Low energy-curable high solids coatings

High solids, low energy curing compositions of (1) a carboxyl-modified polycaprolactone polyol which is the reaction product of a polycaprolactone polyol and an intramolecular carboxylic acid anhydride, (2) a monocarboxylic acid compound, (3) a stannous salt and (4) a polyepoxide. The compositions are useful as inks or coatings.

BACKGROUND OF THE INVENTION 
Government regulations have placed ever increasing restrictions on the 
amounts and types of organic volatiles permitted to escape into the 
atmosphere from coatings compositions. Considerable efforts have been 
expended to develop coatings compositions having a minimal amount of 
volatile organic components; and this had led to development of powder 
coatings, radiation-curable coatings, water-borne coatings, and high solid 
coatings. In these recent developments, the amounts of organic solvents 
present are minimal; consequently, there is little or no atmospheric 
pollution. 
In the field of solvent coatings, efforts have been made to reduce the 
amount of volatile solvent present and to increase the amount of reactive 
components that will react to produce the coatings on the substrate. At a 
sufficiently high concentration of such components, one has what is known 
as a high solids coating composition. These are compositions that are 
applied in liquid form and dry to acceptable films without the evaporation 
of substantial quantities of solvents. Such compositions are described, 
for example, in U.S. Pat. No. 4,086,293 and in U.S. Pat. No. 4,119,593. 
U.S. Pat. No. 4,086,293 describes compositions of a polyepoxide, a 
stannous salt and a carboxyl-modified polycaprolactone polyol which is the 
reaction product of polycaprolactone polyol with an intramolecular 
carboxylic acid anhydride; U.S. Pat. No. 4,119,593 describes compositions 
of a polyepoxide, a stannous salt and a monocarboxylic acid compound. 
The major factors which have led to the development of high solids 
coatings, i.e. the deleterious effects of organic solvent in the 
atmosphere and the high cost of energy needed to drive off the solvent, 
have become even more pronounced. Consequently there is a continuing need 
for high solids compositions which require less energy to cure and result 
in less air pollution than heretofore known high solids compositions. One 
way of accomplishing these ends is to increase the amount of solids 
content in the compositions. Therefore a high solids composition having a 
higher solids content than the composition heretofore available, which is 
easily applicable to a substrate and which cures to a good satisfactory 
dry film would be of great importance. 
SUMMARY OF THE INVENTION 
It has now been found that the combination of a polyepoxide, a stannous 
salt, certain monocarboxylic acid compounds and a carboxyl-modified 
polycaprolactone polyol which is the reaction product of a 
polycaprolactone polyol with an intramolecular carboxylic acid anhydride, 
all as hereinafter more fully described will produce high solids 
compositions having a higher solids contents than heretofore known high 
solids compositions and cure rapidly and efficiently with the use of less 
energy. 
DESCRIPTION OF THE INVENTION 
The carboxyl-modified polycaprolactone polyol adducts that are blended with 
the polyepoxides, the stannous salts and the monofunctional carboxylic 
acids to produce the compositions of this invention are the adducts 
comprising the reaction product mixture of a polycaprolactone polyol and 
an intramolecular anhydride of a polycarboxylic acid. As starting 
materials for producing the adducts one can use any of the known 
polycaprolactone polyols that are commercially available and that are 
fully described, for example, in U.S. Pat. No. 3,169,945. As described in 
this patent the polycaprolactone polyols are produced by the catalytic 
polymerization of a excess of a caprolactone and an organic polyfunctional 
initiator having at least two reactive hydrogen atoms. The polyols for use 
herein can be single compounds or mixtures of compounds and either can be 
used. The method for producing the polycaprolactone polyols is of no 
consequence and the organic functional initiators can be any polyhydroxyl 
compound as is shown in U.S. Pat. No. 3,169,945. Illustrative thereof are 
the diols such as ethylene glycol, diethylene glycol, triethylene glycol, 
1,2-propylene glycol, dipropylene glycol, 1,3-propylene glycol, 
polyethylene glycol, polypropylene glycol, poly(oxyethylene-oxypropylene) 
glycol, and similar polyalkylene glycols, either blocked, capped or 
heteric, containing up to about 40 or more alkyleneoxy units in the 
molecule, 3-methyl-1,5-pentanediol, cyclohexanediol, 
4,4'-methylene-bis-cyclohexanol, 4,4'-isopropylidene-bis-cyclohexanol, 
xylenediol, 2-(4-hydroxymethylphenyl)ethanol, 1,4-butanediol, and the 
like; triols such as glycerol, trimethylolpropane, 1,2,6-hexanetriol, 
triethanolamine, triisopropanolamine, and the like; tetrols such as 
erythritol, pentaerythritol, N,N,N',N'-tetrakis(2-hydroxyethyl)ethylene 
diamine, and the like. 
