U.S. patent application number 15/522453 was filed with the patent office on 2017-12-21 for grease compositions.
The applicant listed for this patent is Aktiebolaget SKF. Invention is credited to Frank Fiddelaers, Eustathios Ioannides.
Application Number | 20170362527 15/522453 |
Document ID | / |
Family ID | 52118525 |
Filed Date | 2017-12-21 |
United States Patent
Application |
20170362527 |
Kind Code |
A1 |
Fiddelaers; Frank ; et
al. |
December 21, 2017 |
GREASE COMPOSITIONS
Abstract
The invention relates to a grease composition having a base oil
and a thickener that includes hydrophilic metal oxide particles and
one or more amines that contain one or more unsaturated C--C bonds
and/or at least one OH group. The hydrophilic metal oxide particles
have a BET specific surface area of at least 10 m.sup.2/g and at
least 80% of the hydrophilic metal oxide particles have a particle
size in the range of from 5 nm to 900 .mu.m. The amount of the
thickener is in the range of from 0.1-40% by weight, based on the
total weight of the grease composition. The invention further
relates to methods for manufacturing the grease composition, and
the use of the grease composition for lubricating bearings, gears
and couplings.
Inventors: |
Fiddelaers; Frank;
(Gorinchem, NL) ; Ioannides; Eustathios; (London,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Aktiebolaget SKF |
Goteborg |
|
BE |
|
|
Family ID: |
52118525 |
Appl. No.: |
15/522453 |
Filed: |
October 30, 2015 |
PCT Filed: |
October 30, 2015 |
PCT NO: |
PCT/EP2015/075248 |
371 Date: |
April 27, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 123/02 20130101;
C10N 2050/10 20130101; C10M 2207/1256 20130101; C10M 2215/08
20130101; C10N 2030/06 20130101; C10M 2223/041 20130101; C10M
101/00 20130101; C10M 2227/006 20130101; C10M 133/06 20130101; C10M
2215/026 20130101; C10N 2040/04 20130101; C10M 2215/042 20130101;
C10M 2227/06 20130101; C10M 2215/30 20130101; C10N 2020/06
20130101; C10M 169/00 20130101; C10M 2201/0626 20130101; C10M
2219/082 20130101; C10M 2201/1056 20130101; C10M 2203/003 20130101;
C10N 2040/02 20130101; C10M 113/16 20130101; C10M 2215/04 20130101;
C10M 2215/26 20130101 |
International
Class: |
C10M 113/16 20060101
C10M113/16; C10M 169/00 20060101 C10M169/00; C10M 101/00 20060101
C10M101/00; C10M 133/06 20060101 C10M133/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2014 |
GB |
1419439.3 |
Claims
1. A grease composition comprising: a base oil, and a thickener
that provides hydrophilic metal oxide particles and one or more
amines that contain one or more unsaturated C--C bonds and/or at
least one OH group, wherein the hydrophilic metal oxide particles
have a BET specific surface area of at least 10 m.sup.2/g and at
least 80% of the hydrophilic metal oxide particles have a particle
size in the range of from 5 nm to 900 .mu.m, and wherein the amount
of the thickener is in the range of from 0.1-40% by weight, based
on the total weight of the grease composition.
2. The grease composition according to claim 1, wherein the one or
more amines are fatty acid amines.
3. The grease composition according to claim 1, wherein the amine
in addition contains one or more unsaturated C--C bonds and at
least one OH group.
4. The grease composition according to claim 1, wherein the one or
more amines contain two or more unsaturated C--C bonds.
5. The grease composition according to claim 1, wherein the one or
more amines are metal salts.
6. The grease composition according to claim 1, wherein the
thickener further comprises one or more metal salts of fatty acids,
one or more fatty acids, one or more esters and/or one or more
amides.
7. The grease composition according to claim 6, wherein the
thickener further comprises one or more metal salts of fatty
acids.
8. The grease composition according to claim 6, wherein the one or
more metal salts of fatty acids, one or more fatty acids, one or
more esters and/or one or more amides contain one or more
unsaturated C--C bonds and/or at least one OH group.
9. The grease composition according to claim 1, further comprising
one or more metal sulphonates, metal sulphates, metal phosphates
and/or metal phosphonates.
10. The grease composition according to claim 1, wherein the
hydrophilic metal oxide are silicon oxide particles.
11. The grease composition according to claim 10, wherein the
silicon oxide is amorphous fumed silicon oxide.
12. A method for manufacturing a grease composition having a base
oil, and a thickener that provides hydrophilic metal oxide
particles and one or more amines that contain one or more
unsaturated C--C bonds and/or at least one OH group, wherein the
hydrophilic metal oxide particles have a BET specific surface area
of at least 10 m.sup.2/g and at least 80% of the hydrophilic metal
oxide particles have a particle size in the range of from 5 nm to
900 .mu.m, and wherein the amount of the thickener is in the range
of from 0.1-40% by weight, based on the total weight of the grease
composition, the method comprises: mixing the base oil, the
hydrophilic metal oxide particles and the one or more amines that
contain one or more unsaturated C--C bonds and/or at least one OH
group in any possible order of sequence, and subjecting before or
after mixing the hydrophilic metal oxide particles, the one or more
amines that contain one or more unsaturated C--C bonds and/or at
least one OH group, or a mixture thereof, to a mechanical
treatment, a thermal treatment or to both a mechanical treatment
and a thermal treatment.
13. A grease composition having a base oil, and a thickener that
provides hydrophilic metal oxide particles and one or more amines
that contain one or more unsaturated C--C bonds and/or at least one
OH group, wherein the hydrophilic metal oxide particles have a BET
specific surface area of at least 10 m.sup.2/g and at least 80% of
the hydrophilic metal oxide particles have a particle size in the
range of from 5 nm to 900 .mu.m, and wherein the amount of the
thickener is in the range of from 0.1-40% by weight, based on the
total weight of the grease composition used for lubricating a
bearing, a gearing or a coupling.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to grease compositions,
methods for manufacturing the grease compositions, and the use of
the grease compositions for lubricating bearings, gears and
couplings.
BACKGROUND OF THE INVENTION
[0002] Grease compositions are widely used for lubricating bearings
and other structural components. A grease is an essential product
to reduce, for example, wear, friction, running temperatures and
energy losses. Greases are materials which comprise a base oil that
is thickened with a metal soap, and they are usually prepared by
reacting a metal hydroxide with a fatty acid in the presence of the
base oil. Conventional metal soap greases require an energy
intensive grease cooking and milling process in order to achieve
proper thermo-mechanical stability. Conventional metal soap greases
can still be sensitive to poor thermo-mechanical stability and can
require additional treatments. It is known to improve further the
stability, and thus the lubricating capacity, of conventional
greases by adding solid additives during the thickening process.
Examples of such solid additives are, for example, molybdenum
disulfide, graphite, zinc oxide and/or a silica gel. The process of
grease cooking and milling and additional treatments is relatively
expensive because it is carried out at an elevated temperature and
over a relatively long period of time. Moreover, the greases so
prepared are still unsuitable for a variety of applications, and
not all conventional greases are suitable for food and beverage
processing applications.
