Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
Field of the Invention: The present invention relates to electro-
deposltlon. In another aspect, the invention relates to electrodeposition
employlng polymers prepared by a new method in aqueous medium. More
;~ ~ particularly, this inventiQn relates to the polymerization of dienes in the
presence of a salt of an adduct of an unsaturated carboxylic acid or
anhydride~and a member selected from the class consisting of drying oils -
and polybutadienes.
Brief Description of the Prior Art: U. S. Patent 3,258,437 discloses
polymers of butadiene prepared in the presence of aqueous msdium contalning
the salt of an adduct of a drying oil and an unsaturated dicarboxylic acid
or anhydride such as maleic anhydride. These polymers are prepared in the
~ .
pressnce of a water-soluble salt-forming free radical polymeri~ation catalyst;
and, although they are excellent resinous vehicles for many coating appli-
catlons such as dip or spray coating, they are unfortunately not suitable for
use ln electrodeposition. The salt-forming catalyst affects the conductivlty
of the bath, causing the polymers to coat out at high voltages which destroys
film continuity.
U. S. Patent 2,941,968 to McKenna discloses polymers of a vinyl
monomer such as styrene prepared in the presence of an aqueous medium containing
the salt of an adduct of a drying oil and an unsaturated dicarboxylic acid or
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:
anhydride such as maleic anhydride. These polymers may be prepared in the
presence of either water-soluble salt-forming free radical polymerization
catalyst or in the presence of oil-soluble free radical polymerization catalyst.U.S. Patent 3,511,816 to Dickakian discloses that polymers formed from
relatively low molecular weight polybutadienes and maleic anhydride are
capable of forming coatings which firmly adhere to metal. The coatings can
be made water-soluble by neutralization with an amine and used as vehicles for
water-based coatings. Unfortunately, such materials are not particularly
suited for electrodeposition. As aqueous dispersions, they have poor throw-
power; do not electrodeposit uniform coatings and the deposited coatings
do not have particularly good corrosion resistance. -
Summary of the Invention
The present invention provides a resinous vehicle prepared by addition ;
polymerizing a diene such as butadiene in the presence of an oil-soluble
free radical catalyst with a partially neutralized reaction product of an
unsaturated carboxylic acid or anhydride and a member selected from the
class consisting of drying oils and polybutadiene. The vehicles are
particularly suitable for use in electrodeposition. They have high throw-
power, good corrosion resistance on pretreated steel, and amazing bath
stability. That is, the resin can be employed in an electrodeposition bath
day after day without decomposing. Besides these advantages, the resin
employs water as substantially the only solvent. Also the resins of the
invention lose little solids on baking. Less than 5 percent by weight solids
are lost on baking, whereas losses as high as 25 percent are common with many
electrocoating vehicles.
Besides resinous products and their method of preparation, the
invention also provides for aqueous dispersions of the resinous products, for
methods of electrocoating employing these aqueous dispersions, and for the
resultant coated articles.
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More specifically the present invention provides a process for
preparing a resinous vehicle suitable for electrodeposition which comprises:
(A) addition polymerizing a diene, in the presence of
an oil-soluble free radical polymerization catalyst and a chain
transfer agent, in aqueous medium with
(B) at least 5 percent by weight of an at least partially
neutralized reaction product of:
(1) an unsaturated carboxylic acid or anhydride
and
(2) a member selected from the class consisting of
drying oils and polybutadienes; said polybutadiene being
a liquid at room temperature and having a molecular weight
of 700-5000;
when (2) is a drying oil (B) being at least 25 percent neutralized and
the percentages by weight of (1) and (2) being 14 to 45 percent and
55 to 86 percent by weight respectively; when (2) is a poly-
butadiene (B) being at least 30 percent neutralized and the
percentages by weight of (l) and (2) being 5 to 25 percent and 75
to 95 percent by weight respectively.
Detailed Description
Various dienes which may be used in the practice of the invention
include in addition to 1,3-butadiene, which is preferred, isoprene and
-2a-
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most of the dl-unsaturated members of the alkylidene series including
both the unsubstituted and substituted conjugated diole~ins. The sub-
stituted diolefins may be those containing lower alkyl groups or halogen
groups directly bonded to the alkylidene chain. Representative examples
of these diolefins include chloroprene, 2,3-dimethylbutadiene, myrcene
and the like. Also, mixtures of dienes can be used.
