KR100190266B1 - Additives for distillate fuels and distillate fuels containing them - Google Patents

Abstract

It has been found that polymers of 1,000 to 20,000 with number average molecules containing the following repeating units are particularly useful as cold flow improvers for distillate fuels by mixing with other additives.

Wherein x is an integer, y is 0 or an integer, the sum of x in the entire polymer is at least 2, the ratio of unit (II) to unit (I) is 0 to 2, and unit (II) to unit ( III) ratio is 0 to 2, R ¹ and R ² are the same or different and C ₁₀ to C ₃₀ alkyl, R ³ is H, -OOCR ⁶ , C ₁ to C ₃₀ alkyl, -COOR ⁶ , aryl or ar Alkyl group or halogen, R ⁴ is H or methyl, R ⁵ is H, C ₁ to C ₃₀ alkyl or -COOR ⁶ , R ⁶ is C ₁ to C ₂₂ alkyl, provided that R ¹ , R ² , R ^{The 3} , R ⁴ , R ⁵ and R ⁶ groups may each be inactively substituted.

Description

Additives for distillate fuels and distillate fuels containing the same

The present invention relates to oils and fuel oil compositions to which novel polymers and flow modifiers useful as flow modifiers for fuel oils have been added.

When the oil and fuel oil are at low ambient temperatures, the wax separates and impairs fluidity unless cold flow improvers are added. The properties of the wax vary depending on the type of fuel, and the present invention relates, in particular, to additives for treating distillate fuels which precipitate linear alkanes wax that form large plates that clog fuel lines and filters in the absence of additives.

FIELD OF THE INVENTION The present invention relates to waxes containing distillate fuel treated with additives, wherein the size and structural shape of the additives correspond in particular to the crystallography of the wax crystals that form in the distillate fuel as it cools, so that the additives act with these waxes during crystallization. Produces precipitated wax with reduced crystal size.

Mineral oils containing paraffin wax have poor fluidity as the oil temperature decreases. This loss of fluidity is due to the crystallization of the wax into plate crystals that ultimately form an oil-collected sponge mass. The temperature at which the wax crystals begin to form is known as the cloud point, and the temperature at which the wax blocks the flow of oil is known as the pour point. However, between these temperatures wax crystals can clog filters and pipes, making systems such as diesel trucks and household heating systems inoperable. The efficiency of the additives to improve operability at low temperatures can be measured by tests such as CFPP and PCT, as well as their ability to suppress clouding points and wax appearance points.

It has long been known that various additives act as wax crystal modifiers when blended with waxy mineral oil. These compositions modify the size and shape of the wax crystals and in between the crystals in such a way as to allow the oil to remain fluid at lower temperatures and in some cases to improve the filtration capacity at temperatures between the cloud point and the pour point And reduces cohesion between wax and oils.

Various pour point inhibitors are described in the literature, some of which are commercially available. For example, US Pat. No. 3,038,479 teaches the use of copolymers of ethylene and C ₁ to C ₅ vinyl esters (eg vinyl acetate) as flow inhibitors for fuels, particularly heating oils, diesel and jet fuels. have. Hydrocarbon polymer flow inhibitors based on ethylene and higher alpha-olefins (eg propylene) are also known.

U. S. Patent No. 3,961, 916 suggests that the size of the wax crystals can be controlled. The system of the above patent documents all has a pore in the filter by forming a porous cake on the filter, rather than plate crystals formed in the absence of additives, in which the resulting needle-shaped wax crystals can form passages of residual fluid. Since it does not clog, it improves the ability of the fuel to pass through the filter as determined by the Cold Filter Plugging Point (CFPP).

In addition, other additives have been proposed. For example, British Patent No. 1,469,016 discloses copolymers of di-n-alkyl fumarate and vinyl acetate which are already used as flow inhibitors for lubricating oils in the treatment of distillate fuels having a high final boiling point to improve low temperature fluidity. It is proposed that it can be used as a co-additive with vinyl acetate copolymer.

U.S. Patent No. 3,252,771 is a flow inhibitor in a wide range of boiling point distillate fuels commercially available in the United States in the early 1960s, predominantly present in aluminum trichloride / halogenated alkyl catalysts and linear C ₁₆ to C ₁₈ alpha-olefins. It relates to the use of C ₁₆ to C ₁₈ alpha-olefin polymers obtained by polymerizing olefinic mixtures.

