U.S. patent application number 14/103892 was filed with the patent office on 2016-03-24 for fatty sorbitan ester based friction modifiers.
The applicant listed for this patent is Frank J. DeBlase, Venkatramanan K. Madabusi, Cyrill A. Migdal, Gerard Mulqueen. Invention is credited to Frank J. DeBlase, Venkatramanan K. Madabusi, Cyrill A. Migdal, Gerard Mulqueen.
Application Number | 20160083668 14/103892 |
Document ID | / |
Family ID | 53367673 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160083668 |
Kind Code |
A9 |
DeBlase; Frank J. ; et
al. |
March 24, 2016 |
Fatty Sorbitan Ester Based Friction Modifiers
Abstract
A friction modifier composition for reducing friction in a
lubricant comprising a fatty acid sorbitan ester that is solid or
semi-solid. The fatty acid sorbitan ester is capable of being
released into a lubricant at a rate of less than or equal to 0.15
grams per minute.
Inventors: |
DeBlase; Frank J.; (Hopewell
Junction, NY) ; Madabusi; Venkatramanan K.;
(Naugatuck, CT) ; Migdal; Cyrill A.; (Pleasant
Valley, NY) ; Mulqueen; Gerard; (Watertown,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DeBlase; Frank J.
Madabusi; Venkatramanan K.
Migdal; Cyrill A.
Mulqueen; Gerard |
Hopewell Junction
Naugatuck
Pleasant Valley
Watertown |
NY
CT
NY
CT |
US
US
US
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20150166922 A1 |
June 18, 2015 |
|
|
Family ID: |
53367673 |
Appl. No.: |
14/103892 |
Filed: |
December 12, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12371872 |
Feb 16, 2009 |
|
|
|
14103892 |
|
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Current U.S.
Class: |
508/100 |
Current CPC
Class: |
C10M 129/76 20130101;
C10M 2207/283 20130101; C10M 175/0091 20130101; C10N 2030/06
20130101; C10M 2207/289 20130101 |
International
Class: |
C10M 129/76 20060101
C10M129/76 |
Claims
1. A device for providing additives to a lubricant, the device
comprising: a fatty acid sorbitan ester that is solid or semi-solid
solid and represented by general formula: ##STR00011## wherein n
ranges from 6 to 22; and a container for holding the fatty acid
sorbitan ester, the container being configured to allow the
lubricant to flow therethrough; wherein the device is configured to
allow the lubricant to pass over and/or through the fatty acid
sorbitan ester causing the fatty acid sorbitan ester to be released
into the lubricant.
2. The device of claim 1, wherein the fatty acid sorbitan ester
comprises a mixture of fatty acid sorbitan esters.
3. The device of claim 1, wherein the fatty acid sorbitan ester is
fully saturated.
4. The device of claim 1, wherein the fatty acid sorbitan ester is
released into the lubricant at a rate ranging from about 0.0025
grams per minute to about 0.15 grams per minute.
5. The device of claim 1, wherein the container is an oil
filter.
6. The device of claim 2, wherein the container is an oil
filter.
7. The device of claim 2, wherein the fatty acid sorbitan ester is
a tallow fatty acid sorbitan ester and/or a coconut fatty acid
sorbitan ester.
8. The device of claim 7, wherein the container is an oil
filter.
9. The device claim 8, wherein the mixture of fatty acid sorbitan
esters comprises a tallow fatty acid sorbitan ester.
10. The device of claim 2, wherein the fatty acid sorbitan ester is
released into the lubricant at a rate ranging from about 0.0025
grams per minute to about 0.15 grams per minute.
11. The device of claim 5, wherein the fatty acid sorbitan ester is
released into the lubricant at a rate ranging from about 0.0025
grams per minute to about 0.15 grams per minute.
12. The device of claim 8, wherein the fatty acid sorbitan ester is
released into the lubricant at a rate ranging from about 0.0025
grams per minute to about 0.15 grams per minute.
Description
[0001] This patent application is a divisional of U.S. patent
application Ser. No, 12/371,872, filed Feb. 16, 2009, the contents
of which are incorporated herein by reference.
[0002] The present invention relates to friction modifiers for use
in lubricants. More specifically, the invention relates to the use
of fatty acid sorbitan ester based friction modifiers that are
solid or semi-solid.
BACKGROUND OF THE INVENTION
[0003] Engines and their associated parts use lubricants, such as
oil, to facilitate the movement of internal components and improve
and/or lengthen their respective working lifetimes. These
lubricants, along with various additives, possess a number of
different lubricating properties, such as properties for reducing
soot/sludge formation, corrosion or oxidation, reducing friction,
thermal decomposition, extreme pressure and wear, etc. Generally,
over the lifetime of a lubricant, additives in the lubricants
deplete and/or change form, thus reducing their effectiveness. As a
result, over time, lubricants degrade and ultimately must be
replaced.
[0004] Time release additives for lubricants may be useful to
supplement and/or provide additional lubricating properties to
lubricant compositions, thereby extending their useful lifetime.
Some slow release lubricant additives are known and, for example,
may be utilized in oil filters. Such additives may be incorporated
into thermoplastic polymers, for example, which slowly dissolve
into the oil being processed by the filter. Examples of such
additives are disclosed in U.S. Pat. No. 4,075,098, the entirety of
which is incorporated herein by reference. Other additives may be
incorporated into polymers, which are oil-permeable at elevated
engine temperatures. Examples of such additives are disclosed in
U.S. Pat. No. 4,066,559, the entirety of which is incorporated
herein by reference. Still other additives are incorporated into
particles which are oil-insoluble but oil-wettable. Examples of
such additives are disclosed in U.S. Pat. No. 5,478,463, the
entirety of which is incorporated herein by reference.
[0005] In another approach, oil-soluble solid polymers capable of
functioning as viscosity improvers are provided inside an oil
filter, with or without additional additives being incorporated
into the polymer. Examples of such additives are disclosed in U.S.
Pat. No. 4,014,794, the entirety of which is incorporated herein by
reference. Although these systems are capable of introducing
lubricant additives into the oil being filtered, they typically
require inert carriers for slow release of the additives into the
oil.
[0006] In addition, U.S. Pat. No. 7,384,896, the entirety of which
is incorporated herein by reference, discloses additive gels that
can provide additives to a functional fluid over time. The additive
gel comprises i.) at least two additives selected from the group
comprising detergents, dispersants, acids, bases, over based
detergent, succinated polyolefins or mixtures thereof wherein the
selected additives when combined form a gel; ii.) optionally at
least one additive comprising viscosity modifier(s), friction
modifier(s), detergent(s), cloud point depressant(s), pour point
depressant(s), demulsifier(s), flow improver(s), anti static
agent(s), dispersant(s), antioxidant(s), antifoam(s),
corrosion/rust inhibitor(s), extreme pressure/antiwear agent(s),
seal swell agent(s), lubricity aid(s), antimisting agent(s), and
mixtures thereof; resulting in a controlled release gel that over
time releases at least one desired additive into a functional fluid
when the gel is contacted with the functional fluid.
[0007] Also, U.S. Pat. No. 7,417,012, the entirety of which is
incorporated herein by reference, discloses a lubricant additive
gel formed by the gellation of two or more lubricant additives for
the slow release of the additive components into a fluid. The
lubricant additive gel slowly releases into its component lubricant
additives when contacted with the fluid such as an oil thereby
serving as a lubricant fluid such as an oil.
[0008] U.S. Publication No. 2006/0079413, the entirety of which is
incorporated herein by reference, discloses formulations using
tartaric compounds in a low sulfur, low ash and low phosphorous
lubricant to lower wear, and friction and improve fuel economy.
[0009] U.S. Publication No. 2007/0004601, the entirety of which is
incorporated herein by reference, discloses a release additive
composition including at least one overbased detergent present in a
form chosen from a solid and a semi-solid. Also disclosed is a
lubrication system and a method of improving the drain interval of
oil.
[0010] U.S. Publication No. 2007/0004604, the entirety of which is
incorporated herein by reference, discloses a release additive
composition including at least one dispersant viscosity index
improver present in a form chosen from a semi-solid and a
solid.
[0011] In addition, U.S. Publication No. 2007/0049505, the entirety
of which is incorporated herein by reference, discloses a method of
lubricating containing: (a) employing a first functional fluid, (b)
adding or contacting the first functional fluid with a controlled
release gel wherein the controlled release gel has the desired
additives to be released imparting the desired properties into the
first functional fluid which is for lubricating a mechanical
device; and/or adding a delivery system with the desired additives
for a second functional fluid; (c) releasing the desired additives
from the delivery system into the first functional fluid resulting
in the first functional fluid changing into a second functional
fluid, with the proviso that the second functional fluid is
different from the first functional fluid.
[0012] U.S. Publication No. 2008/0015126, the entirety of which is
incorporated herein by reference, discloses a control release gel
for delivery of additives free of producing ash to substantially
free of producing ash into a lubricant.
[0013] Finally, U.S. Publication No. 2008/0108531, the entirety of
which is incorporated herein by reference, discloses the use of
viscosity modifiers in a control release additive gel containing a
viscosity modifier that control releases additives into a
lubricant.
[0014] Even in view of the above-described lubricant additives, the
need remains for effective additives, e.g., effective friction
modifier additives, that can be released, optionally controllably
released, into a lubricant to replenish and/or enhance the
lubricating properties of the lubricant that otherwise may be
reduced over time.
SUMMARY OF THE INVENTION
[0015] In one aspect, the present invention relates to friction
modifier compositions for reducing friction in lubricants. The
friction modifier compositions comprise fatty acid sorbitan esters,
e.g., C.sub.8 or greater fatty acid sorbitan esters such as tallow
sorbitan esters, that are solid or semi-solid. In use, as the solid
or semi-solid fatty acid sorbitan ester is contacted by a
lubricant, the fatty acid sorbitan ester is released into the
lubricant, preferably over an extended period of time. As such, the
inventive composition adds and/or supplements the lubricant with
fatty acid sorbitan ester additive at a controlled rate. In another
aspect, the present invention relates to a friction modifier
composition that comprises the inventive fatty acid sorbitan
esters, discussed above, and at least one additional additive.
[0016] In another aspect, the present invention relates to a
lubricant composition. The lubricant composition may comprise a
base lubricant, e.g., a base stock, and the inventive fatty acid
sorbitan ester composition. As the fatty acid sorbitan ester
compositions are gradually blended with the base stocks, the
lubricating properties of the base stock that typically decrease
over time are replenished with the fatty acid sorbitan esters.
Thus, the newly introduced fatty acid sorbitan ester provides
supplemental lubricating properties that preferably balance the
properties lost by the lubricant over time.
[0017] In another embodiment, the invention is to a process for
improving the friction reducing ability of a lubricant. The
inventive process comprises the step of releasing, e.g., gradually
releasing, into the lubricant a C.sub.8 or greater fatty acid
sorbitan ester from a solid or semi-solid fatty acid sorbitan ester
composition. As noted above, the gradual rate of release of fatty
acid sorbitan ester composition into the lubricant replenishes the
lubricating properties of the lubricant that are lost over time. In
a preferred embodiment, the rate of release of fatty acid sorbitan
ester into the base stock is not greater than 0.5 grams per minute,
e.g., not greater than 0.15 grams per minute.
[0018] In another embodiment, the invention is to a device for
providing fatty acid sorbitan ester additives to a lubricant. The
device includes a C.sub.8 or greater fatty acid sorbitan ester that
is solid or semi-solid and a containiner for holding the fatty acid
sorbitan ester, the container being configured to allow the
lubricant to flow therethrough. The device is preferably configured
to allow the lubricant to pass over and/or through the fatty acid
sorbitan ester causing the fatty acid sorbitan ester to be released
into the lubricant
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present invention will be better understood in view of
the appended non-limiting Figures, in which:
[0020] FIG. 1 is a graph showing FT-IR spectra of a lubricant
comprising tallow fatty acid sorbitan ester monitored over time;
and
[0021] FIG. 2 is a front view also in cross section of an exemplary
system utilized to evaluate the release rate of a friction modifier
composition in to a base stock.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention relates to improving the friction
reducing ability of lubricants. In particular, the invention
relates to the use of fatty acid sorbitan esters, e.g., tallow
sorbitan esters (TSEs), which may be released, optionally
controllably released or slowly released, over extended periods of
time into the lubricants such that one or more properties of the
lubricants, e.g., the lubricating properties or friction reducing
properties, are (i) improved, (ii) substantially maintained or
(iii) reduced more slowly over time than they would in the absence
of the fatty acid sorbitan esters.