[0003] Consequently, there is a need for greases which can easily
be manufactured at low costs, which are stable and show highly
attractive lubricating properties in terms of low friction
performance. In addition, there is a need for greases that are
biodegradable, environmentally benign and food compatible.
SUMMARY OF THE INVENTION
[0004] Object of the present invention is to provide grease
compositions which show excellent lubricating properties such as
grease life performance, corrosion wear and thermo and mechanical
stability, and which can easily be manufactured at low costs and/or
are more environmentally friendly. Surprisingly, it has now been
found that this can be established when use is made of a base oil
and a thickener which comprises hydrophilic metal oxide particles
and a particular amine.
[0005] Accordingly, the present invention relates to a grease
composition comprising a base oil and a thickener which comprises
hydrophilic metal oxide particles and one or more amines that
contain one or more unsaturated C--C bonds and/or at least one OH
group; wherein the hydrophilic metal oxide particles have a BET
specific surface area of at least 10 m2/g and at least 80% of the
hydrophilic metal oxide particles have a particle size in the range
of from 5 nm to 900 .mu.m, and wherein the amount of the thickener
is in the range of from 0.1-40% by weight, based on the total
weight of the grease composition.
[0006] Suitably, the thickener comprises in addition one or more
metal salts such as metal sulphonates, metal sulphates, metal
phosphates and/or metal phosphonates.
[0007] In particular, the present invention relates to a grease
composition comprising a base oil and a thickener which comprises
hydrophilic metal oxide particles and one or more amines that
contain one or more unsaturated C--C bonds; wherein the hydrophilic
metal oxide particles have a BET specific surface area of at least
10 m2/g and at least 80% of the hydrophilic metal oxide particles
have a particle size in the range of from 5 nm to 900 .mu.m, and
wherein the amount of the thickener is in the range of from 0.1-40%
by weight, based on the total weight of the grease composition.
[0008] In particular, the present invention relates to a grease
composition comprising a base oil and a thickener which comprises
hydrophilic metal oxide particles and one or more amines that
contain at least one OH group; wherein the hydrophilic metal oxide
particles have a BET specific surface area of at least 10 m2/g and
at least 80% of the hydrophilic metal oxide particles have a
particle size in the range of from 5 nm to 900 .mu.m, and wherein
the amount of the thickener is in the range of from 0.1-40% by
weight, based on the total weight of the grease composition.
[0009] In particular, the present invention relates to a grease
composition comprising a base oil and a thickener which comprises
hydrophilic metal oxide particles and one or more amines that
contain one or more unsaturated C--C bonds and at least one OH
group; wherein the hydrophilic metal oxide particles have a BET
specific surface area of at least 10 m2/g and at least 80% of the
hydrophilic metal oxide particles have a particle size in the range
of from 5 nm to 900 .mu.m, and wherein the amount of the thickener
is in the range of from 0.1-40% by weight, based on the total
weight of the grease composition.
[0010] The grease compositions according to the present invention
show an attractive low friction performance, whereas at the same
time they can easily be manufactured at low costs and/or are more
environmental friendly.
BRIEF DESCRIPTION OF THE DRAWING
[0011] The invention will now be described with reference to the
attached drawing, showing some non-limiting exemplary embodiments
of the invention, in which:
[0012] FIG. 1 is a chart showing the results of the test sample
where the values of the Stribeck friction coefficient and the
entrainment speed [mms-1] measurements obtained on the MTM rig are
shown
DETAILED DESCRIPTION OF THE INVENTION
[0013] The thickener to be used in the present grease composition
according to the present invention comprises one or more amines
that contain one or more unsaturated C--C bonds and/or at least one
OH group.
[0014] Preferably, the one or more amines are fatty acid amines. In
the context of the present application fatty acid amines are
defined as amines derived from fatty acids. It will be understood
that fatty acids are aliphatic monocarboxylic acids derived from,
or contained in esterified form in an animal or vegetable fat, oil
or wax. In accordance with the present invention use can be made of
natural and synthetic fatty acids. Suitably, the amine to be used
in accordance with the present invention is a fatty acid that
contains one or more unsaturated C--C bonds in which a NH2 group is
introduced somewhere in the unsaturated fatty acid chain.
[0015] Primary, secondary, tertiary and cyclic amines exist.
Organic amines include amino acids, trimethylamine, aniline and
biogenic amines. Fatty amines have an amine attached to a
hydrocarbon chain and the amines form part of oleochemical
functional groups that are derived from plant and animal fats.
[0016] Several methods to make the amines to be used in accordance
with the present invention are available. Amino acids are widely
represented in biology and organic chemistry. The amino acid
comprises functional groups of amine(s) and carboxylic acids. In
biology the breakdown of amino acids forms amines. Many industrial
and laboratory methods exist to form amines and many more methods
to form different amines in combination with various starting amine
ingredients and catalysts.
[0017] Amines can for instance be formed from ammonia in an
alkylation reaction with alcohol in the presence of ammonia and in
the presence of catalysts. Hydrogenation reduces nitriles to amines
in the presence of a catalyst. Reaction of haloalkanes with ammonia
and amines forms different type of amines. Lithiumaluminiumhydride
can be used to reduce amides to amines. Many amines are produced
from aldehydes and ketones via reductive amination, which can
either proceed catalytically or stoichiometrically. Ammonium salts
which can provide beneficial effects to the grease composition of
the present invention can be formed from amines and halocarbons.
The amines may also be formed by the hydrolysis of alkyl
isocyanate, or by degradation of the acid amide with aid of
hypochlorite, hypobromite, halogen, or in combination with a base,
or the conversion of the corresponding acid azide with aid of an
acid chloride with sodium azide resulting in amine hydrochloride,
or reduction of a cyanide or of acid amide.
[0018] Commonly applied amines can originate from saturated and
unsaturated fatty acids like lauric acid, myristic acid, palmitic
acid, stearic acid, arachidic acid, behenic acid, lignoceric acid,
lauroleic acid, myristoleic acid, palmitoleic acid, gadoleic acid,
erucic acid, ricinoleic acid, linoleic acid, linolenic acid,
eleostearic acid, arachidonic acid, phenylstearylamine and
clupanodic acid. The amines of the foregoing acids may be obtained
by transformation to the acid amide followed by reduction with
sodium in absolute alcohol. Other sources of mixed amines are known
to the art.
[0019] The unsaturated fatty amines to be used in accordance with
the presented invention can be prepared from ammonia of which one
or two hydrogens are substituted by hydrocarbon chain of a length
from 18 C-atom or more and having 1 to 3 unsaturated carbon bonds.
Commercial unsaturated fatty amines are blends of fatty amine of
various hydrocarbon chain length and comprising of 1 to 3
unsaturated carbon bonds. These blended compositions can have
various wt. % of unsaturated fatty amines. These mixed fatty amines
can be further processed to obtain the desired quantity of
unsaturated amines and to control these amounts by applied
processing techniques of decanting, steam distillation or other
processing techniques. Examples of unsaturated fatty amines are
oleylamine, linoleylamine, linolenylamine, arachidylamine,
eleostearylamine, erucylamine, petroselenylamine, and
palmitoleylamine.
