Fuel Oil Composition Containing Oil-soluble Pour Depressant Polymer And Auxiliary Flow-improving Compound

Abstract

Cold flow properties of fuel oils are improved by addition thereto of certain oil-soluble, pour point depressant polymers together with non-nitrogen containing, oil-soluble, auxiliary, flow improving compounds.

Description

BACKGROUND OF THE INVENTION

This invention relates to the treatment of petroleum oil to improve the flow properties. More specifically, it relates to middle distillate fuel oils containing certain polymers in combination with non-nitrogen-containing, oil-soluble, auxiliary, flow-improving compounds.

DESCRIPTION OF THE PRIOR ART

Kerosene, which acts as a solvent for n-paraffin wax, has traditionally been a component of middle distillate fuel oils. Recently, with the increased demand for kerosens for use in jet fuels, the amount of kerosene used in middle distillate fuel oils has decreased. 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 for the lack of kerosene.

The more effective of these distillate oil pour depressants are copolymers of ethylene with various other monomers, e.g. copolymers of ethylene and vinyl esters of lower fatty acids such as vinyl acetate (U.S. Pat. No. 3,048,479); copolymers of ethylene and alkyl acrylate (Canadian Pat. No. 676,985); terpolymers of ethylene with vinyl esters and alkyl fumarates (U.S. Pat. Nos. 3,304,261 and 3,341,309); polymers of ethylene with other lower olefins, or homopolymers of ethylene (British Pat. Nos. 848,777 and 993,744); chlorinated polyethylene (Belgium Pat. No. 707,371 and U.S. Pat. No. 3,337,313); etc.

However, in general, these ethylene backbone pour point depressants, while very effective in lowering the pour point of distillate oil, sometimes have little or no effect on wax crystal size. Wax crystals having large particle sizes ranging from 1 millimeter up to an inch in their larger dimensions may therefore be present in these fuels. These large particles tend to be filtered out by the screens and other filter equipment normally used on delivery trucks and fuel oil storage systems, with a resulting plugging of these screens and filters even though the temperature of the oil is substantially above its pour point.

Prior art flow improvers also include the use of naturally occurring waxes or nitrogen compounds. Typical of prior art flow improvers are those shown in U.S. Pat. No. 3,250,599 and U.S. Pat. No. 2,615,799 and U.S. Pat. No. 2,917,375 including mixtures of ethylene-vinyl acetate copolymers or of polymers of esters of acrylates or methacrylates together with microcrystalline waxes or normal paraffins. U.S. Pat. No. 3,444,082 discloses the use of certain nitrogen-containing compounds as does British Pat. No. 1,140,171. Other prior patents of interest include U.S. Pat. No. 3,166,387, British Pat. No. 1,154,966, etc. It has now been found that materials other than nitrogen-containing materials or naturally occurring compositions can be used to improve the performance of flow improvers.

SUMMARY OF THE INVENTION

In accordance with certain of its aspects, the novel fuel oil composition of this invention comprises:

a. a major portion of a middle distillate fuel boiling in the range of 250.degree. -750.degree.F., and a minor portion of a flow-improving system containing

b. as a first component an oil-soluble, pour point depressant polymer of molecular weight M.sub.n of 500-50,000 selected from the group consisting of:

an ethylene polymer,

a hydrogenated olefin polymer,

a C.sub.10-18 olefin polymer,

a halogenated ethylene polymer, and

a polymer of 3-40 moles of ethylene and one mole of

a copolymerizable comonomer selected from the group consisting of

i. a vinyl ester of a C.sub.1-17, perferably C.sub.2-9 monocarboxylic acid,

ii. an ethylenically unsaturated ester ##SPC1##

wherein X is H, halogen, or alkyl, Y is halogen or --COOR and R is C.sub.1-16, perferably C.sub.2-8 alkyl or aryl,

iii. an ethylenically unsaturated compound ##SPC2##

wherein R' is H or lower alkyl and R" is H or C.sub.1-16, preferably C.sub.2-8 alkyl; and

iv. a C.sub.3-18, preferably C.sub.3-8 olefin hydrocarbon;

c. as a second component a non-nitrogen-containing, oil-soluble auxiliary flow-improving compound containing at least one straight-chain (CH.sub.2).sub.n polymethylene segment where n is 10-30 and a bulky substituent on said polymethylene segment selected from the group consisting of (i) non-polar hydrocarbon moieties substantially free of saturated cyclic hydrocarbons, and (ii) polar moieties containing halogen, oxygen, sulfur, or phosphorous.

The middle distillate fuel oils which may be treated by the technique of this novel invention may commonly have a fluidity, prior to treatment, of 0-20 percent, say 0-10 percent typically 5 percent as measured by a standard test herein designated the Enjay Programmed Fluidity Test. This test may be carried out in an hour-glass-shaped cylindrical device having upper and lower chambers separated by a partition defining a capillary orifice. 40 ml. of oil are poured into the lower chamber, and the device containing the oil is then chilled from a temperature of 10.degree.F. above its ASTM cloud point, at a rate of 4.degree.F. per hour, to a temperature of 10.degree.F. below its cloud point. The device is inverted, allowing the now cloudy oil to flow by gravity into the empty lower chamber. The volume percent of the oil passing through the orifice in three minutes is noted. If the wax is in large crystals, it of course blocks the orifice and slows the oil flow. Small crystals, on the other hand, give good flow.

Another test which may be used to determine the flow properties of a middle distillate is the "Cold Filter Plugging Point Test" (CFPPT). This test is carried out by the procedure described in detail in "Journal of the Institute of Petroleum", Volume 52, Number 510, June 1966, pp. 173-185. In brief, the Cold Filter Plugging Point Test is carried out with a 45 ml. sample of the oil to be tested which is cooled in a bath maintained at about -30.degree.F. Every 2.degree. drop in temperature, starting from 4.degree.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 sqaure 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. Due 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 filter plugging point, which is the temperature in .degree.F. at which the oil fails to fill the pipette in prescribed time.

