ADDITIVES FOR DISTILLATE FUELS AND DISTILLATE FUELS CONTAINING THEM

Abstract: Polymer of number average molecular weight 1,000 to 20,000 containing the repeating units (I) (II) or (III) (II) have been found useful as low temperature flow improvers for distillate fuels particularly in combination with other additives.

Description: Additives for Distillate Fuels and Distillate Fuels Containing Them This invention relates to novel polymers useful as flow improvers for fuel oils and to oil and fuel oil compositions to which a flow improver has been added. When oils and fuel oils are subjected to low ambient temper¬ atures wax will separate out and impair the flow properties unless a Cold Flow Improver is added. The nature of the wax depends upon the type of fuel and this invention is particularly concerned with additives to treat Distillate Fuels which precipitate normal alkane waxes which in the absence of additives form large plates which will block fuel lines and filters . The invention relates to wax containing Distillate Fuels treated with additives whose size and structural configuration are particularly suited to the crystallography of the wax crystals which form in the Distillate Fuel as it cools, so that the additives interact with these waxes during crystallisation to produce precipitated wax of reduced crystal size. Mineral oils containing paraffin wax have the characteristic of becoming less fluid as the temperature of the oil decreases. This loss of fluidity is due to the crystallisation of the wax into plate-like crystals which eventually form a spongy mass entrapping the oil therein. The temperature at which the wax crystals begin to form is known as the Cloud Point and the temperature at which the wax prevents the oil from pouring as the Pour Point . Between these temperatures the wax crystals can however block filters and pipes rendering systems such as diesel trucks and domestic heating systems inoperable. The effectiveness of additives to improve the operability at low temperatures can be evaluated by tests such as the CFPP and PCT and their ability to depress the Cloud Point and Wax Appearance Point can also be ascertained. It has long been known that various additives act as wax crystal modifiers when blended with waxy mineral oils. These compositions modify the size and shape of wax crystals and reduce the cohesive forces between the crystals and between the wax and the oil in such a manner as to permit the oil to remain fluid at lower temperature and in some instances to have improved filterability at temperatures between the cloud point and the pour poin . Various Pour Point depressants have been described in the literature and several of these are in commercial use. For example, U.S. Patent. o. 3,048,479 teaches the use of copolymers of ethylene and C-]_-C5 vinyl esters, e.g. vinyl acetate, as pour depressants for fuels, specifically heating oils, diesel and jet fuels. Hydrocarbon polymeric pour depressants based on ethylene and higher alpha-olefins, e.g. propylene, are also known. U.S. Patent 3,961,916 teaches the use of a mixture of copolymers, to control the size of the wax crystals and United Kingdom Patent 1,263,152 suggests that the size cf the wax crystals may be controlled by using a copolymer having a low degree of side chain branching. Both systems improve the ability of the fuel to pass through filters as determined by the Cold Filter Plugging Point (CFPP) test since instead of SUBSTITUTE SHEET plate like crystals formed without the presence of additives the needle shaped wax crystals produced will not block the pores of the filter rather forming a porous cake on the filter allowing passage of the remaining fluid. Other additives have also been proposed for example, United Kingdom Patent 1,469,016, suggests that the copolymers of di-n-alkyl fumarates and vinyl acetate which have previously been used as pour depressants for lubricating oils may be used as co-additives with ethylene/vinyl acetate copolymers in the treatment of Distillate Fuels with high final boiling points to improve their low temperature flow properties. U.S. Patent 3,252,771 relates to the use of polymers * of C-_ ζ to C]_8 alpha-olefins obtained by polymerising olefin mixtures that predominate in normal __ to C-^g alpha-olefins with aluminium trichloride/alkyl halide catalysts as pour depressants in Distillate Fuels of the broad boiling types available in the United States in the early 1960's. It has also been proposed to use additives based on olefin/maleic anhydride copolymers. For example, U.S. Patent 2,542,542 uses copolymers of olefins such as octadecene with maleic anhydride esterified with an alcohol such as lauryl alcohol as pour depressants and United Kingdom Patent 1,468,588 uses copolymers of C22 -( *---28 olefins with maleic anhydride esterified with behenyl alcohol as co-additives for Distillate Fuels. Similarly, Japanese Patent Publication 5,654,037 uses olefin/maleic anhydride copolymers which have been reacted with amines as pour point depressants and in Japanese Patent Publication 5,654,038 the derivatives of the olefin/maleic SUBSTITUTE SHEET anhydride copolymers are used together with conventional middle distillate flow improvers such as ethylene vinyl acetate copolymers . Japanese Patent Publication 5,540,640 discloses the use of olefin/maleic anhydride copolymers (not esterified) and states that the olefins used should contain more than 20 carbon atoms to obtain CFPP activity. United Kingdom Patent 2,129,012 uses mixtures of esterified olefin/maleic anhydride copolymers and low molecular weight polyethylene, the esterified copolymers being ineffective when used as sole additives . The patent specifies that the olefin should contain 10-30 carbon atoms and the alcohol 6-28 carbon atoms with the longest chain -in the alcohol containing 22-40 carbon atoms. United States Patents 3,444,082; 4,211,534; 4,375,973 and 4,402,708 suggest the use of certain nitrogen containing compounds . Long n-alkyl derivatives of difunctional compounds have also been described as has their use as wax crystal modifiers for Distillate Fuels, to wit derivatives, particularly amine derivatives of alkenyl ' succinic acid (U.S. 3444082), maleic acid (U.S. 4211534) and phthalic acid (GB 2923645, U.S. 4375973 and U.S. 4402708) . Amine salts of certain alkylated aromatic sulphonic acids are described in United Kingdorr. Patent Specification 1209676 as is their use as antirusr additives for turbine oils and hydraulic oils . SUBSTITUTE SHEET The improvement in CFPP activity achieved by the incorporation of the additives of these Patents is achieved by modifying the size and shape of the wax crystals forming to produce needle like crystals generally of particle size 10,000 nanometres or bigger typically 30,000 to 100,000 nanometres . In operation of diesel engines or heating systems at low temperatures, these crystals do not generally pass through the filters but form a permeable cake on the filter which may allow the liquid fuel to pass, the wax crystals will subsequently dissolve as the engine and the fuel heats up, which can be by the bulk fuel being heated by recycled fuel. The wax crystals can however block the filters, leading to starting problems and problems at the start of driving in cold weather or failure of fuel heating systems . In European Patent Publication 0225688 we describe the use of itaconate and citraconate polymers and copolymers as flow improvers