EP0343981A1

EP0343981A1 - Fuel oil compositions

Info

Publication number: EP0343981A1
Application number: EP89305290A
Authority: EP
Inventors: Robert Dryden Tack; Iain More; Kenneth Lewtas
Original assignee: Exxon Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 1988-05-25
Filing date: 1989-05-25
Publication date: 1989-11-29
Anticipated expiration: 2009-05-25
Also published as: GB8812380D0; EP0343981B1; JP2723972B2; CN1024680C; CN1038298A; DE68919907T3; EP0343981B2; DE68919907T2; KR960013611B1; JPH0224394A; KR900018339A; DE68919907D1

Abstract

A fuel composition comprising a major proportion by weight of a liquid hydrocarbon fuel and a minor proportion by weight of a polymer containing more than one amino group, this amino group being a salt of a primary, secondary or tertiary amine or a quaternary ammonium salt, for example an amine salt of a copolymer of an alkyl fumarate, vinyl acetate and maleic anhydride.

Description

This invention relates to fuel oil compositions containing a flow improver.
Wax separation in crude oils, middle distillate fuels, heavy and residual fuels and lubricating oils limits their flow at low temperatures. The usual method of overcoming these problems is to add wax crystal modifying compounds that cause the wax crystals to be smaller (nucleators) and/or to be smaller and to grow into more compact shapes (growth inhibitors).
Another difficulty is that small wax crystals can stick together and form larger agglomerates and these agglomerates as well as the individual crystals can block the filter screens through which the individual crystals would pass and they will settle more rapidly than do the individual, small crystals.
We have now found that the wax crystals may be modified so as to improve filterability and reduce the pour point and the tendency of the wax crystals to agglomerate may be reduced by the addition of certain amino or quaternary ammonium salts.
According to this invention fuel compositions comprise a major proportion by weight of a liquid hydrocarbon fuel and a minor proportion by weight of a polymer containing more than one amino group, this amino group being a salt of a primary, secondary or tertiary amine or a quaternary ammonium salt. Also according to this invention polymers containing more than one amine group, this amino group being a salt of a primary, secondary or tertiary amine or a quaternary ammonium salt are used as a flow improver in a liquid hydrocarbon fuel.
The liquid hydrocarbon fuel oils can be distillate fuel oils, such as the middle distillate fuel oils, e.g. a diesel fuel, aviation fuel, kerosene, fuel oil, jet fuel, heating oil, etc. Generally, suitable distillate fuels are those boiling in the range of 120^oC to 500^oC (ASTM D86), preferably those boiling in the range 150^oC to 400^oC. A representative heating oil specification calls for a 10 percent distillation point no higher than about 226^oC, a 50 percent point no higher than about 272^oC and a 90 percent point of at least 282^oC and no higher than about 338^oC to 343^oC, although some specifications set the 90 percent point as high as 357^oC. Heating oils are preferably made of a blend of virgin distillate, e.g. gas oil, naphtha, etc. and cracked distillates, e.g. catalytic cycle stock.
The polymer containing more than one amino group can be prepared by reacting a polymer having a plurality of carboxylic acid or anhydride groups with a primary, secondary or tertiary amine.
To prepare the quaternary ammonium salts the polymers can be reacted with a tetra-hydrocarbyl ammonium halide. Alternatively, they may be prepared by reaction of a tertiary amine with a hydrocarbyl halide and so the polymer from which the desired polymer is derived should have halide groups and be reacted respectively with a tertiary amine.
There are many different types of polymer which can be further reacted to produce the desired polymer containing two or more amine salt groups.
(I) Examples are polymers of one or more unsaturated monomers including ester and free acid groups and copolymers of unsaturated ester monomers, at least one of which monomers also has a free acid group. Specific examples are copolymers of a dialkyl fumarate, maleate, citraconate or itaconate, copolymers of vinyl acetate with a monoalkyl fumarate, maleate, citraconate or itaconate, copolymers of an alkyl acrylate or an alkyl methacrylate with a monoalkyl fumarate, maleate, citraconate or itaconate and copolymers of a dialkyl fumarate, maleate, citraconate or itaconate with a monoalkyl fumarate and with vinyl acetate.
Particularly suitable examples of type I polymers are a copolymer of vinyl acetate and a monoalkyl fumarate and a dialkyl fumarate where the alkyl groups are 1:1 mixtures of dodecyl and tetra decyl and copolymers of vinyl acetate and either mono dodecyl, mono tetra decyl or mono hexadecyl fumarate.
(II) Other examples are copolymers of an unsaturated ester and/or an olefin with an unsaturated carboxylic anhydride. These copolymers on reaction with a primary or secondary amine can give half amide/half amine salts due to reaction with the anhydride group. Specific examples are copolymers (a) of a dialkyl fumarate, maleate, citraconate or itaconate with maleic anhydride, or (b) of vinyl esters, e.g. vinyl acetate or vinyl stearate with maleic anhydride, or (c) of a dialkyl fumarate, maleate, citraconate or itaconate with maleic anhydride and vinyl acetate. Other examples are copolymers of maleic anhydride with styrene or with an aliphatic olefin, for example a C₁₀ to C₃₀ olefin, such as decene, dodecene, tetradecene, hexadecene, eicosene, docosene, tetracosene, octacosene, propylene tetramer or propylene hexamer.
Particularly suitable examples of Type II polymers are copolymers of didodecyl fumarate, vinyl acetate and maleic anhydride; di-tetradecyl fumarate, vinyl acetate and maleic anhydride, dihexadecyl fumarate, vinyl acetate and maleic anhydride; or the equivalent copolymers where instead of the fumarate the itaconate is used.
(III) The desired polymers may alternatively be prepared by partial hydrolysis of a polymer containing ester groups to obtain carboxylic acid or anhydride groups. Thereafter the partially hydrolysed polymer is reacted with an amine to produce the desired polymer containing two or more amine salt groups. Thus, one may partially hydrolyse polymers of acrylates, methacrylates, alkyl fumarates, alkyl maleates or copolymers thereof or copolymers thereof with an olefin.
