Note: Descriptions are shown in the official language in which they were submitted.
COMPOSITION AND METHOD OF MANUFACTURING
OVERBASED SULFONATE MODIFIED LITHIUM CARBOXYLATE GREASE
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001-0002] This invention relates to lithium carboxylate
greases made with the addition of a small amount of overbased
calcium sulfonate, overbased magnesium sulfonate, or both.
2. Description of Related Art
[0003] Lithium carboxylate greases have been the largest
category of lubricating greases worldwide for decades. Lithium
carboxylate greases (sometimes called lithium soap greases) can
either be simple lithium soap greases (most often lithium 12-
hydroxystearate greases) or they can be lithium complex greases.
Simple lithium soap greases are most often made by reacting 12-
hydroxystearic acid with at least a stoichiometric amount of a source of
lithium hydroxide (usually lithium hydroxide monohydrate, which is an
expensive ingredient) and some solvent water in an initial portion of the
base oil to be used in the final grease. Early lithium soap greases used
stearic acid instead of 12-hydroxystearic acid. The reaction mixture is
typically heated to about 400 F (where the thickener melts) and then
cooled to reform the simple lithium soap thickener. A slight
stoichiometric excess of lithium hydroxide is typically used so as to
insure that all acids are reacted. Additional base oil and additives as
required are added. The final grease is usually milled to optimally
disperse the thickener and provide a smooth and homogenous product.
Dropping points of such greases are typically 380 F to about 400 F or
slightly higher.
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[0004] Lithium complex greases were developed as an improvement
over simple lithium soap greases, where the primary property being improved
was dropping point. In these greases, a dicarboxylic acid, usually adipic,
sebacic, or (preferably) azelaic acid is also used. The dicarboxylic acid is
typically called the complexing acid. The lithium hydroxide monohydrate is
reacted with both 12-hydroxystearic acid (the primary thickener acid) and the
dicarboxylic acid in such a way as to get a thickener system where the
resulting lithium 12-hydroxystearate and di-lithium azelate (in the case of
azelaic acid being used, for example) are associated at the molecular level to
the extent that the high melting point properties of the di-lithium azelate
are
imparted to the overall complex thickener system. This results in a greatly
increased dropping point. Typical dropping points are at least 500 F. As with
simple lithium soap greases, a slight stoichiometric excess of lithium
hydroxide is typically used so as to insure that all acids are reacted.
[0005] U.S. Patent No. 2,898,296 discloses a lithium complex grease
with a reported dropping point above 500 F. In the '296 patent, lithium
hydroxide monohydrate was added to a blend of base oil, stearic acid, and a
diester of sebacic acid and heated to about 400 F. The resulting grease had
a dropping point that ranged from 479 F to >500 F, depending on the ratio of
the stearic acid to the sebacic diester. During the reaction of the lithium
hydroxide, the alcohol group associated with the sebacic acid diester was
released to the atmosphere. This may have not been an issue in 1959 when
the '296 patent issued, but venting of volatile alcohols would be an
environmental concern and prohibited in many areas of the world today. The
highest dropping point taught in the '296 patent occurred when the ratio of
the
stearic acid to the sebacic diester was 1Ø The '296 patent also taught that
if
the same grease was made using sebacic acid instead of the diester, a grainy
product was formed with a dropping point of only about 360 F. The grainy
texture was attributed to the di-lithium sebacate that had not been intimately
incorporated into the lithium 12-hydroxystearate thickener structure. Based
on the teachings of the '296 patent, it appears that the presence of the ester
moieties and/or the transient presence of the released alcohol acted as a
coupling agent to assist in the intimate association of the lithium 12-
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hydroxystearate and the di-lithium sebacate as they formed, thereby
increasing the dropping point.
[0006] U.S. Patent No. 2,940,930 also teaches a lithium complex
grease. In the '930 patent, a mixture of stearic and di-carboxylic acid
(adipic,
sebacic, or azelaic acid) was heated with a polyhydric alcohol (glycol) to
about
350 F to form a reacted product (likely a complex ester). That product was
cooled, added to base oil, and reacted with lithium hydroxide monohydrate by
heating to at least 300 F. The grease formed had a dropping point greater
than 500 F. The preferred wt/wt ratio of stearic acid to azelaic acid was 1.5.
Although not specifically mentioned in the '930 patent, the final reaction of
lithium hydroxide with the initial reaction product of the acids and the
glycol
(di-alcohol) would likely generate alcoholic material that would be
undesirably
released to the atmosphere or retained as an undesirable bi-product. The
method of the '930 patent also requires two heating and cooling cycles, which
adds to the time and expense of manufacturing the grease.
[0007] Another lithium complex grease is disclosed in U.S. Patent No.
3,681,242. In the '242 patent, an aqueous solution of lithium hydroxide was
added to 12-hydroxystearic acid in base oil and heated to about 400 ¨ 430 F
to form the lithium 12-hydroxystearate. The simple lithium soap grease was
cooled to about 220 F. Then the complexing acid, preferably azelaic acid,
was added. Additional aqueous lithium hydroxide was added to react with the
azelaic acid, and the mixture was once again heated to 350 ¨ 375 F. The
product was then cooled and finished as a lithium complex grease. The
dropping point was reported as high as 540 F, and the wt/wt ratio of 12-
hydroxystearic acid to azelaic acid ranged from 1.6 to 2.95. The method of
the '242 patent also requires two heating and cooling cycles, which adds to
the expense of manufacturing the grease.
[0008] In a similar patent, U.S. Patent No. 3,791,973, a process where
the 12-hydroxystearic acid in base oil is reacted with aqueous lithium
hydroxide and dehydrated by heating to 300 F is disclosed. The product was
then cooled to no lower than 205 F. Azelaic acid was then added and reacted
with additional aqueous lithium hydroxide. The mixture was then heated
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again to 390 F and cooled. The resulting lithium complex grease had a
dropping point of 625 F. The preferred wt/wt ratio of 12-hydroxystearic acid
to
azelaic acid ranged from 2.0 to 3.2. Again, this method required multiple
heating and cooling steps.
[0009] The use of two heating and cooling steps was avoided in the
method disclosed in U.S. Patent No. 4,435,299. The multiple heating and
cooling steps are avoided by a slow metered addition of aqueous lithium
hydroxide to a blend of 12-hydroxystearic and azelaic acids in base oil with
the temperature being held below the boiling point of water. Once the
reaction was complete, the product was heated to 390 ¨ 400 F and then
rapidly quenched to 375 F by addition of more base oil. The lithium complex
grease was then cooled and finished. The dropping point was greater than
500 F, and the preferred wt/wt ratio of 12-hydroxystearic acid to azelaic acid
was 2.6 or lower.
[0010] Specialized equipment has also been designed to more
efficiently make lithium complex greases. For example, U.S. Patent No.
4,297,227 discloses equipment and related methods whereby greases can be
continuously made. In U.S. Patent No. 4,444,669, the same inventors applied
this continuous grease making equipment and method to lithium complex
greases. Likewise, lithium complex greases can be more efficiently made
using closed pressurized kettles (sometimes referred to as autoclaves) and
contactors. Contactors are a special closed vessel with cyclic flow and
simultaneous high agitation that occurs throughout the entire reaction of
aqueous lithium hydroxide and the two thickener acids in base oil. This
process is continued through the entire heating (typically to about 400 ¨ 430
F) and cooling. Good thickener yield and high dropping points are obtained
with typically just one heating and cooling cycle. However, many grease
manufacturing facilities do not have access to pressurized kettles or
contactors.
[0011] There is a need in the art for a lithium complex grease
composition and method of manufacture that results in a grease with a
dropping point above 500 F, preferably above 540 F, and more preferably
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above 600 F that avoids using esters of 12-hydroxystearic acid or azelaic acid
or any other processes that, if present, would generate alcohols that would
either be released to the atmosphere, captured and disposed as hazardous
waste, or retained in the grease with associated deleterious properties. There
is also a need for such a high dropping point lithium complex grease that only
requires one heating and cooling cycle during the manufacturing method
and/or that can be made in an open vessel with typical heating and cooling
capacity and does not require a pressurized kettle or contactor. There is also
a need in the art to reduce the amount of azelaic acid and lithium hydroxide
used to make a lithium grease, as these are very expensive ingredients.
Azelaic acid costs 4 to 5 times as much as 12-hydroxstearic acid.
Additionally, it takes 4 times the amount of lithium hydroxide to neutralize
azelaic acid compared to 12-hydroxystearic acid. It has not previously been
known to make a lithium grease using a wt/wt ratio of 12-hydroxystearic acid
to azelaic acid of 3.2 or higher. It has also not been previously known to
simultaneously add the 12-hydroxystearic acid and azelaic acid or add the 12-
hydroxystearic acid followed by immediate sequential addition of azelaic acid
in the lithium grease manufacturing process. It has also not previously been
known to add magnesium sulfonate, calcium sulfonate, or both as an
ingredient in a lithium grease composition.
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SUMMARY OF THE INVENTION
[0012] This invention relates to lithium carboxylate greases modified
with overbased magnesium sulfonate, overbased calcium sulfonate, or both.
As used herein, a lithium carboxylate grease modified with magnesium
sulfonate, overbased calcium sulfonate, or both is sometimes referred to
simply as a lithium grease, which includes both simple lithium greases and
complex lithium greases unless one or the other is specified.
[0013] According to one preferred embodiment, a lithium grease
composition comprises a small amount of overbased magnesium sulfonate,
overbased calcium sulfonate, or both. According to
another preferred
embodiment, a lithium grease composition comprises 12-hydroxystearic acid
and azelaic acid in a wt/wt ratio of at least 3.2, more preferably at least 5,
and
most at least 5.8. According to another preferred embodiment, a lithium
grease composition comprises 1-5% lithium hydroxide monohydrate.
According to another preferred embodiment of the invention, the amount of
lithium hydroxide source may be lower than the stoichiometric amount needed
for reaction with the 12-hydroxystearic and azelaic acids. The grease
compositions according to preferred embodiments of the invention have
dropping points above 500 F, more preferably above 540 F, and most
preferably above 600 F. The grease compositions according to preferred
embodiments also do not require the use of esters that generate undesirable
volatile alcohol by-products or contaminants. Similarly,
these grease
compositions do not require multiple heating and cooling cycles (as defined
below) during manufacture, even when not using pressurized kettles or
contactors.
[0014] According to one preferred method of making a lithium grease,
a small amount of overbased magnesium sulfonate, overbased calcium
sulfonate, or both is added to the initial base oil before adding the acids or
the
source of lithium hydroxide (usually lithium hydroxide monohydrate).
