Note: Descriptions are shown in the official language in which they were submitted.
~,o~72~7
Ihe invention relates to a combination of an
ethylene-containing polymer with very long chain hydrocarbons
containing oil solubilizillg groups, said hydrocarbons illus~
trated by beeswax, ozokerite wax and/or long chain ~ olefins,
for improving the cold flow properties of distillate fuel
oil.
Kerosene, which is a solvent for wax, has tradition-
ally been a component of distillate fuel oils, e.g. diesel
fuels, home heating oils, etc. With the demands for kerosene
for use in jet fuels, the amount of kerosene used in distillate
fuel oils has decreased over the years. This, in turn, has
frequently required the addition of wax crystal modifiers,
e.g. pour point depressant additives, to the fuel oil to make
up the lack of kerosene.
One class of such pour point depressant additives are
ethylene containing polymers. The more effective of these
polymers for distillate fuel oil are copolymers of ethylene
with other rnonomers, e.g. copolymers of ethylene and vinyl
esters of lower fatty acids such as vinyl acetate (U.S. Patent
3,048,479); copolymers of ethylene and alkyl acrylate
(Canadian Patent 676,875); terpolymers of ethylene with vinyl
esters and alkyl fumarates (U.S. Patent 3,304,261 and 3,341,309
polymers of ethylene with other lower olefins; etc. Also,
homopolymers of ethylene ~British Patents 848,777 and
993,744) and chlorinated polyethylene (Belgian Patent 707,371)
are now known as distillate pour depressants.
Natural occurring materials which have been used as
pour point depressants for lubricating oils include beeswax
(U.S. Patent 2,107,772) and montan wax (U.S. Patents:
2,107,772; 2,132,355, 2,150,552; 2,158,370; 2,260,994).
Ozokerite is a hydrocarbon wax which has been re-
ported to destroy the macrocrystalline structure of petroleum
107~Z67
paraffins upon addition thereto (Kirlc-Oth~er Encyclopedia of
Chemical I`echnology, 2nd Ed. Vol. 22, page 169, Interscience
Publishers, New York, N.Y.).
U.S. 3,762,888 -teaches improving the cold f]ow proper-
ties of middle distillate fuels with a combination of oil-solu-
ble pour point depressant polymers together with oil-soluble
auxilliary, flow-improving compounds.
The present invention is based upon finding that the
combinations of (~) ethylene-containing polymeric pour point
depressant with: (B) beeswax, (C) ozokerite wax and/or (D)
long chained ~-olefins are particularly effective as flow im-
provers in distillate fuel oils having a cloud point higher
than about -15C.
Many of the aforedescribed prior art materials, while
very effective in lowering the pour point of distillate fuel
oil, sometimes do not sufficiently reduce large wax particles
that tend to be f`iltered out by the screens and other filter
equipment normally used on trucks and in fuel oil storage sys-
tems, etc., with a resulting plugging even though the temper-
ature of the oil is substantially above its pour point.
Because of this increased effectiveness in regulatingwax crystal size, the additive combination of the invention is
particularly useful in diesel fuels in view of the current
tendency and desire to increase the cloud point by raising the
distillation temperature. One advantage of increasing the
cloud point is that the resulting fuel will then contain a
larger proportion of higher molecular weight hydrocarbons,
which increases the BTU value of the fuel. The greater
BTU value gives economies during the operation of diesel
engines, for example, diesel trucks.
~ he wax crystal size of these fuels will frequently
need to be controlled. For example, in the normal operation
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~077Z67
of` diesel trucks, the diesel engine is usually provided with
a fine mesh filter of about 50 microns, e.g. about equivalent
to a 270 mesh screen, ahead of the engine. In cold weather
when the ambient temperature is below the cloud point, it be-
comes especially essential that the wax crystals that form aresufficiently fine so that they will pass through any filters.
As previously indicated, the present invention provides an ad-
ditive combination which can be used to reduce or regulatethe
wax crystal size to thereby obtain improved cold flow properties.
