Note: Descriptions are shown in the official language in which they were submitted.
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
ACID CLEANERS FOR METAL SUBSTRATES AND ASSOCIATED
METHODS FOR CLEANING AND COATING METAL SUBSTRATES
FIELD OF THE INVENTION
[0001] The present invention relates to acid cleaners for metal
substrates and
associated methods for cleaning metal substrates with the acid cleaners prior
to
application of a pretreatment composition and/or an electrodepositable coating
composition.
BACKGROUND INFORMATION
[0002] The use of protective coatings on metal substrates for improved
corrosion resistance and paint adhesion is common. Conventional techniques for
coating such substrates include techniques that involve pretreating the metal
substrate
with a pretreatment composition and/or with an electrodepositable coating
composition.
SUMMARY OF THE INVENTION
[0003] In certain embodiments, the present invention is directed to a
method
comprising: (a) contacting a substrate with an acid; and then (b) contacting
the
substrate with an electrodepositable coating composition comprising (i) a film-
forming polymer; and (ii) a corrosion inhibitor; with the proviso that the
method does
not comprise contacting the substrate with a pretreatment composition prior to
step
(b).
DETAILED DESCRIPTION OF THE INVENTION
[0004] For purposes of the following detailed description, it is to be
understood that the invention may assume various alternative variations and
step
sequences, except where expressly specified to the contrary. Moreover, other
than in
any operating examples, or where otherwise indicated, all numbers expressing,
for
example, quantities of ingredients 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 parameters set forth in the
following
specification and attached claims are approximations that may vary depending
upon
1
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
the desired properties 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 parameter should at least be construed in light of
the
number of reported significant digits and by applying ordinary rounding
techniques.
[0005] Notwithstanding that the numerical ranges and parameters setting
forth
the broad scope of the invention are approximations, the numerical values set
forth in
the specific examples are reported as precisely as possible. Any numerical
value,
however, inherently contains certain errors necessarily resulting from the
standard
variation found in their respective testing measurements.
[0006] Also, it should be understood that any numerical range recited
herein is
intended to include all sub-ranges subsumed therein. For example, a range of
"1 to
10" is intended to include all sub-ranges between (and including) the recited
minimum value of 1 and the recited maximum value of 10, that is, having a
minimum
value equal to or greater than 1 and a maximum value of equal to or less than
10.
[0007] In this application, the use of the singular includes the plural
and plural
encompasses singular, unless specifically stated otherwise. In addition, in
this
application, the use of "or" means "and/or" unless specifically stated
otherwise, even
though "and/or" may be explicitly used in certain instances.
[0008] Certain embodiments of the present invention are directed to
methods
for cleaning a substrate by contacting the metal substrate with an acid.
[0010] The acid cleaned substrate, in certain embodiments, may then be
contacted with a pretreatment composition. In certain of these embodiments,
the
pretreatment composition includes a group IIIB and/or IVB metal compound,
wherein
the citric acid cleaner acts to provide increased deposition of the group IIIB
and/or
IVB metal onto the metal substrate surface, wherein the increased metal
content acts
to improve corrosion resistance.
[0011] In certain other embodiments, a film forming composition, such
as an
electrodepositable coating composition, may be applied over the acid cleaned
and
optionally pretreated substrate. In these embodiments, the acid provides
improved
corrosion protection to the coated substrate as compared with coated and
uncleaned
substrates or substrates cleaned with alkaline cleaners and coated as
described above.
[0012] In certain other embodiments, a film forming composition, such
as an
electrodepositable coating composition, may be applied over the acid cleaned
2
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
substrate without first contacting the substrate with a pretreatment
composition. In
certain of these embodiments, the acid acts to improve corrosion resistance of
these
acid cleaned and electrocoated substrates as compared with coated and
uncleaned
substrates or substrates cleaned with alkaline cleaners and electrocoated as
described
above.
[0013] Each of these embodiments is described below:
Substrate
[0014] Suitable substrates that can be cleaned and coated in accordance
with
the present invention include, without limitation, metal substrates, metal
alloy
substrates, and/or substrates that have been metallized, such as nickel plated
plastic.
In some embodiments, the metal or metal alloy can be aluminum and/or steel.
For
example, the steel substrate could be cold rolled steel, electrogalvanized
steel, and hot
dipped galvanized steel. Moreover, in some embodiments, the substrate may
comprise a portion of a vehicle such as a vehicular body (e.g., without
limitation,
door, body panel, trunk deck lid, roof panel, hood, and/or roof) and/or a
vehicular
frame. As used herein, "vehicle" or variations thereof includes, but is not
limited to,
civilian, commercial, and military land vehicles such as cars, motorcycles,
and trucks.
Cleaning
[0015] In certain embodiments, the substrates may be contacted with an
acid
prior to contacting the substrate with a pretreatment composition and/or an
electrodepositable coating composition.
[0016] While not wanting to be bound by any theory, it is believed that
the
acid etches the substrate to provide increased surface area to the substrate.
Increased
surface area is believed to provide improved adhesion between the substrate
and the
subsequently applied coating materials, which is believed to improve corrosion
resistance to the coated panels. In addition, increased etching of the
substrate material
is believed to allow for increased deposition of metal from the pretreatment
composition, when utilized, which also is believed to increase corrosion
resistance to
the coated panels. Further, increased etching of the substrate material is
believed for
increased deposition of metal from the electrodepositable coating composition,
when
utilized, at the interface between the electrodepositable coating composition
and the
substrate, which may provide even more corrosion resistance to the coated
panels.
3
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[0017] In certain embodiments, the acid comprises a single acid, while
in
other embodiments the acid comprises a mixture of acids.
[0018] In certain embodiments, the acid comprises a weak acid, while in
other
embodiments the acid comprises a strong acid. A weak acid, by definition, is
an acid
that dissociates incompletely (i.e. it does not release all its hydrogens in
solution),
while a strong acid is an acid that ionizes completely in an aqueous solution
(i.e.
which release all of their hydrogen atoms when dissolved in water).
[0019] In still other embodiments, the acid comprises an organic acid.
An
organic compound, by definition, is an organic compound having acidic
properties.
Exemplary organic acids include uric acid, sulfonic acid, and carboxylic acids
including lactic acid, formic acid, citric acid, and oxalic acid, as well as
mixtures
thereof.
[0020] In still other embodiments, the acid comprises a mineral acid. A
mineral acid, by definition, is an acid derived from an inorganic compound.
Exemplary mineral acids include hydrochloric acid, sulfuric acid, boric acid,
phosphoric acid, hydrofluoric acid, hydrobromic acid, nitric acid, and
mixtures
thereof.
[0021] In still other embodiments, the acid may comprise any
combination of
one or more organic acids and/or mineral acids.
[0022] In certain of these embodiments, the carboxylic acid selected
for use in
the compositions described herein has a water solubility of > 1 g/L at 20 C.
Carboxylic acids suitable for use include, for example, monocarboxylic acids,
such as
formic acid, acetic acid, propionic acid, methylacetic acid, butyric acid,
ethylacetic
acid, n-valeric acid, n-butanecarboxylic acid, acrylic acid, propiolic acid,
methacrylic
acid, palmitic acid, stearic acid, oleic acid, linolic acid, and linolenic
acid;
dicarboxylic acids, such as oxalic acid, malonic acid, succinic acid, glutaric
acid,
adipic acid, pimelic acid, suberic acid, azelaic acid, lepargilic acid,
sebacic acid,
maleic acid, and fumaric acid; aliphatic hydroxy acids, such as glycolic acid,
lactic
acid, tartronic acid, glyceric acid, malic acid, tartaric acid, citramalic
acid, citric acid,
isocitric acid, leucine acid, mevalonic acid, pantoic acid, recinoleic acid,
ricinelaidic
acid, cerebronic acid, quinic acid, and shikimic acid; aromatic hydroxy acids,
such as
salicylic acid, creosote acid, vanillic acid, syringic acid, pyrocatechuic
acid, resorcylic
4
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
acid, protocatechuic acid, gentisic acid, orsellinic acid, gallic acid,
mandelic acid,
benzilic acid, atrolactinic acid, melilotic acid, phloretic acid, coumaric
acid, umbellic
acid, caffeic acid, ferulic acid, and sinapic acid. Mixtures of any of the
foregoing may
also be used.
[0023] In certain embodiments, the acid is incorporated into an acid
cleaner
that also may include other components such as water, surfactants and/or
buffers,
including commercially available surfactants and/or buffers.
[0024] In certain other embodiments, the substrate to be treated in
accordance
with the methods of the present invention may first be cleaned to remove
grease, dirt,
or other extraneous matter. This is often done by employing mild or strong
alkaline
cleaners, such as are commercially available and conventionally used in metal
pretreatment processes. Examples of alkaline cleaners suitable for use in the
present
invention include Chemkleen 163, Chemkleen 177, Chemkleen 2010LP and
Chemkleen 490MX, each of which are commercially available from PPG Industries,
Inc. In certain embodiments, a surfactant may also be included in the alkaline
cleaner, such as 181LP, commercially available from PPG Industries, Inc. Such
cleaners are often followed and/or preceded by a water rinse. After cleaning,
the bare
substrate materials may be rinsed thoroughly with deionized water.
[0025] In certain of these embodiments, the alkaline cleaner is applied
to the
substrate prior to the acid cleaner, while in other embodiments the acid
cleaner is
applied to the substrate prior to the alkaline cleaner.
Pretreatment
[0026] In certain embodiments of the methods of the present invention,
after
the substrate is contacted with the acid, it may then be contacted with a
pretreatment
composition. As used herein, the term "pretreatment composition" refers to a
composition that upon contact with a substrate reacts with and chemically
alters the
substrate surface and binds to it to form a protective layer.
[0027] In certain other embodiments of the present invention, the
pretreatment
composition comprises a group IIIB and/or IVB metal compound.
[0028] In certain embodiments, the pretreatment composition comprises a
carrier, often an aqueous medium, so that the composition is in the form of a
solution
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
or dispersion of a group IIIB or IVB metal compound in the carrier. In these
embodiments, the solution or dispersion may be brought into contact with the
substrate by any of a variety of known techniques, such as dipping or
immersion,
spraying, intermittent spraying, dipping followed by spraying, spraying
followed by
dipping, brushing, or roll-coating. In certain embodiments, the solution or
dispersion
when applied to the metal substrate is at a temperature ranging from 60 to 150
F (15
to 65 C). The contact time is often from 10 seconds to five minutes, such as
30
seconds to 2 minutes.
