Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR TREATING AND/OR COATING A SUBSTRATE WITH NON-
CHROME MATERIALS
100011 (This paragraph intentionally left blank)
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
100041 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
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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,
100061 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 "e caustic
cleaner, "an" acid
cleaner, "a" conversion coating, 'an" electrodepositabie coating, "a"
corrosion inhibitor, a
combination (i.e., a plurality) of caustic cleaners and acid cleaners may be
used.
100081 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.
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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 Ill DMTA analyzer
conducted under
nitrogen.
[0012] As used herein, molecular weight refers to number average
molecular weight
(M,) 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
[00141 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-
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silicated caustic cleaners known in the art. Suitable silicated and/or non-
silicated caustic
cleaners include METALASTTm 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.
100161 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 deionzed
water, in order to
wash at least a portion of the caustic cleaner from the surface of the
substrate.
100171 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 DEOXIDIZERTM 6 (commercially available from
Henkel), or
combinations thereof.
[00181 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 deionzed water,
in order to wash
at least a portion of the acid cleaner from the surface of the substrate.
[00191 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 ppnn 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 ALODINETM 1200S
(commercially available from Henkel) and/or METLAST TCP-HF (commercially
available from
Metalast International Inc.).
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[00201 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.
[00211 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 cleionzecl
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 eleotrodepositable 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 eleotrodepositable
coating composition
is an anionic electrodepositable coating composition. In certain embodiments,
suitable
corrosion inhibitors that may be used in the electrodepositabie 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 '12,3-triazole, which are
suitable for use in
the present invention, include I-methyl-1,2,3- triazole, 1-phenyl-1 ,2,3-
triazole, 4-methyl-2-
pheny1-1,2,3-triazole, 1- benzy1-1,2,3-triazofe, 4-hydroxy-1,2,3-triazole, 1-
amino-1,2,3-triazole,
1-benzamido-4-methyl-1,2,3-triazole, 1-
amino-4,5-dipheny1-1,2,3-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-dipheny1-1,2,4-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-merca.ptobenzothiazole, 2,5-climercapto-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 I -be nzotriazo leoarboxyrate,
hydroxyphenyl)benzotriazole, or combinations thereof. In certain embodiments,
the amount of
azoie compound present in the eiectrodepositable coating composition is ?. 0.5
weight % based
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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 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
electrodepositabie 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
100251 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,
[00261 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
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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).
100271 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 DESOPHANETM (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.
100291 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.
100301 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
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amount such as to render the clear coating composition opaque (not
substantially transparent)
after it has been cured. Any clearcoat coating composition known in the art
may be used in the
present invention. For example, the clearcoat coating composition that is
described in U.S.
Patent Nos. 51989,642, 612451855, 61387,519, and 710051472 can be used in the
coating
system. In certain embodiments, the substantially clear coating composition
can also comprise
a particle, such as e 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.
100321 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.
100331 Example colorants include pigments, dyes and tints, such as those
used in the
paint industry and/or listed in the Dry Color Manufacturers Association
(DCIVIA), 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,
100341 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
phthalooyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole,
thioindigo,
anthrequinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone,
anthanthrone,
dioxazine, triarylcarbonium, quinophthaforie pigments, diketo pyrrolo pyrrole
red ("DPPBO
red"), titanium dioxide, carbon black and mixtures thereof. The terms
"pigment" and "colored
filler" can be used interchangeably.
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,
100351
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.
100361
Example tints include, but are not limited to, pigments dispersed in
water-based
or water miscible carriers such as AQUA-CHEMTm 896 commercially available from
Degussa,
Inc., CHARISMA COLORANTS and MAXITONER INDUSTRIAL COLORANTS commercially
available from Accurate Dispersions division of Eastman Chemical, Inc.
[003711
As noted above, the colorant can be in the form of a dispersion
including, but
not limited to, a nanoparticle dispersion. Nanoparticle dispersions can
include one or more
highly dispersed nanoparticle colorants and/or colorant particles that produce
a desired visible
color and/or opacity and/or visual effect. Nanoparticle dispersions can
include colorants such
as pigments or dyes having a particle size of less than 150 nm, such as less
than 70 nm, or
less than 30 nm. Nanoparticles can be produced by milling stock organic or
inorganic pigments
with grinding media having a particle size of less than 0.5 mm. Example
nanoparticle
dispersions and methods for making them are identified in U.S. Patent No.
