Polymer compositions useful as flow aids, and coating compositions containing the polymer compositions

The present invention relates to polymer compositions which are useful particularly as flow aids in coating resin formulations. In one embodiment, the polymer composition is prepared by reacting (A) at least one acrylic ester, vinyl monomer or mixtures thereof, provided the acrylic ester is not a hydroxyalkyl acrylate, (B) at least one monoester of an alpha-beta unsaturated dicarboxylic acid, and (C) at least one hydroxy-containing compound selected from hydroxyalkyl acrylates and compounds characterized by the formula EQU HOR*SH (IIIA) wherein R* is a hydrocarbylene group containing from 2 to about 10 carbon atoms, or mixtures thereof. The invention also relates to improved coating compositions comprising a coating resin and a flow-improving amount of a polymer composition derived from (A) at least one acrylic ester (not a hydroxyalkyl acrylate) vinyl monomer or mixtures thereof, (B) at least one alpha-beta unsaturated carboxylic acid compound containing only one carboxylic acid group, and (C) at least one hydroxyalkyl acrylate. The coating compositions exhibit improved stain-resistance and recoatability.

TECHNICAL FIELD 
This invention relates to polymer compositions useful as flow aids for 
resin coating formulations. In particular, the invention relates to 
acrylic polymer compositions and to coating formulations containing the 
polymer compositions. The coating compositions containing the polymer 
compositions of the present invention exhibit improved properties, and in 
particular, stain-resistance and recoatability. 
BACKGROUND OF THE INVENTION 
Various types of liquid coating compositions have been applied to 
substrates such as metallic substrates and baked thereon in order to 
protect substrates against degradation and corrosion. The coatings 
deposited on the substrates must generally be sufficiently adherent and 
flexible to resist cracking, chipping and peeling. The coating also must 
be resistant to staining and soiling, and it is also desirable that the 
coated substrate be recoatable with one or more additional coatings. The 
ability of the initial coating to provide a good adhesive bond with the 
second and subsequent coatings is an important consideration when 
evaluating coating compositions. 
A variety of resin materials have been utilized as coating compositions on 
various substrates, and the coating resins include polyester resins, 
acrylic resins, alkyd resins, vinyl resins, etc. The present invention 
relates particularly to coating compositions utilizing polyester or alkyd 
resins. Polyester and alkyd resin coating formulations will contain in 
addition to the resin, one or more pigments, pigment extenders, suspending 
agents, binders, thinners, dryers, vehicles, flow aids, etc., to improve 
application properties as well as to improve the appearance of the coating 
applied to various substrates. Many materials have been suggested in the 
prior art for use in polyester and alkyd resin coating compositions to 
improve the application properties and film appearance, and many of these 
can be utilized in the coating compositions of the present invention. 
Flow aids are incorporated into coating compositions such as paint 
formulations to reduce surface defects in paint films and to contribute to 
a smooth, level, even, and uniform film. Film defects can be caused by air 
bubbles in the applied paint film, by dust, dirt, oil, or other 
contaminants in the film or on the substrate which, as a result of 
differences in surface tensions, cause the paint to pull away from the 
contaminant resulting in film defects known as "craters", or "fish-eyes". 
Materials useful as flow aids function by migrating to the surface of a 
paint film after the film has been applied to a substrate where the flow 
aids lower surface tension so that air bubbles are broken and/or are 
capable of leaving the paint film, and when the surface tension of the 
paint film has been lowered by the flow aid, the paint does not pull away 
from contaminants thereby resulting in a smooth, level and generally 
defect-free coating. 
Flow aids based on acrylic polymers have been utilized in the prior art. 
For example, Modaflow is a commercial acrylic flow aid available from 
Monsanto. This and other commercially available acrylic flow aids are 
effective in improving the surface characteristics of coatings such as 
paints, but in some instances, coatings and paints utilizing such acrylic 
flow aids have a tendency to attract and collect dirt thereby resulting in 
stains and generally unsatisfactory appearance. Moreover, coatings and 
paints containing some presently available acrylic flow aids are often 
characterized by unsatisfactory recoatability. Silicon-type flow aids, for 
example, are known for their poor recoatability. 
Prior art acrylic polymer compositions which have been suggested as being 
useful as flow aids in various coating and paint formulations generally 
are soft, low Tg (glass transition) polymers based on long chain acrylate 
or methacrylate esters such as butyl acrylate, lauryl methacrylate, 
stearyl methacrylate, 2-ethylhexyl acrylate, etc. 