According to another preferred embodiment, only one heating and cooling
cycle is used to make a lithium grease. As used herein a heating and cooling
cycle refers to heating and then cooling a mixture of various ingredients in
the
6
grease making process. For
example, heating to a first range of
temperatures, then heating to a second range of temperatures, then cooling to
a third range of temperatures without any cooling between the two heating
steps is considered one heating and cooling cycle. Heating to a first range of
temperatures, cooling to a second range of temperatures, then heating to a
third range of temperatures, and cooling to a fourth range of temperatures is
considered two heating and cooling cycles. According to yet another
preferred embodiment, a lithium grease is manufactured in an open vessel or
kettle, and a closed, pressurized kettle is not needed. According to yet
another preferred embodiment, the 12-hydroxystearic acid and azelaic acid
may be added simultaneously or the 12-hydroxystearic acid added followed
by the immediate sequential addition of the azelaic acid. According to yet
another preferred embodiment, it is not necessary to add the lithium hydroxide
by slow metered addition.
[0015] The preferred embodiments of the lithium grease compositions
and methods of the invention provide several benefits and advantages.
These include that significantly higher dropping points, preferably at least
540
F and more preferably at least 600 F or higher, may be achieved. The
amounts of azelaic acid and lithium hydroxide (both expensive ingredients)
used are reduced. The manufacturing process is simplified by allowing a
grease batch to be heated to top processing temperature (usually about 390
F- 430 F) only once and using only one heating and cooling cycle, even when
using open kettles instead of pressurized kettles of contactors. The process
is also simplified by the 12-hydroxystearic acid and azelaic acid to be
preferably added at the same time or near the same time and by not requiring
slow metered addition of the lithium hydroxide.
[0015a] Accordingly, in one aspect there is provided a method for
making a lithium carboxylate grease comprising the steps of adding and
mixing an overbased calcium sulfonate or an overbased magnesium sulfonate
or both with a base oil, lithium hydroxide, and water, wherein the
lithium
carboxylate grease is a simple grease or a complex grease.
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[0015b] In another aspect there is provided a lithium carboxylate
grease
composition comprising the following ingredients overbased magnesium
sulfonate, overbased calcium sulfonate, or a combination thereof; lithium
hydroxide; and a base oil, wherein the lithium carboxylate grease is a simple
grease or a complex grease.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] According to one preferred embodiment of the invention, a
simple or complex lithium grease composition is provided comprising (1)
overbased calcium sulfonate, overbased magnesium sulfonate, or both; (2)
base oil; (3) water; and (4) a source of lithium. The preferred source of
lithium
is lithium hydroxide, but other sources such as anhydrous lithium hydroxide,
if
available, may be used. Any material that will react during the grease
manufacturing process at the correct time to generate lithium hydroxide in-
situ
may also be used, provided that no undesirable byproducts are generated.
Most preferably, the lithium hydroxide is a solid, stable monohydrate. It is
noted that when the lithium hydroxide monohydrate is dissolved in water, the
water of hydration is simply incorporated into the water solvent as the
lithium
hydroxide dissociates into its substituent aqueous lithium cations and
hydroxide anions. After the lithium complex grease is finished, all water is
lost. Any excess lithium hydroxide should then be present as the anhydrous
form. When discussing the dissolving and reaction of lithium hydroxide
monohydrate with the thickener acids according to various preferred
embodiments herein, the terms "lithium hydroxide monohydrate" and "lithium
hydroxide" are used interchangeably.
[0017] The highly overbased oil-soluble calcium sulfonate (also
referred to herein as simply "calcium sulfonate" or "overbased calcium
sulfonate" for brevity) used according to these embodiments of the invention
can be any typical to that documented in the prior art, such as U.S. Pat Nos.
4,560,489; 5,126,062; 5,308,514; and 5,338,467. The highly overbased oil-
soluble calcium sulfonate may be produced in situ according to such known
methods or may be purchased as a commercially available product. Such
highly overbased oil-soluble calcium sulfonates will have a Total Base
Number (TBN) value not lower than 200, preferably not lower than 300, and
most preferably about 400 or higher. Commercially available overbased
calcium sulfonates of this type include, but are not limited to, the
following:
Hybase C401 as supplied by Chemtura USA Corporation; Syncal OB 400 and
Syncal 0B405-WO as supplied by Kimes Technologies International
Corporation; Lubrizol 75GR, Lubrizol 75NS, Lubrizol 75P, and Lubrizol 75W0
8
as supplied by Lubrizol Corporation. The overbased calcium sulfonate
contains around 28% to 40% dispersed amorphous calcium carbonate by
weight of the overbased calcium sulfonate, which is converted to crystalline
calcium carbonate during the process of making the calcium sulfonate grease.
The overbased calcium sulfonate also contains around 0% to 8% residual
calcium oxide or calcium hydroxide by weight of the overbased calcium
sulfonate. Most commercial overbased calcium sulfonates will also contain
around 40% base oil as a diluent, to keep the overbased calcium sulfonate
from being so thick that it is difficult to handle and process. The amount of
base oil in the overbased calcium sulfonate may make it unnecessary to add
additional base oil (as a separate ingredient) prior to conversion to achieve
an
acceptable grease.
[0018] The overbased calcium sulfonate used may be of a "good"
quality or a "poor" quality as defined herein and in U.S. Patent No.
9,458,406.
Certain overbased oil-soluble calcium sulfonates marketed and sold for the
manufacture of calcium sulfonate-based greases can provide products with
unacceptably low dropping points when prior art calcium sulfonate grease
technologies are used. Such overbased oil-soluble calcium sulfonates are
referred to as "poor quality" overbased oil-soluble calcium sulfonates
throughout this application. When all ingredients and methods are the same
except for the commercially available batch of overbased calcium sulfonate
used, overbased oil-soluble calcium sulfonates producing greases having
higher dropping points (above 575 F) are considered to be "good" quality
calcium sulfonates for purposes of this invention and those producing greases
having lower dropping points are considered to be "poor" quality for purposes
of this invention. Several examples of this are provided in the '406 patent.
Although comparative chemical analyses of good quality and poor quality
overbased oil-soluble calcium sulfonates has been performed, it is believed
that the precise reason for this low dropping point problem has not been
proven. While many commercially available overbased calcium sulfonates
are considered to be good quality, it is desirable to achieve acceptable
greases regardless of whether a good quality or a poor quality calcium
sulfonate is used. It has been found that both improved thickener yield and
higher dropping point may be achieved with
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either a good quality or a poor quality calcium sulfonate in the lithium
grease
composition and methods according to the invention.
[0019] The overbased magnesium sulfonate (also referred to herein as
simply "magnesium sulfonate," for brevity) used according to these
embodiments of the invention can be any typical to that documented or known
in the prior art. The overbased magnesium sulfonate may be made in-situ or
any commercially available overbased magnesium sulfonate may be used.
Overbased magnesium sulfonate will typically comprise a neutral magnesium
alkylbenzene sulfonate and an amount of overbasing wherein a substantial
amount of that overbasing is in the form of magnesium carbonate. The
magnesium carbonate is believed to typically be in an amorphous (non-
crystalline) form. There may also be a portion of the overbasing that is in
the
form of magnesium oxide, magnesium hydroxide, or a mixture of the oxide
and hydroxide. The total base number (TBN) of the overbased magnesium
sulfonates is preferably at least 400 mg KOH/ gram, but lower TBN values
may also be acceptable and in the same ranges as indicated for the TBN
values for the overbased calcium sulfonate above.
[0020] Calcium sulfonate and magnesium sulfonate may be used
separately or together in any proportion relative to each other according to
various preferred embodiments. These sulfonates ("overbased sulfonate" or
simply "sulfonate" are used herein to refer to either calcium sulfonate or
magnesium sulfonate) do not appear to convert to any functionally significant
extent during their use in various preferred embodiments of the invention.
The conversion process, as described in U.S. Patent Nos. U.S. Patent
9,273,265 and 9,458,406, does not appear to be a part of the unexpectedly
beneficial function of the overbased sulfonates in the various preferred
embodiments of the invention. The overbased magnesium sulfonates appear
to only slightly convert when used to make lithium greases. However, this
property of overbased sulfonates is not a limitation in making lithium greases
according to the compositions and methods of the preferred embodiments of
the invention. Without being bound by theory, it appears that the overbased
sulfonate is dispersing the initially formed aqueous lithium hydroxide
solution
to facilitate its reaction with the thickener acids, thereby further
preventing the
reaction of the thickener acids with the overbased sulfonate. The overbased
CA 2967558 2017-05-17
sulfonate apparently also promotes the intimate association of the lithium 12-
hydroxystearate and di-lithium azelate as they are formed, thereby eliminating
the need for esters, alcohols, or multiple heating and cooling cycles as a
means of imparting a high dropping point.
[0021] Any petroleum-based naphthenic or paraffinic mineral oils
commonly used and well known in the grease making art may be used as the
base oil according to the invention. Base oil is added as needed, since most
commercial overbased calcium sulfonates will already contain about 40%
base oil as a diluent so as to prevent the overbased sulfonate from being so
thick that it cannot be easily handled. Similarly, overbased magnesium
sulfonate will likely contain base oil as a diluent. With the amount of base
oil
in the overbased calcium sulfonate and overbased magnesium sulfoante, it
may be unnecessary to add additional base oil depending on the desired
consistency of the grease. Synthetic base oils may also be used in the
greases of the present invention. Such
synthetic base oils include
polyalphaolefins (PAO), diesters, polyol esters, polyethers, alkylated
benzenes, alkylated naphthalenes, and silicone fluids. In some cases,
synthetic base oils may have an adverse effect if present during the
conversion process as will be understood by those of ordinary skill in the
art.
In such cases, those synthetic base oils should not be initially added, but
added to the grease making process at a stage when the adverse effects will
be eliminated or minimized, such as after conversion. Naphthenic and
paraffinic mineral base oils are preferred due to their lower cost and
availability. Combinations of different base oils as described above may also
be used in the invention, as will be understood by those with ordinary skill
in
the art.
[0022] According to another preferred embodiment, a complex lithium
grease composition comprises ingredients (1)-(4) above and further
comprises a thickener acid and a complexing acid. Most preferably, the
primary thickener acid is 12-hydroxystearic acid, but any alkyl 016 to 022
monocarboxylic acid or a mixture of such may be used. The primary
thickener acid (or acids) may have a hydroxy group covalently attached to one
of the non-carboxylic carbons or it may have no hydroxy group. Most
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preferably, the complexing acid is azelaic acid, but any alkyl 06 to C12
dicarboxylic acid or a mixture of such may be used.
