U.S. patent application number 13/721153 was filed with the patent office on 2014-01-02 for marine engine lubrication.
The applicant listed for this patent is Minh Doan, Terence Garner, Frederick W. Girshick. Invention is credited to Minh Doan, Terence Garner, Frederick W. Girshick.
Application Number | 20140005087 13/721153 |
Document ID | / |
Family ID | 47351517 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140005087 |
Kind Code |
A1 |
Doan; Minh ; et al. |
January 2, 2014 |
Marine Engine Lubrication
Abstract
A two-stroke or four-stroke marine engine lubricating oil
composition comprising an oil of lubricating viscosity in a major
amount and (A) additives in respective minor amounts; and (B) a
polymethacrylate viscosity modifier. Preferably, brightstock is
completely or substantially absent from the composition.
Inventors: |
Doan; Minh; (Witney, GB)
; Garner; Terence; (Ellesmere Port, GB) ;
Girshick; Frederick W.; (Scotch Plains, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Doan; Minh
Garner; Terence
Girshick; Frederick W. |
Witney
Ellesmere Port
Scotch Plains |
NJ |
GB
GB
US |
|
|
Family ID: |
47351517 |
Appl. No.: |
13/721153 |
Filed: |
December 20, 2012 |
Current U.S.
Class: |
508/470 ;
508/469 |
Current CPC
Class: |
C10N 2030/52 20200501;
C10N 2040/252 20200501; C10N 2020/02 20130101; C10M 145/14
20130101; C10M 2209/084 20130101; C10N 2030/06 20130101; C10M
2203/108 20130101 |
Class at
Publication: |
508/470 ;
508/469 |
International
Class: |
C10M 145/14 20060101
C10M145/14 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2011 |
EP |
11195007.7 |
Claims
1. A two-stroke or four-stroke marine engine lubricating oil
composition comprising an oil of lubricating viscosity in a major
amount and (A) additives, in respective minor amounts; and (B) a
viscosity modifier in the form of a polymethacrylate in an amount
in the range of 0.05-6 mass %, wherein the composition includes
less than 0.5 mass % of brightstock; and wherein the two-stroke
marine engine lubricating oil composition has a TBN of 40 to 100 mg
KOH/g, as calculated using ASTM D2896, or the four-stroke marine
engine lubricating oil composition has a TBN of 20 to 60 mg KOH/g,
as calculated using ASTM D2896.
2. The composition as claimed in claim 1, wherein the
polymethacrylate has a weight-average molecular weight of 180,000
or more.
3. The composition as claimed in claim 1, wherein the
polymethacrylate is a polymer of CH.sub.2.dbd.C(CH.sub.3)COOR.sup.1
(I) where R.sup.1 is a straight chain or branched alkyl group
having 1-18 carbon atoms.
4. The composition as claimed in claim 3, wherein the
polymethacrylate is a copolymer of a monomer of formula (I) and a
N-containing monomer selected from
CH.sub.2.dbd.C(R.sup.2)COO--(R.sup.3).sub.a--X.sup.1 and
CH.sub.2.dbd.C(R.sup.4)X.sup.2 where R.sup.2 and R.sup.3 are each
independently, H or CH.sub.3; R.sup.3 is a straight chain or
branched alkylene group having 2-18 carbon atoms; a is 0 or 1;
X.sup.1 and X.sup.2 are each independently an amine residue or
heterocyclic ring having 1 or 2 N atoms and 0-20 atoms.
5. The composition as claimed in claim 1, in the form of a marine
diesel cylinder lubricant.
6. The composition as claimed in claim 1, in the form of a trunk
piston engine oil.
7. A method of lubricating a cross-head marine diesel engine
comprising supplying a composition as claimed in claim 1 to the
piston/cylinder assembly of the engine.
8. A method of lubricating a trunk piston marine diesel engine
comprising supplying a composition as claimed in claim 1 to the
engine.
9. A method of reducing the amount of brightstock in a two-stroke
or four-stroke marine engine lubricating oil composition comprising
an oil of lubricating viscosity in a major amount and (A)
additives, in respective minor amounts; the method comprising the
step of replacing, in part or in full, the brightstock with 0.05 to
6 mass % of (B) a viscosity modifier in the form of a
polymethacrylate.
