Polymerization process and product

The product and process is directed to polymerizing second stage ethylenically unsaturated monomers within an aqueous dispersion of a preformed epoxy based resinous material comprising a mixture of graft epoxy polymer containing grafted addition polymer grafted to the epoxy backbone, ungrafted epoxy polymer, and ungrafted addition polymer uniformly dispersed in water wherein the second stage monomers are polymerized in the presence of at least 0.1% of benzoin derivative reducing agent based on monomer weight in combination with a peroxide polymerization initiator.

BACKGROUND OF THE INVENTION 
This invention relates to a process for increasing the addition polymer 
content of a resinous reaction product in a liquid vehicle. More 
particularly, the invention is concerned with a process for in situ 
polymerization of ethylenic monomers in the presence of a water-reducible, 
epoxy-based aqueous dispersion. The invention is also concerned with 
products produced by these processes, and particularly, with 
water-reducible, epoxy-based coating compositions. The subject matter of 
the present patent application is related to the subject matter of other 
patent applications now being U.S. Pat. No. 4,212,781 and U.S. Pat. No. 
4,285,847. 
Graft polymers formed between epoxy resins and polymerized addition 
monomers including an acrylic acid are suggested in these patents and in 
certain prior art for use in coating compositions. 
In the art prior to U.S. Pat. No. 4,212,781 and U.S. Pat. No. 4,285,847, 
so-called graft polymers were formed by an esterification reaction between 
an acidic addition monomer or polymer and an epoxy resin to form an ester 
graft. The techniques for making epoxy-based resins water-dispersible, 
through inversion with amines, and for cross-linking them with added 
aminoplast, are well known. However, ester adduct products have not been 
satisfactory and do not have good resistance to water since the adducts 
are susceptible to hydrolysis. 
U.S. Pat. No. 4,212,781 discloses a process for resinous compositions for 
use in coating compositions particularly useful as sanitary coatings, that 
is, as coatings for cans to contain edible materials. Such can coating 
compositions are easy to apply in existing equipment, have excellent shelf 
stability, and after application and curing have excellent functional 
properties as coatings and do not impart any flavor to the food or 
beverage in the can. The process comprises preparing a curable resinous 
composition having an Acid Number of at least 30, by reacting together at 
90.degree. C. to 130.degree. C. an aromatic diepoxide resin having a 
molecular weight above 1,000 and addition polymerizable monomer including 
10% to 80% by weight acrylic acid, the diepoxide resin being present in 
sufficient quantity to provide from 30% to 90% by weight of the initial 
reaction mixture, in the presence of a free radical initiator of the 
benzoyl peroxide type. During this reaction there is simultaneous addition 
polymerization of the monomer through its ethylenic unsaturation and 
grafting of addition polymer to the diepoxide resin. The acid 
functionality of the reaction mixture is sufficiently high to effect 
stable dispersion of the product in a basic aqueous medium. As is more 
particularly pointed out in U.S. Pat. No. 4,212,781, the resinous reaction 
product produced contains three polymeric components, namely, the graft 
polymer, ungrafted diepoxide resin, and ungrafted addition polymer. The 
initial epoxy resin employed in the graft polymer production process can 
be terminated to eliminate part or all of the terminal epoxy groups to 
eliminate the possibility of ester grafting, as more particularly set 
forth in copending application Ser. No. 793,507, filed May 4, 1977. 
In U.S. Pat. No. 4,285,847, a preferred embodiment sets forth a process for 
polymerizing in situ an added quantity of addition polymerizable monomer 
containing ethylenic (vinyl) unsaturation, in an aqueous dispersion of a 
resinous reaction product produced in accordance with a process of one of 
the earlier filed patent applications described above, that contains as 
the resinous component thereof a mixture of graft polymer, unreacted epoxy 
resin, and ungrafted addition polymer. The net result of that process is 
to reduce substantially the percentage of epoxy resin and increase 
substantially the percentage of polymerized addition polymerizable 
monomer. Another useful result is to increase the solids content of the 
composition. 
It now has been found that an organic reducing agent, preferably a benzoin 
derivative advantageously avoids redox catalyst problems that can occur in 
the second stage monomer polymerization step wherein ethylenically 
unsaturated monomers are polymerized in the presence of the preformed 
resinous mixture which desirably contains (a) epoxy polymer, (b) addition 
polymer, and (c) grafted polymer of addition polymer grafted to the epoxy 
backbone. Too much catalyst can cause a protective coating to exhibit a 
blush whereas too little catalyst causes insufficient conversion and 
polymerization of the monomers. In accordance with this invention, an 
organic reducing agent, preferably benzoin, used in conjunction with 
peroxide catalyst advantageously avoids the blushing problem and further 
provides excellent conversion of the monomers during polymerization. This 
advantage is particularly important where large amounts of acrylic 
monomers are used whereby a film blush can now be avoided. A further 
advantage is achieved with coating compositions synthesized with benzoin 
wherein the cured coatings exhibit excellent resistance to strenuous 
detergent testing such as a 1% boiling Joy detergent test. These and other 
advantages will become more apparent by referring to the detailed 
description of the invention and the illustrative examples. 
