Coating composition

A coating composition contains: PA1 (i) a mixture of copolymers comprising (a) 20% to 80% by weight, in terms of the resin solid content, of at least one copolymer selected from the group consisting of silicon-containing copolymers and fluorine-containing copolymers comprising 40 to 60 mol % of fluoroolefin, 45 to 5 mol % of cyclohexylvinyl ether, 15 to 5 mol % of alkylvinyl ether, and 0 to 30 mol % of other comonomers, having an active hydrogen group and (b) 80% to 20% by weight, in terms of the resin solid content, of an acrylic copolymer resin having a solubility parameter greater by 0.5 to 1.5 than that of the copolymer (a) and having an active hydrogen group, and PA1 (ii) a curing agent having a solubility parameter greater by 0.5 to 1.5 than that of the copolymer (a).

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a coating composition, more particularly 
to a coating composition which provides an exterior overcoating having an 
excellent weathering resistance, solvent resistance, and dirt resistance, 
and yet having a good appearance, undercoat adhesiveness, and recoating 
adhesiveness. The present invention also relates to a coating composition 
by which a coating having a deep tone can be formed by ensuring that the 
upper layer of the pigment dispersed system is a clear layer. 
Particularly, it relates to a coating composition which can impart a 
characteristic of the resin coating in a small amount to the resin of the 
clear layer which becomes the upper layer of the pigment dispersed system. 
These coating compositions can be used as final-coat paints for 
automobiles, paints for exteriors of buildings, and paints for metal 
substrates, etc. 
2. Description of the Related Art 
In the final-coating of automobiles, etc., or exterior coating of 
construction materials, etc., coatings having an excellent appearance and 
an excellent weathering resistance, solvent resistance, dirt resistance, 
etc., are required, but although top-coats such as acrylic resin paints, 
alkyl resin paints, polyester resin paints, conventionally used for 
general purpose work have an excellent coating appearance, they have a 
poor weathering resistance, solvent resistance, and dirt resistance, and 
an improvement of these properties is desired. Accordingly, various 
proposals have been made for solving such problems; for example, it has 
been proposed to coat a fluorine type resin on the top-coat, or to use a 
fluorine type resin as the resin for the top-coat. Japanese Unexamined 
Patent Publication (Kokai) No. 57-34107 (Japanese Patent Publication 
(Kokoku) No. 60-21686) discloses a fluorine-containing copolymer curable 
at a normal temperature. According to this publication, by using a 
copolymer containing a specific amount of fluoroolefin, cyclohexylvinyl 
ether, alkylvinyl ether, and hydroxyalkylvinyl ether as essential 
constituents, not only is the curability improved to a great extent, to 
enable curing within a short time by use of a known curing agent such as 
melamine, etc., but also a weathering-resistant coating having an enriched 
gloss and excellent solvent resistance, which is curable at a normal 
temperature by the use of isocyanate, can be obtained. 
Also, Japanese Unexamined Patent Publication (Kokai) No. 59-197471 
described a thermosetting resin composition for paint comprising a 
fluorine-containing copolymer. This publication disclosed that a solid 
color paint, metallic paint, clear paint, etc., having an excellent water 
resistance, solvent resistance, weathering resistance, etc., can be 
obtained by using a thermosetting resin composition for paint comprising a 
mixture of copolymers of a fluorine-containing copolymer containing a 
hydroxyl group and a copolymer comprising an alkyl ester of acrylic acid 
or methacrylic acid with other acrylic monomers, and a curing agent 
containing a functional group reactive with the hydroxyl group. 
Further, Japanese Unexamined Patent Publication (Kokai) No. 61-46283 
disclosed a paint composition containing a fluorine-containing copolymer. 
According to this publication, a coating having an excellent weathering 
resistance over a long term and an excellent appearance with a high gloss 
and good sharpness can be obtained by applying, as the final coating, a 
top clear paint comprising a polyol component comprising a 
fluorine-containing copolymer comprising fluoroolefin, cyclohexylvinyl 
ether, alkylvinyl ether, hydroxyalkylvinyl ether, and another copolymer 
polymerized at specific proportions, and an acrylic copolymer, and a 
polyhydric isocyanate compound or an aminoplast compound, on the base 
paint coating. 
However, these coating compositions of the prior art contain a copolymer 
resin such as a fluorine-containing resin, and when a powder paint or 
water-dispersion paint is used, require baking at a high temperature have 
a poor coating appearance, and further, the solvent soluble type is very 
expensive and has a drawback in that the adhesiveness to the undercoat or 
recoating adhesiveness are poor. 
Further, there was a problem in that the pigment-dispersed type top-coat of 
the prior art has unsatisfactory coating characteristics when the coating 
appearance is preferentially taken into account, and conversely, has an 
inferior appearance when the coating performance is preferentially taken 
into account. Accordingly, it has been very difficult in the prior art to 
satisfy both of these two antagonistic requirements. 
As described above, attempts have been made in the prior art to coat a 
fluorine type resin on the exterior coating or formulate the resin in the 
top-coat paint, to improve the properties of an exterior top-coat, such as 
weathering resistance, solvent resistance, and dirt resistance, but 
problems still remain in that the appearance is bad, as mentioned above, 
and the adhesiveness to the undercoat or recoating adhesiveness are also 
bad. Conversely, if an attempt is made to improve the appearance of the 
coating, a problem arises in that coating properties such as weathering 
resistance, solvent resistance, and dirt resistance, etc., become 
unsatisfactory. 
