Title of Invention

A COMPOUND AND A METHOD OF COATING A METAL

Abstract The invention relates to a composition of matter of formula: where R is H or C1-C6 alkyl.
Full Text COMPOSITION FOR COATING OF ALUMINUM
FIELD OF THE INVENTION
This invention is in the field of coatings for metals. The coating is useful on
aluminum and aluminum alloys.
BACKGROUND OF THE INVENTION
Aluminum and aluminum alloy metals typically need to be coated otherwise
they rust or display other undesirable effects from exposure to atmosphere and
moisture.
Chromating has been the method of choice in aluminum finishing and
aerospace industry for pretreating of all types of aluminum alloys for many decades.
The chromate conversion coating formed on aluminum surface serves two basic
purposes: stand-alone temporary protection of the metal against corrosion and as a base
for adhesion to paint overcoat. The former is achieved via electrochemical and barrier
passivation of aluminum by an Al2O3-Cr2O3 mixed oxide layer, and the latter owes, in
large part, to increased surface area of chromated surface. The chromating reaction
proceeds by Cr(VI) oxidizing the Al to Al (III), which forms an amorphous mixed
oxide layer. This reaction is by no means stoichiometric, and excess Cr(VI) are often
present in the resultant oxide film. When fresh metal surface is exposed as a result of
physical impact and at suitable humidity levels, the remnant Cr(VI) in the film can
slowly leach out to oxidize and seal the "wound", a phenomenon known as "self-
healing". Nonetheless, use of chromates is under ever-tightening regulations because
chromate has been identified as a human carcinogen.
Exploring health/environment-benign alternatives to chromates with
comparable corrosion protection performance has been underway for well over a

decade. To date, the new types of chemistry investigated have only partially met the
goal. Those proposed new conversion coatings often necessitate using other transition
metals (although less toxic), and/or fail to meet the same performance standard set by
chromates in terms of both stand-alone protection and paint adhesion.
Among different conversion coating systems examined, silane-based one
possesses several valuable characteristics. Silane based coatings are completely metal-
free (therefore truly "green"), and they can covalently bind the paint to the metal,
leading to superior paint adhesion. Organofunctional silanes have long been used as
coupling agents for binding two surfaces of different chemistries, such as fiberglass to
plastics and rubber to metals. Commonly referred to as "organic-inorganic hybrid"
compounds, organofunctional silanes have reactive organic functional groups on one
end (such as epoxy, amino, acryl, etc.) and hydrolysable alkoxysilyl groups on the
other. Coupling to paint resins is effected via reaction between the organic functional
groups of the silane and those of resin molecules; while coupling to metal surfaces
occurs via formation of metal-oxygen-silicon, or M-O-Si bonds, where M is equal to
metal. When applied from water solution at acidic pH, the hydrophobic alkoxysilyl
group of the silane hydrolyzes to hydrophilic silanol groups that are more compatible,
in terms of surface energy, with that of hydrophilic metal oxide surfaces.
Investigation on using silane coupling agents as replacement to chromates has
been pioneered by Van Ooij et al. Initial efforts of other research groups were largely
confined to monofunctional silane, i.e., silane with one hydrolysable alkoxysilyl group.
Monofunctional silane - X-R-Si-(OR')3, where X is the organic functional group, tends
to form a linear siloxane polymer with pendant silanol groups upon controlled