Certain advantages can be obtained by combining the diene with
ethylenically unsaturated comonomers (other than the dienes mentioned
above). Examples of ethylenically unsaturated comonomers are vinyl
monomers which are characterized as having the CH2=C ~ group, and can
be present in amounts of up to 65 and preferably 20 to 40 percent by
weight based on total weight of reactive monomer components Examples
of the vinyl monomers which may be used are: monoolefinic and diolefinic
hydrocarbons such as styrene, vinyl toluene, cyclopentadiene and the
like; halogenated monoolefinic and diolefinic hydrocarbons such as alpha-
chlorostyrene; esters of organic and inorganic acids such as vinyl acetate,
methyl methacrylate, butyl methacrylate, ethyl acrylate, butyl acrylate,
isopropenyl acetate, allyl chloride, allyl cyanide, dibutyl itaconate,
ethyl alpha-chloroacrylate, and diethyl maleate; organic nitriles such
as acrylonitrile, methacrylonitrile and ethacrylonitrile.
` Ethylenically unsaturated comonomers containing cyclic rings
such as styrene and vinyl toluene are preferred because they give
compositions of improved throwpower. By throwpower is meant the property
of the resinous vehicle whereby areas of the electrode being coated at
varying distances from the other electrode receive substantially the same
density of product. Several methods have been proposed for measuring
throwpower, including the Ford Cell Test and the General Motors Cell Test,
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see, for example, Brewer et al, Journal of Paint Technology, 41, No. 535,
pages 461-471 (1969); and Gilchrist et al, American Chemical Society,
Div. of Organic Coatings and Plastics Chemistry, Preprint Book, 31,
No. 1, pages 346-356, Los Angeles Meeting, March-April 1971.
The drying oils employed in the invention are esters of fatty
acids which can be obtained from naturally occurring sources or which
can be obtained by reacting a fatty acid with a polyol. The drying~oils
all contain at least a portion of polyunsaturated fatty acids. The drying
oils are those oils which have an iodine value of about 90 or above as
determined by ASTM D-1467 and thus include the so-called semi-drying
oils. Examples of suitable naturally occurring drying oils are linseed
oil, soya oil, safflower oil, perilla oil, tung oil, oiticia oil, poppy-
seed oil, sunflower oil, tall oil esters, walnut oil, dehydrated castor
oil, herring oil, menhaden oil, sardine oil, and the like.
Drying oils may also be obtained by reacting fatty acids with
a polyol. Suitable fatty acids are oleic, linoleic and linolenic. Various
polyols can be used, including butanediol, glycerol, trimethylol ethane,
trimethylol propane, triethanol propane, trimothane~Vhexane, pentaerythritol
and sorbitol.
The drying oils can be modified with other acids, including
saturated, unsaturated or aromatic acids such as butyric acid, stearic
acid, oleic acid, phthalic acid, isophthalic acid, terephthalic acid,
rosin or ben~oic acid or anhydride of such an acid. These acid-modified
oils are made by transesterification of the ester as by forming a di-
or monoglyceride by alcoholysis, followed by esterification with the ~ -
modifying acid.
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Also included among the drying oils are alkyd resins prepared
utilizing drying oil; esters of epoxide with fatty acids, such as those
mentioned above, including esters of diglycidyl esters of polyhydric
compounds, as well as other mono-, di- and polyepoxides; and drying oil
fatty acid esters of resinous polyols such as homopolymers or copolymers
of unsaturated aliphatic alcohols, for example, allyl alcohol or methallyl
alcohol including copolymers of such alcohols with styrene or other`
ethylenically unsaturated monomers. Esters of epoxies with fatty acids
such as esters formed from linoleic acid and epichlorohydrin-Bisphenol A
condensates are particularly desirable for use in electrodeposition.
The polybutadienes used in the practlce of the invention are
known in the art as exemplified by U. S. Patent 3,789,046 to Heidel. By
the term "polybutadiene" is meant a homopolymer of a conjugated diolefin
containing from 4 to 6 carbon atoms such as 1,3-butadiene, isoprene,
piperylene or mixtures thereof. Homopolymers and copolymers of 1,3-
butadiene ~butadiene) are preferred. Any polymer or copolymer of butadiene
which is a liquid at room temperature can be employed as a starting polymer
for the reaction of the process of the present invention, for example,
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polybutadienes having a viscosity of from ~4~ to ~ 3 centipoises at 20C.
