U.S. patent application number 12/812820 was filed with the patent office on 2011-01-27 for method for preparing a lubricating composition.
Invention is credited to Alan Richard Wheatley.
Application Number | 20110021392 12/812820 |
Document ID | / |
Family ID | 39456435 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110021392 |
Kind Code |
A1 |
Wheatley; Alan Richard |
January 27, 2011 |
METHOD FOR PREPARING A LUBRICATING COMPOSITION
Abstract
The present invention provides a method for preparing a
lubricating composition, in particular a grease, the method at
least comprising the steps of: a) providing a base oil composition
optionally containing one or more additives; b) providing a
solution of one or more alkyl-substituted quinolines or oligomeric
derivatives thereof in a solvent; and c) adding the solution of
step b) to the base oil composition of step a) at a temperature
below 150.degree. C.
Inventors: |
Wheatley; Alan Richard;
(Ince Chester Cheshire, GB) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
39456435 |
Appl. No.: |
12/812820 |
Filed: |
January 16, 2009 |
PCT Filed: |
January 16, 2009 |
PCT NO: |
PCT/EP09/50483 |
371 Date: |
October 7, 2010 |
Current U.S.
Class: |
508/261 |
Current CPC
Class: |
C10M 133/40 20130101;
C10M 2207/126 20130101; C10N 2030/70 20200501; C10N 2030/00
20130101; C10M 169/06 20130101; C10M 2207/141 20130101; C10M
2207/16 20130101; C10M 2207/127 20130101; C10M 2203/1025 20130101;
C10M 2207/1265 20130101; C10M 2209/103 20130101; C10M 2207/1276
20130101; C10M 2203/1085 20130101; C10N 2030/26 20200501; C10M
2207/1415 20130101; C10M 2223/045 20130101; C10N 2050/10 20130101;
C10N 2030/10 20130101; C10M 2215/221 20130101; C10M 2219/024
20130101; C10M 177/00 20130101; C10N 2030/12 20130101; C10M
2207/126 20130101; C10N 2010/02 20130101; C10M 2207/1265 20130101;
C10N 2010/02 20130101; C10M 2207/127 20130101; C10N 2010/02
20130101; C10M 2207/1276 20130101; C10N 2010/02 20130101; C10M
2207/141 20130101; C10N 2010/04 20130101; C10M 2207/1415 20130101;
C10N 2010/04 20130101; C10M 2207/16 20130101; C10N 2010/04
20130101; C10M 2223/045 20130101; C10N 2010/04 20130101; C10M
2207/126 20130101; C10N 2010/02 20130101; C10M 2207/1265 20130101;
C10N 2010/02 20130101; C10M 2207/127 20130101; C10N 2010/02
20130101; C10M 2207/1276 20130101; C10N 2010/02 20130101; C10M
2207/141 20130101; C10N 2010/04 20130101; C10M 2207/1415 20130101;
C10N 2010/04 20130101; C10M 2207/16 20130101; C10N 2010/04
20130101; C10M 2223/045 20130101; C10N 2010/04 20130101 |
Class at
Publication: |
508/261 |
International
Class: |
C10M 133/40 20060101
C10M133/40 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 16, 2008 |
EP |
08100550.6 |
Claims
1. A method for preparing a lubricating composition, in particular
a grease, the method at least comprising the steps of: a) providing
a base oil composition; b) providing a solution of an
alkyl-substituted quinoline or oligomeric derivative thereof in a
solvent; and c) adding the solution of step b) to the base oil
composition of step a) at a temperature below 150.degree. C.
2. (canceled)
3. The method according to claim 2, wherein the alkyl-substituted
quinoline is an alkyl-substituted 1,2-dihydroquinoline.
4. The method according to claim 3, wherein the alkyl-substituted
1,2-dihydroquinoline has the general formula (I) ##STR00002##
wherein R.sup.1-R.sup.8 are independently selected from hydrogen or
an alkyl group having 1-8 carbon atoms; and n is 0, 1, 2 or 3.
5. The method according to claim 4, wherein R.sup.1-R.sup.8 are
independently selected from hydrogen or an alkyl group having 1-4
carbon atoms.
6. The method according to claim 5, wherein R.sup.4-R.sup.8 are
hydrogen.
7. The method according to claim 6, wherein the alkyl-substituted
1,2-dihydroquinoline has an average value for n of from 1.0 to
2.0.
