Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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LUBRICANT COMPOSITION FOR AIR-COOLED TWO-STROKE CYCLE
ENGINES
The present invention relates to a detergency additive useful in a lubricating
oil composition suitable for use in air-cooled two-stroke cycle engines and to
lubricating oil compositions containing the detergency additive of the present
invention. In another aspect, the present invention relates to a method of
improving the detergency in an air-cooled two-stroke cycle engine by
lubricating the engine with the lubricating oil composition of the present
invention. In still a further aspect, the present invention relates to
concentrates of the detergency additive. The detergency additive of the
present invention has excellent detergency properties.
BACKGROUND OF THE INVENTION
Over the past several decades the use of spark ignited two-stroke internal
combustion engines has steadily increased. They are presently found in
power lawn mowers and other power operated garden equipment, power
chain saws, pumps, electrical generators, marine outboard engines,
snowmobiles, motorcycles and the like.
The unique problems and techniques associated with the lubrication of two-
stroke cycle engines has led to the recognition by those skilled in the art of
two-stroke cycle engine lubricants as a distinct lubricant type. See, for
example, U.S. Patents 3,085,975; 3,004,837; and 3,753,905.
U.S. 4,025,316 to Stover, issued May 24, 1977, discloses polymeric alkyl-
hydroxy benzyl N-substituted amines having a high degree of ring formation
are derived from the condensation reaction of C8 -C40 aliphatic alkyl
substituted hydroxy aromatic, an aldehyde and an amine, wherein the molar
ratio of said aromatic to said amine is about 2 to 1, with said aldehyde being
present in a molar amount in excess of said aromatic. These novel amines
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are useful as a detergent and/or antioxidant additive for liquid hydrocarbons,
e.g., in lubricating oils for gasoline engines that have a two stroke cycle.
U.S. 4,088,586 to Wilgus et al., issued May 9, 1978, discloses a new Mannich
base, prepared by condensing tetrapropenylphenol, formaldehyde and
diethylenetriamine wherein the molar ratio of reactants is 1 mol
tetrapropenylphenol to 0.5 to 0.85 mols formaldehyde to at least 0.3 mols of
diethylenetriamine, and the calcium salt thereof are useful as dispersant
additives for lubricating oils, particularly for use in marine cylinder
lubricating
oils.
U.S. 4,200,545 to Clason et al., issued April 29, 1980, discloses combinations
of amino phenols, wherein said phenols contain a substantially saturated
hydrocarbon substituent of at least 10 aliphatic carbon atoms, and one or
more detergent/dispersants selected from the group consisting of (I) neutral
or basic metal salts of an organic sulfur acid, phenol or carboxylic acid;
(II)
hydrocarbyl-substituted amines wherein the hydrocarbyl substituent is
substantially aliphatic and contains at least 12 carbon atoms; (III) acylated
nitrogen-containing compounds having a substituent of at least 10 aliphatic
carbon atoms; and (IV) nitrogen-containing condensates of a phenol,
aldehyde and amino compound. Fuels and lubricants containing such
combinations as additives are particularly useful in two-cycle (two-stroke)
engines.
U.S. Patent 4,663,063 to Davis, issued May 5, 1987, discloses a functional
fluid for a two-cycle engine having base oil and a combination of an alkylated
phenol and a polyalkylene polyamine. That patent discloses that metal
thiocarbamates are useful as extreme pressure agents.
U.S. 4,740,321 to Davis et al., issued April 26, 1988, discloses lubricating
oils
which are useful in two-cycle engines. These oils contain a minor amount of
at least one phenolic compound of the general formula: (R).-AR-(OH)b, or
salts thereof, wherein R is a substantially saturated, hydrocarbon-based
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group of an average of at least 10 aliphatic carbon atoms; a and b are each
independently an integer of one up to three times the number of aromatic
nuclei present in Ar with the proviso that the sum of a and b does not exceed
the unsatisfied valences of Ar; and Ar is a linked polynuclear moiety wherein
the bridging linkages are sulfur-containing moieties, having 0 to 3 optional
substituents consisting of lower alkyl, lower alkoxyl, methylol or lower
hydrocarbon-based substituted methylol, halo and combinations of two or
more of said optional substituents.
WO 91/13950 to Saitor et al., published September 19, 1991, discloses
lubricating oils which are utilized in two-stroke engines sometimes produce
clogging (gelation) in fuel filters. The gelling is particularly pronounced
when
an alkali metal or alkaline earth metal containing composition is present in
the
lubricating oil or the fuel. The present invention deals with this particular
problem by introducing a hydrocarbon-soluble or dispersible polycarboxylic
acid to the fuel and oil mixture.
WO 92/21736 to Chamberlin, published December 10, 1992, discloses a
lubricant composition for two-cycle engines comprising: a major amount of at
least one oil of lubricating viscosity which is free of oils having a
viscosity
greater than or equal to 100 cSt at 40 C, an amount sufficient to reduce or
prevent piston scuffing of a mixture of (A) at least one phenol selected from
(A-I) an aminophenol and (A-2) a reaction noduct of a nitrophenol and an
amino compound, and (B) at least one ashless dispersant. The compositions
may also include up to about 10 % by weight of (C) at least one polyalkene
having a number average molecular weight from about 500 to about 2,500.
