U.S. patent application number 12/827151 was filed with the patent office on 2012-01-05 for lithium complex grease with improved thickener yield.
This patent application is currently assigned to CHEVRON U.S.A. INC.. Invention is credited to Samil Beret.
Application Number | 20120004153 12/827151 |
Document ID | / |
Family ID | 45400155 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120004153 |
Kind Code |
A1 |
Beret; Samil |
January 5, 2012 |
Lithium Complex Grease with Improved Thickener Yield
Abstract
Provided is an improved lithium complex grease. The grease
composition has a higher thickener yield, yet good mechanical
properties. The grease composition comprises a lubricating oil, a
lithium complex thickener and a copolymer, which in one embodiment
may comprise styrene and butadiene.
Inventors: |
Beret; Samil; (Danville,
CA) |
Assignee: |
CHEVRON U.S.A. INC.
San Ramon
CA
|
Family ID: |
45400155 |
Appl. No.: |
12/827151 |
Filed: |
June 30, 2010 |
Current U.S.
Class: |
508/539 ;
508/110; 508/591 |
Current CPC
Class: |
C10M 2207/1265 20130101;
C10N 2030/02 20130101; C10M 117/00 20130101; C10M 2203/108
20130101; C10M 2205/024 20130101; C10M 2203/1085 20130101; C10M
2205/04 20130101; C10M 2203/1006 20130101; C10M 2207/022 20130101;
C10N 2010/02 20130101; C10M 2207/1285 20130101; C10N 2050/10
20130101; C10M 169/06 20130101; C10M 2219/044 20130101; C10N
2040/04 20130101; C10M 2207/1256 20130101; C10N 2040/02 20130101;
C10M 2205/022 20130101; C10M 2205/06 20130101; C10M 2207/16
20130101; C10M 117/04 20130101; C10M 117/02 20130101; C10M 2205/026
20130101; C10M 2207/1276 20130101; C10M 2205/04 20130101; C10M
2205/06 20130101; C10M 2205/022 20130101; C10M 2205/024
20130101 |
Class at
Publication: |
508/539 ;
508/110; 508/591 |
International
Class: |
C10M 117/00 20060101
C10M117/00; C10M 143/10 20060101 C10M143/10; C10M 169/02 20060101
C10M169/02 |
Claims
1. A grease composition having improved thickener yield, comprised
of a major amount of a lubricating base oil, and a minor amount of
a lithium complex thickener.
2. The grease composition of claim 1, where the amount of thickener
and any additives is less than 25 wt % of the grease
composition.
3. The grease composition of claim 1, further comprising a
copolymer of styrene and butadiene.
4. The grease composition of claim 3, wherein the composition has a
thickener yield at least 25% higher than that of a composition with
no copolymer.
5. The grease composition of claim 3, wherein the thickener yield
is at least 35% higher than that of a composition with no
copolymer.
6. The grease composition of claim 3, wherein the thickener yield
is at least 50% higher than that of a composition with no
copolymer.
7. The grease composition of claim 3, further comprising a
copolymer of ethylene and propylene.
8. The grease composition of claim 1, wherein the lithium complex
thickener comprises a lithium salt of a carboxylic acid.
9. The grease composition of claim 8, wherein the lithium complex
thickener comprises a lithium salt of stearic acid.
10. The grease composition of claim 8, wherein the lithium complex
thickener comprises a reaction product of lithium hydroxyl
monohydrate and hydroxystearic acid.
11. The grease composition of claim 8, wherein the amount of
styrene/butadiene copolymer ranges from about 2-6 weight
percent.
12. The grease composition of claim 11, wherein the amount of
styrene/butadiene copolymer ranges from about 3-4 weight
percent.
13. The grease composition of claim 1, wherein the composition has
a worked penetration of at least about 290.
14. The grease composition of claim 1, wherein the composition has
a worked penetration of at least about 300.
15. The grease composition of claim 3, wherein the composition has
a worked penetration of at least about 310.
16. The grease composition of claim 6, wherein the lithium complex
thickener comprises a lithium salt of a carboxylic acid, the amount
of styrene/butadiene copolymer ranges from about 2-6 weight
percent, and the composition has a worked penetration of at least
about 300.
17. A method of lubricating wheel bearings, which comprises coating
the wheel bearings with the grease composition of claim 1.
18. A method of lubricating wheel bearings, which comprises coating
the wheel bearings with the grease composition of claim 16.
