CA2042855A1

CA2042855A1 - Composition for improving cold flow properties of middle distillates

Info

Publication number: CA2042855A1
Application number: CA002042855A
Authority: CA
Inventors: Nicholas Feldman; Jacob J. Habeeb
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1990-06-28
Filing date: 1991-05-17
Publication date: 1991-12-29
Also published as: JPH04226192A; FI913128A0; NO912367L; FI913128A; EP0465042A1; KR920000907A; NO912367D0

Abstract

ABSTRACT OF THE DISCLOSURE

A wax-containing middle distillate, such as diesel fuel, having improved low temperature flow properties comprises three or more components including (A) an oil-soluble ethylene backbone flow improving polymer such as ethylene vinyl acetate copolymer, (B) a hydrocarbyl substituted amine salt and/or amide of a carboxylic acid or anhydride such as phthalic anhydride salts, and (C) a hydrocarbyl substituted amine salt and/or amide of (I) a benzoic acid derivative such as the dihydrogenated tallow amine salt of an alkyl substituted dithiobenzoic acid or (II) a phosphoric acid derivative such as the dihydrogenated tallow amine salt of dialkyldithiophosphoric acid.

Description

~2~5 BACKGROUND OF THE INVENTION

Field of the Inventio_ This invention relates to an additive compo-sition for improving the cold flow properties of middle distillates such as diesel fuels and heating oils.
More particularly, the invention relates to a diesel fuel composition having improved cold flow properties imparted by an additive composition comprising three or more components including (A) an oil-soluble ethylene backbone flow improving polymer, (B) a hydrocarbyl substituted amine salt and/or amide of a carboxylic acid or anhydride and (C) a hydrocarbyl substituted am$ne salt and/or amide of a derivative of (I) a benzoic acid or (II) a phosphoric acid.

DescriPtion of the Prior Art Serious problems have been encountered by heating oils and diesel and jet fuels that are subject to low temperatures. These petroleum products are frequently subjected to low temperatures below their pour point, resulting either in distribution or operat-ing difficulties or both. For example, the distribu-tion of heating oils by pumping or siphoning is ren-dered difficult or impossible at temperatures around or below the pour point of the oil. Similarly, the flow of fuels at such low temperatures cannot be maintained through filters, leading to the failure of equipment to operate.

It is, of course, well known to add pour depressants to middle distillates, such as heating oils and diesel fuels, to improve their cold flow - 2 - ~a~2855 properties. For example, various polymers, useful as middle distillate pour point depressants, prepared from ethylene have been described in the patent literature.
These pour depressants include copolymers of ethylene and vinyl esters of lower fatty acids such as vinyl acetate (U.S. Patent No. 3,048,479); copolymers of ethylene and alkyl acrylate (Canadian Patent No.
676,875); terpolymers of ethylene with vinyl esters and alkyl fumarates (U.S. Patent Nos. 3,304,261 and 3,341,309); polymers of ethylene (British Patents Nos.
848,777 and 993,744); chlorinated polyethylene (Belgian Patent No. 707,371 and U.S. Patent No. 3,337,313): etc.

Polymers having alkyl groups in the range of C6 to Clg, such as homopolymers and copolymers of olefins, alkyl esters of unsaturated dicarboxylic acids (e.g., copolymers of dialkyl fumarate with vinyl acetate), and copolymers of olefins and said esters, are known in the art, principally as lube oil pour depressants and/or V.I. improvers. For example, U.S.
Patent No. 2,379,728 teaches olefin polymers as lube pour depressants; U.S. Patent No. 2,460,035 shows polyfumarates; U.S. Patent No. 2,936,30Q shows a copolymer of dialkyl fumarate and vinyl acetate; while U.S. Patent No~ 2,542,542 teaches copolymers of olefins, such as octadecene with maleic anhydride esterified with alcohol, e.g., lauryl alcohol, in lube and heating oils.

Combinations of various pour depressants and flow improvers for middle distillates are also well known. For example, U.S. Patent No. 4,153,422 describes a pour point depressing combination of ethylene vinyl ester copolymers with a polyester of a C14 to Cl6 substantially straight chained alkyl ester of an ethylenically unsaturated mono carboxylic acid.

h ~ 2 ~ ~ ~

U.K. Patent No. 1,469,016 teaches ethylene polymers or copolymers which are pour depressants for distillate fuels, in combination with a second polymer having alkyl groups of 6 to 18 carbon atoms, which is a polymer of an olefin or unsaturated dicarboxylic acid ester, useful in improving the cold flow properties of distillate fuel oils.