SUMMARY OF THE INVENTION 
The present invention relates to polymer compositions which are useful 
particularly as flow aids in resin coating formulations. In one 
embodiment, the polymer composition is prepared by reacting (A) at least 
one acrylic ester, vinyl monomer or mixtures thereof, provided the acrylic 
ester is not a hydroxyalkyl acrylate, (B) at least one monoester of an 
alpha-beta unsaturated dicarboxylic acid, and (C) at least one 
hydroxy-containing compound selected from hydroxyalkyl acrylates and 
compounds characterized by the formula 
EQU HOR*SH (IIIA) 
wherein R* is a hydrocarbylene group containing from 2 to about 10 carbon 
atoms, or mixtures thereof. 
The invention also relates to improved coating compositions comprising a 
coating resin and a flow-improving amount of a polymer composition derived 
from (A) at least one acrylic ester, vinyl monomer or mixtures thereof, 
provided the acrylic ester is not a hydroxyalkyl acrylate, (B) at least 
one alpha-beta unsaturated carboxylic acid compound containing only one 
carboxylic acid group, and (C) at least one hydroxy-containing compound 
selected from hydroxyalkyl acrylates and compounds characterized by the 
formula 
EQU HOR*SH (IIIA) 
wherein R* is a hydrocarbylene group containing from 2 to about 10 carbon 
atoms, or mixtures thereof. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a first embodiment, the present invention relates to polymer 
compositions including acrylic polymer compositions and polymers obtained 
by polymerizing vinyl monomers such as styrene monomers. The polymer 
compositions of the present invention result from the polymerization of at 
least three copolymerizable monomers, namely, 
(A) at least one acrylic ester, vinyl monomer or mixtures thereof, provided 
the acrylic ester is not a hydroxyalkyl acrylate, 
(B) at least one alpha-beta unsaturated carboxylic acid compound containing 
only one carboxylic acid group, and 
(C) at least one hydroxy-containing compound selected from hydroxyalkyl 
acrylates and compounds characterized by the formula 
EQU HOR*SH (IIIA) 
wherein R* is a hydrocarbylene group containing from 2 to about 10 carbon 
atoms, or mixtures thereof. When component (A) is an acrylic ester, the 
polymer compositions are characterized herein as acrylic polymer 
compositions. 
As used in this specification and in the appended claims, the terms 
"hydrocarbyl" and "hydrocarbylene" denote a group having a carbon atom 
directly attached to the polar group and having a hydrocarbon or 
predominantly hydrocarbon character within the context of this invention. 
Such groups include the following: 
(1) Hydrocarbon groups; that is, aliphatic, (e.g., alkyl or alkenyl), 
alicyclic (e.g., cycloalkyl or cycloalkenyl), and the like, as well as 
cyclic groups wherein the ring is completed through another portion of the 
molecule (that is, any two indicated substituents may together form an 
alicyclic group). Such groups are known to those skilled in the art. 
Examples include methyl, ethyl, octyl, decyl, octadecyl, cyclohexyl, etc. 
(2) Substituted hydrocarbon groups; that is, groups containing 
non-hydrocarbon substituents which, in the context of this invention, do 
not alter the predominantly hydrocarbon character of the group. Those 
skilled in the art will be aware of suitable substituents. Examples 
include halo, hydroxy, alkoxy, etc. 
(3) Hetero groups; that is, groups which, while predominantly hydrocarbon 
in character within the context of this invention, contain atoms other 
than carbon in a chain or ring otherwise composed of carbon atoms. 
Suitable hetero atoms will be apparent to those skilled in the art and 
include, for example, nitrogen, oxygen and sulfur. 
In general, no more than about three substituents or hetero atoms, and 
preferably no more than one, will be present for each 10 carbon atoms in 
the hydrocarbyl group. 
Terms such as "alkyl", "alkylene", etc. have meanings analogous to the 
above with respect to hydrocarbyl and hydrocarbylene. 
The term "hydrocarbon-based" also has the same meaning and can be used 
interchangeably with the term hydrocarbyl when referring to molecular 
groups having a carbon atom attached directly to the polar group. 
The term "lower" as used herein in conjunction with terms such as 
hydrocarbyl, alkyl, alkenyl, alkoxy, and the like, is intended to describe 
such groups which contain a total of up to 7 carbon atoms. 
(A) Acrylic Ester, Vinyl Monomer or Mixtures Thereof 
A variety of acrylic esters can be utilized as one of the components in the 
preparation of the acrylic polymer compositions of the invention. The 
acrylic esters may be represented by the formula 
EQU CH.sub.2 .dbd.C(R)COOR.sup.1 (I) 
wherein R is hydrogen or a lower alkyl group, and R.sup.1 is an alkyl 
group. As used in this specification and claims, the terms "lower alkyl" 
and "lower alkylene" include alkyl and alkylene groups containing from 1 
to about 7 carbon atoms. Examples include methyl, ethyl, propyl, butyl, 
pentyl, hexyl and heptyl; methylene, ethylene, propylene, etc. In one 
embodiment, R is hydrogen, methyl or ethyl, and in another embodiment, 
R.sup.1 is an alkyl group containing from 1 to about 24 carbon atoms. In a 
preferred embodiment R is H and R.sup.1 is an alkyl group containing at 
least 4 carbon atoms up to about 24 carbon atoms. When preparing the 
acrylic polymers of the invention utilizing acrylic esters characterized 
by Formula I, more than one acrylic ester can be utilized as component 
(A). 
