Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1
PREPARATION OF TREATMENT COMPOSITION AND
SYSTEM AND METHOD OF MAINTAINING A TREATMENT
BATH FORMED THEREFROM
[0001] FIELD OF THE INVENTION
[0002] The present invention relates to treatment compositions for the
treatment of
substrates such as metal substrates, such as to treatment compositions for
forming a protective
coating on the surface, and also to the preparation of such compositions and
systems and
methods of maintaining treatment baths formed from such treatment composition.
BACKGROUND OF THE INVENTION
[0003] The use of protective coatings on metal surfaces for improved
corrosion
resistance and paint adhesion characteristics is well known in the metal
finishing arts.
Conventional techniques involve treating metal substrates with treatment
compositions
containing phosphate and chromium for promoting corrosion resistance and
adherence of the
coating formed by the treatment composition to the substrate surface. The use
of such phosphate
and/or chromate-containing compositions, however, gives rise to environmental
and health
concerns. As a result, chromate-free and/or phosphate-free treatment
compositions have been
developed.
[0004] During a typical treatment process, as a treatment composition is
contacted with a
substrate, certain ingredients, such as metal ions in the treatment
composition, deposit on or bind
to the substrate's surface to form a protective layer. As a result, the
concentration of those ions in
the composition may be diminished during the process, which may adversely
affect the coating
characteristics and reproducibility among substrates coated successively in
the same coating
composition. Accordingly, it would be desirable to provide treatment
compositions which do not
give rise to environmental and health concerns and can be used to form
protective
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coatings having efficient corrosion protection and adhesion characteristics on
a substrate surface,
and means to avoid or at least alleviate compositional variations upon
continued use of such
compositions for treating substrates and associated adverse effects on coating
characteristics and
reproducibility. The present invention therefore aims to provide treatment
compositions which
are environmentally safe and health benign, can be produced in a cost-
efficient manner from
readily available resources and yet may form a protective layer imparting
efficient corrosion
protection and having suitable adhesion on a substrate surface comparable to
phosphate and/or
chromate-containing compositions.
[0005] Another objective resides in providing a method and a system which
enable
continued use of treatment baths formed from such compositions for treating
substrates yielding
coatings of desirable characteristics in a reproducible manner without
compositional variations
that impact corrosion or adhesion performance.
SUMMARY OF THE INVENTION
[0006] These objectives are solved by the treatment composition and method
of making
the same and the method and system for maintaining a treatment bath as
specified in the
appended claims and described in more detail in the following description.
[0007] The treatment compositions described herein generally comprise a
carbon dioxide
source, a lithium cation, which may be in the form of a lithium salt, and an
aqueous medium.
[0008] The treatment composition may comprise lithium carbonate, wherein
the lithium
carbonate may be formed by reacting carbon dioxide and a lithium cation in
situ in an aqueous
medium.
[0009] The present invention thus relates to a method of making a treatment
composition
comprising: combining a lithium cation and carbon dioxide in an aqueous medium
to form a
treatment composition comprising lithium in an amount of 5 ppm to 5,500 ppm
(calculated as
lithium cation) based on total weight of the treatment composition and
carbonate in an amount of
15 ppm to 25,000 ppm (calculated as carbonate) based on total weight of the
treatment
composition.
[0010] The present invention relates furthermore to a system for
maintaining a treatment
bath formed from a treatment composition comprising lithium carbonate, the
system comprising:
a lithium salt; and/or carbon dioxide; and optionally, a hydroxide source.
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[0011] Also part of the present invention is a method for maintaining a
treatment bath
formed from a treatment composition comprising lithium carbonate, the method
comprising:
supplying during and/or after treatment of a substrate with the bath at least
one of carbon dioxide
and a lithium salt to the bath in an amount sufficient to maintain the pH of
the treatment bath at
9.5 to 12.5, lithium in an amount of 5 ppm to 5,500 ppm (calculated as lithium
cation) based on
total weight of the treatment bath, and carbonate in an amount of 15 ppm to
25,000 ppm
(calculated as carbonate) based on total weight of the treatment bath.
[0012] The present invention moreover relates to substrates treated with
such
compositions and maintained treatment baths. The coating characteristics and
reproducibility of
coatings formed on substrates treated with such compositions and maintained
treatment baths are
more consistent in successively treated substrates than are coating
characteristics and
reproducibility of coatings formed on substrates treated with compositions
that are not formed or
maintained in this manner. Accordingly, the protective coatings formed from
compositions and
treatment baths maintained according to the present invention are reproducible
and exhibit
suitable corrosion performance and adhesion on the substrate surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Fig. 1 shows a flow diagram detailing the sequential steps used to
prepare the
treatment baths containing the treatment compositions used in Examples D to J.
[0014] Fig. 2 shows a flow diagram detailing the sequential steps used to
prepare the
treatment baths containing the compositions used in Examples L to 0.
[0015] Fig. 3 shows a schematic illustrating the thickness of a layer of
the treatment
composition on a substrate surface.
DETAILED DESCRIPTION OF THE INVENTION
[0016] 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 such as those expressing values, amounts, percentages,
ranges, subranges
and fractions may be read as if prefaced by the word "about," even if the term
does not expressly
appear. 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
the desired properties to be obtained by the present invention. At the very
least, and not as an
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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. Where a closed or open-
ended numerical
range is described herein, all numbers, values, amounts, percentages,
subranges and fractions
within or encompassed by the numerical range are to be considered as being
specifically
included in and belonging to the original disclosure of this application as if
these numbers,
values, amounts, percentages, subranges and fractions had been explicitly
written out in their
entirety.
[00171 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.
[0018] As used herein, unless indicated otherwise, a plural term can
encompass its
singular counterpart and vice versa, unless indicated otherwise. For example,
although reference
is made herein to "a" lithium salt, "a" hydroxide, and "a" treatment
composition, a combination
(i.e., a plurality) of these components can be used. 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.
[0019] As used herein, "including," "containing" and like terms are
understood in the
context of this application to be synonymous with "comprising" and are
therefore open-ended
and do not exclude the presence of additional undescribed and/or unrecited
elements, materials,
ingredients and/or method steps. As used herein, "consisting of' is understood
in the context of
this application to exclude the presence of any unspecified element,
ingredient and/or method
step. As used herein, "consisting essentially of' is understood in the context
of this application
to include the specified elements, materials, ingredients and/or method steps
"and those that do
not materially affect the basic and novel characteristic(s)" of what is being
described.
[0020] As used herein, the terms "on," "onto," "applied on," "applied
onto," "formed
on," "deposited on," "deposited onto," mean foinied, overlaid, deposited,
and/or provided on but
not necessarily in contact with the surface. For example, a coating layer
"formed over" a
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substrate does not preclude the presence of one or more other intervening
coating layers of the
same or different composition located between the formed coating layer and the
substrate.
[0021] Unless otherwise disclosed herein, the term "substantially free,"
when used with
respect to the absence of a particular material, means that such material, if
present at all in a
composition, a bath containing the composition, and/or layers formed from and
comprising the
composition, only is present in a trace amount of 5 ppm or less based on a
total weight of the
composition, bath and/or layer(s), as the case may be. Unless otherwise
disclosed herein, the
term "essentially free," when used with respect to the absence of a particular
material, means that
such material, if present at all in a composition, a bath containing the
composition, and/or layers
formed from and comprising the composition, only is present in a trace amount
of 1 ppm or less
based on a total weight of the composition, bath and/or layer(s), as the case
may be Unless
otherwise disclosed herein, the term "completely free," when used with respect
to the absence of
a particular material, means that such material, if present at all in a
composition, a bath
containing the composition, and/or layers foimed from and comprising the
composition, is absent
from the composition, the bath containing the composition, and/or layers
formed from and
comprising same (i.e., the composition, bath containing the composition,
and/or layers formed
from and comprising the composition contain 0 ppm of such material). When a
composition,
bath containing a composition, and/or a layer(s) formed from and comprising
the same is
substantially free, essentially free, or completely free of a particular
material, this means that
such material is excluded therefrom, except that the material may be present
as a result of, for
example, carry-over from prior treatment baths in the processing line,
municipal water sources,
substrate(s), and/or dissolution of equipment.
[0022] As used herein, a "salt" refers to an ionic compound made up of
metal cations and
non-metallic anions and having an overall electrical charge of zero. Salts may
be hydrated or
anhydrous
[0023] As used herein, "aqueous composition" refers to a solution or
dispersion in a
medium that comprises predominantly water. For example, the aqueous medium may
comprise
water in an amount of more than 50 wt.%, or more than 70 wt.% or more than 80
wt.% or more
than 90 wt.% or more than 95 wt.%, based on the total weight of the medium.
The aqueous
medium may for example consist substantially of water.
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[0024] As used herein, the term "oxidizing agent," when used with respect
to a
component of the sealing composition, refers to a chemical which is capable of
oxidizing at least
one of: a metal present in the substrate which is contacted by the sealing
composition and/or a
metal-complexing agent present in the sealing composition. As used herein with
respect to
"oxidizing agent," the phrase "capable of oxidizing" means capable of removing
electrons from
an atom or a molecule present in the substrate or the sealing composition, as
the case may be,
thereby decreasing the number of electrons.
[0025] As used herein, the term "Group IA metal" refers to an element that
is in Group
IA of the CAS version of the Periodic Table of the Elements as is shown, for
example, in the
Handbook of Chemistry and Physics, 63rd edition (1983), corresponding to Group
1 in the actual
IUPAC numbering
[0026] As used herein, the term "Group IA metal compound" refers to
compounds that
include at least one element that is in Group IA of the CAS version of the
Periodic Table of the
Elements.
[0027] As used herein, the term "Group HA metal" refers to an element that
is in Group
IIA of the CAS version of the Periodic Table of the Elements as is shown, for
example, in the
Handbook of Chemistry and Physics, 63' edition (1983), corresponding to Group
2 in the actual
IUPAC numbering.
[0028] As used herein, the term "Group HA metal compound" refers to
compounds that
include at least one element that is in Group HA of the CAS version of the
Periodic Table of the
Elements.
[0029] As used herein, the term "Group IIIB metal" refers to yttrium and
scandium of the
CAS version of the Periodic Table of the Elements as is shown, for example, in
the Handbook of
Chemistry and Physics, 63'd edition (1983), corresponding to Group 3 in the
actual IUPAC
numbering. For clarity, "Group MB metal" expressly excludes lanthanide series
elements.
[0030] As used herein, the term "Group IIIB metal compound" refers to
compounds that
include at least one element that is in group IIIB of the CAS version of the
Periodic Table of the
Elements as defined above.
[0031] As used herein, the term "Group IVB metal" refers to an element that
is in group
IVB of the CAS version of the Periodic Table of the Elements as is shown, for
example, in the
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Handbook of Chemistry and Physics, 63' edition (1983), corresponding to Group
4 in the actual
RIPAC numbering.
[0032] As used herein, the term "Group IVB metal compound" refers to
compounds that
include at least one element that is in Group IVB of the CAS version of the
Periodic Table of the
Elements.
[0033] As used herein, the term "Group VB metal" refers to an element that
is in group
VB of the CAS version of the Periodic Table of the Elements as is shown, for
example, in the
Handbook of Chemistry and Physics, 63' edition (1983), corresponding to Group
5 in the actual
IUPAC numbering.
[0034] As used herein, the term "Group VB metal compound" refers to
compounds that
include at least one element that is in Group VB of the CAS version of the
Periodic Table of the
Elements
[0035] As used herein, the term "Group VIB metal" refers to an element that
is in group
VIB of the CAS version of the Periodic Table of the Elements as is shown, for
example, in the
Handbook of Chemistry and Physics, 63' edition (1983), corresponding to Group
6 in the actual
IUPAC numbering.
[0036] As used herein, the term "Group VIB metal compound" refers to
compounds that
include at least one element that is in Group VIB of the CAS version of the
Periodic Table of the
Elements.
[0037] As used herein, the term "Group VIM metal" refers to an element that
is in Group
IA of the CAS version of the Periodic Table of the Elements as is shown, for
example, in the
Handbook of Chemistry and Physics, 63rd edition (1983), corresponding to Group
7 in the actual
IUPAC numbering
[0038] As used herein, the term "Group VII13 metal compound" refers to
compounds that
include at least one element that is in Group VIIB of the CAS version of the
Periodic Table of
the Elements
[0039] As used herein, the term "Group XII metal" refers to an element that
is in Group
IA of the CAS version of the Periodic Table of the Elements as is shown, for
example, in the
Handbook of Chemistry and Physics, 63 edition (1983), corresponding to Group
12 in the
actual IUPAC numbering.
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[0040] As used herein, the term "Group XII metal compound" refers to
compounds that
include at least one element that is in Group XII of the CAS version of the
Periodic Table of the
Elements.
[0041] As used herein, the term "lanthanide series elements" refers to
elements 57-71 of
the CAS version of the Periodic Table of the Elements and includes elemental
versions of the
lanthanide series elements. According to the present invention, the lanthanide
series elements
may be those which have both common oxidation states of +3 and +4, referred to
hereinafter as
+3/+4 oxidation states.