Moreover, the use of the additive which has an olefin / maleic anhydride copolymer as a main component is also proposed. For example, US Patent No. 2,542,542 uses copolymers of olefins, such as maleic anhydride and octadecene, esterified with alcohols such as lauryl alcohol, as a flow inhibitor, and in UK Patent No. 1,468,558 As a fuel additive, a copolymer of maleic anhydride esterified with behenyl alcohol and C ₂₂ to C ₂₈ olefins is used.

Similarly, Japanese Patent Publication No. 5,654,037 uses an olefin / maleic anhydride copolymer reacted with an amine as the pour point inhibitor, and Japanese Patent Publication No. 5,654,038 uses a conventional intermediate distillation such as ethylene vinyl acetate copolymer. Derivatives of olefin / maleic anhydride copolymers are used with flow improvers.

Japanese Patent Publication No. 5,540,640 describes the use of olefin / maleic anhydride copolymers (not esterified) and states that the olefins used must contain more than 20 carbon atoms to obtain CFPP activity. Doing.

In British Patent 2,129,012 a mixture of esterified olefin / maleic anhydride copolymers and low molecular weight polyolefins is used because of the inefficiency of the esterified copolymer when used as a single additive. The patent states that the olefin should contain 10 to 30 carbon atoms and the alcohol should contain 6 to 28 carbon atoms (the long chain in alcohol contains 22 to 40 carbon atoms).

U.S. Patent Nos. 3,444,082, 4,211,534, 4,375,973, and 4,402,708 propose the use of any nitrogen containing compound.

In addition, long n-alkyl derivatives of bifunctional compounds, in particular alkenyl succinic acid (US Patent No. 3444082, maleic acid (US Patent No. 4211534)) and phthalic acid (UK Patent No. 2923645, US Patent No. 4375973 and US Patent) Amine derivatives of 4402708) are also used as wax crystal modifiers for distillate fuels.Amine salts of any alkylated aromatic sulfonic acids are described in British Patent No. 1209676, which are used in turbine oil and It is used as an antirust additive for hydraulic oil.

The improvement in CFPP activity achieved by combining the additives of this patent document is generally achieved by modifying the size and shape of the wax crystals formed to produce needle-like crystals with a particle size of 10,000 nm or more, typically 30,000 to 100,000 nm. . When operating a diesel engine or heating system at low temperatures, these crystals generally do not pass through the filter, but rather form a permeable cake on the filter that can pass liquid fuel, and the wax crystals subsequently heat the engine and fuel. As it is dissolved, this dissolution can be performed by heating the bulk fuel with the recycled fuel. However, wax crystals can clog the filter, causing problems when driving in cold weather, or causing the fuel heating system to fail.

In European Patent Publication No. 0225688, Applicant is suitable as a flow improver or effective for improving the cooling fluidity of fuel oils and oils (crude oil or lubricating oils) such as middle distillate fuels and jet fuels, which are residual fuels, or suitable for particular oils or fuel oils involved. The use of itaconate and citraconate polymers and copolymers as a dewaxing aid in lubricating oils that can be made is described. These polymers and copolymers are described as having a number average molecular weight of 1,000 to 500,000 as measured by gel permeation chromatography, and the particular material illustrated has a molecular weight of at least 20,000.

In particular, European Patent Publication No. 0225688 provides crude, lubricating or fuel oils containing a small amount (by weight) of polymer having the following units.

Wherein x is an integer, y is 0 or an integer, the sum of x and y in the entire polymer is at least 2, the ratio of units (II) to units (I) is 0 to 2, and units (II) to units The ratio of (III) is 0 to 2, R ¹ and R ² are the same or different and are C ₁₀ to C ₃₀ alkyl, R ³ is H, -OOCR ⁶ , C ₁ to C ₃₀ alkyl, -COOR ⁶ , -OR ⁶ , aryl or alkaryl group or halogen, R ⁴ is H or methyl, R ⁵ is H, C ₁ to C ₃₀ alkyl, or -COOR ⁶ , R ⁶ is C ₁ to C ₂₂ alkyl, R ^{The 1} , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ groups may each be inactively substituted as necessary.

