Note: Descriptions are shown in the official language in which they were submitted.
-- 1 --
COATING_RESIN COMPOSITION
This invention is directed to a water dispersible
polymeric vehicle for use as a coating binder in coating
compositions. More specifically this invention relates to
a polymeric vehicle which comprises a reaction product of
an epoxy polyol ester resin with unsaturated monomers ~ ~
which when neutralized with a base provides a water -
dispersible polymeric vehicle for use in coating
compositions.
Environmental concern has become increasingly
important in recent years. This concern not only extends
to preservation of the environment for its own sake, but
extends to safety for the public as to both living an ~ ~ `
working conditions. Volatile organic emissions resulting
15 from coating compositions which are applied and used by ~; ;
industry and by the consuming public are often not only -
unpleasant, but contribute to photochemical smog. Fire - ~
and health hazards of organic solvents also are well -
known. Governments may or have established regulations ~ -
20 setting forth guidelines relating to volatile organic ~ -
compounds (VOCs) which may be released to the atmosphere.
The United States Environmental Protection Agency (EPA)
has established guidelines relating to the amount of VOCs
released to the atmosphere, such guidelines being
scheduled for adoption by the states of the United
States. Guidelines relating to VOCs, such as those of the -
EPA, and environmental concerns are particularly pertinent `
to the paint and industrial coating industry which uses -
organic solvents which are emitted into the atmosphere. -
Coating compositions such as enamels include
epoxy resin esters as polymeric vehicles for coating
binders. These epoxy resins usually require an organic
solvent to reduce or disperse them. The present invention ;~
not only provides a water dispersible polymeric vehicle ~-~
i
' ~,'.,`
for an air dried coating, but also provides a resin which
may be used as a polymeric vehicle for a coating binder
for coatings such as enamels where the coatings have
improved visual appearance, higher gloss, increased
humidity resistance and improved adhesion. In an aqueous
air drying coating composition, the polymeric Yehicle of
this invention when incorporated into a coating
composition provides a coating composition with very good
hydrolytic stability in aqueous solution and rapid drying
capabilities. Moreover, the polymeric vehicle of the
invention may be cross-linked with cross-linking agents in
baked coating systems.
As used herein coating binder is the polymer
portion of a coating film which has hardness, adhesion,
humidity resistance, impact resistance and other
measurable coating film properties. Pigments, solvents -
and additives may be mixed with the polymeric vehicle to
provide a formulated coating composition. The formulated
coating composition is that which is applied to a
substrate and after baking an cross-linking or after any
solvent, or diluent, such as water, is evaporated a -
coating film remains.
A resin which provides a water dispersible
polymeric vehicle which is based on an epoxy ester is
described in United States Patent No. 4,166,054 to Meeske
et al. The resin described in Meeske et al. is based
solely upon an epoxy resin. It has been found, however,
that coating compositions which comprise resins based
solely upon an epoxy resin provide coatings with low
gloss, gloss loss over time under high humidity and a
proclivity to whiten during exposure to humidity.
A resin which provides a water dispersible
polymeric resin based solely upon an epoxy ester resin or
solely upon a polyol resin ester is described in U.K.
1,550,822. It has been found that coating compositions
,' ~''-
which comprise resins based solely upon polyol esters have
relatively slow dry times and provide coatings with loose
adhesion and corride relatively rapidly in corrosive
environments.
The invention provides a polymeric vehicle which
after neutralization is a water dispersible polymeric
vehicle for an aqueous formulated coating composition with
very good hydrolytic stability and rapid drying
characteristics. The polymeric vehicle of this invention -~
provides a coating binder, which, when applied on a
substrate, exhibits good adhesion to the substrate, high
gloss, and moisture resistance.