[0023] Typically, lubricant base stocks and additives that are
initially added to lubricant base stocks deteriorate over the
lubricant lifetime. Thus, the lubricating properties of lubricants
tend to decrease over time. Some time release additives have been
used to slowly provide additives to lubricants. The effectiveness
of some of these time release additives, however, leaves room for
improvement. In addition, many additives that may be suitable
friction modifiers do not gel sufficiently and/or do not lend
themselves to being controllably released. The compositions,
processes and devices of the present invention may be used to
supplement lubricants with effective additives, e.g., effective
friction reduction additives, over time, thus countering the
depletion of lubricating properties caused by the normal
deterioration of the lubricant base stocks and/or their additives.
As a result, the lubricating properties of lubricants may be
beneficially improved, maintained and/or reduced more slowly
thereby improving the overall effective lifetime of such lubricants
and the equipment in which they are utilized.
Fatty Acid Sorbitan Esters
[0024] One preferred embodiment of the present invention relates to
a friction modifier additive composition for reducing friction in a
lubricant. The friction modifier additive (also referred to herein
as a "fatty acid sorbitan ester" or "fatty acid sorbitan ester
composition") comprises a fatty acid sorbitan ester, optionally a
tallow sorbitan ester, that is solid, substantially solid or
semi-solid.
[0025] For the purposes of this specification, the term "solid"
refers to a composition having: (1) a Brookfield viscosity greater
than 5,000 cP at 100.degree. C., e.g., greater than 10,000 cP at
100.degree. C., greater than 30,000 cP at 100.degree. C., greater
than 40,000 cP at 100.degree. C. or greater than 50,000 cP at
100.degree. C.; and/or (2) an ASTM D 2240-45 Type D Durometer
Reading greater than 20, e.g., greater than 25, greater than 30,
greater than 35, greater than 45, greater than 50 or greater than
55. For the purposes of this invention, the term "semi-solid"
refers to a composition having: (1) a Brookfield viscosity greater
than 5,000 cP at at 25.degree. C., e.g., greater than 10,000 cP at
25.degree. C., greater than 15,000 cP at 25.degree. C. or greater
than 20,000 cP at 25.degree. C.; and/or (2) an ASTM D 2240-45 Type
D Durometer Reading less than 45, e.g., less than 40, less than 35,
less than 30, less than 25 or less than 20; and/or (3) an ASTM D
2240-45 Type A Durometer Reading greater than 0, e.g., greater than
0.1, greater than 0.5, greater than 1.0 or greater than 5. In
preferred embodiments, the semi-solid fatty acid sorbitan ester has
a Brookfield viscosity ranging from 1 cP to 50,000 cP, e.g., from
100 cP to 40,000 cP, from 100 cP to 20,000 cP, from 100 cP to 8,000
cP, from 1,000 to 7,000 cP or from 1,000 cP to 5,000 cP at
25.degree. C. Unless otherwise indicated, the viscosities referred
to in this specification are determined by a Brookfield Viscometer,
e.g., the viscosities are Brookfield viscosities, and are measured
at ambient temperature unless a different temperatures is
specified.
[0026] In use, as the solid fatty acid sorbitan ester or semi-solid
fatty acid sorbitan ester is contacted by a lubricant, the fatty
acid sorbitan ester is released, preferably dissolved, into the
lubricant, thereby adding and/or supplementing the lubricant with
fatty acid sorbitan ester. In one embodiment, the solid or
semi-solid (gel) state of the fatty acid sorbitan ester allows the
fatty acid sorbitan ester to be released, e.g., controllably
released at a specified release rate, into a lubricant over an
extended period of time, for example, over more than a day, over
more than a week, over more than a month or over more than a year.
In one embodiment, the viscosity of the fatty acid sorbitan ester
composition is inversely proportional to the release rate into the
lubricant. That is, as the viscosity of the fatty acid sorbitan
ester increases, the accompanying release rate will decrease.
[0027] The fatty acid sorbitan ester compositions of the present
invention lend themselves particularly well to gelation and/or
solidification and/or to controlled release into a lubricant due to
the hydrophilic chains provided by the fatty acid moiety of the
molecules. The viscosities of the inventive fatty acid sorbitan
ester compositions can be formulated to suit particular
applications. In preferred embodiments, the fatty acid sorbitan
ester composition has a Brookfield viscosity of at least about 100
cP, e.g., at least about 1,000 cP, at least about 5,000 cP, at
least about 10,000 cP, at least 15,000 cP, at least 20,000 cP, at
least 25,000 cP or at least about 30,000 cP, at 25.degree. C. In
terms of ranges, the fatty acid sorbitan ester optionally has a
Brookfield viscosity in the range of from about 1 cP to about
100,000 cP, e.g., from about 1,000 cP to about 75,000 cP, from
about 5,000 cP to about 60,000 cP, from about 10,000 cP to about
50,000 cP, or from about 10,000 cP to about 40,000 cP, at
25.degree. C. In other preferred embodiments, the Brookfield
viscosity of the fatty acid sorbitan ester composition is at least
about 5 cP, at least about 10 cP, at least about 20 cP, at least
about 100 cP, at least about 500 cP, at least about 1,000 cP, at
least about 5,000 cP or at least about 10,000 cP at 100.degree. C.
In terms of ranges, the fatty acid sorbitan ester optionally has a
Brookfield viscosity ranging from about 1 cP to about 50,000 cP,
e.g., from about 5 cP to about 40,000 cP, from about 10 cP to about
35,000 cP or from about 20 cP to about 30,000 cP, at 100.degree.
C.
[0028] In utilizing the benefits of the hydrophilic fatty acid
chains, such viscous fatty acid sorbitan ester compositions are
able to release into the respective lubricant at slow and/or
controlled rates. In various preferred embodiments, the release
rate into the lubricant is not greater than about 0.5 grams per
minute, e.g., not greater than about 0.15 grams per minute, not
greater than about 0.10 gram per minute, not greater than about
0.075 grams per minute, not greater than about 0.05 grams per
minute, not greater than about 0.03 grams per minute, not greater
than about 0.025, not greater than about 0.01 grams per minute or
not greater than 0.0025 grams per minute. In terms of ranges, the
release rate optionally ranges from about 0.0001 to about 0.5 grams
per minute, e.g., from about 0.0025 to about 0.15 grams per minute,
from about 0.01 to about 0.15 grams per minute, from about 0.01 to
about 0.1 grams per minute, from about 0.01 to about 0.05 grams per
minute or from about 0.01 to about 0.025 grams per minute. In one
embodiment, such release rates are achieved at temperatures ranging
from about 25.degree. C. to about 180.degree. C., e.g., from about
50.degree. C. to about 170.degree. C., from about 70.degree. C. to
about 150.degree. C., or from about 90.degree. C. to about
130.degree. C. In one embodiment, such release rates are achieved
at about 95.degree. C. Such fatty acid sorbitan ester compositions
surprisingly and unexpectedly have been found to function well as
friction modifiers that effectively release into lubricants at
controlled rates, e.g., slow rates.
[0029] Various fatty acid sorbitan esters and/or mixtures of fatty
acid sorbitan esters may be utilized in the present invention. In
preferred embodiments, the fatty acid sorbitan ester comprises (or
the fatty acid sorbitan esters comprise) a C.sub.4 or greater fatty
acid sorbitan ester, e.g., a C.sub.6 or greater fatty acid sorbitan
ester, a C.sub.8 or greater fatty acid sorbitan ester, a C.sub.10
or greater fatty acid sorbitan ester, a C.sub.12 or greater fatty
acid sorbitan ester or a C.sub.14 or greater fatty acid sorbitan
ester. The fatty acid sorbitan esters comprise a fatty acid moiety.
By "C.sub.n or greater fatty acid sorbitan ester" it is meant that
the fatty acid moiety contains at least n carbon atoms, including
the ester carbon atom. Thus, by "C.sub.8 or greater fatty acid
sorbitan ester," it is meant that the fatty acid moiety contains at
least 8 carbon atoms. Generally speaking, in terms of ranges, the
number of carbon atoms in the fatty acid moiety ranges from 4 to 28
carbon atoms, e.g., from 6 to 28 carbon atoms, from 8 to 22 carbon
atoms, from 10 to 20 carbon atoms or from 12 to 18 carbon atoms. In
some preferred embodiments, the fatty acid sorbitan ester may
comprise a tallow sorbitan ester and/or a coconut sorbitan
ester.
[0030] The fatty acid sorbitan ester compositions of the present
invention may be characterized by their hardness. Hardness may be
determined, as discussed above for example, under ASTM D-2240-45,
which may utilize a Type A or Type D Shore Durometer. In a
preferred embodiment, the fatty acid sorbitan ester compositions of
the present invention have a Type A hardness of at least about
0.05, e.g., at least about 0.1, at least about 0.25, at least about
0.5, at least about 1, at least about 5, at least about 10, at
least about 50, at least about 94 or at least about 100. In terms
of ranges, the hardness of the fatty acid sorbitan ester
compositions may range from 0.05 Type A to 100 Type D, e.g., from
0.25 Type A to 50 Type D, from 0.5 Type A to 40 Type D or from 5
Type A to 5 30 Type D, as measured under ASTM D-2240-45. The terms
"Type A" and "Type D" refer to the hardness measured on a Type A or
Type D Durometer, respectively.
[0031] As noted above, the fatty acid sorbitan ester compositions
of the present invention are particularly effective friction
modifiers. That is to say, the fatty acid sorbitan ester
compositions possess the ability to reduce friction in a lubricant
to which the fatty acid sorbitan ester composition is added. In one
embodiment, the effectiveness of friction modification is measured
via a Cameron Plint TE 77 High Frequency Friction Test testing
procedure. The Cameron Plint testing procedure quantifies the
coefficient of friction of the lubricant into which an additive is
released. In a preferred embodiment, the fatty acid sorbitan ester
compositions reduce the coefficient of friction of the respective
lubricant by at least 10%, e.g., at least 20%, at least 30% or at
least 40%, as measured at temperatures above 25.degree. C., e.g.,
above 40.degree. C. or above 60.degree. C. In other embodiments,
the reduced friction performance is indicated by a reduction in
average wear scar of greater than 25%, e.g., greater than 35%,
greater than 50% or greater than 60%, as measured by Cameron Plint
Wear, Falex Four Ball Wear and/or High Frequency Reciprocating Wear
(HFRR) testing.
[0032] In another embodiment, the fatty acid sorbitan ester
compositions of the present invention exhibit excellent oxidative
and/or thermal stability. In one embodiment, the thermal stability
of the fatty acid sorbitan ester composition is measured by the
decomposition onset temperature of the composition. In preferred
embodiments, the decomposition onset temperature is greater than
about 150.degree. C., e.g., greater than 180 .degree. C., greater
than about 200.degree. C., greater than about 230.degree. C. or
greater than about 250.degree. C., as measured by TGA. In terms of
ranges, the decomposition onset temperature optionally ranges from
about 150.degree. C. to about 500.degree. C., e.g., from about
235.degree. C. to about 300.degree. C. or from about 250.degree. C.
to about 275.degree. C. Also, the fatty acid sorbitan ester
compositions preferably have a thermal oxidative stability of
greater than 10 minutes, e.g., greater than 12 minutes, greater
than 15 minutes, greater than 18 minutes or greater than 25
minutes, as measured by Pressure Differential Scanning calorimetry
(PDSC) Oxidation Induction Time (OIT) testing run at 130.degree. C.
with O.sub.2 (which accelerates normal oxidation times, e.g., from
hours to minutes).
[0033] In one embodiment, the fatty acid sorbitan ester composition
comprises a mixture of several fatty acid sorbitan esters. In
another embodiment, the fatty acid sorbitan ester composition
comprises a mixture of the fatty acid sorbitan esters discussed
above. Preferably, the fatty acid sorbitan ester composition may be
a mixture TSEs and CSEs.
[0034] The fatty acid sorbitan esters of the present invention may
be represented by the general formula:
##STR00001##
wherein n is a whole number from 6 to 28, e.g., from 8 to 22, from
10 to 20 from 12 to 16 or from 14 to 18, and, preferably, n is 16
and is derived from tallow fatty acid. In another embodiment, the
fatty acid sorbitan ester has a fatty acid moiety chain length of
greater than 4 carbon atoms, e.g., greater than 6 carbon atoms,
greater than 8 carbon atoms or greater than 10 carbon atoms. For
example, the tallow fatty acid ester may comprise a lauryl sorbitan
ester in which the fatty acid moiety contains about 12 carbon
atoms. Typically, the fatty acid sorbitan ester compositions of the
invention will include a mixture of various fatty acid sorbitan
ester compounds, and the above general formula is merely exemplary
of some of the tallow fatty acid esters contained in the
composition. The fatty acid carbon chain may be straight chain or
branched, and saturated or partially unsaturated, or a mixture
thereof.