[0029] As used herein, the term "group IIIB and/or IVB metal" refers to
an
element that is in group IIIB or group IVB of the CAS Periodic Table of the
Elements
as is shown, for example, in the Handbook of Chemistry and Physics, 63'
edition
(1983). Where applicable, the metal themselves may be used. In certain
embodiments, a group IIIB and/or IVB metal compound is used. As used herein,
the
term "group IIIB and/or IVB metal compound" refers to compounds that include
at
least one element that is in group IIIB or group IVB of the CAS Periodic Table
of the
Elements.
[0030] In certain embodiments, the group IIIB and/or IVB metal compound
used in the pretreatment composition is a compound of zirconium, titanium,
hafnium,
yttrium, cerium, or a mixture thereof. Suitable compounds of zirconium
include, but
are not limited to, hexafluorozirconic acid, alkali metal and ammonium salts
thereof,
ammonium zirconium carbonate, zirconyl nitrate, zirconium carboxylates and
zirconium hydroxy carboxylates, such as hydrofluorozirconic acid, zirconium
acetate,
zirconium oxalate, ammonium zirconium glycolate, ammonium zirconium lactate,
ammonium zirconium citrate, and mixtures thereof. Suitable compounds of
titanium
include, but are not limited to, fluorotitanic acid and its salts. A suitable
compound of
hafnium includes, but is not limited to, hafnium nitrate. A suitable compound
of
yttrium includes, but is not limited to, yttrium nitrate. A suitable compound
of cerium
includes, but is not limited to, cerous nitrate.
[0031] In certain embodiments, the group IIIB and/or IVB metal compound
is
present in the pretreatment composition in an amount of at least 10 ppm metal,
such
as at least 100 ppm metal, or, in some cases, at least 150 ppm metal. In
certain
embodiments, the group IIIB and/or IVB metal compound is present in the
6
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
pretreatment composition in an amount of no more than 5000 ppm metal, such as
no
more than 300 ppm metal, or, in some cases, no more than 250 ppm metal. The
amount of group IIIB and/or IVB metal in the pretreatment composition can
range
between any combination of the recited values inclusive of the recited values.
The pH
of the pretreatment composition often ranges from 2.0 to 7.0, such as 3.5 to
5.5. The
pH of the pretreatment composition may be adjusted using, for example, any of
the
acids and bases identified earlier with respect to cleaning the substrate.
[0032] In some embodiments, the pretreatment composition may be a
silane or
a non-crystalline phosphate, such as iron phosphate, containing pretreatment
composition. Suitable silane containing pretreatment compositions include, but
are
not limited to, certain commercially available products, such as Silquest A-
1100
Silane, which is described in the Examples herein and which is commercially
available from Momentive Performance Materials. Suitable non-crystalline
phosphate containing pretreatment composition include pretreatment composition
that
comprise, iron phosphate, manganese phosphate, calcium phosphate, magnesium
phosphate, cobalt phosphate, or an organophosphate and/or organophosphonate,
such
as is disclosed in United States Patent Nos. 5,294,265 at col. 1, line 53 to
col. 3, line
12 and 5,306,526 at col. 1, line 46 to col. 3, line 8, the cited portions of
which being
incorporated herein by reference. Suitable non-crystalline phosphate
containing
pretreatment compositions are commercially available, such as Chemfos0 158 and
Chemfos0 Si, which are iron phosphate pretreatment compositions commercially
available from PPG Industries, Inc.
[0033] In certain embodiments, the pretreatment composition also
comprises
an electropositive metal, such as copper. The source of electropositive metal,
such as
copper, in the pretreatment composition may comprise, for example, any of the
materials described earlier with respect to the plating solution. In certain
embodiments, the electropositive metal is included in such pretreatment
compositions
in an amount of at least 1 ppm, such as at least 5 ppm, or in some cases, at
least 10
ppm of total metal (measured as elemental metal). In certain embodiments, the
electropositive metal is included in such pretreatment compositions in an
amount of
no more than 500 ppm, such as no more than 100 ppm, or in some cases, no more
than 50 ppm of total metal (measured as elemental metal).
7
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[0034] In certain embodiments, the pretreatment composition comprises a
resinous binder. Suitable resins include reaction products of one or more
alkanolamines and an epoxy-functional material containing at least two epoxy
groups,
such as those disclosed in United States Patent No. 5,653,823. In some cases,
such
resins contain beta hydroxy ester, imide, or sulfide functionality,
incorporated by
using dimethylolpropionic acid, phthalimide, or mercaptoglycerine as an
additional
reactant in the preparation of the resin. Alternatively, the reaction product
is that of
the diglycidyl ether of Bisphenol A (commercially available from Shell
Chemical
Company as EPON 880), dimethylol propionic acid, and diethanolamine in a 0.6
to
5.0:0.05 to 5.5:1 mole ratio. Other suitable resinous binders include water
soluble and
water dispersible polyacrylic acids as disclosed in United States Patent Nos.
3,912,548 and 5,328,525; phenol formaldehyde resins as described in United
States
Patent Nos. 5,662,746; water soluble polyamides such as those disclosed in WO
95/33869; copolymers of maleic or acrylic acid with allyl ether as described
in
Canadian patent application 2,087,352; and water soluble and dispersible
resins
including epoxy resins, aminoplasts, phenol-formaldehyde resins, tannins, and
polyvinyl phenols as discussed in United States Patent No. 5,449,415.
[0035] In these embodiments of the present invention, the resinous
binder is
present in the pretreatment composition in an amount of 0.005 percent to 30
percent
by weight, such as 0.5 to 3 percent by weight, based on the total weight of
the
ingredients in the composition.
[0036] In other embodiments, however, the pretreatment composition is
substantially free or, in some cases, completely free of any resinous binder.
As used
herein, the term "substantially free", when used with reference to the absence
of
resinous binder in the pretreatment composition, means that any resinous
binder is
present in the pretreatment composition in an amount of less than 0.005
percent by
weight. As used herein, the term "completely free" means that there is no
resinous
binder in the pretreatment composition at all.
[0037] The pretreatment composition may optionally contain other
materials,
such as nonionic surfactants and auxiliaries conventionally used in the art of
pretreatment. In an aqueous medium, water dispersible organic solvents, for
example,
alcohols with up to about 8 carbon atoms, such as methanol, isopropanol, and
the like,
8
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
may be present; or glycol ethers such as the monoalkyl ethers of ethylene
glycol,
diethylene glycol, or propylene glycol, and the like. When present, water
dispersible
organic solvents are typically used in amounts up to about ten percent by
volume,
based on the total volume of aqueous medium.
[0038] Other optional materials include surfactants that function as
defoamers
or substrate wetting agents, such as those materials and amounts described
earlier
with respect to the plating solution.
[0039] In certain embodiments, the pretreatment composition also
comprises a
reaction accelerator, such as nitrite ions, nitro-group containing compounds,
hydroxylamine sulfate, persulfate ions, sulfite ions, hyposulfite ions,
peroxides, iron
(III) ions, citric acid iron compounds, bromate ions, perchlorinate ions,
chlorate ions,
chlorite ions as well as ascorbic acid, citric acid, tartaric acid, malonic
acid, succinic
acid and salts thereof. Specific examples of suitable materials and their
amounts are
described in United States Patent Application Publication No. 2004/0163736 Al
at
[0032] to [0041], the cited portion of which being incorporated herein by
reference.
[0040] In certain embodiments, the pretreatment composition also
comprises a
filler, such as a siliceous filler. Non-limiting examples of suitable fillers
include
silica, mica, montmorillonite, kaolinite, asbestos, talc, diatomaceous earth,
vermiculite, natural and synthetic zeolites, cement, calcium silicate,
aluminum
silicate, sodium aluminum silicate, aluminum polysilicate, alumina silica
gels, and
glass particles. In addition to the siliceous fillers other finely divided
particulate
substantially water-insoluble fillers may also be employed. Examples of such
optional fillers include carbon black, charcoal, graphite, titanium oxide,
iron oxide,
copper oxide, zinc oxide, antimony oxide, zirconia, magnesia, alumina,
molybdenum
disulfide, zinc sulfide, barium sulfate, strontium sulfate, calcium carbonate,
and
magnesium carbonate.
[0041] As indicated, in certain embodiments, the pretreatment
composition is
substantially or, in some cases, completely free of chromate and/or heavy
metal
phosphate. As used herein, the term "substantially free" when used in
reference to the
absence of chromate and/or heavy metal phosphate, such as zinc phosphate, in
the
pretreatment composition means that these substances are not present in the
composition to such an extent that they cause a burden on the environment.
That is,
9
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
they are not substantially used and the formation of sludge, such as zinc
phosphate,
formed in the case of using a treating agent based on zinc phosphate, is
eliminated.
[0042] Moreover, in certain embodiments, the pretreatment composition
is
substantially free, or, in some cases, completely free of any organic
materials. As
used herein, the term "substantially free", when used with reference to the
absence of
organic materials in the composition, means that any organic materials are
present in
the composition, if at all, as an incidental impurity. In other words, the
presence of
any organic material does not affect the properties of the composition. As
used
herein, the term "completely free" means that there is no organic material in
the
composition at all.
[0043] In certain embodiments, the film coverage of the residue of the
pretreatment coating composition generally ranges from 1 to 1000 milligrams
per
square meter (mg/m2), such as 10 to 400 mg/m2. The thickness of the
pretreatment
coating can vary, but it is generally very thin, often having a thickness of
less than 1
micrometer, in some cases it is from 1 to 500 nanometers, and, in yet other
cases, it is
to 300 nanometers.
[0044] In certain other embodiments of the present invention, the
pretreatment
composition comprises (a) a rare earth metal; and (b) a zirconyl compound.
These
pretreatment compositions are applied directly to the metal substrate without
the prior
application of an electropositive metal (i.e. in a one-step pretreatment
process).
[0045] Often, the pretreatment composition comprises a carrier, often
an
aqueous medium, so that the composition is in the form of a solution or
dispersion of
the rare earth metal compound and/or other pretreatment composition components
in
the carrier. In these embodiments, the solution or dispersion may be brought
into
contact with the substrate by any of a variety of known techniques, such as
dipping or
immersion, spraying, intermittent spraying, dipping followed by spraying,
spraying
followed by dipping, brushing, or roll-coating. In certain embodiments, the
solution or
dispersion when applied to the metal substrate is at a temperature ranging
from 60 to
150 F. (15 to 65 C.). The contact time is often from 10 seconds to five
minutes, such
as 30 seconds to 2 minutes.