Since lubricant compositions for two-cycle engines are often mixed with fuels
before or during combustion. This reference also includes fuel-lubricant
mixtures. The above compositions act to control piston scuffing while also
contributing to piston lubrication, deposit control, ring stick protection,
reduced
exhaust port blockage and reduced visible smoke emission.
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U.S. 5,281,346 to Adams et al., issued January 25, 1994, discloses lubricants
for two-cycle engines comprising a major amount of at least one oil of
lubricating viscosity and a minor amount of at least one metal carboxylate.
U.S. Patent 5,516,444 to Gaines et al., issued May 14, 1996, discloses a
functional fluid for a two-cycle engine having base oil and an acylated
nitrogen-containing compound having an oil soluble olefinic substituent and at
least one ashless detergent/dispersant. That patent discloses that
molybdenum- and molybdenum/sulfur-containing compounds are some of the
anti-wear and lubricity agents useful in that invention.
U.S. Patent 5,688,751 to Cleveland et al., issued November 18, 1997,
discloses alkali metal salicylate salts as lubricant additives for two-cycle
engines.
SUMMARY OF THE INVENTION
The present invention provides a detergency additive especially useful in a
lubricating oil composition useful in air-cooled two-stroke cycle engines.
In its broadest embodiment the present invention relates to detergency
additive comprising a Mannich detergent and an ashless dispersant wherein
the ratio of the Mannich detergent to ashless dispersant is from 1:3 to 1:5.
In
a further embodiment, the detergency additive may also contain at least one
of the following compounds: a molybdenum compound, an overbased alkyl
oxy benzene sulfonate, and an alkylsalicylate.
In another embodiment, the present invention relates to a lubricating oil
composition comprising a major amount of at least one base oil of lubricating
viscosity and an effective minor amount of a detergency additive of the
present invention. Optionally, the lubricating oil composition may further
comprise at least a solvent and/or a polyisobutylene.
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The lubricating oil composition can be produced by blending together a major
amount of the base oil of lubricating viscosity, an effective minor amount of
detergency additive, and, optionally, minor amounts other additives, such as,
solvent and polyisobutene. The lubricant composition can be used to improve
the detergency of an air-cooled two-stroke cycle engine by supplying the
lubricating oil composition to the engine crankcase and operating the engine
or by supplying the lubricating oil composition to the fuel and operating the
engine.
The present invention also provides an additive concentrate suitable for
mixing with base oil to provide lubricating oils which may be used to
lubricate
air-cooled two-stroke cycle engines. This additive concentrate has from 5.0 to
wt % of an organic diluent and from 85 to 95 wt % of the detergency
15 additive of the present invention.
Among other factors the present invention provides a low-ash detergency
additive that demonstrates superior detergency including dispersancy and
lubricity in air-cooled two-stroke cycle engine lubricating or compositions.
The
lubricating oil composition containing the detergency additive of the present
invention keeps air-cooled two-stroke cycle engines clean by preventing ring
sticking, piston deposits, plug fouling and exhaust deposits. Other benefits
include wear and corrosion prevention.
According to another aspect of the present invention, there is provided a
detergency additive for lubricating oil compositions used in air-cooled two-
stroke cycle engines comprising:
a) an alkaline earth metal salt of a Mannich base;
b) an ashless dispersant selected from a polyalkylene succinimide;
wherein the weight ratio of the Mannich base salt to ashless
dispersant is from 1:3 to 1:5; and
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c) at least one of the following compounds:
1) a molybdenum compound;
2) an overbased alkyl oxy benzene sulfonate; and
3) an alkylsalicylate.
DETAILED DESCRIPTION OF THE INVENTION
In its broadest aspect, the present invention involves a detergency additive
having excellent detergency properties when used in a lubricating oil
composition for air-cooled two-stroke cycle engines. The detergency additive
comprises a Mannich detergent and an ashless dispersant wherein the ratio
of the Mannich detergent to ashless dispersant is 1:3 to 1:5. The detergency
additive may further contain at least one of the following compounds: a
molybdenum compound, an overbased alkyl oxy benzene sulfonate, and an
alkylsalicylate.
Prior to discussing the invention in further detail, the following terms will
be
defined:
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DEFINITIONS
As used herein the following terms have the following meanings unless
expressly stated to the contrary:
The term "alkylphenol" means a phenol group having one or more alkyl
substituents; at least one of which has a sufficient number of carbon atoms to
impart oil solubility to the phenol.
The term "alkaline earth metal" means calcium, barium, magnesium, and
strontium.
The term "alkaline earth alkylsalicylate" means an alkaline earth salt of an
alkyl salicylic acid.
The term "internal olefins" means an olefin wherein the double bond is at the
4- position and higher positions of the alkene, instead of at the 1-, 2-, or 3-
position.
The term "succinimide" is understood in the art to include many of the amide,
imide, etc. species which are also formed by the reaction of a succinic
anhydride with an amine. The predominant product, however, is succinimide
and this term has been generally accepted as meaning the product of a
reaction of an alkenyl- or alkyl-substituted succinic acid or anhydride with a
polyamine. Alkenyl or alkyl succinimides are disclosed in numerous
references and are well known in the art. Certain fundamental types of
succinimides and related materials encompassed by the term of art
"succinimide" are taught in U.S. Patent Nos. 2,992,708; 3,018,291; 3,024,237;
3,100,673; 3,219,666; 3,172,892; and 3,272,746.
The term "polysuccinimide" means a compound that is formed by the reaction
of an unsaturated acidic reagent copolymer and an alkene or alkyl succinic
acid derivative with an amine.
