Note: Descriptions are shown in the official language in which they were submitted.
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LOW ASH OR ASHLESS TWO-CYCLE LUBRICATING OIL
WITH REDUCED SMOKE GENERATION
FIELD OF THE INVENTION
This invention relates to a lubricant composition useful as a two-cycle oil.
More particularly the invention relates to two-cycle oil characterized in that
it is either
ashless or contains a relatively low amount of metal detergent, but provides
an oil
which complies with certain smoke generation test standards and viscosity
requirements for land equipment, gasoline fueled, two-cycle engines, such as
motorcycle engines, moped engines, snowmobile engines, lawn mower engines and
the like.
BACKGROUND OF THE INVENTION
Two-stroke-cycle gasoline engines now range from small, less than 50 cc
engines, to higher performance engines exceeding 500 cc. The development of
such
high performance engines has created the need for new two-cycle oil standards
and
test procedures.
Traditional two-cycle engines are lubricated by mixing the fuel and lubricant
and allowing the mixed composition to pass through the engine. Newer two-cycle
engines may involve the use of direct fuel injection to reduce emissions. In
either
case, the oil passes through the engine and is burned. Various types of two-
cycle oils,
compatible with fuel, have been described in the art. Typically, such oils
contain a
variety of additive components in order for the oil to pass industry standard
tests to
permit use in two-cycle engines.
A worldwide demand for fuel economy and environmental cleanliness has
spurred manufacturers of two-cycle oils to meet increasingly severe standards
for
viscosity and smoke production. In many cases, these new standards are
conventionally satisfied by employing ever-greater quantities of expensive
starting
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materials to manufacture new and improved two-cycle oils. Consequently, a need
exists for alternative starting materials which meet the new standards for
fuel
economy and environmental cleanliness.
SUMMARY OF THE INVENTION
The present invention is based on the discovery that the use of highly
reactive
polyisobutylene polymer, solvent and lubricating oil basestock in certain
proportions
with appropriate amounts of two cycle lubricating oil additive packages can
provide a
low ash or ashless two-cycle engine oil of suitable viscosity properties which
exceeds
the JASO (Japan Automobile Standards Organization) M342 Smoke Index test.
Highly reactive polyisobutylene polymer, also known as HR-PIB, contains more
terminal vinylidene double bonds and is manufactured by a different
manufacturing
process, as compared to conventional polyisobutylene, which is known as PIB.
Two-
cycle oils containing HR-PM are a useful and efficient alternative to
conventional
two-cycle oils.
In one aspect, the invention is a low ash two-cycle lubricating oil
composition
having a kinematic viscosity of at least 6.5 mm2/s (cSt) at 100 C and a JASO
M342
Smoke Index of at least 85. The composition comprises:
(a) 15 to 35 % by weight of an olefinically unsaturated polymer
selected from the group consisting of polybutene,
polyisobutylene or a mixture of polybutene and
polyisobutylene, which has a number average molecular weight
of 400 to 2200 and a terminal vinylidene content of at least 60
mol % based on the total number of double bonds in the
polymer;
(b) 20 to 30 % by weight of a normally liquid hydrocarbon or
mineral oil solvent, which has a viscosity of 1 to 5 cP, at 25 C;
(c) 1 to 5% by weight of an additive package for two cycle oils;
and
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(d) a mineral or synthetic oil, or a mixture thereof, which has a
viscosity of 4 to15 mm2/s (cSt) at 100 C.
In another aspect, the invention is an ashless two-cycle lubricating oil
composition having a kinematic viscosity of at least 6.5 mm2/s (cSt) at 100 C
and a
JASO M342 Smoke Index of at least 85. The composition comprises:
(a) 6 to 12 % by weight of a reactive polybutene polymer being a
polybutene, polyisobutlene or a mixture of polybutenes and
polyisobutylenes having a number average molecular weight of 400
to 2200 and having at least 60 mol % double bonds as terminal
vinylidene;
(b) 18 to 30 % by weight of a normally liquid hydrocarbon or
mineral oil solvent having a viscosity of 1 to 5 cP. at 25 C;
(c) 14 to 25% by weight of a metal-free additive package for two
cycle oils; and -
(d) the balance a mineral or synthetic oil, or a mixture thereof,
having a viscosity of 4 to15 mm2/s (cSt) at 100 C.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
Highly reactive polybutene polymers (hereinafter referred to as "HR-PIB")
useful in this invention include polybutylenes, polyisobutylenes, or mixtures
thereof,
of Mn 400 to 2200, preferably about 800 to 1500, such as about 1000, which
have a
terminal vinylidene content of at least 60 mol %, based on the total moll of
double
bonds. The terminal vinylidene content is preferably at least 70%, more
preferably at
least 80%, most preferably at least 85%. The following issued patents teach
manufacturing processes for highly reactive polyisobutylene: U.S. Pat. Nos.
