosity (ps/6 rpm (type B viscometer)) on 
storing the aqueous paint composition for 20 days at 40.degree. C., and 
the assessment was made on the basis of the following standard levels. 
O: Less than.+-.15% 
x: More than.+-.15% 
EXAMPLES 1-5 
1) Preparation of Acrylic Based Graft Copolymers 
Toluene (116.4 parts) was introduced into a reaction vessel which had been 
furnished with a stirrer, a temperature controller, a condenser and 
drip-feed apparatus; the temperature was raised, with stirring, and the 
toluene was refluxed. Next, a mixture of 41.8 parts 2-hydroxyethyl 
methacrylate, 18.5 parts acrylic acid, 64.3 parts n-butyl acrylate, 55.4 
parts n-butyl methacrylate and 3.6 parts of azobisisobutyronitrile was 
added dropwise over a period of 2 hours. The mixture was then stirred 
under reflux for a further 2 hours and the polymerization was completed. 
(This reaction process is referred to hereinafter as "Process 1") 
The resin obtained was an acrylic based copolymer of acid value 80 
mg.KOH/gram, hydroxy group value 10 100 mg.KOH/gram, glass transition 
temperature 0.degree. C. and number average molecular weight 4900. 
Next, 0.1 part of dibutyltin dilaurate was introduced into this resin 
solution and, after cooling to 80.degree. C., 7.4 parts of 
.alpha.,.alpha.-dimethylisopropenylbenzylisocyanate were introduced, with 
stirring, and the stirring was continued for 1 hour and the reaction was 
completed. (This reaction process is referred to hereinafter as "Process 
2".) 
Next, 266.2 parts of toluene were introduced into this resin solution and 
the mixture was stirred under reflux. Next, a mixture of 97.4 parts 
2-hydroxyethyl methacrylate, 149.2 parts methyl methacrylate, 173.4 parts 
n-butyl acrylate and 6.3 parts azobisisobutyronitrile was added dropwise 
over a period of 2 hours. The polymerization was then completed by 
continuing the stirring for a further 5 hours. (This reaction process is 
referred to hereinafter as "Process 3".) 
The acrylic based graft copolymer A-1 obtained was a resin solution which 
had an acid value of 24 mg.KOH/gram, a hydroxy group value of 96 
mg.KOH/gram, a glass transition temperature of +7.degree. C. and a number 
average molecular weight of 32000. The acrylic based graft copolymers 
A-2-A-5 were manufactured in the same way as described above using the 
formulations shown in Tables 1 to 3. The valves of the physical preperties 
and the like are given in Table 3. 
TABLE 1 
______________________________________ 
Acrylic Based Graft 
(Parts by Weight) 
Copolymer No. 
A - 1 A - 2 A - 3 A - 4 A - 5 
______________________________________ 
Process 1 
Solvent 
Toluene 116.4 155.2 97.7 77.0 -- 
Methyl isobutyl ketone 
-- -- -- -- 77.6 
Monomer Composition 
2-Hydroxyethyl 
41.8 33.4 41.8 22.3 22.3 
methacrylate 
Acrylic acid 18.5 21.6 15.4 12.3 18.5 
n-Butyl acrylate 
64.3 105.6 78.7 22.8 31.8 
n-Butyl methacrylate 
55.4 79.4 -- 50.6 47.4 
2-Ethylhexyl methacry- 
-- -- 14.1 -- -- 
late 
Styrene -- -- -- 12.0 -- 
Initiator 
Azobisisobutyronitrile 
3.6 4.8 -- -- 2.4 
t-BPOEH *1 -- -- -- 3.0 -- 
t-Butyl peroxybenzoate 
-- -- 2.3 -- -- 
Reaction Temperature 
Reflux Reflux Reflux 
Reflux 
Reflux 
Process 2 
Monomer 
.alpha.,.alpha.-Dimethyliso- 
7.4 9.9 3.6 4.9 4.7 
propenylbenzyl- 
isocyanate 
Catalyst 
Dibutyltin dilaurate 
0.1 0.2 0.1 0.1 0.1 
Reaction Temperature 
80.degree. C. 