The polvmeric vehicle of the invention is the - - -
reaction product of from about 25 to about 9o parts by
weight based upon the weight of solids of the polymeric
vehicle of an epoxy polyol ester resin and from about 10
to about 75 parts by weight based upon the weight of
solids of the polymeric vehicle of a blend of two or more ~ ;
unsaturated monomers having polymerizable double bonds
such that the resulting polymeric vehicle has an acid
value in the range of from about 15 to about 100,
preferably about 40 to about 70, and most preferably about --
60 to about 65. The epoxy polyol ester resin is a
reaction product of from about 10 to about 65 parts by
weight based upon the weight of solids of the epoxy polyol
ester resin of an epoxy resin which has an average epoxy
functionality of from about 1.8 to about 2.5 and an
average epoxy equivalent weight in the range of from about
150 to about 800, from about 1 to about 30 parts by weight -
30 based upon the weight of solids of the epoxy polyol ester -~
resin of a polyol having at least three hydroxyl groups
and a molecular weight of at least about 120 and from
about 25 to about 85 parts by weight based upon the weight
of solids of the epoxy polyol ester resin of an ~-
unsaturated partially conjugated fatty acid having 16 to
20 carbon atoms having double bonds of which from about 20
to about 50% are conjugated. Preferably the partially
conjugated fatty acid is a C18 acid with from about 25
- 4 -
to about 30 percent conjugation. Generally these acids
are used as a mixture of acids having 16 to 20 carbon
atoms. A preferred epoxy resin which may be used in the
invention is a reaction product of bisphenol A also known
as 2,2 bis(4 hydroxy phenyl) dimethyl methane or
bisphenol F also known as 2,2 bis (4 hydroxy phenyl)
methane and epichlorohydrin having an epoxide equivalent
weight of from about 150 to about 800 and preferably about
380. A~ will be discussed in further detail, the epoxy
polyol ester resin is not just a blend of a polyol ester
and epoxy ester resin, but rather, is a unique reaction
product from the reaction of the epoxy resin, polyol and
unsaturated partially conjugated fatty acid. As a result
the method of making the epoxy polyol ester resin is
important to the invention. Two methods to make the epoxy
polyol ester resin are described herein one of which is an
important alternative embodiment of the invention. In one
method (hereinafter referred to as "method 1"), the epoxy
resin starting material undergoes a catalyzed chain
extension with bisphenol A, bisphenol F, aliphatic or
cycloaliphatic diols or thios to obtain the proper epoxy
equivalent weight which step which also includes an
addition of part of the unsaturated partially conjugated
fatty acid for esterification. This reaction is carried
out at a temperature range of from about 400 to about
475-F. When conjugated acid and chain extender such as
bisphenol A are reacted with the epoxy resin starting
material, the relative amounts of conjugated acid and
bisphenol A used in the reaction are dependent upon one
another. In total the equivalents of conjugated acid and
bisphenol A should be sufficient to react with
substantially all of the epoxy and hydroxyl groups
available on the epoxy resin starting material. At ~;
minimum in method 1 an amount of conjugated acid is used
to inhibit gelling of the epoxy polyol resin and
facilitate processing thereof. The chain extension
reaction is followed by further addition of the
unsaturated partially conjugated fatty acid for
- 5 - -
esterification. This reaction is generally carried out at
a temperature range of from about 400 to about 475~F.
Suitable chain extension catalysts include triphenyl
phosphine and aryl phosphonium halides. Suitable
esterification catalysts include zirconium salts of an
organic acid, dibutyl tin oxide, tetraisobutyl titanate,
butyl stannoic acid and monobutyl phosphate. Method 1 is
an important embodiment of the invention. In connection
with method 1, epoxy equivalent weight ranges are a -~
calculated value based upon equivalencies of reactants.
In a second method of making the epoxy polyol ester resin -
(hereinafter referred to as "method 2"), the starting ~ -
epoxy undergoes a catalyzed chain extension without the
unsaturated partially conjugated fatty acid. In method 2
the partially conjugated fatty acid is added after the
chain extension reaction.
