U.S. patent application number 13/669702 was filed with the patent office on 2013-05-23 for water resistant grease composition.
This patent application is currently assigned to EXXONMOBIL RESEARCH AND ENGINEERING COMPANY. The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to Smruti A. Dance, John Phillips Doner, John K. Graham, James Edward Spagnoli.
Application Number | 20130130953 13/669702 |
Document ID | / |
Family ID | 47228044 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130130953 |
Kind Code |
A1 |
Spagnoli; James Edward ; et
al. |
May 23, 2013 |
WATER RESISTANT GREASE COMPOSITION
Abstract
A grease with improved water resistance is based on a
combination of a polyamide thixotrope with a water insoluble
thickener, preferably a lithium soap/complex thickener and an
antioxidant/corrosion inhibitor/antiwear additive package. The
improvement is maintained when highly effective or aggressive rust
inhibitors which normally tend to degrade water wash out resistance
are present in the grease. Another advantage is that resistance to
fretting is significantly improved to the extent that the greases
containing these components are capable of achieving a high level
of resistance to false brinelling. The greases are particularly
useful for application in wind turbine bearings.
Inventors: |
Spagnoli; James Edward;
(Mount Laurel, NJ) ; Dance; Smruti A.;
(Robbinsville, NJ) ; Graham; John K.; (Ardmore,
PA) ; Doner; John Phillips; (Sewell, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company; |
Annandale |
NJ |
US |
|
|
Assignee: |
EXXONMOBIL RESEARCH AND ENGINEERING
COMPANY
Annandale
NJ
|
Family ID: |
47228044 |
Appl. No.: |
13/669702 |
Filed: |
November 6, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61557002 |
Nov 8, 2011 |
|
|
|
Current U.S.
Class: |
508/136 ;
508/286; 508/513 |
Current CPC
Class: |
C10N 2030/70 20200501;
C10N 2030/26 20200501; C10N 2030/12 20130101; C10N 2050/10
20130101; C10N 2030/06 20130101; C10M 2223/043 20130101; C10M
123/02 20130101; C10M 2205/0285 20130101; C10M 2215/224 20130101;
C10M 2215/0813 20130101; C10N 2030/02 20130101; C10M 2201/1036
20130101; C10M 169/06 20130101; C10M 115/08 20130101; C10M
2207/1256 20130101; C10N 2030/04 20130101; C10M 2207/1256 20130101;
C10N 2010/02 20130101; C10M 2207/1256 20130101; C10N 2010/04
20130101; C10M 2207/1256 20130101; C10N 2010/06 20130101; C10M
2207/1256 20130101; C10N 2010/06 20130101; C10M 2207/1256 20130101;
C10N 2010/02 20130101; C10M 2207/1256 20130101; C10N 2010/04
20130101 |
Class at
Publication: |
508/136 ;
508/513; 508/286 |
International
Class: |
C10M 169/06 20060101
C10M169/06 |
Claims
1. A grease composition which comprises: a lubricating base oil, a
water insoluble thickener, and a thixotropic polyamide.
2. The grease composition according to claim 1 in which the
polyamide comprises a reaction product of (i) a long chain
(C.sub.8-C.sub.20) carboxylic acid derivative and (ii) an alkylene
amine having at least two primary amine groups.
3. The grease composition according to claim 2 in which the
polyamide comprises a diamide which is a reaction product of a
C.sub.10-C.sub.20 carboxylic acid and a C.sub.2-C.sub.4 alkylene
diamine.
4. The grease composition according to claim 3 in which the
polyamide comprises a diamide which is a reaction product of a
C.sub.10-C.sub.20 straight chain fatty carboxylic acid and a
C.sub.2-C.sub.4 alkylene diamine.
5. The grease composition according to claim 4 in which the
polyamide comprises a diamide which is derived from ethylene
diamine, decanoic acid and 12-hydroxyoctadeanoic acid.
6. The grease composition according to claim 4 in which the
polyamide comprises a diamide which is mixture of
N,N'-ethane-1,2-diylbis(decanamide), 12-hydroxy-N-[2(1-oxydecyl)
amino]ethyloctadecanamide and
N,N'-1,2-diylbis(12-hydroxyoctadecanamide).
7. The grease composition according claim 1 in which the thickener
comprises an aluminum, barium, calcium or lithium soaps, or an
aluminum, barium, calcium or lithium salt/soap complex.
8. The grease composition according claim 7 in which the thickener
comprises a lithium salt/soap complex.
9. The grease composition according claim 1 in which the thickener
comprises an inorganic clay thickener.
10. The grease composition according claim 1 in which the
lubricating base oil comprises a poly alpha olefin.
11. The grease composition according claim 10 in which the
lubricating base oil comprises a poly alpha (C.sub.8-C.sub.12)
olefin.
13. The grease composition according claim 10 in which the
lubricating base oil comprises a poly alpha (C.sub.8-C.sub.12)
olefin having a kinematic viscosity of 2 to 10 cSt and a poly alpha
(C.sub.8-C.sub.12) olefin having a kinematic viscosity of 100 to
200 cSt.
14. The grease composition according claim 1 which comprises at
least one of a corrosion inhibitor, an antioxidant and an antiwear
agent.
15. The grease composition according claim 14 in which the
corrosion inhibitor comprises an amine phosphate derived from a
tertiary alkylamine and acid phosphate moiety derived from a
phosphoric acid represented by the formula.
R.sub.1O(R.sub.2O)P(O)OH, where R.sub.1 is hydrogen or
C.sub.10-C.sub.20 hydrocarbyl and R.sub.2 is hydrocarbyl and
R.sub.1 and R.sub.2 may be the same or different.
16. The grease composition according claim 14 which comprises an
imidazoline rust inhibitor.
17. The grease composition according claim 16 in which the
imidazoline rust inhibitor comprises a long chain alkyl or alkenyl
(C.sub.8-C.sub.20) imidazoline.
18. The grease composition according claim 17 in which the
imidazoline rust inhibitor comprises 2-oleyl imidazoline.
19. The grease composition according claim 1 which has a rating in
the Riffel Test of maximum scar less than 10.mu., average scar less
than 3.mu. and corrosion not more than 3.
20. The grease composition according claim 1 which has a water
resistance (ASTM D 1264) of not more than 10%.
21. The grease composition according claim 1 which has an oil
separation (ASTM D 6184) less than 5%.
22. The grease composition according claim 1 which has a
low-temperature starting torque (ASTM D 1478, -40.degree. C.) not
more than 4,000 g-cm.
