Note: Descriptions are shown in the official language in which they were submitted.
U'O 9~/12 92-1 PCI/US91/09599
- 1 - 2~9732f~
SMOKE REDUCING ADDITIVES FOR
TWO-CYCLE ENGINE LUBRICANT-FUEL MIXTURE
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a lubricant-fuel mixture for
two-cycle internal combustion engines in which the mixture has reduced
smoke emission due to the presence of an amine salt and/or amide of a
derivative of benzoic ~cid or thiobenzoic acid, a hydrocarbyl substi-
tuted amine salt of a derivative of phosphoric acid, or certain
auaternary ammonium hydroxides.
; 2. DescriDtion of Related Art
In the last several years, the use of spark-ignited two-
cycle internal combustion engines has increased significantly. This
is due to their use in a variety of garden and recreational equipment
such as motorcycles, marine outboard eng~nes, snowmobiles, power
mowers, snow blowers, chain saws, and the like. As such, the amount
of smoke released from two-cycle engines has become a major environ-
mental concern to engine manufacturers and fuel suppliers. However,
few smoke reducing additives are commercially available, and the few
that are contain metals7 which are environmentally undesirable.
Amine salts of certain benzoic acid derivatives have been
used as extreme pressure (EP) agents for water-based metal cutting
fluids (see for example, Japanese Patent No. 55023132). Substituted
benzoic acids have also been used as EP agents in water-based fluids
(see for example, U.S. Patent 4,569,776). U.S. Patent No. 4,434,066
discloses a water based hydraulic fluid containing a combination of a
hydroxyl-substituted aromatic acid component and a nitroaromatic
comp^-~nd component. U.S. Patent ~o. 4,01~,331 discloses a lubricatin~
oil composition comprising a sulfur compound prepared by reacting a
trithiolan compound with a thiol compound in the presence of a base.
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W 0 92tl2224 2 ~ '~ 7 3 2 ~ PCT/~'S9l/09~9~,~
-- 2
Similarly, U.S. Patents 4,787,916 and 4,902,437, together
with the patents disclosed therein, describe the use of quaternary
ammonium hydroxides in fuels and in lubricating oils, respectively.
More recently, the use of a hydrocarbyl substituted amine
salt and/or amide of benzoic acid as an antioxidant in lubricating
oils and as a flow improver in middle distillates has been disclosed
in copending applications U.S. Serial Nos. 582,316 and 545,002,
respectively.
However, none of these publications suggest the particular
ashless two-cycle engine lubricant-fuel mixture disclosed herein or
its effectiveness in reducing the smoke formed during combustion of
the mixture.
SUMMARY OF THE INVENTION
In one embodiment, this invention concerns a two-cycle
engine lubricant-fuel mixture that comprises
(a) a lubricating oil basestock,
(b) a distillate fuel, and
(c) one of the following oil-soluble additives:
(i) a hydrocarbyl substituted amine salt and/or
amide of a compound having the formula
, ' '' ' . ,~
'
w.n 92/12224 ~ ~ ~ r~ CT/US91/09:99
- 3 -
H
,, X
C = X
: Rl ~ R2
R~ ~ R4
~' I
Rs
.wherein X is oxygen or sulfur, and Rl, R2, R3,
R4 and Rs are selected from hydrogen; a hydro-
carbyl group containing from 1 to 24 carbon
atoms; a hydroxy group; and an oxygen-contairllng
hydrocarbyl group containing from 1 to 24 carbon
atoms and at least one of the radicals Rl, R2,
R3, R4 or Rs ;s a hydrocarbyl group containing
from 1 to 24 carbon aioms;
(ii) a hydrocarbyl substituted amine salt of a
compound having the formula
lX
R60 - P - XH
OR7
wherein X is oxygen or sulfur and R6 and R7 are
selected from hydrogen and a hydrocarbyl group
containing from 1 to 28 carbon atoms; or
(iii) a quaternary ammonium hydroxide having the
fo.m.ula
~, .
.
.. .
~',
. . - . ~ .
. :
, .
'~, - : ''
WO 92/12224 PC~/l S~1/09!99r~--
.~ ~ 4 ~
Rg +
Rg~ Rlo OH
Rll
wherein R8 is a hydrocarbon radical or a hydroxy
terminated radical having from 1 to 24 carbon
atoms, Rg is a hydrocarbon radical having from 1
to 24 carbon atoms, and Rlo and R11 are hydro-
carbon radicals having from 4 to 24 carbon
atoms.