After the epoxy polyol ester resin is made, the
polymeric vehicle is obtained by reacting the epoxy polyol
ester with a blend of unsaturated monomers at a ~
temperature in the range of about 250 to about 350-F. ~ ;
Each of the monomers in the blend have double bonds which i -
are polymerizable in a free radical reaction using free
radical initiators such as dicumyl peroxide, tertiary -
butyl perbenzoate, ethyl-3,3-di(tertiary amyl peroxy)
butyrate and cumene hydroperoxide. This blend comprises a
first monomer which is an unsaturated monobasic acid with
a polymerizable double bond and a second monomer which -
also has a polymerizable double bond. The monomer blend
may contain monomers in addition to the first and second
monomers. The double bonds of both monomers are
polymerizable through a free radical mechanism. The
amount of unsaturated acid monomer may vary, but ~;;
sufficient unsaturated monobasic acid should be in the -
monomer blend to be in an effective amount to bring the
acid value of the polymeric vehicle in the range of from
about 15 to about 100. In a preferred form of the
invention which includes an epoxy based upon bisphenol A
3 ~ ~ :
-- 6 --
and epichlorohydrin, at least about 8 parts by weight non
acid second monomer based upon the weight of the solids in
the polymeric vehicle will be required.
Suitable commercially available epoxy resins for
use in this invention include: Araldite GY6010 which is
an epoxy resin based on bisphenol A and epichlorohydrin
and which has an epoxy equivalent weight in the range of
from about 182 to about 192, Araldite PY307 which is an
epoxy novalac resin based on bisphenol A and which has an
epoxy functionality of 2.4, Araldite PY306 which is based
on bisphenol F and which has an epoxy equivalent weight in
the range of from about 159 to about 170, and XB4122 which
is a flexible epoxy based on bisphenol A and which has an
epoxy equivalent weight in the range of from about 333 to
about 357 are available from Ciba-Geigy Chemical Company;
DER-736 which is a flexible epoxy which has an epoxy
equivalent weight in the range of from about 175 to about
205 from Dow Chemical Company and DRH-151 which is an
aliphatic epoxy having an epoxy equivalent weight from ~ -
about 232 to about 238 from Shell Chemical Company.
Generally the starting epoxy resin material can have an
average epoxy equivalent weight in the range of about 150
to about 400 prior to chain extension.
Polyols which are suitable for use in the
invention have a molecular weight in the range of from
about 120 to about 5,000, preferably from about 250 to ~ -~
about 2,000 and include RJ101, which is a styrene-allyl
alcohol copolymer from Monsanto Chemical Company which has
a hydroxyl content of about 7.7, an equivalent weight of ~ ;~
about 220, a number average molecular weight of 1150 and a ~ ~-
weight average molecular weight of about 1700;
ditrimethylolpropane which has the
formula
' :; ' ~ ;''~.'
~- ' ':: " .' . .: -
~ 7 ~
' ' ,
;,,:.~,' ~
l 2H5 C2H5
H:)C!~2-- C--C''2 0-CH2--C--CH20H ~ -
CH2OH CH2OH
- is commercially available from Perstorp Chemicals; :~
dipentaerythritol which has the formula ~ :~
1 0 ~ ~ -
CHnOH CH~OH
HOCH~7--C--CHn--O--CH~--C--CHnOH
, ~ . .' '~
CHnOH CH~OH .
1 5
- is commercially available from Hercules Chemical
Company: neopentyl polyol which is an ester neopentyl
polyol having an equivalent weight of about 50,
functionality of 5 and a hydroxyl content by weight .. ::
percent of 30 to 33% and is available from Pitman Moore
Chemical under the designation XR101. Hul's
Ketone-Aldehyde resins sold under the designations SK and
BL 1201 may also be used as polyols, the SK polyol having
the general formula .~
_ _ ;
- fH - CH2 - fHCH2
fHOH fHOH
R R n :
and the BL 1201 polyol having the general formula ..
- 7H - CH2 - CH - CH2 -
-O-C-HN-R2-HN-C-O-CH CHOH
~ l .. '.,:
O O R . R n . ~ :
: :.
~i~
- 8 -
Suitable unsaturated partially conjugated fatty
acids which may be used in the invention include
dehydrated caster fatty acids, conjugated sunflower fatty
acids and conjugated tall fatty acids. Pamolyn 327-B is
an example of a commercially available C18 unsaturated
tall type fatty acid which is about 27% conjugated, from
Hercules Chemical Company.
