U.S. patent application number 13/133183 was filed with the patent office on 2012-07-05 for lubricating composition containing a compound derived from a hydroxy-carboxylic acid.
This patent application is currently assigned to THE LUBRIZOL CORPORATION. Invention is credited to Mark R. Baker, Stuart L. Bartley, Shubhamita Basu.
Application Number | 20120172265 13/133183 |
Document ID | / |
Family ID | 42072863 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120172265 |
Kind Code |
A1 |
Bartley; Stuart L. ; et
al. |
July 5, 2012 |
Lubricating Composition Containing a Compound Derived from a
Hydroxy-carboxylic Acid
Abstract
The invention relates to a lubricating composition comprising
(a) a compound derived from a hydroxy-carboxylic acid, and (b) an
oil of lubricating viscosity. The invention further provides for
the use of the lubricating composition for lubricating a limited
slip differential.
Inventors: |
Bartley; Stuart L.;
(Wickliffe, OH) ; Baker; Mark R.; (Lyndhurst,
OH) ; Basu; Shubhamita; (Willoughby, OH) |
Assignee: |
THE LUBRIZOL CORPORATION
Wickliffe
US
|
Family ID: |
42072863 |
Appl. No.: |
13/133183 |
Filed: |
December 8, 2009 |
PCT Filed: |
December 8, 2009 |
PCT NO: |
PCT/US2009/067091 |
371 Date: |
August 11, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61120932 |
Dec 9, 2008 |
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Current U.S.
Class: |
508/185 ;
508/272; 508/290 |
Current CPC
Class: |
C10N 2030/06 20130101;
C10M 2219/022 20130101; C10N 2030/76 20200501; C10M 129/76
20130101; C10N 2030/10 20130101; C10M 2207/124 20130101; C10M
141/10 20130101; C10N 2070/02 20200501; C10M 141/08 20130101; C10M
2215/086 20130101; C10N 2030/04 20130101; C10M 2215/082 20130101;
C10M 2219/106 20130101; C10M 2223/043 20130101; C10N 2030/36
20200501; C10N 2060/14 20130101; C10N 2030/08 20130101; C10M 133/16
20130101; C10M 2207/289 20130101; C10N 2030/54 20200501 |
Class at
Publication: |
508/185 ;
508/290; 508/272 |
International
Class: |
C10M 135/36 20060101
C10M135/36; C10M 133/44 20060101 C10M133/44 |
Claims
1-22. (canceled)
23. A method of lubricating a limited slip differential comprising
supplying to the limited slip differential a lubricating
composition comprising (a) a derivative of a hydroxy-carboxylic
acid, and (b) an oil of lubricating viscosity, wherein derivative
of a hydroxy-carboxylic acid is represented by Formula 1a or 1b:
##STR00002## wherein n' is 0 to 10 for Formula (1b), and 1 to 10
for Formula (1a); p is 1 to 5; Y and Y' are independently --O--,
>NH, >NR.sup.3, or an imide group formed by taking together
both Y and Y' groups in (1b) or two Y groups in (1a) and forming a
R.sup.1--N<group between two >C.dbd.O groups; X is
independently --CH.sub.2--, >CHR.sup.4, >CR.sup.4R.sup.5,
>CHOR.sup.6, >C(OH)CO.sub.2R.sup.6,
>C(CO.sub.2R.sup.6).sub.2, --CH.sub.3, --CH.sub.2R.sup.4 or
CHR.sup.4R.sup.5, --CH.sub.2OR.sup.6,
--CH(CO.sub.2R.sup.6).sub.2,.dbd.C--R.sup.6 (where equals three
valences, and may only apply to Formula (1a) or mixtures thereof to
fulfill the valence of Formula (1a) and/or (1b)); R.sup.1 and
R.sup.2 are independently hydrocarbyl groups; R.sup.3 is a
hydrocarbyl group; R.sup.4 and R.sup.5 are independently
keto-containing groups, ester groups or hydrocarbyl groups, or
--OR.sup.6, or --CO.sub.2R.sup.6, or --OH; and R.sup.6 is
independently hydrogen or a hydrocarbyl group.
24. The method of claim 23, wherein the derivative of a
hydroxy-carboxylic acid is a derivative of a hydroxy-polycarboxylic
acid.
25. The method of claim 24, wherein the derivative of a
hydroxy-polycarboxylic acid is selected from the group consisting
of a hydroxy-carboxylic acid di-ester, a hydroxy-carboxylic acid
di-amide, a hydroxy-carboxylic acid imide, a hydroxy-carboxylic
acid di-imide, a hydroxy-carboxylic acid ester-amide, a
hydroxy-carboxylic acid ester-imide, and a hydroxy-carboxylic acid
imide-amide.
26. The method of claim 24, wherein the derivative of a
hydroxy-polycarboxylic acid is selected from the group consisting
of a hydroxy-carboxylic acid imide, a hydroxy-carboxylic acid
di-imide, a hydroxy-carboxylic acid ester-imide, and a
hydroxy-carboxylic acid imide-amide.
27. The method of claim 24, wherein the derivative of a
hydroxy-polycarboxylic acid is selected from the group consisting
of a hydroxy-carboxylic acid imide and a hydroxy-carboxylic acid
di-imide.
28. The method of claim 24, wherein the derivative of a
hydroxy-polycarboxylic acid is a derivative of tartaric acid, an
imide derivative of citric acid, or mixtures thereof.
29. The method of claim 24, wherein the derivative of a
hydroxy-polycarboxylic acid is an imide derivative of tartaric
acid, an imide derivative of citric acid, or mixtures thereof.
30. The method of claim 24, wherein the derivative of a
hydroxy-polycarboxylic acid is an imide derivative of tartaric
acid, or mixtures thereof.
31. The method of claim 23, wherein the derivative of a
hydroxy-carboxylic acid is present in an amount in the range of 0.2
wt % to 3 wt % of the lubricating composition
32. The method of claim 23, wherein the derivative of a
hydroxy-carboxylic acid is present at greater than 0.2 wt % to 3 wt
% of the lubricating composition.
33. The method of claim 23, further comprising a sulphur-containing
compound.
34. The method of claim 33, wherein the sulphur-containing compound
is a dimercaptothiadiazole or derivative, or mixtures thereof.
35. The method of claim 33, wherein the sulphur-containing compound
is a polysulphide or a sulphurised olefin.
36. The method of claim 23, wherein the lubricating composition
further comprises a phosphorus-containing compound, and wherein the
phosphorus containing compound is an amine salt of a phosphoric
acid ester.
37. The method of claim 36, wherein the amine salt of a phosphoric
acid ester is an amine salt of either (i) a hydroxy-substituted
di-ester of phosphoric acid, or (ii) a phosphorylated
hydroxy-substituted di- or tri-ester of phosphoric acid.
38. The method of claim 23, wherein the lubricating composition
further comprises a boron-containing compound, and wherein the
boron-containing compound is a borated dispersant, a borate ester
or a borated phospholipid.
