U.S. patent application number 16/324977 was filed with the patent office on 2019-06-13 for preparation of treatment composition and system and method of maintaining a treatment bath formed therefrom.
This patent application is currently assigned to PRC-DeSoto International, Inc.. The applicant listed for this patent is PRC-DeSoto International, Inc.. Invention is credited to Michael A. Mayo, Eric L. Morris, Michael J. Pawlik, Gordon L. Post, Edward F. Rakiewicz.
Application Number | 20190177855 16/324977 |
Document ID | / |
Family ID | 59762041 |
Filed Date | 2019-06-13 |
United States Patent
Application |
20190177855 |
Kind Code |
A1 |
Post; Gordon L. ; et
al. |
June 13, 2019 |
Preparation of Treatment Composition and System and Method of
Maintaining a Treatment Bath Formed Therefrom
Abstract
Disclosed is a method of making a treatment composition. A
lithium cation and carbon dioxide are combined in an aqueous medium
to form the treatment composition comprising lithium carbonate in
situ. Also disclosed is a system and method for maintaining a
treatment bath formed from a treatment composition comprising
lithium carbonate. Carbon dioxide and/or a lithium salt are
supplied 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) and carbonate in an amount
of 15 ppm to 25,000 ppm (calculated as carbonate) based on total
weight of the treatment bath. Substrates treated with the
composition, system and method also are disclosed.
Inventors: |
Post; Gordon L.;
(Pittsburgh, PA) ; Pawlik; Michael J.; (Glenshaw,
PA) ; Morris; Eric L.; (Murrieta, CA) ;
Rakiewicz; Edward F.; (Gibsonia, PA) ; Mayo; Michael
A.; (Pittsburgh, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRC-DeSoto International, Inc. |
Sylmar |
CA |
US |
|
|
Assignee: |
PRC-DeSoto International,
Inc.
Sylmar
CA
|
Family ID: |
59762041 |
Appl. No.: |
16/324977 |
Filed: |
August 14, 2017 |
PCT Filed: |
August 14, 2017 |
PCT NO: |
PCT/US2017/046705 |
371 Date: |
February 12, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62374188 |
Aug 12, 2016 |
|
|
|
62526382 |
Jun 29, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 22/66 20130101;
C23C 22/86 20130101; C23C 22/83 20130101; C01D 15/00 20130101 |
International
Class: |
C23C 22/66 20060101
C23C022/66; C23C 22/83 20060101 C23C022/83; C23C 22/86 20060101
C23C022/86 |
Claims
1. A composition comprising lithium carbonate, wherein the lithium
carbonate is formed in situ by reacting a carbon dioxide source and
a lithium cation in an aqueous medium.
2. The composition of claim 1, wherein the carbon dioxide source
comprises a gas, a solid, or combinations thereof.
3. The composition of claim 1, 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 composition.
4. The composition of claim 1, wherein the pH is 9.5 to 12.5.
5. The composition of claim 1, further comprising a hydroxide
source.
6. The composition of claim 1, wherein the carbonate is present in
an amount of 15 ppm to 25000 ppm (calculated as carbonate) based on
total weight of the treatment composition.
7. A substrate treated with the composition of claim 1.
8. A method of making a treatment composition comprising: combining
a lithium cation and a carbon dioxide source in an aqueous medium
to form the treatment composition wherein the treatment composition
comprises lithium cation in an amount of 5 ppm to 5500 ppm
(calculated lithium cation) based on total weight of the treatment
composition and carbonate in an amount of 15 ppm to 25000 ppm
(calculated as carbonate) based on total weight of the treatment
composition.
9. The method of claim 8, wherein the pH of the treatment
composition is 9.5 to 12.5.
10. The method of claim 8, further comprising adding an acid other
than carbon dioxide to the treatment composition.
11. The method of claim 8, wherein the lithium cation is present as
a salt comprising lithium carbonate, lithium hydroxide, or
combinations thereof.
12. The method of claim 8, further comprising adding a hydroxide
source to the aqueous medium.
13. The method of claim 8, wherein the hydroxide source comprises
lithium hydroxide, sodium hydroxide, potassium hydroxide, or
combinations thereof.
14. The method of claim 8, wherein the carbon dioxide source
comprises a gas, a solid, or combinations thereof.