Suitable unsaturated monobasic acids for the
monomer blend used in the invention include acrylic acid,
methacrylic acid, maleic acid, and conjugated fatty
acids. Any carboxylic acid with a double bond which is
polymerizable through a free radical mechanism is believed
appropriate as a functional component in the blend. ~ -
Styrene, vinyl toluene, paramethyl styrene, N-vinyl
pyrolidone, acrylonitrile and acrylic esters or any other
monomer with a double bond which is polymerizable through
a free radical mechanism with the other monomers including
acid monomer and conjugated fatty acid are suitable as the
second monomer in the monomer blend. Further,
hydroxylalkyl acrylates and hydroxyalkyl methacrylates may
be added to the blend to modify the polymeric vehicle,
which then is neutralized, will be suitable for a
thermosetting or baking cure system. As used in this
context alkyl means sn aliphatic group with four or less
carbon atoms. This polymeric vehicle is cross-linked with
a cross-linking resin such as an aminoplast resin.
Cross-linking resins in such a system may include hexakis
(methoxymethyl) melamine resin ~HMMM).
A highly preferred embodiment of the invention
includes the use of Araldite GY6010 which is chain
! ~ I extendediwith bisphenol A to an average epoxy equivalent
weight of about 380. In this preferred embodiment the ; -
following ingredients are used in the preferred ranges
shown:
,':''~ ,~'''''.' -'
: ., :'~, -,
~i ... ~ .:. . ;., ..:
~,'
3 ~ ~ :
.
g ,
Parts by Weight
Based On
Reactant Total Solids ~ ;
GY 6010 16 to 20
bisphenol A 3 to 5
Pamolyn 327-B 31 to 35
RJ 101 3 to 6
Styrene 26 to 30
Acrylic acid 8 to 11 -
Free Radical Catalyst
such as di-cumyl
peroxide 1 to 3 -
1 0
After the polymeric vehicle is made, it is
neutralized with a base to make a neutralized water
dispersible polymeric vehicle. The base can be a variety
of amines such as triethylamine, dimethyaminoethanol and ~-
diisoproylamine. The base can also be ammonium hydroxide
or ammonia.
The following examples are provided to illustrate ; ~
the invention more fully; however, they should not be ~ - --
construed a~ limiting the scope of the invention, many
20 variations of which are contemplated. -
EXAMPLE 1
The following procedure describes method 1 for
making the epoxy polyol ester resin of the invention using
the following ingredients. ' ;~
Parts
by
Ingredients For Epoxy Polyol Ester Resin Weight
(1) Araldite GY6010 27.34
(2) Bisphenol A 6.39
(~3) Triphenyl Phosphine l0.02
(4) Pamolyn 327-B 25.62 -
(5) Intercar Zirco 12% - Catalyst 0.10
(6) Xylene Reflux Solvent 2.23 ;;-
61.73
(7) Pamolyn 327-B 25.22
(8) RJ-101 936 64
Less reaction water (1.46)
Less stripped xylene (2.23) -
90. 00 ~ -
(9) Butyl Cellosolve (butoxyethanol) 10.00
-- 10 --
The Charge
GY6010 epoxy, bisphenol A, triphenyl phosphine
catalyst, initial Pamolyn 327-B fatty acid, xylene and 12
Zirconium Intercar catalyst are charged into a 4-necked
round bottom flask equipped with agitation, heat source,
thermometer, nitrogen inlet, Dean-Stark trap and
condenser. Initial fatty acid charge (see #4 above) in
equivalents is equal to: oxirane equivalents of the GY6010
charge minus hydroxyl equivalents of the bisphenol A
charge.
Epoxy Advancement/Esterification
The solution is heated to 450F maximum under
xylene reflux and nitrogen sparge. When an acid number of ~
15 2 or less is attained, the remaining Pamolyn 327-B fatty --~ -
acid (see #7 above) and RJ-lOl are added to the solution.
