U.S. patent application number 13/262934 was filed with the patent office on 2012-02-02 for marine engine lubrication.
Invention is credited to Terence Garner, Laury Gregory, Joseph Peter Hartley, Peter Watts.
Application Number | 20120028522 13/262934 |
Document ID | / |
Family ID | 40718757 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120028522 |
Kind Code |
A1 |
Garner; Terence ; et
al. |
February 2, 2012 |
MARINE ENGINE LUBRICATION
Abstract
Trunk piston marine engine lubrication, when the engine is
fueled by heavy fuel oil, is effected by a composition comprising a
major amount of an oil of lubricating viscosity containing at least
50 mass % of a basestock containing greater than or equal to 90%
saturates and less than or equal to 0.03% sulphur or a mixture
thereof, and respective minor amounts of an over-based metal
hydrocarbyl-substituted hydroxybenzoate detergent other than such a
detergent having a basicity index of less than two and a degree of
carbonation of 80% or greater and at least 1 mass % of a
hydrocarbyl-substituted carboxylic acid, anhydride, ester or amide
thereof. Asphaltene precipitation in the lubricant, caused by the
presence of contaminant heavy fuel oil, is prevented or
inhibited.
Inventors: |
Garner; Terence;
(Oxfordshire, GB) ; Gregory; Laury; (Oxfordshire,
GB) ; Hartley; Joseph Peter; (Oxfordshire, GB)
; Watts; Peter; (Oxfordshire, GB) |
Family ID: |
40718757 |
Appl. No.: |
13/262934 |
Filed: |
March 31, 2010 |
PCT Filed: |
March 31, 2010 |
PCT NO: |
PCT/EP2010/002131 |
371 Date: |
October 5, 2011 |
Current U.S.
Class: |
440/88L ;
508/306 |
Current CPC
Class: |
C10M 2207/129 20130101;
C10M 2219/089 20130101; C10M 2207/262 20130101; C10M 2207/282
20130101; C10N 2030/04 20130101; C10N 2040/252 20200501; C10M
2205/0285 20130101; C10M 2203/1025 20130101; C10N 2010/04 20130101;
C10M 2207/127 20130101; C10M 2207/126 20130101; C10M 2215/08
20130101; C10M 2203/1006 20130101; C10M 169/045 20130101; C10M
2215/28 20130101; C10M 2203/10 20130101; C10M 2203/1025 20130101;
C10N 2020/02 20130101; C10M 2207/262 20130101; C10N 2010/04
20130101; C10M 2203/1025 20130101; C10N 2020/02 20130101; C10M
2207/262 20130101; C10N 2010/04 20130101 |
Class at
Publication: |
440/88.L ;
508/306 |
International
Class: |
B63H 21/38 20060101
B63H021/38; C10M 129/26 20060101 C10M129/26 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2009 |
EP |
09157524.1 |
Claims
1. A trunk piston marine engine lubricating oil composition for
improving asphaltene handling in use thereof, in operation of the
engine when fuelled by a heavy fuel oil, which composition
comprises or is made by admixing an oil of lubricating viscosity,
in a major amount, containing 50 mass % or more of a basestock
containing greater than or equal to 90% saturates and less than or
equal to 0.03% sulphur or a mixture thereof, and, in respective
minor amounts: (A) an overbased metal hydrocarbyl-substituted
hydroxybenzoate detergent other than such a detergent having a
basicity index of less than two and a degree of carbonation of 80%
or greater, where degree of carbonation is the percentage of
carbonate present in the overbased metal hydrocarbyl-substituted
hydroxybenzoate detergent expressed as a mole percentage relative
to the total excess base in the detergent; and (B) a
hydrocarbyl-substituted carboxylic acid, anhydride, ester or amide
thereof, wherein the or at least one hydrocarbyl group contains at
least eight carbon atoms, the acid, anhydride, ester or amine
constituting at least 1 mass % of the lubricating oil
composition.
2. The composition as claimed in claim 1 wherein (A) has (A1) a
basicity index of two or greater and a degree of carbonation of 80%
or greater; or (A2) a basicity index of two or greater and a degree
of carbonation of less than 80%; or (A3) a basicity index of less
than two and a degree of carbonation of less than 80%.
3. The composition as claimed in claim 1 wherein (B) is depicted
as: ##STR00003## where R.sup.1 represents a C.sub.8 to C.sub.100
branched or linear hydrocarbyl; X and Y each independently
represents OR.sup.2 and OR.sup.3, where each R.sup.2 and R.sup.3
independently represents a hydrogen atom or an alkyl, aryl or
aralkyl group, or X and Y together represent --O--; and/or are
depicted as R.sup.1CH.sub.2COR.sup.4 (II) where R.sup.1 is as
defined as above; and R.sup.4 represents OR.sup.5 or
NR.sup.6R.sup.7, where each R.sup.5, R.sup.6 and R.sup.7
independently represents a hydrogen atom or an alkyl group.
4. The composition as claimed in claim 1 wherein the metal in (A)
is calcium.
5. The composition as claimed in claim 1 wherein the
hydrocarbyl-substituted hydroxybenzoate in (A) is a salicylate.
6. The composition as claimed in claim 1 wherein the oil of
lubricating viscosity contains more than 60 mass % of a basestock
containing greater than or equal to 90% saturates and less than or
equal to 0.03% sulphur or a mixture thereof.
7. The composition as claimed in claim 1 wherein the hydrocarbyl
group in (B) has from 8 to 400 carbon atoms.
8. The composition as claimed in claim 1 wherein, in the acid or
derivative (B), the hydrocarbyl substituent is derived from a
polyolefin.
9. The composition as claimed in claim 1 wherein (B) is a succinic
acid or a succinic anhydride.
10. The composition as claimed in claim 9 wherein (B) is a
polyisobutene succinic acid or anhydride.