U.S. Patent No. 3,982,909 teaches nitrogen compounds such as amides, diamides, ammonium salts or monoesters of dicarboxylic acids, alone or in combina-tion with a hydrocarbon microcrystalline wax and/or a pour point depressant, particularly an ethylene back-bone polymeric pour point depressant, are wax crystal modifiers and cold flow improvers for middle distillate fuel oils, particularly diesel fuel.

U.S. Patent Nos. 3,444,082 and 3,846,093 teach various amides and salts of alkenyl succinic anhydride reacted with amines, in combination with ethylene copolymer pour point depressants, for distil-late fuels.

Middle distillate fuel oils containing three or more additives for improvement of cold flow proper-ties are also known. For example, U.S. Patent No.

4,211,534 discloses a three component additive combina-tion for distillate fuel oils comprising (A) an ethylene backbone distillate fuel oil pour depressant polymer, (B) a second polymer having alkyl side chains of 6 to 30 carbon atoms and derived from carboxylic acid ester or olefins, and (C) a nitrogen compound, e.g., amides and salts of a carboxylic acid or anhydride.

~2~

SUMMARY OF THE INVENTION

The present invention is based on the finding that the presence of the claimed three component system imparts improved flow properties to middle distillates as compared to the improvement imparted by equal or greater amounts of one or two of the components.

A wax-containing middle distillate having improved low temperature flow properties comprises three or more components including:

(A) 0.001 to 0.5 weight percent, preferably O.OOS - 0.10 weight percent, of an oil-soluble ethylene backbone flow improving polymer having a number average molecular weight in the range of about 500 to 50,000;

(B) 0.001 to 0.5 weight percent, preferably 0.01 - 0.20 weight percent, of an oil-soluble hydrocarbyl substituted amine salt and/or amide of a carboxylic acid or anhydride having 1 to 4 carbonyl groups;

(C) 0.001 to 0.5 weight percent, preferably 0.005 - 0.15 weight percent, of an oil-soluble hydrocarbyl substituted amine salt and/or amide, preferably an amine salt, of (I) a benzoic acid deriva-tive having the formula:

- s -R~ R2 I

wherein X is oxygen or sulfur, preferably sulfur, and R1, R2, R3, R4 and RS are selected from hydrogen; a hydrocarbyl group containing 1 to 24 carbon atoms, preferably an alkyl group containing 1 to 18 carbon atoms; a hydroxy group, i.e., -OH; and an oxygen-con-taining hydrocarbyl group containing 1 to 24 carbon atoms and at least one of the radicals R1, R2, R3, R4 or Rs is a hydrocarbyl, preferably an alkyl group, group containing 1 - 18 carbon atoms, most preferably 1-6 carbon atoms, or (II) a phosphoric acid derivative having the formula:

wherein X is oxygen or sulfur and R6 and R7 are selected from hydrogen and a hydrocarbyl group contain-ing 1 to 28 carbon atoms and at least one of the radicals R6 or R7 is a hydrocarbyl group containing 3 to 18 carbon atoms;

wherein the aforesaid weight percents are based on the weight of the total fuel composition.

2~2~5 DETAILED DESCRIPTION OF THE INVENTION

The First Component: the Ethylene Backbone Flow Improving Polymer.

The ethylene backbone polymers are of the type known in the art as wax crystal modifiers, e.g.
pour depressants and cold flow improvers for distillate fuel oils. These polymers will have a polymethylene backbone which is divided into segments by hydrocarbon or oxy-hydrocarbon side chains, or by alicyclic or heterocyclic structures or by chlorine atoms. They may be simply homopolymers of ethylene as prepared by free radical polymerization so as to result in some branch-ing. More usually, they will comprise about 3 to 40, preferably 4 to 20, molar proportions of ethylene per molar proportion of a second ethylenically unsaturated monomer, which latter monomer can be a single monomer or a mixture of such monomers in any proportion. These polymers will generally have a number average molecular weight in the range of about 500 to 50,000, preferably about 800 to about 20,000, e.g., 1000 to 6000, as measured for example by Vapor Pressure osmometry (VPO), such as using a Mechrolab Vapor Pressure Osmometer Model 302B.

