U.S. patent application number 12/414719 was filed with the patent office on 2010-09-30 for method for treating and/or coating a substrate with non-chrome materials.
This patent application is currently assigned to PPG INDUSTRIES OHIO, INC.. Invention is credited to Richard F. Karabin, Alan J. Kaylo, Mark W. McMillen, Michelle S. Miles, Robin M. Peffer, Edward F. Rakiewicz, Craig A. Wilson.
Application Number | 20100243108 12/414719 |
Document ID | / |
Family ID | 42320688 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100243108 |
Kind Code |
A1 |
Karabin; Richard F. ; et
al. |
September 30, 2010 |
METHOD FOR TREATING AND/OR COATING A SUBSTRATE WITH NON-CHROME
MATERIALS
Abstract
The present invention is directed to a method for coating a
substrate comprising: (a) applying a caustic cleaner onto at least
a portion of the substrate; (b) rinsing at least a portion of the
substrate that was subjected to step (a) with water; (c) applying
an acid cleaner onto at least a portion of the caustically cleaned
substrate; (d) rinsing at least a portion of the substrate that was
subjected to step (c) with water; and (e) applying a conversion
coating comprising zirconium onto at least a portion of the acid
cleaned substrate; and wherein at least one of the materials used
in steps (c) and (e) is substantially chrome free. The present
invention is also directed to a substrate, such as an aluminum
substrate, that has been coated using the aforementioned
method.
Inventors: |
Karabin; Richard F.; (Ruffs
Dales, PA) ; Kaylo; Alan J.; (Glenshaw, PA) ;
McMillen; Mark W.; (Cabot, PA) ; Miles; Michelle
S.; (Mercer, PA) ; Peffer; Robin M.;
(Valencia, PA) ; Rakiewicz; Edward F.; (Gibsonia,
PA) ; Wilson; Craig A.; (Allison Park, PA) |
Correspondence
Address: |
PPG INDUSTRIES INC;INTELLECTUAL PROPERTY DEPT
ONE PPG PLACE
PITTSBURGH
PA
15272
US
|
Assignee: |
PPG INDUSTRIES OHIO, INC.
Cleveland
OH
|
Family ID: |
42320688 |
Appl. No.: |
12/414719 |
Filed: |
March 31, 2009 |
Current U.S.
Class: |
148/240 ;
148/437; 205/188 |
Current CPC
Class: |
C23C 22/78 20130101;
C23G 1/125 20130101; C23G 1/00 20130101; C09D 5/4442 20130101; C23G
1/22 20130101 |
Class at
Publication: |
148/240 ;
205/188; 148/437 |
International
Class: |
C23C 22/78 20060101
C23C022/78; C23C 28/00 20060101 C23C028/00; C22C 21/00 20060101
C22C021/00 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0001] This invention was made with Government support under
Contract No. FA8650-05-C-5010 awarded by the United States Air
Force Research Laboratory. The United States Government may have
certain rights in this invention.
Claims
1. A method for coating a substrate comprising: (a) applying a
caustic cleaner onto at least a portion of the substrate; (b)
rinsing at least a portion of the substrate that was subjected to
step (a) with water; (c) applying an acid cleaner onto at least a
portion of the caustically cleaned substrate; (d) rinsing at least
a portion of the substrate that was subjected to step (c) with
water; and (e) depositing a conversion coating composition
comprising zirconium onto at least a portion of the acid cleaned
substrate; and wherein at least one of the materials used in steps
(c) and (e) is substantially chrome free.
2. The method according to claim 1, wherein the method further
comprises (f) rinsing at least a portion of the substrate that was
subjected to step (e) with water; and (g) depositing an
electrodepositable coating composition onto at least a portion of
the conversion coating, wherein the electrodepositable coating
composition comprises a corrosion inhibitor.
3. The method according to claim 2, wherein the electrodepositable
coating composition is substantially free of chrome.
4. The method according to claim 2, wherein the corrosion inhibitor
comprises an azole compound.
5. The method according to claim 4, wherein the azole compound
comprises benzotriazole, 3-mercapto-1,2,4-triazole,
2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4thiadiazole,
1-methylbenzotriazole, or combinations thereof.
6. The method according to claim 2, wherein the electrodepositable
coating composition comprises an ungelled phosphated epoxy resin in
which the phosphated epoxy resin comprises a mixture of the
reaction product of a polymeric epoxy compound with phosphoric
acid, an organophosphonic acid, an organophosphinic acid, or
combinations thereof.
7. The method according to claim 1, wherein the acid cleaner
comprises phosphoric acid, sulfonic acid, hydrofluoric acid, nitric
acid, or combinations thereof.
8. The method according to claim 1, wherein the conversion coating
composition is substantially free of chrome.
9. A method for coating a substrate comprising: (a) applying a
caustic cleaner onto at least a portion of the substrate; (b)
rinsing at least a portion of the substrate that was subjected to
step (a) with water; (c) applying an acid cleaner onto at least a
portion of the caustically cleaned substrate; (d) rinsing at least
a portion of the substrate that was subjected to step (c) with
water; and (e) depositing a conversion coating composition
comprising zirconium onto at least a portion of the acid cleaned
substrate; and wherein the materials used in steps (c) and (e) are
substantially chrome free.