hydrolysis. This might suggest that further condensation via those pendant silanols
should give rise to a well crosslinked barrier film. However, it was found that the
property of monofunctional silane-derived coating is hardly satisfactory without using
additional crosslinkers such as tetraethoxysilane (TEOS) or tetravalent Zr, and the
applicable life of the coating solution is very short. Problematic still, in diluted water
solutions, the monofunctional silanes also tend to form a monolayer on hydroxylated or
silaceous surfaces via M-Si-O bonds, leaving no -Si(OR')3 groups available to
crosslink with other silane molecules and unable to build up a thicker film that is
essential to corrosion protection.
The Van Ooij group has determined that multifunctional silanes (silanes with
more than one alkoxysilyl groups) are much effective at forming protection layer on
aluminum. This finding underscores the importance of film-forming properties of the
silanes when it comes to corrosion protection of unpainted metals. It is believed,
without intending to be bound thereby, that corrosion of a coated metal surface
involves diffusion of corrosive species from environment to the paint/metal interface,
which can be hindered when the diffusion path is made tortuous and diffusivity
reduced by high degree of crosslinking of the coating layer.
The situation is very different in the case of Afunctional silanes, denoted as
(R'O) 3-Si-R-Si-(OR')3, where R is a bridging group with or without heteroatoms. This
bifunctional silane is capable of covalently binding to the native metal oxide on metal
surfaces through one of the two alkoxysilyl groups and of condensing/crosslinking
among themselves through the other. The nature of thus crosslinked matrix is no longer
that of a siloxane, but of an organic/inorganic hybrid material.

Bis-type silanes reported in literature for use in corrosion protection of metals
include bis-(3-triethoxysilylpropyl)tetrasulfane(BTSPS), bis-1,2-[triethoxysilyl]ethane
(BTSE), bis-l,2-[trimethoxylsilylpropyl]amine (BTSPA), all of which are
commercially available. BTSE was the first bisfunctional silane explored and was soon
discarded due to lack of reactive organic functional groups on the backbone ethylene
group that is essential for paint adhesion. The sulfidesilane -BTSPS had been
investigated as a protection layer on various grades of steel and aluminum alloys. A
series of corrosion tests including neutral and copper accelerated salt spray, paint
adhesion, hot salt immersion, as well as several electrochemical characterization
demonstrated that overall performance of BTSPS is equivalent to, sometimes better
than that of chromate conversion coating. It is believed that interaction between the
sulfide -(S4)- and Fe atom significantly contributes to the electrochemical passivation
of steel, and interaction between S4 group and topcoat functional residues enhances the
adhesion of the silane layer to paints and rubbers. Although BTSPS also protects
aluminum and zincated surfaces as well as it does to steel, it suffers two major
drawbacks. It is solvent-borne and requires lengthy (often days of) hydrolysis prior to
application due to its high hydrophobicity. Furthermore, although the bisamino silane -
BTSPA is totally water soluble without any organic solvent, its corrosion protection
performance of unpainted aluminum is far inferior to that of tetrasulfide silane. This
can be partially explained by its lower hydrophobicity due to the presence of
hydrophilic secondary amine group. Adding vinyltriacetoxylsilane - VTAS to BTSPA
solution helps raise its performance to a certain degree, but the vinyl silane is not stable
in water and is observed to slowly condense and precipitate out of solution over time.

The key to a successful silane-based metal pretreatment process lies in
identifying a multifunctional silane with an ideal combination of water solubility (a
practical issue), hydrophobicity (for best corrosion protection), high crosslinking
capabilities (barrier to diffusion of corrosive species), slow rate of condensation (long
solution life), and reactivity (for paint adhesion). However, neither tetrasulfide nor
bisamino silane can meet all five requirements, nor can any current commercial silanes.
Therefore, it would be desirable to identify new metal coatings that are useful to coat
aluminum and aluminum alloys.
SUMMARY OF THE INVENTION
The first aspect of the instant claimed invention is a composition of matter of
formula

where R is H or Ci - C6 alkyl.

The second aspect of the instant claimed invention is a composition of matter
of formula TG 14-R:

where R is H or C| - C6 alkyl.
The third aspect of the instant claimed invention is a method of coating metal
comprising
a) cleaning the surface of the metal with a cleaner;
b) coating the surface of the metal with a Coating Mixture; and
c) thermally annealing the Coating Mixture on the surface of the metal to form
a crosslinked coating;
wherein the Coating Mixture comprises a composition of matter of formula
TG13-R:


where R is H or C1-C6 alkyl;
or a composition of matter of formula TG14-R:


where R is H or Ci-C6 alkyl; or a combination thereof; and
where the metal is aluminum or an aluminum alloy.
The fourth aspect of the invention is a method of coating a metal comprising (a)
optionally cleaning the surface of the metal with a cleaner; (b) coating the
surface of the metal with a Coating Mixture; and (c) thermally annealing the
Coating Mixture on the surface of the metal to form a crosslinked coating;
wherein the Coating Mixture comprises a composition of matter of formula:



where R is H or Q-C6 alkyl; or a combination thereof; and
wherein the metal is aluminum or an aluminum alloy.
DETAILED DESCRIPTION OF THE INVENTION
Throughout this patent application, the following terms have the indicated
meanings. "Alkyl" means a monovalent group derived from a straight chain
saturated hydrocarbon by the removal of a single hydrogen atom. d-C6 Alkyl
means alkyl selected from the group consisting of methyl, ethyl, n-propyl, n-
butyl, n-pentyl and n- hexyl.
"Nalco" means Nalco Company, 1601 W. Diehl Road, Naperville, IL 60563. (630)
305-1000.

The first aspect of the instant claimed invention is a composition of matter of
formula TGI3-R:

Where R is H or Ci-C6 alkyl,

TG13-R is formed by reacting an epoxy silane and an aliphatic diamine in a
molar ratio of 3:1 epoxy silane to aliphatic diamine.
When R is methyl, the epoxy silane is 3-glycidoxypropyltrimethoxysilane and
the aliphatic diamine is C,C,C,-trimethyl-1,6-hexanediamine.
When R is ethyl, the epoxy silane is 3-glycidoxypropyltriethoxysilane and the
aliphatic diamine is C,C,C,-trimethyl-l,6-hexanediamine.
When R is n-propyl, the epoxy silane is 3-glycidoxypropyltripropoxysilane and
the aliphatic diamine is C,C,C,-trimethyl-l,6-hexanediamine.
When R is n-butyl, the epoxy silane is 3-gIycidoxypropyItributoxysilane and the
aliphatic diamine is C,C,C,-trirnethyl-l,6-hexanediamine.
When R is n-pentyl, the epoxy silane is 3-glycidoxypropyltripentoxysilane and
the aliphatic diamine is C,C,C,-trimethyl-1,6-hexanediamine.
When R is n-hexyl, the epoxy silane is 3-glycidoxypropyltrihexoxysilane and
the aliphatic diamine is C,C,C,-trimethyl-l,6-hexanediamine.
C,C,C,-trimethyl-1,6-hexanediamine, 3-glycidoxypropyltrimethoxysilane and
3-glycidoxypropyltriethoxysilane are all available commercially. 3-
glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-
glycidoxypropyltripentoxysilane, and 3-glycidoxypropyltrihexoxysilane can be
synthesized using techniques known to people of ordinary skill in the art.
The reaction optimally takes place in an equal amount of a suitable solvent,
such as a suitable alcohol. Suitable alcohols include, but are not limited to, methyl
alcohol and ethyl alcohol. A preferred alcohol is methyl alcohol.

The mixture is allowed to react at room temperature, about 21 °C, for from
about 24 to about 48 hours. If time is an issue, the mixture is allowed to react at about
70°C for about 3 hours. For either synthetic route, the yield is high, usually above 95%
(on amine basis).
TG13-R and TG14-R can also be synthesized when R is hydrogen, abbreviated
"H". This synthesis involves first making TG13-R or TG14-R where R is C1-C6 alkyl
and then hydrolyzing TG13-R and TG14-R in water for from about 2 to about 24
hours. The composition of matter where R is H is a silanol, and silanols are known to
be relatively unstable. Therefore, if it is desired to make the composition of matter
where R is hydrogen, then it must be understood that this composition must be applied
to metal as soon as the synthesis has been completed.
The preferred composition of matter of formula TG13-R is when R is methyl.
This composition is depicted in formula TGI3.


The second aspect of the instant claimed invention is a composition of matter
of formula TG14-R:

where R is H or C1-C6 alkyl.
The composition of matter of formula TG14-R is formed by reacting an epoxy
silane and an aliphatic diamine in a molar ratio of 4:1 epoxy silane to aliphatic
diamine. The epoxy silane and aliphatic diamine are the same as for the synthesis of
TG13-R. The synthetic method is also the same as that for the synthesis of TG14-R,
with the change being in the molar ratio of epoxy silane to aliphatic diamine.
The preferred composition of matter of formula TG14-R is when R is methyl.
This composition is depicted in formula TG14.