15. A substrate treated with the method of claim 8.
16. A system for maintaining carbonate levels in a treatment bath
containing a treatment composition, comprising: a lithium cation;
and/or a carbon dioxide source; and optionally, a hydroxide
source.
17. The system of claim 16, wherein the lithium cation comprises
lithium carbonate, lithium hydroxide, or combinations thereof.
18. The system of claim 16, wherein the carbon dioxide source
comprises a gas, a solid, or combinations thereof.
19. The system of claim 16, wherein the hydroxide source comprises
lithium hydroxide, sodium hydroxide, potassium hydroxide, or
combinations thereof.
20. A substrate treated with the treatment composition in the bath
maintained according to the system of claim 16.
21. A method for maintaining carbonate levels in a treatment bath
containing a treatment composition, comprising: supplying at least
one of a carbon dioxide source and a lithium source to the bath in
an amount sufficient to maintain the pH of the treatment
composition at 9.5 to 12.5, lithium in an amount of 5 ppm to 5500
ppm (calculated as lithium cation) based on total weight of the
treatment composition, and carbonate in an amount of 15 ppm to
25000 ppm (calculated as carbonate) based on total weight of the
treatment composition.
22. The method of claim 21, wherein the carbon dioxide source
comprises a gas, a solid, or combinations thereof.
23. The method of claim 21, wherein the lithium source comprises
lithium carbonate, lithium hydroxide, or combinations thereof.
24. The method of claim 21, further comprising supplying to the
bath a hydroxide source.
25. The method of claim 21, wherein the amount of lithium carbonate
in the treatment bath following the supplying is 25 ppm to 30000
ppm (calculated as total compound) based on total weight of the
treatment composition.
26. The method of claim 21, further comprising monitoring pH of the
treatment bath, amount of carbonate in the treatment bath, amount
of lithium in the treatment bath, or combinations thereof.
27. The method of claim 21, further comprising adding an acid other
than carbon dioxide to the treatment bath.
28. A substrate treated with the treatment composition in the bath
maintained according to the method of claim 21.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/374,188, filed on Aug. 12, 2016 and entitled
"Sealing Composition" and to U.S. Provisional Application No.
62/526,382, filed on Jun. 29, 2017 and entitled "Preparation of
Treatment Composition and System and Method of Maintaining a
Treatment Bath Formed Therefrom," both of which are incorporated in
their entireties herein by reference.
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 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.
[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 O.
[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 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.
[0017] 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
formed, overlaid, deposited, and/or provided on but not necessarily
in contact with the surface. For example, a coating layer "formed
over" a 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 formed 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.
[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, 63.sup.rd 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 IIA 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.sup.rd edition (1983), corresponding to
Group 2 in the actual IUPAC numbering.
[0028] As used herein, the term "Group IIA metal compound" refers
to compounds that include at least one element that is in Group IIA
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.sup.rd edition (1983), corresponding to Group 3 in
the actual IUPAC numbering. For clarity, "Group IIIB 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 Handbook of
Chemistry and Physics, 63.sup.rd edition (1983), corresponding to
Group 4 in the actual IUPAC 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.sup.rd 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.sup.rd 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 VIIB 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.sup.rd edition (1983), corresponding to
Group 7 in the actual IUPAC numbering.
[0038] As used herein, the term "Group VIIB 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.sup.rd edition (1983), corresponding to
Group 12 in the actual IUPAC numbering.
[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 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 10.times. 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.
[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.degree. C. (K;
25.degree. C.) of at least 1.times.10.sup.-11, such as least
1.times.10.sup.-4, and in some instances, may be no more than
5.times.10.sup.+2. According to the present invention, the lithium
salt may have a solubility constant in water at a temperature of
25.degree. C. (K; 25.degree. C.) of 1.times.10.sup.-11 to
5.times.10.sup.+2, such as 1.times.10.sup.-4 to 5.times.10.sup.+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.
[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 12.5.
[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 VIB 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 5 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 VIB 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.
[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 VIB) 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 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 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 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.
[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.
[0064] 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 IIA 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 IIA metal cation, this includes Group IIA metal
cations in any form, such as, but not limited to, the Group IIA
metal-containing compounds listed above.
[0065] 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.
[0066] 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.
[0067] 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.RTM. 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 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.
[0068] 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.
[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 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.
[0070] 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 form.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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 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
acridines.