[0035] Additionally or alternatively, the fatty acid sorbitan ester
compositions of the invention may include fatty acid sorbitan
esters that are substituted, e.g., substituted with one or more of
alkyl, aryl, acyl alkoxy and/or phenyl groups. In one embodiment,
the fatty acid sorbitan esters are substituted with alkyl
groups.
[0036] In some embodiments, the fatty acid sorbitan esters are
completely saturated. For example, in a preferred embodiment, the
fatty acid moiety is a C.sub.12 laurate. In other embodiments, the
fatty acid sorbitan esters are partially saturated. For example,
the fatty acid moiety may comprise a C.sub.18 oleate. In still
other embodiments, the fatty acid sorbitan esters are unsaturated
or completely unsaturated. Preferably, the saturation may be
achieved via hydrogenation. As a result, the fatty acid sorbitan
esters may be saturated, e.g., fully saturated, hydrogenated fatty
acid sorbitan esters.
[0037] Suitable fatty acid sorbitan esters are commercially
available as Kemester.TM. 5632.
Preparation
[0038] The fatty acid sorbitan esters of the present invention, in
one embodiment, are prepared by reacting a fatty acid, e.g., a
tallow fatty acid (TFA), with one or more sorbitols and/or
sorbitans. In some embodiments, the fatty acid is reacted with a
sorbitol to form a fatty acid sorbitol. In one embodiment, the
sorbitol moiety of such a fatty acid sorbitol is cyclized to form
the fatty acid sorbitan. In other embodiments, the sorbitol is
cyclized to form a sorbitan, which may then be reacted with the
fatty acid to form the fatty acid sorbitan. In still other
embodiments, a mixture of sorbitols and sorbitans are reacted with
the fatty acid. The fatty acid sorbitols that result from this
reaction may then be cyclized to form the fatty acid sorbitans.
[0039] The fatty acid used to form the fatty acid sorbitan esters
of the invention preferably has the structure:
##STR00002##
wherein n is a whole number from 6 to 28, e.g., from 8 to 22, from
10 to 20 from 12 to 16 or from 14 to 18, and, preferably, n is 16.
The carbon chain in the fatty acid (as well as the resulting fatty
acid sorbitan ester composition of the invention) may be fully
saturated, partially unsaturated or a combination thereof.
Unsaturation in the fatty acid is usually determined by iodine
number, which in preferred embodiments, can vary 100 to less than
1, e.g., from 90 to less than 1 or from 65 to less than 1,
depending on the amount of unsaturated fatty acid and whether the
fatty acid is further saturated by hydrogenation. In one
embodiment, the fatty acid (as well as the resulting fatty acid
sorbitan ester composition of the invention) includes partially
unsaturated tallow fatty acids having the general formula:
##STR00003##
wherein x and y are whole numbers, and (x+y) equals the sum of from
4 to 26, e.g., from 6 to 20, from 8 to 18 or from 12 to 16, and,
preferably, (x+y) is 14. In one embodiment, the fatty acid sorbitan
ester is multiply unsaturated. In still another embodiment, the
level of multiple unsaturation is less than 10%, e.g., less than
7%, less than 5% or less than 3%. For example, where x=7 and y=7,
the resulting partially unsaturated fatty acid has the
structure:
##STR00004##
It is noted that this formula shows the fatty acid in cis-form. In
other embodiments, the fatty acid is in the trans-form. Thus, the
fatty acid may be the cis form, the trans form, or a mixture
thereof. In certain embodiments, the cis-form is "kinked" and may
soften more than the trans-form. This phenomenon may be useful in
particular applications. In a preferred embodiment, the fatty acid
(and the resulting fatty acid sorbitan ester composition of the
invention) comprises a mixture of fully saturated fatty acids and
partially unsaturated fatty acids. In other embodiments, such fatty
acids may be substituted at any one or more of the carbons. The
substituents may include, for example, one or more alkyl, aryl,
acyl, alkoxy and/or branched alkyl(iso-stearic) groups.
[0040] In various optional embodiments, the fatty acid is selected
from one or more of stearic acid, oleic acid, myristic acid and/or
a palmitic acid. Of course, these fatty acides are merely exemplary
and other fatty acids may be employed to form the fatty acid
sorbitan ester compositions of the invention.
[0041] In preferred embodiments, the sorbitans are prepared by the
cyclization of sorbitols. Sorbitols may be represented by the
following general formula:
##STR00005##
and may comprise a mixture of stereoisomers thereof. The dominant
sorbitol stereoisomer that preferably is employed to form the fatty
acid sorbitan ester compositions of the present invention is
represented by the following formula, and preferably is present in
the reactant sorbitol in an amount greater than 60 wt. %, greater
than 80 wt. % or greater than 90 wt. %, based on the total weight
of the sorbitol reactant employed:
##STR00006##
[0042] In preferred embodiments, sorbitol, e.g., D-sorbitol or
D-glucitol, may be cyclized, e.g. dehydrized, to form D-sorbitans,
which may be utilized in the reaction with fatty acids (see above)
to form the fatty acid sorbitan esters of the invention. The
cyclization reaction is preferably achieved in the presence of a
phosphoric acid catalyst at elevated temperatures, e.g., greater
than 150.degree. C., greater than 200.degree. C. or greater than
250.degree. C., and may form the cyclized D-sorbitan isomers shown
below.
##STR00007##
[0043] The D-sorbitans having the 3, 6 linkage and/or the
1,4-linkage may further dehydrize to form the corresponding
bicyclic isosorbide.
##STR00008##
[0044] In preferred embodiments, the fatty acid is reacted with the
sorbitan, e.g. 1,4-sorbitan, to form a mixture of the following
mono-, di- and tri-esters. As will be appreciated by those skilled
in the art, many various isomers of the mono-, di- and tri-esters
may be formed and these chemical formulae are merely exemplary of
the some of the mono-, di- and tri-esters that may be formed.
##STR00009##
[0045] In preferred embodiments, a tallow fatty acid is reacted
with the sorbitan, e.g., a 1,4-sorbitan, to provide a mixture of
mono-, di- and tri-esters, e.g., tallow sorbitan mono-esters,
tallow sorbitan di-esters, tallow sorbitan tri-esters.
Additionally, isosorbide may be added to the reaction (i.e.,
generated in a separate reaction) or generated in-situ from the
sorbitans to form one or more isosorbide esters, as shown
below.
##STR00010##
[0046] Thus, in another embodiment, a tallow fatty acid is
esterified by one or more isosorbides to yield one or more tallow
isosorbide esters. In a preferred embodiment, a mixture of
saturated and unsaturated tallow fatty acids, and saturated and
unsaturated coconut fatty acids are esterified by one or more
isosorbides to form a mixture of tallow isosorbide esters and
coconut isosorbide esters.
[0047] The molar ratios of the various mono-esters, di-esters,
tri-esters and/or isosorbide esters to one another in the fatty
acid sorbitan ester may be manipulated to control the viscosity of
the fatty acid sorbitan ester composition. Optionally, the molar
ratio of mono-esters to di-esters, of mono-esters to tri-esters, of
mono-esters to the combination of both di-esters and tri-esters, or
of mono-esters to isosorbide esters in the fatty acid sorbitan
ester compositions of the invention may range from 1:10 to 10:1,
e.g., from 1:5 to 5:1, or about 1:1. Most preferably, the molar
ratio of mono-esters to di-esters, or mono-esters to tri-esters, or
mono-esters to the combination of both di-esters and tri-esters is
at least 1:10, e.g., at least 1:5, at least 1:2 or at least 1:1.
The distribution of the ratio of the mono-, di-, tri- and
isosorbide esters that are formed may be used to manipulate the
chemical and physical properties of the final product, and,
accordingly, the performance of the final product. The distribution
may, for example, be controlled by the stoichiometry of the
reactants, the type of catalyst employed, e.g., acid and/or base,
and other reaction conditions. Referring to the reactions discussed
above, in a preferred embodiment, tallow fatty acids, e.g.,
C.sub.14-C.sub.18, m is 0, (1+n) is 13. In another preferred
embodiment 1 is 6, m is 1 and n is 5. In another embodiment, excess
fatty acid is utilized to favor formation of the di- and
tri-esters. The manipulation of the reaction parameters may be
utilized to affect physical/tribological properties, sorbitol
dehydration, degree of esterification and degree of
unsaturation.
[0048] In a preferred embodiment, the fatty acid sorbitan ester
compositions of the present invention are formulated to be solid or
semi-solid, e.g., solid or semi-solid tablets, which are released,
preferably dissolved, over time in the respective lubricant. Thus,
another embodiment the invention is directed to a lubricant
composition comprising a lubricant base stock and a fatty acid
sorbitan ester composition of the invention. In still another
embodiment, the fatty acid sorbitan ester is directed through a
flow retarding tight cellulose barrier (utilizing sugar functional
group-cellulose sugar molecular attraction). The fatty acid
sorbitan ester may be either or both (i) in solid or semi-solid
form, and/or (i) dispersed or dissolved in the base stock (but
derived from the fatty acid sorbitan ester composition in solid or
semi-solid form).
[0049] Preferably, the fatty acid is directly esterified by one or
more sorbitans. In a preferred embodiment, a fatty acid halide is
esterified by one or more sorbitans to yield the fatty acid
sorbitan esters of the present invention. For example, a tallow
acid halide may be reacted with one or more sorbitans to form one
or more TSEs.
[0050] Alternatively, a methyl tallowate may be indirectly
transesterified by the sorbitol. In a preferred embodiment, the
sorbitol is dehydrated to form a cyclic sugar. The dehydrated
sorbitol may then be reacted with the fatty acid to form the fatty
acid sorbitan ester. One preferred embodiment utilizes a tallow
fatty acid containing 3% Myristic (Tetradecanoic: C.sub.14), 0.4%
(cis-9-Tetradecenoic: C.sub.14:1), 26.3% Palmitic (Hexadecanoic:
C.sub.16), 2.6% (cis-9-Hexadecenoic), 0.4% (Heptacecanoic:
C.sub.17), 0.4% (Heptadecenoic C.sub.17:1).sub., 22.4% Stearic
(Octadecanoic: C.sub.18), 43.1% Oleic: (cis-9-Octadecenoic), and
1.4% Linoleic (cis-9, cis-12-Octadecadienoic: C.sub.18:2).
[0051] In addition to the fatty acid sorbitan ester compositions,
in other embodiments, the invention is directed to methods of
producing fatty acid sorbitan esters comprising esterifying one or
more fatty acids, e.g., tallow fatty acids, with one or more
sorbitols or sorbitans to form one or more fatty acid sorbitan
esters as well as to methods of producing fatty acid sorbitan
esters comprising trans-esterifying one or more fatty acids, e.g.,
tallow fatty acids, with one or more sorbitols or sorbitans to form
the one or more fatty acid sorbitan esters. The reaction parameters
discussed above are also applicable to the inventive methods for
producing fatty acid sorbitan esters.
[0052] The reaction conditions employed to form the fatty acid
sorbitan ester compositions of the invention may vary widely.
Preferably, the fatty acid is reacted with the sorbitan at a
temperature ranging from about 25.degree. C. to about 300.degree.
C., e.g., from about 50.degree. C. to about 300.degree. C., from
about 100.degree. C. to about 280, from about 150.degree. C. to
about 280.degree. C., from about 180.degree. C. to about
250.degree. C. or about 200.degree. C. to about 250.degree. C. In
some embodiments, the reaction takes place at pressures ranging
from about 1 torr to about 400 torr, e.g., from about 2 torr to
about 350 torr, from about 10 torr to about 300 torr or from about
10 torr to about 200 torr. In one embodiment, the pressure at which
the reaction is run is increased by utilizing nitrogen N.sub.2
sparging. In other embodiments the molar ratio of sorbitol to fatty
acid ranges from about 10:1 to about 1:10, e.g., from about 6:1 to
about 1:6, from about 3:1 to about 1:3 or from about 1:1 to about
1:2. Preferably, the molar ratio is about 1:1. In other
embodiments, the molar ratio of sorbitol to fatty acid may be
selected depending upon the desired level of di-ester and/or
tri-ester.
[0053] The reaction may take place in any suitable reactor known in
the art. Preferably, the reactor is a stainless steel reactor or a
glass-lined reactor. In one embodiment, the reaction may be run as
a batch process. In another embodiment, the reaction may be run in
a continuous manner. In still other embodiments, suitable catalysts
may be utilized to promore the reaction. In one embodiment,
residual catalyst is neutralized before obtaining the final
product. In other embodiments, the final product is washed, e.g.,
washed with water, to remove the catalyst salts from the reaction
mixture. In other embodiments, the water wash serves to separate
and, optionally remove, any unreacted sorbitol. Such a procedure
may be followed by atmospheric and/or vacuum stripping to remove
residual water. Of course, this list is not limiting and other
separation methods may be employed.