which are effective in improving the cold flow properties of an oil (crude or lubricating) and fuel oils such as residual fuel middle Distillate Fuels and jet fuel or as a dewaxing aid in lubricating oil and which can be tailored to suit the particular oil or fuel oil concerneci. These polymers and copolymers were described as having number average molecular weights as measured by Gel Permeation Chromatography of from 1,000 to 500,000 and the specific materials exemplified had molecular weights of 20,000 and higher. Specifically European Patent Publication 0225688 provides a crude oil, lubricating oil or fuel oil containing a minor proportion by weight of a polymer containing the units: (I) ( ii: (III) (ID where x is an integer and y is 0 or an integer and wherein in the total polymer x + y is at least two and the ratio of units (II) to units (I) is between 0 and 2, the ratio of units (II) to (III) is between 0 and 2 and wherein: SUBSTITUTE SHEET - 1 - R 1 and R2, the same or different, are C ] _ Q to C 30 alkyl, R 3 is H, -OOC R 6 , C-i to C 30 alkyl, -COO R^, -OR^, an aryl or alkaryl group or halogen, R 4 is H or methyl, R 5 is H, C*L to C30 alkyl, or -COOR 6 . R β is Ci to C 2 alkyl each of the groups R 1 , R 2 , R 3 , R 4 , R 5 and R 6 can be inertly substituted if desired. We have now found that the use of polymers and copolymers of this general formula of number average molecular weight in the range 1,000 to 20,000 as additives for Distillate Fuels results in the formation of particularly small wax crystals in the fuel, smaller than those achieved when using the higher molecular weight analogues. We have also found that this effect is particularly marked when the low molecular weight polymers and copolymers are used in combination with other types of additive. The present invention therefore provides the use as a flow improver in Distillate Fuel oil of a polymer of number average molecular weight 1,000 to 20,000 containing the repeating units : SUBSTITUTE SHEET (I) (ID (III) (II) where x is an integer and y is 0 or an integer and wherein in the total polymer x + y is at least two and the ratio cf units (II) to units (I) is between 0 and 2, the ratio cf units (II) to (III) is between 0 and 2, and wherein: SUBSTITUTE SHEET R 1 and R 2 , the same or different are C__ to C 30 alkyl, R 3 is H, -OOC R 6 , C*]_ to C 30 alkyl, -COO R°, an aryl or aralkyl group or halogen, R 4 is H or methyl, R 5 is H, Ci to C30 alkyl or -COOR 6 , R 6 is C_ to C22 alkyl and provided each of the groups R 1 , R 2 , R 3 , R 4 , R^ and R 6 can be inertly substituted. The invention further provides Distillate Fuel containing the polymer as defined above and an additive concentrate ' comprising a solution of a polymer as defined above suitable for incorporation into Distillate Fuels . The preferred polymers are homopolymers of a dialkyl itaconate or citraconate or copolymers of a dialkyl itaconate or citraconate with an aliphatic olefin, a vinyl ether, a vinyl ester of an alkanoic acid, an alkyl ester of an unsaturated acid, an aromatic olefin, a vinyl halide or a dialkyl fumarate or maleate. The groups R-'- and R 2 which can be the same or different are C]_o to C30 alkyl groups, and these are preferably straight chain although they can be branched. If branched it is preferred that the branch be a single methyl in the 1 or 2 position. Examples of the groups R*-- and R 2 are decyl, dodecyl, hexadecyl and eicosyl. Each of the groups R-- and R 2 may be a single C]_Q to C30 alkyl group or they may be mixtures of alkyl groups . It has been found that mixtures of C]_2 to C20 alkyl groups are particularly suitable when the polymer is to be used as a flow improver in middle SUBSTITUTE SHEET Distillate Fuel oils. Likewise, suitable chain lengths are C1 to C22 f° r use of the polymers in heavy fuel oils and crude oils and Cχo to ^18 for use of the polymer in lubricating oils . These preferred chain lengths are applicable both for homopolymers and copolymers . At least two polymers as defined in the present invention may be used in combination to advantage in a particular embodiment of the invention. Thus, as will be illustrated in the examples hereinafter, a first polymer may be selected to inhibit the tendency of wax to settle from a distillate fuel at reduced temperature, and a second polymer, being different from the first polymer, may be selected to counter any tendency of the first polymer to regress the CFPP performance of the fuel. For example, the first and second • such polymers may be homopolymers of a dialkylitaconate where the alkyl groups of the first polymer are the same as one another and the alkyl groups of the second polymer are the same as one another, those of the first polymer each having at least two (preferably two) carbon atoms fewer than those of the second polymer. Examples of such first polymers are those where the alkyl groups (i.e. R 1 and R 2 in the general formula herein) are C__,_ or Cτ_g or c 18- In specific examples, the alkyl groups of the first polymer are C__ ζ when those of the second polymer are Ci8' and the alkyl groups of the first polymer are C-ig when those of the second polymer are C20- In the above-described particular embodiment, the ratio of the first polymer to the second polymer may, for example, be in the range of 10:1 to 1:10. Where one or more other flow improver is used (such as described hereinafter) , the ratio of such flow improvers to the first and second polymers together may, for example, be in the range of 10:1 to 1:1C. SUBSTITUTE SHEET As an example, the ratio of the first polymer to the second polymer is 1:1, their combined ratio to any other flow improver also being 1:1. All of the above ratios are weight :weight (ai) . When copolymers of dialkyl itaconates or dialkyl citraconates are used y, being integer, the above-mentioned comonomer is a compound of the formula: where R-", R 4 and R~ are as defined above. Such comonomer can be one or more of a variety of compounds and in all cases mixtures of compounds having the above formula can be used. When the comonomer is an aliphatic olefin R 3 and R 5 are hydrogen or identical or non-identical 0χ to C30 alkyl groups, preferably n-alkyl groups. Thus, when R 3 , R 4 and R~> are all hydrogen, the olefin is ethylene, and when R 3 is methyl, R 4 and R 5 are hydrogen, the olefin is n-propylene. When R 3 is an alkyl group it is preferred that R 4 and R^ are hydrogen. Examples of other suitable olefins are butene-1, butene-2, isobutylene, pentene-1, hexene-1, tetradecene-1, hexadecene-1 and octadecene-1 and mixtures thereof. Other suitable comonomers are vinyl esters or alkyl substituted vinyl esters of C2 to C31 alkanoic acids, i.e. for vinyl esters when R 3 is R 6 COO-, R 4 is H and R > is H, and for alkyl substituted vinyl esters when R 3 is R 6 COO- and R 4 is methyl and/or R 5 is C-j_ to C30 alkyl. Non-substituted vinyl esters are preferred and suitable examples are vinyl acetate, vinyl propionate, vinyl SUBSTITUTE SHEET butyrate, vinyl decanoate, vinyl hexadecanoate and vinyl stearate. Another class of comonomers are the alkyl esters of unsaturated acids, i.e. when R 3 is a R 6 OOC- and R^ is H or Ci to C30 alkyl. When R 4 and R5 are hydrogen these comonomers are alkyl esters of acrylic acid. When R 4 is methyl the comonomers are esters of methacrylic acid or C-_ to C30 alkyl substituted methacrylic acid. Suitable examples of alkyl esters of acrylic acid are methyl acrylate, n-hexyl