U.S. patent application number 10/699508 was filed with the patent office on 2005-05-05 for high throughput screening methods for lubricating oil compositions.
Invention is credited to Balk, Thomas J., Wollenberg, Robert H..
Application Number | 20050095717 10/699508 |
Document ID | / |
Family ID | 34550983 |
Filed Date | 2005-05-05 |
United States Patent
Application |
20050095717 |
Kind Code |
A1 |
Wollenberg, Robert H. ; et
al. |
May 5, 2005 |
High throughput screening methods for lubricating oil
compositions
Abstract
A method for determining oxidation stability for a plurality of
different lubricating oil composition samples is provided. The
methods can advantageously be optimized using combinatorial
chemistry, in which a database of combinations of lubricating oil
compositions is generated. As market conditions vary and/or product
requirements or customer specifications change, conditions suitable
for forming desired products can be identified with little or no
downtime.
Inventors: |
Wollenberg, Robert H.;
(Orinda, CA) ; Balk, Thomas J.; (San Francisco,
CA) |
Correspondence
Address: |
Michael E. Carmen, Esq.
DILWORTH & BARRESE, LLP
333 Earle Ovington Blvd.
Uniondale
NY
11553
US
|
Family ID: |
34550983 |
Appl. No.: |
10/699508 |
Filed: |
October 31, 2003 |
Current U.S.
Class: |
436/60 ;
422/400 |
Current CPC
Class: |
G01N 33/2888 20130101;
Y10T 436/12 20150115; Y10T 436/11 20150115 |
Class at
Publication: |
436/060 ;
422/061 |
International
Class: |
G01N 033/03 |
Claims
What is claimed is:
1. A high throughput method for screening lubricating oil
compositions, under program control, comprising: (a) providing a
plurality of different lubricating oil composition samples
comprising (i) a major amount of at least one base oil of
lubricating viscosity and (ii) a minor amount of at least one
lubricating oil additive, each sample being in a respective one of
a plurality of test receptacles; (b) measuring the oxidation
stability of each sample to provide oxidation stability data for
each sample; and, (c) outputting the results of step (b).
2. The method of claim 1, wherein the base oil is a natural or
synthetic oil.
3. The method of claim 1, wherein the lubricating oil additive is
selected from the group consisting of antioxidants, anti-wear
agents, detergents, rust inhibitors, dehazing agents, demulsifying
agents, metal deactivating agents, friction modifiers, pour point
depressants, antifoaming agents, co-solvents, package
compatibilisers, corrosion-inhibitors, ashless dispersants, dyes,
extreme pressure agents and mixtures thereof.
4. The method of claim 1, wherein the step of measuring the
oxidation stability of each sample comprises exposing the sample to
oxygen at a predetermined temperature for a predetermined time
period and determining the amount of oxygen consumed by the
sample.
5. The method of claim 1, wherein the step of measuring the
oxidation stability of each sample comprises exposing the sample to
a predetermined amount of oxygen at a predetermined temperature for
a predetermined time period and determining the amount of time
required for the sample to consume the predetermined quantity of
oxygen.
6. The method of claim 1, wherein the step of measuring the
oxidation stability of each sample comprises subjecting the sample
to oxidation reaction conditions in the presence of a substrate and
determining the amount of deposit formed on the substrate after a
predetermined period of reaction time.
7. The method of claim 1, wherein the step of measuring the
oxidation stability of each sample comprises using infrared
spectroscopy.
8. The method of claim 7, wherein the infrared spectroscopy is
Fourier-transform infrared spectroscopy (FTIR).
9. The method of claim 1, wherein the step of measuring the
oxidation stability of each sample is determined by differential
scanning calorimetry.
10. The method of claim 1, wherein in step (c) the results of step
(b) for each sample are transmitted to a computer, wherein the
computer compares the results with a predetermined value delimiting
a failure or passing of the results, and the computer identifies
failed samples to preclude further testing of the failed
samples.
11. The method of claim 1, wherein the step of outputting comprises
storing the results of step (b) on a data carrier.
12. The method of claim 1, further comprising the step of using the
results of step (b) as a basis for obtaining a result of further
calculations.
13. The method of claim 11, further comprising the step of
transmitting the results of step (b) to a data carrier at a remote
location.
14. The method of claim 12, further comprising the step of
transmitting the results of further calculations to a remote
location.
15. A system for screening lubricating oil composition samples,
under program control, comprising: a) a plurality of test
receptacles, each containing a different lubricating oil
composition sample comprising (i) a major amount of at least one
base oil of lubricating viscosity and (ii) a minor amount of at
least one lubricating oil additive; b) a computer controller for
selecting individual samples for testing; c) receptacle moving
means responsive to instructions from the computer controller for
individually moving the selected samples to a testing station for
measuring oxidation stability of the selected samples; d) means for
measuring the oxidation stability of the selected samples to obtain
oxidation stability data and for transferring the oxidation
stability data to the computer controller.
16. The system of claim 15, wherein the receptacle moving means
comprises a movable carriage.
17. The system of claim 15, wherein the receptacle moving means
comprises a robotic assembly having a movable arm for grasping and
moving a selected individual receptacle.
18. The system of claim 15, wherein the receptacle moving means
comprises means for agitating the test receptacles.
19. The system of claim 15 wherein the means for measuring
oxidation stability comprises means for measuring the consumption
of oxygen of the selected samples.
20. The system of claim 15 wherein the means for measuring oxygen
stability comprises means for measuring deposit formation on a
transparent glass substrate resulting from oxidation of the
selected samples.
21. The system of claim 18 wherein the means for measuring deposit
formation includes a light source and a photocell aligned with the
light source.
22. The system of claim 15 wherein each test receptacle has a bar
code affixed to an outer surface thereof.
23. The system of claim 22 further comprising a bar code reader.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates generally to methods for high
throughput screening of lubricating oil compositions.
[0003] 2. Description of the Related Art
[0004] The use of a combinatorial approach for materials synthesis
is a relatively new area of research aimed at using rapid synthesis
and screening methods to build libraries of polymeric, inorganic or
solid state materials. For example, advances in reactor technology
have empowered chemists and engineers to rapidly produce large
libraries of discrete organic molecules in the pursuit of new drug
discovery, which have led to the development of a growing branch of
research called combinatorial chemistry. Combinatorial chemistry
generally refers to methods and materials for creating collections
of diverse materials or compounds--commonly known as libraries--and
to techniques and instruments for evaluating or screening libraries
for desirable properties.