SUMMARY OF THE INVENTION 
Briefly, the process of the invention comprises the in situ polymerization 
of ethylenically unsaturated monomers in an aqueous dispersion of 
preformed resinous mixture of graft epoxy polymer containing grafted 
addition polymer, ungrafted epoxy polymer, and ungrafted addition polymer, 
wherein the improvement comprises the inclusion of at least about 0.1% of 
reducing agent, preferably benzoin, in combination with a peroxide 
initiating catalyst. 
DETAILED DESCRIPTION OF THE INVENTION 
The process of this invention comprises the polymerization of second stage 
ethylenic monomers in the presence of a water-dispersed graft polymer 
resinous reaction product wherein the second stage monomers are 
polymerized in the presence of a benzoin derivative reducing agent in 
combination with a peroxide initiator. 
The term "graft polymer resinous reaction product" is used to refer to the 
reaction mixture that is produced by the addition polymerization of 
ethylenically unsaturated monomer in the presence of an epoxy resin 
containing aliphatic backbone carbons having one or two hydrogens bonded 
thereto in the ungrafted state, in the presence of at least 3% benzoyl 
peroxide (BPO) or equivalent hydrogen-extracting initiator, based on 
monomer. The resinous reaction product can be either acid-functional or 
base-functional. The resulting graft polymer resinous reaction product is 
a mixture of unreacted epoxy resin, a graft polymer formed by 
carbon-to-carbon bonding of addition polymer to an aliphatic backbone 
carbon of the epoxy resin, and addition (vinyl) polymer formed from 
polymerized ungrafted monomer present. 
The vinyl monomer used in the first-stage resinous reaction product can be 
a single monomer but preferably is a monomer mixture, and includes 
ethylenically unsaturated acids, particularly acrylic acid and methacrylic 
acid. Styrene and ethylenically unsaturated acid esters are also useful, 
such as, for example, ethyl acrylate, butyl acrylate, the corresponding 
esters of methacrylic acid, and the like. The ethylenically unsaturated 
acids include acrylic acid and lower alkyl substituted acrylic acids, that 
is, those acids having ethylenic unsaturation in a position that is alpha, 
beta, to a single carboxylic acid group. The preferred acrylic acid is 
methacrylic acid. 
To form the graft polymer resinous reaction product, the ethylenically 
unsaturated monomer component is addition polymerized in the presence of 
the epoxy resin component. Generally a solvent can be employed that will 
dissolve all of the reactants and the reaction product such as 
2-butoxyl-ethanol-1. The epoxy resin can be an aromatic 1,2-epoxy 
diepoxide resin that has two terminal epoxy groups per molecule such as a 
diglycidyl ether of bisphenol A. The initiator preferably is benzoyl 
peroxide at a concentration of at least 3% by weight of the monomer, and 
preferably 4% or more, and most preferably from 6% to 7%. Concentrations 
of benzoyl peroxide of 15% or higher based on monomer may be employed 
although about 6% to 7% is adequate. With this particular initiator, the 
polymerization temperature may be in the range from about 110.degree. C. 
to about 130.degree. C., for practical reaction speeds although higher and 
lower can be used between about 50.degree. C. and 200.degree. C. Other 
free radical initiators other than benzoyl peroxide can be used such as 
t-butyl perbenzoate, lauroyl peroxide, decanoyl peroxide, and caproyl 
peroxide. 
The epoxy resin may be terminated to eliminate substantially all of the 
epoxy groups, by reacting with terminating agents such as the phenols, 
carboxylic acids, primary and secondary amines, mercaptans, alcohols, and 
even water. A base-functional graft polymer resinous reaction product may 
be made by incorporating an amine in the graft polymer molecule. There are 
two preferred ways to to this. First, an epoxy resin having epoxide groups 
available for reaction may be reacted with a primary or a secondary amine, 
thus introducing tertiary amine groups into the molecule. Second, an 
unsaturated amine such as dimethylaminoethyl methacrylate may be 
incorporated in the monomer mixture that is used to form the graft polymer 
resinous reaction product. 
Some representative first stage acid-functional dispersion compositions are 
as follows, in parts by weight. 
TABLE I 
______________________________________ 
Representative First Stage Dispersion Compositions 
Component Parts By Weight 
______________________________________ 
Epoxy resin 95 75 60 37.5 12.5 
EEW 4,000 
addition polymerizable 
5 25 40 62.5 87.5 
monomer including 
an acrylic acid 
2-butoxy-ethanol-1 
30.4 24 19 12 4 
n-butanol 45.6 36 29 18 6 
dimethyl ethanol 
7.6 6 4.8 3 1 
amine 
(ionizing agent) 
demineralized water 
310 245 196 122.5 70 
Total 493.6 411 348.8 255.5 181 
______________________________________ 
SECOND STAGE POLYMERIZATION 
In accordance with this invention, the addition polymerization of second 
stage ethylenically unsaturated monomers is conducted in an aqueous 
dispersion of the graft polymer resinous reaction product from the first 
stage. 
Addition polymerizable ethylenically unsaturated monomer is added to the 
aqueous dispersion of resinous reaction product together with a suitable 
initiator, including at least 0.1% benzoin or similar reducing agent and 
preferably between 0.1% and 5% benzoin based on second stage monomers. 