The unsaturated monomers, copolymerizable with ethylene, include unsaturated mono and diesters of the general formula:

IRl l f =f wherein R1 is hydrogen or methyl; R2 is a --OOCR4 or --COOR4 group wherein R4 is hydrogen or a C1 to C28, 2 ~ 5 ~

more usually Cl to C16, and preferably a Cl to Cg, 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 Cl to C2g, more usually Cl to C17, mono-carboxylic acid, and preferably C2 to Cs monocarboxylic acid. Examples of such esters include vinyl acetate, vinyl isobutyrate, vinyl laurate, vinyl myristate, vinyl palmitate, etc. When R2 is --COOR4 and R3 is hydrogen, such esters include methyl acrylate, isobutyl acrylate, methyl methacrylate, etc. Examples of monomers where Rl is hydrogen and either or both of R2 and R3 are --COOR4 groups, include mono and diesters of unsaturated dicarboxylic acids such as: mono C13 Oxo fumarate, di-C13 Oxo fumarate, di-isopropyl maleate, di-lauryl fumarate, ethyl methyl fumarate, etc. It is preferred, however, that the acid groups be completely esterified as free acid groups tend to promote haze if moisture is present in the oil.

Another class of monomers that can be copolymerized with ethylene include C3 to C16 alpha monoolefins, which can be either branched or unbranched, such as propylene, isobutene, n-octene-l, isooctene-l, n-decene-l, dodecene-l, etc.

Vinyl acetate is particularly preferred as the monomer to be copolymerized with ethylene.

A further description of the ethylene back-bone polymer and methods for making such polymers are given in U.S. Patent No. 4,211,534 which is incorpo-rated herein by reference.

The Second Component: the Hydrocarbyl Substi-tuted Amine Salt and/or Amide of a Carboxylic Acid or Anhydride.

~42~

The second component includes oil-soluble amine salts and/or amides, which are known in the art and are generally formed by reaction of at least one molar proportion hydrocarbyl substituted amines with a molar proportion of hydrocarbyl acid having 1 to 4 carboxylic acid groups, or their anhydrides.

In the case of polycarboxylic acids, or anhydrides thereof, all acid groups may be converted to amine salts or amides, or part of the acid groups may be converted to esters by reaction with hydrocarbyl alcohols, or part of the acid groups may be left unreacted.

The hydrocarbyl groups of the preceding amine, carboxylic acid or anhydride, and alcohol compounds 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.g. hydroxy groups, carbonyl groups, ester groups, or oxygen, or sulfur, or chlorine atoms, etc. These hydrocarbyl groups will usually be long chain, e.g. C12 to C40, e.g. C14 to C24. However, some short chains, e.g. Cl to Cll may be included as long as the total numbers of carbons is sufficient for solubility. Thus, the resulting compound should contain a sufficient hydro-carbon 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 com-pound containing 8 to 40 e.g. 12 to 30 carbon atoms.
This straight chain alkyl segment may be in one or several of the amine or ammonium ion, or in the acid, or in the alcohol (if an ester group is also present).

~2~
At least one ammonium salt, or amine salt, or amide linkage is required to be present in the molecule.

The amines may be primary, secondary, ter-tiary or quaternary, 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 secon-dary 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 tertiary 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.

Amine mixtures may also be used and many amines derived from natural materials are mixtures.
Thus, coco amines derived from coconut oil 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 Clg straight chain alkyl groups. Tallow amine is particularly preferred.

Examples of the carboxylic acids or anhydrides, include formic, acetic, hexanoic, lauric, myristic, palmitic, hydroxy strearic, behenic, naphthenic, salicy~lic, acrylic, linoleic, dilinoleic, trilinoleic, maleic, maleic anhydride, fumaric, succinic, cuccinic anhydride, alkenyl succinic anhydride, adipic, glutaric, sebacic, lactic, malic, malonic, citraconic, phthalic acids (o, m, or p), e.g.

- lo - ~2~

terephthalic, phthalic anhydride, citric, gluconic, etc.

Phthalic anhydride amides or amine salts are particularly preferred as the second component of the additive composition of the invention.