[0020] The fatty acid from which the fatty amine can suitably be
prepared comprises 2-24 carbon atoms. A suitable example is for
instance oleic amine. Suitably, the amines are metal salts. When
the amines are metal salts, the amount of metal (salt(s) is in the
range of from 0.1-40% by weight, based on the total weight of the
grease composition.
[0021] Suitably, the amines to be used in accordance with the
present invention contain one or more unsaturated C--C bonds and/or
at least one OH group. Suitably, the amines to be used in
accordance with the present invention contain one or more
unsaturated C--C bonds and at least one OH group. Suitably, the
amines contain two or more unsaturated C--C bonds. Suitably, the
amines contain two or more unsaturated C--C bonds and at least one
OH group, preferably at least two OH groups.
[0022] Suitably, the unsaturated amines further include at least
one OH-group. Suitable examples of such amines are ethyl hydroxy
stearamine and bishydroxyethyl oleylamine, and diamines such as
bishydroxyethyl oleylamine. Suitably, the one or more amines are
fatty acid amines. The one or more unsaturated amines may suitably
in addition contain at least one OH group, suitably at least two OH
groups. Suitably, the one or more amines contain two or more
unsaturated C--C bonds and at least one OH group. Suitably, the one
or more amines are metal salts. The amines may contain an ester
group.
[0023] The metal in the metal salts is preferably an alkali metal
or an alkaline earth metal of Groups 1 and 2 of the Periodic System
of Elements, and bismuth. Suitable examples of metals include
lithium, potassium, sodium, calcium, aluminium, rubidium, cesium,
francium, beryllium, strontium, barium, radium, bismuth and
magnesium. In addition it is noted that the metal in the metal salt
to be used can be a semi-metal such as borium. According to a
preferred embodiment according to the present invention, the metal
is an alkaline earth metal, most preferably calcium.
[0024] The thickener to be used in accordance with the present
invention may in addition contain one or more metal salts of fatty
acids.
[0025] The present invention therefore further relates to a grease
composition comprising a base oil and a thickener which comprises a
hydroxyl group containing metal compound, one or more amines that
contain one or more unsaturated C--C bonds and/or at least one OH
group and one or more metal salts of fatty acids.
[0026] The present invention therefore preferably relates to a
grease composition comprising a base oil and a thickener which
comprises hydrophilic metal oxide particles, one or more amines
that contain one or more unsaturated C--C bonds and/or at least one
OH group and one or more metal salts of fatty acids, wherein the
hydrophilic metal oxide particles have a BET specific surface area
of at least 10 m2/g and at least 80% of the hydrophilic metal oxide
particles have a particle size in the range of from 5 nm to 900
.mu.m, and wherein the amount of the thickener is in the range of
from 0.1-40% by weight, based on the total weight of the grease
composition.
[0027] Suitable metal salts of fatty acids include metals salts of
caprylic acid, pelargonic acid, capric acid, lauric acid, linderic
acid, rayristic acid, tsuzuic acid, physetoleic acid, myristoleic
acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric
acid, stearic acid, 12-hydroxystearic acid, petroselinic acid,
oleic acid, elaidic acid, vaccenic acid, linolic acid, linolenic
acid, elaeostearic acid, tuberculostearic acid, arachidic acid,
eicosadienic acid, eicosatrienic acid, arachidonic acid, behenic
acid, lignoceric acid, nervonic acid, hexadocosanic acid,
octadocosanic acid and erucic acid.
[0028] The one or more metal salts of fatty acids may be metal
salts of different fatty acids. When use is made of two metal salts
of different acids the first metal and the second metal may be the
same metal or they may differ from each other. In another
embodiment wherein use is made of two metal salts of fatty acids,
the fatty acid of the first metal salt and the fatty acid of the
second metal salt may be the same fatty acid or they may differ
from each other. When two different metal salts of fatty acids are
used, the at least first and second metals will not be the same
metal when the fatty acid of the first metal salt and the fatty
acid of the second metal salt are the same fatty acids, and vice
versa. Suitably, the fatty acid of the first metal salt and the
fatty acid of the second metal salt comprise a different number of
carbon atoms. Preferably, the fatty acid of the first metal
comprises 2-16 carbon atoms and the fatty acid of the second metal
salt comprises 20-24 carbon atoms. Suitably, the fatty acid of the
first metal salt is butyric acid, caproic acid, caprylic acid,
capric acid, lauric acid, myristic acid or palmitic acid,
preferably caproic acid or caprylic acid. Suitably, the fatty acid
of the second metal salt is arachidic acid, behenic acid or
lignoceric acid. Such a grease composition is particularly
attractive in low speed applications such as mining and cement
applications. Preferably, the thickener includes in addition to the
one or more amines a metal salt of stearic acid, 12-hydroxy stearic
acid and/or oleic acid. More preferably, the metal salt is
12-hydroxy stearic acid, preferably in combination with a metal
salt of stearic acid and/or a metal salt of oleic acid. The
thickener may apart from the one or more metal salts of fatty acids
also contain one or more fatty acids. Preferably, the thickener
contains in addition a metal salt of 12-hydroxy stearic acid,
stearic acid or oleic acid also 12-stearic acid, stearic acid or
oleic acid. The metal salts of fatty acids may contain an OH group,
amine group and/or ester group.
[0029] The present invention preferably relates to a grease
composition comprising a base oil and a thickener which comprises
hydrophilic metal oxide particles, one or more amines that contain
one or more unsaturated C--C bonds and/or at least one OH group and
one or more fatty acids, wherein the hydrophilic metal oxide
particles have a BET specific surface area of at least 10 m2/g and
at least 80% of the hydrophilic metal oxide particles have a
particle size in the range of from 5 nm to 900 .mu.m, and wherein
the amount of the thickener in the range of from 0.1-40% by weight,
based on the total weight of the grease composition.
[0030] Suitably, the thickener comprises in addition one or more
metal salts such as metal sulphonates, metal sulphates, metal
phosphates and/or metal phosphonates.
[0031] Suitable fatty acids that can be used include caprylic acid,
pelargonic acid, capric acid, lauric acid, linderic acid, rayristic
acid, tsuzuic acid, physetoleic acid, myristoleic acid,
pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid,
stearic acid, 12-hydroxystearic acid, petroselinic acid, oleic
acid, elaidic acid, vaccenic acid, linolic acid, linolenic acid,
elaeostearic acid, tuberculostearic acid, arachidic acid,
eicosadienic acid, eicosatrienic acid, arachidonic acid, behenic
acid, lignoceric acid, nervonic acid, hexadocosanic acid,
octadocosanic acid and erucic acid.
[0032] When use is made of two or more different fatty acids the
fatty acids suitably comprise a different number of carbon atoms.