4,152,499, 5,962,604, 6,562,913, 6,683,138 and 6,710,140. HR-PIB is
commercially
available under the trade names Glissopal[R] (from BASF) and Ultravis[R] (from
BP-
Amoco), among other sources.
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Solvents useful in the present invention are normally liquid natural or
synthetic hydrocarbon or mineral oil solvents having a viscosity of 1 to 5,
preferably
1.2 to 2 cP. at 25 C. The solvent should have a flash point in the range of
about 60-
120 C such that the flash point of the two-cycle oil of this invention is
greater than
70 C. Typical examples include paraffinic, isoparaffinic and naphthenic
aliphatic
hydrocarbon or mineral oil solvents. The solvent may contain functional groups
other
than carbon and hydrogen provided such groups do not adversely affect
performance
of the two-cycle oil. Preferred are mineral oils sold as "Exxsol D80" by
ExxonMobil
Chemical Company and "Shellsol D70" sold by Shell Chemicals.
The invention may additionally comprise as a third component 1-5% for low
ash oils and 14-25% for ashless oils, each by weight, of an additive package
which
contains one or more conventional two-cycle lubricating oil additives, and
these may
be any additive normally included in such lubricating oils for a particular
purpose.
For the ashless package, there will be essentially no metallic additives.
Conventional additives for the additive package component of this invention
include corrosion inhibitors, oxidation inhibitors, friction modifiers,
dispersants,
antifoaming agents, antiwear agents, pour point depressants, metal detergents,
rust
inhibitors, lubricity agents, and the like. All percentages are by weight on
an active
ingredient basis.
A preferred low ash additive package comprises (i) polyisobutenyl (Mn 400-
2500, preferably about Mn 950) succinimide or another oil soluble, acylated,
nitrogen
containing lubricating oil dispersant present in the amount of 0.2-5 wt.%,
preferably
1-3 wt.%. dispersant in the lubricating oil and (ii) a metal phenate,
sulfonate or
salicylate oil soluble detergent additive. This detergent is a neutral metal
detergent or
overbased metal detergent of Total Base Number 200 or less, present in the
amount of
0.1-2 wt.%, preferably 0.2-1 wt.%. metal detergent additive in the lubricating
oil. The
metal is preferably calcium, barium or magnesium. Neutral calcium salicylates
are
preferred and may be present in amounts of about 0.5 to 1.5 wt.% in the
lubricating
oil.
Trade-mark
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A preferred ashless additive package comprises an ashless lubricating oil
dispersant in the oil, in the range of about 5.5 to 17 wt. %, preferably 9 to
15 wt.%,
and one or more of the ashless dispersants as disclosed below may be used.
Dispersants useful in the present invention include nitrogen-containing,
ashless dispersants known to be effective for reducing formation of deposits
upon use
in gasoline and diesel engines, when added to lubricating oils. These ashles
dispersants have an oil soluble polymeric long chain backbone having
functional
groups capable of associating with particles to be dispersed. Typically,
amine, amine-
alcohol or amide polar moieties are attached to the polymer backbone, often
via a
bridging group. The ashless dispersant may be, for example, selected from the
group
consisting of oil soluble salts, esters, amino-esters, amides, imides and
oxazolines of
long chain hydrocarbon-substituted mono- and polycarboxylic acids or
anhydrides
thereof; thiocarboxylate derivatives of long chain hydrocarbons; long chain
aliphatic
hydrocarbons having polyamine moieties attached directly thereto; and Mannich
condensation products formed by condensing a long chain substituted phenol
with
formaldehyde and polyalkylene polyamine.
