Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF STABILIZING METAL PIGMENTS AGAINST GASSING
FIELD OF THE INVENTION
[0001] The present invention is related to polymeric compounds useful as a
combined corrosion or hydrolysis inhibitor and surface modifier for metallic
flake
pigment. The invention also pertains to coating compositions containing the
treated
metallic pigments.
BACKGROUND OF THE INVENTION
[0002j The use of metallic flake pigments, such as aluminum flake pigments,
in decorative coatings to give the coating a metallic effect is widespread.
The
metallic effect is particularly popular with customers in the automotive
market where
"glamour fnishes" are desired.
[0003] Automotive coatings can utilize a single, uniformly pigmented layer.
Alternatively, they can have two distinct layers, i.e., a first, highly
pigmented layer
(basecoat) and a subsequently applied coating layer with little or no
pigmentation
(clearcoat). The two-layer coating is known in the industry as
"basecoat/clearcoat".
Basecoat/clearcoat coatings impart a high level of gloss and depth of color
that can
result in a particularly appealing look. Metallic flake pigments typically are
incorporated into the basecoat composition.
[0004] Waterborne automotive .paints are gaining widespread usage in the
automotive industry due to concerns over organic solvent emissions during
coating
application and curing processes. However, waterborne paints have the
disadvantage of using a medium that can be corrosive to metallic flake
pigments.
For example, hydrolysis of the metal pigments can occur in waterborne paints.
Additionally, the pH of typical waterborne acrylic coating compositions can
range
from 8.0 to 9.0, and typical polyurethane coating compositions can have a pH
typically ranging from 7.5 to 8Ø In a basic pH environment, the aluminum
pigment
can be oxidized. The oxidation is a form of corrosion that destroys the
metallic
pigmentation properties of the mirror-like particles. When a paint with
oxidized
metallic flake pigments is coated onto a substrate, the coating shows
discoloration
and diminished metallic effect.
[0005] Additionally, the hydrolysis or oxidation of the metallic surfaces in
waterborne paints results in the evolution of hydrogen gas. The amount of
hydrogen
gas evolved is indicative of the amount of oxidation (i.e., corrosion) of the
metallic
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pigment. The hydrogen gas can accumulate under pressure if the coating
composition is stored in a closed container.
[0006] Hydrolysis of aluminum pigment in the presence of water can
accelerate over time due to continuous contact with the basic pH environment
of the
coating composition. Coating compositions containing metal flake pigment are
often
stored for 6 months or more before application, which can result in
significant
corrosion of the pigment. If this corrosion remains unchecked the coating
composition can be rendered unusable.
[0007] Considerable work has been done in the industry to treat or
"passivate" metal pigment surfaces to prevent corrosion of the metal surface
by water
in waterborne coating compositions. For example, it is known to apply a chrome
coating over aluminum pigment surfaces to prevent the corrosion and hydrogen
generation described above. However, chrome can be toxic and, therefore,
special
handling and disposal procedures are required for such chrome coated metallic
pigment particles.
[0008] Therefore, it would be advantageous to provide a coating composition
that could be used to passivate metal pigments while reducing or eliminating
altogether at least some of the problems associated with known passivation
procedures.
SUMMARY OF THE INVENTION
[0009] In one embodiment, the present invention is directed to a polymer
suitable for passivating a metal surface. The polymer comprises (a) at least
one nitro
group, and/or pyridine group, and/or phenolic hydroxyl group; and (b) at least
one
group selected from a phosphorous-containing group and/or a carboxylic acid
group,
wherein the at least one phosphorous-containing group is selected from a
phosphate,
a phosphite, or a non-nitrogen substituted phosphonate.
[0010] Also, the present invention provides a passivated metal pigment
comprising at least one metal pigment particle and a passivating material
formed
over at least a portion of the at least one pigment particle. The passivating
material
can comprise a polymer comprising (a) at least one nitro group, andlor
pyridine
group, and/or phenolic hydroxyl group; and (b) at least one group selected
from a
phosphorous-containing group and/or a carboxylic acid group, wherein the at
least
one phosphorous-containing group is selected from a phosphate, a phosphite, or
a
non-nitrogen substituted phosphonate.
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(0011] In a further embodiment, the present invention is directed to a coating
composition which comprises a diluent medium, a film-forming polymer, and at
least
one metal pigment particle at least partly treated with a passivating
material. The
passivating material can comprise a polymer comprising (a) at least one vitro
group,
and/or pyridine group, and/or phenolic hydroxyl group; and (b) at least one
group
selected from a phosphorous-containing group and/or a carboxylic acid group,
wherein the at least one phosphorous-containing group is selected from a
phosphate,
a phosphite, or a non-nitrogen substituted phosphonate.
[0012] Another embodiment provides a coating composition which comprises
an aqueous diluent medium, a film-forming polymer, and at least one metal
pigment
particle at least partly treated with a passivating material. The passivating
material
can comprise a polymer comprising the reaction product of a diglycidyl ether
of a
polyhydric alcohol; a vitro group-containing compound selected from at least
one of
an alkyl, an aryl, and/or an alkyl aryl vitro group-containing compound; and a
phosphorous group-containing compound comprising a phosphate group and/or a
non-nitrogen substituted phosphonate group.
[0013] A method of passivating a metal surface that comprises contacting the
metal surface with a passivating material is also provided. The passivating
material
comprises a polymer comprising (a) at least one vitro group, andlor pyridine
group,
and/or phenolic hydroxyl group; and (b) at least one group selected from a
phosphorous-containing group and/or a carboxylic acid group, wherein the at
least
one phosphorous-containing group is selected from a phosphate, a ,phosphite,
or a
non-nitrogen substituted phosphonate.
DESCRIPTION OF THE INVENTION
[0014] As used herein, all numbers expressing dimensions, physical
characteristics, processing parameters, quantities of ingredients, reaction
conditions,
and the like, used in the specification and claims are to be understood as
being
modified in all instances by the term "about". Accordingly, unless indicated
to the
contrary, the numerical values set forth in the following specification and
claims are
approximations that may vary depending upon the desired properties sought to
be
obtained by the present invention. At the very least, and not as an attempt to
limit
the application of the doctrine of equivalents to the scope of the claims,
each
numerical value should at least be construed in light of the number of
reported
significant digits and by applying ordinary rounding techniques. Moreover, all
ranges
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disclosed herein are to be understood to include the beginning and ending
range
values and to encompass any and all subranges subsumed therein. For example, a
stated range of "1 to 10" should be considered to include any and all
subranges
between (and inclusive of) the minimum value of 1 and the maximum value of 10;
that is, all subranges beginning with a minimum value of 1 or more and ending
with a
maximum value of 10 or less, e.g., 5.5 to 10, 3.7 to 6.4, or 1 to 7.8, just to
illustrate a
few. Molecular weight quantities used herein, whether Mn or Mw, are those
determinable from gel permeation chromatography using polystyrene as a
standard.
Also, as used herein, the term "polymer» includes oligomers, homopolymers, and
copolymers. The terms "surface modification" and "surface modified" encompass
any and all associations, interactions, or reactions between a metallic
surface and a
compound or composition in accordance with the disclosed invention. The terms
"passivate" and "passivation" refer to a surface that has been modified to
reduce the
tendency of the surface to corrode and/or to generate hydrogen gas upon
contact
with water. All references referred to in this document are to be understood
to be
incorporated by reference in their entirety. As used herein, the phrase "non-
nitrogen
substituted phosphonate" means a group having the formula:
O
R~- ; -OH
OH
where R~ is any group that does not contain nitrogen.
(0015 The passivating materials useful in the present invention generally
comprise a polymer having at least two substituents. In one non-limiting
embodiment, a first substituent can comprise at least one vitro group, and/or
at least
one pyridine group, and/or at least one phenolic hydroxyl group. A second
substituent can comprise at least one phosphorous-containing group and/or at
least
one carboxylic acid group.
[0016] In the broad practice of the invention, the passivating polymer can be
a straight chain or branched polymer. The polymer can be or can be derived
from,
for example, an acrylic polymer, a polyester polymer, a polyurethane polymer,
an
epoxy polymer, a polyolefin polymer, a polyether polymer, or can be a
copolymer
containing one or more of the above. In one embodiment, the polymer can be or
can
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be derived from a hydroxyl group- or an epoxy group-containing polymer
including
addition and condensation polymers, or mixtures of such polymers can also be
used.
The polymer can have a hydroxyl equivalent weight ranging from 100 to 1000,
such
as 200 to 400; or an epoxy equivalent weight ranging from 100 to 2000, such as
300
to 600.
[0017] Examples of hydroxyl group-containing polymers that can be utilized
include, but are not limited to, hydroxyl group-containing condensation
polymers,
such as hydroxyl functional polyesters. Examples of epoxy group-containing
polymers that can be utilized include polyglycidyl ethers of polyhydric
alcohols such
as the reaction products of epichlorohydrin or dichlorohydrin with aliphatic
and
cycloaliphatic alcohols, such as ethylene glycol, diethylene glycol,
triethylene glycol,
propylene glycol, dipropylene glycol, tripropylene glycol, propane diols,
butane diols,
pentane diols, glycerol, 1,2,6-hexanetriol, pentaerythritol, and 2,2-bis(4-
hydroxycyclohexyl)propane.