Preferably, a first fatty acid comprises 2-16 carbon atoms and a
second fatty acid comprises 20-24 carbon atoms. Suitably, the first
fatty acid is butyric acid, caproic acid, caprylic acid, capric
acid, lauric acid, myristic acid or palmitic acid, preferably
caproic acid or caprylic acid. Suitably, the second fatty acid is
arachidic acid, behenic acid or lignoceric acid. Such a grease
composition is particularly attractive in low speed applications
such as mining and cement applications. In another attractive
embodiment of the present invention, the grease composition
comprises two different fatty acids, wherein the fatty acids both
comprise 18 carbon atoms. Suitably, the two fatty acids are
selected from stearic acid, oleic acid and 12-hydroxy stearic acid.
Preferably, the first fatty acid is 12-hydroxy stearic acid and the
second fatty acid is stearic acid. The 12-hydroxy stearic acid will
be able to form covalent bonds with OH-groups (silanol) of
amorphous hydrophilic fumed silicon oxide resulting in a very
attractive performance of the grease composition in terms of
thermal mechanical stability.
[0033] When one or more metal salts of fatty acids and/or one or
fatty acids are present, preferably at least one metal salt of a
fatty acid or fatty contains one or more unsaturated C--C bonds and
at least one OH group.
[0034] The present invention also relates to a grease composition
comprising a base oil and a thickener which comprises hydrophilic
metal oxide particles, one or more amines that contain one or more
unsaturated C--C bonds and/or at least one OH group, and one or
more esters, wherein the hydrophilic metal oxide particles have a
BET specific surface area of at least 10 m2/g and at least 80% of
the hydrophilic metal oxide particles have a particle size in the
range of from 5 nm to 900 .mu.m, and wherein the amount of the
thickener is in the range of from 0.1-40% by weight, based on the
total weight of the grease composition.
[0035] The esters to be used suitably contain one or more
unsaturated C--C bonds and/or at least one OH group. Suitable
esters include unsaturated esters such as methyl oleate ester and
ethyl linoleate ester; saturated diesters such as dioctyl sebacate
ester, diisooctylsebacate ester and dioctyl adipate ester; and
OH-group containing esters such methyl-12-hydroxystearate ester
9-octadecenoic acid, 12 hydroxy methyl ester and hydroxy palmitic
ester. The diesters to be used may also contain one or more
unsaturated C--C bonds. The esters to be used in accordance with
the present invention include branched and unbranched esters.
Suitable esters include unbranched and branched alkylated
carboxylate esters, as well as triglycerides, in particularly
unsaturated triglycerides. Suitably, the one or more esters contain
one or more unsaturated C--C bonds. Preferably, the one or more
esters contain one or more unsaturated C--C bonds and at least one
OH group. Suitably, the one or more esters are diesters. Suitably,
the one or more esters contain two or more unsaturated C--C bonds.
Suitably, the one or more esters contain at least two OH groups.
Suitably, the one or more esters contain at least two unsaturated
C--C bonds and at least one OH group. Suitably, the one or more
esters contain at least two unsaturated C--C bonds and at least two
OH groups. Suitably, the one or more esters are metal salts. The
esters may containing an amine group and/or amide group. Suitably,
the thickener comprises in addition one or more sulphonates,
sulphates, phosphates and/or phosphonates. When the one or more
esters are metal salts, the amount of metal (salt(s) is in the
range of from 0.1-40% by weight, based on the total weight of the
grease composition.
[0036] The present invention in particular relates to a grease
composition comprising a base oil and a thickener which comprises
hydrophilic metal oxide particles, one or more amines that contain
one or more unsaturated C--C bonds and/or at least one OH group and
one or more amides, wherein the hydrophilic metal oxide particles
have a BET specific surface area of at least 10 m2/g and at least
80% of the hydrophilic metal oxide particles have a particle size
in the range of from 5 nm to 900 .mu.m, and wherein the amount of
the thickener is in the range of from 0.1-40% by weight, based on
the total weight of the grease composition.
[0037] Suitably, the thickener comprises in addition one or more
metal salts such as metal sulphonates, metal sulphates, metal
phosphates and/or metal phosphonates.
[0038] Suitably, the amides to be used in accordance with the
present invention contain one or more unsaturated C--C bonds and/or
at least one OH group. Suitably, the amides to be used in
accordance with the present invention contain one or more
unsaturated C--C bonds and at least one OH group. Suitably, the
amides contain one or more unsaturated C--C bonds and at least one
OH group. Suitably, the amides contain two or more unsaturated C--C
bonds. Suitably, the amides contain two or more unsaturated C--C
bonds and at least one OH group, preferably at least two OH groups.
The amides may contain an ester group.
[0039] Suitable amides that contain one or more unsaturated C--C
bonds include unsaturated amides such as oleamide and linoleamide;
diamides such as ethylene bis stearamide, hydroxy ethyl ethylene
bis oleamide, ethylene bis-12-hydroxystearamide and bishydroxethyl
oleylamine; and OH-group containing amides such as hydroxy ethyl
ethylene bis oleamide, ethylene bis-12-hydroxystearamide.
[0040] Preferably, the unsaturated amides are unsaturated fatty
acid amides, more preferably the amides are metal salts of
unsaturated fatty acid amides.
[0041] The present invention preferably provides a grease
composition comprising a base oil and a thickener which comprises
crystalline hydrophilic metal oxide particles, one or more amines
that contain one or more unsaturated C--C bonds and/or at least one
OH group, one or more metal salts of fatty acids, one or more fatty
acids, one or more esters and/or one or more amides, wherein the
hydrophilic metal oxide particles have a BET specific surface area
of at least 10 m2/g and at least 80% of the hydrophilic metal oxide
particles have a mean particle size of 5 nm to 900 .mu.m, and
wherein the amount of the thickener is 0.1-40% by weight, based on
the total weight of the grease composition. Suitably, the
additional one or more metal salts of fatty acids, one or more
fatty acids, one or more esters and/or one or more amides contain
one or more unsaturated C--C bonds and/or at least one OH group.
Preferably, the additional one or more metal salts of fatty acids,
one or more fatty acids, one or more esters and/or one or more
amides contain one or more unsaturated C--C bonds and at least one
OH group. The one or more metal salts of fatty acids, one or more
fatty acids, one or more esters and/or one or more amides may be
any of the fatty acids, fatty acids, esters and amines as described
hereinabove.
[0042] The present invention preferably provides a grease
composition comprising a base oil and a thickener which comprises
hydrophilic metal oxide particles, one or more metal sulphonates,
metal sulphates, metal phosphates and/or metal phosphonates, and
one or more amines that contain one or more unsaturated
carbon-carbon bonds and/or at least one OH group, wherein the
hydrophilic metal oxide particles have a BET specific surface area
of at least 10 m2/g and at least 80% of the hydrophilic metal oxide
particles have a mean particle size of 5 nm to 900 .mu.m, and
wherein the amount of the thickener is 0.1-40% by weight, based on
the total weight of the grease.
[0043] The grease compositions according to the present invention
are preferably non-hydroxide grease compositions. Non-hydroxide
grease compositions in accordance with the present invention do not
contain impurities such as excess amounts of hydroxide which are
normally present in greases that are prepared in conventional
lithium and calcium soap manufacturing processes. The non-hydroxide
grease compositions according to the present invention are suitably
substantially free of free hydroxide ions and/or metal hydroxide.