[0005] Presently, research in the lubricant industry involves
individually forming candidate lubricating oil compositions and
then performing a macro-scale analysis of the candidate
compositions by employing a large amount of the candidate to be
tested. Additionally, the methods employed for testing each
candidate composition require manual operation. This, in turn,
significantly reduces the number of compositions that can be tested
and identified as leading lubricating oil compositions.
[0006] Drawbacks associated with conventional screening procedures
can be seen as follows. For example, governmental and automotive
industry pressure towards reducing the phosphorous and sulfur
content of lubricating oil compositions used as, for example,
passenger car and heavy duty diesel engine oils, is leading to new
research to identify oil compositions which can satisfy certain
tests such as, for example, oxidation, wear and compatibility
tests, while containing low levels of phosphorous and sulfur. In
this context, United States Military Standards MIL-L-46152E and the
ILSAC Standards defined by the Japanese and United States
Automobile Industry Association at present require the phosphorous
content of engine oils to be at or below 0.10 wt. % with future
phosphorous content being proposed to even lower levels, e.g., 0.08
wt. % by January, 2004 and below 0.05 wt. % by January, 2006. Also,
at present, there is no industry standard requirement for sulfur
content in engine oils, but it has been proposed that the sulfur
content be below 0.2 wt. % by January, 2006. Thus, it would be
desirable to decrease the amount of phosphorous and sulfur in
lubricating oils still further, thereby meeting future industry
standard proposed phosphorous and sulfur contents in the engine oil
while still retaining the oxidation or corrosion inhibiting
properties and antiwear properties of the higher phosphorous and
sulfur content engine oils. In order to accomplish this, a large
number of proposed lubricating oil compositions must be tested to
determine which compositions may be useful.
[0007] Additionally, similar changes in specifications and changing
customer needs also drive reformulation efforts in other lubricant
applications such as, for example, transmission fluids, hydraulic
fluids, gear oils, marine cylinder oils, compressor oils,
refrigeration lubricants and the like.
[0008] However, as stated above, present research in the lubricant
industry does not allow for reformulation to occur in an
expeditious manner. As such, there exists a need in the art for a
more efficient, economical and systematic approach for the
preparation of lubricating oil compositions and screening of such
compositions for information correlating to the actual useful
properties of the compositions. For example, lubricating oils as
used in, for example, internal combustion engines of automobiles or
trucks, are subjected to a demanding environment during use. The
environment results in the oil suffering oxidation which is
catalyzed by the presence of impurity species in the oil such as,
for example, iron compounds, and is also promoted by the elevated
temperatures experienced by the oil during use. The catalyzed
oxidation of the oil contributes to the formation of corrosive
oxidation products and sludge in the oil but can also cause the
viscosity of the oil to increase or even solidify.
[0009] Accordingly, it would be desirable to rapidly screen a
plurality of sample candidate lubricating oil compositions for
oxidation stability utilizing small amounts of each sample. In this
manner, a high throughput preparation and screening of a vast
number of diverse compositions can be achieved to identify leading
lubricating oil compositions.
SUMMARY OF THE INVENTION
[0010] A high throughput screening method for determining lubricant
performance is provided herein. In accordance with one embodiment
of the present invention, a high throughput method for screening
lubricating oil compositions, under program control, is provided
comprising the steps of (a) providing a plurality of different
lubricating oil composition samples comprising (i) a major amount
of at least one base oil of lubricating viscosity and (ii) a minor
amount of at least one lubricating oil additive, each sample being
in a respective one of a plurality of test receptacles; (b)
measuring the oxidation stability of each sample to provide
oxidation stability data for each sample; and (c) outputting the
results of step (b).
[0011] The methods of the present invention advantageously permits
the automatic screening of many different lubricating oil
composition samples in an efficient manner in accordance with
adjustable selection criteria to determine oxidation stability of
the samples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Various embodiments are described below with reference to
the drawings wherein:
[0013] FIG. 1 is a schematic diagram of a system for preparing a
plurality of different lubricating oil compositions;
[0014] FIG. 2 is a schematic diagram of a system for high
throughput oxidation screening of a variety of lubricant oil
compositions; and,
[0015] FIG. 3 is a schematic diagram of a photocell system for
measuring deposit formation on a substrate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0016] The present invention is directed to a high throughput
screening method for determining lubricant performance of a
plurality of different lubricating oil compositions by subjecting a
plurality of different lubricating oil composition samples in a
respective one of a plurality of test receptacles to measure
oxidation stability. The expression "high throughput" as used
herein shall be understood to mean that a relatively large number
of different lubricating oil compositions is rapidly prepared and
analyzed. In a first step of the screening method of the present
invention, varying quantities of at least one base oil of
lubricating viscosity and at least one lubricating oil additive are
introduced in respective test reservoirs so that each reservoir
contains a different lubricating oil composition having a different
composition depending upon the percentage amounts and/or types of
the additives combined with the base oil of lubricating viscosity
in each receptacle. Data regarding the composition of each sample
are stored in a data library. The procedure is advantageously
accomplished under program control and is automatically controlled
by, for example, a microprocessor or other computer control device.
The expression "program control" as used herein shall be understood
to mean the equipment used herein in providing the plurality of
lubricating oil compositions is automated and controlled by a
microprocessor or other computer control device.
[0017] The lubricating oil compositions for use in the high
throughput screening method of this invention include as a first
component a major amount of base oil of lubricating viscosity,
e.g., an amount of greater than 50 wt. %, preferably greater than
about 70 wt. %, more preferably from about 80 to about 99.5 wt. %
and most preferably from about 85 to about 98 wt. %, based on the
total weight of the composition. The expression "base oil" as used
herein shall be understood to mean a base stock or blend of base
stocks which is a lubricant component that is produced by a single
manufacturer to the same specifications (independent of feed source
or manufacturer's location); that meets the same manufacturer's
specification; and that is identified by a unique formula, product
identification number, or both. The base oil for use herein can be
any presently known or later-discovered base oil of lubricating
viscosity used in formulating lubricating oil compositions for any
and all such applications, e.g., engine oils, marine cylinder oils,
functional fluids such as hydraulic oils, gear oils, transmission
fluids, etc. Additionally, the base oils for use herein can
optionally contain viscosity index improvers, e.g., polymeric
alkylmethacrylates; olefinic copolymers, e.g., an
ethylene-propylene copolymer or a styrene-butadiene copolymer; and
the like and mixtures thereof.
[0018] As one skilled in the art would readily appreciate, the
viscosity of the base oil is dependent upon the application.