10. The method as claimed in claim 9, wherein (B) substantially
replaces the brightstock so that the composition includes less than
0.5 mass %.
11. The method as claimed in claim 10, wherein the composition
includes less than 0.1 mass % of brightstock.
12. The method as claimed in claim 11, wherein the composition is
completely or substantially free from brightstock.
13. The method as claimed in claim 9, wherein the two-stroke marine
engine lubricating oil composition has a TBN of 40 to 100 mg KOH/g,
as calculated using ASTM D2896, or the four-stroke marine engine
lubricating oil composition has a TBN of 20 to 60 mg KOH/g, as
calculated using ASTM D2896.
Description
FIELD OF THE INVENTION
[0001] This invention relates to the lubrication of 2-stroke and
4-stroke marine diesel internal combustion engines, the former
usually being referred to as cross-head engines and the latter as
trunk piston engines. Respective lubricants therefor are usually
known as marine diesel cylinder lubricants ("MDCL's") and trunk
piston engine oils ("TPEO's").
BACKGROUND OF THE INVENTION
[0002] Cross-head engines are slow engines with a high to very high
power range. They include two separately-lubricated parts: the
piston/cylinder assembly lubricated with total-loss lubrication by
a highly viscous oil (an MDCL); and the crankshaft lubricated by a
less viscous lubricant, usually referred to as a system oil.
[0003] Trunk piston engines may be used in marine, power-generation
and rail traction applications and have a higher speed than
cross-head engines. A single lubricant (TPEO) is used for crankcase
and cylinder lubrication. All major moving parts of the engine,
i.e. the main and big end bearings, camshaft and valve gear, are
lubricated by means of a pumped circulation system. The cylinder
liners are lubricated partially by splash lubrication and partially
by oil from the circulation systems that finds its way to the
cylinder wall through holes in the piston skirt via the connecting
rod and gudgeon pin.
[0004] It is known in the art to include brightstock in MDCL's and
TPEO's, brightstock being a high viscosity oil that is highly
refined and dewaxed and that is produced from residual stocks or
bottoms. It may, for example, have a kinematic viscosity at
100.degree. C. of greater than 25, usually greater than 30,
mm.sup.2s.sup.-1, such as a solvent-extracted, de-asphalted product
from vacuum residuum generally having a kinematic viscosity at
100.degree. C. of 28-36 mm.sup.2s.sup.-1.
[0005] Brightstock is however expensive and art describes ways of
replacing it. WO 99/64543 describes MDCL's formulated without
brightstock and US 2008/0287329 describes a TPEO containing little
or no brightstock.
[0006] A problem in the art is to formulate brightstock-free MDCL's
and TPEO's at reduced cost and at the same time provide improved
antiwear properties.
SUMMARY OF THE INVENTION
[0007] It is now found that the use of polymethacrylate in an MDCL
or a TPEO enables the above problem to be overcome.
[0008] Thus, the present invention provides a two-stroke or
four-stroke marine engine lubricating oil composition comprising an
oil of lubricating viscosity in a major amount and [0009] (A)
additives, in respective minor amounts; and [0010] (B) a viscosity
modifier in the form of a polymethacrylate in an amount in the
range of 0.05-6 mass %, wherein the composition includes less than
0.5 mass %, preferably less than 0.1 mass %, of brightstock;
preferably brightstock is completely or substantially absent from
the composition.
[0011] In further aspects the present invention comprises:
[0012] The use of a viscosity modifier (B) to improve the anti-wear
properties of a marine diesel cylinder lubricant of a trunk piston
engine oil which includes less than 0.5 mass %, preferably less
than 0.1 mass %, of brightstock; preferably brightstock is absent
or is substantially absent from the marine diesel cylinder
lubricant or the trunk piston engine oil;
[0013] A method of lubricating a cross-head marine diesel engine
comprising supplying the composition to the piston/cylinder
assembly of the engine; and
[0014] A method of lubricating a trunk piston marine diesel engine
comprising supplying the composition to the engine.