8. The method according to claim 7, wherein the alkyl substituted
quinoline provided in the solution has a solubility of below 0.1%
as determined using ASTM D893.
9. The method according to claim 8, wherein the solvent comprises a
polyglycol.
10. A lubricating composition, in particular a grease, obtained by
the method according to any one of claims 1 to 9.
11. A method according to any one of claims 1, 3, 4, 5, 6, 7, 8,
and 9, wherein in step c) the solution of step b) is added at a
temperature below 120.degree..
Description
[0001] The present invention relates to a method for preparing a
lubricating composition, in particular a grease.
[0002] Alkyl-substituted quinolines and polymerized derivatives
thereof are known as very effective, low cost antioxidants for
several uses, including the use in lubricating compositions.
[0003] As an example, WO 94/24235 discloses the use of
alkyl-substituted 1,2-dihydroquinolines (including monomers,
dimers, trimers and tetramers thereof) in motor oils, transmission
oils, gear oils, metal working fluids, hydraulic fluids, greases
and the like. Illustrative examples of these alkyl-substituted
1,2-dihydroquinolines are 2,2,4-trimethyl-1,2-dihydroquinoline,
2-methyl-2,4-diethyl-1,2-dihydroquinoline,
2,2,4,6-tetramethyl-1,2-dihydroquinoline,
2,2,4,7-tetramethyl-1,2-dihydroquinoline,
6,6'-bis(2,2,4-trimethyl-1,2-dihydroquinoline) and the like.
[0004] Further, U.S. Pat. No. 5,246,606 discloses that dimeric,
trimeric and tetrameric tetrahydroquinoline derivatives are
suitable for stabilising organic materials against light-induced,
thermal and/or oxidative degradation. U.S. Pat. No. 5,246,606
suggests to use these compounds amongst others functional fluids
such as lubricants and hydraulic fluids.
[0005] Although alkyl-substituted quinolines such as
2,2,4-trimethyl-1,2-dihydroquinoline (also referred to as "TMQ",
"TMDQ" and "TMHQ") and oligomeric (i.e. dimeric, trimeric and
tetrameric) derivatives thereof, are widely used as antioxidants,
they have a number of disadvantages.
[0006] As an example, TMQ is in the form of a brittle solid at room
temperature and, being usually in the form of a mixture of monomer
and oligomers, it has no well-defined melting point. Although it
softens as the temperature increases, it is still a very viscous
and stringy material at typical additive addition temperatures of
around 80 to 100.degree. C.
[0007] If TMQ is added to lubricating compositions such as greases
at this typical temperature range of from 80 to 100.degree. C., it
will not be suitably dispersed into the grease and will result in
e.g. filter blockages in grease delivery systems. Even if the
filter loading of these grease delivery systems is not enough for
the filter to block immediately, some of the antioxidant will have
been taken out of the grease, which would then suffer from reduced
life as a result.
[0008] In view of the above, alkyl-substituted quinolines are
usually added to greases at temperatures above 150.degree. C.,
usually between 150-160.degree. C. after the grease has completed
its critical cooling phase after establishing the thickener system
in the base oil.
[0009] However, an associated problem of the known method is that
the window of opportunity for adding the alkyl-substituted
quinolines is usually narrow, if they are to be dispersed properly
in the grease. If the alkyl-substituted quinolines are added e.g.
ten minutes later, this may be too late as the grease may have been
cooled too much.
[0010] A further problem of the known method of adding the
alkyl-substituted quinolines to the grease at relatively high
temperatures, is that more severe health and safety issues need to
be taken into account, relating e.g. to the dangers of grease at
high temperature and the danger of fumes when the manufacturing
vessel has to be opened.
[0011] It is an object of the present invention to avoid the above
problems.
[0012] It is another object to provide an alternative method for
preparing a lubricating composition, in particular a grease.
[0013] One or more of the above or other objects are obtained by
the present invention by providing a method for preparing a
lubricating composition, in particular a grease, the method at
least comprising the steps of:
[0014] a) providing a base oil composition optionally containing
one or more additives;
[0015] b) providing a solution of one or more alkyl-substituted
quinolines or oligomeric derivatives thereof in a solvent; and
[0016] c) adding the solution of step b) to the base oil
composition of step a) at a temperature below 150.degree. C.
[0017] Surprisingly, it has been found according to the present
invention that if the alkyl-substituted quinolines (or oligomeric
derivatives thereof) are added in a solvent to the base oil
composition, they can be added at a lower temperature, whilst still
obtaining a proper dispersing thereof in the base oil
composition.