[0042] As used herein, the term "lanthanide compound" refers to compounds
that include
at least one of elements 57-71 of the CAS version of the Periodic Table of the
Elements.
[0043] As used herein, a "sealing composition" refers to a composition,
e.g. a solution or
dispersion, that affects a substrate surface or a material deposited onto a
substrate surface in such
a way as to alter the physical and/or chemical properties of the substrate
surface (e.g., the
composition affords corrosion protection).
[0044] As used herein, a "conversion composition" refers to a composition,
e.g., a
solution or dispersion, that is capable of reacting with and chemically
altering the substrate
surface and binding to it to form a film that affords corrosion protection.
[0045] As used herein, a "treatment bath" refers to an aqueous bath formed
from an
initial treatment composition. The treatment bath may contain components that
are byproducts of
the process of contacting a substrate with the treatment composition.
[0046] As used herein, "maintaining" a treatment bath formed from a
treatment
composition refers to keeping certain parameters of the treatment bath
including the
concentration of certain ingredients and/or the pH in desirable ranges. This
can be achieved, as
described in more detail below, by the addition of one or more materials from
a respective source
to the treatment bath on-shift and/or off-shift. As used herein, "on-shift"
means that an article to
be treated is present in the treatment bath. As used herein, "off-shift" means
that an article to be
treated by the treatment composition is absent from the treatment bath, but
does not mean that
the treatment bath is necessarily removed from the process line.
[0047] Pitting corrosion is the localized formation of corrosion by which
cavities or holes
are produced in a substrate. The term "pit," as used herein, refers to such
cavities or holes
resulting from pitting corrosion and is characterized by (1) a rounded,
elongated or irregular
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appearance when viewed normal to the test panel surface, (2) a "comet-tail", a
line, or a "halo"
(i.e., a surface discoloration) emanating from the pitting cavity, and (3) the
presence of corrosion
byproduct (e.g., white, grayish or black granular, powdery or amorphous
material) inside or
immediately around the pit. An observed surface cavity or hole must exhibit at
least two of the
above characteristics to be considered a corrosion pit. Surface cavities or
holes that exhibit only
one of these characteristics may require additional analysis before being
classified as a corrosion
pit. Visual inspection using a microscope with 10X magnification is used to
determine the
presence of corrosion byproducts when corrosion byproducts are not visible
with the unaided
eye.
[0048] Unless otherwise disclosed herein, as used herein, the terms "total
composition
weight", "total bath weight", "total weight of a composition", "total weight
of a treatment bath"
or similar terms refer to the total weight of all ingredients being present in
the respective
composition or bath including any carriers and solvents.
[0049] As mentioned above, according to the present invention, disclosed is
a treatment
composition comprising lithium carbonate. The lithium carbonate may in
particular be formed in
situ as set forth above by reacting carbon dioxide and a lithium cation, which
may be in the form
of a lithium salt, for example, in an aqueous medium. The treatment
composition may be a
sealing composition, a conversion composition, or the like.
[0050] The treatment composition of the present invention is typically
alkaline.
According to the present invention, the pH of the treatment composition may be
at least 9.5, such
as at least 10, such as at least 11, and in some instances, may be no greater
than 12.5, such as no
greater than 12, such as no greater than 11.5. According to the present
invention, the pH of the
treatment composition may be 9.5 to 12.5, such as 10 to 12, such as 11 to
11.5. According to the
present invention, the pH of the treatment composition may be adjusted through
the inclusion of
an acidic material, including carbon dioxide, water soluble and/or water
dispersible acids, such
as nitric acid, sulfuric acid, and/or phosphoric acid. According to the
present invention, the pH
of the treatment composition may be adjusted through the inclusion of a basic
material, including
water soluble and/or water dispersible bases including carbonates, such as
Group I carbonates,
Group II carbonates, hydroxides, such as lithium hydroxide, sodium hydroxide,
potassium
hydroxide, or ammonium hydroxide, ammonia, and/or amines such as
triethylamine, methylethyl
amine, or mixtures thereof.
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[0051] According to the present invention, the carbon dioxide used to form
the treatment
composition of the present invention may be a gas, a solid (i.e., dry ice), or
a combination
thereof.
[0052] According to the present invention, the lithium salt used to form
the treatment
composition of the present invention may comprise an inorganic lithium salt,
an organic lithium
salt, or combinations thereof. According to the present invention, the anion
and the cation of the
lithium salt both may be soluble in water. According to the present invention,
the lithium salt
may have a solubility constant in water at a temperature of 25 C. (K; 25 C)
of at least 1x1011,
such as least 1x104, and in some instances, may be no more than 5x I 0'.
According to the
present invention, the lithium salt may have a solubility constant in water at
a temperature of 25
C. (K ;25 C.) of 1x10-11 to 5x10+2, such as 1x10' to 5x10+2. As used herein,
"solubility
constant" means the product of the equilibrium concentrations of the ions in a
saturated aqueous
solution of the respective lithium salt. Each concentration is raised to the
power of the respective
coefficient of ion in the balanced equation. The solubility constants for
various salts can be
found in the Handbook of Chemistry and Physics. Examples of suitable lithium
salts are lithium
carbonate, lithium hydroxide, lithium phosphate, lithium sulphate, and lithium
tetraborate.
[0053] Optionally, the treatment composition also may comprise a hydroxide,
such as an
alkaline metal hydroxide, an alkaline earth metal hydroxide, or a combination
thereof.
According to the present invention, the hydroxide may be one or more Group I
hydroxide(s),
ammonium hydroxide, or mixtures thereof The hydroxide, if present at all, may
be present in
any amount, such as in an amount that the pH of the treatment composition
remains 9.5 to 12.5.
Nonlimiting examples of Group I hydroxides include sodium hydroxide, potassium
hydroxide,
lithium hydroxide, or mixtures thereof Accordingly, the hydroxide, if used,
may be supplied as
the lithium salt component used to form the treatment composition or part
thereof, e.g. as lithium
hydroxide, optionally in combination with other lithium salts such as lithium
carbonate. The
treatment composition may however also comprise one or more hydroxide
different from lithium
salts such as for example sodium hydroxide, potassium hydroxide, or a
combination thereof.
[0054] The treatment composition of the present invention generally
comprises an
aqueous medium as a carrier. The composition may thus be in the form of a
solution or
dispersion of the lithium salt in the carrier.
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[0055] According to the present invention, lithium carbonate is formed by
combining
carbon dioxide and a lithium cation in the aqueous carrier medium wherein the
carbon dioxide
and lithium cation are balanced to be present in amounts such that lithium is
present in the
treatment composition in an amount of 5 ppm to 5,500 ppm (calculated as
lithium cation) based
on total weight of the treatment composition, carbonate is present in the
treatment composition in
an amount of 15 ppm to 25,000 ppm (calculated as carbonate) based on total
weight of the
treatment composition. As set forth above, optionally further one or more pH
modifier(s) such as
one or more acidic material(s) and/or one or more basic material(s) such as
one or more
hydroxide is added to the aqueous carrier medium wherein the amounts of such
optional pH
modifier(s), carbon dioxide and lithium salt may be balanced such that the pH
of the treatment
composition is 9.5 to 125.
[0056] According to the present invention, the treatment composition may
further
comprise at least one Group IA metal cation other than lithium, a Group VB
metal cation, and/or
Group VIB metal cation. According to the present invention, the at least one
Group IA metal
cation other than lithium, a Group VB metal cation, and/or Group VIE metal
cation may be in
the form of a salt and cation each may be present in the treatment composition
in an amount of at
least 5 ppm, such as at least 50 ppm, such as at least 150 ppm, such as at
least 250 ppm
(calculated as metal cation) based on total weight of the treatment
composition, and in some
instances, may be present in an amount of no more than 5,500 ppm, such as no
more than 1,200
ppm, such as no more than 1,000 ppm, such as no more than 500 ppm, (calculated
as metal
cation) based on total weight of the treatment composition. In some instances,
according to the
present invention, the lithium metal may be present in the treatment
composition in an amount of
ppm to 5,500 ppm, such as 50 ppm to 1,000 ppm, (calculated as metal cation)
based on total
weight of the treatment composition, such as 150 ppm to 500 ppm.
[0057] Nonlimiting examples of anions suitable for forming a salt with
lithium cation,
Group IA cations other than lithium, Group VB cations, and/or Group VIE
cations include
carbonates, hydroxides, nitrates, halogens, sulfates, phosphates and silicates
(e.g., orthosilicates
and metasilicates) such that the metal salt may comprise a carbonate, an
hydroxide, a nitrate, a
halide, a sulfate, a phosphate, a silicate (e.g., orthosilicate or
metasilicate), a permanganate, a
chromate, a vanadate, a molybdate, and/or a perchlorate.
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[0058] According to the present invention, the metal salts of the treatment
composition
(i.e., the salts of lithium, Group IA metals other than lithium, Group VB,
and/or Group V1B)
each may be present in the treatment composition in an amount of at least 25
ppm, such as at
least 150 ppm, such as at least 500 ppm (calculated as total compound) based
on total weight of
the treatment composition, and in some instances, no more than 30,000 ppm,
such as no more
than 2,000 ppm, such as no more than 1,500 ppm (calculated as total compound)
based on total
weight of the treatment composition. According to the present invention, the
metal salts each
may be present in the treatment composition in an amount of 25 ppm to 30,000
ppm, such as 150
ppm to 2,000 ppm, such as 500 ppm to 1,500 (calculated as total compound)
based on total
weight of the treatment composition.
[0059] According to the present invention, the sealing composition of the
present
invention may an include oxidizing agent, such as hydrogen peroxide,
persulfates, perchlorates,
sparged oxygen, bromates, peroxi-benzoates, ozone, and the like, or
combinations thereof. For
example, the sealing composition may comprise 0.1 wt % to 15 wt % of an
oxidizing agent based
on total weight of the sealing composition, such as 2 wt% to 10 wt %, such as
6 wt% to 8 wt%.
Alternatively, according to the present invention, the sealing composition may
be substantially
free, or in some cases, essentially free, or in some cases, completely free,
of an oxidizing agent.
[0060] According to the present invention, the treatment composition may
exclude
chromium or chromium-containing compounds. As used herein, the term "chromium-
containing
compound" refers to materials that include hexavalent chromium. Non-limiting
examples of
such materials include chromic acid, chromium trioxide, chromic acid
anhydride, dichromate
salts, such as ammonium dichromate, sodium dichromate, potassium dichromate,
and calcium,
barium, magnesium, zinc, cadmium, and strontium dichromate. When a treatment
composition
and/or a bath, or a coating or a layer formed from the same is substantially
free, essentially free,
or completely free of chromium, this includes chromium in any form, such as,
but not limited to,
the hexavalent chromium-containing compounds listed above.
[0061] Thus, optionally, according to the present invention, the present
treatment
compositions and/or treatment baths and/or coatings or layers formed from the
same may be
substantially free, may be essentially free, and/or may be completely free of
one or more of any
of the elements or compounds listed in the preceding paragraph. A treatment
composition and/or
bath and/or coating or layer formed from the same that is substantially free
of chromium or
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chromium-containing compounds means that chromium or chromium-containing
compounds are
not intentionally added, but may be present in trace amounts, such as because
of impurities or
unavoidable contamination from the environment. In other words, the amount of
material is so
small that it does not affect the properties of the treatment composition
and/or bath and/or
coating or layer formed from the same; in the case of chromium, this may
further include that the
element or compounds thereof are not present in the treatment compositions
and/or baths and/or
coatings or layers formed from the same, in such a level that it causes a
burden on the
environment. The term "substantially free" may thus for example mean that the
treatment
compositions and/or baths and/or coating or layers formed from the same
contain less than 10
ppm of any or all of the elements or compounds listed in the preceding
paragraph, based on total
weight of the composition, bath, coating or layer, as the case may be, if any
at all. The term
"essentially free" means that the treatment compositions and/or baths and/or
coatings or layers
formed from the same contain less than 1 ppm of any or all of the elements or
compounds listed
in the preceding paragraph, based on total weight of the composition, bath,
coating or layer, as
the case may be, if any at all. The teini "completely free" means that the
treatment compositions
and/or baths and/or coatings or layers formed from the same contain less than
1 ppb of any or all
of the elements or compounds listed in the preceding paragraph, based on total
weight of the
composition, bath, coating or layer, as the case may be, if any at all.
[0062]
According to the present invention, the present treatment compositions and/or
treatment baths and/or coatings or layers formed from the same may, in some
instances, exclude
phosphate ions or phosphate-containing compounds and/or the formation of
sludge, such as
aluminum phosphate, iron phosphate, and/or zinc phosphate, formed for example
in the case of
using a treating agent based on zinc phosphate. As used herein, "phosphate-
containing
compounds" include compounds containing the element phosphorous such as ortho
phosphate,
pyrophosphate, metaphosphate, tripolyphosphate, organophosphonates, and the
like, and can
include, but are not limited to, monovalent, divalent, or trivalent cations
such as: sodium,
potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. When a
treatment
composition and/or bath and/or coatings or layers formed from the same is
substantially free,
essentially free, or completely free of phosphate, this includes phosphate
ions or compounds
containing phosphate in any form.