In another embodiment, this invention concerns a method for
reducing smoke emission from a two-cycle internal combustion engine by
operating the engine with the lubr-,cant-fuel mixture described above.
' .
DETAILED DESCRIPTION OF THE INVENTION
In general, the two-cycle engine lubricant-fuel mixture of
this invention requires a lubricating oil basestock, a distillate
fuel, and one of the following: an amine salt and/or amide of a
derivative of benzoic acid or dithiobenzoic acid, an amine salt of a
phosphoric acid derivative, or a particular class of quaternary
ammonium hydroxides. However, if desired, other lubricant and distil-
late fuel additives may be present in the mixture as well.
;
The lubricating oil basestock can be derived from natural
lubricating oils, synthetic lubricating oils, or mixtures thereof. In
general; the luhricating nil kasPctrrk will h3Ye ~ kinem.atic Visrosity
- ranging from about 5 to about 10,000 cSt at 40D0, although typical
:.
applications will require an oil having a viscosity ranging from about
10 to about 1,000 cSt at 40~C.
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W~ 92/1''224 9 r1 ~ 2 ~ PCr/~'S91/09599
-- 5 --
Natural lubricating oils include animal oils, vegetable oils
(e.q., castor oil and lard oil), petroleum oils, mineral oils, and
oils derived from coal or shale.
Synthetic oils include hydrocarbon oils and halo-substituted
hydrocarbon oils such as polymerized and interpolymerized olefins
(e.q. polybutylenes, polypropylenes, propylene-isobutylene copolymers,
chlorinated polybutylenes, poly(l-hexenes), poly(l-octenes), poly(l-
decenes), etc., and mixtures thereof); alkylbenzenes (e.q. dodecyl-
benzenes, tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)ben-
zene, etc.); polyphenyls (e.q. biphenyls, terphenyls, alkylated
polyphenyls, etc.); alkylated diphenyl ethers, alkylated diphenyl
sulfides, as well as their derivatives, analogs, and homologs thereof;
and the like.
Synthetic lubricating oils also include alkylene oxide
polymers, interpolymers, copolymers and derivatives thereof wherein
the terminal hydroxyl groups have been modified by esterification,
etherification, etc. This class of synthetic oils is exemplified by
polyoxyalkylene polymers prepared by polymerization of ethylene oxide
or propylene oxide; the alkyl and aryl ethers of these polyoxyalkylene
polymers (e.q., methyl-polyisopropylene 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); and mono- and polycarboxylic
esters thereof (e.~., the acetic acid esters, mixed C3-Cg fatty acid
esters, and C13 oxo acid diester of tetraethylene glycol?.
Another suitable class of synthetic lubricating oils com-
prises the esters of dicarboxylic acids (e.~., 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, alkylm21Onic acids, alkenyl malonic
acids, etc.) with a variety bf alcohols (e.q., butyl alcohol, hexyl
alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, di-
ethylene glycol monoether, propylene glycol, etc.). Specific examples
of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
~ : '
'
wo 9'/12224 ` PCT~US91/0~999
3'732~ - 6-
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 tetra-
ethylene glycol and two moles of 2-ethylhexanoic acid~ and the like.
Esters useful as synthetic oils also include those made from
Cs to C1~ monocarboxylic acids and polyols and polyol ethers such as
neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaeryl-
thritol, tripentaerythritol, and the like.
Silicon-based oils ~such as the polyalkyl-, polyaryl-,
polyalkoxy-, or polyarylaxy-siloxane oils and silicate oils) comprise
another useful class of synthetic lubricating oils. These oils
include tetraethyl silicate, tetraisopropyl silicate, tetra-~2-ethyl-
hexyl) silicate, tetra-(4-methyl-2-ethylhexyl) silicate, tetra(p-tert-
butylphenyl) silicate, hexa-(4-methyl-2-pentoxy)-disiloxane,
poly(méthyl)-siloxanes and poly(methylphenyl) siloxanes, and the like.
Other synthetic lubricating oils include liquid esters of phosphorus~
containing acids (e.g., tricresyl phosphate, trioctyl phosphate,
diethyl ester of decylphosphonic acid), polymeric tetrahydrofurans,
polyalphaolefins, and the like.
The lubricating oil may be derived from unrefined, refined,
rerefined oils, or mixtures thereof. Unrefined oils are obtained
directly from a natural source or synthetic source (e.q., coal, shale,
or tar sands bitumen) without further purification or treatment.