[0018] An important advantage of the present invention is that the
alkyl-substituted quinolines (or oligomeric derivatives thereof)
can be added at a lower temperature, resulting in less severe
safety requirements. Also, there is more flexibility in the moment
of adding the alkyl-substituted quinolines (or oligomeric
derivatives thereof), as the specific temperature for adding
thereof is less critical than in the case where no solvent is
used.
[0019] Preferably in step c) the solution of step b) is added at a
temperature below 120.degree. C., preferably in the range of from
10 to 110.degree. C., more preferably from 15 to 100.degree. C.
[0020] According to an especially preferred embodiment of the
present invention, the one or more alkyl-substituted quinolines are
alkyl-substituted 1,2-dihydroquinolines (or oligomeric derivatives
thereof). Preferably, the one or more alkyl-substituted
1,2-dihydroquinolines have the general formula (I)
##STR00001##
wherein R.sup.1-R.sup.8 are independently selected from hydrogen or
an alkyl group having 1-8 carbon atoms; and n is 0, 1, 2 or 3.
[0021] Preferably, R.sup.1-R.sup.8 are independently selected from
hydrogen or an alkyl group having 1-4 carbon atoms, preferably
having 1-2 carbon atoms. Preferably R.sup.4 is H. It is even more
preferred that R.sup.4-R.sup.8 are, all H. Also it is preferred
that R.sup.1-R.sup.3 are all a methyl group.
[0022] Further the one or more alkyl substituted
1,2-dihydroquinolines preferably have an average value for n of
from 1.0 to 2.0, preferably from 1.3 to 1.6.
[0023] Also it is preferred that the one or more alkyl substituted
quinolines provided in the solution have a solubility of below 0.1%
as determined using ASTM D893.
[0024] The alkyl substituted quinoline compounds (or oligomeric
derivatives thereof) as used in the present invention are either
commercially available or can be prepared by various reactions that
are known in the art. Examples of preparation methods have been
given in the above-mentioned WO 94/24235 and U.S. Pat. No.
5,246,606 and references cited therein, the teaching of which is
hereby incorporated by reference. Other examples are given in U.S.
Pat. No. 4,692,258 and U.S. Pat. No. 3,910,918 and references cited
therein, the teaching of which is hereby incorporated by reference
as well.
[0025] One specific example for preparing TMQ
(2,2,4-trimethyl-1,2-dihydroquinoline) has been given in W. R.
Vaughan, "Organic synthesis", Collective Volume III, pp 329-30,
(1955).
[0026] There are no particular limitations regarding the solvent
used in the method according to the present invention, and various
conventional solvents may be conveniently used.
[0027] Preferably, the solvent comprises a polyglycol, more
preferably a polyalkylene glycol. Polyglycols are well known in the
art and are not further discussed here in detail.
[0028] As an example, the polyalkylene glycols (PAG) may exhibit
alkylene oxide units with 1 to 6 carbon atoms (--R--O--) as monomer
units.
[0029] The polyalkylene glycols may exhibit hydrogen end groups,
alkyl, aryl, alkylaryl, aryloxy, alkoxy, alkylaryloxy and/or
hydroxy end groups. Alkylaryloxy groups should also be understood
to mean arylalkyl (ene)oxy groups and alkylaryl groups to mean
arylalkyl(ene) groups (e.g. aryl CH.sub.2CH.sub.2--). The end
groups of the alkyl type, including the alkoxy type, or of the aryl
types, including the alkylaryl type, aryloxy type and alkylaryloxy
type preferably exhibit 6 to 24 carbon atoms, particularly
preferably 6 to 18 carbon atoms, based on the aryl types, and
preferably 1 to 12 carbon atoms, based on the alkyl types.
[0030] The polyalkylene glycols according to the invention may be
either homopolymers, namely polypropylene glycol (and/or
polypropylene oxide) or copolymers, terpolymers etc. For the latter
cases, the monomer units may exhibit a random distribution or a
block structure. If the polyalkylene glycols are not homopolymers,
preferably at least 20%, preferably at least 40% of all monomer
units are producible from polypropylene oxide (PO), and also
preferably, at least 20% of all monomer units of these polyalkylene
glycols are producible by using ethylene oxide (EO) (PO/EO
copolymers). According to a further embodiment, preferably at least
20%, preferably at least 40% of all monomer units are obtainable
from butylene oxide (BO) and, moreover, preferably at least 20% of
all monomer units of these polyalkylene glycols are obtainable by
using ethylene oxide (BO/EO copolymers).