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and preferably from about ~h~ to 50,000-centipoises at 20C. Such polymers
preferably have a molecular weight (weight average) of about 400 to 10,000;
more preferably, from about 700 to 5000. Especially preferred are liquid
polymers having a viscosity of less than 5000 centipoises at 20C. and
preferably those having a viscosity of less than 1000 centipoises at 20C.
The preferred starting polymers are liquid polybutadiene polymers
or copolymers produced in the presence of an organometal/nickel catalyst
system. These polymers generally contain butadiene polymer units of which
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at least 50 percent, preferably at least 60 percent, for example, 50-90
percent, have cis-1,4-structure, substantially all of the remainder,
for example, 10-50 percent, having trans-1,4-structure, with less than
3 percent, usually less than 1 percent having 1,2-vinyl structure.
Polybutadienes having incorporated therein up to 30 percent of another diolefin, -
for example, isoprene, or 2,3-dimethyl-1,3-butadiene or both, and/or an olefin,
for example, one or more of styrene, propene and butene-l may be used.
The unsaturated carboxylic acid utilized in forming the adduct
with the drying oil or polybutadiene can be an alpha, beta-ethylenically
unsaturated dicarboxylic acid or its anhydride such as maleic acid, fumaric
acid, itaconic acid, maleic anhydride and itaconic anhydride. Mixtures
of the same or different acids and anhydrides may also be utilized.
Ordinarily, the acid and anhydride employed should contain from about
4 to 12 carbon atoms, although longer chain compounds can also be ~mployed
if desired.
In preparing the adduct of the carboxylic acid or anhydride and
the drying oil, about 14 percent to 45 percent by weight of the unsaturated
acid anhydride should be reacted with from about 55 percent to 86 percent
by weight of the drying oil. If less than 14 percent by weight of the
unsaturated acid or anhydride is employed, the adducts will only be
partially water soluble unless water-soluble organic solvents are employed
to give water solubility. Even when so formulated, however, such adducts
will not give films which possess the desired degree of hardness required
in protective coatings for metallic surfaces, and may not have adequate
corrosion resistance. If more than 45 percent of acid or anhydride is
used, the resultant films will be seriously deficient in water resistance.
The reaction between the acid or acid anhydride and the drying
oil takes place readily without the use of catalyst and at temperatures
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within the range of 200 to about 275C., with the reaction preferably
being carried out between about 220 and about 250C.
In preparing the adduct of the carboxylic acid or anhydride
and polybutadiene, about 5 to 25 percent by weight of the unsaturated
acid or anhydride should be reacted with about 95 to 75 percent by weight
of the polybutadiene. If less than 5 percent by weight of the unsaturated
acid or anhydride is employed, the adducts will only be partially water
soluble unless water-soluble organic solvents are employed to give water
solubility. Even when so formulated, however, such adducts will not have
good bath stability and may not give films which possess the desired
degree of hardness required in protective coatings for metallic surfaces,
may not have adequate corrosion resistance. If more than 25 percent by
weight of the acid or anhydride is used, the resultant films may be
seriously deficient in water resistance. The reaction between the acid
or acid anhydride and the polybutadiene takes place readily without the
use of catalyst, although a copper compound may be used to control viscosity.
Reaction temperatures within the range of 190-220C. or higher are typical.
The adduct of the acid or acid anhydride with the drying oil or
the polybutadiene can be modified by partially esterifying the carboxylic
acid groups. For example, esterification can take place with an alcohol
or with a polyol. Partial esterification modifies film properties and, in
certain instances, has been found to increase throwpower.
The adduct obtained from the above reactants is not dispersible
in water. To make the material water dispersible, the acidity of the
drying oil adduct has to be at least 25 percent neutralized, and in the
case of the polybutadiene adduct, 30 percent neutralized with a water-
soluble inorganic base such as sodium or potassium hydroxide or an organic
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base such as ammonia or water-soluble amine or quaternary ammonium hydroxide.