[0023] According to another preferred embodiment of the invention,
less azelaic acid (or other dicarboxylic acid) is used relative to the amount
of
12-hydroxystearic acid (or other monocarboxylic acid). Without being bound
by theory, it is believed that adding a small amount of overbased sulfonate
allows the use of less azelaic acid relative to the 12-hydroxystearic acid.
This
is important since it is the 12-hydroxystearic acid that imparts good
thickener
yield. Azelaic acid is not good for thickener yield, but does raise the
dropping
point. Prior art lithium complex greases must compromise in how the relative
amounts of 12-hydroxystearic acid and azelaic acid are added. More 12-
hydroxystearic acid and less azelaic acid give better thickener yield but
lower
dropping point. Less 12-hydroxystearic acid and more azelaic acid give
higher dropping point but poorer thickener yield. Adding an overbased
sulfonate according to preferred embodiments of the invention allows the best
of both worlds by allowing less azelaic acid relative to the 12-hydroxystearic
acid while still providing good thickener yields and dropping points. In fact,
the dropping points are not only good but even higher than many prior art
lithium complex greases. Additionally, azelaic acid is about five times as
costly as 12-hydroxystearic acid, so lowering the relative amount of azelaic
acid to 12-hydroxystearic acid according to various preferred embodiments of
the invention reduces the cost of the final grease.
[0024] According to another preferred embodiment of the invention,
the amount of lithium hydroxide source may be lower than the stoichiometric
amount needed for reaction with the 12-hydroxystearic and azelaic acids (or
other monocarboxylic and dicarboxylic acids). The additional base needed for
reaction with the acids may be from the overbased sulfonate or may be from a
small amount of optionally added calcium containing base, such as added
calcium hydroxide, added calcium oxide, added calcium carbonate, calcium
hydroxyapatite, or a mixture of two or more of these materials. This is
important since lithium hydroxide is an expensive ingredient, so it is
beneficial
to reduce the amount of lithium hydroxide used. The amount of lithium
hydroxide according to a preferred embodiment of the invention is reduced
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relative to prior art lithium carboxylate greases while still maintaining good
thickener yield and improved dropping point. If one or
more calcium
containing bases are added, they are preferably finely divided with a mean
particle size of around 1 to 20 microns, preferably around 1 to 10 microns,
most preferably around 1 to 5 microns. Furthermore, any calcium containing
base is preferably of sufficient purity so as to have abrasive contaminants
such as silica and alumina at a level low enough to not significantly impact
the
anti-wear properties of the resulting grease. Ideally, for best results, any
calcium containing base should be either food grade or U.S. Pharmacopeia
grade.
[0025] According to several preferred embodiments, a lithium grease
composition comprises the following ingredients by weight percent of the final
grease product (although some ingredients, such as water, sulfonates, and
acids, may not be in the final grease product or may not be in the
concentrations indicated for addition):
[0026] TABLE 1 ¨ Preferred Compositions
Ingredient Preferred More Preferred Most
Amount (%) Amount (%) Preferred
Amount (%)
Overbased 0.01 - 10 0.1 -5 0.2 -2
Calcium
Sulfonate
Overbased 0.01 - 10 0.1 -5 0.2 - 2
Magnesium
Sulfonate
Lithium 1 -5 1.2 -3.6 2 - 3
Hydroxide
Monohyd rate
12- 4.3 - 21.2 5.2- 15.3 8.6 - 12.8
Hyd roxystearic
Acid (or other
monocarboxylic
acid)
Azelaic Acid (or 0.8 - 3.6 0.9 - 2.6 1.6 - 2.2
other
dicarboxylic
acid)
Base Oil (total) 50.2 - 93.9 68.5 - 92.5 78 -
87.4
Water (added) 0.1 - 10 0.5 - 5 1 - 3
Ratio of 12- 1 - <10 2 - 8 3.2 - 6
HSA(or other
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monocarboxylic
acid)/Azelaic
Acid (or other
dicarboxylic
acid (wt/wt)
Ratio of 12- >1 - 1000 2 - 100 3.3 - 50
HSA (or other
monocarboxylic
acid)/Overbase
d sulfonate
(wt/wt)
Excess Lithium 0.01 - 0.22 0.03 - 0.18 0.07 - 0.15
Hydroxide,
Anhydrous
[0027] All percentages are based on the total unreacted weight of all
ingredients (raw materials) in the grease, not including water. Water will not
be present in the final grease since both the added water and the water of
reaction will be evaporated during the manufacturing process. Even so, the
percentages of added water are based on the total unreacted weight of the
grease, not including the added water. Other ingredients, such as sulfonates
and acids, may not be in the final finished grease product or may not be in
the
final grease product in the amounts indicated for addition as an ingredient,
due to evaporation, volatilization, or reaction with other ingredients during
manufacture. These amounts are when a grease is made in an open vessel.
Even smaller amounts of may be used when a lithium grease is made in a
pressure vessel. Although it is preferred to make lithium greases in an open
vessel, a pressurized kettle or contactor may be used according to the
invention. The widest ranges of the thickener components in the above table
take into account the applicability of the subject invention as it would
include
final greases with NLGI consistency grades spanning 000 to 3.
[0028] According to one preferred method for making a lithium grease,
the method comprises the following steps: (1) adding an initial portion of the
base oil and the overbased sulfonate (magnesium, calcium, or both) and
begin mixing; (2) adding the lithium hydroxide monohydrate and water; (3)
heating the mixture to about 160 F ¨ 200 F, most preferably around 180 F; (4)
adding the monocarboxylic and dicarboxylic acids, preferably 12-
hydroxystearic and azelaic acids; (5) heating the mixture to about 190 ¨ 200 F
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and holding the mixture in that temperature range until the reaction is
complete; and (6) heating the mixture to 390 ¨ 430 F and then cooling the
mixture.
[0029] According to this preferred embodiment, it is not necessary to
heat, cool, re-heat, and re-cool the mixture ¨ it may be heated in multiple
stages without intermediate cooling and cooled only once at the end of the
process for a total of one heating and cooling cycle. The order of addition of
the lithium hydroxide and water in step (2) is not important, and a pre-
dissolved aqueous solution of lithium hydroxide may be used if desired. The
order of addition of the acids in step (4) is not critical, although adding
the
monocarboxylic acid (12-hydroxystearic acid) first is preferred. The order of
steps (1)-(5) relative to each other is not critical, but it is preferred that
they be
carried out in the order indicated numerically. It is noted that prior art
lithium
grease processes teach the addition of the thickener acids before the lithium
hydroxide, whereas it is preferred to add them after the lithium hydroxide in
various embodiments of the invention. For fully additized lithium complex
greases, the final processing steps after heating to the maximum processing
temperature are the same as with any prior art grease. They include cooling
the grease to a temperature that is appropriate for the addition of any
additives are used, and milling to optimize the thickener dispersion, texture
smoothness, and any other properties associated with optimized thickener
dispersion. Most preferably, the preferred compositions according to the
invention are made using the preferred methods according to the invention.
[0030] According to another preferred embodiment, the acids in step
(4) are added at substantially the same time (substantially simultaneously,
recognizing that adding each ingredient takes at least some time and cannot
occur instantaneously and that it may take longer to add the larger amount of
monocarboxylic acid than the smaller amount of dicarboxylic acid according to
one preferred embodiment). According to another preferred embodiment, the
acids in step (4) are added sequentially without any heating or cooling
between their additions and/or without any other ingredient being added
between their additions. According to another preferred embodiment, the
CA 2967558 2017-05-17
lithium hydroxide is added in a batch manner all at once (en masse, as
opposed to a slow metered addition over time).
[0031] According to another preferred embodiment, the method
comprises the steps above except that the sulfonate(s) are added after the
thickener reaction and after heating to the maximum processing temperature.
According to other preferred embodiments, a portion of one or both sulfonates
may be added early in the process and another portion of the same or both
sulfonates may be added later in the process. For example, a portion of
magnesium sulfonate may be added prior to addition of the lithium hydroxide
and another portion of magnesium sulfonate may be added after reaching
maximum processing temperature and cooling. According to another
preferred embodiment, all of the calcium sulfonate or magnesium sulfonate
may be added prior to the addition of lithium hydroxide and all of the other
sulfonate may be added after reaching maximum processing temperature and
cooling. Various combinations of partial or total addition of one or both
sulfonates at the beginning and end of the process may be used.
[0032] The overbased calcium magnesium sulfonate grease
compositions and methods for making such compositions according to various
embodiments the invention are further described and explained in relation to
the following examples. The greases in Examples 1-4 are baseline example
greases according to the prior art, for comparison with various preferred
embodiments of the invention. Examples 1 and 2 use ratios within the ranges
taught by the prior art and the overall grease making process is according to
the prior art. Example 3 and 4 use increased ratios of 12-hydroxystearic acid
to azelaic acid higher than taught in the prior art, but otherwise use the
overall
grease making process according to the prior art (with multiple heating and
cooling cycles).
[0033] Example 1 - A lithium complex base grease (grease with no
additives except a minor amount of antioxidant) was prepared within the
scope of previously described prior art methods involving the separate and
sequential reaction of the two acids with lithium hydroxide monohyd rate with
two distinct heating and cooling steps. The wt/wt ratio of 12-hydroxystearic
16
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acid to azelaic acid was 2.89. The amount of stoichiometric excess lithium
hydroxide in the final grease was 0.06 /0(wt).
[0034] This grease was made as follows: 740.35 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.48 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
The mixture was heated using a rheostat controlled electric heating mantle
until the temperature was 180 F. Then 155.25 grams of 12-hydroxystearic
acid were added and allowed to melt and mix into the mixture. At this point,
47.25 grams of lithium hydroxide monohydrate were added, and the mixture
was heated to the range of 190 ¨ 200 F. Then 12.67 grams water were
added. The mixture was allowed to react for 30 minutes during which time it
foamed. Although reaction of the acids with the base was clearly occurring,
no visible grease structure had formed. After the 30 minutes, the mixture was
heated to the range of 280 ¨ 290 F and then cooled back down to 190 ¨ 200
F. Cooling was accomplished by removing the heating mantle and stirring in
open air. Then 53.70 grams of azelaic acid and 12.85 grams water were
added. The batch was stirred for 30 minutes after which it was heated to 400
¨ 410 F. This heating step took over one hour to complete. When the target
top temperature range was reached and held for 5 minutes, the heating
mantle was removed and the batch was mixed in the open air and allowed to
cool to 170 F. During this cooling period, as the grease structure formed and
became increasingly heavy, six portions of the same paraffinic base oil
totaling 660.72 grams were added and allowed to fully mix in. The entire
batch was given three passes through a three roll mill with both gaps set at
0.001 inches. The final milled grease had a worked 60 stroke penetration of
280. The dropping point was 503 F.
[0035] Example 2 - Another lithium complex base grease was made
essentially the same as the previous Example 1 grease. The only difference
was that when the grease had been heated to its top temperature range of
390 ¨ 400 F, it was cooled to 250 F and then heated again to 390 ¨ 400 F.