[0031] When (poly)alcohols are used, the starting compound is
incorporated into the polymer and, according to the meaning of the
invention, also referred to as end group of the polymer chain.
Suitable starting groups consist of compounds comprising active
hydrogen such as e.g. n-butanol, propylene glycol, ethylene glycol,
neopentyl glycols such as pentaerythritol, ethylene diamine,
phenol, cresol or other (C1 to C16 (mono, di or tri)alkyl)
aromatics, (hydroxyalkyl) aromatics, hydroquinone,
aminoethanolamines, triethylenetetramines, polyamines, sorbitol or
other sugars. Other C--H acidic compounds such as carboxylic acids
or carboxylic anhydrides can also be used as starting
compounds.
[0032] Preferably, the polyalkylene glycols comprise aryl groups or
corresponding heteroaromatic groups, e.g. inserted into the polymer
chain, as side groups or end groups; the groups may, if necessary,
be substituted with linear or branched alkyl groups or alkylene
groups, the alkyl groups or alkylene groups overall exhibiting
preferably 1 to 18 carbon atoms.
[0033] Cyclic ether alcohols such as hydroxyfurfuryl or
hydroxytetrahydrofuran, nitrogen heterocyclics or sulphur
heterocyclics can also be used as starting groups. Such
polyalkylene glycols are disclosed in WO 01/57164, the teaching of
which is herewith incorporated by reference.
[0034] Preferably, the polyalkylene glycols according to the
invention have an average molecular weight (number average) of 200
to 3000 g/mole, more preferably 400 to 2000 g/mole. The kinematic
viscosity of the polyalkylene glycols is preferably 10 to 400
mm.sup.2/s (cSt) measured at 40.degree. C. according to DIN
51562.
[0035] The polyalkylene glycols used according to the invention can
be produced by reacting alcohols, including polyalcohols, as
starting compounds with oxiranes such as ethylene oxide, propylene
oxide and/or butylene oxide. Following the reaction, these possess
only one free hydroxy group as end group. Polyalkylene glycols with
only one hydroxy group are preferred over those with two free
hydroxy groups. Polyalkylene glycols which, e.g. after a further
etherification step, comprise no free hydroxy groups any longer are
particularly preferred regarding the stability, hygroscopicity and
compatibility. The alkylation of terminal hydroxyl groups leads to
an increase in the thermal stability. Thus, in an especially
preferred embodiment according to the present invention, the PAG
base oil comprises end-capped PAG, i.e. where no free hydroxyl
groups are present.
[0036] It is also possible to use neopentyl polyolesters instead of
the polyalkylene glycols described above.
[0037] The esters of neopentyl polyols such as neopentyl glycol,
pentaerythritol and trimethylol propane with linear or branched
C.sub.4 to C.sub.12 monocarboxylic acids, e.g. with addition of
corresponding dicarboxylic acids are suitable neopentyl
polyolesters. Usually, pentaerythritol is obtainable as technical
grade pentaerythritol which is a mixture of monopentaerythritol,
dipentaerythritol and tripentaerythritol. However, their
condensation products such as dipentaerythritol and/or
tripentaerythritol are also suitable as alcohol components.
[0038] Pentaerythritol or mixtures with dipentaerythritol and/or
tripentaerythritol, preferably mixtures comprising predominantly
dipentaerythritol are particularly suitable.
[0039] Complex esters can be produced by proportional
esterification of polyhydric alcohols with monovalent and divalent
acids such as C.sub.4 to C.sub.12 dicarboxylic acids. In this way,
dimers and oligomers are formed. When using neopentyl glycol and/or
trimethylol propane as alcohol group, complex esters are
preferred.
[0040] There are no particular limitations regarding the base oil
composition used in the method according to the present invention,
and various conventional mineral oils and synthetic oils may be
conveniently used. For the purpose of this description, the term
"base oil" is meant to also include a grease base stock.
[0041] The base oil composition used in the present invention may
conveniently comprise mixtures of one or more mineral oils and/or
one or more synthetic oils.
[0042] Mineral oils include liquid petroleum oils and
solvent-treated or acid-treated mineral lubricating oil of the
paraffinic, naphthenic, or mixed paraffinic/naphthenic type which
may be further refined by hydrofinishing processes and/or
dewaxing.