When the organic functional initiator is reacted with the caprolactone a 
reaction occurs that can be represented in its simplest form by the 
equation: 
##STR1## 
In this equation the organic functional initiator is the R"(OH).sub.x 
compound and the caprolactone is the 
##STR2## 
compound; this can be caprolactone itself or a substituted caprolactone 
wherein R' is an alkyl, alkoxy, aryl, cycloalkyl, alkaryl or aralkyl group 
having up to twelve carbon atoms and wherein at least six of the R' groups 
are hydrogen atoms, as shown in U.S. Pat. No. 3,169,945. The 
polycaprolactone polyols that are used are shown by the formula on the 
right hand side of the equation; they can have an average molecular weight 
of from 290 to about 6,000. The preferred polycaprolactone polyol 
compounds are those having an average molecular weight of from about 290 
to about 3,000, preferably from about 300 to about 1,000. The most 
preferred are the polycaprolactone compounds having an average molecular 
of from about 375 to about 500 since they yield derivatives which impart 
good flexibility and hardness to the coating compositions of this 
invention. In the formula m is an integer representing the average number 
of repeating units needed to produce the compound having said molecular 
weights. The hydroxyl number of the polycaprolactone polyol can be from 15 
to 600, preferably from 220 to 500; and the polycaprolactone polyol can 
have from 2 to 6, preferably 2 to 4 hydroxyl groups. 
Illustrative of polycaprolactone polyols that can be used as starting 
materials in the production of the polycaprolactone derivatives used in 
the blend of this invention one can mention the reaction products of a 
polyhydroxyl compound having from 2 to 6 hydroxyl groups with 
caprolactone. The manner in which these polycaprolactone polyol 
compositions are produced is shown in U.S. Pat. No. 3,169,945 and many 
such compositions are commercially available. In the following table there 
are listed illustrative polycaprolactone polyols. The first column lists 
the organic functional initiator that is reacted with the caprolactone and 
the average molecular weight of the polycaprolactone polyol is shown in 
the second column. Knowing the molecular weights of the initiator and of 
the polycaprolactone polyol one can readily determine the average number 
of molecules of caprolactone (CPL Units) that reacted to produce the 
compound; this figure is shown in the third column. 
______________________________________ 
POLYCAPROLACTONE POLYOLS 
Average No. 
Average MW of CPL Units 
Initiator of polyol in molecules 
______________________________________ 
1 Ethylene glycol 290 2 
2 Ethylene glycol 803 6.5 
3 Ethylene glycol 2,114 18 
4 Propylene glycol 
874 7 
5 Octylene glycol 602 4 
6 Decalene glycol 801 5.5 
7 Diethylene glycol 
527 3.7 
8 Diethylene glycol 
847 6.5 
9 Diethylene glycol 
1,246 10 
10 Diethylene glycol 
1,998 16.6 
11 Diethylene glycol 
3,526 30 
12 Triethylene glycol 
754 5.3 
13 Polyethylene glycol (MW 200)* 
713 4.5 
14 Polyethylene glycol (MW 600)* 
1,396 7 
15 Polyethylene glycol (MW 1500)* 
2,868 12 
16 1,2-Propylene glycol 
646 5 
17 1,3-Propylene glycol 
988 8 
18 Dipropylene glycol 
476 3 
19 Polypropylene glycol (MW 425)* 
824 3.6 
20 Polypropylene glycol 
(MW 1000)* 1,684 6 
21 Polypropylene glycol 
(MW 2000)* 2,456 4 
22 Hexylene glycol 916 7 
23 2-Ethyl-1,3-hexanediol 
602 4 
24 1,5-Pentanediol 446 3 
25 1,4-Cyclohexanediol 
629 4.5 
26 1,3-Bis(hydroxyethyl)-benzene 
736 5 
27 Glycerol 548 4 
28 1,2,6-Hexanetriol 
476 3 
29 Trimethylolpropane 
590 4 
30 Trimethylolpropane 
761 5.4 
31 Trimethylolpropane 
1,103 8.5 
32 Triethanolamine 890 6.5 
33 Erythritol 920 7 
34 Pentaerythritol 1,219 9.5 
______________________________________ 
*Average molecular weight of glycol. 
The structures of the compounds in the above tabulation are obvious to one 
skilled in the art based on the information given. The structure of 
compound No. 7 is: 
##STR3## 
wherein the variable r is an integer, the sum of r+r has an average value 
of 3.7 and the average molecular weight is 527. The structure of compound 
No. 20 is: 
##STR4## 
wherein the sum of r+r has an average value of 6 and the average molecular 
weight is 1,684. This explanation makes explicit the structural formulas 
of compounds 1 to 34 set forth above. 