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The term "polyamine" means a polyamine containing 2 to amine nitrogen
atoms and 2 to 40 carbon atoms and includes both acyclic and cyclic
polyamines and may be substituted with a variety of substituents so long as
the substitution does not significantly adversely affect the deposit control
and
fuel compatibility properties of the present compositions.
The term "polyalkylene polyamine" by definition contains at least two amine
groups.
The term "Total Base Number" or "TBN" refers to the amount of base
equivalent to milligrams of KOH in one gram of sample. Thus, higher TBN
numbers reflect more alkaline products, and therefore a greater alkalinity
reserve. The TBN of a sample can be determined by ASTM Test No. D664 or
any other equivalent procedure.
Unless otherwise specified, all percentages are in weight percent and all
molecular weights are number average molecular weights.
DETERGENCY ADDITIVE
The detergency additive of the present invention comprises a Mannich
detergent and an ashless dispersant wherein tile ratio of the Mannich
detergent to ashless dispersant is from 1:3 to 1:5. The detergency additive
may further contain at least one of the following compounds: molybdenum, an
overbased alkyl oxy benzene sulfonate, and an alkylsalicylate.
Mannich Detergent
The Mannich base of the present invention may be prepared from a phenol or
C9 to C200 alkylphenol, an aldehyde, such as formaldehyde or formaldehyde
precursor such as paraformaldehyde, and an amine compound. The amine
may be a mono or polyamine and typical compositions are prepared from an
alkylamine, such as methylamine or an ethylene amine, such as, diethylene
triamine, or tetraethylene pentamine, and the like. The phenolic material may
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be sulfurized and preferably is dodecylphenol or a C8 to Cioo alkylphenol.
Typical Mannich bases which can be used in this invention are disclosed in
U.S. Patent Nos. 3,368,972; 3,539,663; 3,649,229; 4,088,586; 4,157,308;
4,157,309; 4,178,759; and 4,219,430.
For example, U.S. Patent 4,088,586 discloses preparing Mannich bases by
condensing tetrapropenylphenol, formaldehyde and diethylene triamine
wherein the molar ratio of reactants is 1 mol tetrapropenylphenol to 0.5 to
0.85 mols formaldehyde to at least 0.3 mots of diethylene triamine followed by
alkaline earth metal salts of the Mannich bases of this invention are
particularly useful as lubricating oil additives. Preferred alkaline earth
metal
salts are calcium and magnesium.
The alkaline earth metal salts of the Mannich bases are prepared using
conventional methods, for example, by treating the Mannich base with an
alkaline earth metal hydroxide, such as calcium hydroxide or magnesium
methoxide in the presence of a promotor, such as water, ethylene glycol, 1,3-
propane diol, 1,4-butane diol, diethylene glycol, butyl cellosolve, propylene
glycol, 1,3-butylene glycol, methylcarbitol, diethanol amine, N-
methyldiethanol
amine, dimethyl formamide, N-methyl acetamide, or dimethyl acetamide.
Preferred promotors are water, ethylene glycol and dimethyl acetamide. Most
preferred is ethylene glycol. The reaction is carried out at 100 -175 C.
After
the reaction is completed, the product is stripped at a higher temperature,
such as 175 -202 C and at reduced pressure, for example 20 mm Hg, to
remove any unreacted low-molecular-weight polyamines, such as ethylene
diamine and diethylene triamine, and other volatile components.
The Mannich bases and the alkaline earth metal salts thereof of this invention
provide a high alkalinity value. The alkaline earth metal salts provide a
particularly high alkalinity value at a lower ash content than is present in
conventional dispersants and acid neutralizers used in lubricating oil
additives.
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The detergency additive may comprise from 5.0 to 30 wt % of the Mannich
detergent, preferably 15 to 23 wt %, and most preferably 21 to 23 wt %.
Ashless Dispersant
The ashless dispersant in the present invention is a polyalkylene succinimide.
Polyalkylene succinimides are disclosed in numerous references and are well
known in the art. Certain fundamental types of succinimides and the related
materials encompassed by the term of art "succinimide" are described in U.S.
Pat. Nos. 3,219,666; 3,172,892; and 3,272,746. The term "succinimide" is
understood in the art to include many of the amide, imide, and amidine
species which may also be formed. The predominant product however is a
succinimide and this term has been generally accepted as meaning the
product of a reaction of an alkenyl- or alkyl-substituted succinic acid or
anhydride with a nitrogen-containing compound such as a polyalkylene
polyamine. Typical polyalkylene polyamines are, for example, ethylene
diamine, diethylene triamine, triethylene tetramine, and tetraethylene
pentamine.
The polyalkylene succinimides of the present invention can be prepared by
conventional processes, such as disclosed in U.S. Patent No. 2,992,708;
3,018,250; 3,018,291; 3,024,237; 3,100,673; 3,172,892; 3,219,666;
3,272,746; 3,361,673; 3,381,022; 3,912,764; 4,234,435; 4,612,132;
4,747,965; 5,112,507; 5,241,003; 5,266,186; 5,286,799; 5,319,030;
5,334,321; 5,356,552; and 5,716,912.