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[0063] Thus, according to the present invention, the treatment compositions
and/or baths
and/or coatings or layers formed from the same disclosed herein may be
substantially free, or in
some cases may be essentially free, or in some cases may be completely free,
of one or more of
any of the ions or compounds listed in the preceding paragraph. A treatment
compositions
and/or baths and/or coatings or layers formed from the same that is
substantially free of
phosphate means that phosphate ions or compounds containing phosphate are not
intentionally
added, but may be present in trace amounts, such as because of impurities or
unavoidable
contamination from the environment. In other words, the amount of material is
so small that it
does not affect the properties of the treatment compositions and/or baths
and/or coatings or
layers formed from the same; this may further include that phosphate is not
present in the
treatment compositions and/or baths and/or coatings or layers formed from the
same in such a
level that they cause a burden on the environment. The term "substantially
free" may in
particular mean that the treatment compositions and/or baths and/or coatings
or layers formed
from the same contain less than 5 ppm of any or all of the phosphate anions or
compounds listed
in the preceding paragraph, based on total weight of the composition, bath,
coating or layer, as
the case may be, if any at all. The term "essentially free" means that the
treatment compositions
and/or baths and/or coatings or layers formed from the same contain less than
1 ppm of any or all
of the phosphate anions or compounds listed in the preceding paragraph, based
on total weight of
the composition, bath, coating or layer, as the case may be, if any at all.
The term "completely
free" means that the treatment compositions and/or baths and/or coatings or
layers formed from
the same contain less than 1 ppb of any or all of the phosphate anions or
compounds listed in the
preceding paragraph, based on total weight of the composition, bath, coating
or layer, as the case
may be, if any at all.
[0001] A According to the present invention, the sealing composition may
exclude Group
IIA metal cations or Group IIA metal-containing compounds, including but not
limited to
calcium. Non-limiting examples of such materials include Group IIA metal
hydroxides, Group
IIA metal nitrates, Group HA metal halides, Group IIA metal sulfamates, Group
IIA metal
sulfates, Group IIA carbonates and/or Group IIA metal carboxylates. When a
sealing
composition and/or a coating or a layer, respectively, formed from the same is
substantially free,
essentially free, or completely free of a Group HA metal cation, this includes
Group HA metal
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cations in any form, such as, but not limited to, the Group IIA metal-
containing compounds
listed above.
[0064] According to the present invention, the sealing composition may, in
some
instances, exclude fluoride or fluoride sources. As used herein, "fluoride
sources" include
monofluorides, bifluorides, fluoride complexes, and mixtures thereof known to
generate fluoride
ions. When a composition and/or a layer or coating comprising the same is
substantially free,
essentially free, or completely free of fluoride, this includes fluoride ions
or fluoride sources in
any form, but does not include unintentional fluoride that may be present in a
bath as a result of,
for example, carry-over from prior treatment baths in the processing line,
municipal water
sources (e.g.: fluoride added to water supplies to prevent tooth decay),
fluoride from a pretreated
substrate, or the like. That is, a bath that is substantially free,
essentially free, or completely free
of fluoride, may have unintentional fluoride that may be derived from these
external sources,
even though the composition used to make the bath prior to use on the
processing line was
substantially free, essentially free, or completely free of fluoride.
[0065] For example, the sealing composition may be substantially free of
any fluoride-
sources, such as ammonium and alkali metal fluorides, acid fluorides,
fluoroboric, fluorosilicic,
fluorotitanic, and fluorozirconic acids and their ammonium and alkali metal
salts, and other
inorganic fluorides, nonexclusive examples of which are: zinc fluoride, zinc
aluminum fluoride,
titanium fluoride, zirconium fluoride, nickel fluoride, ammonium fluoride,
sodium fluoride,
potassium fluoride, and hydrofluoric acid, as well as other similar materials
known to those
skilled in the art.
[0066] Fluoride present in the sealing composition that is not bound to
metals ions such
as Group IVB metal ions, or hydrogen ion, defined herein as "free fluoride,"
may be measured as
an operational parameter in the sealing composition bath using, for example,
an Orion Dual Star
Dual Channel Benchtop Meter equipped with a fluoride ion selective electrode
("ISE") available
from Thermoscientific, the symphony Fluoride Ion Selective Combination
Electrode supplied
by VWR International, or similar electrodes. See, e.g., Light and Cappuccino,
Determination of
fluoride in toothpaste using an ion-selective electrode, J. Chem. Educ., 52:4,
247-250, April
1975. The fluoride ISE may be standardized by immersing the electrode into
solutions of known
fluoride concentration and recording the reading in millivolts, and then
plotting these millivolt
readings in a logarithmic graph. The millivolt reading of an unknown sample
can then be
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compared to this calibration graph and the concentration of fluoride
determined. Alternatively,
the fluoride ISE can be used with a meter that will perform the calibration
calculations internally
and thus, after calibration, the concentration of the unknown sample can be
read directly.
[0067] Fluoride ion is a small negative ion with a high charge density, so
in aqueous
solution it is frequently complexed with metal ions having a high positive
charge density, such as
Group IVB metal ions, or with hydrogen ion. Fluoride anions in solution that
are ionically or
covalently bound to metal cations or hydrogen ion are defined herein as "bound
fluoride." The
fluoride ions thus complexed are not measurable with the fluoride ISE unless
the solution they
are present in is mixed with an ionic strength adjustment buffer (e.g.:
citrate anion or EDTA) that
releases the fluoride ions from such complexes. At that point (all of) the
fluoride ions are
measurable by the fluoride ISE, and the measurement is known as "total
fluoride". Alternatively,
the total fluoride can be calculated by comparing the weight of the fluoride
supplied in the sealer
composition by the total weight of the composition.
[0068] According to the present invention, the treatment composition may,
in some
instances, be substantially free, or in some instances, essentially free, or
in some instances,
completely free, of cobalt ions or cobalt-containing compounds. As used
herein, "cobalt-
containing compounds" include compounds, complexes or salts containing the
element cobalt
such as, for example, cobalt sulfate, cobalt nitrate, cobalt carbonate and
cobalt acetate. When a
composition and/or a layer or coating comprising the same is substantially
free, essentially free,
or completely free of cobalt, this includes cobalt ions or compounds
containing cobalt in any
form.
[0069] According to the present invention, the treatment composition may,
in some
instances, be substantially free, or in some instances, essentially free, or
in some instances,
completely free, of vanadium ions or vanadium-containing compounds. As used
herein,
"vanadium-containing compounds" include compounds, complexes or salts
containing the
element vanadium such as, for example, vanadates and decavanadates that
include counterions of
alkali metal or ammonium cations, including, for example, sodium ammonium
decavanadate. When a composition and/or a layer or coating comprising the same
is
substantially free, essentially free, or completely free of vanadium, this
includes vanadium ions
or compounds containing vanadium in any foim.
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[0070] According to the present invention, the treatment composition may
optionally
further contain an indicator compound, so named because it indicates, for
example, the presence
of a chemical species, such as a metal ion, the pH of a composition, and the
like. An "indicator",
"indicator compound", and like terms as used herein refer to a compound that
changes color in
response to some external stimulus, parameter, or condition, such as the
presence of a metal ion,
or in response to a specific pH or range of pHs.
[0071] The indicator compound used according to the present invention can
be any
indicator known in the art that indicates the presence of a species, a
particular pH, and the like.
For example, a suitable indicator may be one that changes color after forming
a metal ion
complex with a particular metal ion. The metal ion indicator is generally a
highly conjugated
organic compound. A "conjugated compound" as used herein, and as will be
understood by
those skilled in the art, refers to a compound having two double bonds
separated by a single
bond, for example two carbon-carbon double bonds with a single carbon-carbon
bond between
them. Any conjugated compound can be used according to the present invention.
[0072] Similarly, the indicator compound can be one in which the color
changes upon
change of the pH; for example, the compound may be one color at an acidic or
neutral pH and
change color in an alkaline pH, or vice versa. Such indicators are well known
and widely
commercially available. An indicator that "changes color upon transition from
a first pH to a
second pH" (i.e., from a first pH to a second pH that is more or less acidic
or alkaline) therefore
has a first color (or is colorless) when exposed to a first pH and changes to
a second color (or
goes from colorless to colored) upon transition to a second pH (i.e., one that
is either more or
less acidic or alkaline than the first pH). For example, an indicator that
"changes color upon
transition to a more alkaline pH (or less acidic pH) goes from a first
color/colorless to a second
color/color when the pH transitions from acidic/neutral to alkaline. For
example, an indicator
that "changes color upon transition to a more acidic pH (or less alkaline pH)
goes from a first
color/colorless to a second color/color when the pH transitions from
alkaline/neutral to acidic
[0073] Non-limiting examples of such indicator compounds include methyl
orange,
xylenol orange, catechol violet, bromophenol blue, green and purple,
eriochrome black T,
Celestine blue, hematoxylin, calmagite, gallocyanine, and combinations
thereof. Optionally, the
indicator compound may comprise an organic indicator compound that is a metal
ion indicator.
Nonlimiting examples of indicator compounds include those found in Table 1.
Fluorescent
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indicators, which will emit light in certain conditions, can also be used
according to the present
invention, although the use of a fluorescent indicator also may be
specifically excluded. That is,
alternatively, conjugated compounds that exhibit fluorescence are specifically
excluded. As used
herein, "fluorescent indicator" and like terms refer to compounds, molecules,
pigments, and/or
dyes that will fluoresce or otherwise exhibit color upon exposure to
ultraviolet or visible light.
To "fluoresce" will be understood as emitting light following absorption of
shorter wavelength
light or other electromagnetic radiation. Examples of such indicators, often
referred to as "tags,"
include acridine, anthraquinone, coumarin, diphenylmethane,
diphenylnaphthlymethane,
quinoline, stilbene, triphenylmethane, anthracine and/or molecules containing
any of these
moieties and/or derivatives of any of these such as rhodamines,
phenanthridines, oxazines,
fluorones, cyanines and/or acri dines.
TABLE 1
Compound Structure CAS Reg. No.
Catechol Violet 0 115-41-3
Synonyms: OH
OH
Catecholsulfonphthalein;
Pyrocatecholsulfonephthalein; HO
Pyrocatechol Violet
HO
Xylenol Orange 3618-43-7
_
Synonym: 0,0.011
3,3'-Bis[N,N-
'-
ISO
bis(carboxymethyBaminomethyl]-
611
o-cresolsulfonephthalein tetrasodium salt HO
NJ,OH
Cr4(OH
[0074] According to the present invention, the conjugated compound useful
as indicator
may for example comprise catechol violet, as shown in Table 1. Catechol violet
(CV) is a
sulfone phthalein dye made from condensing two moles of pyrocatechol with one
mole of o-
sulfobenzoic acid anhydride. It has been found that CV has indicator
properties and when
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incorporated into compositions having metal ions, it forms complexes, making
it useful as a
complexiometric reagent. As the composition containing the CV chelates metal
ions coming
from the metal substrate (i.e., those having bi- or higher valence), a
generally blue to blue-violet
color is observed.
[0075] Xylenol orange, as shown in Table 1 may likewise be employed in the
compositions according to the present invention. It has been found that
xylenol orange has metal
ion (i.e., those having bi- or higher valence) indicator properties and when
incorporated into
compositions having metal ions, it forms complexes, making it useful as a
complexiometric
reagent. As the composition containing the xylenol orange chelates metal ions,
a solution of
xylenol orange turns from red to a generally blue color.
[0076] According to the present invention, the indicator compound may be
present in the
treatment composition in an amount of at least 0.01 g/1000 g treatment
composition, such as at
least 0.05 g/1000 g treatment composition, and in some instances, no more than
3 g/1000 g
treatment composition, such as no more than 0.3g/1000 g treatment composition.
According to
the present invention, the indicator compound may be present in the treatment
composition in an
amount of 0.01 g/1000 g treatment composition to 3 g/1000 g treatment
composition, such as
0.05 g/1000 g treatment composition to 0.3 g/1000 g treatment composition.
[0077] According to the present invention, the indicator compound changing
color in
response to a certain external stimulus provides a benefit when using the
treatment composition
in that it can serve, for example, as a visual indication that a substrate has
been treated with the
composition. For example, a treatment composition comprising an indicator that
changes color
when exposed to a metal ion that is present in the substrate will change color
upon complexing
with metal ions in that substrate; this allows the user to see that the
substrate has been contacted
with the composition. Similar benefits can be realized by depositing an
alkaline or acid layer on
a substrate and contacting the substrate with a composition of the present
invention that changes
color when exposed to an alkaline or acidic pH.
[0078] Optionally, the treatment composition of the present invention may
further
comprise a nitrogen-containing heterocyclic compound. The nitrogen-containing
heterocyclic
compound may include cyclic compounds having 1 nitrogen atom, such as
pyrroles, and azole
compounds having 2 or more nitrogen atoms, such as pyrazoles, imidazoles,
triazoles, tetrazoles
and pentazoles, 1 nitrogen atom and 1 oxygen atom, such as oxazoles and
isoxazoles, or 1
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nitrogen atom and 1 sulfur atom, such as thiazoles and isothiazoles.