10. The method according to claim 9, wherein the method further
comprises (f) rinsing at least a portion of the substrate that was
subjected to step (e) with water; and (g) depositing an
electrodepositable coating composition onto at least a portion of
the conversion coating composition, wherein the electrodepositable
coating composition comprises a corrosion inhibitor.
11. The method according to claim 10, wherein the corrosion
inhibitor comprises an azole compound.
12. The method according to claim 11, wherein the azole compound
comprises benzotriazole, 3-mercapto-1,2,4-triazole,
2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4thiadiazole,
1-methylbenzotriazole, or combinations thereof.
13. The method according to claim 10, wherein the
electrodepositable coating composition comprises an ungelled
phosphated epoxy resin in which the phosphated epoxy resin
comprises a mixture of the reaction product of a polymeric epoxy
compound with phosphoric acid, an organophosphonic acid, an
organophosphinic acid, or combinations thereof.
14. The method according to claim 9, wherein the materials used in
steps (c) and (e) are substantially chrome free.
15. A method for coating a substrate consisting essentially of: (a)
applying a caustic cleaner onto at least a portion of the
substrate; (b) rinsing at least a portion of the substrate that was
subjected to step (a) with water; (c) applying an acid cleaner onto
at least a portion of the caustically cleaned substrate; (d)
rinsing at least a portion of the substrate that was subjected to
step (c) with water; (e) depositing a conversion coating
composition comprising zirconium onto at least a portion of the
acid cleaned substrate; (f) rinsing at least a portion of the
substrate that was subjected to step (e) with water; and (g)
depositing an electrodepositable coating composition onto at least
a portion of the conversion coating composition, wherein the
electrodepositable coating composition comprises a corrosion
inhibitor; and wherein the materials used in steps (c), (e), and
(g) are substantially free of chrome.
16. The method according to claim 15, wherein the corrosion
inhibitor comprises an azole compound.
17. The method according to claim 16, wherein the azole compound
comprises benzotriazole, 3-mercapto-1,2,4-triazole,
2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4thiadiazole,
1-methylbenzotriazole, or combinations thereof.
18. The method according to claim 15, wherein the
electrodepositable coating composition comprises an ungelled
phosphated epoxy resin in which the phosphated epoxy resin
comprises a mixture of the reaction product of a polymeric epoxy
compound with phosphoric acid, an organophosphonic acid, an
organophosphinic acid, or combinations thereof.
19. A substrate coated according to claim 1.
20. The substrate according to claim 19, wherein the substrate is
aluminum.
Description
FIELD OF THE INVENTION
[0002] The present invention relates generally to a method for
treating and/or coating a substrate with non-chrome materials.
BACKGROUND INFORMATION
[0003] Conventional pretreatment and primer coating compositions
which are used in the aerospace industry contain chrome, such as
hexavalent chrome, in order to impart corrosion resistance to the
substrate onto which these coatings are deposited. However, due to
toxicity concerns associated with hexavalent chrome as well as
potential governmental regulations regarding the amount of
hexavalent chrome that may be used in a coating, there is a need to
reduce and/or eliminate that use of hexavalent chrome in
pretreatment and primer coatings that are used in the aerospace
industry.
SUMMARY OF THE INVENTION
[0004] The present invention is directed to a method for coating a
substrate comprising: (a) applying a caustic cleaner onto at least
a portion of the substrate; (b) rinsing at least a portion of the
substrate that was subjected to step (a) with water; (c) applying
an acid cleaner onto at least a portion of the caustically cleaned
substrate; (d) rinsing at least a portion of the substrate that was
subjected to step (c) with water; and (e) applying a conversion
coating comprising zirconium onto at least a portion of the acid
cleaned substrate; and wherein at least one of the materials used
in steps (c) and (e) is substantially chrome free. The present
invention is also directed to a substrate, such as an aluminum
substrate, that has been coated with the aforementioned method.
[0005] The present invention is also directed to a method for
coating a substrate comprising: (a) applying a caustic cleaner onto
at least a portion of the substrate; (b) rinsing at least a portion
of the substrate that was subjected to step (a) with water; (c)
applying an acid cleaner onto at least a portion of the caustically
cleaned substrate; (d) rinsing at least a portion of the substrate
that was subjected to step (c) with water; and (e) applying a
conversion coating comprising zirconium onto at least a portion of
the acid cleaned substrate; and wherein the materials used in steps
(c) and (e) are substantially chrome free.
[0006] The present invention is also directed to a method for
coating a substrate consisting essentially of: (a) applying a
caustic cleaner onto at least a portion of the substrate; (b)
rinsing at least a portion of the substrate that was subjected to
step (a) with water; (c) applying an acid cleaner onto at least a
portion of the caustically cleaned substrate; (d) rinsing at least
a portion of the substrate that was subjected to step (c) with
water; (e) applying a conversion coating comprising zirconium onto
at least a portion of the acid cleaned substrate; (f) rinsing at
least a portion of the substrate that was subjected to step (e)
with water; and (g) applying an electrodepositable coating
composition onto at least a portion of the conversion coating,
wherein the electrodepositable coating composition comprises a
corrosion inhibitor; and wherein the materials used in steps (c),
(e), and (g) are substantially free of chrome.