Accordingly, the viscosity of a base oil for use herein will
ordinarily range from about 2 to about 2000 centistokes (cSt) at
100.degree. Centigrade (C). Generally, individually the base oils
used as engine oils will have a kinematic viscosity range at
100.degree. C. of about 2 cSt to about 30 cSt, preferably about 3
cSt to about 16 cSt, and most preferably about 4 cSt to about 12
cSt and will be selected or blended depending on the desired end
use and the additives in the finished oil to give the desired grade
of engine oil, e.g., a lubricating oil composition having an SAE
Viscosity Grade of 0W, 0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W,
5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W, 10W-20, 10W-30, 10W-40,
10W-50, 15W, 15W-20, 15W-30 or 15W-40. Oils used as gear oils can
have viscosities ranging from about 2 cSt to about 2000 cSt at
100.degree. C.
[0019] Base stocks may be manufactured using a variety of different
processes including, but not limited to, distillation, solvent
refining, hydrogen processing, oligomerization, esterification, and
rerefining. Rerefined stock shall be substantially free from
materials introduced through manufacturing, contamination, or
previous use. The base oil of the lubricating oil compositions of
this invention may be any natural or synthetic lubricating base
oil. Suitable hydrocarbon synthetic oils include, but are not
limited to, oils prepared from the polymerization of ethylene or
from the polymerization of 1-olefins to provide polymers such as
polyalphaolefin or PAO oils, or from hydrocarbon synthesis
procedures using carbon monoxide and hydrogen gases such as in a
Fischer-Tropsch process. For example, a suitable base oil is one
that comprises little, if any, heavy fraction; e.g., little, if
any, lube oil fraction of viscosity 20 cSt or higher at 100.degree.
C.
[0020] The base oil may be derived from natural lubricating oils,
synthetic lubricating oils or mixtures thereof. Suitable base oil
includes base stocks obtained by isomerization of synthetic wax and
slack wax, as well as hydrocracked base stocks produced by
hydrocracking (rather than solvent extracting) the aromatic and
polar components of the crude. Suitable base oils include those in
all API categories I, II, III, IV and V as defined in API
Publication 1509, 14th Edition, Addendum I, December 1998. Group IV
base oils are polyalphaolefins (PAO). Group V base oils include all
other base oils not included in Group I, II, III, or IV. Although
Group II, III and IV base oils are preferred for use in this
invention, these preferred base oils may be prepared by combining
one or more of Group I, II, III, IV and V base stocks or base
oils.
[0021] Useful natural oils include mineral lubricating oils such
as, for example, liquid petroleum oils, solvent-treated or
acid-treated mineral lubricating oils of the paraffinic, naphthenic
or mixed paraffinic-naphthenic types, oils derived from coal or
shale, animal oils, vegetable oils (e.g., rapeseed oils, castor
oils and lard oil), and the like.
[0022] Useful synthetic lubricating oils include, but are not
limited to, hydrocarbon oils and halo-substituted hydrocarbon oils
such as polymerized and interpolymerized olefins, e.g.,
polybutylenes, polypropylenes, propylene-isobutylene copolymers,
chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes),
poly(1-decenes), and the like and mixtures thereof; alkylbenzenes
such as dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)-benzenes, and the like; polyphenyls such as
biphenyls, terphenyls, alkylated polyphenyls, and the like;
alkylated diphenyl ethers and alkylated diphenyl sulfides and the
derivative, analogs and homologs thereof and the like.
[0023] Other useful synthetic lubricating oils include, but are not
limited to, oils made by polymerizing olefins of less than 5 carbon
atoms such as ethylene, propylene, butylenes, isobutene, pentene,
and mixtures thereof. Methods of preparing such polymer oils are
well known to those skilled in the art.
[0024] Additional useful synthetic hydrocarbon oils include liquid
polymers of alpha olefins having the proper viscosity. Especially
useful synthetic hydrocarbon oils are the hydrogenated liquid
oligomers of C.sub.6 to C.sub.12 alpha olefins such as, for
example, 1-decene trimer.
[0025] Another class of useful synthetic lubricating oils include,
but are not limited to, alkylene oxide polymers, i.e.,
homopolymers, interpolymers, and derivatives thereof where the
terminal hydroxyl groups have been modified by, for example,
esterification or etherification. These oils are exemplified by the
oils prepared through polymerization of ethylene oxide or propylene
oxide, the alkyl and phenyl ethers of these polyoxyalkylene
polymers (e.g., methyl poly propylene glycol ether having an
average molecular weight of 1,000, diphenyl ether of polyethylene
glycol having a molecular weight of 500-1000, diethyl ether of
polypropylene glycol having a molecular weight of 1,000-1,500,
etc.) or mono- and polycarboxylic esters thereof such as, for
example, the acetic esters, mixed C.sub.3-C.sub.8 fatty acid
esters, or the C.sub.13 oxo acid diester of tetraethylene
glycol.
[0026] Yet another class of useful synthetic lubricating oils
include, but are not limited to, the esters of dicarboxylic acids
e.g., plithalic acid, succinic acid, alkyl succinic acids, alkenyl
succinic acids, maleic acid, azelaic acid, suberic acid, sebacic
acid, fumaric acid, adipic acid, linoleic acid dimer, malonic
acids, alkyl malonic acids, alkenyl malonic acids, etc., with a
variety of alcohols, e.g., butyl alcohol, hexyl alcohol, dodecyl
alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol
monoether, propylene glycol, etc. Specific examples of these esters
include dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl
fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate,
dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the
2-ethylhexyl diester of linoleic acid dimer, the complex ester
formed by reacting one mole of sebacic acid with two moles of
tetraethylene glycol and two moles of 2-ethylhexanoic acid and the
like.
[0027] Esters useful as synthetic oils also include, but are not
limited to, those made from carboxylic acids having from about 5 to
about 12 carbon atoms with alcohols, e.g., methanol, ethanol, etc.,
polyols and polyol ethers such as neopentyl glycol, trimethylol
propane, pentaerythritol, dipentaerythritol, tripentaerythritol,
and the like.
[0028] Silicon-based oils such as, for example, polyalkyl-,
polyaryl-, polyalkoxy- or polyaryloxy-siloxane oils and silicate
oils, comprise another useful class of synthetic lubricating oils.
Specific examples of these include, but are not limited to,
tetraethyl silicate, tetra-isopropyl silicate, tetra-(2-ethylhexyl)
silicate, tetra-(4-methyl-hexyl)silicate,
tetra-(p-tert-butylphenyl)silicate,
hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxanes,
poly(methylphenyl)siloxanes, and the like. Still yet other useful
synthetic lubricating oils include, but are not limited to, liquid
esters of phosphorous containing acids, e.g., tricresyl phosphate,
trioctyl phosphate, diethyl ester of decane phosphionic acid, etc.,
polymeric tetrahydrofurans and the like.