39. The method of claim 23, wherein the lubricating composition has
a sulphur content in the range of 0.3 wt % to 5 wt %.
40. The method of claim 23, wherein the hydroxy-carboxylic acid
comprises a monohydroxy monocarboxylic acid.
41. The method of claim 23, wherein the monohydroxy monocarboxylic
acid comprises glycolic acid.
42. The method of claim 23, wherein the derivative of the
hydroxy-carboxylic acid is an amide.
43. The method of claim 23, wherein the amide is the condensation
product of glycolic acid with a hydrocarbyl amine containing 1-150
carbon atoms.
Description
FIELD OF INVENTION
[0001] The invention relates to a lubricating composition
comprising (a) a compound derived from a hydroxy-carboxylic acid,
and (b) an oil of lubricating viscosity. The invention further
provides for the use of the lubricating composition for lubricating
a limited slip differential.
BACKGROUND OF THE INVENTION
[0002] A limited slip differential in a vehicle typically employs a
wet multi-plate clutch, i.e., clutch plates which are immersed in a
lubricant. The limited slip differential typically has bevel gear
or spur gear planetary systems which distribute the drive torque
evenly to the two driving wheels irrespective of their rotational
speed. This makes it possible for the driven wheels to roll during
cornering without slip between the wheel and road surface in spite
of their different rotational speed. In order for the slip to be
controlled lubricants containing compounds capable of improving
friction performance, dispersants and sulphur- and/or
phosphorus-containing extreme pressure agents may be used. Examples
of lubricants of this type are disclosed in U.S. Pat. Nos.
4,308,154; 5,547,586; 4,180,466; 3,825,495; and European Patent
Application 0 399 764 A1.
[0003] Lubricants containing compounds suitable for (i) deposit
control (U.S. Pat. No. 3,284,409), and (ii) wear performance are
described in International Application WO 96/037585, US Patent
Application 2002/0119895, and U.S. Pat. No. 5,487,838.
SUMMARY OF THE INVENTION
[0004] The inventors of this invention have discovered that a
lubricating composition and method as disclosed herein is capable
of providing an acceptable level of at least one of (i) lubricant
thermal stability, (ii) lubricant oxidative stability, (iii) high
static coefficient of friction, (iv) fuel economy, (v) deposit
control, (vi) seal compatibility, (vii) cleanliness and (viii) low
tendency towards noise, vibration and harshness (NVH) often
manifested as chatter (i.e. an abnormal noise typically referred to
as a low-frequency "growl" and "groan", particularly during
higher-speed cornering manoeuvres). The inventors have also
unexpectedly discovered that the lubricant composition and method
disclosed herein may also be suitable for limited slip systems
having one or more distinct plate materials. For example the plate
materials may be steel, paper, ceramic, carbon fibers and systems
employing a mixture of plate types such as steel on ceramic, carbon
fibers in paper or steel on paper.
[0005] In one embodiment, the invention provides a method of
lubricating a limited slip differential comprising supplying to the
limited slip differential a lubricating composition comprising (a)
a derivative of (or a compound derived from) a hydroxy-carboxylic
acid, and (b) an oil of lubricating viscosity.
[0006] In one embodiment, the invention provides for the use of a
lubricating composition comprising (a) a derivative of (or a
compound derived from) a hydroxy-carboxylic acid, and (b) an oil of
lubricating viscosity in a limited slip differential to provide an
acceptable level of at least one of (i) lubricant thermal
stability, (ii) lubricant oxidative stability, (iii) friction
coefficient, (iv) fuel economy, (v) deposit control, (vi) seal
compatibility, and (vii) chattering (abnormal noise). In one
embodiment the use provides an acceptable level of friction
coefficient.
DETAILED DESCRIPTION OF THE INVENTION
[0007] The present invention provides a lubricating composition and
method as disclosed herein above.
Compound Derived from a Hydroxy-Carboxylic Acid
[0008] The lubricating composition of the present invention
includes a derivative of (or a compound derived from) a
hydroxy-carboxylic acid, or mixtures thereof. As used herein, the
expression "a derivative of" is meant to encompass materials that
are literally "derived from" the indicated hydroxy-carboxylic acid
as well as those materials that are potentially "derivable from"
the hydroxy-carboxylic acid, whether or not they are actually
prepared using the indicated acid as a starting material.
Derivatives of hydroxy-carboxylic acids include materials prepared
or preparable by reaction of the acid group and/or the alcohol
group, such as esters, amides, and imides and mixtures of multiple
such functionalities.
[0009] The hydroxy-carboxylic acid includes monohydroxy
monocarboxylic acids, polyhydroxy monocarboxylic acids, monohydroxy
polycarboxylic acids and polyhydroxy polycarboxylic acids. Also,
hydroxy polycarboxylic acids may be monohydroxy polycarboxylic
acids such as citric acid or polyhydroxy polycarboxylic acids such
as tartaric acid. The derivative of (or compound derived from) a
hydroxy-carboxylic acid includes amide, ester or imide derivatives
of a hydroxy-carboxylic acid, or mixtures thereof. Typically, the
derivative of a hydroxy-carboxylic acid may be a derivative of a
hydroxy-polycarboxylic acid such as tartaric acid.
[0010] In one embodiment the an amide, ester or imide derivative of
a hydroxy-carboxylic acid may be at least one of hydroxy-carboxylic
acid di-ester, a hydroxy-carboxylic acid di-amide, a
hydroxy-carboxylic acid mono-imide, a hydroxy-carboxylic acid
di-imide, a hydroxy-carboxylic acid ester-amide, a
hydroxy-carboxylic acid ester-imide, and a hydroxy-carboxylic acid
imide-amide. In one embodiment the amide, ester or imide derivative
of a hydroxy-carboxylic acid may be at least one of the group
consisting of a hydroxy-carboxylic acid di-ester, a
hydroxy-carboxylic acid di-amide, and a hydroxy-carboxylic acid
ester-amide.
[0011] Examples of a suitable a hydroxy-carboxylic acid include
citric acid, tartaric acid, lactic acid, glycolic acid,
hydroxy-propionic acid, hydroxyglutaric acid, or mixtures thereof.
In one embodiment the amide, ester or imide derivative of a
hydroxy-carboxylic acid may be derived from tartaric acid, citric
acid, hydroxy-succinic acid, dihydroxy mono-acids, mono-hydroxy
diacids, or mixtures thereof. In one embodiment the amide, ester or
imide derivative of a hydroxy-carboxylic acid includes a derivative
or (or compound derived from) tartaric acid or citric acid. In one
embodiment the amide, ester or imide derivative of a
hydroxy-carboxylic acid includes a compound derived from tartaric
acid.
[0012] The derivative of a hydroxy-carboxylic acid may be selected
from the group consisting of a hydroxy-carboxylic acid di-ester, a
hydroxy-carboxylic acid di-amide, a hydroxy-carboxylic acid imide,
a hydroxy-carboxylic acid di-imide, a hydroxy-carboxylic acid
ester-amide, a hydroxy-carboxylic acid ester-imide, and a
hydroxy-carboxylic acid imide-amide.