11. The composition as claimed in claim 1 having a TBN of 20 to
60.
12. (canceled)
13. A method of operating a trunk piston medium-speed
compression-ignited marine engine comprising (i) fueling the engine
with a heavy fuel oil; and (ii) lubricating the crankcase of the
engine with a composition as defined in claim 1.
14. A method of dispersing asphaltenes in a trunk piston marine
lubricating oil composition during its lubrication of surfaces of
the combustion chamber of a medium-speed compression-ignited marine
engine and operation of the engine, which method comprises (i)
providing a composition as defined in claim 1: (ii) providing the
composition in the combustion chamber; (iii) providing heavy fuel
oil in the combustion chamber; and (iv) combusting the heavy fuel
oil in the combustion chamber.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a trunk piston marine engine
lubricating composition for a medium-speed four-stroke
compression-ignited (diesel) marine engine and lubrication of such
an engine.
BACKGROUND OF THE INVENTION
[0002] Marine trunk piston engines generally use Heavy Fuel Oil
(`HFO`) for offshore running. Heavy Fuel Oil is the heaviest
fraction of petroleum distillate and comprises a complex mixture of
molecules including up to 15% of asphaltenes, defined as the
fraction of petroleum distillate that is insoluble in an excess of
aliphatic hydrocarbon (e.g. heptane) but which is soluble in
aromatic solvents (e.g. toluene). Asphaltenes can enter the engine
lubricant as contaminants either via the cylinder or the fuel pumps
and injectors, and asphaltene precipitation can then occur,
manifested in `black paint` or `black sludge` in the engine. The
presence of such carbonaceous deposits on a piston surface can act
as an insulating layer which can result in the formation of cracks
that then propagate through the piston. If a crack travels through
the piston, hot combustion gases can enter the crankcase, possibly
resulting in a crankcase explosion.
[0003] It is therefore highly desirable that trunk piston engine
oils (`TPEO`s) prevent or inhibit asphaltene precipitation. The
prior art describes ways of doing this.
[0004] WO 96/26995 discloses the use of a hydrocarbyl-substituted
phenol to reduce `black paint` in a diesel engine. WO 96/26996
discloses the use of a demulsifier for water-in-oil emulsions, for
example, a polyoxyalkylene polyol, to reduce `black paint` in
diesel engines. US-B2-7,053,027 describes use of one or more
overbased metal carboxylate detergents in combination with an
antiwear additive in a dispersant-free TPEO.
[0005] The problem of asphaltene precipitation is more acute at
higher basestock saturate levels. WO 2008/128656 describes a
solution by use of an overbased metal hydrocarbyl-substituted
hydroxybenzoate detergent having a basicity index of less than 2
and a degree of carbonation of 80% or greater in a marine trunk
piston engine lubricant to reduce asphaltene precipitation in the
lubricant. Mentioned, but not exemplified, are lubricants
comprising Group III and Group IV basestocks, and exemplified are
lubricants comprising a Group II basestock, all of which basestocks
have high saturates levels.
[0006] The above-described solution is however restricted to a
specific class of detergents. It is now found, in the present
invention, that the problem in WO 2008/128656 is solved for a
different range of overbased metal carboxylate detergents by
employing, in combination therewith, a hydrocarbyl-substituted
carboxylic acid, anhydride, ester or amide in high saturates
basestocks.
[0007] WO-A-2008/021737 describes lubricating an internal
combustion engine with a composition that includes at least 0.5 wt
% of a carboxylic acid or an anhydride thereof. It exemplifies such
compositions that include an overbased phenate and an overbased
sulfonate and provides panel coker test data thereof. It does not
however address the presence of heavy fuel oil in the
composition.
SUMMARY OF THE INVENTION
[0008] A first aspect of the invention is a trunk piston marine
engine lubricating oil composition for improving asphaltene
handling in use thereof, in operation of the engine when fuelled by
a heavy fuel oil, which composition comprises or is made by
admixing an oil of lubricating viscosity, in a major amount,
containing 50 mass % or more of a basestock containing greater than
or equal to 90% saturates and less than or equal to 0.03% sulphur
or a mixture thereof, and, in respective minor amounts: [0009] (A)
an overbased metal hydrocarbyl-substituted hydroxybenzoate
detergent other than such a detergent having a basicity index of
less than two and a degree of carbonation of 80% or greater, where
degree of carbonation is the percentage of carbonate present in the
overbased metal hydrocarbyl-substituted hydroxybenzoate detergent
expressed as a mole percentage relative to the total excess base in
the detergent; and [0010] (B) a hydrocarbyl-substituted carboxylic
acid, anhydride, ester or amide thereof, wherein the or at least
one hydrocarbyl group contains at least eight carbon atoms, the
acid, anhydride, ester or amide constituting at least 1 mass % of
the lubricating oil composition.
[0011] A second aspect of the invention is the use of a detergent
(A) in combination with a carboxylic acid, anhydride, ester or
amide (B) as defined in, and in the amounts stated in, the first
aspect of the invention in a trunk piston marine lubricating oil
composition for a medium-speed compression-ignited marine engine,
which composition comprises an oil of lubricating viscosity in a
major amount and contains 50 mass % or more of a basestock
containing greater than or equal to 90% saturates and less than or
equal to 0.03% sulphur or a mixture thereof, to improve asphaltene
handling during operation of the engine, fueled by a heavy fuel
oil, and its lubrication by the composition, in comparison with
analogous operation when the same amount of detergent (A) is used
in the absence of (B).
[0012] A third aspect of the invention is a method of operating a
trunk piston medium-speed compression-ignited marine engine
comprising [0013] (i) fueling the engine with a heavy fuel oil; and
[0014] (ii) lubricating the crankcase of the engine with a
composition as defined in the first aspect of the invention.