[0046] As defined by IUPAC and used herein, rare earth elements or rare
earth metals are a collection of seventeen chemical elements in the periodic
table,
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
specifically the fifteen lanthanoids (the fifteen elements with atomic numbers
57
through 71, from lanthanum to lutetium) plus scandium and yttrium. Where
applicable, the metal themselves may be used. In certain embodiments, a rare
earth
metal compound is used. As used herein, the term "rare earth metal compound"
refers
to compounds that include at least one element that is a rare earth element as
defined
above.
[0047] In certain embodiments, the rare earth metal compound used in
the
pretreatment composition is a compound of yttrium, cerium, praseodymium, or a
mixture thereof. Exemplary compounds that may be used include praseodymium
chloride, praseodymium nitrate, praseodymium sulfate, cerium chloride, cerium
nitrate, cerium sulfate, yttrium chloride, yttrium nitrate, yttrium sulfate.
[0048] In certain embodiments, the rare earth metal compound is present
in
the pretreatment composition in an amount of at least 10 ppm metal, such as at
least
100 ppm metal, or, in some cases, at least 150 ppm metal. In certain
embodiments,
the rare earth metal compound is present in the pretreatment composition in an
amount of no more than 5000 ppm metal, such as no more than 300 ppm metal, or,
in
some cases, no more than 250 ppm metal. The amount of rare earth metal in the
pretreatment composition can range between any of the recited values inclusive
of the
recited values.
[0049] As noted above, the pretreatment composition also comprises a
zirconyl compound. A zirconyl compound, as defined herein, refers to a
zirconium
compound with an oxide or a hydroxide group on a zirconium atom.
[0050] In certain embodiments, the zirconyl compound in the
pretreatment
composition is zirconyl nitrate (ZrO(NO3)2), zirconyl acetate, zirconyl
carbonate,
zirconyl sulfate, or a mixture thereof.
[0051] In certain embodiments, the ratio of zirconium (from the
zirconyl
compound or compounds) to rare earth metal (from the rare earth metal or rare
earth
metal compound) is between 200/1 and 1/1. In other embodiments, the ratio is
between 100/1 and 2/1. In certain embodiments, the ratio is 20/1.
[0052] In certain embodiments, the pretreatment composition also
includes a
group IIIB, group IVB, and/or group VB metal. As used herein, the term "group
IIIB,
11
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
group IVB, and/or group VB metal" refers to an element that is in group IIIB
or group
IVB or group VB of the CAS Periodic Table of Elements as is shown, for
example, in
the Handbook of Chemistry and Physics, 63rd edition (1983). Where applicable,
the
metal themselves may be used. In certain embodiments, a group IIIB, group IV
and/or a group VB metal compound is used. As used herein, the term "a group
IIIB,
group IV and/or a group VB metal compound" refers to compounds that include at
least one element that is in the group IIIB or group IVB or group VB of the
CAS
Periodic Table of Elements.
[0053] In certain embodiments, the group IIIB or group IVB or group VB
metal compound used in the pretreatment composition is a compound of
zirconium,
titanium, hafnium, yttrium, cerium, praseodymium, or a mixture thereof.
Suitable
compounds of zirconium include, but are not limited to, hexafluorozirconic
acid,
alkali metal and ammonium salts thereof, ammonium zirconium carbonate,
zirconyl
nitrate, zirconium carboxylates and zirconium hydroxy carboxylates, such as
hydrofluorozirconic acid, zirconium acetate, zirconium oxalate, ammonium
zirconium
glycolate, ammonium zirconium lactate, ammonium zirconium citrate, and
mixtures
thereof. Suitable compounds of titanium include, but are not limited to,
fluorotitanic
acid and its salts. A suitable compound of hafnium includes, but is not
limited to,
hafnium nitrate. A suitable compound of yttrium includes, but is not limited
to,
yttrium nitrate. A suitable compound of cerium includes, but is not limited
to, cerous
nitrate.
[0054] In certain embodiments, the group IIIB or group IVB or group VB
metal compound is present in the pretreatment composition in an amount of at
least 10
ppm metal, such as at least 100 ppm metal, or, in some cases, at least 150 ppm
metal.
In certain embodiments, the group IIIB or group IVB or group VB metal compound
is
present in the pretreatment composition in an amount of no more than 5000 ppm
metal, such as no more than 300 ppm metal, or, in some cases, no more than 250
ppm
metal. The amount of group IIIB or group IVB or group VB metal in the
pretreatment
composition can range between any combination of the recited values inclusive
of the
recited values.
[0055] In certain embodiments, the pretreatment composition also
comprises
an electropositive metal. As used herein, the term "electropositive metal"
refers to
12
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
metals that are more electropositive than the metal substrate. This means
that, for
purposes of the present invention, the term "electropositive metal"
encompasses
metals that are less easily oxidized than the metal of the metal substrate. As
will be
appreciated by those skilled in the art, the tendency of a metal to be
oxidized is called
the oxidation potential, is expressed in volts, and is measured relative to a
standard
hydrogen electrode, which is arbitrarily assigned an oxidation potential of
zero. The
oxidation potential for several elements is set forth in the table below. An
element is
less easily oxidized than another element if it has a voltage value, E*, in
the following
table, that is greater than the element to which it is being compared.
Element Half-cell reaction Voltage, E*
Potassium K+ + e ¨> K -2.93
Calcium Ca2+ + 2e ¨> Ca -2.87
Sodium Na + + e ¨> Na -2.71
Magnesium Mg2+ + 2e ¨> Mg -2.37
Aluminum Al3+ + 3e ¨> Al -1.66
Zinc Zn2+ + 2e ¨> Zn -0.76
Iron Fe2+ + 2e ¨> Fe -0.44
NickelN1 =2+
+ 2e ¨> Ni -0.25
Tin Sn2+ + 2e ¨> Sn -0.14
Lead Pb2+ + 2e ¨> Pb -0.13
Hydrogen 2H+ + 2e ¨> H2 -0.00
Copper Cu2+ + 2e ¨> Cu 0.34
Mercury Hg22+ + 2e ¨> 2Hg 0.79
Silver Ag+ + e ¨> Ag 0.80
Gold Au3+ + 3e ¨> Au 1.50
[0056] Thus, as will be apparent, when the metal substrate comprises
one of
the materials listed earlier, such as cold rolled steel, hot rolled steel,
steel coated with
zinc metal, zinc compounds, or zinc alloys, hot-dipped galvanized steel,
galvanealed
steel, steel plated with zinc alloy, aluminum alloys, aluminum plated steel,
aluminum
alloy plated steel, magnesium and magnesium alloys, suitable electropositive
metals
for deposition thereon in accordance with the present invention include, for
example,
nickel, copper, silver, and gold, as well mixtures thereof.
13
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[0057] In certain embodiments, the source of electropositive metal in
the
pretreatment composition is a water soluble metal salt. In certain embodiments
of the
present invention, the water soluble metal salt is a water soluble copper
compound.
Specific examples of water soluble copper compounds, which are suitable for
use in
the present invention include, but are not limited to, copper cyanide, copper
potassium
cyanide, copper sulfate, copper nitrate, copper pyrophosphate, copper
thiocyanate,
disodium copper ethylenediaminetetraacetate tetrahydrate, copper bromide,
copper
oxide, copper hydroxide, copper chloride, copper fluoride, copper gluconate,
copper
citrate, copper lauroyl sarcosinate, copper formate, copper acetate, copper
propionate,
copper butyrate, copper lactate, copper oxalate, copper phytate, copper
tartarate,
copper malate, copper succinate, copper malonate, copper maleate, copper
benzoate,
copper salicylate, copper aspartate, copper glutamate, copper fumarate, copper
glycerophosphate, sodium copper chlorophyllin, copper fluorosilicate, copper
fluoroborate and copper iodate, as well as copper salts of carboxylic acids in
the
homologous series formic acid to decanoic acid, copper salts of polybasic
acids in the
series oxalic acid to suberic acid, and copper salts of hydroxycarboxylic
acids,
including glycolic, lactic, tartaric, malic and citric acids.
[0058] When copper ions supplied from such a water-soluble copper
compound are precipitated as an impurity in the form of copper sulfate, copper
oxide,
etc., it may be preferable to add a complexing agent that suppresses the
precipitation
of copper ions, thus stabilizing them as a copper complex in the solution.
[0059] In certain embodiments, the copper compound is added as a copper
complex salt such as K3Cu(CN)4 or Cu-EDTA, which can be present stably in the
composition on its own, but it is also possible to form a copper complex that
can be
present stably in the composition by combining a complexing agent with a
compound
that is difficultly soluble on its own. Examples thereof include a copper
cyanide
complex formed by a combination of CuCN and KCN or a combination of CuSCN
and KSCN or KCN, and a Cu-EDTA complex formed by a combination of Cu504
and EDTA.2Na.
[0060] With regard to the complexing agent, a compound that can form a
complex with copper ions can be used; examples thereof include inorganic
compounds, such as cyanide compounds and thiocyanate compounds, and
14
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
polycarboxylic acids, and specific examples thereof include
ethylenediaminetetraacetic acid, salts of ethylenediaminetetraacetic acid,
such as
dihydrogen disodium ethylenediaminetetraacetate dihydrate, aminocarboxylic
acids,
such as nitrilotriacetic acid and iminodiacetic acid, oxycarboxylic acids,
such as citric
acid and tartaric acid, succinic acid, oxalic acid,
ethylenediaminetetramethylenephosphonic acid, and glycine.
[0061] In certain embodiments, the electropositive metal, such as
copper, is
included in the pretreatment compositions in an amount of at least 1 ppm, such
as at
least 5 ppm, or in some cases, at least 10 ppm of total metal (measured as
elemental
metal). In certain embodiments, the electropositive metal is included in such
pretreatment compositions in an amount of no more than 500 ppm, such as no
more
than 100 ppm, or in some cases, no more than 50 ppm of total metal (measured
as
elemental metal). The amount of electropositive metal in the pretreatment
composition can range between any combination of the recited values inclusive
of the
recited values.
[0062] The pretreatment composition may optionally contain other
materials,
such as nonionic surfactants and auxiliaries conventionally used in the art of
pretreatment. In an aqueous medium, water dispersible organic solvents, for
example,
alcohols with up to about 8 carbon atoms, such as methanol, isopropanol, and
the like,
may be present; or glycol ethers such as the monoalkyl ethers of ethylene
glycol,
diethylene glycol, or propylene glycol, and the like. When present, water
dispersible
organic solvents are typically used in amounts up to about ten percent by
volume,
based on the total volume of aqueous medium.