Additives
[0054] In addition to being effective friction modifiers, the fatty
acid sorbitan esters of the present invention are well suited to
combination with other additional additives, which may be
separately added to the lubricant or contained within the solid or
semi-solid fatty acid sorbitan ester compositions of the invention,
i.e., as a solid solution or mixture. In the latter embodiment, the
fatty acid sorbitan ester compositions beneficially may function to
gradually release the additive as the fatty acid sorbitan ester
compound is released into the lubricant. The mixture of the
additives may be achieved in any suitable manner known in the art.
In a preferred embodiment, the fatty acid sorbitan esters and the
additional additives are mechanically mixed together and pressed
into a single solid mass. In another preferred embodiment, the
individual fatty acid sorbitan esters and additional additives are
melted, e.g., heated to above the respective melting points, and
blended in the molten state. The molten material may then be cooled
to form the solid fatty acid sorbitan ester composition.
[0055] Thus, in some embodiments, the invention is to a friction
modifier composition (fatty acid sorbitan ester composition)
comprising one or more fatty acid sorbitan esters and one or more
additives. In some embodiments of the present invention, the
friction modifier composition, i.e., fatty acid sorbitan ester
composition, further comprises one or more of the following:
viscosity modifiers, additional friction modifiers, detergents,
cloud point depressants, pour point depressants, demulsifiers, flow
improvers, antistatic agents, dispersants, antioxidants, antifoams,
corrosion inhibitors, rust inhibitors, extreme pressure/antiwear
agents, seal swell agents, lubricity acids, antimisting agents and
mixtures thereof.
[0056] In one embodiment of the invention, the fatty acid sorbitan
esters and the (at least one) additional additives are combinable
in any amount or in any ratio. In one embodiment, the composition
comprises the fatty acid sorbitan ester in a major amount and other
additive(s) in a minor amount. In other embodiments, the fatty acid
sorbitan esters are present in an amount ranging from 5 weight
percent to 95 weight percent, e.g., from 10 weight percent to 90
weight percent, from 20 weight percent to 80 weight percent, from
25 weight percent to 75 weight percent or from 25 weight percent to
60 weight percent, based on the total weight of the fatty acid
sorbitan ester composition. In other embodiments, the additional
additives are present in an amount ranging from 5 weight percent to
95 weight percent, e.g., from 10 weight percent to 90 weight
percent, from 20 weight percent to 80 weight percent, from 25
weight percent to 75 weight percent or from 25 weight percent to 60
weight percent, based on the total weight of the fatty acid
sorbitan ester composition. In terms of ratios, the ratio of fatty
acid sorbitan ester to additional additive(s) may range from 10:1
to 1:10, e.g., from 2:8 to 8:2, from 3:6 to 6:3 or from 1:2 to
2:1.
[0057] The fatty acid sorbitan esters of the present invention
perform particularly well with antioxidants. Accordingly, preferred
embodiments include combinations of fatty acid sorbitan esters and
antioxidants, e.g., aminic antioxidants and phenolic antioxidants.
Preferred aminic antioxidants are octylated diphenylamine and
liquid aminics: phenyl-.alpha.-napthylamine; nonylated
diphenylamine; styrenated diphenylamine; octylated butylated
diphenylamine; other alkylated diphenylamines;
N,N'-di-sec-butyl-p-phenylenediamine;
N-phenyl-N'alkyl-p-phenylenediamine;
N,N'-di-isopropyl-p-phenylenediamine and mixtures thereof.
Preferably, these aminic antioxidants are solid. Preferred phenolic
antioxidants are solid phenolics, BHT, Pyrogallol,
Tert-butyl-hydroquinone, as well as liquid phenolics:
2,6-di-tertbutylphenol, 2,4-di-methyl-6-tertbutylphenol,
2-methyl-6-tertbutylphenol, 2-tertbutyl-4-methylphenol;
2,6-dimethyl-4-tertbutylphenol;
2,6-bis(.alpha.-methylbenzyl)-4-methylphenol and mixtures thereof.
In addition, preferred embodiments may utilize, as aminic
antioxidants, Naugalube 438L, Naugalube.TM. 403, Naugalube.TM. 420,
Naugalube.TM. 410, and mixtures thereof. These are commercial
products manufactured by Chemtura Corporation. Additionally or
alternatively, preferred embodiments may utilize, as phenolic
antioxidants, Naugalube FAO.TM. 30, Naugalube FAO.TM. 31, Naugalube
FAO.TM. 32. Further preferred embodiments utilize blends of
antioxidants including, but not limited to, Naugalube.TM. 403,
Naugalube.TM. 420, Naugalube.TM. 431, Naugalube.TM. 438,
Naugalube.TM. 438L, Naugalube.TM. 531, Naugalube.TM. 635,
Naugalube.TM. 640, Naugalube.TM. 680 Naugalube.TM. ANS,
Naugalube.TM. APAN, Naugalube.TM. PANA, Naugalube FAO.TM. 80,
Naugalube FAO.TM. 100 and mixtures thereof. In addition, preferred
embodiments utilize Moldpro 873 laurylamide of diethanol amine,
which is a commercial product formerly manufactured by Chemtura
Corporation, and is also manufactured by other manufacturers, e.g.,
Stepan Corp.
[0058] In some embodiments, the inventive fatty acid sorbitan ester
compositions comprise tartrates and/or citrates. These tartrates
and/or citrates may be substituted by alkyl, aryl, acyl alkoxy
and/or, alkoxyl groups. A particularly preferable embodiment
utilizes an alkyl tartrate in combination with the fatty acid
sorbitan ester. Preferably, the additional additives include
C.sub.12-C.sub.14 acetal of tartrate, diethyl tartrate, diisopropyl
tartrate, and mixtures thereof. In preferred embodiments, the alkyl
tartrate is HXL 7121 or HXL 7353, which are laboratory experimental
products produced by Chemtura Corporation. In another preferred
embodiment, the HXL 7121 or HXL 7353 is combined with the fatty
acid sorbitan ester at a ratio of about 1:10 to about 10:1, e.g.,
from about 2:8 to about 8:2, about 0.25:1 to about 2:1 or about
0.5:1 to about 0.75:1.
[0059] In a preferred embodiment, the fatty acid sorbitan ester
composition is blended with a viscosity modifier to adjust
viscosity. In other embodiments, viscosity modifiers such as
alkanolamides, poly-.alpha.-olefins, polyisobutylenes and
polyethers are combined with the fatty acid sorbitan ester. In
other preferred embodiments, a high-molecular weight viscosity
modifier, e.g., having a M.sub.w greater than 5,000, greater than
10,000 or greater than 20,000, is utilized to adjust the viscosity
of the fatty acid sorbitan ester composition. In a preferred
embodiment, the fatty acid sorbitan ester is combined with a lauryl
diethanolamide at a molar ratio of from 1:10 to 10:1, e.g., from
2:8 to 8:2 or about 1:1.
[0060] Of course, additives other than those listed above may be
utilized in combination with the fatty acid sorbitan esters and the
additives mentioned above. Examples of other additives follow.
[0061] Ashless dispersants may be utilized, including Mannich
dispersants, polymeric dispersants, carboxylic dispersants, amine
dispersants, and combinations and mixtures thereof, all of which
are substantially free of forming ash or are completely free of
forming ash. In one embodiment, the preferred dispersant is
polyisobutenyl succinimide dispersant.
[0062] Suitable ashless dispersants include, but are not limited
to, ashless dispersants such as a polyisobutenyl succinimide.
Polyisobutenyl succinimide ashless dispersants are commercially
available products which are typically made by reacting together
polyisobutylene having a number average molecular weight (M.sub.n)
of about 300 to 10,000 with maleic anhydride to form polyisobutenyl
succinic anhydride (PIBSA) and then reacting the product so
obtained with a polyamine typically containing 1 to 10 ethylene
amino groups per molecule. The dispersant so obtained is typically
formed from a mixture of different compounds and can be
characterized by a variety of different variables including the
degree of amine substitution (i.e., the ratio of the equivalents of
amino groups to carbonylic groups, or the N:CO ratio), the maleic
anhydride conversion level (i.e., the molar ratio of maleic
anhydride to PIB, as defined in U.S. Pat. No. 4,234,435, which is
hereby incorporated by reference in its entirety), the M.sub.n of
the PIB group, and the mode of preparation (thermal assisted
succination vs. Cl.sub.2-assisted succination). Analogous compounds
made with other polyamines (e.g. polypropenyl) may also be used.
Ashless dispersants of this type are described, for example, in
U.S. Pat. No. 4,234,435, which is hereby incorporated by reference
in its entirety.
[0063] The Mannich dispersants may be the reaction products of
alkyl phenols in which the alkyl group contains at least about 30
carbon atoms with aldehydes (especially formaldehyde) and amines
(especially polyalkylene polyamines).
[0064] Another class of suitable ashless dispersants is nitrogen
containing carboxylic dispersants. Examples of these "carboxylic
dispersants" are described in Patent U.S. Pat. No. 3,219,666, which
is hereby incorporated by reference in its entirety.
[0065] Suitable amine dispersants, include, but are not limited to,
reaction products of relatively high molecular weight aliphatic
halides and amines, preferably polyalkylene polyamines. Examples
thereof are described, in U.S. Pat. No. 3,565,804 which is hereby
incorporated by reference in its entirety.
[0066] Suitable polymeric dispersants include, but are not limited
to, interpolymers of oil-solubilizing monomers such as decyl
methacrylate, vinyl decyl ether and high molecular weight olefins
with monomers containing polar substituents, e.g., amino alkyl
acrylates or acrylamides and poly-(oxyethylene)-substituted
acrylates. Examples of polymer dispersants thereof are disclosed in
the following U.S. Pat. Nos. 3,329,658 and 3,702,300, each of which
are hereby incorporated by reference in its entirety.
[0067] Dispersants may also be post-treated by reaction with any of
a variety of agents. Among these are urea, thiourea,
dimercaptothiazoles, carbon disulfide, aldehydes, ketones,
carboxylic acids, hydrocarbon-substituted succinic anhydrides,
nitriles, expoxides, boron compounds, and phosphorus compounds.
[0068] Specific antioxidants other than those discussed above
include, but are not limited to, alkyl-substituted phenols such as
2,6-di-tertiary butyl-4-methyl phenol, phenate sulfides,
phosphosulfurized terpenes, sulfurized esters, aromatic amines,
diphenyl amines, alkylated diphenyl amines and hindered phenols,
bis-nonylated diphenylamine, nonyl diphenylamine, octyl
diphenylamine, bis-octylated diphenylamine, bis-decylated
diphenylamine, decyl diphenylamine and mixtures thereof.
[0069] Suitable sterically hindered phenols include, but are not
limited to, 2,6-di-tert-butylphenol,
4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol,
4-propyl-2,6-di-tert-butylphenol, 4-butyl-2,6-di-tert-butylphenol,
4-pentyl-2-6-di-tert-butylphenol, 4-hexyl-2,6-di-tert-butylphenol,
4-heptyl-2,6-di-tert-butylphenol,
4-(2-ethylhexyl)-2,6-di-tert-butylphenol,
4-octyl-2,6-di-tert-butylphenol, 4-nonyl-2,6-di-tert-butylphenol,
4-decyl-2,6-di-tert-butylphenol, 4-undecyl-2,6-di-tert-butylphenol,
4-dodecyl-2,6-di-tert-butylphenol,
4-tridecyl-2,6-di-tert-butylphenol,
4-tetradecyl-2,6-di-tert-butylphenol, methylene-bridged sterically
hindered phenols include but are not limited to
4,4-methylenebis(6-tert-butyl-o-cresol),
4,4-methylenebis(2-tert-amyl-o-cresol),
2,2-methylenebis(4-methyl-6-tert-butylphenol),
4,4-methylene-bis(2,6-di-tertbutylphenol) and mixtures thereof
[0070] Suitable extreme pressure (EP)/anti-wear agents include, but
are not limited to, a sulfur or chlorosulphur EP agent, a
chlorinated hydrocarbon EP agent, or a phosphorus EP agent, or
mixtures thereof. Examples of such EP agents are amine salts of
phosphorus acid acid, chlorinated wax, organic sulfides and
polysulfides, such as benzyldisulfide, bis-(chlorobenzyl)disulfide,
dibutyl tetrasulfide, sulfurized sperm oil, sulfurized methyl ester
of oleic acid sulfurized alkylphenol, sulfurized dipentene,
sulfurized terpene, and sulfurized Diels-Alder adducts;
phosphosulfurized hydrocarbons, such as the reaction product of
phosphorus sulfide with turpentine or methyl oleate, phosphorus
esters such as the dihydrocarbon and trihydrocarbon phosphate,
i.e., dibutyl phosphate, diheptyl phosphate, dicyclohexyl
phosphate, pentylphenyl phosphate; dipentylphenyl phosphate,
tridecyl phosphate, distearyl phosphate and polypropylene
substituted phenol phosphate, metal thiocarbamates, such as zinc
dioctyldithiocarbamate and barium heptylphenol diacid, such as zinc
dicyclohexyl phosphorodithioate and the zinc salts of a
phosphorodithioic acid combination may be used and mixtures
thereof.