Typical acrylic esters that can be used as component (A) in the preparation 
of the acrylic polymers are: methyl acrylate, ethyl acrylate, propyl 
acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, hexyl 
acrylate, 2-ethylhexyl acrylate, nonyl acrylate, lauryl acrylate, stearyl 
acrylate, cyclohexyl acrylate, isodecyl acrylate, methyl methacrylate, 
ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl 
methacrylate, nonyl methacrylate, lauryl methacrylate, stearyl 
methacrylate, cyclohexyl methacrylate, isodecyl methacrylate, propyl 
methacrylate, phenyl methacrylate, etc. As noted above, the alkyl 
acrylates of Formula I wherein the alkyl group contains at least 4 carbon 
atoms and R is H are preferred. 
The vinyl monomers useful as component (A) in the preparation of the 
polymer compositions include vinyl aromatic compounds such as styrene and 
substituted styrenes including: methylstyrenes, such as m-methylstyrene, 
o-methylstyrene, p-methylstyrene; dimethylstyrenes such as 
2,5-dimethylstyrene; halogenated styrenes such as m-bromostyrene, 
p-bromostyrene, p-iodostyrene, pentachlorostyrene; and alkoxystyrenes such 
as p-methoxystyrene. Other vinyl monomers include vinyl halides such as 
vinyl chloride, vinyl bromide; nitriles such as acrylonitrile, 
methacrylonitrile, etc. The vinyl monomer also may comprise vinyl esters 
such as vinyl acetate, vinyl propionate, vinyl stearate, etc. 
(B) Alpha-Beta Unsaturated Carboxylic Acid Compound Containing Only One 
Carboxylic Acid Group 
A second essential component in the preparation of the polymer compositions 
useful in the present invention is at least one alpha-beta unsaturated 
carboxylic acid compound containing only one carboxylic acid group. 
Although it is desirable that the compound contain only one free 
carboxylic acid group, the compound (B) may contain carboxylic ester 
groups in addition to the carboxylic acid groups. The alpha-beta 
unsaturated carboxylic acid compound (B) may be characterized by the 
formulae 
EQU CH.sub.2 .dbd.C(R)COOH (IIA) 
or 
EQU HOOCC(R.sup.4).dbd.C(R.sup.4)COOR.sup.3 (IIB) 
wherein R is H or a lower alkyl group, R.sup.3 is an alkyl group, and each 
R.sup.4 is independently H or methyl with the proviso that at least one 
R.sup.4 is H. In one embodiment, R is H, methyl or ethyl, and R.sup.3 is 
an alkyl group containing from 1 to about 24 carbon atoms. In another 
embodiment, R.sup.3 is a lower alkyl group and each R.sup.4 is hydrogen. 
Carboxylic acids of the type represented by Formula IIA are acrylic acids 
including acrylic acid, methacrylic acid, ethacrylic acid, etc. Examples 
of carboxylic acids represented by Formula IIB include methyl maleate, 
ethyl maleate, propyl maleate, butyl maleate, hexyl maleate, methyl 
itaconate, ethyl itaconate, methyl mesaconate, ethyl mesaconate, methyl 
glutaconate, ethyl glutaconate, etc. 
(C) Hydroxy-Containing Compound 
The third component utilized in the preparation of the polymer compositions 
is at least one hydroxy-containing compound. In one embodiment, the 
hydroxy-containing compound is at least one hydroxyalkyl acryl 
EQU CH.sub.2 .dbd.C(R)C(O)OR.sup.2 OH (III) 
wherein R is hydrogen or a lower alkyl group and R.sup.2 is an alkylene 
group. Generally, the alkylene group will be a lower alkylene group, and 
more particularly is an alkylene group containing from 1 to about 4 carbon 
atoms. In one preferred embodiment, R is a methyl or ethyl group. 
Examples of hydroxyalkyl acrylates useful as component (C) include: 
2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl 
acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 
2-hydroxybutyl methacrylate, 2-hydroxyethyl ethacrylate, 2-hydroxypropyl 
ethacrylate, etc. 