SUMMARY OF THE INVENTION 
Accordingly, an object of the present invention is to provide a 
copolymer-containing coating composition which provides an exterior top 
coating having excellent coating properties such as weathering resistance, 
solvent resistance, and dirt resistance, and having a good appearance, 
adhesiveness to the substrate and recoating adhesiveness, by solving the 
problems of the prior art as described above. 
Other objects and advantages of the present invention will be apparent from 
the following description. 
In accordance with the first embodiment of the present invention, there is 
provided a coating composition which comprises: 
(i) a mixture of copolymers comprising (a) 20% to 80% by weight, in terms 
of the resin solid content, of at least one copolymer selected from the 
group consisting of silicon-containing copolymers and fluorine-containing 
copolymers comprising 40 to 60 mol % of fluoroolefin, 45 to 5 mol % of 
cyclohexylvinyl ether, 15 to 5 mol % of alkylvinyl ether, and 0 to 30 mol 
% of other comonomers, having an active hydrogen group and b) 80% to 20% 
by weight, in terms of the resin solid content, of an acrylic copolymer 
resin having a solubility parameter greater by 0.5 to 1.5 than that of the 
copolymer (a) and having an active hydrogen group, and 
(ii) a curing agent having a solubility parameter greater by 0.5 to 1.5 
than that of the copolymer (a). 
The use of such a copolymer-containing coating composition can solve the 
above problems. 
In accordance with the second embodiment of the present invention, there is 
also provided a coating composition which further contains, in addition to 
the above-mentioned essential constituents, a pigment dispersed in the 
above-mentioned acrylic copolymer resin.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As described above, according to the present invention, by applying a 
coating of a formulation of a copolymer having an active hydrogen group 
with a specific acrylic copolymer resin on a conventional overcoating, the 
weathering resistance, solvent resistance, and dirt resistance, etc., of 
the cover-coat can be greatly improved, also, for example, the undercoat 
adhesiveness or recoating adhesiveness can be improved, without impairing 
the characteristics of the fluorine-containing copolymer and/or 
silicon-containing copolymer, and in addition, costs can be reduced 
without impairing the characteristics of the expensive fluorine-containing 
resin and/or silicon containing copolymer, thus also having a great 
economical effect. 
The acrylic copolymer resin having an active hydrogen group and the curing 
agent to be used in the present invention are both essentially required to 
have specific solubility parameters as mentioned above, and the solubility 
parameter (i.e. SP value) .delta.sp is determined by the formula of K. W. 
SUH, J. M. CORBETT (Journal of Applied Polymer Science, 12, 2359, 1968) 
shown below. 
##EQU1## 
wherein ml: low Sp solvent, mh: high Sp solvent, .delta.: solubility 
parameter, V: molecular volume at turbidity point. 
The .delta.sp value of the resin used herein is determined by vaporizing a 
solvent in the sample and then by redissolving 0.5 g of the resultant 
resin solid in 10 ml of dioxane, followed by measuring according to a 
turbidity titration method by using n-hexane and water. 
Coating compositions comprising mixtures of copolymers having an active 
hydrogen group and acrylic copolymers have been known in the prior art, 
but all are products of a compromise by which the characteristics of the 
above copolymer are sacrificed to some extent, and it is presumed that the 
above copolymer is compatible with the acrylic resin, or no reference is 
made to compatibility. In contrast, the composition according to the 
present invention requires that the above copolymer should be incompatible 
to some extent with the acrylic resin, and this is defined by the 
solubility parameters as specified above. That is, in the present 
invention, the solubility parameters of the acrylic resin and the curing 
agent must be values greater by 0.5 or more, relative to the solubility 
parameter value of the above copolymer. 
The coating obtained from a mixture of resins incompatible with each other 
or a mixture of resins which are incompatible to some extent, as mentioned 
above, tends to separate into two layers during setting or baking, because 
it is per se incompatible. At that time, the resin component with a 
smaller surface energy is liable to be oriented, i.e., floating at the top 
portion of the coating film, on the coating surface. Since the solubility 
parameter value and the surface energy have a parallel relationship, the 
copolymer component with the lower solubility parameter value is liable to 
be oriented on the coating surface, whereby the surface has the 
characteristics of the above copolymer, but conversely, the lower portion 
of the coating has the characteristics of the acrylic resin. Further, when 
a pigment is dispersed in the acrylic resin, the resin component 
containing the pigment with a greater solubility parameter value is 
oriented in the lower layer of the coating, but conversely, a clear layer 
with a greater solubility parameter value is liable to be oriented on the 
upper portion of the coating. Because a clear layer is formed at the upper 
portion, the coating thus obtained becomes a coating with a deep tone, and 
further, the characteristics of the clear layer resin can be imparted to 
the coating surface. For example, if a fluorine resin and/or a silicon 
resin is formed in the clear layer, only a small amount of the expensive 
fluorine resin and/or silicon resin having the weathering resistance, 
solvent resistance and dirt resistance functions of the fluorine resin 
and/or silicon resin need be used, whereby costs are reduced to a great 
extent compared with a coating of the fluorine resin alone, although 
having the same functions. There are no reports in the prior art that a 
two layer separation can be achieved by adjusting the compatibility of two 
or more of resins in a liquid composition, i.e., a resin suitable for 
dispersing the pigments therein and a resin essential to effect the 
desired characteristics or an additional resin used in combination with 
the base resin. 