Nonlimiting examples of
suitable azole compounds include 2,5-dimercapto-1,3,4-thiadiazole (CAS:1072-71-
5), 1H-
benzotriazole (CAS: 95-14-7), 1H-1,2,3-triazole (CAS: 288-36-8), 2-amino-5-
mercapto-1,3,4-
thiadiazole (CAS: 2349-67-9), also named 5-amino-1,3,4-thiadiazole-2-thiol,
and 2-amino-1,3,4-
thiadiazole (CAS: 4005-51-0). In some embodiments, for example, the azole
compound
comprises 2,5-dimercapto-1,3,4-thiadiazole. Additionally, according to the
present invention,
the nitrogen-containing heterocyclic compound may be in the form of a salt,
such as a sodium
salt.
[00791 The nitrogen-containing heterocyclic compound may be present in the
treatment
composition at a concentration of at least 0 0005 g per liter of composition,
such as at least
0.0008 g per liter of composition, such as at least 0.002 g per liter of
composition, and in some
instances, may be present in the treatment composition in an amount of no more
than 3 g per liter
of composition, such as no more than 0.2 g per liter of composition, such as
no more than 0.1 g
per liter of composition. According to the present invention, the nitrogen-
containing
heterocyclic compound may be present in the treatment composition (if at all)
at a concentration
of 0.0005 g per liter of composition to 3 g per liter of composition, such as
0.0008 g per liter of
composition to 0.2 g per liter of composition, such as 0.002 g per liter of
composition to 0.1 g
per liter of composition.
[0080] As indicated above, the treatment composition of the present
invention comprises
an aqueous medium as carrier. The aqueous carrier may optionally contain other
materials such
as at least one organic solvent. Nonlimiting examples of suitable solvents
include propylene
glycol, ethylene glycol, glycerol, low molecular weight alcohols (i.e., CI-C12
alcohols), and the
like. When present, if at all, the organic solvent may be present in the
treatment composition in
an amount of at least 1 g solvent per liter of treatment composition, such as
at least about 2 g
solvent per liter of treatment composition, and in some instances, may be
present in an amount of
no more than 40 g solvent per liter of treatment composition, such as no more
than 20 g solvent
per liter of treatment composition. According to the present invention, the
organic solvent may
be present in the treatment composition, if at all, in an amount of 1 g
solvent per liter of
treatment composition to 40 g solvent per liter of treatment composition, such
as 2 g solvent per
liter of treatment composition to 20 g solvent per liter of treatment
composition.
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[0081] As set forth above, the treatment composition of the present
invention described
above may be prepared by a method that comprises combining a lithium salt and
carbon dioxide
in an aqueous carrier medium to form the treatment composition comprising
lithium in an
amount of 5 ppm to 5,500 ppm (calculated as lithium cation) based on total
weight of the
treatment composition and carbonate in an amount of 15 ppm to 25,000 ppm
(calculated as
carbonate) based on total weight of the treatment composition. Suitable
lithium salts and
amounts of lithium in the treatment composition are described above. For
example, the lithium
salt used in the method of forming the treatment composition can comprise
lithium carbonate,
lithium hydroxide, or a combination thereof The method of making a treatment
composition of
the present invention may furthermore comprise adjusting the pH of the
treatment composition to
a pH of at least 9.5, such as at least 10, such as at least 11, and in some
instances to a pH no
greater than 12.5, such as no greater than 12, such as no greater than 11.5.
According to the
present invention, the treatment composition may thus be adjusted to have a pH
of 9.5 to 12.5,
such as 10 to 12, such as 11 to 11.5. The pH of the treatment composition may
be measured
according to any of the methods described below and may be adjusted using, for
example, any
acid and/or base as is necessary, as described above.
[0082] According to the present invention, the method of making the
treatment
composition comprises combining carbon dioxide, and the lithium salt in an
aqueous medium.
According to the present invention, the carbon dioxide may be supplied to the
aqueous carrier
medium in the form of a gas, a solid, or a combination thereof. As used
herein, "supplied," when
used with respect to carbon dioxide, refers to introducing carbon dioxide to
the composition
using a source other than the atmosphere. The carbon dioxide is supplied to
the aqueous medium
in an amount sufficient to form the treatment composition comprising carbonate
(calculated as
carbonate) in an amount of at least 15 ppm based on total weight of the
treatment composition,
such as at least 50 ppm, such as at least 200 ppm, and in some instances, no
more than 25,000
ppm based on total weight of the treatment composition, such as no more than
15,000 ppm, such
as no more than 2,400 ppm. In some instances, according to the present
invention, the carbon
dioxide may be combined with water in an amount sufficient to form the
treatment composition
comprising carbonate (calculated as carbonate) in an amount of 15 ppm to
25,000 ppm based on
total weight of the treatment composition, such as 50 ppm to 15,000 ppm, such
as 200 ppm to
2,400 ppm.
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[0083] As pointed out above, the method of making the treatment composition
according
to the present invention also may comprise adding a hydroxide, such as Group I
hydroxides,
ammonium hydroxide, or mixtures thereof. The hydroxide source, if present at
all, may be
present in any amount, such as in an amount such that the pH of the treatment
composition is
within the range of 9.5 to 12.5. Nonlimiting examples of Group I hydroxides
include sodium
hydroxide, potassium hydroxide, lithium hydroxide, or mixtures thereof.
[0084] As mentioned above, according to the present invention, also
disclosed is a
system and method of maintaining a treatment bath formed from a treatment
composition
comprising lithium carbonate. The treatment composition may be the treatment
composition
described above and may be made according to the method described herein above
or may be
made by any method known to those of skill in the art. In an example,
according to the present
invention, a "treatment bath" may refer to an aqueous bath formed from an
initial treatment
composition comprising lithium carbonate, e.g. as described above, upon
treatment of one or
more substrate(s). As used "maintaining" a treatment bath formed from the
treatment
composition comprising lithium carbonate (regardless of how the lithium
carbonate composition
was formed) refers to keeping certain parameters of the treatment bath
including the
concentration of lithium and carbonate and the pH in desirable ranges such as
those indicated
above for the treatment composition according to the present invention. This
can be achieved, as
described in more detail below, by the addition of one or more materials from
a respective source
to the treatment bath on-shift and/or off-shift.
[0085] According to the present invention, the system or method of
maintaining may
comprise (i) adding materials to the treatment bath formed from the treatment
composition that
are different from materials used to formulate the treatment composition
and/or (ii) adding
materials to the treatment bath formed from the treatment composition that are
the same as those
materials used to formulate the treatment composition For example, while the
method of
maintaining the treatment bath containing the treatment composition may
comprise adding
carbon dioxide to the treatment bath, the treatment composition may be
formulated using a
carbonate.
[0086] According to the present invention, the system or method of
maintaining may
comprise adding materials to the treatment bath containing the treatment
composition that are the
same as materials used to formulate the treatment composition. For example,
the treatment
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composition may be formulated using carbon dioxide (as described above), and
the method of
maintaining the treatment bath containing the treatment composition may
comprise adding
carbon dioxide to the treatment bath.
[0087] The system or method of the present invention is not directed to
simply adding
more treatment composition to the treatment bath in order to maintain the
bath. Rather, as
mentioned above, the system and method of the present invention are directed
to adding carbon
dioxide and/or a lithium salt and/or a hydroxide to the treatment bath in an
amount sufficient to
maintain the pH of the treatment bath at 9.5 to 12.5, lithium in an amount of
5 ppm to 5,500 ppm
(calculated as lithium cation) based on total weight of the treatment bath,
and carbonate in an
amount of 15 ppm to 25,000 ppm (calculated as carbonate) based on total weight
of the treatment
bath. The supplying can be carried out on-shift or off-shift.
[0088] As mentioned above, according to the present invention, the system
for
maintaining a treatment bath formed from a treatment composition comprising
lithium carbonate
is disclosed. According to the present invention, the system may comprise a
lithium salt and/or a
carbon dioxide, optionally a hydroxide, or a combination of any of the
foregoing. The lithium
salt may comprise one or more of any of the lithium salts described above,
such as for example
lithium carbonate, lithium hydroxide or a combination thereof. The carbon
dioxide may comprise
carbon dioxide as a gas, a solid, or a combination thereof. The hydroxide may
comprise one or
more of any of the hydroxides mentioned above such as for example lithium
hydroxide, sodium
hydroxide, potassium hydroxide or a combination thereof. The lithium salt,
carbon dioxide,
and/or hydroxide described above may be included in the system individually or
in any
combination and may be added from their respective sources of the system to
the treatment bath
formed from the treatment composition to achieve a treatment bath being
maintained having a
pH and amounts of lithium and carbonate as described above.
[0089] As mentioned above, according to the present invention, also
disclosed is a
method of maintaining a treatment bath formed from a treatment composition
comprising lithium
carbonate. According to the present invention, the method comprises supplying
during and/or
after treatment of a substrate with the bath at least one of carbon dioxide
and a lithium salt and,
optionally, a hydroxide to the treatment bath in an amount sufficient to
maintain the pH of the
treatment bath at 9.5 to 12.5, lithium in an amount of 5 ppm to 5,500 ppm
(calculated as lithium
cation) based on total weight of the treatment bath, and carbonate in an
amount of 15 ppm to
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25,000 ppm (calculated as carbonate) based on total weight of the treatment
bath. The lithium
salt, carbon dioxide, and hydroxide described above may be added to the
treatment bath formed
from the treatment composition to achieve a treatment bath being maintained
having a pH and
amounts of lithium and carbonate as described above in more detail in the
context of the
treatment composition according to the present invention. For example,
according to the present
invention, the method of maintaining may comprise adding carbon dioxide to the
treatment bath
formed from the treatment composition in such amount that the pH of the
treatment bath is
maintained below 12.5 and/or adding a hydroxide to the treatment bath in such
amount that the
pH of the treatment bath is maintained above 9.5. In examples, according to
the present
invention, the carbon dioxide may be slowly bubbled into the treatment bath or
may be added by
dropping in dry ice piece by piece. According to the present invention, the pH
may be
periodically or continually monitored (described below) and/or hydroxide may
be added to the
treatment bath as discussed above to maintain pH between 9.5 and 12.5.
[0090] According to the present invention, as described above, following
the supplying
of the carbon dioxide and/or the lithium salt and/or the hydroxide, lithium
(calculated as lithium
cation) may be present in the treatment composition in an amount of at least 5
ppm, such as at
least 50 ppm, such as at least 150 ppm, such as at least 250 ppm, based on
total weight of the
treatment bath, and in some instances, may be present in an amount of no more
than 5,500 ppm,
such as no more than 1,200 ppm, such as no more than 1,000 ppm, such as no
more than 500
ppm, based on total weight of the treatment bath. In some instances, according
to the present
invention, following the supplying of the carbon dioxide and/or the lithium
salt, lithium
(calculated as lithium cation) may be present in the treatment bath in an
amount of 5 ppm to
5,500 ppm based on total weight of the treatment bath, such as 50 ppm to 1,200
ppm, such as
150 ppm to 1,000 ppm, such as 250 ppm to 500 ppm.
[0091] According to the present invention, following the supplying of the
carbon dioxide
and/or the lithium salt and/or the hydroxide, carbonate (calculated as
carbonate) may be present
in the treatment bath in an amount of at least 15 ppm based on total weight of
the treatment bath,
such as at least 50 ppm, such as at least 200 ppm, and in some instances, may
be present in an
amount of no more than 25,000 ppm based on total weight of the treatment bath,
such as no more
than 15,000 ppm, such as no more than 2,400 ppm. In some instances, according
to the present
invention, following the supplying of the carbon dioxide and/or the lithium
salt and/or the
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hydroxide, the carbonate (calculated as carbonate) may be present in the
treatment bath in an
amount of 15 ppm to 25,000 ppm based on total weight of the treatment bath,
such as 50 ppm to
15,000 ppm, such as 200 ppm to 2,400 ppm.
[0092] According to the present invention, following the supplying of the
carbon dioxide
and/or the lithium salt and/or the hydroxide, the treatment bath may have a pH
of at least 9.5,
such as at least 10, such as at least 11, and in some instances, may have a pH
no greater than
12.5, such as no greater than 12, such as no greater than 11.5. According to
the present
invention, following the supplying of the carbon dioxide and/or the lithium
salt and/or the
hydroxide, the treatment bath may have a pH of 9.5 to 12.5, such as 10 to 12,
such as 11 to 11.5.