TABLE-US-00001 TABLE 1 Compound Structure CAS Reg. No. Catechol
Violet Synonyms: Catecholsulfonphthalein;
Pyrocatecholsulfonephthalein; Pyrocatechol Violet ##STR00001##
115-41-3 Xylenol Orange Synonym: 3,3'-Bis[N,N- bis(carboxymethyl)
aminomethyl]- o-cresolsulfonephthalein tetrasodium salt
##STR00002## 3618-43-7
[0075] 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 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.
[0076] 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.
[0077] 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 0.3 g/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.
[0078] 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.
[0079] 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 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.
[0080] 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.
[0081] 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., C1-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.
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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.
[0086] 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.
[0087] 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 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.
[0088] 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.
[0089] 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.
[0090] 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 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.
[0091] 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.
[0092] 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
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.
[0093] 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.
[0094] 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.
[0095] 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/AgCl reference;
Fisher Scientific).
[0096] 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 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.
[0097] 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.
[0098] 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.degree. F.
(5.degree. C.) to about 160.degree. F. (71.degree. C.), such as
60.degree. F. (16.degree. C.) to 110.degree. F. (43.degree. 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.degree. C., if not indicated otherwise. The
contact time is often from 1 second to 2 hours, such as 5 minutes
to 60 minutes.
[0099] 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 formed 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.
[0100] 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, civilian,
commercial and military aircraft, and/or land vehicles such as
cars, motorcycles, and/or trucks.
[0101] 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 Chemkleen.TM. 166tlP, 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, Ohio), and any of the DFM Series,
RECC 1001, and 88X1002 cleaners commercially available from
PRC-DeSoto International, Sylmar, Calif.), and Turco 4215-NCLT and
Ridolene (commercially available from Henkel Technologies, Madison
Heights, Mich.). Such cleaners are often preceded or followed by a
water rinse, such as with tap water, distilled water, or
combinations thereof.
[0102] 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, Mich.), 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 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.degree. F. to 150.degree. F.
(10.degree. C. to 66.degree. C.), such as from 70.degree. F. to
130.degree. F. (21.degree. C. to 54.degree. C.), such as from
80.degree. F. to 120.degree. F. (27.degree. C. to 49.degree. 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.
[0103] 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.degree. C. to 100.degree. C., such as 20.degree. C. to
90.degree. C., or in a heater assembly using, for example, infrared
heat, such as for 10 minutes at 70.degree. 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 IIIB 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 IIA 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.
[0104] 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 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.
[0105] 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.
[0106] 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 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.
[0107] 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 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]-[0015] and U.S. patent
application Ser. No. 13/232,093 at [0014]-[0040], the cited
portions of which being incorporated herein by reference. 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.
[0108] 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.
[0109] 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
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.degree. C. for 15 minutes.
[0110] 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.
[0111] 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.degree. F. to 450.degree. F.
(121.1.degree. C. to 232.2.degree. C.), such as from 275.degree. F.
to 400.degree. F. (135.degree. C. to 204.4.degree. C.), such as
from 300.degree. F. to 360.degree. F. (149.degree. C. to
180.degree. C.). For anionic electrodeposition, the coated
substrate may be heated to a temperature ranging from 200.degree.
F. to 450.degree. F. (93.degree. C. to 232.2.degree. C.), such as
from 275.degree. F. to 400.degree. F. (135.degree. C. to
204.4.degree. C.), such as from 300.degree. F. to 360.degree. F.
(149.degree. C. to 180.degree. C.), such as 200.degree. F. to
210.2.degree. F. (93.degree. C. to 99.degree. 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 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.
[0112] 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 U.S. Pat. No. 7,470,752, assigned to PPG Industries,
Inc. and incorporated herein by reference); 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 U.S. Pat. No. 7,432,333, assigned
to PPG Industries, Inc. and incorporated herein by reference); and
those ccomprising a solid particulate mixture of a reactive
group-containing polymer having a T.sub.g of at least 30.degree. C.
(such as those described in U.S. Pat. No. 6,797,387, assigned to
PPG Industries, Inc. and incorporated herein by reference).
[0113] 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.degree. C. to 200.degree. C., such as from
170.degree. C. to 190.degree. 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.
[0114] 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 SPECTRACRON.RTM. line of solventbased coating
compositions, the AQUACRON.RTM. line of waterbased coating
compositions, and the RAYCRON.RTM. 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.