In general, the compositions of the inven-tion will
comprise a major amount of a distillate fuel oil having a cloud
point higher than about -15C. And a minor, flow improving a-
mount of: (A) an ethylene polymer pour point depressant with
a co-additive of either (B) beeswax, (C) ozokerite wax and/or
(D) ~-olefins of at least about 24 carbon atoms, preferably
greater than about 30 carbons usually in relative ratios of
~ 0.3 to 10, preferably 0.5 to 5, parts by weight of (A) per
; part by weight of (B), (C) and/or (D).
1~eco-additives have very long hydrocarbon chains
i.e. at least about 24 carbon atoms and contain a structurally
heterogeneous group such as an ester, an unsaturation and/or
a cyclic structure.
In general, the distillate fuel oils of the invention
will boil in the range of 120C. to 400C., and will have
cloud points usually from about 5 C. to about -15 C. The fuel
. .
oil can comprise straight run, or cracked gas oil, or a blend
in any proportion of straight run and thermally and/or
` catalytically cracked distillates, etc. The most common petro-
~ leum middle distillate fuels are kerosene, diesel fuels,
: 30 jet fuels and heating oils. The low temperature flow
problem is most usually encountered with diesel fuels and
with heating oils. As earlier pointed out, the screens and
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similar structures in the fuel supply lines tend to rapidly
plug up at the low temperatures.
As noted, the middle distillate fuel oils for which
this invention has utility are those of a boiling range of
from about 120C. to about 400 C. and cloud points of at least
about -15C. e.g. ranging from about +5C. to about -15C. and
are f`urther characterized by wax contents at -29 C. of from
about 2 to 15 wt. %. These middle distillate fuels are
similar to the non-responsive fuels referenced in U.S. Patent
3,762,888 which were cold flow improved by the teachings of
said patent.
It has now been found that these middle dis-
tillate fuels having a cloud point of above about -15C. can
be further improved in cold flow properties by utilizing the
co-additives of this invention.
Generally there will be added to a waxy middle dis-
tillate petroleum fuel from about 0.01 to about 3 weight
percent, or more preferably from about 0.05 to about 0.75
weight percent of the additive of the invention. Concentrates
of the additive can also be prepared containing from 3 to 75
weight percent of the additive in a hydrocarbon oil, as for
example, a distillate fuel.
The ethylene polymer pour depressants have a
polymethylene backbone which is divided into segments by
hydrocarbon or oxy-hydrocarbon side chains. These oil-
soluble polymers will generally have a number average molec-
ular weight in the range of about 500 to 50,000, preferably
about 1,000 to about 5,000, as measured for examp]e, by
Vapor Pressure Osmometer, such as using a Mechrolab Vapor
Pressure Osmometer Model 310A. Generally, they will comprise
about 3 to 40, preferably 4 to 20, molar proportions of
ethylene per molar proportion of a second ethylenically
_ 5 _
~077267
unsaturated monomer, which latter monomer can be a single
monomer or a mixture of such monomers in any proportion.
The unsaturated monomers, copolymerizable with
ethylene, include unsaturated mono- and diesters of the
general formula:
R H
C -_ C
R2 R3
wherein Rl is hydrogen or methyl; R2 is a OOCR4 or -COOR4
group wherein R4 is hydrogen or a Cl to C16, preferably a
~ Cl to C4, straight or branched chain alkyl group; and R3
;` is hydrogen or -COOR4. The monomer, when Rl and R3 are
' hydrogen and R2 is -OOCR4 includes vinyl alcohol esters of
C2 to C17 monocarboxylic acids, preferably C2 to C5 mono-
, 15 carboxylic acid. Examples of such esters include vinyl
! acetate, vinyl isobutyrate, vinyl laurate, vinyl myristate,
~l vinyl palmitate, etc. When R2 is -COOR4, such esters in-
.~.
clude methyl acrylate, isobutyl acrylate, methyl methacry-
late, 2-ethylhexyl acrylate, C13 oxo alcohol esters of meth-
acrylic acid, etc. Examples of monomers where Rl is hydro-
~i gen and R2 and R3 are -COOR4 groups, include mono- and di-
i esters of unsaturated dicarboxylic acids such as: mono C13
oxo fumarate, di-C13 oxo fumarate, di-isopropyl maleate, di-
lauryl fumarate; ethylmethyl fumarate; etc.
