Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02288130 2005-05-20
Water-in-oil microemulsions and their preparation
This invention relates to clear homogenous water-in-oil microemulsions
suitable for
use as industrial lubricants e.g. hydraulic or machine tool cutting oils.
The use of cutting oil and macroemulsions of these oils in metalworking is
well
known. Neat oils are used when a good surface finish is required on the metal
being
worked. However, due to the poor coolant properties of the oils used rapid
degeneration of the machine tool (which can reach temperatures in excess of
200°C.)
takes place.
To improve the life of the machine tool macroemulsions of the oil are made
with
water. The excellent coolant properties of the water does indeed improve the
life of
the tool. However, the incorporation of water coupled with the instability of
macroemulsions gives rise to several other problems. These are that the
lubricity of
the oil is decreased with addition of water thereby affecting the surface
finish of the
metal. Also, as water is present the likelihood of corrosion becomes apparent.
Consequently, the macroemulsion requires further addition of specialist
additives to
overcome the occurrence of corrosion.
The presence of water droplets (>0.1 mum) may also give rise to bacterial
growth
which not only can affect performance of the lubricant but also is unpleasant
for the
machine operator due to the oil becoming rancid and thus foul smelling.
The present invention, as set out in the accompanying claims, seeks to
overcome the
above mentioned problems by providing a surfactant composition which allows
the
formulation of oil-water mixtures which are microemulsions of water in oil and
behave as true solutions. The term "solution" herein describes any mixtures
which are
clear and homogenous. The term "behave as such" means that the mixture has
substantially the same stability as a solution.
The present invention accordingly provides, in one aspect, a water-in-oil
microemulsion comprising oil, water and a surfactant composition which
comprises
(i) a fatty acid amine ethoxylate and (ii) a C6-C15 alcohol ethoxylate. The
surfactant
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composition may optionally comprise (iii) a tall oil fatty acid amine.
The components of the surfactant composition are combined together in
quantities
that allow the formation of microemulsions on addition to the appropriate oil
and
water mixture.
The composition may comprise additional components. These have been found to
include sorbitan esters, mono and di-glycerides of fatty acids, polymeric
emulsifiers
containing fatty acid side groups, polyimides and substituted polyimides such
as poly
isobutenylsuccimide. Other surfactant types will be apparent to those versed
in the art.
Preferred components of the surfactant composition are all readily available
commercially.
A preferred surfactant composition comprises the following components:
i) 1-5 parts of a fatty acid amine ethoxylate
ii) 0.5-4 parts of alcohol ethoxylate and optionally
iii) 1.5-5 parts of tall oil fatty acid amine
the parts by volume in each case being relative to the total volume of the
surfactant
composition.
In one example, the surfactant composition comprises:
3 parts by volume of water and oil of the fatty acid amine ethoxylate, and
2 parts by volume of water and oil of the C6-C15 alcohol ethoxylate, and
optionally 2.75 parts by volume of water and oil of tall oil fatty acid amine.
In another example, the surfactant composition comprises:
3 parts by volume of water and oil of the fatty acid amine ethoxylate, and
1 parts by volume of water and oil of the C6-C15 alcohol ethoxylate, and
optionally 1.5 parts by volume of water and oil of tall oil fatty acid amine.
In a further example, the surfactant composition comprises:
2 parts by volume of water and oil of the fatty acid amine ethoxylate, and
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1 parts by volume of water and oil of the C6-C15 alcohol ethoxylate, and
optionally 3 parts by volume of water and oil of tall oil fatty acid amine.
In a highly preferred embodiment, the surfactant composition comprises the
tall oil
fatty acid amine. This component may be used to impart (further) stability to
the
microemulsion of the present invention.
The minimum quantity of the surfactant composition required is dependant upon
the
water content of the desired microemulsion and the base oil type being used.
For
example, 80 parts of a naphthenic base oil (Shell Solvent Pale" 60) was
emulsified
with 20 parts of water such that a microemulsion was obtained. This was
achieved
with the addition of 20 parts of the surfactant composition. Using a different
base oil,
based upon a paraffinic type (Shell 130 Solvent Neutral), with the same
quantities
of water and oil required 30 party of the surfactant composition to form a
microemulsion.
To determine the minimum quantity of the surfactant composition required the
surfactant is added to the oil water mixture with gentle mixing until a clear
homogenous microemulsion is obtained.