DETAILED DESCRIPTION OF THE INVENTION
[0007] As used herein, unless otherwise expressly specified, all
numbers such as those expressing values, ranges, amounts or
percentages may be read as if prefaced by the word "about", even if
the term does not expressly appear. Plural encompasses singular and
vice versa. For example, although reference is made herein to "a"
caustic cleaner, "an" acid cleaner, "a" conversion coating, "an"
electrodepositable coating, "a" corrosion inhibitor, a combination
(i.e., a plurality) of caustic cleaners and acid cleaners may be
used.
[0008] As used herein, "plurality" means two or more.
[0009] As used herein, "includes" and like terms means "including
without limitation."
[0010] When referring to any numerical range of values, such ranges
are understood to include each and every number and/or fraction
between the stated range minimum and maximum.
[0011] As used herein, the term "cure" refers to a coating wherein
any crosslinkable components of the composition are at least
partially crosslinked. In certain embodiments, the crosslink
density of the crosslinkable components (i.e., the degree of
crosslinking) ranges from 5% to 100%, such as 35% to 85%, or, in
some cases, 50% to 85% of complete crosslinking. One skilled in the
art will understand that the presence and degree of crosslinking
(i.e., the crosslink density) can be determined by a variety of
methods, such as dynamic mechanical thermal analysis (DMTA) using a
Polymer Laboratories MK III DMTA analyzer conducted under
nitrogen.
[0012] As used herein, molecular weight refers to number average
molecular weight (M.sub.w) as determined by Gel Permeation
Chromatography.
[0013] Reference to any monomer(s) herein refers generally to a
monomer that can be polymerized with another polymerizable compound
such as another monomer or polymer. Unless otherwise indicated, it
should be appreciated that once the monomer components react with
one another to form the compound, the compound will comprise the
residues of the monomer components.
Coating Process
[0014] As stated above, the present invention is directed to a
method of coating a substrate, such as an aluminum substrate, with
a non-chrome coating system. Unlike other methods of coating an
aluminum substrate, the method disclosed herein does not require
the use of any materials (e.g., cleaners, water, conversion
coatings, electrodepositable coating compositions) that contain
chrome. Accordingly, in certain embodiments, the materials used in
one or more of the steps described below can be substantially
chrome free. As used herein, "substantially chrome free" means that
chrome is not intentionally added to the material by the user. For
example, in some embodiments, all the materials used in the steps
described below are substantially chrome free. In other
embodiments, one or more of the materials used in the steps below
(e.g., the conversion coating and/or the electrodepositable coating
composition) are substantially chrome free while other materials
used in other steps (e.g., the acid cleaner) may contain chrome.
For purposes of this disclosure, the materials used in steps (a)
through (g) may be applied onto the substrate using techniques
known in the art such as spray and/or immersion techniques.
[0015] The method begins by (a) applying a caustic cleaner onto at
least a portion of a substrate. The caustic cleaner is used to
remove oil and/or other contaminants (e.g., dirt or dust), which
can be deposited onto the surface of the substrate during a forming
and/or stamping process, prior to the application of another
coating composition onto the substrate. The caustic cleaner that
may be used in the present invention can be any silicate and/or
non-silicated caustic cleaners known in the art. Suitable silicated
and/or non-silicated caustic cleaners include METALAST CLEANER 1000
(commercially available from METALAST International, Inc.),
RIDOLENE 298 (commercially available from HENKEL), CHEMKLEEN 275
(commercially available from PPG Industries, Inc.), or combinations
thereof.
[0016] After step (a), at least of a portion of the substrate that
was subjected to step (a) undergoes (b) a rinsing stage and rinsed
with water, such as deionized water, in order to wash at least a
portion of the caustic cleaner from the surface of the
substrate.
[0017] After step (b), (c) an acid cleaner is applied onto at least
a portion of the caustically cleaned substrate. The acid cleaner is
applied onto the surface in order to etch the surface of the
substrate. In certain embodiments, the acid cleaner is used to
deoxidize the surface of the substrate (e.g., remove the oxide
layer found on the surface of the substrate) in order to promote
the uniform deposition of a conversion coating, which is described
below, as well as to promote the adhesion of the conversion coating
to the substrate. Suitable acid cleaners that may be used in the
method disclosed herein include, without limitation, phosphoric
acid, sulfuric acid, nitric acid, hydrofluoric acid, LNC DEOXIDIZER
(commercially available from Oakite), TURCO DEOXIDIZER 6
(commercially available from Henkel), or combinations thereof.
[0018] After step (c), at least a portion of the substrate that was
subjected to step (c) undergoes (d) a rinsing stage and rinsed with
water, such as deionized water, in order to wash at least a portion
of the acid cleaner from the surface of the substrate.