The preferred fuel oil compositions which may be treated by the process of this invention may include middle distillate fuels having a boliing point in the range of 250.degree.-750.degree.F. Commonly, the 10-90 percent boiling range of the middle distillate will fall within the range of 250.degree.-750.degree.F., eg, 300.degree.-700.degree.F. Typical of these compositions may be those commonly designated middle dsitillate fuel oil.

The oil-soluble, pour point depressant which may be the first component of the composition or system used in practice of this invention, typically present, per 100 parts of oil, in amount of 0.001 - 0.5 parts, preferably 0.005 - 0.3 parts, say 0.02, may be selected from the group consisting of:

an ethylene polymer,

a hydrogenated olefin polymer,

a C.sub.10-18 olefin polymer,

a halogenated ethylene polymer, and

a polymer of 3-40 moles of ethylene and one mole of a copolymerizable comonomer selected from the group consisting of

i. a vinyl ester of a C.sub.1-17, preferably C.sub.2-9 monocarboxylic acid,

ii. an ethylenically unsaturated ester ##SPC3##

wherein X is H, halogen, or alkyl, Y is halogen or --COOR and R is C.sub.1-16, preferably C.sub.2-8 alkyl or aryl,

iii. an ethylenically unsaturated compound ##SPC4##

wherein R' is H or lower alkyl and R" is

H or C.sub.1-16, preferably C.sub.2-8 alkyl; and

iv. a C.sub.3-18, preferably C.sub.3-8 olefin hydrocarbon.

When the first component is an olefin polymer, it may preferably be an alpha-olefin polymer; preferably, it may be a polymer of ethylene or a copolymer thereof with one of the compounds listed in Table I:

TABLE I

propene

butent-1

pentene-1

3-methyl butene-1

hexene-1

3-methyl pentene-1

4-methyl pentene-1

heptene-1

3-methyl hexene-1

4-methyl hexene-1

5-methyl hexene-1

3-ethyl pentene-1

octene-1

3-methyl heptene-1

4-methyl heptene-1

5-methyl heptene-1

6-methyl heptene-1

3-ethyl hexene-1

4-ethyl hexene-1

3-propyl hexene-1

decene-1

Preferred olefin polymer is polyethylene having a molecular weight M.sub.n of 500-10,000, typically 800-2,500, say 1,500.

When the first component is a hydrogenated olefin polymer, it may be one obtained by hydrogenation of the olefin polymer. Typically the hydrogenated polymer may include hydrogenated polybutadiene and hydrogenated copolymers of ethylene-butadiene, butadiene-styrene, butadiene-isoprene, ethylene-styrene, butadiene-butene-1, etc. Typically the molecular weight M.sub.n may be 500-50,000. A preferred illustrative composition may be polybutadiene having a molecular weight of 3,000 which has been hydrogenated.

When the first component is a halogenated olefin polymer, e.g. a halogenated alpha olefin polymer, it may be one obtained by halogenation (e.g., chlorinating or brominating) the olefin polymer. Typically the so-prepared halogenated alpha olefin polymer may contain 2-30 percent, preferably 5- 15 percent, say 10 percent by weight of halogen. A preferred halogenated olefin polymer may be chlorinated polyethylene, typically containing 10-30 percent, say 20 percent by weight of chlorine and characterized by a molecular weight M.sub.n of 500-50,000, more specifically 1,500-15,000, say 5,000.

In the preferred embodiment, the polymer may be a copolymer of an olefin, more preferably ethylene, with a second copolymerizable monomer. Preferably the copolymer may contain 3- 40 moles of olefin, say ethylene, and one mole of copolymerizable comonomer and optionally one or more moles of other copolymerizable monomer. The comonomer may, in one embodiment, be a vinyl ester of a monocarboxylic acid. Typical of such comonomers may be those listed in the following table.

TABLE II

Vinyl acetate

Vinyl propionate

Vinyl butyrate

Vinyl caproate

Vinyl caprylate

Vinyl caprate

Typical of such copolymers may be the copolymer containing 5 moles of ethylene and one mole of vinyl acetate having a molecular weight M.sub.n of 2,000.

In another embodiment of this invention, the polymer may be a copolymer of 3-40 moles of olefin, preferably ethylene, and an ethylenically unsaturated ester ##SPC5##

wherein X is H, halogen, alkyl, or aryl, and Y is halogen or --COOR wherein R is alkyl, preferably C.sub.1 -C.sub.16 alkyl, more preferably C.sub.2 -C.sub.8 alkyl or aryl.

When X is H, hydrogen, and Y is --COOR, the comonomer may be an alkyl acrylate, typically as set forth in the following table:

TABLE III

Methyl acrylate

Isobutyl acrylate

Lauryl acrylate

C.sub.13 Oxo-alkyl acrylate

When X is halogen, e.g. chlorine, and Y is --COOR, the comonomer may be a chloroacrylate, typically as set forth in the following table:

TABLE IV

Methyl chloroacrylate

Methyl bromoacrylate

Ethyl chloroacrylate

Isobutyl chloroacrylate

When X is alkyl, typically lower alkyl having 1-8 carbon atoms, e.g., methyl, and Y is --COOR, the comonomer may be a methacrylate, typically as set forth in the following table:

TABLE V

Methyl methacrylate

Ethyl methacrylate

Methyl ethacrylate

Isobutyl methacrylate

Lauryl methacrylate

When X is hydrogen and Y is halogen, the comonomer may be e.g., vinyl chloride. When both X and Y are halogen, the comonomer may be e.g., vinylidene chloride.

Of these, the preferred comonomer may be isobutyl acrylate and the preferred polymer may be the copolymer containing 3-40 moles of ethylene and 1 mole of isobutyl acrylate typically having a molecular weight M.sub.n of 500-50,000, preferably 1,500-15,000, say 5,000. Methyl acrylate may also be employed.