[0018] Examples of hydroxyl or epoxy group-containing addition polymers
that can be utilized include hydroxyl or epoxy functional polymers or
copolymers of
ethylenically unsaturated monomers. Examples of suitable monomers with
hydroxyl
functionality include hydroxyethyl (meth)acrylate, hydroxypropyl
(meth)acrylate,
hydroxybutyl (meth)acrylate, and allyl alcohol. Examples of suitable monomers
with
epoxy functionality include glycidyl (meth)acrylate. The addition polymer can
be a
homopolymer of any of these hydroxyl or epoxy functional monomers or can be a
copolymer of one or more of these hydroxyl or epoxy functional monomers and at
least one other ethylenically unsaturated monomer that is not hydroxyl or
epoxy
functional. Examples of these other monomers include but are not limited to
methyl
(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, styrene, and vinyl
monomers such as styrene, vinyl toluene and vinyl acetate.
(0019] Examples of epoxy compounds that can be utilized include
compounds as simple as ethylene oxide, propylene oxide, butylene oxide,
cyclohexene oxide, and the like.
[0020] Examples of epoxy compounds that can be utilized also include the
epoxy polyethers obtained by reacting an epihalohydrin (such as
epichlorohydrin or
epibromohydrin) with a polyphenol in the presence of an alkali. Suitable
polyphenols
include: 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol-A), 1,1-bis(4-
hydroxyphenyl)isobutane, 2,2-bis(4-hydroxytertiarybutylphenyl)propane, 4,4-
dihydroxybenzophenone, 1,1-bis(4-hydroxyphenyl)ethane, bis(2-
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hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene, 1,1-bis(4-hydroxy-3-
allylphenyl)ethane, and the hydrogenated derivatives of such compounds. The
polyglycidyl ethers of polyphenols of various molecular weights can be
produced, for
example, by varying the mole ratio of epichlorohydrin to polyphenol in known
manner.
[0021] Examples of epoxy compounds that can be utilized also include the
polyglycidyl ethers of mononuclear polyhydric phenols such as the polyglycidyl
ethers
of resorcinol, pyrogallol, hydroquinone, and pyrocatechol, as well as the
monoglycidyl
ethers of monohydric phenols such as phenylglycidyl ether, alpha-
naphthylglycidyl
ether, beta-naphthylglycidyl ether, and the corresponding compounds bearing an
alkyl substituent on the aromatic ring.
[0022] Further non-limiting examples of epoxy compounds that can be
utilized also include the glycidyl ethers of aromatic alcohols, such as
benzylglycidyl
ether and phenylglycidyl ether, or the polyglycidyl ethers of polyhydric
alcohols such
as the reaction,products of epichlorohydrin or dichlorohydrin with aliphatic
and
cycloaliphatic alcohols such as ethylene glycol, diethylene glycol,
triethylene glycol,
dipropylene glycol, tripropylene glycol, propane diols, butane diols, pentane
diols,
glycerol, 1,2,6-hexanetriol, pentaerythritol and 2,2-bis(4-
hydroxycyclohexyl)propane.
[0023] More non-limiting examples of epoxy compounds that can be utilized
also include polyglycidyl esters of polycarboxylic acids such as the generally
known
polyglycidyl esters of adipic acid, phthalic acid, and the like. Other epoxy
compounds
that can be utilized include the monoglycidyl esters of monocarboxylic acids,
such as
glycidyl benzoate, glycidyl naphthoate as well as the monoglycidyl esters of
substituted benzoic acid and naphthoic acids.
[0024] Addition polymerized resins containing epoxy groups can also be
employed. Such materials can be produced by the addition polymerization of
epoxy
functional monomers such as glycidyl acrylate, glycidyl methacrylate and allyi
glycidyl
ether typically in combination with polymerizable ethylenically unsaturated
and/or
vinyl monomers such as styrene, alpha-methyl styrene, alpha-ethyl styrene,
vinyl
toluene, t-butyl styrene, acrylamide, methacrylamide, acrylonitrile,
methacrylonitrile,
ethacrylonitrile, ethyl methacrylate, methyl methacrylate, isopropyl
methacrylate,
isobutyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-
ethylhexyl
acrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, and the like.
[0025] Alternatively, the polymeric backbone can comprise an acrylic,
urethane, polyester, alkyd or epoxy polymer or oligomer. The polymeric
backbone
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when synthesized can include thereon at least two isocyanate groups or capped
or
blocked isocyanate groups. This can be accomplished by either copolymerizing
into
the polymeric backbone a monomer with isocyanate or blocked isocyanate
functionality, or by reacting one or more groups (e.g., hydroxyl or amino
groups) with
isocyanate or blocked isocyanate functionality onto the polymer. The reaction
of the
isocyanate or blocked isocyanate functionality with an isocyanate-reactive
functionality of the first substituent or the second substituent can form the
appropriate
linking group.
[0026] Illustrative examples of isocyanate or blocked isocyanate functional
urethane backbones include urethane polymers with terminal isocyanate or
blocked
isocyanate functionality. The urethane polymers can be synthesized by known
techniques, such as bulk polymerization, such as solution polymerization, from
polyisocyanates and polyfuncttonal compounds reactive with polyisocyanates,
including, for example, polyols, polyamines, and amino alcohols; with the
proviso that
the sum of equivalents of isocyanate and latent isocyanate groups used exceeds
the
equivalents used of polyfunctional compounds reactive with potyisocyanates.
The
polyisocyanate can be, for example, isophorone diisocyanate, p-phenylene
diisocyanate, biphenyl 4, 4' diisocyanate, meta-xylylene diisocyanate, toluene
diisocyanate, 3,3'-dimethyt-4,4'-biphenylene diisocyanate, 1,4-tetramethytene
diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexane-1,6-
diisocyanate, 1,3-bis-[2-((isocyanato)propyl]benzene (also known as
tetramethylxylyldiisocyanate, TMXDI) methylene bis-(phenyl isocyanate), 1,5-
naphthalene diisocyanate, bis-(isocyanatoethyl fumarate), methylene bis-(4-
cyclohexyl isocyanate), and biurets or isocyanurates of any of these.
[0027] The polyfunctionat compounds reactive with polyisocyanates can
include any of diols, triols, or alcohols of higher functionality, such as
ethylene glycol,
propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol,
trimethylolethane,
trimethylolpropane, pentaerythritol, polyester polyols, polyether polyols, and
the like;
polyamines, such as ethylene diamine and diethylene triamine; or amino
alcohols,
such as diethanolamine and ethanolamine.
[0028] One of either the polyisocyanate or the polyfunctional compound
reactive with polyisocyanate can have functionality (including blocked
functionality)
greater than two. The reactants can be apportioned so that the polyurethane
copolymer has terminal isocyanate functionality.
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[0029] Illustrative examples of isocyanate or blocked isocyanate functional
acrylics are copolymers of an ethylenically unsaturated monomer containing an
isocyanate or blocked isocyanate group. The copolymers can be prepared by
using
conventional techniques, such as free radical polymerization cationic
polymerization,
or anionic polymerization, in, for example, a batch or semi-batch process. For
instance, the polymerization can be carried out by heating the ethylenically
unsaturated monomers in bulk or in organic solution in the presence of a free
radical
source, such as an organic peroxide or azo compound and, optionally, a chain
transfer agent for a batch process; or, alternatively, the monomers and
initiators) can
be fed into the heated reactor at a controlled rate in a semi-batch process.
[0030] In one non-limiting embodiment, the first substituent can comprise a
vitro (N02) group. The vitro substituent can be formed by reacting a vitro-
containing
material with isocyanate groups on the polymer backbone. Examples of such
materials useful for forming the substituents compatible with the above-
mentioned
requirements include any vitro-containing compound having an isocyanate
reactive
group, such as hydroxy, amino, mercapto or oxirane group. Useful vitro-
containing
compounds include alkyl, aryl, or alkylaryl substituted compounds including an
isocyanate reactive group. Exemplary, non-limiting vitro-containing compounds
for
purposes of the present invention include 2-methyl-2-vitro propanol, 2-vitro-1-
propanol, 2-nitroethanol, 4-nitroaniline, 2-nitrobenzyl alcohol, 4-nitrothio
phenol, 2-
nitrobenzoic acid, 4-nitrobenzoic acid, 2-4-dinitrobenzoic acid, andlor
mixtures
thereof.
[0031] In another non-limiting embodiment, the first substituent can comprise
at least one pyridine group and/or at least one phenolic hydroxyl group.
Examples of
materials suitable for forming the pyridine group include, but are not limited
to, 2,6
pyridine dimethanol, 2-pyridine propanol, 3-pyridine propanol, pyridine
proprionic
acid, isonicotonic acid, picolinic acid, dipicolinic acid, nicotinic acid,
dinicotinic acid,
cinchomeronic acid, isocinchomeronic acid, or mixtures thereof. Examples of
materials suitable for forming the phenolic hydroxyl group include, but are
not limited
to, gallic acid, allyl phenol, polyhydroxy phenols, such as resorcinol,
catechol,
phloroglucinol, pyrogallol, 1,2,4-benzene triol, or mixtures thereof.
