U.S. patent application number 10/706125 was filed with the patent office on 2005-04-07 for passivation composition and process for zinciferous and aluminiferous surfaces.
Invention is credited to Kelly, Timm L., Meagher, Kevin K., Sohi, Jasdeep.
Application Number | 20050072495 10/706125 |
Document ID | / |
Family ID | 32326361 |
Filed Date | 2005-04-07 |
United States Patent
Application |
20050072495 |
Kind Code |
A1 |
Sohi, Jasdeep ; et
al. |
April 7, 2005 |
Passivation composition and process for zinciferous and
aluminiferous surfaces
Abstract
In at least one embodiment, the present invention relates to a
process for the temporary anti-corrosive treatment of a metal
surface that consist predominantly of aluminum and/or zinc, said
process comprising a) placing the surface of the metal in contact
with an anti-corrosive composition comprising 2.0-400 g/L phosphate
ions, 0.5-400 g/L fluorometallate ions, and having a pH of between
1.0-4.0, for a time period of between 0.1-200 seconds, b) drying
the anti-corrosive treatment composition on the metal surface to
form a primary passivating coating on the metal surface, c)
removing the primary passivating coating from the metal surface,
and d) conversion coating the metal surface. In certain
embodiments, the phosphate solution comprises phosphoric acid and
the fluorometallate solution comprises hexafluorotitanic acid.
Inventors: |
Sohi, Jasdeep; (Shelby
Township, MI) ; Kelly, Timm L.; (Birmingham, MI)
; Meagher, Kevin K.; (Northville, MI) |
Correspondence
Address: |
BROOKS KUSHMAN P.C./ HENKEL CORPORATION
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075-1238
US
|
Family ID: |
32326361 |
Appl. No.: |
10/706125 |
Filed: |
November 12, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60426477 |
Nov 15, 2002 |
|
|
|
Current U.S.
Class: |
148/254 ;
148/277 |
Current CPC
Class: |
C23C 22/361 20130101;
C23C 22/73 20130101 |
Class at
Publication: |
148/254 ;
148/277 |
International
Class: |
C23C 022/60 |
Claims
What is claimed is:
1. A method for the temporary anti-corrosive treatment of a metal
surface that consist predominantly of aluminum and/or zinc, said
process comprising: a) placing the surface of the metal in contact
with an anti-corrosive composition comprising 2.0-400 g/L phosphate
ions, 0.5-400 g/L fluorometallate ions, and having a pH of between
1.0-4.0, for a time period of between 0.1-200 seconds; b) drying
the anti-corrosive treatment composition on the metal surface to
form a primary passivating coating on the metal surface; c)
removing the primary passivating coating from the metal surface;
and d) conversion coating the metal surface.
2. The method of claim 1 wherein the ratio of fluorometallate
anions and phosphate ions is 0.10:1.0 to 5.0:1.0.
3. The method of claim 1 wherein the phosphate ions are provided in
a 75% by weight phosphate solution, based on the total weight of
the phosphate solution, and the fluorometallate ions are provided
in a 50% by weight fluorometallate solution, based on the total
weight of the fluorometallate solution.
4. The method of claim 3 wherein the phosphate solution is present
in the composition in an amount of 25-65 wt. % and the
fluorometallate solution is present in the composition in an amount
of 35-75 wt. %, based on the total weight of the composition.
5. The method of claim 4 further comprising water present in an
amount of 2 to 50 wt. %, based on the total weight of the
composition.
6. The method of claim 3 wherein the phosphate solution comprises
phosphoric acid and the fluorometallate solution comprises
hexafluorotitanic acid.
7. The method of claim 6 wherein the phosphoric acid is present in
the composition in an amount of 1.0-15.0 wt. %, based on the total
weight of the composition, and the hexafluorotitanic acid is
present in an amount of 1.0-20.0 wt. %, based on the total weight
of the composition, and the composition further comprising water
present in an amount of 45-98 wt. %, based on the total weight of
the composition.
8. The method of claim 1 wherein the metal surface comprises steel
treated with a galvanic coating comprising aluminum, zinc and
silicon.
9. The method of claim 1 wherein the metal surface comprises steel
treated with a galvanic coating comprising 55% aluminum, 43.5% zinc
and 1.5% silicon.
10. The method of claim 1 wherein the temperature of the
composition during step a) is 15-66.degree. C.
11. The method of claim 1 wherein the primary passivating coating
method surface is stored after step b) and prior to step c).
12. The method of claim 1 wherein the removal of step c) takes
place by exposing the primary passivating coating to an alkaline
solution.
13. A chromium-free, anti-corrosive composition for temporarily
passivating metal surfaces consisting predominantly of aluminum
and/or zinc, said composition comprising: 2.0-400 g/L phosphate
ions; and 0.5-400 g/L fluorometallate anions; the composition
having a pH of 1.0-4.0.
14. The composition of claim 13 wherein the ratio of
fluorometallate anions and phosphate ions is 0.10:1.0 to
5.0:1.0.
15. The composition of claim 13 wherein the phosphate ions are
provided in a 75% by weight phosphate solution, based on the total
weight of the phosphate solution, and the fluorometallate ions are
provided in a 50% by weight fluorometallate solution, based on the
total weight of the fluorometallate solution.
16. The composition of claim 15 wherein the phosphate solution is
present in the composition in an amount of 25-65 wt. % and the
fluorometallate solution is present in the composition in an amount
of 35-75 wt. %, based on the total weight of the composition.
17. The composition of claim 16 further comprising water present in
an amount of 2 to 50 wt. %, based on the total weight of the
composition.
18. The composition of claim 15 wherein the phosphate solution
comprises phosphoric acid and the fluorometallate solution
comprises hexafluorotitanic acid.
19. The composition of claim 18 wherein the phosphoric acid is
present in the composition in an amount of 1.0-15.0 wt. %, based on
the total weight of the composition, and the hexafluorotitanic acid
is present in an amount of 1.0-20.0 wt. %, based on the total
weight of the composition, and the composition further comprising
water present in an amount of 45-98 wt. %, based on the total
weight of the composition.