Then the grease was cooled to 170 F. The wt/wt ratio of 12-hydroxystearic
17
CA 2967558 2017-05-17
acid to azelaic acid was 2.89. The amount of stoichiometric excess lithium
hydroxide in the final grease was 0.05%(wt).
[0036] The grease was made as follows: 745.24 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.45 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
The mixture was heated using a rheostat controlled electric heating mantle
until the temperature was 180 F. Then 155.25 grams of 12-hydroxystearic
acid were added and allowed to melt and mix into the mixture. At this point,
47.25 grams of lithium hydroxide monohydrate were added, and the mixture
was heated to the range of 190 ¨ 200 F. Then 12.5 grams water were added.
The mixture was allowed to react for 30 minutes during which time it foamed.
Although reaction of the acids with the base was clearly occurring, no visible
grease structure had formed. After the 30 minutes, the mixture was heated to
the range of 280 ¨ 290 F and then cooled back down to 190 ¨ 200 F. Cooling
was accomplished by removing the heating mantle and stirring in open air.
Then 53.70 grams of azelaic acid and 12.5 grams water were added. The
batch was stirred for 30 minutes after which it was heated to 400 ¨ 410 F.
This heating step took over one hour to complete. When the target top
temperature range was reached and held for 5 minutes, the heating mantle
was removed and the batch was mixed in the open air and allowed to cool to
250 F. During this cooling period, as the grease structure formed and
became increasingly heavy, two portions of the same paraffinic base oil
totaling 231.94 grams were added and allowed to fully mix in. When the
batch reached 250 F, it was once again heated to 400 ¨ 410 F and held there
for 5 minutes. Then it was allowed to cool in the same manner as before. As
it was cooled to 170 F, the batch continued to get thicker. Six more portions
of the same paraffinic base oil totaling 623.62 grams were added and allowed
to mix in. The entire batch was given three passes through a three roll mill
with both gaps set at 0.001 inches. The final milled grease had a worked 60
stroke penetration of 284. The dropping point was 581 F. As can be seen,
the effect of adding a third heating and cooling cycle was to further increase
the dropping point as compared to Example 1. This is in accord with the prior
18
CA 2967558 2017-05-17
art teaching that additional heating to about 400 F allows the two thickener
components (lithium 12-hydroxystearate and di-lithium azelate) to increasingly
associate at the molecular level, thereby increasingly imparting the high
melting point attributes of the di-lithium azelate.
[0037] Example 3 - Another lithium complex base grease was made
essentially the same as the previous Example 2 grease. Like the previous
Example 2 grease, this grease had three heating and cooling steps. The only
significant difference was that the amount of azelaic acid relative to the
amount of 12-hydroxystearic acid was reduced. The wt/wt ratio of 12-
hydroxystearic acid to azelaic acid was increased from 2.89 to 3.71. The
amount of stoichiometric excess lithium hydroxide in the final grease was
0.11%(wt).
[0038] The grease was made as follows: 751.51 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.47 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
The mixture was heated using a rheostat controlled electric heating mantle
until the temperature was 180 F. Then 155.26 grams of 12-hydroxystearic
acid were added and allowed to melt and mix into the mixture. At this point,
43.37 grams of lithium hydroxide monohydrate were added, and the mixture
was heated to the range of 190 ¨ 200 F. Then 12.8 grams water were added.
The mixture was allowed to react for 30 minutes during which time it foamed.
Although reaction of the acids with the base was clearly occurring, no visible
grease structure had formed. After the 30 minutes, the mixture was heated to
the range of 280 ¨ 290 F and then cooled back down to 190 ¨ 200 F. Cooling
was accomplished by removing the heating mantle and stirring in open air.
Then 41.85 grams of azelaic acid and 12.5 grams water were added. The
batch was stirred for 30 minutes after which it was heated to 400 ¨ 410 F.
This heating step took over one hour to complete. When the target top
temperature range was reached and held for 5 minutes, the heating mantle
was removed and the batch was mixed in the open air and allowed to cool to
230 F. During this cooling period, as the grease structure formed and
19
CA 2967558 2017-05-17
became increasingly heavy, 131.23 grams of the same paraffinic base oil
were added and allowed to fully mix in. When the batch reached 230 F, it was
once again heated to 400 ¨ 410 F and held there for 5 minutes. Then it was
allowed to cool in the same manner as before. As it was cooled to 170 F, the
batch continued to get thicker. Five more portions of the same paraffinic base
oil totaling 531.69 grams were added and allowed to mix in. The entire batch
was given three passes through a three roll mill with both gaps set at 0.001
inches. The final milled grease had a worked 60 stroke penetration of 301.
The dropping point was 580 F.
[0039] Example 4 - Another lithium complex base grease was made
essentially the same as the previous Example 3 grease. The only significant
difference was that after the 12-hydroxystearic acid had reacted and the first
heating (to 280 ¨ 290 F) and cooling cycle had been completed, the batch
was only heated once to 390 ¨ 400 F. However, this heating and cooling
cycle was intentionally done at a slower rate so that it took 3 hours to heat
to
top temperature and 2 hours to cool from the top temperature to 170 F. The
wt/wt ratio of 12-hydroxystearic acid to azelaic acid was 3.71. The amount of
stoichiometric excess lithium hydroxide in the final grease was 0.12 /0(wt).
[0040] The grease was made as follows: 761.09 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.57 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
The mixture was heated using a rheostat controlled electric heating mantle
until the temperature was 180 F. Then 155.25 grams of 12-hydroxystearic
acid were added and allowed to melt and mix into the mixture. At this point,
43.37 grams of lithium hydroxide monohydrate were added, and the mixture
was heated to the range of 190 ¨ 200 F. Then 12.8 grams water were added.
The mixture was allowed to react for 30 minutes during which time it foamed.
Although reaction of the acids with the base was clearly occurring, no visible
grease structure had formed. After the 30 minutes, the mixture was heated to
the range of 280 ¨ 290 F. This took about 45 minutes. Then the batch was
cooled back down to 190 ¨ 200 F. Cooling was accomplished by removing
CA 2967558 2017-05-17
the heating mantle and stirring in open air. Then 41.86 grams of azelaic acid
and 12.9 grams water were added. The batch was stirred for 30 minutes after
which it was heated to 400 ¨ 410 F. This heating step took about 3 hours to
complete. When the target top temperature was reached and held for 15
minutes, the rheostat was turned down so as to slowly cool the batch. After
about 2 hours the batch had reached 170 F. During that time two more
portions of the same paraffinic base oil totaling 196.97 grams were added to
the batch. Due to the lateness of the day, the heating mantle was removed
and mixing was stopped. The next morning, the batch was mixed and heated
back to 170 F (this is not considered an additional heating/cooling cycle).
Due
to the heaviness of the grease, two more portions of the same paraffinic base
oil totaling 235.24 grams were added. The entire batch was given three
passes through a three roll mill with both gaps set at 0.001 inches. The final
milled grease had a worked 60 stroke penetration of 300. The dropping point
was 567 F.
[0041] Compositions of Examples 1 ¨ 4 based on the sum of the
unreacted components (not including added water) as well as test data are
provided in Table 2.
[0042] Table 2 ¨ Summary of Examples 1-4
Example 1 2 3 4
600 SUS
Paraffinic Base 84.16 85.86 85.08 82.79
Oil %
12-
hydroxystearic 9.33 8.33 9.34 10.77
acid %
Lithium
Hydroxide 2.84 2.53 2.61 3.01
Monohydrate %
Azelaic acid 0/0 3.23 2.88 2.52 2.90
Aryl Amine
Antioxidant % 0.45 0.40 0.45 0.53
Ratio of xystearic12-
2.89 2.89 3.71 3.71
hydro
21
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Example 1 2 3 4
acid-azelaic acid
(wt/wt)
---
Temperature
when 12-
hydroxystearic 180 180 180 180
acid was added,
Temperature
when LiOH was 180 180 180 180
added, F
Order of
Addition of LiOH 12- 12- 12- 12-
and 12- hydroxystearic hydroxystearic hydroxystearic hydroxystearic
hydroxystearic acid first acid first acid first acid first
acid
Order of
Addition of water LiOH first LiOH first LiOH first LiOH
first
and LiOH
12-
hydroxystearic
acid and azelaic
No No No No
acid Added at
about the Same
Time?
Heat to 280-290
F and cool
Yes Yes Yes Yes
before adding
azelaic acid?
How many
heatings to 400- 1 2 2 1
410 F?
How many
heating/cooling 2 3 3 2
cycles total?
Speed of
Heating to
Maximum Moderate Moderate Moderate Slow (3hrs)
Process
Temperature
Cooled from
Maximum In air In air In air Slow (2hrs)
Process
Temperature
22
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Example 1 2 3 4
How?
% excess LiOH
0.06 0.05 0.11 0.12
in final grease
Unworked 277 280 297 299
Penetration
Worked 60
strokes 280 284 301 300
Penetration
Dropping Point, 503 581 580 567
Dropping Point,
262 305 304 297
Roll Stability at
25C, 2 hrs:
Initial
worked
289 289 295 305
Penetration
Final
Worked 309 317 315 307
Penetration
% Change 6.9 9.7 6.8 0.7
Roll Stability at
150 C, 2 hrs:
Initial
worked 289 289 295 305
Penetration
Final
Worked 315 313 311 287
Penetration
% Change 9.0 8.3 5.4 -5.9
[0043] The data in Table 2 verifies that when more than one heating
cycle to 400 F is used, dropping points of these prior art lithium complex
base
greases are good, just as the prior art states. In Examples 2 and 3, where
there are three total heating and cooling cycles (including two cycles to 400
23
CA 2967558 2017-05-17
F), dropping point was about 480 F. In Examples 1 and 4, where two heating
cycles (including one cycle to 400 F) were used, dropping point was still much
higher in Grease 4 where the total heating time was much longer. Thus, it
appears that both the number of times the grease is heated to 400 F and the
total temperature-time heating effect is important for improving dropping
point.
The longer heating and cooling times of Example 4 may be closer to what
would be experienced in typical open kettle grease manufacturing equipment.