[0032] In one non-limiting embodiment, the second substituent comprises a
phosphorous-containing group, such as a phosphate group, a non-nitrogen
substituted phosphonate group, orthophosphoric acid, an organic ester of
phosphoric
acid, andlor a phosphite compound. For example, the phosphate compound can be
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of the type described in U.S. Patent No. 4,565,716. Organic phosphites are
derivatives of phosphorous acid, rather than phosphoric acid used to produce
organic
phosphates. Exemplary organic phosphates are described in U.S. Patent No.
4,808,231.
[0033] Examples of phosphoric acid esters that can be used in the practice of
the invention include mono- and di-C4-C,8 alkyl esters, such as mono- and
dibutylphosphate, mono and dipentyl phosphate, mono- and dihexylphosphate,
mono- and diheptylphosphate, mono- and dioctylphosphate, mono- and
dinonylphosphate, mono- and dihexadecylphosphate and mono- and
dioctadecylphosphate; and aryl and aralkyl esters containing from 6 to 10
carbon
atoms in the aromatic group, for example mono- and diphenylphosphate and mono-
and dibenrylphosphate.
[0034] In one particular non-limiting embodiment, the passivating polymer
useful in the present invention comprises an epoxy polymer with at least one
nitro
group substituent and at least one phosphoric acid group having an equivalent
ratio
of epoxy: nitro group: phosphoric acid of 3.8 / 0.3 / 4.8 to 3.8 ! 3 / 0.8. In
another
non-limiting embodiment, the equivalent ratio of epoxy: nitro group:
phosphoric acid
can be 3.8 I 0.8 / 4.2 to 3.8 /1 I 3.2.
[0035] It has been found that contacting a metallic pigment with a passivating
polymer, such as any of those described above, reduces or prevents hydrolysis
or
oxidation of the pigment and thereby reduces or eliminates altogether the
generation
of hydrogen gas. 'Moreover, the inclusion of metallic pigment treated with
such a
polymer in a waterborne coating composition does not disadvantageously affect
humidity resistance of dry films (coatings) produced from such waterborne
compositions.
[0036] An exemplary waterborne coating composition of the invention
typically comprises a film-forming polymer, an aqueous diluent medium, and a
metallic pigment at least partially treated with a passivating polymer of the
invention.
The tendency of the pigment to react with the aqueous medium and release
gaseous
material is prevented or reduced by the incorporation of an effective amount
of a
passivating material of the invention.
[0037] Examples of metallic pigments suitable for use in a waterborne
coating composition of the invention include any metallic pigments that are
generally
known for use in pigmented coating compositions. Examples include, without
limitation, metallic pigments, such as metallic flake pigments, comprised at
least
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partly of aluminum, copper, zinc, iron, and/or brass as well as those composed
of
other malleable metals and alloys such as nickel, tin, silver, chrome,
aluminum-
copper alloy, aluminum-zinc alloy, and aluminum-magnesium alloy. Moreover, a
waterborne coating composition of the invention also can include one or more
of a
wide variety of other pigments generally known for use in coating
compositions, such
as various color-producing pigments and/or filler pigments. Examples of such
pigments include, without limitation, generally known pigments based on metal
oxides; metal hydroxides; metal sulfides; metal sulfates; metal carbonates;
carbon
black; china clay; phthalo blues and greens, organo-reds, and organic dyes.
[0038] Various procedures can be used to incorporate a passivating material
comprising a passivating polymer of the invention, such as any of those
described
previously, into a coating composition, such as but not limited to a
waterborne
coating composition of the invention. By "waterborne" coating composition is
meant
a coating composition in which the diluent medium is primarily an aqueous
medium,
i.e., the waterborne coating composition is free or substantially free of
organic
solvent. By "substantially free of organic solvent" is meant that the amount
of organic
solvent; if present, is less than 20 weight percent based on the total weight
of the
coating composition, such as less than 10 weight percent, such a less than 5
weight
percent, such as less than 2 weight percent, such as less than 1 weight
percent. As
will be appreciated by one skilled in the coating art, in one non-limiting
embodiment
of the invention the waterborne coating composition can include a small amount
of
organic solvent to affect one or more of the coating properties, such as to
improve
flow or leveling of the applied composition or to decrease viscosity as
needed. One
method of incorporating the passivating material comprising a polymer of the
invention is to bring the metallic pigment into contact with the passivating
material
prior to the incorporation of the pigment into the waterborne coating
composition.
This can be done by adding the passivating material of the invention to the
pigment
paste (e.g., pigment as normally supplied commercially), or it can be added at
an
earlier stage such as during the actual production of the pigment.
Alternatively, a
passivating material can be introduced into a waterborne coating composition
of the
invention by simply introducing it "neat", i.e., as a further ingredient in
the formulation
of the waterborne coating composition, for example during the mixing of film-
forming
resin, metallic pigment and aqueous medium together with other conventional
and
optional constituents such as crosslinking agents, co-solvents, thickeners and
fillers.
Irrespective of the manner in which a passivating material of the invention is
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incorporated into a waterborne coating composition of the invention, an amount
of
such compound generally is employed which is effective in reducing or
eliminating
gassing of the metallic pigment in the aqueous medium. For example, the amount
of
the passivating material can be in the range of 5 weight percent to 200 weight
percent passivating material solids based on the weight of pigment solids,
such as in
the range of 10 weight percent to 100 weight percent, such as in the range of
10
weight percent to 80 weight percent, such as in the range of 15 weight percent
to 50
weight percent, such as in the range of 16 weight percent to 25 weight
percent.
[0039] One exemplary substantially organic solvent-free coating composition
of the present invention can be a thermoplastic film-forming composition, or,
alternatively, a thermosetting composition. As used herein, by "thermosetting
composition" is meant one which "sets" irreversibly upon curing or
crosslinking,
wherein the polymer chains of the polymeric components are joined together by
covalent bonds. This property is usually associated with a crosslinking
reaction of
the composition constituents often induced, for example, by heat or radiation.
Hawley, Gessner G., The Condensed Chemical Dictionary, Ninth Edition., page
856;
Surtace Coatings, vol. 2, Oil and Colour Chemists' Association, Australia,
TAFE
Educational Books (1974). Curing or crosslinking reactions also may be carried
out
under ambient conditions. Once cured or crosslinked, a thermosetting
composition
will not melt upon the application of heat and is insoluble in solvents. By
contrast, a
"thermoplastic composition" comprises polymeric components which are not
joined
by covalent bonds and thereby can undergo liquid flow upon heating and are
soluble
in solvents. Saunders, K.J., Organic Polymer Chemistry, pp. 41-42, Chapman and
Hall, London (1973).
[0040] An exemplary coating composition of the invention comprises a diluent
medium, a resinous binder system, a passivating material comprising a polymer
of
the invention, and at least one metal pigment particle. For example, the
pigment
particle can be at least partially treated with a passivating material of the
invention.
[0041] The diluent medium can be a solventborne diluent medium or an
aqueous (e.g., waterborne) diluent medium. By "solventborne" is meant that the
diluent material is primarily a non-aqueous, e.g., organic solvent, material.
[0042] The resinous binder system typically comprises (a) at least one
reactive functional group-containing film-forming polymer and (b) at least one
crosslinking agent having functional groups reactive with the functional
groups of the
film-forming polymer.
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[0043] The film-forming polymer (a) can comprise any of a variety of reactive
group-containing polymers well known in the surface coatings art provided the
polymer is sufi~iciently dispersible in the diluentmedia. Suitable non-
limiting examples
can include acrylic polymers, polyester polymers, polyurethane polymers,
polyether
polymers, polysiloxane polymers, polyepoxide polymers, copolymers thereof, and
mixtures thereof. Also, the polymer (a) can comprise a variety of reactive
functional
groups, for example, functional groups selected from at least one of hydroxyl
groups,
carboxyl groups, epoxy groups, amino groups, amido groups, carbamate groups,
isocyanate groups, and combinations thereof.
[0044] For example, suitable hydroxyl group-containing polymers can include
acrylic polyols, polyester polyols, polyurethane polyols, polyether polyols,
and
mixtures thereof.
[0045] Suitable hydroxyl group and/or carboxyl group-containing acrylic
polymers can be prepared from polymerizable ethylenically unsaturated monomers
and are typically copolymers of (meth)acrylic acid and/or hydroxylalkyl esters
of
(meth)acrylic acid with one or more other polymerizable ethylenically
unsaturated
monomers such as alkyl esters of (meth)acrylic acid including methyl
(meth)acrylate,
ethyl (meth)acrylate, butyl (meth)acrylate and 2-ethyl hexylacrylate, and
vinyl
aromatic compounds such as styrene, alpha-methyl styrene, and vinyl toluene.
[0046] In a one embodiment of the present invention, the acrylic polymer can
be prepared from ethylenically unsaturated, beta-hydroxy ester functional
monomers,
such as those described above.