acrylate, n-decyl acrylate, n-hexadecyl acrylate, n-octadecyl acrylate, and 2-methyl hexadecyl acrylate, whilst suitable examples of alkyl esters of methacrylic acid are propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, nøtetradecyl methacrylate, n-hexadecyl methacrylate and nøoctadecyl methacrylate. Other examples are the corresponding esters where R^ is alkyl, e.g. methyl, ethyl,, n-hexyl, n-decyl, n-tetradecyl and n-hexadecyl. Another suitable class of comonomers is when both R 3 and R 5 are R 6 OOC-, i.e. when they are C__ to C22 dialkyl fumarates or aleates and the alkyl groups may be n-alkyl or branched alkyl, e.g. n-octyl, n-decyl, n-tetradecyl, n-hexadecyl or n-octadecyl. Other examples of comonomer are when R 3 is an aryl group. When R 4 and R^ are hydrogen and R 3 is phenyl the comonomer is styrene and when one of R 4 and R^ is methyl and comonomer is a methyl styrene, e.g. -methyl styrene. Another example when R 3 is aryl is vinyl naphthalene. Other suitable examples when R 3 is alkaryl are for example substituted styrenes such as vinyl toluene, or 4-methyl styrene. SUBSTITUTE SHEET Another suitable co-monomer is when R 3 is halogen, e.g. chlorine, such as vinyl chloride (R 4 and R^ hydrogen) . In all cases it is to be understood that some or all of the groups R 1 , R 2 , R 3 , R 4 , R 5 and R 6 can be inertly substituted, for example, by one or more halogen atoms, for instance, chlorine or fluorine. Thus, for example, the comonomer could be vinyl trichloroacetate . Alternatively, the substituent could be an alkyl group, e.g. methyl. The ratio of units (II) to units (I) should be between 0 (when the polymer is an itaconate or citraconate homopoivmer) " and 2 (when the polymer is a copolymer) but in practice the ratio for the copolymer will usually be between 0.5 and 1.5. Usually the copolymer will consist of only units ' (I) and (II) or units (II) and (III), but other units are not excluded. However, in practice, it is desirable that the weight percentage of units (I) and (II) or of units (II) and (III) in the copolymer is at least 60% and preferably at least 70%. For both homopolymers and copolymers the molecular weight cf the polymer will be between 1,000 and 20,000, preferably between 1,000 and 10,000, more preferably between 2,200 and 5,000. We have found .that particular small wax crystals are obtained in Distillate Fuels when polymers or copolymers of molecular weights in this range are used. Molecular weights are measured by gel permeation chromatography (GPC) relative to polystyrene standards . The homopolymers and copolymers are generally prepared by polymerising the monomers neat or in solution in a hydrocarbon solvent such as heptane, benzene, cyclohexane, or white oil, at a temperature generally in the range of from 20°C to 150°C and usually promoted with a peroxide or azo type catalyst such as benzoyl peroxide or SUBSTITUTE SHEET azodiisobutyronitrile under a blanket of an inert gas such as nitrogen or carbon dioxide in order to exclude oxygen. The polymer may be prepared under pressure in an autoclave or by refluxing. When copolymers are to be prepared the polymerisation reaction mixture should preferably contain up to 2 moles of comonomer (e.g. vinyl acetate) per mole of dialkyl itaconate or dialkyl citraconate. The copolymers are suitable for use as low temperature flow improvers in fuel oils . These fuel oils can be 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° to 500°C (ASTM D-86) , preferably those boiling in the range 150° to 400°C, for example, those having a relatively high final boiling point (FBP) of above 360°C. A representative heating oil specification calls for a 10 percent distillation point no higher than about 226°C, a 50 percent point no higher than about 272°C and a 90 percent point of at least 282°C and no higher than about 338°C to 343°C, although some specifications set the 90 percent point as high as 357°C. 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. A representative specification for a diesel fuel includes a minimum flash point of 38°C and a 90 percent distillation point between 282°C and 338°C. (See ASTM Designations D-396 and D-975) . The best effect is usually obtained when the polymer additives of the invention are used in combination with othe: additives known for improving the cold flow properties of SUBSTITUTE SHEET Distillate Fuels generally. The polymer additives of the invention may however be used on their own. The additives of the invention are particularly effective when used in combination with comb polymers of the general formula. n where D = R, C(O) .OR, OC(O) .R, R 1 C(0) .OR or OR E = H or CH3 or D or R 1 G = H, or D m = 1.0 (homopolymer) to 0.4 (mole ratio) J = H, R 1 , Aryl or Heterocyclic group, R 1 CO.OR K = H, C(0) .OR-*-, OC(0) .R 1 , OR 1 , C (0) OH L = H, R 1 , C(O) .OR 1 , 0C(0) .R 1 , Aryl, C(0)OH n = 0.0 to 0.6 (mole ratio) R is a hydrocarbyl group containing more than 10 carbon atoms, preferably from 10 to 3C carbon atoms • 1 is a Ci to C30 hydrocarbyl group. The comb polymers may contain termonomers . Examples of suitable comb polymers are the fumarate/vinyi acetate particularly those described in our European Patent Publications 0153176, 0153177, and esterified olefine/maleic anhydride copolymers and the polymers and copolymers of alpha defines and esterified copolymers of styrene and maleic anhydride . Examples of other additives which may be included in the compositions of this invention are the polyoxyalkylene esters, ethers, ester/ethers amide/esters and mixtures thereof, particularly those containing at least one, preferably at least two C^ Q to C30 linear saturated alkyl groups of a polyoxyalkylene glycol group 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 describes some of these additives . The preferred esters, ethers or ester/ethers may be structurally depicted by the formula: R-O- (A)-O-R 1 where R and R are the same or different and may be i) n-alkyl 0 II ϋ ) n-alkyl— C — 0 II iϋ ) n-alkyl— 0—C—( CH 2 )τ— II 0 0 II II iv) n-alkyl-O— C— (CH 2 )- — C— the alkyl group being linear and saturated and containing 1C to 30 carbon atoms, and A represents the polyoxyalkylene segment 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; SUBSTITUTE SHEET 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 C*j_8 _ C24 fatty acid, especially behenic acids . The esters may also be prepared by esterifying polyethoxylated fatty acids or polyethoxylated alcohols . A may also contain nitrogen in which case the materials may be obtained by esterification of ethoxylated amines . Other suitable additives for inclusion in the fuel compositions 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 R^ is hydrogen or methyl, R 7 is a -OOCR 1 ^ group wherein R 1 ^ is hydrogen or a C* ] _ to C28 r more usually C]_ to C__η , and preferably a C__ to C^, straight or branched chain alkyl group; or R 7 is a -COOR 1 ^ group wherein R--® s as previously defined but is not hydrogen and R9 is hydrogen or -COOR 1 ^ as previously defined. The monomer, when R 7 and R^ are hydrogen and R^ is -00CR 11 *- 1 , includes vinyl alcohol esters of 0 to 029, SUBSTITUTE SHEET more usually C-_ to Cχ8r monocarboxylic acid, and preferably C2 to C2g, more usually C]_ to monocarboxylic acid, and preferably C2 to C5 monocarboxylic acid. Examples of vinyl esters which may be copolymerised with ethylene include vinyl acetate, vinyl propionate and vinyl butyrate or isobutyrate, vinyl acetate being preferred. It is preferred that the copolymers contain from 10 to 40 wt0% of the vinyl ester, more preferably from 25 to 35 wt0% 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 vapour phase osmometry of 1,000 to 6,000, preferably 1,000 to 4,000. Other suitable additives for inclusion in the fuel compositions of the present invention are polar compounds, either ionic or non-ionic, which have the capability in fuels of acting as w.ax crystal growth inhibitors. 