As the difference in the solubility parameter value of the acrylic 
copolymer resin and the curing resin relative to the above copolymer 
having an active hydrogen such as a hydroxyl group, carboxylic group, 
etc., is smaller than 0.5, the compatibility of these acrylic copolymer 
resin and curing agent is good, whereby the surface orientation effect of 
the copolymer as mentioned above cannot be exhibited. On the other hand, 
when the solubility parameter of the acrylic copolymer resin and the 
curing agent exhibits a value smaller than that of the above copolymer, 
the surface orientation tendency of the acrylic resin is reversed, whereby 
the characteristics of the above copolymer cannot be made available. The 
solubility parameter value of the acrylic copolymer and the curing agent 
desirably should be greater by 0.5 or more, preferably 0.5 to 1.5, than 
the Sp value of the fluorine-containing copolymer and the 
silicon-containing resin. 
The content of the copolymer having the above active hydrogen group in the 
copolymer mixture in the coating composition according to the present 
invention is 10% to 90% by weight. When the above-mentioned copolymer is 
less than 10% by weight, the characteristics of the copolymer cannot be 
made fully available, and conversely, if in excess of 90% by weight, the 
adhesiveness to the substrate is poor, the costs are higher, and the 
shielding characteristic is undesirably degraded. The content of the 
above-mentioned copolymer is preferably within the range of 20% to 80% by 
weight. 
As the copolymer having the active hydrogen group according to the present 
invention, for example, there may be included copolymers having one or 
more bonds such as --OH, --COOH, --NH.sub.2, &gt;NH, --SH, --SiOH, --SiH, 
etc., such as fluorine resin, silicon resin, acrylic resin, polyester 
resin, alkyl resin, etc., particularly preferably fluorine resin or 
silicon resin. The fluorine resin may be preferably a fluorine containing 
copolymer comprising 40 to 60 mol % of fluoroolefin, 45 to 5 mol % of 
cyclohexylvinyl ether, 15 to 5 mol % of alkylvinyl ether and 0 to 30 mol % 
of other comonomers. Of the above fluorine copolymers, as disclosed in 
Japanese Patent Publication (Kokoku) No.60-21686 as mentioned above, those 
with too low a content of fluoroolefin are not preferable with respect to 
weathering resistance, and those with too high a fluoroolefin content tend 
to be disadvantageous from the aspects of manufacturing costs. Also, those 
with too low a content of cyclohexylvinyl ether tend to have an 
undesirably lowered hardness in the coating, and those with too low a 
content of alkylvinyl ether tend to have an undesirably lowered 
flexibility. Also, it is particularly important to contain 
hydroxyalkylvinyl ether at a proportion within the range as specified 
above, to improve the curability without impairing the various useful 
characteristics thereof as the paint. More specifically, a fluorine 
copolymer with too high a content of hydroxyalkylvinyl ether not only has 
a lowered solubility of the copolymer in organic solvents, but also a 
lowered flexibility of the coating, and conversely, if the content is too 
low, the durability and adhesiveness of the coating tend to be undesirably 
lowered. As the fluoroolefin, perhaloolefins, particularly 
chlorotrifluoroethylene or tetrafluoroethylene, are preferred. As the 
alkylvinyl ether, those having straight or branched alkyl group of 2 to 8 
carbon atoms, particularly with alkyl groups having 2 to 4 carbon atoms, 
are preferred. 
The above fluorine-containing copolymer can also contain comonomers other 
than the four kinds of essential constituents as mentioned above, within 
the range which does not exceed 30 mol %. As such comonomers, ethylene, 
propylene, isobutylene, vinyl chloride, vinylidene chloride, methyl 
methacrylate, butyl acetate, etc., may be included. 
The above fluorine-containing copolymer can be produced according to 
conventional methods by carrying out a copolymerization reaction by 
permitting a polymerization initiator (e.g., peroxide compound such as 
benzoyl peroxide, etc., and azo type compound such as 
azobisisobutylonitrile, etc.) to act on a monomeric mixture at 
predetermined proportions in the co-presence of a polymerization medium 
(e.g., aromatic hydrocarbon such as xylene, toluene, etc., and ester type, 
ether type organic solvent). The copolymerization reaction temperature is 
not particularly limited, but it is necessary to maintain a general 
temperature sufficient for cleavage of the polymerization initiator. 
As the silicon resin to be used in the present invention, any 
resin-containing silicon element in the resin can be used, and is 
generally an organopolysiloxane, a copolymer having a structure of: 
##STR1## 
(wherein R is C.sub.1-3 alkyl group or phenyl group) introduced into the 
resin structure. To obtain such a copolymer, it is possible to use the 
method in which an organopolysiloxane is mixed into a copolymer containing 
no silicon element, and then a condensation reaction is conducted in the 
presence of heat or a catalyst. Alternatively, the method in which an 
organopolysiloxane is reacted with a vinyl monomer having active hydrogen 
such as acrylic acid, methacrylic acid, etc., to prepare a vinyl monomer 
containing silicon, and then another vinyl monomer is copolymerized 
therewith, can be used. 