[0063] Other optional materials include surfactants that function as
defoamers
or substrate wetting agents, such as those materials and amounts described
earlier
with respect to the plating solution.
[0064] In certain embodiments, the pretreatment composition also
comprises a
reaction accelerator, such as nitrite ions, nitro-group containing compounds,
hydroxylamine sulfate, persulfate ions, sulfite ions, hyposulfite ions,
peroxides, iron
(III) ions, citric acid iron compounds, bromate ions, perchlorinate ions,
chlorate ions,
chlorite ions as well as ascorbic acid, citric acid, tartaric acid, malonic
acid, succinic
acid and salts thereof. Specific examples of suitable materials and their
amounts are
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
described in United States Patent Application Publication No. 2004/0163736 Al
at
[0032] to [0041], the cited portion of which being incorporated herein by
reference.
[0065] In certain embodiments, the pretreatment composition also
comprises a
filler, such as a siliceous filler. Non-limiting examples of suitable fillers
include
silica, mica, montmorillonite, kaolinite, asbestos, talc, diatomaceous earth,
vermiculite, natural and synthetic zeolites, cement, calcium silicate,
aluminum
silicate, sodium aluminum silicate, aluminum polysilicate, alumina silica
gels, and
glass particles. In addition to the siliceous fillers other finely divided
particulate
substantially water-insoluble fillers may also be employed. Examples of such
optional fillers include carbon black, charcoal, graphite, titanium oxide,
iron oxide,
copper oxide, zinc oxide, antimony oxide, zirconia, magnesia, alumina,
molybdenum
disulfide, zinc sulfide, barium sulfate, strontium sulfate, calcium carbonate,
and
magnesium carbonate.
[0066] As indicated, in certain embodiments, the pretreatment
composition is
substantially or, in some cases, completely free of chromate and/or heavy
metal
phosphate. As used herein, the term "substantially free" when used in
reference to the
absence of chromate and/or heavy metal phosphate, such as zinc phosphate, in
the
pretreatment composition means that these substances are not present in the
composition to such an extent that they cause a burden on the environment.
That is,
they are not substantially used and the formation of sludge, such as zinc
phosphate,
formed in the case of using a treating agent based on zinc phosphate, is
eliminated.
[0067] Moreover, in certain embodiments, the pretreatment composition
is
substantially free, or, in some cases, completely free of any organic
materials. As
used herein, the term "substantially free", when used with reference to the
absence of
organic materials in the composition, means that any organic materials are
present in
the composition, if at all, as an incidental impurity. In other words, the
presence of
any organic material does not affect the properties of the composition. As
used
herein, the term "completely free" means that there is no organic material in
the
composition at all.
[0068] In certain embodiments, the film coverage of the residue of the
pretreatment coating composition generally ranges from 1 to 1000 milligrams
per
square meter (mg/m2), such as 10 to 400 mg/m2. The thickness of the
pretreatment
16
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
coating can vary, but it is generally very thin, often having a thickness of
less than 1
micrometer, in some cases it is from 1 to 500 nanometers, and, in yet other
cases, it is
to 300 nanometers.
[0069] Following contact with the pretreatment solution according to
any of
the above embodiments, the substrate may be rinsed with water and dried.
Additional Coating Composition or Compositions After Pretreatment
[0070] In certain embodiments of the methods of the present invention,
after
the substrate is contacted with the acid and optional alkaline cleaner and
optionally
with a pretreatment composition, it is then contacted with a coating
composition
comprising a film-forming resin. Any suitable technique may be used to contact
the
substrate with such a coating composition, including, for example, brushing,
dipping,
flow coating, spraying and the like. In certain embodiments, however, as
described in
more detail below, such contacting comprises an electrocoating step wherein an
electrodepositable composition is deposited onto the metal substrate by
electrodeposition.
[0071] As used herein, the term "film-forming resin" refers to resins
that can
form a self-supporting continuous film on at least a horizontal surface of a
substrate
upon removal of any diluents or carriers present in the composition or upon
curing at
ambient or elevated temperature. Conventional film-forming resins that may be
used
include, without limitation, those typically used in automotive OEM coating
compositions, automotive refinish coating compositions, industrial coating
compositions, architectural coating compositions, coil coating compositions,
and
aerospace coating compositions, among others.
[0072] In certain embodiments, the coating composition comprises a
thermosetting film-forming resin. As used herein, the term "thermosetting"
refers to
resins that "set" 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 cross-linking reaction of the composition
constituents often
induced, for example, by heat or radiation. Curing or crosslinking reactions
also may
be carried out under ambient conditions. Once cured or crosslinked, a
thermosetting
resin will not melt upon the application of heat and is insoluble in solvents.
In other
embodiments, the coating composition comprises a thermoplastic film-forming
resin.
17
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
As used herein, the term "thermoplastic" refers to resins that comprise
polymeric
components that are not joined by covalent bonds and thereby can undergo
liquid
flow upon heating and are soluble in solvents.
[0073] As previously indicated, in certain embodiments, the substrate
is
contacted with a coating composition comprising a film-forming resin by an
electrocoating step wherein an electrodepositable composition is deposited
onto the
metal substrate by electrodeposition. In the process of electrodeposition, the
metal
substrate being treated, serving as an electrode, and an electrically
conductive counter
electrode are placed in contact with an ionic, electrodepositable composition.
Upon
passage of an electric current between the electrode and counter electrode
while they
are in contact with the electrodepositable composition, an adherent film of
the
electrodepositable composition will deposit in a substantially continuous
manner on
the metal substrate.
[0074] Electrodeposition is usually carried out at a constant voltage
in the
range of from 1 volt to several thousand volts, typically between 50 and 500
volts.
Current density is usually between 1.0 ampere and 15 amperes per square foot
(10.8
to 161.5 amperes per square meter) and tends to decrease quickly during the
electrodeposition process, indicating formation of a continuous self-
insulating film.
[0075] The electrodepositable composition utilized in certain
embodiments of
the present invention often comprises a resinous phase dispersed in an aqueous
medium wherein the resinous phase comprises: (a) an active hydrogen group-
containing ionic electrodepositable resin, and (b) a curing agent having
functional
groups reactive with the active hydrogen groups of (a).
[0076] In certain embodiments, the electrodepositable compositions
utilized in
certain embodiments of the present invention contain, as a main film-forming
polymer, an active hydrogen-containing ionic, often cationic,
electrodepositable resin.
A wide variety of electrodepositable film-forming resins are known and can be
used
in the present invention so long as the polymers are "water dispersible,"
i.e., adapted
to be solubilized, dispersed or emulsified in water. The water dispersible
polymer is
ionic in nature, that is, the polymer will contain anionic functional groups
to impart a
negative charge or, as is often preferred, cationic functional groups to
impart a
positive charge.
18
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[0077] Examples of film-forming resins suitable for use in anionic
electrodepositable compositions are base-solubilized, carboxylic acid
containing
polymers, such as the reaction product or adduct of a drying oil or semi-
drying fatty
acid ester with a dicarboxylic acid or anhydride; and the reaction product of
a fatty
acid ester, unsaturated acid or anhydride and any additional unsaturated
modifying
materials which are further reacted with polyol. Also suitable are the at
least partially
neutralized interpolymers of hydroxy-alkyl esters of unsaturated carboxylic
acids,
unsaturated carboxylic acid and at least one other ethylenically unsaturated
monomer.
Still another suitable electrodepositable film-forming resin comprises an
alkyd-
aminoplast vehicle, i.e., a vehicle containing an alkyd resin and an amine-
aldehyde
resin. Yet another anionic electrodepositable resin composition comprises
mixed
esters of a resinous polyol, such as is described in United States Patent No.
3,749,657
at col. 9, lines 1 to 75 and col. 10, lines 1 to 13, the cited portion of
which being
incorporated herein by reference. Other acid functional polymers can also be
used,
such as phosphatized polyepwdde or phosphatized acrylic polymers as are known
to
those skilled in the art.
[0078] As aforementioned, it is often desirable that the active
hydrogen-
containing ionic electrodepositable resin (a) is cationic and capable of
deposition on a
cathode. Examples of such cationic film-forming resins include amine salt
group-
containing resins, such as the acid-solubilized reaction products of
polyepoxides and
primary or secondary amines, such as those described in United States Patent
Nos.
3,663,389; 3,984,299; 3,947,338; and 3,947,339. Often, these amine salt group-
containing resins are used in combination with a blocked isocyanate curing
agent.
The isocyanate can be fully blocked, as described in United States Patent No.
3,984,299, or the isocyanate can be partially blocked and reacted with the
resin
backbone, such as is described in United States Patent No. 3,947,338. Also,
one-
component compositions as described in United States Patent No. 4,134,866 and
DE-
OS No. 2,707,405 can be used as the film-forming resin. Besides the epoxy-
amine
reaction products, film-forming resins can also be selected from cationic
acrylic
resins, such as those described in United States Patent Nos. 3,455,806 and
3,928,157.
[0079] Besides amine salt group-containing resins, quaternary ammonium
salt
group-containing resins can also be employed, such as those formed from
reacting an
organic polyepoxide with a tertiary amine salt as described in United States
Patent
19
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
Nos. 3,962,165; 3,975,346; and 4,001,101. Examples of other cationic resins
are
ternary sulfonium salt group-containing resins and quaternary phosphonium salt-
group containing resins, such as those described in United States Patent Nos.
3,793,278 and 3,984,922, respectively. Also, film-forming resins which cure
via
transesterification, such as described in European Application No. 12463 can
be used.
Further, cationic compositions prepared from Mannich bases, such as described
in
United States Patent No. 4,134,932, can be used.
[0080] In certain embodiments, the resins present in the
electrodepositable
composition are positively charged resins which contain primary and/or
secondary
amine groups, such as described in United States Patent Nos. 3,663,389;
3,947,339;
and 4,116,900. In United States Patent No. 3,947,339, a polyketimine
derivative of a
polyamine, such as diethylenetriamine or triethylenetetraamine, is reacted
with a
polyepwdde. When the reaction product is neutralized with acid and dispersed
in
water, free primary amine groups are generated. Also, equivalent products are
formed
when polyepwdde is reacted with excess polyamines, such as diethylenetriamine
and
triethylenetetraamine, and the excess polyamine vacuum stripped from the
reaction
mixture, as described in United States Patent Nos. 3,663,389 and 4,116,900.