Recently, applicants have found that the use of polymers and copolymers of the above general formula having a number average molecular weight in the range of 1,000 to 20,000 as additives for distillate fuels can result in formation in fuels for wax crystals that are particularly smaller than those obtained with high molecular weight homologues. Found that it can. In addition, Applicants have found that the effect is particularly pronounced when using low molecular weight polymers and copolymers with other types of additives.

Therefore, the present invention provides the use of a polymer having a number average molecular weight of 1,000 to 20,000 having the following repeating unit as a flow improving agent in distillate fuel oil.

Wherein x is an integer, y is 0 or an integer, the sum of x and y in the entire polymer is at least 2, the ratio of units (II) to units (I) is 0 to 2, and units (II) to The ratio of units (III) is 0 to 2, R ¹ and R ² are the same or different and are C ₁₀ to C ₃₀ alkyl, R ³ is H, -OOCR ⁶ , C ₁ to C ₃₀ alkyl, -COOR ⁶ , aryl Or an aralkyl group or halogen, R ⁴ is H or methyl, R ⁵ is H, C ₁ to C ₃₀ alkyl, or -COOR ⁶ , R ⁶ is C ₁ to C ₂₂ alkyl, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ groups may each be inactively substituted.

The present invention further provides an additive concentrate comprising a polymer solution as defined above suitable for incorporation into distillate fuels containing the polymer as defined above and distillate fuel.

Preferred polymers are homopolymers of dialkyl itaconates or citraconates, or aliphatic olefins, vinyl ethers, vinyl esters of alkanoic acids, alkyl esters of unsaturated acids, aromatic olefins, halogenated vinyls, or dialkyl fumarates or maleates. Copolymers of dialkyl itaconate or citraconate.

R ¹ and R ² groups, which may be the same or different, are C ₁₀ to C ₃₀ alkyl groups, which may be branched, but are preferably straight chain. If these groups are branched, it is preferred that the side chain is single methyl in the 1 or 2 position. Examples of R ¹ and R ² groups are decyl, dodecyl, hexadecyl and eicosyl. The R ¹ and R ² groups may each be a single C ₁₀ to C ₃₀ alkyl group or may be a mixture of alkyl groups. Mixtures of C ₁₂ to C ₂₀ alkyl groups have been found to be particularly suitable when the polymer is used as a flow improver in middle distillate fuel oils. Similarly, suitable chain lengths are C ₁₆ to C ₂₂ for use of polymers in heavy fuel oils and crude oils and C ₁₀ to C ₁₈ for use of polymers in lubricating oils. These preferred chain lengths are applicable to both homopolymers and copolymers.

At least two polymers as defined in the present invention may be used together to benefit certain embodiments of the present invention. Therefore, as demonstrated later by the examples, the first polymer can be selected to suppress the tendency of the wax to settle out of the distillate at reduced temperatures, and a second polymer different from the first polymer can be used to improve the CFPP performance of the fuel. It may be chosen to counter any tendency of the first polymer to inhibit. For example, such first and second polymers are homopolymers of dialkylitaconates in which the alkyl groups of the first polymer are identical to each other and the alkyl groups of the second polymer are identical to each other (the alkyl groups of the first polymer are each second). At least two (preferably two) fewer carbon atoms than the alkyl group of the polymer). Examples of such first polymers are those in which the alkyl groups (ie, R ¹ and R ² in the general formula herein) are C ₁₄ or C ₁₆ or C ₁₈ . Alkyl group of the first polymer as the specific examples is an alkyl group of the second polymer when C ₁₈ C _16, alkyl group of the first polymer is the alkyl group of the second polymer when C ₂₀ C _18.

In certain embodiments described above, the ratio of the first polymer to the second polymer may be in the range of, for example, 10: 1 to 1:10. When using one or more other flow modifiers (described later), the ratio of such flow modifiers to the first and second polymers may be in the range of, for example, 10: 1 to 1:10.

By way of example, the ratio of the first polymer to the second polymer is 1: 1 and their bonding ratio to other flow modifiers is also 1: 1. All of these ratios are weight: weight.

When the copolymer of dialkyl itaconate or dialkyl citraconate uses y as an integer, the above-mentioned comonomer is a compound of the following general formula.