Examples of unrefined oils include a shale oil obtained directly from
a retorting operation, a petroleum oil obtained directly from distil-
lation, or an ester oil obtained directly from an esterification
process, each of which is then used without further treatment.
Refined oils are similar to the unrefined oils except that refined
oils have been tre2ted in one cr more ~rification s~eps 'o .mprove
one or ~ore properties. Suitable purification techniques include
distillation, hydrotreating, dewaxing, solvent extraction, acid or
base extraction, filtration, and percolation, all of which are known
to those skilled in the art. Rerefined oils are obtained by treating
:
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WC) 92~1222~ PCl tUS91/09599
~ rJ ~
refined oils in processes similar to those used to obtain the refined
oils. These rerefined oils are also known as reclaimed or reprocessed
oils and often are additionally processed by techniques for removal of
spent additives and oil breakdown products.
If desired, other additives known in the art may be added to
the lubricating base oil. Such additives include dispersants, anti-
wear agents, antioxidants, corrosion inhibitors, detergents, pour
point depressants, extreme pressure additives, viscosity index
improvers, friction modifiers, and the like. These additives are
typically disclosed, for example, in "Lubricant Additives" by C. V.
Smalhear and R. Kennedy Smith, 1967, pp. 1-11 and in U.S. Patent
4,1~5,571, the disclosures of wh;ch are ;ncorporated herein by rafer-
ence.
The distillate fuels used in two-cycle engines are well
known to those skilled in the art and usually contain a major portion
o~ a normally liquid fuel such as hydrocarbonaceous petroleum distil-
late fuel (a.g., motor gasoline as defined by ASTM Specification
D-439-73). Such fuels can also contain non-hydrocarbonaceous mate-
rials such as alcohols, ethers, organo-nitro compounds and the like
(e.q. methanol, ethanol, diethyl ether, methyl ethyl ether, nitro-
methane), are also within the scope of this invention as 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 fuel and ether, gasoline and nitro-
methane, etc. Particularly preferred is gasoline, that is, 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.
Two-cycle fuels may also contain other additives which are
well known to those skilled in the art. These can include anti-knock
agents such 2' tetra-alkyl lead compounds, le~d scavengers such as
halo-alkanes (e.q., ethylene dichloride and ethylene dibromide), dyes,
cetane improvers, anti-oxidants such as 2,6-di-tertiary-butyl-4-
methylphenol, rust inhibitors such as alkylated succinic acids and
anhydrides, bacteriostatic agents, gum inhibitors, metal deactivators,
U'O 92/17224 ~ PCT/~'S91/095~9
-- 8 --
demulsifiers, upper cylinder lubricants, anti-icing agents, and the
like. This invention is useful with lead-free as well as lead con-
taining fuels.
The lubricant-fuel mixture of this invention will a?so
contain a hydrocarbyl substituted amine salt and/or amide of an oil-
soluble benzoic acid or thiobenzoic acid derivative, an amine salt of
a phosphoric acid derivative, or a particular class of quaternary
ammonium hydroxides.
The hydrocarbyl substituted amine salt and/or amide (prefer-
ably an amine salt) of an oil-soluble benzoic acid or thioben~oic acid
derivative has the formula
I = X
I
Rl~ R2
R3~R4
R5
wherein X is oxygen or sulfur, preferably sulfur, and Rl, R2, R3, R4
and Rs are selected from hydrogen; a hydrocarbyl group containing from
l to 24 carbon atoms, preferably an alkyl group containing from 1 to
18 carbon atoms; a hydroxy group, l.e., -OH; and an oxygen-containino
hydrocarbyl group containing from 1 to 24 carbon atoms and at least
one of the radicals Rl, R2, R3, R4 or Rs is a hydrocarbyl, preferably
an alkyl group, containing from 1 to 24, preferably from 1 to 18
carbon atoms, most preferably from 1 to 6 carbon atoms.
~ pPcif;~ e~amplPs of the ben70ic or dithiohPnzolr acid
derivatives include 4-hydroxy 3,5 ditertiary butyl dithiobenzoic acid;
.
,
WO 92/12224 PCI/I,'S91/09599
9 ~ 3 2 1'~
4-hydroxy 3,5 ditertiary butyl benzoic acid; 3,5 dimethyl dithioben-
zoic acid; 4-hydroxy 3,5 dimethyl dithiobenzoic acid and the like.
The oil soluble additive is formed in a conventional manner
by mixing substantially equimolar amounts of the benzoic acid deriva-
tive and a hydrocarbyl substituted amine at temperatures generally in
the range of 20C - 100DC.