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 C;j_2 -C 40 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-C_ j θ preferably C14 to C24 alkyl segment. SUBSTITUTE SHEET Suitable amines include primary, secondary, tertiary or quaternary, but preferably are secondary. Tertiary and quaternary amines can only form amine salts. Examples of amines include tetradecyl amines, cocoamine, hydrogenated tallow amine and the like. Examples of secondary amines include dioctacedyl 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 NHR1R2 wherein R__ and R2 are alkyl groups derived from hydrogenated tallow fat composed of approximately 4% C]_4, 31% C-]_5, 59% C]_8- Examples of suitable carboxylic acids or their anhydrides 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 acids such as phthalic acid, tera-phthalic acid, and iso-phthalic acid. Phthalic acid or its anhydride is particularly preferred. Alkyl substituted succinic acid or anhydride may also be used. 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 . Examples of other suitable co-additives include the compounds described in our European Patent Application 0261957 which are compounds of the general formula: SUBSTITUTE SHEET where A and B may be the same or different and may be alkyl, alkenyl or aryl; L is selected from the group consisting of >CH - CH< and >C = C< and A, B and L together can constitute part of a cyclic structure, which can be aromatic, alicyclic or mixed aromatic/alicylic and with the proviso that when A,B and L do not constitute part of a cyclic structure one of A or B may be hydrogen and in that when L is non-cyclic ethylenic, said X-X and Y-Y 1 groupings are present in a cis configuration; X is selected from the group consisting of S0 3 <->, -C(O)-, -C(0)θ (-) -, -R 4 -C(0)0-, -NR 3 C(0)- -R 0-, -R 0C(0)-, -R 4 - and -NC(O) - ; X 1 is selected from the group consisting of N (+) R 3 R 2 A HN( + )R 3 R , H 2 N( + )R 3 R 2 , H 3 N(+)R 2 , N(+)R 3 R1, N( + )HR R 1 , H 2 N( + )R3 R I. H 3 N( + )R 1 , NR R 2 , -R 2 , - RSR 1 , and R 1 ; SUBSTITUTE SHEET Y is -Sθ3 ~ or -SO2- ; When Y is SO3 ( - " •', Y 1 is selected from the group consisting of N(-Γ)R|R 2 , HN (+) R 3 R 2 Λ H 2 N( + )R R 2 , H 3 N( + )R 2 , and when Y is -S0 - Y 1 is -OR 2 , -NR 3 R 2 or -R 2 and wherein R 1 and R 2 are independently selected from the group consisting of alkyl typically C*)_o to C40 alkyl more preferably C*j_o to C30 more preferably C14 to C24 alkyl, alkoxy alkyl or polyalkoxyalkyl groups containing at least 10 typically ten to 40 carbon atoms in their main chain R 3 is hydrocarbyl preferably alkyl, more preferably C]_ to C30 most preferably C]_o to C30 straight chain alkyl and each R 3 may be the same or different and R 4 is ~(CH2) n where n is from 0 to 5. It is preferred that X 1 and Y 1 together contain at least three alkyl, alkoxy alkyl or polyalkoxy alkyl groups . In these compounds A and B together or separately form one or more bulky groups, L is the linking group which may also be part of the bulky group, X and/or Y are configurational groups and X 1 and/or Y constitute the adsorbing groups . When L is part of a cyclic structure together with A and B, the cyclic structure may be aromatic, alicyclic, or mixed aromatic/alicyclic. More specifically the cyclic structure may be mono-cyclic or polycyclic aromatic, polynuclear aromatic, heteroaromatic, and heteroalicyclic. The ring TUTE SHEET structure may be saturated or unsaturated with one or more unsaturations; with at least one ring containing 4 or more atoms, and it may be multicyclic, bridged and may be substituted. When the cyclic structure is heterocyclic it may include one or more of N, S or O atoms . Examples of suitable monocyclic ring structures are benzene, cyclohexane, cyclohexene, cyclopentane, pyridine and furan . The ring structure may contain additional substituents . Suitable polycyclic compounds, that is those having two or more ring structures, can take various forms. They can be (a) fused aromatic structures, (b) fused partially hydrogenated aromatic ring structures where at least one but not all rings are aromatic, (c) alicyclic which, includes fused alicyclic, bridged alicyclic, spiro alicyclic compounds (d) hydrocarbon ring assemblies of like or unlike rings which may be aromatic, alicyclic or mixed; (e) any of (a) to (d) which contain at least one hetero atom. Fused aromatic structures from which the compounds defined by L, A and B collectively may be derived include for example naphthalene, anthracene, phenathrene, fluorene, pyrene and indene. Suitable condensed ring structures where none or not all rings are benzene include for example azulene, hydronaphthalene, hydroindene, hydrofluorene, diphenylene. Suitable bridged alicyclic structures include bicycloheptane and bicycloheptene . Suitable ring assemblies include biphenyl and cyclohexyl benzene. Suitable heteropolycyclic structures include σuinuclidine and indole. .SUBSTITUTE SHEET Suitable heterocyclic compounds defined by L, A and B collectively from which the compounds of this invention may be derived include quinoline; indole, 2,3 dihydroindole, benzofuran, coumarin and isocoumarin, benzothiophene, carbazole and thiodiphenylamine. Suitable non-aromatic or partially saturated ring systems defined by L, A and B collectively include decalin (decahydronaphthalene) , 00-pinene, cadinene, bornylene. Suitable bridged compounds include norbornene, bicycloheptane (norbornane) , bicyclo octane and bicyclo octene . When L, A and B form part of a cyclic structure X and Y are preferably attached to adjoining ring atoms located completely within a single ring whether mono- or polycyclic. For example if one were to use naphthalene, these substituents could not be attached to the 1,8- or 4,5- positions, but would have to be attached to the 1,2-, 2,3-, 3,4-, 5,6-, 6,7- or 7,8- positions. The hydrogen- and carbon-containing groups in the substituents A and B when L is ethylenic and not part of a ring with A and B, are preferably alkyl, typically C-j_ tc C2 alkyl or alkenyl, aryl typically Cg to C1 aryl. Such groups may also be halogenated preferably only containing a small proportion of halogen atoms (e.g. chlorine atoms), for example less than 20 weight per cent. The A and B groups are preferably aliphatic, e.g. alkylene. They are preferably straight chain. Unsaturated hydrocarbyl groups, e.g. alkenyl, could be used but they are not preferred. When the compounds are used as Distillate Fuel additives we prefer that R 1 , R 2 , and R 3 when present contain 10 to 24 carbon atoms, for example 14 to 22 preferably 18 to 22 carbon atoms and are preferably straight chain or branched at SUBSTITUTE SHEET the 1 or 2 position. Suitable alkyl groups include decyl, dodecyl, tetradecyl, eicosyl and docosyl (behenyl) . Alternatively the groups may be polyethylene oxide or polypropylene oxide, the main chain of the groups being the longest linear segment. The especially preferred compounds are the amides