20. The composition of claim 19 further comprising a polymer
solution comprising a polymer comprising the Mannich adduct of
polyhydroxystyrene with N-methylglucamine.
21. The composition of claim 20 wherein the polymer solution
further comprises an acid selected from the group consisting of
fluorotitanic acid and fluorozirconic acid.
Description
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/426,477, filed on Nov. 15, 2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] In at least one aspect, the present invention relates to
compositions and processes for passivating, i.e., forming a
corrosion protective surface layer, on metal surfaces that consist
predominantly of aluminum and/or zinc. A wide variety of such
surfaces are in normal use, including many kinds of galvanized
and/or aluminized steel, and the invention is applicable to such
surfaces which differ from the underlying metal, as well as to
solid alloys of aluminum and/or zinc.
[0004] 2. Background Art
[0005] Zinc (zinciferous) and zinc alloy (such as aluminiferous)
coatings are frequently used to protect steel from corrosion. Two
common types of metal-coated steel typically used are galvanized
steel (zinc) and Galvalume.RTM. (55% Al, 43.5% Zn, 1.5% Si). Both
galvanized steel and Galvalume.RTM. have long service lifetimes as
a result of galvanic and/or sacrificial corrosion protection
afforded by the coatings. While the underlying steel is protected,
the zinc coating is sometimes susceptible to corrosion that can
result in surface staining and white corrosion.
[0006] Traditionally, most zinciferous and/or aluminiferous
surfaces have been passivated by chemical treatment with aqueous
liquid compositions containing at least some hexavalent chromium.
However, the adverse environmental effects of hexavalent chromium
that have come to public attention in recent years have resulted in
development of alternative, chromium-free compositions for this
purpose. As such, what is needed is a composition and process for
passivating metal surfaces that consist predominantly of aluminum
and/or zinc that overcomes at least one constraint in the prior
art.
SUMMARY OF THE INVENTION
[0007] In at least one aspect of the invention, an entirely or
substantially chromium-free composition and process for passivating
is provided that provides adequate corrosion resistance in
comparison with previously used chromate containing passivating
agents.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0008] Reference will now be made in detail to presently preferred
compositions or embodiments and methods of the invention, which
constitute the best modes of practicing the invention presently
known to the inventors.
[0009] It has been found that one or more of the objects stated
above for the invention can be achieved by the use of a passivating
aqueous liquid composition that comprises, preferably consists
essentially of, or more preferably consists of, water and:
[0010] (A) dissolved phosphate anions; and
[0011] (B) dissolved fluorometallate anions selected from the group
consisting of TiF.sub.6.sup.-2, ZrF.sub.6.sup.-2, HfF.sub.6.sup.-2,
SiF.sub.6.sup.-2, AlF.sub.6.sup.-3, GeF.sub.6.sup.-2,
SnF.sub.6.sup.-2, BF.sub.4.sup.-, and mixtures thereof.
[0012] The above composition may optionally further comprises one
or more of the following:
[0013] (C) an amino-phenolic polymer component;
[0014] (D) a pH adjusting component; and
[0015] (E) a wetting agent.
[0016] Various embodiments of the invention include working
compositions for direct use in treating metals, make-up
concentrates from which such working compositions can be prepared
by dilution with water, replenisher concentrates suitable for
maintaining optimum performance of working compositions according
to the invention, processes for treating metals with a composition
according to the invention, and extended processes including
additional steps that are conventional per se, such as cleaning,
rinsing, and subsequent painting or some similar overcoating
process that puts into place an organic binder-containing
protective coating over the metal surface treated according to a
narrower embodiment of the invention. Articles of manufacture
including surfaces treated according to a process of the invention
are also within the scope of the invention.
[0017] Except in the operating examples, or where otherwise
expressly indicated, all numerical quantities in this description
indicating amounts of material or conditions of reaction and/or use
are to be understood as modified by the word "about" in describing
the broadest scope of the invention. Practice within the numerical
limits stated is generally preferred. Also, unless expressly stated
to the contrary: percent, "parts of", and ratio values are by
weight; the term "polymer" includes "oligomer", "copolymer",
"terpolymer", and the like; the description of a group or class of
materials as suitable or preferred for a given purpose in
connection with the invention implies that mixtures of any two or
more of the members of the group or class are equally suitable or
preferred; description of constituents in chemical terms refers to
the constituents at the time of addition to any combination
specified in the description, and does not necessarily preclude
chemical interactions among the constituents of a mixture once
mixed; specification of materials in ionic form implies the
presence of sufficient counter-ions to produce electrical
neutrality for the composition as a whole (any counter-ions thus
implicitly specified should preferably be selected from among other
constituents explicitly specified in ionic form, to the extent
possible; otherwise such counter-ions may be freely selected,
except for avoiding counter-ions that act adversely to the objects
of the invention); the first definition of an acronym or other
abbreviation applies to all subsequent uses herein of the same
abbreviation and applies mutatis mutandis to normal grammatical
variations of the initially defined abbreviation; the term "paint"
includes all like materials that may be designated by more
specialized terms such as lacquer, enamel, varnish, shellac,
topcoat, and the like; and the term "mole" and its variations may
be applied to elemental, ionic, and any other chemical species
defined by number and type of atoms present, as well as to
compounds with well defined molecules.
[0018] For a variety of reasons, it is sometimes preferred that
compositions according to the invention as defined above should be
substantially free from many ingredients used in compositions for
similar purposes in the prior art. Specifically, when maximum
storage stability of a concentrate, avoidance of possibly
troublesome anions, and/or minimization of pollution potential is
desired, it is preferred, with increasing preference in the order
given, independently for each preferably minimized component listed
below, that these compositions contain no more than 25, 15, 9, 5,
3, 1.0, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002
percent of each of the following constituents: nitrite; halates and
perhalates (i.e., perchlorate, chlorate, iodate, etc.);
hydroxylamine and salts and complexes of hydroxylamine; chloride;
bromide; iodide; organic compounds containing nitro groups;
hexavalent chromium; ferricyanide; ferrocyanide; and pyrazole
compounds. Components such as these may not be harmful in some
instances, but they have not been found to be needed or
advantageous in compositions according to this invention, and their
minimization is therefore normally preferred at least for reasons
of economy.