[0081] In certain embodiments, the active hydrogen-containing ionic
electrodepositable resin is present in the electrodepositable composition in
an amount
of 1 to 60 percent by weight, such as 5 to 25 percent by weight, based on
total weight
of the electrodeposition bath.
[0082] As indicated, the resinous phase of the electrodepositable
composition
often further comprises a curing agent adapted to react with the active
hydrogen
groups of the ionic electrodepositable resin. For example, both blocked
organic
polyisocyanate and aminoplast curing agents are suitable for use in the
present
invention, although blocked isocyanates are often preferred for cathodic
electrodeposition.
[0083] Aminoplast resins, which are often the preferred curing agent
for
anionic electrodeposition, are the condensation products of amines or amides
with
aldehydes. Examples of suitable amine or amides are melamine, benzoguanamine,
urea and similar compounds. Generally, the aldehyde employed is formaldehyde,
although products can be made from other aldehydes, such as acetaldehyde and
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
furfural. The condensation products contain methylol groups or similar alkylol
groups depending on the particular aldehyde employed. Often, these methylol
groups
are etherified by reaction with an alcohol, such as a monohydric alcohol
containing
from 1 to 4 carbon atoms, such as methanol, ethanol, isopropanol, and n-
butanol.
Aminoplast resins are commercially available from American Cyanamid Co. under
the trademark CYMEL and from Monsanto Chemical Co. under the trademark
RESIMENE.
[0084] The aminoplast curing agents are often utilized in conjunction
with the
active hydrogen containing anionic electrodepositable resin in amounts ranging
from
percent to 60 percent by weight, such as from 20 percent to 40 percent by
weight,
the percentages based on the total weight of the resin solids in the
electrodepositable
composition.
[0085] As indicated, blocked organic polyisocyanates are often used as
the
curing agent in cathodic electrodeposition compositions. The polyisocyanates
can be
fully blocked as described in United States Patent No. 3,984,299 at col. 1,
lines 1 to
68, col. 2, and col. 3, lines 1 to 15, or partially blocked and reacted with
the polymer
backbone as described in United States Patent No. 3,947,338 at col. 2, lines
65 to 68,
col. 3, and col. 4 lines 1 to 30, the cited portions of which being
incorporated herein
by reference. By "blocked" is meant that the isocyanate groups have been
reacted
with a compound so that the resultant blocked isocyanate group is stable to
active
hydrogens at ambient temperature but reactive with active hydrogens in the
film
forming polymer at elevated temperatures usually between 90 C and 200 C.
[0086] Suitable polyisocyanates include aromatic and aliphatic
polyisocyanates, including cycloaliphatic polyisocyanates and representative
examples include diphenylmethane-4,4'-diisocyanate (MDI), 2,4- or 2,6-toluene
diisocyanate (TDI), including mixtures thereof, p-phenylene diisocyanate,
tetramethylene and hexamethylene diisocyanates, dicyclohexylmethane-4,4'-
diisocyanate, isophorone diisocyanate, mixtures of phenylmethane-4,4'-
diisocyanate
and polymethylene polyphenylisocyanate. Higher polyisocyanates, such as
triisocyanates can be used. An example would include triphenylmethane-4,4',4"-
triisocyanate. Isocyanate ( )-prepolymers with polyols such as neopentyl
glycol and
21
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
trimethylolpropane and with polymeric polyols such as polycaprolactone diols
and
triols (NCO/OH equivalent ratio greater than 1) can also be used.
[0087] The polyisocyanate curing agents are typically utilized in
conjunction
with the active hydrogen containing cationic electrodepositable resin in
amounts
ranging from 5 percent to 60 percent by weight, such as from 20 percent to 50
percent
by weight, the percentages based on the total weight of the resin solids of
the
electrodepositable composition.
[0088] In certain embodiments, the coating composition comprising a
film-
forming resin also comprises yttrium. In certain embodiments, yttrium is
present in
such compositions in an amount from 10 to 10,000 ppm, such as not more than
5,000
ppm, and, in some cases, not more than 1,000 ppm, of total yttrium (measured
as
elemental yttrium).
[0089] Both soluble and insoluble yttrium compounds may serve as the
source
of yttrium. Examples of yttrium sources suitable for use in lead-free
electrodepositable coating compositions are soluble organic and inorganic
yttrium
salts such as yttrium acetate, yttrium chloride, yttrium formate, yttrium
carbonate,
yttrium sulfamate, yttrium lactate and yttrium nitrate. When the yttrium is to
be
added to an electrocoat bath as an aqueous solution, yttrium nitrate, a
readily available
yttrium compound, is a preferred yttrium source. Other yttrium compounds
suitable
for use in electrodepositable compositions are organic and inorganic yttrium
compounds such as yttrium oxide, yttrium bromide, yttrium hydroxide, yttrium
molybdate, yttrium sulfate, yttrium silicate, and yttrium oxalate.
Organoyttrium
complexes and yttrium metal can also be used. When the yttrium is to be
incorporated into an electrocoat bath as a component in the pigment paste,
yttrium
oxide is often the preferred source of yttrium.
[0090] The electrodepositable compositions described herein are in the
form
of an aqueous dispersion. The term "dispersion" is believed to be a two-phase
transparent, translucent or opaque resinous system in which the resin is in
the
dispersed phase and the water is in the continuous phase. The average particle
size of
the resinous phase is generally less than 1.0 and usually less than 0.5
microns, often
less than 0.15 micron.
22
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[0091] The concentration of the resinous phase in the aqueous medium is
often at least 1 percent by weight, such as from 2 to 60 percent by weight,
based on
total weight of the aqueous dispersion. When such compositions are in the form
of
resin concentrates, they generally have a resin solids content of 20 to 60
percent by
weight based on weight of the aqueous dispersion.
[0092] The electrodepositable compositions described herein are often
supplied as two components: (1) a clear resin feed, which includes generally
the
active hydrogen-containing ionic electrodepositable resin, i.e., the main film-
forming
polymer, the curing agent, and any additional water-dispersible, non-pigmented
components; and (2) a pigment paste, which generally includes one or more
colorants
(described below), a water-dispersible grind resin which can be the same or
different
from the main-film forming polymer, and, optionally, additives such as wetting
or
dispersing aids. Electrodeposition bath components (1) and (2) are dispersed
in an
aqueous medium which comprises water and, usually, coalescing solvents.
[0093] As aforementioned, besides water, the aqueous medium may contain
a
coalescing solvent. Useful coalescing solvents are often hydrocarbons,
alcohols,
esters, ethers and ketones. The preferred coalescing solvents are often
alcohols,
polyols and ketones. Specific coalescing solvents include isopropanol,
butanol, 2-
ethylhexanol, isophorone, 2-methoxypentanone, ethylene and propylene glycol
and
the monoethyl monobutyl and monohexyl ethers of ethylene glycol. The amount of
coalescing solvent is generally between 0.01 and 25 percent, such as from 0.05
to 5
percent by weight based on total weight of the aqueous medium.
[0094] In addition, a colorant and, if desired, various additives such
as
surfactants, wetting agents or catalyst can be included in the coating
composition
comprising a film-forming resin. As used herein, the term "colorant" means any
substance that imparts color and/or other opacity and/or other visual effect
to the
composition. The colorant can be added to the composition in any suitable
form, such
as discrete particles, dispersions, solutions and/or flakes. A single colorant
or a
mixture of two or more colorants can be used.
[0095] Example colorants include pigments, dyes and tints, such as
those used
in the paint industry and/or listed in the Dry Color Manufacturers Association
(DCMA), as well as special effect compositions. A colorant may include, for
23
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
example, a finely divided solid powder that is insoluble but wettable under
the
conditions of use. A colorant can be organic or inorganic and can be
agglomerated or
non-agglomerated. Colorants can be incorporated by use of a grind vehicle,
such as
an acrylic grind vehicle, the use of which will be familiar to one skilled in
the art.
[0096] Example pigments and/or pigment compositions include, but are
not
limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol
AS,
salt type (lakes), benzimidazolone, condensation, metal complex,
isoindolinone,
isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone,
diketopyrrolo prole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine,
flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium,
quinophthalone
pigments, diketo pyrrolo pyrrole red ("DPPBO red"), titanium dioxide, carbon
black
and mixtures thereof. The terms "pigment" and "colored filler" can be used
interchangeably.
[0097] Example dyes include, but are not limited to, those that are
solvent
and/or aqueous based such as phthalo green or blue, iron oxide, bismuth
vanadate,
anthraquinone, perylene, aluminum and quinacridone.
[0098] Example tints include, but are not limited to, pigments
dispersed in
water-based or water miscible carriers such as AQUA-CHEM 896 commercially
available from Degussa, Inc., CHARISMA COLORANTS and MAXITONER
INDUSTRIAL COLORANTS commercially available from Accurate Dispersions
division of Eastman Chemical, Inc.
[0099] As noted above, the colorant can be in the form of a dispersion
including, but not limited to, a nanoparticle dispersion. Nanoparticle
dispersions can
include one or more highly dispersed nanoparticle colorants and/or colorant
particles
that produce a desired visible color and/or opacity and/or visual effect.
Nanoparticle
dispersions can include colorants such as pigments or dyes having a particle
size of
less than 150 nm, such as less than 70 nm, or less than 30 nm. Nanoparticles
can be
produced by milling stock organic or inorganic pigments with grinding media
having
a particle size of less than 0.5 mm. Example nanoparticle dispersions and
methods for
making them are identified in U.S. Patent No. 6,875,800 B2, which is
incorporated
herein by reference. Nanoparticle dispersions can also be produced by
crystallization,
precipitation, gas phase condensation, and chemical attrition (i.e., partial
dissolution).
24
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
In order to minimize re-agglomeration of nanoparticles within the coating, a
dispersion of resin-coated nanoparticles can be used. As used herein, a
"dispersion of
resin-coated nanoparticles" refers to a continuous phase in which is dispersed
discreet
"composite microparticles" that comprise a nanoparticle and a resin coating on
the
nanoparticle. Example dispersions of resin-coated nanoparticles and methods
for
making them are identified in United States Patent Application Publication
2005-
0287348 Al, filed June 24, 2004, U.S. Provisional Application No. 60/482,167
filed
June 24, 2003, and United States Patent Application Serial No. 11/337,062,
filed
January 20, 2006, which is also incorporated herein by reference.