In another embodiment, the hydroxy-containing compound contains an --SH 
group in addition to the --OH group and may be represented by the formula 
EQU HOR*SH (IIIA) 
wherein R* is a hydrocarbyl group containing from 2 to about 10 carbon 
atoms, and the --OH and --SH groups are on different carbon atoms. The 
hydrocarbyl group may also include other atoms or groups such as 
carboxylic ester groups. Compounds represented by Formula IIIA are 
generally known in the art as chain-transfer agents. 
Examples of hydroxy-containing compounds, as represented by Formula IIIA 
include: 2-mercaptoethanol, 1-mercapto-2-propanol, 3-mercapto-1-propanol, 
3-mercapto-2-butanol, 2-hydroxyethyl-3-mercaptopropionate, etc. Mixtures 
of one or more hydroxyalkyl acrylate and one or more compounds of Formula 
IIIA can be utilized in the preparation of the polymers of the invention. 
The molar ratio of the components (A), (B) and (C) used to form the 
polymers may vary over a wide range. Generally, the amounts may be within 
the general and preferred ranges set forth in Table I. 
TABLE I 
______________________________________ 
General Range 
Preferred Range 
Component (mole %) (mole %) 
______________________________________ 
(A) 25-86 62-81 
(B) 10-50 14-26 
(C) 4-25 4-12 
______________________________________ 
In one embodiment, the amount of carboxylic ester (B) included in the 
monomer mixture is an amount which is sufficient to provide a polymer 
having an acid value of from about 50 to about 150. The amount of 
hydroxyalkyl compound (C) included in the monomer mixture, in one 
embodiment is an amount sufficient to provide a polymer having a hydroxyl 
number of from about 20 to about 80. 
Examples of some of the polymers of the present invention include 
polymerization products of the following mixtures: 
______________________________________ 
A B C 
______________________________________ 
styrene acrylic acid 2-hydroxyethyl 
acrylate 
ethyl acrylate 
acrylic acid 2-hydroxyethyl 
acrylate 
butyl acrylate 
acrylic acid 2-hydroxypropyl 
methacrylate 
lauryl meth- 
monobutyl maleate 
2-hydroxyethyl 
acrylate methacrylate 
butyl acrylate 
monoethyl maleate 
2-hydroxypropyl 
ethacrylate 
butyl acrylate 
methacrylic acid 
2-hydroxybutyl 
methacrylate 
butyl acrylate 
monobutyl itaconate 
2-hydroxyethyl 
methacrylate 
methyl meth- 
ethyl mesaconate 
2-hydroxypropyl 
acrylate methacrylate 
butyl acrylate 
butyl maleate 2-mercaptoethanol 
______________________________________ 
The preparation of the polymer compositions generally is effected in the 
presence of solvents including hydrocarbons, ketones, alcohols, esters, 
etc. Specific examples include toluene, ethyl acetate, mineral spirits, 
aromatic naphtha, acetone, methylisobutyl ketone, methylethyl ketone, 
ethyl alcohol, ethylene glycol monoether acetate, butoxyethanol, etc. 
A polymerization catalyst generally is included in the mixtures used to 
form the desired polymers. About 0.1 to about 2% by weight or more, based 
on the combined weight of the monomers, of a polymerization catalyst is 
used to prepare the polymers. Any of the catalysts known in the art for 
polymerizing acrylic and vinyl monomers can be utilized in preparing the 
acrylic and vinyl polymers of the present invention. Typical catalysts 
include azo-bis-isobutyronitrile, benzoyl peroxide, acetyl peroxide, 
dicumyl peroxide, cumene hydroperoxide, ethyl 3,3-di(t-amylperoxy) 
butyrate, etc. Mixtures of such catalysts also can be used.

The following examples illustrate the preparation of acrylic polymer 
compositions of the present invention. Unless otherwise indicated, all 
parts and percentages are by weight, all temperatures are in degrees 
centigrade, and all pressures are at or near atmospheric. The viscosities 
are reported on the Gardner-Bubble (GB) scale (25.degree. C.). 
EXAMPLE 1 
Into a resin reaction flask equipped with an agitator, a condenser, a 
thermometer and an inert gas inlet, there are charged 817 parts of 
butoxyethanol which is heated to 116.degree. C. A premix of 317.3 parts of 
acrylic acid, 1467.6 of butyl acrylate, 198.4 parts of 2-hydroxyethyl 
methacrylate, and 39.3 parts of Vazo 64 
(2,2'-azobis(2-methylpropanenitrile) is added over a 3-hour period while 
maintaining the reaction temperature at 106.degree.-122.degree. C. After 
the addition is complete, the solution is held at 109.degree.-111.degree. 
C. for one hour. There is then added 0.3 part of Vazo 64 and 50 parts of 
butoxyethanol, and the reaction mixture maintained at 
110.degree.-116.degree. C. for 30 minutes to complete the polymerization. 