[0047] Epoxy functional groups can be incorporated into the acrylic polymer
prepared from polymerizable ethylenically unsaturated monomers by
copolymerizing
oxirane group-containing monomers, for example glycidyl (meth)acrylate and
allyl
glycidyl ether, with other polymerizable ethylenically unsaturated monomers,
such as
those discussed above. Preparation of such epoxy functional acrylic polymers
is
described in detail in U.S. Patent No. 4,001,156 at columns 3 to 6.
[0048] Carbamate functional groups can be incorporated into the acrylic
polymer prepared from polymerizable ethylenically unsaturated monomers by
copolymerizing, for example, the above-described ethylenically unsaturated
monomers with a carbamate functional vinyl monomer such as a carbamate
functional alkyl ester of methacrylic acid. Useful carbamate functional alkyl
esters
can be prepared by reacting, for example, a hydroxyalkyl carbamate, such as
the
reaction product of ammonia and ethylene carbonate or propylene carbonate,
with
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methacrylic anhydride. Other useful carbamate functional vinyl monomers
include,
for instance, the reaction product of hydroxyethyl methacrylate, isophorone
diisocyanate, and hydroxypropyl carbamate; or the reaction product of
hydroxypropyl
methacrylate, isophorone diisocyanate, and methanol. Still other carbamate
functional vinyl monomers may be used, such as the reaction product of
isocyanic
acid (HNCO) with a hydroxyl functional acrylic or methacrylic monomer such as
hydroxyethyl acrylate, and those described in U.S. Patent No. 3,479,328.
Carbamate
functional groups can also be incorporated into the acrylic polymer by
reacting a
hydroxyl functional acrylic polymer with a low molecular weight alkyl
carbamate, such
as methyl carbamate. Pendant carbamate groups can also be incorporated into
the
acrylic polymer by a "transcarbamoylation" reaction in which a hydroxyl
functional
acrylic polymer is reacted with a low molecular weight carbamate derived from
an
alcohol or a glycol ether. The carbamate groups exchange with the hydroxyl
groups
yielding the carbamate functional acrylic polymer and the original alcohol or
glycol
ether. Also, hydroxyl functional acrylic polymers can be reacted with
isocyanic acid
to provide pendent carbamate groups. Likewise, hydroxyl functional acrylic
polymers
can be reacted with urea to provide pendent carbamate groups.
[0049] The polymers prepared from polymerizable ethylenically unsaturated
monomers can be prepared by solution polymerization techniques, which are well
known to those skilled in the art, in the presence of suitable catalysts such
as organic
peroxides or azo compounds, for example, benzoyl peroxide or N,N-
azobis(isobutylronitrile). The polymerization can be carried out in an organic
solution
in which the monomers are soluble by techniques conventional in the art.
Alternatively, these polymers can be prepared by aqueous emulsion or
dispersion
polymerization techniques which are well known in the art. The ratio of
reactants and
reaction conditions are selected to result in an acrylic polymer with the
desired
pendent functionality.
[0050] Polyester polymers are also useful in the film-forming compositions of
the invention. Useful polyester polymers typically inGude the condensation
products
of polyhydric alcohols and polycarboxylic acids. Suitable polyhydric alcohols
can
include ethylene glycol, neopentyl glycol, trimethylol propane, and
pentaerythritol.
Suitable polycarboxylic acids can include adipic acid, 1,4-cyclohexyl
dicarboxylic
acid, and hexahydrophthalic acid. Besides the polycarboxylic acids mentioned
above, functional equivalents of the acids such as anhydrides where they exist
or
lower alkyl esters of the acids such as the methyl esters can be used. Also,
small
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amounts of monocarboxylic acids such as stearic acid can be used. The ratio of
reactants and reaction conditions are selected to result in a polyester
polymer with
the desired pendent functionality, i.e., carboxyl or hydroxyl functionality.
[0051] For example, hydroxyl group-containing polyesters can be prepared
by reacting an anhydride of a dicarboxylic acid such as hexahydrophthalic
anhydride
with a diol such as neopentyl glycol in a 1:2 molar ratio. Where it is desired
to
enhance air drying, suitable drying oil fatty acids may be used and include
those
derived from linseed oil, soya bean oil, tall oil, dehydrated castor oil, or
tung oil.
[0052] Carbamate functional polyesters can be prepared by first forming a
hydroxyalkyl carbamate that can be reacted with the polyacids and polyols used
in
forming the polyester. Alternatively, terminal carbamate functional groups can
be
incorporated into the polyester by reacting isocyanic acid with a hydroxy
functional
polyester. Also, carbamate functionality can be incorporated into the
polyester by
reacting a hydroxyl polyester with a urea. Additionally, carbamate groups can
be
incorporated into the polyester by a transcarbamoylation reaction. Preparation
of
suitable carbamate functional group-containing polyesters are those described
in
U.S. Patent No. 5,593,733 at column 2, line 40 to column 4, line 9.
[0053] Polyurethane polymers containing terminal isocyanate or hydroxyl
groups also can be used as the polymer in the coating compositions of the
invention.
The polyurethane polyols or NCO-terminated polyurethanes which can be used are
those prepared by reacting polyols including polymeric polyols with
polyisocyanates.
Polyureas containing terminal isocyanate or primary and/or secondary amine
groups
which also can be used are those prepared by reacting polyamines including
polymeric polyamines with polyisocyanates. The hydroxyl/isocyanate or
amine/isocyanate .equivalent ratio is adjusted and reaction conditions are
selected to
obtain the desired terminal groups. Examples of suitable polyisocyanates
include
those described in U.S. Patent No. 4,046,729 at column 5, line 26 to column 6,
line
28, incorporated herein by reference. Examples of suitable polyols include
those
described in U.S. Patent No. 4,046,729 at column 7, line 52 to column 10, line
35.
Examples of suitable polyamines include those described in U.S. Patent No.
4,046,729 at column 6, line 61 to column 7, line 32 and in U.S. Patent No.
3,799,854
at column 3, lines 13 to 50.
[0054] Carbamate functional groups can be introduced into the polyurethane
polymers by reacting a polyisocyanate with a polyester having hydroxyl
functionality
and containing pendent carbamate groups. Alternatively, the polyurethane can
be
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prepared by reacting a polyisocyanate with a polyester polyol and a
hydroxyalkyl
carbamate or isocyanic acid as separate reactants. Examples of suitable
polyisocyanates are aromatic isocyanates, such as 4,4'-diphenylmethane
diisocyanate, 1,3-phenylene diisocyanate and toluene diisocyanate, and
aliphatic
polyisocyanates, such as 1,4-tetramethylene diisocyanate and 1,6-hexamethylene
diisocyanate. Cycloaliphatic diisocyanates, such as 1,4-cyclohexyl
diisocyanate and
isophorone diisocyanate also can be employed.
[0055] Examples of suitable polyether polyols include polyalkylene ether
polyols such as those having the following structural formulas (I) or (II):
H O~ CH OH
n Jm
R
or
H O--f--CH2-CH OH
R n --~ m
wherein the substituent R is hydrogen or a lower alkyl group containing from 1
to 5
carbon atoms including mixed substituents, and n has a value typically ranging
from
2 to 6 and m has a value ranging from 8 to 100 or higher. Exemplary
polyalkylene
ether polyols include poly(oxytetramethylene) glycols, poly(oxytetraethylene)
glycols,
poly(oxy-1,2-propylene) glycols, and poly(oxy-1,2-butylene) glycols.
[0056] Also useful are polyether polyols formed from oxyalkylation of various
polyols, for example, glycols such as ethylene glycol, 1,6-hexanediol,
Bisphenol A,
and the like, or other higher polyols such as trimethylolpropane,
pentaerythritol, and
the like. Polyols of higher functionality which can be utilized as indicated
can be
made, for instance, by oxyalkylation of compounds such as sucrose or sorbitol.
One
commonly utilized oxyalkylation method is reaction of a polyol with an
alkylene oxide,
for example, propylene or ethylene oxide, in the presence of an acidic or
basic
catalyst. Specific examples of polyethers include those sold under the names
TERATHANE and TERACOL, available from E. I. Du Pont de Nemours and
Company, Inc.
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[0057] As previously mentioned, in certain embodiments of the present
invention, the film-forming composition may also comprise (b) one or more
crosslinking agents that are adapted to react with the functional groups of
the
polymer and/or any of the previously mentioned polymeric microparticles andlor
addivites to provide curing, if desired, for the film-forming composition. Non-
limiting
examples of suitable crosslinking agents include any of the aminoplasts and
polyisocyanates as are well known in the surface coatings art, provided that
the
crosslinking agents) are adapted to be water soluble or water dispersible as
described below, and polyacids, polyanhydrides and mixtures thereof. When
used,
selection of the crosslinking agent or mixture of crosslinking agents is
dependent
upon the functionality associated with the polymeric microparticles, such as
hydroxyl
and/or carbamate functionality. When, for example, the functionality is
hydroxyl, the
hydrophilic crosslinking agent may be an aminoplast or polyisocyanate
crosslinking
agent.