Useful second stage vinyl monomers include vinylidene chloride; 
arylalkenes, such as styrene, vinyl toluene, alpha-methyl styrene, 
dichlorostyrene, and the like; C 1 to C 15 alkyl acrylate esters, and 
particularly, lower alkyl acrylates, such as methyl acrylate, butyl 
acrylate, and lower alkyl methacrylates, such as methyl methacrylate, 
butyl methacrylate, and, as well, the nonyl, decyl, lauryl, isobornyl, 
2-ethyl hexyl, and octyl esters of acrylic or methacrylic acid, also 
trimethylol-propane, trimethacrylate, 1,6-hexanediol dimethacrylate, and 
the like; hydroxy lower alkyl acrylates, such as hydroxy propyl acrylate, 
hydroxy ethyl acrylate, and the like; hydroxy lower alkyl methacrylates, 
such as hydroxy ethyl methacrylate, hydroxy propyl methacrylate, and the 
like; amino lower alkyl methacrylates, such as N,N-dimethylamino ethyl 
methacrylate; amino lower alkyl acrylates, such as N,N-dimethylamino ethyl 
acrylate; lower alkenyl nitriles, such as acrylonitrile, 
methacrylonitrile, and the like; lower alkenyl carboxylic acids, such as 
acrylic acid, methacrylic acid, and the like; lower alkenyl amides, such 
as acrylamide, methacrylamide, isobutoxymethylacrylamide, and the like; 
lower hydroxyalkyl alkenyl amides such as hydroxy methyl acrylamide, and 
the like; lower alkyl butenedioates such as dibutyl maleate, dibutyl 
fumarate, and the like; vinyl lower alkenoates, such as vinyl acetate, and 
vinyl propionate, and the like; vinyl chloride and other vinyl halides, 
isoprene, conjugated butadiene, and the like, etc. Preferred vinyl 
monomers include styrene, butyl acrylate, ethyl acrylate, and methacrylic 
acid. 
In order to cause the vinyl monomer to polymerize, at least one peroxide 
initiator is introduced into the aqueous dispersion before or during 
addition of the second stage monomers. The amount of initiator used in the 
second stage polymerization typically is in the range from about 0.1 to 20 
parts per 100 parts by weight of total second stage ethylenically 
unsaturated added and preferably from about 0.5 to 10 parts per 100 parts 
total second stage monomer. Useful initiators comprises organic peroxides. 
One group of suitable peroxides comprises diacyl peroxides, such as 
benzoyl peroxide, lauroyl peroxide, acetyl peroxide, caproyl peroxide, 
butyl perbenzoate, 2,4-dichloro benzoyl peroxide, p-chlorobenzoyl 
peroxide, and the like. Another group comprises ketone peroxides, such as 
methyl ethyl ketone peroxide and the like. Another group comprises alkyl 
hydroperoxide such as t-butyl hydroperoxide, and the like. Another group 
comprises aqueous hydrogen peroxides. Preferred catalysts are 
hydroperoxides such as t-butyl hydroperoxide and hydrogen peroxide. 
In accordance with this invention, at least about 0.1% of a benzoin 
derivative reducing agent based on second stage monomers is used in 
conjunction with the peroxide initiator in the second stage polymerization 
step. The preferred benzoin derivative is benzoin. Other useful benzoin 
derivatives include benzoin alkyl ethers and substituted benzoins such as 
alkyl substituted, either alkyl substituted such as methoxy or ethoxy 
benzoin, or halogen substituted benzoin. The useful range of benzoin 
derivative is between 0.1% and 10%, and the preferred range is 1% to 5% 
benzoin derivative based on the weight of the second stage monomers. With 
respect to the ratio of benzoin derivative, a weight ratio of about 1 to 
20 moles of peroxide per mole of benzoin derivative is useful and a weight 
ratio of 3 to 10 moles of peroxide to benzoin derivative is preferred. A 
highly desirable weight ratio is 5 moles of peroxide to 1 mole of benzoin 
derivative. 
In general, in situ polymerization of the second stage ethylenic monomers 
in accordance with this invention proceeds under liquid phase conditions 
at temperatures in the range from about 25.degree. to 100.degree. C., and 
preferably, from 50.degree. C. to 100.degree. C., and most preferably, 
from about 50.degree. to 80.degree. C. Polymerization times are variable, 
depending upon starting materials, conditions, and the like; typical 
reaction times and monomer addition rates range from about 1 to 3 hours, 
but longer and shorter times are common. The resulting product can contain 
between about 1 to 5 weight parts of second stage polymerized monomer per 
about 20 weight parts first stage resinous reaction product. 
To make especially durable surface coatings from the resulting dispersed 
product, aminoplast resins are added as cross-linking agents. Typical 
aminoplasts include melamine, benzoguanamine, acetoguanamine, and urea 
resins such as ureaformaldehyde. Commercially available aminoplasts which 
are water soluble or water dispersible for this purpose include Cymel 301, 
Cymel 303, Cymel 370, and Cymel 373 (all being products of American 
Cyanamid, Stamford, Conn., and being melamine based, e.g., 
hexamethoxymethyl melamine for Cymel 301), and Beetle 80 (products of 
American Cyanamid which are methylated or butylated ureas). If acrylamide 
or the like is used as a vinyl monomer in either the first stage, the 
second stage, or both, in an acid-functional resinous reaction product, 
the product will be self cross-linking. Another way to introduce 
cross-linking capability into the reaction mixture and the graft polymer 
is by utilizing as all or part of the polymerizable monomer, in the 
initial first stage monomer mixture, an alkyl derivative of acrylamide or 
a material such as bis maleimide. 