[0013] The derivative of a hydroxy-carboxylic acid may be selected
from the group consisting of a hydroxy-carboxylic acid imide, a
hydroxy-carboxylic acid di-imide, a hydroxy-carboxylic acid
ester-imide, and a hydroxy-carboxylic acid imide-amide.
[0014] The derivative of a hydroxy-carboxylic acid may be selected
from the group consisting of a hydroxy-carboxylic acid imide and a
hydroxy-carboxylic acid di-imide.
[0015] The derivative of a hydroxy-carboxylic acid may be
derivative of tartaric acid, an imide derivative of citric acid, or
mixtures thereof.
[0016] The derivative of a hydroxy-carboxylic acid may be imide
derivative of tartaric acid, an imide derivative of citric acid, or
mixtures thereof.
[0017] In one embodiment the derivative of a hydroxy-carboxylic
acid is either an ester or imide. The ester derivative of a
hydroxy-carboxylic acid may be a tartrate. The imide derivative of
a hydroxy-carboxylic acid may be a tartrimide.
[0018] In one embodiment the derivative of (or compound derived
from) a hydroxy-carboxylic acid may be imide derivative of a
hydroxy-carboxylic acid.
[0019] U.S. Patent Applications US 60/939,949 (filed May 24, 2007),
now WO2008/147704, and U.S. 60/939,952 (filed May 24, 2007), now WO
2008/147700, disclose suitable hydroxy-carboxylic acid compounds,
and methods of preparing the same.
[0020] Canadian Patent 1 183 125; US Patent Publication numbers
2006/0183647 and US-2006-0079413; U.S. Patent Application No.
60/867,402 (now WO2008/067259); and British Patent 2 105 743 A, all
disclose examples of suitable tartaric acid derivatives.
[0021] In one embodiment the amide, ester or imide derivative of a
hydroxy-carboxylic acid may be represented by Formula (1) (that is,
1a or 1b):
##STR00001##
wherein
[0022] n' is 0 to 10 for Formula (1b), and 1 to 10 for Formula
(1a);
[0023] p is 1 to 5;
[0024] Y and Y' are independently --O--, >NH, >NR.sup.3, or
an imide group formed by taking together both Y and Y' groups in
(1b) or two Y groups in (1a) and forming a R.sup.1--N<group
between two >C.dbd.O groups;
[0025] X is independently --CH.sub.2--, >CHR.sup.4,
>CR.sup.4R.sup.5, >CHOR.sup.6, >C(OH)CO.sub.2R.sup.6,
>C(CO.sub.2R.sup.6).sub.2, --CH.sub.3, --CH.sub.2R.sup.4 or
CHR.sup.4R.sup.5, --CH.sub.2OR.sup.6,
--CH(CO.sub.2R.sup.6).sub.2,.dbd.C--R.sup.6 (where =equals three
valences, and may only apply to Formula (1a)) or mixtures thereof
to fulfill the valence of Formula (1a) and/or (1b) (typically the
compound of Formula (1a) or (1b) has at least one X that is
hydroxyl-containing (i.e., >CHOR.sup.6, wherein R.sup.6 is
hydrogen));
[0026] R.sup.1 and R.sup.2 are independently hydrocarbyl groups,
typically containing 1 to 150, or 4 to 30, or 8 to 15 carbon
atoms;
[0027] R.sup.3 is a hydrocarbyl group;
[0028] R.sup.4 and R.sup.5 are independently keto-containing groups
(such as acyl groups), ester groups or hydrocarbyl groups, or
--OR.sup.6, or --CO.sub.2R.sup.6, or --OH (typically not more than
one --OH when X is >CR.sup.4R.sup.5); and
[0029] R.sup.6 is independently hydrogen or a hydrocarbyl group,
typically containing 1 to 150, or 4 to 30, or 8 to 15 carbon
atoms.
[0030] In one embodiment the compound of Formula (I) contains an
imide group. The imide group is typically formed by taking together
the Y and Y' groups and forming a R.sup.1--N<group between two
>C.dbd.O groups.
[0031] In one embodiment the compound of Formula (I) has m, n, X,
and R.sup.1, R.sup.2 and R.sup.6 defined as follows: m is 0 or 1, n
is 1 to 2, X is >CHOR.sup.6, and R.sup.1, R.sup.2 and R.sup.6
are independently hydrocarbyl groups containing 4 to 30 carbon
atoms.
[0032] In one embodiment Y and Y' are both --O--.
[0033] In one embodiment the compound of Formula (I) has m, n, X,
Y, Y' and R.sup.1, R.sup.2 and R.sup.6 defined as follows: m is 0
or 1, n is 1 to 2, X is >CHOR.sup.6; Y and Y' are both --O--,
and R', R.sup.2 and R.sup.6 are independently hydrogen or
hydrocarbyl groups containing 4 to 30 carbon atoms.
[0034] The di-esters, di-amides, ester-amide, ester-imide compounds
of Formula (1) may be prepared by reacting a dicarboxylic acid
(such as tartaric acid), with an amine or alcohol, optionally in
the presence of a known esterification catalyst. In the case of
ester-imide compounds it is necessary to have at least three
carboxylic acid groups (such as citric acid). The amine or alcohol
typically has sufficient carbon atoms to fulfill the requirements
of R.sup.1 and/or R.sup.2 as defined in Formula (1).
[0035] In one embodiment R.sup.1 and R.sup.2 are independently
linear or branched hydrocarbyl groups. In one embodiment the
hydrocarbyl groups are branched. In one embodiment the hydrocarbyl
groups are linear. The R.sup.1 and R.sup.2 may be incorporated into
Formula (I) by either an amine or an alcohol. The alcohol includes
both monohydric alcohol and polyhydric alcohol. The carbon atoms of
the alcohol may be linear chains, branched chains, or mixtures
thereof.
[0036] Examples of a suitable branched alcohol include
2-ethylhexanol, isotridecanol, Guerbet alcohols, or mixtures
thereof.
[0037] Examples of a monohydric alcohol include methanol, ethanol,
propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol,
decanol, undecanol, dodecanol, tridecanol, tetradecanol,
pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol,
eicosanol, or mixtures thereof. In one embodiment the monohydric
alcohol contains 5 to 20 carbon atoms.
[0038] The alcohol includes either a monohydric alcohol or a
polyhydric alcohol. Examples of a suitable polyhydric alcohol
include ethylene glycol, propylene glycol, 1,3-butylene glycol,
2,3-butylene glycol, 1,5-pentane diol, 1,6-hexane diol, glycerol,
sorbitol, pentaerythritol, trimethylolpropane, starch, glucose,
sucrose, methylglucoside, or mixtures thereof. In one embodiment
the polyhydric alcohol is used in a mixture along with a monohydric
alcohol. Typically, in such a combination the monohydric alcohol
constitutes at least 60 mole percent, or at least 90 mole percent
of the mixture.