[0019] The dissolved phosphate ions that constitute necessary
component (A) may be obtained from a variety of sources as known in
the art. Normally much of the phosphate content will be supplied by
phosphoric acid added to the composition, and the stoichiometric
equivalent as phosphate ions of all undissociated phosphoric acid
and all its anionic ionization products in solution, along with the
stoichiometric equivalent as phosphate ions of any dihydrogen
phosphate, monohydrogen phosphate, or completely neutralized
phosphate ions added to the composition in salt form, are to be
understood as forming part of phosphate ions component (A),
irrespective of the actual degree of ionization and/or reaction to
produce some other chemical species that exists in the composition.
If any metaphosphoric acid, other condensed phosphoric acids, or
salts of any of these acids are present in the compositions, their
stoichiometric equivalent as phosphate is also considered part of
component (A). Generally, however, it is preferred, at least partly
for reasons of economy, to utilize orthophosphoric acid and its
salts as the initial source for component (A).
[0020] In a working passivating aqueous liquid composition
according to the invention, the concentration of phosphate ions
and/or their stoichiometric equivalents as noted above preferably
is at least, with increasing preference in the order given, 2.0,
3.0, 4.0, 5.0, 6.0, 7.0, 9.0, 10.0, 12.0, 13.0, 14.0, 15.0, 16.0 or
17.0 grams per liter (hereinafter usually abbreviated as "g/L") of
total composition and independently preferably is not more than,
with increasing preference in the order given, 400, 200, 100, 90,
80, 75, 70, 60, 50, 45, 40 or 34 g/L.
[0021] The dissolved fluorometallate anions that constitute
necessary component (B) preferably are selected from the group
consisting of TiF.sub.6.sup.-2, ZrF.sub.6.sup.-2, HfF.sub.6.sup.-2,
SiF.sub.6.sup.-2, AlF.sub.6.sup.-3, GeF.sub.6.sup.-2,
SnF.sub.6.sup.-2, BF.sub.4.sup.-, and mixtures thereof, with the
first two being more preferred and fluorotitanate being the most
preferred. Such anions may be introduced into a treatment
composition according to the invention as acids or salts, with the
acids usually preferred for economy and because a net acidity of
the compositions is preferable as considered further below, and the
entire stoichiometric equivalent as any of the above recited
fluorometallate ions in any source material as dissolved in a
composition according to the invention or a precursor composition
for it is to be considered as part of the fluorometallate
component, irrespective of the actual degree of ionization that may
occur. Independently of their chemical nature, the total
concentration of the fluorometallate anions dissolved in a working
treatment composition according to the invention preferably is at
least, with increasing preference in the order given, 0.5, 1.0,
2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 7.5, 8.5, 10.0, 11.0, 12.0 or 13.0
g/L and independently, primarily for reasons of economy, preferably
is not more than, with increasing preference in the order given,
400, 200, 100, 90, 80, 75, 65, 50, 45, 38, 37.5, 35.0, 32.5 30.0,
28.0, 27.0 or 26.0 g/L.
[0022] Furthermore, independently of their actual concentrations,
the concentrations of fluorometallate anions (B) and phosphate ions
(A) preferably are such that the ratio between them, in working
compositions and concentrated solutions used to prepare working
concentrations, is at least, with increasing preference in the
order given, 0.10:1.0, 0.15:1.0, 0.25:1.0, 0.35:1.0, 0.45:1.0,
0.50:1.0, 0.55:1.0, 0.60:1.0, 0.65:1.0, or 0.75:1.0 and
independently preferably is not more than, with increasing
preference in the order given, 5:1.0, 4:1.0, 3.5:1.0, 3.2:1.0,
2.0:1.0, 1.5:1.0, 1.0:1.0, or 0.9:1.0.
[0023] The composition of the present invention also optionally
includes an amino-phenolic polymer component (C). Suitable examples
of such polymers include Mannich adducts of secondary amines
containing a carbon chain with at least one hydroxy group,
formaldehyde, and a polyphenolic resin. In some embodiments,
polymer composition (C) is selected from the group consisting of
water soluble and water dispersible polymers and copolymers of one
or more x-(N--R.sup.1--N--R.sup.2-aminomethyl)-4-hydrox-
y-styrenes, where x=2, 4, 5, or 6, R.sup.1 represents an alkyl
group containing from 1 to 4 carbon atoms, preferably a methyl
group, and R.sup.2 represents a substituent group conforming to the
general formula H(CHOH).sub.nCH.sub.2--, where n is an integer from
1 to 7, preferably from 3 to 5. Certain preferred polymers are
Mannich adducts of polyvinyl phenol that are described in more
detail in U.S. Pat. Nos. 4,376,000; 4,433,015; 4,457,790;
4,517,028; 4,963,596; 4,970,264; 5,039,770; 5,068,299; 5,116,912;
5,266,410; 5,298,289; and 5,891,952, the entire disclosure of each
patent, except to the extent contrary to any explicit statement
herein, is hereby incorporated herein by reference. In certain
embodiments, the polymer component (C) is the Mannich adduct of
polyhydroxystyrene with N-methylglucamine. Polymer (C), in some
embodiments, can also be added as a solution of the polymer
component with an acid, such as fluorotitanic acid, phosphoric
acid, and fluorozirconic acid. In these embodiments, the
concentrations of polymer (C) and the acid in the polymer (C)/acid
solution preferably are such that the ratio between them is at
least, with increasing preference in the order given, 1.0:1.0,
2.0:1.0, 3.0:1.0, 4.0:1.0, 5.0:1.0, 5.0:1.0 or 6.5:1.0, and
independently preferably is not more than, with increasing
preference in the order given, 50:1:0, 40:1.0, 30:1.0, 25:1.0,
15:1.0, 10:1.0, 9.0:1.0, 8.0:1.0 or 7.5:1.0. When polymer (C) is
used, independently of their chemical nature, the total
concentration of the polymer (C) dissolved in a working treatment
composition according to the invention preferably is at least, with
increasing preference in the order given, 0.1, 0.25, 0.50, 0.75,
1.0, 1.25, 1.50 or 1.70 g/L of total composition and independently
preferably not more than, with increasing preference in the order
given, 150, 100, 75, 50, 25, 15 or 13 g/L. The optimal amount of
polymer (C) depends in large part on the desired end property of
the coating. If relatively significant corrosion protection is
considered more important than ease of coating removability, then a
relatively higher amount of polymer (C) can be used, however, if
ease of coating removability is considered more important than
corrosion protection, then a relatively smaller amount of polymer
(C) can be used.