The amides can be formed in a conventional manner by heating a primary or secondary amine with acid, or acid anhydride. The ammonium salts are also conventionally prepared by simply mixing the amine (or ammonium hydroxide) with the acid or acid anhydride, or the partial ester of a polycarboxylic acid, or partial amide of a polycarboxylic acid, with stirring, general-ly with mild heating (e.g. 70-80C).

The Third Component: (I) the Hydrocarbyl Substituted Amine Salt or Amide of a Benzoic Acid Derivative.

The benzoic acid derivative will have the formula:

C = X

Rl --~ - R2 R - ~ - R4 I

wherein X is oxygen or sulfur, preferably sulfur, and Rl, R2, R3, R4 and RS are selected from hydrogen; a hydrocarbyl group containing 1 to 24 carbon atoms, preferably an alkyl group containing 1 to 18 carbon atoms; a hydroxy group, i.e., -OH; and an oxygen-con-taining hydrocarbyl group containing 1 to 18 carbon atoms and at least one of the radicals Rl, R2, R3, R4 or Rs is a hydrocarbyl, preferably an alkyl group, group containing 1 - 18 carbon atoms, most preferably 1-6 carbon atoms.

Specific examples of the benzoic acid deriva-tive include 4-hydroxy 3,5 ditertiary butyl dithio-benzoic acid; 4-hydroxy 3,5 ditertiary butyl benzoic acid; 3,5 dimethyl dithiobenzoic acid; 4-hydroxy 3,5 dimethyl dithiobenzoic acid and the like.

Component (I) is formed in a conventional manner by mixing substantially equimolar amounts of the benzoic acid derivative and a hydrocarbyl substi-tuted amine at temperatures generally in the range of 20 - 100C. The hydrocarbyl substituted amines include those described with respect to the preparation of the aforedescribed second component. The preferred amines include the long straight chain alkyl amines containing 8 - 40, preferably 12 to 24, 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 Clg.
Another example is di tallow amine, derived from hydrogenated tallow acids, which amine is a mixture of C14 to C1g straight chain alkyl groups. Di tallow amine is particularly preferred.

The Third Component: (II) the Hydrocarbyl Substituted Amine Salt of a Phosphoric Acid Derivative.

The phosphoric acid derivative will have the formula:

- 12 - ~ ~ ~2~

wherein X is oxygen or sulfur, preferably sulfur, and R1 and R2 are selected from hydrogen and a hydrocarbyl group containing 1 to 28 carbon atoms, preferably an alkyl group containing 4 to 12 carbon atoms, and at least one of the radicals Rl or R2 is a hydrocarbyl, preferably an alkyl group, group containing 3 - 18 carbon atoms.

Specific examples of the phosphoric acid derivative include dioctyldithiophosphoric acid;
dihexyldithiophosphoric acid; dibutyldithiophosphoric acid; didodecylphenyldithiophosphoric acid; dioctyl-phosphoric acid; butylhexyldithiophosphoric acid;
butyloctyldithiophosphoric acid; and the like.

Component (II3 is formed in a conventional manner by mixing substantially equimolar amounts of the phosphoric acid derivative and a hydrocarbyl substi-tuted amine at temperatures generally in the range of 15 ~ 100 r C~ The hydrocarbyl substituted amines include those described with respect to the preparation of the aforedescri~ed second component. The preferred amines include the long straight chain alkyl amines containing 8 - 40, preferably 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 hydroge-nated tallow acids, which amine is a mixture of C14 to C18 straight chain alkyl groups. Tallow amine is particularly preferred.

~2~5 The Middle Distillate Oil.

The middle distillates will generally boil within the range of about 120C to about 500C., e.g.
150 to about 400C. The fuel oil can comprise atmo-spheric distillate or vacuum distillate, or cracked gas oil or a blend in any proportion of straight run and thermally and/or catalytically cracked distillates, etc. The most common petroleum distillate fuels are kerosene, jet fuels, diesel fuels and heating oils.
The heating oil may be a straight atmospheric distil-late, or it may frequently contain minor amounts, e.g.
0 to 35 wt.%, of vacuum gas oil and/or of cracked gas oils. The low temperature flow problem is most usually encountered with diesel fuels and with heating oils.

Oil soluble, as used herein, means that the additives are soluble in the fuel at ambient tempera-tures, e.g., at least to the extent of about 0.1 wt.%
additive in the fuel oil at 25C, although at least some of the additive comes out of solution near the cloud point in order to modify the wax crysta}s that form.