.[0058] Examples of aminoplast resins suitable for use as the crosslinking
agent include those containing methylol or similar alkylol groups, a portion
of which
have been etherified by reaction with a lower alcohol, such as methanol, to
provide a
water solubleldispersible aminoplast resin. One appropriate aminoplast resin
is the
partially methylated aminoplast resin, CYMEL 385, which is commercially
available
from Cytec Industries, Inc. An example of a blocked isocyanate which is water
soluble/dispersible and suitable for use as the crosslinking agent is dimethyl
pyrazole
blocked hexamethylene diisocyanate trimer commercially available as BI 7986
from
Baxenden Chemicals, Ltd. in Lancashire, England.
[0059] Polyacid crosslinking materials suitable for use in the present
invention can include, for example, those that on average generally contain
greater
than one acid group per molecule, sometimes three or more and sometimes four
or
more, such acid groups being reactive with epoxy functional film-forming
polymers.
Polyacid crosslinking materials may have di-, tri- or higher functionalities.
Suitable
polyacid crosslinking materials which can be used include, for example,
carboxylic
acid group-containing oligomers, polymers and compounds, such as acrylic
polymers, polyesters, and polyurethanes and compounds having phosphorus-based
acid groups.
[0060] Examples of suitable polyacid crosslinking agents include, for
example, ester group-containing oligomers and compounds including half esters
formed from reacting polyols and cyclic 1,2-acid anhydrides or acid functional
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polyesters derived from polyols and polyacids or anhydrides. These half-esters
are
of .relatively low molecular weight and are quite reactive with epoxy
functionality.
Suitable ester group-containing oligomers include those described in U.S. Pat.
No.
4,764,430, column 4, line 26 to column 5, line 68, which is hereby
incorporated by
reference.
[0061] Other useful crosslinking agents include acid-functional acrylic
crosslinkers made by copolymerizing methacrylic acid and/or acrylic acid
monomers
with other ethylenically unsaturated copolymerizable monomers as the polyacid
crosslinking material. Alternatively, acid-functional acrylics can be prepared
from
hydroxy-functional acrylics reacted with cyclic anhydrides.
[0062] In accordance with certain embodiments of the present invention, the
crosslinking agent (b) which typically is water soluble/dispersible, may be
present as
a component in the film-forming composition in an amount ranging from 0 to at
least
weight percent, or at least 10 to at least 20 weight percent, or from at least
20 to
at least 30 weight percent based on total resin solids weight in the film-
forming
composition. In accordance with certain embodiments of the present invention,
the
crosslinking agent may be present as a component in the film-forming
composition in
an amount ranging from less than or equal to 70 to less than or equal to 60
weight
percent, or less than or equal to 60 to less than or equal to 50 weight
percent, or less
than or equal to 50 to less than or equal to 40 weight percent based on total
resin
solids weight of the film-forming composition. The crosslinking agent can be
present
in the film-forming composition in an amount ranging between any combination
of
these values inclusive of the recited ranges.
[0063] Resinous binders for a basecoat can be organic solvent-based
materials, such as those described in U.S. Patent No. 4,220,679, note column
2, line
24 continuing through column 4, line 40. Also, water-based coating
compositions,
such as those described in U.S. Patent No. 4,403,003, U.S. Patent No.
4,147,679,
and U.S. Patent No. 5,071,904, can be used as the binder in the basecoat
composition.
[0064] The coating composition can include various other ingredients
generally known for use in waterborne coating compositions. Examples of
various
other ingredients include: fillers; plasticizers; antioxidants; mildewcides
and
fungicides; surfactants; various flow control agents including, for example,
thixotropes and additives for sag resistance and/or pigment orientation such
as
precipitated silicas, fumed silicas, organo-modified silicas, bentone clays,
organo-
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modified bentone clays, and such additives based on polymer microparticles
(sometimes referred to as microgels) described for example in U.S. Pat. Nos.
4,025,474; 4,055,607; 4,075,141; 4,115,472; 4,147,688; 4,180,489; 4,242,384;
4,268,547; 4,220,679; and 4,290,932.
[0065] Examples of organic solvents and/or diluents that can be employed in
an organic solvent-borne coating composition of the invention include
alcohols, such
as lower alkanols containing 1 to 8 carbon atoms including methanol, ethanol,
n-
propanol, isopropanol, butanol, sec-butyl alcohol, tertbutyl alcohol, amyl
alcohol,
hexyl alcohol and 2-ethylhexyl alcohol; ethers and ether alcohols such as
ethyleneglycol monoethyl ether, ethyleneglycol monobutyl ether, ethyleneglycol
dibutyl ether, propyleneglycol monomethyl ether, diethyleneglycol monobutyl
ether,
diethyleneglycol dibutyl ether, dipropyleneglycol monomethyl ether, and
dipropyleneglycol monobutyl ether; ketones such as methyl ethyl ketone, methyl
isobutyl ketone, methyl amyl ketone and methyl N-butyl ketone; esters such as
butyl
acetate, 2-ethoxyethyl acetate and 2 ethylhexyl acetate; aliphatic and
alicyclic
hydrocarbons such as the various petroleum naphthas and cyclohexane; and
aromatic hydrocarbons such as toluene and xylene. The amount of organic
solvent
and/or diluent utilized in an organic solvent-borne coating composition of the
invention may vary widely. However, in one non-limiting embodiment, the amount
of
organic solvent andlor diluent can range from about 10 percent to about 50
percent,
such as from 20 percent to 40 percent, by weight based on the total weight of
organic
solvent-borne coating composition.
[0066] Passivating materials of the present invention can also be utilized in
powder coating compositions comprising a film-forming polymer and a pigment
(typically a metallic pigment).
[0067] The following examples illustrate the invention and should not be
construed as a limitation on the scope thereof. Unless specifically indicated
otherwise, all percentages and amounts are understood to be by weight.
EXAMPLES
[0068] The following examples illustrate the gassing characteristics of
exemplary coating compositions incorporating passivating materials comprising
polymers of the present invention as compared to commercially available
passivating
materials.
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Preparation of Passivatinq Materials
(0069] Polymers for use in the passivating materials of the present invention
and compositions incorporating the polymers were prepared as follows:
Polymer Synthesis Example 1 (PE1 )
A passivating polymer of the present invention was prepared as described below
from the following ingredients.
' Table 1
Ingredients Amounts (gram)
1 EPON 828' 358.5
2 N-methyl pyrrolidone 263.4
3 2-Nitrophenol 106.1
4 Phosphoric Acid 73.1
Propyl ether of propylene263.3
glycol
6 N, N-dimethyl ethanol43.2
amine
7 Deionized water 671.0
' EPON 828 is bis-epoxy with an epoxy equivalent weight of
188 and is commercially available from Shell Oil and
Chemical Co.
[0070] A reactor was charged with the first three ingredients and heated to a
temperature of 100°C under nitrogen and was held at this temperature
for about an
hour. The reaction mixture was cooled to a temperature of 30°C and
ingredient 4
was then added. The reaction temperature was then raised to 100°C, and
the
mixture was held at this temperature for approximately 2 hours. The product
thus
formed was then diluted with ingredients 5, 6, and 7 under agitation. The
product
was cooled to room temperature. The reaction product had a solid content of
about
32%andapHof5.7.
Polymer Synthesis Example 2 (PE2)
[0071] This polymer was prepared as was the polymer of Example 1 but
replacing 2-nitophenol with 4-nitrobenzoic acid on an equivalent basis.
Polymer Synthesis Example 3 (PE3)
[0072] This polymer was prepared as was the polymer of Example 2 but
replacing one half of the 4-nitrobenzoic acid with isonicotinic acid on an
equivalent
basis.
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Polymer Synthesis Example 4 (PE4)
(0073] This polymer was prepared as was .the polymer of Example 2 but
replacing the 4-nitrobenzoic acid with isonicotinic acid on an equivalent
basis.
Polymer Synthesis Example 5 (PE5)
[0074] This polymer was prepared as was the polymer of Example 2 but
reacting all of the EPON 828 with only 4-nitrobenzoic acid. No phosphoric acid
was
used.
Polymer Synthesis Example 6 (PE6)
[0075] This polymer was prepared as was the polymer of Example 2 but
replacing 42 weight percent of the phosphoric acid with trimellitic anhydride
on an
equivalent basis.
Polymer Synthesis Example 7 (PE7)
(0076] This polymer was prepared as was the polymer of Example 2 but
replacing 50 equivalent percent of the 4-nitrobenzoic acid with a reaction
product of
phthalic anhydride and hydroxyethylethylene urea (prepared by reacting the two
components at 120°C).
Polymer Synthesis Example 8 (PE8)
(0077] This polymer was made in the same way as the polymer of Example 2
but replacing the 4-nitrobenzoic acid with isostearic acid on an equivalent
basis.
Polymer Synthesis Example 9 (PE9)
[0078] This polymer was prepared as was the polymer of Example 8 but
replacing EPON 828 with EPON 872 (epoxy equivalent weight of 645) on an
equivalent basis.
Polymer Synthesis Example 10 (PE10)
(0079] A polyurethane acrylate was prepared as described below from the
following ingredients:
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Table 2
Amount
rams Material
1 934.0 polyester polyol having a hydroxyl
value of 120 (prepared
from trimethylolpropane (15.2%), neopentyl
glycol (35.3%),
and adipic acid (49.5%).)