[0024] Furthermore, when polymer (C) is used, independently of
their actual concentrations, the concentrations of polymer (C) and
phosphate anions (A) preferably are such that the ratio between
them, in working compositions and concentrated solutions used to
prepare working concentrations, is at least, with increasing
preference in the order given, 0.005:1.0, 0.01:1.0, 0.015:1.0,
0.02:1.0, 0.025:1.0, 0.03:1.0, 0.035:1.0, 0.04:1.0, 0.045:1.0 or
0.05:1.0, and independently preferably is not more than, with
increasing preference in the order given, 1.2:1.0, 1.0:1.0,
0.90:1.0, 0.75:1.0, 0.60:1.0, 0.50:1.0, 0.45:1.0, 0.35:1.0,
0.25:1.0, 0.20:1.0, 0.10:1.0 or 0.07:1.0.
[0025] The pH of the treatment bath should be from 1.0 to 4.0, more
preferably 1.2 to 2.5, and most preferably from 1.5 to 2.0. A pH
below 1.0 may result in an overly strong etch and scanty coating
formation. At a pH in excess of 4.0, the solution may have a
pronounced tendency to form precipitates, which can result in a
shortened bath life. The pH can be adjusted using a pH adjusting
component (D) such as an acid such as phosphoric acid, or nitric
acid, or a base such as sodium hydroxide, potassium hydroxide,
sodium carbonate, or ammonium hydroxide, with ammonium hydroxide
being the most preferred. When the pH adjusting component (D) is
used, independently of their chemical nature, the total
concentration of pH adjusting component (D) dissolved in a working
treatment composition according to the invention preferably is at
least, with increasing preference in the order given, 1.0, 5, 10,
15, 20, 25, 30, or 32.5 g/L of total composition, and independently
preferably not more than, with increasing preference in the order
given, 100, 90, 80, 75, 70, 60, 50, or 45 g/L.
[0026] The composition of the present invention also optionally
includes a wetting agent (E). The wetting agent (E) is particularly
useful for wetting surfaces that are known to be somewhat difficult
to wet, such as Galvalume.RTM.. Wetting agents that improve coating
wetting without increasing water sensitivity of the composition and
that are soluble and stable in strong acidic solutions are
preferred. Examples of suitable wetting agents include, but are not
limited to, phosphate esters. Preferred phosphate esters include,
but are not limited to, substituted phosphate esters, and more
preferably substituted carboxylated phosphate esters. A
particularly preferred wetting agent (E) is PHOSPHOTERIC.TM. TC-6.
PHOSPHOTERIC.TM. TC-6 is reported by its supplier, Uniqema of New
Castle, Del., to have an "R" moiety according to chemical formula
(II): 1
[0027] where at least one of R.sup.1 and R.sup.3 is carboxyethyl or
salt thereof and the other is carboxyethyl, salt thereof, or
hydrogen, and R.sup.2 is coconut oil alkyl, in chemical formula
(III): 2
[0028] where u is 1 or 2, y=(4-u), and M is hydrogen or sodium
cation, except that at least one M must be sodium cation.
[0029] When this component (E) is used, independently of their
chemical nature, the total concentration of wetting agent (E)
dissolved in a working-composition according to the invention,
preferably is at least, with increasing preference in the order
given, 0.10, 0.20, 0.25, 0.30, 0.40, 0.50, 0.55, 0.60 or 0.65 g/L
of total composition and independently preferably not more than,
with increasing preference in the order given, 5.0, 4.0, 3.0, 2.5,
2.0, 1.5, 1.0, 0.90, 0.80 or 0.75 g/L.
[0030] Furthermore, when wetting agent (E) is used, independently
of their actual concentrations, the concentrations of wetting agent
(E) and phosphate anions (A) preferably are such that the ratio
between them, in working compositions and concentrated solutions
used to prepare working compositions, is at least, with increasing
preference in the order given, 0.010:1.0, 0.015:1.0, 0.020:1.0 or
0.025:1.0 and independently preferably is not more than, with
increasing preference in the order given, 0.20:1.0, 0.15:1.0,
0.10:1.0, 0.090:1.0, 0.075:1.0, 0.060:1.0, 0.050:1.0, 0.045:1.0,
0.040:1.0 or 0.035:1.0.
[0031] The most preferred components are as follows:
1 Component Trade Name Supplier CAS No. A Phosphoric Acid (75% by
Lidochem, 7664-38-2 weight) Hazlet, NJ B Hexafluorotitanic Acid
(50% GE 17439-11-1 by weight) Honeywell, Morristown, NJ C
TD-1355-DE (about 10% by Henkel weight non-volatiles).sup.1 Corp. D
Ammonium Hydroxide Sigma- 1336-21-6 (29% by weight) Aldrich, St.
Louis, MO E Phosphoteric .TM. TC-6 Uniqema, (35% by weight)
Chicago, IL .sup.1TD-1355-DE is an aqueous solution containing
about 1.2 wt. % hexafluorotitanic acid and about 8.6 wt. % of a
Mannich adduct of polyhydroxystyrene, N-methylglucamine, and
formaldehyde prepared in accordance with U.S. Pat. No.
5,891,952.
[0032] The composition of the present invention can be prepared by
combining the components in any order.
