U.S. patent application number 14/221359 was filed with the patent office on 2014-09-25 for marine engine lubrication.
The applicant listed for this patent is Infineum International Limited. Invention is credited to Dhanesh Goberdhan, John H. Smythe.
Application Number | 20140287970 14/221359 |
Document ID | / |
Family ID | 47901880 |
Filed Date | 2014-09-25 |
United States Patent
Application |
20140287970 |
Kind Code |
A1 |
Smythe; John H. ; et
al. |
September 25, 2014 |
MARINE ENGINE LUBRICATION
Abstract
Marine engine (two- or four-stroke) lubrication is effected by a
composition comprising a major amount of an oil of lubricating
viscosity blended with minor amounts of one or more additives and a
star polymer or olefin co-polymer viscosity modifier dispersed in a
heavy basestock diluent oil.
Inventors: |
Smythe; John H.; (Wantage,
GB) ; Goberdhan; Dhanesh; (Oxford, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineum International Limited |
Abingdon |
|
GB |
|
|
Family ID: |
47901880 |
Appl. No.: |
14/221359 |
Filed: |
March 21, 2014 |
Current U.S.
Class: |
508/525 |
Current CPC
Class: |
C10M 2203/1025 20130101;
C10M 165/00 20130101; C10M 2205/028 20130101; C10M 2203/1006
20130101; C10M 2203/1085 20130101; C10N 2030/52 20200501; C10M
2207/262 20130101; C10M 169/04 20130101; C10M 143/00 20130101; C10N
2030/04 20130101; C10N 2020/073 20200501; C10M 2205/06 20130101;
C10M 2205/026 20130101; C10N 2030/08 20130101; C10N 2030/74
20200501; C10M 2205/024 20130101; C10N 2040/252 20200501; C10M
2207/262 20130101; C10N 2010/04 20130101; C10M 2205/06 20130101;
C10M 2205/04 20130101; C10M 2205/026 20130101; C10M 2205/022
20130101; C10M 2207/262 20130101; C10N 2010/04 20130101 |
Class at
Publication: |
508/525 |
International
Class: |
C10M 143/12 20060101
C10M143/12; C10M 143/04 20060101 C10M143/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2013 |
EP |
13160467.0 |
Claims
1. A two-stroke or four-stroke marine engine lubricating oil
composition comprising an oil of lubricating viscosity in a major
amount, and blended with: (A) one or more additives, in respective
minor amounts; and (B) a viscosity modifier in the form of either
(i) a polymer comprising a core and a plurality of polymeric arms
extending therefrom, or (ii) an olefin copolymer, the viscosity
modifier being dispersed in a diluent oil having a kinematic
viscosity at 100.degree. C. in the range of 6-15 mm.sup.2 s.sup.1,
wherein the two-stoke marine engine lubricating oil composition has
a TBN of 10 to 100 mg KOH/g, as measured using ASTM D2896 and the
four-stroke marine engine lubricating oil composition has a TBN of
25 to 60 mg KOH/g, as measured using ASTM D2896.
2. A method of making a two-stroke or four-stroke marine engine
lubricating oil composition comprising blending an oil of
lubricating viscosity in a major amount with: (A) one or more
additives, in relative minor amounts; and (B) a viscosity modifier
in the form of either (i) a polymer comprising a core and a
plurality of polymeric arms extending therefrom, or (ii) an olefin
copolymer, the viscosity modifier being dispersed in a diluent oil
of kinematic viscosity at 100.degree. C. in the range of 6-15
mm.sup.2 s.sup.-1, wherein the two-stoke marine engine lubricating
oil composition has a TBN of 10 to 100 mg KOH/g, as measured using
ASTM D2896 and the four-stroke marine engine lubricating oil
composition has a TBN of 25 to 60 mg KOH/g, as measured using ASTM
D2896.
3. A two-stroke or four-stroke marine engine lubricating oil
composition obtained or obtainable by the method of claim 2.
4. The composition of claim 1, wherein the composition contains
less than 0.5 mass % of brightstock.
5. The composition of claim 4, wherein the composition is
completely or substantially free of brightstock.
6. The method of claim 2, wherein the composition contains less
than 0.5 mass % of brightstock.
7. The method of claim 6, wherein the composition is completely or
substantially free of brightstock.
8. The composition of claim 1, wherein the viscosity modifier (B)
is present in the composition in an amount in the range of 0.01 to
40 mass %.
9. The composition of claim 8, wherein the viscosity modifier (B)
comprises the polymer (i), the arms of which comprise a
hydrogenated isoprene-butadiene copolymer, a hydrogenated
styrene-isoprene-butadiene copolymer, a hydrogenated
isoprene-styrene copolymer or a hydrogenated butadiene-styrene
copolymer.
10. The composition claim 8, wherein the viscosity modifier (B)
comprises the olefin copolymer (ii) as a copolymer of two or more
monomers of C.sub.2-C.sub.30 olefins, such as a copolymer of
ethylene with a C.sub.3-C.sub.30 olefin such as propylene.
11. The method of claim 2, wherein the viscosity modifier (B) is
present in the composition in an amount in the range of 0.01 to 40
mass %.