These four greases, and especially Example 4, serve as a baseline for
comparison with regard to the next example greases according to various
preferred embodiments of the invention.
[0044] Example 5 - A lithium complex base grease was made using
the overall process of the previous Example 4, but with the addition of
magnesium sulfonate and other method changes as noted below and in Table
3. The wt/wt ratio of 12-hydroxystearic acid to azelaic acid was 3.71. The
amount of stoichiometric excess lithium hydroxide in the final grease was
0.11%(wt).
[0045] The grease was made as follows: 745.84 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.47 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
Then 8.41 grams of a 400 TBN overbased magnesium sulfonate were added.
This is the same overbased magnesium sulfonate "A" as described in U.S.
Serial No. 15/593,792. The mixture was stirred for 15 minutes. Then 43.36
grams of lithium hydroxide monohydrate and 25.0 grams water were added,
and the mixture was heated to 180 F. Then 155.25 grams of 12-
hydroxystearic acid were added and allowed to melt and mix into the mixture.
Almost immediately a thick grease structure formed. Then 41.86 grams of
azelaic acid were added. The grease structure visibly softened in consistency
once the azelaic acid had melted and mixed into the batch. The temperature
of the batch was adjusted to 190 ¨ 200 F and held there for 45 minutes. Then
the batch was heated to 400 ¨ 410 F. This heating step took about 3 hours to
complete. When the target top temperature was reached and held for 15
24
CA 2967558 2017-05-17
minutes, the rheostat was turned down so as to slowly cool the batch over a 2
hour period. During that time two more portions of the same paraffinic base
oil totaling 251.43 grams were added to the batch. Due to the lateness of the
day, the heating mantle was removed and mixing was stopped. The next
morning, the batch was mixed and heated back to 170 F. Due to the
heaviness of the grease, three more portions of the same paraffinic base oil
totaling 283.00 grams were added. The entire batch was given three passes
through a three roll mill with both gaps set at 0.001 inches. The final milled
grease had a worked 60 stroke penetration of 283. The dropping point was
625 F. The wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate was
about 20. This ratio is usually determined by the amount of 12-hydroxystearic
acid and overbased sulfonate added at the beginning as the lithium complex
thickener system is being formed. The only exception to this is when the only
overbased sulfonate added as part of this invention is added later after the
initial thickener formation reaction has occurred, such as when the only
overbased sulfonate is added after top temperature has been reached and
after cooling has begun.
[0046] Example 6 - Another lithium complex base grease was made
essentially the same as the previous Example 5 grease. The only significant
difference was that the amount of overbased magnesium sulfonate A was
about half of what was used in Example 5. The wt/wt ratio of 12-
hydroxystearic acid to azelaic acid was 3.72. The amount of stoichiometric
excess lithium hydroxide in the final grease was 0.11%(wt). The final milled
grease had a worked 60 stroke penetration of 287. The dropping point was
602 F. The wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate was
about 40.
[0047] Example 7 - Another lithium complex base grease was made
essentially the same as the previous Example 5 grease. The only significant
difference was that the amount of overbased magnesium sulfonate A was
about twice what was used in Example 5. The wt/wt ratio of 12-
hydroxystearic acid to azelaic acid was 3.71. The amount of stoichiometric
excess lithium hydroxide in the final grease was 0.12%(wt). The final milled
CA 2967558 2017-05-17
grease had a worked 60 stroke penetration of 303. The dropping point was
613 F. The wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate was
about 10.
[0048] Example 8 - Another lithium complex base grease was made
essentially the same as the previous Example 5 grease. The only difference
was that after the three hour heating to a top temperature of 400 ¨ 410 F, the
mixing bowl was removed and immersed almost to the rim in a large container
of crushed ice with manual stirring of the batch. This caused a rapid cooling
such that the temperature of the batch was reduced to 240 F in 10 minutes.
At this point, the mixing bowl was again positioned within the mixer, and the
batch was mixed and finished. The wt/wt ratio of 12-hydroxystearic acid to
azelaic acid was 3.71. The amount of stoichiometric excess lithium hydroxide
in the final grease was 0.11%(wt). The final milled grease had a worked 60
stroke penetration of 299. The dropping point was 580 F. The wt/wt ratio of
12-hydroxystearic acid/overbased sulfonate was about 20.
[0049] Example 9 - Another lithium complex base grease was made
essentially the same as the previous Example 5 grease. The only difference
was that the overbased magnesium sulfonate A was not added at the
beginning, but after the batch had reached top temperature and was cooled to
255 F. The wt/wt ratio of 12-hydroxystearic acid to azelaic acid was 3.71.
The amount of stoichiometric excess lithium hydroxide in the final grease was
0.12')/0(wt). The wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate
was
about 20.
[0050] The grease was made as follows: 748.18 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.54 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
The mixture was stirred for 15 minutes. Then 43.36 grams of lithium
hydroxide monohydrate and 25.0 grams water were added, and the mixture
was heated to 180 F. Then 155.25 grams of 12-hydroxystearic acid were
added and allowed to melt and mix into the mixture. Then 41.85 grams of
azelaic acid were added. The temperature of the batch was adjusted to 190 ¨
26
CA 2967558 2017-05-17
200 F and held there for 45 minutes. The batch remained a liquid in
consistency. Then the batch was heated to 400 ¨ 410 F. This heating step
took about 3 hours to complete. When the target top temperature was
reached and held for 15 minutes, the rheostat was turned down so as to
slowly cool the batch over a 2 hour period. When the batch reached a
temperature of 255 F, 7.70 grams of a 400 TBN overbased magnesium
sulfonate A were added. The batch thickened significantly by this time, so
three more portions of the same paraffinic base oil totaling 381.43 grams were
added to the batch. Due to the lateness of the day, the heating mantle was
removed and mixing was stopped. The next morning, the batch was mixed
and heated back to 170 F. Due to the heaviness of the grease, two more
portions of the same paraffinic base oil totaling 122.69 grams were added.
The entire batch was given three passes through a three roll mill with both
gaps set at 0.001 inches. The final milled grease had a worked 60 stroke
penetration of 283. The dropping point was 580 F.
[0051] Example 10 - Another lithium complex base grease was made
essentially the same as the previous Example 5 grease. The only significant
difference was that the heating and cooling rates after initial thickener
reaction
was the same as what was done in the Example 1 ¨ 3 greases. The wt/wt
ratio of 12-hydroxystearic acid to azelaic acid was 3.70. The amount of
stoichiometric excess lithium hydroxide in the final grease was 0.10%(wt).
The wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate was about 20.
The final milled grease had a worked 60 stroke penetration of 290. The
dropping point was 623 F.
[0052] Example 11 - Another lithium complex base grease was made
essentially the same as the previous Example 5 grease. The only significant
difference was that the amount of azelaic acid was reduced to an amount that
resulted in a wt/wt ratio of 12-hydroxystearic acid to azelaic acid of 5.78.
The
amount of lithium hydroxide was also proportionally lowered so that the
stoichiometric excess lithium hydroxide in the final grease remained
0.11%(wt). The final milled grease had a worked 60 stroke penetration of
27
CA 2967558 2017-05-17
293. The wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate was about
20. The dropping point was 610 F.
[0053] Compositions of Examples 5 - 11 based on the sum of the
unreacted components (not including added water) as well as test data are
provided in Table 3. Example 4 is also included for ease of comparison.
[0054] Table 3 - Summary of Examples 4-11
Example 4 5 6 7 8 9 10 11
600 SUS Paraffinic
Base Oil % 82.79 83.32 83.61 81.60 83.41 84.76 84.76 83.71
Overbased
magnesium sulfonate
0.00 0.55 0.24 1.05 0.49 0.50 0.50 0.55
A
12-hydroxystearic
acid % 10.77 10.10 10.11 10.86 10.08 9.22 9.22
10.80
Lithium Hydroxide
Monohydrate % 3.01 2.82 2.82 3.03 2.81 2.58 2.58 2.53
Azelaic acid A
2.90 2.72 2.72 2.93 2.72 2.49 2.49 1.87
Aryl Amine
Antioxidant A 0.53 0.49 0.49 0.53 0.49 0.45 0.45 0.54
Ratio of 12-
hydroxystearic acid-
3.71 3.71 3.72 3.71 3.71 3.71 3.70 5.78
azelaic acid (wt/wt)
Ratio of 12-
hydroxystearic acid to
NA
Magnesium sulfonate 18.4 42.1 10.3 20.6 18.5 18.4 19.6
(wt/wt)
Temperature when
12-hydroxystearic 180 180 180 180 180 180 180 180
acid was added, F
Temperature when
180 75 75 75 75 75 75 75
LiOH was added, F
12-
Order of Addition of hydroxy
LiOH LiOH LiOH LiOH LiOH LiOH LiOH
LiOH and 12- stearic
first first first first first first
first
hydroxystearic acid acid
first
Order of Addition of LiOH H20 H20 H20 H2O H20 H20 H20
water and LiOH first first first first first first first
first
28
CA 2967558 2017-05-17
Example 4 5 6 7 8 9 10 11
12-hydroxystearic
acid and azelaic acid
No Yes Yes Yes Yes Yes Yes Yes
Added at about the
Same Time?
Heat to 280-290 F
and cool before Yes No No No No No No No
adding azelaic acid?
How many heatings to 1
1 1 1 1 1 1 1
400-410 F?
How many
heating/cooling cycles 2 1 1 1 1 1 1 1
total?