[0033] Some preferred concentrated compositions, in accordance with
the present invention, comprise:
2 Preferred More Preferred Most Preferred Component Wt. % Range Wt.
% Range Wt. % Range A 25-65 35-55 46-47 B 35-75 45-65 53-54
[0034] Other preferred concentrated compositions, in accordance
with the present invention, comprise:
3 Preferred More Preferred Most Preferred Component Wt. % Range Wt.
% Range Wt. % Range A 8.0-65.0 12.5-40.0 15.0-34.0 B 10.0-75.0
10.0-35.0 13.0-30.0 C 0-80.0 5.0-70.0 22-67 D 0-7.5 2.0-5.0 3.5-4.5
E 0-3.5 0.5-2.5 1.0-2.0
[0035] For use as working compositions, the concentrated
composition is typically diluted, with water, to about 2-50 wt. %,
more preferably 3.5-30 wt. %, and most preferably about 5-20 wt.
%.
[0036] Some particularly preferred working compositions, in
accordance with the present invention, comprise:
4 Preferred More Preferred Most Preferred Component Wt. % Range Wt.
% Range Wt. % Range A 1.0-15.0 2.0-10.0 3.0-5.0 B 1.0-20.0 2.0-15.0
3.0-4.0 C 0-40.0 1.0-25.0 2.0-17.5 D 0-2.5 0.1-1.0 0.3-0.5 E 0-1.2
0.01-0.80 0.1-0.6 DI Water 45-98 60-92 72-91
[0037] It should be appreciated that the weight percents in the
three preceding tables are on a wet basis and that the components
referred to in those tables have percent solids similar to the
percent solids of the components listed in the table preceding the
above three tables.
[0038] A process according to the invention in its simplest form
consists of bringing a metal surface to be passivated into physical
contact with a working composition according to the invention as
described above for a period of time, then discontinuing such
contact and drying the surface previously contacted. Suitable metal
surfaces include galvanized and/or aluminized steel, and solid
alloys of aluminum and/or zinc. Physical contact and subsequent
separation can be accomplished by any of the methods well known in
the metal treatment art, such as immersion for a certain time, then
discontinuing immersion and removing adherent liquid by drainage
under the influence of natural gravity or with a squeegee or
similar device; spraying to establish the contact, then
discontinuing the spraying and removing excess liquid as when
contact is by immersion; roll coating of the amount of liquid
followed by drying into place, and the like.
[0039] Preferably the temperature of the working passivating
aqueous liquid composition during a passivation process according
to the invention is at least, with increasing preference in the
order given, 15.degree. C., 20.degree. C., 25.degree. C.,
30.degree. C., 34.degree. C. or 37.degree. C. and independently
preferably, primarily for reasons of economy, is not more than
66.degree. C., 60.degree. C., 55.degree. C., or 50.degree. C. The
quality of the passivation layer formed is not known to be
substantially affected by the temperature during passivating if the
temperature is within any of these preferred limits; the primary
reason for the preference for a minimum temperature during
passivating that is greater than the normal ambient temperature is
that with such a passivating temperature and squeegeeing off of any
adherent liquid promptly after discontinuing contact of the surface
to be passivated with a working passivating aqueous liquid
composition according to the invention, the surface will dry
spontaneously in ambient air within a few seconds to form a
passivated surface according to the invention. This method of
operation is particularly well adapted to most existing coil
processing plants.
[0040] The time during which physical contact is maintained between
the metal surface to be passivated and a working passivating
aqueous liquid composition according to the invention preferably,
for reasons of economy of operation, is as short as possible,
consistent with formation of a passivating layer as effective as
desired. More specifically, the time of contact preferably is not
more than, with increasing preference in the order given, 200, 150,
100, 75, 50, 40, 30, 25, 20, 15, 13, 11, 10, 9.0, 8.0, 7.0, 6.0,
5.0, 4.0, 3.0, 2.0, 1.5, 1.0, 0.5 or 0.1 seconds. Spraying a heated
working passivating aqueous liquid composition onto the surface to
be passivated followed by removing excess liquid with a squeegee
has been found effective in forming a passivated surface according
to this invention within a few seconds at most.
[0041] Normally the surface to be passivated preferably is not
rinsed with water or other diluent between contact with a working
passivating aqueous liquid composition according to the invention
and drying. Drying can be accomplished by simple exposure to
ambient air for a sufficient time, and indeed is preferably
accomplished in this way if the passivated surface has been formed
at a sufficiently high temperature that drying occurs within a few
seconds of separation from contact with the working passivating
aqueous liquid composition according to the invention as described
above. Alternatively, one may hasten the drying by exposure of the
wet surface after passivation to a higher temperature than the
normal ambient temperature, in an oven or by any of the other means
such as infrared radiant heating, microwave drying, and the like
well known per se in the art.
[0042] Preferably, the coating is thick enough that aqueous liquid
composition according to the invention corresponds to at least,
with increasing preference in the order given, 5, 10, 15, 20, 21.5,
30, 38, 43, 50, 60, or 64.6 milligrams per square meter of the
metal surface passivated (hereinafter usually abbreviated as
"mg/m.sup.2"), measured as total weight of the coating, and
independently, preferably is not more than, with increasing
preference in the order given, 600, 575, 540, 450, 300, 200, 172,
150, 129, 115, 100, or 90 mg/m.sup.2 measured as total weight of
the coating. The amount of total coating weight added-on may
conveniently be measured with commercially available instruments,
or by other means known to those skilled in the art.
[0043] Preferably, the coating is thick enough that aqueous liquid
composition according to the invention corresponds to at least,
with increasing preference in the order given, 0.24, 0.5, 1.0, 2.0,
4.0, 6.0, or 8.0 milligrams per square meter of the metal surface
passivated (hereinafter usually abbreviated as "mg/m.sup.2"),
measured as titanium atoms, and independently preferably
corresponds to not more than 133, 125, 100, 75, 50, 40, 24, or 17
mg/m.sup.2 measured as Titanium atoms. The amount of titanium
added-on may conveniently be measured with a commercially available
instrument, a PORTASPEC.TM. Model 2501 X-ray spectrograph from
Cianflone Scientific, or by other means known to those skilled in
the art.