or amine salts of secondary amines. Although two substituents are necessary for the cyclic derivatives described above it should be realised that these cyclic compounds can contain one or more further substituents attached to ring atoms cf the cyclic compounds . These compounds may be prepared from a reactant such as where A, B, L are as previously defined and X 2 and Y 2 are as defined in connection with X and Y and additionally and Y together can form part of a cyclic anhydride structure wherein an oxy group (0) is common to both X-*-* ana Y 2 . Preferred reactants are those in which X 2 is selected from -C(0)0- and -Sθ3 (~ * 1 and particularly preferred reactants are compounds of the formula: SUBSTITUTE SHEET The most preferred reactants are compounds in which A, B and L together are part of a cyclic structure especially an aromatic ring. A particularly preferred reactant is represented by the formula: in which the aromatic ring may be substituted, and in which the aromatic ring represents A,B and L collectively, and X 2 and Y 2 together form an anhydride ring. The compounds are prepared by reacting both the Y 2 -H group and the X -H group with amines, alcohols, quaternary ammonium salts etc. or mixtures thereof. Where the final compounds are the amides or amine salts they are preferably of a secondary amine which has a hydrogen and carbon containing group containing at least 10 carbon atoms preferably a straight chain alkyl group containing from 10 to 30 more preferably 16 to 24 carbon atoms. Such amides or salts may be prepared by reacting the acid or anhydride with a secondary amine or alternatively by reaction with an amine derivative. Removal of water and heating are generally necessary to prepare the amides from the acids . Alternatively the Y -H and X -H groups may be reacted with an alcohol containing at least 10 carbon atoms or a mixture of an alcohol and an amine or sequentially with an amine and an alcohol or vice-versa. SUBSTITUTE SHEET Thus, the final additive compounds, comprise as a result of the identity of X-X 1 , and Y-Y 1 esters, amides, ethers, primary, secondary or tertiary amine salts, amino amides, a ino ethers and the like. The preferred compounds of this type are of the formulae: more preferably and Hydrocarbon polymers may also be used in additive combinations of the present invention, these may be of the following general formula: w SUBSTITUTE SHEET where each may be T = H or R 1 U = H, T or Aryl v = 1.0 to 0.0 (mole ratio) w = 0.0 to 1.0 (mole ratio) where R 1 is alkyl. These polymers may be made directly from ethylenically unsaturated monomers or indirectly by hydrogenating the polymer made from monomers such as isoprene, butadiene, etc. A particularly preferred hydrocarbon polymer is a copolymer of ethylene and propylene having an ethylene content- preferably between 20 and 60% (w/w) and is commonly made via homogeneous catalysis. One or more of these co-additives may be used in the compositions of this invention. When mixtures of additives are used 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 itaconate or citraconate polymer or copolymer to 1 part of the other additives . The total amount of additive added to the fuel oil is preferably 0.0001 to 5.0 wt0%, for example, 0.001 to 0.5 wt0% (active matter) based on the weight of fuel oil. The additives 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. Such concentrates are also within the scope of this invention. The present invention is illustrated by the following Examples in which the following additives were used. Additive A The N,N-dialkyl ammonium salt of 2-dialkylamido benzene sulphonate where the alkyl groups are nC**_5_**_8 H33_37. Prepared by reacting 1 mole of ortho-sulphobenzoic acid cyclic anhydride with 2 moles of di- (hydrogenated) tallow amine in a xylene solvent at 50% (w/w) concentration. The reaction mixture was stirred at between 100°C and the refluxing temperature. The solvent and chemicals should be kept as dry as possible so as not to enable hydrolysis of the anhydride. The product was analysed by 500 MHz Nuclear Magnetic Resonance Spectroscopy and the spectrum confirmed the structure to be (CH 2 - (CH 2 ) ι 4/ ι 6 -CH 3 ) 2 (-)H 2 N(+) (CH 2 (CH 2 ) 14/16 CH 3 ) SUBSTITUTE SHEET Addit ive B An ethylene vinyl acetate copolymer of number average molecular weight 3500 containing 13.5 wt% vinyl acetate and containing 8 methyls per 100 methylene groups. Additive C Various itaconate polymers prepared by polymerising the monomers in cyclohexane solvent using a free radical catalyst . Oligomeric materials of number average molecular weight 4000 and polymeric materials of molecular weight 80,000 were prepared for the sake of comparison . Each contained C__2 to C* ] _8 linear alkyl groups in the itaconate esters . These are referred to in the table that follows as CIQ PI, C]_2 -P* 3 -/ C1 PI, etc. Additive D The reaction product of one mole of phthalic anhydride with two moles of dihydrogenated tallow amine, to form a half amide/half amine salt. Additive E An ethylene vinyl acetate copolymer of number average molecular weight 3000 containing 29% vinyl acetate and containing 4 methyl groups per 100 methylene groups. SUBSTITUTE SHEET Additi e Additive D blended with 10 wt% benzoic acid as a stabilizer. Additive G The 3 nitro derivative of Additive D The various additives were used in combination at a treat rate of 250 ppm each in a Distillate Fuel having the following characteristics Cloud Point -2°C Untreated CFPP -4°C ASTM D-86 distillation °C Initial Boiling Point 178 Final Boiling Point 368 and tested in the following tests . Testing The effectiveness of additive systems as filterability improvers in Distillate Fuels were determined by the following methods . By one method, the response of the oil to the additives was measured by the Cold Filter Plugging Point Test (CFPP) whic: is carried out by the procedure described in detail in "Journal of the Institute of Petroleum", Volume 52, Number 510, June 1966, pp. 173-285. This test is designed to correlate with the cold flow of a middle distillate in automotive diesels . S UBSTITUTE SHEET In brief, a 40 ml. sample of the oil to be tested is cooled in a bath which is maintained at about -34°C to give non-linear cooling at about l°C/min. Periodically (at each one degree C starting from above the cloud point), the cooled oil is tested for its ability to flow through a fine screen in a prescribed time period using a test device which is a pipette to whose lower end is attached an inverted funnel which is 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 defined by a 12 millimetre diameter. 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. After each successful passage, the oil is returned immediately to the CFPP tube. The test is repeated with each one degree drop in temperature until the oil fails to fill the pipette within 60 seconds. This temperature is reported as the CFPP temperature. The difference between the CFPP of an additive free fuel and of the same fuel containing additive is reported as the CFPP depression (dCFPP) by the additive . A more effective flow improver gives a greater CFPP depression at the same concentration of additive. Another determination of flow improver effectiveness is made under conditions of the flow improver Programmed Cooling Test (PCT) which is a slow cooling test designed to indicate whether the wax in the fuel will pass through filters such as are found in heating oil distribution system. In the test, the cold flow properties of the described fuels containing the additives were determined as follows. 