Speed of Heating to
Maximum Process Slow (3 Slow
(3 Slow Slow Slow Slow Mode Slow
Temperature hr) hr) (3 hr) (3 hr) (3 hr) (3 hr)
rate (3 hr)
Cooled from
Very
Maximum Process Slow (2 Slow (2 Slow Slow
fast Slow
In air Slow
Temperature How? hr) hr) (2 hr) (2 hr) (2 hr) (2 hr)
(ice)
When was
Beginni Begin Begi Begi Near Begi Begi
Magnesium sulfonate NA
added? ng fling nning
nning End nning nning
% excess LiOH in
final grease 0.12 0.11 0.11 0.12 0.11 0.12 0.10 0.11
% LiOH Monohydrate
based on Worked 60
3.01 2.66 2.70 3.06 2.80 2.43 2.49 2.47
Stroke Pen of 300
Unworked Penetration
299 282 277 295 293 277 286 284
Worked 60 strokes
Penetration 300 283 287 303 299 283 290 293
Dropping Point, F
567 625 602 613 580 580 623 610
Dropping Point, C
297 329 317 323 304 304 328 321
Roll Stability at 25C, 2
hrs:
Initial worked
305 285 289 297 301 287 285 299
Penetration
Final Worked
307 323 325 323 315 301 295 303
Penetration
A Change
0.7 13.3 12.5 8.8 4.7 4.9 3.5 1.3
Roll Stability at 150 C,
2 his:
29
CA 2967558 2017-05-17
Example 4 5 6 7 8 9 10 11
Initial worked 305 285 289 297 301 287 285 299
Penetration
Final Worked
287 311 305 317 295 277 293 297
Penetration
% Change
-5.9 9.1 5.5 6.7 -2.0 -3.5 2.8 -0.7
[0055] As can be seen, the dropping points of the Example 5 ¨ 11
greases were all as good as or better than the Example 4 grease. In fact, the
dropping points of the Example 5 ¨ 11 greases were all as good as or better
than all the Example 1 ¨ 4 greases (Table 2). It is also noted that the
Example 4 grease (and the Example 1 ¨ 3 greases), had two or more heating
and cooling cycles and had separate addition of the two thickener acids with a
heating and cooling cycle between each thickener acid addition. The
Example 5 ¨ 11 greases had only one heating and cooling cycle with both
thickener acids added at about the same time and without any interim heating
or cooling between the additions of the acids. This demonstrates that the use
of a relatively small amount of overbased magnesium sulfonate allows only
one heating and cooling cycle to be needed with both thickener acids being
added at about the same time without suffering a loss of dropping point. By
comparing Example 9 to the other greases in Table 3, it appears that adding
the overbased magnesium sulfonate after the initial thickener reaction, top
heating temperature, and cooling still provides similar benefits to adding it
before the initial thickener reaction.
[0056] Thickener yield can be qualitatively determined by examining
the percent lithium hydroxide monohydrate in the final grease relative to the
worked 60 stoke penetration values. Since both thickener acids will be
completely neutralized by the lithium hydroxide, a lower lithium hydroxide
monohydrate concentration correlates to a lower thickener concentration.
Also, since lithium hydroxide monohydrate costs are extremely high, using
lithium hydroxide monohydrate concentration is appropriate. By using the
customary inverse linear relationship between thickener concentration (as
indicated by lithium hydroxide monohydrate concentration) and penetration
value, an estimated value of the percent lithium hydroxide monohydrate can
CA 2967558 2017-05-17
be determined for what each grease would have had if more or less base oil
had been used to bring the worked penetration to the same value (300) as the
Example 4 grease. Those estimated lithium hydroxide concentrations are
provided in Table 3. As can be seen, all the Example 5 ¨ 11 greases had
significantly improved thickener yield compared to the Example 4 grease
except for Example 7, which used a higher concentration of overbased
magnesium sulfonate A than any of the other greases. Based on the
thickener yield of Example 7, it appears that using too much overbased
magnesium sulfonate A may result in diminished thickener yield even though
dropping point will still be high.
[0057] It is also noted that the Example 11 grease had a dropping
point higher than any of the prior art-based Example 1 ¨ 4 greases, even
though it had a much lower level of azelaic acid relative to 12-hydroxystearic
acid, as evidenced by the 12-hydroxystearic acid/azelaic acid ratio value.
This is particularly significant since it is the azelaic acid that imparts a
dropping point that is higher than a simple lithium soap grease. The use of
overbased magnesium sulfonate is appears to be facilitating a more efficient
interaction of the two thickener components, thereby magnifying the dropping
point enhancing power of the azelaic acid even though less azelaic acid is
used. The thickener yield of the Example 11 grease was also excellent, as
indicated by the adjusted percentage of lithium hydroxide monohydrate.
[0058] By examining the results of Example 8 compared to Example 5,
it is apparent that rapid cooling of the grease from its top temperature does
not impart any additional benefit. This means that optimum thickener yield
and dropping point are not dependent on special equipment or process steps
that require such rapid cooling. Similarly, comparing Example 10 with
Example 5 shows that high dropping points can be obtained when using a
variety of heating and cooling rates.
[0059] Shear stability as indicated by the roll stability data show that all
the greases had acceptable performance in this test. The Example 11 grease
with the lowest relative level of azelaic acid was particularly good in this
regard.
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[0060] Example 12 - Another lithium complex base grease was made
essentially the same as the previous Example 11 grease. The only significant
difference was that this grease had the amount of lithium hydroxide reduced
to a level that was 10%(wt) less than what was required to fully neutralize
both thickener acids. All previous examples had a slight stoichiometric
excess of lithium hydroxide relative to what is required to fully neutralize
all
the acids. The wt/wt ratio of 12-hydroxystearic acid to azelaic acid was 5.78.
This grease behaved noticeably different from all the previous greases in that
the grease was visibly softer from the time it reached top temperature and
was cooled. The initial base oil added was all that was required; no
additional
base oil was added. The final milled grease had a worked 60 stroke
penetration of 294. The dropping point was 620F.
[0061] Since, the lithium hydroxide was intentionally reduced below its
stoichiometric required value in this Example 12 grease, using the percentage
lithium hydroxide monohydrate is not a valid parameter for determining
relative thickener yield. However, the percentage of 12-hydroxystearic and
azelaic acids can be used. For this Example 12 grease the % 12-
hydroxystearic acid was 15.26; the % azelaic acid was 2.64. Comparing
these values to those in Table 3 for the Example 11 grease (which had almost
the same 60 stroke worked penetration as compared to Example 12), it is
apparent that the thickener yield of this Example 12 grease was much lower
than Example 11. This result is very significant. It shows that when
overbased magnesium sulfonate and the aqueous dispersion of lithium
hydroxide are present when the two complexing acids are added, the acids
react with the lithium hydroxide and leave the basic components of the
overbased magnesium sulfonate essentially untouched as long as there is
enough lithium hydroxide to fully react with all the added acids. If this was
not
true, then there would not be such a large difference in thickener yield
between Example 11 (where a slight stoichiometric excess of lithium
hydroxide was present) and Example12 (where the lithium hydroxide was only
90% of what was required). Even so, the dropping point of the Example 12
grease was excellent and it used less lithium hydroxide (which is an
expensive ingredient) than Example 11. Thus, according to another preferred
32
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embodiment, less than a stoichiometric amount of lithium hydroxide is used to
make a sulfonate modified lithium grease.
[0062] Example 13 - Another lithium complex base grease was made
essentially the same as the previous Example 5 grease. The only significant
difference was that a 400 TBN overbased calcium sulfonate was used instead
of the 400 TBN overbased magnesium sulfonate A. The 400 TBN calcium
sulfonate was a poor quality overbased calcium sulfonate as defined in the
406 patent. The wt/wt ratio of 12-hydroxystearic acid to azelaic acid was
3.71. The amount of stoichiometric excess lithium hydroxide in the final
grease was 0.12 /0(wt).
[0063] The grease was made as follows: 746.85 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.63 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
Then 7.76 grams of a 400 TBN overbased calcium sulfonate were added.
The 400 TBN calcium sulfonate was a poor quality overbased calcium. The
mixture was stirred for 15 minutes. Then 43.35 grams of lithium hydroxide
monohydrate and 25.14 grams water were added, and the mixture was
heated to 180 F. Then 155.24 grams of 12-hydroxystearic acid were added
and allowed to melt and mix into the mixture. Almost immediately a thick
grease structure formed. Then 41.86 grams of azelaic acid were added. The
grease structure visibly softened in consistency once the azelaic acid had
melted and mixed into the batch. The temperature of the batch was adjusted
to 190 ¨ 200 F and held there for 45 minutes. Then the batch was heated to
400 ¨ 410 F. This heating step took about 3 hours to complete. When the
target top temperature was reached and held for 15 minutes, the rheostat was
turned down so as to slowly cool the batch over a 2 hour period. During that
time three more portions of the same paraffinic base oil totaling 305.93 grams
were added to the batch.
[0064] Due to the lateness of the day, the heating mantle was
removed and mixing was stopped. The next morning, the batch was mixed
and heated back to 170 F (this is not considered another heat/cooling cycle,
33
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since the batch was only reheated to allow mixing following an overnight
break in the processing). Due to the heaviness of the grease, 176.89 grams
of the same paraffinic base oil were added. The entire batch was given three
passes through a three roll mill with both gaps set at 0.001 inches. The final
milled grease had a worked 60 stroke penetration of 279. The dropping point
was 600 F. The lithium hydroxide monohydrate concentration in the final
grease, as calculated in the previous example greases was 2.92% (based on
the weight of all unreacted ingredients, excluding the weight of water). This
result is surprising in that it shows that overbased calcium sulfonates also
have the ability to provide the same benefits as overbased magnesium
sulfonates regarding the formulation and manufacture of improved lithium
complex greases according to various preferred embodiments of the
invention.
[0065] Example 14 - Another lithium complex base grease was made
essentially the same as the previous Example 13 grease. The only significant
difference was that this grease used about 20 times as much of the same
poor quality overbased calcium sulfonate as the previous Example 13 grease.
This meant that the final concentration of the overbased calcium sulfonate
would have been about 10`)/0(wt), assuming the same amount of base oil was
added during the manufacturing process. Since less base oil was added to
this grease compared to the Example 13 grease, the concentration of
overbased calcium sulfonate in the final product was 12.41%. Likewise, the
amount of stoichiometric excess lithium hydroxide in the final grease product
was 0.14%(wt). The wt/wt ratio of 12-hydroxystearic acid to azelaic acid was
3.71. The wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate was 1Ø
[0066] The batch was made as follows: 660.31 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.92 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
Then 150.69 grams of a 400 TBN overbased calcium sulfonate were added.
The 400 TBN calcium sulfonate was a poor quality overbased calcium
sulfonate as defined in U.S. Patent 9,458,406. The mixture was stirred for 15
34
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minutes. Then 43.35 grams of lithium hydroxide monohydrate and 25.02
grams water were added, and the mixture was heated to 180 F. Then 155.25
grams of 12-hydroxystearic acid were added and allowed to melt and mix into
the mixture. Then 41.89 grams of azelaic acid were added. Unlike the
previous lithium hydroxide base grease examples where an overbased
sulfonate was used, the grease structure of this grease did not soften in
consistency once the azelaic acid had melted and mixed into the batch.
Instead, it continued to thicken. The temperature of the batch was adjusted to
190 ¨ 200 F and held there for 45 minutes. During this time, the batch
became sufficiently heavy that three portions of the same paraffinic base oil
totaling 191.15 grams were added.