When the comonomer is an ethylenically insaturated compound, it may have the formula ##SPC6##

wherein R' is H or lower alkyl, e.g. C.sub.1 -C.sub.8 alkyl and R" is H or alkyl preferably having one to 16 carbon atoms. Illustrative of these, may be those set forth in the following table:

TABLE VI

Fumaric acid

Maleic acid

Monomethyl fumarate

Monobutyl fumarate

Monohexyl maleate

di-isopropyl maleate

di-C.sub.13 Oxo fumarate

di-lauryl fumarate

di-ethyl methylfumarate

When the comonomer polymerized with ethylene is an olefin hydrocarbon having more than two carbon atoms, it may be selected from the compounds of Table I supra. The preferred of such comonomers may be propylene. The preferred copolymers may be copolymers of ethylene-propylene containing 3-40 moles of ethylene and one mole of propylene, e.g. 5 moles of ethylene and one mole of propylene, having a molecular weight M.sub.n of 500-50,000, preferably 1,500-15,000, say 5,000.

The preferred oil-soluble, first component, pour-point depressant may be typically selected from the following table:

TABLE VII

poly(ethylene/propylene)

halogenated poly(ethylene/propylene)

poly(ethylene/vinyl acetate)

poly(ethylene/vinyl chloride)

poly(ethylene/vinylidene chloride)

poly(ethylene/isobutyl acrylate)

poly(ethylene/methyl methacrylate)

poly(ethylene/chloroacrylate)

poly(ethylene/dimethyl fumarate)

Most preferred is the copolymer of about 5 moles of ethylene with one mole of vinyl acetate having a molecular weight of about M.sub.n of 2,000.

This oil-soluble pour-point depressant first component may be present in amount of 0.001-0.5 parts, preferably 0.005-0.30 parts, say 0.02 parts per 100 parts of oil.

The second component of the composition added to the middle distillate fuel oil may be a non-nitrogen-containing oil-soluble auxiliary flow-improving compound containing at least one straight chain (CH.sub.2).sub.n polymethylene segment, wherein n is 10-30, and a bulky substituent on said polymethylene segment selected from the group consisting of (1) non-polar hydrocarbon moieties substantially free of saturated cyclic hydrocarbons and (ii) polar moieties containing or including halogen, oxygen, sulfur, or phosphorous.

The second component of the composition may be a hydrocarbon, halohydrocarbon, ester, acid (including anhydride), ether, ketone, etc.

It is a feature of the novel technique of this invention that many of the first components -- the oil-soluble pour point depressants -- may frequently contribute only little or marginal improvement in flow properties when used alone in "difficult" or "unresponsive" fuels such as some of the commonly available European fuels, e.g., a distillate fuel characterized by a 10 percent boliing point of 384.degree.F., a 90 percent boiling point of 643.degree.F., an aniline point of 163.5.degree.F., a pour point of +5.degree.F., and a cloud point of 26.degree.F. (Fuel C).

Since the second component may normally be one which generally yields little or no flow-improving properties, it is unexpected that it should be able to enhance the flow-improving ability of the first component.

The ability of the combination of this invention to achieve outstanding results in practice of this invention may vary depending upon the particular fuel and the particular combination. The most desirable results may normally be achieved when the fuel is one generally acknowledged to be difficult, i.e., non-responsive to the impact of prior art flow improvers and/or when the flow improver (which may be satisfactory for "normal" fuels) fails, for some unexplained reason to provide the desired effect in the particular fuel oil.

The second component may be a non-nitrogen-containing, oil-soluble auxiliary flow-improving compound containing at least one (CH.sub.2).sub.n polymethylene segment wherein n is 10-30 and a bulky substituent on said polymethylene segment selected from the group consisting of

i non-polar hydrocarbon moieties free of saturated cyclic hydrocarbons, and

ii. polar moieties containing halogen, oxygen, sulfur, or phosphorous.

The second component may contain at least one (CH.sub.2).sub.n polymethylene segment wherein n is 10-30, preferably 14-24. Commonly such segments may include those derived from groups such as hexadecyl, octadecyl, pentacosyl, etc.

The molecule may include a bulky substituent, i.e., one which terminates or interrupts the chain (e.g., is positioned between two adjoining chains or is a side chain on a chain). The bulky substituent may be one which has a discontinuity or steric configuration to provide a non-continuous envelope along the molecule. Typically such bulky substituents may include aromatic rings such as phenyl, the double bond, halogen including chloro, bromo, etc., oxygen as in an acid, anhydride, alcphol or ester residue, ethers as in polyoxyethylene moieties, etc.

When the second component is a hydrocarbon, it may typically be one of those in the following table:

TABLE VIII

Phenyl pentadecane

21-Dotetracontene

Dodecyl toluene

Tetradecyl toluene

Hexadecyl toluene

Octadecyl toluene

21-Dotetracontyl toluene

Chlorowzx toluene condensate

C.sub.42 -C.sub.56 internal olefin

19-Octatriacontene

When the second component is a halohydrocarbon, it may typically be one of the following:

TABLE IX

21-Bromodotetracontane

21-Chlorodotetracontane

Chlorowax

C.sub.30 + alkyl bromide

C.sub.42 -56 alkyl chloride

19-chloroctatriacontane

When the second component is an ester, it may typically be one of the following:

TABLE X

Cholesteryl laurate

Cholesteryl myristate

Cholesteryl palmitate

Cholesteryl erucate

Trilaurin

Phenyl stearate

Sorbitan monopalmitate

Sorbitan monostearate

Sorbitan tristearate

Sorbitol myristate

Sorbitol laurate

Sorbitol stearate

Pentaerythrityl tetrastearate

Pentaerythrityl tetralaurate

Sorbitan monooleate

Sucrose myristate

Sucrose laurate

Sucrose stearate

Sorbitol oleate

Benzoate of sorbitan monostearate

Tristearin

Dibehenyl adipate

A particularly preferred class of esters is the sorbitan esters -- particularly those containing the following structures: ##SPC7##

As commonly available, compositions may be a mixture of these two formulae wherein A, X, Y and Z may be

a. a long-chain fatty acid residue, e.g. stearate, laurate, palmitate, etc. or

b. hydrogen or

c. a polyethoxy residue such as --(CH.sub.2 CH.sub.2).sub.20 H. In particular molecule, at least one of A, X, Y, or Z is other than hydrogen or the polyoxyethylene moiety (CH.sub.2 CH.sub.2 O).sub.n. Typical available compositions may include those having the following designations: sorbitan monostearate; sorbitan tristearate; polyoxyethylene (20) sorbitan tristearate.