[00100] Example special effect compositions that may be used include
pigments and/or compositions that produce one or more appearance effects such
as
reflectance, pearlescence, metallic sheen, phosphorescence, fluorescence,
photochromism, photosensitivity, thermochromism, goniochromism and/or color-
change. Additional special effect compositions can provide other perceptible
properties, such as opacity or texture. In certain embodiments, special effect
compositions can produce a color shift, such that the color of the coating
changes
when the coating is viewed at different angles. Example color effect
compositions are
identified in U.S. Patent No. 6,894,086, incorporated herein by reference.
Additional
color effect compositions can include transparent coated mica and/or synthetic
mica,
coated silica, coated alumina, a transparent liquid crystal pigment, a liquid
crystal
coating, and/or any composition wherein interference results from a refractive
index
differential within the material and not because of the refractive index
differential
between the surface of the material and the air.
[00101] In certain embodiments, a photosensitive composition and/or
photochromic composition, which reversibly alters its color when exposed to
one or
more light sources, can be used. Photochromic and/or photosensitive
compositions
can be activated by exposure to radiation of a specified wavelength. When the
composition becomes excited, the molecular structure is changed and the
altered
structure exhibits a new color that is different from the original color of
the
composition. When the exposure to radiation is removed, the photochromic
and/or
photosensitive composition can return to a state of rest, in which the
original color of
the composition returns. In certain embodiments, the photochromic and/or
photosensitive composition can be colorless in a non-excited state and exhibit
a color
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
in an excited state. Full color-change can appear within milliseconds to
several
minutes, such as from 20 seconds to 60 seconds. Example photochromic and/or
photosensitive compositions include photochromic dyes.
[00102] In certain embodiments, the photosensitive composition and/or
photochromic composition can be associated with and/or at least partially
bound to,
such as by covalent bonding, a polymer and/or polymeric materials of a
polymerizable component. In contrast to some coatings in which the
photosensitive
composition may migrate out of the coating and crystallize into the substrate,
the
photosensitive composition and/or photochromic composition associated with
and/or
at least partially bound to a polymer and/or polymerizable component in
accordance
with certain embodiments of the present invention, have minimal migration out
of the
coating. Example photosensitive compositions and/or photochromic compositions
and methods for making them are identified in U.S. Application Serial No.
10/892,919 filed July 16, 2004, incorporated herein by reference.
[00103] In general, the colorant can be present in the coating
composition in
any amount sufficient to impart the desired visual and/or color effect. The
colorant
may comprise from 1 to 65 weight percent, such as from 3 to 40 weight percent
or 5
to 35 weight percent, with weight percent based on the total weight of the
composition.
[00104] After deposition, the coating is often heated to cure the
deposited
composition. The heating or curing operation is often carried out at a
temperature in
the range of from 120 to 250 C, such as from 120 to 190 C, for a period of
time
ranging from 10 to 60 minutes. In certain embodiments, the thickness of the
resultant
film is from 10 to 50 microns.
Electrodepositable Coating Composition Without Pretreatment
[00105] In certain embodiments of the methods of the present invention,
after
the substrate is contacted with the acid and without the subsequent contact
with a
pretreatment composition, it may then be contacted with a electrodepositable
coating
composition comprising (i) a film-forming compound and (ii) a source of
yttrium.
[00106] As defined herein, the term "without the subsequent contact with
a
pretreatment composition" means that the substrate has not been contacted with
a
composition that, upon contact with the substrate, reacts with and chemically
alters
26
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
the substrate surface and binds to it to form a protective layer. This
specifically
includes any of the pretreatment compositions comprising a group IIIB and/or
group
IVB metal as described above, and further includes other known pretreatment
compositions such as, for example, zinc or iron phosphate-type conversion or
pretreatment coatings.
[00107] In certain embodiments, the electrodepositable coating
composition
may be formed in accordance with U.S. Patent Application No. 12/693,626, which
is
herein incorporated by reference, and may also include (iii) a silane that
does not
contain an ethylenically unsaturated double bond. In certain embodiments, the
coating composition may be formed in accordance with U.S. Patent Application
No.
12/693,626 and may further also include (iii) an amino silane, which could or
could
not contain an ethylenically unsaturated double bond.
[00108] In some embodiments, when the film-forming polymer comprises a
reactive functional group, the coating composition further comprises (iv) a
curing
agent that is reactive with a reactive functional group of the film-forming
polymer.
[00109] A wide variety of film-forming polymers, which are known in the
art,
can be used as component (i) so long as the polymers are "water dispersible."
As
used herein, "water dispersible" means that a material is adapted to be
solubilized,
dispersed, and/or emulsified in water. The film-forming polymers used in the
present
invention are ionic in nature. Accordingly, in some embodiments, the film-
forming
polymer is cationic. In other words, the film-forming polymer comprises
cationic salt
groups, generally prepared by neutralizing a functional group on the film-
forming
polymer with an acid, which enables the film-forming polymer to be
electrodeposited
onto a cathode.
[00110] Examples of film-forming polymers suitable for use in cationic
electrocoating coating compositions include, without limitation, cationic
polymers
derived from a polyepoxide, an acrylic, a polyurethane, and/or polyester. In
certain
embodiments, the film-forming polymer comprises reactive functional groups. As
used herein, the phrase "reactive functional group" means hydroxyl, carboxyl,
carbamate, epoxy, isocyanate, aceto acetate, amine-salt, mercaptan, or
combinations
thereof. It should be noted that in some embodiments, the film-forming polymer
is a
copolymer of the polymers listed in the preceding sentence. In some
embodiments,
27
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
the cationic polymer can be derived by reacting a polyepwdde containing
polymer
with a cationic salt group former. As used herein, "cationic salt group
former" means
a material that is reactive with epoxy groups and which can be acidified
before,
during, or after reaction with the epoxy groups to form cationic salt groups.
Suitable
materials that can be used as the cationic salt group former include amines
such as
primary or secondary amines, which can be acidified after reaction with the
epoxy
groups to form amine salt groups, or tertiary amines, which can be acidified
prior to
reaction with the epoxy groups and which after reaction with the epoxy groups
form
quaternary ammonium salt groups. Examples of other cationic salt group formers
are
sulfides which can be mixed with acid prior to reaction with the epoxy groups
and
form ternary sulfonium salt groups upon subsequent reaction with the epoxy
groups.
[00111] In certain embodiments, the film-forming polymer (i) that is
used in
the present invention comprises the reaction product of an epoxy functional
compound (e.g., EPON 880) and a phenolic hydroxyl group-containing material
such
as bisphenol A, which is a polyhydric phenol. In some embodiments, the film-
forming polymer (i) described in the preceding sentence can be reacted with an
amine,
such as aminopropyldiethanolamine (APDEA) and dimethylaminopropylamine
(DMAPA), in order to make the film-forming polymer water dispersible. In
certain
embodiments, ketimine can be reacted with the backbone of the film-forming
polymer
thereby forming ketimine arms that extend pendant to the backbone. When the
polymer is dispersed in a water/acid mixture, the ketimine arms will hydrolyze
and
form primary amines. Accordingly, in some embodiments, the electrodepositable
coating compositions that are disclosed in U.S. Patent Nos. 5,633,297,
5,820,987,
and/or 5,936,012 can be used with the present invention.
[00112] Various corrosion inhibitors may be used as component (a) in the
present invention. Suitable corrosion inhibitors include, without limitation,
rare earth
metals, bismuth, copper, zinc, silver, zirconium, or combinations thereof. In
certain
embodiments, an yttrium compound or a cerium compound, or a mixture of an
yttrium and cerium compound, may be used as the corrosion inhibitor. Yttrium
and
cerium compounds, as defined herein, include their respective salts and
hereinafter
may be referred to simply as yttrium compounds or cerium compounds. They may
also be included in the list of potential compounds comprising a source or
yttrium or a
source of cerium.
28
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[00113] Various yttrium compounds may be used as component (ii) in the
present invention. For example, the yttrium compounds may include, without
limitation, yttrium formate, yttrium acetate, yttrium lactate, yttrium
sulfamate, yttrium
methane sulfonate, yttrium nitrate, or combinations thereof. In some
embodiments,
yttrium comprises < 5 weight % of the total resin solids of the
electrodepositable
coating composition. In other embodiments, yttrium comprises > 0.15 weight %
of
the total resin solids of the electrodepositable coating composition. In
certain
embodiments, the amount of yttrium can range between any combination of
values,
which were recited in the preceding sentences, inclusive of the recited
values. For
example, in certain embodiments, the amount of yttrium can range from 0.20
weight
% to 2 weight % of the total resin solids of the electrodepositable coating
composition.
[00114] Various cerium compounds may be used as component (ii) in the
present invention. For example, the cerium compounds may include ammonium
cerium nitrate, ammonium cerium sulfate, cerium acetate, cerium bromide,
cerium
carbonate, cerium chloride, cerium fluoride, cerium iodide, cerium nitrate,
cerium
molybdate, cerium oxide, cerium oxalate, cerium phosphate, and cerium sulfate.
In
some embodiments, cerium comprises < 5 weight % of the total resin solids of
the
electrodepositable coating composition. In other embodiments, cerium comprises
>
0.15 weight % of the total resin solids of the electrodepositable coating
composition.
In certain embodiments, the amount of cerium can range between any combination
of
values, which were recited in the preceding sentences, inclusive of the
recited values.
For example, in certain embodiments, the amount of cerium can range from 0.20
weight % to 2 weight % of the total resin solids of the electrodepositable
coating
composition.
[00115] Various combinations of yttrium compounds and cerium compounds,
as described in the previous paragraphs, may be used as component (ii) in the
present
invention. In some embodiments, the combination of yttrium and cerium
comprises <
weight % of the total resin solids of the electrodepositable coating
composition. In
other embodiments, the combination of yttrium and cerium comprises > 0.15
weight
% of the total resin solids of the electrodepositable coating composition. In
certain
embodiments, the amount of yttrium and cerium can range between any
combination
of values, which were recited in the preceding sentences, inclusive of the
recited
29
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
values. For example, in certain embodiments, the amount of yttrium and cerium
can
range from 0.20 weight % to 2 weight % of the total resin solids of the
electrodepositable coating composition.
[00116] If (i) the film-forming polymer comprises reactive functional
groups,
such as those described above, then the electrodepositable coating composition
may
further comprise (iv) a crosslinking agent ("curing agent") that is reactive
with the
reactive functional groups of the polymer. Suitable crosslinking agents
include,
without limitation, aminoplasts, polyisocyanates (including blocked
isocyanates),
polyepwddes, beta-hydroxyalkylamides, polyacids, anhydrides, organometallic
acid-
functional materials, polyamines, polyamides, cyclic carbonates, siloxanes, or
combinations thereof. In some embodiments, the curing agent can comprise from
30
weight % to 40 weight % of the total resin solids of the coating composition.