The coating composition of the present invention can be pigmented and/or 
opacified with known pigments and opacifiers. For many uses, including 
food uses, the preferred pigment is titanium dioxide. Generally, the 
pigment is used in a pigment-to-binder ratio of 0.11:1 to 1:1, by weight. 
Thus titanium dioxide pigment can be incorporated into the composition in 
amounts of from about 5% to 40% by weight, based on solids in the 
composition. 
The resulting aqueous coating composition can be applied satisfactorily by 
any conventional method known in the coating industry. Thus, spraying, 
rolling, dipping, flow coating or electrodeposition applications can be 
used for both clear and pigmented films. Often spraying is preferred. 
After application onto a metal substrate, the coating is cured thermally 
at temperatures in the range from about 95.degree. C. to about 235.degree. 
C. or higher, for periods in the range from 1 to 20 minutes, such time 
being sufficient to effect complete curing as well as volatilizing of any 
fugitive component therein. Further, films may be air dried at ambient 
temperatures for longer periods of time. 
For metal sheet substrates intended as beverage containers and particularly 
for carbonated beverages such as beer, the coatings should be applied at a 
rate in the range from 0.5 to 15 milligrams of polymer coating per square 
inch of exposed metal surface. To attain the foregoing, the 
water-dispersible coating as applied can be as thick as 1/10th to 1 mil.

The merits of this invention are further illustrated in the following 
examples. 
EXAMPLE 1 
First stage resinous reaction products containing an epoxy-acrylic graft 
copolymer were produced as follows: 
(a) 80% By Weight Epoxy Resinous Reaction Product 
In this procedure, 18,099 lbs. of an aromatic epoxy resin having an epoxy 
equivalent weight of 5,300 and a viscosity of Z.sub.2 -Z.sub.3 (40% in 
2-butoxy-ethanol-1) and containing 482 lbs. of xylene are charged to the 
reactor. The mixture is sparged with nitrogen and formed into a mixture 
with 5,073 lbs. of 2-butoxy-ethanol-1 and 8,725 lbs. of n-butanol. The 
mixture is brought to a temperature in the range from about 240.degree. F. 
to 245.degree. F. (About 115.degree. C.-118.degree. C.). 
In a separate weigh tank, a mixture is made of the following: 
______________________________________ 
Ingredients Parts by Weight 
______________________________________ 
methacrylic acid 2,997 lbs. 
styrene 1,565 lbs. 
ethyl acrylate 40 lbs. 
wet benzoyl peroxide 400 lbs. 
(78% dry bases) 
2-butoxy-ethanol-1 1,170 lbs. 
______________________________________ 
With the contents of the reactor at a temperature in the range from about 
240.degree. F. to 245.degree. F. (about 115.degree. C.-118.degree. C.), 
and while mixing, the addition of the monomer mixture is initiated and 
continued for about 2 hours, at a uniform rate of about 45 lbs. per 
minute, with the agitation continuing. The contents of the reactor are 
then held at the 240.degree. F.-245.degree. F. (about 115.degree. 
C.-118.degree. C.) temperature for about 3 hours. At the end of this time, 
the viscosity is K-R, in 1/1, resin/m-pyrol (N-methyl-pyrolidone). The 
non-volatiles are in the range from about 56% to about 60%, preferably 
58.5%. Oxirane value (N.V.) is about 0.1-0.3, preferably 0.2. 
During the three hours period in the reactor, a reducing tank is loaded 
with 5,580 gallons of demineralized water (46,488 lbs.). Then, 2,182 lbs. 
of dimethyl ethanol amine and 2,762 lbs. of 2-butoxy-ethanol-1 are added 
to the water in the reducing tank. The contents of the reactor are then 
transferred to the reducing tank over a period of 30 to 45 minutes, with 
continued heating and agitation for about a half hour. Then an additional 
quantity of demineralized water, 922 gallons (7,672 lbs.), is added to the 
reducing tank, and the contents of the reactor are cooled to the range 
from 90.degree. F. to 100.degree. F. (about 32.degree.-38.degree. C.), to 
provide the product A. At this point, the weight per gallon of the product 
A, should be about preferably 8.5 lbs., with a non-volatiles content of 
preferably about 22.5%. The viscosity as determined in a No. 4 Ford cup at 
25.degree. C. (77.degree. F.) should be in the range from 50 to 60, and 
the pH should be preferably 7.3. The Base Number (N.V.) should be 
preferably about 60. The Acid Number (N.V.) is about 85. 
The epoxy resin contributes about 80% by weight to the polymeric solids of 
the resinous reaction product, and the first stage addition polymerizable 
monomer contributes about 20% to the reaction product. The resulting water 
dispersed resinous reaction product A has three solids components, namely: 
(a) unreacted modified epoxy resin, about 38% by weight of total solids; 
(b) graft polymer in which addition polymer is grafted to aliphatic 
backbone carbon atoms of the epoxy resin that have either one or two H 
bonded thereto in the ungrafted state, about 50% by weight of solids in 
product A; and 
(c) (ungrafted) addition polymer, about 12% by weight of the product A 
solids. The percentage figures for the respective solids components are 
approximations based on solvent partition and other analytical techniques. 