When the second component is an acid (including anhydrides), it may typically include the following:

TABLE XI

Erucic acid

Behenic acid

Octadecylsuccinic anhydride

C.sub.22 -C.sub.28 Alkenylsuccinic anhydride

19-octatricontene/maleic anhydride condensate

C.sub.42 -C.sub.56 internal olefin*/maleic anhydride condensate

When the second component is an ether, it may typically be the following:

TABLE XIII

Polyoxyethylene (8) stearate

Polyoxyethylene (8) laurate

Polyoxyethylene (20) stearyl ether

Polyoxyethylene (10) stearyl ether

Polyoxyethylene (2) stearyl ether

Polyoxyethylene (4) lauryl ether

Polyoxyethylene (2) oleyl ether

Polyoxyethylene (20) sorbitan tristearate

Polyoxyethylene (20) sorbitan trioleate

Tetrahydrofurfuryl palmitate

Polyoxyethylene (20) oleylphenol

Polyoxyethylene (6) dodecylphenol

Polyethyleneglycol stearate

Polyethyleneglycol stearate methyl ether

The numbers in parentheses indicate the average number of oxyethylene groups per molecule.

A preferred polyether may have the formula R-(OCH.sub.2 CH.sub.2).sub.2-20 OH wherein R is stearyl.

When the second component is a ketone, it may commonly be prepared by acylation.

A particularly useful group of products may be those prepared by the Friedel-Craft-type acylation (preferably in the presence of aluminum chloride) of long-chain (e.g., containing more than 30 carbon atoms) symmetrical internal olefins with an acyl halide - typically

C.sub.20 H.sub.41 C = C - C.sub.20 H.sub.41 with C.sub.6 H.sub.5 COCl.

Typical of the ketones may be those listed in the following table:

TABLE XIII

21-Dotetracontene/benzoyl chloride

21-Dotetracontene/sebacoyl chloride

21-Dotetracontene/phthaloyl chloride

C.sub.42 -C.sub.56 internal olefin/benzoyl chloride

19-Octatriacontene/benzoyl chloride

C.sub.22 -C.sub.28 olefin/benzoyl chloride

C.sub.22 -C.sub.28 olefin/sebacoyl chloride

C.sub.30 + olefin/benzoyl chloride

C.sub.30 + olefin/sebacoyl chloride

11 Docosene/benzoyl chloride

Myristophenone

The specific first and second components and relative proportions thereof may vary depending upon the properties of the fuel oil. Commonly the formulation may contain 1-99 percent, preferably 4-97 percent, of the first component, the remainder being the second component.

Thus the novel fuel oil compositions which may be prepared by the process of this invention may contain the following proportions of ingredients (per 100 parts of oil):

Component Broad Range Preferred First Component 0.001-0.5 0.005-0.3 Second Component 0.001-0.5 0.005-0.3

In the preferred embodiment the first component and the second component may be employed in the form of a concentrate in a diluent-solvent which is soluble in the oil to which the concentrate is to be added. Typically, such concentrates may contain 5 to 70 parts, preferably 10 to 50 parts, say 40 parts of first and second components in 0-100 parts of dilient-solvent. This diluent-solvent may be an inert liquid in which the first and the second components are soluble or dispersible.

Although each of the first and second components of the composition may be separately formulated in diluent-solvent, it is preferred that they be formulated as a concentrate in a single diluent-solvent; and in the preferred embodiment, the diluent-solvent may be the oil to which the composition is to be added. Typically, this solvent may be a material such as Solvent 325 Neutral, a light lubricating oil base stock, a vacuum gas oil, a heavy aromatic naphtha, Varsol, kerosene, or a distillate heating oil. Other appropriate solvents will be obvious to those skilled in the art.

In the practice of this invention, both the first and the second components may be added to a fuel oil in amount (as a mixture in one diluent-solvent or each in a separate diluent solvent) sufficient to improve the flow properties of the oil. Preferably this amount is about 0.002 to 1.0 parts by weight, typically 0.04 parts by weight per 100 parts of oil.

Practice of the process of this invention in accordance with certain of its aspects, may be effected by adding the first and second components (either sequentially or simultaneously) to the oil, and mixing, thereby forming a petroleum oil composition. Mixing may be done continuously or batchwise. Typically, such formulations may be prepared by adding the flow-improving amount of said flow improvers to a body of the oil at a temperature up to 300.degree.F., preferably greater than 100.degree.F. When the first and second components are added as a concentrate in diluent-solvent, the preferrd temperature may be 60.degree.-200.degree.F., say 130.degree.F. When the first and second components are added, without diluent-solvent, the preferred temperature may be 150.degree.-300.degree.F., say 200.degree.F.

Practice of this invention will be apparent to those skilled in the art from the following examples wherein, as elsewhere in this specification, all parts are parts by weight.

DESCRIPTION OF PREFERRED EMBODIMENT

In the examples which follow, the following middle distillate oils (which are either non-responsive or difficultly responsive to prior art flow improvers) were tested:

Fuel A - Number 2 Heating Oil. A middle distillate oil having an IBP of 374.degree.F., a 10 percent boiling point of 421.degree.F., a 90 percent boiling point of 569.degree.F., a final boiling point of 614.degree.F., a cloud point of -2.degree.F., a pour point of -5.degree.F., an aniline point of 136.degree.F., and containing 3.1 percent wax.