Wherein R ³ , R ⁴ and R ⁵ are as defined above.

Such comonomers may be one or more of various compounds, and in all cases, mixtures of compounds having the above general formula may be used.

When the comonomer is an aliphatic olefin, R and R are hydrogen or C ₁ to C ₃₀ alkyl groups, identical or unequal, preferably n-alkyl groups. Therefore, the olefin is ethylene when R ³ , R ⁴ and R ⁵ are all hydrogen, the olefin is n-propylene when R ³ is methyl and R ⁴ and R ⁵ are hydrogen. When R ³ is an alkyl group, R ⁴ and R ⁵ are preferably 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 C ₂ to C ₃₁ alkanoic acid. That is, vinyl ester when R ³ is R ⁶ COO-, R ⁴ is H and R ⁵ is H, R ³ is R ⁶ COO-, R ⁴ is methyl and / or R ⁵ is C ₁ to C ₃₀ alkyl Is an alkyl substituted vinyl ester. Unsubstituted vinyl esters are preferred and suitable examples are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl decanoate, vinyl hexadecanoate and vinyl stearate.

Another class of comonomers are alkyl esters of unsaturated acids when R ³ is R ⁶ OOC- and R ⁵ is H or C ₁ to C ₃₀ alkyl. These comonomers are alkyl esters of acrylic acid when R ⁴ and R ⁵ are hydrogen. The comonomer when R ⁴ is methyl is an ester of methacrylic acid or C ₁ to C ₃₀ 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, while methacryl Suitable examples of alkyl esters of acids include propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, n-tetradecyl methacrylate, n-hexadecyl methacrylate and n-octadecyl methacrylate. to be. Other examples are the corresponding esters where R ⁵ is alkyl, eg 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-, ie they are C ₁ to C ₂₂ dialkyl fumarate or maleate, and the alkyl group is n-alkyl or branched alkyl, eg For example n-octyl, n-decyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

Another example of a comonomer is when R ³ is an aryl group. When R ⁴ and R ⁵ are hydrogen and R ³ is phenyl, the comonomer is styrene and when one of R ⁴ and R ⁵ is methyl, the comonomer is methyl styrene. When R ³ is aryl, another example is vinyl naphthalene. Other suitable examples when R ³ is alkaryl are substituted styrenes such as, for example, vinyl toluene or 4-methyl styrene.

Another suitable comonomer is such as vinyl chloride when R ³ is halogen, such as chlorine (R ⁴ and R ⁵ are hydrogen).

In all cases, some or all of the groups R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be unsaturated by, for example, one or more halogen atoms, for example chlorine or fluorine. You must understand that you can. Thus, for example, the comonomer can be vinyl trichloroacetate. In addition, the substituent may be an alkyl group, for example methyl.

The ratio of unit (II) to unit (I) should be between 0 (when the polymer is an itaconate or citraconate homopolymer) and 2 (when the polymer is a copolymer), but in practice the ratio in the copolymer is usually It will be between 0.5 and 1.5. Generally, the copolymer consists only of units (I) and (II) or units (II) and (III), but other units are not excluded. However, in practice the weight percent of units (I), (II) and (III) in the copolymer is at least 60%, preferably at least 70%.

For both homopolymers and copolymers the molecular weight of the polymer is between 1,000 and 20,000, preferably between 1,000 and 10,000, more preferably between 2,200 and 5,000. It has been found that certain small wax crystals are obtained in distillate fuel when using polymers or copolymers of molecular weight in the above range. Molecular weight is determined by gel permeation chromatography (GPC) on polystyrene standards.

Homopolymers and copolymers generally polymerize monomers in solution in hydrocarbon solvents such as heptane, benzene, cyclohexane or white oil at a general temperature ranging from 20 ° C. to 150 ° C., or polymerize the monomers themselves. It is generally promoted with a catalyst in the form of a peroxide or azo, such as benzoyl peroxide or azodiisobutyronitrile, under a blanket of an inert gas such as nitrogen or carbon dioxide to exclude oxygen. The polymer may be prepared under pressure in an autoclave or by reflux.

When preparing the copolymer, the polymerization reaction mixture should preferably contain up to 2 moles of comonomer (eg vinyl acetate) per mole of polyalkyl itaconate or dialkyl citraconate.