80.degree. C. 
80.degree. C. 
80.degree. C. 
80.degree. C. 
______________________________________ 
*1 tBPOEH: tButylperoxy-2-ethylhexanoate 
TABLE 2 
______________________________________ 
Acrylic Based Graft 
(Parts by Weight) 
Copolymer No. 
A - 1 A - 2 A - 3 A - 4 A - 5 
______________________________________ 
Process 3 
Solvent 
Toluene 266.2 220.9 285.0 305.4 -- 
Methyl isobutyl ketone 
-- -- -- -- 308.0 
Monomer Composition 
2-Hydroxyethyl meth- 
97.4 66.9 125.3 89.1 66.9 
acrylate 
Acrylic acid -- 4.6 -- -- -- 
Methyl methacrylate 
149.2 136.4 113.1 171.1 235.8 
n-Butyl acrylate 
173.4 152.1 211.6 171.8 177.3 
Styrene -- -- -- 48.0 13 
Initiator 
Azobisisobutyronitrile 
6.3 -- -- -- 7.2 
t-BPOEH *1 -- -- -- 9.6 -- 
t-Butyl peroxybenzoate 
-- 9.0 11.3 -- -- 
Reaction Temperature 
Reflux Reflux Reflux 
Reflux 
Reflux 
______________________________________ 
*1 tBPOEH: tButylperoxy-2-ethylhexanoate 
TABLE 3 
__________________________________________________________________________ 
Acrylic Based Graft Copolymer No. 
A - 1 
A - 2 
A - 3 
A - 4 
A - 5 
__________________________________________________________________________ 
Characteristic 
Acid Value (mg.KOH/gram) 
80 70 80 80 120 
Values of the 
Hydroxy Group Value (mg.KOH/gram) 
100 60 120 80 80 
Acrylic Based 
Glass Transition Temperature (.degree.C.) 
0 -10 -15 +20 +10 
Copolymer Obtained 
Number Average Molecular Weight 
4900 
4900 
8500 
4900 
5100 
in Process 1 
Characteristic Values 
Acid Value (mg.KOH/gram) 
0 10 0 0 0 
of the Acrylic Based 
Hydroxy Group Value (mg.KOH/gram) 
100 80 120 80 60 
Copolymer Obtained 
Glass Transition Temperature (.degree.C.) 
+10 +10 0 +20 +20 
in Process 3 
Characteristic Values 
Acid Value (mg.KOH/gram) 
24 28 20 16 24 
of the Acrylic Based 
Hydroxy Group Value (mg.KOH/gram) 
96 67 118 78 62 
Graft Copolymer 
Glass Transition Temperature (.degree.C.) 
+7 +2 -4 +20 +18 
Number Average Molecular Weight 
32000 
27000 
45.000 
38000 
33000 
Component (a)/Component (b) 
30/70 
40/60 
25/75 
20/80 
20/80 
ratio by weight 
Component (a2)/Component (a1) 
1.0 1.0 1.0 1.0 1.0 
mol ratio 
__________________________________________________________________________ 
2) Preparation of Aqueous Dispersions 
Ethylene glycol monobutyl ether (80.0 parts) was added to 533.0 parts of 
the acrylic based graft copolymer A-1 obtained in 1) above and then 207.3 
parts of toluene were distilled off by distillation under reduced 
pressure. Dimethylethanolamine (6.1 parts, 0.5 equivalents with respect to 
the carboxyl groups) was added to this polymer solution and the mixture 
was stirred, and then 588.2 parts of deionized water were added and the 
mixture was stirred until it became homogeneous, and the milk-white low 
viscosity aqueous dispersion B-1 of the acrylic based graft copolymer A-1 
was obtained. 
Furthermore, the aqueous dispersions B-2-B-5 of the acrylic based graft 
copolymers A-2-A-5 were obtained using the same method as described above 
with the formulations shown in Table 4. The properties of the aqueous 
dispersion obtained are shown in Table 4. 
TABLE 4 
__________________________________________________________________________ 
Aqueous Dispersion No. 