19. A method of lubricating an automotive chassis, which comprises
using the grease composition of claim 3 to grease the chassis.
20. A method of lubricating gears, which comprises applying the
grease composition of claim 3 to the gears.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a lithium complex grease
having improved thickener yield. More particularly, a more
economical yet effective lithium complex grease is provided having
a higher weight of base oil incorporated into the grease
matrix.
[0003] 2. Description of the Related Art
[0004] Lithium complex greases have been known and manufactured for
quite some time. Such greases can be made from any of a wide number
of different base stocks of lubricating oil viscosity, and
combination and mixtures of such stocks. The resulting greases are
all marked by varying levels of desirable grease characteristics
including dropping point, penetration, mechanical and/or shear
stability, oxidation resistance, etc., all of which in combination
are taken into account when describing the lubricating life of the
grease.
[0005] Lubricating formulations and greases containing a wide
assortment of different materials are described in the literature.
Lithium complex greases comprising a lithium complex thickener and
a lubricating base oil are well known.
[0006] There remains a need for greases, however, that keep
penetration in an acceptable range while remaining economical and
commercially acceptable.
SUMMARY OF THE INVENTION
[0007] Provided is a grease composition comprising a major amount
of a base oil of lubricating viscosity, and a minor amount of a
lithium complex thickener. The grease composition can further
comprise a copolymer, for example, of styrene and butadiene. In
general, the composition will comprise less than 25 wt % of the
thickener in combination with the copolymer. The present grease
composition exhibits a higher thickener yield, believed due to the
combination of the lithium complex thickener and the copolymer,
which in one embodiment is comprised of styrene and butadiene.
[0008] In one aspect of the present invention, a grease composition
has been discovered which provides good mechanical properties, but
also good economics. The thickener yield for the grease is much
higher due to the presence of the copolymer of styrene and
butadiene. The thickener yield can be at least 25% higher, 35%
higher or even 50% higher than that of a composition without the
copolymer.
DETAILED DESCRIPTION
[0009] The lubricant base oil used in the present invention can be
selected from Group I, II, III, IV, and V lubricant base oils, and
mixtures thereof. The lubricant base oils of the present invention
include synthetic lubricant base oils, such as Fischer-Tropsch
derived lubricant base oils, and mixtures of lubricant base oils
that are not synthetics and synthetics. The specifications for
Lubricant Base Oils defined in the API Interchange Guidelines (API
Publication 1509) using sulfur content, saturates content, and
viscosity index, are shown below in Table I:
TABLE-US-00001 TABLE I Group Sulfur, ppm Saturates, % VI I >300
And/or <90 80-120 II .ltoreq.300 And .gtoreq.90 80-120 III
.ltoreq.300 And .gtoreq.90 >120 IV All Polyalphaolefins V All
Stocks Not Included in Groups I-IV
[0010] Facilities that make Group I lubricant base oils typically
use solvents to extract the lower viscosity index (VI) components
and increase the VI of the crude to the specifications desired.
These solvents are typically phenol or furfural. Solvent extraction
gives a product with less than 90% saturates and more than 300 ppm
sulfur. The majority of the lubricant production in the world is in
the Group I category.
[0011] Facilities that make Group II lubricant base oils typically
employ hydroprocessing such as hydrocracking or severe
hydrotreating to increase the VI of the crude oil to the
specification value. The use of hydroprocessing typically increases
the saturate content above 90 and reduces the sulfur below 300 ppm.
Approximately 10% of the lubricant base oil production in the world
is in the Group II category, and about 30% of U.S. production is
Group II.
[0012] Facilities that make Group III lubricant base oils typically
employ wax isomerization technology to make very high VI products.
Since the starting feed is waxy vacuum gas oil (VGO) or wax which
contains all saturates and little sulfur, the Group III products
have saturate contents above 90 and sulfur contents below 300 ppm.
Fischer-Tropsch wax is an ideal feed for a wax isomerization
process to make Group III lubricant base oils. Only a small
fraction of the world's lubricant supply is in the Group III
category.
[0013] Group IV lubricant base oils are derived by oligomerization
of normal alpha olefins and are called poly alpha olefin (PAO)
lubricant base oils.
[0014] Group V lubricant base oils are all others. This group
includes synthetic esters, silicon lubricants, halogenated
lubricant base oils and lubricant base oils with VI values below
80. For purposes of this application, Group V lubricant base oils
exclude synthetic esters and silicon lubricants. Group V lubricant
base oils typically are prepared from petroleum by the same
processes used to make Group I and II lubricant base oils, but
under less severe conditions.