Polyisobutylene polymers that may be employed for making dispersants are
generally based on a hydrocarbon chain of from about 400 to 3000 daltons.
Methods
for making polyisobutylene are publicly known. Polyisobutylene can be
functionalized by halogenating (e.g. chlorinating), thermally reacting via the
thermal
"ene" reaction, or by free radical grafting using a catalyst (for example,
peroxide), as
described below.
The functionalized, oil-soluble polymeric hydrocarbon backbones may also be
derivatized with hydroxy compounds such as monohydric and polyhydric alcohols,
or
with aromatic compounds such as phenols and naphthols. Preferred polyhydric
alcohols include alkylene glycols in which the alkylene radical contains from
2 to 8
carbon atoms. Other useful polyhydric alcohols include glycerol, mono-oleate
of
glycerol, monostearate of glycerol, monomethyl ether of glycerol,
pentaerythritol,
dipentaerythritol, and mixtures thereof. An ester dispersant may also be
derived from
unsaturated alcohols, such as allyl alcohol, cinnamyl alcohol, propargyl
alcohol, 1-
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cyclohexane-3-ol, and oleyl alcohol. Still other classes of alcohols capable
of
yielding ashless dispersants include ether-alcohols, including oxy-alkylene
and oxy-
arylene. These ether-alcohols may incorporate up to 150 oxy-alkylene radicals,
in
which the alkylene radical contains from 1 to 8 carbon atoms. The ester
dispersants
may be di-esters of succinic acids or acid-esters, such as partially
esterified succinic
acids, as well as partially esterified polyhydric alcohols or phenols, such as
esters
having free alcohols or phenolic hydroxy radicals. An ester dispersant may be
prepared by any one of several known methods as described, for example, in
U.S.
Patent No. 3,381,022.
A preferred category of dispersants comprises the succinimides of the highly
reactive polyisobutylenes of Mn 400-2200, as described above. These
dispersants are
typically prepared by reacting a polyisobutenyl succinic anhydride and an
alkylene
polyamine such as triethlyene tetramine or tetraethylene pentamine.
Another class of high molecular weight ashless dispersants comprises
Mannich base condensation products. Generally, these products are prepared by
condensing about one mole of a long chain alkyl-substituted mono- or
polyhydroxy
benzene with about 1 to 2.5 moles of carbonyl compound(s) (for example,
formaldehyde and paraformaldehyde) and about 0.5 to 2 moles of polyalkylene
polyamine, as disclosed, for example, in U.S. Patent No. 3,442,808. Such
Mannich
base condensation products may include a polymer product of a metallocene
catalyzed polymerization as a substituent on the benzene group, or may be
reacted
with a compound containing such a polymer substituted on a succinic anhydride
in a
manner similar to that described in U.S. Patent No. 3,442,808.
Corrosion inhibitors may be present in the oil in amounts of 0.01-3 wt.%,
preferably 0.01-1.5 wt.%, and are illustrated by phosphosulfurized
hydrocarbons and
the products obtained by reacting a phosphosulfurized hydrocarbon with an
alkaline
earth metal oxide or hydroxide.
Oxidation inhibitors may be present in the oil in amounts of 0.01-5 wt.%,
preferably 0.01-1.5 wt.%. Suitable oxidation inhibitors include alkaline earth
metal
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salts of alkylphenol thioesters having preferably C5-C12 alkyl side chain such
as
calcium nonylphenol sulfide, barium t-octylphenol sulfide, and
dioctylphenylamines.
Also included are oil soluble sulfurized or phosphosulfurized hydrocarbons and
antioxidant copper compounds, such as copper salts of C10 to C18 oil soluble
fatty
acids.
Friction modifiers may be present in the oil in amounts of 0.01-3 wt.%,
preferably 0.01-1.5 wt.%, and include fatty acid esters and amides, glycerol
esters of
dimerized fatty acids and succinate esters or metal salts thereof.
Pour point depressants, also known as lube oil flow improvers, may be
included in the oil in amounts of 0.01-2 wt.%, preferably 0.01-1.5 wt.%.
Suitable
pour point depressants are C8-C18 or C14 dialkyl fumarate vinyl acetate
copolymers,
which are preferred, polymethacrylates and wax naphthalene.