The polycaprolactone polyol is reacted with a polycarboxylic acid anhydride 
and illustrative thereof one can mention trimellitic anhydride, 
tetrahydrophthalic anhydride, phthalic anhydride, benzophenone 
dicarboxylic acid anhydride, succinic anhydride, maleic anhydride, 
naphthoic anhydride, glutaric anhydride, or any other intramolecular 
anhydride, including those having substituents thereon such as halogen 
atoms, alkyl or alkoxy groups, nitro, carboxyl, aryl, or any other group 
which will not unduly interfere with the reaction. 
The amount of polycarboxylic acid anhydride reacted with the 
polycaprolactone polyol can be an amount sufficient to react with all of 
the hydroxyl groups present in the polycaprolactone polyol. This amount 
will vary and can be from 0.5 to 1 anhydride equivalent for each hydroxyl 
equivalent or group present in the polycaprolactone polyol initially 
charged to the reaction mixture. Preferably from 0.85 to 0.95 anhydride 
equivalent per hydroxyl equivalent is used, with the most preferred ratio 
being 0.9 anhydride equivalent per hydroxyl equivalent. It is preferred 
not to have any free anhydride present in the adduct reation mixture as it 
presents problems in the formulations of this invention due to its 
insolubility. 
The polycaprolactone polyols are reacted with the polycarboxylic acid 
anhydride with or without a solvent present at a temperature of about 
75.degree. to 200.degree. C., preferably about 100.degree. to 140.degree. 
C. The time required for reaction will vary depending upon the particular 
reactants charged and the batch size of the reaction mixture, facts which 
are well known to those skilled in the art. Generally it has been found 
that a reaction period of the laboratory of from 15 to 45 minutes at from 
about 125.degree. to 175.degree. C. is adequate to produce the initial 
water insoluble carboxyl modified oligomer addition reaction product 
mixture obtained by the reaction of these two intermediates. 
The adduct formed at this stage of the reaction is a viscous liquid in most 
instances. However, in some instances it has been observed that the 
product will solidify upon standing at room temperature for an extended 
period of time. This, however, does not detract from its further utility. 
Generally these modified oligomers or adducts are solvent soluble. 
One can also modify the reaction by inclusion and reaction of an organic 
polyisocyanate to react with a portion of the hydroxyl groups prior to 
reaction with the anhydride, as is shown in Example 3 hereinafter. In such 
instances any of the known polyisocyanates can be used such as tolylene 
diisocyanate, 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethycyclohexane, 
4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, 
dicyclohexyl-4,4'-methane diisocyanate, and polymethylene 
polyphenolisocyanates, and the like. 
In a typical reaction, one normally charges a polycaprolactone polyol and a 
polycarboxylic acid anhydride to a reaction vessel and heats the mixture 
to a temperature of from about 125.degree. C. to 175.degree. C. for a 
period of about 20 to 30 minutes. This produces the carboxyl modified 
polycaprolactone oligomer or adduct. 
The monofunctional carboxylic acid compounds can be represented by the 
general formula 
EQU HOOC--R--(COOR'").sub.x 
wherein x is an integer having a value of from 0 to 2, preferably 0 or 1; 
when x is 0, R can be a phenyl group or an alkyl group having from 6 to 24 
carbon atoms, preferably 12 to 18 carbon atoms; when x is 1, R can be a 
--CH.dbd.CH-- group; when x is 1 or 2, R can be a polyvalent alkylene 
having from 1 to 12 carbon atoms, preferably 2 to 6 carbon atoms, or a 
polyvalent phenylene group, or a polyvalent naphthylene group; R'" is an 
alkyl group having from 1 to 8 carbon atoms, preferably 1 to 3 carbon 
atoms, --C.sub.n H.sub.2n (OC.sub.n H.sub.2n).sub.m OC.sub.2p+1 group or a 
--C.sub.n H.sub.2n OOCCX.dbd.CH.sub.2 group; n is 2 to 4, preferably 2, m 
is 0 to 10, preferably 2 to 7; p is 1 to 15 and X is hydrogen or methyl. 
The monofunctional carboxylic acid compounds can be unsubstituted or they 
can be substituted with any group which will not interfere with the 
reaction or have an undesirable effect on the finished coating. 
Illustrative of suitable substituents are the halogens, nitro, alkoxy, 
alkyl, keto and the like. 
The most preferred monofunctional carboxylic acid compounds are those 
having a pK.sub.a value of less than 4. In addition, those that are liquid 
and readily miscible are more preferred than are the solid compounds which 
may present problems of uniform distribution in the composition. 