[0044] After forming the initial passivating layer as described
above, it is sometimes preferred to further improve the corrosion
and/or staining resistance of the passivated surface face by
overcoating it with a protective layer containing at least an
organic binder. It is presently contemplated that any of a wide
variety of clear and pigmented paints and like materials, as
generally known per se in the art can be used for this purpose.
Such an overcoating preferably has a thickness after drying that is
at least, with increasing preference in the order given, 0.2, 0.4,
0.6, 0.8, or 1.0 micrometers (hereinafter usually abbreviated as
".mu.m") and independently preferably, primarily for reasons of
economy, is not more than 10, 7, 5, 3, 2.5, 2.0, 1.5, or 1.3 .mu.m.
When the passivated surface is to be used in an application where a
metallic appearance is desired, as in roofing for example, this
relatively thin clear overcoating can serve adequately as the final
coating layer in many instances. For more severe service,
additional thicker coatings of paint and like materials adapted to
a specific purpose as known per se in the art may be applied
directly over this initial thin acrylic overcoating, or directly
over the passivated metal surface itself.
[0045] In certain embodiments, the passivated surface may remain
uncovered, i.e., not painted.
[0046] In certain other embodiments, the passivating coating can
act as a temporary coating. In this embodiment, the passivating
coating is intended to provide temporary corrosion protection for
preventing corrosion and staining during the time period after
galvanizing and prior to final finishing, i.e., during storage and
shipping. The passivating coating could then be removed and the
substrate-coated with a more permanent corrosion resistant coating,
as is known in the art. For instance, the more permanent corrosion
resistant coatings can be provided by a suitable conversion coating
process. Suitable conversion coating composition and processes are
disclosed in U.S. Pat. Nos. 4,961,794; 4,838,957; 5,073,196;
4,149,909; 5,356,490; 5,281,282; and 5,769,967, which are hereby
incorporated by reference. In this embodiment, if the passivating
coating is to be removed, it is presently contemplated that this
can be readily done by exposing the passivating coating to a
suitable alkaline cleaner solution.
[0047] Before passivating according to this invention is to be used
for any metal substrate, the substrate to be passivated may, but is
not necessarily, thoroughly cleaned by any of various methods well
known to those skilled in the art to be suitable for the particular
substrate to be coated.
[0048] Where galvanized metal surfaces are mentioned in connection
with the present invention, they are understood to be material
surfaces of electrolytically galvanized or hot-dip-galvanized or
even alloy-galvanized steel, preferably electrolytically galvanized
or hot-dip-galvanized steel strip. By steel is meant unalloyed to
low-alloyed steel of the type used, for example, in the form of
sheets for automotive bodywork. The use of galvanized steel,
particularly electrolytically galvanized steel in strip form, has
grown considerably in significance in recent years. The expression
"galvanized steel" in the context of the present invention is
understood to encompass electrolytically galvanized steel and also
hot-dip-galvanized steel and also applies generally to
alloy-galvanized steel, zinc/nickel alloys, zinc/iron alloys
(Galvanealed) an zinc/aluminum alloys (GALFAN.RTM., from Eastern
Alloys, Inc., of Maybrook, N.Y., GALVALUME.TM., from BIEC
International, Inc. of Vancouver, Wash.) playing a particularly
crucial role as zinc alloys.
[0049] The practice of this invention may be further appreciated by
consideration of the following, non-limiting examples, and the
benefits of the invention may be appreciated by the examples set
forth below.
EXAMPLES
Example 1
[0050] Working compositions 1 and 2 were prepared as set forth
below in Table 1.
5TABLE 1 Passivate Compositions Composition 1 Composition 2 (pH
.about.1.7) (pH .about.1.7) Ingredient wt. (g) wt. (g) DI Water
92.5 77.5 75% H.sub.3PO.sub.4 3.5 4.0 50% H.sub.2TiF.sub.6 4.0 3.5
TD-1355-DE -- 15.0 (10% solids)
[0051] Test panels of HDG (hot dipped galvanized) steel and
Galvalume.RTM. steel were prepared in the following manner.
[0052] The HDG steel panels were cleaned with a 3 wt. % solution of
Parco.RTM. Cleaner 1200, available from Henkel Corporation, at a
temperature of about 140.degree. F. for about 20 seconds. The
panels were then hot water rinsed at a temperature of about
120.degree. F. for about 10 seconds. The panels were then squeegeed
dry. Compositions 1 and 2 were then diluted to about 66 wt. % and
were then applied to the panels using a No. 3 draw bar. The panels
were then dried in an IR oven. The total coating weight on the
panels were about 4-8 mg/ft.sup.2.
[0053] Galvalume.RTM. steel panels were cleaned and treated in the
same manner except they were only cleaned for about 7 seconds.
[0054] The panels, along with bare test panels, were submitted for
168 hours of NSS (Neutral Salt Spray) testing in accordance with
ASTM B117-90 and 240 hours of Cleveland Condensing Humidity testing
in accordance with ASTM D4585-87. The results are shown below in
Tables 2 and 3.
6TABLE 2 168-Hour Neutral Salt Spray Test Results. Compositions 1
and 2 vs. bare samples 168 Hrs of Neutral Salt Spray Composition
Substrate % White Rust 1 Galvalume .RTM. 50% 1 HDG 100% after 48
hrs 2 Galvalume .RTM. 33% 2 HDG 33% after 48 hrs Bare Galvalume
.RTM. 100%* after 24 hrs Bare HDG 100% after 5 hrs *Represents
Black Rust
[0055]
7TABLE 3 240-Hour Cleveland Condensing Humidity Test Results
Compositions 1 and 2 vs. bare samples 240 Hrs of Cleveland
Condensing Composition Substrate % White Rust 1 Galvalume .RTM.
<1% 1 HDG 50% after 72 hrs 2 Galvalume .RTM. 3% 2 HDG 13% Bare
Galvalume .RTM. 100%* after 48 hrs Bare HDG 100% after 5 hrs
*Represents Black Rust
Example 2
[0056] Working compositions 3 and 4 were prepared as set forth
below in Table 4.