(B) 75% By Weight of Epoxy Resin Resinous Reaction Product 
A graft polymer resinous reaction product is prepared having its solids 
content derived from an initial raw material comprising about 75% epoxy 
resin and about 25% ethylenically unsaturated monomers. The graft polymer 
resinous reaction product is prepared in the following manner. About 4,233 
lbs. of an aromatic epoxy resin having an epoxy equivalent weight of 5,300 
and a viscosity of Z.sub.2 -Z.sub.3 (40% in 2-butoxy-ethanol-1) and 
containing 100 lbs. of xylene is mixed in a agitated reactor with a 
solvent system made up of 1,155 of 2-butoxy-ethanol-1 and 2,252 lbs. of 
n-butanol. Mixing is continued while the epoxy resin is brought to 
240.degree. F.-245.degree. F. (115.degree. C.-118.degree. C.), with 
nitrogen sparging. 
In a separate vessel, the following are charged, to form a mixture: 
______________________________________ 
methacrylic acid 878 lbs. 
styrene 460 lbs. 
ethyl acrylate 14 lbs. 
benzoyl peroxide (BPO) 
115 lbs. (as is basis, 
78% active, 
in water) 
2-butoxy-ethanol-1 
347 lbs. 
______________________________________ 
The BPO amounts to about 6.6% by weight of the total first stage monomer 
present. The monomers are thoroughly mixed, then the mixture is gradually 
added to the reactor containing the epoxy resin, at a uniform rate, over a 
period of about three hours, while maintaining an essentially constant 
temperature. The reactor contents are then held at 240.degree. 
F.-245.degree. F. (115.degree. C.-118.degree. C.) for about three hours. 
The reaction mixture is then cooled to 210.degree. F. (85.degree. C.). 
During the three hours hold period, the following are charged to a mixing 
tank: 
______________________________________ 
demineralized water 9,564 lbs. 
2-butoxy-ethanol-1 524 lbs. 
dimethyl ethanolamine 377 lbs. 
______________________________________ 
After thorough mixing and heating to about 120.degree. F., 7,810 lbs. of 
the above reaction product is added to the mixing tank to form an aqueous 
dispersion referred to hereafter as product B. The resinous reaction 
product B is a mixture formed from the addition polymerization of 1,352 
parts by weight of the mixture of addition polymerizable monomers in the 
presence of 4,113 parts by weight, approximately, of the epoxy resin, and 
in the presence of about 6.6% by weight of BPO initiator based on total 
monomer. This amount is far above that used for ordinary addition 
polymerizations, and is effective simultaneously to cause carbon-to-carbon 
grafting of addition (vinyl) polymer to the aliphatic backbone carbons of 
the epoxy resin and addition (vinyl) polymerization of the monomer. The 
grafting is believed to be due to the hydrogen extracting ability of the 
BPO at the reaction temperature employed. The ionization is sufficient in 
extent that the product B solids can be characterized as dispersoid in 
nature. The dispersion is opalescent and remains stable over a period of 
many months at room temperature, without any need for agitation to 
redistribute the particles. The Acid Number of product B on a solids basis 
(on non-volatiles, i.e., NV) is about 104. The Base No. (mg. of KOH/gm. of 
solids) is about 53.2 (NV), viscosity is 72 seconds as measured in a No. 4 
Ford cup at 25.degree. C. N.V. content is about 24.7%. 
(C) 70% By Weight of Epoxy Resin Resinous Reaction Product 
Product C is made similarly to that of product A and product B except 5% of 
the epoxy resin is replaced by styrene, so the epoxy content in product C 
is roughly 70%. The remaining is consisted of 16.7% styrene, 13% 
methacrylic acid and 0.3% ethyl acrylate. 
(D) Resinous Reaction Product (Epoxy Advancement) 
To a 5 liter flask fitted with an agitator, thermometer, and nitrogen gas 
inlet tube, 1084 grams of low molecular weight epoxy (Epon 828, Shell) 614 
grams Bisphenol A, 57 grams xylene and 310 grams 2-butoxy-ethanol-1 was 
charged. This mixture was then heated to 85.degree. C. with a nitrogen 
sparge present. At 85.degree. C., 0.51 g. of sodium acetate dissolved in 
2.5 g. H.sub.2 O was added to the flask. A 17" Hg vacuum was then pulled 
on the reaction vessel and the contents were heated to 140.degree. C. The 
heat was then turned down and vacuum continued until 28.7 grams of 
volatiles were removed from the reaction flask. The reaction mixture was 
then held at 175.degree. C. until a viscosity of Z.sub.2 at 40% in 
2-butoxy-ethanol-1 was reached. At this time 170 g. 2-butoxy-ethanol-1 was 
added and the reaction product was cooled to 155.degree. C. when 826 
grams of normal butanol was added over a period of time to allow the 
solvent to mix in without refluxing heavily. 
The reaction product temperature was then allowed to drop to 117.degree. C. 