[0015] A fourth aspect of the invention is a method of dispersing
asphaltenes in a trunk piston marine lubricating oil composition
during its lubrication of surfaces of the combustion chamber of a
medium-speed compression-ignited marine engine and operation of the
engine, which method comprises [0016] (i) providing a composition
as defined in the first aspect of the invention; [0017] (ii)
providing the composition in the combustion chamber; [0018] (iii)
providing heavy fuel oil in the combustion chamber; and [0019] (iv)
combusting the heavy fuel oil in the combustion chamber.
[0020] In this specification, the following words and expressions,
if and when used, have the meanings ascribed below: [0021] "active
ingredients" or "(a.i.)" refers to additive material that is not
diluent or solvent; [0022] "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; [0023] "major amount" means in excess of 50 mass
% of a composition; [0024] "minor amount" means less than 50 mass %
of a composition; [0025] "TBN" means total base number as measured
by ASTM D2896. Furthermore in this specification: [0026] "calcium
content" is as measured by ASTM 4951; [0027] "phosphorus content"
is as measured by ASTM D5185; [0028] "sulphated ash content" is as
measured by ASTM D874; [0029] "sulphur content" is as measured by
ASTM D2622; [0030] "KV100" means kinematic viscosity at 100.degree.
C. as measured by ASTM D445.
[0031] 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.
[0032] 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
[0033] The features of the invention will now be discussed in more
detail below.
Oil of Lubricating Viscosity
[0034] The 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 mm.sup.2/sec, as measured
at 100.degree. C.
[0035] Natural oils include animal oils and vegetable oils (e.g.,
caster 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.
[0036] 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, analogs and
homologs thereof.
[0037] 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.
[0038] 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, sebasic 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.
[0039] 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.
[0040] 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 phosphorous-containing acids (e.g.,
tricresyl phosphate, trioctyl phosphate, diethyl ester of
decylphosphonic acid) and polymeric tetrahydrofurans.
[0041] 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 an
esterification and used without further treatment would be an
unrefined oil. Refined oils are similar to unrefined oils except
that the oil is further treated in one or more purification steps
to improve one or more properties. Many such purification
techniques, such as distillation, solvent extraction, acid or base
extraction, filtration and percolation are known to those skilled
in the art. Re-refined oils are obtained by processes similar to
those used to provide refined oils but begin with oil that has
already been used in service. Such re-refined oils are also known
as reclaimed or reprocessed oils and are often subjected to
additional processing using techniques for removing spent additives
and oil breakdown products.
[0042] 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: [0043] 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. [0044] 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.
[0045] 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. [0046] d) Group IV base stocks
are polyalphaolefins (PAO). [0047] e) Group V base stocks include
all other base stocks not included in Group I, II, III, or IV.
[0048] 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
[0049] By way of example, the present invention embraces Group II,
Group III and Group IV basestocks and also 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.
[0050] As stated, the oil of lubricating viscosity in this
invention contains 50 mass % or more of the defined basestock or a
mixture thereof. Preferably, it contains 60, such as 70, 80 or 90,
mass % or more of the defined basestock or a mixture thereof. The
oil of lubricating viscosity may be substantially all the defined
basestock or a mixture thereof.
Overbased Metal Detergent (A)
[0051] A metal detergent is an additive based on so-called metal
"soaps", that is metal salts of acidic organic compounds, sometimes
referred to as surfactants. They generally comprise a polar head
with a long hydrophobic tail. Overbased metal detergents, which
comprise neutralized metal detergents as the outer layer of a metal
base (e.g. carbonate) micelle, may be provided by including large
amounts of metal base by reacting an excess of a metal base, such
as an oxide or hydroxide, with an acidic gas such as carbon
dioxide.
[0052] In the present invention, overbased metal detergents (A) are
overbased metal hydrocarbyl-substituted hydroxybenzoate, preferably
hydrocarbyl-substituted salicylate, detergents.
[0053] "Hydrocarbyl" means a group or radical that contains carbon
and hydrogen atoms and that is bonded to the remainder of the
molecule via a carbon atom. It may contain hetero atoms, i.e. atoms
other than carbon and hydrogen, provided they do not alter the
essentially hydrocarbon nature and characteristics of the group. As
examples of hydrocarbyl, there may be mentioned alkyl and alkenyl.
The overbased metal hydrocarbyl-substituted hydroxybenzoate
typically has the structure shown:
##STR00001##
wherein R is a linear or branched aliphatic hydrocarbyl group, and
more preferably an alkyl group, including straight- or
branched-chain alkyl groups. There may be more than one R group
attached to the benzene ring. M is an alkali metal (e.g. lithium,
sodium or potassium) or alkaline earth metal (e.g. calcium,
magnesium barium or strontium). Calcium or magnesium is preferred;
calcium is especially preferred. The COOM group can be in the
ortho, meta or para position with respect to the hydroxyl group;
the ortho position is preferred. The R group can be in the ortho,
meta or para position with respect to the hydroxyl group.
[0054] Hydroxybenzoic acids are typically prepared by the
carboxylation, by the Kolbe-Schmitt process, of phenoxides, and in
that case, will generally be obtained (normally in a diluent) in
admixture with uncarboxylated phenol. Hydroxybenzoic acids may be
non-sulphurized or sulphurized, and may be chemically modified
and/or contain additional substituents. Processes for sulphurizing
a hydrocarbyl-substituted hydroxybenzoic acid are well known to
those skilled in the art, and are described, for example, in US
2007/0027057.
[0055] In hydrocarbyl-substituted hydroxybenzoic acids, the
hydrocarbyl group is preferably alkyl (including straight- or
branched-chain alkyl groups), and the alkyl groups advantageously
contain 5 to 100, preferably 9 to 30, especially 14 to 24, carbon
atoms.