[0039] The tartaric acid used for preparing the tartrates of the
invention can be commercially available, and it is likely to exist
in one or more isomeric forms such as d-tartaric acid, l-tartaric
acid, d,l-tartaric acid or mesotartaric acid, often depending on
the source (natural) or method of synthesis (from maleic acid). For
example a racemic mixture of d-tartaric acid and l-tartaric acid is
obtained from a catalysed oxidation of maleic acid with hydrogen
peroxide (with tungstic acid catalyst). These derivatives can also
be prepared from functional equivalents to the diacid readily
apparent to those skilled in the art, such as esters, acid
chlorides, or anhydrides.
[0040] When the compound of Formula (I) is derived from tartaric
acid, resultant tartrates may be solid, semi-solid, or liquid oil
depending on the particular alcohol used in preparing the tartrate.
For use as additives in a lubricating composition the tartrates are
advantageously soluble and/or stably dispersible in such oleaginous
compositions. For example, compositions intended for use in oils
are typically oil-soluble and/or stably dispersible in an oil in
which they are to be used. The term "oil-soluble" as used in this
specification and appended claims does not necessarily mean that
all the compositions in question are miscible or soluble in all
proportions in all oils. Rather, it is intended to mean that the
composition is soluble in an oil (mineral, synthetic, etc.) or in a
formulated lubricant in which it is intended to function, to an
extent which permits the solution to exhibit one or more of the
desired properties. Similarly, it is not necessary that such
"solutions" be true solutions in the strict physical or chemical
sense. They may instead be micro-emulsions or colloidal dispersions
which, for the purpose of this invention, exhibit properties
sufficiently close to those of true solutions to be, for practical
purposes, interchangeable with them within the context of this
invention.
[0041] The derivative of (or compound derived from) a
hydroxy-carboxylic acid may be present in the lubricating
composition in an amount in the range of 0.1 wt % to 5 wt %, or 0.2
wt % to 3 wt %, or greater than 0.2 wt % to 3 wt % of the
lubricating composition.
Amine Salt of a Phosphoric Acid Ester
[0042] In one embodiment the lubricating composition further
includes an amine salt of a phosphoric acid ester. The phosphoric
acid utilised to prepare the phosphoric acid ester amine salt may
be either a phosphoric acid or a thiophosphoric acid.
[0043] The amine salt of a phosphoric acid ester may contain ester
groups each having 1 to 30, 6 to 30, 8 to 30, 10 to 24 or 12 to 20,
or 16 to 20 carbon atoms, with the proviso that a portion or all of
ester groups are sufficiently long to solubilise the amine salt of
a phosphoric acid ester in an oil of lubricating viscosity.
Typically ester groups containing 4 or more carbon atoms are
particularly useful.
[0044] Examples of suitable ester groups include isopropyl,
methyl-amyl (may also be referred to as 1,3-dimethyl butyl),
2-ethylhexyl, heptyl, octyl, nonyl, decyl, dodecyl, butadecyl,
pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl,
or mixtures thereof.
[0045] In one embodiment the ester groups is selected from the
group consisting of isopropyl, methyl-amyl (may also be referred to
as 1,3-dimethyl butyl), 2-ethylhexyl, heptyl, octyl, nonyl, decyl,
and mixtures thereof.
[0046] The amines which may be suitable for use as the amine salt
include primary amines, secondary amines, tertiary amines, and
mixtures thereof. The amines include those with at least one
hydrocarbyl group, or, in certain embodiments, two or three
hydrocarbyl groups. The hydrocarbyl groups may contain 2 to 30
carbon atoms, or in other embodiments 8 to 26, or 10 to 20, or 13
to 19 carbon atoms.
[0047] Primary amines include ethylamine, propylamine, butylamine,
2-ethylhexylamine, octylamine, and dodecylamine, as well as linear
amines as n-octylamine, n-decylamine, n-dodecylamine,
n-tetradecylamine, n-hexadecyl-amine, n-octadecylamine and
oleyamine. Other useful fatty amines include commercially available
fatty amines such as "Armeen.RTM." amines (products available from
Akzo Chemicals, Chicago, Ill.), such as Armeen C, Armeen O, Armeen
OL, Armeen T, Armeen HT, Armeen S and Armeen SD, wherein the letter
designation relates to the fatty group, such as coco, oleyl,
tallow, or stearyl groups.
[0048] Examples of suitable secondary amines include dimethylamine,
diethylamine, dipropylamine, dibutylamine, diamylamine,
dihexylamine, diheptylamine, methylethylamine, ethylbutylamine,
ethylamylamine, dicocoamine and di-2-ethylhexylamine. The secondary
amines may be cyclic amines such as piperidine, piperazine and
morpholine.
[0049] The amine may also be a tertiary-aliphatic primary amine.
The aliphatic group in this case may be an alkyl group containing 2
to 30, or 6 to 26, or 8 to 24 carbon atoms. Tertiary alkyl amines
include monoamines such as tert-butylamine, tert-hexylamine,
1-methyl-1-amino-cyclohexane, tert-octylamine, tert-decylamine,
tertdodecylamine, tert-tetradecylamine, tert-hexadecylamine,
tert-octadecylamine, tert-tetracosanylamine, and
tert-octacosanylamine.
[0050] The amine salt of a phosphorus acid ester may be a reaction
product of a C.sub.12-20 alkyl phosphoric acid with a tertiary
C.sub.11-22 alkyl primary amine.
[0051] In one embodiment the amine salt of a phosphorus acid ester
includes an amine with C11 to C14 tertiary alkyl primary amino
groups or mixtures thereof. In one embodiment the amine salt of a
phosphorus compound includes an amine with C14 to C18 tertiary
alkyl primary amines or mixtures thereof. In one embodiment the
amine salt of a phosphorus compound includes an amine with C18 to
C22 tertiary alkyl primary amines or mixtures thereof.
[0052] In one embodiment the amine salt of a phosphorus acid ester
includes the reaction product of octadecenyl phosphoric acid with
Primene 81R.TM..
[0053] Mixtures of amines may also be used in the invention. In one
embodiment a useful mixture of amines is "Primene.TM. 81R" and
"Primene.TM. JMT." Primene.TM. 81R and Primene.TM. JMT (both
produced and sold by Rohm & Haas) are mixtures of C11 to C14
tertiary alkyl primary amines and C18 to C22 tertiary alkyl primary
amines respectively.
[0054] In one embodiment the amine salt of a phosphorus acid ester
is the reaction product of a C.sub.14 to C.sub.18 alkylated
phosphoric acid with Primene 81R.TM. which is a mixture of C11 to
C14 tertiary alkyl primary amines.
[0055] Examples of the amine salt of a phosphorus acid ester
include the reaction product(s) of isopropyl, methyl-amyl
(1,3-dimethyl butyl or mixtures thereof), 2-ethylhexyl, heptyl,
octyl, nonyl or decyl dithiophosphoric acids with ethylene diamine,
morpholine, or Primene 81R.TM., and mixtures thereof.