The acrylic copolymer resin having the active hydrogen group to be used in 
the present invention can be obtained by copolymerization of various 
ethylenic monomers according to conventional methods. Examples of such 
ethylenic monomers may include aromatic vinyl monomers such as styrene, 
.alpha.-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 
p-tertbutylstyrene, benzyl acrylate, benzyl methacrylate, etc.; acrylic 
acid or methacrylic acid esters (methyl acrylate, ethyl acrylate, 
isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl 
acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, 
n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 
2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl 
acrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, dodecyl 
methacrylate, lauryl methacrylate, stearyl methacrylate, tridecyl 
methacrylate, addition reaction products of oil fatty acids with acrylic 
acid or methacrylic acid ester monomer having oxirane structure (e.g., 
addition reaction product of stearic acid with glycidyl methacrylate), 
itaconic acid ester such as addition reaction product of an oxirane 
compound having C.sub.8 or more alkyl group with acrylic acid or 
methacrylic acid (dimethyl itaconate, etc.), maleic acid ester (dimethyl 
maleate, etc.), fumaric acid ester (methyl fumarate, etc.), acrylonitrile, 
methacrylonitrile, vinyl acetate and other ethylenic monomers. Examples of 
the ethylenic monomer having active hydrogen may include ethylenic 
monomers having hydroxyl group such as hydroxyethyl acrylate, 
hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxymethyl methacrylate, 
hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl 
methacrylate, N-methylolacrylamide, allyl alcohol, etc.; and ethylenic 
monomers having carboxylic group such as methacrylic acid, crotonic acid, 
ethacryl acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, 
maleic anhydride fumaric acid, etc. 
The acrylic copolymer resin can be obtained according to general methods, 
for example, by formulating the above various monomers at predetermined 
proportions, respectively, and polymerizing the mixture in a conventional 
manner. For example, a monomeric formulation is mixed with a known 
polymerization catalyst (e.g., azobisisobutylonitrile, benzoyl peroxide, 
etc.), and adding the mixture dropwise into a reaction vessel containing a 
solvent (e.g., xylene, toluene, mineral spirit, etc.) heated to a 
polymerizable temperature (e.g., 60.degree. to 140.degree. C.), followed 
by aging. 
As the curing agent having an sp value greater by 0.5 or more than that of 
the above copolymer to be formulated in the coating composition of the 
present invention, for example, an alkyl etherated amino resin or an 
isocyanate type compound may be employed. 
When an alkyl etherated amino resin is used as the curing agent, or when a 
copolymer mixture and an alkyl etherated amino resin are used as the 
curing agent, the ratio of the copolymer mixture and the alkyl etherated 
amino resin used is preferably 55/45 to 95/5, more preferably 60/40 to 
80/20, based on weight. On the other hand, when an isocyanate type 
compound is used as the curing agent, the ratio of the copolymer and the 
isocyanate type compound used is preferably 0.3 to 1.5, more preferably 
0.5 to 1.0, in terms of the molar ratio of the isocyanate group/hydroxyl 
group. 
If the amount of the alkyl etherated amino resin used is more than the 
above range, a mutual reaction between the alkyl etherated amino resins is 
likely to occur, whereby the flexibility, etc., of the coating will be 
lowered, but conversely if the amount is too small, a satisfactory 
curability can not be obtained to give a low crosslinking density, whereby 
the weathering resistance, solvent resistance, and dirt resistance are 
undesirably lowered. As the alkyl etherated amino resin, for example, 
melamine resins, urea resins, benzoguanamine resin subjected to alkyl 
etheration such as methyl etheration, butyl etheration, isobutyl 
etheration, methyl butyl mixed etheration, etc., may be employed. Also, to 
accelerate the curing, an acid catalyst (e.g., sulfonic acid type catalyst 
such as p-toluene sulfonic acid, etc. can be added, if necessary. 
On the other hand, if an isocyanate type compound is outside the above 
range, a large amount of isocyanate may remain in the coating, or it may 
react with moisture, etc., in the air to lower the weathering resistance, 
adhesiveness, etc. Conversely, if the amount is too small, the mechanical 
properties, chemical resistance, etc., of the coating are undesirably 
lowered. Examples of the isocyanate type compound may include 
polyisocyanate compounds, polyisocyanate compounds subjected to blocking, 
and examples of the polyisocyanate compound may include ethylene 
diisocyanate, propylene diisocyanate, tetramethylene diisocyanate 
hexamethylene diisocyanate, phenylene diisocyanate, isophorone 
diisocyanate, and the like. Also, as the polyisocyanate compound subjected 
to blocking, those obtained by blocking of the polyisocyanate compound as 
mentioned above with a blocking agent may be employed, and examples of the 
blocking agent may include phenol type, alcohol type, mercaptan type, 
oxime type, imine type compounds, etc. 
As the pigment available in the second embodiment of the present invention, 
for example, inorganic tinting pigments such as titanium dioxide, zinc 
oxide, chrome yellow, etc., inorganic extender pigments such as barium 
sulfate, talc etc., organic pigments such as azo type, quinacridone type, 
perylene type, cyanine blue type, carbon black, etc., can be used. These 
pigments are formulated in a conventional manner generally in an amount of 
1% to 50% by weight, preferably 5% to 50% by weight, in the case of an 
inorganic pigment, and 5% to about 20% by weight in the case of an organic 
pigment, in the above acrylic resin. Also, a flaky metal powder can be 
used in combination with the above pigment, or alone when dispersed in the 
acrylic copolymer resin for dispersion. 
In the coating composition according to the present invention, in addition 
to the essential components as described above, any desired component 
generally formulated in paint compositions of the prior art can be 
included so long as the desired characteristics described above are not 
impaired. Such components may include organic solvents such as aliphatic, 
alicyclic, aromatic hydrocarbons, esters, ethers, ketones, alcohols, 
(generally 1% to 90% by weight), etc., and further, other conventional 
additives can be formulated. 