A Coating Mixture comprising a composition of matter of formula TG13-R or a
composition of matter of formula TG14-R or a combination thereof has been found to
be useful in coating aluminum or aluminum alloys.
The third aspect of the instant claimed invention is a method of coating a metal
comprising
a) optionally cleaning the surface of the metal with a cleaner;
b) coating the surface of the metal with a Coating Mixture;
c) thermally annealing the Coating Mixture on the surface of the metal to form
a crossl inked coating;
wherein the Coating Mixture comprises a composition of matter of formula
TG13-R:


where R is H or C|-C6 alkyl;
or a composition of matter of formula TG14-R:


where R is H or C1-C6 alkyl;
or a combination thereof; and
wherein the metal is aluminum or an aluminum alloy.
The metals are selected from the group comprising aluminum and aluminum
alloys. Commercially available aluminum and aluminum alloys include, but are not
limited to, the following: sheet forming alloys 2024, 7075, 6061, 6111, 1100,
3003,3015, 5086, 5052 and cast forming alloy 356. These aluminum and aluminum
alloys are available from ACT Laboratory.
The surface of the metal may optionally be cleaned using techniques known in
the art of aluminum cleaning. In practice, it is preferred that the metal be cleaned
before it is coated with the Coating Mixture.
In order to make a composition of matter of either formula TG13-R or formula
TG14-R or a combination thereof water soluble, the formula must be neutralized with a
stoichiometric amount of suitable acid. One such suitable acid is acetic acid.
Once the composition of matter has been rendered water soluble, any coating
made therefrom should have low volatile organic compound ("VOC") emissions.
In addition to containing the composition of matter TG13R or TG14R or a
combination thereof, the Coating Mixture may contain other ingredients commonly
found in coatings used on aluminum or aluminum alloys. These ingredients may
include biocides, corrosion inhibitors, pigments, rheology modifiers and surfactants.
These formulated coatings may also include other functional ingredients known in the
metal coatings industry.

The Coating Mixture may be applied as a coating by any known coating method,
including dipping, spraying, brush application or any other coating technique.
In a typical coating process, the metal is
(a) cleaned,
(b) rinsed
(c) coated, and then
(d) thermally cured.
It is recommended that a coating thickness of at least from about 0.1 microns to
about 1.0 microns be applied to the surface of the aluminum or aluminum alloy. A very
useful feature of this Coating Mixture is that the Coating Mixture is compatible with
existing coating equipment.
The Coating Mixture on the surface of the metal is thermally annealed by
exposing the coated aluminum to heat for from about 10 minutes to about 16 hours, to
form a crosslinked coating. The amount of time for annealing within that range
depends upon the annealing temperature. Typical annealing temperatures range from
room temperature of about 20 °C to an elevated temperature of about 120°C. The
relationship between time and annealing temperature is this: the hotter the annealing
temperature, the less time it takes to anneal the coating and the cooler the annealing
temperature, the more time it takes to anneal the coating.
Another useful feature of this Coating Mixture is that the Coating Mixture,
as described herein, does not require any chromium metal to make it an effective
Coating Mixture.

Another useful feature of this Coating Mixture is that an aqueous 5% wt. solids
Coating Mixture, where R is Ci-C6 alkyl, and not H, has been found to exhibit stable
shelf life of at least about 3weeks without exhibiting any degradation of anticorrosion
performance for painted metal.
Another useful feature of the instant claimed invention is that an aqueous 5%
wt. solids Coating Mixture containing the TGI 4 composition of matter has been found
to yield a thin, clear coating, which is invisible to the eyes, and therefore does not
interfere with the metal's natural luster. Interference with the natural luster of the
metal has been found when a chromium containing coating is used.
It has been found that the Coating Mixture formed with a 4:1 epoxy silane-
aliphatic diamine molar ratio performed well in salt spray corrosion tests. Coatings
formed with the instant claimed Coating Mixtures exhibit an overall performance
comparable or superior to chrome-based conversion coatings for certain types of
aluminum alloys, either bare or painted.
The foregoing may be better understood by reference to the following
Examples, which are presented for purposes of illustration and are not intended to limit
the scope of this invention.
EXAMPLES
Example la
Synthesis of TGI 3
A 3:1 molar ratio of 3-glycidoxypropyItrimethoxysilane(GPS) and C,C,C-
trimethyl-1,6-hcxanediamine(TMH) is added to an equal weight of ethyl alcohol. The