The additive combination of this invention may be dissolved in a suitable solvent for ease in handling, as is conventional practice. The additive concentrate may comprise from about 30 to 80 wt% of a suitable diluent, such as a hydrocarbon diluent, and about 70 to 20 wt% of an additive combination compris-ing:

(A) one part by weight of an oil-soluble ethylene backbone distillate flow improving polymer having a number average molecular weight in the range of about 500 to 50,000;

- 14 - 2~2~

(B) 0.10 to 10 parts by weight of an oil soluble hydrocarbyl substituted amine salt or amide of a carboxylic acid or anhydride; and (C) 0.10 to 10 parts by weight of an oil-soluble hydrocarbyl substituted amine salt or amide of (I) a benzoic acid derivative having the formula:

C = X
Rl --~ - R2 R - ~ - R4 I

wherein X is oxygen or sulfur, and R1, R2, R3, R4 and Rs are selected from hydrogen; a hydrocarbyl group containing 1 to 24 carbon atoms; a hydroxy group, and an oxygen-containing hydrocarbyl group containing 1 to 24 carbon atoms and at least one of the radicals R1, R2, R3, R4 or R5 is a hydrocarbyl group containing 1 24 carbon atoms, or (II) a phosphoric acid derivative having the formula:

wherein X is oxygen or sulfur and R6 and R7 are selected from hydrogen and a hydrocarbyl group contain-ing 1 to 28 carbon atoms and at least one of the radicals R1 or R2 is a hydrocarbyl group containing 3 to 18 carbon atoms.

The invention will be further understood by reference to the following Examples which include preferred embodiments of the invention.

In this Example, the flow improvement impart-ed by the three component additive composition of the invention is compared to the flow improvement imparted by equal or greater amounts of an additive composition containing only the first two components of the addi-tive composition of the invention.

The oil-soluble ethylene backbone polymer used in this Example is an ethylene-vinyl acetate copolymer containing about 38 wt.% vinyl acetate and having a number average molecular weight of about 1800 (VPo). The copolymer was prepared in accordance with the teachings of U.S. Patent No. 3,916,916 which is incorporated herein by reference. This copolymer is hereinafter referred to as Additive A.

The second component used in this Example was a dihydrogenated tallow amine salt of the monoamide of phthalic anhydride hereinafter referred to as Additive B. This material was conventionally prepared ky reacting stoichiometric amounts of phthalic anhydride with the amine.

The third component used in this Example was a dihydrogenated tallow amine salt of 4-hydroxy 3,5 ditertiary butyl dithiobenzoic acid hereinafter referred to as Additive CI. This material was prepared as follows.

A tallow amine solution was prepared by dissolving 26 grams of dihydrogenated tallow amine sold under the tradename Armeen 2HT in 260 ml. of toluene.
A solution of 14 grams of 4-hydroxy ~,5 ditertiarybutyl dithiobenzoic acid in 150 ml toluene was then slowly added with constant stirring at room temperature to the tallow solution. Upon completion of the addition, the mixture was stirred for about 60 minutes and the toluene was then boiled off under low heat (about 50C) under a nitrogen stream to isolate the product.

The middle distillate tested in this Example is a diesel fuel having a -5C ASTM cloud point, and a -12C ASTM pour point.

Various amounts of Additives A, B and C were blended in the diesel fuel and tested for flow improve-ment in the ASTM D-4539 Low Temperature Flow Test (LTFT). In this test, the fuel is cooled at 1C per hour to the test temperature to determine the lowest temperature at which the fuel will flow through a suction tube having a filter screen. The results obtained are shown in the following Table I.

Table I

Lowest Pass Weight % Additive (100% Active Temperature C
Ingredient) in Diesel Fuel in LTFT

Additive A Additive B Additive CI

0.015 0.040 - -13 0.025 0.030 - -13 0.010 0.025 0.010 -16 0.009 0.024 0.017 -19 It can be seen from the data in Table I that lower flow temperatures are obtained at lower total additive concentrations when all three additives are used as compared to higher concentrations of Additives A and B.

EXAMPLE II

Additives A, B and CI were tested in another diesel fuel. The fuel had a -7C ASTM cloud point, and a 15C ASTM pour point.