[0015] In this specification, the following words and expressions,
if and when used, have the meanings ascribed below:
[0016] "active ingredients" or "(a.i.)" refers to additive material
that is not diluent or solvent;
[0017] "comprising" or any cognate word specifies the presence of
stated features, steps, or integers or components, but does not
preclude the presence or addition of one or more other features,
steps, integers, components or groups thereof; the expressions
"consists of" or "consists essentially of" or cognates may be
embraced within "comprises" or cognates, wherein "consists
essentially of" permits inclusion of substances not materially
affecting the characteristics of the composition to which it
applies;
[0018] "major amount" means 40 or 50 mass % or more of a
composition;
[0019] "minor amount" means less than 50 mass % of a
composition;
[0020] "TBN" means total base number as measured by ASTM D2896.
Furthermore in this specification, if and when used:
[0021] "calcium content" is as measured by ASTM 4951;
[0022] "phosphorus content" is as measured by ASTM D5185;
[0023] "sulphated ash content" is as measured by ASTM D874;
[0024] "sulphur content" is as measured by ASTM D2622;
[0025] "KV100" means kinematic viscosity at 100.degree. C. as
measured by ASTM D445.
[0026] Also, it will be understood that various components used,
essential as well as optimal and customary, may react under
conditions of formulation, storage or use and that the invention
also provides the product obtainable or obtained as a result of any
such reaction.
[0027] Further, it is understood that any upper and lower quantity,
range and ratio limits set forth herein may be independently
combined.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The features of the invention will now be discussed in more
detail below.
Oil of Lubricating Viscosity
[0029] The lubricant composition contains a major proportion of an
oil of lubricating viscosity. Such lubricating oils may range in
viscosity from light distillate mineral oils to heavy lubricating
oils. Generally, the viscosity of the oil ranges from 2 to 40, such
as 3 to 15, mm.sup.2/sec, as measured at 100.degree. C., and a
viscosity index of 80 to 100, such as 90 to 95. The lubricating oil
may comprise greater than 60, typically greater than 70. mass % of
the composition.
[0030] Natural oils include animal oils and vegetable oils (e.g.,
castor oil, lard oil); liquid petroleum oils and hydrorefined,
solvent-treated or acid-treated mineral oils of the paraffinic,
naphthenic and mixed paraffinic-naphthenic types. Oils of
lubricating viscosity derived from coal or shale also serve as
useful base oils.
[0031] Synthetic lubricating oils include 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)); alkybenzenes
(e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls,
terphenyls, alkylated polyphenols); and alkylated diphenyl ethers
and alkylated diphenyl sulphides and derivative, analogues and
homologues thereof
[0032] Alkylene oxide polymers and interpolymers and derivatives
thereof where the terminal hydroxyl groups have been modified by
esterification, etherification, etc., constitute another class of
known synthetic lubricating oils. These are exemplified by
polyoxyalkylene polymers prepared by polymerization of ethylene
oxide or propylene oxide, and the alkyl and aryl ethers of
polyoxyalkylene polymers (e.g., methyl-polyiso-propylene glycol
ether having a molecular weight of 1000 or diphenyl ether of
poly-ethylene glycol having a molecular weight of 1000 to 1500);
and mono- and polycarboxylic esters thereof, for example, the
acetic acid esters, mixed C.sub.3-C.sub.8 fatty acid esters and
C.sub.13 oxo acid diester of tetraethylene glycol.
[0033] Another suitable class of synthetic lubricating oils
comprises the esters of dicarboxylic acids (e.g., phthalic acid,
succinic acid, alkyl succinic acids and alkenyl succinic acids,
maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric
acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic
acids, alkenyl malonic acids) with a variety of alcohols (e.g.,
butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl
alcohol, ethylene glycol, diethylene glycol monoether, propylene
glycol). Specific examples of such esters includes 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, and the complex ester formed by reacting one mole of
sebacic acid with two moles of tetraethylene glycol and two moles
of 2-ethylhexanoic acid.
[0034] Esters useful as synthetic oils also include those made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols and polyol
esters such as neopentyl glycol, trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
[0035] Silicon-based oils such as the polyalkyl-, polyaryl-,
polyalkoxy- or polyaryloxysilicone oils and silicate oils comprise
another useful class of synthetic lubricants; such oils include
tetraethyl silicate, tetraisopropyl silicate,
tetra-(2-ethylhexyl)silicate,
tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl)
silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane,
poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other
synthetic lubricating oils include liquid esters of
phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl
phosphate, diethyl ester of decylphosphonic acid) and polymeric
tetrahydrofurans.