B - 1 B - 2 B - 3 B - 4 B - 5 
__________________________________________________________________________ 
Type of Acrylic Based Graft Copolymer Used 
A - 1 A - 2 A - 3 A - 4 A - 5 
Amount of Acrylic Based Graft 
(parts by 
533.0 533.0 533.0 533.0 533.0 
Copolymer Compounded 
weight) 
Ethylene Glycol Monobutyl Ether 
(parts by 
80.0 80.0 80.0 80.0 80.0 
weight) 
Amount of Toluene Distilled Off 
(parts 
207.3 200.5 204.0 203.8 -- 
under Reduced Pressure 
by weight) 
Amount of Methyl Isobutyl Ketone 
(parts by 
-- -- -- -- 205.5 
Distilled Off Under Reduced Pressure 
weight) 
Dimethylethanolamine (parts by weight) 
6.1 7.1 5.1 4.1 6.1 
Deionized Water (parts by weight) 
588.2 580.4 585.9 586.7 586.4 
Properties of the Aqueous Dispersion 
Milk white low 
Milk white low 
Milk white low 
Milk white low 
Milk white low 
Obtained viscosity 
viscosity 
viscosity 
viscosity 
viscosity 
liquid liquid liquid liquid liquid 
__________________________________________________________________________ 
3) Preparation of Aqueous Paint Compositions and Performance Tests 
Aqueous paint compositions were prepared on the basis of the formulation 
shown in Table 5. That is to say, amino resin (trade name Saimeru 327, 
manufactured by the Mitsui Sairakku Co.), titanium dioxide (trade name 
Teika Rutile Type Titanium Dioxide JR602, manufactured by the Teika Co.), 
dimethylethanolamine and deionized water were added to the aqueous 
dispersions B-1-B-5 obtained in 2) above to prepare aqueous paint 
compositions of solid fraction 65 percent by weight. Deionized water was 
added to these aqueous paint compositions to adjust the viscosity measured 
using a B-type viscometer to 3.+-.1 ps as a 6 rpm rotation viscosity and 
then they were evaluated using the methods described earlier. 
The appearance of the paint films obtained and the results of the 
performance tests, and the results of the storage stability tests, are 
shown in Table 6. 
TABLE 5 
__________________________________________________________________________ 
Example No. 1 2 3 4 5 
__________________________________________________________________________ 
Type of Aqueous 
B - 1 328.1 
-- -- -- -- 
Dispersion 
B - 2 -- 328.1 
-- -- -- 
(parts by B - 3 -- -- 328.1 
-- -- 
weight) B - 4 -- -- -- 328.1 
-- 
B - 5 -- -- -- -- 328.1 
Dimethylethanolamine 
(parts by 
2.0 2.3 1.7 1.3 3.7 
weight) 
Saimeru 327 
(parts by 
50.0 50.0 50.0 50.0 50.0 
weight) 
Titanium dioxide 
(parts by 
500.0 
500.0 
500.0 
500.0 
500.0 
weight) 
Ethylene glycol 
(parts by 
50.0 50.0 50.0 50.0 50.0 
monobutyl ether) 
weight) 
Deionized water 
(parts by 
69.9 69.6 70.2 70.6 68.2 
weight) 
Deionized water for 
(parts by 
43.3 74.3 23.6 15.6 38.3 
adjusting the 
weight) 
viscosity 
Total 1043.3 
1074.3 
1023.6 
1015.6 
1038.3 
Solid (weight %) 
62.3 60.5 63.5 64.0 62.6 
fraction 
__________________________________________________________________________ 
TABLE 6 
______________________________________ 
Example No. 1 2 3 4 5 
______________________________________ 
Dry Film 
Thickness 
Base coat (.mu.m) 
15 15 16 15 16 
Clear coat (.mu.m) 
40 41 40 41 41 
Painted 
Appearance 
60.degree. Gloss 
93 94 93 92 94 
Smoothness .largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
Run Properties 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
Paint Film 
Performance 
Water resistance 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
Resistance to 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
chemical attack 
Storage Stability 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
______________________________________ 
COMATIVE EXAMPLES 1-7 
1) Preparation of Acrylic Based Graft Copolymers 
The acrylic based graft copolymers a-1-a-7 were prepared using the same 
method as in 1) of Examples 1-5 using the formulations shown in Tables 7 
and 8. The property values etc. are shown in Table 9. 