12. The method of claim 11, wherein the viscosity modifier (B)
comprises the polymer (i), the arms of which comprise a
hydrogenated isoprene-butadiene copolymer, a hydrogenated
styrene-isoprene-butadiene copolymer, a hydrogenated
isoprene-styrene copolymer or a hydrogenated butadiene-styrene
copolymer.
13. The method of claim 11, wherein the viscosity modifier (B)
comprises the olefin copolymer (ii) as a copolymer of two or more
monomers of C.sub.2-C.sub.30 olefins, such as a copolymer of
ethylene with a C.sub.3-C.sub.30 olefin such as propylene.
14. The composition of claim 1, wherein the composition is in the
form of a marine diesel cylinder lubricant.
15. The composition of claim 1, wherein the composition is in the
form of a trunk piston engine oil.
16. The method of claim 2, wherein the composition is in the form
of a marine diesel cylinder lubricant.
17. The method of claim 2, wherein the composition is in the form
of a trunk piston engine oil.
18. A method of lubricating a cross-head marine diesel engine
comprising supplying a composition of claim 1 to the
piston/cylinder of the engine.
19. A method of lubricating a trunk piston marine diesel engine
comprising supplying a composition of claim 1 to the engine.
20. The composition of claim 1, wherein the oil of lubricating
viscosity contains 50% or more of a basestock that contains greater
than or equal to 90% saturates and less than or equal to 0.03%
sulphur.
21. The method of claim 2, wherein the oil of lubricating viscosity
contains 50% or more of a basestock that contains less than 90
percent saturates and/or greater than 0.03% sulphur.
22. The method of claim 18, wherein the oil of lubricating
viscosity contains 50% or more of a basestock that contains less
than 90 percent saturates and/or greater than 0.03% sulphur.
23. The method of claim 19, wherein the oil of lubricating
viscosity contains 50% or more of a basestock that contains less
than 90 percent saturates and/or greater than 0.03% sulphur.
Description
FIELD OF THE INVENTION
[0001] This invention relates to the lubrication of two-stroke and
four-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 with
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. Both use liquid, oil-miscible polyisobutylene
(`PIB`).
[0006] A problem with brightstock-free MDCL's and TPEO's is that
they give rise to evaporation debits (i.e. lubricating oil
evaporation and consumption). As discussed in US 2008/0287329, the
degradation of polyisobutylene leads to the formation of volative
products that escape from the engine, which results in lube oil
consumption.
[0007] The aim of the invention is to overcome the problems of the
prior art. In particular, an aim of the present invention is to
reduce lubricating oil consumption.
SUMMARY OF THE INVENTION
[0008] It is now found that the use of star polymers (such as an
amorphous styrene-diene copolymer) or olefin copolymers (such as an
ethylene-propylene copolymer) dispersed in a heavy diluent oil in
an MDCL or a TPEO enables the above problem to be overcome.
[0009] 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 blended with
[0010] (A) one of more additives, in respective minor amounts; and
[0011] (B) a viscosity modifier in the form of either (i) a polymer
comprising a core and a plurality of polymeric arms extending
therefrom, or (ii) an olefin copolymer, the viscosity modifier
being dispersed in a heavy diluent oil of kinematic viscosity at
100.degree. C. in the range of 6-15, such as 7-14, mm.sup.2s.sup.-1
wherein the two-stoke marine engine lubricating oil composition has
a TBN of 10 to 100 such as 40 to 100 using ASTM D2896 and the
four-stroke marine engine lubricating oil composition has a TBN of
25 to 60 using ASTM D2896.
[0012] In further aspects the present invention comprises:--
[0013] a method of making a two-stroke or four-stroke marine engine
lubricating oil composition comprising blending an oil of
lubricating viscosity in a major amount with: [0014] (A) one or
more additives, in respective minor amounts; and [0015] (B) a
viscosity modifier in the form of either (i) a polymer comprising a
core and a plurality of polymeric arms extending therefrom, or (ii)
an olefin copolymer, the viscosity modifier being dispersed in a
heavy diluent oil of kinematic viscosity at 100.degree. C. in the
range of 6-15, such as 7-14, mm.sup.2 s.sup.-1, wherein the
two-stoke marine engine lubricating oil composition has a TBN of 10
to 100 such as 40 to 100 using ASTM D2896 and the four-stroke
marine engine lubricating oil composition has a TBN of 25 to 60
using ASTM D2896;
[0016] a two-stroke or four-stroke marine engine lubricating oil
composition obtainable by the above method of this invention.
[0017] a method of lubricating a cross-head marine diesel engine
comprising supplying the composition of the invention to the
piston/cylinder assembly of the engine;
[0018] a method of lubricating a trunk piston marine diesel engine
comprising supplying the composition to the engine; and the use of
a viscosity modifier (B) as defined in the first aspect of the
invention to improve the carbon deposition properties of a marine
diesel cylinder lubricant of TBN 10-100 such as 40 to 100 using
ASTM D2896 or a trunk piston engine oil having a TBN of 25-60 using
ASTM D2896.