[0056] Examples of the amine salt of a phosphorus acid ester
include the reaction product(s) of tetradecyl, pentadecyl,
hexadecyl, heptadecyl, octadecyl, nonadecyl or eicosyl
dithiophosphoric acids with ethylene diamine, morpholine, or
Primene 81 R.TM., and mixtures thereof. In one embodiment the amine
salt of a phosphorus acid ester includes the reaction product of
octadecenyl dithiophosphoric acid with Primene 81R.TM..
[0057] In one embodiment the amine salt of a phosphorus compound
may be an amine salt of either (i) a hydroxy-substituted di-ester
of phosphoric acid, or (ii) a phosphorylated hydroxy-substituted
di- or tri-ester of phosphoric acid. A more detailed description of
this type of compound is described in International Publication WO
2008/094759.
[0058] In one embodiment the amine salt of a phosphoric acid is a
compound described in U.S. Pat. No. 3,197,405. In one embodiment
the amine salt of a phosphorus compound other than those disclosed
above, may be prepared by any one of examples 1 to 25 of U.S. Pat.
No. 3,197,405.
[0059] In one embodiment the amine salt of a phosphorus compound
other than those disclosed above, is a reaction product prepared
from a dithiophosphoric acid is reacting with an epoxide or a
glycol. This reaction product is further reacted with a phosphorus
acid, anhydride, or lower ester (where "lower" signifies 1 to 8, or
1 to 6, or 1 to 4, or 1 to 2 carbon atoms in the alcohol-derived
portion of the ester). The epoxide includes an aliphatic epoxide or
a styrene oxide. Examples of useful epoxides include ethylene
oxide, propylene oxide, butene oxide, octene oxide, dodecene oxide,
styrene oxide and the like. In one embodiment the epoxide is
propylene oxide. The glycols include aliphatic glycols having 2 to
12, or 2 to 6, or 2 to 3 carbon atoms. The dithiophosphoric acids,
glycols, epoxides, inorganic phosphorus reagents and methods of
reacting the same are described in U.S. Pat. Nos. 3,197,405 and
3,544,465. The resulting acids are then salted with amines.
[0060] An example of suitable dithiophosphoric acid based product
is prepared by adding phosphorus pentoxide (about 64 grams) at
58.degree. C. over a period of 45 minutes to 514 grams of
hydroxypropyl O,O-di(1,3-dimethylbutyl)phosphorodithioate (prepared
by reacting di(1,3-dimethylbutyl)-phosphorodithioic acid with 1.3
moles of propylene oxide at 25.degree. C.). The mixture is heated
at 75.degree. C. for 2.5 hours, mixed with a diatomaceous earth and
filtered at 70.degree. C. The filtrate contains 11.8% by weight
phosphorus, 15.2% by weight sulphur, and an acid number of 87
(bromophenol blue).
[0061] The amine salt of a phosphorus acid ester may be present at
0 wt % to 5 wt %, or 0.01 wt % to 5 wt %, or 0.01 wt % to 2 wt %,
or 0.25 wt % to 1 wt % of the lubricating composition.
Oils of Lubricating Viscosity
[0062] The lubricating composition comprises an oil of lubricating
viscosity. Such oils include natural and synthetic oils, oil
derived from hydrocracking, hydrogenation, and hydrofinishing,
unrefined, refined and re-refined oils and mixtures thereof.
[0063] Unrefined oils are those obtained directly from a natural or
synthetic source generally without (or with little) further
purification treatment.
[0064] Refined oils are similar to the unrefined oils except they
have been further treated in one or more purification steps to
improve one or more properties. Purification techniques are known
in the art and include solvent extraction, secondary distillation,
acid or base extraction, filtration, percolation and the like.
[0065] Re-refined oils are also known as reclaimed or reprocessed
oils, and are obtained by processes similar to those used to obtain
refined oils and often are additionally processed by techniques
directed to removal of spent additives and oil breakdown
products.
[0066] Natural oils useful in making the inventive lubricants
include animal oils (e.g., lard oil), vegetable oils (e.g., castor
oil), mineral lubricating oils such as liquid petroleum oils and
solvent-treated or acid-treated mineral lubricating oils of the
paraffinic, naphthenic or mixed paraffinic-naphthenic types and
oils derived from coal or shale or mixtures thereof.
[0067] Synthetic lubricating oils are useful and include
hydrocarbon oils such as polymerised and interpolymerised olefins
(e.g., polybutylenes, polypropylenes, propyleneisobutylene
copolymers); poly(1-hexenes), poly(1-octenes), poly(1-decenes), and
mixtures thereof; alkylbenzenes (e.g. dodecylbenzenes,
tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)-benzenes);
polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls);
alkylated diphenyl ethers and alkylated diphenyl sulphides and the
derivatives, analogs and homologs thereof or mixtures thereof.
[0068] Other synthetic lubricating oils include polyol esters (such
as Priolube.RTM.3970), diesters, liquid esters of
phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl
phosphate, and the diethyl ester of decane phosphonic acid), or
polymeric tetrahydrofurans. Synthetic oils may be produced by
Fischer-Tropsch reactions and typically may be hydroisomerised
Fischer-Tropsch hydrocarbons or waxes. In one embodiment oils may
be prepared by a Fischer-Tropsch gas-to-liquid synthetic procedure
as well as other gas-to-liquid oils.
[0069] Oils of lubricating viscosity may also be defined as
specified in the American Petroleum Institute (API) Base Oil
Interchangeability Guidelines. The five base oil groups are as
follows: Group I (sulphur content >0.03 wt %, and/or <90 wt %
saturates, viscosity index 80-120); Group II (sulphur content
.ltoreq.0.03 wt %, and .gtoreq.90 wt % saturates, viscosity index
80-120); Group III (sulphur content .ltoreq.0.03 wt %, and
.gtoreq.90 wt % saturates, viscosity index .gtoreq.120); Group IV
(all polyalphaolefins (PAOs)); and Group V (all others not included
in Groups I, II, III, or IV). The oil of lubricating viscosity
includes an API Group I, Group II, Group III, Group IV, Group V oil
or mixtures thereof. Often the oil of lubricating viscosity is an
API Group I, Group II, Group III, Group IV oil or mixtures thereof.
Alternatively the oil of lubricating viscosity is often an API
Group II, Group III or Group IV oil or mixtures thereof.
[0070] The amount of the oil of lubricating viscosity present is
typically the balance remaining after subtracting from 100 wt % the
sum of the amount of the borated phospholipid, the amine salt of a
phosphoric acid ester, and the other performance additives.