TABLE 7 
__________________________________________________________________________ 
Acrylic Based Graft 
(Parts by Weight) 
Copolymer No. 
a - 1 
a - 2 
a - 3 
a - 4 
a - 5 
a - 6 
a - 7 
__________________________________________________________________________ 
Process 1 
Solvent 
Toluene -- 94.0 
116.4 
-- 97.0 
116.4 
-- 
Methyl isobutyl ketone 
116.4 
-- -- 114.6 
-- -- 97.0 
Monomer Composition 
2-Hydroxyethyl 
33.4 
34.8 
16.7 
29.3 
27.9 
75.2 
41.8 
methacrylate 
Acrylic acid 
7.0 19.3 
18.5 
13.9 
28.9 
18.5 
19.3 
n-Butyl acrylate 
53.9 
56.2 
56.4 
123.0 
43.8 
38.6 
-- 
n-Butyl methacrylate 
85.7 
39.7 
88.4 
13.8 
-- -- 47.8 
2-Ethylhexyl methacry- 
-- -- -- -- 49.4 
47.7 
11.1 
late 
Styrene -- -- -- -- -- -- 30.0 
Initiator 
Azobisisobutyronitrile 
3.6 -- -- -- 3.0 3.6 -- 
t-BPOEH *1 -- 6.0 3.6 -- -- -- 3.0 
t-Butyl peroxybenzoate 
-- -- -- 5.4 -- -- -- 
Reaction Temperature 
Reflux 
Reflux 
Reflux 
Reflux 
Reflux 
Reflux 
Reflux 
Process 2 
Monomer 
.alpha.,.alpha.-Dimethyliso- 
7.4 9.2 7.0 7.5 6.0 7.4 5.9 
propenylbenzyl- 
isocyanate 
Catalyst 
Dibutyltin dilaurate 
0.1 0.2 0.1 0.1 0.1 0.1 0.1 
Reaction Temperature 
80.degree. C. 
80.degree. C. 
80.degree. C. 
80.degree. C. 
80.degree. C. 
80.degree. C. 
80.degree. C. 
__________________________________________________________________________ 
*1 tBPOEH: tButylperoxy-2-ethylhexanoate 
TABLE 8 
__________________________________________________________________________ 
Acrylic Based Graft 
(Parts by Weight) 
Copolymer No. 
a - 1 
a - 2 
a - 3 
a - 4 
a - 5 
a - 6 
a - 7 
__________________________________________________________________________ 
Process 3 
Solvent 
Toluene -- 270.3 
264.5 
-- 287.1 
264.1 
-- 
Methyl isobutyl ketone 
266.2 
-- -- 261.9 
-- -- 285.0 
Monomer Composition 
2-Hydroxyethyl 
78.0 
104.4 
39.0 
68.3 
83.6 
175.5 
125.3 
methacrylate 
Acrylic acid 
-- -- -- -- -- -- -- 
Methyl methacrylate 
164.6 
159.9 
246.4 
80.8 
230.9 
138.5 
199.7 
n-Butyl acrylate 
177.4 
185.7 
134.6 
270.9 
135.5 
106.0 
35.0 
Styrene -- -- -- -- -- -- 90.0 
Initiator 
Azobisisobutyronitrile 
6.3 -- -- -- 6.8 8.4 -- 
t-BPOEH *1 -- 20.3 
8.4 -- -- -- 9.0 
t-Butyl peroxybenzoate 
-- -- -- 10.5 
-- -- -- 
Reaction Temperature 
Reflux 
Reflux 
Reflux 
Reflux 
Reflux 
Reflux 
Reflux 
__________________________________________________________________________ 
*1 tBPOEH: tButylperoxy-2-ethylhexanoate 
TABLE 9 
__________________________________________________________________________ 
Acrylic Based Graft Copolymer No. 
a - 1 
a - 2 
a - 3 
a - 4 
a - 5 
a - 6 
a - 7 
__________________________________________________________________________ 
Characteristic 
Acid Value (mg.KOH/gram) 
30 100 
80 60 150 80 100 
Values of the 
Hydroxy Group Value (mg.KOH/gram) 
80 100 
40 70 80 180 120 
Acrylic Based 
Glass Transition Temperature (.degree.C.) 
