Note: Descriptions are shown in the official language in which they were submitted.
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R-914
CLEANING AND PASSIVATING
TREATMENT FOR METALS
FIELD OF THE INVENTION
The present invention relates to cleaning and passivating treat-
ments for metals. More particularly, the present invention relates to
10 cleaning and passivating treal",e,)ts for metals which are essentially free
of amines, alkanolamines, and phosphates. The aqueous Iredl")er,ls of
the present invention co,nprise ar"pl)oteric surfactants which were found
to provide an excellent passivating film on ferrous surfaces. The ampho-
teric su, raclants of the present invention are caprylic acid derivatives of
15 imidazoline compounds.
BACKGROUND OF THE INVENTION
"In process" cleaners are employed in the metal treatment industry
20 to clean and passivate a metal surface. These types of aqueous clean-
ers are typically based on organic rust-proofing or passivating agents
such as combinations of alkanolamines and fatty acids, surfactants, anti-
foam agents and/or phosphonates and possibly biocides and builders.
~- 21~3471
In order to passivate a metal surface to prevent rusting during process
breaks and slorage, approp, iate additives are used. Cleaning and
passivating agents which inhibit the corrosion of ferrous metal surfaces
contain for example alkali nitrites, alkanolamines, soaps and ber,,oates.
Clean and passivate treatments are typically employed in applica-
tions which require good cleaning and temporary metal passivation.
Treated parts may need to remain rust-free, while exposed in the manu-
facturing plant for from several hours up to 30 days. In order to maintain
10 their rust prevention ability, these cleaners are not rinsed. Current com-
mercial cleaners typically employ alkanolamines such as monoethanol-
amine, diethanolamine or triethanolamine as a passivating agent for fer-
rous surfaces. The alkanolamine co",pol-ent inhibits flash rusting of
ferrous iron parts during line stops or storage. Typical cleaners also will
15 include surfactants such as glycol ether compounds and phosphonate
compounds which aid in cleaning of the parts. For example, U.S. Patent
No. 4,578,208 which issued to Geke et al. discloses a cleaning and/or
passivating composition and process which employs a phosphoric acid
ester, an alkanolamine and a surfactant and optionally builders, non-
20 ferrous metal inhibitors and biocides.
Currently, environmental objections are being raised concerningthe use of alkanolamines, phosphates and glycol ethers as raw materials
for industrial processes.
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SUMMARY OF THE INVENTION
The present inventors discovered that a specific class of ampho-
teric su, ra~;tanls provides excellent passivation of ferrous metals when
5 substituted for alkanolamines. The use of amphoteric surfactants in
accordar,ce with the present invention obviates the need for amines
alkanolamines phosphates and other currently environmentally undesir-
able materials in clean and passivate formulations. The inventors found
that caprylic acid derivatives of imidazoline compounds provide effica-
10 cious passivation of ferrous metal surfaces. The treatment solution of thepresent invention is subslantially free of amines alkanolamines and
,c I ,osphales. By substantially free it is meant that these materials are not
intentionally added as active cor"ponents of the treatment solution. The
prefer,ed treatment solution also includes small quantities of a borate ion
15 and sodium molybdate. These co",pounds were found to allow reduc-
tions in the concer,t,ation of the amphoteric surfactant component without
adversely drrecting efficacy. In addition a defoamer such as a nonionic
surfactant may be desirable in spray applications.
20 DESCRIPTION OF THE PREFERRED EMBODIMENT
The present inventors discovered a clean and passivate treatment
formulation for use in treating ferrous metal surfaces which is substan-
tially free of amines alkanolamines and phosphates. The clean and
25 passivate formulation of the presenl invention is an aqueous solution of
a caprylic acid derivative of an imidazoline. The formulation preferably
also includes a borate ion sodium molybdate and a nonionic surfactant
defoamer. The inventors found that aqueous solutions of caprylic acid
derivatives of an imidazoline provide effective rust protection. It was
30 further discovered that when such a~ JI ,oteric su, racta, ItS were used in
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combination with a borate ion and sodium molybdate significantly lower
concenlrations of the amphoteric surfactant could be employed with good
rust inhibition results. The borate ion may be provided by a borate salt or
by boric acid.