After the latter addition the resulting solution is heated
to 450F maximum while removing reaction water. The
reaction is continued until an acid number of 4 is
attained. The reflux xylene is allowed to evolve off while
the reactants attain an acid number of 3 or less~
thereafter the reaction mixture is cooled to 300F while
switching to nitrogen blanket and total condenser. The
resulting epoxy polyol ester resin product is thinned with
butoxyethanol. The epoxy polyol ester resin has the
following characteristics: ~
'' ,. ' :" ~'' ";
Gardner-Holdt Viscosity Z4-Z5 ;~
Viscosity, Stokes 0 25-C 63-98
% Non-volatiles 89.0-91.0
Acid Number, Solids about 3
Gardner Color, Appearance about lO, clear
' `
" ' ""'''~'"' ~
Copolymerization With The Honomer Blend
Ingredients For Polymer Vehicle
Parts
Ingredient Weight
(1) Epoxy Polyol Ester Resin 46.15 ~ -
(2) Butyl Cellosolve (butoxyethanol) 23.07 --
(3) styrene 20.03
(4) Acrylic Acid 6.85
(5~ Di Cup-R (dicumyl peroxide) 0.90
(6) Di Cup-R Booster 0.11
(7) Di Cup-R Booster 0.11
(8~ Butyl Cellosolve 2.78
100. 00 . ', ' '
The epoxy polyol ester resin is solubilized in
Butyl Cellosolve and the solution temperature is stabilized
within the range of 295 to 305CF. Premixed styrene, ~ -
glacial acrylic acid and dicumyl peroxide (80% of total)
are added continuously to the solution and at a constant
rate over 3 hours. After monomer addition the mixture is ;
heated for one hour and then dicumyl peroxide booster (10%
of total) is charged into the reaction mixture. The
reaction is heated for another hour and then the last
dicumyl peroxide booster (10% of total) is added. The
reaction is continued for another 1~ hours and then cooled5 to 160-F. After cooling the polymeric vehicle is filtered.
The resulting product has the following
characteristics:
Gardner-Holdt Viscosity Z5-Z6+ ~;
Viscosity, Stokes Q 25-C100-200
% Non-volatiles 68.0-72.0
Acid Number, Solids 63.0-69.0
Gardner Color, Appearance about 8
~ `
~'
.' ~. ~ .,,' .
- 12 -
EXAMPLE 2
The following procedure describes method 2 for
making the epoxy polyol ester resin of the invention with
the ingredients shown below.
Parts
by
Ingredients For E~oxy Polyol Ester Resin Weight
(1) Araldite GY6010 27.34
(2) Bisphenol A 6.39
(3) Triphenyl Phosphine 0.02
(4) Pamolyn 327-B 50.87
(5) Intercar Zirco 12% 0.10
(6) Xylene Reflux Solvent 2.23
(7) RJ-101 6.74
(8) Butyl Cellosolve 10.00
The Char~e
GY6010 epoxy, bisphenol A, triphenyl phosphine
catalyst and xylene are charged into a 4-necked
round-bottom flask equipped with agitation, heat source,
thermometer, nitrogen inlet, Dean-Stark trap and condenser.
Epoxy Advance~ent
The solution is heated to 250 F, under nitrogen
blanket. The exotherm is allowed to carry reaction
temperature to 410-420~F, and which is held for desired
~;; . .,
average epoxy equivalent weight which is about 380.
Esterification
The Pamolyn 327-B fatty acids, RJ-101 and 12%
Zirconium Intercar are charged into the epoxy solution and '""
the solution is upheated under xylene reflux and nitrogen
sparge to 450F maximum while removing reaction water.l The
mixture is reacted to an acid number of 4. The reflux -
xylene is allowed to evolve off while reacting to an acid
number of 3 or }ess. The reaction mixture is cooled to
300-F while switching to nitrogen blanket and total
condenser. The resulting epoxy polyol resin is thinned
with butoxyethanol.
~ -
~: :, ;,
~,-
- 13 -
Copolymerization With The Mono~er Blend
The epoxy polyol resin is reacted with a monomeric
blend having the same ingredients in the same proportions
under the same conditions as in Example 1 to provide a
polymeric vehicle.
EXAMPLE 3
Using method 1 described in example 1 to make the
epoxy polyol ester resin and polymeric vehicle, the
following ingredients were reacted.