EXAMPLES 
In the following, the present invention is described in more detail by 
referring to Examples, which in no way limit the scope of the present 
invention. In the following Examples, "%" and "parts" indicate "% by 
weight" and "parts by weight", unless otherwise specified. 
EXAMPLES 1-4 AND COMATIVE EXAMPLES 
Preparation of Formulated Components 
(1) Preparation of Fluorine-Containing 
Copolymer (A) 
A 50% xylene solution of a fluorine-containing copolymer (Lumiflon LF-200, 
produced by Asahi Glass K.K.) was prepared. This fluorine-containing 
copolymer had a hydroxyl value of 52 (mgKOH/g) and a solubility parameter 
value of 9.8 (hereinafter called fluorine-containing copolymer A). 
(2) Preparation of Silicon-Containing 
Copolymer (B) 
A solvent mixture of 90 parts of xylene and 10 parts of MIBK was heated to 
105.degree. C., and to this mixture was added a mixture of 10 parts of a 
silicon-containing monomer having a structure of the formula: 
##STR2## 
16.9 parts of styrene, 7.3 parts of methyl methacrylate, 46.5 parts of 
ethylhexyl methacrylate, 16.2 parts of hydroxyethyl methacrylate and 3.1 
parts of methacrylic acid, and 0.7 parts of azobisisobutylonitrile over 4 
hours, and further, polymerization was carried out at the same temperature 
for 2 hours. 
The silicon-containing copolymer obtained had a solubility parameter value 
of 9.8, a hydroxyl value of mgKOH/g, and an acid value of 20 mgKOH/g 
(hereinafter called silicon-containing copolymer B). 
(3) Preparation of Acrylic Copolymer Resin (C-1-C-3) 
The solvent with the composition shown in Table 1 was heated to 105.degree. 
C., and the mixture comprising monomers with the composition and the 
polymerization initiator shown in Table 1 were added dropwise thereto over 
4 hours, and further, polymerization was carried out at the same 
temperature for 2 hours. 
TABLE 1 
______________________________________ 
Resin C-1 C-2 C-3 
______________________________________ 
Composition: 
Solvent; 
Xylene 90 90 90 
MIBK 10 10 10 
Monomer; 
Styrene -- -- 16.9 
Ethyl acrylate 31.0 8.6 -- 
Methyl methacrylate 
29.5 25.3 7.3 
Ethylhexyl methacrylate 
20.2 46.8 56.5 
Hydroxyethyl methacrylate 
16.2 16.2 16.2 
Methacrylic acid 3.1 3.1 3.1 
Polymerization initiator 
0.7 0.7 0.7 
(Azobisisobutylonitrile) 
Solubility parameter value 
11.0 10.5 10.0 
Hydroxyl value (mgKOH/g) 
70 70 70 
Acid value (mgKOH/g) 
20 20 20 
______________________________________ 
(4) Curing Agent 
D-1 Sumidule N-75, produced by Sumitomo Bayer Urethane Co. (urethane type 
curing agent, solids 75%) 
D-2 Cymel 1130-254J, produced by Mitsui Cyanamide Co. (methyl butyl mixed 
etherated melamine resin, solids 80%) 
D-3 Uvan 20N-60, produced by Mitsui Toatsu Co. (butyl etherated melamine 
resin, solids 60%) 
The curing agents D-1, D-2 and D-3 had solubility parameter values of 11.0, 
11.3 and 10.1, respectively. 
(5) Preparation of Coating Materials 
Coating materials were prepared by mixing with the compositions, shown in 
varnish ratio, in Table 2. 
TABLE 2 
__________________________________________________________________________ 
Example Comparative Example 
Component 
1 2 3 4 1 2 3 4 5 6 
__________________________________________________________________________ 
A 39 39 39 39 39 39 78 -- -- -- 
C-1 39 -- 39 -- 39 -- -- 78 -- -- 
C-2 -- 39 -- 39 -- -- -- -- 78 -- 
C-3 -- -- -- -- -- 39 -- -- -- 78 
D-1 6.9 
6.9 
-- -- -- 17.7 
17.7 
17.7 
17.7 
17.7 
D-2 -- -- 12.3 
12.3 
-- -- -- -- -- -- 
D-3 -- -- -- -- 16.3 
-- -- -- -- -- 
Solvesso 100 
7.0 
7.0 
5.0 
5.0 
7.0 
7.0 
7.0 
7.0 
7.0 
7.0 
Solvesso 150 
-- -- 5.0 
5.0 
-- -- -- -- -- -- 
Xylene 3.0 
3.0 
-- -- 3.0 
3.0 
3.0 
3.0 
3.0 
3.0 
__________________________________________________________________________ 
(Note): Solvesso 100 and Solvesso 150: Aromatic hydrocarbon solvents 
produced by Exxon Chemical 
Preparation of Coatings 
On a substrate of a dull steel plate chemically treated with zinc phosphate 
of 0.8.times.90.times.300 mm, which was further subjected to cationic 
electrodeposition (Power Coat U-500, produced by Nippon Paint Co.), an 
intercoating (Orga OP-2 Gray, produced by Nippon Paint Co.) and a 
top-coating (Orga G-65 White, produced by Nippon Paint K.K.), a clear 
coating material adjusted to a viscosity of 20 seconds by #4 Ford Cup with 
a solvent mixed at a ratio of Solvesso 100: xylene: and Solvesso 150 of 
5:3:2, was applied to a film thickness of 30 .mu.m, was then allowed to 
set at room temperature for 7 minutes, and was baked at 140.degree. C. for 
30 minutes to prepare a test piece. 