Illustrative of the monofunctional carboxylic acid compounds when x is 0 
one can name hexanoic acid, octanoic acid, caprylic acid, capric acid, 
hendacanoic acid, lauric acid, tridecanoic acid, pentadecanoic, stearic 
acid, arachidic acid, behenic acid, cerotic acid, 2-ethylhexanoic acid, 
9-methyldecanoic acid, benzoic acid, naphthoic acid, myristic acid, 
palmitic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic 
acid, olestearic acid, licanic acid, ricinoleic acid, hexenoic acid, 
hexadienoic acid, and the like. It is advantageous for purposes of economy 
to employ mixtures of acids, particularly those derived from natural 
sources such as linseed oil, castor oil, dehydrated castor oil, coconut 
oil, cotton seed oil, oiticaca oil, perilla oil, palm oil, olive oil, 
safflower oil, sardine oil, soybean oil, tung oil, tall oil, and the like. 
When x is 1 or 2, the monufunctional carboxylic acid compounds are the 
partial esters (having a free carboxyl group) of di- or tri-carboxylic 
acids or the anhydrides thereof. These partial esters are known to those 
skilled in the art, as are the methods by which they are produced. 
Illustrative thereof are the partial esters of the following acids: 
oxalic, malonic, succinic, glutaric, adipic, suberic, azelaic, sebacic, 
brassylic, maleic, fumaric, itaconic, phthalic, isophthalic, terephthalic, 
trimellitic, tartaric, malic, 1,2-cyclohexanedicarboxylic 
1,4-cyclohexanedicarboxylic, tetrahydrophthalic, tetrachlorophthalic, 
1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid, and the like. 
The polyepoxides that can be used in producing the high solids compositions 
of this invention are well known to those skilled in the art and are fully 
described in U.S. Pat. No. 3,027,357, U.S. Pat. No. 2,890,194, U.S. Pat. 
No. 2,890,197, U.S. Pat. No. 3,117,009, U.S. Pat. No. 3,031,434, U.S. Pat. 
No. 3,125,592 and U.S. Pat. No. 3,201,360. Of particular interest is that 
portion of U.S. Pat. No. 3,027,357 beginning at column 4, line 11 to 
column 7, line 38 and that portion of U.S. Pat. No. 3,201,360 beginning at 
column 2 line 60 to column 4, line 43, which portions are specifically 
incorporated herein by reference. Among some of the specific illustrative 
polyepoxides disclosed therein one can mention, 
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 
bis(3,4-epoxycyclohexylmethyl)adipate, vinyl cyclohexane dioxide, 
bis(2,3-epoxycyclopentyl)ether, epoxidized linseed oil, epoxidized soybean 
oil, methyl epoxy linseedate, butyl epoxy soyate, octyl epoxy linseedate, 
epoxidized polymers and copolymers of butadiene, polyglycidyl ethers of 
polyhydric phenols, and the like. 
The stannous salts are either the stannous acylates or stannous alkoxides. 
These can be substituted with hydroxyl, halogen, keto or other groups 
which do not deleteriously affect the reaction. 
The stannous acylates which are used as catalysts in this invention are the 
divalent tin salts of mono- and dicarboxylic acids which contain from 1 to 
54 carbon atoms. These can be salts of the saturated acids such as acetic 
acid, 2-ethylhexanoic acid, octanoic acid, 2-ethylhexanoic acid, ethyl 
acid phthalate, and the like, or of the unsaturated acids such as oleic 
acid, linoleic acid, eleostearic acid, ricinoleic acid, and the like. 
Illustrative of suitable stannous acylates one can name stannous acetate, 
stannous propionate, stannous oxalate, stannous butyrate, stannous 
tartrate, stannous valerate, stannous octanoate, stannous octoate, 
stannous stearate and stannous oleate. The preferred catalysts are 
stannous acetate, stannous octoate, stannous stearate and stannous oleate. 
The stannous alkoxides which are used as catalysts in this invention are 
the divalent tin salts of a saturated or unsaturated branched chain or 
straight chain alcohol containing from 1 to 18 carbon atoms, preferably 3 
to 12 carbon atoms. Representative examples of suitable stannous alkoxides 
include stannous methoxide, stannous isopropoxide, stannous butoxide, 
stannous t-butoxide, stannous 2-ethylhexoxide, stannous tridecanoxide, 
stannous heptadecanoxide, stannous phenoxide, the o-, m- and p-stannous 
cresoxides, and the like. 
The concentration of the polycaprolactone adduct in the compositions of 
this invention can be from 20 to 60 weight percent, preferably from 25 to 
40 weight percent based on the combined weight of said polycaprolactone 
adduct, monofunctional carboxylic acid compound, polyepoxide and stannous 
salt. 