[0019] After step (d), (e) a conversion coating composition
(pretreatment coating composition) comprising zirconium is then
deposited onto at least a portion of the acid cleaned substrate. In
some embodiments, the conversion coating comprises a pretreatment
bath that comprises 10 parts per million (ppm) to 10,000 ppm of
zirconium based on the total weight of the pretreatment bath. In
certain embodiments, the conversion coating composition can further
comprise chrome. Traditional chrome containing (non-zirconium
containing) conversion coatings, which are known in the art, may
also be used in the present invention. Examples of such traditional
chrome containing conversion coatings include ALODINE 1200S
(commercially available from Henkel) and/or METLAST TCP-HF
(commercially available from Metalast International Inc.).
[0020] Alternatively, in some embodiments, in lieu of the
application of the conversion coating described in the previous
paragraph, the surface of the substrate can be anodized using
techniques known in the art.
[0021] After step (e), at least of a portion of the substrate that
was subjected to step (e) undergoes (f) a rinsing stage and rinsed
with water, such as deionized water, in order to wash at least a
portion of excess conversion coating composition from the surface
of the substrate.
[0022] After step (f), (g) an electrodepositable coating
composition, which comprises a corrosion inhibitor, is deposited
onto at least a portion of the substrate onto which the conversion
coating was deposited using techniques known in the art such as
aniodic or cathodic electrodeposition. In some embodiments, the
electrodepositable coating composition is an anionic
electrodepositable coating composition. In certain embodiments,
suitable corrosion inhibitors that may be used in the
electrodepositable coating composition comprise a
nitrogen-containing heterocyclic compound. Examples of such
compounds, which are suitable for use in the present invention, are
azoles, oxazoles, thiazoles, thiazolines, imidazoles, diazoles,
pyridines, indolizines, and triazines, tetrazoles, tolutriazole, or
mixtures thereof. Suitable triazoles include, for example,
1,2,3-triazole, 1,2,4-triazole, benzotriazole, and their
derivatives, or combinations thereof. Derivatives of
1,2,3-triazole, which are suitable for use in the present
invention, include 1-methyl-1,2,3-triazole,
1-phenyl-1,2,3-triazole, 4-methyl-2-phenyl-1,2,3-triazole,
1-benzyl-1,2,3-triazole, 4-hydroxy-1,2,3-triazole,
1-amino-1,2,3-triazole, 1-benzamido-4-methyl-1,2,3-triazole,
1-amino-4,5-diphenyl-1,2,3-triazole, 1,2,3-triazole aldehyde,
2-methyl-1,2,3-triazole-4-carboxylic acid, and
4-cyano-1,2,3-triazole, or combinations thereof. Derivatives of
1,2,4-triazole, which are suitable for use in the present
invention, include 1-methyl-1,2,4-triazole,
1,3-diphenyl-1,2,4-triazole, 5-amino-3-methyl-1,2,4-triazole,
3-mercapto-1,2,4-triazole, 1,2,4-triazole-3-carboxylic acid,
1-phenyl-1,2,4-triazole-5-one, 1-phenylurazole, or combinations
thereof. Suitable examples of diazoles and thiazole could include
2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4thiadiazole and
derivatives, or combinations thereof. Derivatives of benzotriazole,
which are suitable for use in the present invention, include
1-methylbenzotriazole, 5,6-dimethylbenzotriazole,
2-phenylbenzotriazole, 1-hydroxybenzotriazole, methyl
1-benzotriazolecarboxylate,
2-(3',5'-dibutyl-2'-hydroxyphenyl)benzotriazole, or combinations
thereof. In certain embodiments, the amount of azole compound
present in the electrodepositable coating composition is
.gtoreq.0.5 weight % based on the total resin solids of the
electrodepositable coating composition. In some embodiments, the
amount of azole compound present in the electrodepositable coating
composition is .ltoreq.5 weight % based on the total resin solids
of the electrodepositable coating composition. In certain
embodiments, the amount of azole compound present in the
electrodepositable coating composition ranges between any
combination of values, which were recited in the preceding
sentences, inclusive of the recited values. For example, in some
embodiments, the azole compound is present from 2 weight % to 4
weight % based on the total resin solids of the electrodepositable
coating composition.
[0023] Alternatively, in some embodiments, in lieu of the
application of the electrodepositable coating composition described
in the previous paragraph, a color imparting coating composition
(described in further detail below) may be applied onto the
substrate using techniques known in the art.
[0024] In some embodiments, the method consists essentially of
steps (a) through (g) and wherein the materials used in steps (c),
(e), and (g) are substantially free of chrome.
Substrate with a Coating System
[0025] The method described above can be used on a variety of
substrates. Suitable substrates that can be used with the present
invention include metal substrates, metal alloy substrates, and/or
substrates that have been metallized, such as nickel plated
plastic. In some embodiments, the metal or metal alloy can be steel
and/or aluminum. For example, the steel substrate could be cold
rolled steel, electrogalvanized steel, and/or hot dipped galvanized
steel. Aluminum alloys of the 2XXX, 5XXX, 6XXX, or 7XXX series as
well as clad aluminum alloys may also be used as the substrate. The
substrate used in the present invention may also comprise titanium
and/or titanium alloys. In some embodiments, the substrate may
comprise a portion of a vehicle such as a vehicular body (e.g.,
without limitation, door, body panel, trunk deck lid, roof panel,
hood, 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.