Particularly suitable examples of Type III polymers are partially hydrolysed polymers of alkyl acrylates or methacrylates, e.g. dodecyl acrylate, tetradecyl acrylate or hexadecyl acrylate.
(IV) Suitable polymers are also polymers of unsaturated carboxylic acids, for example polyacrylic acid or polymethacrylic acid, copolymers of acrylic acid with an olefin, e.g. ethylene or an alkyl fumarate; and copolymers of methacrylic acid with an olefin, e.g. ethylene, or an alkyl fumarate.
In all the above mentioned types of suitable polymer (I, II, III and IV) the desired amine salt is obtained by reacting the polymer containing carboxylic acid or anhydride groups with a primary-, secondary- or tertiary amine to obtain the corresponding amine salt, (optionally also with a alcohol whence an ester-amine salt is formed). Very often, for example when reacting polymers containing an anhydride group, the resulting amino groups will be amine salts and amides. Such polymers can be used, provided that they contain at least two amine salt groups.
To prepare a quaternary ammonium salt any of the above described polymers (I, II, III or IV) are reacted with a tetra hydrocarbyl ammonium halide or the polymers are converted so that they contain halide groups instead of carboxylic acid groups or they are formed by polymerising with an unsaturated halide, for example vinyl chloride. They would then be reacted with a tertiary amine so as to form the quaternary ammonium salt.
(V) Other suitable polymers are obtained by partial hydrolysis of polymers of unsaturated esters followed by reaction with a carboxylic anhydride which is thereafter reacted with a p-, s- or t-amine to form the desired amine salt. Suitable polymers of unsaturated esters are homo polymers of acrylates, methacrylates, alkyl fumarates or copolymers thereof with an olefin, for example ethylene or a copolymer of vinyl acetate with an olefin. A specific example is an ethylene-vinyl acetate copolymer. After partial hydrolysis the polymer is reacted with an acid anhydride, e.g. succinic or maleic anhydride and the resulting product can be reacted with a p-, s- or t-amine to obtain the corresponding amine salt, or with a tetrahydrocarbyl ammonium halide to obtain the corresponding quaternary ammonium salt.
Although it is not essential it is highly desirable that the polymer containing at least two amine salt or quaternary ammonium salt groups contains at least one hydrogen- and carbon-containing group where the total number of carbon atoms in said group(s) is at least 10 carbon atoms. More preferably there are 12 to 18 carbon atoms in at least one of said groups. Any such group which is preferably a straight chain or branched alkyl groups, can be present either attached directly or through a carboxylate group to the backbone of the polymer or attached to the nitrogen atom of the amine salt or quaternary ammonium salt group. The polymers may also contain such groups attached both to the nitrogen atom and to the backbone or to the carboxylate group. Thus in Type I, II, III and IV polymers the alkyl groups of the mono- and di-alkyl fumarate, of the alkyl acrylate or of the alkyl methacrylate from which the polymers are derived can contain at least 10 carbon atoms. Particularly suitable monomers are therefore di dodecyl fumarate, di tetra decyl fumarate, di octadecyl fumarate and the corresponding mono alkyl fumarates and mixtures thereof. Also dodecyl, tetradecyl, hexadecyl and octadecyl acrylates and methacrylates are particularly suitable. In type III polymers one could use for example di-decyl, di-dodecyl, di-tetradecyl maleates.
As an alternative or an addition one can introduce the long chain group into the polymer by using a long chain p-, s- or t-amine or tetrahydrocarbyl ammonium halide or mixtures thereof in forming the salt.
The amines can be represented by the formulae
R¹NH₂, R¹R²NH and R¹R²R³H
and the tetrahydrocarbyl ammonium halide by the formula
R¹R²R³R⁴NX
wherein R¹, R², R³, and R⁴ are hydrocarbyl groups, preferably alkyl groups and wherein at least one of R¹, R², R³ and R⁴ preferably contains at least 10 carbon atoms, for instance 12 to 18 carbon atoms, for example dodecyl, tetradecyl, hexadecyl and octadecyl and wherein X is halogen, preferably chlorine.
Suitable polyamines can be represented by the formulae H₂N[RHN]_xH and R¹NH[RNR¹]_xH where R¹ is a hydrocarbyl group, R is a divalent hydrocarbyl group, preferably alkylene or hydrocarbyl substituted alkylene and x is an integer.
Examples of suitable primary amines are hexyl amine, octyl amine, and those containing at least 10 carbon atoms, for instance decyl amine, tetradecyl amine, octadecyl amine, eicosylamine, the mixed amine RNH₂ (Armeen C) where R is 0.5 wt % C₆ alkyl, 8 wt % C₈ alkyl, 7 wt % C₁₀ alkyl, 50 wt % C₁₂ alkyl, 18 wt % C₁₄ alkyl, 8 wt % C₁₆ alkyl, 1.5 wt % C₁₈ alkyl and 7.0 wt % C₁₈/C₁₉ unsaturated.
Examples of suitable secondary amines are di-octyl amine, and those containing alkyl groups with at least 10 carbon atoms, for instance di-decyl amine, di-docyl amine, di-coco amine (i.e. di mixed C₁₂ to C₁₄ alkyl amines), di octadecyl amine, hexadecyl, octadecyl amine, dihydrogenated tallow amine (Armeen 2HT) (approx. 4 wt % nC₁₄ alky l, 30% nC₁₆ alkyl, 60 wt % C₁₈ alkyl, the rest unsaturated) n-coco-propyl di amine (C₁₂/C₁₄ alkyl-propyl di amine - Duomeen C), n-tallow-propyl diamine (C₁₆/C₁₈ alkyl propyl diamine - Duomeen T).
Examples of suitable tertiary amines are tri hexyl amine, tri octyl amine and those containing alkyl groups with at least 10 carbon atoms, for instance, hexyl di-decyl amine, tri decyl amine and tri hexadecyl amine.
Examples of suitable quaternary ammonium halides are tri-octyl-methyl ammonium chloride, and those containing alkyl groups with at least 10 carbon atoms, for instance tri-dodcyl-methyl ammonium chloride, tri-tetradecyl, dodecyl ammonium chloride and hexadecyl, dimethyl, phenyl amine.
Examples of suitable polyamines are N-octadecyl propane diamine; N′N′ dioctadecyl propane diamine, N tetradecyl butane diamine and N,N′ dihexadecyl hexane diamine.
The polymer salts of this invention usually have a number average molecular weight of 1,000 to 500,000, for example 10,000 to 100,000.
Particularly suitable examples of amino group-containing polymers for use in the present invention are:

(1) A copolymer of di-tetradecyl fumarate, vinyl acetate and maleic anhydride, (the mole ratio of acetate:fumarate:anhydride being approximately 50:45:5) reacted with di C₁₆/C₁₈ n-alkyl amine (C₁₆ alkyl/C₁₈ alkyl being approximately 1:2) to produce the half amide, half amine salt of the carboxylic acid groups mainly derived from the maleic anhydride units of the copolymer.
(2) A copolymer of 50.0 mole % vinyl acetate, 45.0 mole % di C₁₂/C₁₄ alkyl (1:1) fumarate and 5 mole % maleic anhydride reacted with 5 mole % trioctylamine to produce the half amide, half amine salt of the carboxylic acid groups derived from the maleic anhydride units of the copolymer.
(3) A copolymer as (2) above but formed by the reaction of 10 mole % of di-coco (C₁₂ to C₁₄ alkyl) amines instead of trioctylamine.
(4) A copolymer as (2) above but formed by the reaction of 5 mole % of trioctyl-methyl ammonium chloride and 5 mole % of sodium hydroxide in the minimum amount of water instead of trioctylamine. This results in the quaternary ammonium salt of the polymer.
(5) A copolymer as (1) above but formed by the reaction of a mixture of dodecylamine and tetradecylamine instead of the dialkylamine.
(6) A copolymer as (1) above but formed by the reaction of n-coco (C₁₂ to C₁₄ alkyl) propyl diamine instead of the dialkylamine.
(7) Copolymers as (1) to (6) above where the copolymer is based on equimolar proportions of alkyl fumarate and vinyl acetate but where the amount of maleic anhydride is 10 mole % based on the total weight of the fumarate and vinyl acetate.

Improved results are often achieved when the fuel compositions of this invention incorporate other additives known for improving the cold flow properites of distillate fuels generally. Examples of these other additives are the polyoxyalkylene esters, ethers, ester/ethers, amide/esters and mixtures thereof, particularly those containing at least one, preferably at least two C₁₀ to C₃₀ linear saturated alkyl groups of a polyoxyalkylene glycol of molecular weight 100 to 5,000 preferably 200 to 5,000, the alkyl group in said polyoxyalkylene glycol containing from 1 to 4 carbon atoms. European Patent Publication 0,061,895 A2 describe some of these additives.
The preferred esters, ethers or ester/ethers may be structurally depicted by the formula:
R⁵-O-(A)-O-R⁶
where R⁵ and R⁶ are the same or different and may be:
(i) n-alkyl