300 ml. of fuel are cooled linearly at l°C/hour to the test temperature and the temperature then held constant . After 2 hours at -12°C, approximately 20 ml. of the surface layer is SUBSTITUTE SHEET moved as 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 stirring, then a CFPP 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 60 seconds through a given mesh size of a FAIL if the flow rate is too slow indicating that the filter has become blocked. CFPP filter assemblies with filter screens of 20, 30, 4C, 60, 8C, 100, 120, 150, 200, 250, 350, VW, LTFT and 500 mesh ■ number and then 25, 20, 15 and 10 microns are used to determine the finest filter the fuel will pass. The larger the mesh number that a wax containing fuel will pass, the smaller are the wax crystals and the greater the effectiveness of the. additive flow improver. It should be noted that it is unlikely that two fuels will give exactly the same test results at the same treatment level for the same flow improver additive. In the tables herein, the relative order is also given, higher numbers representing a finer filter passed. Wax settling studies were also performed prior to PCT filtration. The extent of the settled layer (WAS) was visually measured as a % of the total fuel volume by leaving the treated fuel in a measuring flask. This extensive wax settling would be given by a low number whilst an unsettled fluid fuel would be at a state of 100%. Care must be taken because poor samples of gelled fuel with large wax crystals almost always exhibit high values, therefore these results should be recorded as "gel". The effectiveness of the additives of the present invention in lowering the Cloud Point of Distillate Fuels can be determined by the standard Cloud Point Test (IF-219 cr AST -Z SUBSTITUTE SHEET 2500) other measures of the onset of crystallisation are the Wax Appearance Point (WAP) Test (ASTM D.3117-72) and the Wax Appearance Temperature (WAT) as measured by differential scanning calorimetry using a Mettler TA 2000B differential scanning calorimeter. In the test a 25 microlitre sample of the fuel is cooled at 2°C/min. from a temperature at least 30°C above the expected cloud point of the fuel. The observed onset of crystallisation is estimated, without correction for thermal lag (approximately 2°C) , as the wax appearance temperature as indicated by the differential scanning calorimeter. This is the preferred method because of its accuracy and repeatability and is consequently the method of choice here. The Wax Appearance Temperature (WAT) of the fuel is measured by differential scanning calorimetry (DSC) . In this test a small sample of fuel (25 ul) is cooled at 2°C/minute together with a reference sample of similar thermal capacity but which will not precipitate wax in the temperature range of interest (such as kerosene) . An exotherm is observed when crystallisation commences in the sample. For example the WAT of the fuel may be measured by the extrapolation technique or. the Mettler TA 2000B. dWAT is the depression of the Wax Appearance Temperature from the base fuel due to the incorporation of the additive in the fuel . The wax content is derived from the DSC trace by integrating the area enclosed by the baseline and the exotherm down to the specified temperature. The calibration having been previously performed on a known amount of crystallizing wax. The wax crystal average particle size is measured by analysing an Optical Micrograph of a fuel sample and measuring the longest axis of crystals . SUBSTITUTE SHEET The crystal shape is determined by taking magnified photographs of the wax crystals in the fuel. The Results of the tests are set out in Table 1 as follows: TABLE 1 Polyitaconate Composition Crystal % % Size Relative (nanometres) Crystal Shape PCT PCT 100 Plates 120 100 30-80 Plates 100 0-50 Plates 100 10-20 Bypyramid 100 5-20 Bypyramid 100 10-50 Plates 100 _0-80 Plates Grad floe >200 Ribbons & 60 dendrites Dendrites Dendrites Nodules Plates 100 10-20 Small 100 -10 Small 100 <10 Small 100 10->200 Plates 100 10->200 Plates dWAT 0.8 0.8 0.1 0.5 0.9 1.9 0.8 I 1.9 1.7 0.8 2.2 2.1 1.2 2.1 1.9 1.0 2.1 2.0 1.1 2.0 1.9 1.0 TABLE 1 % % % Relative Additive, Polymer Oliσomer WAS PCT PCT CFPP dCFPP CIO PI 20 80 Gel 30 2 -3 -1 C12 PI 20 80 Gel 30 2 -3 -1 C14 PI 30 70 Gel 30 2 -3 -1 C16 PI 10 90 Floe 20 1 -4 0 C18 PI 0 100 Gel 40 3 4 c ra CIO PI 20 80 -13 9 C12 PI 20 80 -16 12 H C14 PI 30 70 -9 5 C16 PI 10 90 -7 3 c C18 PI 0 100 -12 8 0 m CIO PI 20 80 -6 2 0 C12 PI 20 80 -4 0 x) C14 PI 30 70 -5 1 π C16 PI 10 90 -1 -3 pi C18 PI 0 100 -13 -I E CIO PI 20 80 -17 13 C12 PI 20 80 -19 15 C14 PI 30 70 -17 13 C16 PI 10 90 -14 10 C18 PI 0 1 00 -19 15 In a further series of experiments the following additional additives were used. Additive H A mixture of two ethylene vinyl acetate copolymers : one of M n 2580 and containing 36.5 wt% vinyl acetate and the other of M n 5000 and containing 13.5 wt% vinyl acetate, the ratio of the two copolymers being 3:1 (weight :weight) . Additive I As Additive H but where the ratio of two copolymers is 13:1 (weight : eight) . Additive J An ethylene vinyl acetate copolymer of number average molecular weight 2000 containing 28.0 wt% vinyl. The Additives were tested in the fuels having the properties se: out in table 2 : SUBSTITUTE SHEET TABLE 2 (0 c m c H π 0) x PI n In the tests the treat rate is 250 ppm active ingredient of each additive. The wax antisettling was measured by: (a) Visual examination of the vessel as described in the previous example. The figure gives the extent of wax settling and is further qualified by a letter, via C = clear above % layer, i.e. fuel has been dewaxed completely down to test temperature and all the wax has settled to bottom layer. F = Floe, indicative of undesirable larger crystals present . CL = Cloudy with bottom layer, a good anti-settling result . In the results the letter H means Hazy, M means Milky and C is Clear, F is FLOC. (b) Taking a top and bottom sample of 5 mis. They were then examined by measuring their WATS on a DSC as previously described. In an unsettled sample the two numbers would be the same. The bigger the difference between the numbers the greater the wax settling. Thus T-B range = WAT bottom - WAT top (°C) . The results are set out in Table 3: TABLE 3 t C12 SFEC 60H 60 -17 C12-14 SFEC 50C 80 -15 C14 SFEC 60C 100 -15 C14-16 SFEC 30C 60 -11 C16 SFEC 100 gel 60 -2 C16 PI (olig) 30CL 60 -4 C18 PI (olig) 90CL 150 -16 TABLE 3 ω c B3 (0 -J ^ CO C H rπ x I PI TABLE 3 TABLE 3 A still further set of experiments was carried out . The additives used were as follows, designated by the letters A 1 , B 1 , D 1 , E 1 and F 1 to M 1 , and the fuels used were those as characterised hereinafter: A-*- : For tests on Fuels I and II, A was a mixture of two ethylene/vinyl acetate copolymers: a copolymer of Mn 2580 containing 36.5 wt% vinyl acetate and containing 3-4 methyl groups per 100 methylene groups, and a copolymer of Mn 5000 containing 13.5 wt% vinyl acetate and containing 6 methyl groups per 100 methylene groups, the ratio of the two copolymers being 93:7 (weight : eight) ; for tests on the remaining fuels, A was an ethylene/vinyl acetate copolymer of Mn 3000 containing 29.0 wt% vinyl acetate and containing 4 methyl groups per 100 methylene groups. __>- • - : the