The polyalkylene succinimide additive is an ashless dispersant and can be
prepared by reaction of a high molecular weight alkenyl- or alkyl-substituted
succinic anhydride and a polyalkylene polyamine having an average of 4 to 10
nitrogen atoms (preferably 5 to 7 nitrogen atoms) per mole. The polyalkylene
of the polyalkylene succinimide additive is derived from polyalkylenes having
a molecular weight of at least 1,000. Preferably, the
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polyalkylene succinimide is a polybutene succinimide derived from
polybutenes having a molecular weight of from 1,000 to 2,700, more
preferably 1,900 to 2,700, and most preferably 2,000 to 2,400. A particularly
preferred polyalkylene succinimide additive is derived from a polyalkylene
having a molecular weight of 1,300.
The polyalkylene succinimide additive is prepared by reacting, under reactive
conditions, a mixture of a polybutene succinic acid derivative, an unsaturated
acidic reagent copolymer of an unsaturated acidic reagent and an olefin, and
a polyamine, such as taught in U.S. Patent No. 5,716,912.
The detergency additive may comprise from 50 to 90 wt % of the ashless
dispersant, preferably 73 to 81 wt %, and most preferably 75 to 79 wt %.
A wide variety of other ashless detergent/dispersants can also be used in the
present invention. They are preferably oil-soluble. Typical of such
compositions are carboxylic acid amides, hydrocarbyl monoamines,
hydrocarbyl polyamines, ashless Mannich bases, succinic esters,
phosphoramides, phosphonamides, dispersant viscosity index improvers, and
mixtures thereof. These basic nitrogen-containing compounds are described
below. Any of the nitrogen-containing compositions may be post-treated using
procedures well known in the art so long as the compositions continue to
contain basic nitrogen. Post-treatment may be accomplished by contacting
the basic nitrogen-containing compound with the post-treating compound(s)
concurrently or in any sequence. Suitable post-treating compounds include
urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids,
hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron
compounds, organic phosphorus compounds, inorganic phosphorus
compounds (such as H3PO3, H3PO4, etc.) or the like, and mixtures thereof.
These post-treatments are particularly applicable to succinimides and
Mannich base compositions.
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Molybdenum Compound
Suitable molybdenum compounds that can be used in the invention include,
for example, molybdenum dithiophosphate (MoDTP) and molybdenum
dithiocarbamate (MoDTC). This MoDTP includes molybdenum dialkyl (or
diaryl) dithiophosphate such as molybdenum diisopropyldithiophosphate,
molybdenum di-(2-ethylhexyl) dithiophosphate and molybdenum di-
(nonylphenyl) dithiophosphate. MoDTC includes molybdenum
dialkyldithiocarbamate such as molybdenum dibutyldithiocarbamate,
molybdenum di-(2-ethylhexyl) dithiocarbamate and molybdenum
dilauryldithiocarbamate. Other molybdenum compounds include molybdenum
oxydisulfides and Molyvan 855 (a non-sulfur, non-phosphorus molybdenum
compound sold by the R.T. Vanderbilt Company). Particularly preferred
molybdenum compounds are molybdenum oxydisulfides.
The amount of sulfur-containing molybdenum compounds (such as
molybdenum dithiophosphates, molybdenum dithiocarbamates, molybdenum
oxydisulfides) should be kept low so that the sulfur in the lubricating oil
composition will be less than 0.2%.
The detergency additive may comprise from 0.5 to 10 wt % of the
molybdenum compound, preferably 2.0 to 6.0 wt %, and most preferably 3.0
to5.0wt%.
The Overbased Alkyl Oxy Benzene Sulfonate
The lubricating oil has a minor amount of an overbased, alkyl oxy benzene
sulfonate having a TBN of at least 200, preferably at least 250, wherein at
least 40 wt % of the alkyl group of the sulfonate is attached at the 4-
position
and higher positions of the alkyl group. The oxy group can be either hydroxy,
methoxy, ethoxy, propoxy, butoxy, pentoxy, or hexoxy. Preferably, it is
hydroxy.
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Preferably, the alkyl group of the overbased, alkyl oxy benzene sulfonate has
from eighteen to thirty carbon atoms per alkyl group. More preferably, the
alkyl group has from twenty to twenty-four carbon atoms per alkyl group.
The additive of the present invention can be produced by alkylating an oxy
benzene with an olefin containing between 40 wt % and 80 wt % internal
olefins to produce an alkyl oxy benzene, sulfonating the alkyl oxy benzene to
produce an alkyl oxy benzene sulfonic acid; and overbasing the alkyl oxy
benzene sulfonic acid to produce the overbased, alkyl oxy benzene sulfonate.
An olefin containing between 40 wt % and 80 wt % internal olefins can be
formed by isomerizing an alpha olefin using an iron pentacarbonyl catalyst.
The processes of alkylating an alkyl oxy benzene with an olefin to produce an
alkyl oxy benzene, and sulfonating the alkyl oxy benzene to produce an alkyl
oxy benzene sulfonic acid are both discussed in detail in U.S. Patent Nos.
5,330,663 and 5,330,664. Our alkylation and sulfonation processes differ only
in the olefins used and reaction time. In our batch alkylation reaction, we
need only about six to eight hours. The preferred sulfonation process is a
falling film process using a charge mole ratio of sulfur trioxide to
alkylphenol of
1.1:1 and a reaction temperature in the range of from 70 to 100 C, followed
by immediate neutralization.