The polymer solution obtained in this manner contains 69.9% solids and has 
an acid value of 112.6, a viscosity of Z3-Z4, and a Gardner color rating 
of 1-2. 
EXAMPLE 2 
To a resin reaction flask as described in Example 1, there are added 285.8 
parts of maleic anhydride, 237.6 parts of 1-butanol and 725.6 parts of 
Aromatic Naphtha 100. The mixture is heated to about 100.degree. C., and 
the ensuing exotherm raises the temperature of the mixture to about 
129.degree. C. Heat is then applied to raise the reaction mixture to 
140.degree. C. where it is maintained for 20 minutes to complete the 
formation of monobutyl maleate. 
To the reaction vessel there is added simultaneously, 36.9 parts of 
2-mercaptoethanol and a premix consisting of 1052.2 parts of butyl 
acrylate, 127.1 parts of 2-hydroxyethyl methacrylate, 129.3 parts of 
lauryl methacrylate and 36.9 parts of dicumyl peroxide over a 3-hour 
period while maintaining the reaction temperature at 
135.degree.-145.degree. C. After the additions are complete, the solution 
is maintained at about 137.degree. C. for 20 minutes whereupon 12.3 parts 
of ethyl 3,3-di(t-amyl-peroxy) butyrate are added and the temperature is 
maintained at about 132.degree.-139.degree. C. to complete the 
polymerization. An additional 47.8 parts of Aromatic Naphtha 100 are 
added. The resulting polymer solution contains 69.4% solids and has an 
acid value of 80.7, a viscosity of T-U and a Gardner color of less than 1. 
EXAMPLES 3-8 
The general procedure of Example 1 is repeated using the reactants and 
amounts (mole percent) specified in the following Table II. 
TABLE II 
______________________________________ 
Reactant/Example 
3 4 5 6 7 8 
______________________________________ 
butyl acrylate 
70.0 65.9 71.4 59.7 62.8 63.2 
lauryl methacrylate 
-- -- -- 4.6 2.3 -- 
stearyl methacry- 
-- -- -- -- -- 1.8 
late 
acrylic acid 
25.2 25.3 19.6 26.5 25.9 26.0 
hydroxyethyl acry- 
4.8 -- -- -- -- -- 
late 
hydroxyethyl metha- 
-- 8.8 9.0 9.2 9.0 9.0 
crylate 
______________________________________ 
EXAMPLES 9-16 
The general procedure of Example 2 is repeated using the reactants and 
amounts (mole percent) specified in the following Table III. 
TABLE III 
______________________________________ 
Reactant/ 
Example 9 10 11 12 13 14 15 16 
______________________________________ 
butyl acrylate 
60.8 58.8 70.8 71.4 67.0 59.9 62.4 60.6 
lauryl metha- 
-- 4.1 3.9 -- -- 3.9 3.9 3.9 
crylate 
stearyl -- -- -- 3.0 6.1 -- -- -- 
methacrylate 
styrene 9.1 -- -- -- -- -- -- -- 
butyl maleate 
23.8 26.0 14.6 14.8 15.5 25.1 22.5 24.9 
hydroxyethyl 
6.3 11.1 10.7 10.8 11.4 7.5 7.6 -- 
methacrylate 
2-mercapto- 
-- -- -- -- -- 3.6 3.6 10.6 
ethanol 
______________________________________ 
The polymer compositions described above are useful as leveling agents and 
flow modifiers for coating resins, including thermoplastic and 
thermosetting resins such as polyester resins, alkyd resins, acrylic 
resins, polyurethane resins, vinyl resins, melamine resins, epoxy resins 
and phenolic resins. The polymer compositions are particularly useful in 
polyester resins and alkyd resins. Sufficient amounts of the polymer 
compositions should be incorporated into the coating formulation to 
improve the flow properties of the resins and to provide the desired 
properties in the coating, particularly, resistance to staining and 
recoatability. In general, the coating compositions will contain from 
about 0.1% to about 3% by weight of the polymer compositions. In a 
preferred embodiment, the coating compositions will contain from about 
0.1% to about 2% by weight of the polymer. 
The polyester resins that can be utilized in the present invention may be 
either saturated or unsaturated polyester resins formed by condensing a 
polycarboxylic acid or anhydride (either saturated or unsaturated) with at 
least one polyhydric alcohol. Illustrative of these polyester resins are 
the products of the reaction of a saturated dicarboxylic acid or anhydride 
such as phthalic acid or anhydride, isophthalic acid, tetrahydrophthalic 
anhydride, hexahydrophthalic anhydride, succinic acid, glutaric acid, 
adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, 
and an unsaturated dicarboxylic acid or anhydride such as maleic 
anhydride, fumaric anhydride, chloromaleic acid, itaconic acid, citraconic 
acid and mesaconic acid with a dihydric alcohol such as ethylene glycol, 
propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, 
and neopentyl glycol. Small amounts of a polyhydric alcohol such as 
glycerol, pentaerythritol, trimethylolpropane, or sorbitol may be used in 
combination with the glycol. 