reaction product of one mole of phthalic anhydride with two moles of dihydrogenated tallow amine to form a half amide/half amine salt. _2~- : a homopolymer of an ester of itaconic acid whose linear alkyl groups have 16 carbon atoms made by polymerising the monomer using a free radical catalyst, the homopolymer having an Mw of 4000. E 1 : a blend of D-*- and a second polyitaconate made in the same way as additive D*-- but whose alkyl groups have 18 carbon atoms, the second polyitaconate also having an Mw of 4000. ∑~- : the second polyitaconate as contained in Additive E 1 . It will be noted that certain of the additives correspond to those used in the experiments described hereinbefore in this specification. There is not necessarily any relationship SUBSTITUTE SHEET between additives coded by the same letter whether with or without the superscript 1. An additive (which includes a combination of individual additive components as identified by juxtaposition of the code letters in the results hereinafter) was added to a Diesel fuel at an additive concentration of 200 ppm (ai) for additive A 1 , 200 ppm (al) for additive B 1 and 200 ppm (ai) for additive D^-, E-** or F-- , said additives being defined as above. The following tests were then carried out on the so-treated fuel: CFPP, WAS, and Determination of Crystal Size, each as described hereinbefore. The fuels used were fuels I to VIII whose characteristics are listed in Diagram 1 below, all temperatures being in °C. SUBSTITUTE SHEET DI FUEL PROPERTIES II III IV V VI VII VIII CO c -6 -5 -6 -7 -4 -4 03 +3 0) -4 -8 -8 -4 C -1 I O X i Test Temperature: ■ 17 ■ 15 -17 -17 ■ 15 -15 -15 -9 Additives A 1 , B 1 and D-^-F 1 , or combinations thereof, were, as stated above, tested in each of the fuels I - VIII. The results for CFPP, WAS and Crystal Size are shown in each of the following three tables, designated TABLES 4, 5, and 6 respectively where the following explanations are to be noted: TABLE 4 (CFPP) all results are negative values TABLE 5 (WAS) all results are percentage dispersed, 100 being fully dispersed and the observations being taken ' after 2 to 3 hours at the test temperature. TABLE 6 (Crystal Size) : all values are on a scale of 1 to 10 where The following general conclusions can be drawn from the results shown in TABLES 4-6: - Additives A 1 and A-^-E 1 (comparison examples) gave good CFPP performance but less good WAS and Crystal Size performance. Additives A^-B--D 1 and A--B--F-- gave good WAS and Crystal Size performance but regression in CFPP performance. The above regression was cured by Additive A^E 1 at least in Fuels I to V (fbp < 365°C) . SUBSTITUTE SHEET TABLE 4 (CFPP ) FU ADDITIVE I II III IV V VI VII VIII A 1 11 14 14 25 8 19 13 1C A---B 1 13 19 20 14 14 24 18 13 A^D 1 8 18 15 16 7 12 7 3 A^E 1 16 18 21 15 14 12 17 8 A^F 1 15 18 22 18 16 13 18 15 SUBSTITUTE SHEET - 53 - TABLE 5 (WAS ) FUEL ADDITIVE I II III IV V VI VII VIII A 1 20 20 40 20 30 15 40 20 A-LB 1 70 80 10 15 100 100 80 40 A 1 B 1 D 1 100 100 80 100 100 100 100 A 1 B 1 E 1 95 95 100 100 100 100 100 A 1 B 1 F 1 95 95 10 o 100 100 100 75 100 SUBSTITUTE SHEET - 54 - TABLE 6 (CRYSTAL SIZE) FUEL ADDITIVE I II III IV V VI VII VIII A 1 5 5* 7 8 5 6* 5 3 A 1 B 1 6 9 9 9 6 9 6 6 A^D 1 6 9 10 10 7 10 9 8 A^E 1 6 - 9 10 10 6 10 7 8 A-J-B-LF 1 5 9 10 10 5 10 5 6 * ALSO CONTAINED SMALL CRYSTALS SUBSTITUTE SHEET Lastly, cloud points of certain of the above fuels alone and when containing certain of the above-described additives were measured as described herein. Results obtained were as follows (in °C) : TABLE 7 (CLOUD POINT) FUEL ADDITIVE II IV VI VII None -7 -8 -5 -1 A 1 -7 -6 -5 -1 A-J-B 1 -8 -8 -8 -2 A 1 B 1 D 1 _ 8 _ 10 -10 -4 A 1 B 1 E 1 _ 8 _ 9 _ 9 - 2 K 1 1 F 1 . -8 -9 -9 -2 The results show that the additive compositions of the invention may give rise to cloud point depression. HEET

Claims: CLAIMS : The use as a low temperature flow improver in Distillate Fuel oil of a polymer of number average molecular weight 1,000 to 20,000 containing the repeating units: (I) (ID (III) (II) where x is an integer and y is 0 or an integer and wherein in the total polymer x + y is at least two and SUBSTITUTE SHEET the ratio of units (II) to units (I) is between 0 and 2, the ratio of units (II) to (III) is between 0 and 2, and wherein: R 1 and R-2, the same or different are C ] _o to C30 alkyl, R 3 is H, -OOC R β , C* ] _ to C 30 alkyl, -COO R°, an aryl or aralkyl group or halogen, R^ is H or methyl, R 5 is H, Ci to C 30 alkyl or -COOR 6 , R 6 is Ci to C22 alkyl and provided each of the groups R**-, R^, R3, R4. . R5 and R 6 can be inertly substituted. 2. The use according to claim 1 in which the polymer is a homopolymer of a dialkyl itaconate or citraconate or a copolymer of a dialkyl itaconate or citraconate with an aliphatic olefin, a vinyl ether, a vinyl ester of an alkanoic acid, an alkyl ester of an unsaturated acid, an aromatic olefin, a vinyl halide or a dialkyl fumarate or maleate. 3. The use according to claim 1 or claim 2 of a copolymer of dialkyl itaconates or dialkyl citraconates with an aliphatic olefin , a vinyl esters or an alkyl substituted vinyl esters of C2 to C3-L alkanoic acids, or when R 3 is an aryl group. 4. The use according to any of the preceding claims in which the molecular weight of the polymer is between 1,000 and 10,000. 5. The use according to any of the preceding claims wherein the low temperature flow improver includes at least two polymers as defined in claim 1, a first being selected to inhibit the tendency of wax to settle from the fuel at reduced temperature, and a second being different from the first and being selected to counter any tendency of the first to regress the CFPP performance of the fuel. 6. The use according to claim 5 wherein the first and second polymers are homopolymers of a dialkylitaconate, and the alkyl groups of the first polymer are the same as one another and the alkyl groups of the second polymer being the same as one another, those of the first polymer each having at least two carbon atoms fewer than those of the second. . The use according to claim 6 wherein each of the alkyl groups of the first polymer has 16 carbon atoms when each of those of the second polymer has 18 carbon atoms, or each of those of the first polymer has 18 carbon atoms when each of those of the second polymer has 20 carbon atoms . 8. The use according to any of the preceding claims in combination with another low temperature flow improver for distillate fuels. 9. The use according to claim 8 in which the other low temperature flow improver is a comb polymer as hereinbefore defined. 10. The use according to claim 8 or claim 9 in which the other low temperature flow improver is an ethylene unsaturated ester copolymer. 11. The use according to any of claims 8 to 10 in which the other low temperature flow improver is an amine salt and/or amide formed by reacting a hydrocarbyl SUBSTITUTE SHEET substituted amine with a hydrocarbyl acid having 1 to 4 carboxylic acid groups or corresponding anhydride groups. 12. Distillate Fuel oil containing from 0.0001 to 5.0 wt% of a polymer of number average molecular weight 1,000 to 20,000 containing the repeating units: (I) (ID (III) (ID SUBSTITUTE SHEET where x is an integer and y is 0 or an integer and wherein in the total polymer x + y is at least two and the ratio of units (II) to units (I) is between 0 and 2, the ratio of units (II) to (III) is between 0 and 2, and wherein: R and R~-, the same or different are C-_ Q to C 30 alkyl, R 3 is H, -OOC R β , C x to C30 alkyl, -COO R 6 , an aryl or aralkyl group or halogen, R 4 is H or methyl, R 5 is H, Ci to C30 alkyl or -COOR 6 , R 6 is C*]_ to C22 alkyl and provided each of the groups R-- r R^, R 3 , R 4 , R5 and R 6 can be inertly substituted. 