Among the amines which may be u~ilized are water-soluble primary, secondary
and tertiary amines such as methylamine, ethylamine, propylaminej dimethyl-
amine, diethylamine, dlpropylamine, trimethylamine, triethylamine, tripropyl-
amine, monoethanolamine, monobutanolamine, diethanolamine, dibutanolamine,
triethanolamine, tributanolamine and the like. Examples of the quaternary
ammonium hydroxides which may be employed include trimethyl benzyl ammonium
hydroxide and trimethyl lauryl ammonium hydroxide.
Preferably, the pH of the water-dispersed, neutralized and
solubilized adduct should be maintained in the range of 8.0 to 9.2. If
the pH is substantially lower than 8.0, a physical separation of the
dispersion takes place.
The resinous compositions of the instant invention are prepared
by simply admixing the diene or the diene plus vinyl monomer in water
with an oil-soluble free radical-type catalyst, and the amine or ammonia
solubilized salt of the adduct of the unsaturated carboxylic acid or
anhydride and a material selected from the class consisting of drying
oils and polybutadienes. The reaction mass is then heated for a period
of about 2 to 20 hours.
In order to obtain a product suitable for use in electro-
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deposition, it is desirable that the salt of t~e a'dduct of the~drying oil
and unsaturated carboxylic acid or anhydride be present in amounts of at
least 5 and preferably 20 to 75 percent by weight of the total reactants.
As has been mentioned above, polymerization of the diene with
the salt of the adduct of an unsaturated carboxylic acid or anhydride and
a member selected from the class consisting of drying oils and polybutadiene
is conducted in the presence of an oil-soluble free radical-type catalyst.
These types of catalysts have been found to give products suitable for
electrodeposition.
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1079 Z Zl
Examples of suitable oil-soluble catalysts include azobisiso-
butyronitrile, cumene hydroperoxide, diisopropylbenzene hydroperoxide,
diazothioether, para-methoxyphenyl diazothio-(~-naphthyl) ether and
para-chlorobenzyl peroxide. Cumene hydroperoxide and azobisisobutyronitrile
are the preferred free radical initiators. These catalysts bring about an
approximately 100 percent conversion of the diene into polymer product.
Other free radical polymerization catalysts such as others mentioned
above have not been found to give as high a conversion.
Besides the free radical catalyst, a chain terminator such as
tertiary-dodecyl mercaptan, 2-mercaptoethanol, isooctyl mercaptopropionate,
- para-octyl mercaptan, or 3-mercaptopropicnic acid is preferably incorporated
into the polymer charge. Chain terminators provide the necessary control
over molecular weight to give products having the required viscosity for
electrodeposition. Tertiary-dodecyl mercaptan is preferred because it
results in higll conversion of diene into polymer product. Other chaini
terminators such as those mentioned above give lower conversions.
For electrodeposition, the above-described resinous products
are dispersed in water to about 1 to 30 percent by weight resin solids
aqueous dispersions. The term "aqueous dispersion" as used within the
context of the present invention is intended to cover two-phase, trans-
lucent, aqueous-resin systems, especially those in which the aqueous phase
forms the continuous phase, and is also intended to cover homogeneous
aqueous solutions which appear optically clear. The aqueous dispersions
of the present invention have dispersed phases which have average particle
size diameters of about O.l to 5 microns.- The dispersed phase may be
spherical or elongated in shape or actually invisible by microscopic
investigation.
1~79~2~
The products can be employed as such to electrodeposit clear
films, ~ut ordinarily they are used as a vehicle along with a pigment
composition. The pigment composition used may be of any conventional
type, comprising, for example, iron oxides, lead oxides, strontium
chromate, carbon black, titanium dioxide, talc, barium sulfate and tlle
like, as well as combinations of these and similar pigments. Color
pigments such as cadmium yellow, cadmium red, phthalocyanine blue,
chromic yellow, toluidine red, hydrated iron oxide and the like may
also be included. Dispersing or surface active agents which should be
of non-ionic or anionic type or a combination of these types can also
be employed.