The copolymers are suitable for use as cold flow improvers in fuel oils. Such fuel oils may be intermediate distillate fuel oils such as diesel fuel, aviation fuel, kerosene, fuel oil, jet fuel, heating oil and the like. Generally suitable distillate fuels boil in the range of 120 ° to 500 ° C. (ASTM D-86), preferably in the range of 150 ° to 400 ° C., for example, relatively high final boiling points (FBP above 360 ° C.). ) Typical heating oils require 10% distillation point below about 226 ° C, 50% distillation point below about 272 ° C and 90% distillation point above 282 ° C and below about 338 ° C to 343 ° C. 90% distillation point is required at temperatures as high as ° C. The heating oil is preferably made of a blend of virgin distillates such as gas oil, naphtha and the like and fractionated distillates such as contact cycle raw materials. Diesel fuel typically requires a minimum flash point of 38 ° C and a 90% distillation point between 282 ° C and 338 ° C (see ASTM Designations D-396 and D-975).

Best results are generally obtained when the polymer additives of the present invention are used in combination with other additives known to improve the cold flowability of distillate fuels. However, the polymer additive of the present invention can also be used by itself.

The additives of the present invention are particularly effective when used with comb polymers of the general formula

Wherein D is R, C (O) .OR, OC (O) .R, R ¹ C (O) .OR or OR, E is H or CH ₃ or D or R ¹ , and G is H or D, m is 1.0 (homopolymer) to 0.4 (molar ratio), J is H, R ¹ , aryl or heterocyclic group, R ¹ CO.OR, K is H, C (O) .OR ¹ , OC (O) .R ¹ , OR ¹ , C (O) OH, L is H, R ¹ , C (O) .OR ¹ , OC (O) .R ¹ , aryl, C (O) OH, n Is 0.0 to 0.6 (molar ratio), R is a hydrocarbyl group containing 10 or more, preferably 10 to 30, carbon atoms, and R ¹ is a C ₁ to C ₃₀ hydrocarbyl group.

The comb polymer may contain ternary comonomers.

Examples of suitable comb polymers are fumarate / vinyl acetate, in particular those described in Applicants' European Patent Publication Nos. 0153176, 0153177 and polymers and copolymers and styrenes of esterified olefin / maleic anhydride copolymers and alpha olefins. And esterified copolymers with maleic anhydride.

Examples of other additives that may be included in the compositions of the invention include polyoxyalkylene esters, ethers, esters / ether amides / esters and mixtures thereof, in particular polyoxyalkylenes having a molecular weight of 100 to 5,000, preferably 200 to 5,000. And those containing one or more, preferably two or more, C ₁₀ to C ₃₀ linear saturated alkyl groups of the glycol group (the alkyl group in the polyoxyalkylene glycol contains 1 to 4 carbon atoms). European Patent Publication No. 0,061,895 A2 discloses some of these additives.

Preferred esters, ethers or esters / ethers can be described structurally by the following general formula, which may allow some branching (as in polyoxypropylene glycols) to lower alkyl side chains, but the glycols are substantially linear desirable.

R-O-(A)-O-R ¹

Wherein R and R ¹ are the same or different,

Iii) n-alkyl

Ii)

Ⅲ)

Ⅳ) Wherein the alkyl group is linear and saturated and contains from 10 to 30 carbon atoms, and A is an alkylene, such as a substantially linear polyoxymethylene, polyoxyethylene or polyoxytrimethylene moiety, and the like. The group represents a polyoxyalkylene segment of glycols having 1 to 4 carbon atoms.

Suitable glycols are generally substantially linear polyethylene glycol (PEG) and polypropylene glycol (PPG) having a molecular weight of about 100 to 5,000, preferably about 200 to 2,000. Esters are preferred, and fatty acids containing 10 to 30 carbon atoms are useful for reacting with glycols to form ester additives, and preference is given to using C ₁₈ to C ₂₄ fatty acids, in particular behenic acid. These esters can also be prepared by esterifying polyethoxylated fatty acids or polyethoxylated alcohols. A may also contain nitrogen, in which case the material can be obtained by esterification of an ethoxylated amine.