Coating Performance Tests 
The following evaluation tests of the coatings obtained above were 
conducted respectively. 
(1) Adhesiveness 
100 checkered pieces were cut on the test strip, in accordance with 
JIS-K-5400 6.15, and after a commercially available Cellophane tape was 
pressure adhered thereon, the tape was at once peeled off and the 
checkered pieces remaining on the test strip after peeling were counted to 
confirm the adhesiveness between the overcoating and the clear coating. 
(2) Recoating Adhesiveness 
On the coating as prepared above, a clear coating material adjusted to a 
similar viscosity was applied, and again baked at 140.degree. C. for 30 
minutes. The test piece was tested according to the method of (1) to 
confirm adhesiveness between the clear coating and the clear coating. 
(3) Contact Angle 
The coating as prepared above was subjected to measurement of the contact 
angle with water by use of FACE contact angle form produced by Kyowa 
Kaimen Kagaku Co. 
(4) Weathering Resistance Test 
A natural exposure for 2 years was carried out in Okinawa, and the gloss of 
the coating (60.degree. gloss) was measured. 
The results were as shown in Table 3. 
TABLE 3 
__________________________________________________________________________ 
Example Comparative Example 
1 2 3 4 1 2 3 4 5 6 
__________________________________________________________________________ 
Fluorine resin 
A A A A A A A -- -- -- 
Acrylic resin 
C-1 C-2 C-1 C-2 C-1 C-3 -- C-1 C-2 C-3 
Curing agent D-1 D-1 D-2 D-2 D-3 D-1 D-1 D-1 D-1 D-1 
Adhesiveness 100/100 
100/100 
100/100 
100/100 
100/100 
100/100 
50/100 
100/100 
100/100 
100/100 
Recoating adhesiveness 
100/100 
100/100 
100/100 
100/100 
100/100 
100/100 
0/100 
100/100 
100/100 
100/100 
Contact angle 
90.0 90 91 90 78 87 91 74 76 78 
Weathering resistance 
99 101 98 96 92 90 98 83 85 85 
60.degree. C. gloss retention 
after 2 years exposure in 
Okinawa 
__________________________________________________________________________ 
EXAMPLES 5-8 AND COMATIVE EXAMPLES 7-8 
Coating compositions with the compositions shown in Table 4 were prepared 
as described in Examples 1-4 and Comparative Examples 1-6, and their 
performance were evaluated. 
The results were as shown in Table 4. 
TABLE 4 
__________________________________________________________________________ 
Comparative 
Example Example 
5 6 7 8 7 8 
__________________________________________________________________________ 
Fluorine resin 
A/74 A/62.4 
A/15.6 
A/3.9 
A/75.7 
A/2.3 
Acrylic resin 
C-1/3.9 
C-1/15.6 
C-1/62.4 
C-1/74.1 
C-1/2.3 
C-1/75.7 
Curing agent 
D-1/17.7 
D-1/17.7 
D-1/17.7 
D-1/17.7 
D-1/17.7 
D-1/17.7 
Adhesiveness 
100/100 
100/100 
100/100 
100/100 
70/100 
100/100 
Recoating adhesiveness 
100/100 
100/100 
100/100 
100/100 
50/100 
100/100 
Contact angle 
91 90 90 89 91 80 
Weathering resistance 
100 100 98 94 100 87 
__________________________________________________________________________ 
EXAMPLES 10-11 AND COMATIVE EXAMPLES 9-10 
As shown in the formulations of Table 5, 39 parts of the acrylic resin and 
40 parts of titanium dioxide were premixed according to a conventional 
method, and subsequently dispersed by a sand grind mill (hereinafter 
called SG mill), followed by mixing the remaining resins as a dissolution 
resin, curing agent, and xylene, to prepare white coating materials. 
TABLE 5 
______________________________________ 
Comparative 
Example Example 
10 11 9 10 
______________________________________ 
Fluorine resin 
A/39 A/39 A/39 -- 
Acrylic resin 
C-1/39 C-1/39 C-3/39 C-1/78 
Curing agent 
D-1/17.2 D-2/12.3 D-1/17/7 
D-1/17.7 
Titanium dioxide 
40 40 40 40 
Xylene 10 10 10 10 
______________________________________ 
On a substrate of a dull steel plate chemically treated with zinc 
phosphate, which was further subjected to cationic electrodeposition 
(Power Coat V-500, produced by Nippon Paint Corp.), an intercoating (Orga 
OP-2 Gray, produced by Nippon Paint Corp.), the above white coating 
material adjusted to a viscosity of 20 seconds by #4 Ford Cup with a 
solvent at a ratio of Solvesso 100/xylene=5/5, was applied to a film 
thickness of 40 .mu.m, was then allowed to set at room temperature for 7 
minutes, and was baked at 140.degree. C. for 30-minutes to prepare a test 
piece. 
The performances of the coatings obtained were as shown in Table 6. 
TABLE 6 
______________________________________ 
Comparative 
Example Example 
10 11 9 10 
______________________________________ 
Finished appearance 
.smallcircle. 
.smallcircle. 
x .smallcircle. 