[0093] According to the present invention, the method of maintaining a
treatment bath
may further comprise adjusting a pH of the treatment bath, such as by adding
any acid and/or
base as is necessary. According to the present invention, the treatment bath
may be maintained
through the inclusion of an acidic material, including water soluble and/or
water dispersible
acids, such as nitric acid, sulfuric acid, and/or phosphoric acid. According
to the present
invention, the pH of the treatment bath may be maintained through the
inclusion of a basic
material, including water soluble and/or water dispersible bases, such as
Group I carbonates,
Group II carbonates, hydroxides, such as sodium hydroxide, potassium
hydroxide, lithium
hydroxide, ammonium hydroxide, ammonia, amines such as triethylamine,
methylethyl amine,
or mixtures thereof
[0094] The method of maintaining a treatment bath of the present invention
may further
comprise monitoring the pH of the treatment bath using a pH meter and probe
appropriate for the
size of the bath formed from the treatment composition comprising lithium
carbonate. An
example of a suitable pH meter and probe includes, but is not limited to, the
Accumet AB15
(available from Fisher Scientific) and a single junction electrode (Ag/AgC1
reference; Fisher
Scientific)
[0095] The method of maintaining a treatment bath of the present invention
may further
comprise monitoring the amount of lithium, carbonate, or lithium carbonate in
the treatment bath
by any method known to those skilled in the art. For example, according to the
present
invention, the method of monitoring lithium may comprise, for example, using
an optical
emission spectrometer or equivalent instrumentation and using a standard
sample with a defined
concentration of lithium (e.g. a standard of known concentration (such as a
500 ppm Li standard
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26
diluted to 5 ppm Li) at a specified wavelength (e.g., 670.784 nm) to calculate
the concentration
of lithium (metal cation) in the treatment bath. The method of maintaining a
treatment bath of
the present invention may further comprise monitoring the amount of carbonate
in the treatment
bath by any method known to those skilled in the art, including for example,
using a manual
titration or an autotitration method.
[0096] It has been unexpectedly discovered that carbon dioxide and/or a
lithium salt and,
optionally a hydroxide, may be used to maintain a treatment bath formed from a
lithium
carbonate containing treatment composition such that the pH and lithium cation
concentration,
and/or lithium cation concentration and carbonate (anion) concentration may be
independently
manipulated or adjusted, depending on bath conditions, compared to maintenance
of a bath with,
for example, lithium carbonate, where pH, lithium concentration, and carbonate
concentration
are all changed upon addition of lithium carbonate to the bath (i.e., there is
no independent
control of each such parameter). For example, carbon dioxide and/or a lithium
salt and,
optionally a hydroxide, may be used to maintain a treatment bath formed from a
lithium
carbonate containing treatment composition such that the treatment bath has a
pH of 9.5 to 12.5,
a lithium concentration of 5 ppm to 5,500 ppm (calculated as lithium cation)
based on total
weight of the treatment bath, and a carbonate concentration of 15 ppm to
25,000 ppm (calculated
as carbonate) based on total weight of the treatment bath.
[0097] As mentioned above, the treatment composition or bath formed
therefrom
comprises an aqueous medium as a carrier. Accordingly, the composition or bath
may be in the
form of a solution or dispersion of the lithium salt in the carrier. According
to the present
invention, the solution or dispersion may be brought into contact with a
substrate to be treated
with the composition or bath 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. According to the invention, the solution
or dispersion when
applied to the substrate may be at a temperature ranging from 40 F (5 C) to
about 160 F (71 C),
such as 60 F (16 C) to 110 F (43 C). For example, the process of contacting
the substrate with
the treatment composition or bath may be carried out at ambient or room
temperature, such as
23 C, if not indicated otherwise. The contact time is often from 1 second to 2
hours, such as 5
minutes to 60 minutes.
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27
[0098] According to the present invention, the thickness of the layer
formed by the
treatment composition may for instance be up to 550 nm, such as 5 nm to 550
nm, such as 10 nm
to 400 nm, such as 25 nm to 250 nm. Thickness of layer formed from the
treatment composition
can be determined using a handful of analytical techniques including, but not
limited to XPS (x-
ray photoelectron spectroscopy) depth profiling or TEM (transmission electron
microscopy).
As used herein, "thickness," when used with respect to a layer formed by the
treatment
composition of the present invention, refers to either (a) a layer formed
above the original
air/substrate interface, (b) a modified layer foimed below the
pretreatment/substrate interface, or
(c) a combination of (a) and (b), as illustrated in Fig. 3. Although modified
layer (b) is shown
extending to the pretreatment/substrate interface in Fig 3, an intervening
layer may be present
between the modified layer (b) and the pretreatment/substrate interface.
Likewise, (c), a
combination of (a) and (b), is not limited to a continuous layer and may
include multiple layers
with intervening layers therebetween, and the measurement of the thickness of
layer (c) may
exclude the intervening layers.
[0099] Suitable substrates that may be used in the present invention
include metal
substrates, metal alloy substrates, and/or substrates that have been
metallized, such as nickel
plated plastic. According to the present invention, the metal or metal alloy
can comprise or be
steel, aluminum, zinc, nickel, and/or magnesium. For example, the steel
substrate could be cold
rolled steel, hot rolled steel, electrogalvanized steel, and/or hot dipped
galvanized steel.
Aluminum alloys of the 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, or 7XXX series as
well
as clad aluminum alloys also may be used as the substrate. Aluminum alloys may
comprise
0.01% by weight copper to 10% by weight copper. Aluminum alloys which are
treated may also
include castings, such as 1XX.X, 2XX.X, 3XX.X, 4XX.X, 5XX.X, 6XX.X, 7XX.X,
8XX.X, or
9XX.X (e.g.: A356.0). Magnesium alloys of the AZ31B, AZ91C, AM60B, or EV31A
series also
may be used as the substrate. The substrate used in the present invention may
also comprise
titanium and/or titanium alloys, zinc and/or zinc alloys, and/or nickel and/or
nickel alloys.
According to the present invention, 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, roof
and/or stringers, rivets, landing gear components, and/or skins used on an
aircraft) and/or a
vehicular frame. As used herein, "vehicle" or variations thereof includes, but
is not limited to,
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28
civilian, commercial and military aircraft, and/or land vehicles such as cars,
motorcycles, and/or
trucks.
[0100] According to the present invention, at least a portion of the
substrate surface may
be cleaned and/or deoxidized and/or otherwise pretreated by any conventional
means known in
the art of cleaning or pretreating a metal substrate prior to contacting at
least a portion of the
substrate surface with a treatment composition or bath described above, in
order to remove
grease, dirt, and/or other extraneous matter. At least a portion of the
surface of the substrate may
be cleaned by physical and/or chemical means, such as mechanically abrading
the surface and/or
cleaning/degreasing the surface with commercially available alkaline or acidic
cleaning agents
that are well known to those skilled in the art. Examples of alkaline cleaners
suitable for use in
the present invention include ChemkleenTM 166t1P, 166 m/c, 177, 490MX, 2010LP,
and Surface
Prep 1 (SP1), Ultrax 32, Ultrax 97, Ultrax 29 and 92D, each of which are
commercially available
from PPG Industries, Inc. (Cleveland, OH), and any of the DFM Series, RECC
1001, and
88X1002 cleaners commercially available from PRC-DeSoto International, Sylmar,
CA), and
Turco 4215-NCLT and Ridolene (commercially available from Henkel Technologies,
Madison
Heights, MI). Such cleaners are often preceded or followed by a water rinse,
such as with tap
water, distilled water, or combinations thereof.
[0101] As mentioned above, according to the present invention, at least a
portion of the
cleaned substrate surface may be deoxidized, mechanically and/or chemically.
As used herein,
the term "deoxidize" means removal of the oxide layer found on the surface of
the substrate in
order to promote uniform deposition of a conversion or pretreatment
composition as well as to
promote the adhesion of the such a composition coating to the substrate
surface. Suitable
deoxidizers will be familiar to those skilled in the art. A typical mechanical
deoxidizer may be
uniform roughening of the substrate surface, such as by using a scouring or
cleaning pad.
Typical chemical deoxidizers include, for example, acid-based deoxidizers such
as phosphoric
acid, nitric acid, fluoroboric acid, sulfuric acid, chromic acid, hydrofluoric
acid, and ammonium
bifluoride, or Amchem 7/17 deoxidizers (available from Henkel Technologies,
Madison Heights,
MI), OAKITE DEOXIDIZER LNC (commercially available from Chemetall), TURCO
DEOXIDIZER 6 (commercially available from Henkel), or combinations thereof.
Often, the
chemical deoxidizer comprises a carrier, often an aqueous medium, so that the
deoxidizer may be
in the form of a solution or dispersion in the carrier, in which case the
solution or dispersion may
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29
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. According to the present
invention, the skilled
artisan will select a temperature range of the solution or dispersion, when
applied to the metal
substrate, based on etch rates, for example, at a temperature ranging from 50
F to 150 F (10 C to
66 C), such as from 70 F to 130 F (21 C to 54 C), such as from 80 F to 120 F
(27 C to 49 C).
The contact time may be from 30 seconds to 20 minutes, such as 1 minute to 15
minutes, such as
90 seconds to 12 minutes, such as 3 minutes to 9 minutes.
[0102] Following the cleaning and/or deoxidizing step(s), the substrate
optionally may be
rinsed with tap water, deionized water, and/or an aqueous solution of rinsing
agents in order to
remove any residue. According to the present invention, the wet substrate
surface may be
pretreated by any method familiar to those skilled in the art of substrate
protection, such an
anodized or treated with a conversion composition, and/or may be treated one
of the treatment
compositions described above, or the substrate may be dried prior to treating
the substrate
surface, such as air dried, for example, by using an air knife, by flashing
off the water by brief
exposure of the substrate to a high temperature, such as 15 C to 100 C, such
as 20 C to 90 C, or
in a heater assembly using, for example, infrared heat, such as for 10 minutes
at 70 C, or by
passing the substrate between squeegee rolls. According to the present
invention, the conversion
composition may comprise, for example, a lanthanide series element, a Group
IBB metal, and/or
a Group IVB metal, and may further comprise a Group IIA metal, a Group VB
metal, a Group
VIB metal, a Group VIIB metal, and/or a Group XII. According to the present
invention, the
lanthanide series element may, for example, comprise cerium, praseodymium,
terbium, or
combinations thereof; the Group HA metal may comprise magnesium; the Group
IIIB metal may
comprise yttrium, scandium, or combinations thereof; the Group IVB metal may
comprise
zirconium, titanium, hafnium, or combinations thereof; the Group VB metal may
comprise
vanadium; the Group VIB metal may comprise trivalent or hexavalent chromium
and/or
molybdenum; the Group VIIB metal may comprise manganese; and the Group XII
metal may
comprise zinc.
[0103] According to the present invention, after the substrate is contacted
with the
treatment composition, a coating composition comprising a film-forming resin
may be deposited
onto at least a portion of the surface of the substrate that has been
contacted with the treatment
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composition. Any suitable technique may be used to deposit such a coating
composition onto the
substrate, including, for example, brushing, dipping, flow coating, spraying
and the like. In
some instances, however, as described in more detail below, such depositing of
a coating
composition may comprise an electrocoating step wherein an electrodepositable
composition is
deposited onto a metal substrate by electrodeposition. In certain other
instances, as described in
more detail below, such depositing of a coating composition comprises a powder
coating step.
In still other instances, the coating composition may be a liquid coating
composition.
[0104] According to the present invention, the coating composition may
comprise a
thermosetting film-forming resin or a thermoplastic film-forming resin. 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. 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. 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.
[0105] As previously indicated, according to the present invention, an
electrodepositable
coating composition comprising a water-dispersible, ionic salt group-
containing film-forming
resin that may be deposited onto the substrate by an electrocoating step
wherein the
electrodepositable coating composition is deposited onto the metal substrate
by
electrodeposition. The ionic salt group-containing film-forming polymer may
comprise a
cationic salt group containing film-forming polymer for use in a cationic
electrodepositable
coating composition. As used herein, the term "cationic salt group-containing
film-forming
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31
polymer" refers to polymers that include at least partially neutralized
cationic groups, such as
sulfonium groups and ammonium groups, that impart a positive charge. The
cationic salt group-
containing film-forming polymer may comprise active hydrogen functional
groups, including,
for example, hydroxyl groups, primary or secondary amine groups, and thiol
groups. Cationic
salt group-containing film-forming polymers that comprise active hydrogen
functional groups
may be referred to as active hydrogen-containing, cationic salt group-
containing film-forming
polymers. Examples of polymers that are suitable for use as the cationic salt
group-containing
film-forming polymer include, but are not limited to, alkyd polymers,
acrylics, polyepoxides,
polyamides, polyurethanes, polyureas, polyethers, and polyesters, among
others. The cationic
salt group-containing film-forming polymer may be present in the cationic
electrodepositable
coating composition in an amount of 40% to 90% by weight, such as 50% to 80%
by weight,
such as 60% to 75% by weight, based on the total weight of the resin solids of
the
electrodepositable coating composition. As used herein, the "resin solids"
include the ionic salt
group-containing film-forming polymer, curing agent, and any additional water-
dispersible non-
pigmented component(s) present in the electrodepositable coating composition.
[01061 Alternatively, the ionic salt group containing film-forming polymer
may comprise
an anionic salt group containing film-forming polymer for use in an anionic
electrodepositable
coating composition. As used herein, the term "anionic salt group containing
film-forming
polymer" refers to an anionic polymer comprising at least partially
neutralized anionic functional
groups, such as carboxylic acid and phosphoric acid groups that impart a
negative charge. The
anionic salt group-containing film-forming polymer may comprise active
hydrogen functional
groups. Anionic salt group-containing film-forming polymers that comprise
active hydrogen
functional groups may be referred to as active hydrogen-containing, anionic
salt group-
containing film-forming polymers. The anionic salt group-containing film-
forming polymer may
comprise base-solubilized, carboxylic acid group-containing film-forming
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 anionic electrodepositable resin comprises an
alkyd-aminoplast
32
vehicle, i.e., a vehicle containing an alkyd resin and an amine-aldehyde
resin. Another suitable
anionic electrodepositable resin composition comprises mixed esters of a
resinous polyol. Other
acid functional polymers may also be used such as phosphatized polyepoxide or
phosphatized
acrylic polymers. Exemplary phosphatized polyepoxides are disclosed in U.S.