Other suitable additives included in the fuel composition of the present invention are ethylenically unsaturated ester copolymer flow improving agents. Unsaturated monomers that can be copolymerized with ethylene include unsaturated mono and diesters of the general formula:

Wherein R ⁸ is hydrogen or methyl, and R ⁷ is —OOCR ¹⁰ group, wherein R ¹⁰ is hydrogen or C ₁ to C ₂₈ , more generally C ₁ to C ₁₇ , preferably C ₁ to C ₈ straight chain Or a branched chain alkyl group, or a -COOR ¹⁰ group, wherein R ¹⁰ is as defined above except for hydrogen, and R ⁹ is hydrogen or -COOR ¹⁰ , wherein R ¹⁰ is as defined above to be.

When R ⁷ and R ⁹ are hydrogen and R ⁸ is —OOCR ¹⁰ , the monomers are C ₁ to C ₂₉ , more commonly C ₁ to C ₁₈ monocarboxylic acids and preferably C ₂ to C ₂₉ , more commonly C ₁ to Vinyl alcohol esters of C ₁₈ mono carboxylic acids and preferably C ₂ to C ₅ monocarboxylic acids. Examples of vinyl esters that can be copolymerized with ethylene include vinyl acetate, vinyl propionate and vinyl butyrate or isobutyrate, with vinyl acetate being preferred. The copolymer preferably contains 10 to 40% by weight of vinyl esters, more preferably 25 to 35% by weight of vinyl esters. They may also be mixtures of two copolymers, such as those described in US Pat. No. 3,961,916. It is preferred that these copolymers have a number average molecular weight of 1,000 to 6,000, preferably 1,000 to 4,000, as measured by a vapor osmometer.

Other suitable additives included in the fuel composition of the present invention are polar compounds that are ionic or nonionic having the ability to act as a wax crystal growth inhibitor in the fuel. These polar compounds are generally amine salts and / or amides formed by the reaction of at least 1 mole of hydrocarbyl acid with 1 to 4 carboxylic acid groups or anhydrides thereof and at least 1 mole of hydrocarbyl substituted amines, and also have a total of 30 to 300 carbon atoms. Ester / amides containing dogs, preferably 50 to 150, can also be used. These nitrogen compounds are described in US Pat. No. 4,211,534. Suitable amines are commonly primary, secondary, tertiary or quaternary amines of long chain C ₁₂ to C ₄₀ , or mixtures thereof, but the nitrogen compounds obtained are oil soluble and usually contain about 30 to 300 total carbon atoms. Shorter chain amines can also be used. The nitrogen compound preferably contains at least one alkyl segment of straight chain C ₈ to C ₄₀ , preferably C ₁₄ to C ₂₄ .

Suitable amines include primary, secondary, tertiary or quaternary, but preferred are secondary amines. Tertiary and quaternary amines can only form amine salts. Examples of the amine include tetradecyl amine, cocoamine, hydrogenated tallow amine and the like. Examples of secondary amines include dioctadecylamine, methyl-benhenyl amine, and the like. Amine mixtures are also suitable, and many of the amines derived from natural substances are mixtures. Preferred amines are _secondary hydrogenation of the general formula NHR ₁ R ₂ , wherein R ₁ and R ₂ are alkyl groups derived from hydrogenated tallow fat consisting of about 4% C ₁₄ , 31% C ₁₆ , 59% C ₁₈ Tallow amine.

Examples of carboxylic acids or anhydrides thereof suitable 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 have about 5 to 13 carbon atoms in the cyclic moiety. Preferred acids are benzene dicarboxylic acids such as phthalic acid, terephthalic acid, iso-phthalic acid and the like. Phthalic acid or its anhydride is particularly preferred. Also, alkyl substituted succinic acid or anhydride can be used. Particularly preferred compounds are the amide-amine salts formed by the reaction of 2 moles of dihydrogenated tallow amine with 1 mole of phthalic anhydride. Another preferred compound is diamide formed by dehydrating such amide-amine salts.