Foam control can also be provided by an anti-foamant of the polysiloxane type
such as silicone oil and polydimethyl siloxane; acrylate polymers are also
suitable.
These are used in the oil in amounts of 0.01-5 wt.%, preferably 0.01-1.5 wt.%.
Anti-wear agents reduce wear of metal parts and representative materials are
zinc dialkyldithiophosphate, zinc diaryl diphosphate, and sulfurized
isobutylene.
These may be used in the oil in amounts of 0.01-5 wt.%.
Lubricity agents useful in this invention include a wide variety of oil
soluble
materials. Generally, they are used in the oil in an amount of 1-20 wt.%,
preferably 1-
7% by weight. Lubricity agents include polyol ethers and polyol esters, such
as
polyol esters of C5-C15 monocarboxylic acids, particularly pentaerythritol
trimethylol
propane and neopentyl glycol synlube esters of these acids, wherein the ester
has a
viscosity of at least 9 mm2/s (cSt) at 100 C, natural oils such as bright
stock, which is
preferred, and is the highly viscous mineral oil fraction derived from the
distillation
residues formed as a result of the preparation of lubricating oil fractions
from
petroleum.
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Lubricating compositions of this invention normally include an oil of
lubricating viscosity, that is, a viscosity of about 4-15, preferably 12-15
mm2/s (cSt) at
100 C, to provide a finished two-cycle oil having a KV in the range of 6.5-14
mm2/s
(cSt) at 100 C.
These oils of lubricating viscosity can be natural or synthetic oils. Mixtures
of
such oils are also often useful. Blends of oils may also be used so long as
the final
viscosity of the blend is 4-15 mmZ/s (cSt) at 100 C.
Natural oils include mineral lubricating oils, which are prefered, such as
liquid petroleum oils and solvent-treated or acid-treated mineral lubricating
oils of the
paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils of
lubricating
viscosity derived from coal or shale are also useful base oils.
Synthetic lubricating oils include hydrocarbon oils such as polymerized and
interpolymerized olefins alkylated diphenyl ethers and alkylated diphenyl
sulfides and
the derivatives, analogs and homologs thereof.
Oils made by polymerizing olefins of less than 5 carbon atoms and mixtures
thereof are typical synthetic polymer oils. Methods of preparing these polymer
oils
are well known to those skilled in the art, as is shown for example by U.S.
Patent Nos.
2,278,445; 2,301,052; 2,318,719; 2,329,714; 2,345,574; and 2,422,443.
Alkylene oxide polymers (such as, for example, homopolymers,
interpolymers, and derivatives thereof in which the terminal hydroxyl groups
have
been modified by esterification, etherification, etc.) constitute a preferred
class of
known synthetic lubricating oils for the purpose of this invention, especially
for use in
combination with alkanol fuels. They are exemplified by the oils prepared
through
polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers
of these
polyoxyalkylene polymers (e.g., methyl polypropylene glycol ether having an
average
molecular weight of 1000, diphenyl ether of polyethylene glycol having a
molecular
weight of 500-1000, diethyl ether of polypropylene glycol having a molecular
weight
of 1000-1500, etc.) or mono- and polycarboxylic esters thereof, for example,
the
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acetic acid esters mixed C3-C8 fatty acid esters, or the C13 Oxo acid diester
of
tetraethylene glycol.
Another suitable class of synthetic lubricating oils comprises the esters of
dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids,
alkenyl
succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric
acid,
adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl
malonic
acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol,
octyl alcohol,
dodecyl alcohol, tridecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol,
diethylene
glycol monoether, propylene glycol, etc.). Specific examples of these esters
include
dioctyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl
sebacate,
diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate,
dieicosyl
sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester
formed by
reacting one mole of sebacic acid with two moles of tetraethylene glycol and
two
moles of 2-ethylhexanoic acid and the like. Preferred esters will have a
viscosity of 5-
12 mm2/s (cSt) at 100 C;
Esters useful as synthetic oils also include those made from C5 to C18
monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol,
trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol,
etc.