Patent
Application Publication No. 2009-0045071 at [0004[40015] and U.S. Patent
Application Ser.
No. 13/232,093 at [0014]-[0040]. The anionic salt group-containing film-
forming polymer may
be present in the anionic electrodepositable coating composition in an amount
50% to 90%, such
as 55% to 80%, such as 60% to 75%, based on the total weight of the resin
solids of the
electrodepositable coating composition.
[0107] The electrodepositable coating composition may further comprise a
curing agent.
The curing agent may react with the reactive groups, such as active hydrogen
groups, of the ionic
salt group-containing film-forming polymer to effectuate cure of the coating
composition to form
a coating. Non-limiting examples of suitable curing agents are at least
partially blocked
polyisocyanates, aminoplast resins and phenoplast resins, such as
phenolformaldehyde
condensates including allyl ether derivatives thereof. The curing agent may be
present in the
cationic electrodepositable coating composition in an amount of 10% to 60% by
weight, such as
20% to 50% by weight, such as 25% to 40% by weight, based on the total weight
of the resin
solids of the electrodepositable coating composition. Alternatively, the
curing agent may be
present in the anionic electrodepositable coating composition in an amount of
10% to 50% by
weight, such as 20% to 45% by weight, such as 25% to 40% by weight, based on
the total weight
of the resin solids of the electrodepositable coating composition.
[0108] The electrodepositable coating composition may further comprise
other optional
ingredients, such as a pigment composition and, if desired, various additives
such as fillers,
plasticizers, anti-oxidants, biocides, UV light absorbers and stabilizers,
hindered amine light
stabilizers, defoamers, fungicides, dispersing aids, flow control agents,
surfactants, wetting
agents, or combinations thereof. The electrodepositable coating composition
may comprise
water and/or one or more organic solvent(s). Water can for example be present
in amounts of
40% to 90% by weight, such as 50% to 75% by weight, based on total weight of
the
electrodepositable coating composition. If used, the organic solvents may
typically be present in
an amount of less than 10% by weight, such as less than 5% by weight, based on
total weight of
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the electrodepositable coating composition. The electrodepositable coating
composition may in
particular be provided in the form of an aqueous dispersion. The total solids
content of the
electrodepositable coating composition may be from 1% to 50% by weight, such
as 5% to 40%
by weight, such as 5% to 20% by weight, based on the total weight of the
electrodepositable
coating composition. As used herein, "total solids" refers to the non-volatile
content of the
electrodepositable coating composition, i.e., materials which will not
volatilize when heated to
110 C for 15 minutes.
[0109] The cationic electrodepositable coating composition may be deposited
upon an
electrically conductive substrate by placing the composition in contact with
an electrically
conductive cathode and an electrically conductive anode, with the surface to
be coated being the
cathode. Alternatively, the anionic electrodepositable coating composition may
be deposited
upon an electrically conductive substrate by placing the composition in
contact with an
electrically conductive cathode and an electrically conductive anode, with the
surface to be
coated being the anode. An adherent film of the electrodepositable coating
composition is
deposited in a substantially continuous manner on the cathode or anode,
respectively, when a
sufficient voltage is impressed between the electrodes. The applied voltage
may be varied and
can be, for example, as low as one volt to as high as several thousand volts,
such as 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.
[0110] Once the cationic or anionic electrodepositable coating composition
is
electrodeposited over at least a portion of the electroconductive substrate,
the coated substrate
may be heated to a temperature and for a time sufficient to cure the
electrodeposited coating on
the substrate. For cationic electrodeposition, the coated substrate may be
heated to a temperature
ranging from 250 F to 450 F (121.1 C to 232.2 C), such as from 275 F to 400 F
(135 C to
204.4 C), such as from 300 F to 360 F (149 C to 180 C). For anionic
electrodeposition, the
coated substrate may be heated to a temperature ranging from 200 F to 450 F
(93 C to 232.2 C),
such as from 275 F to 400 F (135 C to 204.4 C), such as from 300 F to 360 F
(149 C to
180 C), such as 200 F to 210.2 F (93 C to 99 C). The curing time may be
dependent upon the
curing temperature as well as other variables, for example, the film thickness
of the
electrodeposited coating, level and type of catalyst present in the
composition and the like. For
34
example, the curing time can range from 10 minutes to 60 minutes, such as 20
to 40 minutes. The
thickness of the resultant cured electrodeposited coating may range from 2 to
50 microns.
[0111] Alternatively, as mentioned above, according to the present
invention, after the
substrate has been contacted the treatment composition, a powder coating
composition may then
be deposited onto at least a portion of the surface of the substrate that has
been contacted with the
treatment composition. As used herein, "powder coating composition" refers to
a coating
composition which is completely free of water and/or solvent. Accordingly, the
powder coating
composition disclosed herein is not synonymous to waterborne and/or solvent-
borne coating
compositions known in the art. According to the present invention, the powder
coating
composition may comprise (a) a film forming polymer having a reactive
functional group; and (b)
a curing agent that is reactive with the functional group. Examples of powder
coating
compositions that may be used in the present invention include the polyester-
based
ENVIROCRON line of powder coating compositions (commercially available from
PPG
Industries, Inc.) or epoxy-polyester hybrid powder coating compositions.
Alternative examples of
powder coating compositions that may be used in the present invention include
low temperature
cure thermosetting powder coating compositions comprising (a) at least one
tertiary aminourea
compound, at least one tertiary aminourethane compound, or mixtures thereof;
and (b) at least one
film-forming epoxy-containing resin and/or at least one siloxane-containing
resin (such as those
described in US Patent No. 7,470,752, assigned to PPG Industries, Inc.);
curable powder coating
compositions generally comprising (a) at least one tertiary aminourea
compound, at least one
tertiary aminourethane compound, or mixtures thereof, and (b) at least one
film-forming epoxy-
containing resin and/or at least one siloxane-containing resin (such as those
described in US
Patent No. 7,432,333, assigned to PPG Industries, Inc.); and those ccomprising
a solid particulate
mixture of a reactive group-containing polymer having a Tg of at least 30 C
(such as those
described in US Patent No. 6,797,387, assigned to PPG Industries, Inc.).
[0112] After deposition of the powder coating composition, 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 150 C to 200 C, such as from 170 C to 190 C,
for a period of
time ranging from 10 to 20 minutes. According to the invention, the thickness
of the resultant
film is from 50 microns to 125 microns.
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35
101131 As
mentioned above, according to the present invention, the coating composition
may be a liquid coating composition. As used herein, "liquid coating
composition" refers to a
coating composition which contains a portion of water and/or solvent.
Accordingly, the liquid
coating composition disclosed herein is synonymous to waterborne and/or
solventborne coating
compositions known in the art. According to the present invention, the liquid
coating
composition may comprise, for example, (a) a film forming polymer having a
reactive functional
group; and (b) a curing agent that is reactive with the functional group. In
other examples, the
liquid coating may contain a film forming polymer that may react with oxygen
in the air or
coalesce into a film with the evaporation of water and/or solvents. These film
forming
mechanisms may require or be accelerated by the application of heat or some
type of radiation
such as Ultraviolet or Infrared. Examples of liquid coating compositions that
may be used in the
present invention include the SPEC ____________________________________
IRACRONS line of solventbased coating compositions, the
AQUACRON line of waterbased coating compositions, and the RAYCRON line of UV
cured coatings (all commercially available from PPG Industries, Inc.).
Suitable film forming
polymers that may be used in the liquid coating composition of the present
invention may
comprise a (poly)ester, an alkyd, a (poly)urethane, an isocyanurate, a
(poly)urea, a (poly)epoxy,
an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a
(poly)amide, (poly)vinyl
chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane, or
combinations thereof
101141
According to the present invention, the substrate that has been contacted with
the
treatment composition described herein may also be contacted with a primer
composition and/or a
topcoat composition. The primer coat may be, for examples, chromate-based
primers and
advanced performance topcoats. According to the present invention, the primer
coat can be a
conventional chromate based primer coat, such as those available from PPG
Industries, Inc.
(product code 44GN072), or a chrome-free primer such as those available from
PPG
(DESOPRIME CA7502, DESOPRIME CA7521, Deft 02GN083, Deft 02GN084). Alternately,
the primer coat can be a chromate-free primer coat, such as the coating
compositions described in
U.S. patent application Ser. No. 10/758,973, titled "CORROSION RESISTANT
COATINGS
CONTAINING CARBON", and U.S. patent application Ser. Nos. 10/758,972, and
10/758,972,
both titled "CORROSION RESISTANT COATINGS", and other chrome-free primers that
are
CA 3031758 2020-05-28
36
known in the art, and which can pass the military requirement of MIL-PRF-85582
Class N or
MIL-PRP-23377 Class N may also be used with the current invention.
[0115] As mentioned above, the substrate of the present invention also
may comprise a
topcoat. As used herein, the term "topcoat" refers to a mixture of binder(s)
which can be an
organic or inorganic based polymer or a blend of polymers, typically at least
one pigment, can
optionally contain at least one solvent or mixture of solvents, and can
optionally contain at least
one curing agent. A topcoat is typically the coating layer in a single or
multi-layer coating system
whose outer surface is exposed to the atmosphere or environment, and its inner
surface is in
contact with another coating layer or polymeric substrate. Examples of
suitable topcoats include
those conforming to MIL-PRF-85285D, such as those available from PPG (Deft
03W127A and
Deft 03GY292). According to the present invention, the topcoat may be an
advanced performance
topcoat, such as those available from PPG (Defthane ELT.TM. 99GY001 and
99W009).
However, other topcoats and advanced performance topcoats can be used in the
present invention
as will be understood by those of skill in the art with reference to this
disclosure.
[0116] According to the present invention, the metal substrate also may
comprise a
self-priming topcoat, or an enhanced self-priming topcoat. The term "self-
priming topcoat", also
referred to as a "direct to substrate" or "direct to metal" coating, refers to
a mixture of a binder(s),
which can be an organic or inorganic based polymer or blend of polymers,
typically at least one
pigment, can optionally contain at least one solvent or mixture of solvents,
and can optionally
contain at least one curing agent. The term "enhanced self-priming topcoat",
also referred to as
an "enhanced direct to substrate coating" refers to a mixture of
functionalizeid fluorinated
binders, such as a fluoroethylene-alkyl vinyl ether in whole or in part with
other binder(s), which
can be an organic or inorganic based polymer or blend of polymers, typically
at least one
pigment, can optionally contain at least one solvent or mixture of solvents,
and can optionally
contain at least one curing agent. Examples of self-priming topcoats include
those that conform
to TT-P-2756A. Examples of self-priming topcoats include those available from
PPG (03W169
and 03GY369), and examples of enhanced self-priming topcoats include Defthane
ELTTm/ESPT and product code number 97GY121, available from PPG. However, other
self-priming topcoats and enhanced self-priming topcoats can be used in the
coating system
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according to the present invention as will be understood by those of skill in
the art with reference
to this disclosure.
[0117] According to the present invention, the self-priming topcoat and
enhanced self-
priming topcoat may be applied directly to the sealed substrate. The self-
priming topcoat and
enhanced self-priming topcoat can optionally be applied to an organic or
inorganic polymeric
coating, such as a primer or paint film. The self-priming topcoat layer and
enhanced self-priming
topcoat is typically the coating layer in a single or multi-layer coating
system where the outer
surface of the coating is exposed to the atmosphere or environment, and the
inner surface of the
coating is typically in contact with the substrate or optional polymer coating
or primer.
[0118] According to the present invention, the topcoat, self-priming
topcoat, and
enhanced self-priming topcoat can be applied to the sealed substrate, in
either a wet or "not fully
cured" condition that dries or cures over time, that is, solvent evaporates
and/or there is a
chemical reaction. The coatings can dry or cure either naturally or by
accelerated means for
example, an ultraviolet light cured system to foim a film or "cured" paint.
The coatings can also
be applied in a semi or fully cured state, such as an adhesive.
[0119] In addition, a colorant and, if desired, various additives such as
surfactants,
wetting agents or catalyst can be included in the coating composition
(electrodepositable,
powder, or liquid). As used herein, the term "colorant" means any substance
that imparts color
and/or other opacity and/or other visual effect to the composition. 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. 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.
ASPECTS
[0120] In view of the foregoing the present application thus relates in
particular, without
being limited thereto, to the following Aspects 1 to 24:
[0121] 1. A composition comprising carbon dioxide and a lithium cation,
in an
aqueous medium.
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[0122] 2. The composition according to Aspect 1, wherein the carbon
dioxide
comprises a gas, a solid, or combinations thereof
[0123] 3. The composition according to any one of Aspects 1 or 2,
wherein the
lithium cation is present in an amount of 5 ppm to 5500 ppm (calculated as
lithium cation) based
on total weight of the treatment composition.