[0019] In this specification, the following words and expressions,
if and when used, have the meanings ascribed below: [0020] "active
ingredients" or "(a.i.)" refers to additive material that is not
diluent or solvent; [0021] "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; [0022] "major amount" means 40 or 50 mass % or
more of a composition, preferably 60 mass % or more, even more
preferably 70 mass % or more; [0023] "minor amount" means less than
50 mass % of a composition, preferably less than 40 mass %, even
more preferably less than 30 mass %; [0024] "TBN" means total base
number as measured by ASTM D2896. Furthermore in this
specification, if and when used:
[0025] "calcium content" is as measured by ASTM 4951;
[0026] "phosphorus content" is as measured by ASTM D5185;
[0027] "sulphated ash content" is as measured by ASTM D874;
[0028] "sulphur content" is as measured by ASTM D2622;
[0029] "KV100" means kinematic viscosity at 100.degree. C. as
measured by ASTM D445.
[0030] 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.
[0031] 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
[0032] The features of the invention will now be discussed in more
detail below.
Oil of Lubricating Viscosity
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] The American Petroleum Institute (API) publication "Engine
Oil Licensing and Certification System", Industry Services
Department, Fourteenth Edition, December 1996, Addendum 1, December
1998 categorizes base stocks as follows: [0042] a) Group I base
stocks contain less than 90 percent saturates and/or greater than
0.03 percent sulphur and have a viscosity index greater than or
equal to 80 and less than 120 using the test methods specified in
Table E-1. [0043] b) Group II base stocks contain greater than or
equal to 90 percent saturates and less than or equal to 0.03
percent sulphur and have a viscosity index greater than or equal to
80 and less than 120 using the test methods specified in Table E-1.
[0044] c) Group III base stocks contain greater than or equal to 90
percent saturates and less than or equal to 0.03 percent sulphur
and have a viscosity index greater than or equal to 120 using the
test methods specified in Table E-1. [0045] d) Group IV base stocks
are polyalphaolefins (PAO). [0046] e) Group V base stocks include
all other base stocks not included in Group I, II, III, or IV.
[0047] Analytical Methods for Base Stock are tabulated below:
TABLE-US-00001 PROPERTY TEST METHOD Saturates ASTM D 2007 Viscosity
Index ASTM D 2270 Sulphur ASTM D 2622 ASTM D 4294 ASTM D 4927 ASTM
D 3120
[0048] The present invention preferably embraces those of the above
oils containing greater than or equal to 90% saturates and less
than or equal to 0.03% sulphur as the oil of lubricating viscosity,
eg Group II, III, IV or V. They also include basestocks derived
from hydrocarbons synthesised by the Fischer-Tropsch process. In
the Fischer-Tropsch process, synthesis gas containing carbon
monoxide and hydrogen (or `syngas`) is first generated and then
converted to hydrocarbons using a Fischer-Tropsch catalyst. These
hydrocarbons typically require further processing in order to be
useful as a base oil. For example, they may, by methods known in
the art, be hydroisomerized; hydrocracked and hydroisomerized;
dewaxed; or hydroisomerized and dewaxed. The syngas may, for
example, be made from gas such as natural gas or other gaseous
hydrocarbons by steam reforming, when the basestock may be referred
to as gas-to-liquid ("GTL") base oil; or from gasification of
biomass, when the basestock may be referred to as biomass-to-liquid
("BTL" or "BMTL") base oil; or from gasification of coal, when the
basestock may be referred to as coal-to-liquid ("CTL") base
oil.
[0049] Preferably, the oil of lubricating viscosity in this
invention contains 50 mass % or more said basestocks. It may
contain 60, such as 70, 80 or 90, mass % or more of said basestock
or a mixture thereof. The oil of lubricating viscosity may be
substantially all of said basestock or a mixture thereof.
Marine Diesel Cylinder Lubricant ("MDCL")
[0050] 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
10-100, such as 40-100, preferably 60-90, more preferably
70-80.
[0051] The following may be mentioned as examples of typical
proportions of additives in an MDCL.
TABLE-US-00002 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")
[0052] 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 25-60, such as 25-55.
[0053] The following may be mentioned as typical proportions of
additives in a TPEO.
TABLE-US-00003 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
Additives (A)
[0054] More detailed description of additive components is given
below.
Detergents
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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
[0059] 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.
[0060] 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.
[0061] Other additives such as pour point depressants,
anti-foamants, metal rust inhibitors, pour point depressants and/or
demulsifiers may be provided, if necessary.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] The final formulations may typically contain about 5 to 40
mass % of the additive packages(s), the remainder being base
oil.
Viscosity Modifier (B)
[0067] In this invention, as stated above, a viscosity modifier (B)
is additionally provided in the form of (i) a so-called star
polymer, or (ii) an olefin copolymer. Its concentration in the
composition may, for example, be in the range of 0.01 to 40 mass
%.
(i) Star Polymers
[0068] These are polymers comprising a core and a plurality of
polymeric arms extending from the core. Such polymers are known as
star-shaped polymers (or star or radial polymers). Examples of
ranges of (B) in the composition include 0.1-6, 0.1-5, 0.1-4,
0.1-3, mass % and a lower limit of 1 mass %.