(ii) n-alkyl -
-

(iii) n-alkyl - O -
- (CH)₂)_n -

(iv) n-alkyl - O -
(CH₂)_n -
-
the alkyl group being linear and saturated and containing 10 to 30 carbon atoms, and A represents the polyoxyalkylene segement of the glycol in which the alkylene group has 1 to 4 carbon atoms, such as polyoxymethylene, polyoxyethylene or polyoxytrimethylene moiety which is substantially linear; some degree of branching with lower alkyl side chains (such as in polyoxypropylene glycol) may be tolerated but it is preferred the glycol should be substantially linear.
Suitable glycols generally are the substantially linear polyethylene glycols (PEG) and polypropylene glycols (PPG) having a molecular weight of about 100 to 5,000, preferably about 200 to 2,000. Esters are preferred and fatty acids containing from 10-30 carbon atoms are useful for reacting with the glycols to form the ester additives and it is preferred to use a C₁₈-C₂₄ fatty acid, especially behenic acids. The esters may also be prepared by esterifying polyethoxylated fatty acids or polyethoxylated alcohols. A particularly preferred additive of this type is polyethylene glycol dibehenate, the glycol portion having a molecular weight of about 600 and is often abbreviated as PEG 600 dibehenate. Similar polyethylene glycol dibehenates where the glycol portion has molecular weights of about 200 and 400 are often abbreviated as PEG 200 and PEG 400 respectively.
Other suitable additives for fuel composition of this invention are ethylene unsaturated ester copolymer flow improvers. The unsaturated monomers which may be copolymerised with ethylene include unsaturated mono and diesters of the general formula:
wherein R₈ is hydrogen or methyl, R₇ is a -OOCR₁₀ group wherein R₁₀ is hydrogen or a C₁ to C₂₈, more usually C₁ to C₁₇, and preferably a C₁ to C₈, straight or branched chain alkyl group; or R₇ is a -COOR₁₀ group wherein R₁₀ is as previously defined but is not hydrogen and R₉ is hydrogen or -COOR₁₀ as previously defined. The monomer, where R₇ and R₉ are hydrogen and R₈ is -OOCR₁₀, includes vinyl alcohol esters of C₁ to C₂₉, more usually C₁ to C₁₈, monocarboxylic acid, and preferably C₂ to C₂₉, more usually C₁ to C₁₈, monocarboxylic acid, and preferably C₂ to C₅ monocarboxylic acid. Examples of vinyl esters which may be copolmerised with ethylene include vinyl acetate, vinyl propionate and vinyl butyrate or isobutyrate, vinyl acetate being preferred. It is preferred that the copolymers contain from 20 to 40 wt % of the vinyl ester, more preferably from 25 to 35 wt % vinyl ester. They may also be mixtures of two copolymers such as those described in US Patent 3,961,916. It is preferred that these copolymers have a number average molecular weight as measured by vapor phase osmometry of 1,000 to 6,000, preferably 1,000 to 3,000.
Other suitable additives for fuel compositions of the present invention are polar compounds, either ionic or non-ionic, which have the capability in fuels of acting as wax crystal growth inhibitors. Polar nitrogen containing compounds have been found to be especially effective when used in combination with the glycol esters, ethers or ester/ethers. These polar compounds are generally amine salts and/or amides formed by reaction of at least one molar proportion of hydrocarbyl substituted amines with a molar proportion of hydrocarbyl acid having 1 to 4 carboxylic acid groups or their anhydrides; ester/amides may also be used containing 30 to 300, preferably 50 to 150 total carbon atoms. These nitrogen compounds are described in US Patent 4,211,534. Suitable amines are usually long chain C₁₂-C₄₀ primary, secondary, tertiary or quaternary amines or mixtures thereof but shorter chain amines may be used provided the resulting nitrogen compound is oil soluble and therefore normally containing about 30 to 300 total carbon atoms. The nitrogen compound preferably contains at least one straight chain C₈-C₄₀, preferably C₁₄ to C₂₄ alkyl segment.
Suitable amines include primary, secondary, tertiary and quaternary, but preferably are secondary. Tertiary and quaternary amines can only form amine salts. Examples of amines include tetradecyl amine, cocoamine, hydrogenated tallow amine and the like. Examples of secondary amines include dioctadecyl amine, methyl-behenyl amine and the like. Amine mixtures are also suitable and many amines derived from natural materials are mixtures. The preferred amine is a secondary hydrogenated tallow amine of the formula HNR₁R₂ wherein R₁ and R₂ are alkyl groups derived from hydrogenated tallow fat composed of approximately 4% C₁₄, 31% C₁₆, 59% C₁₈.
Examples of suitable carboxylic acids for preparing these nitrogen compounds (and their anhydrides) include cyclohexane, 1,2 dicarboxylic acid, cyclohexane dicarboxylic acid, cyclopentane 1,2 dicarboxylic acid, naphthalene dicarboxylic acid and the like. Generally, these acids will have about 5-13 carbon atoms in the cyclic moiety. Preferred acids are benzene dicarboxylic acid such as phthalic acid, tere-phthalic acid, and iso-phthalic acid. Phthalic acid or its anhydride is particularly preferred. The particularly preferred compound is the amide-amine salt formed by reacting 1 molar portion of phthalic anhydride with 2 molar portions of di-hydrogenated tallow amine. Another preferred compound is the diamide formed by dehydrating this amide-amine salt.
The relative proportions of additives used in the mixtures are preferably from 0.05 to 20 parts by weight, more preferably from 0.1 to 5 parts by weight of the amine salt - or quaternary ammonium salt - containing polymer to 1 part of the other additives, such as the polyoxyalkylene esters, ether, ester/ether or amide ether.
The amount of amine salt - or quaternary ammonium salt - containing polymer added to the liquid hydrocarbon fuel is preferably 0.0001 to 5.0 wt. %, for example, 0.001 to 0.5 wt %, especially 0.01 to 0.05 wt %, (active matter) based on the weight of hydrocarbon fuel.
The polymer may conveniently be dissolved in a suitable solvent to form a concentrate of from 20 to 90, e.g., 30 to 80 weight % of the polymer in the solvent. Suitable solvents include kerosene, aromatic naphthas, mineral lubricating oils, etc.