[0115] 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. No. 10/758,972, and Ser. No. 10/758,972, both
titled "CORROSION RESISTANT COATINGS", all of which are
incorporated herein by reference, and other chrome-free primers
that are known in the art, and which can pass the military
requirement of MIL-PRF-85582 Class N or MIL-PRF-23377 Class N may
also be used with the current invention.
[0116] 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.RTM. ELT.RTM. 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.
[0117] 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 functionalized
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.RTM. ELT.TM./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 according to the present invention as
will be understood by those of skill in the art with reference to
this disclosure.
[0118] 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.
[0119] 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 form a film or "cured" paint.
The coatings can also be applied in a semi or fully cured state,
such as an adhesive.
[0120] 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
[0121] In view of the foregoing the present application thus
relates in particular, without being limited thereto, to the
following Aspects 1 to 24:
[0122] 1. A composition comprising carbon dioxide and a lithium
cation, in an aqueous medium.
[0123] 2. The composition according to Aspect 1, wherein the carbon
dioxide comprises a gas, a solid, or combinations thereof.
[0124] 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.
[0125] 4. The composition according to any one of the preceding
Aspects, wherein the pH is 9.5 to 12.5.
[0126] 5. The composition according to any one of the preceding
Aspects, further comprising a hydroxide.
[0127] 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.
[0128] 7. A method of making a treatment composition comprising:
[0129] 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.
[0130] 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.
[0131] 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.
[0132] 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.
[0133] 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.
[0134] 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.
[0135] 13. A treatment composition obtained according to the method
of any one of Aspects 7 to 12.
[0136] 14. A method for maintaining a treatment bath formed from a
treatment composition comprising lithium carbonate, the method
comprising: [0137] 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.
[0138] 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.
[0139] 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.
[0140] 17. The method for maintaining a treatment bath according to
any one of Aspects 14 to 16, comprising supplying a hydroxide to
the bath.
[0141] 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.
[0142] 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.
[0143] 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.
[0144] 21. A system for maintaining a treatment bath formed from a
treatment composition comprising lithium carbonate, the system
comprising: [0145] a lithium salt source; and/or [0146] a carbon
dioxide source; and [0147] optionally, a hydroxide source.
[0148] 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.
[0149] 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.
[0150] 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.
[0151] 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.
[0152] 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-US-00002 [0153] 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
2,5-dimercapto-1,3,4-thiadiazole, 98% Acros Organics Carbowet
GA100, 100% Air Products cerium nitrate solution (65.37%
Ce(NO.sub.3).sub.3.cndot.6H.sub.2O) ProChem Inc. yttrium nitrate
solution (72.45% Y(NO.sub.3).sub.3.cndot.6H.sub.2O) ProChem Inc.
cerium chloride solution (32.2% as CeO.sub.2*) ProChem Inc.
hydrogen peroxide solution (30% H.sub.2O.sub.2) Alfa Aesar *per
supplier's certificate of analysis
TABLE-US-00003 TABLE 3 Cleaner/Deoxidizer Composition (Example A)
WEIGHT (g) sodium hydroxide pellets, 98% 0.016 sodium phosphate
dodecahydrate, 97% 0.063 polyvinylpyrrolidone (PVP), 8000 m.w.
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
[0154] 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, 7.times.7 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.
TABLE-US-00004 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
[0155] 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.
TABLE-US-00005 TABLE 5 Sealing Compositions (Examples C-O)
LiCO.sub.3 LiOH 5% LiOH Deionized (98% purity) (98% purity) Li
Solution Water (g) (g) (moles) CO.sub.2 (g) (g) pH 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. O -- -- -- -- 15.54 -- 11.37
[0156] 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/AgCl reference; Fisher
Scientific) and the pH for each Example K-O was measured using a pH
meter (Mettler Toledo, Seven2Go, model S2) and a double open
junction electrode (Mettler Toledo, Xerolyt.RTM. polymer
reference).
[0157] 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, 7.times.7 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).
[0158] 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 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).
[0159] 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 FIG. 1 and Table
5. Example E was used to treat panels in Example 3 (described
below).
[0160] 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 FIG. 1 and Table 5. Example F was
used to treat panels in Example 4 (described below).
[0161] 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 FIG. 1 and Table 5. Example G was
used to treat panels in Example 5 (described below).
[0162] 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 FIG. 1 and Table 5. Example H was used
to treat panels in Example 6 (described below).
[0163] 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 FIG. 1 and Table 5. Example I was used to treat
panels in Example 7 (described below).