23. A grease composition having improved water resistance,
mechanical grease stability and low temperature performance which
comprises: (i) a synthetic hydrocarbon base oil, (ii) a lithium
complex thickener, (iii) a thixotropic, water-insoluble,
oil-insoluble polyamide co-thickener derived from at least one
C.sub.8-C.sub.20 monocarboxylic fatty acid and a C.sub.2-C.sub.6
alkylene diamine, (iv) a corrosion inhibitor (v) an antioxidant,
and (vi) an antiwear agent.
24. The grease composition according to claim 23 in which: (i) the
base oil comprises a polyalpha olefin), (ii) the thixotropic
polyamide co-thickener is derived from decanoic acid,
12-hydroxystearic acid and ethylene diamine, and (iii) the
corrosion inhibitor comprises an amine phosphate and/or an alkyl
imidazoline.
25. The grease composition according to claim 24 which comprises:
(i) from 70 to 85 wt % of the base oil, (ii) from 6 to 14 wt % of
the lithium complex thickener, (iii) from 0.1 to 5 wt % of the
polyamide co-thickener.
26. A grease composition having improved water washout resistance
and anticorrosion characteristics having a water washout resistance
(D 1264) not more than 15%, low-temperature torque starting torque
(ASTM D 1478, -40.degree. C.) not more than 4,000 g-cm, and oil
separation (ASTM D6184) less than 8.
27. The grease according to claim 26 having a water washout
resistance (D 1264) not more than 10%, and low-temperature torque
starting torque (ASTM D 1478, -40.degree. C.) not more than 3,000
g-cm, and an oil separation (ASTM D 6184) less than 5%.
28. The grease according to claim 26 having a water washout
resistance (D 1264) not more than 15%, low-temperature torque
starting torque (ASTM D 1478, -30.degree. C.) not more than 2,000
g-cm, and an oil separation (ASTM D 6184) less than 8%.
29. The grease according to claim 26 having an Oil separation (ASTM
D 6184) less than 5%.
30. The grease according to claim 26 having a negative change in
penetration in the Wet Roll test (ASTM D 7342-2 (Procedure B, 10%
DI at room temperature).
31. A method of making a grease composition having improved water
resistance, mechanical grease stability and low temperature
performance which comprises providing the following components: (i)
a synthetic hydrocarbon base oil, (ii) a lithium complex thickener,
(iii) a thixotropic, water-insoluble, oil-insoluble polyamide
co-thickener derived from at least one C.sub.8-C.sub.20
monocarboxylic fatty acid and a C.sub.2-C.sub.6 alkylene diamine,
(iv) a corrosion inhibitor (v) an antioxidant, and (vi) an antiwear
agent, and mixing the components to form a grease.
32. The method according to claim 31 in which: (i) the base oil
comprises a poly(alpha olefin), (ii) the thixotropic polyamide
co-thickener is derived from decanoic acid, 12-hydroxystearic acid
and ethylene diamine, and (iii) the corrosion inhibitor comprises
an amine phosphate and/or an alkyl imidazoline.
33. The method according to claim 32 which comprises: (i) from 70
to 85 wt % of the base oil, (ii) from 6 to 14 wt % of the lithium
complex thickener, (iii) from 0.1 to 5 wt % of the polyamide
co-thickener.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 61/557,002 filed on Nov. 8, 2011, which is
incorporated herein in its entirety by reference.
FIELD
[0002] This disclosure relates to a grease composition with
improved water and corrosion resistance which is particularly
useful for use in wind turbine gearboxes and bearings as well as in
other applications where heavy loads are encountered in adverse
environments, especially when high loadings may prevail. In
addition, improved low temperature performance and stability have
been demonstrated.
BACKGROUND
[0003] The use of polymers to impart desirable properties to
greases is known and widely practiced by grease manufacturers; see,
for example, the description of various thickeners in Manufacture
and Application of Lubricating Greases (1954), Reinhold, N.Y. 1954
and Alteration of Grease Characteristics with New Generation
Polymers, G. D. Hussey, NLGI Spokesman, August 1987. Oil soluble
polymers have been used, for example, to increase the structural
stability of greases and to confer reduced oil separation, and
increased water resistance. Although these benefits could be
obtained without polymers by using lubricating oils having high
viscosity basestocks, the resulting debit on low temperature
mobility (i.e., pumpability) severely limits a non-polymer
approach.
[0004] Water resistance is a property desirable in grease for many
industrial applications; for example, in papermaking machinery and
gearboxes, power transmissions and other bearings used in wet
environments such as the slewing bearings in large outdoor antenna
mountings and cranes on offshore oil rigs. It has been previously
found that polymers may be effective in improving the water
resistance of industrial and automotive greases. U.S. Pat. No.
5,110,490 (Pink), for instance, discloses a grease composition with
enhanced water resistance containing an ethylene copolymer with
amine functionality. The copolymer is produced by reaction of a
polyamine such as ethylene diamine with an ethylene copolymer
grafted with carboxylic moieties by reaction with and unsaturated
carboxylic acid or anhydride group, for example, maleic anhydride.
Amine functionalized ethylene copolymers of this type are described
in U.S. Pat. No. 4,517,104 (Bloch) to which reference is made for a
description of them.
[0005] Polymer additives are well established for enhancing enhance
grease performance at low treatment levels as reported in NLGI
Paper Benefits of Polymer Additives in Grease, Larson, et al, NLGI
Spokesman, ISSN: 00276782, Vol: 73, Issue 7. As discussed in that
paper, the challenges facing grease manufacturers face can be
addressed with the inclusion of polymer additives in a variety of
grease types. The benefits of polymer additives in this study are
shown to include improved shear stability, enhanced water
resistance, and increased yield. In addition to performance
enhancements, selected polymer additives may provide economic
benefits through increased grease yields of up to 17%.
[0006] Polymers that have been studied as grease additives include
polyisobutylene (PIB), ethylene-propylene copolymers (OCP),
styrene-hydrogenated butadiene (SBR), styrene-hydrogenated isoprene
(SI), radial hydrogenated polyisoprene (star), acid functionalized
polymers (FP), polymethacrylate (PMA), styrene ester copolymers
(SE), and styrene ethylene butylene copolymers (SEBCP). These
polymers have been used as co-thickeners e.g. with a calcium soap
as described in U.S. Pat. No. 5,084,193 (Waynick) or as the sole
thickener as in U.S. Pat. No. 5,874,391 (Meijer).