[0036] Unrefined, refined and re-refined oils can be used in
lubricants of the present invention. Unrefined oils are those
obtained directly from a natural or synthetic source without
further purification treatment. For example, a shale oil obtained
directly from retorting operations; petroleum oil obtained directly
from distillation; or ester oil obtained directly from
esterification and used without further treatment are unrefined
oils.
Marine Diesel Cylinder Lubricant ("MDCL")
[0037] An MDCL may employ 10-35, preferably 13-30, most preferably
16-24, mass % of a concentrate or additive package, the remainder
being base stock. It preferably includes at least 50, more
preferably at least 60, even more preferably at least 70, mass % of
oil of lubricating viscosity based on the total mass of MDCL.
Preferably, the MDCL has a compositional TBN (using ASTM D2896) of
40-100, such as 50-60.
[0038] The following may be mentioned as examples of typical
proportions of additives in an MDCL.
TABLE-US-00001 Mass % a.i. Mass % a.i. Additive (Broad) (Preferred)
detergent(s) 1-20 3-15 dispersant(s) 0.5-5 1-3 anti-wear agent(s)
0.1-1.5 0.5-1.3 pour point dispersant 0.03-1.15 0.05-0.1 base stock
balance balance
Trunk Piston Engine Oil ("TPEO")
[0039] A TPEO may employ 7-35, preferably 10-28, more preferably
12-24, mass % of a concentrate or additives package, the remainder
being base stock. Preferably, the TPEO has a compositional TBN
(using D2896) of 20-60, such as 25-55.
[0040] The following may be mentioned as typical proportions of
additives in a TPEO.
TABLE-US-00002 Mass % a.i. Mass % a.i. Additive (Broad) (Preferred)
detergent(s) 0.5-12 2-8 dispersant(s) 0.5-5 1-3 anti-wear agent(s)
0.1-1.5 0.5-1.3 oxidation inhibitor 0.2-2 0.5-1.5 rust inhibitor
0.03-0.15 0.05-0.1 pour point dispersant 0.03-1.15 0.05-0.1 base
stock balance balance
[0041] When a plurality of additives is employed it may be
desirable, although not essential, to prepare one or more additive
packages comprising the additives, whereby several additives can be
added simultaneously to the base oil to form the lubricating oil
composition. Dissolution of the additive package(s) into the
lubricating oil may be facilitated by solvents and by mixing
accompanied with mild heating, but this is not essential. The
additive package(s) will typically be formulated to contain the
additive(s) in proper amounts to provide the desired concentration,
and/or to carry out the intended function, in the final formulation
when the additive package(s) is/are combined with a predetermined
amount of base lubricant. Thus, compounds in accordance with the
present invention may be admixed with small amounts of base oil or
other compatible solvents together with other desirable additives
to form additive packages containing active ingredients.
[0042] More detailed description of additive components is given
below.
Detergents
[0043] A detergent is an additive that reduces formation of
deposits, for example, high-temperature varnish and lacquer
deposits, in engines; it has acid-neutralising properties and is
capable of keeping finely divided solids in suspension. It is based
on metal "soaps", that is, metal salts of acidic organic compounds,
sometimes referred to as surfactants.
[0044] A detergent comprises a polar head with a long hydrophobic
tail. Large amounts of a metal base are included by reacting an
excess of a metal compound, such as an oxide or hydroxide, with an
acidic gas such as carbon dioxide to give an overbased detergent
which comprises neutralised detergent as the outer layer of a metal
base (e.g. carbonate) micelle.
[0045] The detergent is preferably an alkali metal or alkaline
earth metal additive such as an overbased oil-soluble or
oil-dispersible calcium, magnesium, sodium or barium salt of a
surfactant selected from phenol, sulphonic acid, carboxylic acid,
salicylic acid and naphthenic acid, wherein the overbasing is
provided by an oil-insoluble salt of the metal, e.g. carbonate,
basic carbonate, acetate, formate, hydroxide or oxalate, which is
stabilised by the oil-soluble salt of the surfactant. The metal of
the oil-soluble surfactant salt may be the same or different from
that of the metal of the oil-insoluble salt. Preferably the metal,
whether the metal of the oil-soluble or oil-insoluble salt, is
calcium.