[0026] The various coating compositions described herein may be
applied as part of a coating system that can be deposited onto the
substrate. The coating system typically comprises a number of
coating layers. A coating layer is usually formed when a coating
composition (e.g., a primer-surfacer, color imparting, and/or
substantially clear coating composition; described further below)
that is deposited onto the substrate is substantially cured or
dried by methods known in the art (e.g., by thermal heating).
[0027] Depending on the industry (e.g., aerospace or automotive),
various coating layers, such as a primer-surfacer layer or a color
imparting coating layer, may be applied onto at least a portion of
the electrodepositable coating layer. For example, in the aerospace
industry, a color imparting coating layer, such as DESOPHANE
(commercially available from PPG Industries, Inc.), is deposited
onto at least a portion of the electrodepositable coating layer. In
certain embodiments, a primer layer, such as DESOPRIME
(commercially available from PPG Industries, Inc.), is disposed
between the electrodepositable coating layer and the color
imparting coating layer.
[0028] In a conventional coating system used in the automotive
industry, a primer-surfacer layer, such as DPX-1791, DPX-1804,
DSPX-1537, GPXH-5379, OPP-2645, PCV-70118, and 1177-225A (available
from PPG Industries, Inc.) is typically deposited onto at least a
portion of the electrodepositable coating layer. The
primer-surfacer coating layer serves to enhance chip resistance of
subsequently applied coating layers (e.g., color imparting coating
composition and/or substantially clear coating composition) as well
as to aid in the appearance of the subsequently applied layers. As
used herein, "primer-surfacer" refers to a primer composition for
use under a subsequently applied coating composition, and includes
such materials as thermoplastic and/or crosslinking (e.g.,
thermosetting) film-forming resins generally known in the art of
organic coating compositions.
[0029] It should be noted that in some embodiments, the
primer-surfacer coating layer is not used in the coating system.
Therefore, a color imparting coating layer can be deposited onto at
least a portion of the electrodepositable coating layer.
[0030] In some embodiments, a color imparting coating composition
(hereinafter, "basecoat") is deposited onto at least a portion of
the primer surfacer coating layer (if present). Any basecoat
coating composition known in the art may be used in the present
invention. It should be noted that these basecoat coating
compositions typically comprise a colorant.
[0031] In certain embodiments, a substantially clear coating
composition (hereinafter, "clearcoat") is deposited onto at least a
portion of the basecoat coating layer. As used herein, a
"substantially clear" coating layer is substantially transparent
and not opaque. In certain embodiments, the substantially clear
coating composition can comprise a colorant but not in an amount
such as to render the clear coating composition opaque (not
substantially transparent) after it has been cured. Any clearcoat
coating composition known in the art may be used in the present
invention. For example, the clearcoat coating composition that is
described in U.S. Pat. Nos. 5,989,642, 6,245,855, 6,387,519, and
7,005,472 can be used in the coating system. In certain
embodiments, the substantially clear coating composition can also
comprise a particle, such as a silica particle, that is dispersed
in the clearcoat coating composition (such as at the surface of the
clearcoat coating composition after curing). In some embodiments,
the coating composition comprising the polymer described herein can
be used as the clearcoat coating composition.
[0032] One or more of the coating compositions described herein can
comprise colorants and/or other optional materials, which are known
in the art of formulated surface coatings. As used herein, the term
"colorant" means any substance that imparts color and/or other
opacity and/or other visual effect to the composition. The colorant
can be added to the coating in any suitable form, such as discrete
particles, dispersions, solutions and/or flakes (e.g., aluminum
flakes). A single colorant or a mixture of two or more colorants
can be used in the coating composition described herein.
[0033] Example colorants include pigments, dyes and tints, such as
those used in the paint industry and/or listed in the Dry Color
Manufacturers Association (DCMA), as well as special effect
compositions. A colorant may include, for example, a finely divided
solid powder that is insoluble but wettable under the conditions of
use. A colorant can be organic or inorganic and can be agglomerated
or non-agglomerated. Colorants can be incorporated into the
coatings by use of a grind vehicle, such as an acrylic grind
vehicle, the use of which will be familiar to one skilled in the
art.
[0034] Example pigments and/or pigment compositions include, but
are not limited to, carbazole dioxazine crude pigment, azo,
monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone,
condensation, metal complex, isoindolinone, isoindoline and
polycyclic phthalocyanine, quinacridone, perylene, perinone,
diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone,
anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone,
dioxazine, triarylcarbonium, quinophthalone pigments, diketo
pyrrolo pyrrole red ("DPPBO red"), titanium dioxide, carbon black
and mixtures thereof. The terms "pigment" and "colored filler" can
be used interchangeably.
[0035] Example dyes include, but are not limited to, those that are
solvent and/or aqueous based such as phthalo green or blue, iron
oxide, bismuth vanadate, anthraquinone, perylene, aluminum and
quinacridone.