[0056] The term "overbased" is generally used to describe metal
detergents in which the ratio of the number of equivalents of the
metal moiety to the number of equivalents of the acid moiety is
greater than one. The term low-based' is used to describe metal
detergents in which the equivalent ratio of metal moiety to acid
moiety is greater than 1, and up to about 2.
[0057] By an "overbased calcium salt of surfactants" is meant an
overbased detergent in which the metal cations of the oil-insoluble
metal salt are essentially calcium cations. Small amounts of other
cations may be present in the oil-insoluble metal salt, but
typically at least 80, more typically at least 90, for example at
least 95, mole %, of the cations in the oil-insoluble metal salt,
are calcium ions. Cations other than calcium may be derived, for
example, from the use in the manufacture of the overbased detergent
of a surfactant salt in which the cation is a metal other than
calcium. Preferably, the metal salt of the surfactant is also
calcium.
[0058] Carbonated overbased metal detergents typically comprise
amorphous nanoparticles. Additionally, there are disclosures of
nanoparticulate materials comprising carbonate in the crystalline
calcite and vaterite forms.
[0059] The basicity of the detergents may be expressed as a total
base number (TBN). A total base number is the amount of acid needed
to neutralize all of the basicity of the overbased material. The
TBN may be measured using ASTM standard D2896 or an equivalent
procedure. The detergent may have a low TBN (i.e. a TBN of less
than 50), a medium TBN (i.e. a TBN of 50 to 150) or a high TBN
(i.e. a TBN of greater than 150, such as 150-500). In this
invention, Basicity Index and Degree of Carbonation may be used.
Basicity Index is the molar ratio of total base to total soap in
the overbased detergent. Degree of Carbonation is the percentage of
carbonate present in the overbased detergent expressed as a mole
percentage relative to the total excess base in the detergent.
[0060] Overbased metal hydrocarbyl-substituted hydroxybenzoates can
be prepared by any of the techniques employed in the art. A general
method is as follows: [0061] 1. Neutralisation of
hydrocarbyl-substituted hydroxybenzoic acid with a molar excess of
metallic base to produce a slightly overbased metal
hydrocarbyl-substituted hydroxybenzoate complex, in a solvent
mixture consisting of a volatile hydrocarbon, an alcohol and water;
[0062] 2. Carbonation to produce colloidally-dispersed metal
carbonate followed by a post-reaction period; [0063] 3. Removal of
residual solids that are not colloidally dispersed; and [0064] 4.
Stripping to remove process solvents.
[0065] Overbased metal hydrocarbyl-substituted hydroxybenzoates can
be made by either a batch or a continuous overbasing process.
[0066] Metal base (e.g. metal hydroxide, metal oxide or metal
alkoxide), preferably lime (calcium hydroxide), may be charged in
one or more stages. The charges may be equal or may differ, as may
the carbon dioxide charges which follow them. When adding a further
calcium hydroxide charge, the carbon dioxide treatment of the
previous stage need not be complete. As carbonation proceeds,
dissolved hydroxide is converted into colloidal carbonate particles
dispersed in the mixture of volatile hydrocarbon solvent and
non-volatile hydrocarbon oil.
[0067] Carbonation may by effected in one or more stages over a
range of temperatures up to the reflux temperature of the alcohol
promoters. Addition temperatures may be similar, or different, or
may vary during each addition stage. Phases in which temperatures
are raised, and optionally then reduced, may precede further
carbonation steps.
[0068] The volatile hydrocarbon solvent of the reaction mixture is
preferably a normally liquid aromatic hydrocarbon having a boiling
point not greater than about 150.degree. C. Aromatic hydrocarbons
have been found to offer certain benefits, e.g. improved filtration
rates, and examples of suitable solvents are toluene, xylene, and
ethyl benzene.
[0069] The alkanol is preferably methanol although other alcohols
such as ethanol can be used. Correct choice of the ratio of alkanol
to hydrocarbon solvents, and the water content of the initial
reaction mixture, are important to obtain the desired product.
[0070] Oil may be added to the reaction mixture; if so, suitable
oils include hydrocarbon oils, particularly those of mineral
origin. Oils which have viscosities of 15 to 30 mm.sup.2/sec at
38.degree. C. are very suitable.
[0071] After the final treatment with carbon dioxide, the reaction
mixture is typically heated to an elevated temperature, e.g. above
130.degree. C., to remove volatile materials (water and any
remaining alkanol and hydrocarbon solvent). When the synthesis is
complete, the raw product is hazy as a result of the presence of
suspended sediments. It is clarified by, for example, filtration or
centrifugation. These measures may be used before, or at an
intermediate point, or after solvent removal.
[0072] The products are generally used as an oil solution. If the
reaction mixture contains insufficient oil to retain an oil
solution after removal of the volatiles, further oil should be
added. This may occur before, or at an intermediate point, or after
solvent removal.
[0073] In this invention, (A) may have: [0074] (A1) a basicity
index of two or greater and a degree of carbonation of 80% or
greater; or [0075] (A2) a basicity index of two or greater and a
degree of carbonation of less than 80%; or [0076] (A3) a basicity
index of less than two and a degree of carbonation of less than
80%.
Carboxylic Acid, Anhydride, Ester or Amide Thereof (B)
[0077] As stated, the acid, anhydride, ester or amide thereof
constitutes at least 1 mass % of the lubricating oil composition.
Preferably it constitutes from 1.5 such as up to 10, such as 2 to
10, for example 3 to 6, mass %. (B) may be a mixture.
[0078] The acid may be mono or polycarboxylic, preferably
dicarboxylic, acid. The hydrocarbyl group preferably has from 8 to
400, such as 8 to 100, carbon atoms.
[0079] As (B), an anhydride of a dicarboxylic acid is
preferred.
[0080] Esters may be half or diesters when the acid is a
dicarboxylic acid. Ester groups may include alkyl, aryl, or
aralkyl, and amide groups may be unsubstituted or carry one or more
alkyl, aryl or aralkyl groups.