[0015] Synthetic lubricant base oils meet API Interchange
Guidelines but are prepared by Fisher-Tropsch synthesis, ethylene
oligomerization, normal alpha olefin oligomerization, or
oligomerization of olefins boiling below C.sub.10.
[0016] The lithium complex thickener used in the present grease
composition can be any known lithium complex thickener. For
example, the lithium complex thickener can comprise a lithium soap
derived from a fatty acid containing an epoxy group and/or
ethylenic unsaturation and a dilithium salt derived from a straight
chain dicarboxylic acid and/or, in one embodiment, a lithium salt
derived from a hydroxy-substituted carboxylic acid such as
salicylic acid.
[0017] The thickener can be a complex of a lithium soap of a
C.sub.12 to C.sub.24 hydroxy fatty acid and a monolithium salt of
boric acid and can include a lithium salt of a second hydroxy
carboxylic acid such as salicylic acid.
[0018] The complex can comprise a lithium soap of a C.sub.12 to
C.sub.24 hydroxy fatty acid thickener antioxidant comprising an
alkali metal salt of hydroxy benzoic acid and a diozime compound.
The alkali metal salt of hydroxy benzoic acid include dilithium
salicylate.
[0019] The complex can be a lithium soap which is a combination of
a dilithium salt of a C.sub.4 to C.sub.12 dicarboxylic acid, e.g.,
dilithium azelate, a lithium soap of a 9-, 10- or 12-hydroxy
C.sub.12 to C.sub.24 fatty acid, e.g., lithium 12-hydroxy stearate;
and a lithium salt formed in-situ in the grease from a second
hydroxy carboxylic acid wherein the --OH group is attached to a
carbon atom not more than 6 carbons removed from the carboxyl group
and wherein either of those groups may be attached to either
aliphatic or aromatic portions of the materials.
[0020] Or, the lithium complex can comprise a combination of a
complex lithium soap thickener, a lithium salt of a C.sub.3 to
C.sub.14 hydroxycarboxylic acid and a thiadiazole. The grease may
also optionally and preferably contain additional antioxidants,
preferably amine type or phenol type anti-oxidants, most preferably
amine type antioxidants.
[0021] In one embodiment, the lithium complex thickener is simply a
lithium salt of a carboxylic acid, and in particular a
hydroxycarboxylic acid, such as hydroxystearic acid. Such a
thickener can be prepared, for example, by reacting lithium
hydroxyl monohydrate with the hydroxystearic acid.
[0022] The greases will comprise a major amount, e.g., greater than
50% by weight of the base oil, and a minor amount of the thickener
and any other additives, i.e., less than 50% by weight. The greases
of the present invention may, of course, contain any of the other,
typical grease additives such as rust inhibitors, barium dinonyl
naphtheline fulfonate, order modifiers, tackiness agents, extreme
pressure agents, water shedding agents, dyes, etc. Typical
additives and their function are described in Modem Lubricating
Greases by C. J. Boner, Scientific Publication (G.B.) Ltd.
1976.
[0023] For the present invention, a copolymer is of particular
significance as an additive. The copolymer can be a hydrocarbon
based copolymer such as a copolymer of styrene and butadiene or
ethylene and propylene. In one embodiment, the copolymer additive
is a copolymer of styrene and butadiene. It has been found that use
of a small amount of such a copolymer, e.g. from 2-6 weight
percent, or from 2-5 weight percent, or in another embodiment, from
3-4 weight percent, in combination with a lithium complex
thickener, results in a 25-50% increase in thickener yield.
[0024] Grease thickener yield, defined as the weight of base oil
incorporated into the grease matrix per unit of weight of
thickener, is a key determinant of grease mechanical properties,
such as penetration, shear stability and water resistance as well
as formula cost. The incorporation of the copolymer of styrene and
butadiene with the lithium complex thickener permits the use of a
greater amount of base oil, thereby raising the grease thickener
yield, while maintaining good mechanical properties. The result is
a more economical yet still effective grease.
[0025] Such copolymers of styrene and butadiene are commercially
available. For example, V-211 is a copolymer of styrene and
butadiene available from Functional Products, Inc. of Macedonia,
Ohio. The copolymer is a white-yellow rubber powder which is quick
dissolving. These copolymers of styrene and butadiene can be used
in conjunction with other polymers, but they must be present in the
grease compositions of the present invention.