The LTFT results from this test are shown in Table II.
It is seen that the presence of all three components imparts a greater flow improvement than an equal concentration of Additives A and B.

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Table II

Lowest Pass Weight % Additive (100% Active Temperature ~C
Ingredient) in Diesel Fuel in LTFT
Addi~ive A Additive B Additive CI

0.012 0.020 - -15 0.006 0.016 0.010 -22 EXAMPLE III

Additives A, B and CI were tested in another diesel fuel. The fuel had a -8C ASTM cloud point, and a -15-C ASTM pour point.

The LTFT results for this Example are shown in the following Table III.

Table III

Lowest Pass Weight % Additive (100% Active Temperature C
Inaredient) in Diesel Fuel in LTFT _ Additive A Additive B Additive CI

0.015 0.030 - -17 0.007 0.015 0.010 -23 - 19 - ~ g5~

EXAMPLE IV

In this Example, Additives A and B were blended with a dihydrogenated tallow amine salt of 4-hydroxy, 3,5-ditertiarybutyl benzoic acid in the diesel fuel of Example I. The amine salt of the benzoic acid derivative was prepared as follows.

A tallow amine solution was prepared by dissolving 41.5 grams of dihydrogenated tallow amine sold under the tradename Armeen 2HT in 400 ml. of toluene. A solution of 20 grams of 4-hydroxy 3,5 ditertiarybutyl benzoic acid in 500 ml. of toluene was then slowly added with constant stirring at room temperature to the tallow amine solution. Upon comple-tion of the addition, the mixture was stirred for about 20 minutes and the toluene was then boiled off under low heat (about 50C) under a nitrogen stream to isolate the product.

This material is designated as Additive DI. The LTFT
results for this Example which are shown in t~e follow-ing Table IV demonstrate the effectiveness of the three components compared to greater amounts of Additives A
and B.

J ~

Table IV

Lowest Pass Weight % Additive (100% Active Temperature C
Inqredient) in Diesel Fuel in LTFT

Addi~ive_~ Additive B Additive DI

0.015 0.040 - -13 0.025 0.030 - -13 0.009 0.024 0.017 -17 EXAMPLE V

In this Example, Additives A, B and DI of Example IV were tested in the diesel fuel described in Example II. The LTFT results for this Example which are shown in the following Table V.

Table V

Lowest Pass Weight % Additive (100% Active Temperature 'C
Ingredient) in Diesel Fuel in LTFT

Additive A Additive B Additive DI

0.012 0.020 - -15 0.006 0.016 0.010 -22 ~2~5~

EXAMPLE VI

In this Example, the flow improvement impart-ed by the three component additive composition of the invention is compared to the flow improvement imparted by equal or greater amounts of an additive composition containing only the first two components of the addi-tive composition of the invention.

The oil-soluble ethylene backbone polymer used in this Example is an ethylene-vinyl acetate copolymer containing about 38 wt.% vinyl acetate and having a number average molecular weight of about 1800 (VP0). The copolymer was prepared in accordance with the teachings of U.S. Patent No. 3,916,916 which is incorporated herein by reference. This copolymer is hereinafter referred to as Additive A.

The second component used in this Example was a dihydrogenated tallow amine salt of the monoamide of phthalic anhydride hereinafter referred to as Additive B. This material was conventionally prepared by reacting stoichiometric amounts of phthalic anhydride with the amine.

The third component used in this Example was a dihydrogenated tallow amine salt of dioctyldithio-phosphoric acid hereinafter referred to as Additive CII. This material was prepared as follows.

A tallow amine solution was prepared by dissolving 51 grams of dihydrogenated tallow amine sold under the tradename Armeen 2HT in 600 ml. of toluene.
A solution of 35 grams of di n-octyl dithiophosphoric acid in 200 ml. of toluene was then slowly added with constant stirring at room temperature to the tallow - 22 - ~ ~2 amine solution. Upon completion of the addition, the mixture was stirred for about 60 minutes and the toluene was then boiled off under low heat (about 50 C) under a nitrogen stream to isolate the product.

The middle distillate tested in this Example is a diesel fuel having a +12F ASTM cloud point, a 0F
ASTM pour point, and Various amounts of Additives A, B and CII
were blended in the diesel fuel and tested for flow improvement in the ASTM D-4539 Low Temperature Flow Test (LTFT). In this test, the fuel is cooled at 1C
per hour to the test temperature to determine the lowest temperature at which the fuel will flow through a suction tube having a filter screen. The results obtained are shown in the following Table VI.