[0036] Example tints include, but are not limited to, pigments
dispersed in water-based or water miscible carriers such as
AQUA-CHEM 896 commercially available from Degussa, Inc., CHARISMA
COLORANTS and MAXITONER INDUSTRIAL COLORANTS commercially available
from Accurate Dispersions division of Eastman Chemical, Inc.
[0037] As noted above, the colorant can be in the form of a
dispersion including, but not limited to, a nanoparticle
dispersion. Nanoparticle dispersions can include one or more highly
dispersed nanoparticle colorants and/or colorant particles that
produce a desired visible color and/or opacity and/or visual
effect. Nanoparticle dispersions can include colorants such as
pigments or dyes having a particle size of less than 150 nm, such
as less than 70 nm, or less than 30 nm. Nanoparticles can be
produced by milling stock organic or inorganic pigments with
grinding media having a particle size of less than 0.5 mm. Example
nanoparticle dispersions and methods for making them are identified
in U.S. Pat. No. 6,875,800. Nanoparticle dispersions can also be
produced by crystallization, precipitation, gas phase condensation,
and chemical attrition (i.e., partial dissolution). In order to
minimize re-agglomeration of nanoparticles within the coating, a
dispersion of resin-coated nanoparticles can be used. As used
herein, a "dispersion of resin-coated nanoparticles" refers to a
continuous phase in which is dispersed discreet "composite
microparticles" that comprise a nanoparticle and a resin coating on
the nanoparticle. Example dispersions of resin-coated nanoparticles
and methods for making them are identified in United States Patent
Application Publication 2005-0287348, filed Jun. 24, 2004, U.S.
Provisional Application No. 60/482,167, filed Jun. 24, 2003, and
U.S. patent application Ser. No. 11/337,062, filed Jan. 20,
2006.
[0038] Example special effect compositions that may be used include
pigments and/or compositions that produce one or more appearance
effects such as reflectance, pearlescence, metallic sheen,
phosphorescence, fluorescence, photochromism, photosensitivity,
thermochromism, goniochromism and/or color-change. Additional
special effect compositions can provide other perceptible
properties, such as opacity or texture. In a non-limiting
embodiment, special effect compositions can produce a color shift,
such that the color of the coating changes when the coating is
viewed at different angles. Example color effect compositions are
identified in U.S. Pat. No. 6,894,086. Additional color effect
compositions can include transparent coated mica and/or synthetic
mica, coated silica, coated alumina, a transparent liquid crystal
pigment, a liquid crystal coating, and/or any composition wherein
interference results from a refractive index differential within
the material and not because of the refractive index differential
between the surface of the material and the air.
[0039] In certain non-limiting embodiments, a photosensitive
composition and/or photochromic composition, which reversibly
alters its color when exposed to one or more light sources, can be
used in the coating composition described herein. Photochromic
and/or photosensitive compositions can be activated by exposure to
radiation of a specified wavelength. When the composition becomes
excited, the molecular structure is changed and the altered
structure exhibits a new color that is different from the original
color of the composition. When the exposure to radiation is
removed, the photochromic and/or photosensitive composition can
return to a state of rest, in which the original color of the
composition returns. In one non-limiting embodiment, the
photochromic and/or photosensitive composition can be colorless in
a non-excited state and exhibit a color in an excited state. Full
color-change can appear within milliseconds to several minutes,
such as from 20 seconds to 60 seconds. Example photochromic and/or
photosensitive compositions include photochromic dyes.
[0040] In a non-limiting embodiment, the photosensitive composition
and/or photochromic composition can be associated with and/or at
least partially bound to, such as by covalent bonding, a polymer
and/or polymeric materials of a polymerizable component. In
contrast to some coatings in which the photosensitive composition
may migrate out of the coating and crystallize into the substrate,
the photosensitive composition and/or photochromic composition
associated with and/or at least partially bound to a polymer and/or
polymerizable component in accordance with a non-limiting
embodiment of the present invention, have minimal migration out of
the coating. Example photosensitive compositions and/or
photochromic compositions and methods for making them are
identified in U.S. application Ser. No. 10/892,919, filed Jul. 16,
2004.
[0041] In general, the colorant can be present in any amount
sufficient to impart the desired visual and/or color effect. The
colorant may comprise from 1 to 65 weight percent of the present
compositions, such as from 3 to 40 weight percent or 5 to 35 weight
percent, with weight percent based on the total weight of the
compositions.
[0042] The coating compositions can comprise other optional
materials well known in the art of formulated surface coatings,
such as plasticizers, anti-oxidants, hindered amine light
stabilizers, UV light absorbers and stabilizers, surfactants, flow
control agents, thixotropic agents such as bentonite clay,
pigments, fillers, organic cosolvents, catalysts, including
phosphonic acids and other customary auxiliaries.
[0043] It will be further appreciated that one or more of the
coating compositions that form the various coating layers described
herein can be either "one component" ("1K"), "two component"
("2K"), or even multi-component compositions. A 1K composition will
be understood as referring to a composition wherein all of the
coating components are maintained in the same container after
manufacture, during storage, etc. A 2K composition or
multi-component composition will be understood as referring to a
composition wherein various components are maintained separately
until just prior to application. A 1K or 2K coating composition can
be applied to a substrate and cured by any conventional means, such
as by heating, forced air, and the like.