[0029] The lubricating oil may be derived from unrefined, refined
and rerefined oils, either natural, synthetic or mixtures of two or
more of any of these of the type disclosed hereinabove. Unrefined
oils are those obtained directly from a natural or synthetic source
(e.g., coal, shale, or tar sands bitumen) without further
purification or treatment. Examples of unrefined oils include, but
are not limited to, a shale oil obtained directly from retorting
operations, a petroleum oil obtained directly from distillation or
an ester oil obtained directly from an esterification process, each
of which is then used without further treatment. 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. These purification techniques are known to those of
skill in the art and include, for example, solvent extractions,
secondary distillation, acid or base extraction, filtration,
percolation, hydrotreating, dewaxing, etc. Rerefined oils are
obtained by treating used oils in processes similar to those used
to obtain refined oils. Such rerefined oils are also known as
reclaimed or reprocessed oils and often are additionally processed
by techniques directed to removal of spent additives and oil
breakdown products.
[0030] Lubricating oil base stocks derived from the
hydroisomerization of wax may also be used, either alone or in
combination with the aforesaid natural and/or synthetic base
stocks. Such wax isomerate oil is produced by the
hydroisomerization of natural or synthetic waxes or mixtures
thereof over a hydroisomerization catalyst.
[0031] Natural waxes are typically the slack waxes recovered by the
solvent dewaxing of mineral oils; synthetic waxes are typically the
wax produced by the Fischer-Tropsch process.
[0032] The second component of the lubricating oil compositions for
use herein is at least one lubricating oil additive. Such additives
can be any presently known or later-discovered additive used in
formulating lubricating oil compositions. The lubricating oil
additives for use herein include, but are not limited to,
antioxidants, anti-wear agents, detergents such as metal
detergents, rust inhibitors, dehazing agents, demulsifying agents,
metal deactivating agents, friction modifiers, pour point
depressants, antifoaming agents, co-solvents, package
compatibilisers, corrosion-inhibitors, ashless dispersants, dyes,
extreme pressure agents and the like and mixtures thereof. Greases
will require the addition of appropriate thickeners. A variety of
the additives are known and commercially available. These
additives, or their analogous compounds, can be employed for the
preparation of the various lubricating oil compositions herein.
[0033] Alternatively, the lubricating oil additive(s) can further
contain a diluent oil to form an additive concentrate. These
concentrates usually include at least from about 90 wt. % to about
10 wt. % and preferably from about 90 wt. % to about 50 wt. %, of a
diluent oil and from about 10 wt. % to about 90 wt. %, preferably
from about 10 wt. % to about 50 wt. %, of the foregoing
additive(s). Suitable diluents for the concentrates include any
inert diluent, preferably an oil of lubricating viscosity such as,
for example, a base oil as described hereinbelow, so that the
concentrate may be readily mixed with lubricating oils to prepare
lubricating oil compositions. Suitable lubricating oils that may be
used as diluents can be any oil of lubricating viscosity.
[0034] Generally the lubricating oil compositions of the present
invention will include at least one antioxidant. Examples of
antioxidants include, but are not limited to, hindered phenolic
antioxidants, secondary aromatic amine antioxidants, sulfurized
phenolic antioxidants, oil-soluble copper compounds,
phosphorus-containing antioxidants, organic sulfides, disulfides
and polysulfides and the like. The antioxidants will ordinarily be
present in the lubricating oil compositions of the present
invention at a concentration ranging from about 0.1 to about 5
weight percent.
[0035] Examples of sterically hindered phenolic antioxidants
include, but are not limited to, ortho-alkylated phenolic compounds
such as 2,6-di-tertbutylphenol, 4-methyl-2,6-di-tertbutylphenol,
2,4,6-tri-tertbutylphenol, 2-tert-butylphenol,
2,6-diisopropylphenol, 2-methyl-6-tert-butylphenol,
2,4-dimethyl-6-tert-butylphenol,
4-(N,N-dimethylaminomethyl)-2,6-di-tertbutyl phenol,
4-ethyl-2,6-di-tertbutylphenol, 2-methyl-6-styrylphenol,
2,6-distyryl-4-nonylphenol, and their analogs and homologs.
Mixtures of two or more such mononuclear phenolic compounds are
also suitable.
[0036] Examples of other phenol antioxidants for use in the
lubricating oil compositions of the present invention include, but
are not limited to, methylene-one or more of bridged alkylphenols,
one or more sterically-hindered unbridged phenolic compounds and
mixtures thereof. Examples of methylene-bridged compounds include,
but are not limited to, 4,4'-methylenebis(6-tert-butyl o-cresol),
4,4'-methylenebis(2-tert-amyl-o- -cresol),
2,2'-methylenebis(4-methyl-6-tert-butylphenol),
4,4'-methylene-bis(2,6-di-tertbutylphenol), and the like.
Particularly preferred are mixtures of methylene-bridged
alkylphenols such as those described in U.S. Pat. No. 3,211,652,
the contents of which are incorporated by reference herein.
[0037] Amine antioxidants can also be used in the lubricating oil
compositions of this invention. Examples include, but are not
limited to, oil-soluble aromatic secondary amines, aromatic
secondary polyamines and the like and combinations thereof with
aromatic secondary amines being preferred. Examples of aromatic
secondary monoamines include diphenylamine, alkyl diphenylamines
containing 1 or 2 alkyl substituents each having up to about 16
carbon atoms, phenyl-alpha-naphthylamine, phenyl-beta-napthylamine,
alkyl- or aralkylsubstituted phenyl-alpha-naphthylamine containing
at least one or two alkyl or aralkyl groups each having up to about
16 carbon atoms, alkyl- or aralkyl-substituted
phenyl-beta-naphthylamine containing at least one or two alkyl or
aralkyl groups each having up to about 16 carbon atoms, and the
like.
[0038] A preferred type of aromatic amine antioxidant is an
alkylated diphenylamine of the general formula
R.sub.1--C.sub.6--H.sub.4--NH--C.sub.6H.sub.4--R.sub.2
[0039] wherein R.sub.1 is an alkyl group (preferably a branched
alkyl group) having 6 to 12 carbon atoms and preferably 8 or 9
carbon atoms; and R.sub.2 is a hydrogen atom or an alkyl group
(preferably a branched alkyl group) having 6 to 12 carbon atoms and
preferably 8 or 9 carbon atoms. Most preferably, R.sub.1 and
R.sub.2 are the same. One such preferred compound is available
commercially as Naugalube 438L, a material which is understood to
be predominately a 4,4'-dinonyldiphenylamine (i.e.,
bis(4-nonylphenyl)(amine) wherein the nonyl groups are
branched.