Table VI

Weight ~ Additive (100% Active Inqredient) in D~esel Fuel LTFT ~esults at F

Additive A Addi~ive B A~ditive CII +7 +5 Q -5 0.20 - - Fail Fail - 0.20 - Fail Fail 0.08 0.12 - Fail Fail - - 0.10 Pass Fail 0.03 0.045 0.03 Pass Pass Pass 0.03 0.045 0.02 Pass Pass Pass It can be seen from the data in Table VI that lower flow temperatures are obtained at lower total additive concentrations when all three additives are ~42~5 used as compared to higher concentrations of Additives A and/or B.

EXAMPLE VII

Additives A, B and CII were tested in another diesel fuel. The fuel had a -5C ASTM cloud point, a -12-C ASTM pour point, a The LTFT results from this test are shown in Table VII.
It is ceen that the presence of all three components imparts a greater flow improvement than an equal concentration of Additives A and B.

Table VII

Lowest Pass Weight % Additive (100~ Active Temperature CC
Inaredient) in Diesel Fuel in LTFT

Additive A Additive B Additive CII

0.015 0.045 - -13 0.012 0.048 - -12 0.030 0.030 - -13 0.012 0.030 0.018 -20

Claims

1. A wax-containing middle distillate fuel composition having improved low temperature flow properties comprising three or more components includ-ing:

(A) about 0.001 to 0.5 wt.% of an oil-soluble ethylene backbone distillate flow improving polymer having a number average molecular weight in the range of about 500 to 50,000;

(B) about 0.001 to 0.5 wt.% of an oil-soluble hydrocarbyl substituted amine salt or amide of a carboxylic acid or anhydride; and (C) about 0.001 to 0.5 wt.% of an oil-soluble hydrocarbyl substituted amine salt or amide of (I) a benzoic acid derivative having the formula:

wherein X is oxygen or sulfur, and R1, R2, R3, R4 and R5 are selected from hydrogen; a hydrocarbyl group containing 1 to 24 carbon atoms; a hydroxy group, and an oxygen-containing hydrocarbyl group containing 1 to 24 carbon atoms and at least one of the radicals R1, R2, R3, R4 or R5 is a hydrocarbyl group containing 1 -24 carbon atoms, or (II) a phosphoric acid derivative having the formula:

wherein X is oxygen or sulfur and R6 and R7 are selected from hydrogen and a hydrocarbyl group contain-ing 1 to 28 carbon atoms and at least one of the radicals R6 or R7 is a hydrocarbyl group containing 3 to 18 carbon atoms;

wherein the aforesaid weight percents are based on the weight of the total fuel composition.

2. The middle distillate fuel of claim 1 wherein said fuel is a diesel fuel.

3. The middle distillate fuel of claim 2 wherein additive (C) is an amine salt.

4. The middle distillate fuel of claim 3 wherein the hydrocarbyl substituted amine used in the preparation of additives B and C comprises at least one straight chain alkyl group containing 8 to 40 carbon atoms.

5. The middle distillate fuel of claim 3 wherein at least one of the radicals R1, R2, R3, R4 or R5 is a hydrocarbyl radical containing 1 - 18 carbon atoms.

6. The middle distillate fuel of claim 5 wherein the oil-soluble ethylene backbone distillate flow improving polymer is a copolymer of ethylene and vinyl acetate.

7. The middle distillate fuel of claim 6 wherein X in the formula for the benzoic acid deriva-tive represents sulfur.

8. The middle distillate fuel of claim 7 wherein additive (B) is an amine salt or amide of phthalic anhydride.

9. The middle distillate fuel of claim 8 wherein at least one of the radicals R1, R2, R3, R4 or R5 is an alkyl group containing 1 - 6 carbon atoms.

10. The middle distillate fuel of claim 6 wherein X in the formula for the phosphoric acid derivative represents sulfur.

11. The middle distillate fuel of claim 10 wherein at least one of the radicals R6 or R7 is a hydrocarbyl radical containing 3 - 18 carbon atoms.

12. The middle distillate fuel of claim 6 wherein the hydrocarbyl substituted amine used in the preparation of additive (C) is tallow amine.