A neutralized slurry of alkyl oxy benzene sulfonic acid is added to a slurry
of
xylenes, methanol, and calcium hydroxide. The resulting slurry is then
carbonated during which a second slurry of alkyl oxy benzene sulfonic acid
and a second slurry of xylenes, methanol, and calcium hydroxide are added.
After the carbonation, the material is stripped to remove methanol and water.
Lube oil is then added and the solids removed. The remainder of the solvents
are then stripped off and additional lube oil added to adjust the product to
the
final base number.
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The detergency additive may comprise from 1.0 to 10 wt % of the overbased
alkyl oxy benzene sulfonate, preferably 2.0 to 5.0 wt %, and most preferably
3.0 to 4.0 wt %.
Alkylsalicylate
The detergency additive of the present invention may further contain an alkyl
salicylate. Alkylsalicylates are a class of lubricating oil detergents known
to
impart improved performance (detergency, water tolerance, thermal stability,
antioxidancy) to lubricating oil compositions used for lubrication of internal
combustion engines. This class of detergents are well known in the art and
their description may be found for example in U.S. Patent 2,197,832;
5,808,145; 5,434,293; and 5,415,792.
Sulfurized and unsulfurized alkaline earth alkylsalicylate are well known.
Such alkylsalicylates are usually double aromatic-ring alkylsalicylates, but
single aromatic-ring alkylsalicylates are also known. Preferably, the
unsulfurized alkaline earth alkylsalicylate is calcium alkylsalicylate.
a) Preferred Process for Producing Unsulfurized Alkaline Earth
Alkylsalicylates
One preferred process for producing unsulfurized alkaline earth
alkylsalicylates can be characterized by its unique composition, with much
more alkylphenol and alkaline earth single aromatic-ring alkylsalicylate than
produced by other routes. That reaction product has the following
composition:
(a) from 40 to 60 wt % alkylphenol,
(b) from 10 to 40 wt % alkaline earth alkylphenate, and
(c) from 20 to 40 wt % alkaline earth single aromatic-ring
alkylsalicylate.
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Unlike other processes for producing alkaline earth alkylsalicylates, this
reaction product can be characterized by having only minor amounts of an
alkaline earth double aromatic-ring alkylsalicylates. The mole ratio of single
aromatic-ring alkylsalicylate to double aromatic-ring alkylsalicylate is at
least
8:1.
b) Neutralization Step
In the first step, alkylphenols are neutralized using an alkaline earth base
in
the presence of at least one C, to C4 carboxylic acid. This reaction is
carried
out in the absence of alkali base, and in the absence of dialcohol or
monoalcohol.
The alkylphenols contain up to 85 wt % of linear alkylphenol (preferably at
least 35 wt % linear alkylphenol) in mixture with at least 15 wt % of branched
alkylphenol. Preferably, the linear alkyl radical contains 12 to 40 carbon
atoms, more preferably 18 to 30 carbon atoms. The branched alkyl radical
contains at least nine carbon atoms, preferably 9 to 24 carbon atoms, more
preferably 10 to 15 carbon atoms.
The use of an alkylphenol containing at least 35 wt % of long linear
alkylphenol (from 18 to 30 carbon atoms) is particularly attractive because a
long linear alkyl chain promotes the compatibility and solubility of the
additives
in lubricating oils. However, the presence of relatively heavy linear alkyl
radicals in the alkylphenols makes the latter less reactive than branched
alkylphenols, hence the need to use harsher reaction conditions to bring
about their neutralization by an alkaline earth base.
Branched alkylphenols can be obtained by reaction of phenol with a branched
olefin, generally originating from propylene. They consist of a mixture of
monosubstituted isomers, the great majority of the substituents being in the
para position, very few being in the ortho position, and hardly any in the
meta
position. That makes them relatively reactive towards an alkaline earth base,
since the phenol function is practically devoid of steric hindrance.
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On the other hand, linear alkylphenols can be obtained by reaction of phenol
with a linear olefin, generally originating from ethylene. They consist of a
mixture of monosubstituted isomers in which the proportion of linear alkyl
substituents in the ortho, para, and meta positions is much more uniformly
distributed. This makes them much less reactive towards an alkaline earth
base since the phenol function is much less accessible due to considerable
steric hindrance, due to the presence of closer and generally heavier alkyl
substituents.
The alkaline earth bases that can be used for carrying out this step include
the oxides or hydroxides of calcium, magnesium, barium, or strontium, and
particularly of calcium oxide, calcium hydroxide, magnesium oxide, and
mixtures thereof. In one embodiment, slaked lime (calcium hydroxide) is
preferred.
The C1 to C4 carboxylic acids used in this step include formic, acetic,
propionic and butyric acid, and may be used alone or in mixture. Preferably, a
mixture of acids is used, most preferably a formic acid/acetic acid mixture.
The molar ratio of formic acid/acetic acid should be from 0.2:1 to 100:1,
preferably between 0.5:1 and 4:1, and most preferably 1:1. The carboxylic
acids act as transfer agents, assisting the transfer of the alkaline earth
bases
from a mineral reagent to an organic reagent.
The neutralization operation is carried out at a temperature of at least 200
C,
preferably at least 215 C, and, more preferably, at least 240 C. The pressure
is reduced gradually below atmospheric in order to distill off the water of
reaction. Accordingly the neutralization should be conducted in the absence
of any solvent that may form an azeotrope with water. Preferably, the
pressure is reduced to no more than 7,000 Pa (70 mbars).