Alkyd resins are the polymerization products of polyhydric alcohols and 
polybasic acids modified with monobasic fatty acids. Non-oil or oil-free 
alkyds, best described as saturated or hydroxylated reactive polyesters, 
are formed by the reaction of polybasic acids with excess polyhydric 
alcohols. 
Alkyd resins generally are classified by alkyd ratio or polyhydric 
alcohol:phthalate ratio, oil length or percent oil for alkyds containing 
glycerol as the only polyol, and percent phthalic anhydride. Alkyds are 
roughly classified into four main types: short (30-42% fatty acid content, 
38-46% phthalic anhydride content); medium (43-54% fatty acid content, 
30-37% phthalic anhydride content); long (55-68% fatty acid content, 
20-30% phthalic anhydride content); and very long (&gt;68% fatty acid 
content, &lt;20% phthalic anhydride content). The percentage of fatty acid 
content influences the properties of alkyd resins. 
Among the polyhydric alcohols which can be used to prepare alkyd resins, 
glycerol is the most widely used followed by pentaerythritol. Polyols such 
as sorbitol and diethylene glycol also have been used. 
Phthalic acid and isophthalic acid have been the most widely used polybasic 
acids in the preparation of alkyd resins. 
In one embodiment, the alkyd resin and polyester resin formulations used in 
the present invention will also contain an unsaturated monomer capable of 
reacting with the alkyd resin or unsaturated polyester resin to form 
cross-linkages. The unsaturated monomers include vinyl or acrylate 
monomers, and these are incorporated into the formulations as reactive 
diluents. Suitable unsaturated monomers include styrene, methyl styrene, 
dimethyl styrene, vinyl toluene, divinyl benzene, dichloro styrene, methyl 
acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, 
diallylphthalate, vinyl acetate, acrylonitrile, acrylamide, vinyl 
chloride, vinylidine chloride, vinyl formate, vinyl acetate, vinyl 
butyrate, vinyl stearate, etc. Mixtures of such monomers such as methyl 
methacrylate and butyl acrylate, styrene and ethyl or butyl acrylate, or 
acrylonitrile and ethyl acrylate also may be utilized. 
The alkyd and polyester resin formulations which are modified with one or 
more of the above unsaturated monomers may contain from about 20% to about 
80% by weight of non-volatile material. 
The coating resins utilized in the compositions of the present invention 
may be derived from at least one curable acrylic resin derived from 
acrylic acid, methacrylic acid, or esters of acrylic acid or methacrylic 
acid by techniques well known to those skilled in the art. Most acrylics 
are based on methyl methacrylate monomer which can be produced in a 
two-step process where acetone is reacted with hydrogen cyanide to form 
acetone cyanohydrin, and this intermediate is heated with methanol in the 
presence of an acid such as sulfuric acid to produce methyl methacrylate 
monomer. The acrylic resins may comprise homopolymers or copolymers of 
methyl methacrylate with other acrylates such as methyl or ethyl acrylate. 
The acrylic resins can be modified with various ingredients including 
butadiene, vinyl, and butyl acrylate to improve certain properties. Vinyl 
resins such as those derived from vinyl acetate, vinyl halides, etc., also 
can be utilized in the compositions of the present invention. 
Examples of other thermosetting resins which can be utilized include 
polyurethane resins, melamine resins, epoxy resins, and phenolic resins. 
The epoxy resins contain a reactive functional group (oxirane ring) in 
their molecular structure. The epoxy resins utilized in the present 
invention may be any one of a number of well known resins, and many of 
these are available commercially from a variety of sources. As used in 
this specification and in the appended claims, the term "epoxy resin" is 
intended to describe the reaction products of the condensation reaction of 
an epihalohydrin and a hydroxy-containing compound or carboxylic acid. 
Thus, the epoxy resins may be of the ether or ester types. 
Examples of ester-type epoxy resins include polyglycidyl esters obtained by 
the reaction of a compound containing two or more carboxylic acid groups 
per molecule with epichlorohydrin or glycerol dichlorohydrin in the 
presence of an alkali. Such polyglycidyl esters may be derived from 
aliphatic polycarboxylic acids, e.g., succinic acid, glutaric acid, adipic 
acid, pimelic acid, etc.; from cycloaliphatic polycarboxylic acids such as 
tetrahydrophthalic acid; and from aromatic polycarboxylic acids such as 
phthalic acid, isophthalic acid, and terephthalic acid. 