0 0 0 -30 0 +10 +50 
Copolymer Number Average Molecular Weight 
4900 
3300 
5200 
4800 
5000 
4900 
5100 
Obtained 
in Process 1 
Characteristic 
Acid Value (mg.KOH/gram) 
0 0 0 0 0 0 0 
Values of the 
Hydroxy Group Value (mg.KOH/gram) 
80 100 
40 70 80 180 120 
Monomer Composition 
Glass Transition Temperature (.degree.C.) 
+10 +10 
+30 -20 +30 +30 +70 
Polymerized 
in Process 3 
Characteristic 
Acid Value (mg.KOH/gram) 
9 25 24 18 38 24 25 
Values of the 
Hydroxy Group Value (mg.KOH/gram) 
76 96 37 66 77 176 117 
Acrylic Based 
Glass Transition Temperature (.degree.C.) 
+7 +10 
+24 -23 +22 +24 +65 
Graft Copolymer 
Number Average Molecular Weight 
42000 
9000 
32000 
31000 
37000 
31000 
33000 
Component (a)/Component (b) 
30/70 
25/75 
30/70 
30/70 
25/75 
30/70 
26/75 
ratio by weight 
Component (a2)/Component (a1) 
1.0 1.0 
1.0 1.0 1.0 1.0 1.0 
mol ratio 
__________________________________________________________________________ 
2) Preparation of Aqueous Dispersions 
The aqueous dispersions b-1-b-7 of the acrylic based graft copolymers 
a-1-a-7 were prepared using the same method as in 2) of Examples 1-5 with 
the formulations shown in Table 10, using the acrylic based graft 
copolymers obtained in 1) above. Moreover, 588.6 parts of deionized water 
were added when the acrylic based graft copolymer a-1 was used and the 
mixture was stirred but, since the acid value of the component (a1) was 
too low, a sediment was produced and a stable aqueous dispersion could not 
be obtained (Comparative Example 1). 
TABLE 10 
__________________________________________________________________________ 
Aqueous Dispersion No. 
b - 1 
b - 2 b - 3 b - 4 b - 5 
b - 6 b - 
__________________________________________________________________________ 
7 
Type of Acrylic Based Graft Copolymer Used 
a - 1 
a - 2 a - 3 a - 4 a - 5 
a - 6 a - 7 
Amount of Acrylic Based Graft 
533.0 
533.0 533.0 533.0 533.0 
533.0 533.0 
Copolymer Compounded (parts by weight) 
Ethylene Glycol Monobutyl Ether (parts by weight) 
80.0 80.0 80.0 80.0 80.0 80.0 80.0 
Amount of Toluene Distilled Off under Reduced 
Pressure (parts by weight) 
-- 194.2 203.0 -- 204.7 
202.8 -- 
Amount of Methyl Isobutyl Ketone Distilled Off 
203.9 
-- -- 200.7 -- -- 203.6 
Under Reduced Pressure (parts by weight) 
Dimethylethanolamine (parts by weight) 
2.3 6.3 6.1 4.6 9.6 6.1 6.3 
Deionized Water (parts by weight) 
588.6 
574.9 583.9 583.1 582.1 
583.7 584.3 
Properties of the Aqueous 
Dispersion 
Milk white 
Milk white 
Milk white 
High Milk white 
Milk white 
Dispersion Obtained in water 
low viscosity 
low viscosity 
viscosity 
viscosity 
low viscosity 
low viscosity 
impossible 
liquid 
liquid 
liquid 
liquid 
liquid 
liquid 
__________________________________________________________________________ 
3) Preparation of Aqueous Paint Compositions and Performance Tests 
Aqueous paint compositions were prepared in the same way as in 3) of 
Examples 1-5 on the basis of the formulation shown in Table 11, and they 
were evaluated in the same way as Examples 1-5. The results are shown in 
Table 12. 