[0044] The coating compositions that form the various coating
layers described herein can be deposited or applied onto the
substrate using any technique that is known in the art. For
example, the coating compositions can be applied to the substrate
by any of a variety of methods including, without limitation,
spraying, brushing, dipping, and/or roll coating, among other
methods. When a plurality of coating compositions are applied onto
a substrate, it should be noted that one coating composition may be
applied onto at least a portion of an underlying coating
composition either after the underlying coating composition has
been cured or prior to the underlying coating composition being
cured. If the coating composition is applied onto an underlying
coating composition that has not been cured, one or more of the
uncured coating compositions may be cured simultaneously.
[0045] The coating compositions may be cured using any technique
known in the art such as, without limitation, thermal energy,
infrared, ionizing or actinic radiation, or by any combination
thereof. In certain embodiments, the curing operation can be
carried out at temperatures .gtoreq.10.degree. C. In other
embodiments, the curing operation can be carried out at temperature
.ltoreq.246.degree. C. In certain embodiments, the curing operation
can carried out at temperatures ranging between any combination of
values, which were recited in the preceding sentences, inclusive of
the recited values. For example, the curing operation can be
carried out at temperatures ranging from 120.degree. C.-150.degree.
C. It should be noted, however, that lower or higher temperatures
may be used as necessary to activate the curing mechanisms.
[0046] In certain embodiments, the coating compositions described
herein are a low temperature, moisture curable coating
compositions. As used herein, the term "low temperature, moisture
curable" refers to coating compositions that, following application
to a substrate, are capable of curing in the presence of ambient
air, the air having a relative humidity of 10% to 100%, such as 25%
to 80%, and a temperature in the range of -10.degree. C. to
120.degree. C., such as 5.degree. C. to 80.degree. C., in some
cases 10.degree. C. to 60.degree. C. and, in yet other cases,
15.degree. C. to 40.degree. C.
[0047] The dry film thickness of the coating layers described
herein can range from 0.1 micron to 500 microns. In other
embodiments, the dry film thickness can be .ltoreq.125 microns,
such as .ltoreq.80 microns. For example, the dry film thickness can
range from 15 microns to 60 microns.
[0048] While specific embodiments of the invention have been
described in detail, it will be appreciated by those skilled in the
art that various modifications and alternatives to those details
could be developed in light of the overall teachings of the
disclosure. Accordingly, the particular arrangements disclosed are
meant to be illustrative only and not limiting as to the scope of
the invention which is to be given the full breadth of the claims
appended and any and all equivalents thereof.
EXAMPLES
Example I
[0049] 2024-T3 bare aluminum panels were cleaned by spraying with a
solution of CHEMKLEEN 275, an alkaline cleaner available from PPG
Industries, for two minutes at 130.degree. F. After alkaline
cleaning, the panels were rinsed thoroughly with deionized water.
The panels were then immersed in an acidic solution for two minutes
at 120.degree. F. The acid solution was prepared by diluting 198.1
grams of 85% phosphoric acid, 8.5 grams of 70% nitric acid, 16.5
grams of TRITON X-100 (available from The Dow Chemical Company) and
11.1 grams of TRITON CF-10 (available from The Dow Chemical
Company) to five gallons of volume with deionized water, and then
neutralizing to pH 3.0 with CHEMFIL Buffer (available from PPG
Industries). After treatment in the acid solution, the panels were
rinsed thoroughly with deionized water and blown dry with a warm
air blowoff.
[0050] The panels were then electrocoated in an electrodeposition
bath (described below) after the bath was subjected to 50%
ultrafiltration. The electrodeposition was performed at 100 to 170
volts for 90 seconds at bath temperatures of 24-27.degree. C. After
electrodeposition, the panels were all baked at 93.degree. C.
(200.degree. F.) for 30 min. in a gas-fired oven. The electrocoated
panels were then subjected to ASTM B117 5% neutral salt fog for
3000 hours.
Bath Composition Used in Example I
Resin 1: Phosphated Epoxy Resin Dispersion Preparation
[0051] A mixture of 819.2 parts of bisphenol A diglycidyl ether
(EEW 188), 263.5 parts of bisphenol A, and 209.4 parts of
2-n-butoxy-1-ethanol was heated to 115.degree. C. At that point,
0.8 parts of ethyl triphenylphosphonium iodide was added. This
mixture was heated and held at a temperature of at least
165.degree. C. for one hour. As the mixture was allowed to cool to
88.degree. C., 51.3 parts of EKTASOLVE EEH solvent and 23.2 parts
of 2-n-butoxy-1-ethanol were added. At 88.degree. C., a slurry
consisting of 32.1 parts of 85% o-phosphoric acid, 18.9 parts
phenylphosphonic acid, and 6.9 parts of EKTASOLVE EEH was added.