[0069] The viscosity modifier may comprise at least one
star-shaped, at least partially hydrogenated, polymer derivable, at
least in part, from the polymerisation of one or more conjugated
diene monomers as defined hereinbefore. Suitably, the star-shaped
polymer includes multiple arms extending from a central core; the
arms being derived from the polymerisation of one or more
conjugated diene monomers as defined hereinbefore, and optionally a
vinyl aromatic hydrocarbon monomer as defined hereinbefore.
[0070] The arms of the star polymer may be a homopolymer derived
essentially from the polymerisation of a single conjugated diene
monomer as defined herein, such as isoprene or 1,3-butadiene,
particularly isoprene.
[0071] Alternatively, the arms of the star polymer may be a
copolymer derived essentially from the polymerisation of two or
more conjugated diene monomers as defined herein, such as an
isoprene and 1,3-butadiene copolymer, or a copolymer derived
essentially from the polymerisation of one or more conjugated diene
monomers as defined herein and a vinyl aromatic hydrocarbon monomer
as defined herein, such as an isoprene-styrene copolymer, a
butadiene-styrene copolymer or an isoprene-butadiene-styrene
copolymer.
[0072] As used herein in connection with polymer composition,
"derived essentially" permits the inclusion of other substances not
materially affecting the characteristics of the polymer to which it
applies. Preferably, "derived essentially" means the specified
monomer and comonomers, in the case of a copolymer, are present in
an amount of at least 90%, more preferably 95%, even more
preferably greater than 99% by mass of the polymer.
[0073] The arms of the star polymer may also be a block copolymer,
preferably a linear block copolymer, more preferably a linear
diblock copolymer, such as one represented by the following general
formula:
A.sub.z-(B-A).sub.y-B.sub.x
wherein: A is a polymeric block derived predominantly from vinyl
aromatic hydrocarbon monomer; B is a polymeric block derived
predominantly from conjugated diene monomer; x and z are,
independently, a number equal to 0 or 1; and y is a whole number
ranging from 1 to about 15.
[0074] The arms of the star polymer may also be a tapered linear
block copolymer such as one represented by the following general
formula:
A-A/B-B
wherein: A is a polymeric block derived predominantly from vinyl
aromatic hydrocarbon monomer; B is a polymeric block derived
predominantly from conjugated diene monomer; and A/B is a tapered
segment derived from both vinyl aromatic hydrocarbon monomer and
conjugated diolefin monomer.
[0075] Preferably, the arms of the star polymer comprise a
hydrogenated isoprene-butadiene copolymer, a hydrogenated
styrene-isoprene-butadiene copolymer, a hydrogenated
isoprene-styrene copolymer or a hydrogenated butadiene-styrene
copolymer.
[0076] Most preferably, the arms of the star polymer comprise a
linear diblock copolymer as defined herein. Preferably, the linear
diblock copolymer comprises at least one block derivable
predominantly from a vinyl aromatic hydrocarbon monomer as defined
herein and at least one block derivable predominantly from one or
more conjugated diene monomers as defined herein. Preferably, the
vinyl aromatic hydrocarbon monomer comprises styrene. Preferably,
the one or more conjugated diene monomers comprise isoprene,
butadiene or a mixture thereof. Most preferably, the linear diblock
copolymer is at least partially hydrogenated.
[0077] Preferably, the at least one block derivable predominantly
from a vinyl aromatic hydrocarbon monomer (e.g. styrene) in the
linear diblock copolymer is present in an amount of up to 35%, even
more preferably up to 25%, most preferably 5 to 25%, by mass based
on the total mass of the linear diblock copolymer.
[0078] Preferably, the at least one block derivable from
predominantly from one or more conjugated diene monomers is present
in an amount of greater than 65%, even more preferably greater than
or equal to 75%, most preferably 75 to 95%, by mass based on the
total mass of the linear diblock copolymer.
[0079] Preferably, the linear diblock copolymer comprises at least
one polystyrene block and a block derived from isoprene, butadiene,
or a mixture thereof. Highly preferred linear diblock copolymers
comprise linear diblock copolymers including at least one linear
diblock copolymer selected from hydrogenated styrene/isoprene
diblock copolymers, hydrogenated styrene/butadiene diblock
copolymers and hydrogenated styrene/isoprene-butadiene diblock
copolymers.
[0080] Preferably, when the linear diblock copolymer comprises at
least one isoprene-butadiene block the block is derived
predominantly from 70 to 90 mass % isoprene monomers and 30 to 10
mass % 1,3-butadiene monomers.
[0081] The arms of the star polymer typically comprise a copolymer
derived from 70 to 90 mass % isoprene monomers and 30 to 10 mass %
1,3-butadiene monomers. More preferably, the arms of the star
polymer further include a vinyl aromatic hydrocarbon monomer as
defined herein, particularly styrene. A highly preferred copolymer
is derived from isoprene monomers, 1,3-butadiene monomers and a
vinyl aromatic hydrocarbon monomer, especially styrene. The vinyl
aromatic hydrocarbon monomer may be present in an amount of up to
35 mass %, preferably up to 25 mass %, based on the total mass of
the copolymer.
[0082] Preferably, the arms of the star polymer are formed via
anionic polymerization to form a living polymer. Anionic
polymerization has been found to provide copolymers having a narrow
molecular weight distribution (Mw/Mn), such as a molecular weight
distribution of less than about 1.2
[0083] As is well known, and disclosed, for example, in U.S. Pat.