Usually, the pigment and surface active agent, i~ used, are
ground together in a portion of the vehicle to make a paste, and this
is blended with the major portion of the vehicle to produce the coating
composition. There may also be included in the coating compositions -
additives such as anti-oxidants, wetting agents, dryers, anti-foaming
agents, suspending agents and the like. It is often desirable to include
small amounts of water-miscible organic solvents, which may be added to
the resinous vehicle to aid in handling and processing. 4-Methoxy-4-
methyl-pentanone-2 is a preferred solvent of this type, but others, such
as dioxane and glycol ethers, can also be used.
It has been found that in most instances desirable coatings
are obtained using pigmented compositions containing weight ratios of
pigment to ve!licle of not higher than about 1.5 to 1 and preferably not
higher than about 1 to 1. If the composition has too high a pigment-to-
vehicle ratio, the electrodeposited film may exhibit poor flow character-
istics.
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In formulating the water-dispersed compositions, ordinary
tap water may be employed. However, such water may contain relatively
high levels of cations, which, while not ordinarily rendering the process
inoperative, may result in variations in the properties of the bath when
used for electrodeposition. In such cases, it is often desirable to
utilize deionized water from which the free ions have been removed, as
by passage through an ion exchange resin.
; The compositions such as described above are applied by placing
the aqueous bath containing the composition in contact with an electrically
conductive anode and an electrically conductive cathode and passing an
electric current between the electrodes. The electrodes may be of any
electrically conductive material, usually metal such as iron, steel,
aluminum, galvanized steel, phosphatized steel, zinc, copper, or other
metal. Other electrically conductive materials or non-conductive materials
such as glass, plastics, etc. having a surface made conductive by appli-
cation of a conductive coating or a layer, can also be coated in accordance
with the invention. Upon passage of electric current between the anode
j and the cathode, while in contact with the bath containing the coating
- composition, an adherent film of the coating composition is deposited
on the anode.
Generally speaking, the conditions under which the electro-
deposition process is carried out are those conventionally used in the
electrodeposition methods employed heretofore. The applied voltage may
be varied greatly and can be very low, for example, 1 volt, or very high,
for example, several thousand volts or even higher. Particularly
advantageous of the products herein is that they permit the use of higher
voltage without the problems usually encountered; thus, they are often
electrodeposited from about 200 to about 500 volts.
1~)79ZZl
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Electrodeposition produces an adherent film which is very high
in solids content, often 80 to 90 percent or even higher, which provides -
the important advantage that the film will not readily run or wash.
Although the articles so coated can be used, if desired, without additional
baking or other drying procedures, addltional baking or drying of the
film is usually accomplished inasmuch as there is little or no solvent
to be evaporated from the film. Ordinarily, the coated articles are baked
- at a temperature of about 125C. to about 200C. for about 10 minutes to
,l 30 minutes.
The invention will be described further in conjunction with
several examples showing the method and practice of the invention. These
examples, however, are not to be construed as limiting the invention to
their details. All parts and percentages by weight are based upon non-
volatile solids content unless otherwise indicated.
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Example I
An epoxy-fatty acid ester was prepared by charging the following
to a glass reactor:
Charge Parts by Wei~ht
EPON 828 1730
PAMOLYN 200 5500
xylene 172
benzyl dimethylamine 6
stannous octoate 6
Condensation product of epichlorohydrin and Bisphenol A, having an
epoxide equivalent of about 185-192, commercially available from Shell
Chemical Company.
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10792;~1
A fatty acid composition containing 17 percent by weight oleic acid,
70 percent by weight linoleic acid, and 11 percent by weight conjugated
linoleic acid, which is commercially available from Hercules Inc.
The charge was heated to about 195C. and held for one hour
and then raised to about 250C. and maintained at this temperature until
an acid value of 5.92 was obtained. The reaction mixture was sparged
with nltrogen for 15 minutes and then cooled to room temperature, àt
which time 1340 parts by weight of maleic anhydride was added to the
A reactor. The reaction mixture was then heated to about-~5~C. and
held for two hours and then sparged with nitrogen for approximately
15 minutes. The reaction mixture was cooled to room temperature. The
epoxy-fatty acid ester had a Gardner-Holdt viscosity at 75 percent solids
in xylene of Y-. The epoxy-fatty acid ester at 100 percent solids was
dispersed to a solution of water and triethylamine (15.75 percent by
weight based on weight of epoxy-fatty acid ester) to form a 30 per~ent
by weight resin solids solution.