Another class of monomers that can be copolymer-
` ized with ethylene include C3 to C16 alpha monoolefins,
which can be either branched or unbranched, such as propyl-
ene, isobutene, n-octene-l, isooctene-l, n-decene-l,
dodecene-l, etc.
Still another monomers include vinyl chloride, although
essentially the same result can be obtained by polyethylene
' chlorinated to contain about 5 to 35 wt.% chlorine. Even
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~077Z67
branched polyethylene can be used per se as the pour depress-
ant.
Ihese polyethylene and ethylene copolymer pour de-
pressants are generally formed using a free radical promoter,
or in some cases they can be formed by thermal polymeriza-
tion, or they can be formed by Ziegler-type polymerization
in the case of ethylene with other olefins. The polymers
produced by free radical polymerization appear to be the more
important and can be formed as follows: Solvent, and 0-50
wt. %, of the total amount of monomer other than ethylene,
e.g. an ester monomer, used in the batch, are charged to a
stainless steel pressure vessel which is equipped with a
stirrer and cooling coil. The temperature of the pressure
vessel is then brought to the desired reaction temperature,
e.g. 70 to 250 C., and pressured to the desired pressure
with ethylene, e.g. 800 to 10,000 psig., usually 900 to
6000 psig. Then promoter, usually diluted with the reaction
solvent, and additional amounts of the second monomer, e.g.
unsaturated ester, are added to the vessel continuously, or
at least intermittently, during the reaction time, which
continuous addition gives a more homogeneous copolymer pro-
duct as compared to adding all the unsaturated ester at the
beginning of the reaction. Also during this reaction time,
as ethylene is consumed in the polymerization reaction,
additional ethylene is supplied through a pressure controlling
regulator so as to maintain the desired reaction pressure
fairly constant at all times. Following the completion of
the reaction, usually a total reaction time of 1/4 to 10
hours will suffice, the liquid products are withdrawn from
the pressure vessel, and the solvent removed by stripping,
leaving the polymer as residue.
With respect to -the beeswax, either natural or a
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comparable synthetic beeswax can be used. 'I`he natural~y
occurring beeswax ls an item of commerce remarkably uni-
form in composition regardless of the different strains,
races and varieties of bees. 'I`ypically, it has a melting
point of 16-22C., a KOH/g. acid number of 17 to 21, an
iodine number of 8-12, a specific gravity at 25C. of` 0.955-
0.975 and a hardness (ASTM D-5) of 15. Although as much as
13% of the beeswax is hydrocarbon, the principal constitu-
ents are the esters. The predominant hydrocarbon is hen-
triacontane as in candelilla. It is estimated that as much
as 23% of the total wax is myricyl palmitate, C15H31COOC30H61.
Among the other esters present are myricyl alcohol compounds
with acids, such as cerotic acid, C27H55COOH, estimated at
12% of the total, and other palmitates, such as that of
lacceryl alcohol, C32H650H, estimated at 2% of the total.
Ozokerite is a hydrocarbon wax mixture containing
hydrocarbon with ring structures embedded in a long poly-
methylene chain. 'I'he ozokerite hydrocarbons are higher
molecular weight than the usual waxes which fall within the
n-paraffin series of C17-C35, i.e., they have from 37 to 50
carbons in the hydrocarbon chains.
The long-chain ~-olefins have chain length of at
least about 24 carbons, preferably at least about 30 carbons.
The preferred coadditive is exemplified by a commercially
available mixture which had a carbon number distribution of
about 9 wt.% of C26 and lower, 6 wt.% of C28, 14 wt.% of
C30, 13 wt.% of C32, 11 wt.% of C34 and 15 wt.% of C36 and
higher (up to about C50). It is preferred that the long-
chained ~-olefins have at least 30 carbons and optimally
from about 30 carbons to about 50 carbons.
The coadditives of the invention, i.e., the bees-
wax, ozokerite wax and long-chained ~-olefins are
~0'7~Z~7
characterized hy very long hydrocarbon chains of at least
about 24 carbons, preferably of` at least about 28, and
optimally at least about 30 and up to about 50 carbons.