The quantities of reagents used should correspond to the following molar
ratios:
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(1) alkaline earth base/alkylphenol of 0.2:1 to 0.7:1, preferably 0.3:1 to
0.5:1; and
(2) carboxylic acid/alkylphenol of 0.01:1 to 0.5:1, preferably from 0.03:1
to 0.15:1.
Preferably, at the end of this neutralization step the alkylphenate obtained
is
kept for a period not exceeding fifteen hours at a temperature of at least
215 C and at an absolute pressure of between 5,000 and 105 Pa (between
0.05 and 1.0 bar). More preferably, at the end of this neutralization step the
alkylphenate obtained is kept for between two and six hours at an absolute
pressure of between 10,000 and 20,000 Pa (between 0.1 and 0.2 bar).
By providing that operations are carried out at a sufficiently high
temperature
and that the pressure in the reactor is reduced gradually below atmospheric,
the neutralization reaction is carried out without the need to add a solvent
that
forms an azeotrope with the water formed during this reaction.
c) Carboxylation Step
The carboxylation step is conducted by simply bubbling carbon dioxide into
the reaction medium originating from the preceding neutralization step and is
continued until at least 20 mole% of the alkylphenate to alkylsalicylate
(measured as salicylic acid by potentiometric determination). It must take
place under pressure in order to avoid any decarboxylation of the
alkylsalicylate that forms.
Preferably, at least 22 mole% of the starting alkylphenols is converted to
alkylsalicylate using carbon dioxide at a temperature of between 180 and
240 C, under a pressure within the range of from above atmospheric
pressure to 15 x 105 Pa (15 bars) for a period of one to eight hours.
According to one variant, at least 25 mole% of the starting alkylphenols is
converted to alkylsalicylate using carbon dioxide at a temperature equal to or
greater than 200 C under a pressure of 4 x 105 Pa (4 bars).
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CA 02341924 2001-03-21
d) Filtration Step
The purpose of the filtration step is to remove sediments, and particularly
crystalline calcium carbonate, which might have been formed during the
preceding steps, and which may cause plugging of filters installed in
lubricating oil circuits.
The detergency additive may comprise from 1.0 to 15 wt % of the
alkylsalicylate, preferably 4.0 to 10 wt %, and most preferably 6.0 to 8.0 wt
%.
Solvent
The lubricating oil compositions of the present invention may optionally
contain a minor amount of a suitable solvent. The solvent is used just to
adjust the viscosity of the finished oil. Suitable solvents include aromatic
and
dearomatized aliphatic distillate in the 190 -290 C range.
Polyisobutvlene
The lubricating oil compositions of the present invention may optionally
contain a polyisobutylene having a molecular weight from 350 to 2,300,
preferably about 950. This polyisobutylene may be present in an amount up
to 35 wt %, preferably up to 30 wt %, more preferably 25 wt % base of the
total weight of the lubricating oil composition. The polyisobutylene acts to
improve lubricity and anti-scuff activity of the lubricant.
Other Additives
The following additive components are examples of some of the components
that can be favorably employed in the present invention. These examples of
additives are provided to illustrate the present invention, but they are not
intended to limit it:
1. Metal Detergents
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Sulfurized or unsulfurized alkyl or alkenyl phenates, alkyl or alkenyl
aromatic sulfonates, sulfurized or unsulfurized metal salts of multi-
hydroxy alkyl or alkenyl aromatic compounds, alkyl or alkenyl hydroxy
aromatic sulfonates, sulfurized or unsulfurized alkyl or alkenyl
naphthenates, metal salts of alkanoic acids, metal salts of an alkyl or
alkenyl multiacid, and chemical and physical mixtures thereof.
2. Anti-Oxidants
Anti-oxidants reduce the tendency of mineral oils to deteriorate in
service which deterioration is evidenced by the products of oxidation
such as sludge and varnish-like deposits on the metal surfaces and by
an increase in viscosity. Examples of anti-oxidants useful in the
present invention include, but are not limited to, phenol type (phenolic)
oxidation inhibitors, such as 4,4'-methylene-bis(2,6-di-tert-butylphenol),
4,4'-bis(2,6-di-tert-butylphenol), 4,4'-bis(2-methyl-6-tert-butylphenol),
2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 4,4'-butylidene-bis(3-
methyl-6-tert-butylphenol), 4,4'-isopropylidene-bis(2,6-di-tert-
butylphenol), 2,2'-methylene-bis(4-methyl-6-nonylphenol), 2,2'-
isobutylidene-bis(4,6-dimethylphenol), 2,2'-methylene-bis(4-methyl-6-
cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-
ethylphenol, 2,4-dimethyl-6-tert-butyl-phenol, 2,6-di-tert-l-
dimethylamino-p-cresol, 2,6-di-tert-4-(N,N'-
d imethylaminomethylphenol), 4,4'-thiobis(2-methyl-6-tert-butylphenol),
2,2'-thiobis(4-methyl-6-tert-butylphenol), bis(3-methyl-4-hydroxy-5-tert-
butylbenzyl)-sulfide, and bis(3,5-di-tert-butyl-4-hydroxybenzyl).
Diphenylamine-type oxidation inhibitors include, but are not limited to,
alkylated diphenylamine, phenyl-.alpha.-naphthylamine, and alkylated-
.alpha.-naphthylamine. Other types of oxidation inhibitors include metal
dithiocarbamate (e.g., zinc dithiocarbamate), and
methylenebis(dibutyldithiocarbamate).