[0007] One application where water resistance is of major
importance in grease formulations is wind turbine lubrication,
especially in the stewing (pitch and yaw) bearings. Other
significant factors include the life of the grease since the
nacelles of the turbines are usually inaccessible for maintenance
as well as elastomer and paint compatibility. Another and
potentially more serious factor in the formulation of wind turbine
greases is the need to provide protection against false brinelling
which is the wear by fretting which occurs in bearings which are
subjected to vibration in the absence of rotation. When the bearing
is not turning, the minute oscillations which take place displace
the grease from the bearing contact surfaces without allowing it to
flow back, resulting in metal to metal contact, wear and damage
which will cause the bearing to fail. In addition, capillary
action, or damaged seals may allow water to enter the bearing,
creating the potential for corrosion which further accelerates the
damage. The bearing damage which occurs appears as "ripple"
formations in the bearing surfaces. False brinelling is likely to
be encountered in wind turbine pitch and yaw bearings as a result
of the turbine being stationary either in low wind conditions or,
contrarily, when high winds speeds necessitate shut down to avoid
over-speeding. When this occurs, the bearings are subject to
wind-induced vibrations which may accelerate escape of the
lubricant from the bearing contact surfaces, creating the potential
for fretting and bearing failure.
[0008] Along with water resistance, corrosion resistance is another
highly important performance characteristic in wind turbine greases
given the service conditions under which the turbines operate,
often in remote wind- and rain-swept locations and often at sea.
Corrosion inhibitors therefore form a necessary part of the
additive package and in view of the harsh operating environments,
it may be necessary to resort to the most effective types of
corrosion inhibitors. Anti-wear performance is also significant in
view of the heavy loadings to which wind turbine bearings are
exposed for extended periods of time without the opportunity for
routine maintenance.
SUMMARY
[0009] We have now found that improved water resistance in greases
provided by a unique combination of a thickener, preferably a
lithium salt soap thickener in combination with an oil insoluble
polyamide thixotrope as a co-thickener; the improvement is,
moreover, maintained when highly effective or aggressive rust
inhibitors which normally tend to degrade grease stability and
water wash out resistance are present in the grease. Another
advantage which we have found is that resistance to fretting is
significantly improved to the extent that the greases containing
these components are capable of achieving good ripple protection in
the Riffel Test.
[0010] According to the present disclosure the greases have a
grease base of a lubricating base oil, a water- and oil-insoluble
thickener, and an oil insoluble, thixotropic polyamide
co-thickener. To this base formulation, additives including at
least antioxidants, corrosion inhibitors and anti-wear agents will
normally be added to obtain the desired final combination of
properties. These greases, when fully formulated, exhibit a highly
advantageous combination of properties including good water
resistance as well as mechanical stability in wet conditions and
good low temperature properties; this combination makes them
eminently suitable for use in wind turbine bearings.
BRIEF DESCRIPTION OF E DRAWINGS
[0011] FIG. 1 is a bar graph of water wash-out versus wt %
polyamide of Example 2.
[0012] FIG. 2 is a bar graph of oil separation versus wt %
polyamide of Example 1.
DETAILED DESCRIPTION
[0013] All numerical values within the detailed description and the
claims herein are modified by "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art.
Lubricating Base Oil
[0014] The present greases are preferably synthetic greases, that
is, greases which are based on a synthetic liquid lubricating
component but mineral oil lubricating bases may also be used. If a
mineral oil base is used, it will typically be a neutral
(paraffinic) base stock with a viscosity from 2 to 500 cSt, more
usually 2 or 4 to 300 cSt, (40.degree. C.) although for some power
transmission applications, heavier base stocks may also be used.
Blends of low viscosity oils, e.g. 2 to 10 cSt with higher
viscosity oils e.g. 100 cSt or higher, are likely to be
particularly favorable. One class of base oils derived from mineral
oil sources which are potentially useful are the high viscosity
index hydrocracked, catalytically dewaxed oils of API Groups II, II
Plus, III and III Plus. These oils, especially the higher end Group
II oils with viscosity indices of 110 to 120 (SAE) and the Group
III oils with viscosity indices over 120 and higher, e.g 130 or
140, approaching those of the totally synthetic poly alpha olefins
are particularly desirable base stocks for the greases whether used
on their own or in combination with a synthetic base stock
component, e.g. a poly alpha olefin (PAO) stock. Another class of
useful base oils is the synthetic Fischer-Tropsch oils, especially
those derived from waxy, Fischer-Tropsch (F-T) synthesized tube
range fractions by hydroisomerization and catalytic dewaxing to
improve the low temperature flow properties of the oil and improve
its viscosity index. The F-T process used to form the initial waxy
hydroisomerization feed is preferably one produced with a slurry
F-T process using a cobalt catalyst. Lube base stocks of this kind
are described in US 2002/0086803. Hydroisomerization over zeolite
catalysts is a particularly preferred hydroisomerization/dewaxing
technique.
[0015] Among the synthetic base oils, the poly alpha olefins (PAOs)
constitute the most preferred class, having excellent oxidation
stability and resistance to hydrolytic attack. Blends of the PAOs
with either the high VI hydroisomerized mineral oils or the F-T
lube stocks mentioned above are also especially favorable for their
rheolology characteristics, especially VI and low temperature
fluidity. The synthetic esters oils such as the Type I (dibasic
acid, e.g. sebacic acid, azelaic,acid esters such as dicotly
sebacate) and the Type II (polyol/monobasic acid esters, especially
the neopentyl polyol esters e.g. the trimethylopropane,
pentaerythritol of C.sub.8-C.sub.10 acids) are not generally
favored in view of their susceptibility to hydrolytic attack but
they may be present in minor amounts to promote good seal swell and
additive solvency, if needed. Other synthetic base stocks include
the alkylbenzenes, carbonate esters (e.g., the product of reacting
C.sub.8 oxo alcohol with ethyl carbonate to form a half ester
followed by reaction of the latter with tetraethylene glycol,
etc.), polyphenyl ethers, e.g., those having from about 3 to 7
ether linkages and about 4 to 8 phenyl groups polyalkylene glycols
and the polyphenyl ethers. Synthetic components such as the long
chain alkylated naphthalenes may be used as blend components, e.g.
for added additive solvency, if required.
[0016] Normally, the lubricating oil will comprise a major amount
of the grease composition. Typically, the amount of lubricating oil
will range from above about 50 to about 90 wt %, preferably from
about 70 to about 85 wt %, of the grease composition.