The reaction mixture was subsequently maintained at a temperature
of at least 120.degree. C. for 30 minutes. At that point, the
mixture was cooled to 100.degree. C. and 71.5 parts of deionized
water was gradually added. Once the water was added, a temperature
of about 100.degree. C. was maintained for 2 hours. Then the
reaction mixture was cooled to 90.degree. C. and 90.0 parts of
diisopropanolamine was added, followed by 413.0 parts of CYMEL 1130
and 3.0 parts of deionized water. After 30 minutes of mixing,
1800.0 parts of this mixture was reverse-thinned into 1506.0 parts
of agitated deionized water. An additional 348.0 parts of deionized
water was added to yield a homogeneous dispersion which evidenced a
solids content of 39.5% after 1 hour at 110.degree. C.
[0052] The electrodeposition bath was prepared as follows:
TABLE-US-00001 Ingredients Parts by Weight Phosphated epoxy resin
dispersion 1522 Pigment paste.sup.1 331 Deionized water 1947
.sup.1Grey pigment paste, ACPP-1120, available from PPG Industries,
Inc., 50% solids.
[0053] The above ingredients were thoroughly blended to produce a
resinous blend having a solids content of 19% with a pigment/binder
ratio of 0.2.
Example II
[0054] 2024-T3 bare aluminum panels were cleaned by spraying with a
solution of CHEMKLEEN 275, an alkaline cleaner available from PPG
Industries, for two minutes at 130.degree. F. After alkaline
cleaning, the panels were rinsed thoroughly with deionized water.
The panels were then immersed in an acidic solution for two minutes
at 120.degree. F. The acid solution was prepared by diluting 198.1
grams of 85% phosphoric acid, 8.5 grams of 70% nitric acid, 16.5
grams of TRITON X-100 (available from The Dow Chemical Company) and
11.1 grams of TRITON CF-10 (available from The Dow Chemical
Company) to five gallons of volume with deionized water, and then
neutralizing to pH 3.0 with CHEMFIL Buffer (available from PPG
Industries). After treatment in the acid solution, the panels were
rinsed thoroughly with deionized water. The panels were then
immersed in a solution of fluorozirconic acid for two minutes at
100.degree. F. The acid bath was prepared by diluting 16.6 grams of
45% fluorozirconic acid to five gallons of volume with deionized
water, and then neutralizing to pH 4.5 with CHEMFIL Buffer
(available from PPG Industries). After treatment in the acid
solution, the panels were rinsed thoroughly with deionized water
and blown dry with a warm air blowoff.
[0055] The panels were then electrocoated in an electrodeposition
bath (described below) after the bath was subjected to 50%
ultrafiltration. The electrodeposition was performed at 100 to 170
volts for 90 seconds at bath temperatures of 24-27.degree. C. After
electrodeposition, the panels were all baked at 93.degree. C.
(200.degree. F.) for 30 min. in a gas-fired oven. The electrocoated
panels were then subjected to ASTM B117 5% neutral salt fog for
3000 hours.
Bath Composition Used in Example II
Resin II: Phosphated Epoxy Resin Dispersion Preparation
[0056] A mixture of 819.2 parts of bisphenol A diglycidyl ether
(EEW 188), 263.5 parts of bisphenol A, and 209.4 parts of
2-n-butoxy-1-ethanol was heated to 115.degree. C. At that point,
0.8 parts of ethyl triphenylphosphonium iodide was added. This
mixture was heated and held at a temperature of at least
165.degree. C. for one hour. As the mixture was allowed to cool to
88.degree. C., 51.3 parts of EKTASOLVE EEH solvent and 23.2 parts
of 2-n-butoxy-1-ethanol were added. At 88.degree. C., a slurry
consisting of 32.1 parts of 85% o-phosphoric acid, 18.9 parts
phenylphosphonic acid, and 6.9 parts of EKTASOLVE EEH was added.
The reaction mixture was subsequently maintained at a temperature
of at least 120.degree. C. for 30 minutes. At that point, the
mixture was cooled to 100.degree. C. and 71.5 parts of deionized
water was gradually added. Once the water was added, a temperature
of about 100.degree. C. was maintained for 2 hours. Then the
reaction mixture was cooled to 90.degree. C. and 90.0 parts of
diisopropanolamine was added, followed by 413.0 parts of CYMEL 1130
and 3.0 parts of deionized water. After 30 minutes of mixing,
1800.0 parts of this mixture was reverse-thinned into 1506.0 parts
of agitated deionized water. An additional 348.0 parts of deionized
water was added to yield a homogeneous dispersion which evidenced a
solids content of 39.5% after 1 hour at 110.degree. C.
[0057] A resinous blend of the above-described phosphated epoxy
resin was prepared as follows:
TABLE-US-00002 Ingredients Parts by Weight Phosphated epoxy resin
dispersion of 1522 Example 1 + corrosion inhibitor Pigment
paste.sup.1 331 Deionized water 1947 .sup.1Grey pigment paste,
ACPP-1120, available from PPG Industries, Inc., 50% solids.
[0058] The above ingredients were thoroughly blended to produce a
resinous blend having a solids content of 19% with a pigment/binder
ratio of 0.2.
Test Result Summary
[0059] Test results indicated that the panels from Example II
exhibited improved corrosion performance (i.e. less blistering;
face and scribe), less corrosion in the scribe, and less pitting
when compared to panels from Example I.
* * * * *