A mixture of 283 g. methacrylic acid, 148 grams styrene, 4 grams ethyl 
acrylate, 38.5 grams benzoyl peroxide and 111 grams 2-butoxy-ethanol-1 
were added to the reaction flask over a period of 2 hours. At the end of 
the addition 62 grams of n-butanol was added. The reaction product was 
then held at 117.degree.-118.degree. C. for 3 hours. At the end of 3 
hours, 2,683 grams of the reaction product was added to a mixture of 3,411 
grams DM H.sub.2 O, 193 grams 2-butoxy-ethanol-1, and 152 grams of 
dimethyl ethanol amine, which was then heated to 50.degree. C. An 
additional 560 grams of DM H.sub.2 O was then added 10 minutes later. The 
constants of this dispersion were: NV--22.9%, No. 4 Ford Cup visc.--31 
seconds; Acid Number--83.6 on NV; Base Number--64.3 on NV. This product 
was mixed overnight and allowed to cool to room temperature. The dispersed 
product was useful in formulating stable, sprayable beverage can coating 
compositions and is designated product D. 
SECOND STAGE MONOMER POLYMERIZATION 
EXAMPLE 2 
In accordance with this invention, a 1988 gm. of the product D dispersion 
product (20% NV) was charged into a 5-liter round bottom flask fitted with 
an agitator, thermometer and nitrogen sparge tub. 1.3 gm. of benzoin is 
added followed by a monomer mixture of 114.8 gm. of styrene and 17.3 gm. 
of methacrylic acid. The reaction mixture is then heated to 70.degree. C., 
at which time 2.1 gm. of hydrogen peroxide (50% in water) was added. The 
reaction mixture was then heated to 86.degree.-88.degree. C., and held at 
that temperature for 6 hours. At the end of the 6 hours hold, heating was 
discontinued and 13.3 gm. of deimethylethanol amine and 75 gm. of water 
were added to the reaction mixture. The non-volatile of the final product 
is 24.7%, viscosity No. 4 Ford cup--27 seconds, % free styrene--0.2%. 
EXAMPLE 3 
In accordance with this invention, 2850 gm. of the product D dispersion 
product (20%NV) was charged into a 5-liter round bottom flask similar to 
that in Example 2. A monomer mixture of 165 gm. of styrene and 25 gm. of 
methacrylic acid and 1.9 gm. of benzoin was added to the flask and the 
reaction mixture heated to 65.degree. C. At that time, 3 gm. of hydrogen 
peroxide (50% solution in H.sub.2 O) was added, and the reaction mixture 
heated to 85.degree. C. and held at 85.degree. C. for 6 hours. At the end 
of the 6 hour hold, 18 gm. of dimethylethanolamine and 32 gm. of water 
were added and heating discontinued. The final constants are: non-volatile 
24%, Viscosity No. 4 Ford cup--20 seconds and free styrene--0.19%. 
EXAMPLE 4 
In accordance with this invention, 2775 gm. of the product D dispersion 
(20% NV) was charged into a round bottom similar to that in Example 5. A 
monomer mixture consisted of the following: 165 gm. of styrene, 25 gm. of 
methacrylic acid and 1.9 gm. of benzoin was added to the dispersion, and 
the reaction mixture heated to 65.degree. C. At that temperature, 11.5 gm. 
of t-butylhydroperoxide (70% active in H.sub.2 O) and 61 gm. of water were 
added and the temperature of the reaction mixture raised to 85.degree. C. 
After 2 hours at 85.degree. C., 5.8 gm. of t-butylhydroperoxide (70% 
active in water) and 37 gm. of water were added, and the reaction mixture 
held at 85.degree. C. for another hour. At that time another shot of 5.8 
gm. t-butylhydroperoxide (70% active in water) and 37 gm. of water were 
added, and the reaction mixture held at 85.degree. C. for another hours. 
Heating was then discontinued and 18 gm. of dimethylethanolamine and 32 
gm. of water were added. The final constants are: volatile--22.8%, 
viscosity No. 4 Ford cup--13 seconds and free styrene--0.2%. 
In the following examples 5-9 in accordance with this invention, Table I 
lists some of the properties of examples 5-9 made with benzoin. In Table 
II, spray application properties as well as blush properties with 1% 
boiling Joy are listed for examples 5-9. 
TABLE I 
__________________________________________________________________________ 
Mole 
Wt. % Peroxide Vis. 
Benzoin 
Based On No. 4 Ford 
Base Based On 
Benzoin 
Benzoin 
Peroxide 
Cup, % Free 
Example 
Material 
BC/n-BuOH 
Monomer 
(1 mole) 
Addition 
Addition 
N.V. 
Secs. Styrene 
Example 
__________________________________________________________________________ 
5 Prod. A 
50/50 1 (tBHP-70) 
in monomer 
Shots 
23.1 
24.5 -- -- 
6 Prod. D 
25/75 1 (H.sub.2 O.sub.2) 
Batch Batch 
24.7 
27 0.2 5 
5 
7 Prod. D 
25/75 1 tBHP-70 
in monomer 
Shots 
22.8 
13 0.2 7 
20 
8 Prod. D 
25/75 1 (H.sub.2 O.sub.2) 
in monomer 
Batch 
24 20 0.19 6 
5 
9 Prod. D 
25/75 1 tBHP-70 
in monomer 
Batch 
23.9 
16 0.55 -- 
10 
__________________________________________________________________________ 
TABLE II 
__________________________________________________________________________ 
Blush in 1% 
No. 4 Ford ma Boiling Joy (15 Min.) 