[0040] Another antioxidant for use in the lubricating oil
compositions of this invention is comprised of one or more liquid,
partially sulfurized phenolic compounds such as those prepared by
reacting sulfur monochloride with a liquid mixture of phenols
wherein at least about 50 weight percent of the mixture of phenols
is composed of one or more reactive, hindered phenols and in
proportions to provide from about 0.3 to about 0.7 gram atoms of
sulfur monochloride per mole of reactive, hindered phenol so as to
produce a liquid product. Typical phenol mixtures useful in making
such liquid product compositions include a mixture containing by
weight about 75% of 2,6-di-tert-butylphenol, about 10% of
2-tert-butylphenol, about 13% of 2,4,6-tri-tertbutylphenol, and
about 2% of 2,4-di-tertbutylphenol. The reaction is exothermic and
is preferably kept within the range of about 15.degree. C. to about
70.degree. C., most preferably between about 40.degree. C. to about
60.degree. C.
[0041] Mixtures of different antioxidants can also be used in the
lubricating oil compositions of the present invention. One suitable
mixture is comprised of a combination of (i) an oil-soluble mixture
of at least three different sterically-hindered tertiary butylated
monohydric phenols which is in the liquid state at 25.degree. C.,
(ii) an oil-soluble mixture of at least three different
sterically-hindered tertiary butylated methylene-bridged
polyphenols, and (iii) at least one bis(4-alkylphenyl) amine
wherein the alkyl group is a branched alkyl group having 8 to 12
carbon atoms, the proportions of (i), (ii) and (iii) on a weight
basis falling in the range of about 3.5 to about 5.0 parts of
component (i) and about 0.9 to about 1.2 parts of component (ii)
per part by weight of component (iii). Examples of such
antioxidants discussion above are disclosed in U.S. Pat. No.
5,328,619, the contents of which are incorporated by reference
herein. Other useful antioxidants are those disclosed in U.S. Pat.
No. 4,031,023, the contents of which are incorporated by reference
herein.
[0042] Examples of antiwear agents include, but are not limited to,
zinc dialkyldithiophosphates and zinc diaryldithiophosphates, e.g.,
those described in an article by Born et al. entitled "Relationship
between Chemical Structure and Effectiveness of Some Metallic
Dialkyl- and Diaryl-dithiophosphates in Different Lubricated
Mechanisms", appearing in Lubrication Science 4-2 January 1992, see
for example pages 97-100; aryl phosphates and phosphites,
sulfur-containing esters, phosphosulfur compounds, metal or
ash-free dithiocarbamates, xanthates, alkyl sulfides and the like
and mixtures thereof.
[0043] Examples of detergents include, but are not limited to,
overbased or neutral detergents such as sulfonate detergents, e.g.,
those made from alkyl benzene and fuming sulfuric acid; phenates
(high overbased or low overbased), high overbased phenate
stearates, phenolates, salicylates, phosphonates, thiophosphonates,
ionic surfactants and the like and mixtures thereof. Low overbased
metal sulfonates typically have a total base number (TBN) of from
about 0 to about 30 and preferably from about 10 to about 25. Low
overbased metal sulfonates and neutral metal sulfonates are well
known in the art.
[0044] Examples of rust inhibitors include, but are not limited to,
nonionic polyoxyalkylene agents, e.g., polyoxyethylene lauryl
ether, polyoxyethylene higher alcohol ether, polyoxyethylene
nonylphenyl ether, polyoxyethylene octylphenyl ether,
polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether,
polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol
monooleate, and polyethylene glycol monooleate; stearic acid and
other fatty acids; dicarboxylic acids; metal soaps; fatty acid
amine salts; metal salts of heavy sulfonic acid; partial carboxylic
acid ester of polyhydric alcohol; phosphoric esters; (short-chain)
alkenyl succinic acids; partial esters thereof and
nitrogen-containing derivatives thereof; synthetic
alkarylsulfonates, e.g., metal dinonylnaphthalene sulfonates; and
the like and mixtures thereof.
[0045] Examples of friction modifiers include, but are not limited
to, alkoxylated fatty amines; borated fatty epoxides; fatty
phosphites, fatty epoxides, fatty am ines, borated alkoxylated
fatty amines, metal salts of fatty acids, fatty acid amides,
glycerol esters, borated glycerol esters; and fatty imidazolines as
disclosed in U.S. Pat. No. 6,372,696, the contents of which are
incorporated by reference herein; friction modifiers obtained from
a reaction product of a C.sub.4 to C.sub.75, preferably a C.sub.6
to C.sub.24, and most preferably a C.sub.6 to C.sub.20, fatty acid
ester and a nitrogen-containing compound selected from the group
consisting of ammonia, and an alkanolamine, e.g., those disclosed
in U.S. Ser. No. 10/402,170, filed Mar. 28, 2003, the contents of
which are incorporated by reference herein, and the like and
mixtures thereof.
[0046] Examples of antifoaming agents include, but are not limited
to, polymers of alkyl methacrylate; polymers of dimethylsilicone
and the like and mixtures thereof.
[0047] Examples of ashless dispersants include, but are not limited
to, polyalkylene succinic anhydrides; non-nitrogen containing
derivatives of a polyalkylene succinic anhydride; a basic nitrogen
compound selected from the group consisting of succinimides,
carboxylic acid amides, hydrocarbyl monoamines, hydrocarbyl
polyamines, Mannich bases, phosphonoamides, thiophosphonamides and
phosphoramides; thiazoles, e.g., 2,5-dimercapto-1,3,4-thiadiazoles,
mercaptobenzothiazoles and derivatives thereof; triazoles, e.g.,
alkyltriazoles and benzotriazoles; copolymers which contain a
carboxylate ester with one or more additional polar function,
including amine, amide, imine, imide, hydroxyl, carboxyl, and the
like, e.g., products prepared by copolymerization of long chain
alkyl acrylates or methacrylates with monomers of the above
function; and the like and mixtures thereof. The derivatives of
these dispersants, e.g., borated dispersants such as borated
succinimides, may also be used. Preferably, the dispersants are
polyalkylene succinimides derived from animation of polyalkylene
succinic anhydrides with polyalkylene polyamine.