The concentration of monofunctional carboxylic acid compound in the 
compositions of this invention can be from 5 to 50 weight percent, 
preferably from 10 to 30 weight percent, based on the combined weight of 
polycaprolactone adduct, monofunctional carboxylic acid compound, 
polyepoxide and stannous salt. 
The concentration of polyepoxide in the compositions of this invention can 
be from 30 to 90 weight percent, preferably from 40 to 70 weight percent 
based on the combined weight of polycaprolactone adduct, monofunctional 
carboxylic acid compound, polyepoxide and stannous salt. 
The concentration of stannous salt catalyst in the compositions of this 
invention can be from 0.1 to 10 weight percent, preferably from 0.5 to 2 
weight percent based on the combined weight of polycaprolactone adduct, 
monofunctional carboxylic acid compound, polyepoxide and stannous salt. 
The high solids curable compositions can also contain a minor amount of 
solvent, to assist in viscosity control. In such instances any of the 
known organic solvents can be used that are conventionally used in the 
coating and ink fields. 
In addition, other crosslinkers, such as urea-formaldehyde resins or 
melamine-formaldehyde resins, can also be present in small amounts. In 
such instances one can include a known catalyst for this crosslinking 
reaction. 
Combinations containing ethyl acid phthalate and reaction products formed 
by the reaction of a polycaprolactone polyol and an intramolecular 
anhydride of a polycarboxylic acid were found to be particularly effective 
initiators for the polymerization of epoxidized oils and cycloaliphatic 
epoxides in the presence of the stannous salts. Coatings containing 70 to 
90 percent solids by weight were typical. These coatings cured rapidly at 
temperatures of from 90.degree. C. to 120.degree. C. Combinations of 
epoxidized linseed oil, cycloaliphatic epoxides, ethyl acid phthalate, and 
stannous octanoate afforded coatings with a good balance of hardness, 
flexibility and solvent resistance. Combinations of an aromatic 
polyepoxide, the diglycidyl ether of bisphenol-A, ethyl acid phthalate, 
and stannous octanoate did not cure well at temperatures below 150.degree. 
C. However, when used in combination with epoxidized linseed oil or 
cycloaliphatic epoxides, the glycidyl ether of bisphenol-A did afford 
coatings with low energy cure responses indicating the beneficial 
influence of the aliphatic-type epoxides. 
When the monofunctional carboxylic acid compound is a phthalate half-acid, 
the initiation of epoxide homopolymerization occurs at 100.degree. C. as 
opposed to 150.degree. C. to 200.degree. C. when the acid is absent. By 
utilizing this technique, coatings can now be designed which minimize 
pollution and conserve energy. 
In the absence of any stannous salt catalyst in the high solids 
compositions of this invention, the pot-life of the composition can be as 
much as 10 hours or more. The presence of a catalyst tends to hasten the 
cure reaction, even at ambient temperature, and generally reduces the 
pot-life to up to about 5 hours. It was observed, however, that the 
presence of a tertiary amine in amount in excess of the equivalent amount 
of catalyst present for the reaction, served to extend the pot-life of the 
compositions of this invention; in some instances to as long as two days. 
In view of the pot-lives of the compositions, it is preferred to prepare 
the desired blend of polycaprolactone derivative and polyepoxide of this 
invention as it is needed. This is a common and accepted procedure in 
commercial practice today when reactive components are involved. The 
blends are produced by any of the known and practiced mixing procedures 
used by the ink and coating compositions industry. These procedures 
require no further description herein to enable one skilled in the art to 
produce our novel compositions. 
The high solids compositions of this invention can also contain colorants, 
pigments, dyes, fillers, fungicides, bactericides, flow control additives, 
antioxidants, UV-absorbing agents, or other additives conventionally added 
to coating and ink compositions, in their usual concentrations. 
The coating compositions are applied to a substrate by the known 
conventional methods. They are cured by heating at a temperature of about 
50.degree. C. to 150.degree. C., preferably from 55.degree. C. to 
95.degree. C. for a period of time sufficient to obtain a dry film. 
Generally, this time will range from about 1 to 30 minutes, preferably 
from 10 to 20 minutes. The components present in a particular coating 
composition used will control the temperature and time that will be 
required to obtain an adequate cure and a good film coating. 
The coatings compositions of this invention are high solids coatings 
compositions and they can contain as much as 100 weight percent solids 
therein. Generally the total solids content of the coatings compositions 
of this invention ranges from about 70 to 90 weight percent of the total 
weight of the composition. 