Unrefined, refined and rerefined oils, either natural or synthetic (as well as
mixtures of two or more of any of these) of the type disclosed hereinabove can
be
used in the lubricant compositions 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, a
petroleum oil obtained directly from primary distillation or an ester oil
obtained
directly from an esterification process and used without further treatment
would be an
unrefined oil. Refined oils are similar to the unrefined oils except they have
been
further treated in one or more purification steps to improve one or more
properties.
Many such purification techniques are known to those of skill in the art such
as
solvent extraction, secondary distillation, acid or base extraction,
filtration,
percolation, etc. Rerefined oils are obtained by processes similar to those
used to
i
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obtain refined oils which have been already used in service. Such rerefined
oils are
also known as reclaimed or reprocessed oils and often are additionally
processed by
techniques directed to removal of spent additives and oil breakdown products.
The lubricating oil compositions of the present invention will mix freely with
the fuels used in such two-cycle engines. Admixtures of such lubricating oils
with
fuels comprise a further embodiment of this invention. The fuels useful in two-
cycle
engines are well known to those skilled in the art and usually contain a major
portion
of a normally liquid fuel such as a hydrocarbonaceous petroleum distillate
fuel, e.g.,
motor gasoline as defined by ASTM specification D-439-73. Such fuels can also
contain non-hydrocarbonaceous materials such as alcohols, ethers, organo nitro
compounds and the like. For example, methanol, ethanol, diethyl ether,
methylethyl
ether, nitro methane and such fuels are within the scope of this invention as
are liquid
fuels derived from vegetable and mineral sources such as corn, alpha shale and
coal.
Examples of such fuel mixtures are combinations of gasoline and ethanol,
diesel fuel
and ether, gasoline and nitro methane, etc. Gasoline is preferred. Gasoline
means a
mixture of hydrocarbons having an ASTM boiling point of 60 C at the 10%
distillation point to about 205 C at the 90% distillation point. Lead-free
gasoline is
particularly preferred.
The lubricants of this invention are used in admixture with fuels in amounts
of
about 20 to 250 parts by weight of fuel per 1 part by weight of lubricating
oil, more
typically about 30-100 parts by weight of fuel per 1 part by weight of oil.
The invention is further illustrated by the following examples which are
presented to better communicate the invention and not to limit the scope of
the
invention in any way. Percentages are by weight.
Example
An oil of the invention containing reactive HR-PIB, designated "Invention" in
the Table below, and a conventional oil containing conventional
polyisobutylene,
designated "Conventional" in the Table below, were evaluated in accordance
with
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JASO M345 test procedures JASO M340, M341, M342 and M343. These are engine
tests established by the Society of Automotive Engineers of Japan (JSAE) for
two-
cycle gasoline engine oils. As of July 1, 1994, oils used in two-cycle engines
are
being labeled in accordance with the JASO-M345 standards as announced by the
Japan Automobile Standards Organization (JASO). JASO published the JASO M345
standards in April, 1994 and updated them in 2004. "EGD Detergency" is a
reference
to a further modification of the normal JASO M341 detergency test (1 hour)
procedure in which the test is run for 3 hours. This is a more stringent
standard
adopted by ISO (the International Organization for Standardization). "FC" was
the
highest performance standard for the JASO M345 standards prior to the update.
The
update in 2004 created an "FD" classification, analogous to ISO-EGD. Results
of this
testing are presented in the Table below.
TABLE
Mass % Invention Conventional
Low ash additive package 2.25 2.25
PIB (Polyisobutylene, Mn 950) 0 25.00
HR-PIE (Glissopal 1000, Mn 1000) 25.00 0
Aliphatic solvent (Shellsol D70) 25.00 25.00
Mineral oil (Shell HVI 160B) 47.50 47.50
Results
Kinematic viscosity @ 100 C, cSt (JASO > 6.5) 7.25 7.30
M342 Smoke Index (JASO FD/FC/ISO-EGD > 85) 89 88
Inspection of the data in Table reveals that the viscosity and smoke index
performance of a low ash two-cycle oil containing HR-PIB are practically
identical to
those of a conventional low ash two-stroke oil containing a corresponding
amount of
PIB. Accordingly, the data demonstrates that HR-PIB is a useful alternative to
PIB
for formulating and manufacturing low ash two-stroke oils.