[0081] General formulae of exemplary monocarboxylic and
dicarboxylic acids and anhydrides, esters or amides thereof may be
depicted as
##STR00002##
[0082] where R.sup.1 represents a C.sub.8 to .sub.0100 branched or
linear hydrocarbyl such as a polyalkenyl, alkyl or alkaryl
group;
[0083] X and Y each independently represents OR.sup.2 and OR.sup.3,
where each R.sup.2 and R.sup.3 independently represents a hydrogen
atom, or an alkyl, aryl or aralkyl group, or X and Y together
represent --O--; and/or depicted as
R.sup.1CH.sub.2COR.sup.4 (II)
[0084] where R.sup.4 represents OR.sup.5 or NR.sup.6R.sup.7, where
each R.sup.5, R.sup.6 and R.sup.7 independently represents a
hydrogen atom or an alkyl group.
[0085] Preferably, the hydrocarbyl group is a polyalkenyl group.
Such polyalkenyl moiety may have a number average molecular weight
of from 200 to 3000, preferably from 350 to 950.
[0086] Suitable hydrocarbons or polymers employed in the formation
of the acid/derivative of the present invention include
homopolymers, interpolymers or lower molecular weight hydrocarbons.
One family of such polymers comprise polymers of ethylene and/or at
least one C.sub.3 to C.sub.28 alpha-olefin having the formula
H.sub.2C.dbd.CHR.sup.1 wherein R.sup.1 is straight or branched
chain alkyl radical comprising 1 to 26 carbon atoms and wherein the
polymer contains carbon-to-carbon unsaturation, preferably a high
degree of terminal ethenylidene unsaturation. Preferably, such
polymers comprise interpolymers of ethylene and at least one
alpha-olefin of the above formula, wherein R.sup.1 is alkyl of from
1 to 18 carbon atoms, and more preferably is alkyl of from 1 to 8
carbon atoms, and more preferably still of from 1 to 2 carbon
atoms. Therefore, useful alpha-olefin monomers and comonomers
include, for example, propylene, butene-1, hexene-1,
octene-1,4-methylpentene-1, decene-1, dodecene-1, tridecene-1,
tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1,
octadecene-1, nonadecene-1, and mixtures thereof (e.g., mixtures of
propylene and butene-1, and the like). Exemplary of such polymers
are propylene homopolymers, butene-1 homopolymers,
ethylene-propylene copolymers, ethylene-butene-1 copolymers,
propylene-butene copolymers and the like, wherein the polymer
contains at least some terminal and/or internal unsaturation.
Preferred polymers are unsaturated copolymers of ethylene and
propylene and ethylene and butene-1. The interpolymers of this
invention may contain a minor amount, e.g. 0.5 to 5 mole % of a
C.sub.4 to C.sub.18 non-conjugated diolefin comonomer. However, it
is preferred that the polymers of this invention comprise only
alpha-olefin homopolymers, interpolymers of alpha-olefin comonomers
and interpolymers of ethylene and alpha-olefin comonomers. The
molar ethylene content of the polymers employed in this invention
is preferably in the range of 0 to 80%, and more preferably 0 to
60%. When propylene and/or butene-1 are employed as comonomer(s)
with ethylene, the ethylene content of such copolymers is most
preferably between 15 and 50%, although higher or lower ethylene
contents may be present.
[0087] These polymers may be prepared by polymerizing alpha-olefin
monomer, or mixtures of alpha-olefin monomers, or mixtures
comprising ethylene and at least one C.sub.3 to C.sub.28
alpha-olefin monomer, in the presence of a catalyst system
comprising at least one metallocene (e.g., a
cyclopentadienyl-transition metal compound) and an alumoxane
compound. Using this process, a polymer in which 95% or more of the
polymer chains possess terminal ethenylidene-type unsaturation can
be provided. The percentage of polymer chains exhibiting terminal
ethenylidene unsaturation may he determined by FTIR spectroscopic
analysis, titration, or C.sup.13 NMR. Interpolymers of this latter
type may be characterized by the formula
POLY-C(R.sup.1).dbd.CH.sub.2 wherein R.sup.1 is C.sub.1 to C.sub.26
alkyl, preferably C.sub.1 to C.sub.18 alkyl, more preferably
C.sub.1 to C.sub.8 alkyl, and most preferably C.sub.1 to C.sub.2
alkyl, (e.g., methyl or ethyl) and wherein POLY represents the
polymer chain. The chain length of the R.sup.1 alkyl group will
vary depending on the comonomer(s) selected for use in the
polymerization. A minor amount of the polymer chains can contain
terminal ethenyl, i.e., vinyl, unsaturation, i.e.
POLY-CH.dbd.CH.sub.2, and a portion of the polymers can contain
internal monounsaturation, e.g. POLY-CH.dbd.CH(R.sup.1), wherein
R.sup.1 is as defined above. These terminally unsaturated
interpolymers may be prepared by known metallocene chemistry and
may also be prepared as described in U.S. Pat. Nos. 5,498,809;
5,663,130; 5,705,577; 5,814,715; 6,022,929 and 6,030,930.