No. 4,116,917, living polymers may be prepared by anionic solution
polymerization of a mixture of the conjugated diene monomers in the
presence of an alkali metal or an alkali metal hydrocarbon, e.g.,
sodium naphthalene, as anionic initiator. The preferred initiator
is lithium or a monolithium hydrocarbon. Suitable lithium
hydrocarbons include unsaturated compounds such as allyl lithium,
methallyl lithium; aromatic compounds such as phenyl lithium, the
tolyl lithiums, the xylyl lithiums and the naphthyl lithiums, and
in particular, the alkyl lithiums such as methyl lithium, ethyl
lithium, propyl lithium, butyl lithium, amyl lithium, hexyl
lithium, 2-ethylhexyl lithium and n-hexadecyl lithium.
Secondary-butyl lithium is the preferred initiator. The
initiator(s) may be added to the polymerization mixture in two or
more stages, optionally together with additional monomer. The
living polymers are olefinically unsaturated.
[0084] The solvents in which the living polymers are formed are
inert liquid solvents, such as hydrocarbons e.g., aliphatic
hydrocarbons such as pentane, hexane, heptane, octane,
2-ethylhexane, nonane, decane, cyclohexane, methylcyclohexane, or
aromatic hydrocarbons e.g., benzene, toluene, ethylbenzene, the
xylenes, diethylbenzenes, propylbenzenes. Cyclohexane is preferred.
Mixtures of hydrocarbons e.g., lubricating oils, may also be
used.
[0085] The temperature at which the polymerization is conducted may
be varied within a wide range, such as from about -50.degree. C. to
about 150.degree. C., preferably from about 20.degree. C. to about
80.degree. C. The reaction is suitably carried out in an inert
atmosphere, such as nitrogen, and may optionally be carried out
under pressure e.g., a pressure of from about 0.5 to about 10
bars.
[0086] The concentration of the initiator used to prepare the
living polymer may also vary within a wide range and is determined
by the desired molecular weight of the living polymer.
[0087] To form the star polymer, the living polymers formed via the
foregoing process are reacted in an additional reaction step, with
a polyalkenyl coupling agent. Polyalkenyl coupling agents capable
of forming star polymers have been known for a number of years and
are described, for example, in U.S. Pat. No. 3,985,830. Polyalkenyl
coupling agents are conventionally compounds having at least two
non-conjugated alkenyl groups. Such groups are usually attached to
the same or different electron-withdrawing moiety e.g. an aromatic
nucleus. Such compounds have the property that at least of the
alkenyl groups are capable of independent reaction with different
living polymers and in this respect are different from conventional
conjugated diene polymerizable monomers such as butadiene,
isoprene, etc. Pure or technical grade polyalkenyl coupling agents
may be used. Such compounds may be aliphatic, aromatic or
heterocyclic. Examples of aliphatic compounds include the polyvinyl
and polyallyl acetylene, diacetylenes, phosphates and phosphates as
well as dimethacrylates, e.g. ethylene dimethylacrylate. Examples
of suitable heterocyclic compounds include divinyl pyridine and
divinyl thiophene.
[0088] The preferred coupling agents are polyalkenyl aromatic
compounds and most preferred are the polyvinyl aromatic compounds.
Examples of such compounds include those aromatic compounds, e.g.
benzene, toluene, xylene, anthracene, naphthalene and durene, which
are substituted with at least two alkenyl groups, preferably
attached directly thereto. Specific examples include the polyvinyl
benzenes e.g. divinyl, trivinyl and tetravinyl benzenes; divinyl,
trivinyl and tetravinyl ortho-, meta- and para-xylenes, divinyl
naphthalene, divinyl ethyl benzene, divinyl biphenyl, diisobutenyl
benzene, diisopropenyl benzene, and diisopropenyl biphenyl. The
preferred aromatic compounds are those represented by the formula
A-(CH.dbd.CH.sub.2).sub.x wherein A is an optionally substituted
aromatic nucleus and x is an integer of at least 2. Divinyl
benzene, in particular meta-divinyl benzene, is the most preferred
aromatic compound. Pure or technical grade divinyl benzene
(containing other monomers e.g. styrene and ethyl styrene) may be
used. The coupling agents may be used in admixture with small
amounts of added monomers which increase the size of the nucleus,
e.g. styrene or alkyl styrene. In such a case, the nucleus can be
described as a poly(dialkenyl coupling agent/monoalkenyl aromatic
compound) nucleus, e.g. a poly(divinylbenzene/monoalkenyl aromatic
compound) nucleus.
[0089] The polyalkenyl coupling agent should be added to the living
polymer after the polymerization of the monomers is substantially
complete, i.e. the agent should be added only after substantially
all the monomer has been converted to the living polymers.
[0090] The amount of polyalkenyl coupling agent added may vary
within a wide range, but preferably, at least 0.5 mole of the
coupling agent is used per mole of unsaturated living polymer.
Amounts of from about 1 to about 15 moles, preferably from about
1.5 to about 5 moles per mole of living polymer are preferred. The
amount, which can be added in two or more stages, is usually an
amount sufficient to convert at least about 80 mass % to 85 mass %
of the living polymer into star-shaped polymer.