[0071] In one embodiment, the fatty acid sorbitan ester composition
includes an antiwear agent/EP agent comprising an amine salt of a
phosphorus ester acid. The amine salt of a phosphorus ester acid
includes phosphoric acid esters and salts thereof,
dialkyldithiophosphoric acid esters and salts thereof, phosphites;
and phosphorus-containing carboxylic esters, ethers, and amides;
and mixtures thereof.
[0072] Suitable amines other than those mentioned above include,
but are not limited to, primary amines, secondary amines, tertiary
amines, and mixtures thereof. These amines include those with at
least one hydrocarbyl group, or, in certain embodiments, two or
three hydrocarbyl groups. The hydrocarbyl groups may contain about
2 to about 30 carbon atoms, or in other embodiments about 8 to
about 26 or about 10 to about 20 or about 13 to about 19 carbon
atoms.
[0073] Suitable primary amines may include ethylamine, propylamine,
butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as
well as such fatty amines as n-octylamine, n-decylamine,
n-dodecylamine, n-tetradecylamine, n-hexadecylamine,
n-octadecylamine and oleylamine. Other useful fatty amines include
commercially available fatty amines such as "ArmeenOR" amines
(products available from Akzo Chemicals, Chicago, Ill.), such as
Armeen C, Armeen O, Armeen O L, Armeen T, Armeen H T, Armeen S and
Armeen S D, wherein the letter designation relates to the fatty
group, such as coco, oleyl, tallow, or stearyl groups.
[0074] Examples of suitable secondary amines include dimethylamine,
diethylamine, dipropylamine, dibutylamine, diamylamine,
dihexylamine, diheptylamine, methylethylamine, ethylbutylamine and
ethylamylamine. The secondary amines may be cyclic amines such as
piperidine, piperazine and morpholine.
[0075] In some embodiments, the amine may also be a
tertiary-aliphatic primary amine. The aliphatic group in this case
may be an alkyl group containing about 2 to about 30, or about 6 to
about 26, or about 8 to about 24 carbon atoms. Tertiary alkyl
amines include monoamines such as tert-butylamine, tert-hexylamine,
1-methyl-1-amino-cyclohexane, tert-octylamine, tert-decylamine,
tert-dodecylamine, tert-tetradecylamine, tert-hexadecylamine,
tert-octadecylamine, tert-tetracosanylamine, and
tert-octacosanylamine.
[0076] Mixtures of amines may also be used in the invention. In one
embodiment a useful mixture of amines is "Primene.TM. 81R" and
"Primene.TM. JMT." Primene.TM. 81R and Primene.TM. JMT (produced
and sold by Rohm & Haas) are mixtures of C.sub.11 to C.sub.14
tertiary alkyl primary amines and C.sub.18 to C.sub.22 tertiary
alkyl primary amines respectively.
[0077] In one embodiment, the hydrocarbyl amine salt of an
alkylphosphoric acid ester is the reaction product of a C.sub.14 to
C.sub.18 alkylated phosphoric acid with Primene 81.TM. (produced
and sold by Rohm & Haas) which is a mixture of C.sub.11 to
C.sub.14 tertiary alkyl primary amines.
[0078] Examples of suitable hydrocarbyl amine salts of
dialkyldithiophosphoric acid esters include the reaction product(s)
of hexyl, heptyl or octyl or nonyl, 4-methyl-2-pentyl or
2-ethylhexyl, isopropyl dithiophosphoric acids with ethylene
diamine, morpholine, or Primene 81R.TM., and mixtures thereof.
[0079] In one embodiment, the dithiophosphoric acid is reacted with
an epoxide or a glycol. This reaction product is further reacted
with a phosphorus acid, anhydride, or lower ester. The epoxide may
include an aliphatic epoxide or a styrene oxide. Examples of
suitable epoxides include ethylene oxide, propylene oxide, butene
oxide, octene oxide, dodecene oxide, styrene oxide and the like. In
one embodiment, the epoxide is propylene oxide. Suitable glycols
may be aliphatic glycols having from 1 to about 12, or from about 2
to about 6, or about 2 to about 3 carbon atoms. The
dithiophosphoric acids, glycols, epoxides, inorganic phosphorus
reagents and methods of reacting the same are described in U.S.
Pat. Nos. 3,197,405 and 3,544,465, each of which are incorporated
herein by reference in its entirety. The resulting acids may then
be salted with amines. An example of suitable dithiophosphoric acid
is prepared by adding phosphorus pentoxide (about 64 grams) at
about 58.degree. C. over a period of about 45 minutes to about 514
grams of hydroxypropyl O,O-di(4-methyl-2-pentyl)phosphorodithioate
(prepared by reacting di(4-methyl-2-pentyl)-phosphorodithioic acid
with about 1.3 moles of propylene oxide at about 25.degree. C.).
The mixture is heated at about 75.degree. C. for about 2.5 hours,
mixed with a diatomaceous earth and filtered at about 70.degree. C.
The filtrate contains about 11.8% by weight phosphorus, about 15.2%
by weight sulfur, and an acid number of 87 (bromophenol blue).
[0080] Suitable antifoams include, but are not limited to, organic
silicones such as poly dimethyl siloxane, poly ethyl siloxane,
polydiethyl siloxane, polyacrylates and polymethacrylates,
trimethyl-triflouro-propylmethyl siloxane and the like.
[0081] Suitable viscosity modifiers other than those discussed
above may provide both viscosity improving properties and
dispersant properties. Examples of dispersant-viscosity modifiers
include, but are not limited to, vinyl pyridine, N-vinyl
pyrrolidone and N,N'-dimethylaminoethyl methacrylate are examples
of nitrogen-containing monomers and the like. Polyacrylates
obtained from the polymerization or copolymerization of one or more
alkyl acrylates also are useful as viscosity modifiers.
[0082] In some embodiments, functionalized polymers are used as
viscosity modifiers. Among the common classes of such polymers are
olefin copolymers and acrylate or methacrylate copolymers.
Functionalized olefin copolymers can be, for instance,
interpolymers of ethylene and propylene which are grafted with an
active monomer such as maleic anhydride and then derivatized with
an alcohol or an amine. Other such copolymers are copolymers of
ethylene and propylene which are reacted or grafted with nitrogen
compounds. Derivatives of polyacrylate esters are well known as
dispersant viscosity index modifiers additives. Dispersant acrylate
or polymethacrylate viscosity modifiers such as Acryloid.TM. 985 or
Viscoplex.TM. 6-054, from RohMax, are particularly suitable. Solid,
oil-soluble polymers such as the PIB, methacrylate,
polyalkystyrene, ethylene/propylene and
ethylene/propylene/1,4-hexadiene polymers and maleic
anhydride-styrene interpolymer and derivatives thereof, can also be
used as viscosity index improvers.
[0083] In one embodiment, the friction modifiers other than those
mentioned above may include organo-molybdenum compounds, including
molybdenum dithiocarbamates, and fatty acid based materials,
including those based on oleic acid, including glycerol
mono-oleate, those based on stearic acid, and the like.
[0084] In one embodiment, the friction modifier is a phosphate
ester or salt including a monohydrocarbyl, dihydrocarbyl or a
trihydrocarbyl phosphate, wherein each hydrocarbyl group is
saturated. In several embodiments, each hydrocarbyl group contains
from about 8 to about 30, or from about 12 up to about 28, or from
about 14 up to about 24, or from about 14 up to about 18 carbons
atoms. In another embodiment, the hydrocarbyl groups are alkyl
groups. Examples of hydrocarbyl groups include tridecyl,
tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl groups and
mixtures thereof.
[0085] In one embodiment, the phosphate salts may be prepared by
reacting an acidic phosphate ester with an amine compound or a
metallic base to form an amine or a metal salt. The amines may be
monoamines or polyamines. Useful amines include those amines
disclosed in U.S. Pat. No. 4,234,435, which is hereby incorporated
by reference in its entirety.
[0086] Metal salts of the phosphorus acid esters that are prepared
by the reaction of a metal base with the acidic phosphorus ester
may be utilized in combination with the fatty acid sorbitan esters.
The metal base may be any metal compound capable of forming a metal
salt. Examples of metal bases include metal oxides, hydroxides,
carbonates, borates, or the like. Suitable metals include alkali
metals, alkaline earth metals and transition metals. In one
embodiment, the metal is a Group IIA metal, such as calcium or
magnesium, Group IIB metal, such as zinc, or a Group VIIB metal,
such as manganese. Examples of metal compounds which may be reacted
with the phosphorus acid include zinc hydroxide, zinc oxide, copper
hydroxide or copper oxide.
[0087] In one embodiment, additional friction modifiers such as
phosphites may be utilized, such phosphites include, but are not
limited to, monohydrocarbyl, dihydrocarbyl or trihydrocarbyl
phosphites, wherein each hydrocarbyl group may be saturated. In
other embodiments, each hydrocarbyl group independently contains
from about 8 to about 30, or from about 12 up to about 28, or from
about 14 up to about 24, or from about 14 up to about 18 carbons
atoms. In one embodiment, the hydrocarbyl groups are alkyl groups.
Examples of hydrocarbyl groups include tridecyl, tetradecyl,
pentadecyl, hexadecyl, heptadecyl, octadecyl groups and mixtures
thereof.
[0088] In one embodiment, the additional friction modifier may be a
fatty imidazoline comprising fatty substituents containing from 8
to about 30, or from about 12 to about 24 carbon atoms. The
substituent may be saturated or unsaturated, preferably saturated.
In one aspect, the fatty imidazoline may be prepared by reacting a
fatty carboxylic acid with a polyalkylenepolyamine, such as those
discussed above. A suitable fatty imidazoline includes those
described in U.S. Pat. No. 6,482,777, which is hereby incorporated
by reference in its entirety.
[0089] Suitable anti-misting agents include, but are not limited
to, very high (.gtoreq.100,000 M.sub.n) polyolefins such as 1.5 Mn
polyisobutylene (for example the material of the trades name
Vistanex.TM.), or polymers containing 2-(N-acrylamido), 2-methyl
propane sulfonic acid (also known as AMPS.TM.), or derivatives
thereof.
[0090] Suitable corrosion inhibitors include, but are not limited
to, alkylated succinic acids and anhydrides derivatives thereof,
organo phosphonates and the like. The rust inhibitors may be used
alone or in combination.
[0091] Suitable ashless metal deactivators include, but are not
limited to, derivatives of benzotriazoles such as tolyltriazole,
N,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine,
N,N-bis(nonyl)-ar-methyl-1H-Benzotriazole-l-methanamine,
N,N-bis(decyl)ar-methyl-1H-Benzotriazole-1-methanamine,
N,N-(undecyl)ar-methyl-1H-benzotriazole-1-methanamine,
N,N-bis(dodecyl)ar-methyl-1H-Benzotriazole-l-methanamine
N,N-bis(2-ethylhexyl)-ar-methyl-1H-Benzotriazole-1-methanamine and
mixtures thereof. In one embodiment the metal deactivator is
N,N-bis(1-ethylhexyl)ar-methyl-1H-benzotriazole-1-methanamine;
1,2,4-triaz-oles, benzimidazoles, 2-alkyldithiobenzimidazoles;
2-alkyldithiobenzothiazoles;
2-N,N-dialkyldithio-carbamoyl)benzothiazoles;
2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles such as
2,5-bis(tert-octyldithio)-1,3,4-thiadiazole
2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-decyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-undecyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-tridecyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-tetradecyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-octadecyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-nonadecyldithio)-1,3,4-thiadiazole,
2,5-bis(tert-eicosyldithio)-1,3,4-thiadiazole and mixtures thereof;
2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazoles; and
2-alkydithio-5-mercapto thiadiazoles.
[0092] Suitable demulsifiers include, but are not limited to,
polyethylene and polypropylene oxide copolymers and the like.
Suitable lubricity aids include, but are not limited to, glycerol
mono oleate, sorbitan mono oleate and the like. Suitable flow
improvers include, but are not limited to, ethylene vinyl acetate
copolymers and the like. Suitable cloud point depressants include,
but are not limited to, alkylphenols and derivatives thereof,
ethylene vinyl acetate copolymers and the like. Suitable pour point
depressants include, but are not limited to, alkylphenols and
derivatives thereof, ethylene vinyl acetate copolymers and the
like. Suitable seal swell agents include, but are not limited to,
organo sulfur compounds such as thiophene,
3-(decyloxy)tetrahydro-1,1-dioxide, phthalates and the like. These
additional additives may be used alone or in combination.