Grease Thickener
[0017] The grease will contain an essentially water- and
oil-insoluble thickener to provide the desired grease consistency
and structure (cone penetration, dropping point, etc). Thickeners
may be of the soap or non-soap types. Non-soaps are based on
organic or non-organic solids such as bentonite clay, polymers such
as the polyureas or silica aerogels and may be used where their
particular properties so indicate. The preferred thickeners for the
present greases are the metal salt/soap thickeners, including the
complex soap thickeners based on metals including aluminum, barium,
calcium, lithium, sodium, with the lithium salt/soap complex
thickeners being the most preferred. These types of thickeners are
well established and are described in numerous publications. See,
for example, Boner op cit, Lubricants and Related Products,
Klamann, Verlag Chemie, 1984, ISBN 3-527-26022-6, ISBN
0-89573-177-0 to which reference is made for a description of
suitable thickeners and the manufacture of grease incorporating
them.
[0018] The complex grease thickeners are made by combining the
conventional metallic soaps with a complexing agent. The soaps are
typically a metal salt of a long chain fatty acid having from 8 to
24 carbon atoms such as decanoic acid, myristic acid, palmitic acid
or stearic acid. Particularly preferred is a lithium or lithium
complex thickener that incorporates an hydroxy fatty acid having
from 12 to 24 (preferably from 16 to 20) carbon atoms. A preferred
hydroxy fatty acid is an hydroxy stearic acid, e.g., 9-hydroxy or
10-hydroxy stearic acid, with 12-hydroxy stearic acid being the
most preferred. Other hydroxyl fatty acids which may be used
include ricinoleic acid (12-hydoxystearic acid unsaturated at the
9,10 position), 12-hydroxybehenic acid and 10-hydroxypalmitic acid.
The complex salt/soap thickeners are made with a combination of
conventional lithium soap such as lithium 12-hydroxystearate and a
complexing agent which may vary with the type of thickener, e.g.
calcium complex thickeners may be formulated with acetic acid and
hydroxy-substituted acids; boric acid may be used with lithium
soaps. Low molecular-weight organic acid, typically C.sub.4 to
C.sub.12 dibasic acids such as glutaric, azelaic, pimelic, suberic,
adipic or sebacic acids, are generally favored as the complexing
agents with lithium greases. The complexes are formed by the
introduction of the complexing agent or its metal salt into the
lattice of the metal salt. Examples of metal salt/soap complex
thickeners are described in U.S. Pat. No. 3,929,651; 3,940,339;
4,410,435; 4,444,669 and 5,731,274. The complexing agent may be
added as the free acid, a salt e.g, the lithium salt or as an ester
such as an alkyl ester, e.g. methyl glutarate or methyl adipate,
which will undergo hydrolysis to the acid in the presence of the
added alkali, e.g. lithium hydroxide, to form the complexing
agent.
[0019] The amount of thickener in the lubricating composition will
typically range from about 1 to about 20 wt %. For most purposes,
between about 6 to about 14 wt %, preferably between about 8 to
about 10 wt %, of the thickener will be present in the composition.
PAO bases may require a higher proportion of thickener than mineral
oil basestocks.
Polyamide Co-Thickener
[0020] The present greases contain a polyamide thixotrope as a
co-thickener which contributes to the formation of the thickener
matrix. The thixotrope is essentially insoluble in water and oil in
order to maintain the grease structure and the desired resistance
to water wash out. Thixotropes create a viscosity increase that is
reversed during shearing but then reforms when the shear forces are
removed. This characteristic has been found to provide advantageous
properties when used in combination with the remaining grease
components.
[0021] The polyamides used in the present formulations have two or
more amide groups [R--CO--NR'--R'] in their structure formed by
reaction of a diamine, with a carboxylic entity. The diamine
reactant will have two or more amine groups which may be either
primary or secondary amine groups. Typical preferred amine
compounds include the alkylene diamines of the formula:
H--NR'-[-alkylene-NR'--].sub.x--H
where R and R' which may be the same or different and may each be H
or alkyl groups, typically of 2 to 6 carbon atoms and alkylene has
2 to 6 carbon atoms and x is an integer of about 1 to 10,
preferably about 2 to 7, and the alkylene radical is a straight or
branched chain alkylene group or substituted alkylene group having
2 to 10, preferably 2 to 7, more preferably 2 to 4, carbon atoms;
the primary amities are preferred (R' is H).
[0022] Examples of the alkylene diamines of the above formula
include ethylene diamine, propylene diamines, butylene diamines,
pentylene diamines, hexylene diamines, heptylene diamines,
dioctylene amines, other polymethylene amines, e.g. hexamethylene
diamine. Polyamines e.g. triamines, etc are not generally favored
in view of their tendency to form polymers which do not possess the
desired thixotropic properties.
[0023] The preferred amines for the synthesis of the present
thixotropes are the straight chain alkylene diamines which produce
polyamides of substantially linear structure consistent with the
thixotropic character. Examples of such diamines include ethylene
diamine, 1,3-propylene diamine, 1,4-butylene diamine, hexamethylene
diamine with special preference for ethylene diamine and
hexamethylene diamine for their commercial availability.
[0024] The carboxylic component includes C.sub.4+ monocarboxylic
acids, typically long chain fatty acids from 8 to 20 carbon atoms
and their derivatives including anhydrides, acyl halides and other
entities capable of reaction with the primary amine groups of the
polyamine to form the amide linkages. Polycarboxyylic acids are not
favored in view of their tendency to react with the diamine
reactant to form the undesired higher molecular weight condensation
polymers which are not thixotropes; the molecular weight of the
polyamide should not exceed about 800 and in most cases, not more
than 650 for good thixotropic properties. Preferably, the molecular
weight should be in the range of 250 to 630. The hydrocarbon groups
attached to the carboxyl moiety may typically be alkyl, alkenyl,
aryl, alkaryl, aralkyl and may be substituted by heteroatoms or
other groups such as hydroxyl or hydroxyalkyl groups. The preferred
carboxyl reactants are essentially aliphatic and include alkenyl
and alkyl groups with straight chain alkyl groups and hydroxylalkyl
groups being preferred. Particularly preferred carboxyl compounds
are the C.sub.8 to C.sub.20 alkyl and hydroxyalkyl monocarboxylic
acids. The carboxyl component may contain hydrocarbon and
substituted hydrocarbon groups of varying chain length, for
example, a mixture of C.sub.10 and C.sub.18 alkyl and hydroxyalkyl
acids.
[0025] A currently preferred carboxyl component comprise a
combination alkanoic and hydroxyalkanoic acids, preferably a
mixture of a C.sub.8 to C.sub.18 alkanoic acid with a C.sub.8 to
C.sub.18 hydroxyalkanoic acid. The alkanoic acid is preferably the
major component of the mixture with the hydroxyalkanoic acid being
present in a lesser amount. A particularly preferred carboxylic
reactant is a mixture of decanoic acid and 12-hydroxystearic acid.