8TABLE 4 Passivate Compositions Composition 3 Composition 4 (pH
.about.1.7) (pH .about.1.7) Ingredient wt. (g) wt. (g) DI Water
945.0 90.5 75% H.sub.3PO.sub.4 25.0 4.0 50% H.sub.2TiF.sub.6 30.0
3.5 TD-1355-DE -- 2.0 (10% solids)
[0057] HDG and Galvalume.RTM. steel test panels were prepared and
subjected to NSS testing for 336 hours in the manner set forth
above in Example 1. The results are shown below in Table 5.
9TABLE 5 NEUTRAL SALT SPRAY TESTING RESULTS ON GALVALUME AND HDG: %
WHITE RUST Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 14 Panel#
Composition Substrate Application Appearance 24 48 72 96 120 144
168 336 13 3 Galvalume .RTM. #3 db Splotchy 1 1 3 3 10 33 33 100 14
4-6 mg/ft.sup.2 1 1 3 10 33 33 33 100 15 Coating wt. 0 0 1 3 10 33
33 50 16 3 Galvalume .RTM. coater Perfect 3 100 100 100 100 100 100
100 17 2-4 mg/ft.sup.2 3 100 100 100 100 100 100 100 18 Coating wt.
3 100 100 100 100 100 100 100 28 4 Galvalume .RTM. #3 db Perfect 0
0 0 0 0 0 0.1 1 29 4-8 mg/ft.sup.2 0 0 0 0 0.1 0.1 0.1 1 30 Coating
wt. 0 0 0 0 0 0 0.1 3 110 1 Galvalume .RTM. #3 db Perfect 0 0 0 1 3
5 10 100 111 4-8 mg/ft.sup.2 0 0 1 1 5 5 10 100 112 Coating wt.
Dark 0 1 1 5 5 5 3 100 113 2 Galvalume .RTM. #3 db Splotchy 1 1 1 1
1 1 1 100 114 4-8 mg/ft.sup.2 1 1 1 1 1 1 1 50 115 Coating wt. 1 1
1 1 3 3 3 100 40 1 HDG #3 db Uneven 16 100 100 100 100 100 100 100
41 66% sol. 2-4 mg/ft.sup.2 edges 16 100 100 100 100 100 100 100 42
Coating wt. 10 33 33 100 100 100 100 100 43 1 HDG #3 db Perfect 1
16 50 100 100 100 100 100 44 66% sol. 2-4 mg/ft.sup.2 1 33 50 100
100 100 100 100 45 Coating wt. 1 10 33 100 100 100 100 100 67 3 HDG
coater Splotchy 16 100 100 100 100 100 100 68 2-4 mg/ft.sup.2 33
100 100 100 100 100 100 69 Coating wt. 33 100 100 100 100 100 100
82 4 HDG #3 db Near 3 16 50 50 50 100 100 83 4-8 mg/ft.sup.2
Perfect 1 50 100 100 100 100 100 84 Coating wt. 3 50 100 100 100
100 100
Example 3
[0058] HDG and Galvalume.RTM. steel test panels were cleaned with a
4 wt. % solution of Ridoline.RTM. 321 at a temperature of about
140.degree. F. for about 30 seconds. The panels were then hot water
rinsed at a temperature of about 120.degree. F. for about 10
seconds. The panels were then squeegeed dry. Composition 1 was
applied to the panels using various drawbars. The test panels were
then subjected to (i) Stack testing, (ii) Butler Water Immersion
testing, and (iii) NSS testing for 72 hours in the manner set forth
above in Example 1. The results are shown below in Tables 6, 7, and
8.
10TABLE 6 Stack Test Results (% Black Rust (BR) White Rust (WR))
Substrate/ Total Coat. Coating Wt. 168 Hrs 336 Hrs 672 Hrs method
(mg/ft.sup.2) BR WR BR WR BR WR HDG 8-12 0 0 1 10 3 33 (#9 drawbar)
Galvalume 4-8 0 0 1 1 3 1 (#3 drawbar)
[0059]
11TABLE 7 Butler Water Immersion Test Results (% Black Rust (BR)
White Rust (WR)) Substrate/ Total Coat. Coating Wt. 168 Hrs 336 Hrs
672 Hrs method (mg/ft.sup.2) BR WR BR WR BR WR HDG 8-12 1 1 10 3 33
33 (#9 drawbar) Galvalume 4-8 1 1 3 3 33 3 (#3 drawbar)
[0060]
12TABLE 8 Neutral Salt Spray Test Results (% Black Rust (BR) White
Rust (WR)) Substrate/ Total Coat. Coating Wt. 168 Hrs 336 Hrs 672
Hrs method (mg/ft.sup.2) BR WR BR WR BR WR HDG 8-12 0 0 1 10 3 33
(#9 drawbar) Galvalume 4-8 0 0 1 1 3 1 (#3 drawbar) Note: BR, WR
and RR corresponds to black rust, white rust and red rust.
[0061] The Stack testing, (ii) Butler Water Immersion testing were
carried out as follows:
[0062] StackTest:
[0063] The panels were cut to 4".times.4" size.
[0064] Any duplicate test panels were stacked face-to-face with an
amount of deionized water (as indicated in drops or as a spray)
being applied between the two test panels to wet the surfaces.
[0065] The stack of test panels were clamped together in a test jig
and tightened to about 50 in..multidot.lb. torque.
[0066] The stack of panels were placed in a humidity test cabinet
at 100.degree. F. and 100% humidity.
[0067] The test panels were evaluated at the time intervals shown
in table 6 for black rust (BR) and white rust (WR).
[0068] Butler Water Immersion Test:
[0069] Samples were cut into 3-1/2".times.7-1/2" panels such that
the samples support themselves on the sides of the glass tray
approximately 1/2" from the bottom of the tray.
[0070] Metal surfaces that had been oiled were rinsed on both sides
of the sample with naphtha and allowed to dry.
[0071] The samples were placed in the glass tray.
[0072] Enough distilled water was added to the tray to cover the
sample with 3/4" of water.
[0073] The uncovered trays were placed in a humidity cabinet at
100% humidity and 100.degree. F.