[0071] The lubricating composition may be in the form of a
concentrate and/or a fully formulated lubricant. If the lubricating
composition disclosed herein is in the form of a concentrate (which
may be combined with additional oil to form, in whole or in part, a
finished lubricant), the ratio of the of components of the
lubricating composition to the oil of lubricating viscosity and/or
to diluent oil include the ranges of 1:99 to 99:1 by weight or
80:20 to 10:90 by weight. When in the form of a concentrate, the
present invention may be part of a full lubricant composition or
may be a supplemental additive package or "top treat".
Other Performance Additives
[0072] The composition of the invention optionally further includes
at least one other performance additive. The other performance
additives include dispersants, metal deactivators, detergents,
viscosity modifiers, extreme pressure agents (typically boron-
and/or sulphur- and/or phosphorus-containing), antiwear agents,
antioxidants (such as hindered phenols, aminic antioxidants or
molybdenum compounds), corrosion inhibitors, foam inhibitors,
demulsifiers, pour point depressants, seal swelling agents,
friction modifiers and mixtures thereof.
[0073] The total combined amount of the other performance additives
(excluding the viscosity modifiers) present on an oil free basis
may include ranges of 0 wt % to 25 wt %, or 0.01 wt % to 20 wt %,
or 0.1 wt % to 15 wt % or 0.5 wt % to 10 wt %, or 1 to 5 wt % of
the composition. Although one or more of the other performance
additives may be present, it is common for the other performance
additives to be present in different amounts relative to each
other.
[0074] In one embodiment the lubricating composition is free of
molybdenum-containing additives.
Viscosity Modifiers
[0075] In one embodiment the lubricating composition further
includes one or more viscosity modifiers.
[0076] When present the viscosity modifier may be present in an
amount of 0.5 wt % to 70 wt %, 1 wt % to 60 wt %, or 5 wt % to 50
wt %, or 10 wt % to 50 wt % of the lubricating composition.
[0077] Viscosity modifiers include (a) polymethacrylates, (b)
esterified copolymers of (i) a vinyl aromatic monomer and (ii) an
unsaturated carboxylic acid, anhydride, or derivatives thereof, (c)
esterified interpolymers of (i) an alpha-olefin; and (ii) an
unsaturated carboxylic acid, anhydride, or derivatives thereof, or
(d) hydrogenated copolymers of styrene-butadiene, (e)
ethylene-propylene copolymers, (f) polyisobutenes, (g) hydrogenated
styrene-isoprene polymers, (h) hydrogenated isoprene polymers, or
(i) mixtures thereof.
[0078] In one embodiment the viscosity modifier includes (a) a
polymethacrylate, (b) an esterified copolymer of (i) a vinyl
aromatic monomer; and (ii) an unsaturated carboxylic acid,
anhydride, or derivatives thereof, (c) an esterified interpolymer
of (i) an alpha-olefin; and (ii) an unsaturated carboxylic acid,
anhydride, or derivatives thereof, or (d) mixtures thereof.
Extreme Pressure Agents
[0079] Extreme pressure agents include compounds containing boron
and/or sulphur and/or phosphorus.
[0080] The extreme pressure agent may be present in the lubricating
composition at 0 wt % to 20 wt %, or 0.05 wt % to 10 wt %, or 0.1
wt % to 8 wt % of the lubricating composition.
[0081] In one embodiment the extreme pressure agent is a
sulphur-containing compound. In one embodiment the
sulphur-containing compound may be a sulphurised olefin, a
polysulphide, or mixtures thereof.
[0082] Examples of the sulphurised olefin include a sulphurised
olefin derived from propylene, isobutylene, pentene; an organic
sulphide and/or polysulphide including benzyldisulphide;
bis-(chlorobenzyl)disulphide; dibutyl tetrasulphide; di-tertiary
butyl polysulphide; and sulphurised methyl ester of oleic acid, a
sulphurised alkylphenol, a sulphurised dipentene, a sulphurised
terpene, a sulphurised Diels-Alder adduct, an alkyl sulphenyl
N'N-dialkyl dithiocarbamates; or mixtures thereof. In one
embodiment the sulphurised olefin includes a sulphurised olefin
derived from propylene, isobutylene, pentene or mixtures
thereof.
[0083] In one embodiment the extreme pressure agent
sulphur-containing compound includes a dimercaptothiadiazole or
derivative, or mixtures thereof. Examples of the
dimercaptothiadiazole include 2,5-dimercapto-1,3,4-thia-diazole or
a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole, or
oligomers thereof. The oligomers of hydrocarbyl-substituted
2,5-dimercapto-1,3,4-thiadiazole typically form by forming a
sulphur-sulphur bond between 2,5-dimercapto-1,3,4-thiadiazole units
to form derivatives or oligomers of two or more of said thiadiazole
units. Suitable 2,5-dimercapto-1,3,4-thiadiazole derived compounds
include 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or
2-tert-nonyldithio-5-mercapto-1,3,4-thiadiazole.
[0084] The number of carbon atoms on the hydrocarbyl substituents
of the hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole
typically include 1 to 30, or 2 to 20, or 3 to 16.
[0085] In one embodiment the extreme pressure agent includes a
boron-containing compound. The boron-containing compound includes a
borate ester (which in some embodiments may also be referred to as
a borated epoxide), a borated alcohol, a borated dispersant or
mixtures thereof. In one embodiment the boron-containing compound
may be a borate ester or a borated alcohol.
[0086] The borate ester may be prepared by the reaction of a boron
compound and at least one compound selected from epoxy compounds,
halohydrin compounds, epihalohydrin compounds, alcohols and
mixtures thereof. The alcohols include dihydric alcohols, trihydric
alcohols or higher alcohols, with the proviso for one embodiment
that hydroxyl groups are on adjacent carbon atoms i.e. vicinal.
[0087] Boron compounds suitable for preparing the borate ester
include the various forms selected from the group consisting of
boric acid (including metaboric acid, HBO.sub.2, orthoboric acid,
H.sub.3BO.sub.3, and tetraboric acid, H.sub.2B.sub.4O.sub.7), boric
oxide, boron trioxide and alkyl borates. The borate ester may also
be prepared from boron halides.
[0088] In one embodiment suitable borate ester compounds include
tripropyl borate, tributyl borate, tripentyl borate, trihexyl
borate, triheptyl borate, trioctyl borate, trinonyl borate and
tridecyl borate.
[0089] In one embodiment the borate ester compounds include
tributyl borate, tri-2-ethylhexyl borate or mixtures thereof.
[0090] In one embodiment, the boron-containing compound is a
borated dispersant, typically derived from an N-substituted long
chain alkenyl succinimide. In one embodiment the borated dispersant
includes a polyisobutylene succinimide. Borated dispersants are
described in more detail in U.S. Pat. Nos. 3,087,936; and U.S. Pat.
No. 3,254,025.
[0091] In one embodiment the borated dispersant may be used in
combination with a sulphur-containing compound or a borate
ester.
[0092] In one embodiment the extreme pressure agent is other than a
borated dispersant.