With ethylene diamine as the amine component, the polyamide formed
from these two acids will be a mixture of three individual diamides
with the formulae:
##STR00001##
Preferably, the mol ratio between these reactants will be from 0.2
to 1 mol of the alkanoic acid and 0.1 to 1 mol of the
hydroxyalkanoic acid per mol of the diamine. Polyamides of this
type are disclosed in U.S. Re 41,588.
[0026] The carboxyl-donating component may be used in the form of a
salt or other derivative, e.g. ester, anhydride or halide which is
capable of reacting with the diamine to form the desired amide,
[0027] The amine and acid component will generally be prereacted to
form the polyamide prior to admixing with the other grease
components. Typically the amount of the polyamide will range from
about 0.01 to about 4 wt %, preferably from about 0.1 to about 2 wt
%, based on weight of the grease, although larger amounts could be
used if desired.
Grease Manufacture
[0028] The grease making procedures either in a hatch process with
contactor followed by finishing kettle or in a continuous
greasemaking process are well known and widely used. In batch
greasemaking, the grease is usually prepared by chemically reacting
and mechanically dispersing the thickener components in the
lubricating oil for from about 1 to about 8 hours or more
(preferably from about 3 to about 6 hours) followed by heating at
elevated temperature (e.g., from about 140 to about 225.degree. C.
depending upon the particular thickener used) until the mixture
thickens. In sonic cases (e.g. a simple lithium grease), a
preformed thickener can be used. The mixture is then cooled to
ambient temperature (typically about 60.degree. C.) during which
time additive package is added.
[0029] The polyamide thixotropes may be incorporated into a
semi-finished grease containing the base oil and thickener possibly
with the additive package present or added earlier as a blend
component. The polyamides are typically viscous liquids,
semi-liquids or, quite often powders and in order to facilitate
blending into the grease base, it may be necessary in the case of
the powder materials or, in the case of the liquids, desirable, to
heat the polyamide prior to incorporation into the other grease
components. In a batch type process, the polyamide may be liquefied
prior to being added to the contactor in which the components of
the thickener are to be reacted in the presence of the base oil
although it has been found preferable to add powdered thixotrope to
the finishing kettle that is at a high enough temperature to melt
the thixotrope but sufficiently low to avoid exposure to the higher
temperatures typically prevailing in the contactor during the
soapmaking step; in addition, this sequence avoids subjecting the
thixotrope to high temperature/high shear conditions of the
contactor likely to degrade the thixotropic properties. The
temperatures in the finishing kettle will typically be 120.degree.
C. or higher so as to preclude separation of the polyamide before
it becomes incorporated into the grease mass. In a continuous
greasemaking process, the polyamide may be added as one of the
blend components to where the line where the temperature/shear
regime is suitable for the particular thixotrope.
[0030] A continuous greasemaking process for making lithium complex
greases is described to U.S. Pat. No. 7,829,512.
[0031] The grease composition can be mixed, blended, or milled in
any number of ways including external mixers, roll mills, internal
mixers, Banbury mixers, screw extruders, augers, colloid mills,
homogenizers, and the like.
Additives
[0032] The grease composition will typically contain small amounts
of additives such as anticorrosive agents, extreme pressure and
antiwear agents, pour point depressants, tackiness agents,
oxidation inhibitors, dyes, and the like. The amounts of individual
additives will vary according to the additive and the level of
functionality to be provided by it. The total amount of these
additives will typically range from about 2 to about 5 wt % based
on total weight of the grease composition. In addition, solid
lubricants such as molybdenum disulfide and graphite may be present
in the composition, typically from about 1 to about 5 wt %
(preferably from about 1.5 to about 3 wt %) for molybdenum
disulfide and from about 3 to about 15 wt % (preferably from about
6 to about 12 wt %) for graphite.
[0033] When the additives are described below by reference to
individual components used in the formulation, they will not
necessarily be present or identifiable as discrete entities in the
final product but may be present as reaction products which are
formed during the grease manufacture or even its use. This will
depend on the respective chemistries of the ingredients, their
stoichiometry, and the temperatures encountered in the greasemaking
process or during its use. It will also depend, naturally enough,
on whether or not the species are added as a pre-reacted additive
package. For example, the acid amine phosphates may be added as
discrete amines and acid phosphates but these may react to form a
new entity in the final grease composition under the processing
conditions used in the grease manufacture.
[0034] At least one antioxidant will be present to retard oxidative
degradation of the grease while in storage and use. Typically,
these additives will be either aminic antioxidants or phenolic
antioxidants; antioxidants of these two classes may be used
together. Aminic antioxidants are generally aromatic amines of
which the naphthylamines are in common use, e.g.
alpha.-naphthylamine, phenyl-alpha.-naphthylamine,
butylphenyl-.alpha.-naphthylamine,
pentylphenyl-.alpha.-naphthylamine,
hexylphenyl-.alpha.-naphthylamine,
heptylphenyl-.alpha.-naphthylamine,
octylphenyl-.alpha.-naphthylamine and
nonylphenyl-.alpha.-naphthylamine; the monoalkylphenyl
alpha-naphthylamines e.g. tert.-octyl-phenyl-.alpha.-naphtylamine
and monononyldiphenylamine are particular common. Other classes of
aromatic amines include the dinuclear aromatic amines such as the
dialkyl-diphenylamines, e.g. 4,4'-dibutyldiphenylamine,
4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine,
4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine and
4,4'-dinonyldiphenylamine; polyalkyldiphenylamines such as
tetrabutyldiphenylamine, tetrahexyldiphenylamine,
tetraoctyldiphenylamine and tetranonyldiphenylamine. Amities of
both types may be used singly or in combination with one another.
The combination of tert.-octyl-phenyl-.alpha.-naphtylamine and
dioctyl-diphenylamine is common Amine antioxidants are generally
used in amounts from about 0.01 to 5 wt %, more usually from 0.5 to
1.5 wt %. Phenolic antioxidants, typically used in amounts from
about 0.01 to 5 wt %, more usually from 0.5 to 1.5 wt %., are
typified by the alkylated hydroxytoluenes, e.g. butylated
hydroxytoluene.