Adhesiveness 100/100 100/100 100/100 
100/100 
Recoating 100/100 100/100 100/100 
100/100 
adhesiveness 
Contact angle 
90 90 84 74 
Weathering resistance 
92 87 72 42 
60.degree. gloss retention 
after 2 years exposure 
in Okinawa 
______________________________________ 
EXAMPLES 12-15 AND COMATIVE EXAMPLES 11-16 
As shown in the formulations of Table 7, 39 parts of the resin C-1, C-2, or 
C-3 (39 parts of the resin A in the case of Comparative Example 13) and 45 
parts of the component E-1 were premixed according to a conventional 
method, then dispersed by a paint shaker (produced by Red Devil Co.), and 
further mixed with the remaining resin components as a dissolution resin, 
the curing agent, and the solvents to prepare white coating materials. 
On a substrate of a dull steel plate chemically treated with zinc phosphate 
of 0.8.times.90.times.300 mm which was further applied with a cationic 
electrodeposition, (Power Coat U-500, produced by Nippon Paint Co.) and an 
intercoating (Orga OP-2 Gray, produced by Nippon Paint), a clear coating 
material adjusted to a viscosity of 20 seconds by 4 Ford Cup with a 
solvent mixed at a ratio of Solvesso 100: xylene: and Solvesso 150 of 
5:3:2 was applied to a film thickness of 30.mu.. After allowing to set at 
room temperature for 7 minutes, the coated steel substrate was baked at 
140.degree. C. for 30 minutes to prepare a test piece. 
The evaluation of the coating obtained was conducted as in Example 1. The 
results were as shown in Table 7. 
TABLE 7 
__________________________________________________________________________ 
Example Comparative Example 
Component 12 13 14 15 11 12 13 14 15 16 
__________________________________________________________________________ 
A 39 39 39 39 39 39 78 -- -- -- 
C-1 39 -- 39 -- 39 -- -- 78 -- -- 
C-2 -- 39 -- 39 -- -- -- -- 78 -- 
C-3 -- -- -- -- -- 39 -- -- -- 78 
D-1 6.9 
6.9 
-- -- -- 17.7 
17.7 
17.7 
17.7 
17.7 
D-2 -- -- 12.3 
12.3 
-- -- -- -- -- -- 
D-3 -- -- -- -- 16.3 
-- -- -- -- -- 
E-1 45 45 45 45 45 45 45 45 45 45 
Solvesso 100 
7.0 
7.0 
5.0 
5.0 
7.0 
7.0 
7.0 
7.0 
7.0 
7.0 
Solvesso 150 
-- -- 5.0 
5.0 
-- -- -- -- -- -- 
Xylene 3.0 
3.0 
-- -- 3.0 
3.0 
3.0 
3.0 
3.0 
3.0 
Contact angle 
90 90 90 90 78 86 90 73 76 82 
Gloss retention 
90 90 86 88 72 70 92 62 64 67 
after 2 years' exposure 
in Okinawa 
Finished appearance 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.DELTA. 
.DELTA. 
x x x x 
__________________________________________________________________________ 
(Note 1): Component E1 = Titanium dioxide 
(Note 2): Solvesso 100 and Solvesso 150: Aromatic hydrocarbon solvents 
produced by Shell Petroleum 
EXAMPLE 16-23 AND COMATIVE EXAMPLE 17-22 
Coating materials with the composition shown in Table 8 were prepared as 
described in Examples 12-15 and Comparative Examples 11-16, and their 
performances were evaluated. 
The results were as shown in Table 8. 
TABLE 8 
__________________________________________________________________________ 
Example Comparative Example 
Component 16 17 18 19 20 21 22 23 17 18 19 20 21 22 
__________________________________________________________________________ 
A 39 
39 39 39 39 39 39 39 39 39 78 -- -- -- 
C-1 39 39 39 39 39 -- 39 -- 39 -- -- 78 -- -- 
C-2 -- -- -- -- -- 39 -- 39 -- -- -- -- 78 -- 
C-3 -- -- -- -- -- -- -- -- -- 39 -- -- -- 78 
D-1 6.9 
6.9 
6.9 
6.9 
6.9 
6.9 
-- -- -- 17.7 
17.7 
17.7 
17.7 
17.7 
D-2 -- -- -- -- -- -- 12.3 
12.3 
-- -- -- -- -- -- 
D-3 -- -- -- -- -- -- -- -- 16.3 
-- -- -- -- -- 
E-1* 45 -- -- -- -- 45 45 45 45 45 45 45 45 45 
E-2* -- 11 -- -- -- -- -- -- -- -- -- -- -- -- 
E-3* -- -- 11 -- -- -- -- -- -- -- -- -- -- -- 
E-4* -- -- -- 11 -- -- -- -- -- -- -- -- -- -- 
E-5* -- -- -- -- 7.8 
-- -- -- -- -- -- -- -- -- 
Solvesso 100 
7.0 
7.0 
7.0 
5.0 
7.0 
7.0 
5.0 
5.0 
7.0 
7.0 
7.0 
7.0 
7.0 
7.0 
Solvesso 150 
-- -- -- -- -- -- 5.0 
5.0 
-- -- -- -- -- -- 
Xylene 3.0 
3.0 
3.0 
-- 3.0 
3.0 
-- -- 3.0 
3.0 
3.0 
3.0 
3.0 
3.0 
Contact angle 
90 90 90 90 90 90 88 87 76 72 91 74 76 76 
Gloss retention 
95 90 94 90 92 94 90 90 86 90 98 83 84 81 
after 2 years' exposure 
in Okinawa 
Finished appearance 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
x .DELTA. 