[0093] The number average molecular weight of the hydrocarbon from
which the long chain alkenyl group was derived includes ranges of
350 to 5000, or 500 to 3000, or 550 to 1500. The long chain alkenyl
group may have a number average molecular weight of 550, or 750, or
950 to 1000.
[0094] The N-substituted long chain alkenyl succinimides are
borated using a variety of agents including boric acid (for
example, metaboric acid, HBO.sub.2, orthoboric acid,
H.sub.3BO.sub.3, and tetraboric acid, H.sub.2B.sub.4O.sub.7), boric
oxide, boron trioxide, and alkyl borates. In one embodiment the
borating agent is boric acid which may be used alone or in
combination with other borating agents.
[0095] The borated dispersant may be prepared by blending the boron
compound and the N-substituted long chain alkenyl succinimides and
heating them at a suitable temperature, such as, 80.degree. C. to
250.degree. C., or 90.degree. C. to 230.degree. C., or 100.degree.
C. to 210.degree. C., until the desired reaction has occurred. The
molar ratio of the boron compounds to the N-substituted long chain
alkenyl succinimides may have ranges including 10:1 to 1:4, or 4:1
to 1:3; or the molar ratio of the boron compounds to the
N-substituted long chain alkenyl succinimides may be 1:2. An inert
liquid may be used in performing the reaction. The liquid may
include toluene, xylene, chlorobenzene, dimethylformamide or
mixtures thereof.
[0096] Friction modifiers (other than (a) a borated phospholipid,
and (b) an amine salt of a phosphoric acid ester) include fatty
amines, esters such as borated glycerol esters, fatty phosphites,
fatty acid amides, fatty epoxides, borated fatty epoxides,
alkoxylated fatty amines, borated alkoxylated fatty amines, metal
salts of fatty acids, or fatty imidazolines, condensation products
of carboxylic acids and polyalkylene-polyamines.
[0097] In one embodiment the lubricating composition may contain
phosphorus- or sulphur-containing antiwear agents other than
compounds described as an extreme pressure agent of the amine salt
of a phosphoric acid ester described above. Examples of the
antiwear agent may include a non-ionic phosphorus compound
(typically compounds having phosphorus atoms with an oxidation
state of +3 or +5), a metal dialkyldithiophosphate (typically zinc
dialkyldithiophosphates), a metal mono- or di-alkylphosphate
(typically zinc phosphates), or mixtures thereof.
[0098] The non-ionic phosphorus compound includes a phosphite
ester, a phosphate ester, or mixtures thereof. A more detailed
description of the non-ionic phosphorus compound include column 9,
line 48 to column 11, line 8 of U.S. Pat. No. 6,103,673.
[0099] In one embodiment the lubricating composition of the
invention further includes a dispersant. The dispersant may be a
succinimide dispersant (for example N-substituted long chain
alkenyl succinimides), a Mannich dispersant, an ester-containing
dispersant, a condensation product of a fatty hydrocarbyl
monocarboxylic acylating agent with an amine or ammonia, an alkyl
amino phenol dispersant, a hydrocarbyl-amine dispersant, a
polyether dispersant or a polyetheramine dispersant.
[0100] In one embodiment the succinimide dispersant includes a
polyisobutylene-substituted succinimide, wherein the
polyisobutylene from which the dispersant is derived may have a
number average molecular weight of 400 to 5000, or 950 to 1600.
[0101] Succinimide dispersants and their methods of preparation are
more fully described in U.S. Pat. Nos. 4,234,435 and 3,172,892.
[0102] Suitable ester-containing dispersants are typically high
molecular weight esters. These materials are described in more
detail in U.S. Pat. No. 3,381,022.
[0103] In one embodiment the dispersant includes a borated
dispersant. Typically the borated dispersant includes a succinimide
dispersant including a polyisobutylene succinimide, wherein the
polyisobutylene from which the dispersant is derived may have a
number average molecular weight of 400 to 5000. Borated dispersants
are described in more detail above within the extreme pressure
agent description.
[0104] Dispersant viscosity modifiers (often referred to as DVMs)
include functionalised polyolefins, for example, ethylene-propylene
copolymers that have been functionalized with the reaction product
of maleic anhydride and an amine, a polymethacrylate functionalised
with an amine, or esterified styrene-maleic anhydride copolymers
reacted with an amine may also be used in the composition of the
invention.
[0105] Corrosion inhibitors include 1-amino-2-propanol, octylamine
octanoate, condensation products of dodecenyl succinic acid or
anhydride and/or a fatty acid such as oleic acid with a
polyamine.
[0106] Metal deactivators include derivatives of benzotriazoles
(typically tolyltriazole), 1,2,4-triazoles, benzimidazoles,
2-alkyldithiobenzimidazoles or 2-alkyldithiobenzothiazoles. The
metal deactivators may also be described as corrosion
inhibitors.
[0107] Foam inhibitors include copolymers of ethyl acrylate and
2-ethylhexylacrylate and optionally vinyl acetate.
[0108] Demulsifiers include trialkyl phosphates, and various
polymers and copolymers of ethylene glycol, ethylene oxide,
propylene oxide, or mixtures thereof.
[0109] Pour point depressants including esters of maleic
anhydride-styrene, polymethacrylates, polyacrylates or
polyacrylamides.
[0110] Seal swell agents including Exxon Necton-37.TM. (FN 1380)
and Exxon Mineral Seal Oil.TM. (FN 3200).
INDUSTRIAL APPLICATION
[0111] The limited slip differential typically incorporates a
self-contained lubricant supply isolated from the lubricant
disposed in the differential housing or carrier. The self-contained
lubricant of the limited slip differential is generally different
from the lubricant supplied to a manual transmission or an
automatic transmission fluid. In both the manual and automatic
transmission systems not comprising a limited slip differential,
one lubricant is typically sufficient to lubricate all of the
transmission constituents.
[0112] An axle gear may have any one of a number of different types
of differentials. A differential typically has three major
functions. The first function is to transmit engine power to the
wheels. The second function is act as the final gear reduction in
the vehicle, slowing the rotational speed from the transmission to
the wheels. The third function is to transmit the power to the
wheels while allowing them to rotate at different speeds. A number
of differentials are known and include an open differential, a
clutch-type limited slip differential, a viscous coupling
differential, a Torsen differential and a locking differential. All
of these differentials may be generically referred to as axle
gears.
[0113] Axle gears typically require a lubricant. The lubricant
formulation is dependent on the type of axle gear, and the
operating conditions of the axle gear. For example, an open
differential axle gear is believed to require antiwear and/or
extreme pressure additives. In contrast, a limited slip
differential typically requires a friction modifier because, in
addition to an open differential (known from many axle fluids), a
spring pack and a clutch pack are typically present. The clutch
pack may contain one or more reaction plates (often made from
steel) and one or more friction plates. The friction plates are
known, and may be made from a number of materials including paper,
carbon, graphite, steel and a composite.