[0093] In preferred embodiments of the present invention, the fatty
acid sorbitan ester compositions contain no ash, e.g., the fatty
acid sorbitan ester compositions are ash-free, or contain minimal
ash. In other preferred embodiments, the fatty acid sorbitan ester
compositions contain minimal amounts of heavy metals or are free of
heavy metals. Furthermore, in other embodiments, the fatty acid
sorbitan ester compositions contain no or minimal amounts of zinc
dialkyl dithio phosphate (ZDDP), e.g., less than 10 weight percent,
less than 5 weight percent, less than 3 weight percent or less than
1 weight percent, based on the total weight of the fatty acid
sorbitan ester composition.
Lubricant Compositions
[0094] In addition to the fatty acid sorbitan ester compositions,
the invention also relates to a lubricant composition comprising
the fatty acid sorbitan ester compositions discussed above and a
base lubricant, e.g., a base stock. Typically, as base stocks are
utilized to lubricate the respective systems and/or devices, the
lubricating properties of the base stock deteriorate over time.
When the fatty acid sorbitan ester compositions of the present
invention are gradually blended with the base stocks, the
lubricating properties that are lost over time are replenished by
the fatty acid sorbitan esters. Thus, the newly introduced fatty
acid sorbitan esters provide supplemental lubricating properties
that balance the properties lost by the lubricant over time. In
other words, the controllably released fatty acid sorbitan esters
of the present invention preferably work to increase, maintain or
slow the reduction of lubricating properties in a base stock
throughout the lifetime of the lubricant. In one embodiment, the
fatty acid sorbitan ester composition is released, e.g.,
controllably released, into the base stock. In a preferred
embodiment, the fatty acid sorbitan ester is controllably released
into the base stock at the rates discussed above.
[0095] In preferred embodiments, free fatty acid sorbitan ester is
present in the lubricant composition in an amount ranging from
about 1 part per million to about 50,000 parts per million, e.g.,
from about 1 part per million to about 5,000 parts per million,
from about 1 part per million to about 1000 parts per million or
from about 50 parts per million to about 750 parts per million,
based on the total parts by weight of the lubricant composition. In
this context, "free" fatty acid sorbitan ester refers to fatty acid
sorbitan ester that is solubilized or dispersed in the base stock
exclusive of solid or semi-solid fatty acid sorbitan ester
composition from which the free fatty acid sorbitan ester may be
derived.
[0096] In other preferred embodiments, in addition to the free
fatty acid sorbitan esters, the inventive lubricant compositions
may further comprise additional additives, as discussed above. In
preferred embodiments, the suitable additional additives are
present in the lubricant in an amount ranging from about 1 part per
million to about 50,000 parts per million, e.g., from about 1 part
per million to about 5,000 parts per million, from about 1 part per
million to about 1000 parts per million or from about 50 parts per
million to about 750 parts per million, based on the total parts of
the lubricant composition. Of course, the desired concentration of
the one or more additives will vary widely depending on the
additive in question and its purpose. In preferred embodiments, the
additional additives of the lubricant composition comprises one or
more alkyl tartrates, e.g., one or more of HXL 7121 and/or HXL
7353. The HXL 7121 and/or HXL 7353 may be combined with the fatty
acid sorbitan ester at a ratio ranging from 10:1 to 1:10, e.g.,
from 2:8 to 8:2, from 3:6 to 6:3 or from 1:2 to 2:1. Preferably,
the ratio of HXL 7121 and/or HXL 7353 to fatty acid sorbitan ester
is about 1:1. The one or more alkyl tartrates may be added
separately to the base stock or may be incorporated in a solid or
semi-solid fatty acid sorbitan ester composition such that the one
or more alkyl tartrates are gradually released into the base
stock.
[0097] In other embodiments, the fatty acid sorbitan ester
compositions of the present invention may be utilized in fuel
compositions. In such embodiments, all of the parameters that apply
to lubricant compositions/lubricant combinations apply equally to
the use of the fatty acid sorbitan esters in fuel compositions and
in methods and devices for improving the friction reducing ability
of fuels or fuel compositions. In preferred embodiments, the
inventive fatty acid sorbitan ester compositions can be utilized in
fuel filters much the same way as has been described in relation to
lubricant, e.g., oil filters. In preferred embodiments, the fatty
acid sorbitan esters can be utilized with fuels such as,
hydrocarbon fuels, gasoline, diesel fuels, and biodiesel.
[0098] Preferably, the fatty acid sorbitan esters and/or additives
are released into the base stock at a release rate not greater than
about 0.5 grams per minute, e.g., not greater than about 0.15 grams
per minute, not greater than about 0.10 gram per minute, not
greater than about 0.075 grams per minute, not greater than about
0.05 grams per minute, not greater than about 0.03 grams per
minute, not greater than about 0.025, not greater than about 0.01
grams per minute or not greater than 0.0025 grams per minute. In
terms of ranges, the release rate optionally ranges from about
0.0001 to about 0.5 grams per minute, e.g., from about 0.0025 to
about 0.15 grams per minute, from about 0.01 to about 0.15 grams
per minute, from about 0.01 to about 0.1 grams per minute, from
about 0.01 to about 0.05 grams per minute or from about 0.01 to
about 0.025 grams per minute. The release rates may be measured at
temperatures of at least 25.degree. C., e.g., at least 50.degree.
C., at least 60.degree. C., at least 70.degree. C., at least
80.degree. C., at least 90.degree. C., at least 95.degree. C., at
least 105.degree. C., at least 120.degree. C. or at least
150.degree. C.
[0099] In preferred embodiments, the fatty acid sorbitan esters
and/or the additional additives released into the base stock reduce
the coefficient of friction of the overall lubricant composition.
In a preferred embodiment, the fatty acid sorbitan esters and/or
the additional additives that have been released in to the
respective base stock reduce the coefficient of friction of the
respective lubricant, as measured via the Cameron Plint testing
method discussed above, by at least 50%, e.g., at least 40%, at
least 30%, at least 20% or at least 10%, as measured at
temperatures greater than or equal to 50.degree. C., e.g., greater
than or equal to 70.degree. C., greater than or equal to 90.degree.
C. or greater than or equal to 110.degree. C. In other embodiments,
the reduced friction performance is indicated by a reduction in
average wear scar of greater than 25%, e.g., greater than 35%,
greater than 50% or greater than 60%, as measured by Cameron Plint
Wear, Falex Four Ball Wear and/or High Frequency Reciprocating Wear
(HFRR) testing.
[0100] In other preferred embodiments, the fatty acid sorbitan
ester compositions reduce the coefficient of friction in the
resultant lubricating composition to below .1.0, e.g., below 0.8,
below 0.75, below 0.7, below 0.6, below 0.4 or below 0.1, as
compared to the lubricating composition without the fatty acid
sorbitan ester composition. These coefficients of friction may be
measured at temperatures greater than 100.degree. C., e.g., greater
than 120.degree. C., greater than 130.degree. C., greater than
150.degree. C., greater than 175.degree. C. or greater than
200.degree. C.
Base Stocks
[0101] In preferred embodiments, the base stock is selected from
natural oils, e.g., mineral oils, petroleum oils, vegetable oils,
paraffinic oils, naphthenic oils, aromatic oils, synthetic oils,
and derivatives and mixtures thereof. The synthetic oils may
comprise at least one of an oligomer of an .alpha.-olefin, an
ester, an oil derived from a Fischer-Tropsch process, and a
gas-to-liquid stock. In one preferred embodiment, the base stock is
Excell 100HC.TM. produced by Penzoil. In other preferred
embodiments, the base stock may be only one or more of all Group I,
II, III base stocks produced by producers such as Conoco Philips,
Chevron, Exon, Shell, Conoco-Philips, Petro-Canada ex. VHVI-4 and
Purity 1003].
[0102] In other embodiments, the base lubricants may include, but
are not limited to, other natural oils including animal oils and
vegetable oils, e.g., lard oil, castor oil, and hydrorefined,
solvent-treated or acid-treated mineral oils of mixed
paraffinic-naphthenic types. Oils of lubricating viscosity derived
from coal or shale also serve as useful base oils. Other examples
of oils and fats derived from animal or vegetable material are
rapeseed oil, coriander oil, soya bean oil, cottonseed oil,
sunflower oil, castor oil, olive oil, peanut oil, maize oil, almond
oil, canola oil, jojoba oil, palm kernel oil, coconut oil, mustard
seed oil, jatropha oil, beef tallow, and fish oils. Further
examples include oils derived from corn, jute, sesame, shea nut,
ground nut, and linseed oil, and may be derived therefrom by
methods known in the art. Rapeseed oil, which is a mixture of fatty
acids partially esterified with glycerol, is available in large
quantities and can be obtained in a simple way by pressing from
rapeseed. Recycled oils such as used kitchen oils are also
suitable.
[0103] Useful base stocks are, for example, alkyl esters of fatty
acids, which include commercial mixtures of the ethyl, propyl,
butyl and especially methyl esters of fatty acids with 12 to 22
carbon atoms. For example, lauric acid, myristic acid, palmitic
acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid,
petroselic acid, ricinoleic acid, elaeostearic acid, linoleic acid,
linolenic acid, eicosanoic acid, gadoleic acid, docosanoic acid, or
erucic acid are useful and have an iodine number from 50 to 150,
especially 90 to 125. Mixtures with particularly advantageous
properties are those which contain mainly, i.e., at least 50 wt. %,
methyl esters of fatty acids with 16 to 22 carbon atoms and 1, 2,
or 3 double bonds. The preferred lower alkyl esters of fatty acids
are the methyl esters of oleic acid, linoleic acid, linolenic acid,
and erucic acid.
[0104] Commercial mixtures of the stated kind are obtained for
example by cleavage and esterification of animal and vegetable fats
and oils by their transesterification with lower aliphatic
alcohols. For production of alkyl esters of fatty acids, it is
advantageous to start from fats and oils which contain low levels
of saturated acids, less than 20%, and which have an iodine number
of less than 130. Blends of the following esters or oils are
suitable, e.g., rapeseed, sunflower, coriander, castor, soya bean,
peanut, cotton seed, beef tallow, and the like. Alkyl esters of
fatty acids based on a new variety of rapeseed oil, the fatty acid
component of which comprises more than 80 wt. % unsaturated fatty
acids with 18 carbon atoms, are preferred.
[0105] Particularly preferred base stocks are oils capable of being
utilized as biofuels. Biofuels, i.e., fuels derived from animal or
vegetable material, are believed to be less damaging to the
environment on combustion and are obtained from a renewable source.
It has been reported that on combustion less carbon dioxide is
formed by the equivalent quantity of petroleum distillate fuel,
e.g., diesel fuel, and very little sulfur dioxide is formed.
Certain derivatives of vegetable oil, e.g., those obtained by
saponification and re-esterification with a monohydric alkyl
alcohol, can be used as a substitute for diesel fuel.
[0106] Preferred biofuels are vegetable oil derivatives, of which
particularly preferred biofuels are alkyl ester derivatives of
rapeseed oil, cottonseed oil, soya bean oil, sunflower oil, olive
oil, or palm oil, rapeseed oil methyl ester being especially
preferred, either alone or in admixture with other vegetable oil
derivatives, e.g., mixtures in any proportion of rapeseed oil
methyl ester and palm oil methyl ester.
[0107] At present, biofuels are most commonly used in combination
with petroleum-derived oils. The present invention is applicable to
mixtures of biofuel and petroleum-derived fuels in any ratio. For
example, at least 5%, preferably at least 25%, more preferably at
least 50%, and most preferably at least 95% by weight of the oil,
may be derived from a plant or animal source.
[0108] Synthetic base stock lubricating oils include hydrocarbon
oils and halo-substituted hydrocarbon oils such as polymerized and
interpolymerized olefins (e.g., polybutylenes, polypropylenes,
propylene-isobutylene copolymers, chlorinated polybutylenes,
poly(1-hexenes), poly(1 octenes), poly(1-decenes)); alkylbenzenes
(e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls,
terphenyls, alkylated polyphenols); and alkylated diphenyl ethers
and alkylated diphenyl sulfides and derivative, analogs, and
homologs thereof. Also useful are synthetic oils derived from a gas
to liquid process from Fischer-Tropsch synthesized hydrocarbons,
which are commonly referred to as gas to liquid or "GTL" base
oils.
[0109] Alkylene oxide polymers and interpolymers and derivatives
thereof where the terminal hydroxyl groups have been modified by
esterification, etherification, etc., constitute another class of
known synthetic lubricating oils. These are exemplified by
polyoxyalkylene polymers prepared by polymerization of ethylene
oxide or propylene oxide and the alkyl and aryl ethers of
polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol
ether having a molecular weight of 1000 or diphenyl ether of
polyethylene glycol having a molecular weight of 1000 to 1500), and
mono- and polycarboxylic esters thereof, for example, the acetic
acid esters, mixed C.sub.3-C.sub.8 fatty acid esters, and C.sub.13
oxo acid diester of tetraethylene glycol.