Fuel B - A middle distillate fuel oil having a -6.degree.F. cloud point, a pour point of -10.degree.F., an aniline point of 137.degree.F., a 10 percent boiling point of 474.degree.F., and a 90 percent boiling point of 556.degree.F.

Fuel C - A European middle distillate fuel oil having a 10 percent point of 384.degree.F., a 90 percent boiling point of 643.degree.F., an aniline point of 163.5.degree.F., a pour point of +5.degree.F., and a cloud point of 26.degree.F.

Fuel D - A middle distillate fuel oil from a European source having a 10 percent boiling point of 384.degree. F., a 90 percent boiling point of 610.degree.F., an aniline point of 157.degree.F., a pour point of 0.degree.F., and a cloud point of 16.degree.F.

Fuel E - A middle distillate fuel oil from a European source having a 10 percent boiling point of 372.degree.F., a 90 percent boiling point of 594.degree.F., an aniline point of 150.5.degree.F., a pour point of -10.degree.F., and a cloud point of +6.degree.F.

In each Example of the first series which follows, the middle distillate fuel oil was tested in a control example to determine its flow characteristics by the Enjay Programmed Fluidity Test supra. Typical compositions of this invention containing equal parts by weight of active ingredient of the first and second components were added, in all cases, in the Experimental runs. In further control examples, there was added to the fuel the same total amount of either the first of the second component.

In these Examples, the following middle distillate pour-depressing materials were oil concentrates employed as the first component of the compositions, which concentrates contained the following active ingredients:

I - A copolymer of ethylene-vinyl acetate of M.sub.n of about 2,000, containing about 38 percent by weight of vinyl acetate, and containing about 5 moles of ethylene to 1 mole of vinyl acetate.

II- A chlorinated ethylene polymer having a molecular weight M.sub.n of about 3500 and a chlorine content of about 20 percent.

III- A polymer consisting essentially of ethylene and isobutyl acrylate having a molecular weight M.sub.n of about 3,000 and an isobutyl acrylate content of about 4 percent.

In these Examples, the following were employed as the second component of the compositions:

1. Polyoxyethylene (20) sorbitan tristearate.

2. Polyoxyethylene (2) stearyl ether.

3. Polyoxyethylene (10) stearyl ether.

4. Polyoxyethylene (20) stearyl ether.

5. Sorbitan monopalmitate.

6. Sorbitan tristearate.

TABLE XIV

First Second Total Example Compo- Compo- Conc. Rating nent nent 1* I -- 0.10 74 2 I 1 0.04 100 3 I 2 0.04 100 4 I 3 0.04 95 5* II -- 0.10 44 6 II 1 0.10 100 7 II 2 0.10 100 8 II 3 0.10 92 9 II 4 0.10 92 10* td III -- 0.10 45 11 OOO 2 0.10 78 12 III 3 0.10 100 13 III 4 0.10 93 * Control

In the above Table the fuel oil was Fuel B.

For example, in Example I, presence in the base oil (Fuel B used as base oil in Examples 1-13) of 0.10 parts, per 100 parts of base oil, of first component I gives a rating of 74 when measured by the Enjay Programmed Fluidity Test supra, i.e., in the test time, 74 percent of the fuel passed through the orifice. The original fuel oil is rated at 0-20.

Unexpectedly it is found that use of 0.04 parts total of first component I and second component 1 gives a rating of 100 -i.e., although the total amount of additive employed is only 40 percent of that employed in Example 1, the amount of oil passing through the orifice in test time is 100 percent -- in contrast to 74 percent of Example 1.

Although not set forth in the Table, it may be noted that use of 0.04 parts of second component 1 (and 0 parts of first component I) will yield an unsatisfactory rating.

Similarly, comparison of Control Example 5 with experimental Examples 6-9 reveals that the flow properties may be more than doubled by practice of the instant invention. A comparison of control Example 10 with experimental Examples 11-13 reveals similar outstanding improvements.

In the following series of Examples, the flow properties of Fuels C, D, and E were tested by the CFPP Test noted supra. In each example, the toal amount of added first and second component was 0.015 parts per 100 parts of Fuel. The test rating was determined as the temperature (.degree.F.) at which the oil no longer flows.

TABLE XV

First Second Example Compo- Compo- Fuel Rating .degree.F. nent nent 14* I -- C 20 15 I 5 C 6 16 I 6 C 12 17 I 1 C 14 18 I 3 C 10 19 I 4 C 16 20* I -- D 10 21 I 5 D 2 22 I 6 D 4 23 I 1 D 2 24 I 2 D 4 25 I 3 D 0 26 I 4 D 6 27* I -- E 2 28 I 5 E -8 29 I 6 E -4 30 I 1 E -4 31 I 2 E -6 32 I 3 E -12 33 I 4 E -8 34* III -- D 2 35 III 4 D -2 36* III -- E -4 37 III 5 E -8 38 III 6 E -8 39 III 1 E -1 40 III 2 E -8 41 III 3 E -8 42 III 4 E -8

Rating of Oils with No Additive

Oil Rating C 26 D 12 E 6 * Cpntrol

From the above table it may be apparent that the novel technique of this invention permits attainment of unexpected results. Base Oil C has a rating (with neither first nor second component being present) of 26.degree.F. In Example 14, presence in the base oil (Oil C) of 0.015 parts of first component per 100 parts of base oil yielded a rating of 20. Addition of the same total amount (of a 50--50 mixture by weight) of First Component I and Second Component 5 (q.v. Example 15) desirably decreased the rating to 6.degree.F.

Comparable improvement may be observed by comparing, e.g., control Examples 20 and 27 with the experimental Examples immediately following each.