[0091] The coupling reaction can be carried out in the same solvent
as the living polymerization reaction. The coupling reaction can be
carried out at temperatures within a broad range, such as from
0.degree. C. to 150.degree. C., preferably from about 20.degree. C.
to about 120.degree. C. The reaction may be conducted in an inert
atmosphere, e.g. nitrogen, and under pressure of from about 0.5 bar
to about 10 bars.
[0092] The star polymers thus formed are characterized by a dense
centre or nucleus of crosslinked poly(polyalkenyl coupling agent)
and a number of arms of substantially linear unsaturated polymers
extending outwardly from the nucleus. The number of arms may vary
considerably, but is typically between about 4 and 25.
[0093] The resulting star polymers can then be hydrogenated using
any suitable means. A hydrogenation catalyst may be used e.g. a
copper or molybdenum compound. Catalysts containing noble metals,
or noble metal-containing compounds, can also be used. Preferred
hydrogenation catalysts contain a non-noble metal or a non-noble
metal-containing compound of Group VIII of the periodic Table i.e.,
iron, cobalt, and particularly, nickel. Specific examples of
preferred hydrogenation catalysts include Raney nickel and nickel
on kieselguhr. Particularly suitable hydrogenation catalysts are
those obtained by causing metal hydrocarbyl compounds to react with
organic compounds of any one of the group VIII metals iron, cobalt
or nickel, the latter compounds containing at least one organic
compound that is attached to the metal atom via an oxygen atom as
described, for example, in U.K. Patent No. 1,030,306. Preference is
given to hydrogenation catalysts obtained by causing an aluminium
trialkyl (e.g. aluminium diethyl (Al(Et.sub.3)) or aluminium
triisobutyl) to react with a nickel salt of an organic acid (e.g.
nickel diisopropyl salicylate, nickel naphthenate, nickel 2-ethyl
hexanoate, nickel di-tert-butyl benzoate, nickel salts of saturated
monocarboxylic acids obtained by reaction of olefins having from 4
to 20 carbon atoms in the molecule with carbon monoxide and water
in the presence of acid catalysts) or with nickel enolates or
phenolates (e.g., nickel acetonylacetonate, the nickel salt of
butylacetophenone). Suitable hydrogenation catalysts will be well
known to those skilled in the art and the foregoing list is by no
means intended to be exhaustive.
[0094] The hydrogenation of the star polymer is suitably conducted
in solution, in a solvent which is inert during the hydrogenation
reaction. Saturated hydrocarbons and mixtures of saturated
hydrocarbons are suitable. Advantageously, the hydrogenation
solvent is the same as the solvent in which polymerization is
conducted. Suitably, at least 50%, preferably at least 70%, more
preferably at least 90%, most preferably at least 95% by mass of
the original olefinic unsaturation is hydrogenated.
[0095] The hydrogenated star polymer may then be recovered in solid
form from the solvent in which it is hydrogenated by any convenient
means, such as by evaporating the solvent. Alternatively, oil e.g.
lubricating oil, may be added to the solution, and the solvent
stripped off from the mixture so formed to provide a concentrate.
Suitable concentrates contain from about 3 mass % to about 25 mass
%, preferably from about 5 mass % to about 15 mass % of the
hydrogenated star polymer VI improver.
[0096] The star polymers useful in the practice of the present
invention can have a number average molecular weight of from about
10,000 to 700,000, preferably from about 30,000 to 500,000. The
term "number average molecular weight", as used herein, refers to
the number average weight as measured by Gel Permeation
Chromatography ("GPC") with a polystyrene standard, subsequent to
hydrogenation. It is important to note that, when determining the
number average molecular weight of a star polymer using this
method, the calculated number average molecular weight will be less
than the actual molecular weight due to the three dimensional
structure of the star polymer.
[0097] In one preferred embodiment, the star polymer of the present
invention is derived from about 75% to about 90% by mass isoprene
and about 10% to about 25% by mass butadiene, and greater than 80%
by mass of the butadiene units are incorporated 1,4-addition
product. In another preferred embodiment, the star polymer of the
present invention comprises amorphous butadiene units derived from
about 30 to about 80% by mass 1,2-, and from about 20 to about 70%
by mass 1,4-incorporation of butadiene. In another preferred
embodiment, the star polymer is derived from isoprene, butadiene,
or a mixture thereof, and further contains from about 5 to about
35% by mass styrene units.
[0098] Typically, the star polymer has a Shear Stability Index
(SSI) of from about 1% to 35% (30 cycle). An example of a
commercially available star polymer VI improver having an SSI equal
to or less than 35 is Infineum SV200.TM., available from Infineum
USA L.P. and Infineum UK Ltd. Other examples of commercially
available star polymer VI improver having an SSI equal to or less
than 35 include Infineum SV250.TM., Infineum SV261.TM. and Infineum
SV270.TM., also available from Infineum USA L.P. and Infineum UK
Ltd.
[0099] Typically, the viscosity modifier may be provided in an
amount of from 0.01 to 20, preferably 1 to 15, mass % based on the
mass of the lubricating oil composition.