[0124] 4. The composition according to any one of the preceding Aspects,
wherein
the pH is 9.5 to 12.5.
[0125] 5. The composition according to any one of the preceding Aspects,
further
comprising a hydroxide.
[0126] 6. The composition according to any one of the preceding Aspects,
wherein
the carbonate is present in an amount of 15 ppm to 25,000 ppm (calculated as
carbonate) based
on total weight of the treatment composition.
[0127] 7. A method of making a treatment composition comprising:
[0128] combining a lithium cation and carbon dioxide in an aqueous
medium to
form the treatment composition in situ, wherein the treatment composition
comprises comprising
lithium in an amount of 5 ppm to 5,500 ppm (calculated as lithium cation)
based on total weight
of the treatment composition and carbonate in an amount of 15 ppm to 25,000
ppm (calculated as
carbonate) based on total weight of the treatment composition.
[0129] 8. The method of making a treatment composition according to
Aspect 7,
wherein the lithium cation is present as lithium carbonate, lithium hydroxide,
or a combination
thereof.
[0130] 9. The method of making a treatment composition according to any
one of
Aspects 7 or 8, wherein the carbon dioxide is supplied to the aqueous medium
as a gas, a solid,
or a combination thereof.
[0131] 10. The method of making a treatment composition according to any
one of
Aspects 7 to 9, comprising adding a hydroxide to the aqueous medium.
[0132] 11. The method of making a treatment composition according to
Aspect 10,
wherein the hydroxide comprises lithium hydroxide, sodium hydroxide, potassium
hydroxide, or
a combination thereof.
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[0133] 12. The method of making a treatment composition according to
any one of
Aspects 7 to 11, wherein the method comprises adjusting the pH of the
treatment composition to
from 9.5 to 12.5.
[0134] 13. A treatment composition obtained according to the method
of any one of
Aspects 7 to 12.
[0135] 14. A method for maintaining a treatment bath formed from a
treatment
composition comprising lithium carbonate, the method comprising:
[0136] supplying during and/or after treatment of a substrate with
the bath at least
one of carbon dioxide and a lithium salt to the bath in an amount sufficient
to maintain the pH of
the bath at 9.5 to 12.5, lithium in an amount of 5 ppm to 5,500 ppm
(calculated as lithium cation)
based on total weight of the treatment bath, and carbonate in an amount of 15
ppm to 25,000
ppm (calculated as carbonate) based on total weight of the treatment bath.
[0137] 15. The method for maintaining a treatment bath according to
Aspect 14,
wherein the lithium salt comprises lithium carbonate, lithium hydroxide, or a
combination
thereof.
[0138] 16. The method for maintaining a treatment bath according to
any one of
Aspects 14 or 15, wherein the carbon dioxide is supplied to the bath as a gas,
a solid, or a
combination thereof.
[0139] 17. The method for maintaining a treatment bath according to
any one of
Aspects 14 to 16, comprising supplying a hydroxide to the bath.
[0140] 18. The method for maintaining a treatment bath according to
Aspect 17,
wherein the hydroxide comprises lithium hydroxide, sodium hydroxide, potassium
hydroxide, or
a combination thereof.
[0141] 19. The method for maintaining a treatment bath according to
any one of
Aspects 14 to 18, further comprising monitoring pH of the treatment bath,
amount of carbonate
in the treatment bath, amount of lithium in the treatment bath, or a
combination thereof.
[0142] 20. A substrate treated with the treatment composition of any
one of Aspects 1
to 6 or 13 or with the treatment bath maintained according to the method of
any one of Aspects
14 to 19.
[0143] 21. A system for maintaining a treatment bath formed from a
treatment
composition comprising lithium carbonate, the system comprising:
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[0144] a lithium salt source; and/or
[0145] a carbon dioxide source; and
[0146] optionally, a hydroxide source.
[0147] 22. The system for maintaining a treatment bath according to
Aspect 21,
wherein the lithium salt source comprises lithium carbonate, lithium
hydroxide, or a combination
thereof.
[0148] 23. The system for maintaining a treatment bath according to any
one of
Aspects 21 or 22, wherein the carbon dioxide source comprises carbon dioxide
as a gas, a solid,
or a combination thereof.
[0149] 24. The system for maintaining a treatment bath according to any
one of
Aspects 21 to 23, wherein the system includes a hydroxide source comprising
lithium hydroxide,
sodium hydroxide, potassium hydroxide, or a combination thereof
[0150] Whereas particular features of the present invention have been
described above
for purposes of illustration, it will be evident to those skilled in the art
that numerous variations
of the details of the treatment composition and bath formed therefrom and
methods of preparing
or maintaining the same disclosed herein may be made without departing from
the scope in the
appended claims.
[0151] Illustrating the invention are the following examples that are not
to be considered
as limiting the invention to their details. All parts and percentages in the
examples, as well as
throughout the specification, are by weight unless otherwise indicated.
EXAMPLES
Table 2 ¨ Materials
lithium carbonate, 98% Alfa Aesar
lithium hydroxide mono hydrate, 98% min Alfa Aesar
carbon dioxide gas Air Gas
sodium hydroxide pellets, 98% Alfa Aesar
sodium phosphate dodecahydrate, 97% Alfa Aesar
polyvinylpyrrolidone (PVP), 8000 m.w. Alfa Aesar
Allantoin, 98% Alfa Aesar
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2,5-dimercapto-1,3,4-thiadiazole, 98% Acros Organics
Carbowet GA100, 100% Air Products
cerium nitrate solution (65.37% Ce(NO3)3 = 61-120) ProChem Inc.
yttrium nitrate solution (72.45% Y(NO3)3 = 6H20) ProChem Inc.
cerium chloride solution (32.2% as Ce02*) ProChem Inc.
hydrogen peroxide solution (30% H202) Alfa Aesar
* per supplier's certificate of analysis
Table 3 - Cleaner/Deoxidizer Composition (Example A)
WEIGHT (g)
sodium hydroxide pellets, 98% 0.016
sodium phosphate dodecahydrate, 97% 0.063
polyvinylpyrrolidone (PVP), 8000 mw. 0.002
Allantoin, 98% 0.003
2,5-dimercapto-1,3,4-thiadiazole( DMTD), 98% 0.100
Carbowet GA100 0.410
deionized water 98.7
[0152] The ingredients and their relative amounts used to prepare
cleaner/deoxidizer
composition Example A are provided in Table 3. Sodium hydroxide and sodium
phosphate were
completely dissolved in deionized water under mild mechanical agitation using
a stir plate
(VWR, 7x7 CER HOT/STIR). Next, once the sodium hydroxide and sodium phosphate
were
completely dissolved, the PVP was stirred in until dissolved, and then
Allantoin was added and
stirred until dissolved, and then the DMTD was added and stirred until
dissolved. After the
DMTD was completely dissolved, Carbowet GA100 was stirred in under mild
mechanical
agitation as above
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Table 4 - Conversion Composition (Example B)
Mass (g)
Yttrium Nitrate Solution 12.48
Cerium Nitrate Solution 10.40
Cerium Chloride Solution 0.04
Hydrogen Peroxide Solution 1.04
Deionized Water 1953
[01531 The ingredients used to prepare a solution of conversion coating
composition
Example B and their amounts are provided in Table 4. Cerium nitrate, yttrium
nitrate and cerium
chloride solutions were weighed into individual cups. Then using 500 grams of
deionized water,
the solutions were transferred to a vessel containing 1,000 grams of deionized
water under mild
agitation. The remaining 453 grams of water was added and the solution was
stirred for 10
minutes to ensure uniformity before the hydrogen peroxide was added. The final
solution was
stirred for a minimum of 30 minutes before use.
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Table 5 - Sealing Compositions (Examples C-0)
LiCO3 LiOH 5%
(98% (98% Li LiOH Deionized
CO2 pH
purity) purity) (moles) Solutio Water (g)
(g) (g) n (g)
Ex. C 3.06 0.081 --- 1996.94 11.52
Ex. D --- 1.99 0.081 --- --- 1998.01 12.69
Ex. E --- --- --- Bubbled --- --- 11.42
Ex. F --- --- Bubbled --- --- 10.54
. . . . .
Ex. G --- ---
Bubbled --- --- 9.47
Ex. H --- --- --- --- 15.3 --- 10.47
Ex. I --- --- --- --- 15.5 --- 11.48
Ex. J --- --- --- --- 23.2 --- 12.47
Ex. K 3.06 --- 0.081 --- --- 1996.94 11.14
Ex. L --- 1.99 0.081 --- --- 1998.01 12.17
Ex. M --- --- --- Bubbled --- --- 11.37
Ex. N --- ---
Bubbled --- --- 9.50
Ex. 0 --- --- --- --- 15.54 --- 11.37
[0154] In preparing the sealing compositions, pH for each Example C-J was
measured
using a pH meter (Accumet AB15, Fisher Scientific) and a single junction
electrode (Ag/AgC1
reference; Fisher Scientific) and the pH for each Example K-0 was measured
using a pH meter
(Mettler Toledo, Seven2Go, model S2) and a double open junction electrode
(Mettler Toledo,
Xerolyt polymer reference).
[0155] Sealing composition Example C and Example K each were prepared using
the
ingredients shown in Table 5 by dissolving lithium carbonate into deionized
water under mild
agitation using the stir plate as described above (VWR, 7x7 CER HOT/STIR).
Example C had a
final pH of 11.52. Example C was used to treat panels in Comparative Example 1
(described
below). Example K had a final pH of 11.14. Example K was used to treat panels
in
Comparative Example 9 (described below).
[0156] Sealing composition Example D and Example L each were prepared using
the
ingredients shown in Table 5 by dissolving lithium hydroxide into deionized
water under mild
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agitation using the stir plate as described above. Example D had a final pH
value of 12.69.
Example D was used to treat panels in Comparative Example 2 (described below).
Example L
had a final pH value of 12.17. Example L was used to treat panels in
Comparative Example 10
(described below).
[0157] Following use of the bath containing the composition of Example D to
treat
panels according to Comparative Example 2, sealing composition Example E was
prepared by
bubbling carbon dioxide gas into the bath containing the composition of
Example D until a final
pH value of 11.42 was obtained. See Figure 1 and Table 5. Example E was used
to treat panels
in Example 3 (described below).
[0158] Following use of the bath containing the composition of Example E to
treat panels
according to Example 3, sealing composition Example F was prepared by bubbling
additional
carbon dioxide gas into the composition of Example E until a final pH value of
10.54 was
obtained. See Figure 1 and Table 5. Example F was used to treat panels in
Example 4
(described below).
[0159] Following use of the bath containing the composition of Example F to
treat panels
according to Example 4, sealing composition Example G was prepared by bubbling
additional
carbon dioxide gas into the composition of Example F until a final pH value of
9.47 was
obtained. See Figure 1 and Table 5. Example G was used to treat panels in
Example 5
(described below).
[0160] Following the use of the bath containing the composition of Example
G to treat
panels according to Example 5, sealing composition Example H was prepared by
adding 5%
lithium hydroxide solution into the composition of Example G until a final pH
value of 10.47
was obtained. See Figure 1 and Table 5. Example H was used to treat panels in
Example 6
(described below).
[0161] Following the use of the bath containing the composition of Example
H according
to Example 6, sealing composition Example I was prepared by adding 5% lithium
hydroxide
solution into the composition of Example H until a final pH value of 11.48 was
obtained. See
Figure 1 and Table 5. Example I was used to treat panels in Example 7
(described below).
[0162] Following the use of the bath containing the composition of Example
I according
to Example 7, sealing composition Example J was prepared by adding 5% lithium
hydroxide
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solution into the composition of Example I until a final pH value of 12.47 was
obtained. See
Figure 1 and Table 5. Example J was used to treat panels in Example 8
(described below).
[0163] Following use of the bath containing the composition of Example L to
treat panels
according to Comparative Example 10, sealing composition Example M was
prepared by
bubbling carbon dioxide gas into the bath containing the composition of
Example L until a final
pH value of 11.37 was obtained. See Figure 2 and Table S. Example M was used
to treat panels
in Example 11 (described below).
[0164] Following use of the bath containing the composition of Example M to
treat
panels according to Example 11, sealing composition Example N was prepared by
bubbling
additional carbon dioxide gas into the composition of Example M until a final
pH value of 9.5
was obtained. See Figure 2 and Table 5. Example N was used to treat panels in
Example 12
(described below).
[0165] Following the use of the bath containing the composition of Example
N according
to Example 12, sealing composition Example 0 was prepared by adding 5% lithium
hydroxide
solution into the composition of Example N until a final pH value of 11.37 was
obtained. See
Figure 2 and Table 5. Example 0 was used to treat panels in Example 13
(described below).