Preferably, the present non-hydroxide grease compositions contain
less than 0.2% by weight, and more preferably less than 0.1% by
weight of free hydroxide ions and/or metal hydroxide, based on the
total weight of the grease composition. Preferably, the present
non-hydroxide grease compositions are substantially free of free
hydroxide ions and/or metal hydroxide. Preferably, the present
grease compositions contain less than 0.2% by weight, and more
preferably less than 0.1% by weight of metal hydroxide, based on
the total weight of the grease composition. Most preferably, the
present non-hydroxide grease compositions are completely free of
metal hydroxide. It will be understood that OH-groups present on
the hydrophilic metal oxide particles or in an fatty acid such as
12-hydroxy stearate or the metal salt of such an fatty acid are not
to be considered free hydroxide ions since they are bonded to
silicon atoms or to a carbon atom of the fatty acid. The thickener
to be used in accordance with the present invention is suitably a
non-saponified thickener.
[0044] The present invention further provides a grease composition
comprising a base oil and a thickener which comprises hydrophilic
silicon oxide particles and one or more amines that contain one or
more unsaturated C--C bonds and/or at least one OH group, wherein
the hydrophilic silicon oxide particles have a BET specific surface
area of at least 10 m2/g and at least 80% of the hydrophilic
silicon oxide particles have a mean particle size of 5 nm to 900
.mu.m, and wherein the amount of the thickener is 0.1-40% by
weight, based on the total weight of the grease composition.
[0045] The present invention further provides a grease composition
comprising a base oil and a thickener which comprises hydrophilic
titanium oxide particles and/or hydrophilic aluminium oxide
particles and one or more amines that contain one or more
unsaturated C--C bonds and/or at least one OH group, wherein the
hydrophilic titanium oxide particles and/or hydrophilic aluminium
oxide particles have a BET specific surface area of at least 10
m2/g and at least 80% of the hydrophilic titanium oxide particles
and/or hydrophilic aluminium oxide particles have a mean particle
size of 5 nm to 900 .mu.m, and wherein the amount of the thickener
is 0.1-40% by weight, based on the total weight of the grease
composition.
[0046] The nature of the base oil to be used in accordance with the
present invention is not essential. The base oil may be selected
from the group consisting of mineral base oils and synthetic base
oils. Mineral base oils are derived from crude oils and are either
formulated on the basis of aromatic, paraffinic and/or naphthenic
base oils. Further, a wide range of synthetic base oils is known
and they include esters, poly-alpha-olefins, polysiloxanes and the
like.
[0047] The base oil to be used in accordance with the present
invention may comprise a base oil blend. Suitably, blends of
mineral base oils and synthetic base oils may be used. The base oil
in this invention is one which may ordinarily be used as the base
oil of a lubricating oil or as the base oil of a grease, and there
are no special restrictions. As examples mention may be made of
mineral oils, synthetic oils, animal and plant oils, and mixtures
thereof. In particular it is possible to use, singly or as
mixtures, base oils which belong to Group I, Group II, Group III,
Group IV and so on of the API (American Petroleum Institute) base
oil categories. Group I base oils include, for example, paraffinic
mineral oils obtained by a suitable combination of refining
processes such as solvent refining, hydrorefining, and dewaxing in
respect of lubricating oil-o fractions obtained by atmospheric
distillation of crude oil. Group II base oils include, for example,
paraffinic mineral oils obtained by a suitable combination of
refining processes such as hydrorefining and dewaxing in respect of
lubricating oil fractions obtained by atmospheric distillation of
crude oil. Group II base oils refined by hydrorefining methods such
as the Gulf Company method have a total sulphur content of less
than 10 ppm and an aromatic content of not more than 5% and so are
suitable for this invention. Group III base oils and Group 11+ base
oils include paraffinic mineral oils manufactured by a high degree
of hydrorefining in respect of lubricating oil fractions obtained
by atmospheric distillation of crude oil, base oils refined by the
Isodewax process which dewaxes and substitutes the wax produced by
the dewaxing process with isoparaffins, and base oils refined by
the Mobil wax isomerisation process. These too are suitable for use
in this invention. Concrete examples of synthetic oils include
polyolefins, polyoxyalkylene glycols such as polyethylene glycol or
polypropylene glycol, esters such as di-2-ethylhexyl sebacate or
di-2-ethylhexyl adipate, polyol esters such as trimethylolpropane
esters or pentaerythritol esters, perfluoroalkyl ethers, silicone
oils, polyphenyl ethers, and so on. The aforementioned polyolefins
include polymers of various olefins or hydrides thereof. Any olefin
may be used, and as examples mention may be made of ethylene,
propylene, butene and [alpha]-olefins with five or more carbons. In
the manufacture of polyolefins, one of the aforementioned olefins
may be used singly or two or more may be used in combination.
Particularly suitable are the polyolefins called
poly-[alpha]-olefins (PAO). These are base oils of Group IV. GTL
(gas to liquid) base oils synthesised by the Fischer-Tropsch method
of converting natural gas to liquid fuel have a very low sulphur
content and aromatic content compared with mineral oil base oils
refined from crude oil and have a very high paraffin constituent
ratio, and so have excellent oxidative stability, and because they
also have extremely small evaporation losses, they are suitable as
base oils for this invention. As typical examples of animal and
plant oils mention may be made of castor oil and rape-seed oil. The
various aforementioned oils may be used singly or in mixtures for
the base oil. The aforementioned examples are listed singly but the
invention is not limited thereby.
[0048] Preferably, the base oil or the base oil blend to be used in
accordance with the present invention has a kinematic viscosity in
the range of 1 to 60 000 cSt at a temperature of 40.degree. C.
according to DIN 51562/1. Suitable base oils include ISO VG 68, ISO
VG 46, ISO VG 32, ISO VG 22, ISO VG 15 and ISO VG 10 oils.
[0049] The hydrophilic metal oxide particles to be used in
accordance with the present invention can be derived from titanium
oxide, aluminium oxide and silicon oxide. Preferably, the
hydrophilic metal oxide particles are hydrophilic silicon oxide
particles. The metal oxide particles may be crystalline metal oxide
particles or amorphous metal oxide particles. Preferably, the
silicon oxide particles are amorphous silicon oxide particles. The
amorphous silicon oxide may contain various amounts of water,
implying that it may comprise silicic acid. In this respect it is
noted that silicic acid is a general name for a group of chemical
compounds, oligomers and polymers consisting of silicon, hydrogen,
and oxygen. According to a preferred embodiment of the present
invention, the amorphous silicon oxide particles are derived from
an amorphous hydrophilic silicon oxide. More preferably, they are
derived from an amorphous fumed silicon oxide. Most preferably, the
silicon oxide particles are derived from an amorphous hydrophilic
fumed silicon oxide. Fumed silicon oxide is an exceptionally pure
form of silicon oxide made from silica tetrachloride as a starting
material, as is well known in the art. Suitable sources for the
fumed silicon oxide are Aerosil.RTM. which is commercially
available from Evonik Industries (formerly known as Degussa) or
Cap-o-Sil.RTM. which is commercially available from Cabbot
Corporation. Preferably, silicon oxide particles have an average
size in the range of from 5-100 microns and have a BET specific
surface area in the range of from 5-100 m2/g.