Parts
by
Ingredients For Epoxy Polyol Ester Resin Wei~ht
Araldite GY6010 12 62
Bisphenol A 2 95
Triphenyl Phosphine 0.01
Pamolyn 327-B 23.48
Intercar Zirco 12% 0.05
RJ-101 3.11
Styrene 20.03
Acrylic Acid 6.85
Di-Cumyl Peroxide 1 12
Butoxyethanol 30 46
The epoxy advancement reaction temperature was -
452~F and the copolymerization temperature was 300.
Several resins (denominated Resins Rl to R8) in
addition to the polymeric vehicle of Example 3 were made
for testing. The method of making the resin which is
designated as Method 1 or Method 2, the ingredients and
reaction conditions to obtain each resin are shown in Table
I. After each resin was made, a water dispersible enamel
was prepared and tested with the test results shown in
Table II. Enamel film tests using the Resin of Example 3
and Resins Rl-R8, the results of which are shown in Table
II, were conducted on films which had been oxidatively
cured at room temperature. The enamels were prepared using
a sandmill and the following ingredients.
Parts --
by
Ingredient Weight
Copolymer Resin 98.6
Butoxyethanol 9-9
sec-Butanol 29.6
Ammonium Hydroxide 28%, aqueous5.0
Byk-301 (Byk-Chemie) Flow control additive. 2.0
Special Black 4 (Degussa Corp.)12.1
Aerosil R972 (Degussa Corp.) Fumed Silica
Extender Pigment 2.0
Copolymer Resin 182.0
Butoxyethanol 9.9
Activ-8 (R. T. Vanderbilt Company, Inc.)
Activator for metal driers. 1.0
5% Cobalt Hydro-Cure (Mooney Chemicals, Inc.) 2.5
Manganese Hydro-Cure II (Mooney
Chemicals, Inc.) 2.2 -~
Ammonium Hydroxid 28%, aqueous 8.0
Deionized Water
The procedure using the sandmill to make the enamels shown
in Table II was as follows.
; ;~
Sandmill Procedure For Making
The Enamels Shown In Table II
l. 98.6 g of resin was placed into a suitable
container for milling.
2. The resin was neutralized with 5.0 g of ammonium
hydroxide 28% with thorough stirring in of the ~-
ammonium hydroxide.
3. While agitating the resin ammonium hydroxide -~
mixture 11.8 g. sec-butanol, 9.9 g but~oxyethanol,
and 2.0 g Byk-301 were added to the mixture.
4. The pigments Special Black 4A (12.1 g) and Aerosil
R972 (2.0 g) were added and the agitation was
increased.
'':''':'-''','':
- 15 - ~
5. Sand was added to the mixture until the desired
consistency was achieved.
6. Sandmilling was continued until a grind of 7.0
national standard was achieved, then the material
was added to the letdown.
7. The letdown was prepared with 182.0 g of resin
neutralized by 8.0 g ammonium hydroxide 28%.
, -
8. 14.8 g sec-butanol, 9.9 g butoxyethanol, 1.0 g
Activ-8, 2.5 g 5% Cobalt Hydro-Cure, and 2.2 g
Manganese Hydro-Cure II were combined and added to
the resin ammonium hydroxide combination for the
letdown.
9. After the millbase and letdown were thoroughly
combined, deionized water 467.7 was stirred in.
10. Filter the paint to remove sand. -
11. The pH was adjusted to 8.0-8.5 with ammonium
hydroxide 28%, aqueous as needed.
': .
Enamels made with the polymerîc vehicles of the
invention also may be made using other known procedures
including those using a pebble mill.
EXAMPLE 4 ~ -
A water reducible baking resin using the polymeric
vehicle of Example 1 is made with the following
ingredients.
., ~
:
- 16 - ~ 3~ :
Parts
Ingredient Weight
Resin of Example 1 84.78 ~ -
Melamine Resin 11.15 -
Butoxyethanol 3-44 -~
Nacure 135 acid catalyst (a
dinonylnaphthalene disulfonic
aci~i catalyst) .64 ;,
After the blending of the resin of Example 1 with
a cross-linking resin and catalyst as described above, the
polymeric vehicle in the blend is neutralized and it is
ground and blended with pigments and additives following
the procedure in making the enamel described in Example 3.