These coadditives can be further characterized by contain-
ing groups such as esters, unsaturation and/or cyclic ringstructures which groups help impart oil solubility.
The fuel composition of the invention will com-
prise a major amount of the petroleum distillate fuel, and
about 0.005 to 3 wt.%, preferably 0.01 to 1.0 wt.% of the
additive combination of the invention, i.e., the ethylene-
containing polymer with Component (B), the beeswax, and/or
Component C, the ozokerite wax, and/or Component (D), the
long-chained -olefin. Concentrates of the aforesaid
additive combination can also be prepared containing 3 to
60 wt.% of the combination in a solvent, e.g., a distillate
fuel, mineral oil, an aromatic hydrocarbon, etc.
The additive combinations of the invention may be
used alone as the sole oil additive, or in combination with
;~ other oil additives such as corrosion inhibitors, antioxi-
~ 20 dants, sludge inhibitors, pour depressants, etc.
; In carrying out the Examples, the following mater-
ials were used:
Additive A - This consisted of about 55 wt.% light
mineral oil and about 45 wt.qo of an ethylene-vinyl acetate
random copolymer having a number average molecular weight of
about 1900, as determined by Vapor Pressure Osmometry, hav-
ing about 1.5 methyl terminated branches (exclusive of the
methyl groups in the vinyl acetate) per 1,000 molecular
weight of polymer and about 38 wt.% vinyl acetate. The
copolymer was prepared by copolymerizing ethylene and vinyl
acetate with dilauroyl peroxide at a temperature of about
105 C., under about 1050 psig ethylene pressure in cyclo-
. _ g
~, , ~ , '- :
~07';~267
hexane solvent. A typical laboratory preparation of this
polymer is as follows:
A three-liter stirred autoclave is charged with about
1000 ml. of cyclohexane as solvent and about 100 ml. of vinyl
acetate. The autoclave is then purged with nitrogen and then
with ethylene. The autoclave is then heated to 105C. while
ethylene is pressured into the autoclave until the pressure
is raised to about 1050 psig. Then, while maintaining a
temperature of 105C. and said 1050 psig. pressure, about
- 10 160 ml/hour of vinyl acetate and about 80 ml/hour of solution
consisting of 9 wt. % di-lauroyl peroxide dissolved in 91 wt.
% cyclohexane are continuously pumped into the autoclave at
an even rate. A total of 320 ml. of vinyl acetate and 11 gm.
of peroxide are injected into the reactor over a period of
about 2 hours. After the last of said peroxide is injected,
l the batch is maintained at 105C. for an additional 10
.1 ., .
ll minutes. Then, the temperature of the reactor contents is
. .,
lowered to about 60C., the reactor is depressurized, and
` the contents are discharged from the autoclave. The emptied
reactor is rinsed with 1 liter of warm benzene (about 50 C.)
which is added to the product. The product is then stripped
of the solvent and unreacted monomers on a steam bath over-
night by blowing nitrogen through the product.
.~ .
Further examples of this class of polymers are des-
cribed in Canadian Patent 882,194. Details of measuring
the branching on this type of polymer are given in Journal
; of Applied Polymer Science, Vol. 15, pp. 1737-1742 (1971).
Additive (B) - The beeswax, purchased from Inter-
national Wax Refining, Inc., Valley Stream, New York had
; 30 the following specifications:
Melting point 66C.
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~0772~7
KOH/~. acid number 20
Saponification (SAP) value 93
Specific Gravity 0.950 at 20 C.
Additive (C) - I`he ozokerite wax, purchased from
5 International ~lax Refining, Inc., Valley Stream, New York
had the following specifications:
Melting point 91 C.
KOH/g. acid number 0.0
SAP value 0.0
Specific Gravity 0.915 at 20 C.
Paraffin content nil
Additive (D) - A commercially available mixture which
had a carbon number distribution of about 9 wt. % of C26 and
lower, 6 wt. % of C28, 14 wt. % of C30, 13 wt. % of C32, 11
wt. % of C34 and 15 wt. % of C36 and higher (up to about C50).