[0035] Other types of antioxidant may also be considered, including
the sulfur-containing antioxidants, for example, dialkyl
thiodipropionates such as dilauryl thiodipropionate and distearyl
thiodipropionate, dialkyldithiocarbamic acid derivatives (excluding
metal salts), bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide,
mercaptobenzothiazole, reaction products of phosphorus pentoxide
and olefins, and dicetyl sulfide,
[0036] Given the necessity of securing good corrosion resistance,
the grease will include a corrosion inhibitor of a type which is
effective for rust inhibition; non-ferrous metal, especially
copper, passivation functionality may also be useful. Corrosion
inhibitors are a well-established class of additives and may
typically be physical inhibitors which form a barrier type film on
the metal or chemical type inhibitors which react on the metal
surface to form a protective coating. Physical type inhibitors
include the metal naphthenates and petroleum sulfonates, e.g barium
petroleum sulfonates, zinc naphthenate and the like with preference
for the zinc and calcium salts for their improved environmental
acceptability.
[0037] The metal sulfonates and naphthenates are very effective and
favored in many applications as corrosion inhibitors and have been
found to be effective in wet tests but some greases formulated with
the polyamide thixotrope and this class of corrosion inhibitors
have been found to be subject to failure in corrosion testing. For
this reason, the metal sulfonate/naphthenate corrosion inhibitors
are not preferred in the current formulations.
[0038] The more aggressive chemical type inhibitors including the
amine phosphates and imidazolines, are known to confer good
corrosion (rust) inhibition in the conventional grease compositions
even though these greases with alternative types of thickener
system have been found to undergo degradation of the grease
structure with these additives. The present greases, however, have
been found to possess excellent mechanical stability even in the
presence of water and under wet agitation (churning).
[0039] The amine rust inhibitors will generally contain from 8 to
24 carbon atoms and can be primary, secondary, tertiary, acyclic or
cyclic, mono or polyamines. They can also be heterocyclic. The
amine containing components can also contain other substituents,
e.g, ether linkages or hydroxyl moieties. The preferred amines are
generally aliphatic in nature. Some specific examples include:
octylamine, decylamine, C.sub.10, C.sub.12, C.sub.14 and C.sub.16
tertiary alkyl primary amines (or combinations thereof),
laurylamine, hexadecylamine, heptadecylamine, octadecylamine,
decenylamine, dodecenylamine, palmitoylamine, oleylamine,
linoleylamine, di-isoamylamine, di-octylamine,
di-(2-ethylhexyl)amine, dilaurylamine, cyclohexylamine,
1,2-propylene amine, 1,3-propylenediamine, diethylene triamine,
triethylene tetraamine, ethanolamine, triethanolamine,
trioctylamine, pyridine, morpholine, 2-methylpiperazine,
1,2-bis(N-piperazinyl-ethane), 1,2-diamine, tetraminooctadecene,
triaminooctadecene, N-hexylaniline and the like. They may also be
triazole or triazole derivatives, which are described elsewhere as
a necessary ingredient in the composition according to the present
disclosure.
[0040] A preferred group of amities for this disclosure to serve as
rust inhibitors are the oil-soluble aliphatic amines in which the
aliphatic group is a tertiary alkyl group. Primene.TM. 81R (a
primary aliphatic amine in which the amino nitrogen atom is linked
to a tertiary carbon with C.sub.12-14 highly branched alkyl groups)
and Primene.TM. JMT (a primary aliphatic amine in which the amino
nitrogen atom is linked to a tertiary carbon with C.sub.16-22
highly branched alkyl groups) amines are commercially available
amines that fall into this category.
[0041] The amines are preferably used in the form of salts with
acid phosphates, which are effective as antirust and antiwear
agents. The salts of the phosphates and amines may for instance be
formed prior to addition to the additive package or they may be
formed in situ after the acid phosphate and amine is added to the
package.
[0042] The amine derivatives of the mono-or dialkyl acid phosphate
provide valuable antiwear functionality and should be chosen to be
soluble in the selected base oil of the grease. The amines may be
of the types described above with preference given to the tertiary
amines such as e.g. Primene.TM. 81-R; (Primene.TM. JM-T) or
Primene.TM. TOA (a primary aliphatic amine in which the amino
nitrogen atom is linked to a tertiary carbon with C.sub.8 alkyl
groups).
[0043] Preferred mono- and/or dialkyl-acid phosphate antiwear
additives include at least one acid phosphate moiety derived from a
phosphoric acid represented by the formula
R.sub.1O(R.sub.2O)P(O)OH, where R.sub.1 is hydrogen or hydrocarbyl
and R.sub.2 is hydrocarbyl. R.sub.1 and R.sub.2 may be the same or
different, typically from 10 to 20 carbon atoms and preferably 10
to 12 carbon atoms.
[0044] The preferred hydrocarbyl groups for R.sub.1 (if present)
and R.sub.2 are independently selected from C.sub.1-C.sub.30
hydrocarbyls, preferably C.sub.3-C.sub.20 alkyl, alkenyl, or
aryl-containing hydrocarbyls, which may be straight chain, branched
or cyclic, and may also contain heteroatoms such as O, S, or N.
Suitable hydrocarbyl groups are alkyls of 1-40 carbon atoms,
preferably 2-20 carbon atoms, more preferably 3-20 carbon atoms,
alkenyls of 1-20 carbon atoms, cycloalkyls of 5-20 carbon atoms,
aryls of 6-12 carbon atoms, alkaryls of 7-20 carbon atoms or
aralkyls of 7-20 carbon atoms. Examples of suitable alkyl groups
are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,
nonyl, decyl, methyl-decyl or dimethyl-decyl. Examples of suitable
alkenyl groups are ethenyl, propenyl, butenyl, pentenyl or hexenyl.
Examples of suitable cycloalkyl groups are cyclohexyl or
methylcyclohexyl. Examples of suitable cycloalkenyl groups are 1-,
2-, or 3-cyclohexenyl or 4-methyl-2-cyclohexenyl. Examples of
suitable aryl groups are phenyl or diphenyl. Examples of suitable
alkaryl groups are 4-methyl-phenyl (p-tolyl) or p-ethyl-phenyl.
Examples of suitable aralkyl groups are benzyl or phenethyl. It is
possible to use a variety of acid phosphates, for example, one
where R.sub.2 is an aryl group, and the other where R.sub.2 is an
alkyl group like hexyl. The hydrocarbyl groups are typically
selected from ethyl, iso-propyl, n-butyl, i-amyl, hexyl, 2-ethyl
hexyl, n-octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl,
hexadecyl, octadecyl, oleyl, linoleyl, linolenyl, phytol, myricyl,
lauryl, myristyl, cetyl, stearyl, amyl phenol, nonyl phenol,
methylcyclohexanol, alkylated napthol.