mixture is allowed to react at 70 °C for 3 hours. The reaction products are
subsequently neutralized with a 20% excess (based on stoichiometry) of acetic acid.
Example lb
Testing of TGI 3
The neutralized silane concentrate of Example la is diluted with water to 5%
silane (by weight) and applied to aluminum panels by dip-coating.
The panels dip coated with this Coating Mixture are first baked in an oven at
120 °C for about 0.5 hours and then further coated with about 20 microns of white
polyester based paint, obtained from Sherwin Williams Coatings Company. The white
painted panels are then subjected to an ASTM Bl 17 condition Neutral Salt Spray
Corrosion test. After 3000 hours of salt spray, no paint loss or blistering is found along
the scribe lines.
The conclusion reaches is that the Coating Mixture comprising TG13 bonds the
paint to aluminum very well even when the aluminum is exposed to humid and
corrosive conditions.
Example 2
Example 2a
Synthesis of TGI 4
A 4:1 molar ratio of 3-glycidoxypropyltrimethoxysilane(GPS) and C,C,C-
trimethyl-l,6-hexanediamine(TMH) is added to an equal weight of ethyl alcohol. The
mixture is allowed to react at 70 °C for 3 hours. The reaction products are subsequently
neutralized with a 20% excess (based on stoichiometry) of acetic acid.

Example 2b
First Testing of TGI 4
The neutralized silane concentrate of Example 2a is diluted with water to 5%
silane (by weight) and applied to aluminum panels by dip-coating.
The coated aluminum panels are found to tolerate over 360 hours of salt spray
(tested according to ASTM Bl 17) without showing any signs of corrosion, equivalent
in performance to conventional chrome-based conversion coating.
In contrast to the results obtained using the Coating Mixture of the instant
claimed invention, bare Al panels start to corrode in 6 hours. Other commercially
available silane based coatings failed at 96 hours (bis-[trimethoxysilyl]amine and
vinyltriacetoxysilane mixture) and 240 hours (structures of 3-
glycidoxypropyltrimethoxysilane and N-(2-aminoethyl)3-
aminopropyltrimethoxysilane).
Example 2c
Second Testing of TGI 4
In a second test, the neutralized silane concentrate of Example 2a is diluted
with water to 5% silane (by weight) and applied to aluminum panels by dip-coating.
The panels dip coated with this TGI4 Coating Mixture are first baked in an oven at
120 °C for about 0.5 hours and then further coated with about 20 microns of white
polyester based paint, obtained from Sherwin Williams Coatings Company. The white
painted panels are then subjected to an ASTM Bl 17 condition Neutral Salt Spray
Corrosion test. After 3000 hours of salt spray, no paint loss or blistering is found along
the scribe lines.

Various changes and modifications to the presently preferred embodiments
described herein will be apparent to those skilled in the art. Such changes and
modifications can be made without departing from the spirit and scope of the present
invention and without diminishing its attendant advantages. It is therefore intended
that such changes and modifications be covered by the appended claims.

We Claim:
1. A composition of matter of formula:

where R is H or C1-C6 alkyl.
2. A composition of matter of formula:

where R is H or C1-C6 alkyl.

3. A composition of matter as claimed in claim 1 of formula :

4. A composition of matter as claimed in claim 2 of formula:


5. A method of coating a metal comprising
(a) optionally cleaning the surface of the metal with a cleaner;
(b) coating the surface of the metal with a Coating Mixture; and
(c) thermally annealing the Coating Mixture on the surface of the metal to form a
crosslinked coating;
wherein the Coating Mixture comprises a composition of matter of formula:

where R is H or C1-C6 alkyl;
or a composition of matter of formula:


where R is H or C1-C6 alkyl; or a combination thereof; and
wherein the metal is aluminum or an aluminum alloy.
6. The method as claimed in claim 5, wherein R is methyl.