[0100] Optionally, one or both types of viscosity modifiers used in
the practice of the invention can be provided with
nitrogen-containing functional groups that impart dispersant
capabilities to the VI improver. One trend in the industry has been
to use such "multifunctional" VI improvers in lubricants to replace
some or all of the dispersant. Nitrogen-containing functional
groups can be added to a polymeric VI improver by grafting a
nitrogen- or hydroxyl-containing moiety, preferably a
nitrogen-containing moiety, onto the polymeric backbone of the VI
improver (functionalizing). Processes for the grafting of a
nitrogen-containing moiety onto a polymer are known in the art and
include, for example, contacting the polymer and
nitrogen-containing moiety in the presence of a free radical
initiator, either neat, or in the presence of a solvent. The free
radical initiator may be generated by shearing (as in an extruder)
or heating a free radical initiator precursor, such as hydrogen
peroxide.
[0101] The amount of nitrogen-containing grafting monomer will
depend, to some extent, on the nature of the substrate polymer and
the level of dispersancy required of the grafted polymer. To impart
dispersancy characteristics to both star and linear copolymers, the
amount of grafted nitrogen-containing monomer is suitably between
about 0.4 and about 2.2 mass %, preferably from about 0.5 to about
1.8 mass %, most preferably from about 0.6 to about 1.2 mass %,
based on the total weight of grafted polymer.
[0102] Methods for grafting nitrogen-containing monomer onto
polymer backbones, and suitable nitrogen-containing grafting
monomers are known and described, for example, in U.S. Pat. No.
5,141,996, WO 98/13443, WO 99/21902, U.S. Pat. No. 4,146,489, U.S.
Pat. No. 4,292,414, and U.S. Pat. No. 4,506,056. (See also J
Polymer Science, Part A: Polymer Chemistry, Vol. 26, 1189-1198
(1988); J. Polymer Science, Polymer Letters, Vol. 20, 481-486
(1982) and J. Polymer Science, Polymer Letters, Vol. 21, 23-30
(1983), all to Gaylord and Mehta and Degradation and Cross-linking
of Ethylene-Propylene Copolymer Rubber on Reaction with Maleic
Anhydride and/or Peroxides; J. Applied Polymer Science, Vol. 33,
2549-2558 (1987) to Gaylord, Mehta and Mehta.
(ii) Olefin Copolymers
[0103] In this invention olefin copolymers (OCP's) may be used.
Examples of ranges in the composition include 0.1-6, 0.1-5, 0.1-4,
mass % and lower limits of 1 or 2 mass %.
[0104] These may be copolymers of two or more monomers of C.sub.2
to C.sub.30, e.g. C.sub.2 to C.sub.8, olefins, including both
alpha-olefins and internal olefins, which may be straight or
branched, aliphatic, aromatic, alkyl-aromatic, or cycloaliphatic.
Frequently, they are of ethylene with C.sub.3 to C.sub.30 olefins,
particularly preferred being copolymers of ethylene and propylene.
They may also be copolymers of C.sub.6 and higher alpha olefins and
terpolymers of styrene, e.g. with isoprene and/or butadiene and
hydrogenated derivatives thereof.
[0105] Preferred OCP's are ethylene copolymers containing 15 to 90,
preferably 30 to 80, mass % of ethylene and 10 to 85, preferably 20
to 70, mass % of one or more C.sub.3 to C.sub.28, preferably
C.sub.3 to C.sub.18, more preferably C.sub.3 to C.sub.8,
alpha-olefins. Such OCP's may have a degree of crystallinity of
less than 25 mass %, as determined by x-ray and differential
scanning calorimetry. As indicated above, copolymers of ethylene
and propylene are most preferred. Other alpha-olefins suitable in
place of propylene, or in combination with ethylene and propylene
to form a terpolymer or tetrapolymer, for example, include:
1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,
1-decene; and branched chain alpha-olefins such as
4-methyl-1-pentene, 4-methyl-1-hexene, 4-methyl pentene-1, 4,
4-dimethyl-1-pentene, 6-methylheptene-1, and mixtures thereof.
[0106] There may also be included terpolymers and tetrapolymers of
ethylene, said C3 to C28 alpha-olefin, and a non-conjugated
diolefin or mixtures of such diolefins. The non-conjugated diolefin
is generally present as 0.5 to 20, preferably 1 to 7, mole percent
of the total moles of ethylene and alpha-olefin.
Diluent Oil
[0107] The viscosity modifier is dispersed (e.g. dissolved) in a
heavy basestock diluent oil. As stated, the latter has a kinematic
viscosity at 100.degree. C. in the range of 6-15, preferably 7-14,
mm.sup.2s.sup.-1. As examples of concentrations of the viscosity
modifier in the heavy basestock diluent oil, the following ranges,
in mass %, may be mentioned; 0.05 to 5, such as to 4, 3 or 2; 0.01
to 5, 4, 3 or 2, preferably 0.01 to 2; more preferably 1 to 2 such
as 1 to 1.5. The main consideration is that the resulting
dispersion should have the same or similar kinematic viscosity to
that of a brightstock oil.
Examples
[0108] The present invention is illustrated by, but not limited to,
the following examples.