Parts
Ingredient For Baking By ;~
Coating Composition Weight
Blended Bakable Resin
(with melamine) 140.2
Dimethylethanolamine 10.5 `~
Titanium Dioxide Ti-Pure R-960
(DuPont) 210.8
Zinc Phosphate J0852 (Nineral
Pigments Corp.) 38.7 -
Heliogen Blue L 6875 F (BASF
Wyandotte Corp. 0.5
Special Black 4 (Degussa Corp.)
Pigment 0.7
Aerosil F972 (Degussa Corp.
Fumed Silica Extender Pigment 4.0 ~ ; ~
Patcote 577 (C.J. Patterson Co.) -;
Antifoam Additive 2.5
Deionized Water 225.0
Blended Bakable Resin
(with melamine) 115.2 ,!'~" ;,',,`
Dimethylethanolamine 5.0i
Patcote 577 (C.J.Patterson Co.) 2.5 :~
Butoxyethoxyethanol 4.9
Butoxyethanol 25.8
Deionized Water 231.9
, . :-, :, ~ -
"' '"''"`"^ '~'.-
";
17
TEIE TESTS
The enamels made from the Resin of Example 3 andRl through R8 were drawn down on cold-rolled steel panels
for testing as described below.
Dry times were determined on films drawn down on
Lenata opacity charts. A Bird applicator was used to
deposit a film that results in a 0.9-1.1 mil. thick film
when dry. All other properties were determined on 0.8-1.0
mil. thick films on the cold-rolled steel panels. These
were applied using a DeVilbiss spray gun and 50 psig. air
pressure. ~ ~
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RESULTS AND DISCUSSION
AS TO ENAMEL TESTS
(A) RESIN VISCOSITY The Gardner-Holdt and the
viscosity in Stokes were determined at 25.0-C. Viscosity
and non-volatile are directly related.
(B) ENAMEL SOLUTION STABILITY Accelerated
stability was tested at 120-F to guickly obtain an
approximation of what stability will be at ambient
temperatures. The changes in pH and viscosity were
measured and recorded to measure stability. In water
soluble or dispersible oxidative cure ester type systems a
drop of both pH and viscosity i8 normal. These changes are
attributed to degradation of the polymer. While not
intending to be bound by any theory, it is believed that
hydrolysis reactions which generate additional carboxyl -
groups makes the system more acidic and lowers pH.
Hydrolysis along with alcoholysis cleave the polymer into
smaller molecules and this is generally the explanation for ~ ;
lower viscosity. Aside from Resins 3 and 8 the changes
seen here are relatively small.
(C) DRY TIMES Dry times were determined using a
Zapon tack tester using ASTM test D1640. Relatively small
changes in dry times between initial and aged enamels is
another indication of the good solution stability of these
enamels.
:: : ' ;
(D) VISUAL APPEARANCE This test indicates the -
30 degree to which patterns appear in the coating fil~. The - ~ -
patterns that develop in these films are known as picture ~ -~
framing, orange peel, crawling, and cratering. The
descriptions shown attempt to incorporate all these
effects. Anything below a good ratinq would not be
acceptable for most applications.
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- 21 -
(E) SALT FOG The salt fog test was conducted by
exposing the coated panel to a 5 percent sodium chloride
vapor at a temperature of 95-F for the stated time period. -~
Before exposure a large X was scribed through a section of
the coating to expose the substrate. A number of
measurements are made after exposing the panel. "Scribe
creep" is a measure of how far substrate corrosion has
progressed under the paint film from a leg of the X, and is
measured in millimeters. The higher the number the poorer
the corrosion protection. The ~adhesion~ value is obtained
by Scotch taping a leg of the X and estimating the -
percentage of coating that comes off of the taped area when
the tape is removed. The ideal would be no film removal
under these conditions.
The 5 percent removal reported for most resins is
considered good. This amount could almost be accounted for
by imperfections and/or dirt in the film.
(F) HUMID~~ Humidity resistance was tested by
exposing the coated panel in a Cleveland condensation
cabinet. The testing conditions were lOO-F and 100 percent
relative humidity. See ASTM D2247-68 for further
discussion of humidity testing. --
Properties evaluated on the exposed panels are
gloss, adhesion changes and degree of whitening. The
changes in gloss shown in the table are all negative ~;
changes; the films lose glos~. There is no measurable loss
of adhesion by our tests.