[0045] The acid phosphate esters for reaction with the amines may
be conveniently formed by reaction of the corresponding alcohols,
in the proper stoichiometric amounts, with phosphoric acid, to make
the desired mono- or dialkyl phosphate. The preferred acid
phosphates are selected from mono- and di-2-ethylhexyl acid
phosphate, and mixtures of the two. Further description of useful
amine phosphates is in US 2006/0223720 to which reference is made
for a description of them.
[0046] The imidazolines which are useful as corrosion inhibitors
are imidazolines with a long chain (C.sub.8-C.sub.20) alkyl,
alkenyl or substituted alkyl or alkenyl substituent on one or both
nitrogen atoms. A shorter chain substituent may be on the second
nitrogen atom and this may be an alkyl group or substituted alkyl
group. Exemplary useful imidazolines include 2-oleyl imidazoline,
1-hydroxyethyl-2-oleyl imidazoline and similar compounds.
[0047] Another useful class of corrosion inhibitors are the
thiadiazoles, which are especially effective against copper
corrosion. Preferably, the thiadiazole comprises at least one of
2,5-dimercapto-1,3,4-thiadiazole;
2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles;
2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles;
2,5-bis(hydrocarbylthio)- and
2,5-bis(hydrocarbyldithio)-1,3,4-thiadiazoles. The more preferred
compounds are the 1,3,4-thiadiazoles, especially the
2-hydrocarbyldithio-5-mercapto-1,3,4-dithiadiazoles and the
2,5-bis(hydrocaroyldithio)-1,3,4-thiadiazoles, a number of which
are available commercially from Afton Corporation as Hitec.RTM.
4313 or from Lubrizol Corporation as Lubrizol.RTM. 5955A.
[0048] Copper passivators include thiazoles, triazoles, and
thiadizoles such as 2-mercapto-1,3,4-thiadiazole,
2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles,
2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles,
2,5-bis-(hydrocarbylthio)-1,3,4-thiadiazoles, and
2,5-bis-(hydrocarbyldithio)-1,3,4-thiadiazoles. The imidazolines
described above may also be suitable for providing copper
passivation functionality.
[0049] The use of anti-wear/extreme pressure agents is favored in
the present formulations in view of the severe loadings encountered
in wind turbine bearings. Anti-wear and/or extreme pressure agents
can be incorporated, typically in an amount from 0.1 to 5 wt %,
more usually 0.5 to 2 wt %. Examples of anti-wear/extreme pressure
agents include metal-free sulfur-containing species including
sulfurized olefins, dialkyl polysulfides, diarylpolysulfides,
sulfurized fats and oils, sulfurized fatty acid esters,
phosphosulfur compounds, trithiones, sulfurized oligomers of
C.sub.2-C.sub.8 monoolefins, sulfurized terpenes, thiocarbamate
compounds e.g. metal or ash-free dithiocarbamates such as methylene
bis(dibutyldithiocarbamate) or zinc dipentyldithiocarbamate;
thiocarbonate compounds, sulfoxides, thiol sulfinates. Other
examples include aryl phosphates and phosphites, thiophosphoric
acid compounds e.g. zinc dialkyldithiophosphates metal-free
phosphorus-containing additives such as esters of phosphorus acids,
amine salts of phosphorus acids and phosphorus acid-esters, and
partial and total thio analogs of these, for example, acid
phosphate anti-wear agents, of the formula
R.sub.1O(R.sub.2O)P(O)OH, where R.sub.1 is hydrogen or hydrocarbyl
and R.sub.2 is hydrocarbyl.
[0050] Additive functionality may optionally be provided by
multifunctional additives: antiwear agents, for example, will often
provide EP activity; zinc diamyldithiocarbamate, for example, may
be used as an oxidation inhibitor and metal deactivator with copper
corrosion inhibition. Commercially available blends such as zinc
dipentyldithiocarbamate with sulfurized isobutylenes may provide
effective EP/antioxidant activity and the blend of methylene
bis(dibutyldithiocarbamate) with tolutriazole derivative, is an
ashless antioxidant which also exhibits extreme pressure
performance alone or in combination with other additives.
[0051] Further examples of antiwear/EP agents and other additives
are found in US 2007/0289897, to which reference is made for
descriptions of them and exemplary methods for their
preparation.
[0052] As noted above, the present grease formulations are
characterized by a combination of properties including excellent
water washout as measured by ASTM D 1264, low oil separation as
measured by ASTM D 6184 as well as good low temperature properties
including low starting torque as measured by ASTM D 1478 and the
important property of corrosion resistance as measured by ASTM D
1743. Water washout (D 1264) is typically not more than 15% and in
favorable cases less than 10%, e.g. less than 8 or even 6%; wet
Shell roll (ASTM D 7342-2 (Procedure B) 10% DI at room temperature)
may even show a negative change in penetration, i.e. become firmer
after working. The oil separation is typically less than 8% and may
be less than 5% and even less than 3 or 2%. The low temperature
properties are also notable: in the Low-Temperature Torque test
(ASTM D 1478), the starting torque (-40.degree. C.) may be not more
than 5,000 g-cm and typically is not more than 4,000 g-cms with
values below 3,000 g-cms. being achievable; values at -30.degree.
C. are correspondingly better with a maximum of 2,000 g-cms,
typically not more than 1500 g-cms.
[0053] A further advantage of the present formulations is that the
greases are able to pass the Riffel Test (standard conditions),
achieving a maximum scar depth of less than 10 microns (with up to
20 microns permitted in the region of salt water injection provided
that the average is less than 2 microns), an average scare depth of
less than 3 microns and corrosion less than or equal to a rating of
2. The Riffel Test (or Ripple Test) is a test developed by the IME,
the German Institut fur Mechanischenelemente und
Mechanischengestaltung of Aachen (DE); the test can be carried out
on request at the IME.
[0054] The following are examples of the present disclosure and are
not to be construed as limiting.
EXAMPLES
Example 1
[0055] Evaluations of the effect of a polyamide thixotrope on
grease performance were conducted using an additive-free lithium
complex grease.
[0056] A series of grease formulations were made up using an ISO VG
220 PAO as the base oil with a lithium complex thickener and
varying amounts of a water-/oil-insoluble polyamide co-thickener
(from decanoic acid/12-hydroxystearic acid/ethylene diamine). The
polyamide, when used, was added to the contactor during the
thickener reaction at 188.degree. C. in amounts of 0.5, 1.00 and
1.50 wt %, based on the weight of the base grease.