It will be apparent to those skilled in the art that varying results may be achieved with respect to different of the "difficult" fuels by use of selected combinations of additives. Because of the peculiar, widely-varying, and totally unexpected nature of the difficult fuels, it is not always possible to predict few degree of improvement attained; and in some instances the improvement attained with certain combination may be greater. For instance, where it is less it may be found that other combinations may yield improvement with the fuel; and the combination may be effective in improving another fuel. For example, combination I-4 appears to yield little improvement with Fuels C and D (Examples 19 and 26); but yield significant improvement with Fuel E (Example 33). Those skilled in the art will appreciate this factor and will readily be able to determine from a fee simple observations which combinations will be most effective for particular fuels. Thus it is unexpected that the novel invention permits attainment of markedly improved ratings in oils which are non-responsive to a given first component additive alone. It will also be apparent that some of these combinations may be more effective than certain other combinations.

In each of the second series of Examples which follows, the middle distillate fuel oil was tested in a control example to determine its flow characteristics by the Enjay Programmed Fluidity Test supra. Typical compositions of this invention containing equal parts by weight of active ingredient of the first and second components were added in the Experimental runs. In a first control example (Example 43), there was added to the fuel the same total amount of only the first component.

In these examples, the following pour point depressant concentrate material containing the following active ingredient was employed as the first component of the compositions:

I - A copolymer of ethylene-vinyl acetate of M.sub.n of about 2,000, containing about 38 percent by weight of vinyl acetate, and containing about 5 moles of ethylene to one mole of vinyl acetate.

In the following Table there are tabulated for each Example, the second component (employed in a 50--50 percent mixture by weight of a total weight of additive per 100 parts of oil with the noted first component), and the rating. The rating is given, based upon the results of the Enjay Programmed Fluidity Test supra. For the tests which are passes, the rating is given in terms of percent.

TABLE XVI

Total Weight of Ex. Second Component First and Second Component 0.04 0.02 43* None 100 <50 44 21-Dotetracontene -- 98 45* Dotetracontance 40 <40 46 21-Dotetracontyl toluene 90 47 C.sub.42-56 internal olefin 98 48 19-octatriacontene 100 49 21-bromodotetracontance 100 100 50 21-chlorodotetracontance --tm 100 51 C.sub.42-56 secondary alkyl chloride t n 98 52 tristearin tn 100 53 sorbitan monopalmitate 98 98 54 sorbitan monostearate 92 98 55 sorbitan tristearate 100 98 56 sorbitol stearate 100 100 57 sorbitan monostearate benzoate 98 73 58 octadecyl succinic anhydride 84 80 59 polyoxyethylene(20) stearyl ether 85 77 60 polyoxyethylene(10) stearyl ether 95 98 61 polyoxyethylene(20) sorbitan tristearate 98 98 62 polyethylene glycol stearate 80 63 polyethylene gylcol stearate methyl ether tn 100 64 21-dotetracontene/benzoyl chloride 100 85 65 21-dotetracontene/sebacoyl chloride 100 66 C.sub.42-56 internal olefin/benzoyl chloride tn 92 67 * Control

From the above table it may be apparent that the novel technique of this invention permits attainment of unexpected results.

For example, in Example 43, presence in the base oil Fuel A of 0.04 parts per 100 parts of base oil, of first component I alone gives a rating of 100 when measured by The Enjay Programmed Fluidity Test supra, i.e., in the test time, 100 percent of the fuel passed through the orifice. (The original fuel oil would be rated at 0-20.). When the concentration of component I was 0.02 parts, the base oil failed the test, i.e., less than about 75 percent passed through the orifice. Testing of Fuel A with second component (B) alone at high concentrations (even up to 0.1 percent) does not give a pass rating. For example, the component of Example 64 gives an 0 rating in the test at 0.1 concentration when used alone.

Unexpectedly it is found (e.g., Example 47) that use of 0.04 parts total of first component I and second component gives a ratng of 98 -- i.e. although the total amount of active first component employed is the same as the concentration at which it failed in Example 43. The amount of oil pssing through the orifice in test time is 98 percent in contrast to less than 50 percent of Example 43. Therefore, although the second component is inactive alone, it does unexpectedly yield improved results.

Similarly, comparison of Control Example 43 with e.g., experimental Examples 49, 50, 56, 61, 63, etc. reveals that the flow properties may be substantially increased by practice of the instant invention. It has also been found, for example that use of lesser amounts (e.g., 0.01 parts total of first component and the second component of Example 50) yields a rating of 100 in The Enjay Programmed Fluidity Test. This indicates that improvement of at least fourfold is achieved.

It will be apparent that the specific nature of the various distillate fuels may vary widely in terms of wax content, etc. and therefore in response to flow inprovers. It will be found that certain combinations of additives may be more effective in certain oils than other oils.

For example, the combination of first component (I) with second component (2) may be found, as noted in Table XIV to permit attainment of outstanding results in Fuel B (which is generally considered a difficultly responsive fuel) whereas the same combination in the same concentration may be found to give a lesser result when used in Fuel A (which is considered to be more "responsive" to flow improvers than is Fuel B).

In this instance, the novel invention permits attainment of improvement, the amount of improvement depending for example upon whether the oil is, e.g., a heating oil or a diesel oil. In the case of a heating oil, it may be found that the Fludiity Test is significant, whereas as with a diesel fuel, it may be found that a CFPP test is significant i.e., the determinative test for a given oil may depend upon whether the problems most frequently associated with the oil arise because the oil is to be passed through a small tube (as in the case of a heating oil) or through a screen (as in the case of a diesel oil).

It will be apparent that practice of this novel invention permits fullest realization of the flow improving properties of the first component pour depressant compositions. These compositions may be readily available or they may be prepared by desired techniques, which are known in the art.