[0110] Another suitable class of synthetic base stock lubricating
oils comprises the esters of dicarboxylic acids (e.g., phthalic
acid, succinic acid, alkyl succinic acids and alkenyl succinic
acids, maleic acid, azelaic acid, suberic acid, sebasic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid,
alkylmalonic acids, alkenyl malonic acids) with a variety of
alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether,
propylene glycol). Specific examples of such esters includes
dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate,
dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl
phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl
diester of linoleic acid dimer, and the complex ester formed by
reacting one mole of sebacic acid with two moles of tetraethylene
glycol and two moles of 2 ethylhexanoic acid.
[0111] Esters useful as synthetic oils also include those made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols and polyol
esters such as neopentyl glycol, trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
Silicon-based oils (such as the polyalkyl-, polyaryl-, polyalkoxy-,
or polyaryloxy-siloxane oils and silicate oils) comprise another
useful class of synthetic lubricating oils. Other synthetic
lubricating oils include liquid esters of phosphorus-containing
acids, polymeric tetrahydrofurans, poly-.alpha.-olefins, and the
like.
[0112] Silicon-based oils such as the polyalkyl-, polyaryl-,
polyalkoxy- or polyaryloxysilicone oils and silicate oils comprise
another useful class of synthetic base stock lubricants; such oils
include tetraethyl silicate, tetraisopropyl silicate,
tetra-(2-ethylhexyl)silicate,
tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl)
silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane,
poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other
synthetic lubricating oils include liquid esters of
phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl
phosphate, diethyl ester of decylphosphonic acid) and polymeric
tetrahydrofurans.
[0113] The lubricating oil may be derived from unrefined, refined,
rerefined oils, or mixtures thereof. Unrefined oils are obtained
directly from a natural source or synthetic source (e.g., coal,
shale, or tar and bitumen) without further purification or
treatment. Examples of unrefined oils include a shale oil obtained
directly from a retorting operation, a petroleum oil obtained
directly from distillation, or an ester oil obtained directly from
an esterification process, each of which is then used without
further treatment. Refined oils are similar to unrefined oils,
except that refined oils have been treated in one or more
purification steps to improve one or more properties. Suitable
purification techniques include distillation, hydrotreating,
dewaxing, solvent extraction, acid or base extraction, filtration,
percolation, and the like, all of which are well-known to those
skilled in the art. Rerefined oils are obtained by treating refined
oils in processes similar to those used to obtain the refined oils.
These rerefined oils are also known as reclaimed or reprocessed
oils and often are additionally processed by techniques for removal
of spent additives and oil breakdown products.
[0114] Lubricating oil base stocks derived from the
hydroisomerization of wax may also be used, either alone or in
combination with the aforesaid natural and/or synthetic base
stocks. Such wax isomerate oil is produced by the
hydroisomerization of natural or synthetic waxes or mixtures
thereof over a hydroisomerization catalyst. Natural waxes are
typically the slack waxes recovered by the solvent dewaxing of
mineral oils; synthetic waxes are typically the wax produced by the
Fischer-Tropsch process. The resulting isomerate product is
typically subjected to solvent dewaxing and fractionation to
recover various fractions having a specific viscosity range. Wax
isomerate is also characterized by possessing very high viscosity
indices, generally having a viscosity index of at least 130,
preferably at least 135 or higher and, following dewaxing, a pour
point of about -20.degree. C. or lower.
[0115] The base stock of lubricating viscosity can comprise a Group
I, Group II, or Group III base stock or base oil blends of the
aforementioned base stocks. Preferably, the oil of lubricating
viscosity is a Group II or Group III base stock, or a mixture
thereof, or a mixture of a Group I base stock and one or more of a
Group II and Group III. Preferably, a major amount of the oil of
lubricating viscosity is a Group II, Group III, Group IV, or Group
V base stock, or a mixture thereof. The base stock, or base stock
blend, preferably has a saturate content of at least 65%, e.g., at
least 75% or at least 85%. Most preferably, the base stock, or base
stock blend, has a saturate content of greater than 90%.
[0116] Additionally, suitable fuels may include Fischer-Tropsch
fuels. Fischer-Tropsch fuels, also known as FT fuels, include those
described as gas-to-liquid (GTL) fuels, biomass-to-liquid (BTL)
fuels and coal conversion fuels. To make such fuels, syngas
(CO+H.sub.2) is first generated and then converted to normal
paraffins by a Fischer-Tropsch process. The normal paraffins can
then be modified by processes such as catalytic cracking/reforming
or isomerization, hydrocracking and hydroisomerization to yield a
variety of hydrocarbons such as iso-paraffins, cyclo-paraffins and
aromatic compounds. The resulting FT fuel can be used as such or in
combination with other fuel components and fuel types. Also
suitable are diesel fuels derived from plant or animal sources.
These can be used alone or in combination with other types of
fuel.
[0117] Preferably the volatility of the oil or oil blend, as
measured by the Noack volatility test (ASTM D5880), is less than or
equal to 30%, preferably less than or equal to 25%, more preferably
less than or equal to 20%, most preferably less than or equal to
16%. Preferably, the viscosity index (VI) of the oil or oil blend
is at least 85, preferably at least 100, most preferably from about
105 to 140.
[0118] Definitions for the base stocks and base oils in this
invention are the same as those found in the American Petroleum
Institute (API) publication "Engine Oil Licensing and Certification
System," Industry Services Department (14th ed., December 1996),
Addendum 1, Dec. 1998. This publication categorizes base stocks as
follows.
[0119] (a) Group I base stocks contain less than 90 percent
saturates (as determined by ASTM D 2007) and/or greater than 0.03
percent sulfur (as determined by ASTM D 2622, ASTM D 4294, ASTM D
4927 and ASTM D 3120) and have a viscosity index greater than or
equal to 80 and less than 120 (as determined by ASTM D 2270).
[0120] (b) Group II base stocks contain greater than or equal to 90
percent saturates (as determined by ASTM D 2007) and less than or
equal to 0.03 percent sulfur (as determined by ASTM D 2622, ASTM D
4294, ASTM D 4927 and ASTM D 3120) and have a viscosity index
greater than or equal to 80 and less than 120 (as determined by
ASTM D 2270).
[0121] (c) Group III base stocks contain greater than or equal to
90 percent saturates (as determined by ASTM D 2007) and less than
or equal to 0.03 percent sulfur (as determined by ASTM D 2622, ASTM
D 4294, ASTM D 4927 and ASTM D 3120) and have a viscosity index
greater than or equal to 120 (as determined by ASTM D 2270).
[0122] (d) Group IV base stocks are polyalphaolefins (PAO).
[0123] (e) Group V base stocks include all other base stocks not
included in Groups I, II, III, or IV.
Processes for Improving Friction Reducing Ability
[0124] The invention also relates to processes for improving the
friction reducing ability of a lubricant. The process comprises
releasing into the lubricant, e.g., base stock, a fatty acid
sorbitan ester that is solid or semi-solid. In preferred
embodiments, the fatty acid sorbitan ester is as described above in
relation to the fatty acid sorbitan ester composition and the
lubricant composition. In addition to the fatty acid sorbitan
ester, additional additives may, preferably, be released into the
lubricant. These additional lubricants may be those described
above. As a result of the characteristics and properties of the
fatty acid sorbitan ester and/or the additional lubricants, e.g.,
viscosity and/or solid or semi solid state, in preferred
embodiments, the release of the fatty acid sorbitan ester and/or
additional additives into the lubricant is at a controlled rate,
e.g., a gradual rate. In preferred embodiments, the fatty acid
sorbitan ester composition is released into the lubricant at a rate
release rate not greater than about 0.5 grams per minute, e.g., not
greater than about 0.15 grams per minute, not greater than about
0.10 gram per minute, not greater than about 0.075 grams per
minute, not greater than about 0.05 grams per minute, not greater
than about 0.03 grams per minute, not greater than about 0.025, not
greater than about 0.01 grams per minute or not greater than 0.0025
grams per minute. In terms of ranges, the release rate optionally
ranges from about 0.0001 to about 0.5 grams per minute, e.g., from
about 0.0025 to about 0.15 grams per minute, from about 0.01 to
about 0.15 grams per minute, from about 0.01 to about 0.1 grams per
minute, from about 0.01 to about 0.05 grams per minute or from
about 0.01 to about 0.025 grams per minute. The release rates may
be measured at temperatures of at least 25.degree. C., e.g., at
least 50.degree. C., at least 60.degree. C., at least 70.degree.
C., at least 80.degree. C., at least 90.degree. C., at least
95.degree. C., at least 105.degree. C. or at least 120.degree. C.
In some embodiments, the fatty acid sorbitan ester composition is
released into a lubricating composition slowly over a long period
of time, such as the life of the lubricating composition, e.g., at
least one day, at least one week, at least one month or at least
one year. In other embodiments, the fatty acid sorbitan ester can
be delivered into the base oil over the time between oil changes.
For example, the fatty acid sorbitan ester may be delivered into
the base oil over a mileage span of less than 20,000 miles, e.g.,
less than 15,000 miles, less than 10,000 miles, less than 8,000
miles, less than 5,000 miles, less than 3,000 miles or less than
1,000 miles.
[0125] As noted above, the gradual rate of release of fatty acid
sorbitan ester composition into the lubricant, replenishes the
lubricating properties of the lubricant that are lost over time. In
preferred embodiments, the release of the fatty acid sorbitan ester
composition is achieved by contacting the fatty acid sorbitan ester
composition with the lubricant. Typically, the fatty acid sorbitan
ester composition may be delivered by any means by which the fatty
acid sorbitan ester composition can be brought into contact with
the lubricant. The fatty acid sorbitan ester composition can be
used in any lubricating conditioning device including, but not
limited to, internal combustion engines, natural gas engines,
stationary engines, marine diesel engines, power equipment,
hydraulic systems, lubricated mechanical systems, transmission
systems, gears, differentials, metal working coolant systems,
industrial lubricated systems, compressors and the like. For
example, in an engine related application, the contacting of the
fatty acid sorbitan ester composition with the lubricant may be
achieved via a container/delivery device can be placed in an oil
filter or within an oil pan or within a fluid by-pass loop to
contact the fatty acid sorbitan ester composition with the
lubricant. In other embodiments, the fatty acid sorbitan ester
composition may be located in a drain pan, an oil bypass loop, a
canister, a housing, a reservoir, pockets of the filter, a canister
in the filter, mesh in the filter, canister in a bypass system or
mesh in a bypass system. Of course, these examples are not
exclusive of other potential applications. In one embodiment, the
fatty acid sorbitan ester composition is placed in one or more
locations in the lubrication system. In another embodiment, more
than one fatty acid sorbitan ester composition, e.g., different
fatty acid sorbitan ester/additive combinations, can be utilized in
a single system.
[0126] In preferred embodiments, the addition of the fatty acid
sorbitan ester composition is dependent upon the desired form of
the additive composition, the desired speed of addition, the
desired release rate, the desired mode of operation and/or any of
the combinations of the above. In one embodiment, the fatty acid
sorbitan ester composition is semi-solid and is added to the
lubrication system by means of an injector pump, or a container in
an oil filter. In another embodiment, the fatty acid sorbitan ester
composition is a solid and is introduced into the lubricating oil
system by means of an auger.
Lubricating Device (Filter)
[0127] In view of the above, the invention also relates to a device
for providing one or more fatty acid sorbitan esters and optionally
one or more additives to a lubricant, e.g., to a base stock. The
device comprises the fatty acid sorbitan ester composition, as
discussed above, and a container for containing the fatty acid
sorbitan ester composition. In preferred embodiments, the container
is configured to have the lubricant flowing therethrough. With the
lubricant flowing through the container, the lubricant may contact
the fatty acid sorbitan ester composition, e.g., pass over and/or
through the fatty acid sorbitan ester composition, thereby
releasing the fatty acid sorbitan ester composition into the
lubricant.