[0074] The top surfaces of the test panels were evaluated at the
time intervals shown in table 7 for black rust and white rust.
Example 4
[0075] HDG steel test panels were cleaned with a 4 wt. % solution
of Ridoline.RTM. 321 at a temperature of about 140.degree. F. for
about 30 seconds. The panels were then hot water rinsed at a
temperature of about 120.degree. F. for about 10 seconds. The
panels were then squeegeed dry. Compositions 1 and 4 were applied
to the panels using various drawbars. The panels were then cleaned
with a 4.5 wt. % solution of Parco.RTM. cleaner 1200 for about 30
seconds at about 150.degree. F. The test panels were observed to be
fully cleaned in accordance with the following procedure.
[0076] The cleaned test panels were rinsed with D.I. water and
dried. A drop of about a 3 wt. % copper sulfate pentahydrate
solution was dropped on the panels. A 100% reaction, evidenced by
the area of the panel that contacts the drop turning black, within
a second of contact, was observed on all the panels, indicating
that the panels were fully cleaned.
Example 5
[0077] HDG steel test panels prepared in the same manner as set
forth in Example 4 were then subjected to the following procedure
and subjected to T-bend testing. The results are shown below in
Table 9.
[0078] The procedure that was followed was:
[0079] A=pretreat 3 panels with Bonderite.RTM. 1402W, prime coat
with UY9R 24235, and top coat with CLS 9872 from Akzo.
[0080] B=pretreat 3 panels with Bonderite.RTM. 1303 and
Parcolene.RTM. 62, prime coat with UY9R 24235, and top coat with CL
9872 from Akzo.
[0081] C=treat 3 panels with Parcolene.RTM. AT, Bonderite.RTM.
1421, and Parcolene.RTM. 62, prime coat with UY9R 24235, and top
coat with CLS 9872.
[0082] The T-bend test was carried out in accordance with ASTM
D4145.
13TABLE 9 T-bend results Panels Treated With Panels Treated With
Panels Treated With Bonderite .RTM. 1402W Bonderite .RTM. 1303
Bonderite .RTM. 1421 Composition/ T- Composition/ T- Composition/
T- Panel ID Bend Panel ID Bend Panel ID Bend Bare/A1 1T Bare/B1 0T
Bare/C1 1T Bare/A2 1T Bare/B2 0T Bare/C2 1T Bare/A3 1T Bare/B3 0T
Bare/C3 1T 1/A1 2T 1/B1 0T 1/C1 1T 1/A2 2T 1/B2 0T 1/C2 1T 1/A3 2T
1/B3 0T 1/C3 1T 3/A1 2T 3/B1 0T 3/C1 1T 3/A2 3T 3/B2 0T 3/C2 1T
3/A3 2T 3/B3 0T 3/C3 1T 0T is the best, 0T-2T are acceptable.
[0083] From the above results, it confirms that panels treated with
the chrome free passivate of the present invetnion are treatable
and paintable.
Example 6
[0084] HDG steel test panels were coated with composition 1.
Samples C and D were cleaned with a 4.5 wt. % solution of
Parco.RTM. cleaner 1200 for about 25 seconds at about 160.degree.
F. Samples C and D were subjected to the same test as set forth in
Example 4 and were observed to be fully cleaned. The sample
designations are shown below.
[0085] A: Composition 1 treatment on HDG at high coating weights
(8-16 mg/ft.sup.2).
[0086] B: Composition 1 treatment on HDG at low coating weights
(4-8 mg/ft.sup.2).
[0087] C: Sample A cleaned with Parco.RTM. Cleaner 1200.
[0088] D: Sample B cleaned with Parco.RTM. Cleaner 1200.
[0089] The test panels were submitted to Evans Analytical Group.TM.
for surface analysis using X-Ray Photoelectron Spectroscopy. The
surfaces were analyzed as three depths--(i) as received, (ii) about
75 .ANG. (angstroms) below the as received surface, and (iii) about
150 .ANG. (angstroms) below the as received surface. Notably, the
spectroscopy analysis confirmed that samples C and D were fully
cleaned.
[0090] The results are shown below in Table 10.
14TABLE 10 Atomic concentrations of elements expressed in atomic
percents C N O F Na Mg Al Si P Cl Ca Ti Zn Sample A as-rec'd 31.6
0.9 42.6 4.9 -- 0.2 0.3 -- 7.4 -- -- 3.1 9.0 Sample A .about.75
.ANG. 1.9 -- 52.3 8.2 -- 0.2 1.0 -- 10.0 -- -- 8.5 17.9 Sample A
.about.150 .ANG. 0.9 -- 51.8 9.3 -- 0.3 0.9 -- 9.6 -- -- 9.4 17.9
Sample B as-rec'd 25.9 tr 37.7 13.9 1.1 0.5 1.8 -- 5.4 -- 0.2 3.7
10.0 Sample B .about.75 .ANG. 1.4 -- 52.9 8.3 -- 0.2 1.9 -- 7.8 --
-- 11.0 16.6 Sample B .about.150 .ANG. 1.1 -- 53.6 7.7 -- 0.3 2.1
-- 8.0 -- -- 11.3 16.0 Sample C as-rec'd 20.4 tr 52.7 -- -- 0.5 --
0.5 0.4 0.3 0.4 -- 24.8 Sample C .about.75 .ANG. 2.5 -- 39.6 -- --
-- 0.6 -- -- -- 0.2 -- 57.1 Sample C .about.150 .ANG. 1.7 -- 22.3
-- -- -- 0.1 -- -- -- -- -- 75.9 Sample D as-rec'd 29.7 tr 49.4 --
-- 0.6 -- -- -- -- 0.3 -- 20.1 Sample D .about.75 .ANG. 2.6 -- 40.3
-- -- 0.7 1.0 -- -- -- 0.6 -- 54.8 Sample D .about.150 .ANG. 3.7 --
23.2 -- -- -- 0.7 -- -- -- 0.2 -- 72.3 "--" = not detected "tr" =
trace amount detected
[0091] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *