Note: Descriptions are shown in the official language in which they were submitted.
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R-869
METALWORKING EMULSION CLEANER
FIELD OF THE INVENTION
The present invention relates to metal working emulsion
cleaners which comprise oil-in-water emulsions used to clean
machined metal parts and leave a thin oil film to provide
corrosion protection. More particularly, the present invention
relates to an emulsion cleaner which is stable as a concentrate,
resistant to foaming during use and is free of toxic or hazardous
materials.
BACKGROUND OF THE INVENTION
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Emulsion cleaners are employed in the metal treatment
- industry to clean and passivate a metal surface. These type of -~
cleaners are typically oil based and form a macroemulsion when
mixed with water. This type of cleaner is typically used to
remove gross soil contaminants, fines, and cooling lubricants
from machined metal surfaces. The cleaned metal surfaces do not
become "water break-free" clean in the traditional sense. -~
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This type of "cleaner" leaves an oily film on the surface that
provides rust protection.
Emulsion cleaners and clean and passivate treatments some-
times can be interchangeable. Emulsion cleaners usually provide
longer term passivation and may be followed by a subsequent step of
an oil preservative spray where long times in storage are
anticipated. Treated parts may need to remain rust free, while
exposed in the manufacturing plant, for from several hours up to
thirty days. In order to maintain the rust prevention abilities,
these type of cleaners are not rinsed. Commercial emulsion
cleaners typically comprising a mixture of oil and emulsifiers
which are mixed with water to form an oil-in-water emulsion. In a
typical commercial emulsion cleaner, a coupling agent or variety of
coupling agents are used to produce a stable concentrate.
Conventional coupling agents include butyl cellosolve, butyl
carbitol or some similar glycol ether to produce a stable
concentrate. Currently, glycol ethers are listed as toxic or
hazardous under SARA 313 which makes their use in a commercial
setting undesirable.
Typical commercial emulsion cleaners employ oil soluble
rust inhibitors which are compatible with the oil phase. Such oil
soluble rust inhibitors are relatively easy to incorporate into a
stable concentrate. In practice, the emulsion baths tend to be
metastable and separate to some extent into an oil rich layer and
an aqueous layer. Concentration gradients occur with the oil layer
being rich in the oil soluble rust inhibitor and the aqueous phase
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being depleted in rust inhibiting components. When such separa-
tion occurs, the metal surfaces being treated are not adequately
protected from rusting.
SUMMARY OF THE INVENTION
It was discovered that an emulsion cleaner which is
resistant to foam formation during use, stable as a concentrate,
and free of toxic or hazardous materials could be formulated. The
emulsion cleaner of the present invention avoids the use of conven-
tional stabilizing coupling agents. The emulsion cleaner of the
present invention employs a blend of triethanolamine soap of tall
oil fatty acid, polyethylene glycol (400) dioleate and polyethy-
lene glycol (400) monooleate to stabilize a concentrated emulsion
cleaner. This blend also facilitates the formation of oil-in-
water emulsions when the concentrate is mixed with water prior to
use. This formulation avoids the SARA 313 listed glycol ethers
that have been commonly used as coupling agents. The formulation
of the present invention may also include a nonionic surfactant
which enhances the stability of the oil-in-water emulsion bath.
In the formulation of the present invention, in addition
to the conventional addition of an oil soluble corrosion inhibitor
to the oil phase, a water soluble corrosion inhibitor is added to
the concentrate. Thus, upon addition of the concentrate to water,
prior to use, both phases of the resulting oil-in-water emulsion
will include a corrosion inhibitor.
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Thus, the present invention is directed to a combination
of a triethanolamine soap of tall oil fatty acid, polyethylene
glycol (400) dioleate and polyethylene glycol (400) monooleate as
a solubilizing agent in an emulsion cleaner. The formulation of
the present invention is an efficacious replacement for conven-
tional glycol ether based coupling agents. The formulation of the
present invention may also include a nonionic surfactant which
enhances the stability of the working, oil-in-water emulsion bath.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present inventor discovered an emulsion cleaner formu-
lation which is stable both as a concentrate and as a working so-
lution. The formulation of the present invention is also resis-
tant to foam formation during use and is free of toxic or hazar-
dous materials. The formulation of the present invention employs
a unique combination of a triethanolamine soap of tall oil fatty
acid, polyethylene glycol (400) dioleate, and polyethylene glycol
(400) monooleate as a substitute for a glycol ether coupling
agent. This combination provides an enhanced stabilizing effect
in both a concentrate and working solution. The combination is
free of toxic or hazardous materials listed under SARA 313.
Because of increasingly onerous regulations regarding
the use of materials.listed as hazardous or toxic under SARA 313,
there is a demand for efficacious replacements for SARA 313 listed
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chemicals in commercial operations. In addition, the optional
inclusion of a nonionic surfactant in the formulation of the
present invention enhances the stability of the oil-in-water
working emulsion cleaner bath.
The emulsion cleaner formulation of the present invention
is typically supplied as a concentrate which is diluted with water
prior to use. Upon dilution a working solution comprising a milky
oil-in-water emulsion forms. The formulation of the present inven-
tion provides for stability in both the concentrate and dilute or
working solution. By stable, it is meant that the formulation is
resistant to separation into an oil layer and a water layer. The
formulation of the present invention has also been found to be
resistant to the formation of foam in the working bath. During
use, the formulation of the present invention is applied to metal
surfaces by spraying, immersion or flow coating. The formation of
foam in the working bath can have detrimental effects on bath
stability, efficiency of film formation, corrosion protection, and
operation of the application equipment.
The formulation of the present invention employs the com-
bination of triethanolamine soap of tall oil fatty acid, poly-
ethylene glycol (400) dioleate and polyethylene glycol 400 mono-
oleate, preferably along with an anionic surfactant, to replace a
glycol ether coupling agent in an emulsion cleaner. The conven-
tional materials present in an emulsion cleaner concentrate
include oil such as napthenic industrial process oil, sodium -
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petroleum sulfonate, an oil soluble rust inhibitor, and monoethan-
olamine. The formulation of the present invention also includes a
water soluble rust inhibitor.
In the preferred formulation of the present invention, the
triethanolamine soap of tall oil fatty acid comprises from about
0.5 to 10% preferably 2.0% of the concentrate. The polyethylene
glycol 400 dioleate and polyethylene glycol (400) monooleate are
preferably present in a ratio of 1 to 5 and comprise from about 1
to 4% and preferably 2.4% of the concentrate. The nonionic sur-
factant is preferably an alkoxylated fatty alcohol such as polyoxy-
ethylene polyoxypropylene ether of an alcohol such as Plurafac
RA20 available from BASF. The concentrate of the present invention
is typically diluted by adding 1 to 5 parts concentrate to 100
parts water to form the working bath.
In the preferred embodiment, the triethanolamine soap of a
tall oil fatty acid is preferably provided by a mixture of tall
oil fatty acid such as Westvaco L5 available from Westvaco Corpo-
ration, and triethanolamine. The oil phase of thë emulsion
cleaner can comprise a naphthenic process oil such as Telura 323
available from Witco Chemical Corporation. The preferred emulsion
cleaner also includes sodium petroleum sulfonate such as Petrosol
M50 available from Penreco. The preferred oil soluble rust
inhibitor of the present invention is a mixture of a proprietary
barium soap, proprietary high molecular weight organic acids,
sodium petroleum sulfonate and a severely hydrotreated heavy
napthenic distillate available as Alox 575 from Alox Corporation.
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The preferred water soluble rust inhibitor of the present inven-
tion is isononanoic acid, a 3,5,5, trimethylhexanoio acid avail-
able from American Hoeschst Corporation.
The invention is further illustrated by the following
specific examples and tables which should not be construed as
limiting the invention defined in the claims.
Examples
Testing was conducted with two commercially available ; -~
emulsion cleaners and an emulsion cleaner in accordance with the
present invention. The testing included corrosion inhibition and
stability of the concentrate. The commercial emulsion cleaners
tested were Chrysan 418 available from Chrysan Industries and ~;
Betz DH-1767 available from Betz Laboratories of Trevose, PA.
The corrosion inhibition testing comprised wetting cast
iron chips resting on filter paper with the emulsion cleaner to be
tested, pouring off the cleaner after 30 minutes and exposing the
wet chips to the atmosphere for 24 hours. The rating is based on
- the number of rust spots on the filter paper after removing the
chips and on the degree of rust protection based on observation of
the chips themselves. Stability was tested by preparing a working
concentration of the emulsion cleaner, shaking to mix thoroughly,
pouring into a volumetric flask with a neck indexed from 1-10
milliliters, allowing to sit overnight, and recording the
milliliters of oil which separated out of the emulsion.
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Table 1 summarizes the makeup of two formulations tested
alongside the commercial emulsion cleaners. Formulation 1 does
not include the combination of polyethylene glycol (400) dioleate, .
polyethylene glycol (400) monooleate and triethanolamine soap of
tall oil fatty acid while formulation 2 is in accordance with the
present invention. -~:~
TABLE 1
Formulation
I 2
naphthenic process oil 78 81.3
tall oil fatty acid 4 2
45% KOH 2
Triethanolamine 99% 2 2
Alox 575 3 4
Alox 165 3
Isononanoic Acid 2 2.2
sodium petroleum sulfonate 5 7.0
polyethylene glycol (400) dioleate -- 0.2
polyethylene glycol (400) monooleate - -- 1.0
Plurafac RA20 1 0.1
monoethanolamine 39% -- 0.2
Table 2 summarizes the results of the stability testing and ~
corrosion inhibition testing. ~;.
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TABLE 2
Chrysan Betz
418 DH-1767 (1l (2)
chip test (paper) 30S NRS GR NRS
chip test (chips) MR NR 30S+ NR
layering (mls) 1.5 1.3 0.2 0.4
NR = no chip rusting
MR = mild chip rusting
GR = general chip rusting
NRS = no rust spots on filter paper
6S = 6 rust spots on filter paper
Table 2 shows that formulation 2, in accordance with the present
invention provides, an emulsion cleaner which is more effective
and more stable than current commercial emulsion cleaners.
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While the present invention has been described with
respect to particular embodiments thereof, it is apparent that
numerous other forms and modifications of this invention will be
obvious to those skilled in the art. The appended claims and this
invention generally should be construed to cover all such obvious
forms and modifications which are within the true spirit and scope
of the present invention.
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