3. Anti-Wear Agents
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CA 02341924 2001-03-21
As their name implies, these agents reduce wear of moving metallic
parts. Examples of such agents include, but are not limited to,
phosphates, phosphites, carbamates, esters, sulfur containing
compounds, and molybdenum complexes.
4. Rust Inhibitors (Anti-Rust Agents)
a) Nonionic polyoxyethylene surface active agents: polyoxyethylene
lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene
nonyl phenyl ether, polyoxyethylene octyl phenyl ether,
polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether,
polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol
mono-oleate, and polyethylene glycol mono-oleate.
b) Other compounds: stearic acid and other fatty acids, dicarboxylic
acids, metal soaps, fatty acid amine salts, metal salts of heavy
sulfonic acid, partial carboxylic acid ester of polyhydric alcohol, and
phosphoric ester.
5. Demulsifiers
Addition product of alkylphenol and ethylene oxide, polyoxyethylene
alkyl ether, and polyoxyethylene sorbitan ester.
6. Extreme Pressure Agents (EP Agents)
Zinc dialkyldithiophosphate (primary alkyl, secondary alkyl, and aryl
type), sulfurized oils, diphenyl sulfide, methyl trichlorostearate,
chlorinated naphthalene, fluoroalkylpolysiloxane, and lead
naphthenate.
7. Friction Modifiers
Fatty alcohol, fatty acid, amine, borated ester, and other esters.
8. Multifunctional Additives
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CA 02341924 2001-03-21
Sulfurized oxymolybdenum dithiocarbamate, sulfurized
oxymolybdenum organo phosphorodithioate, oxymolybdenum
monoglyceride, oxymolybdenum diethylate amide, amine-molybdenum
complex compound, and sulfur-containing molybdenum complex
compound.
9. Viscosity Index Improvers
Polymethacrylate type polymers, ethylene-propylene copolymers,
styrene-isoprene copolymers, hydrated styrene-isoprene copolymers,
polyisobutylene, and dispersant type viscosity index improvers.
10. Pour Point Depressants
Polymethyl methacrylate.
11. Foam Inhibitors
Alkyl methacrylate polymers and dimethyl silicone polymers.
BASE OIL OF LUBRICATING VISCOSITY
The base oil of lubricating viscosity used in such compositions may be
mineral oils or synthetic oils of viscosity suitable for use in the crankcase
of
an internal combustion engine. The base oils may be derived from synthetic
or natural sources. Mineral oils for use as the base oil in this invention
include, for example, paraffinic, naphthenic and other oils that are
ordinarily
used in lubricating oil compositions. Synthetic oils include, for example,
both
hydrocarbon synthetic oils and synthetic esters and mixtures thereof having
desired viscosity. Useful synthetic hydrocarbon oils include liquid polymers
of
alpha olefins having the proper viscosity. Especially useful are the
hydrogenated liquid oligomers of C6 to C12 alpha olefins such as 1-decene
trimer. Likewise, alkyl benzenes of proper viscosity, such as didodecyl
benzene, can be used. Useful synthetic esters include the esters of
monocarboxylic acids and polycarboxylic acids, as well as mono-hydroxy
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CA 02341924 2001-03-21
alkanols and polyols. Typical examples are didodecyl adipate, pentaerythritol
tetracaproate, di-2-ethylhexyl adipate, dilaurylsebacate, and the like.
Complex
esters prepared from mixtures of mono and dicarboxylic acids and mono and
dihydroxy alkanols can also be used. Blends of mineral oils with synthetic
oils
are also useful.
LUBRICATING OIL COMPOSITION
The detergency additive of the present invention is useful for imparting
greater detergency to an engine lubricating oil composition. Such a
lubricating
oil composition comprises a major part of base oil of lubricating viscosity
and
an effective minor amount of the detergency additive.
In one embodiment, the lubricating oil composition would contain:
(a) a major amount of at least one base oil of lubricating viscosity;
(b) from 1.0 to 10 wt % of the detergency additive of the present
invention; and
(c) optionally at least one of the following:
(1) a minor amount of a solvent; and
(2) a minor amount of a polyisobutylene.
The lubricating oil optionally may contain a solvent and/or polyisobutylene,
the
solvent may be in an amount of 10 to 20 wt %, preferably 15 to 20 wt %, and
the polyisobutylene in an amount of 0 to 35 wt %, preferably 25 to 30 wt %.
The lubricating oil composition of the present invention is useful in a method
of lubricating an air-cooled two-stroke cycle engine. In that method, the
lubricant composition is supplied to the crankcase of the engine or to the
fuel
added to the engine, and the engine is operated.
In a further embodiment, an engine lubricating oil composition is produced by
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CA 02341924 2001-03-21
blending a mixture of the above components. The lubricating oil composition
produced by that method might have a slightly different composition than the
initial mixture, because the components may interact.
The components can be blended in any order and can be blended as
combinations of components. For instance, the Mannich base and ashless
dispersant can be blended together prior to being blended with the other
components of the mixture, including optionally, a molybdenum compound,
an overbased alkyl oxy benzene sulfonate, and an alkylsalicylate. Likewise,
the solvent and polyisobutylene can be blended with detergency additive prior
to being blended with the base oil.
ADDITIVE CONCENTRATES
Additive concentrates are also included within the scope of this invention.