Example II
The following was charged to a reaction vessel capable of
maintaining pressure.
Charge Parts by ~1eight
epoxy-fatty acid ester of
Example I (39.5% resin solids) 71.3
deionized water 110.2
styrene 25.7
azobisisobutyronitrile 2.6
tertiary-dodecyl mercaptan 2.6
surfactant mix 5.8
i3
~0792Zl
The surfactant mix comprised 5.8 parts by weight of a fluorocarbon
commercially available from 3M Corporation as FC-430, 283.0 parts by
weight of deionized water and 1.1 parts by weight of triethylamine.
Sixty (60) parts by weight of 1,3-butadiene was charged to the
reaction mixture under 30 pounds per square inch gauge pressure using a
gear pump. The reaction mixture was then heated to 73C. and held for
about 10 hours, after which time the reaction mixture was cooled tQ
room temperature.
The reaction product prepared as described above was then
diluted with deionized water to form a 20 percer.t solids electrodeposition
bath. Steel panels electrocoated with this bath at a bath temperature of
23C. for 2 minutes at 400 volts produced smooth, hard coatings of
approximately 1 mil thickness.
Example III
The following ingredients were charged to a reaction vessel
suitable of maintaining pressure.
Charge Parts by Weight
epoxy-fatty acid ester of
Example I 3194.2
fatty acid soap mixture942
deionized water 6880
cumene hydroperoxide 78.7
tertiary-dodecyl mercaptan 78.7
styrene 1181.0
1,3-butadiene 2755.5
surfactant mix (see Example I) 29.5
14
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l~9ZZl
lAdduct of 329.7 parts by weight of fatty acid mixture of 17 percent
by weight oleic acid, 42 percent by weight linoleic acid, 40 percent by
weight conjugated linoleic acid, which is commercially available from
Hercules Inc. as PAMOLYN 300, and 118 parts by weight of triethylamine
dispersed in 329.5 parts of isopropanol and 164.8 parts of deioni~ed
water.
The charge was heated to 77C. and maintained for four hobrs,
after which time an additional 19.7 parts by weight of cumene hydroperoxide
was added. The temperature was raised to 190C. over a two-hour period
and an additional 19.7 parts by weight of cumene hydroperoxide added.
The temperature was maintained between 172-190C. for an additional two
hours and a final 19.7 parts by weight of cumene hydroperoxide added.
The reaction mixture was then cooled to room temperature. The resinous
mixture had a pH of 7.8, a Brookfield viscosity of 7 centipoises and a
solids content of 38 percent.
Example IV
- A pigment grind (A) ground to a 7.25 Hegman was prepared from
the following charge:
Charge Parts by Weight
grinding vehicle 5335.8
red iron oxide 2853.3
coal dust 950.7
lead silicate 557.4
strontium chromate 290.3
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lThe grinding vehicle was a 39.5 percent resin solids solution
prepared as described in Example I with the exception that diethylamine
was used for solubilization instead of triethylamine.
To the pigment grind (A), prepared as described above, was
added the following mixture (B): -
1336 parts of pine tar
87 parts of triethylamine
425 parts of 4-methoxy-4-methylpentanone
To the mixture of (A) and (B) was added 268 parts of 2,6-di-
tertiarybutyl-4-methylphenol (anti-oxidant), 268 parts of 4-methoxy-4-
methylpentanone and 1294 parts of the grinding vehicle described
immediately above to form a pigment paste.
An electrodeposition bath was prepared by dispersing 276 parts
by weight of the pigment paste with 8.4 parts by weight of triethylamine
and 1696.6 parts by weight of an aqueous dispersion of resinous vehicle
of Example III (34 percent solids) in 1706 parts by weight of deionized
water to yield a bath of 20 percent solids and a pH of 9.55. The bath
had a rupture voltage of greater than 550 volts and a General Motors
throwpower of 13-1/4 inches deposited with a 17 inch dip.
Both untreated and zinc phosphated steel panels were coated
with this bath, bath temperature 18.5C., at 350 volts for two minutes
to give a film of 0.65 mil thickness. After 14 days salt spray exposure
under conditions described in ASTM B-117-73, the coated, untreated steeI
panel showed 1-1/2 inch creep from the scribe line and the treated steel
panel showed about 1/64 to 1116 inch creep from the scribe line.