EXAMPLE 1

In this Example a vinyl acetate dialkyl fumarate copolymer AA was compared with two amine salt-containing copolymers, BB and CC and a quaternary ammonium salt-containing copolymer DD when added to two distillate fuel oils F1 and F2 having the following characteristics:

F1 F2

D-86 Distillation: IBP 222°C 238°C

20% 275°C 281°C

90% 336°C 331°C

FBP 360°C 352°C

Wax Appearance Point -3°C -3.5°C

Base CFPPT* -3°C -3°C

* Cold Filter Plugging Point Test.
Details of the polymers are as follows:

AA: A copolymer of equimolar proportions of vinyl acetate and C₁₂ alkyl/C₁₄ alkyl (1:1) dialkyl fumarate.
BB: A terpolymer of 50.0 mol % of vinyl acetate, 45.0 mole % of C₁₂ alkyl/C₁₄ alkyl (1:1) dialkyl fumarate and 5 mole % of maleic anhydride reacted with 5 mole % of trioctylamine.
CC: A terpolymer of 50.0 mole % of vinyl acetate, 45.0 mole % of C₁₂ alkyl/C₁₄ alkyl (1:1) dialkyl fumarate and 5 mole % of maleic anhydride reacted with 10 mole % of di-coco (C₁₂ to C₁₄) amine.
DD: A copolymer of 47.5 mole % of vinyl acetate, 47.5 mole % of C₁₂ alkyl/C₁₄ alkyl (1:1) dialkyl fumarate and 5 mole % of maleic anhydride reacted with 5 mole % of trioctyl methyl ammonium chloride and 5 mole % of NaOH in the minimum amount of water where NaCl separated.

Each of polymers AA, BB, CC and DD was mixed with half its weight of a 1:1:1 mole mixture of PEG 200 behenate, PEG 400 dehbenate and PEG 600 behenate and in each case the blend of polymer and PEG behenates were added to the fuel F1 and fuel F2 at an active matter concentration of 0.1% (1000 pm) and the results obtained when tested in the CFPPT were as follows:

Polymer Fuel F1 Fuel F2

AA -11 -10

BB -13 -12

CC -14 -12

DD -14 -13
It can be seen that the polymers BB, CC and DD show superior results to those shown by polymer AA which does not possess an amino group.
Details of the CFPPT are as follows:

THE COLD FILTER PLUGGING POINT TEST (CFPPT)

The cold filter properties of the blend were determined by 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", Vol. 52, No. 510, June 1966, pp. 173-185. In brief, a 40 ml. sample of the oil to be tested is cooled by a bath maintained at about -34^oC. Periodically (at each one degree of Centigrade drop in temperature starting from 2^oC above the cloud point) the cooled oil is tested for its ability to flow through a fine screen in a time period. This cold property is tested with a device consisting of a pipette to whose lower end is attached an inverted funnel positioned below the surface of the oil to be tested. Stretched across the mouth of the funnel is a 350 mesh screen having an area of about 0.45 square inch. The periodic tests are each initiated by applying a vacuum to the upper end of the pipette whereby oil is drawn through the screen up into the pipette to a mark indicating 20 ml. of oil. The test is repeated with each one degree drop in temperature until the oil fails to fill the pipette within 60 seconds. The results of the test are quoted as Δ CFPPT (^oC) which is the difference between the fail temperature of the untreated fuel (CFPP₀) and the fuel treated with the flow improver (CFPP₁), i.e.
Δ CFPP = CFPP₀ - CFPP₁

EXAMPLE 2

In this Example various amine-salt containing polymers based on alkyl fumarate-vinyl acetate-maleic anhydride mixed with the polyethylene glycol dibehenate, the glycol portion having a MW of about 600 (PEG 600 dibehenate) were added to a distillate fuel oil blend known as F3 having the characteristics given in Table 1.
The various polymers blended in each case with PEG 600 dibehenate in a weight ratio of 4 parts of polymer per part of PEG 600 dibehenate were as follows:
The CFPPT was determined for a fuel oil blend containing polymer A and this blend was also subjected to the PCT (programmed cooling test), details of which are as follows:

PROGRAMMED COOLING TEST (PCT)

This is a slow cooling test designed to correlate with the pumping of a stored heating oil. The cold flow properties of the described fuels containing the additives are determined by the PCT as follows. 300 ml of fuel are cooled linearly at 1^oC/hour to the test temperature and the temperature then held constant. After 2 hours at the test temperature, approximately 20 ml of the surface layer is removed by suction to prevent the test being influenced by the abnormally large wax crystals which tend to form on the oil/air interface during cooling. Wax which has settled in the bottle is dispersed by gentle stirring, then a CFPPT filter assembly is inserted. The tap is opened to apply a vacuum of 500 mm of mercury, and closed when 200 ml of fuel have passed through the filter into the graduated receiver: a PASS is recorded if the 200 ml are collected within ten seconds through a given mesh size or A fail if the flow rate is too slow indicating that the filter has become blocked.
The mesh number passed at the test temperature is recorded.
The results obtained were as follows:

Polymer Salt 4 pt by wt PEG 600 dibehenate 1 pt by wt Δ CFPP PCT (+2°C)*

1500 ppm 3000 ppm 1500 ppm 3000 ppm

(active ingredient) (active ingredient)

A 1 4.5 40 100

* Test temperature.
Further determination by the CFPPT were carried out on F3 blends containing polymers B to I all blended with PEG 600 dibehenate in a weight ratio of 4;1 respectively. Copolymer X which is included for comparison purposes is a copolymer of vinyl acetate and ditetradecyl fumarate. The results are as follows:

Polymer Salt Δ CFPP

1500 ppm (active ingredient) 3000 ppm (active ingredient)

B 1.5 2.5

C 1 2

D -2* 5.5

E 0.5 3

F 0 3

G 0 2.5

H 0.5 3.5

I 0.5 3

X 1.5 3.5

* Negative sign indicates an increase in CFPP.