In another aspect, the present invention provides a process for forming a
clear
homogeneous water-in-oil microemulsion, comprising adding to a mixture of oil
and
water the surfactant composition as described above with gentle mixing until
the clear
homogenous water-in-oil microemulsion is formed.
In an example of the above process, there is added to a mixture of 20 parts
water and
80 parts paraffinic type base oil, an amount of 29 parts by volume relative to
the
mixture of the water and the oil, a surfactant composition comprising:
3 parts by volume of water and oil of the fatty acid amine ethoxylate, and
2 parts by volume of water and oil of the C6-C15 alcohol ethoxylate, and
optionally 2.75 parts by volume of water and oil of tall oil fatty acid amine.
In another example of the above process, there is added to a mixture of 30
parts water
and 70 parts paraffinic type base oil, an amount of 40 parts by volume
relative to the
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mixture of the water and the oil, a surfactant composition comprising:
3 parts by volume of water and oil of the fatty acid amine ethoxylate, and
1 parts by volume of water and oil of the C6-C15 alcohol ethoxylate, and
optionally 1.5 parts by volume of water and oil of tall oil fatty acid amine.
In a further example of the above process, there is added to a mixture of 10
parts
water and 90 parts paraffmic type base oil, an amount of 14 parts by volume
relative
to the mixture of the water and the oil, a surfactant composition comprising:
2 parts by volume of water and oil of the fatty acid amine ethoxylate, and
1 parts by volume of water and oil of the C6-C15 alcohol ethoxylate, and
optionally 3 parts by volume of water and oil of tall oil fatty acid amine.
In a further aspect, the present invention relates to a clear homogenous
microemulsion
produced by the above-described process.
In a further aspect, the present invention provides the microemulsion defined
above
for use an industrial lubricant.
In an even further aspect, the present invention relates to a use of the
surfactant
composition defined above to form a water-in-oil microemulsion.
In another aspect, the present invention provides a use of the surfactant
composition
defined above to prevent growth of microorganisms in an oil and water mixture.
These microemulsions will have many applications in the industrial lubricants
market.
It may be necessary for certain applications to incorporate other additives
i.e. to give
extreme pressure protection for higher temperature applications. These
applications
and additional additives will be apparent to those skilled in the art.
The invention shall now be described by way of example only.
Example 1
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A composition suitable for combining 70 parts of a paraffinic type base oil
(Shell 130
Solvent Neutral) with 30 parts of water was prepared by adding the following
components in the quantities stated:
5 3 parts fatty acid amine ethoxylate
2.75 parts tall oil fatty acid amine
2 parts C6-C~5 alcohol ethoxylate
The components were gently mixed to form a homogenous solution.
Example 2
30 ml of water was added to 70 m of Shell 130 Solvent Neutrals in a clear
glass
container. The surfactant composition of Example 1 was introduced to the oil
and
water from a burette. After each addition of surfactant the resulting solution
was
mixed. This continued until a clear homogenous solution was observed. The
resulting
solution remains stable for more than one year.
Example 3
20 ml of water was added to 80 ml of Shell Solvent Neutrals in a clear glass
container. The surfactant solution of Example 1 was introduced into the oil
and water
as in Example 2. The resulting solution remains stable for more than one year.
Example 4
The solution obtained in Example 2 was used to determine its corrosive
properties on
mild steel. This was done by placing a piece of mild steel in the solution and
observing the formation of rust. No corrosion has been observed after 6
months.
Example 5
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When using macroemulsions of oil and water problems of micro-organism growth
can
arise.
To determine whether the microemulsion of the present invention is effective
in
preventing such growth an algae was introduced to the solution of Example 2.
Any
growth of this algae was to be monitored by any colour change of the solution
as the
algae produce a green growth in macroemulsions.
No micro-organism growth was observed after 6 months. It is believed that the
compositions of the present invention prevents any micro-organism growth
because
the water droplets in the solution containing the surfactant composition are
smaller
than the micro-organisms and so there is insufficient oxygen for the algae to
grow.
Example 6
A series of tests were conducted on an industrial lathe using solutions in
Examples 2
and 3 and the neat base oil (Shell 130 Solvent Neutral). Initially the tool
bits that
were to be used were prepared by grinding to the same specification. These
were then
electron micrographed to confirm that the tool bits were to all intents and
purposes
identical. The bits were then used to lathe 75 mm external diameter mild steel
rod
down to 20 mm external diameter over a 600 mm length at a rate of 2.5 mm per
cut.