[0043] Suitable base oils for use in the lubricating oil
composition of the present invention are Group I, Group II or Group
III base oils, polyalphaolefins, Fischer-Tropsch derived base oils
and mixtures thereof.
[0044] By "Group I" base oil, "Group II" base oil and "Group III"
base oil in the present invention are meant lubricating oil base
oils according to the definitions of American Petroleum Institute
(API) categories I, II and III. Such API categories are defined in
API Publication 1509, 15th Edition, Appendix E, April 2002.
[0045] Suitable Fischer-Tropsch derived base oils that may be
conveniently used as the base oil in the lubricating oil
composition of the present invention are those as for example
disclosed in EP 0 776 959, EP 0 668 342, WO 97/21788, WO 00/15736,
WO 00/14188, WO 00/14187, WO 00/14183, WO 00/14179, WO 00/08115, WO
99/41332, EP 1 029 029, WO 01/18156 and WO 01/57166.
[0046] Synthetic oils include hydrocarbon oils such as olefin
oligomers (PAOs), dibasic acid esters, polyol esters, and dewaxed
waxy raffinate. Synthetic hydrocarbon base oils sold by the Shell
Group under the designation "XHVI" (trade mark) may be conveniently
used.
[0047] The total amount of base oil incorporated in the lubricating
composition of the present invention is preferably present in an
amount in the range of from 60 to 92 wt. %, more preferably in an
amount in the range of from 75 to 90 wt. % and most preferably in
an amount in the range of from 75 to 88 wt. %, with respect to the
total weight of the lubricating composition.
[0048] If desired, the final lubricating composition may further
comprise one or more additives such as anti-oxidants, anti-wear
agents, dispersants, detergents, friction modifiers, viscosity
index improvers, pour point depressants, tackifying agents,
corrosion inhibitors, demulsifiers, defoaming agents and seal fix
or seal compatibility agents, etc.
[0049] As the person skilled in the art is familiar with the above
and other additives, these are not further discussed here. The
additives may be added to the base oil composition before or after
the one or more alkyl-substituted quinolines are added in step c).
Also, if appropriate, the additives may also be added at the same
time with the one or more alkyl-substituted quinolines.
[0050] Said additives are typically present in an amount in the
range of from 0.01 to 12.5 wt. %, based on the total weight of the
lubricating composition, preferably in an amount in the range of
from 0.05 to 10.0 wt. %, more preferably from 1.0 to 9.0 wt. % and
most preferably in the range of from 2.0 to 5.0 wt. %, based on the
total weight of the lubricating composition.
[0051] As the lubricating composition may also be (and preferably
is) in the form of a grease, the base oil as contained in the
lubricating composition may contain or be compounded with one or
more thickeners such as metallic soaps, organic substances or
inorganic substances, for example, lithium soaps, lithium complex
soaps, sodium terephthalate, urea/urethane compounds and clays.
[0052] Preferably, the lubricating composition has a kinematic
viscosity in the range of from 2 to 80 mm.sup.2/s at 100.degree.
C., more preferably in the range of from 3 to 70 mm.sup.2/s, most
preferably in the range of from 4 to 50 mm.sup.2/s.
[0053] The lubricating compositions of the present invention may be
conveniently prepared by admixing the one or more base oils and,
optionally, one or more additives that are usually present in
lubricating compositions, for example as herein before described,
with mineral and/or synthetic base oil. Preferably, and as is
customary in the art, the one or more alkyl-substituted quinoline
compounds (or oligomeric derivatives thereof) have a sufficiently
small particle size (e.g. below 50 .mu.m, preferably below 20
.mu.m) to allow easy dispersion thereof in the lubricating
composition.
[0054] In another aspect the present invention provides a
lubricating composition, in particular a grease, obtained by the
method according to the present invention.
[0055] The present invention is described below with reference to
the following Examples, which are not intended to limit the scope
of the present invention in any way.
EXAMPLES
Solutions of Alkyl-Substituted Quinolines
[0056] Solution A
[0057] A 500 ml 50% m/m solution of oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline (solid; available from Rhein
Chemie Rheinau GmbH under the trade designation "Additin RC7010")
in polyalkylene glycol (available from The Dow Chemical Company,
USA under the trade designation "Oxilube 504") was prepared by
heating the polyalkylene glycol to 100.degree. C. before adding the
oligomeric 2,2,4-trimethyl-1,2-dihydroquinoline. The oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline was added slowly over about
two minutes, allowing it to disperse throughout the fluid before
adding more. The mixture thus obtained was stirred for a further 30
minutes at 100.degree. C. A stable, homogeneous solution was
formed.