The
concentrates of this invention comprise the compounds or compound
mixtures of the present invention, preferably with at least one other
additive,
as disclosed above. The concentrates contain sufficient organic diluent to
make them easy to handle during shipping and storage.
Preferably, the additive concentrate would comprise from 5.0 to 15% of an
organic diluent and 85-95 wt % of the detergency additive of the present
invention. Suitable organic diluents that can be used include mineral oil or
synthetic oils, as described above in the section entitled "Base Oil of
Lubricating Viscosity."
FUEL OILS
As is well known to those skilled in the art, two-cycle engine lubricating
oils
are often added directly to the fuel to form a mixture of oil and fuel which
is
then introduced into the engine cylinder. Such lubricant-fuel oil mixtures are
within the scope of this invention. Such lubricant-fuel blends generally
contain
per 1 part of oil about 15-250 parts fuel, typically they contain 1 part oil
to
about 25-100 parts fuel.
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In some two-cycle engines, the lubricating oil can be directly injected into
the
combustion chamber together with the fuel or separated into the fuel just
prior
to the fuel entering the combustion chamber. The two-cycle lubricants of this
invention can be used in this type of engine.
The fuels used 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
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 (e.g., methanol, ethanol, diethyl ether, methyl ethyl
ether, nitromethane). Also within the scope of this invention are liquid fuels
derived from vegetable or mineral sources such as corn, alfalfa, shale and
coal. Examples of such fuel mixtures are combinations of gasoline and
ethanol, diesel fuels, diesel fuels and ether, gasoline and nitromethane, etc.
Particularly preferred is gasoline, that is, a mixture of hydrocarbons having
as
ASTM boiling point of 60 C at the 10% distillation point to about 205 C at the
90% distillation point.
EXAMPLES
The invention will be further illustrated by following examples, which set
forth
particularly advantageous method embodiments. While the Examples are
provided to illustrate the present invention, they are not intended to limit
it.
The detergency additive of the present invention was evaluated in
accordance with the CEC L-79-T-97 test procedure; "3-Hour Detergency Test
Procedure for Two-Stroke-Cycle Gasoline Engine Lubricant Evaluation." The
procedure is under development by the 2T Engine Oil Subcommittee of
Japan Automobile Standards Organization (JASO) and was conducted using
the draft procedure released September 9, 1992 at the Seventh International
Two-Stroke Oil Specification Meeting.
The procedure is designed to evaluate the performance of a two-stroke-cycle
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CA 02341924 2009-08-31
gasoline lubricant relative to engine cleanliness when tested in a single
cylinder engine; Honda TM SK-50Mm air-cooled engine. Tests are conducted
using unleaded gasoline mixed with lubricant to be evaluated at 100:1 fuel oil
ratio. The following critical areas are inspected and rated in accordance with
JPI-5S-34-91 rating manual:
= Piston Ring Sticking (top and second ring)
= Piston Land Deposits (top and second land)
= Piston Ring Groove Deposits (top and second groove)
= Piston Skirt Deposits
= Piston Undercrown Deposits
= Piston Crown Deposits
= Cylinder Head Deposits
The Total Actual Merit is calculated as the sum of the ratings referred to
above. The higher the number, the better the performance.
Besides as specified in the examples below, all formulations contained a
polyisobutene, mix of heavy and light neutral base oils, and solvent. Test
results are presented in Table I.
Example 1
Formulation I contains 1.12 wt % Mannich detergent, 4.75 wt % ashless
dispersant.
Example 2
Formulation II contains 1.12 wt % Mannich detergent, 3.85 wt % ashless
dispersant.
Example 3
Formulation III contains 1.12 wt % Mannich detergent, 3.85 wt % ashless
dispersant, and 0.25 wt % molybdenum compound.
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Example 4
Formulation IV contains 0.80 wt % Mannich detergent, 3.85 wt % ashless
dispersant and 0.38 wt % alkylsalicylate.
Example 5
Formulation V contains 0.80 wt % Mannich detergent, 3.85 wt % ashless
dispersant, 0.25 wt % molybdenum compound and 0.38 wt % alkylsalicylate.
Example 6
Formulation VI contains 0.80 wt % Mannich detergent, 3.85 wt % ashless
dispersant, 0.16 wt % overbased alkyl oxy benzenene sulfonate.
Example 7
Formulation VII contains 0.80 wt % Mannich detergent, 3.85 wt % ashless
dispersant, 0.16 wt % overbased alkyl oxy benzene sulfonate and 0.19 wt %
alkylsalicylate.
Example 8
Formulation VII contains 0.80 wt % Mannich detergent, 3.85 wt % ashless
dispersant, 0.25 wt % molybdenum compound, 0.16 wt % overbased alkyl oxy
benzene sulfonate, and 0.19 wt % alkylsalicylate.
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CA 02341924 2001-03-21
Table I
Formulations, wt %
Components I 11 III IV V VI Vil VIII
Mannich Detergent 1.12 1.12 1.12 0.80 0.80 0.80 0.80 0.80
Ashless Dispersant 4.75 3.85 3.85 3.85 3.85 3.85 3.85 3.85
Molybdenum Compound 0.25 0.25 0.25
Overbased Alkyl Oxy 0.16 0.16 0.16
Benzene Sulfonate
Alkylsalicylate 0.38 0.38 0.19 0.19
Total Actual Merit 72.8 73.7 78.0 75.9 79.5 74.9 78.3 78.3
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