[0050] In accordance with the present invention also mixtures of
different hydrophilic metal oxide particles can be used. For
example a mixture of hydrophilic titanium oxide particles and
hydrophilic aluminium oxide particles can be used.
[0051] Suitably, the hydrophilic metal oxide particles have a BET
specific surface area of at least 50 m2/g, more preferably at least
75 m2/g, yet even more preferably at least 100 m2/g, even yet more
preferably at least 125 m2/g and most preferably at least 150 m2/g
Although is it preferred that the BET specific surface area is as
high as possible, it will usually not be higher than 500 m2/g
Methods for determining the BET specific surface area are well
known in the art.
[0052] In some embodiments of the present invention, the
hydrophilic metal oxide particles have a BET specific surface area
of less than 50 m2/g.
[0053] According to the present invention at least 80% of the
hydrophilic metal oxide particles have a particle size of 5 nm to
900 .mu.m. In some embodiments at least 80% of the hydrophilic
metal oxide particles have a particle size of 5-50 nm, preferably
of 5-40 nm, more preferably of 10-40 nm and most preferably of
20-40 nm. The total particle size distribution of the amorphous
silicon oxide particles is preferably in the range of 1-50 nm.
[0054] The grease compositions according to the invention may
additionally comprise other thickening components, e.g. polymers or
other fatty compounds that contain one or more OH-groups and/or one
or more unsaturated bonds and/or one or more ester groups and/or
one or more aromatic groups. Such thickening components can
suitably be present in an amount of less than 3% by weight,
preferably less than 2% by weight, based on the total weight of the
grease composition.
[0055] The grease compositions according to the present invention
may comprise other additives to tailor its suitability to a certain
use as is well known in the art. Such additives include anti-wear
agents, anti-corrosion agents, rust inhibitors, friction modifiers,
anti-oxidants, VI-improvers and the like as is well known by the
person skilled in the art. As suitable examples of such additives
sulphonates, sulphates, phosphates and/or phosphonates can be
mentioned. Suitable sulphonates include for instance methyl ester
sulphonate, sodium methyl ester sulphonate and calium sulphonate.
Suitable sulphates include for example calcium sulphate, sodium
dodecyl sulphate and sodium lauryl sulphate. Suitable phosphates
include for instance calcium hydrogen phosphate and amine
phosphate. Suitable phosphonates include for example calcium
phosphonate ester and other phosphonate esters.
[0056] Other suitable additives include silanes, (alkylated)
siloxanes, metal hydroxide silicates, silanols, hydrosilicates,
metal bonded silicon compound such as Mg3(Si2O5)(OH)2. Examples of
such additives are for instance polydimethyl siloxane oil,
hexomethyldisiloxane, magnesium hydrosilicate and other
phyllosilicates. As well as polymethylsilesquioxane, hydrated
(metal)silicates, amorphous silica, and sythetic silica gels, which
additives are all used to improve polymer performance. Such other
additives can suitably be present in an amount in the range of from
1-40% by weight, preferably 2-20% by weight, based on the total
weight of the grease composition. In case the grease composition
contains a high amount of such other additives, e.g. 20-40% by
weight, based on total weight of the grease composition, the grease
composition will display paste-type properties. Hence, the grease
composition in accordance with the present invention also includes
pastes. The other additives may also include small amounts (less
than 3% by weight, preferably less than 2% by weight, based on the
total weight of the grease composition) of further metal salts of
fatty acids, but such metal salts will not substantially contribute
to the formation of the grease thickener. In that case the grease
composition will contain more than four metal salts of different
fatty acids. A number of grease compositions according to the
present invention are hydroxide grease compositions.
[0057] The present grease compositions may in addition also contain
a small amount of metal hydroxide. Suitable metal hydroxides
include potassium hydroxide, aluminium hydroxide, calcium
hydroxide, lithium hydroxide, sodium hydroxide, magnesium hydroxide
barium hydroxide and bismuth hydroxide. Other suitable additives
include polypropylene, polyethylene, urea, bentonite, and other
greases such as (complex) greases and PTFE/PFPE greases.
[0058] A common disadvantage of conventionally manufacturing
methods is that it requires a multiple number of hours for blending
the various components, gelling and cooling of the grease
composition. At a batch scale of about 1-5 metric tons, the total
cooking (gelling) and cooling can take about four hours or more,
whereas grease milling can require two or more hours. Usually, the
total manufacturing time takes about eight hours. However, the
grease compositions according to the present invention can be
prepared in a very short manufacturing process, wherein blending,
gelling and cooling is preferably performed within one hour, more
preferably within half an hour period. The mechanical treatment,
preferably grease milling, in accordance with the present invention
for a 5 metric ton volume can require about two or two and a half
hours. In addition, it is observed that conventional grease
manufacturing processes are carried out at high temperatures,
typically in the range of from 170-220.degree. C., whereas the
present grease composition can suitably be prepared at a
temperature below 90.degree. C., including room temperature.
[0059] The present invention also provides methods for preparing
the present grease compositions. In accordance with the present
invention the components of the present grease compositions can be
mixed in any possible order of sequence. Preferably, the
hydrophilic metal oxide particles and the one or more amines that
contain one or more unsaturated C--C bonds and/or at least one OH
group are subjected to a mechanical treatment, a thermal treatment
or to both a mechanical treatment and a thermal treatment. Hence,
(a) the hydrophilic metal oxide particles or the one or more amines
that contain one or more unsaturated C--C bonds and/or at least one
OH group are subjected to a mechanical treatment and/or thermal
treatment; (b) a mixture of the hydrophilic metal oxide particles
and the one or more amines that contain one or more unsaturated
C--C bonds and/or at least one OH group are subjected to a
mechanical treatment and/or thermal treatment; or (c) a mixture of
the base oil, the hydrophilic metal oxide particles and the one or
more amines that contain one or more unsaturated C--C bonds and/or
at least one OH group are subjected to a mechanical treatment
and/or thermal treatment.
[0060] Preferably, the hydrophilic metal oxide particles, the one
or more amines that contain one or more unsaturated C--C bonds
and/or at least one OH group, or a mixture of these components and
the hydrophilic metal oxide particles is before or after mixing
with the other component(s) subjected to a mechanical treatment, a
thermal treatment or to both a mechanical treatment and a thermal
treatment.
[0061] In accordance with the present invention the entire amount
of base oil to be used or parts of the base oil can, for example,
be added at one or more stages of the process. Suitable embodiments
of the present invention include:
[0062] Subjecting a mixture of hydrophilic metal oxide particles
and one or more amines that contain one or more unsaturated C--C
bonds and/or at least one OH group to a mechanical and/or thermal
treatment, and optionally any of the hereinbefore described one or
more fatty acids, metal salts of fatty acids, esters, and/or
amides, followed by adding to the mixture so obtained the base oil
and optionally any further additives, and subjecting the grease
composition so obtained to a mechanical and/or thermal
treatment.