The hydrocarbyl groups of the amine include groups which may
be straight or branched chain, saturated or unsaturated, aliphatic,
cycloaliphatic, aryl, alkaryl, etc. Said hydrocarbyl groups may
contain other groups, or atoms, e.q. hydroxy groups, carbonyl groups,
ester groups, or oxygen, or sulfur, or chlorine atoms, etc. These
hydrocarbyl groups will usually be long chain, e.4. C12 to C40, e.g.
C14 to C24. However, some short chains, e.q. C1 to C11 may be in-
cluded as long as the total numbers of carbons is sufficient for
solubility. Thus, the resulting compound should contain a sufficient
hydrocarbon content so as to be oil-soluble. The number of carbon
atoms necessary to confer oil solubility will vary with the degree of
polarity of the compound. The compound will preferably also have at
least one straight chain alkyl segment extending from the compound
containing 8 to 40, e.~. 12 to 30 carbon atoms.
The amines may be primary, secondary, tertiary or quater-
nary, but preferably are secondary. If amides are to be made, then
primary or secondary amines will be used.
Examples of primary amines include n-dodecyl amine, n
tridecyl amine, C13 Oxo amine, coco amine, tallow amine, behenyl
amine, etc. Examples of secondary amines include methyl-lauryl amine,
dodecyl-octyl amine, coco-methyl amine, tallow-methylamine, methyl-
n-octyl amine, methyl-n-dodecyl amine, methyl-behenyl amine, ditallow
amine etc. Examples of tertiar; amines Include coco-diethyl amine,
cyclohexyl-diethyl amine, coco-dimethyl amine, tri-n-octyl amine,
di-methyl-dodecyl amine, methyl-ethyl-coco amine, methyl-cetyl stearyl
amine, etc.
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wo 92/12224 ;~ ~ ~ 7 3 2 6 Pcr/us9l/09~99
-- 10 --
Amine mixtures may also be used and many amines derived from
natural materials are mixtures. The preferred amines include the long
straight chain alkyl amines containing from 8 to 40, preferably from
12 to 24, carbon atoms. Naturally occurring amines, which are gener-
ally mixtures, are preferred. Examples include coco amines derived
from coconut oil which is a mixture of primary amines with straight
chain alkyl groups ranging from C8 to Clg. Another example is d;
tallow amine, derived from hydrogenated tallow acids, which amine is a
mixture of C14 to Clg straight chain alkyl groups. Ditallow amine is
particularly pre~erred.
The hydrocarbyl substituted amine salt of an oil-soluble
phosphoric acid derivat,ive has the formula
X
I
R60 - P - X~l
OR7
wherein X is oxygen or sulfur, preferably sulfur, and Rs and R7 are
selected from hydrogen and a hydrocarbyl group containing from 1 to 28
carbon atoms, preferably an alkyl group containing from 4 to 12 carbon
atoms. Preferably, at least one of the radicals R6 or R7 is a hydro-
carbyl group, preferably an alkyl group, containing from 3 to 18
carbon atoms.
Specific examples of the phosphoric acid derivative include
dioctyldithiophosphoric acid; dihexyldithiophosphoric acid; dibutyl-
dithiophosphoric acid; didodecylphenyldithiophosphoric acid; dioctyl-
phosphoric acid; butylhexyldithiophosphoric acid; butyloctyldithio-
phosphoric acid-; and the like.
,
The phosphoric acid derivative may be formed in a conven-
tional manr,er by mixing substantially equimolar amounts of the phos-
phoric acid derivative and a hydrocarbyl substituted amine at tempera-
tures generally in the range of 15 to 100C. The hydrocarbyl substi-
tuted amines include those described with respect to the preparation
of the aforedescribed second component. The preferred amines include
O 92/12224 PCr/USsl~09599
r~ 13
the long straight chain alkyl amines containing from 8 to 40, prefer-
ably from 12 to 18, carbon atoms. Naturally occurring amines, which
are generally mixtures, are preferred. Examples include coco amines
derived from coconut oil which is a mixture of primary amines with
straight chain alkyl groups ranging from Cg to C1g. Another example
is tallow amine, derived from hydrogenated tallow acids, which amine
is a mixture of C14 to C1g straight chain alkyl groups. Tallow amine
is particularly preferred.