[00117] In certain embodiments, the electrodepositable coating
composition
may further comprise (v) a curing catalyst, which may be used to catalyze the
reaction
between the crosslinking agent and the reactive functional groups of the film-
forming
polymer. Suitable curing catalysts that may be used as component (v) include,
without limitation, organotin compounds (e.g., dibutyltin oxide, dioctyltin
oxide) and
salts thereof (e.g., dibutyltin diacetate); other metal oxides (e.g., oxides
of cerium,
zirconium and/or bismuth) and salts thereof (e.g., bismuth sulfamate and/or
bismuth
lactate), bicyclic guanidine (as disclosed in U.S. Patent Application No.
11/835,600),
or combinations thereof.
[00118] The electrodepositable coating composition disclosed herein is
typically supplied as two components: (1) a main vehicle ("clear resin feed")
and (2) a
grind vehicle ("pigment paste"). In general, (1) the main vehicle comprises
(a) a film-
forming polymer ("an active hydrogen-containing ionic salt group-containing
resin"),
(b) a crosslinking agent, and (c) any additional water-dispersible, non-
pigmented
components (e.g., catalysts, hindered amine light stabilizers). In general,
(2) the grind
vehicle comprises (d) one or more pigments (e.g., titanium dioxide, carbon
black), (e)
a water-dispersible grind resin, which can be the same or different from the
film-
forming polymer, and, optionally, (f) additives such as catalysts,
antioxidants,
biocides, defoamers, surfactants, wetting agents, dispersing aids, clays,
hindered
amine light stabilizers, UV light absorbers and stabilizers, or combinations
thereof.
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
An electrodeposition bath, which contains the electrodepositable coating
composition
of the present invention, can be prepared by dispersing components (1) and (2)
in an
aqueous medium which comprises water and, usually, coalescing solvents. The
(ii)
yttrium and/or the (iii) silane, which are used in the electrodepositable
coating
composition of the present invention, may be incorporated into the main
vehicle, the
grind vehicle, or post-added to a bath that is prepared with components (1)
and (2).
Alternatively, components (1) and (2) may also be provided as a single
component.
[00119] The electrodepositable coating composition described herein may
be
applied alone or as part of a coating system that can be deposited onto a
number of
different substrates. The coating system typically comprises a number of
coating
layers. A coating layer is typically formed when a coating composition that is
deposited onto the substrate is substantially cured by methods known in the
art (e.g.,
by thermal heating).
[00120] After the electrodepositable coating composition is cured, a
primer-
surfacer coating composition is applied onto at least a portion of the
electrodepositable coating composition. The primer-surfacer coating
composition is
typically applied to the electrodepositable coating layer and cured prior to a
subsequent coating composition being applied over the primer-surfacer coating
composition.
[00121] The primer-surfacer layer that results from the primer-surfacer
coating
composition serves to enhance chip resistance of the coating system as well as
aid in
the appearance of subsequently applied layers (e.g., color imparting coating
composition and/or substantially clear coating composition). As used herein,
"primer-
surfacer" refers to a primer composition for use under a subsequently applied
coating
composition, and includes such materials as thermoplastic and/or crosslinking
(e.g.,
thermosetting) film-forming resins generally known in the art of organic
coating
compositions. Suitable primers and primer-surfacer coating compositions
include
spray applied primers, as are known to those skilled in the art. Examples of
suitable
primers include several available from PPG Industries, Inc., Pittsburgh, Pa.,
as DPX-
1791, DPX-1804, DSPX-1537, GPXH-5379, OPP-2645, PCV-70118, and 1177-
225A. Another suitable primer-surfacer coating composition that can be
utilized in
31
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
the present invention is the primer-surfacer described in U.S. Patent
Application No.
11/773,482, which is incorporated in its entirety herein by reference.
[00122] It should be noted that in some embodiments, the primer-surfacer
coating composition is not used in the coating system. Therefore, a color
imparting
basecoat coating composition can be applied directly onto the cured
electrodepositable coating composition.
[00123] In some embodiments, a color imparting coating composition
(hereinafter, "basecoat") is deposited onto at least a portion of the primer
surfacer
coating layer (if present). Any basecoat coating composition known in the art
may be
used in the present invention. It should be noted that these basecoat coating
compositions typically comprise a colorant.
[00124] In certain embodiments, a substantially clear coating
composition
(hereinafter, "clearcoat") is deposited onto at least a portion of the
basecoat coating
layer. As used herein, a "substantially clear" coating layer is substantially
transparent
and not opaque. In certain embodiments, the substantially clear coating
composition
can comprise a colorant but not in an amount such as to render the clear
coating
composition opaque (not substantially transparent) after it has been cured.
Any
clearcoat coating composition known in the art may be used in the present
invention.
For example, the clearcoat coating composition that is described in U.S.
Patent Nos.
5,989,642, 6,245,855, 6,387,519, and 7,005,472, which are incorporated in
their
entirety herein by reference, can be used in the coating system. In certain
embodiments, the substantially clear coating composition can also comprise a
particle,
such as a silica particle, that is dispersed in the clearcoat coating
composition (such as
at the surface of the clearcoat coating composition after curing).
[00125] One or more of the coating compositions described herein can
comprise colorants and/or other optional materials, which are known in the art
of
formulated surface coatings. As used herein, the term "colorant" means any
substance that imparts color and/or other opacity and/or other visual effect
to the
composition. The colorant can be added to the coating in any suitable form,
such as
discrete particles, dispersions, solutions and/or flakes (e.g., aluminum
flakes). A
single colorant or a mixture of two or more colorants can be used in the
coating
composition described herein.
32
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[00126] Example colorants include pigments, dyes and tints, such as
those used
in the paint industry and/or listed in the Dry Color Manufacturers Association
(DCMA), as well as special effect compositions. A colorant may include, for
example, a finely divided solid powder that is insoluble but wettable under
the
conditions of use. A colorant can be organic or inorganic and can be
agglomerated or
non-agglomerated. Colorants can be incorporated into the coatings by use of a
grind
vehicle, such as an acrylic grind vehicle, the use of which will be familiar
to one
skilled in the art.
[00127] Example pigments and/or pigment compositions include, but are
not
limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol
AS,
salt type (lakes), benzimidazolone, condensation, metal complex,
isoindolinone,
isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone,
diketopyrrolo prole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine,
flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium,
quinophthalone
pigments, diketo pyrrolo pyrrole red ("DPPBO red"), titanium dioxide, carbon
black
and mixtures thereof. The terms "pigment" and "colored filler" can be used
interchangeably.
[00128] Example dyes include, but are not limited to, those that are
solvent
and/or aqueous based such as phthalo green or blue, iron oxide, bismuth
vanadate,
anthraquinone, perylene, aluminum and quinacridone.
[00129] Example tints include, but are not limited to, pigments
dispersed in
water-based or water miscible carriers such as AQUA-CHEM 896 commercially
available from Degussa, Inc., CHARISMA COLORANTS and MAXITONER
INDUSTRIAL COLORANTS commercially available from Accurate Dispersions
division of Eastman Chemical, Inc.
[00130] As noted above, the colorant can be in the form of a dispersion
including, but not limited to, a nanoparticle dispersion. Nanoparticle
dispersions can
include one or more highly dispersed nanoparticle colorants and/or colorant
particles
that produce a desired visible color and/or opacity and/or visual effect.
Nanoparticle
dispersions can include colorants such as pigments or dyes having a particle
size of
less than 150 nm, such as less than 70 nm, or less than 30 nm. Nanoparticles
can be
produced by milling stock organic or inorganic pigments with grinding media
having
33
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
a particle size of less than 0.5 mm. Example nanoparticle dispersions and
methods for
making them are identified in U.S. Patent No. 6,875,800, which is incorporated
herein
by reference. Nanoparticle dispersions can also be produced by
crystallization,
precipitation, gas phase condensation, and chemical attrition (i.e., partial
dissolution).
In order to minimize re-agglomeration of nanoparticles within the coating, a
dispersion of resin-coated nanoparticles can be used. As used herein, a
"dispersion of
resin-coated nanoparticles" refers to a continuous phase in which discreet
"composite
microparticles", which comprise a nanoparticle and a resin coating on the
nanoparticle, is dispersed. Example dispersions of resin-coated nanoparticles
and
methods for making them are identified in U.S. Patent Publication No.
2005/0287348,
filed June 24, 2004, U.S. Provisional Application No. 60/482,167 filed June
24, 2003,
and U.S. Patent Application No. 11/337,062, filed January 20, 2006, which are
also
incorporated herein by reference.
[00131] Example special effect compositions that may be used include
pigments and/or compositions that produce one or more appearance effects such
as
reflectance, pearlescence, metallic sheen, phosphorescence, fluorescence,
photochromism, photosensitivity, thermochromism, goniochromism and/or color-
change. Additional special effect compositions can provide other perceptible
properties, such as opacity or texture. In a non-limiting embodiment, special
effect
compositions can produce a color shift, such that the color of the coating
changes
when the coating is viewed at different angles. Example color effect
compositions are
identified in U.S. Patent No. 6,894,086, incorporated herein by reference.
Additional
color effect compositions can include transparent coated mica and/or synthetic
mica,
coated silica, coated alumina, a transparent liquid crystal pigment, a liquid
crystal
coating, and/or any composition wherein interference results from a refractive
index
differential within the material and not because of the refractive index
differential
between the surface of the material and the air.
[00132] In certain non-limiting embodiments, a photosensitive
composition
and/or photochromic composition, which reversibly alters its color when
exposed to
one or more light sources, can be used in the coating composition described
herein.
Photochromic and/or photosensitive compositions can be activated by exposure
to
radiation of a specified wavelength. When the composition becomes excited, the
molecular structure is changed and the altered structure exhibits a new color
that is
34
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
different from the original color of the composition. When the exposure to
radiation
is removed, the photochromic and/or photosensitive composition can return to a
state
of rest, in which the original color of the composition returns. In one non-
limiting
embodiment, the photochromic and/or photosensitive composition can be
colorless in
a non-excited state and exhibit a color in an excited state. Full color-change
can
appear within milliseconds to several minutes, such as from 20 seconds to 60
seconds.
Example photochromic and/or photosensitive compositions include photochromic
dyes.