[0088] Another useful class of polymers is polymers prepared by
cationic polymerization of isobutene, styrene, and the like. Common
polymers from this class include polyisobutenes obtained by
polymerization of a C.sub.4 refinery stream having a butene content
of about 35 to about 75 mass %, and an isobutene content of about
30 to about 60 mass %, in the presence of a Lewis acid catalyst,
such as aluminum trichloride or boron trifluoride. A preferred
source of monomer for making poly-n-butenes is petroleum
feedstreams such as Raffinate II. These feedstocks are disclosed in
the art such as in U.S. Pat. No. 4,952,739. Polyisobutylene is a
most preferred backbone of the present invention because it is
readily available by cationic polymerization from butene streams
(e.g., using AlCl.sub.3 or BF.sub.3 catalysts). Such
polyisobutylenes generally contain residual unsaturation in amounts
of about one ethylenic double bond per polymer chain, positioned
along the chain. A preferred embodiment utilizes polyisobutylene
prepared from a pure isobutylene stream or a Raffinate I stream to
prepare reactive isobutylene polymers with terminal vinylidene
olefins. Preferably, these polymers, referred to as highly reactive
polyisobutylene (HR-PIB), have a terminal vinylidene content of at
least 65%, e.g., 70%, more preferably at least 80%, most
preferably, at least 85%. The preparation of such polymers is
described, for example, in U.S. Pat. No. 4,152,499. HR-PIB is known
and HR-PIB is commercially available under the tradenames
Glissopal.TM. (from BASF) and Ultravis.TM. (from BP-Amoco).
[0089] Polyisobutylene polymers that may be employed are generally
based on a hydrocarbon chain of from 400 to 3000. Methods for
making polyisobutylene are known. Polyisobutylene can be
functionalized by halogenation (e.g. chlorination), the thermal
"ene" reaction, or by free radical grafting using a catalyst (e.g.
peroxide), as described below.
[0090] To produce (B) the hydrocarbon or polymer backbone may be
functionalized, with carboxylic acid producing moieties (acid or
anhydride moieties) selectively at sites of carbon-to-carbon
unsaturation on the polymer or hydrocarbon chains, or randomly
along chains using any of the three processes mentioned above or
combinations thereof, in any sequence.
[0091] Processes for reacting polymeric hydrocarbons with
unsaturated carboxylic acids, anhydrides or esters and the
preparation of derivatives from such compounds are disclosed in
U.S. Pat. Nos. 3,087,936; 3,172,892; 3,215,707; 3,231,587;
3,272,746; 3,275,554; 3,381,022; 3,442,808; 3,565,804; 3,912,764;
4,110,349; 4,234,435; 5,777,025; 5,891,953; as well as EP 0 382 450
B1; CA-1,335,895 and GB-A-1,440,219. The polymer or hydrocarbon may
be functionalized, with carboxylic acid producing moieties (acid or
anhydride) by reacting the polymer or hydrocarbon under conditions
that result in the addition of functional moieties or agents, i.e.,
acid, anhydride, ester moieties, etc., onto the polymer or
hydrocarbon chains primarily at sites of carbon-to-carbon
unsaturation (also referred to as ethylenic or olefinic
unsaturation) using the halogen assisted functionalization (e.g.
chlorination) process or the thermal "ene" reaction.
[0092] Selective functionalization can be accomplished by
halogenating, e.g., chlorinating or brominating the unsaturated
.alpha.-olefin polymer to about 1 to 8 mass %, preferably 3 to 7
mass % chlorine, or bromine, based on the weight of polymer or
hydrocarbon, by passing the chlorine or bromine through the polymer
at a temperature of 60 to 250.degree. C., preferably 110 to
160.degree. C., e.g., 120 to 140.degree. C., for about 0.5 to 10,
preferably 1 to 7 hours. The halogenated polymer or hydrocarbon
(hereinafter backbone) is then reacted with sufficient
monounsaturated reactant capable of adding the required number of
functional moieties to the backbone, e.g., monounsaturated
carboxylic reactant, at 100 to 250.degree. C., usually about
180.degree. C. to 235.degree. C., for about 0.5 to 10, e.g., 3 to 8
hours, such that the product obtained will contain the desired
number of moles of the monounsaturated carboxylic reactant per mole
of the halogenated backbones. Alternatively, the backbone and the
monounsaturated carboxylic reactant are mixed and heated while
adding chlorine to the hot material.
[0093] While chlorination normally helps increase the reactivity of
starting olefin polymers with monounsaturated functionalizing
reactant, it is not necessary with some of the polymers or
hydrocarbons contemplated for use in the present invention,
particularly those preferred polymers or hydrocarbons which possess
a high terminal bond content and reactivity. Preferably, therefore,
the backbone and the monounsaturated functionality reactant, e.g.,
carboxylic reactant, are contacted at elevated temperature to cause
an initial thermal "ene" reaction to take place. Ene reactions are
known.
[0094] The hydrocarbon or polymer backbone can be functionalized by
random attachment of functional moieties along the polymer chains
by a variety of methods. For example, the polymer, in solution or
in solid form, may be grafted with the monounsaturated carboxylic
reactant, as described above, in the presence of a free-radical
initiator. When performed in solution, the grafting takes place at
an elevated temperature in the range of about 100 to 260.degree.
C., preferably 120 to 240.degree. C. Preferably, free-radical
initiated grafting would be accomplished in a mineral lubricating
oil solution containing, e.g., 1 to 50 mass %, preferably 5 to 30
mass % polymer based on the initial total oil solution.
[0095] The free-radical initiators that may be used are peroxides,
hydroperoxides, and azo compounds, preferably those that have a
boiling point greater than about 100.degree. C. and decompose
thermally within the grafting temperature range to provide
free-radicals. Representative of these free-radical initiators are
azobutyronitrile, 2,5-dimethylhex-3-ene-2,5-bis-tertiary-butyl
peroxide and dicumene peroxide. The initiator, when used, typically
is used in an amount of between 0.005% and 1% by weight based on
the weight of the reaction mixture solution. Typically, the
aforesaid monounsaturated carboxylic reactant material and
free-radical initiator are used in a weight ratio range of from
about 1.0:1 to 30:1, preferably 3:1 to 6:1. The grafting is
preferably carried out in an inert atmosphere, such as under
nitrogen blanketing. The resulting grafted polymer is characterized
by having carboxylic acid (or derivative) moieties randomly
attached along the polymer chains: it being understood, of course,
that some of the polymer chains remain ungrafted. The free radical
grafting described above can be used for the other polymers and
hydrocarbons of the present invention.