[0128] In preferred embodiments, the container is an oil filter. In
one embodiment, the sugar based sorbitol moiety of the fatty acid
sorbitan ester provides an affinity to a cellulosic material, which
may be used as the filter media. In some embodiments, the oil
filter comprises a housing, such as a sleeve or cup, that can be
partitioned, for example with a non-diffusible barrier, thereby
creating at least one pocket. Each pocket may comprise an
identical, similar and/or a different release additive composition
wherein the composition can be in an identical, similar and/or
different form, such as a semi-solid or solid form. A non-limiting
example of this concept includes one pocket comprising a fatty acid
sorbitan ester composition in a solid form and a second pocket
comprising a fatty acid sorbitan ester composition in a semi-solid
form. In other embodiments, multiple pockets may comprise all solid
or all semi-solid fatty acid sorbitan ester compositions and/or
additives. In preferred embodiments, the filter is a desirable
location to place the fatty acid sorbitan ester composition because
the fatty acid sorbitan ester and/or spent additives may easily be
removed and then replaced with a new and/or recycled fatty acid
sorbitan ester composition. In yet another embodiment, the fatty
acid sorbitan ester composition is located anywhere within the
lubrication system. For example, the release additive can be
located outside of an oil filter on the "dirty" side or it can be
located inside of the oil filter on the "clean" side. One of
ordinary skill in the art would understand that the location of the
release additive in the lubrication system is not critical so long
as the release additive composition is in contact with a
lubricating composition.
EXAMPLES
[0129] Embodiments of the invention will become more evident in
view of the following non-limiting examples.
Example 1
Preparation of Fatty Acid Sorbitan Esters
[0130] Fatty acid sorbitan esters were prepared under the following
parameters.
Case 1
[0131] Excess 1,4 Sorbitol is reacted with tallow fatty acid (TFA)
using a single step approach, under mild conditions without a
catalyst for 12 hours. The TFA, Industrene 143, is charged into the
1,4-Sorbitol, Sorbitol 9033, at a mole ratio of 6:1 sorbitol:TFA.
The reaction is kept at 180.degree. C. for 12 hours. The yield is
characterized by monitoring the FT-IR absorbance at 1739.6 cm-1
(Tallow-fatty acid sorbitan ester), and 1704 cm.sup.-1 (Tallow
Fatty acid). Although not a typical commercial process, mostly
mono-ester is formed.
Case 2
[0132] The reaction of Case 1 is repeated at higher TFA levels--1:1
sorbitol:TFA mole ratio. The resultant product contained a greater
concentration of the di-ester--at least 25% greater.
Case 3
[0133] An acidic catalyst is used with a sorbitol:TFA mole ratio of
6:1 and a temperature of 180.degree. C. for 6 hrs. Although, as
examples, sulfuric acid phosphoric acid, (NaH.sub.2PO.sub.3),
p-toluenesulfonic acid and benzene sulfonic acid to may typically
be used, methane sulfonic acid may also be used at a low treat rate
of 0.1 wt. % and reacted for 6 hrs. The resultant product contained
higher mono-ester concentration as compared with the product of the
non-catalyzed reaction.
Case 4
[0134] A base catalyzed approach is used with potassium
tert-butoxoide at 0.5 wt % and reacted for 6 hrs. at 180.degree. C.
with a sorbitol:TFA mole ratio of 6:1. This case may generate more
mono-ester, thus, loadings closer to 1:1 sorbitol to TFA may be
used. The resultant product contained higher mono-ester
concentration.
Cases 5 and 6
[0135] A methane sulfonic acid and K-tert-butoxide catalyst
respectively are run for 6 hrs with a 1:1 sorbitol:TFA mole ratio.
Following these approaches, the use of transesterification of the
methyl tallowate with sorbitan at lower temperatures may be
performed in a two step process (see Cases 7 and 8, below).
Case 7
[0136] Tallow triglyceride is reacted under methanol reflux with
KOH/MeOH to generate methyl Tallowate and glycerine, which is
removed leaving clean Methyl-Tallowate. Following the generation of
the methyl-Tallowate, a transesterification reaction at a 1:1 mole
ratio (sorbitol:Methyl-Tallowate) may be carried out using
potassium tert-butoxide catalyst 0.2% Wt. at 80.degree. C. This
approach is the less severe than higher temperature direct fatty
acid esterification and generates a tallow sorbitan of a good light
color.
Case 8
[0137] In order to form more mono-ester, the reaction is repeated
with a 6:1 sorbitol:Methyl-Tallowate, again, with potassium
tert-butoxide (0.2% Wt.). All catalyzed reaction products are
treated to neutralize the existing catalyst which is then removed
by filtration, aqueous washing is utilized to remove catalyst salts
and unreacted sorbitol/sorbitan or isosorbide followed by stripping
off the residual under vacuum.
Case 9
[0138] The assistance of dimethyl-formamide solvent is explored in
Case 9. Tallow sorbitan was synthesized by first generating the
methyl-tallowate ester, followed by a 1:1 mole ratio of Sorbitol to
methyl-Tallowate dissolved in dimethyl formamide to assist in the
reaction using 0.2% potassium tert-butoxide catalyst and reacting
at 78.degree. C.-82.degree. C. under a moderate N.sub.2 sparge to
remove the methanol and light vacuum. This approach generates
primarily mono-ester tallow sorbitan. In addition to reacting
tallow fatty acid with 1,4-sorbitan, several reactions may be
undertaken to react the methyl-Tallowate with Isosorbide using
potassium tert-butoxide under house vacuum. The role of the
methyl-tallowate and isosorbide is to generate blending stocks for
developing a rage of hardness in the solid or semi-solid tallow
sorbitan/isosorbide friction modifier.
Example 2
Friction Reducing Ability of Inventive TSE Compositions
[0139] A base stock, Excell 100 HC, was blended with 500 parts per
million of TSE compositions A, B and C, the parts per million based
on the total parts of the base stock. Composition A comprises TSE.
Composition B comprises equal parts of TSE and HXL 7121.
Composition C comprises equal parts of TSE and HXL 7353. The
results of Cameron Plint friction testing (Coefficient of Friction,
("CoF"), data) are shown in TABLE 1 for Excell 100 HC, TSE, HXL
7121, and HXL 7353, individually; and for inventive combinations A,
B and C.
TABLE-US-00001 TABLE 1 Excell Excell 100 100 HC HC Excell Excell
with Excell with 100 100 TSE 100 TSE Excell HC HC and HC and 100 HC
with with HXL with HXL without TSE Percent HXL 7121 Percent HXL
7353 Percent additives (A) Red. 7121 (B) Red. 7121 (C) Red. Temp.,
CoF CoF (A) CoF CoF (B) CoF CoF (C) .degree. C. 0.112 0.078 30.4%
0.078 0.08 28.6% 0.079 0.078 30.4% 60 0.117 0.079 32.5% 0.081 0.078
33.3% 0.09 0.077 34.2% 70 0.118 0.079 33.1% 0.093 0.076 35.6% 0.098
0.077 34.7% 80 0.117 0.082 29.9% 0.103 0.075 35.9% 0.097 0.077
34.2% 90 0.113 0.085 24.8% 0.105 0.075 33.6% 0.094 0.078 31.0% 100
0.112 0.088 21.4% 0.099 0.076 32.1% 0.09 0.078 30.4% 110 0.112
0.087 22.3% 0.094 0.069 38.4% 0.083 0.078 30.4% 120 0.112 0.087
22.3% 0.089 0.066 41.1% 0.08 0.069 38.4% 130 0.113 0.096 15.0%
0.086 0.063 44.2% 0.079 0.069 38.9% 140 0.116 0.105 9.5% 0.087
0.062 46.6% 0.079 0.072 37.9% 150 0.123 0.112 8.9% 0.088 0.063
48.8% 0.077 0.071 42.3% 160
[0140] The friction reduction capability of TSEs and various other
additives at various temperatures is shown in TABLE 1. In preferred
embodiments, the fatty acid sorbitan esters (without additional
additives) reduce the coefficient of friction in the respective
lubricant composition by at least 30%, as measured at temperatures
less than or equal to 80.degree. C.; and by at least 15%, as
measured at temperatures less that or equal to 140.degree. C. These
results are surprising and unexpected because the fatty acid
sorbitan esters of the present invention have not previously been
utilized in friction reduction applications. Thus, there would be
no expectation that the inventive fatty acid sorbitan ester
composition would provide such superior results.
[0141] Also, as shown in TABLE 1, the friction reduction capability
of tartrates (alone), as well as the consistency of that
capability, is significantly improved with the addition of the
inventive TSEs. The friction reduction capabilities of the
tartrates is good at temperatures below 60.degree. C., but
decreases in the temperature range of 60.degree. C.-110.degree. C.,
e.g., the CoF of the lubricant composition increases over this
temperature range. The friction reduction capabilities then
increase again as temperatures exceed 110.degree. C. Surprisingly
and unexpectedly, the combination of the TSEs with these tartrates
provides friction reduction that is consistent across the
temperature range of 60.degree. C. to 160.degree. C. An increase in
CoF over the temperature is not seen when the inventive
compositions are utilized. This result could not have been expected
based on the friction reduction capabilities of the tartrates
and/or the TSEs.
[0142] Additionally, the TSEs and tartrates demonstrate a
synergistic effect when utilized in combination with one another,
i.e., the actual effect of the TSE/tartrate combination is greater
than the expected effect of the TSE and the tartrate at
temperatures greater than 60.degree. C., e.g., greater than
80.degree. C., greater than 90.degree. C., greater than 120.degree.
C. or greater than 140.degree. C. The combination of TSE and
tartrate reduces the coefficient of friction of the lubricant
composition to below 0.1, e.g., below 0.8, below 0.75, below 0.7 or
below 0.6, at temperatures greater than 60.degree. C., e.g.,
greater than 80.degree. C., greater than 90.degree. C., greater
than 120.degree. C. or greater than 140.degree. C. In terms of
percentages, the combination of TSE and tartrate reduces the
coefficient of friction of the lubricant composition by at least
50%, e.g., at least 40%, at least 30% or at least 25%, at
temperatures greater than 60.degree. C., e.g., greater than
80.degree. C., greater than 90.degree. C., greater than 120.degree.
C. or greater than 140.degree. C., when compared to a lubricant
composition that contains no additives. These reductions are
significantly lower than would be expected based on the individual
CoFs for TSEs and tartrates alone. Thus, the friction reducing
ability of the inventive combinations is surprising and
unexpected.
Example 3
Controlled Release of Inventive TSE Compositions
[0143] An exemplary system 100 for evaluating the release rate of a
friction modifier composition in to a base stock is shown in FIG.
2. TSE composition 102, which was prepared in accordance with the
present invention, was contained in Whatman-42 filter paper folded
envelope 104. Envelope 104 was placed in base stock 106, e.g.,
Group III base oil, heated to 95.degree. C. using heating element
108, while stirring with stir bar 110 to simulate lubricant flow
through a filter pouch. Base stock 106 was maintained at 95.degree.
C. and continuously stirred for 5 hours. The lubricant composition
was analyzed via Fourier Transform Infared Spectorscopy (FT-IR).
The weight of the friction modifier was measured, at time intervals
indicated below, by removing the envelope and patting the envelope
dry with Kim-wipe towels, then weighing the envelope. The results
of the testing are shown in TABLE 2.
TABLE-US-00002 TABLE 2 Slow FT-IR Release Spectra Peak Height TSE
Weight, grams Time, minutes VHVI-4 0.0012 19.9 0 FM1 0.00295 19.3
15 FM2 0.00364 18.8 30 FM3 0.00401 18.5 45 FM4 0.00432 18.4 60 FM5
0.00448 17.2 75 FM6 0.00585 15.7 105 FM7 0.00595 14.1 115 FM8
0.00643 13.4 145 FM9 0.00651 13.5 175 FM10 0.00701 13.5 205 FM11
0.00758 12.7 235 FM12 0.00789 12.6 265 FM13 0.00831 11.7 295
[0144] As shown in TABLE 2, the FT-IR peak heights, which are
indicative of the quantity of TSE in the lubricant composition,
gradually increase over time, e.g., the TSE is controllably
released into the lubricant composition. This conclusion is also
supported by the weight measurements of the envelope containing the
TSE. Over the 295 minute period, 8.2 grams of TSE was released from
the envelope and into the lubricant. It is noted that there is an
error range in the weight measurement of approximately 0.2 grams.
This explains the alleged increase in weight measurements at 145
and 175 minutes.
[0145] The controlled release, e.g., slow release, of the TSE into
the lubricant is demonstrated in FIG. 1, which shows the growth of
the 1742 cm.sup.-1 wavelength. The growth of this peak over time is
indicative of the increase in TSE in the lubricant over time. As
the size of the peak increases, the amount of TSE in the lubricant
increases.
[0146] Any feature described or claimed with respect to any
disclosed implementation may be combined in any combination with
any one or more other feature(s) described or claimed with respect
to any other disclosed implementation or implementations, to the
extent that the features are not necessarily technically
incompatible, and all such combinations are within the scope of the
present invention. Furthermore, the claims appended below set forth
some non-limiting combinations of features within the scope of the
invention, but also contemplated as being within the scope of the
invention are all possible combinations of the subject matter of
any two or more of the claims, in any possible combination,
provided that the combination is not necessarily technically
incompatible.
* * * * *