TABLE 11 
__________________________________________________________________________ 
Comparative Example No. 
2 3 4 5 6 7 
__________________________________________________________________________ 
Type of b - 2 328.0 
-- -- -- -- -- 
Aqueous b - 3 -- 328.0 
-- -- -- -- 
Dispersion 
b - 4 -- -- 328.0 
-- -- -- 
(parts by b - 5 -- -- -- 328.0 
-- -- 
weight) b - 6 -- -- -- -- 328.0 
-- 
b - 7 -- -- -- -- -- 328.0 
Dimethylethanolamine 
(parts by weight) 
2.1 2.0 1.5 3.2 2.0 2.1 
Saimeru 327 
(parts by weight) 
50.0 
50.0 
50.0 
50.0 
50.0 
50.0 
Titanium dioxide 
(parts by weight) 
500.0 
500.0 
500.0 
500.0 
500.0 
500.0 
Ethylene glycol 
(parts by weight) 
50.0 
50.0 
50.0 
50.0 
50.0 
50.0 
monobutyl ether) 
Deionized water 
(parts by weight) 
69.8 
69.9 
70.4 
68.7 
69.9 
69.8 
Deionized water 
(parts by weight) 
67.3 
55.2 
18.8 
267.1 
56.9 
51.8 
for adjusting 
the viscosity 
Total 1067.3 
1055.2 
1018.8 
1267.1 
1056.9 
1051.8 
Solid (weight %) 
60.9 
61.6 
63.8 
51.3 
61.5 
61.8 
fraction 
__________________________________________________________________________ 
TABLE 12 
______________________________________ 
Comparative Example No. 
2 3 4 5 6 7 
______________________________________ 
Dry Film 
Thickness 
Base coat (.mu.m) 
16 15 15 14 15 15 
Clear coat (.mu.m) 
39 40 39 40 40 41 
Painted 
Appearance 
60.degree. Gloss 
94 92 93 95 93 87 
Smoothness .largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
X 
Run Properties .largecircle. 
.largecircle. 
.largecircle. 
X .largecircle. 
.largecircle. 
Paint Film 
Performance 
Water resistance 
X .largecircle. 
.largecircle. 
.largecircle. 
X .largecircle. 
Resistance to X X .largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
chemical attack 
Storage Stability 
.largecircle. 
.largecircle. 
X .largecircle. 
.largecircle. 
.largecircle. 
______________________________________ 
As is clear from the results shown in Table 12, in Comparative Example 2 
the number average molecular weight of the acrylic based graft copolymer 
was too low and so the water resistance and resistance to chemical attack 
of the paint film obtained were poor. 
In Comparative Example 3 the hydroxy group value of the acrylic based graft 
copolymer was too low and so there were insufficient crosslinking points 
with the amino resin and the resistance to chemical attack of the paint 
film obtained was poor. 
In Comparative Example 4 the glass transition temperature of the acrylic 
based graft copolymer was too low and so the storage stability of the 
aqueous paint composition was poor. 
In Comparative Example 5 the acid value of the acrylic based graft 
copolymer was too high and so the paint solid fraction of the aqueous 
paint composition obtained was reduced and runs formed, and the paint film 
appearance was poor. Furthermore, the water resistance of the paint film 
obtained was also poor. 
In Comparative Example 6 the hydroxy group value of the acrylic based graft 
copolymer was too high and the water resistance of the paint film obtained 
was poor. 
In Comparative Example 7 the glass transition temperature of the acrylic 
based graft copolymer was too high and the smoothness of the paint film 
obtained was poor. 
On the other hand, as shown in Table 6, the aqueous paint compositions of 
Examples 1-5 all provided an excellent finished appearance, excellent 
painting operability and excellent paint film performance and storage 
stability. 