[0057] The test results of the greases are shown in Table 1 below
and in FIGS. 1 and 2 for the water wash out and cone bleed (oil
separation). The results show that the addition of the polyamide is
effective to reduce oil separation and water wash out indicating
good grease structural retention and excellent water washout: a
value of 10-15 is conventionally considered acceptable for ASTM
D1264.
TABLE-US-00001 TABLE 1 Effect of Polyamide Thixotrope Polyamide,
FM, Penetration Cone Bleed Drop Pt. Washout wt. % % 60X 100X D6184
D2265 D1264 0 9.32 301 304 4.8 -- 36.3 0.50 11.15 280 290 2.8 305
13.5 1.00 11.21 265 303 2.1 306 2.5 3.00 10.09 286 342 0.84 262
6.6
Example 2
[0058] ISO 460 grease formulations were prepared using a PAO blend
base oil (6/150 cSt) and the same lithium complex thickener as in
Example 1. A standard antioxidant/corrosion-rust inhibitor package
(4.10 wt. %) containing an amine phosphate and an alkyl imidazoline
as corrosion inhibitors was used. To this basic grease formulation,
the same thixotropic additive as in Example 1 was added to the
finishing kettle in amounts of 0.5, 1.0 and 3.0 weight percent
based on the total weight of the grease formulation. The four
greases were subjected to the performance testing with the results
in Table 2 below.
TABLE-US-00002 TABLE 2 Polyamide Greases Polyamide, wt. % 0.0 0.5
0.95 3.0 Thickener, wt % 13 13 13 13 Test Units Results
Penetration, U/W mm/10 281/283 292/283 315/312 255/252
Mechanical/Structural CGOR wt % Bleed (1) wt % 3.8 3.8 3.9 2.9 CGOR
1/2 Scale Pen mm/10 145 154 157 138 Change in Penetration mm/10 28
24 14 22 Water Resistance Water Washout, wt % 71.6 1.4 8.7 6.6
79.degree. C. (2) Wet Roll (3) 1/2 Scale Penetration mm/10 142 145
152 118 After Change in Penetration mm/10 22 6 2 -10 Wet Extended
Penetration (4) Penetration After mm/10 339 335 339 297 Change in
Penetration mm/10 56 52 2.7 45 Change in Penetration % 19.8 18.4
8.6 17.8 Water Spray Resistance (5) Low Temperature USS Mobility
g/min 9.9 10.2 13.7 4.85 @ -18.degree. C. Notes: (1) Churned Grease
Oil Release, internal dynamic bleed test (2) ASTM D 1264 (3) 10% DI
@ RT, ASTM D7342-2 (Proc. B) (4) (10% DI, 100Kx) ASTM D7342-2
(Proc. A) (5) ASTM D 4049
Example 3
[0059] This example compares a commercial ISO 460 grease using a
synthetic hydrocarbon (SHC) with a comparison ISO 460 grease
containing the same polyamide thixotrope as in Example 2 added to a
batch contactor/finishing kettle; this grease also contained an
amine phosphate/imidazoline antiwear package. The polyamide
co-thickener was added to the new grease formulation in an amount
of 0.83 wt %. The performance of the two formulations was then
tested and the results are shown in Table 3 below.
TABLE-US-00003 TABLE 3 ISO 460 ISO 460 Grease + Grease Units Grease
Polyamide Structural Stability Unworked Penetration (1) mm/10 315
294 60X Worked Penetration (1) mm/10 310 298 100K X Worked
Penetration (1) mm/10 345 305 Change in worked pen, 60x to 100Kx
mm/10 35 7 Change in worked pen, 60x to 100Kx % 11.3 2.3 High
Temperature & Oil Bleed Pressure Bleed, 168 hrs @ 80.degree. C.
(2) % 9.4 5.7 Water Resistance Water Washout (3) % 7.4 3.3 Wet
Extended Penetration (4) Pen before 311 298 Pen after 342 309
Change in Pen mm/10 31 11 Change in Pen % 9.97 3.69 Wet Shell Roll
(5) 1/2 scale pen before 155 144 1/2 scale pen after 163 137 Change
in Pen(full scale) mm/10 16 -14 Change in Pen (full scale) % 5.1
-4.8 Low-Temperature (6) Low Temp. Torque @ -40.degree. C. Starting
g cm 10700 2860 Running g cm 3480 676 Low Temp. Torque @
-30.degree. C. Starting g cm 3130 1300 Running g cm 738 202 USS
Mobility @ -18.degree. C. g/min 4.9 18.46 Corrosion EMCOR, 10% SSW
(7) rating 0, 2/2 0, 0 Notes: (1) ASTM D-217 (2) IP121 (3) ASTM
D1264, 79.degree. C. (4) ASTM D7342 - Proc. A, 100Kx (10% DI) (5)
ASTM D7342 - Proc. B, (10% DI) (6) ASTM D1478 (7) ASTM D6138
Example 4
[0060] Two ISO 460 greases were prepared in a batch mode in a mini
contactor/kettle, both using a 6/150 cSt PAO blend and the same
lithium complex thickener system as in previous examples and the
same additive package as in Example 2 with the exception that the
grease with added polyamide (1.0 wt %), the amount of imidazoline
in the corrosion inhibitor was reduced from 0.5 to 0.2 wt %. The
two formulations were tested in the Riffel Test under standard
conditions with the following results showing acceptable ripple
(false brinelling) and corrosion resistance in spite of the lower
level of inhibitor.
TABLE-US-00004 TABLE 4 IME ISO 460 Test ISO 460 Grease with Riffel
Test Limits Units Grease Polyamide Max Scar <10 micron 3.33 4.4
Mean Scar <3 micron 0.49 1 Corrosion .ltoreq.3 rating 1.5 2
[0061] Applicants have attempted to disclose all embodiments and
applications of the disclosed subject matter that could be
reasonably foreseen. However, there may be unforeseeable,
insubstantial modifications that remain as equivalents. While the
present invention has been described in conjunction with specific,
exemplary embodiments thereof, it is evident that many alterations,
modifications, and variations will be apparent to those skilled in
the art in light of the foregoing description without departing
from the spirit or scope of the present disclosure. Accordingly,
the present disclosure is intended to embrace all such alterations,
modifications, and variations of the above detailed
description.
[0062] All patents, test procedures, and other documents cited
herein, including priority documents, are fully incorporated by
reference to the extent such disclosure is not inconsistent with
this invention and for all jurisdictions in which such
incorporation is permitted.
[0063] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated.
* * * * *