The formulation of the present invention includes amphoteric
su, racta,1ls which are caprylic acid derivatives of an imidazoline com-
pound. The surfactants are present in the treatment solution at concen-
trations of from about 0.05% up to about 5% by weight. Examples of
10 commercially available amphoteric surfactants include Monateric Cy-Na
50% a sodium salt of 2-caprylic-1 (ethyl beta oxypropanoic acid) imida-
zoline; I\lonaleric LF-100 a C5 9 methyl alkyl imidazoline; Monateric LF-
Na 50 a sodium salt of LF-100 but 50% active; Monateric CYA-50 a
capryl ampho-propionate; Monateric 1000 a capryl amphopropionate;
15 and Miranol JAS concentrate which is a carboxylate derivative of capryl
imidazoline. Miranol is a t,ade",ark of Rhone-Poulenc and Monateric is
a tradei"ark of Mona Industries. Amphopropionate is another name for
imidazoline.
When a caprylic acid derivative of an imidazoline is used alone
the preferred treatment conce"l(alion is about 5% by weight. When a
caprylic acid derivative of an imidazoline is employed in the prefer,ed
combination which includes a borate ion (such as sodium ",etaborale
octahydrate) and a molybdate ion (such as sodium molybdate) the con-
ce"l,dlion of the surfactant can be decreased to about 0.1 to 0.3% by
weight. The prefer,ed concerll,dlion of sodium molybdate is from about
0.1 to 0.5% by weight. The prefer,ed concen~,dlion of sodium meta-
borate octahydrate is from about 0.1 to 0.5% by weight. The ratio of
imidazoline to borate ion is from about 1:0.4 to 1.5 and the ratio of
molybdate ion to imidazoline and borate ion is more than about 1:4
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The clean and passivate formulation of the present invention is
typically supplied in two conce"l,ale packages which are diluted and
mixed prior to application. The first comprises the caprylic derivative of
imidazoline co",pound; sodium molybdate and sodium ",etaborale octa-
5 hydrate in deionized water. The second package comprises a nonionicsu, ractant defoaming agent.
Efficacy of the treatment solution of the present invention was
evaluated in a chip test evaluation. The test involved placing 4 9 of cast
10 iron chips on a filter paper in a plastic weighing dish adding 50 ml of the
test solution allowing the solution to stand for 24 hours. The filter paper
is rinsed with tap water and examined for rust spots. Refer to ASTM
D4627-92.
The effectiveness of the composition and method of the present
invention is cle",onslrated by the following examples which are provided
as illustrative and are not intended to limit the scope of the invention as
set forth in the claims.
20 Example 1
A variety of a",photeric su,ractanls which are imidazoline com-
pounds were tested in the above manner. Table I su"""a, i~es the
results.
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TABLE I
Bath ComPosition ChiP Test
99% water 20+ rust spots
1% Monateric 1000
95% water 0 rust spots
5% 1\101 Idl~riC 1 000
99% water 2 rust spots
1% Monateric CY Na-50
95% water 0 rust spots
5% Monaleric CY NA-50
99% water 5 rust spots
1% Monateric LF Na-50
95% water 0 rust spots
5% Monateric LF Na-50
95% water 20+ rust spots
5% Monateric CEM-38
~h1Onateric CEM-38 is a sodium salt of a coconut fatty acid derivative of
an imidazoline co""~ound available from Mona Industries.
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The data in Table I shows that a",pl)oteric su,ractanls which are
caprylic acid derivatives of an i",id~oline will provide chip protection
while a C12-C14 fatty acid derivative of an imidazoline (Monateric CEM-
38) does not provide such protection.
Example 2
The above clesc, ibed chip test was employed to evaluate various
treatment concen~, alions of the SUI ractanl the borate and the molybdate.