[0048] If desired, prior to dispensing the at least one base oil
and at least one lubricating oil additive to provide the
compositions herein, as discussed hereinbelow, it can be
advantageous to conduct molecular modeling of proposed compounds
for use in the compositions (i.e., formulations) to determine which
compounds may provide potential leading candidate compositions. For
example, calculations can be carried out involving such factors as,
for example, transition states, bond lengths, bond angles, dipole
moment, hydrophobicity, etc, of the compounds. Accordingly, the
proposed compounds can be screened to determine, for example, which
compounds may perform poorly in an oxidation inhibition process due
to a poor ability to trap intermediate peroxides. This can be
carried out using known software such as, for example, Quantum
Mechanics available from Accelrys (San Diego, Calif.).
[0049] Software for the design of test libraries can be used to
design the original compound test libraries based on input from the
foregoing experimental program(s). This software can be used to
efficiently design test libraries that cover the desired
experimental space and utilize statistical experimental design
methods. Other software can then be used to analyze the data from
the experiments and correlate that data with the structure of the
compounds and/or compound treatment conditions and/or reaction
conditions. Such correlations are often referred to as QSAR
software (Quantitative Structure Activity Relations) available from
Accelrys (San Diego, Calif.). Such QSAR programs can then be used
by the software to design subsequent compound test libraries for
further screening.
[0050] The use of such QSAR programs can add to the efficiency of
screening. As more data is collected, these QSAR programs can
become more efficient at developing compounds libraries with
increased probability for finding desirable compounds. For example,
the compounds analyzed can be formulated into various lubricating,
oil compositions, as decribed herein, and then further analyzed by
way of, for example, regression and analysis technologies, using
known software, e.g., C.sup.2-QSAR available from Accelrys (San
Diego, Calif.). In this manner, validation of the data obtained
from the molecular modeling can be achieved and then this data can
also be stored in a data collector. In this way, new compounds,
conceived by one skilled in the art can be checked by the QSAR
software to predict their activity prior to their actual synthesis.
Additionally, such software tools may be utilized to prioritize a
list of possible compounds being considered for synthesis in such a
way that one skilled in the art will have a higher probability for
success.
[0051] Referring now to FIG. 1, an example of a system to provide
the foregoing compositions in the plurality of respective test
receptacles is generally illustrated as system 100. Representative
of this system and method for providing the foregoing compositions
in the plurality of respective test receptacles is one disclosed in
co-pending U.S. patent application Ser. No. ______ filed on ______
and entitled "HIGH THROUGHPUT PREPARATION OF LUBRICATING OIL
COMPOSITIONS FOR COMBINATORIAL LIBRARIES" by Wollenberg et al.
(Docket No. T-6298A; (538-60)) and having a common assignee with
the present application, the contents of which are incorporated by
reference herein. Generally, vessel 110 contains a supply of the
foregoing base oils of lubricating viscosity B. Vessel 120 contains
a supply of additive A, which can be any of the foregoing additives
useful for modifying the properties of the base oil. As one skilled
in the art would readily appreciate, one or more of vessels 110 and
vessels 120 can be used when dispensing more than one base oil
and/or more than one additive, respectively.
[0052] Tubular line 111 is a conduit for communicating the base oil
B to nozzle portion 113, from which it can be dispensed into a
selected test reservoir, as described below. The amount of base oil
dispensed is determined by metering pump 112, which can be computer
controlled.
[0053] Tubular line 121 is a conduit for communicating the
lubricating oil additive A to nozzle portion 123, from which it can
be dispensed into a selected test reservoir, as described below.
The amount of lubricating oil additive dispensed is determined by
metering pump 122, which also can be computer controlled. Computer
programs and systems for automatically metering predetermined
amounts of materials in accordance with a preselected protocol are
known in the art and can be used herein.
[0054] Nozzles 113 and 123 are preferably in close proximity so
that base oil B and additive A can be simultaneously dispensed in a
test reservoir. Alternatively, base oil B and additive A can be
sequentially added to the test reservoir. The nozzles 113 and 123
can comprise a multichannel pipette or one or more syringe
needles.
[0055] The vessels 110 and 120 can be under pressure. Optionally,
more than two vessels can be employed. Metering pumps suitable for
use in the invention are known and commercially available. In the
event that highly viscous lubricant base stock or additives are
used, the vessels 110 and 120 and/or the tubular lines 111 and 121,
metering pumps 112 and 122, and/or nozzles 113 and 123 can be
heated to facilitate fluid flow therethrough.
[0056] The test frame 130 includes a block 131 of transparent
material (e.g., glass) having a plurality of recesses 132 for
receiving the dispensed additives or base oil and additives. The
recesses provide test reservoirs wherein each reservoir contains
lubricating oil compositions of a different and predetermined
composition, i.e., the percentage and/or type of base oil and/or
additives in each composition will vary from one reservoir to
another. Optionally, the reservoirs can be individual receptacles
(e.g., test tubes) mounted upon a rack, instead of being recesses
in a block. Preferably, the test receptacles comprise transparent
glass tubes. While five reservoirs, i.e., recesses 132a, 132b,
132c, 132d, 132e, are illustrated in FIG. 1, any number of
reservoirs can be employed herein. For example the system can
employ 20, 50, 100 or even more test receptacles and samples as
required.
[0057] The individual reservoirs are adapted to hold relatively
small amounts of lubricating oil samples. The sample size in each
reservoir can generally be no more than about 20 ml, preferably no
more than about 15 ml, more preferably no more than about 10 ml and
yet more preferably no more than about 5 ml.
[0058] The test frame 130 and dispensing nozzles 113 and 123 are
movable relative to one another. Although manual movement of the
apparatus by an equipment operator is within the purview of the
invention, robotic mechanisms with programmable movement are
preferred. In one embodiment the test frame 130 is mounted upon a
slidable carriage movable in a lateral and/or vertical direction so
as to sequentially position a selected recess under the dispensing
nozzles 113 and 123. In another embodiment, the nozzles 113 and
123, and optionally the vessels 110 and 120, are slidably movable
laterally and/or vertically to accomplish positioning of the
nozzles 113 and 123.
[0059] In a testing procedure, vessels 110 and 120 are filled with
the selected lubricant base oil and additive(s), respectively. The
apparatus of system 100 is moved such that dispensing nozzles 113
and 123 are positioned above and in alignment with recess 132a. A
metered amount of base oil B and a metered amount of additive A are
simultaneously dispensed into recess 132a. The dispensing nozzles
113 and 123 are thereafter repositioned to be in alignment with the
next recess 132b and the metered amounts of additive A and/or base
oil B are changed in accordance with a predetermined schedule of
variation such that the lubricating oil in recess 132b has a
different percentage composition of additive than that in recess
132a. The pattern is repeated as the nozzles 113 and 123 are
sequentially aligned with the successive recesses 132c, 132d, and
132e so that each recess has a predetermined composition of
lubricating oil.