[0063] Subjecting a mixture of hydrophilic metal oxide particles
and one or more amines that contain one or more unsaturated C--C
and/or at least one OH group, and optionally any of the
hereinbefore described one or more fatty acids, metal salts of
fatty acids, esters and/or amides, and a part of the base oil to a
mechanical and/or thermal treatment, followed by adding to the
mixture so obtained the remaining part of the base oil and
optionally any further additives, and subjecting the grease
composition so obtained to a mechanical and/or thermal
treatment.
[0064] Subjecting a mixture of hydrophilic metal oxide particles,
the one or more amines that contain one or more unsaturated C--C
and/or at least one OH group, and optionally any of the
hereinbefore described one or more fatty acids, metal salts of
fatty acids, esters and/or amides, and the base oil to a mechanical
and/or thermal treatment, followed by adding to the mixture so
obtained any further additives, and subjecting the grease
composition so obtained to a mechanical and/or thermal
treatment.
Subjecting a mixture of the base oil, the hydrophilic metal oxide
particles and one or more amines, and optionally any of the
hereinbefore described one or more fatty acids, metal salts of
fatty acids, esters and/or amides, and optionally any further
additives, to a mechanical and/or thermal treatment. Subjecting the
hydrophilic metal oxide particles to a mechanical and/or thermal
treatment, followed by adding one or more one or more amines that
contain one or more unsaturated C--C bonds and/or at least one OH
group, and optionally any of the hereinbefore described one or more
fatty acids, metal salts of fatty acids, esters and/or amides, to
the hydrophilic metal oxide particles so obtained and subjecting
the mixture so obtained subsequently to a mechanical and/or thermal
treatment. The base oil and optionally any further additives are
then added to the mechanically and/or thermally treated mixture and
the grease composition so obtained is then subjected to a
mechanical and/or thermal treatment.
[0065] Subjecting the hydrophilic metal oxide particles to a
mechanical and/or thermal treatment, followed by adding the base
oil, one or more amines that contain one or more unsaturated C--C
bonds and/or at least one OH group, and optionally any of the
hereinbefore described one or more fatty acids, metal salts of
fatty acids, esters and/or amides, and optionally any further
additives, to the mechanically and/or thermally treated hydrophilic
metal oxide particles, and subjecting the grease composition so
obtained to a mechanical and/or thermal treatment. Subjecting one
or more amines that contain one or more unsaturated C--C bonds
and/or at least one OH group, and optionally any of the
hereinbefore described one or more fatty acids, metal salts of
fatty acids, esters and/or amides, to a mechanical and/or thermal
treatment, followed by adding the base oil, the hydrophilic metal
oxide particles and optionally any further additives to the at
least one metal salt so obtained, and subjecting the grease
composition so obtained to a mechanical and/or thermal
treatment.
[0066] Subjecting one or more amines that contain one or more
unsaturated C--C bonds and/or at least one OH group, and optionally
any of the hereinbefore described one or more fatty acids, metal
salts of fatty acids, esters and/or amides, to a mechanical and/or
thermal treatment of, followed by adding the hydrophilic metal
oxide particles to the mechanically and/or thermally treated
amine(s) and subjecting the mixture so obtained subsequently to a
mechanical and/or thermal treatment. The base oil and optionally
any further additives are then added to the mechanically and/or
thermally treated mixture and the grease composition so obtained is
then subjected to a mechanical and/or thermal treatment.
[0067] As indicated above, the grease composition may comprise any
further additives. Such further additives can be added to one or
more of the components at any stage of the preparation process of
the grease composition.
[0068] In the process according to the present invention each of
the components or any mixture of the components can be subjected to
a mechanical and/or thermal treatment in any possible order of
sequence. For example, all components can be added together after
which the mechanical and/or thermal treatment is applied. One of
the components (e.g. the hydrophilic metal oxide particles) can
first be subjected to a mechanical and/or thermal treatment after
which one other component(s) (e.g. the amine) or two or more other
components (e.g. one or more of the amines and the base oil) can be
added to the mechanically and/or thermally treated component,
followed by subjecting the grease composition so obtained to a
mechanical and/or thermal treatment. Alternatively, one of the
components (e.g. the hydrophilic metal oxide particles) can first
be subjected to a mechanical and/or thermal treatment after which
one other component (e.g. an amine) can be added to the
mechanically and/or thermally treated component, subjecting the
mixture so obtained to a further mechanical and/or thermal
treatment, followed by adding yet one or more other components
(e.g. the base oil and an optionally another metal salt) to the
mechanically and/or thermally treated mixture so obtained, and
subjecting the grease composition thus obtained to a mechanical
and/or thermal treatment. According to one embodiment of the
present invention, the hydrophilic metal oxide particles are first
subjected to a mechanical treatment, a thermal treatment or to both
a mechanical treatment and a thermal treatment. Subsequently, the
hydrophilic metal oxide particles so obtained are mixed with the
base oil and the one or more amines that contain one or more
unsaturated C--C and/or at least one OH group to form a grease
composition.
[0069] Hence, the present invention also relates to a method for
manufacturing a grease composition according to the present
invention, which method comprises the following sequential
steps:
[0070] (a) subjecting the hydrophilic metal oxide particles) to a
mechanical treatment, a thermal treatment or to both a mechanical
treatment and a thermal treatment; and (b) mixing the hydrophilic
metal oxide particles so obtained with the base oil and one or more
amines that contain one or more unsaturated C--C and/or at least
one OH group to form a grease composition.
[0071] According to another embodiment of the present invention,
the hydrophilic metal oxide particles are first mixed with the base
oil and the one or more amines that contain one or more unsaturated
C--C and/or at least one OH group to form a grease composition,
whereafter the grease composition so formed is subjected to the
mechanical treatment, the thermal treatment or to both the
mechanical treatment and the thermal treatment.
[0072] Accordingly, the present invention also relates to a method
for manufacturing a grease according to the present invention,
which method comprises the following sequential steps: (a) mixing
the hydrophilic metal oxide particles with the base oil and one or
more amines that contain one or more unsaturated C--C bonds and/or
at least one OH group to form a grease composition; and (b)
subjecting the grease composition so formed to a mechanical
treatment, a thermal treatment or to both a mechanical treatment
and a thermal treatment.
[0073] The mechanical treatment is preferably a milling step which
can be performed in any suitable milling apparatus, e.g. a high
pressure homogeniser, a colloid mill, a three-roller mill (e.g. a
three-roller mill) or a worm gear mill. Preferably, the milling
apparatus is a worm gear milling apparatus. The milling step can be
performed under inert conditions, i.e. in the absence of air or
oxygen and/or in the absence of water (vapour). The thermal
treatment is preferably a heating step. The heating step preferably
involves heating at a temperature in the range of 30-120.degree.