[0164] 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 solution into the
composition of Example I until a final pH value of 12.47 was
obtained. See FIG. 1 and Table 5. Example J was used to treat
panels in Example 8 (described below).
[0165] 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 FIG. 2 and Table
5. Example M was used to treat panels in Example 11 (described
below).
[0166] 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 FIG. 2 and Table 5. Example N was
used to treat panels in Example 12 (described below).
[0167] Following the use of the bath containing the composition of
Example N according to Example 12, sealing composition Example O
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 FIG. 2 and Table 5. Example O was used to treat
panels in Example 13 (described below).
Panel Preparation
Comparative Example 1
[0168] Aluminum 2024T3 bare substrate (obtained from Priority
Metals, Orange County, Calif.) measuring
3''.times.5''.times.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 at ambient temperature with intermittent agitation.
The panel was air dried at ambient conditions overnight before
corrosion testing as described below.
Comparative Example 2
[0169] Aluminum 2024T3 bare substrate (obtained from Priority
Metals, Orange County, Calif.) measuring
3''.times.5''.times.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
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
[0170] 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 FIG.
1.
[0171] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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 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
[0172] 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 FIG. 1.
[0173] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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
[0174] 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 FIG. 1.
[0175] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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 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
[0176] 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 FIG. 1.
[0177] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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.
Example 7
[0178] 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 FIG. 1.
[0179] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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
[0180] 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 FIG. 1.
[0181] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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 ambient temperature
with intermittent 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
[0182] Aluminum 2024T3 bare substrate (obtained from Priority
Metals, Orange County, Calif.) measuring
3''.times.5''.times.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
[0183] Aluminum 2024T3 bare substrate (obtained from Priority
Metals, Orange County, Calif.) measuring
3''.times.5''.times.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
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
[0184] 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 FIG.
2.
[0185] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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
[0186] 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 9.50 (i.e., to form
Example N as described above). See FIG. 2.
[0187] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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 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
[0188] 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 O as described
above). See FIG. 2.
[0189] Next, additional aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' (Priority Metals, Orange County,
Calif.) 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 O 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
[0190] 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 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.
[0191] Baths from Examples 9-13 were evaluated for lithium
carbonate content using an autotitration method (Metrohm 799 GPT
Titrino, Software by Tiamo 2.3). % Li.sub.2CO.sub.3 and % CO.sub.3
were calculated using the following formulae:
% Li.sub.2CO.sub.3=[(Volume at EP3-Volume at EP2).times.MW
Li.sub.2CO.sub.3.times.HCl conc..times.100]/(SW.times.1000) and
% CO.sub.3=[(Volume at EP3-Volume at EP2).times.MW
CO.sub.3.times.HCl conc..times.100]/(SW.times.1000), [0192] where
EP2 is the second endpoint and EP3 is the third endpoint. HCl
concentration (N) was 0.1012.
[0193] 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.
TABLE-US-00006 TABLE 6 Corrosion Results and Carbonate Measurements
Pits/ Sample HCl HCl Avg Avg Corrosion Weight (mL) (mL) % %
CO.sub.3 CO.sub.3 Example pH Sites (g) EP2* EP3** Li.sub.2CO.sub.3
CO.sub.3 (%) (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
11.14 -- 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 Example 11 11.37 -- 10.1814 2.2263 4.1518 0.141
0.115 0.115 1147 10.3984 2.2655 4.2272 0.141 0.115 Example 12 9.50
-- 10.0817 0.8203 4.0719 0.241 0.196 0.196 1960 10.8563 0.8730
4.3789 0.241 0.196 Example 13 11.37 -- 10.4032 3.6583 7.0788 0.246
0.200 0.200 2002 10.3221 3.5725 6.9857 0.247 0.201
[0194] 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.
[0195] 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 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 CO.sub.2 to CO.sup.3-. 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.
[0196] Example 3 demonstrated that by bubbling CO.sub.2 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.sub.2 also
can be used to form lithium carbonate in a bath that had only a
trace amount of lithium carbonate prior to addition of
CO.sub.2.
[0197] Examples 4, 5, and 12 also demonstrated that bubbling
additional quantities of CO.sub.2 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.
[0198] 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.
[0199] 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.
[0200] The Examples demonstrate the interaction of pH, lithium
concentration, and carbonate concentration with respect to
corrosion resistance.
* * * * *