[00133] In a non-limiting embodiment, the photosensitive composition
and/or
photochromic composition can be associated with and/or at least partially
bound to,
such as by covalent bonding, a polymer and/or polymeric materials of a
polymerizable component. In contrast to some coatings in which the
photosensitive
composition may migrate out of the coating and crystallize into the substrate,
the
photosensitive composition and/or photochromic composition associated with
and/or
at least partially bound to a polymer and/or polymerizable component in
accordance
with a non-limiting embodiment of the present invention, have minimal
migration out
of the coating. Example photosensitive compositions and/or photochromic
compositions and methods for making them are identified in U.S. Patent
Application
No. 10/892,919, filed July 16, 2004.
[00134] In general, the colorant can be present in any amount sufficient
to
impart the desired visual and/or color effect. The colorant may comprise from
1 to 65
weight percent of the present compositions, such as from 3 to 40 weight
percent or 5
to 35 weight percent, with weight percent based on the total weight of the
compositions.
[00135] The coating compositions can comprise other optional materials
well
known in the art of formulated surface coatings, such as plasticizers, anti-
oxidants,
hindered amine light stabilizers, UV light absorbers and stabilizers,
surfactants, flow
control agents, thixotropic agents such as bentonite clay, pigments, fillers,
organic
cosolvents, catalysts, including phosphonic acids and other customary
auxiliaries.
[00136] In addition to the materials described above, the coating
composition
can also comprise an organic solvent. Suitable organic solvents that can be
used in
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
the coating composition include any of those listed in the preceding
paragraphs as
well as butyl acetate, xylene, methyl ethyl ketone, or combinations thereof.
[00137] It will be further appreciated that one or more of the coating
compositions that form the various coating layers described herein can be
either "one
component" ("1K"), "two component" ("2K"), or even multi-component
compositions. A 1K composition will be understood as referring to a
composition
wherein all of the coating components are maintained in the same container
after
manufacture, during storage, etc. A 2K composition or multi-component
composition
will be understood as referring to a composition wherein various components
are
maintained separately until just prior to application. A 1K or 2K coating
composition
can be applied to a substrate and cured by any conventional means, such as by
heating, forced air, and the like.
[00138] The coating compositions that form the various coating layers
described herein can be deposited or applied onto the substrate using any
technique
that is known in the art. For example, the coating compositions can be applied
to the
substrate by any of a variety of methods including, without limitation,
spraying,
brushing, dipping, and/or roll coating, among other methods. When a plurality
of
coating compositions are applied onto a substrate, it should be noted that one
coating
composition may be applied onto at least a portion of an underlying coating
composition either after the underlying coating composition has been cured or
prior to
the underlying coating composition being cured. If the coating composition is
applied
onto an underlying coating composition that has not been cured, both coating
compositions may be cured simultaneously.
[00139] The coating compositions may be cured using any technique known
in
the art such as, without limitation, thermal energy, infrared, ionizing or
actinic
radiation, or by any combination thereof. In certain embodiments, the curing
operation can be carried out at temperatures > 10 C. In other embodiments, the
curing operation can be carried out at temperature < 246 C. In certain
embodiments,
the curing operation can carried out at temperatures ranging between any
combination
of values, which were recited in the preceding sentences, inclusive of the
recited
values. For example, the curing operation can be carried out at temperatures
ranging
36
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
from 120 C - 150 C. It should be noted, however, that lower or higher
temperatures
may be used as necessary to activate the curing mechanisms.
[00140] In certain embodiments, one or more of the coating compositions
described herein is a low temperature, moisture curable coating compositions.
As
used herein, the term "low temperature, moisture curable" refers to coating
compositions that, following application to a substrate, are capable of curing
in the
presence of ambient air, the air having a relative humidity of 10 % to 100 %,
such as
25 % to 80 %, and a temperature in the range of -10 C to 120 C, such as 5 C to
80 C,
in some cases 10 C to 60 C and, in yet other cases, 15 C to 40 C.
[00141] The dry film thickness of the coating layers described herein
can range
from 0.1 micron to 500 microns. In other embodiments, the dry film thickness
can be
< 125 microns, such as < 80 microns. For example, the dry film thickness can
range
from 15 microns to 60 microns.
[00142] While specific embodiments of the invention have been described
in
detail, it will be appreciated by those skilled in the art that various
modifications and
alternatives to those details could be developed in light of the overall
teachings of the
disclosure. Accordingly, the particular arrangements disclosed are meant to be
illustrative only and not limiting as to the scope of the invention which is
to be given
the full breadth of the claims appended and any and all equivalents thereof.
[00143] It will be appreciated by those skilled in the art that changes
could be
made to the embodiments described above without departing from the broad
inventive
concept thereof. It is understood, therefore, that this invention is not
limited to the
particular embodiments disclosed, but it is intended to cover modifications
which are
within the spirit and scope of the invention, as defined by the appended
claims.
EXAMPLES
[00144] Coating compositions, panels, and testing methods used in these
Examples were prepared and described as follows:
[00145] Alkaline Cleaner 1: Chemkleen 2010LP/181ALP, a commercial
alkaline cleaner available from PPG Industries, Inc.
37
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
[00146] Alkaline Cleaner 1A: Experimental alkaline cleaner with a
composition similar to Chemkleen 166HP, commercially available from PPG
Industries, Inc.
[00147] Acid Cleaner 2 ¨ A citric acid cleaner prepared as follows.
First, 468.4
g of anhydrous citric acid was dissolved in 18,000 g of water. Next, 103.4 g
of a
commercial surfactant package, Chemkleen 171-12, was added to the mixture.
Finally, potassium hydroxide was added to the mixture to adjust the pH of the
resultant mixture to 4.5.
[00148] Pretreatment Composition 1: CHEMFOS 700, immersion applied
tricationic Zn phosphate (a commercial pretreatment product available from PPG
Industries, Inc.).
[00149] Electrodepositable Paint Composition 1: Enviro-prime 7000P, a
cationic electrocoat commercially available from PPG Industries, Inc.
[00150] Electrodepositable Paint Composition 2: Yttrium-containing
Electrodeposiable Paint prepared in accordance with Paint 4 in Table 1
(paragraph
[0074]) of U.S. Patent Application No. 12/693,626.)
[00151] Phosphated panels were purchased from ACT.
[00152] Test 1: 40 cycles of GM9540P (Cycle B)
[00153] Test 2: 24 hours in a cathodic disbondment test. The test
involves a
scribed panel submerged into a sodium sulfate solution where a current of 10
mA is
passed through the panel. After 24 hours, tape is used to remove delaminated
paint
and the width of the delaminated area is measured.
Comparative Results
Experiment 1 ¨ Comparison of corrosion resistance on cleaned panels
subsequently coated with Electrodepositable Coating Composition 1 ¨
Alkaline Cleaner 1 vs. Acid Cleaner 2
[00154] Cold-rolled steel panels (ACT Panels) were cleaned using Cleaner
1 or
Cleaner 2, rinsed with deionized water, and dried using forced hot air. The
panels
were electrocoated in Electrodepositable Paint Composition 1 and cured for 25
minutes @ 177 C in an electric oven. The dry film thickness was 0.0005-0.0010
inches. Samples were then scribed vertically and placed in Test 1. Average
scribe
creep results are shown in Table 1 below.
38
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
Table 1
Cleaner Avg Scribe Creep (mm)
#1 ¨ 2' Spray 18.7
#2 ¨ 4' Spray 7.6
Experiment 2 ¨ Comparison of corrosion resistance on cleaned panels
subsequently coated with Electrodepostable Coating Composition 2 ¨
Alkaline Cleaner 1A vs. Acid Cleaner 2
[00155] Cold-rolled steel panels (ACT Panels) were cleaned using
Alkaline
Cleaner lA or Acid Cleaner 2, rinsed with deionized water, and dried using
forced hot
air. The panels were electrocoated in Electrodepositable Paint Composition 2
and
cured for 25 minutes @ 177 C in an electric oven. The dry film thickness was
0.0005-0.0010 inches. Samples were then scribed vertically and placed in Test
1.
Average scribe creep results are shown in Table 2 below:
Table 2
Cleaner Avg Scribe Creep (mm)
#1A ¨ 2' Immersion 9.5
#2 ¨ 4' Spray 3.3
Experiment 3- Comparison of yttrium deposition on cleaned panels - Alkaline
Cleaner 1A alone vs. Alkaline Cleaner 1A followed by Acid Cleaner 2
[00156] Cold-rolled steel panels (ACT Panels) were cleaned using
Alkaline
Cleaner lA alone, or Alkaline Cleaner lA followed by Acid Cleaner 2, and
rinsed
with deionized water. The panels were then placed in a solution of yttrium
sulfamate
(800 ppm yttrium) buffered to a pH of 5.5. 80 mA of current was passed through
the
solution for 2 minutes at room temperature. Panels were then rinsed with
deionized
water and dried using forced air. After drying, the amount of yttrium
deposited on the
panels was measured by wave-dispersive X-ray fluorescence. The results are
shown
in Table 3 below:
39
CA 02849983 2014-03-25
WO 2013/049004
PCT/US2012/057022
Table 3
Cleaner #1A Cleaner #2 Wt % Y
2' Spray --- 0.82
l' Spray 2' Spray 1.5
Experiment 4 - Comparison of corrosion resistance on cleaned panels
subsequently coated with Electrodepositable Coating Composition 2 -
Cleaner 1A vs. Cleaner 1A followed by Cleaner 2 vs. Cleaner 2 followed by
Cleaner 1A ¨ Ecoated Panels (with Corrosion Inhibitor)
[00157] Cold-rolled steel panels (ACT Panels) were cleaned using
Alkaline
Cleaner 1A, Alkaline Cleaner lA followed by Acid Cleaner 2, or Acid Cleaner 2
followed by Alkaline Cleaner 1A, and then rinsed with deionized water. Panels
were
then dried using forced air. After drying, the panels were electrocoated in
Electrodepositable Paint Composition 2 and cured for 25 minutes @ 177 C in an
electric oven. The dry film thickness was 0.0005-0.0010 inches.
[00158] Panels with Pretreatment 1 were purchased from ACT and
electrocoated with Electrodepositable Paint Composition 1 for comparison.
[00159] Samples were then scribed vertically and placed in Test 2. The
results
are shown Table 4 below:
Table 4
Step 1 Step 2 Scribe Creep (mm)
Cleaner #1A ¨ 2' Spray --- 5.52
Cleaner #1A ¨ 30 sec
Cleaner #2 ¨ 3' Spray 3.03
Spray
Cleaner #1A ¨30 sec
Cleaner #2 ¨ 3' Spray 3.00
Spray
Phosphate (Pretreatment #1) 5.34