C., more preferably 40-110.degree. C. and in particular
45-90.degree. C. In this heating step, the water content of the
amorphous hydrophilic metal oxide particles is reduced, preferably
to a water content of the hydrophilic metal oxide particles of less
than 5% by weight, more preferably less than 1% by weight, even
more preferably less than 0.5% by weight, yet even more preferably
less than 0.25% by weight, based on the total weight of the
hydrophilic metal oxide particles. The water content of the
hydrophilic metal oxide particles is usually more than 0.01% by
weight, based on the total weight of the hydrophilic metal oxide
particles.
[0074] Most preferably, the grease composition is manufactured by
optionally subjecting the hydrophilic metal oxide particles to a
thermal treatment, preferably a heating step, to reduce the water
content of the hydrophilic metal oxide particles, followed by
mixing the hydrophilic metal oxide particles with the base oil and
the one or more amines that contain one or more unsaturated C--C
bonds and/or at least one OH group to form a grease composition,
whereafter the grease composition so formed is subjected to a
mechanical treatment, preferably a milling step.
[0075] As disclosed above, the grease composition according to the
present invention comprises a base oil, hydrophilic metal oxide
particles, more in particular silicon oxide particles, and one or
more amines that contain one or more unsaturated C--C bonds and/or
at least one OH group, wherein the amount of the amine (s) is
0.1-40% by weight, based on the total weight of the grease
composition. Suitably, the amount of the hydrophilic metal oxide
particles will be 0.1-20% by weight, preferably 1-5% by weight,
based on the total weight of the hydrophilic metal oxide particles
and the one or more amines that contain one or more unsaturated
C--C bonds and/or at least one OH group. The skilled person will
understand how such amounts can be realised starting from the
respective starting materials.
[0076] According to a preferred embodiment of the present
invention, the total amount of the one or more amines that contain
one or more unsaturated C--C bonds and/or at least one OH group,
based on the total amount of the hydrophilic metal oxide particles
and the amines, is within a range of 0.1-30% by weight, preferably
within the range of 0.1-20% by weight, based on the total amount of
the grease composition The grease composition according to the
present invention can be used in many applications. However, it is
in particular useful for lubricating a bearing, preferably a
rolling element bearing, e g. a spherical roller bearing, a taper
roller bearing, a cylindrical roller bearing, a needle roller
bearing, a ball bearing, and may also be used to lubricate a
sliding or plain bearing It is furthermore very useful in coupling
and gearing applications.
[0077] The grease compositions according to the present invention
encompass NLGI (National Lubricating Grease Institute) grades
ranging from NLGI grade 000 to NLGI grade 6. Preferably, the grease
compositions according to the present invention have a dropping
point of at least 70.degree. C. up to about 200.degree. C.
according to ASTM D-2265. When used in low loading gearings, the
grease composition has preferably a NLGI grade of 000 to 1. When
used in high loading gearings, the grease composition has
preferably a NLGI grade of 0 to 2. When used in bearings, the
grease composition has preferably a NLGI grade of 1 to 4, more
preferably a NLGI grade of 2 or 3 and most preferably a NLGI grade
of 2.
EXAMPLES
[0078] The performance of four grease compositions has been tested
on tribological and friction performance on the Ball-on-disc, the
Mini Traction Machine, at Imperial College, London UK. In each case
the test procedure consists of four steps, i.e. first a grease
working step which is followed by three consecutive Stribeck step
tests. Two grease samples from each of the four grease compositions
have undergone the entire test procedure. These duplications were
performed to monitor the repeatability of the test between two
different tests carried out in the exact same conditions. The same
ball and disc used for each of grease samples were cleaned prior to
running of the tests and the test repeat. The tests were run with
fresh grease.
[0079] The grease working step had the purpose of ensuring an even
distribution of the grease and to prepare the same initial
condition for each test, by shearing the grease in the same way and
for the same time, before the start of the actual test. In Table 1,
the test operating conditions during the grease working step and
the Stribeck test steps are shown.
TABLE-US-00001 TABLE 1 Grease working Stribeck steps (2nd, step
(1st step) 3rd, 4th steps) Load [N] 1 31 Max Hertz pressure [GPa]
0.31 0.96 Temperature [.degree. C.] 60 60 Speed range [mm/s] 5
(constant) 5-1000 (in 50 log steps) SRR [%] 0 10 Time [min] 5 6
In the four test procedure steps, the following operating
conditions were applied.
[0080] Step 1--Grease working step: a ball load of 1 N was applied
on the disc resulting in Hertzian contact pressure of 0.31 GPa, and
a constant speed of 5 mm/s, for 5 minutes.
[0081] Steps 2-4--The three consecutive Stribeck steps: a ball load
of 31 N was applied on the disc resulting in a Hertzian contact
pressure of 1 GPa, and the speed increased from 5 mms/s to 1000
mms/s at a slide-to-roll ratio (SRR) of 10%. This step was repeated
three times to monitor the repeatability of the step within the
same test, and to analyse the friction coefficient evolution after
each step due to the grease thixotropic character.
[0082] A test sample of a grease composition according to the
present invention was manufactured from a paraffinic mineral blend
base oil of 120 cSt from Scharr, Tunap, and 10 wt. %
calciumhydroxystearate from Barlocher, 2 wt. % calciumstearate from
Barlocher, 3 wt. % aerosol from Evonik i.e. hydrophilic silicon
oxide primary particles having a BET specific surface area of
175-220 m2/g and the primary particle size ranges typically between
7-25 nm, 1.2 wt. % triphenylphosphate from M. Volkholz, 2 wt. %
disodiumsebacic acid from M. Volkholz, 0.5 wt. %
alkylphosphateamine from Ciba, 0.5 wt. % from butylated triphenyl
phosphorothionate from Ciba, 0.5 wt. % benzotriazole from Ciba, 2.5
wt. % triphenylphosphorothionate from Ciba, 2 wt. %
ditertdodecylpolysulfide from Elf Atochem, 10 wt. % oleic
acid-oleylamine from Croda. The grease has been composed by adding,
mixing and milling in a 3-roller-mill for 30 minutes in total.
[0083] For comparison reasons, test sample of the present invention
was compared with three reference greases of the following
compositions:
(a) Li-1 comprising and a lithium salt as a grease thickener, and
having a mineral base oil viscosity of 100 mm2/s at 40.degree. C.;
(b) Li-2 comprising a mineral base oil and lithium salt as a grease
thickener, and having viscosity of 200 mm2/s at 40.degree. C.; (c)
CaSX-1 comprising a base oil blend of mineral and synthetic PAO
base oil and calcium sulphonate and calcium salts as a grease
thickener, and having of a viscosity of 80 mm2/s at 40.degree.
C.
[0084] In FIG. 1, the results of the test sample according to the
invention and the three reference grease compositions are compared
with each other, whereby the values of the Stribeck friction
coefficient and the entrainment speed [mms-1] measurements obtained
on the MTM rig are shown. The boundary, mixed and full film
lubricating regimes are indicated in the FIGURE over the ranges of
entrainment speeds.
[0085] From FIG. 1 it is clear that the test sample of the grease
composition according to the present invention constitutes an
improvement in terms of lubrication and friction when compared with
the three reference grease compositions.
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