Additive (D') - A commercially available mixture
of long chain ~ -olefins which had a carbon number distri-
bution of about 26 wt. % of C24, 43 wt. % of C26, 21 wt. %
of C28 and 9 wt. % of C30 and higher.
Fuel - This was a diesel fuel oil having a cloud
point of -6C., a pour point of -6 C., a specific gravity
at 16 C. of 0.8403, and ASTM distillation (D-1160) of 10%
at 203C., of 50% at 284C., and of 90% at 329C., an aniline
point of 70C. and a wax content at -29C of 6.9 wt. %.
This fuel was subjected to a test for predicting the
low-temperature operability of certain fuels, particularly
diesel fuels. The test is conveniently referred to herein
as the "Cold Filter Plug Point" (CFPP) test. The test pro-
cedure is discussed and described in detail in Journal
Inst. Pet. Vol. 52, No. 510 pps. 173 to 185; in particular
on pps. 184 and 185.
In brief, the CFPPT is carried out with a 45 ml.
-- 1 1 --
~077Z67
sample of the oil to be tested which is cooled in a bath
maintaining at about -30 F. Every 2 drop in temperature,
starting from 4 F. above the cloud point, the oil is tested
with a test device consisting of a pipette to whose lower
end is attached an inverted funnel. Stretched across the
mouth of the funnel is a 350 mesh screen having an area of
about 0.45 square inch. A vacuum of about 7" of water is
applied to the upper end of the pipette by means of a vacuum
line while the screen is immersed in the oil sample. ~ue to
the vacuum, oil is drawn across the screen up into the
pipette to a mark indicating 20 ml. of oil. The test is
repeated with each two degrees drop in temperature until
the oil fails to fill the pipette to the aforesaid mark due
to clogging of the screen with wax crystals. The results
of the test are reported as the "operability limit" or cold
filtering plugging point, which is the temperature in F. at
which the oil fails to fill the pipette in prescribed time.
The results of the CFPP1 comparing the additive com-
binations of the invention with either no additive and each
additive separately are shown in the following Table:
Wt. % A.I. Cold Filter Plugging
Test Added Additive Point F. of Fuel
'. 1 - - +ZO
3 0.07 A +16
256 0.07) A) +12
0.07 B)
0.14 B +26
7 0.14 C +24
8 0.07) A) +10
0.07) C)
2 0.06 A +18
4 0.13 A +10
11 0.14 D +22
9 0.06) A) +6
0.07) D)
0.06) A) +10
0.07) D')
The results demonstrate the utility of the inver-
tive combinations. In this fuel the ethylene-vinyl aceta-te
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;
:.
1077'~tj7
random copolymers (A) shows marginal but increasing cold flow
improvement directly related to its concentration (see Tests
1-4) howeverl, UpOIl adding a co-addi-tive the cold f`ilter plug-
ging point is reduced (for beeswax compare results of i`ests 3
and 6; for ozokerite wax compare results of I`ests 3 and 8)
sometimes markedly reduced (for long-chain ~-olefins compare
results of Tests 2 and 9) even though the co-additives by
themselves exhibited no cold flow improvement activity.
This invention has taught that improvements in cold
flow properties of middle dis-tillate fuels can be obtained
for those fuels having a cloud point in excess of about -15C.,
e.g., ranging from about ~5 C. to about -15 C. Although not
known for certain, it appears that the co-additives of the
invention enhance the cold flow properties of these fuels which
have a temperature difference in cloud point and pour point
of no more than about 3C. with marked improvement where the
difference is no more than about 2 C. Surprisingly, these
fuels, which decrease in responsiveness to the co-additives
of U.S. Patent 3,762,888 in a direct relationship to the differ-
; 20 ence between cloud point and pour point, become more responsiveto the co-additives of the invention as this difference d~-
~; creases. For reasons not understood, though it would appear
related to the wax deposition rate of the fuel these rather
non-responsive fuels which have the difference of less than
about 3 C. become improved in cold flow performance by using
the co-additives of the invention which improvement appears
to be inversely related to the magnitude of the difference
between cloud point and pour point.
~'~
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