The novel high solids coatings compositions of this invention which contain 
both the carboxyl-modified polycaprolactone polyol adduct and a 
monofunctional carboxylic acid compound in addition to a stannous salt and 
a polyepoxide have a higher solids content, and are cured to dry films at 
lower temperatures that the known high solids coatings in which only the 
carboxyl-modified polycaprolactone polyol adduct or only the 
monofunctional carboxylic acid compound is present. This result was 
unexpected and is highly advantageous from both an air pollution and an 
energy usage standpoint. 
The coatings compositions were evaluated according to the following 
procedures: 
Solvent resistance is a measure of the resistance of the cured film to 
attack by acetone and is reported in the number of rubs or cycles of 
acetone soaked material required to remove one half of a film from the 
test area. The test is performed by stroking the film back and forth with 
an acetone soaked cheesecloth until that amount of film coating is 
removed. The number of cycles required to remove this amount of coating is 
a measure of the coating solvent resistance. 
Reverse impact measures the ability of a given film to resist rupture from 
a falling weight. A Gardner Impact Tester using an eight pound dart is 
used to test the films cast and cured on the steel panel. The dart is 
raised to a given height in inches and dropped on to the reverse side of a 
coated metal panel. The inches times pounds, designated inch-pound, 
absorber by the film without rupturing is a measure of the films 
reverse-impact resistance. 
Pencil hardness is a measure of film hardness. The adhesion and cohesive 
strength of the film also influences pencil hardness. Pencils of known 
lead hardness are shaped to a cylindrical point with a flat tip. The 
pencils are manually pushed into the coating surface at a 45.degree. 
angle. Pencil hardness is recorded as the hardest pencil which does not 
cut the coating. 
Pencil hardness after water immersion--Coated panels are immersed in a 
circulating, distilled water-bath for 16 hours at 52.degree. C. The panels 
are then placed in a shallow pan filled with warm tap water and tested for 
the retention of pencil hardness while immersed. This test is a measure of 
water sensitivity. 
Crosshatch adhesion--The coated substrate is cut with a series of parallel 
razor blades in a crosshatch pattern. Adhesion of the coating to the 
substrate is tested by firmly applying high tack tape and pulling the tape 
off with a quick pull. The percent coating remaining within the crosshatch 
pattern is recorded as the crosshatch adhesion. 
Pasteurization is a test designed to measure the resistance of a film to a 
simulated pasteurization cycle. The coated substrate is immersed in 
deionized, distilled water maintained at 76.7.degree. C. for 45 minutes. 
The coated substrate is quickly dried with a dry cloth or tissue and 
observed for blush or film whitening. Then the crosshatch test is used to 
measure the "wet" adhesion of the coating. 
In this application the following definitions describe the particular 
compounds that are used in the examples: Silicone Surfactant I is 
##STR5## 
Polyol A is a polycaprolactone triol having an average molecular weight of 
300 and an average hydroxyl number of 560. Polyol B is a polycaprolactone 
triol having an average molecular weight of 540 and an average hydroxyl 
number of 310. Polyol C is a polycaprolactone triol having an average 
molecular weight of 900 and an average hydroxyl number of 187. 
Epoxide A is 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate. 
Epoxide B is bis(3,4-epoxycyclohexylmethyl)adipate.

The following examples serve to further illustrate the invention. 
EXAMPLE 1 (Ex.2-4, KTC-77-21) 
A reaction flask equipped with a stirrer, thermometer, and nitrogen inlet 
tube was charged with 93.6 grams of 2-butoxyethanol and 21 grams of 
phthalic anhydride. The mixture was heated under nitrogen for 30 minutes 
at 130.degree. C. The butoxyethyl monoester of phthalic acid produced was 
a light yellow liquid which crystallized upon standing at room temperature 
for about one week. 
To a reaction flask similar to that described above there were charged 
137.1 grams of Polyol A and 182.9 grams of phthalic anhydride. The mixture 
was reacted under nitrogen for 60 minutes at 135.degree. C. in the 
presence of 80 grams of butyl acetate solvent. The resulting product was 
the carboxyl-modified polycaprolacetone polyol adduct; it as a clear, 
light brown liquid. 
A coating composition was formulated by mixing 4 grams of the liquid 
butoxyethyl monester of phthalic acid and 7.5 grams of the above 
carboxyl-modified polycaprolactone polyol adduct with 18 grams of Epoxide 
B, 0.15 gram of stannous octoate, 0.13 gram of Silicone Surfactant I, and 
3 grams of butyl acetate as solvent. Films were cast on steel panels with 
a number 40 wire-wound rod and cured for 30 minutes at about 100.degree. 
C. The cured film was solvent resistant (100 acetone rubs), flexible (&gt;320 
inch-pounds reverse impact), glossy and had a pencil hardness of H. 