[0060] The components A and B are preferably combined in the
reservoirs by mixing, for example, by agitation of the frame 131,
static mixing, individual stirring of the contents of the
reservoirs (mechanical or magnetic stirring) and/or by bubbling the
reservoir with gas, e.g., nitrogen. Optionally, base oil B and
additive(s) A can be combined prior to dispensing into the
respective reservoirs. For example, a single dispensing nozzle
having a mixing chamber can be used, wherein base oil B and
additive(s) A are metered into the mixing chamber and then
dispensed through the nozzle into the reservoir.
[0061] Once the plurality of receptacles have been provided
containing lubricating oil compositions, the plurality of fluid
samples can then be analyzed for oxidation stability measurements
such as, e.g., oxidation consumption data, deposit data, viscosity
data, etc. Referring now to FIG. 2, a system for sequentially
analyzing a plurality of fluid samples for antioxidant properties
is schematically illustrated. System 200 is schematically
illustrated wherein an array of test receptacles 212 are mounted in
a holder 215. The system 200 is adapted to accommodate any number
of test receptacles 212 (and samples). Each sample is identifiable,
for example, by the position of its test receptacle in an ordered
array in holder 215, or more preferably by having an identifying
mark associated with it. For example, each test receptacle 212 can
include an identifying bar code 213 affixed to the outer surface
thereof. A bar code reader 225 is positioned so as to be able to
read the individual bar codes of the respective test receptacles
212 and to transmit a bar code data signal to a computer controller
230 via a data transmission line 226 to electronically identify the
sample. The bar code reader 225 is preferably movable with respect
to the holder 215 in response to a signal from computer controller
230 so as to be positionable in alignment with selected individual
test receptacles 212.
[0062] A robotic assembly 250 includes a movable arm 251 with a
grasping mechanism 252. The robotic assembly is adapted to grasp an
individual test receptacle 212 in accordance with selection
instructions from computer controller 230 and move the test
receptacle to a position in testing station 220 so that the sample
in the receptacle can be measured for antioxidant properties. The
computer controller 230 is operatively associated with controls to
the robotic assembly via control signal transmission line 231 to
selectively retrieve predetermined test receptacles for measurement
and then replace them in their assigned respective positions in the
holder 215.
[0063] Testing station 220 includes means for testing the samples
for oxidation stability, i.e., resistance to oxidation. Oxidation
stability data results of the test are converted to an electrical
or optical signal and transmitted via signal transmission line 223
to computer controller 230. Various means for oxidation stability
testing are known and generally include subjecting the sample to an
oxygen environment and measuring the effect of oxidation upon the
sample over a predetermined period of time.
[0064] For example, in one test method for use herein (known as the
Lube Oil Oxidator test method), a sample of oil is weighed into an
oxidator cell, e.g., glass. A glass stirrer is inserted into the
cell, and the cell is sealed together with a delivery source of
oxygen gas which is maintained at about one atmosphere pressure
(760 mmHg). Typically, the stirrer is magnetically coupled to a
stir motor which is external to the oxidator cell. To an area above
the oil sample can be placed a sufficient solid material suitable
for absorption of carbon dioxide gas which may be liberated during
oxidation of the test lube oil, e.g., potassium hydroxide.
Optionally, a liquid catalyst may be added to the lube oil to
assist in accelerating oxidation and is chosen to simulate the
types of metal ions typically found in an internal combustion
engine.
[0065] The cell is then placed in an oil bath maintained at a
predetermined temperature, e.g., a temperature ranging from about
250.degree. F. to about 400.degree. F. and preferably from about
300.degree. F. to about 350.degree. F., and connected to an oxygen
supply. A sufficient quantity of oxygen is delivered into the cell
while the stirrer agitates the oil sample. The test is run until
the quantity of oxygen is consumed by the sample and the total
time, e.g., in hours, of the sample run is reported. In general,
large scale operation typically requires one liter of oxygen for a
25 gram sample. Accordingly, methods employing a smaller quantity
of sample require proportionately smaller volumes of oxygen and are
within the purview within the purview of one skilled in the art. If
desired, results from measurements of the current quantity of
oxygen that is consumed as well as the lube oil viscosity can be
recorded at predetermined time intervals to a computer database for
later analysis. In a variation of this test, the amount of oxygen
consumed after a predetermined time period, e.g., about a 10 hour
test, is measured while recording to a computer database at time
intervals the volume of oxygen uptake and the lube oil viscosity.
Suitable high throughput methods for measuring viscosity are
disclosed in EP 1158290, WO 99/18431, US 2003/0037601, U.S. Pat.
No. 6,383,898, and WO 03/019150.
[0066] In a second embodiment, a method to determine the
temperature where a test oil undergoes oxidation and deposit
formation on, for example, a transparent tube, is used. In this
method, the transparent glass tube can be placed inside a metal
heating block, e.g., an aluminum heating block, and a small air
hose is attached to a holder at the bottom of the glass tube. Next,
a suitable nozzle, e.g., about a 5 ml syringe, and a suitable hose,
e.g., about a 12 inch flexible tubing, are filled with the oil
sample.
[0067] The tubing is attached to a holder on the glass tube above
the air hose and oil is steadily introduced into the glass tube by
the nozzle. Air forces the test oil up the glass tube through the
heating block for the duration of the test. The rate of air flow
and sample introduction are controlled such that the entire sample
is injected within a predetermined time, e.g., a 16 hour time
period. The oxidation of the oil gradually forms a dark deposit on
the inner wall of the glass tube. The heating block is temperature
controlled within small limits and the test conditions are
generally chosen over a range of temperatures, e.g., from about
230.degree. C. to about 330.degree. C., and tests can be run at
different temperatures to determine deposit formation over a
temperature range. After a predetermined period of time (e.g., 16
hours) the glass tube is removed from the test apparatus, rinsed
with a suitable solvent, and the amount of deposit is measured in
accordance with the darkness of the deposit in the tube, the
darkness indicating the quantity of the deposit and the amount of
oxidation. The measurement is compared against a predetermined
standard set of tubes.