While as previously indicated, it is only necessary that the oil-soluble flow-improving compound have a C.sub.10 to C.sub.30 straight-chain group and a bulky substituent as previously specified, particularly preferred are those compounds having a total of 12 to 200 carbon atoms, preferably 30-125 carbon atoms, which contains at least one of said C.sub.10 to C.sub.30 straight-chain groups and which include:

1. Alkyl aromatics including those having 1 to 4 alkyl groups each of which is a C.sub.1 -C.sub.30 alkyl and one of which is a C.sub.10 -C.sub.30 alkyl, per aromatic nucleus which can have 1 to 3 rings such as benzene, naphthalene, anthracene, etc.

2. Halohydrocarbons with 1 to 4 halogens per molecule, which hydrocarbons can be straight- or branched-chain, aliphatic, alkaryl, etc., including the alkyl aromatics of (1) supra and the acids of (3) infra.

3. Acids and their anhydrides, having 1 to 3 carboxylic groups, which may be aliphatic, aryl, alkaryl, cycloaliphatic groups, etc.

4. Esters such as those of acids such as (3) above and preferably of C.sub.2 to C.sub.26 fatty acids, preferably straight-chain and saturated, with alcohols having 1 to 6 hydroxy groups of which at least one hydroxy group has been esterified, and which alcohol contains one to 30 carbon atoms which may be straight- or branched-chain aliphatic, aryl, alkaryl, etc. Particularly, useful alcohols include the sorbitols, mannitols, etc., including their mono-dehydrated forms such as sorbitan, etc.

5. Polyethers or alkoxylated materials wherein 1 to 30 alkoxy groups of two to 26 carbon atoms such as ethylene oxide, propylene oxide, docosanyl alpha olefin oxide, are attached to another moiety, e.g. the acids of (3) above or the alcohols of (4), i.e., C.sub.1-30 alcohols with 1-6 hydrogen groups.

6. Unsaturated aliphatic hydrocarbons containing 1 to 4 ethylenically unsaturated bonds.

7. Derivatized compounds of (6) above wherein a further reaction is carried out at 1 or more of said unsaturated bonds including:

a. Acylation with acyl halides wherein the unsaturated aliphatic hydrocarbon of (6) is reached with 1 to 4 moles of an acyl halide ##SPC8## wherein R is a C.sub.1 to C.sub.20 hydrocarbon group, including straight- or branched-chain aliphatics, aromatics, alkyl aromatics, etc.

b. Halogenation or hydrohalogenation particularly chlorination and bromination, to yield derivatives of the above wherein the halogen or hydrogen halide, e.g., HCl, is added to at least one of the ethylenically unsaturated double bonds. (8) A saturated C.sub.10-26 alkanol derivative, e.g. esters of acids of (3); and polyethers of the alkoxy materials of (5).

Generally speaking, the polymeric pour depressant, i.e., the first component, is relatively expensive while the second component may be less expensive. As previously shown, the combination of the first and second component frequently gives a performance advantage, particularly in fuel oils which normally give a poor response to the polymeric pour depressant per se. In addition, the combination also frequently will give an economic advantage, even in oils which are very responsive to the polymeric flow improver, by simply permitting the substitution of a part of the expensive polymeric first component with less expensive second component while still obtaining the desired performance.

In addition, yet another advantage is obtained by simply placing another tool in the hands of the additive formulator for tailoring the additive composition to obtain the optimum, economic performance for a particular fuel oil, or class of fuel oils.

Although this invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made which clearly fall within the scope of this invention.

Claims

What is claimed is:

1. A fuel oil composition comprising

a. a major portion of a middle distillate fuel boiling in the range 250-750.degree.F. and a flow improving amount of a flow-improving system containing:

b. as a first component, in the range of about 0.005 to 0.3 parts, per 100 parts of oil, of an oil-soluble, pour point depressant polymer having a molecular weight M.sub.n in the range of about 500-50,000 selected from the group consisting of:

1. chlorinated ethylene polymer,

2. copolymer comprising 3-40 molar proportions of ethylene and a molar proportion of a copolymerizable comonomer selected from the group consisting of:

i. a vinyl ester of a C.sub.1-17 monocarboxylic acid, and

ii. an ethylenically unsaturated ester ##SPC9##

wherein X is H, or C.sub.1 to C.sub.8 alkyl and Y is --COOR wherein R is a C.sub.1-16 alkyl group, and

c. as a second component, in the range of about 0.005 to 0.3 parts, per 100 parts of oil, of a non-nitrogen-containing oil-soluble auxiliary flow-improving compound having a total of 12 to 200 carbon atoms, containing at least one straight chain (CH.sub.2).sub.n polymethylene segment wherein n is 10-30 and a bulky substituent on said polymethylene segment, said compound being selected from the group consisting of:

1. alkyl aromatics having 1 to 4 alkyl groups, each in the C.sub.1 to C.sub.30 range, per aromatic nucleus,

2. halogenated hydrocarbons having 1 to 4 halogens per molecule,

3. acids and their anhydrides having 1 to 3 carboxylic groups,

4. esters of C.sub.2 to C.sub.26 fatty acids with C.sub.1 to C.sub.30 alcohols having 1 to 6 hydroxy groups wherein at least one hydroxy group has been esterified,

5. polyethers containing 1 to 30 alkoxy groups of two to 26 carbon atoms attached to said acids of (3) above or to said C.sub.1 to C.sub.30 alcohol of (4) above,

6. unsaturated aliphatic hydrocarbons containing 1 to 4 ethylenically unsaturated bonds,

7. derivatized compounds of (6) above wherein a further reaction at one or more of said unsaturated bonds is carried out by:

a. acylation with 1 to 4 moles of acyl halide of the formula: ##SPC10##

where R is a C.sub.1 to C.sub.20 hydrocarbon group, and

b. halogenation and hydrodehalogenation,

8. saturated C.sub.10 to C.sub.26 alkanol esters of said acids of (3), and

9. polyethers of the alkoxy materials of (5).

2. A fuel oil composition according to claim 1, wherein said first component is chlorinated polyethylene containing about 10 to 30 percent chlorine and having a M.sub.n in the range of about 1500 to 15,000.