PROCESSING METHODS COMPARED
.
The advantages of method 1 can be seen by
comparing resins of Exa ple 3 and R5 in the Tables. There
sre only small difference~ in resin physical properties but
important film performance advantages of the resin of
Examp}e 3 sre much faster dry time, and much le~s gloss
,~
.: - .
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- 22 -
change and whitening (a L value) when exposed to humidity.
The higher initial gloss of the film of Resin R5 likely
relates to its slower dry.
EXAMPLE 3 PROVIDES A UNIOUE RESIN AS
COMPARED TO EPOXY ONLY AND POLYOL ONLY RESINS
Resin R4 is an epoxy only type resin which was made
like the resin of Example 3 with the polyol component
1o omitted. The advantages of the resin of Example 3 are very
evident in dry time, visual appearance (flow out on the
substrate), gloss and gloss loss and whitening during
humidity exposure and corrosion resistance.
Resin R3 is a polyol only type of resin which was
made like the resin of Example 3 with the epoxy component
omitted. The advantages of the Resin of Example 3 are seen ~ ;
in dry time and corrosion resistance. ~ ~ ~
.".., ,.,- ,... ...
THE RESINS OF THE INVENTION ARE SUPERIOR TO
A BLEND OF EPOXY ONLY AND POLYOL ONLY_RESINS -
Resin Rl is a physical blend of Resins R4 and R3.
The two resins are blended in a ratio that results in a
composition that would be substantially analytically the
25 same as that of the resin of Example 3. Because resin Rl
is such a blend, Table I refers to an extension temperature
in respect to the R4 portion of the blend. The dry time of
an enamel of this blend is much faster than that of either
of its components and nearly comparable to the dry of the
30 enamel based on the resin of Example 3. However, the film
of the resin blend has a hazy appearance and performs
poorly in humidity. The hazy appearance is an indication ~ s
of incompatibility between the two resins. m e resin of
Example 3 is a different polymer to provide a homogeneous i
35 resin. ;~
Another way in which the components (R4 and R3) can
be put together is to make the epoxy ester and the polyol
.
3~ ~
- 23 -
ester separately and mix these in the proper ratio and then
copolymerize the vinyl monomers with this mixture. This
was done in Resin R2. An advantage of combining and
processing the components in this manner over the physical
blend discussed above is better homogeneity. The evidence
for this is the absence of a milky appearance in R2. Many
other film properties of R2, however, are poorer than those
of a film from the physical blend. More importantly, when
compared to the enamel based on Example 3, enamel
performance of the latter i8 superior in dry time, visual
appearance, corrosion resistance and humidity resistance.
EFFECT OF EPOXY EOUIVALENT WEIGHT
Resins R6 and R7 were made from intermediates
having a lower and higher epoxy equivalent weights,
respectively, than the intermediate for the Resin of
Example 3. The satisfactory processing of these resins
shows that intermediates with a rather broad EEW range can
be used to make these copolymers. An analysi6 of the film
properties of R6 and R7, however, shows that a narrow EEW
range closer to that of the resin of Example 3 is
preferred.
Resin R6, which has a lower epoxy equivalent weight
(EEW), has poorer film performance than a fil~ based on the
resin of Example 3 in all properties evaluated except
adhesion.
The fil~ deficiencies of the higher EEW Resins R7
are dry time, flow out, and humidity resistance.
ESTER/VINYL RATIO
Resin 8 evaluates the effect of increasing the
ratio of ester component to vinyl component fro~ 60/40 to
75/25. Again, the successful preparation of this resin
shows that this ratio can vary over a wide range but film
properties of the enamel show that it must be carefully
0 3D L~ ~
- 24 -
balanced. The film propertie~ that deteriorate badly at
this ratio are dry time and corrosion resistance.
It should be understood that while certain
preferred embodiments of the present invention have been
illustrated and described, various modifications thereof
will become apparent to those skilled in the art.
Accordingly, the scope of the present invention should be
defined by the appended claims and equivalents thereof.
various ~eatureis of the invention are set forth in
the following claims.
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