COMATIVE EXAMPLE 8 
Methyl isobutyl ketone (76.4 parts) was introduced into a reaction vessel 
which had been furnished with a stirrer, a temperature controller, a 
condenser and drip feeding apparatus, and the temperature was raised, with 
stirring, and the toluene was refluxed. Next, a mixture of 27.9 parts 
2-hydroxyethyl methacrylate, 12.3 parts acrylic acid, 16.9 parts n-butyl 
acrylate, 62.9 parts n-butyl methacrylate and 3.6 parts t-butyl 
peroxybenzoate was added dropwise over a period of 2 hours. The mixture 
was then stirred under reflux for a further 2 hours and the polymerization 
was completed. The resin obtained was an acrylic based copolymer of acid 
value 80 mg.KOH/gram, hydroxy group value 100 mg.KOH/gram, glass 
transition temperature +20.degree. C. and number average molecular weight 
4900. 
Next, 0.1 part of dibutyltin dilaurate was introduced into this resin 
solution and, after cooling to 80.degree. C., 4.9 parts of 
.alpha.,.alpha.-dimethylisopropenylbenzylisocyanate were introduced, with 
stirring, and the stirring was continued for 1 hour and the reaction was 
completed. 
Next, 310.2 parts of methyl isobutyl ketone were introduced into this resin 
solution and the mixture was stirred under reflux. Next, a mixture of 
111.4 parts 2-hydroxyethyl methacrylate, 228.8 parts methyl methacrylate, 
139.8 parts n-butyl acrylate and 4.8 parts t-butyl peroxybenzoate was 
added dropwise over a period of 2 hours. The acid value of the mixture 
which was drip fed was 0 mg.KOH/g, the hydroxy group value was 100 
mg.KOH/gram, and the ratio by weight of component (a)/component (b) was 
20/80. The mixture was stirred after the drip feed but the design 
molecular weight of the acrylic based graft copolymer was too high and 
gelling occurred, and a graft copolymer was not produced. 
COMATIVE EXAMPLE 9 
Methyl isobutyl ketone (76.4 parts) was introduced into a reaction vessel 
which had been furnished with a stirrer, a temperature controller, a 
condenser and drip feeding apparatus, and the temperature was raised, with 
stirring, and the toluene was refluxed. Next, a mixture of 27.9 parts 
2-hydroxyethyl methacrylate, 12.3 parts acrylic acid, 16.9 parts n-butyl 
acrylate, 62.9 parts n-butyl methacrylate and 3.6 parts t-butyl 
peroxybenzoate was added dropwise over a period of 2 hours. The mixture 
was then stirred under reflux for a further 2 hours and the polymerization 
was completed. The resin obtained was an acrylic based copolymer of acid 
value 80 mg.KOH/gram, hydroxy group value 100 mg.KOH/gram, glass 
transition temperature +20.degree. C. and number average molecular weight 
4900. 
Next, 0.1 part of dibutyltin dilaurate was introduced into this resin 
solution and, after cooling to 80.degree. C., 8.9 parts of 
.alpha.,.alpha.-dimethylisopropenylbenzylisocyanate were introduced, with 
stirring, and the stirring was continued for 1 hour and the reaction was 
completed. 
Next, 299.0 parts of methyl isobutyl ketone were introduced into this resin 
solution and the mixture was stirred under reflux. Next, a mixture of 
111.4 parts 2-hydroxyethyl methacrylate, 228.8 parts methyl methacrylate, 
139.8 parts n-butyl acrylate and 12.0 parts t-butyl peroxybenzoate was 
added dropwise over a period of 2 hours. The acid value of the mixture 
which was drip fed was 0 mg.KOH/g, the hydroxy group value was 100 
mg.KOH/gram, and the ratio by weight of component (a)/component (b) was 
20/80. The mixture was stirred after the drip feed but the mol ratio of 
.alpha.,.alpha.-dimethylisopropenylbenzylisocyanate (a2)/(a1) was over 1.5 
and so gelling occurred, and a graft copolymer was not produced.