The PCT (+2^oC) was also carried out on F3 blends containing polymers D, E, F, G, H, and I, all blended with PEG 600 dibehenate in a weight ratio of 4:1 respectively. The results obtained were as follows:

Polymer Salt	PCT Mesh Passed at 2°C
	1500 ppm a.i.		3000 ppm a.i.
D	60		150
E	30		80
F	40		80
G	30		80
H	100		200
I	30		60
X	80		150
No polymer (base fuel oil alone)		<20

The advantages of the blends containing the polymer over the base fuel oil alone can be clearly seen. TABLE 1

Wax Content (%)^(a) WAT (°C)^(b) WAP (°C) D86 Distillation

IBP D20 D50 D90 FBP

F3 4.9/9.8^(c) 10.3 7.5 204 262 295 346 362

(a) Wax at 5°C below WAT/10°C below WAT.

(b) Corrected for thermal lag.

(c) Estimated from component values.

EXAMPLE 3

In this Example the polymer salts D, E, F, G, H and I used in Example 2 were added to F4, a high boiling point distillate fuel and the CFPP (F4 alone) and the Δ CFPP measured in each case. The ASTM D86 distillation details of F4 are as follows:

IBP 172°C

D20 228°C

D50 276°C

D90 362°C

FBP 389°C

The results are given below for each polymer-salt added at 300 ppm and 500 ppm (active ingredient), i.e. 0.03 wt % and 0.05 wt %, to the base fuel oil, F4 and when compared with the untreated fuel oil.

Polymer Salt	Concentration ppm	CFPP		Δ CFPP
D	300	-3	-3	7
D	500	-6	-5	9
E	300	+3	+4	0
E	500	-4	-5	8
F	300	+1	+5	1
F	500	-5	-5	9
H	300	-5	-2	7
H	500	-6	-6	10
I	300	+1	+2	2
I	500	-8	-5	10
G	300	+3	+4	0
G	500	-6	-6	10
Base fuel oil alone		+4	+3

The polymer salts D, E, F, G, H and I were also blended with a copolymer Y in a mole rato of 1:4 respectively and then added to F4 at concentrations of 300 and 500 ppm (0.03 wt % and 0.05 wt %). Copolymer Y is a 3:1 weight mixture of an ethylene/vinyl acetate copolymer containing 36 weight % of vinyl acetate of molecular weight about 2000 and an ethylene/vinyl acetate copolymer containing 13 weight % vinyl acetate of molecular weight about 3000.

As before the CFPP (treated fuel oil) and the Δ CFPP were measured in each case. The results are as follows:

Polymer Salt	Concentration		CFPP		Δ CFPP
	Y (ppm)	Polymer Salt (ppm)
D	240	60	-14	-12	17
D	400	100	-17	-16	20
E	240	60	-14	-13	17
E	400	100	-15	-14	18
F	240	60	-15	-14	18
F	400	100	-15	-15	19
H	240	60	-15	-14	18
H	400	100	-14	-14	18
I	240	60	-12	-13	16
I	400	100	-16	-14	19
G	240	60	-15	-13	18
G	400	100	-14	-14	18
Base fuel oil alone			+4	+3

It can be seen that in all cases there is a considerable reduction in the flow point when the polymer salts are added to the base fuel oil.

EXAMPLE 4

Various polymer salts either alone or in admixture with Polymer Y (see Figure 2) were added to a distillate fuel oil F5 which had the following ASTM D86 distillation characteristics:

IBP 188°C

D20 236°C

D50 278°C

D90 348°C

FBP 376°C

The results of the CFPPT and the PCT were as follows:

Polymer Salt	Conc. (ppm)	CFPP		Δ CFPP	PCT at -9°C
D	375	-3,	-3	3	40
D	625	-4,	-4	4	80
E	375	-5,	-5	5	40
E	625	-5,	-4	4	60
F	375	-4,	-3	3	40
F	625	-3,	-3	3	60
H	375	-3,	-3	3	40
H	625	-4,	-4	4	60
I	375	-3,	-4	3	40
I	625	-5,	-5	5	60
G	375	-5,	-4	4	40
G	625	-6,	-6	6	60

Concentration ppm			CFPP		CFPP	PCT at -9°C
Y	Polymer
300	75	D	-16,	-18	17	150
500	125	D	-16,	-18	17	200
300	75	E	-14,	-16	15	120
500	125	E	-17,	-16	16	200
300	75	F	-16,	-14	15	150
500	125	F	-17,	-18	17	200
300	75	H	-14,	-15	14	120
500	125	H	-14,	-15	14	200
300	75	I	-17,	-14	15	150
500	125	I	-16,	-19	17	200
300	75	G	-16,	-17	16	120
500	125	G	-16,	-13	14	150

EXAMPLE 5

In this Example polymer salt C (as used in Example 2) and another polymer salt J was added to a distillate fuel F6 having the D86 distillation properties:

IBP 173°C

D20 222°C

D50 297°C

D90 356°C

FBP 371°C
Polymer salt J is the half amide, half amine salt of the copolymer of di-tetradecyl fumarate-vinyl acetate - 10 mole % maleic anhydride, the amine being R₂NH where R is C₁₆/C₁₈ alkyl.
These polymer salts C and J were also blended in a 1:1 mole ratio with ethylene-vinyl acetate copolymer mixture (see Example 3).