2 108.0 hydroxyethyl acrylate (HEA)
3 1.2 dibutyltin dilaurate
4 1.2 butylated hydroxytoluene
157.2 hexamethylenediisocynate (HDI)
6 262.2 butyl acrylate (BA)
[0080] The first four ingredients were stirred in a flask as the HDI was added
over a one hour period at a temperature of 70°C to 80°C. 39g of
the butyl acrylate
then was used to rinse the addition funnel and the temperature of the reaction
mixture then was held at 70°C for an additional 2 hours as all the
isocyanate reacted.
The remainder of the butyl acrylate then was added to produce an 80% solution
with
a Gardner-Holdt viscosity of X.
[0081] A pre-emulsion was prepared from the following ingredients:
Table 3
Amount
rams Ingredients
1 1003.80polyurethane acrylate prepared as
described
immediately above
2 120.40 butyl acrylate
3 147.00 methyl methacrylate (MMA)
4 20.60 acrylic acid
5 13.52 dimethylethanolammonium dodecylbenzene
sulfonate,
50% in water (DDBSA/DMEA)
6 46.16 ALIPAL Co 436, anionic surfactant,
available from
Rhodia Chemicals
7 17.92 AEROSOL OT-75 (sodium dioctylsulfosuccinate
available from Cytec Industries, Inc.)
8 1246.00Deionized water
[0082] The pre-emulsion was passed once through an M110
MICROFLUIDIZER RTM emulsifier at 7000 psi to produce a microdispersion. The
microdispersion was stirred at 22°C under nitrogen in a round bottom
flask and the
ingredients listed in the following Table 4 were added.
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Table 4
Amount
rams Ingredients
1 429.90 deionized water
2 2.00 isoascorbic acid
3 2.86 ferrous ammonium sulfate
(1% aqueous
solution)
4 2.94 hydogen peroxide (30% aqueous
solution)
21.50 dimethylethanol amine
[0083] Upon addition of the ingredients of Table 4, the reaction temperature
rose spontaneously to 56°C after approximately 15 minutes. The final
product had
the following characteristics:
total solids about 42 wt.%;
pH about 8.3; and
Brookfield viscosity (50 rpm, spindle #1 ) about 14 cps
Polymer Examale 11 (PE11)
[0084] This example describes the preparation of an acrylic polyester
polymer. The acrylic polyester was prepared from the following ingredients as
described below.
[0085] Polyester (P): The polyester was prepared in a four neck round
boftom flask equipped with a thermometer, mechanical stirrer, condenser, dry
nitrogen sparge, and a heating mantle. The polyester was prepared from
ingredients
listed in the following Table 5.
Table 5
Amount
rams Ingredients
1 1103.00stearic acid
2 800.00 pentaerithritol
3 480.00 crotonic acid
4 688.00 phthalic acid
5 6.12 dibutyl tin
dilaurate
6 ~ 6.12 triphenyl phosphite
7 1200.00butyl acrylate
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[0086] The first six ingredients were stirred in the flask at a temperature
230°C. The distillate was collected in a Dean Stark trap and the
mixture was held at
this temperature until the acid value dropped to less than 5. The product was
then
cooled to a temperature of below 80°C and diluted with the butyl
acrylate.
Polyester/acrylic Latex Preparation
[0087] A pre-emulsion was prepared by stirring together the following
ingredients:
Table 6
Amount
rams Ingredients
1 1000.0 deionized water
2 295.0 Polyester (P)
3 30.0 Ethyleneglycol dimethacrylate
4 20.0 acrylic acid
655.0 butyl acrylate
6 46.4 dodecylbenzenesulphonic
acid
7 14.3 Dimethyl ethanolamine
[0088] The pre-emulsion was passed once through a MICROFLUIDIZER
RTM M110T at 8000 psi and transferred to a four neck round bottom flask
equipped
with an overhead stirrer, condenser, thermometer, and a nitrogen atmosphere.
150.0
g of deionized water used to rinse the MICROFLUID1ZER RTM was added to the
flask. The polymerization was initiated by adding 4.0 g of isoascorbic acid
and 0.02 g
of ferrous ammonium sulfate dissolved in 120.0 g water followed by an addition
over
a thirty minute period of 4.0 g of 70% t-butyl hydroperoxide (dissolved in
115.0 g of
water). The reaction temperature increased from 24°C to 85°C
during this time. The
temperature was reduced to 28°C at which time 36 g of 33.3% aqueous
dimethylethanolamine was added, followed by 2.0 g of PROXEL GXL (biocide
commercially available from ICI Americas, Inc.) in 8.0 g of water. The pH of
the latex
thus formed was 7.9, the nonvolatile content was 42.0%, and the Brookfield
viscosity
was 17 cps (spindle #1, 50 rpm).
Polymer Example 12 (PE12)
[0089] This example describes the preparation of an acrylic dispersion. The
acrylic dispersion was prepared as described below from the ingredients listed
in the
following Table 7.
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Table 7
STAGE 1 Amount rams
Charge #1
Deionized water 884.2
Dioctylsulfosuccinate 17.0
Feed A
Methyl methacrylate 441.6
Butyl acrylate 147.2
Methacrylic acid 11.9
Dioctylsulfosuccinate 13.6
Deionized water 423.3
Feed B
Deionized water 339.6
Ammonium persulfate 2.5
STAGE II Amount (grams)
Feed C
Methyl methacrylate 71.0
Butylacrylate 35.0
Hydroxyethyl acrylate 6.9
Dioctylsulfosuccinate 2.4
Deionized water 75.2
Feed D
Deionized water 319.8
Ammonium persulfate 0.42
STAGE III Amount (grams)
Feed E
Methyl methacrylate 71.0
Methyl methacrylate 12.3
Butyl acrylate 30.8
Hydroxyethyl methacrylate40.2
Methacrylic acid 22.7
Ethyleneglycol dimethacrylate34.5
Dioctylsulfosuccinate 2.4
Deionized water 97.5
Feed F
Deionized water 319.8
Ammonium persulfate 0.54
Sodium bicarbonate 1.3
Feed G
Dimethyl ethanolamine 10.9
Deionized water 176.0
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[0090] Charge #1 was added to a reactor fitted with thermocouple, agitator,
and reflux condenser. The contents of the reactor then were heated to a
temperature
of 80°C. Then Feeds A and B (sSage I) were added to the reactor over
three hours,
and the reaction mixture was stirred for 30 minutes at temperature of
80°C. Feeds C
and D (stage II) then were added over a period of 30 minutes and then stirred
for 30
minutes at 80°C. At this time Feeds E and F (Stage III) were added over
30
minutes, stirred for one hour, and cooled to ambient temperature. Then, Feed G
then was added over 5 minutes then stirred for 10 minutes more.
Polymer Example 13 (PE-13)
[0091] This example describes the preparation of a polymer with the following
ingredients:
Table 8
Amount
In redients rams
1 Dimethylpropionic 79.2
acid
2 Neopentylglycol 14.9
3 FORMREZ 55-56' 193.3
4 Poly THFZ 193.3
Dibutyl tin dilaurate 1.7
6 Butanol 3.87
7 N-methylpyrrolidone 195.6
8 DESMODUR W3 28.0
9 N-methylpyrrolidone 28.0
Deionized water 2366.4
11 Ethylenediamine 14.2
12 Dimethylethanolamine 51.8
'hydroxy functional polyester, molecular weight 2000,
available from Witco Chemicals
Zhydroxy functional polyether, made by polymerizing
tetrahydrofurane, molecular weight 2000, available from
E.I. DuPont de Neumors and Co.
'diisocyanate, available from Bayer corporation
[0092] A reactor was charged with the first seven ingredients and heated to
80°C under a nitrogen blanket until mixture became homogeneous. It was
then
cooled to 55°C and premixed ingredients 8 and 9 were added over 30
minutes. The
mixture was allowed to exotherm up to 90°C. The mixture was then held
at thus
temperature until the isocyanate equivalent weight became around 1370. The
premixed ingredients 10, 11, and 12 were then added. The product was stirred
for
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additional 30 minutes and cooled to room temperature. The final product had
total
nonvolatile component of 24%, and viscosity less than 100 centipoise.
Preparation of Aaueous Compositions
Basecoat Examples BC1-10
[0093] Aqueous silver metallic basecoat compositions containing the
passivators of Examples 1 to 10 were prepared. For each of the basecoat
compositions (Examples BC1-10 below), an aluminum pigment slurry, Premix A1-
10,
respectively, first was prepared as described below from the following
ingredients.
Amounts listed below are in parts by weight (grams). The Premix A1-10
components
were admixed under mild agitation, and the admixture was allowed to stir for
30
minutes until well dispersed. Premix A1 utilized a commercially available
passivating
material (LUBRIZOL 2062 commerciaNy available from the Lubrizol Company).