The tool bits were then electron micrographed for a second time to determine
which
bits were wearing faster. The results, which are shown in Table 1, show that
bits
containing just neat oil or neat oil with an extreme pressure additive
(CereclorTM E45)
wear considerably more quickly than those of Examples 2 and 3. The surface
finish of
the mild steel of all the samples was compared and found to be no different,
thereby
indicating no loss in the lubricity of the solutions containing water.
An added benefit was also observed during this test. When lathing the steel
the
observable amount of smoke was reduced using the solutions of Examples 2 and
3. In
addition it is believed that the emissions given by the solutions of the
present
invention will be cleaner due to the higher oxygen content because of the
presence of
water. As seen in Table 1, the swarf generated by the cutting was collected
and an
experiment was carned out to determine the oil that had become associated with
it.
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Again, the solutions from Examples 2 and 3 were shown to have an improvement
over the neat oil as less oil was associated with these cuttings.
Example 7
Microemulsions have been prepared in the following base oil types:
i) paraffinic
ii) naphthenic
iii) linear alpha olefins
iv) ester type base fluids
Example 8
A microemulsion using linear alpha olefin was prepared as in Example 2 using
35
parts of the surfactant composition. This was then tested using the lubricant
industry
standard IP287 to determine the potential of the solution to promote
corrosion. No
corrosion has been observed using this or indeed any other prepared solution.
Example 9
The solution from Example 8 was doped with a heavily contaminated soluble oil.
The
resulting solution was then tested using an agar dipslide to monitor bacterial
growth
within the solution. No culture or bacterial growth was observed after 168
hours at 35
deg. C. It is generally recognised that bacteria will be observed on the
culture medium
after 72 hours when held at 35°C.
Example 10
Solutions from Examples 2, 3 and 8 have been tested for wear prevention using
a
Reichert testing machine. This involves rotating a roller bearing over a known
distance (100 m) within a specific length of time (60 s) with a load of 1.5
Kg. When
comparing the solutions with their respective straight oils a reduction in
weight loss of
22% was observed on the solutions from Examples 2 and 3 whilst that of Example
8
showed a reduction in weight loss of 14%.
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Example 11
A hydraulic oil was prepared using the microemulsion from example 2 with an
anti-
wear additive based on sulphur. This was added at a rate of 5% v/v. A further
hydraulic oil was prepared using the same base oil and sulphur additive. Both
oils
were then tested for their anti-wear properties using the Reichert testing
apparatus.
The microemulsion showed a reduced weight loss compared to the standard oil of
10%.
Example 12
A gear oil has been prepared using a commercially available oil (GlygoyleTM
HE460
available from Mobil) and the composition of Example 1. The resulting oil has
shown
improved coolancy with no loss in lubricity using standard anti-wear tests
i.e. four
1 S ball tests.
Example 13
A grinding oil was prepared using a linear alpha olefin base oil with the
composition
of Example 1. This was tested against a standard grinding oil and was shown to
be of
superior cooling ability with no loss in lubricity.
CA 02288130 2005-05-20
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WO 98150139 PCT/GB97/OI223
TABLE 1:
ample T o 0 Diameter S p a C a Length O i 1
1 Imm a d t I of o n
Number /RPM mm cut / Swarf
mm g/Kg
Shell I 75 - 0 14 2.5 6 8.0
13
solvent 60-45 190 2.5 600
neutralTM 45 - 25 260 2.5 600
25 -20 350 2.5 600
As above 2 75 - 60 140 2.5 600 8.3
+ I % 60 - 45 190 2.5 600
Cereclor 45 - 25 260 2.5 600
F~STM 25 -20 350 2.5 600
Solution 3 75 - 60 140 2.5 600 6.1
f r o 60 - 45 190 2.5 600
m
Example3 45 - 25 260 2.5 600
25 -20 350 2.5 600
Solution 4 75 - 60 I40 2.5 600 5.5
f r o 60 - 45 190 2.5 600
m
Example2 45 - 25 260 2.5 600
25 -20 350 2.5 600
As above 5 75 - 60 140 2.5 600 5.6
+ 1 % 60 - 45 190 2.5 600
Cereclor 45 - 25 260 2.5 600
E45TM 25 -20 350 2.5 600
SUBSTtTUTE SHEET (RULE 26)