Cup mg Enamel 1 Min. 
1 Min. 
1 Min. 
Example 
N.V. 
Visc. MEQ Coverage 
Rater 
Blister 
at 350.degree. F. 
at 370.degree. F. 
at 400.degree. F. 
__________________________________________________________________________ 
5 -- -- -- 90-100 140 
6 19.7 
24 124 100 6.5 200-210 
2* 0 0 
7 19.7 
22 130 90 3 170-180 
2 1 0 
8 19.4 
22 127 100 5 210-220 
1-2 0 0 
9 19.9 
19 132 100 10 200-210 
2 0 0 
__________________________________________________________________________ 
*10 Worst 
0 Best 
EXAMPLE 10 
Second Stage Polymerization 
In contrast to this invention, a coating composition was produced using a 
water-soluble redox initiator system. 
A reaction flask is charged with 6,980 parts by weight (22.5% N.V.) of the 
water-dispersed reaction product (A) produced in accordance with the 
process described in the first stage of Example 1, together with 271 parts 
by weight of styrene. Agitation is initiated to insure thorough mixing, 
and the flask is sparged for about a half hour with nitrogen. The 
temperature is then raised to 30.degree. C., and when this temperature is 
attained, a previously prepared mixture is added to the flask, containing 
2.4 parts by weight of sodium sulfoxylate formaldehyde in 21 parts by 
weight of demineralized water. The agitation is continued for two minutes, 
then a previously prepared mixture is added, containing 2.6 parts of 
t-butyl hydroperoxide in 20.5 parts of demineralized water. The agitation 
is then continued for about 10 minutes, and then the temperature is raised 
to 70.degree. C. and the contents of the flask are held at that 
temperature for about 3 hours. At the end of this hold period, a 
previously prepared mixture is added to the flask, and 62 parts of 
demethylethanolamine flask are then cooled to permit recovery of the 
coating composition. 
At this point, the composition has a non-volatiles content of 20.6% by 
weight, and a viscosity of 83 seconds as measured on a No. 4 Ford cup at 
25.degree. C. (77.degree. F.). The Acid Number (N.V.) of the reaction 
product is 72. The Base Number is 79. The polymeric solids content is 
derived from about 72% of epoxy resin and ethylenically unsaturated 
monomer, about 28%, with the second stage added styrene contributing about 
15% of total solids. 
EXAMPLE 11 
Second Stage Polymerization 
In a manner similar to Example 10, a coating composition produced by a 
redox system where the added ethylenically unsaturated monomer is a 
mixture of styrene and methacrylic acid. 
A reaction flask is charged with 2,793 pounds of a reaction product 
produced in accordance with the process described in the first stage of 
Example 3, product A, together with 100 parts by weight of styrene and 15 
parts by weight of methacrylic acid. These materials are mixed in the 
reaction flask for about 30 minutes, during which a nitrogen sparge is 
maintained. 
After the ingredients are thoroughly mixed, the temperature is raised to 
30.degree. C. At that time, 1.0 parts by weight of sodium sulfoxylate 
formaldehyde and 9 parts by weight of demineralized water are added to the 
reaction flask. The contents of the flask are then held for two minutes, 
and then 1.1 parts by weight of 90% tertiary butyl hydroperoxide and 8.7 
parts by weight of demineralized water are added. The temperature is 
permitted to rise for about 10 minutes until the contents of the reaction 
flask are at about 70.degree. C., and then they are held at that 
temperature for about two hours. 
After the two hour holding period, there are added to the flask 22 parts by 
weight of deimethyl ethanol amine and 865 parts by weight of demineralized 
water. The contents of the reaction flask are mixed thoroughly and 
permitted to cool at 30.degree. C. 
The product contains 20.26% by weight of non-volatiles, and has a viscosity 
of 19 seconds as measured on a No. 4 Ford cup at 25.degree. C. The Base 
Number (N.V.) is 53, and the Acid Number (N.V.) is 85. 
This product is characterized by the fine particle size of its solids 
content, and by its great stability upon storage. The small amount of 
methacrylic acid added during the second stage polymerization results in 
an acid functionality that is ionized by the presence of the subsequently 
added amine. 
The second stage monomer contributed about 15% of total solids present in 
the final product, with about 13% being furnished by the styrene and 2% by 
the methacrylic acid. 
EXAMPLE 12 
A second stage process comprising 75:25 first stage solids to second stage 
solids ratio; approximately 22 styrene to 3 methacrylic acid, was as 
follows: 
2,545 grams of the product D dispersion product was charged to a 5 liter 
flask fitted with an agitator, thermometer and nitrogen sparge tube. 277 
grams of demineralized water, 165 grams of styrene and 25 grams of 
methacrylic acid were then charged to the flask. This mixture was then 
agitated 30 minutes while sparging with nitrogen. After 30 minutes the 
mixture was heated to 52.degree. C. and the heat was turned off. 2 grams 
sodium solfoxylate formaldehyde dissolved in 20 grams of tertiary butyl 
hydroperoxide diluted with 20 grams of demineralized water was added to 
the flask. flask. Ten minutes later the heat gas applied and the reaction 
material heated to 80.degree. C. and held 3 hours and 20 minutes. This 
product was then cooled below 30.degree. C. with agitation. The final 
constants were: NV--24.7%, Visc. No. 4 Ford cup--11.5 seconds, Acid Number 
on NV--90.8, Base Number--49.5 on NV. 