EXAMPLE 2 (Ex.5 KTC-77-21) 
Following a procedure similar to that described in Example 1, a mixture of 
81.4 grams of n-butanol and 98 grams of maleic anhydride was reacted for 
10 minutes at 100.degree. C. The produce was liquid butyl acid maleate and 
had a density of 1.097 gm/ml and an acid number of 334.3 mg KOH/gm. 
A coating composition was formulated by mixing 1.45 grams of the above 
liquid butyl acid maleate and 5.2 grams of the carboxyl-modified 
polycaprolactone polyol adduct of Example 1 with 13.3 grams of Epoxide B, 
0.2 gram of stannous octanoate, 0.1 gram of Silicone Surfactant I and 2 
grams of butyl acetate. Films were cast as described in Example 1 and 
cured for 20 minutes at about 100.degree. C. The cured film was flexible 
(&gt;320 inch-pounds reverse impact) and glossy; it had a pencil hardness of 
F and passed 48 acetone rubs. 
EXAMPLE 3 (Ex.6, KTC-77-21) 
Following a procedure similar to that described in Example 1 a mixture of 
600 grams of Polyol A, 600 grams of Polyol B and 1200 grams of phthalic 
anhydride was reacted for one hour at 135.degree. C. After cooling to 
90.degree. C., 480 grams of butyl acetate solvent was added. The diluted 
carboxyl-modified polycaprolactone polyol adduct had an acid number of 
161.6 mg KOH/gm. 
A coating composition was formulated by mixing 10 grams of the above adduct 
and 2.4 grams of the butyl acid maleate of Example 2 with 10.7 grams of 
Epoxide A, 0.25 gram of stannous octanoate, 0.1 gram of Silicone 
Surfactant I, and 2 grams of butyl acetate. Films were prepared as 
described in Example 1 and cured for 30 minutes at 93.degree. C. The cured 
film was glossy and solvent resistant (100 acetone rubs) had a pencil 
hardness of 3 H and a reverse impact resistance of 5 inch-pounds. 
EXAMPLE 4 (Ex.7, 8, KTC-77-21) 
There were charged to a four-liter resin reactor 900 grams of 200 proof 
ethanol and 2664 grams of phthalate anhydride. Following a procedure 
similar to that described in Example 1, the mixture was reacted for one 
hour at 140.degree. C. to produce ethyl acid phthalate having an acid 
number of 284 mg KOH/gm and a density of 1.185 gm/cc. 
Following a procedure similar to that described in Example 1, 258.4 grams 
of Polyol B and 141.6 grams of phthalic anhydride were reacted for 30 
minutes at 140.degree. C. to produce the carboxyl-modified 
polycaprolactone polyol adduct having a Brookfield viscosity of 3260 
poises at 22.degree. C. and an acid number of 127.2 mg KOH/gm. 
A coating composition was formulated having an 87 weight percent solids 
content by mixing 5 grams of the above adduct and 5 grams of the above 
ethyl acid phthalate with 16.7 grams of Epoxide A, 0.27 grams of stannous 
octanoate, 0.1 grams of Silicone Surfactant I and 4 grams of butyl 
acetate. Films were cast as described in Example 1 and cured for 20 
minutes at 93.degree. C. The cured film was glossy, had a pencil hardness 
of 2 H, a reverse impact resistance of 5 inch-pounds and passed 85 acetone 
rubs. 
EXAMPLE 5 (Ex.9.KTC-77-21) 
A coating composition was formulated by mixing 1.25 grams of Aroflint 
404.RTM. (a chlorinated polycarboxylic acid described in U.S. Pat. No. 
3,218,274) and 2.25 grams of ethyl acid phthalate with 8.55 grams of 
Epoxide B, 0.11 gram of stannous octanoate, and 0.1 gram of Silicone 
Surfactant I. Films were cast as described in Example 1 and cured for 20 
minutes at 93.degree. C. and for 3 weeks at room temperature. The film 
cured at 93.degree. C. had a high gloss, a pencil hardness of H, a reverse 
impact resistance of 275 inch-pounds and passed 52 acetone rubs. The film 
cured at room temperature had a high gloss, a pencil hardness of HB, a 
reverse impact resistance of 25 inch-pounds and passed 30 acetone rubs. 
EXAMPLE 6 (Ex.10, KTC-77-21) 
A 100-gallon, glass-lined autoclave equipped with a 15-inch, three blade 
impeller that operated at 114 rpm was charged with 180 pounds of 
2-ethoxyethyl acetate solvent, 480 pounds of Polyol C, and 230 pounds of 
phthalic anhydride. The mixture was reacted for 4 hours at 140.degree. C. 
to produce a liquid polycarboxylic adduct, which is the carboxyl-modified 
polycaprolactone triol adduct having a viscosity of 1240 centistrokes at 
25.degree. C. and an acid number of 102 mg KOH/gm. 