26
CA 02567038 2006-11-06
WO 2006/118577 PCT/US2005/015753
N o
8
M ~ r.M f~GO~,.)1~m
p O O O O O O O O O ~ ~ O O
O o
U a
N
N
M 00
ttjpjN p O O O O O O O O ~ O ,-~ ~ a
N ._
U
C_
a
c
M o0 0
j ~ N O O O O O O O O ~ O O e-~ 0 U
I,( N
0
N
.O
7
M ~ M M 07
~
O O O O O O O O O
Q tf>O N N 1~ O O
~ E
0
a~
M O OD
p O O O O O njO O O O ~-p O
N r-
N
n
0
M 00 N
Q ~ O O O O '-O O O O O ~ M ~ J oMo
~ D O
u7 N N ~ p
o
N
0
iY
J
c~7 N o0
p O O O O O O O
p O O ~-0 O
-
.~ N r ~ y
X
m
M S m
L(jOjN O 0 0 ~ 0 0 0 0 0 0 0 r-O ~ ~jT
-
N e- c
p) .c
ti o
~
c~m~a
y
:a N ~. N O
M :
a
M ~ I~ ~ ~ M f~o
O O O O O O O O O r- ~ o.
~ 0
N
c
p
E- E . c, N
> c dU~
~
O
.
~
u;~ m aaE ~
a
o? o~ ~
O M ~ ~ o 0 0 0 0 0 M ~ vi .n o o a
Q~~a~"=ov
Q fi OiN O c0 0 0 0 0 r-O O ao
N r, ~m ~
e
y ~
.
> ._
m.
mv
O a
U d a
~ a~
a~cao m ~~ c
a~ oio'oa m
c.
a
,
.
~ N
uu ~UO
~,~I-N c ~ ~
o
o
o
_
_y:~
co
'C~
w=r
C
Nm
N ~ f0 ~ a E
(0 N
~~w~
v m (~
v ~ x a
v_a~
E~ 3 a
a E
W c
E
~ .
n ~ ,~ ~ E _~ ~ - o.
--o'', ~
Z C M (0(Ii Lf7~ ~ o N ~ N o E
O ~
LlJ O N ~-a a o0O O c a = 3 ~ b
>, c a ~
Z c 'S,~ M N ~ ~ a E 3 a o
. .;~ 7 7 N E
O 7,0p z ~J~'.OCo~~<'oo~p.~c
W Q as
~>
O m m m m m m m m O..N
O QOM
~, E E r'N M d'LC>cfl1~COW ~ o N ?' a ~' c0 ~t
O N ~ ~~
p
p o Z ~ O W LiJLULtJLIJLJJlil11J11J>-o t a c'n ~ Q $
~ uW a
U o a I=Q a a a.a n.o.n.n.o~d U ~na N ~ < N ID 0
~
CA 02567038 2006-11-06
WO 2006/118577 PCTlUS2005/015753
[0094] Basecoat compositions (Examples BC1 to BC10) were prepared as described
below from the following ingredients. The amounts listed below are in parts by
weight
(grams) unless otherwise indicated. Basecoat composition BC1 was used as a
control and
contained the commercially available passivating material.
28
CA 02567038 2006-11-06
WO 2006/118577 PCT/US2005/015753
a~
.
,
* r'. o> <?Ice.op ch
~.
U ~ ~ O ~ N ,~.O O O O O O O O O M
O.
O
O
U
V r-co0 o i o in
m O d'O N N etO O O O O O O O ~ O
a0 r-opO O ~ O c0
m p d'O N N ,~-O O O O O O O O O O
O
U r o00 o i. ~ o
O N N etO O O O O O ~ O O O
.-a~o o m o co
m O 'd'O N N d.O O O O O njO O O O
O
O
tn ~ 0Dp O h
~,O O O O ~ O O O O O
N
H
ao0 o r. o ~ c
m p ~1'O N N eYO O O ~ O O O O O O
b
b
V ~ ao0 o r.,
C
Q N ~ O O ~ O O O O O O O
E
N r-ppO O I' p ~- ~ d
' O N N Wit'O ~ O O O O O O O O
O~~1 to
N
~
>
c U
H -
'-O O O ~ p '~ t
U ~ ~ cmn pp~ 0 0 0 0 0 0 0 0 0
Q ' O s .
O . N N tn
~t m
O
U
o a
o m
I~ Y O G) N
Z m t0t~ ~ ~ E ~
N ~ O ~ = ~ ,~_
. p ro
o J ~ Q ~ a a a a a a Q
N ~..J ~. a
o
o .~Q w o ~ x x X x x scx x x X a ~
Q ~ ~ ~ ~ ~
'~.o o ~ ~ a~E E E E ~ ~ ~E_ E ~E o '
._m Q. ~E
00 c a~a~N a~a~a~a~a~a>m - ~ o
~ Q W U o ' ' ' ' ' '
o '
U n cn ~ a ~ a a a a a a d n'.
. .
CA 02567038 2006-11-06
WO 2006/118577 PCT/US2005/015753
[0095] Each of the aqueous basecoat compositions of Examples BC1 to BC10 was
prepared by mixing the above-listed ingredients under agitation. The pH of
each
composition was adjusted to 8.4-8.6 using an appropriate amount of a 50%
aqueous
solution of DMEA. Following an equilibration period of sixteen hours at
ambient conditions,
the pH of each basecoat was readjusted to 8.4-8.6 using an appropriate amount
of a 50%
aqueous solution of DMEA. The viscosity of each of the compositions then was
reduced to
24 to 26 seconds spray viscosity (Ford #4 cup) using deionized water. The
samples were
then placed into the gassing test as described below.
GASSING EVALUATION
[0096] Each of the aqueous basecoat compositions of Examples BC1 to BC10 was
evaluated to measure the amount of gas evolved from an aluminum flake-
containing
waterborne coating. The test method was used to determine the effectiveness of
aluminum
flake passivators (i.e., gassing inhibitors) in stopping or inhibiting the
reaction between the
aluminum pigment surface and water, which generates hydrogen gas and heat. The
method
included loading an aluminum flake-containing waterborne paint into a gassing
experiment
apparatus which measured the amount of gas evolved in milliliters (ml) of gas
evolved per
200 grams of basecoat composition over a period of 7 days.
[0097] Following the final pH and viscosity adjustments described above, 200
grams
of each basecoat composition was placed into a separate 250 ml Erlenmeyer
flask and
capped with a greased glass adapter with a hose connector (Tygon tubing). A
taper clip was
attached at the joint of the flask and adapter. A lead weight was placed
around each of the
filled Erlenmeyer flasks and each was then placed into a pre-set constant
temperature bath
of 40°C. Four hours in the bath was then allowed for temperature
equilibration.
[0098] While the compositions were equilibrating, ring stands and burettes
were
assembled in a Nalgene tub next to the constant temperature bath. Ring stands
were
placed in the Nalgene tub filled with water. Burette clamps were attached to
the ring stands.
For each basecoat, a 250 ml burette was filled with water and inverted in the
Nalgene tub
filled with water. The inverted burette was placed so that the top of the
inverted burette was
below the top of the water level in the tub. The burettes were clamped into
place with
burette clamps.
[0099] Following the equilibration period, the Tygon tubing was inserted into
the
inverted burette and then aftached to the end of the hose adapter on the
flasks inside the
constant temperature bath. The initial water level in the burette was then
recorded (in ml).
The difference between the initial water level and the final water level after
7 days in the test
apparatus was recorded as the amount of gas evolved from the basecoat. As will
be
CA 02567038 2006-11-06
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appreciated by one skilled in the art, gassing results can differ from one run
to another due
to slight changes in the experimental conditions. Therefore, the gassing
results in Table 11
should be understood to have a tolerance of plus or minus about 5 ml.
[0100] The gassing data presented in Table 11 below illustrates that aqueous
metallic
basecoat compositions containing the aluminum passivators of the present
invention (i.e.,
the compositions of Examples BC2 to BC14) provide similar or improved aluminum
flake
passivation as compared with the commercially available passivator (Example
BC1 ).
TABLE 11
BASECOAT GAS Evolved
(in ml)
Example BC1 12-18
*
Example BC2 10
Example BC3 0
Example BC4 3
Example BC5 8
Example BC6 0
Example BC7 4
Example BC8 0
Example BC9 6
Example BC10* 15
* Comparative Example
Basecoat Examales BC11 to BC13
[0101] The following Examples BC11 to BC13 describe the preparation of aqueous
silver metallic basecoat compositions. For each of the basecoat compositions
of Examples
BC11 to BC13, an aluminum pigment slurry, Premix A11-13, respectively, first
was prepared
as described below from the following ingredients. Amounts listed below are in
parts by
weight (grams). The Premix A11-13 components were admixed under agitation, and
the
admixture was allowed to stir for 30 minutes until well dispersed. Premix A11
utilized a
commercially available passivating mater7al (LUBRIZOL 2062 commercially
available from
the Lubrizol Company).
31
CA 02567038 2006-11-06
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Table 12
Premix A11-13
COMPONENT A11 A12 A13
Ethylene Glycol Monohexyl40.3 40.3 40.3
ether
1-octanol 8.1 8.1 8.1
Phosphatized epoxy" 1.0 1.0 1.0
TINUVIN 1130'2 3.0 3.0 3.0
Aluminum Paste'3 27.2 27.2 27.2
Aluminum Passivator'~ 5.6 0 0
PE1 0 6.2 0
PE2 0 0 6.2
CYMEL~ 327'5 11.2 11.2 11.2
" Reaction product of EPON 828 and phosphortc acid at a weight ratio of 83 to
17.