Panel Preparation
Comparative Example 1
[0166] Aluminum 2024T3 bare substrate (obtained from Priority Metals,
Orange County,
CA) measuring 3" x 5" x 0.032" was hand-wiped with methyl ethyl ketone and a
disposable
cloth and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner-
deoxidizer composition Example A for 3.5 minutes at ambient temperature with
intermittent
agitation. The panel was then immersed in two subsequent deionized water
rinses for two
minutes each, both at ambient temperature with intermittent agitation. After
the second rinse, the
panel was rinsed with a cascading deionized water rinse for 10 seconds. The
panel was then
immersed in the conversion composition Example B for 5 minutes at ambient
temperature
without agitation. Next, the panel was rinsed by immersion in deionized water
for 2 minutes at
ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example C
for 2 minutes
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at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Comparative Example 2
[0167] Aluminum 2024T3 bare substrate (obtained from Priority Metals,
Orange County,
CA) measuring 3" x 5" x 0.032" was hand-wiped with methyl ethyl ketone and a
disposable
cloth and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner-
deoxidizer composition Example A for 3.5 minutes at ambient temperature with
intermittent
agitation. The panel was then immersed in two subsequent deionized water
rinses for two
minutes each, both at ambient temperature with intermittent agitation. After
the second rinse, the
panel was rinsed with a cascading deionized water rinse for 10 seconds The
panel was then
immersed in the conversion composition Example B for 5 minutes at ambient
temperature and
without agitation. Next, the panel was rinsed by immersion in deionized water
for 2 minutes at
ambient temperature with intettnittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example D
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Example 3
[0168] After panels from Comparative Example 2 were processed through the
seal
solution of Example D, the pH of the bath was adjusted by bubbling carbon
dioxide gas into the
bath until the pH was 11.42 (i.e., to form Example E as described above). See
Figure 1.
[0169] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion in deionized
water for 2 minutes
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at ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example E
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Example 4
[0170] After panels were processed through the seal solution of Example E,
the pH of the
bath was adjusted by bubbling carbon dioxide gas into the bath until the pH
was 10.54 (i.e., to
form Example F as described above). See Figure 1.
[0171] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion in deionized
water for 2 minutes
at ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example F
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Example 5
[0172] After panels were processed through the seal solution of Example F,
the pH of the
bath was adjusted by bubbling carbon dioxide gas into the bath until the pH
was 9.47 (i.e., to
form Example G as described above). See Figure 1.
[0173] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
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intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion in deionized
water for 2 minutes
at ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example G
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Example 6
[0174] After panels were processed through the seal solution of Example G,
the pH of
the bath was adjusted using lithium hydroxide solution as described above
(i.e., to form Example
H as described above). See Figure 1.
[0175] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion rinse in
deionized water for 2
minutes at ambient temperature with intermittent agitation followed by a 10
second cascading
deionized water rinse. The panel was then immersed in the sealing composition
Example H for
2 minutes at ambient temperature with intermittent agitation. The panel was
air dried at ambient
conditions overnight before corrosion testing as described below.
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Example 7
[0176] After panels were processed through the seal solution of Example H,
the pH of
the bath was adjusted using lithium hydroxide solution as described above
(i.e., to form Example
I as described above). See Figure 1.
[0177] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion rinse in
deionized water for 2
minutes at ambient temperature with intermittent agitation followed by a 10
second cascading
deionized water rinse. The panel was then immersed in the sealing composition
Example I for 2
minutes at ambient temperature with intermittent agitation. The panel was air
dried at ambient
conditions overnight before corrosion testing as described below.
Example 8
[0178] After panels were processed through the seal solution of Example I,
the pH of the
bath was adjusted using lithium hydroxide solution as described above (i.e.,
to form Example I as
described above). See Figure 1.
[0179] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel received a cascading deionized water rinse for 10 seconds.
The panel was then
immersed in the conversion composition Example B for 5 minutes at ambient
temperature and
without agitation. Next, the panel was rinsed by immersion in deionized water
for 2 minutes at
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ambient temperature with inteimittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example J
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Comparative Example 9
[0180] Aluminum 2024T3 bare substrate (obtained from Priority Metals,
Orange County,
CA) measuring 3" x 5" x 0.032" was hand-wiped with methyl ethyl ketone and a
disposable
cloth and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner-
deoxidizer composition Example A for 3.5 minutes at ambient temperature with
intermittent
agitation The panel was then immersed in two subsequent deionized water rinses
for two
minutes each, both at ambient temperature with intermittent agitation. After
the second rinse, the
panel was rinsed with a cascading deionized water rinse for 10 seconds. The
panel was then
immersed in the conversion composition Example B for 5 minutes at ambient
temperature
without agitation. Next, the panel was rinsed by immersion in deionized water
for 2 minutes at
ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example K
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Comparative Example 10
[0181] Aluminum 2024T3 bare substrate (obtained from Priority Metals,
Orange County,
CA) measuring 3" x 5" x 0.032" was hand-wiped with methyl ethyl ketone and a
disposable
cloth and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner-
deoxidizer composition Example A for 3.5 minutes at ambient temperature with
intermittent
agitation The panel was then immersed in two subsequent deionized water rinses
for two
minutes each, both at ambient temperature with intermittent agitation. After
the second rinse, the
panel was rinsed with a cascading deionized water rinse for 10 seconds. The
panel was then
immersed in the conversion composition Example B for 5 minutes at ambient
temperature and
without agitation. Next, the panel was rinsed by immersion in deionized water
for 2 minutes at
ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
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51
water rinse. The panel was then immersed in the sealing composition Example L
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Example 11
[0182] After panels from Comparative Example 10 were processed through the
seal
solution of Example L, the pH of the bath was adjusted by bubbling carbon
dioxide gas into the
bath until the pH was 11.37 (i.e., to form Example M as described above). See
Figure 2.
[0183] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion in deionized
water for 2 minutes
at ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example M
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Example 12
[0184] After panels were processed through the seal solution of Example M,
the pH of
the bath was adjusted by bubbling carbon dioxide gas into the bath until the
pH was 950 (i.e., to
form Example N as described above). See Figure 2
[0185] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
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52
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion in deionized
water for 2 minutes
at ambient temperature with intermittent agitation followed by a 10 second
cascading deionized
water rinse. The panel was then immersed in the sealing composition Example N
for 2 minutes
at ambient temperature with intermittent agitation. The panel was air dried at
ambient conditions
overnight before corrosion testing as described below.
Example 13
[0186] After panels were processed through the seal solution of Example N,
the pH of
the bath was adjusted using lithium hydroxide solution as described above
(i.e., to form Example
0 as described above). See Figure 2.
[0187] Next, additional aluminum 2024T3 bare substrate measuring 3" x 5" x
0.032"
(Priority Metals, Orange County, CA) was hand-wiped with methyl ethyl ketone
and a
disposable cloth and allowed to air dry prior to chemical cleaning. The panel
was immersed in
the cleaner-deoxidizer composition Example A for 3.5 minutes at ambient
temperature with
intermittent agitation. The panel was then immersed in two subsequent
deionized water rinses
for two minutes each, both at ambient temperature with intermittent agitation.
After the second
rinse, the panel was rinsed with a cascading deionized water rinse for 10
seconds. The panel was
then immersed in the conversion composition Example B for 5 minutes at ambient
temperature
and without agitation. Next, the panel was rinsed by immersion rinse in
deionized water for 2
minutes at ambient temperature with intermittent agitation followed by a 10
second cascading
deionized water rinse. The panel was then immersed in the sealing composition
Example 0 for
2 minutes at ambient temperature with intermittent agitation. The panel was
air dried at ambient
conditions overnight before corrosion testing as described below.
Corrosion Testing
[0188] Panels from Examples 1-8 were placed in a 7-day exposure in a
neutral salt spray
cabinet operated according to ASTM B117. Corrosion performance was evaluated
by counting
the number of pits visible to the naked eye on the panels following the 7-day
exposure. Pits that
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53
were pre-existing to testing, on an edge, or resulting from a scratch were
excluded from the
counts. The corrosion performance data are reported in Table 6.
[0189] Baths from Examples 9-13 were evaluated for lithium carbonate
content using an
autotitration method (Metrohm 799 GPT Titrino, Software by Tiamo 2.3). %
Li2CO3 and % CO3
were calculated using the following formulae:
% Li2CO3= [(Volume at EP3 - Volume at EP2 ) x MW Li2CO3 x HC1 conc. x 1001 /
(SW x 1000) and
% CO3= [(Volume at EP3 - Volume at EP2 ) x MW CO3 x HC1 conc. x 1001 / (SW x
1000),
where EP2 is the second endpoint and EP3 is the third endpoint. HC1
concentration (N) was 0.1012.
[0190] These values were used to calculate the amount of carbonate in baths
containing
the sealing compositions of Examples 9-13, as reported in Table 6.
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Table 6. Corrosion Results and Carbonate Measurements
Pits/
Sample HC1 HC1 (1/0 % Avg Avg
Corr
Example 1)11 . Weight (mL) (mL) Li2C CO3
CO3
osion CO3
Sites (g) EP2* EP3** 03 (%) (PPm)
Example 1 --- 11.52 5 --- --- --- --- ---
---
(Comparative)
Example 2 --- --- --- --- --- --- ---
12.69 100+
(Comparative)
Example 3 11.42 6 --- --- --- --- --- --- ---
Example 4 10.54 10 --- --- --- --- --- --- ---
Example 5 9.47 18 --- --- --- --- --- --- ---
Example 6 10.47 14 --- --- --- --- --- --- ---
Example 7 11.48 3 --- --- --- --- --- --- ---
Example 8 12.47 39 --- --- --- --- --- --- ---
Example 9 1114. 10.0781 2.0809 4.1378
0.153 0.124 0.125 1248
---
(Comparative) 10.0877 2.0735 4.1618 0.155 0.126
Example 10 12 . 17 10.1993 4.0802 4.1572
0.006 0.005 0.005 48
---
(Comparative) 10.3639 4.1290 4.2158 0.006 0.005
10.1814 2.2263 4.1518 0.141 0.115 0.115 1147
Example 11 11.37 ---
10.3984 2.2655 4.2272 0.141 0.115
10.0817 0.8203 4.0719 0.241 0.196 0.196 1960
Example 12 9.50 ---
10.8563 0.8730 4.3789 0.241 0.196
10.4032 3.6583 7.0788 0.246 0.200 0.200 2002
Example 13 11.37 ---
10.3221 3.5725 6.9857 0.247 0.201
[0191] Comparative Examples 1 and 9 illustrate treatment baths containing a
composition made from lithium carbonate. These Examples illustrate the pH of
such a treatment
bath containing a composition made from lithium carbonate, and Comparative
Example 9 also
demonstrated the amount of lithium carbonate and carbonate in the treatment
bath. The pH of
the treatment bath of Comparative Example 1 was 11.52 and there were 5 pits on
the treated
panel following salt spray exposure. The treatment bath of Comparative Example
9 had a pH of
11.14, and contained 0.154% lithium carbonate and 1248 ppm carbonate.
[0192] Comparative Example 2 and 10 illustrated a treatment bath containing
a
composition made from lithium hydroxide. Notably, the amount of lithium in
Example D (used
to make Comparative Example 2) was the same as the amount of lithium in
Example C (used to
make Comparative Example 1) (0.081 mol lithium). The pH of the treatment bath
of
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Comparative Example 2 was 12.69 and there were more than 100 pits on the
treated panel
following salt spray exposure. The treatment bath of Comparative Example 10
had a pH of
12.17 and contained only 48 ppm of carbonate. While not wishing to be bound by
theory, it is
hypothesized that the carbonate present in the treatment bath of Comparative
Example 10 is the
result of the conversion of CO2 to CO3. These data demonstrate that lithium in
the absence of
sufficient carbonate does not provide corrosion protection for a metal
substrate treated with the
treatment bath.
[0193] Example 3 demonstrated that by bubbling CO2 into the treatment bath,
pH can be
lowered to a range comparable to Comparative Example 1, while reducing the
number of pits on
the treated panel to 6. As demonstrated by Example 11, CO? also can be used to
form lithium
carbonate in a bath that had only a trace amount of lithium carbonate prior to
addition of CO2
[0194] Examples 4, 5, and 12 also demonstrated that bubbling additional
quantities of
CO2 into the treatment bath lowers pH, but these Examples show a trend of
increasingly more
corrosion pits on the treated panels after salt spray exposure as pH of the
treatment bath is
lowered (i.e., the panels treated in Examples 4 and 5 had 10 and 18 pits at pH
10.54 and 9.47,
respectively) compared to Comparative Example 1, which had a pH of 11.52 and 5
pits on the
treated panel and compared to Example 3, which had a pH of 11.42 and 6 pits on
the treated
panel. As demonstrated by Example 12, there was 1960 ppm of carbonate in the
treatment bath.
These data demonstrate that in a bath that contains lithium carbonate, pH is
critical to corrosion
performance.
[0195] Examples 6, 7, and 13 demonstrated that the addition of LiOH to
increase pH to
10.47 and 11.48, respectively, resulted in improved corrosion performance, as
panels treated in
Example 6 had 14 pits, while those treated in Example 7 had 3 pits.
[0196] Example 8 demonstrated that raising the pH to 12.5 impaired
corrosion
performance even though the carbonate level was sufficient, with the treated
panel having 39
corrosion sites, an improvement over Comparative Example 2, which did not
include any lithium
carbonate and which had more than 100 pits and no lithium carbonate added to
the bath.
[0197] The Examples demonstrate the interaction of pH, lithium
concentration, and
carbonate concentration with respect to corrosion resistance.