3. A fuel oil composition according to claim 1, wherein said first component is said copolymer comprising ethylene and vinyl ester of said monocarboxylic acid.

4. A fuel oil composition according to claim 3, wherein said vinyl ester is a vinyl ester of a C.sub.2 to C.sub.9 monocarboxylic acid.

5. A fuel oil composition according to claim 4, wherein said ester is vinyl acetate.

6. A fuel oil composition according to claim 1, wherein said first component is said copolymer of ethylene and said ethylenically unsaturated ester.

7. A fuel oil composition according to claim 6, wherein said first component is said copolymer comprising ethylene and alkyl acrylate wherein said alkyl group contains two to eight carbon atoms.

8. A fuel oil composition according to claim 7, wherein said ester is a copolymer comprising ethylene and isobutyl acrylate having a molecular weight in the range of about 1,500 to 15,000.

9. A fuel oil composition according to claim 1, wherein said second component is an alkyl aromatic having from 1 to 4 alkyl groups, each in the C.sub.1 to C.sub.30 range, per aromatic nucleus.

10. A fuel oil composition according to claim 1, wherein said second component is a halogenated hydrocarbon having 1 to 4 halogens per molecule.

11. A fuel oil composition according to claim 1, wherein said second component is an acid or anhydride having 1 to 3 carboxylic groups.

12. A fuel oil composition according to claim 1, wherein said second component is an ester of C.sub.2 to C.sub.26 fatty acid with C.sub.1 to C.sub.30 alcohol having 1 to 6 hydroxy groups wherein at least one hydroxy group has been esterified.

13. A fuel oil composition according to claim 1, wherein said second component is polyether.

14. A fuel oil composition according to claim 1, wherein said second component is an unsaturated aliphatic hydrocarbon containing 1 to 4 ethylenically unsaturated bonds.

15. A fuel oil composition according to claim 1, wherein said second component is one of said derivatized compounds.

16. A fuel oil composition according to claim 1, wherein said second component is a C.sub.10 to C.sub.26 alkanol ester of an acid or anhydride having 1 to 3 carboxylic groups.

17. A fuel oil according to claim 1, wherein said first component is said polymer of 3 to 40 moles of ethylene and said copolymerizable monomer and said second component is an ester of C.sub.2 to C.sub.26 fatty acid with C.sub.1 to C.sub.30 alcohol having 1 to 6 hydroxy groups wherein at least one hydroxy group has been esterified.

18. A fuel oil according to claim 17, wherein said copolymerizable monomer is either vinyl acetate or isobutyl acrylate, and said second component is alkoxylated with 1 to 30 alkoxy groups selected from the group consisting of ethylene oxide and propylene oxide.

19. A fuel oil according to claim 18, wherein said second component is a sorbitan ester of stearic or palmitic acid ethoxylated with ethylene oxide.

20. A composition adapted to be used as a flow improver comprising 0-100 parts of inert diluent-solvent and 10-70 parts of a mixture of:

a. as a first component, an oil-solible, pour point depressant polymer having a molecular weight M.sub.n in the range of about 500-50,000 selected from the group consisting of:

1. chlorinated ethylene polymer,

2. copolymer comprising 3-40 molar proportions of ethylene and a molar proportion of a copolymerizable comonomer selected from the group consisting of:

i. a vinyl ester of a C.sub.1-17 monocarboxylic acid, and

ii. an ethylenically unsaturated ester ##SPC11##

wherein X is H, or C.sub.1 to C.sub.8 alkyl and Y is --COOR wherein R is a C.sub.1-16 alkyl group, and

b. as a second component, a non-nitrogen-containing oil-soluble auxiliary flow-improving compound having a total of 12 to 200 carbon atoms, containing at least one striaght chain (CH.sub.2).sub.n polymethylene segment wherein n is 10-30 and a bulky substituent on said polymethylene segment, said compound being selected from the group consisting of:

1. alkyl aromatics having 1 to 4 alkyl groups, each in the C.sub.1 to C.sub.30 range, per aromatic nucleus,

2. halogenated hydrocarbons having 1 to 4 halogens per molecule,

3. acids and their anhydrides having 1 to 3 carboxylic groups,

4. esters of C.sub.2 to C.sub.26 fatty acids with C.sub.1 to C.sub.30 alcohols having 1 to 6 hydroxy groups wherein at least one hydroxy group has been esterified,

5. polyethers containing 1 to 30 alkoxy groups of two to 26 carbon atoms attached to said acids of (3) above or to said C.sub.1 to C.sub.30 alcohol of (4) above,

6. unsaturated aliphatic hydrocarbons containing 1 to 4 ethylenically unsaturated bonds,

7. derivatized compounds of (6) above wherein a further reaction at one or more of said unsaturated bonds is carried out by:

a. acylation with 1 to 4 moles of acyl halide of the formula: ##SPC12## where R is a C.sub.1 to C.sub.20 hydrocarbon group, and

b. halogenation and hydrodehalogenation,

8. saturated C.sub.10 to C.sub.26 alkanol esters of said acids of (3), and

9. polyethers of the alkoxy materials of (5), wherein said mixture contains about 4 to 97 percent of said first component with the remainder of said mixture being said second component.

21. A composition according to claim 20, wherein said first component is said polymer of 3 to 40 moles of ethylene and said copolymerizable monomer and said second component is an ester of C.sub.2 to C.sub.26 fatty acid with C.sub.1 to C.sub.30 alcohol having 1 to 6 hydroxy groups wherein at least one hydroxy group has been esterified.

22. A composition according to claim 21, wherein said copolymerizable monomer is either vinyl acetate or isobutyl acrylate, and said second component is alkoxylated with 1 to 30 alkoxy groups selected from the group consisting of ethylene oxide and propylene oxide.

23. A composition according to claim 22, wherein said second component is a sorbitan ester of stearic or palmitic acid ethoxylated with ethylene oxide.