[0046] The TBN of the detergent may be low, i.e. less than 50 mg
KOH/g, medium, i.e. 50-150 mg KOH/g, or high, i.e. over 150 mg
KOH/g, as determined by ASTM D2896. Preferably the TBN is medium or
high, i.e. more than 50 TBN. More preferably, the TBN is at least
60, more preferably at least 100, more preferably at least 150, and
up to 500, such as up to 350 mg KOH/g, as determined by ASTM
D2896.
Anti-Oxidants
[0047] The trunk piston diesel engine lubricant composition may
include at least one anti-oxidant. The anti-oxidant may be aminic
or phenolic. As examples of amines there may be mentioned secondary
aromatic amines such as diarylamines, for example diphenylamines
wherein each phenyl group is alkyl-substituted with an alkyl group
having 4 to 9 carbon atoms. As examples of anti-oxidants there may
be mentioned hindered phenols, including mono-phenols and
bis-phenols.
[0048] Preferably, the anti-oxidant, if present, is provided in the
composition in an amount of up to 3 mass %, based on the total
amount of the lubricant composition.
[0049] Other additives such as pour point depressants,
anti-foamants, metal rust inhibitors, pour point depressants and/or
demulsifiers may be provided, if necessary.
[0050] The terms `oil-soluble` or `oil-dispersable` as used herein
do not necessarily indicate that the compounds or additives are
soluble, dissolvable, miscible or capable of being suspended in the
oil in all proportions. These do mean, however, that they are, for
instance, soluble or stably dispersible in oil to an extent
sufficient to exert their intended effect in the environment in
which the oil is employed. Moreover, the additional incorporation
of other additives may also permit incorporation of higher levels
of a particular additive, if desired.
[0051] The lubricant compositions of this invention comprise
defined individual (i.e. separate) components that may or may not
remain the same chemically before and after mixing.
[0052] It may be desirable, although not essential, to prepare one
or more additive packages or concentrates comprising the additives,
whereby the additives can be added simultaneously to the oil of
lubricating viscosity to form the lubricating oil composition.
Dissolution of the additive package(s) into the lubricating oil may
be facilitated by solvents and by mixing accompanied with mild
heating, but this is not essential. The additive package(s) will
typically be formulated to contain the additive(s) in proper
amounts to provide the desired concentration, and/or to carry out
the intended function in the final formulation when the additive
package(s) is/are combined with a predetermined amount of base
lubricant.
[0053] Thus, the additives may be admixed with small amounts of
base oil or other compatible solvents together with other desirable
additives to form additive packages containing active ingredients
in an amount, based on the additive package, of, for example, from
2.5 to 90, preferably from 5 to 75, most preferably from 8 to 60,
mass % of additives in the appropriate proportions, the remainder
being base oil.
[0054] The final formulations may typically contain about 5 to 40
mass % of the additive packages(s), the remainder being base
oil.
Viscosity Modifier
[0055] In this invention, as stated above, a viscosity modifier (B)
is additionally provided. Examples of ranges in the composition
include 0.1-6, 0.1-5, 0.1-4, 0.1-2.5, and lower limits of 0.5 and 1
mass %.
[0056] The polymethacrylate-based viscosity index improvers which
may be used in the present invention are any type of non-dispersion
type or dispersion type polymethacrylate compounds which are used
as viscosity modifiers for a lubricating oil.
[0057] The non-dispersion type polymethacrylate-based viscosity
index improver may be a polymer of a compound represented by the
formula
CH.sub.2.dbd.C(CH.sub.3)COOR.sup.1 (I)
[0058] In formula (1) R.sup.1 is a straight chain or branched alkyl
group such as methyl, ethyl, propyl, butyl, hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,
hexadecyl, heptadecyl, and octadecyl groups.