'Z Substituted benzotriazole UV light absorber available from Ciba Additives.
"Aluminum pigment paste ALPATE 7670NS available from Toyal Europe.
"A 60/36/4 w/w solution of LUBRIZOL 2062/diisopropanolaminelPropylene glycol
Butyl ether. LUBRIZOL
2062 is available from the Lubrizol Co.
'S Methylated melamine formaldehyde resin available from Cytec Industries,
Inc.
Aaueous Basecoat Compositions
(0102] Each of the aqueous basecoat compositions of Examples BC11 to BC13 was
next prepared as described below from the following ingredients. Amounts
listed below are
in parts by weight (grams) unless otherwise indicated.
32
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Table 13
COMPONENT BC BC12 BC13
11
Polyester / Acrylic 134.1 134.1 134.1
Latex'e
Mineral Spirits" 6.0 6.0 6.0
Witcobond~ W-242'8 43.3 43.3 43.3
Acrylic Latex'9 76.5 76.5 76.5
50% Aqueous DMEA 3.0 3.0 3.0
Deionized Water 332.9 332.9 332.9
Premix A11 96.4 0 0
Premix A12 0 97.0 0
Premix A13 0 0 97.0
Aqueous Thickener 50.0 50.0 50.0
Solutionz
Viscolam~ 3302' 3.3 3.3 3.3
50% Aqueous DMEA 1.6 1.6 1.6
'8 PE = Polymer of Example
"Mineral Spirits available from Shell Chemical Co.
'e Aqueous polyurethane dispersion available from Crompton Corp.
'B PE = Polymer of Example
Zo 2% solution of LAPONITE RD in deionized water. LAPONITE RD is a synthetic
clay available from
Southern Clay Products, Inc.
Z' Vlscolam 330 is an acrylic thickener emulsion available from Lehmann &
Voss.
[0103] Each of the aqueous basecoat compositions of Examples BC11-13 was
prepared by mixing the above-listed ingredients under agitation. The pH of
each composition
was adjusted to 8.4--8.6 using an appropriate amount of a 50% aqueous solution
of DMEA.
The viscosity of each of the aqueous basecoat compositions then was reduced to
33 to 37
seconds spray viscosity (DIN #4 cup) using deionized water.
GASSING EVALUATION
[0104] Each of the aqueous basecoat compositions of Examples BC11 to BC13
were evaluated according to the gassing test method described previously for
Examples
BC1 to BC10.
[0105] The gassing data presented in Table 14 below illustrates that aqueous
metallic basecoat compositions containing the aluminum passivators of the
present invention
(i.e., the compositions of Examples BC12 to BC13) provide similar or improved
aluminum
flake passivation as compared with the control passivator (i.e., the
composition of Example
BC11) containing the commercially available passivating material.
33
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Table 14
BASECOAT Gas Evolved (in
ml)
Example BC11 9
Example BC12 0
Example BC13 6
Examples BC14 to BC17
[0106] The following Examples BC14 to BC17 (Table 16) describe the preparation
of
aqueous silver metallic basecoat compositions containing the passivators of
Examples A14
to A17, respectively of Table 15. For each of the basecoat compositions of
Examples BC14
to BC17, aluminum pigment slurry, Premix A14-17, respectively, first was
prepared as
described below from the following ingredients. Amounts listed below are in
parts by weight
(grams). The .Premix A14-17 components were admixed under agitation, and the
admixture
was allowed to stir for 30 minutes until well dispersed.
[0107] As shown in Table 15, Premixes 14, 16, and 17 contained known
passivating
materials while Premix 15 contained a passivating material of the invention.
All the premixes
in Table 15 have 15 weight percent passivator of the invention based on the
weight percent
of aluminum pigment.
34
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Table 15
Premix A14-17
Basecoat A14 A15 A16 ComparativeA17 Comparative
DPM Glycol Ether 56 56 56 56
Polypropylene 57 57 57 57
Glycol
TINUVIN 1130 16 16 16 16
Aluminum Paste 94 94 94 94
Aluminum Passivator
Lubrizol 2062 25 - - -
PE 24 - 33 - -
Comparative passivator
#1' - - 17 -
Comparative passivator
#2z - - - 24
Nitroethane3 - - - 8
Phosphatized epoxy4 4 4 4
'' passivating material described in Example 2of U.S. Patent No. 5 389139.
2' passivating material described in Example 1 of U.S. Patent No. 5,215,579.
3' from Aldrich Chemical Co.
PE= Polymer of Example
Aaueous Basecoat Compositions
[0108] The Premixes A11 to A14 were used to prepare aqueous basecoat
compositions (Examples BC14 to BC17) as set forth below in Table 16. Amounts
listed
below are in parts by weight (grams) with 15 weight percent passivator based
on the amount
of aluminum pigment unless otherwise indicated.
CA 02567038 2006-11-06
WO 2006/118577 PCT/US2005/015753
Table 16
BC14 BC16 BC17
ComparativeBC15 ComparativeComparative
Deionized Water 291 291 291 291
PE-10 547 547 547 547
50% Aqueous DMEA 10 10 10 10
CYMEL 385' 205 ' 205 205 205
N-butoxypropanol 153 153 153 153
Mineral Spirits 23 23 23 23
Premix A14 252 - - -
Premix A15 - 260 - -
Premix A16 - - 244 -
Premix A17 - - - 259
Polymer of Example15 15 15 15
13
Rheology modifierz61 61 61 61
'' melamine resin available from Cytec Industries, Inc
2'rheology modifier made by reacting 42.9 g of 4-methylhexahydrophthalic
anhydride, 18.4 g hexahydrophthalic
anhydride, and 38.7 g neopentylglycolhydoxypivalate at 200 °C then
diluting with methylisobuty) ketone to a solid
content of 80 percent with an acid value of 165.
[0109 Each of the aqueous basecoat compositions of Examples BC14 to BC17 was
prepared by mixing the above-listed ingredients under agitation. The pH of
each
composition was adjusted to 8.4-8.6 using an appropriate amount of a 50%
aqueous
solution of DMEA. Following an equilibration period of sixteen hours at
ambient conditions,
the pH of each basecoat was readjusted to 8.4-8.6 using an appropriate amount
of a 50%
aqueous solution of DMEA. The viscosity of each of the compositions then was
reduced to
24 to 26 seconds spray viscosity (Ford #4. cup) using deionized water. The
samples were
then placed into the gassing test as described below.
GASSING EVALUATION
[0110] Each of the aqueous basecoat compositions of Examples BC14 to BC17 was
evaluated according to a test method that measures the amount of gas evolved
from an
aluminum flake-containing waterborne coating. This test method is used to
determine the
effectiveness of aluminum flake passivators (i.e., gassing inhibitors) in
stopping or inhibiting
the reaction between the aluminum pigment surface and water, which generates
hydrogen
gas and heat. The method involves loading an aluminum flake-containing
waterborne paint
into a gassing experiment apparatus that measures the amount of gas evolved in
ml of gas
per 250 gram of paint over 7 days.
36
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[0111] Following the final pH and viscosity adjustments described above, 250
grams
of each basecoat was placed into a gassing bottle and placed in a waterbath of
40°C. Each
sample was placed into the waterbath as quickly as possible to after it was
reduced to
capture all possible gassing. The results are set forth in Table 17.
Table 17
Basecoat ~ Gassing Evolved
in mL
BC14* 24
BC 15 11.9
BC 16* 44.2
BC 17* 17.4
comparative examples
[0112] From the results shown in Table 17, the passivating material of the
invention
provided improved gassing properties compared to the other known passivating
materials.
E)CAAAPLE 2
[0113] This Example illustrates the effect of a passivating material of the
invention on
the appearance characteristics of a coated article.
[0114] The coating compositions B15 and B18-20 were evaluated for various
appearance characteristics as set forth in Table 18 below. B18, B19, and B20
are the same
as B14, B16, and B17, respectively, but have 20 weight percent passivator
instead of 15
weight percent passivator.
Table 18
B18 B15 B19 B20
Wt.% passivator20 15 20 20
Flip/Flop' 1.54 1.52 1.44 1.46
L152 132.08 131.13 126.91 126.49
C03 49 51 30 52
Gassing4 <5 <5 33.7 <5
ml
' calculated by obtaining L15, L45, and L110 values using an X-RITE
spectrophotometer and calculaflng fllplflop from
these values. The larger the flipfflop value, the brighter L15 and the darker
L110 values are.
2 brightness measured at 15° using an X RITE Spectrophotometer. The
higher the value the more brilliant the color.
'Autospec = combined average of gloss, distinctness of image, and orange peel
determined using a conventional
Autospec Quality Measurement System (ASTM 0631 ).
' gassing less than 10 ml is considered acceptable
37
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[0115) It will be readily appreciated by those skilled in the art that
modifications may be
made to the invention without departing from the concepts disclosed in the
foregoing
description. Accordingly, the particular embodiments described in detail
herein are
illustrative only and are not limiting to the scope of the invention, which is
to be given the full
breadth of the appended claims and any and all equivalents thereof.
38