[0026] By using the styrene/butadiene copolymer in combination with
the lithium complex thickener, higher thickener yields are
obtained. The yield, relating to the amount of base oil one
incorporates into the grease matrix while still realizing good
mechanical properties, can increase by at least about 25 weight
percent, about 35 weight percent, or at least about 50 weight
percent. Such grease compositions have been shown to exhibit worked
penetration properties of at least about 290, at least about 300,
and even at least about 310. The compositions can be used in any
automotive grease or industrial grease application. For example,
the grease compositions can be used for wheel bearings, an
automotive chassis or for lubricating gears.
[0027] The following examples help to demonstrate the present
invention and its advantages, but should not be construed to limit
the scope of the invention.
EXAMPLES
[0028] Several greases were prepared as follows:
[0029] 1-50 wt % of formula amount of base oil(s) were mixed in an
open kettle at room temperature. Formula amount of mono and
di-acids, emulsifier(s) are added with water [at 50% base oil
amount] and stirred while heating to 200.degree. F. At 200.degree.
F., lithium hydroxide is added slowly. Once the lithium hydroxide
had been added, the mixture was heated to 400.degree. F. It was
held at 400.degree. F. while stirring for 20 minutes. The grease is
then cooled to 175.degree. F. while stirring. At 175.degree. F.,
performance additives e.g., rust inhibitor, extreme-pressure and
anti-wear agents and polymers, tackifiers are added. The grease
penetration was adjusted by adding base oil slowly while stirring.
When penetration range was achieved, the grease was cooled to room
temperature and stored suitably.
[0030] Penetration of the greases was tested in accordance with
ASTMD 217. The results are shown in the Table below. In the Table,
the various additives used are as follows:
[0031] 1GEPAL CO-430. Surfonic N-40, Naphthenic Acid:
emulsifiers
[0032] Lubrizol 528C, EC5426A: rust inhibitor
[0033] glycerin, Lubrizol 5200: extreme-pressure, anti-wear
agents
[0034] Lubrizol 2017: PIB polymer
[0035] Lubrizol 2002D: functionalized olefin polymer
[0036] V-2II: copolymer of styrene-butadiene
[0037] V-207: copolymer of ethylene and propylene
TABLE-US-00002 A B C D E F G H PENNZOIL 600 HC 57.31 57.31 57.31
57.31 57.31 57.31 57.31 57.31 CITGO BRIGHT 6.36 6.36 6.36 6.36 6.36
6.36 6.36 6.36 STOCK 150 NYNAS BT450 12-HYDROXYSTEARIC 10.26 10.26
10.26 10.26 10.26 10.26 10.26 10.26 ACID SYNATIVE FA 1110 3.14 3.14
3.14 3.14 3.14 3.14 3.14 3.14 [AZEALIC ACID] SEBACID ACID DIMETHYL
SEBACATE LITHIUM HYDROX 2.93 2.93 2.93 2.93 2.93 2.93 2.93 2.93
MONOHYDRATE IGEPAL CO-430 SURFONIC N-40 0.5 0.5 NAPHTHENIC ACID 0.5
LUBRIZOL 5283C 1 1 1 1 1 1 1 1 EC5426A GLYCERINE 0.5 0.5 0.5
LUBRIZOL 5200 8 8 8 8 8 8 8 8 LUBRIZOL 2017 6 2 3 0 LUBRIZOL 2002D
4 2 4 0 POLYMERS V211 3 3 3 3 3 V207 3 Base Oil Content, wt % 80%
80% 157% 132% 157% 184% 155% 135% Penetration; Worked ASTM 294 319
289 314 291 314 267 271 P(60) D217 Penetration; Unworked 289 226
253 P(60)
[0038] Runs A and B are considered as base cases using a PIB
polymer or a functionalized olefin polymer. In both cases, the base
oil amount used is 80% of formula amount. In runs C and D, when
these polymers are replaced with styrene-butadiene or
ethylene-propylene copolymers, the used base oil amount increases
to 157 and 132% of formula amount respectively. With an increasing
amount of base oil in the formula, thickener yield increases
accordingly. Runs E, F, G, and H show increased thickener yield
with styrene-butadiene copolymer use in conjunction with PIB and
functionalized polymers.
[0039] Various modifications and alterations of this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention. Other objects and
advantages will become apparent to those skilled in the art from a
review of the preceding description.
* * * * *