[0067] Then the batch was heated to 400 ¨ 410 F. This heating step
took about 3 hours to complete. During this heating step, when the batch
reached about 280 F, it began to become progressively softer. By the time
the batch reached 300 F, it was a liquid with no discernable grease structure.
By the time the batch reached about 360 F, a significant layer of foam had
developed. This remained all the way to the top temperature. When the
target top temperature was reached, the rheostat was turned down so as to
slowly cool the batch to 170 F over a 2 hour period. The batch never
recovered its grease structure. A portion of the final liquid mixture at 170 F
was given three passes through a three roll mill with both gaps set at 0.001
inches. The mixture remained a liquid and was not significantly thickened by
the milling process. The initial grease structure had been entirely lost. This
example demonstrates that using overbased calcium sulfonate in excess of
10% (wt) and/or using a ratio of 12-hydroxystearic acid to overbased calcium
sulfonate of 1 or less may result in failure to form a sufficient grease
structure.
Accordingly, it is preferred that the amount of overbased calcium sulfonate
used be less than 10% and that the ratio of 12-hydroxystearic acid to
overbased calcium sulfonate must be greater than 1. The amount of
overbased sulfonate used in calculating this ratio will typically be the
amount
added before the thickener formation reaction occurs. However, if no
overbased sulfonate is added at that time, but is added later after the
thickener formation has occurred (such as after heating to top temperature
CA 2967558 2017-05-17
and after cooling has begun), then the amount of overbased sulfonate used to
calculate this ratio will be the amount added as such a later point in the
process.
[0068] Example 15 - Another lithium complex base grease was made
essentially the same as the previous Example 14 grease. Like the Example
14 grease, this grease used the same high amount of overbased calcium
sulfonate, (about 20 times as much of the same poor quality overbased
calcium sulfonate as the previous Example 13 grease). This meant that the
final concentration of the overbased calcium sulfonate in this Example 15
would have been about 10%(wt), assuming the same amount of base oil that
was used in the Example 13 grease was added during the manufacturing
process. Likewise, the amount of stoichiometric excess lithium hydroxide in
the final grease would have been 0.11%(wt) if the same amount of base oil
had been added during the manufacturing process. The wt/wt ratio of 12-
hydroxystearic acid to azelaic acid was 3.71. The wt/wt ratio of 12-
hydroxystearic acid/overbased sulfonate was 1Ø The only
significant
difference between this Example 15 grease and the previous Example 14
grease was that this grease used a good quality overbased calcium sulfonate
as defined in the '406 patent.
[0069] The grease was made as follows: 662.07 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.61 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
Then 150.88 grams of a 400 TBN overbased calcium sulfonate were added.
The 400 TBN calcium sulfonate was a good quality overbased calcium
sulfonate as defined in U.S. Patent 9,458,406. The mixture was stirred for 15
minutes. Then 43.35 grams of lithium hydroxide monohydrate and 24.98
grams water were added, and the mixture was heated to 180 F. Then 155.27
grams of 12-hydroxystearic acid were added and allowed to melt and mix into
the mixture. Like the previous Example 14 grease, nothing happened
immediately. However, after about 5 minutes of mixing a thick grease
structure suddenly formed. Then 41.87 grams of azelaic acid were added.
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Once again, like the previous Example 14 grease, the grease structure of this
grease did not soften in consistency once the azelaic acid had melted and
mixed into the batch. Instead, it continued to thicken. The temperature of the
batch was adjusted to 190 ¨ 200 F and held there for 45 minutes. During this
time, the batch became sufficiently heavy that four portions of the same
paraffinic base oil totaling 347.37 grams were added. Then the batch was
heated to 400 ¨ 410 F. This heating step took about 3 hours to complete.
During this heating step, when the batch reached about 280 F, it began to
become progressively softer. By the time the batch reached 340 F, it was a
liquid with little or no discernable grease structure. However, unlike the
previous Example 14 batch, no foam developed during the heating to top
temperature. When the target top temperature was reached, the rheostat was
turned down so as to slowly cool the batch to 170 F over a 2 hour period. By
the time the batch reached 300 F, it began to recover some of its grease
structure. When the grease reached 170 F, it had become a very soft
appearing grease. A portion of this grease was given three passes through a
three roll mill with both gaps set at 0.001 inches. The composition and
unworked penetration of this milled grease are provided below in Table 4.
[0070] Table 4 ¨ Summary of Example 15
Example 15
600 SUS Paraffinic Base Oil % 71.67
Overbased calcium sulfonate (good
quality) 10.71
12-hydroxystearic acid `)/0 11.02
Lithium Hydroxide Monohydrate %
3.03
Azelaic acid % 2.97
Aryl Amine Antioxidant % 0.54
Ratio of 12-hydroxystearic acid-azelaic
acid (wt/wt) 3.71
Ratio of 12-hydroxystearic acid to
Magnesium sulfonate (wt/wt) 1.0
Temperature when 12-hydroxystearic 180
37
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Example 15
acid was added, F
Temperature when LiOH was added, F 75
Order of Addition of LiOH and 12-
hydroxystearic acid LiOH first
Order of Addition of water and LiOH H20 first
12-hydroxystearic acid and azelaic acid
Added at about the Same Time? Yes
Heat to 280-290 F and cool before
adding azelaic acid? No
How many heatings to 400-410 F? 1
Speed of Heating to Maximum Process
Temperature Slow (3 hr)
Cooled from Maximum Process
Temperature How? Slow (2 hr)
Unworked Penetration 367
[0071] The unworked penetration of this grease corresponds to an
NLGI No. 0 grade. The dropping point was not determined since greases of
this consistency usually run out of the dropping point cup at a very low
temperature. This example demonstrates that there is a difference between
how the good and poor quality overbased calcium sulfonates behave when in
various compositions. Unlike the previous Example 14 which used a poor
quality overbased calcium sulfonate, this Example 15 resulted in a grease
even when the %(wt) overbased sulfonate was about 10.0 and when the ratio
of 12-hydroxystearic acid/overbased sulfonate was 1Ø However, the grease
was very soft. It should also be pointed out that the Fourier Transform
Infrared (FTIR) spectrum of this grease showed that the calcium carbonate
from the good quality overbased calcium sulfonate was almost entirely
present as its original amorphous form. There was only a slightly measurable
trace of conversion to crystalline calcium carbonate, but it was not enough to
have contributed to the soft grease structure that formed.
38
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[0072] Additionally, with the amount of lithium hydroxide monohydrate
and overbased calcium sulfonate used, the cost of such a grease like
Example 15 would be extremely high. If one wanted to make a grease like
this one, but with a harder consistency (such as an NLGI No. 2), the higher
amount of lithium complex thickener required would cause the cost to be even
higher.
[0073] Example 16 ¨ Another lithium complex base grease was made
the same as the previous Example 15 grease. The only significant difference
was that instead of a 400 TBN overbased calcium sulfonate, the 400 TBN
magnesium sulfonate A was used. This meant that the final concentration of
the overbased magnesium sulfonate in this Example 16 would have been
about 10%(wt), assuming the same amount of base oil that was used in the
Example 13 grease was added during the manufacturing process. Likewise,
the amount of stoichiometric excess lithium hydroxide in the final grease
would have been 0.11 /0(wt) if the same amount of base oil had been added
during the manufacturing process. The wt/wt ratio of 12-hydroxystearic acid
to azelaic acid was 3.71. The wt/wt ratio of 12-HSA/overbased sulfonate was
1Ø
[0074] The batch was made as follows: 661.58 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 7.71 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
Then 151.29 grams of 400 TBN overbased magnesium sulfonate A were
added. The mixture was stirred for 15 minutes. Then 43.35 grams of lithium
hydroxide monohydrate and 25.04 grams water were added, and the mixture
was heated to 180 F. Then 155.26 grams of 12-hydroxystearic acid were
added and allowed to melt and mix into the mixture. Like the previous
Example 15 grease, nothing happened immediately. However, after about 5
minutes of mixing, visible signs of reaction had still not occurred. Then
41.87
grams of azelaic acid were added. Almost immediately, foaming began as the
level of the batch began to rise in the mixer. After another 10 minutes, the
foam had subsided and a grease structure was evident. The temperature of
39
CA 2967558 2017-05-17
the batch was adjusted to 190 ¨200 F and held there for 45 minutes. During
this time, the batch became sufficiently heavy that five portions of the same
paraffinic base oil totaling 267.21 grams were added. Then the batch was
heated to 400 ¨ 410 F. This heating step took about 3 hours to complete.
During this heating step, when the batch reached about 280 F, it began to
become progressively softer. By the time the batch reached 340 F, it was a
liquid with little or no discernable grease structure. However, unlike the
previous Example 14 batch, no foam developed during the heating to top
temperature. When the target top temperature was reached, the rheostat was
turned down so as to slowly cool the batch to 170 F over a 2 hour period. The
batch remained very thin with no grease structure. Repeated passes through
a three roll mill with both gaps set at 0.001 inches did nothing to thicken
the
product. No significant grease structure had formed.
[0075] Examples 14-16 indicate that the amount of overbased
sulfonate, whether calcium sulfonate, magnesium sulfonate, or a combination
thereof, used is preferably in an amount that is less than 10% by weight of
the
grease ingredients (excluding the weight of water) and that the ratio of 12-
hydroxystearic acid (or other monocarboxylic acid) to overbased sulfonate be
greater than 1.
[0076] Example 17 - A lithium complex base grease was made the
same as previous Example 11. The wt/wt ratio of 12-hydroxystearic acid to
azelaic acid was 5.75. The wt/wt ratio of 12-hydroxystearic acid/overbased
sulfonate was 24.9. A weighed portion of this base grease was placed in an
appropriate sized steel can along with weighed portions of various additives.
This mixture was mixed well by hand using a steel spatula. Then the mixture
was placed in a forced air convection oven held at 212 F. The steel can was
periodically removed, and the grease mixture was stirred by hand using the
steel spatula. Once the temperature of the stirred grease mixture was 170 F,
it was given three passes through a three roll mill with both gaps set at
0.001
inches. The amount of stoichiometric excess lithium hydroxide in the final
milled grease was 0.10 /0(wt). The final composition and test properties of
this
grease are provided below in Table 5.