Ether-type epoxy resins are obtained by the reaction of a compound 
containing at least two free alcoholic hydroxyl and/or phenolic hydroxyl 
groups per molecule with an epihalohydrin under alkaline conditions, or in 
the alternative, in the presence of an acidic catalyst with subsequent 
treatment with an alkali. The products of such reactions are generally 
complex mixtures of glycidyl polyethers. These ethers may be made from 
acyclic alcohols such as ethylene glycol, diethylene glycol, 
propane-1,2-diol, hexane-2,4,6-triol, glycerol, etc.; from cycloaliphatic 
alcohols such as bis(4-hydroxycyclohexyl) methane; and some alcohols 
having aromatic nuclei such as N,N-bis(2-hydroxyethyl) aniline, and 
p,p'-bis(2-hydroxyethylamino) diphenylmethane. The epoxy resins also may 
be derived from mononuclear phenols such as resorcinol or from polynuclear 
phenols such as bis(4-hydroxyphenyl) methane (otherwise known as bisphenol 
F), 4,4'-dihydroxydiphenyl, 2,2-bis(4-hydroxyphenyl) propane (otherwise 
known as bisphenol A), and 2,2-bis(3,5-dibromo-4-hydroxyphenyl) propane. 
The most widely used epoxy resins are diglycidyl ethers of bisphenols, 
especially bisphenol A. These are made by reacting epichlorohydrin with 
bisphenol A in the presence of an alkaline catalyst. By controlling the 
operating conditions and varying the ratio of epichlorohydrin to bisphenol 
A, products of different molecular weight can be made. Other usable epoxy 
resins include the diglycidyl ethers of other bisphenol compounds such as 
bisphenol B, F, G and H. 
Epoxy resins of the type described above based on various bisphenols are 
available from a variety of commercial sources. One group is known by the 
general trade designation "Epon" resins and are available from Shell 
Chemical Company. Another group of commercially available epoxy resins is 
identified under the general trade designation EPI-REZ from Celanese 
Resins, a division of Celanese Coatings Company. 
The coating formulations of the present invention also may contain phenolic 
resins. Phenolic resins are the reaction products of phenol and 
formaldehyde. Polyurethanes sometimes referred to as urethanes, are also 
useful as coating resins. The polyurethanes generally are formed by the 
reaction of a polyisocyanate and a polyol. By varying the combinations of 
polyisocyanates and polyols, polyurethanes having a variety of desirable 
properties can be obtained. Two types of polyisocyanates are predominantly 
used to make polyurethanes, and these are diphenylmethanediisocyanate 
monomer (MDI) and its derivatives, and toluene diisocyanate (TDI) and its 
derivatives. The polyols most often used in the formation of polyurethanes 
are polyester polyols and polyether polyols. 
Amino resins also can be utilized and these include, in particular, urea 
resins and melamine formaldehyde resins. Both urea and melamine can react 
with formaldehyde to initially form monomeric addition products. For 
example, a single molecule of urea readily combines with two molecules of 
formaldehyde to form dimethylol urea. As many as six molecules of formalde 
can add to a melamine molecule to form hexylmethylol melamine. These 
methylolated species can further condense in the presence of an acid 
catalyst to produce methylene or methylene ether linkages. Further 
condensation results in the formation of a variety of resins, and the 
particular resin characteristics can be obtained by control of pH, 
reaction temperature, reactant ratio, amino monomer and a degree of 
polymerization. The liquid coating resins commonly are prepared by 
reacting methanol or butanol with the initial methylolated products. These 
methylated and butylated resins can then be used to produce hard, 
solvent-resistant coatings by heating with hydroxyl, carboxyl and amide 
functional polymers. 
In addition to the polymer compositions of the present invention, the 
coating formulations may also contain pigments, solvents, surface-active 
agents, bodying agents, extender pigments, plasticizing agents, etc., as 
is well known in the art. 