The polymer salts and mixtures thereof in a mole ratio of 1:1 with Y were added to the fuel oil at concentrations of 300 and 600 ppm (active ingredient) (0.03 and 0.06 wt%) and the resultant blends were subjected to the PCT and the CFPPT. The results are as follows:

Polymer Salt	Polymer	Concentration (ppm)	PCT (-8°C)	CFPP
J		300	40	+3	+3
J		600	80	+2	+3
J	Z	300	40	-5	-8
J	Z	600	80	-9	-8
C		300	<20	+3	+3
C		600	20	+3	+2
C	Z	300	40	-1	-2
C	Z	600	80	-6	-6

EXAMPLE 6

In this Example polymer salts A and B (as used in Example 2) and J (as used in Example 5) were added to the distillate fuel oil F6 of Example 5. In addition the following polymer salts were also added to this fuel oil. Each polymer salt was blended in a 1:1 mole ratio with the copolymer mixture Y as used in Example 3.

Each polymer salt blended with copolymer mixture Y was added to the fuel oil at two different concentrations, i.e. 300 and 600 ppm (0.03 wt % and 0.05 wt %) active ingredient and submitted to the PCT and CFPPT. The results obtained were as follows:

Additive + Y (1:1)	Concentration (ppm)	PCT (-8°C)		CFPP
K	300	-	20
K	600	-	20
K	300	40	60
K	600	80	100
L	300	-	20
L	600	-	20
L	300	40	60
L	600	80	100
J	300	40	60
J	600	100	120	+2	+1
J	300	60	80
J	600	80	100	-7	-8
A	300	20	30
A	600	20	30	+2	+1
A	300	40	60
A	600	60	80	-9	-11
B	300	-	20
B	600	-	20	+2	+1
B	300	40	60
B	600	60	80	-9	-9
F	300	-	20
F	600	-	20	+2	+2
F	300	30	40	-1	-2
F	600	80	100	-5	-8
M	300	-	20
M	600	-	20	+2	+1
M	300	30	40
M	600	80	100
Base fuel oil alone		20	30	+3	+3

It can be seen that in general adding the polymer salt improves the flow properties of the base fuel oil.

EXAMPLE 7

A comparison was made in the PCT and CFPPT between a copolymer of styrene and maleic anhydride partially esterified with tetradecanol (copolymer XX) and the polymer salt (N) obtained by hydrolysing the unesterified groups of XX and reacting the copolymer containing carboxylic acid groups with tri-octadecyl amine.
It was found that N was more potent than XX by 2^oC in the CFPP but by 6 mesh steps in the PCT at -14^oC, i.e. passes 60 µm versus 250 um when N and XX were added to the fuel oil F5 used in Example 4 at a concentration of 500 ppm.

EXAMPLE 8

In this Example a copolymer of n-octadecene and maleic anhydride reacted with the diamine R₂NH where R is a nC₁₆/nC₁₈ alkyl mixture to produce the polymer salt (P) was added to a distillate fuel alone and with copolymer Y (see Example 3) and comparisons were made with prior art copolymers also added to the same fuel by carrying out the tests PCT (at -10^oC) CFPPT and DSC.
The distillate fuel oil F7 to which the copolymers were added at concentrations of 175 and 300 ppm had the following ASTM D86 characteristics:

IBP 184°C

D20 226°C

D50 272°C

D90 368°C

FBP 398°C
Comparisons were also made with other prior art copolymers BB and CC, details of which (including copolymer AA) are as follows:

Copolymer AA: a copolymer of octadecene and maleic anhydride.
Copolymer BB: copolymer AA reacted with hexadecanol to form the ester.
Copolymer CC: copolymerAA reacted with octadecanol to form the ester.

DIFFERENTIAL SCANNING CALORIMETRY (DSC)

In the DSC (Differential Scanning Calorimetry) the Δ WAT (Wax Appearance Temperature) in ^oC is measured this being the difference between the temperature at which wax appears for the base distillate fuel oil alone (WAT₀) and the temperature at which wax appears for the treated distillate fuel oil (WAT₁) when the calorimeter is cooled at 2^oC/minute. In the DSC test results were obtained for only one concentration, namely, 300 ppm using 25 µl samples of fuel, i.e. Δ WAT = WAT₀ - WAT₁.
The results obtained were as follows where the first figure is from 175 ppm and the second figure (except DSC) for 300 ppm.

BB CC P

PCT alone 60/60 30/30 40/40

+ Y* 80/80 100/100 250/250

CFPP alone 0/Δ1 0/0 Δ1/Δ1

+ Y* Δ18/Δ19 Δ15/Δ16 Δ16/Δ19

DSC Δ WAT 4.2 2.8 2.2

* When Y was present the mole ratio of Y to BB, CC or N is 4:1.