The oil-soluble quaternary ammonium hydroxide has the
formula
R8 N Rlo OH
1"
wherein R8 is a hydrocarbon radical (or group) or a hydroxy terminated
radical (or group) having from 1 to 24 carbon atoms, Rg is a hydrocar-
bon radical having fr~m 1 to 24 (preferably from 4 to 24) carbon
atoms, and R1o and R11 are hydrocarbon radicals having from 4 to 24
carbon atoms. The hydrocarbon radicals (Rg, Rg, R1o, and R11) can be
alkyl groups, unsaturated paraffin groups, cyclic hydrocarbon groups,
aryl groups, arylalkyl groups or mixtures thereof. In addition, said
groups can be normal, branched, substituted groups or mixtures there-
of. The hydrocarbon radicals may also contain other atoms such as
nitrogen, oxygen, or sulfur; e.q., in the form of an alcohol, an
amine, a ketone, a sulfide, a thiosulfide, and other functionalities.
Quaternary ammonium hydroxides in which the ..ydrocarbon
radical is oc~yl, dodecyl, decyl, octadecyl, capryl radicals, or their
mixtures are preferred. Preferred quaternary ammonium hydroxides are
dimethyl dioctadecyl ammonium hydroxide, tetraoctyl ammonium
W O 92/12_~4 ~ ~ - 12 - PCT/~'S91/0959
hydroxide, tricaprylmethyl ammonium hydroxide, or mixtures thereof.
Tetraoctyl ammonium hydroxide, tricaprylmethyl ammonium hydroxide, or
mixtures thereof are especially preferred, with tricaprylmethyl
ammonium hydroxide being most preferred.
The quaternary ammonium hydroxides desc:ribed hereinabove can
be readily prepared from their corresponding commercially available
quaternary ammonium salt, such as a halide. For example, a quaternary
ammonium chloride may be contacted with an anion exchange resin such
that the chloride is exchanged to produce the corresponding quaternary
ammonium hydroxide.
Oil-soluble, as used herein, means that the additive is
soluble in the mixture at ambient temperatures, e.q., at least to the
extent of about 5 wt.% additive in the mixture at 25"C.
As is well known to those skilled in the art, two-cycle
engine lubricating o~ls are often added directly to the fuel to form a
mixture of oil and fuel which is then ;ntroduced into the engine
cylinder. Such lubricant-fuel blends generally contain per I part of
oil about 20-250 part, fuel, typically they contain 1 part oil to
about 30-100 parts fuel.
; The amount of additive in the mixture can vary broadly
depending on the lubricant-fuel mixture ratio. Accordingly, only an
amount effective in reducing the smoke of the mixture need be added.
In practice, however, the amount of additive added will range from
about O.I to about 5 wt.%, preferably from about 0.5 to about 1 wt.%,
based on weight of lubricant in the lubricant-fuel mixture.
The invention will be further understocd by reference to the
following Example, which include preferred embodiments of this inven-
tion.
U ~ 92/12~2~ PCT/~IS91/0959
- 13 - 6~ 3
Exam~le
Three samples of the same lubricant-fuel mixture were tested
in a single cylinder Yamaha snowmobile engine to determine the maximum
smoke produced by each sample. The mixture comprised a commercially
available two-cycle engine lubricating oil and a commercially avail-
able unleaded gasoline having an RON of 91 and an oil to fuel ratio of
1 to 33. The samples tested were the lubricant-fuel mlxture without
additives, the mixture with a conventional smoke reducing additive
(barium sulfonate), and the mixture with dihydrogenated tallow
amine:4-hydroxy-3,5-ditert-butyldithiobenzoate (DTA:DTB). The maximum
-- smoke produced when operating the engine at 4500 rpm and applying a 10
Nm (Newton meter) load was measured by inserting an optical opacity
smokemeter into the exhaust system. The same procedure was repeated
using dihydrogenated tallow amine: dioctyldithiophosphate (DTA:DDP)
and tricapryl methyl ammonium hydroxide (TCMAH) instead of DTA:DTB.
The results of these tests are shown in Table 1 below.
Table 1
.,
Max. Smoke
Test No. Additive_ Conc... wt.% Smoke ~% Reduction~_~
1 None -- 49.6 --
2 DTA:DTB 1.0 39.4 21
3 DTA:DDP 1.0 41.2 17
4 TCMAH }.0 37.6 24
Ba Sulfonate 1.0 39.8 20
The data in Table 1 show that the additives of this inven-
tion provide a reduction in smoke comparable with that of barium
sulfonate (a commercially available additive) without the formation of
ash.