[0114] The lubricating composition suitable for the limited slip
differential may have a sulphur content in the range of 0.3 wt % to
5 wt %, or 0.5 wt % to 5 wt %, or 0.5 wt % to 3 wt % or 0.8 wt % to
2.5 wt %, or 1 wt % to 2 wt %.
[0115] In one embodiment the lubricating composition suitable for
the limited slip differential may be a fully formulated fluid.
[0116] In one embodiment the lubricating composition suitable for
the limited slip differential may be a top treat concentrate.
[0117] When the lubricating composition is in the form of a top
treat concentrate, the concentrate may be added at 0.2 wt % to 10
wt %, or 0.5 wt % to 7 wt % relative to the amount of lubricant in
a limited slip differential.
[0118] The following examples provide illustrations of the
invention. These examples are non exhaustive and are not intended
to limit the scope of the invention.
EXAMPLES
Example 1 (EX1)
[0119] 1271 g of a commercially available limited slip axle fluid
is top-treated with 1.74 wt % of oleyl tartrimide.
[0120] Comparative Example 1 (CE1) is the same commercially
available axle fluid as EX1, except the oleyl tartrimides is not
added.
[0121] The examples prepared (EX1 and CE1) are evaluated using a
mu-PVT (mu, friction coefficient, obtained at varying Pressures,
Velocities and Temperatures) friction screen test on a Low Speed
SAE #2 test machine. This friction screen test utilises a Dana.TM.
Model 80 plate configuration with Miba.TM. MC-631 friction material
with the following plate configuration (S--F--S--F--S--F--S--F--S,
where S is a steel plate, and F is a friction plate) thereby
producing 8 active friction surfaces. The test runs through a map
of varying apply pressures and plate differential speeds while
holding the temperature constant at 50.degree. C. There are six
apply pressure settings of 190, 380, 570, 760, 950 and 1075 kPa. At
each apply pressure setting, four distinct plate differential
speeds of 15, 50, 85 and 120 rpm are utilised. At each plate
differential speed, twenty five repeat cycles are conducted. Each
test has a total of 600 cycles (six pressures.times.four
speeds.times.twenty-five cycles). A 600 cycle mu-PVT or friction
map is conducted before and after a durability cycle to assess the
change in friction performance. The durability cycle consists of a
constant apply pressure of 570 kPa at a fluid temperature of
80.degree. C. and cycling the plate differential speed between 120
and 0 rpm. One complete cycle consists of 5 seconds at 0 rpm and 5
seconds at 120 rpm. This is repeated for a total of 2500 cycles.
The primary measurement is an NVH rating that depicts the variation
in the torque signal during each discrete speed event or the
difference between the minimum and maximum friction coefficient
obtained during the event. This measurement assigns a number to the
magnitude of the torque signal variation according to the following
table:
TABLE-US-00001 Torque Signal Variation NVH Ratine Between 0 and
0.02 Coefficient of Friction Units 0 Between 0.02 and 0.04
Coefficient of Friction Units 1 Between 0.04 and 0.06 Coefficient
of Friction Units 2 Between 0.06 and 0.08 Coefficient of Friction
Units 3 Between 0.08 and 0.10 Coefficient of Friction Units 4
Between 0.10 and 0.12 Coefficient of Friction Units 5 Between 0.12
and 0.14 Coefficient of Friction Units 6 Between 0.14 and 0.16
Coefficient of Friction Units 7
[0122] These ratings are summed up for all cycles completed at one
apply pressure and speed setting and then for the entire test. The
maximum NVH rating is 9600 points (6 pressures.times.4
speeds.times.25 repeats.times.8 NVH Rating=4800, .times.2 for pre
and post durability evaluation =9600). This would be considered
very poor friction performance. The minimum NVH rating is 0 points.
This would be considered excellent friction performance. The Post
Durability NVH rating for EX1 is 152, and 565 for CE1. The total
NVH rating for EX1 and CE1 is 471 and 728 respectively.
[0123] The data obtained from the tests indicates that the
lubricating composition of the invention is capable of providing a
limited slip differential with a low tendency towards post
durability NVH often manifested as chatter.
[0124] It is known that some of the materials described above may
interact in the final formulation, so that the components of the
final formulation may be different from those that are initially
added. The products formed thereby, including the products formed
upon employing lubricant composition of the present invention in
its intended use, may not be susceptible of easy description.
Nevertheless, all such modifications and reaction products are
included within the scope of the present invention; the present
invention encompasses lubricant composition prepared by admixing
the components described above.
[0125] As used herein, the term "hydrocarbyl substituent" or
"hydrocarbyl group" is used in its ordinary sense, which is
well-known to those skilled in the art. Specifically, it refers to
a group having a carbon atom directly attached to the remainder of
the molecule and having predominantly hydrocarbon character.
Examples of hydrocarbyl groups include:
[0126] (i) hydrocarbon substituents, that is, aliphatic (e.g.,
alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl)
substituents, and aromatic-, aliphatic-, and alicyclic-substituted
aromatic substituents, as well as cyclic substituents wherein the
ring is completed through another portion of the molecule (e.g.,
two substituents together form a ring);
[0127] (ii) substituted hydrocarbon substituents, that is,
substituents containing non-hydrocarbon groups which, in the
context of this invention, do not alter the predominantly
hydrocarbon nature of the substituent (e.g., halo (especially
chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto,
nitro, nitroso, and sulphoxy);
[0128] (iii) hetero substituents, that is, substituents which,
while having a predominantly hydrocarbon character, in the context
of this invention, contain other than carbon in a ring or chain
otherwise composed of carbon atoms; and
[0129] (iv) heteroatoms include sulphur, oxygen, nitrogen, and
encompass substituents as pyridyl, furyl, thienyl and imidazolyl.
In general, no more than two, preferably no more than one,
non-hydrocarbon substituent will be present for every ten carbon
atoms in the hydrocarbyl group; typically, there will be no
non-hydrocarbon substituents in the hydrocarbyl group.
[0130] Each of the documents referred to above is incorporated
herein by reference. Except in the Examples, or where otherwise
explicitly indicated, all numerical quantities in this description
specifying amounts of materials, reaction conditions, molecular
weights, number of carbon atoms, and the like, are to be understood
as modified by the word "about." Unless otherwise indicated, each
chemical or composition referred to herein should be interpreted as
being a commercial grade material which may contain the isomers,
by-products, derivatives, and other such materials which are
normally understood to be present in the commercial grade. However,
the amount of each chemical component is presented exclusive of any
solvent or diluent oil, which may be customarily present in the
commercial material, unless otherwise indicated. It is to be
understood that the upper and lower amount, range, and ratio limits
set forth herein may be independently combined. Similarly, the
ranges and amounts for each element of the invention may be used
together with ranges or amounts for any of the other elements.
[0131] While the invention has been explained in relation to its
preferred embodiments, it is to be understood that various
modifications thereof will become apparent to those skilled in the
art upon reading the specification. Therefore, it is to be
understood that the invention disclosed herein is intended to cover
such modifications as fall within the scope of the appended
claims.
* * * * *