The pigments utilized in the coating compositions include any of the known 
organic and inorganic pigments, whether natural or synthetic. Examples of 
organic pigments include the azo-insoluble pigments such as toluidines, 
naphtol reds, benzidines and dinitraniline orange; the acid azo pigments 
such as lithol, Persian orange and tartrazine; the phthalocyanine pigments 
such as phthalocyanine blues and greens; and the basic PNA and PTA 
pigments such as rhodamine, malachite green, methyl violet and victoria 
blue. Examples of inorganic pigments include metal flakes; the natural red 
oxide pigments; chromates such as lead chromate; zinc sulfide pigments 
such as zinc sulfide, lithopone, etc.; zinc oxide; antimony oxide; 
titanium pigments such as titanium dioxide, tinted titanium pigments; 
titanates such as barium, zinc, lead and magnesium titanate; pearlescent 
pigments such as mica which has been plated with a coating of titanium 
dioxide or iorn oxide, etc. All of these pigments are discussed in detail 
in Vol. II of Organic Coating Technology, "Pigments and Pigmented 
Coatings" by Henry F. Payne, John Wiley & Sons, Inc., New York, 1961. The 
ratio of pigment to resin in the coating composition will depend upon the 
usual factors considered in coating chemistry when determining such 
ratios. For example, the ratio is experimentally determined taking into 
consideration such desired properties as hiding power, cover, shade, 
flexibility, mechanical strength, consistency and flow properties. 
Examples of surface-active agents can be utilized in the coating 
compositions of the invention include such materials as oleic and other 
organic acids; lecithin; hydrogenated castor oil; aluminum and calcium 
stearates; silicone oils; and pine oil. Bodying agents may be included to 
increase the consistency of the paint by producing a thixotropic 
condition. Metallic soaps have been used widely as bodying and 
anti-settling agents, and examples include the aluminum, zinc, magnesium, 
calcium and lead stearates. 
Extender pigments are much lower in price than the prime pigments that are 
used in paints to reduce the cost and improve properties such as 
consistency, leveling and pigment settling. Extender pigments are obtained 
either by pulverizing certain rocks and sedimentary deposits, or by 
chemical precipitation. Aluminum silicates have been found to be 
particularly useful as extender pigments. Examples of plasticizing agents 
which may be included in the coating compositions include glycerine, 
glycerol, triphenyl phosphate, dibutyl phthalate, and dioctyl phthalate. 
Cross-linking agents can be included in the coating compositions. For 
example, small amounts of alkylated melamine formaldehyde resin can be 
included in the coating compositions. The alkyl group contains from 1 to 4 
carbon atoms, and the resin can be prepared by conventional techniques in 
which an alcohol such as methanol, ethanol, butanol, isobutanol, etc., is 
reacted with a melamine formaldehyde resin. The resin can be monomeric or 
polymeric. One preferred resin which results in a high quality finish is 
hexamethoxymethyl melamine which is available commercially as "Cymel 303" 
from American Cyanamid. Another example is a methoxybutoxymethyl melamine. 
About 1 to about 30% by weight of the cross-linking agent, based on the 
weight of polymer, can be included in the coating compositions. 
The following examples illustrate coating compositions of the present 
invention. 
EXAMPLE A 
A coating composition is prepared by dispersing 33.15 parts of titanium 
dioxide in 17.82 parts of a polyester resin solution (65% solids) and 7.24 
parts of butoxyethoxyethanol. The dispersion is let down with 22.7 parts 
of the same polyester resin solution, 4.25 parts of hexamethoxymethyl 
melamine (Cymel 303), 0.5 part of the acrylic polymer of Example 1, 3.10 
grams of butoxyethoxyethyl acetate, 2.1 parts of 2-ethylhexanol, 8.8 parts 
of 100/aromatic solvent, 0.14 part of p-toluene sulfonic acid and 0.2 part 
of petroleum wax. 
EXAMPLE B 
A coating composition as prepared in accordance with the formulation of 
Example A except that 0.5 part of the acrylic polymer of Example 2 is 
utilized in lieu of the product of Example 1. 
The coating compositions of this invention can be applied over a variety of 
substrates such as metal, wood, glass, plastics, and the like, by any of 
the conventional application methods such as by spraying, electrostatic 
spraying, dipping, brushing, flow-coating, roller coating, etc. The 
viscosity of the coating composition can be adjusted for any one of these 
methods by adding solvents if necessary. 
The coatings are cured by baking at temperatures of from about 
150.degree.-250.degree. C. for periods of from about 10 seconds up to 
about 4 or 5 minutes or more. Coating thicknesses from about 0.5 to about 
5 mils are usually satisfactory. 
The utility of the coating compositions of the present invention, and any 
of the improvements obtained are illustrated in the following example. 
The coating composition prepared in Example A is applied to aluminum panels 
to yield 0.7 to 0.9 mil dry films and the films are cured by baking for 30 
to 35 seconds at 215.degree.-232.degree. C. The resulting films are 
glossy, solvent-resistant and flexible. The films resist staining by a 
variety of materials and are recoatable. 
While the invention has been explained in relation to its preferred 
embodiments, it is to be understood that various modifications thereof 
will become apparent to those skilled in the art upon reading the 
specification. Therefore, it is to be understood that the invention 
disclosed herein is intended to cover such modifications as fall within 
the scope of the appended claims.