10 Table ll summarizes the results.
TABLE ll
Clean/Passivate Bath comPosition (weiqht %) ChiP Evaluation
Mlo"aleric Sodium
CY Na-50NaBO2.8H20Molybdate Water
-- -- 99.02 rust spots
1 0.2 ---- 98.83 rust spots
0.4 - 98.6no rust spots
0.8 0.5 ---- 98.7no rust spots
0.5 0.5 -- 99.08 rust spots
0.3 0.5 --- 99.218 rust spots
0.3 0.5 0.1 99.1no rust spots
0.3 0.5 0.2 99.0no rust spots
0.3 -- 0.2 99.520+ rust spots
0.2 0.5 0.1 99.2no rust spots
0.1 0.5 0.1 99.3no rust spots
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TABLE ll (cont'd)
Clean/Passivate Bath ComPosilion (weiaht %)ChiP Evaluation
5Monateric Sodium
CY Na-50 NaBO2.8H20 MolybdateWater
0.1 0.4 0.1 99.4no rust spots
0.1 0.3 0.1 99.5no rust spots
-- 0.5 0.1 99.46 rust spots
- 0.5 99.520+ rust spots
-- -- 0.1 99.920+ rust spots
The data in Table ll shows that efficacious results are obtained at a
15 relatively low treatment concenlralion with the prererred combination of
the present invention.
Example 3
hlondleric LF-Na 50 was tested in a treatment solution including
sodium metaborate octahydrate, sodium molybdate and Macol LF 110 (a
nonionic polyoxyalkylated aliphatic ether available from PPG Industries,
Inc. which was added as a defoamer). The addition of the borate and
molybdate was found to allow excellent passivation, i.e., no chip rusting,
in the above described chip test with a relatively low concentration of
amphoteric surfactant. The treatment solution tested is set out in Table
lll in weight percent.
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TABLE lll
Sodium meta borate octahydrate 0.5%
Sodium molybdate 0.1%
MGnaleric LF-Na-50 0.1 % as 100% actives
Macol LF 110 0.04%
Example 4
The presence of Macol LF 110 in the coi"position of Example 3 is
included to inhibit foaming tendencies of the imidazoline su, radant. The
presence of the deroa",er does not effect the passivating activity of the
imidazoline surfactant. Table IV su""nari,es chip testing as described
above of a treatment in accordance with the present invention with and
15 without a nonionic polyoxyalkylated aliphatic ether defoamer (Macol LF
110 available from PPG Industries Inc.).
TABLE IV
ComPosition (~rams/100 qrams) ChiP Test
Monaleric Sodium Macol
LF Na-50 NaBO2.8H20 Molvbdate Water LF 110
1. 0.075 0.37 0.075 99.48 no rustspots
2. 0.075 0.37 0.075 99.44 0.04 no rust spots
3. 0.10 0.50 0.10 99.30 -- no rust spots
4. 0.10 0.50 0.10 99.26 0.04 no rust spots
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For ecGnoi"ies of shipping and handling the treatment solution of
the present invention is preferably supplied as a cor,cenl,ate which is
diluted with deionized water to form a working bath. A prefer,~d co"cen-
trate co",,l~rises 12.5% sodium ",e~aborate octahydrate 2.5% sodium
5 molybdate 5.0% Monateric LF-Na 50 and 80% deionized water. The
Macol LF 110 defoamer is supplied separately. A 4% v/v dilution of the
prefer,ed concentrate with 0.04% v/v of Macol LF 110 results in the
l,eal",enl solution described in Example 3. This prerer,ed treatment
solution has been found to be effective when diluted with Dl soft or hard
1 0 water.
While the present invention has been described with respect to
particular embodi",ents thereof it is apparenl that numerous other forms
and modificalions of this invention will be obvious to those skilled in the
15 art. The appended claims and this invention generally should be con-
strued to cover all such obvious forms and modifications which are within
the true spirit and scope of the present invention.