16
1(~79~
Example V
An electrodeposition bath was prepared by dispersing 303.6
parts by weight of the pigment paste prepared as described in Example IV
with 9.2 grams of triethylamine and 1595 parts by weight of the resinous
vehicle of Example II t40 percent solids) in 2075 parts by weight of
deionized water to yield a bath of 20 percent solids and a pH of 9.4-9.55.
The bath had a rupture voltage of greater than 550 volts and a Genèral
Motors throwpower of 14-3/4 inches deposited with a 17 inch dip.
Both untreated and zinc phosphated steel panels were coated
with this bath, bath temperature 18.5C., at 500 volts for two minutes
to give a film of 0.6-0.7 mil thickness. After 14 days salt spray
exposure under conditions described in ASTM B-117-73, the coated,
untreated steel panels showed 1-1/2 inch creep from the scribe line and
the treated steel panels showed about 1/64-to 1/16 inch creep from the
scribe line.
Example VI
A resinous product prepared according to U. S. Patent 3,258,437
was evaluated for electrocoating. A maleinized linseed oil backbone was
first prepared as described in Example IV of U. S. Patent 3,258,437. The
Gardner-Holdt viscosity of the product was Z, somewhat higher than the K
reported in the example. Styrene and butadiene were then reacted with
the product as generally described in Example VI of the patent to form
a resinous composition which was diluted with additional water to form a
15 percent solids electrodeposition bath. Electrodeposition was conducted
on a series of steel panels at varying voltages until a drop-off in
1079221
amperage was observed. This voltage was then selected for electrocoating.
Steel panels were electrocoated with a 15 percent solids bath at a
temperature of 23C. for two minutes at 300 volts. The coated panels
were then baked for 20-25 minutes at 177C. to give rough, thick,
uneven and cratered coatings, looking like burned toast.
Example VII
A resinous product was prepared according to Examyle II above
with the exception that 2.6 parts by weight of potassium persulfate was
used instead of the azobisisobutyronitrile. Electrodeposition was
conducted as generally described above in Example IV with a 15 percent
solids bath at a temperature of 23C. for two minutes at 20 volts.
The coated panels were baked for 20-25 minutes at 177C. to give coatings
similar in appearance to those described above in Example VI.
Example VIII
A resinous product similar to Example VI above was prepared
with the exception that azobisisobutyronitrile was used instead of the
potassium persulfate free radical catalyst. The charge for preparing
the product was as follows:
Charge Parts by Weight
maleinized linseed oil
(see Example VI)135.0
ammonium hydroxide 1.1
deionized water 320.0
azobisisobutyronitrile2.2
styrene 64.8
butadiene 151.2
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Six hundred twenty-three (623) parts by weight of the resinous
product prepared as described above was diluted with 1177 parts by weight
of deionized water to form an electrodeposition bath. Electrodeposition
was conducted on zinc phosphated steel panels, untreated steel panels
and aluminum panels at 300 volts for two minutes at a bath temperature
of 23C. The coated panels were then baked for 20 to 30 minutes at
177C. to give smooth coatings of about 0.7 mil thickness.
Example IX
The resinous product of Example VIII was prepared again with
the exception that tertiary-dodecyl mercaptan, a chain transfer agent,
was present in the charge. The charge was as follows:
Charge Parts by Weight
maleinized linseed oil135.0
ammonium hydroxide 1.1
deionized water 310.0
azobisisobutyronitrile 6.5
tertiary-dodecyl mercaptan6.5
styrene 64.8
1,3-butadiene 151.2
Six hundred (600) parts by weight of the resinous product was
diluted with 1400 parts by weight of deionized water to form an electro-
deposition bath. Electrodeposition was conducted on zinc phosphated
steel panels, untreated steel panels and aluminum panels at voltages
of from 280 to 300 volts for two minutes, bath temperature 23C. The
coated panels were then baked for 20 to 30 minutes at 177C. to give
smooth films of approximately 1 mil thickness.
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Example X
A maleinized polybutadiene was prepared by charging 220 parts
by weight of polybutadiene, 0.75 parts by weight of copper naphthanate,
0.08 parts of acetyl acetone and 8.4 parts by weight of xylene or a
reaction vessel under a nitrogen blanket. The polybutadiene had a
molecular weight of about 900 and was sold commercially by Lithium
Corporation of America as LITHENE QL. The mixture was heated to 99C.
and charged with 33 parts of maleic anhydride. The reaction mixture
was heated to 193C. and held at this temperature until a Gardner-Holdt
viscosity of F was obtained (15 parts resin diluted with 5 parts xylene).
The mixture was then sparged for 1/2 hour with nitrogen, cooled to 99C.
and charged with 27.4 parts by weight of diacetone alc~hol. The mixture
was cooled to 71C. and charged with 19.3 parts of methanol and 0.22
parts by weight of benzyl dimethylamine catalyst. The temperature of
the reaction mixture was maintained at 71C. for one hour, cooled to 66C.
and then charged with 2.8 parts by weight of cresylic acid (anti-oxidant).
The resultant product had a Gardner-Holdt viscosity of Y and a Brookfield
viscosity of 17,500, spindle No. 4, 12 rpm, 23C.
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Example XI
The following was charged to a closed reaction vessel capable
of maintaining pressure:
Charge Parts by Weight
maleinized polybutadiene
of Example X 270.0
deionized water 286.5
azobisisobutyronitrile4.9
tertiary-dodecyl mercaptan 4.9
styrene 36.5
surfactant mix 1.2
1,3-butadiene 85.0
The surfactant mix comprised 5.8 parts by weight of a fluorocarbon
commercially available from 3M Corporation as FC-430, 283.0 parts by
weight of deionized water and 1.1 parts by weight of triethylamine.
The charged vessel was closed, heated to 70C. and held for
about 16 hours with agitation to complete reaction.
Example XII
A pigment grind ground to a 7.5 Hegman was prepared from the
following charge:
Charge Parts by Weight
grinding vehicle 500
clay 210
lead silicate 70
strontium chromate 35
brown iron oxide 385
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lThe grinding vehicle was an epoxy-fatty acid ester prepared by charging
the following to a glass reactor:
Charge Parts by Weight
EPON 828 1730
PAMOLYN 200B 5500
xylene 172
benzyl dimethylamine 6
stannous octoate 6
ACondensation product of epichlorohydrin and Bisphenol A having
an epoxide equivalent of about 185-192, commercially available from
Shell Chemical Company.
A fatty acid composition containing 17 percent by weight oleic
acid, 70 percent by weight linoleic acid and 11 percent by weight
con~ugated linoleic acid, which is commercially available from
Hercules Inc.
The charge was heated to about 195C. and held for about one
hour and then raised to about 250C. and maintained at this temperature
until an acid value of 5.92 was obtained. The reaction mixture was
sparged with nitrogen for 15 minutes and then cooled to room temperature,
at which time 1340 parts by weight of maleic anhydride was added to the
reactor. The reaction mixture was then heated to about ~ ~ C. and held
A for two hours and then sparged with nitrogen for approximately 15 minutes.
The reaction mixture was cooled to room temperature. The epoxy-fatty acid
ester had a Gardner-Holdt viscosity at 75 percent solids in xylene of Y .
The epoxy-fatty acid ester at 100 percent solids was dispersed by combining
with a solution of water and diethylamine (18.4 percent by weight based
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on weight of epoxy-fatty acid ester) to form a 39.5 percent by weight
resin solids solution.
The pigment grind was thinned with 200 parts by weight of
deionized water to form the paste.
An electrodeposition bath was prepared by dispersing 1250 parts
by weight of the copolymer of Example XI and 156.5 parts by weight of
the pigment paste prepared as described above in 1744.5 parts by weight
of deionized water; 5.7 parts by weight of 4-methoxy-4-methyl pentanone
and 0.5 percent by weight (based on weight of copolymer) of 2,6-di-
tertiary butyl-4-methyl phenol (anti-oxidant) was added to complete the
dispersion. The bath had a solids content of approximately 20 percent
and a pH of 8.5. Both untreated and zinc phosphated steel panels were
electrocoated with the bath, the bath temperature being 23C. at 225-275
volts to prodoce smooth dull fil~s of about l mil thic~ness.
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