The resultant product was further formulated for use as a can coating by 
the addition of a suitable amount of crosslinker, Cymel 303, and also by 
small additions of surfactant and other modifiers. The final coating was 
sprayed on the interior of cans. At a film weight of 115 to 125 mg. per 
can, the product showed good coverage (enamel rater value of 21), and at a 
film weight of 160 mg per can, the first signs of blistering were 
observed. 
When the products from examples 10, 11, and 12 were exposed to harsh 
environment like 1% boiling Joy solution (15 minutes), the coating film 
turns milky white. Samples made with sodium sulfoxylate formaldehyde 
blushed badly regardless of curing temperature. 
EXAMPLE 13 
In accordance with this invention, product C was used as starting material. 
3000 gm. of RP-C (33.5% NV) was charged into a reactor flask. A monomer 
mixture was made with 31.5 gm. of styrene, 152.4 gm. of ethyl acrylate, 
149.6 gm. of methyl methacrylate, 4 gm. of methacrylic acid, 6.8 gm. of 
benzoin was added and the reaction mixture heated to 65.degree. C. At that 
time, 9.6 gm. of t-butylhydroperoxide (70% active in water) and 17.9 gm. 
of water was added, and the reaction mixture heated to 85.degree. C. The 
reaction mixture was held at that temperature for three hours, and 9.6 gm. 
of t-butylhydroperoxide (70% active in water) and 17.9 gm. of water were 
added. The reaction mixture was held at 85.degree. C. for two more hours 
and heating discontinued. The final non-volatile of the material is 38.8%. 
This material when formulated gave an excellent roll coating for can ends. 
EXAMPLE 14 
To a 5 liter flask fitted with an agitator, thermometer and nitrogen gas 
inlet tube, 970 gm. of liquid epoxy (of which 921.5 gm. is Epon 828 and 
48.5 gm. is xylene), 523 gm. bisphenol A and 263 gm. 2-butoxy-ethanol-1 
was charged. This mixture was then heated to 85.degree. C. with a nitrogen 
sparge present. At 85.degree. C., 0.45 gm. of sodium acetate dissolved in 
4 gm. H.sub.2 O was added to the flask. A 17" Hg. vacuum was then pulled 
on the reaction vessel and the contents were heated to 140.degree. C. The 
heat was then turned down and vacuum continued until 21 grams of volatiles 
were removed from the reaction flask. The reaction mixture was then held 
at 175.degree. C. until a viscosity of Z.sub.2 at 40% in 
2-butoxy-ethanol-1 was reached. At this time 105 gm. of 2-butoxy-ethanol-1 
was added and the reaction product was cooled to 155.degree. C. when 688 
gm. of normal butanol was added over a period of time to allow the solvent 
to mix in without refluxing heavily. The reaction product temperature was 
then allowed to drop to 117.degree. C. A mixture of 317 gm. methacrylic 
acid, 302 gm. styrene, 21 gm. ethyl acrylate, 49.2 gm. benzoyl peroxide 
(78% active), 6.6 gm. tert-butyl perbenzoate and 111 gm. of n-butanol were 
added to the reaction flask over a period of 2 hours. At the end of the 
addition 62 gm. of n-butanol was added. The reaction product was then held 
at 117.degree.-118.degree. C. for 3 hours. At the end of 3 hours, 2,475 
gm. of the reaction product was added to a mixture of 3,587 gm. of DM 
H.sub.2 O, 166 gm. of dimethyl ethanol amine, which was then heated to 
50.degree. C. An additional 700 grams of DM water was then added 10 
minutes later. The nonvolatile for this dispersion was 23.4%. This product 
was mixed overnight and allowed to cool to room temperature. 
6,000 gm. of the dispersion was charged into a 5-liter round bottom flask 
fitted with an agitator, thermometer and nitrogen sparge tube. 575 gm. of 
DM H.sub.2 O was added followed by a solution mixture of 293 gm. styrene, 
57 gm. ethyl acrylate, 7 gm. benzoin and 108 gm. n-butanol. The reaction 
mixture is then heated to 85.degree. C. at which time 21 gm. of t-butyl 
hydroperoxide (70% active in H.sub.2 O) and 40 gm. of DM H.sub.2 O were 
added. The reaction mixture was then heated at 85.degree. C. for 2 hours. 
At that time 10.5 gm. of t-butyl hydroperoxide (70% active in H.sub.2 O) 
and 20 gm. of DM H.sub.2 O were added, and the reaction mixture was held 
at 85.degree. C. for two more hours. At the end of the 2 hours hold, 
another shot of 10.5 gm. t-butyl hydroperoxide (70% active in H.sub.2 O) 
and 20 gm. of DM H.sub.2 O was added, and the reaction mixture was held 
another 2 hours at 85.degree. C. After the hold, the reaction mixture was 
let cool to room temperature. The nonvolatile of the final product is 
24.4%, viscosity No. 4 Ford cup--19 seconds, acid number (on NV) 78.2, 
base number (on NV) 53.7, % neutralization 68.6%, MEQ 95.6, % free styrene 
0.13% and % free methacrylic acid 0.035%. 
The foregoing is not intended to be limiting except by the appended claims.