[0058] Solution B
[0059] Similar to Solution A, a 500 ml 50% m/m solution of
oligomeric 2,2,4-trimethyl-1,2-dihydroquinoline in polyglycol
(available from The Dow Chemical Company, USA under the trade
designation "Synalox 50-50B") was prepared. A stable, homogeneous
solution was formed.
Example 1
[0060] A grease was prepared using the above mentioned Solution A
(50 ml) and a conventional grease base stock (4950 g).
[0061] The conventional grease base stock contained about 10% m/m
lithium complex thickener and about 90% m/m paraffinic mineral base
oil blended from SN 500 and bright stock (viscosity at 40.degree.
C. of 180 mm.sup.2/s according to ASTM D445). The conventional
grease base stock also contained an antiwear additive (a zinc
dialkyl dithiophosphate), an extreme pressure additive (a
sulphurised ester) and a rust inhibitor (a zinc naphthenate).
[0062] The grease base stock and Solution A were simply mixed
during 30 minutes using a laboratory paddle mixer, after both had
been previously heated to 80.degree. C. before mixing.
[0063] After visual inspection no apparent deficiencies of the
obtained grease were found. No lumps were formed. Also, no
separating of the oligomeric 2,2,4-trimethyl-1,2-dihydroquinoline
out of the grease occurred after 12 months of storage.
[0064] Other properties of the obtained grease are indicated in
Table I below.
TABLE-US-00001 TABLE I Method/ Test Conditions Value Penetration
ASTM D217 260 (worked) 25.degree. C. Penetration (long ASTM D217
280 term worked) 100,000 strokes Oil separation IP 121 3.5% 7 days
at 40.degree. C. Oxidation ASTM D942 30 kPa stability 100 h at
99.degree. C. Copper corrosion ASTM D4048 lb 24 h at 100.degree. C.
Water washout ASTM D1264 0.5% l h at 79.degree. C.
[0065] The results in Table I show that the desired properties for
a grease such as mechanical stability, oil retention and
surprisingly also the stability against water are still present in
the grease of Example 1 and are not affected by the presence of the
solvent (polyalkylene glycol) used to dissolve the oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline.
Example 2
[0066] Similar to Example 1, a grease was prepared using Solution
B.
[0067] After visual inspection no apparent deficiencies of the
obtained grease were found. No lumps were formed.
[0068] Also, no separating of the oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline
2,2,4-trimethyl-1,2-dihydroquinoline out of the grease occurred
after 12 months of storage. Similar to Example 1, the grease of
Example 2 showed desired properties of mechanical stability, oil
retention and stability against water.
Comparative Example 1
[0069] A grease was prepared using the same amount of oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline (without the solvent) and the
same grease base stock of Examples 1 and 2.
[0070] The grease base stock was heated to about 160.degree. C.
Then, a part of the solid oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline was added to the heated grease
base stock and left at this temperature for about 10 minutes.
Mixing took place using a laboratory paddle mixer until the mixture
had reached the temperature of about 60.degree. C.
[0071] Then the mixture was reheated to about 160.degree. C. and
left at this temperature for about 30 minutes. Subsequently, the
steps of adding and mixing was repeated until all oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline was added and mixed.
[0072] After visual inspection no apparent deficiencies of the
obtained grease were found. No lumps were formed.
Comparative Example 2
[0073] Similar to Comparative Example 1 a grease was prepared,
although the heating was to about 60.degree. C. (instead of to
about 160.degree. C.).
[0074] It was not possible to disperse the solid oligomeric
2,2,4-trimethyl-1,2-dihydroquinoline into the grease base stock,
which would lead to severe filter blockages in case the grease of
Comparative Example 2 was to be used in e.g. grease delivery
systems.
DISCUSSION
[0075] As can be seen from the Examples, the present invention
allows adding the alkyl-substituted quinolines or oligomeric
derivatives thereof at a significant lower temperature, whilst
still obtaining a stable grease having desired properties. It goes
without saying that this is highly desired from a health and safety
perspective as well as from a practical manufacturing
perspective.
[0076] In this respect it is noted that if no solvent was used (see
Comparative Example 2) whilst adding the alkyl-substituted
quinolines or oligomeric derivatives thereof, no stable grease was
obtained.
* * * * *