13. Distillate Fuel according to claim 12 in which the polymer is a homopolymer of a dialkyl itaconate or citraconate or a copolymer of a dialkyl itaconate or citraconate with an aliphatic olefin, a vinyl ether, a vinyl ester of an alkanoic acid, an alkyl ester of an unsaturated acid, an aromatic olefin, a vinyl halide or a dialkyl fumarate or maleate. 14. Distillate Fuel according to claim 12 or claim 13 in which the polymer is a copolymer of dialkyl itaconates or dialkyl citraconates with an aliphatic olefin, a vinyl ester or an alkyl substituted vinyl ester of C2 to C31 alkanoic acid, or when R 3 is an aryl group. 15. Distillate Fuel according to any of claims 12 to 14 in which the molecular weight of the polymer is between 1,000 and 10,000. 16. Distillate Fuel according to any of claims 12 to 15 wherein the low temperature flow improver includes at SUBSTITUTE SHEET least two polymers as defined in claim 1, a first being selected to inhibit the tendency of wax to settle from the fuel at reduced temperature, and a second being different from the first and being selected to counter any tendency of the first to regress the CFPP performance of the fuel. 17. Distillate Fuel according to claim 16 wherein the first and second polymers are homopolymers of a dialkylitaconate, and the alkyl groups of the first polymer are the same as one another and the alkyl groups of the second polymer being the same as one another, those of the first polymer each having at least two carbon atoms fewer than those of the second. 18. Distillate Fuel according to claim 17 wherein each of the alkyl groups of the first polymer has 16 carbon atoms when each of those of the second polymer has 18 carbon atoms, or each of those of the first polymer has 18 carbon atoms when each of those of the second polymer has 20 carbon atoms. 19. Distillate Fuel according to any of claims 12 to 18 also containing another .low temperature flow improver for distillate fuels. 20. Distillate Fuel according to claim 19 in which the other low temperature flow improver is a comb polymer as hereinbefore defined. 21. Distillate Fuel according to claim 19 or claim 20 in which the other low temperature flow improver is an ethylene unsaturated ester copolymer. 22. Distillate Fuel according to any of claims 16 to 21 in which the other low temperature flow improver is an SUBSTITUTE SHEET amine salt and/or amide formed by reacting a hydrocarbyl substituted amine with a hydrocarbyl acid having 1 to 4 carboxylic acid groups or corresponding anhydride groups . 23. An additive concentrate comprising a solution containing from 20 to 80 wt% polymer of number average molecular weight 1,000 to 20,000 containing the repeating units: (I) (II) (III) (II) SUBSTITUTE SHEET where x is an integer and y is 0 or an integer and wherein in the total polymer x + y is at least two and the ratio of units (II) to units (I) is between 0 and 2, the ratio of units (II) to (III) is between 0 and 2, and wherein: R**- and R2, the same or different are C-j_o to C 30 alkyl, R 3 is H, -OOC R 6 , 0 to C30 alkyl, -COO R 6 , an aryl or aralkyl group or halogen, R 4 is H or methyl, R 5 is H, Ci to C30 alkyl or -COOR 6 , R 6 is Ci to C22 alkyl and provided each of the groups R 1 , R~-, R 3 , R 4 , R5 and R 6 can be inertly substituted. 24. An additive concentrate according to claim 23 in which the polymer is a homopolymer of a dialkyl itaconate or citraconate or a copolymer of a dialkyl itaconate or citraconate with an aliphatic olefin, a vinyl ether, a vinyl ester of an alkanoic acid, an alkyl ester of an unsaturated acid, an aromatic olefin, a vinyl halide or a dialkyl fumarate or maleate. 25. An additive concentrate according to claim 23 or claim 24 in which the copolymer is of dialkyl itaconates or dialkyl citraconates with an aliphatic olefin, a vinyl ester or an alkyl substituted vinyl ester of C2 to C31 alkanoic acids, alkyl esters of unsaturated acids, Ci to C22 dialkyl fumarates or maleates, or when R3 is an aryl group. 26. An additive concentrate according to any of claims 23 to 25 in which the molecular weight of the polymer is between 1,000 and 10,00. SUBSTITUTE SHEET 27. An additive concentrate according to any of claims 23 to 26 wherein the low temperature flow improver includes at least two polymers as defined in claim 1, a first being selected to inhibit the tendency of wax to settle from the fuel at reduced temperature, and a second being different from the first and being selected to counter any tendency of the first to regress the CFPP performance of the fuel. 28. An additive concentrate according to claim 27 wherein the first and second polymers are homopolymers of a dialkylitaconate, and the alkyl groups of the first polymer are the same as one another and the alkyl groups of the second polymer being the same as one another, those of the first polymer each having at least two carbon atoms fewer than those of the second. 29. An additive concentrate according to claim 28 wherein each of the alkyl groups of the first polymer has 16 carbon atoms when each of those of the second polymer has 18 carbon atoms, or each of those of the first polymer has 18 carbon atoms when each of those of the second polymer has 20 carbon atoms. 30. An additive concentrate according to any of claims 23 to 29 in combination with another low temperature flow improver for distillate fuels. 31. An additive concentrate according to claim 30 in which the other low temperature flow improver is a comb polymer as hereinbefore defined. 32. An additive concentration according to claim 30 or claim 31 in which the other low temperature flow improver is an ethylene unsaturated ester copolymer. SUBSTITUTE SHEET 33. An additive concentration according to any of claims 30 to 32 in which the other low temperature flow improver is an amine salt and/or amide formed by reacting a hydrocarbyl substituted amine with a hydrocarbyl acid having 1 to 4 carboxylic acid groups or corresponding anhydride groups. 34. A polymer of number average molecular weight 1,000 to 20,000 containing the repeating units: (I) (ID (iii; ;n: SUBSTITUTE SHEET where x is an integer and y is 0 or an integer and wherein in the total polymer x + y is at least two and the ratio of units (II) to units (I) is between 0 and 2, the ratio of units (II) to (III) is between 0 and 2, and wherein: R 1 and R 2 , the same or different are C-]_o to C 30 alkyl, R 3 is H, -OOC ' R 6 , C*]_ to C 30 alkyl, -COO R 6 , an aryl or aralkyl group or halogen, R 4 is H or methyl, R 5 is H, Ci to C30 alkyl or -COOR 6 , R 6 is C__ to C22 alkyl and provided each of the groups R 1 , R 2 , R 3 , R 4 , R5 and R 6 can be inertly substituted. 35. A process for improving the low temperature performance of a Distillate Fuel Oil which comprises incorporating into the oil an additive comprising a polymer as defined in claim 34. SUBSTITUTE SHEET

Inventors: BLAND JACQUELINE DAWN, LEWTAS KENNETH, BLAND, JACQUELINE, DAWN, LEWTAS, KENNETH
Applicants: EXXON CHEMICAL LTD, EXXON CHEMICAL PATENTS INC, EXXON CHEMICAL LIMITED, EXXON CHEMICAL PATENTS INC.
Application year: 1991
Main classification: C10L1
IPC codes: C08L33, C10L1, C10L10