[0059] Specific examples of the dispersion type
polymethacrylate-based viscosity index improver are copolymers
obtained by copolymerizing one or more monomers selected from
compounds represented by formula (1) with one or more
nitrogen-containing monomers selected from compounds represented by
formulae (2) and (3)
CH.sub.2.dbd.C(R.sup.2)COO--(R.sup.3).sub.a--X.sup.1 (2)
CH.sub.2.dbd.C(R.sup.4)X.sup.2 (3)
[0060] In formulae (2) and (3) R.sup.2 and R.sup.4 are each
independently hydrogen or methyl. R.sup.3 is a straight chain or
branched alkylene group having 1 to 18 carbon atoms, such as
ethylene, propylene, butylene, pentylene, hexylene, heptylene,
octylene, nonylene, decylene, undecylene, dodecylene, tridecylene,
tetradecylene, pentadecylene, hexadecylene, heptadecylene, and
octadecylene groups; a is 0 or 1; X.sup.1 and X.sup.2 are each
independently an amino-or heterocyclic-residue having 1 or 2
nitrogen atoms and 0 to 2 oxygen atoms. Specific examples of
X.sup.1 and X.sup.2 are dimethylamino, diethylamino, dipropylamino,
dibutylamino, anilino, toluidino, xylidino, acetylamino,
benzoilamino, morpholino, pryrolyl, pyridyl, methylpyridyl,
pyrolidinyl, piperidinyl, quinonyl, pyrrolidonyl, pyrrolidono,
imidazolino, and pyrazino groups.
[0061] Specific examples of the nitrogen-containing monomers
represented by formula (2) and (3) are
dimethylaminomethylmethacrylate, diethylaminomethylmethacrylate,
dimethylaminoethylmethacrylate, diethylaminoethylmethacrylate,
2-methyl-5-vinylpyridine, morpholinomethylmethacrylate,
morpholinoethylmethacrylate, N-vinylpyrrolidone, and mixtures
thereof.
[0062] The lower limit of the weight-average molecular weight of
the polymethacrylate-based viscosity modifier, which is effective
in improving the performance of an engine oil, is preferably
180,000, more preferably 190,000. The upper limit is preferably
500,000, more preferably 400,000.
[0063] An engine oil composition according to the present invention
may contain the polymethacrylate-based viscosity modifier in such
an amount that the composition has a kinematic viscosity at
100.degree. C. of 4.0 to 9.3 mm.sup.2/s.
EXAMPLES
[0064] The present invention is illustrated by, but in no way
limited to, the following examples.
MDCL's
[0065] A set of MDCL's was formulated, each containing 20.89 mass %
of the same additives in the proportions and having a TBN of about
70. The set comprised a control consisting of additive and base
oil; a reference consisting of additives, base oil and brightstock;
and an inventive MDCL consisting of additives, base oil and
viscosity modifier. The additives were additives known in the art
and used in proportions known in the art for conferring MDCL
properties. The viscosity modifier was a polymethcylate (PMA)
supplied by Rohmax. The brightstock was a Group I bright stock with
a kinematic viscosity of >20 cSt at 100.degree. C. The base oil
was a Group 1 base oil.
TPEO's
[0066] A set of TPEO's was formulated, each containing 16 mass % of
the same additives in the same proportions and having a TBN of
about 40. The set comprised a control consisting of additives and
base oil; a reference consisting of additives, base oil and bright
stock; and an inventive MDCL consisting of additives, base oil and
viscosity modifier. The additives were additives known in the art
and used in proportions known in the art for conferring TPEO
properties. The viscosity modifier, brightstock and base oil were
used in the MDCL's.
Testing & Results
[0067] Samples of the above formulations were tested using a PCS
Instruments high frequency reciprocating rig (HFRR) on a standard
protocol comprising the following conditions: [0068] 120 minutes
[0069] 20 Hz reciprocation of 1 mm stroke length [0070] 200 g load
using standard equipment manufacturer supplied steel
substrates.
[0071] Each test was repeated two further times and the recorded
wear measurement was the average of these values.
[0072] The HFRR data for the compositions are summarized in the
table below.
TABLE-US-00003 TABLE Result Additive Base oil Brightstock PMA (wear
Ex (mass %) (mass %) (mass %) (mass %) vol m.sup.3) TPEO Control 16
84 -- -- 5,584 Reference 1 16 75.5 8.5 -- 8,279 16 83.37 -- 0.63
4,646 MDCL Control 20.89 79.11 -- -- 33,960 Reference 2 20.89 58.89
20.22 -- 3,940 20.89 77.61 -- 1.5 6,792
[0073] The above results show that the use of polymethacrylate
advantageously reduces the wear scar volume as compared to the
control and reference samples for TPEO oils. For MDCL it is clearly
advantageous to include the polymethacrylate versus using no
brightstock at all.
* * * * *