[0096] The preferred monounsaturated reactants that are used to
functionalize the backbone comprise mono- and dicarboxylic acid
material, i.e., acid, or acid derivative material, including (i)
monounsaturated C.sub.4 to C.sub.10 dicarboxylic acid wherein (a)
the carboxyl groups are vicinyl, (i.e., located on adjacent carbon
atoms) and (b) at least one, preferably both, of said adjacent
carbon atoms are part of said mono unsaturation; (ii) derivatives
of (i) such as anhydrides or C.sub.1 to C.sub.5 alcohol derived
mono- or diesters of (i); (iii) monounsaturated C.sub.3 to C.sub.10
monocarboxylic acid wherein the carbon-carbon double bond is
conjugated with the carboxy group, i.e., of the structure
--C.dbd.C--CO--; and (iv) derivatives of (iii) such as C.sub.1 to
C.sub.5 alcohol derived mono- or diesters of (iii). Mixtures of
monounsaturated carboxylic materials (i)-(iv) also may be used.
Upon reaction with the backbone, the monounsaturation of the
monounsaturated carboxylic reactant becomes saturated. Thus, for
example, maleic anhydride becomes backbone-substituted succinic
anhydride, and acrylic acid becomes backbone-substituted propionic
acid. Exemplary of such monounsaturated carboxylic reactants are
fumaric acid, itaconic acid, maleic acid, maleic anhydride,
chloromaleic acid, chloromaleic anhydride, acrylic acid,
methacrylic acid, crotonic acid, cinnamic acid, and lower alkyl
(e.g., C.sub.1 to C.sub.4 alkyl) acid esters of the foregoing,
e.g., methyl maleate, ethyl fumarate, and methyl fumarate.
[0097] To provide the required functionality, the monounsaturated
carboxylic reactant, preferably maleic anhydride, typically will be
used in an amount ranging from about equimolar amount to about 100
mass % excess, preferably 5 to 50 mass % excess, based on the moles
of polymer or hydrocarbon. Unreacted excess monounsaturated
carboxylic reactant can be removed from the final dispersant
product by, for example, stripping, usually under vacuum, if
required.
[0098] The treat rate of additives (A) and (B) contained in the
lubricating oil composition may for example be in the range of 1 to
2.5, preferably 2 to 20, more preferably 5 to 18, mass %.
Co-Additives
[0099] The lubricating oil composition of the invention may
comprise further additives, different from and additional to (A)
and (B). Such additional additives may, for example include ashless
dispersants, other metal detergents, anti-wear agents such as zinc
dihydrocarbyl dithiophosphates, anti-oxidants and demulsifiers.
[0100] It may be desirable, although not essential, to prepare one
or more additive packages or concentrates comprising the additives,
whereby additives (A) and (B) 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, additives (A) and (B), 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 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.
[0101] The final formulations as a trunk piston engine oil may
typically contain 30, preferably 10 to 28, more preferably 12 to
24, mass % of the additive package(s), the remainder being base
oil. Preferably, the trunk piston engine oil has a compositional
TBN (using ASTM D2896) of 20 to 60, such as 25 to 55.
EXAMPLES
[0102] The present invention is illustrated by but in no way
limited to the following examples.
Components
[0103] The following components were used:
Component (A):
[0104] (A1) a calcium salicylate detergent having a TBN of 350
(basicity index of two or greater; a degree of carbonation of 80%
or greater) [0105] (A2) a calcium salicylate detergent having a TBN
of 225 (basicity index of two or greater; a degree of carbonation
of less than 80%) [0106] (A3) a calcium salicylate detergent having
a TBN of 65 (basicity index of less than two; a degree of
carbonation of less than 80%)
Component (B):
[0106] [0107] a polyisobutene succinic anhydride ("PIBSA") derived
from a polyisobutene of number average molecular weight 950 (72%
ai) [0108] Base oil II: an API Group II 600R basestock from Chevron
[0109] Base oil III: an API Group III base oil known as XHV 182
[0110] Base oil IV (1): an API Group IV base oil known as DURASYN82
[0111] Base oil IV (2): an API Group IV base oil known as
SPECTRAPA0100 [0112] HFO: a heavy fuel oil, ISO-F-RMK 380
Lubricants
[0113] Selections of the above components were blended to give a
range of trunk piston marine engine lubricants. Some of the
lubricants are examples of the invention; others are reference
examples for comparison purposes. The compositions of the
lubricants tested when each contained HFO are shown in the tables
below under the "Results" heading.
Testing
Panel Coker Test
[0114] The Panel Coker test was used to evaluate the performance of
test lubricants. The test method involved splashing the oil under
test onto a heated metal plate by spinning a metal comb-like device
within a sump containing the oil. At the end of the test period,
deposits formed may be assessed by weight and by visual inspection
of the plate's appearance.
[0115] The testing was performed using a panel coker tester, model
PK-S, supplied by the Yoshida Kagaku Kikai Co., of Osaka, Japan.
Test panels were thoroughly cleaned and weighed before inserting
them into the apparatus. The test oil was mixed with 2.5% HFO and
225 g of the resulting mixture added to the sump of the apparatus.
When the temperature of the oil was at 100.degree. C. and the test
plate at 320.degree. C., a metal comb device was automatically
rotated causing the oil to be splashed onto the test plate.
[0116] The test sequence lasted for 120 cycles, each cycle
consisting of 15 seconds in which the oil was splashed onto the
plate and 45 seconds without splashing.
[0117] At the end of test, the plate was washed with n-heptane,
dried, reweighed and visually examined. The deposit weight was
reported.
Light Scattering
[0118] Test lubricants were also evaluated for asphaltene
dispersancy using light scattering according to the Focused Beam
Reflectance Method ("FBRM"), which predicts asphaltene
agglomeration and hence `black sludge` formation.