Claims

1. A fuel composition comprising a major proportion by weight of a liquid hydrocarbon fuel and a minor proportion by weight of a polymer containing more than one amino group, this amino group being a salt of a primary, secondary or tertiary amine or a quaternary ammonium salt.

2. A composition according to Claim 1 wherein the fuel is a distillate fuel oil.

3. A composition according to either of Claims 1 and 2 wherein the polymer is derived from a polymer of one or more unsaturated ester monomers also including a free acid group or from a copolymer of unsaturated ester monomers at least one of which has a free acid group.

4. A composition according to either of Claims 1 and 2 wherein the polymer is derived from a copolymer of an unsaturated ester and/or an olefin with an unsaturated carboxylic anhydride.

5. A composition according to either of Claims 1 and 2 wherein the polymer is derived from a polymer containing ester groups partially hydrolysed to obtain carboxylic acid groups.

6. A composition according to either of Claims 1 and 2 wherein the polymer is derived from a partially hydrolysed polymer of an unsaturated ester thereafter reacted with a carboxylic anhydride.

7. A composition according to any one of the preceding claims wherein the polymer contains at least one hydrogen- and carbon-containing group where the total number of carbon atoms in said group(s) is at least 10 carbon atoms.

8. A composition according to Claim 7 wherein said group is attached directly or through a carboxylate group to the backbone of the polymer.

9. A composition according to Claim 7 wherein said group is attached to the nitrogen atom of the amine salt or of the quaternary ammonium salt.

10. A composition according to any one of the preceding claims which also includes a polyoxyalkylene ester, ether, ester/ether or amide/ester, an ethylene unsaturated ester copolymer flow improver, a polar nitrogen containing compound or a mixture thereof.

11. A composition according to Claim 10 wherein the polyoxyalkylene ester, ether, ester/ether or amide/ether contains at least two C₁₀ to C₃₀ linear saturated alkyl groups of a polyoxyalkylene glycol of molecular weight 100 to 5000.

12. A composition according to any one of the preceding claims wherein the amount of amine salt-containing polymer is 0.0001 to 5.0 weight % (active matter) based on the weight of hydrocarbon fuel.

13. The use as a flow improver in a liquid hydrocarbon fuel of a polymer containing more than one amino group, this amino group being a salt of a primary, secondary or tertiary amine or a quaternary ammonium salt.

14. The use according to Claim 13 wherein the fuel is a distillate fuel oil.

15. The use according to either of Claims 13 and 14 wherein the polymer is derived from a polymer of one or more unsaturated ester monomers also including a free acid group or from a copolymer of ester monomers at least one of which has a free acid group.

16. The use according to either of Claims 13 and 14 wherein the polymer is derived from a copolymer of an unsaturated ester and/or an olefin with an unsaturated anhydride.

17. The use according to either of Claims 13 and 14 wherein the polymer is derived from a polymer containing ester groups partially hydrolysed to obtain carboxylic acid groups.

18. The use according to either of Claims 13 and 14 wherein the polymer is derived from a partially hydrolysed polymer of an unsaturated ester thereafter reacted with a carboxylic anhydride.

19. The use according to any one of Claims 13 to 18 wherein the polymer contains at least one hydrogen- and carbon-containing group where the total number of carbon atoms in said group(s) is at least 10 carbon atoms.

20. The use according to Claim 19 wherein said group is attached directly or through a carboxylate group to the backbone of the polymer.

21. The use according to Claim 19 wherein said group is attached to the nitrogen atom of the amine salt or of the quaternary ammonium salt.

22. The use according to any one of Claims 13 to 21 in which the liquid hydrocarbon fuel also includes a polyoxyalkylene ester, ether, ester-ether or amide/ester, an ethylene-unsaturated ester copolymer flow improver, a polar nitrogen-containing compound or a mixture thereof.

23. The use according to Claim 22 wherein the polyoxyalkylene ester, ether, ester/ether or amide/ether contains at least two C₁₀ to C₃₀ linear saturated alkyl groups of polyoxyalkylene glycol of molecular weight 100 to 5000.

24. A concentrate comprising a solvent and based on the solvent 20 to 90 percent by weight of a polymer containing more than one amino group, this amino group being a salt of a primary, secondary or tertiary amine or a quaternary ammonium salt.

25. A concentrate according to Claim 24 wherein the polymer is derived from a polymer of one or more unsaturated ester monomers also including a free acid group or from a copolymer of unsaturated ester monomers at least one of which has a free acid group.

26. A concentrate according to Claim 24 wherein the polymer is derived from a polymer of an unsaturated carboxylic anhydride.

27. A concentrate according to Claim 24 wherein the polymer is derived from a polymer containing ester groups partially hydrolysed to obtain carboxylic acid groups.

28. A concentrate according to Claim 24 wherein the polymer is derived from a partially hydrolysed polymer of an unsaturated ester thereafter reacted with a carboxylic anhydride.

29. A concentrate according to any one of Claims 24 to 28 wherein the polymer contains at least one hydrogen- and carbon-containing group where the total number carbon atoms in said group(s) is at least 10 carbon atoms.

30. A concentrate according to Claim 29 wherein said group is attached directly or through a carboxylate group to the backbone of the polymer.

31. A concentrate according to Claim 29 wherein said group is attached to the nitrogen atom of the amine salt or of the quaternary ammonium salt.