A pigment-containing composition was prepared by charging 30 grams of the 
above polycarboxylic adduct, 30 grams of ethyl acid phthalate, 196 grams 
of titanium dioxide, 3 grams of stannous octanoate, and 46 grams of 
2-ethoxyethyl acetate to a ball mill and grinding overnight. 
A coating composition was formulated by blending 151.75 grams of the above 
pigment-containing composition with 60 grams of Epoxide A, 10 grams of 
Epoxide B and 0.75 gram of Silicone Surfactant I. The coating composition 
had an 88 weight percent solids content, a Brookfield viscosity of 270 
centipoises at 25.degree. C., and a Zahn cup viscosity of 40 seconds. 
Films were applied to steel panels with a suction-feed spray gun and cured 
for 20 minutes at 105.degree. C. The cured film was solvent resistant (100 
acetone rubs) had a 20.degree. C. gloss of 87, a pencil hardness of F, and 
a reverse impact resistance of 150 inch-pounds. 
EXAMPLE 7 (Ex.12-17, KTC-77-21) 
Following a procedure similar to that described in Example 1 a mixture of 
750 grams of Polyol A, 750 grams of Polyol B, 1500 grams of phthalic 
anhydride and 750 grams of 2-ethoxyethyl acetate was charged to a 4-liter 
reactor and reacted for one hour at 140.degree. C. The carboxyl-modified 
polycaprolactone polyol adduct had a solids content of 80 weight percent 
and a Brookfield viscosity of 87,300 centipoises at 25.degree. C. 
The above adduct was blended in 3 different proportions with ethyl acid 
phthalate and the acid number and viscosity were determined at 80 weight 
percent solids in 2-ethoxyethyl acetate. The mixtures and results are 
shown in Table I. For comparative purposes 2 compositions containing only 
the adduct and only the ethyl acid phthalate respectively were evaluated 
and the results are also shown in Table I. 
TABLE I 
______________________________________ 
A B C D E 
______________________________________ 
Adduct, (grams) 100 75 50 25 0 
Ethyl acid phthalate, (gms) 
0 25 50 75 100 
2-Ethoxyethyl acetate, 
(gms) 25 25 25 25 25 
Brookfield viscosity, 
(poises) 873 20.6 4.5 1.4 0.9 
Acid number, (mg KOH/gm) 
160 174 188 208 239 
______________________________________ 
Five coating compositions were formulated by mixing 100 grams of the above 
compositions A-E with Epoxide A at a constant carboxyl-to-epoxide 
equivalent ratio of 0.3. The formulations are shown in Table II. Films 
were cast following a procedure similar to that described in Example 1 and 
cured for 30 minutes at 105.degree. C. The films were evaluated and the 
results are shown in Table II. 
TABLE II 
__________________________________________________________________________ 
A B C D E 
__________________________________________________________________________ 
Epoxide A, (gms) 
129 140 151 167 190 
Stannous Octoate, (gms) 
2.3 2.4 2.4 2.7 2.9 
Silicone Surfactant I, (gms) 
1.2 1.2 1.2 1.3 1.4 
Weight Percent Solids 
91 92 92 93 93 
Viscosity at 25.degree. C., (cps) 
1110 750 430 362 260 
Acetone Rubs &gt;100 &gt;100 &gt;100 &gt;100 &gt;100 
Pencil Hardness 
4H 3H 3H 3H 3H 
Reverse Impact, (in-lbs) 
&lt;5 &lt;5 &lt;5 &lt;5 &lt;5 
__________________________________________________________________________ 
EXAMPLE 8 (EX.18, KTC-77-21) 
Following a procedure similar to that described in Example 1, a mixture of 
272 grams of Polyol C and 128 grams of phthalic anhydride was reacted for 
one hour at 140.degree. C. The carboxyl-modified polycaprolactone polyol 
adduct had a Brookfield viscosity of 19,700 centipoises at 25.degree. C. 
and an acid number of 120 mg KOH/gm. 
A coating composition was formulated by blending 6.5 grams of the above 
adduct and 2.2 grams of linoleic acid with 11.3 grams of Epoxide A, 0.2 
gram of stannous octanoate and 1 gram of 2-ethoxyethyl acetate. Films were 
cast as described in Example 1 at 95 weight percent solids and cured for 
20 minutes at 105.degree. C. The cured films were flexible (&gt;320 
inch-pounds reverse impact), solvent resistant (100 acetone rubs), and had 
pencil hardness of H.