[0119] The FBRM test method was disclosed at the 7.sup.th
International Symposium on Marine Engineering, Tokyo, 24-28 Oct.
2005, and was published in `The Benefits of Salicylate Detergents
in TPEO Applications with a Variety of Base Stocks`, in the
Conference Proceedings. Further details were disclosed at the CIMAC
Congress, Vienna, 21-24 May 2007 and published in "Meeting the
Challenge of New Base Fluids for the Lubrication of Medium Speed
Marine Engines--An Additive Approach" in the Congress Proceedings.
In the latter paper it is disclosed that by using the FBRM method
it is possible to obtain quantitative results for asphaltene
dispersancy that predict performance for lubricant systems based on
base stocks containing greater than or less than 90% saturates, and
greater than or less than 0.03% sulphur. The predictions of
relative performance obtained from FBRM were confirmed by engine
tests in marine diesel engines.
[0120] The FBRM probe contains fibre optic cables through which
laser light travels to reach the probe tip. At the tip, an optic
focuses the laser light to a small spot. The optic is rotated so
that the focussed beam scans a circular path between the window of
the probe and the sample. As particles flow past the window they
intersect the scanning path, giving backscattered light from the
individual particles.
[0121] The scanning laser beam travels much faster than the
particles; this means that the particles are effectively
stationary. As the focussed beam reaches one edge of the particle
there is an increase in the amount of backscattered light; the
amount will decrease when the focussed beam reaches the other edge
of the particle.
[0122] The instrument measures the time of the increased
backscatter. The time period of backscatter from one particle is
multiplied by the scan speed and the result is a distance or chord
length. A chord length is a straight line between any two points on
the edge of a particle. This is represented as a chord length
distribution, a graph of numbers of chord lengths (particles)
measured as a function of the chord length dimensions in microns.
As the measurements are performed in real time the statistics of a
distribution can be calculated and tracked. FBRM typically measures
tens of thousands of chords per second, resulting in a robust
number-by-chord length distribution. The method gives an absolute
measure of the particle size distribution of the asphaltene
particles.
[0123] The Focused beam Reflectance Probe (FBRM), model Lasentec
D600L, was supplied by Mettler Toledo, Leicester, UK. The
instrument was used in a configuration to give a particle size
resolution of 1 .mu.m to 1 mm. Data from FBRM can be presented in
several ways. Studies have suggested that the average counts per
second can be used as a quantitative determination of asphaltene
dispersancy. This value is a function of both the average size and
level of agglomerate. In this application, the average count rate
(over the entire size range) was monitored using a measurement time
of 1 second per sample.
[0124] The test lubricant formulations were heated to 60.degree. C.
and stirred at 400 rpm; when the temperature reached 60.degree. C.
the FBRM probe was inserted into the sample and measurements made
for 15 minutes. An aliquot of heavy fuel oil (10% w/w) was
introduced into the lubricant formulation under stirring using a
four blade stirrer (at 400 rpm). A value for the average counts per
second was taken when the count rate had reached an equilibrium
value (typically overnight).
Results
Panel Coker Test
[0125] The results of the Panel Coker tests are summarized in the
table below where figures are mass % unless otherwise stated.
TABLE-US-00002 TABLE 1 Ca salicylate PIBSA Base oil Base oil Base
oil Ex (A1) (B) III IV (1) IV (2) Deposits (g) 1 5.71 6.1 72.21
15.98 0.0484 X 5.71 77.59 16.71 0.0916 2 5.71 6.1 70.96 17.23
0.0738 Y 5.71 75.43 18.56 0.1062
[0126] Each lubricant contained 44.6 mM of soap and had a TBN of
30. Also, each lubricant contained 0.5 mass % HFO.
[0127] The results show that the examples of the invention (Ex 1
and 2) gave rise to much lower deposits, i.e. improved asphaltene
dispersency, than corresponding examples lacking PIBSA (Ex X and Y
respectively), and also than an example in a Group IV base oil
lacking PIBSA (Ex Y).
Light Scattering
[0128] Results of the FBRM tests are summarized in the tables below
(TABLES 2-4).
TABLE-US-00003 TABLE 2 (Base oil II) Ca Salicylate (A) Component
(B) Ex (mass % a.i.) (mass % a.i.) Particle count/s Ref -- 2.6
13,710 A1 (2.6) -- 15,888 A1 (2.6) 2.6 4,355 Ref -- 2.1 15,191 A2
(2.1) -- 8,782 A2 (2.1) 2.1 6,149 A2 (2.1) 2.6 3,438 Ref -- 1.8
15,564 A3 (1.8) -- 10,748 A3 (1.8) 1.8 5,803 A3 (1.8) 2.6 3,629
TABLE-US-00004 TABLE 3 (Base oil III) Ca Salicylate (A) Component
(B) Ex (mass % a.i.) (mass % a.i.) Particle count/s Ref -- 6.1
19,478 A1 (5.2) -- 24,647 A1 (5.2) 6.1 11,889 Ref A2 (4.2) --
22,953 A2 (4.2) 6.1 13,168 Ref A3 (3.6) -- 20,170 A3 (3.6) 6.1
13,724
TABLE-US-00005 TABLE 4 (Base oil IV(I)) Ca Salicylate (A) Component
(B) Ex (mass % a.i.) (mass % a.i.) Particle count/s Ref -- 6.1
15,386 A1 (5.2) -- 20,585 A1 (5.2) 6.1 10,094 Ref A2 (4.2) --
22,366 A2 (4.2) 6.1 9,385 Ref A3 (3.6) -- 16,440 A3 (3.6) 6.1
7,528
[0129] The results show that, in each of the base oils, II, III and
IV(I), (A), represented by each of A1, A2 and A3, in combination
with (B) is better than (A) alone and better than (B) alone.
* * * * *