[0068] While the determination of the deposit formation can be
performed manually by visually inspecting the test tube, comparing
it with the standard set of tubes, and estimating the degree of
deposit formation, the present method is automated and preferably
employs a light source and a photocell. The amount of deposit can
be measured by directing a beam of light from the light source
through the tube and measuring the amount of light transmitted
through the tube by means of the photocell. The opacity of the tube
indicates the amount of deposit, and hence, the amount of oxidation
of the sample.
[0069] For example, referring to FIG. 3, test tube 224 from the
Komatsu Hot Tube testing apparatus is positioned between light
source 221 and photocell 222. A beam of light from the light source
is directed through the test tube 224 and is measured by the
photocell 222, which measures the amount of transmitted light,
converts this reading to an electrical signal, and transmits the
signal via line 223 to the computer controller 230. The computer
controller 230 has stored values of light transmittance (or
opacity) for the standard set of tubes and rates the oxidation
value of the test sample by comparison with the standard set. The
oxidation rating is assigned to the test sample (which can be
identified by the bar code) and the information is stored as a
component of the data library. The computer controller can
thereafter modify the selection instructions. Programming to
accomplish the various functions of the computer controller 230 are
within the purview of those with skill in the art.
[0070] In another oxidation stability test method of the present
invention, each of the foregoing samples can be placed in an
oxidation container and maintained at a predetermined temperature
for a predetermined time. The oxidation container can be a material
which is suitable for infrared transmittance, e.g., borosilicate
glass. The predetermined temperature can ordinarily range from
about 100.degree. C. to about 200.degree. C. and preferably from
about 140.degree. C. to about 180.degree. C. The predetermined time
may vary up to about 40 hours. Additionally, air is bubbled into
the test oil at a constant rate of flow and in the presence of a
metallic oxidation catalyst, e.g., a combination of metal ions such
as copper, lead and aluminum. The air flow rate can be determined
by one skilled in the art (e.g., 13.9 L/hr .+-.0.5 L/hr has been
used for a 200-g sample of test oil). The degree of oxidation is
then determined by measuring the infrared absorbance of the
carbonyl peak at 1710 cm.sup.-1 using, e.g., a Fourier transform
infrared spectrometer (e.g. a Bruker IFS 48 infrared apparatus). As
oxidation takes place, the absorbance peak at 1710 cm.sup.-1
increases owing to oxidation of the test oil as carbonyl-containing
functional groups are produced. A suitable high-throughput method
for measuring infrared absorbance is taught in US Patent
Application No. 2002/0197731. The data is then recorded in a
database.
[0071] Another oxidation stability test method of the present
invention utilizes differential scanning calorimetry. In general,
differential scanning calorimetry is a technique to measure
oxidation stability of a test oil sample as it is heated. In this
method, the sample is placed in a suitable vessel, e.g., a 10-mL
air-tight vial, and held at a predetermined temperature, e.g., from
about 120.degree. C. to about 200.degree. C., by using a heating
source, e.g., an oven. Automated data collection occurs throughout
the experiment with individual data points representing temperature
and heat flow between the sample and reference and each time of
measurement being recorded. Accordingly, an objective of this test
is to measure the thermal stability of an oil sample at a
predetermined temperature in air-tight model systems to determine
the exothermic release of heat. The temperature at which the
exothermic release of heat is observed is called the oxidation
onset temperature and is a measure of the oxidative stability of
the oil.
[0072] In an alternative embodiment of a oxidation stability test
method of the present invention (known as the thin film oxygen
uptake test (TFOUT) method, e.g., ASTM D 4742), a sample of oil is
weighed into a TFOUT glass dish together with a suitable amount of
a fuel fraction sample, liquid metal catalyst, and water sample.
The sample is placed in a suitable container, e.g., a steel bomb,
and charged with a predetermined amount of oxygen, e.g., from about
30 psi to about 90 psi, at room temperature. The container is then
submerged in an oil bath maintained at a predetermined temperature,
e.g., 120.degree. C. to about 200.degree. C., and rotated at a
predetermined speed, e.g., about 50 rpm to about 140 rpm. A chart
recorder can constantly monitors the oxygen pressure and when there
is a rapid pressure drop the test is over. The time from the start
of the test to the rapid pressure drop is recorded. A time greater
than a predetermined value is preferred, and is used as the basis
for assigning a pass/fail determination.
[0073] If desired, an assigned value of oxidation is programmed
into the computer controller for "pass/fail" determination.
Assigned pass/fail values can be selected based upon performance
requirements for specific lubricant applications and prospective
operating environments. If the test sample fails by having an
excessively high oxidation value, the test sample can be
electronically marked and future testing of lubricant oil
formulations having the same composition as the sample can be
eliminated from further testing for other performance
characteristics. By not retesting failed samples the system can be
made to operate more efficiently, energy and time being spent only
on samples which prospectively meet the desired product
specifications.
[0074] If desired the results of the method of the present
invention can be monitored from a remote location, i.e., a location
which is not in direct or at least in visual contact with the
system operating the method of the invention. A remote location can
be, for example, a central process control system or room which, as
part of the overall system for use herein, monitors and controls
the system as well as records the outputs of each of the results of
the tests being carried out. In this way, it becomes possible for
less interaction with personnel being stationed at the location of
the system. Suitable data lines, with which the results of the
output, as well as control commands, may be transmitted, are
known.
[0075] Oxidation stability data regarding the lubricating oil
compositions can be stored in a relational database to provide a
combinatorial lubricating oil composition library. Alternatively,
the system may be electrically connected to a signal data collector
comprising a computer microprocessor for system operation and
control to collect the data from the various tests over an extended
period of time to compile the combinatorial lubricating oil
composition library. The database can be used to find optimum
combinations for a desired product stream, and can be particularly
useful when the desired product stream varies depending on market
factors. When the product requirements change, appropriate
combinations can be selected to prepare the desired product.
[0076] Relational database software can be used to correlate the
identity of the lubricating oil compositions and the analytical
oxidation stability data obtained therefrom. Numerous commercially
available relational database software programs are available, for
example, from Oracle, Tripos, MDL, Oxford Molecular ("Chemical
Design"), IDBS ("Activity Base"), and other software vendors.
[0077] Relational database software is a preferred type of software
for managing the data obtained during the methods described herein.
However, any software that is able to create a "memory map" of the
lubricating oil compositions and correlate that information with
the information obtained from the storage stability measurements
can be used. This type of software is well known to those of skill
in the art.
[0078] While the above description contains many specifics, these
specifics should not be construed as limitations of the invention,
but merely as exemplifications of preferred embodiments thereof.
Those skilled in the art will envision many other embodiments
within the scope and spirit of the invention as defined by the
claims appended hereto.
* * * * *