The invention relates to a composition of matter of formula:

where R is H or C1-C6 alkyl.

Documents:

03946-kolnp-2006-abstract.pdf

03946-kolnp-2006-claims.pdf

03946-kolnp-2006-correspondence others-1.1.pdf

03946-kolnp-2006-correspondence others.pdf

03946-kolnp-2006-correspondence-1.2.pdf

03946-kolnp-2006-description(complete).pdf

03946-kolnp-2006-form-1-1.1.pdf

03946-kolnp-2006-form-1.pdf

03946-kolnp-2006-form-2.pdf

03946-kolnp-2006-form-26.pdf

03946-kolnp-2006-form-3.pdf

03946-kolnp-2006-form-5.pdf

03946-kolnp-2006-international publication.pdf

03946-kolnp-2006-international search authority report.pdf

03946-kolnp-2006-pct request form.pdf

3946-KOLNP-2006-ABSTRACT 1.1.pdf

3946-KOLNP-2006-ABSTRACT 1.2.pdf

3946-KOLNP-2006-AMANDED CLAIMS.pdf

3946-KOLNP-2006-CLAIMS.pdf

3946-KOLNP-2006-CORRESPONDENCE 1.1.pdf

3946-KOLNP-2006-CORRESPONDENCE.pdf

3946-KOLNP-2006-DESCRIPTION (COMPLETE) 1.1.pdf

3946-KOLNP-2006-DESCRIPTION (COMPLETE) 1.2.pdf

3946-KOLNP-2006-EXAMINATION REPORT.pdf

3946-KOLNP-2006-FORM 1 1.1.pdf

3946-KOLNP-2006-FORM 1-1.2.pdf

3946-KOLNP-2006-FORM 18.1.pdf

3946-kolnp-2006-form 18.pdf

3946-KOLNP-2006-FORM 2 1.1.pdf

3946-KOLNP-2006-FORM 2-1.2.pdf

3946-KOLNP-2006-FORM 26.pdf

3946-KOLNP-2006-FORM 3 1.1.pdf

3946-KOLNP-2006-FORM 3.pdf

3946-KOLNP-2006-FORM 5.pdf

3946-KOLNP-2006-FORM-27.pdf

3946-KOLNP-2006-GRANTED-ABSTRACT.pdf

3946-KOLNP-2006-GRANTED-CLAIMS.pdf

3946-KOLNP-2006-GRANTED-DESCRIPTION (COMPLETE).pdf

3946-KOLNP-2006-GRANTED-FORM 1.pdf

3946-KOLNP-2006-GRANTED-FORM 2.pdf

3946-KOLNP-2006-GRANTED-SPECIFICATION.pdf

3946-KOLNP-2006-OTHERS 1.1.pdf

3946-KOLNP-2006-OTHERS.pdf

3946-KOLNP-2006-OTHERS1.2.pdf

3946-KOLNP-2006-PETITION UNDER RULE 137.pdf

3946-KOLNP-2006-REPLY TO EXAMINATION REPORT.pdf

3946-KOLNP-2006-REPLY TO EXAMINATION REPORT1.2.pdf

abstract-03946-kolnp-2006.jpg


Patent Number 249749
Indian Patent Application Number 3946/KOLNP/2006
PG Journal Number 45/2011
Publication Date 11-Nov-2011
Grant Date 08-Nov-2011
Date of Filing 29-Dec-2006
Name of Patentee NALCO COMPANY
Applicant Address 1601, DIEHL ROAD NAPERVILLE, ILLINOIS 60563-1198
Inventors:
# Inventor's Name Inventor's Address
1 CUI, JI 2131 & 1/2 RIDGE AVENUE APT. IF, EVANSTON IL 60201 U.S.A
PCT International Classification Number C07F 7/02
PCT International Application Number PCT/US2005/022691
PCT International Filing date 2005-06-28
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/881,902 2004-06-30 U.S.A.