Formulations
Marine Diesel Cylinder Lubricants (MDCL's)
[0109] Each MDCL comprised a calcium alkylsalicylate detergent
package of basicity index 18 and containing 12.4 mass % Ca; 23 mass
% of a viscosity modifier or, as a comparison, of a brightstock or
polyisobutylene; and 55.6 mass % of an oil of lubricating viscosity
(a Group I oil (XOM600)). All MDCL's had a TBN of about 70. The
detailed formulations are given in TABLE 1 below.
[0110] The viscosity modifiers used were: [0111] a star polymer in
the form of an amorphous styrene-diene copolymer dispersed either
in a heavy oil diluent or a light oil diluent ("star"); and [0112]
an olefin copolymer in the form of an amorphous ethylene-propylene
copolymer dispersed either in a heavy oil diluent or a light oil
diluent ("OCP")
[0113] The brightstock used was a Group I brightstock with a
kinematic viscosity at 100.degree. C. of greater than 20
mm.sup.2s.sup.-1.
Trunk Piston Engine Oils (TPEO's)
[0114] Each TPEO comprised a calcium alkylsalicylate detergent
package of basicity index 5.8 and containing 8.9 mass % Ca; 7 mass
% of a viscosity modifier or, as a comparison, of a brightstock or
polyisobutylene; and 77.1 mass % of an oil of lubricating viscosity
(a Group II oil (Chevron 600)). All TPEO's had a TBN of 40. The
detailed formulations are given in TABLE 2 below. The viscosity
modifiers, the brightstock and the polyisobutylene were the same as
those in the MDCL's.
Testing & Results
[0115] Samples of the above formulations were tested for carbon
deposition properties using the Panel Coker Test and for
evaporation loss using the NOACK volatility tests. The tests are
described as follows:
Panel Coker Test
[0116] Lubricating oils may degrade on hot engine surfaces and
leave deposits which will affect engine performance; the panel
coker test simulates typical conditions and measures the tendency
of oils to form such deposits. The oil under test is splashed onto
a heated metal plate by spinning a metal comb-like splasher device
within a sump containing the oil. At the end of the test period,
deposits are measured.
[0117] An overview of the test method is as follows: [0118] 225 ml
of the oil is heated in an oil bath to 100.degree. C. [0119] A
heated aluminium panel is located above the oil bath at an incline,
maintained at a temperature of 320.degree. C. [0120] The oil is
splashed for 15 seconds against this panel, followed by no
splashing for 45 seconds. [0121] This cycle of intermittent
splashing is continued for 1 hour. [0122] The panel is weighed and
the deposits are calculated in grams (g).
[0123] NOACK Volatility Test determines the evaporation loss of
lubricants in high temperature service. It is otherwise known as
ASTM D-5800.
TABLE-US-00004 TABLE 1 An MDCL including a major amount of a Group
I oil (XOM600) Star (1.3%) in Star (1.3%) in OCP (1.4%) in OCP
(1.4%) in NOACK Diluent having a Diluent having a Diluent having a
Diluent having a D5800 Evap. Kv100 11.21 mm.sup.2 Kv100 5.21
mm.sup.2 Kv100 11.21 mm.sup.2 Kv100 5.21 mm.sup.2 Polyisobutylene
Panel Coker Loss Ex s.sup.-1 s.sup.-1 s.sup.-1 s.sup.-1 Brightstock
950 Mol. Wt. (g) (mass %) 1 0.0426 3.8 A 0.0736 6.6 2 0.0755 4.0 B
0.0509 6.7 C 0.0988 3.9 D 0.0452 4.4
[0124] Table 1 shows that replacing brightstock with either star
polymer or an olefin copolymer reduces the amount of deposits in
the Panel Coker Test. Table 1 also shows that the use of higher
viscosity diluent for the star polymer and the olefin copolymer
reduces the evaporation loss (i.e. the lube oil consumption)
compared to the use of a lighter viscosity diluent.
[0125] In the Tables, a tick indicates presence of a particular
component and a blank space indicates absence.
TABLE-US-00005 TABLE 2 TPEO including a major amount of a Group II
oil (Chevron 600) Star (1.3%) in Star (1.3%) in OCP (1.4%) in OCP
(1.4%) in NOACK Diluent having Diluent having Diluent having
Diluent having D5800 Evap. a Kv100 12.16 a Kv100 5.21 a Kv100 12.16
a Kv100 5.21 Polyisobutylene Panel Coker Loss Ex mm.sup.2 s.sup.-1
mm.sup.2 s.sup.-1 mm.sup.2 s.sup.-1 mm.sup.2 s.sup.-1 Brightstock
(Mol. Weight 950) (g) (mass %) 3 0.0191 3.7 W 0.0188 4.1 4 0.0187
3.2 X 0.0166 3.9 Y 0.0310 3.1 Z 0.0193 3.4
[0126] Table 2 shows that replacing brightstock with either star
polymer or an olefin copolymer reduces the amount of deposits in
the Panel Coker Test. Table 2 also shows that the use of a higher
viscosity diluent for the star polymer and the olefin copolymer
reduces the evaporation loss (i.e. the lube oil consumption)
compared to the use of a lighter viscosity diluent.
[0127] Examples 1-4 fall within the invention. Examples A-D and W-Z
are comparative examples.
* * * * *