13. The middle distillate fuel of claim 1 wherein said fuel is a diesel fuel, said additive (A) is an ethylene vinyl acetate copolymer, and said additive (B) is a phthalic anhydride amide or amine salt.

14. The middle distillate fuel of claim 13 wherein additive (C) is a dihydrogenated tallow amine salt.

15. The middle distillate fuel of claim 1 wherein additive (A) is an ethylene vinyl acetate copolymer, additive (B) is a tallow amine salt of phthalic anhydride and additive (C) is a tallow amine salt of an alkyl substituted (I) dithiobenzoic acid or (II) dithiophosphoric acid.

16. A wax-containing diesel fuel containing an additive mixture comprising:

(A) 0.005 - 0.10 wt% of an oil-soluble copolymer of ethylene and vinyl acetate;

(B) 0.01 - 0.20 wt% of an oil-soluble amine salt or amide of phthalic anhydride; and (C) 0.005 - 0.15 wt% of an oil-soluble C12 -C30 alkyl amine salt of a benzoic acid derivative having the formula:

wherein X is oxygen or sulfur and R1, R2, R3, R4 and R5 are selected from hydrogen, -OH and an alkyl group containing 1 - 18 carbon atoms, and at least one of the radicals R1, R2, R3, R4 or R5 is an alkyl group con-taining 1 - 6 carbon atoms; wherein the aforesaid weight percents are based on the weight of the total fuel composition.

17. The diesel fuel of claim 16 wherein X
represents sulfur and R1, R2, R3, R4 and R5 are select-ed from hydrogen, -OH, and an alkyl group containing 1 - 6 carbon atoms and at least one of the radicals R1, R2, R3, R4 or R5 is an alkyl group containing 1 - 6 carbon atoms.

18. The diesel fuel of claim 17 wherein additives (B) and (C) are tallow amine salts.

19. The diesel fuel of claim 18 wherein the benzoic acid derivative is 4-hydroxy, 3,5 ditertiary-butyl dithiobenzoic acid.

20. A wax-containing diesel fuel containing an additive mixture comprising:

(A) 0.005 - 0.10 wt% of an oil-soluble copolymer of ethylene and vinyl acetate;

(B) 0.01 - 0.15 wt% of an oil-soluble amine salt or amide of phthalic anhydride; and (C) 0.005 - 0.10 wt% of an oil-soluble C12 -C30 alkyl amine salt of a compound having the formula:

wherein X is oxygen or sulfur and R1 and R2 are selected from hydrogen and an alkyl group containing 4 to 12 carbon atoms, and at least one of the radicals Rl or R2 is an alkyl group containing 4 to 12 carbon atoms; wherein the aforesaid weight percents are based on the weight of the total fuel composition.

21. The diesel fuel of claim 20 wherein X
represents sulfur and R1 and R2 are C4 - C12 alkyl groups.

22. The diesel fuel of claim 21 wherein additives (B) and (C) are tallow amine salts.

23. An additive combination comprising:

(A) one part by weight of an oil-soluble ethylene backbone distillate flow improving polymer having a number average molecular weight in the range of about 500 to 50,000;

(B) 0.10 to 10 parts by weight of an oil soluble hydrocarbyl substituted amine salt or amide of a carboxylic acid or anhydride; and (C) 0.10 to 10 parts by weight of an oil-soluble hydrocarbyl substituted amine salt or amide of (I) a benzoic acid derivative having the formula:

wherein X is oxygen or sulfur, and R1, R2, R3, R4 and R5 are selected from hydrogen; a hydrocarbyl group containing 1 to 24 carbon atoms; a hydroxy group, and an oxygen-containing hydrocarbyl group containing 1 to

24 carbon atoms and at least one of the radicals R1, R2, R3, R4 or R5 is a hydrocarbyl group containing 1 -18 carbon atoms, or (II) a phosphoric acid derivative having the formula:

wherein X is oxygen or sulfur and R6 and R7 are selected from hydrogen and a hydrocarbyl group contain-ing 1 to 28 carbon atoms and at least one of the radicals R6 or R7 is a hydrocarbyl group containing 3 to 18 carbon atoms.

24. An additive concentrate comprising from about 30 to 80 wt% of a hydrocarbon diluent and from about 70 to 20 wt% of the additive combination of claim 23.