CA 2967558 2017-05-17
[0077] Table 5 ¨ Summary of Example 17
Example 17
600 SUS Paraffinic Base Oil % 72.11
Overbased magnesium sulfonate A 0.39
12-hydroxystearic acid A. 9.72
Lithium Hydroxide Monohyd rate % 2.29
Azelaic acid `)/0 1.69
Alkenyl amide borate 0.50
Aryl Amine Antioxidant `)/0 0.39
Zinc dialkyl dithiocarbamate 2.50
Zinc di-alky dithiophosphate 0.20
Acrylate-based co-polymer 0.20
Calcium carbonate 5.00
Anhydrous Calcium Sulfate 5.00
Ratio of 12-hydroxystearic acid-azelaic
acid (wt/wt) 5.75
Ratio of 12-hydroxystearic acid to
Magnesium sulfonate (wt/wt) 24.9
Temperature when 12-hydroxystearic
acid was added, F 180
Temperature when LiOH was added, F 75
Order of Addition of LiOH and 12-
hydroxystearic acid LiOH first
Order of Addition of water and LiOH H20 first
12-hydroxystearic acid and azelaic acid
Added at about the Same Time? Yes
Heat to 280-290 F and cool before
adding azelaic acid? No
How many heatings to 400-410 F? 1
41
CA 2967558 2017-05-17
Example 17
Speed of Heating to Maximum Process
Temperature Slow (3 hr)
Cooled from Maximum Process
Temperature How? Slow (2 hr)
Unworked Penetration 281
Worked 60 strokes Penetration 285
Dropping Point, F 591
Dropping Point, C 311
Copper Strip Corrosion 24 hrs, 100 C 1A/1B
Cone Oil Separation, 24 hrs, 100 C 1.6
Cone Oil Separation, 24 hrs, 150 C 2.2
Four Ball Wear, mm 0.43
Four Ball EP, Weld Load, kg 620
Roll Stability at 25C, 2 hrs:
Initial worked Penetration 285
Final Worked Penetration 299
Dropping Point After Test, F 581
% Change 4.9
Roll Stability at 150 C, 2 hrs:
Initial worked Penetration 285
Final Worked Penetration 291
Dropping Point After Test, F 580
% Change 2.1
[0078] The added calcium carbonate and anhydrous calcium sulfate
were of food grade purity and had a mean particle size below 5 microns. As
can be seen, the Example 17 grease had an excellent dropping point, shear
42
CA 2967558 2017-05-17
stability, oil separation properties, extreme pressure/antiwear (EP/AW)
properties, and was passive to copper even when tested at 150 C. The test
data of Table 5 demonstrate that the compositions and methods of preferred
embodiments of the invention are not limited to base lithium complex greases,
but are also fully applicable to finished, additized greases formulated for
high
performance. The low level of lithium hydroxide monohydrate, the much more
favorable ratio of 12-hydroxystearic acid/azelaic acid, and the use of only
one
heating and cooling cycle compared to the Example 1 ¨ 4 greases
demonstrate again the ability of preferred compositions and methods of the
invention to provide good quality lithium complex greases with improved
thickener yield and/or dropping point.
[0079] Example 18 - Another lithium complex grease was made.
Again the wt/wt ratio of 12-hydroxystearic acid to azelaic acid was 5.78. The
wt/wt ratio of 12-hydroxystearic acid/overbased sulfonate was 24.8. The
amount of stoichiometric excess lithium hydroxide in the final grease was
0.10%(wt). This grease used a 400 TBN overbased calcium sulfonate instead
of a 400 TBN overbased magnesium sulfonate. The 400 TBN calcium
sulfonate was the same good quality overbased calcium sulfonate as used in
the previous Example 15 grease.
[0080] The grease was made as follows: 642.53 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 6.01 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
Then 7.64 grams of a 400 TBN overbased calcium sulfonate were added.
The 400 TBN calcium sulfonate was a good quality overbased calcium
sulfonate as defined in the '406 patent. The mixture was stirred for 15
minutes. Then 44.56 grams of lithium hydroxide monohydrate and 25.06
grams water were added, and the mixture was heated to 180 F. Then 189.60
grams of 12-hydroxystearic acid were added and allowed to melt and mix into
the mixture. Almost immediately a thick grease structure formed. Then 32.86
grams of azelaic acid were added. The grease structure visibly softened in
consistency once the azelaic acid had melted and mixed into the batch. The
43
CA 2967558 2017-05-17
temperature of the batch was adjusted to 190 ¨ 200 F and held there for 45
minutes. Then the batch was heated to 400 ¨ 410 F. This heating step took
about 3 hours to complete. When the target top temperature was reached
and held for 15 minutes, the rheostat was turned down so as to slowly cool
the batch over a 2 hour period. During that time, the batch continued to
become increasingly heavy.
[0081] When the batch reached 290 F, 148.50 grams of the same
paraffinic base oil was added. When the batch reached 250 F, 75.01 grams
of calcium carbonate and 75.18 grams of anhydrous calcium sulfonate were
added. The calcium carbonate and the anhydrous calcium sulfonate were of
food grade purity and had a mean particle size below 5 microns. As the batch
continued to become increasingly heavy, three portions of the same base oil
totaling 273.13 grams were added. When the batch reached 200 F, the
following additives were added: 7.56 grams of an alkenyl borated amide; 4.57
grams of a sulfurized polyisobutylene; 3.05 grams of a zinc dialkyl
dithiophosphate; 37.47 grams of a zinc dialkyl dithiocarbamate; 3.07 grams of
an acrylate-based co-polymer; and 15.24 grams of a polyalphaolefin (PAO)
having a viscosity of 4 cSt at 100 C. Due to the lateness of the day, the
heating mantle was removed and mixing was stopped. The next morning, the
batch was mixed and heated back to 170 F. Due to the heaviness of the
grease, two more portions of the same paraffinic base oil totaling 179.69
grams of the same paraffinic base oil were added. The entire batch was
given three passes through a three roll mill with both gaps set at 0.001
inches.
The final milled grease had a worked 60 stroke penetration of 277. The
dropping point was 557 F. The lithium hydroxide monohydrate concentration
in the final grease, as calculated in the previous example greases was 2.55%.
[0082] Example 19 - Another lithium complex grease was made
similar to the previous Example 18 grease. The primary difference was that
this grease not only used the same good quality 400 TBN overbased calcium
sulfonate, it also used a small amount of overbased magnesium sulfonate A.
Again the wt/wt ratio of 12-hydroxystearic acid to azelaic acid of 5.77. The
wt/wt ratio of 12-hydroxystearic acid/ total overbased sulfonate (calcium and
44
CA 2967558 2017-05-17
magnesium) was 18.9. The amount of stoichiometric excess lithium hydroxide
in the final grease was 0.12')/0(wt).
[0083] The grease was made as follows: 641.17 grams of a solvent
neutral group 1 paraffinic base oil having a viscosity of about 600 SUS at 100
F were added to an open mixing vessel. Then 6.23 grams of an aryl amine
antioxidant were added, and mixing began using a planetary mixing paddle.
Then 7.79 grams of a 400 TBN overbased calcium sulfonate were added.
The 400 TBN calcium sulfonate was a good quality overbased calcium
sulfonate as defined in U.S. Patent 9,458,406. Then 2.23 grams of overbased
magnesium sulfonate A were added. The mixture was stirred for 15 minutes.
Then 44.53 grams of lithium hydroxide monohydrate and 25.04 grams water
were added, and the mixture was heated to 180 F. Then 189.57 grams of 12-
hydroxystearic acid were added and allowed to melt and mix into the mixture.
Almost immediately a thick grease structure formed. Then 32.85 grams of
azelaic acid were added. The grease structure visibly softened in consistency
once the azelaic acid had melted and mixed into the batch. The temperature
of the batch was adjusted to 190 ¨ 200 F and held there for 45 minutes. Then
the batch was heated to 400 ¨ 410 F. This heating step took about 3 hours to
complete. During this
heating step, the batch continued to become
increasingly heavy.
[0084] When the temperature of the grease reached 325 F, another
42.26 grams of the same paraffinic base oil were added. When the target top
temperature was reached and held for 15 minutes, the rheostat was turned
down so as to slowly cool the batch over a 2 hour period. During that time,
the batch continued to become increasingly heavy. When the batch reached
290 F, two portions of the same paraffinic base oil totaling 114.57 grams were
added. When the batch reached 250 F, 75.04 grams of calcium carbonate
and 75.03 grams of anhydrous calcium sulfonate were added. The calcium
carbonate and the anhydrous calcium sulfonate both had a mean particle size
below 5 microns. When the batch reached 200 F, the following additives were
added: 7.50 grams of an alkenyl borated amide; 4.66 grams of a sulfurized
polyisobutylene; 3.05 grams of a zinc dialkyl dithiophosphate; 37.52 grams of
a zinc dialkyl dithiocarbamate; 3.21 grams of a acrylate-based co-polymer;
and 15.63 grams of a polyalphaolefin (PAO) having a viscosity of 4 cSt at 100
C. Another 99.10 grams of the same base oil was added and allowed to mix
in. Due to the lateness of the day, the heating mantle was removed and
mixing was stopped. The next morning, the batch was mixed and heated
back to 170 F. Another 29.99 grams of the same paraffinic base oil were
added. The entire batch was given three passes through a three roll mill with
both gaps set at 0.001 inches. The final milled grease had a worked 60
stroke penetration of 285. The dropping point was 535 F. The lithium
hydroxide monohydrate concentration in the final grease, as calculated in the
previous example greases was 2.96%.
[0085] Various ingredients and methodologies to make overbased
calcium sulfonate greases and overbased calcium magnesium sulfonate
greases as described in the '265 and '406 patents and U.S. Patent Application
Serial Nos. 14/990,473, 15/130,422, 15/593,792, 15/593,839, and
15/593,912, may be useful in making lithium carboxylate greases modified
with overbased sulfonate according to various preferred embodiments of the
invention.
[0086] As used herein, amounts of ingredients identified by percentages
or parts are the amounts added as an ingredient by weight relative to the
total
weight of all ingredients added, excluding the weight of water added. All
penetration tests are done according to ASTM D217 or D1403 as commonly
used in lubricating grease manufacturing. In like manner, as used herein the
"dropping point" of a grease shall refer to the value obtained by using the
standard dropping point test ASTM 02265 as commonly used in lubricating
grease manufacturing. Four Ball EP tests as described herein shall refer to
ASTM D2596. Four Ball Wear tests as described herein shall refer to ASTM
02266. Cone Oil Separation tests as described herein shall refer to ASTM
06184. Roll Stability tests as described herein shall refer to ASTM D1831.
Those of ordinary skill in the art will appreciate upon reading this
specification,
including the examples contained herein, that modifications and alterations to
the composition and methodology
46
CA 2967558 2019-09-13
CA 2967558 2017-05-17
for making the composition may be made within the scope of the invention
and it is intended that the scope of the invention disclosed herein be limited
only by the broadest interpretation of the appended claims to which the
inventor is legally entitled.
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