6,875,800.
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 June 24, 2004, U.S. Provisional Application
No. 60/482,167,
filed June 24, 2003, and United States Patent Application Serial No.
11/337,062, filed January
20, 2006.
[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
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compositions are identified in U.S. Patent 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.
00391 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 BO
seconds. Example photochromic and/or photosensitive compositions include
photochromic
dyes.
[00401 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 US.
Application
Serial No. 10/892,9'19, filed July 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 66
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.
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10042]
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 cosoivents,
catalysts, including
phosphonic acids and other customary auxiliaries.
10043] 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"
("1r), "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 10
C. In other embodiments, the curing operation can be carried out at
temperature 5. 246 C. In certain embodiments, the curing operation can carried
out at
temperatures ranging between any combination of values, which were recited in
the preceding
sentences, inclusive of the recited values. For example, the curing operation
can be carried
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out at temperatures ranging from 120 C - 150 C. It should be noted, however,
that lower or
higher temperatures may be used as necessary to activate the curing
mechanisms.
[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 C to
120 C, such as 5 C to 80 C, in some cases 10 C to 60 C and, in yet other
cases, 15 C to
40 C.
[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 125
microns,
such as 5 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
[00491
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 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 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 TM X-100 (available from The Dow Chemical Company) and
11.1 grams
of TRITONTm CF-10 (available from The Dow Chemical Company) to five gallons of
volume
with deionized water, and then neutralizing to pH 3.0 with CHEMFILTm 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.
12
CA 02754819 2013-04-17
[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 C. After
electrodeposition,
the panels were all baked at 93 C (200 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 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 C for one hour. As the mixture was allowed to cool
to 88 C, 51.3
parts of EKTASOLVETm EEH solvent and 23.2 parts of 2-n-butoxy-1-ethanol were
added. At
88 C, a slurry consisting of 32.1 parts of 85% o-phosphoric acid, 18.9 parts
phenylphosphonic
acid, and 6.9 parts of EKTASOLVETm EEH was added. The reaction mixture was
subsequently
maintained at a temperature of at least 120 C for 30 minutes. At that point,
the mixture was
cooled to 100 C and 71.5 parts of deionized water was gradually added. Once
the water was
added, a temperature of about 100 C was maintained for 2 hours. Then the
reaction mixture
was cooled to 90 C and 90.0 parts of diisopropanolamine was added, followed by
413.0 parts
of CYMELTm 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 C.
[0052] The electrodeposition bath was prepared as follows:
Ingredients Parts by Weight
Phosphated epoxy resin dispersion 1522
Pigment paste' 331
Deionized water 1947
'Grey 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.
13
CA 02754819 2013-04-17
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 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 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 TRITONTm X-100 (available from The Dow Chemical Company) and
11.1 grams
of TRITONTm CF-10 (available from The Dow Chemical Company) to five gallons of
volume
with deionized water, and then neutralizing to pH 3.0 with CHEMFILTm 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 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 eiectrocoated 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 C. After
electrodeposition,
the panels were all baked at 93 C (200 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 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 C for one hour. As the mixture was allowed to cool
to 88 C, 51.3
parts of EKTASOLVETm EEH solvent and 23.2 parts of 2-n-butoxy-1-ethanol were
added. At
88 C, a slurry consisting of 32.1 parts of 85% o-phosphoric acid, 18.9 parts
phenylphosphonic
acid, and 6.9 parts of EKTASOLVETm EEH was added. The reaction mixture was
subsequently
maintained at a temperature of at least 120 C for 30 minutes. At that point,
the mixture was
14
CA 02754819 2011-09-08
WO 2010/117479 PCT/US2010/022206
cooled to 100 C and 71,5 parts of deionized water was gradually added. Once
the water was
added, a temperature of about 100 C was maintained for 2 hours, Then the
reaction mixture
was cooled to 90 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 C.
190571 A resinous blend of the above-described phosphated epoxy resin was
prepared
as follows:
Ingredients Parts by Weight
Phosphated epoxy resin dispersion of 1522
Example 1 + corrosion inhtor
Pigment pastel ----------------------------------------- 331
Deionized water 1947
'Grey pigment paste, ACPP-1120, available from PPG Industries, Inc.,
50% solids,
100581 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.
õ.
Test Result Summar/
[00591 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.