.DELTA. 
.DELTA. 
__________________________________________________________________________ 
*Pigment 
E1 Titanium dioxide 
E2 Hostaperm yellow H3G, produced by Hoechst Co. (azo type) 
E3 Sinquasia Red YRT759D, produced by Du Pont Co. (quinacridone type) 
E4 Pariogen Red L3910D, produced by BASF Co. (perilene type) 
E5 Alpaste 7610N, produced by Toyo Aluminum Co. 
EXAMPLES 24 AND 25 AND COMATIVE EXAMPLE 23 AND 24 
The coating materials with the compositions shown in Table 9 were prepared 
as described in Examples 16-23 and Comparative Examples 17-22, and their 
performances were evaluated. 
The results were as shown in Table 9. 
TABLE 9 
______________________________________ 
Comparative 
Example Example 
24 25 23 24 
______________________________________ 
A -- 19.5 -- -- 
B 39 19.5 78 -- 
C-1 39 39 -- -- 
C-3 -- -- -- 78 
D-2 12.3 12.3 12.3 12.3 
Solvesso 100 5.0 5.0 5.0 5.0 
Solvesso 150 5.0 5.0 5.0 5.0 
Recoating adhesiveness 
.smallcircle. 
.smallcircle. 
x x 
Contact angle 86 88 86 79 
Weathering resistance 
99 101 98 84 
60.degree. gloss retention 
after 2 years exposure 
in Okinawa 
______________________________________ 
COMATIVE EXAMPLES 25 AND 26 
Coating compositions with the compositions shown in Table 10 were prepared 
in the same manner as mentioned above and their performances were 
evaluated. 
The results are shown in Table 10. 
TABLE 10 
______________________________________ 
Comparative 
Example 
Composition .delta.sp 
25 *1 26 *2 
______________________________________ 
Fluorine-containing copolymer *3 
9.8 80 -- 
Fluorine-containing copolymer *3 
9.8 -- 50 
Acrylic copolymer *4 
11.7 20 50 
Block isocyanate solution *5 
11.9 17.1 -- 
Polyisocyanate compound *6 
10.3 -- 16.1 
Xylene -- 18 18 
Butyl acetate -- 6 6 
Cellosolve acetate -- 6 6 
Dibutyl tin dilaurate 
-- 0.6 0.6 
Contact angle -- 90 85 
Visual appearance -- Poor Poor 
______________________________________ 
*1: According to top clear coating composition No. 2 of JPA-61-46283 
*2: According to top clear coating composition No. 5 of JPA-61-46283 
*3: Lumiflon LF200 by Asahi Glass K.K. 
*4: Prepared in the same manner as in JPA-61-46283 
*5: Coronate 2725 by Nippon Polyurethane K.K. 
*6: Coronate EH by Nippon Polyurethane K.K. 
COMATIVE EXAMPLE 27 
A coating composition having the composition shown in Table 11 was prepared 
and the performance thereof was evaluated in the same manner as mentioned 
above. 
The results are shown in Table 11. 
TABLE 11 
______________________________________ 
Comparative 
Composition .delta.sp 
Example 27 
______________________________________ 
Fluorine-containing resin *1 
9.8 20 
Polyisocyanate compound *2 
11.0 14 
Acryl copolymer solution *3 
10.3 80 
Aluminum paste *4 -- 10 
Butyl acetate -- 10 
Contact angle -- 83 
Visual appearance -- Poor 
______________________________________ 
*1: Lumiflon LF200 by Asahi Glass K.K. 
*2: Sumidule N75 by Sumitomo Bayer Urethane Co. 
*3: Prepared in the same manner as in Production Example 8 of 
JPA-59-197471 
*4: Aluminum paste 1700 NL by Toyo Aluminum K.K. 
COMATIVE EXAMPLES 28 AND 29 
Coating compositions having the compositions shown in Table 12 were 
prepared and the performance thereof were evaluated in the same manner as 
mentioned above. 
The results are shown in Table 12. 
TABLE 12 
______________________________________ 
Comparative 
Example 
Composition .delta.sp 28 29 
______________________________________ 
Monomer blend A *1 
10.8 300 -- 
Monomer blend B *2 
9.5 -- 300 
Tert-butyl perbenzoate *3 
10.1 6 6 
Siloxamediol A 9.8 1326 660 
Contact angle -- 80 78 
Visual appearance 
-- Poor Poor 
______________________________________ 
*1: Prepared according to Example 1 of GB 117102 
*2: Prepared according to Example 2 of GB 117102 
*3: Uvan 20N60 by Mitsui Toatsu Co. 
As described above, the following effects can be obtained by using the 
coating composition according to the present invention. That is, according 
to the present invention, through the layer separation phenomenon of two 
specific kinds of resins, a coating having an excellent appearance and 
deep tone of the upper clear layer and the lower pigment layer can be 
obtained, and the characteristics of the resin in the upper clear layer 
can be imparted as the surface characteristics of the coating in a small 
amount. Further, compared with the composition formed only with a 
copolymer resin and a curing agent, an excellent adhesiveness to the 
substrate, and an excellent economy with a superior weathering resistance 
can be obtained. Further, in a composition containing a pigment, by 
dispersing the pigment with an acrylic resin with a high sp value, for 
example, a fluorine resin with a low sp value can be floated to the upper 
layer, whereby a superior effect can be obtained such that the finished 
appearance is also improved.