Examples of other suitable simultaneous additives include the compounds described in European Patent Application No. 0261957, which is a compound of the general formula:

Wherein 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 are aromatic, cycloaliphatic Or may constitute part of a cyclic structure that may be mixed aromatic / alicyclic, provided that when A, B and L do not form part of the cyclic structure, one of A or B may be hydrogen, and L When this non-cyclic ethylene, the XX ¹ and YY ¹ groups are in cis-coordination, X is SO ₃ ^(-) , -C (O)-, C (O) O ^(-) , -R ^4- C (O) O-, -NR ³ C (O)-, -R ⁴ O-, R ⁴ OC (O)-, -R ⁴ -or -NC (O)-, and X ¹ Silver N ⁽⁺⁾ R ₃ ³ R ² , HN ⁽⁺⁾ R ³ R ₂ ² , H ₂ N ⁽⁺⁾ R ³ R ² , H ₃ N ⁽⁺⁾ R ² , N ⁽⁺⁾ R ₃ ³ R ¹ , N ⁽⁺⁾ HR ₂ ³ R ¹ , H ₂ N ⁽⁺⁾ R ³ R ¹ , H ₃ N ⁽⁺⁾ R ¹ , NR ³ R ² , -R ² , -NR ³ R ¹ , or R ¹ Selected from the group consisting of y is -SO ₃ ^(-) or -SO ₂ -and Y is SO ₃ ^{When (-)} , Y ¹ is N ⁽⁺⁾ R ₃ ³ R ² , HN ⁽⁺⁾ R ₂ ³ R ² , H ₂ N ⁽⁺⁾ R ³ R ² , H ₂ N ⁽⁺⁾ R ² , Y When is —SO ₂ —, Y ¹ is —OR ² , —NR ³ R ² or —R ² , and R ¹ and R ² are each alkyl, typically C ₁₀ to C ₄₀ alkyl, more preferably C ₁₀ to C ₃₀ alkyl, most preferably C ₁₄ to C ₂₄ alkyl, alkoxyalkyl, or a polyaxoxyalkyl group containing at least 10, typically 10 to 40 carbon atoms in the backbone thereof, R ³ is hydro Carbyls, preferably alkyl, more preferably C ₁ to C ₃₀ , most preferably C ₁₀ to C ₃₀ straight chain alkyl, R ³ may each be the same or different and R ⁴ is n is from 0 to 5 — (CH ₂ ) _n .

X ¹ and Y ¹ together preferably contain at least three alkyl, alkoxy alkyl or polyalkoxy alkyl groups.

In these compounds A and B together or individually form one or more mass groups, L is a binding group which may also be part of the mass group, X and / or Y are a coordination group, and X ¹ and / or Y ¹ are It constitutes an absorption group.

When L is part of a cycled structure together with A and B, the cycled structure may be aromatic, cycloaliphatic or mixed aromatic / alicyclic. More specifically, the cyclic structure may be mono-cyclic or polycycle aromatic, multinuclear aromatic, heteroaromatic and heteroalicyclic. The ring structure may be saturated or one or more may be unsaturated, but at least one ring contains four or more atoms, may be multi-cycled, crosslinked, and substituted. When the cyclic structure is heterocyclic, the structure may comprise one or more N, S or 0 atoms.

Examples of suitable monocyclic ring structures are benzene, cyclohexane, cyclohexene, cyclopentane, pyridine and furan. The ring structure may contain additional substituents.

Suitable polycycle type compounds, those having two or more ring structures, can have various forms. These compounds include (a) fused aromatic structures, (b) fused partially hydrogenated aromatic ring structures (where not all rings are at least one aromatic), (c) are fused alicyclic, crosslinked alicyclic, spiro alicyclic (A) to (e), containing a cycloaliphatic, (d) aromatic, cycloaliphatic, or hydrocarbon ring combination of the same or unequal rings comprising a group compound and (e) at least one heteroatom It may be one of the.

Fused aromatic structures from which compounds broadly defined by L, A and B can be derived include, for example, naphthalene, anthracene, phenanthrene, fluorene, parene and indene. Suitable condensed ring structures in which all rings are not benzene or all are not benzene include, for example, azulene, hydronaphthalene, hydroindene, hydrofluorene, diphenylene.

Suitable crosslinked cycloaliphatic structures include bicycloheptane and bicycloheptene.

Suitable combinations include biphenyl and cyclohexyl benzene.

Suitable heteropolycycle-type structures include quinuclidin and indole.

Suitable heterocyclic compounds, broadly defined by L, A and B, from which the compounds of the present 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, broadly defined by L, A and B, include decalin (decahydronaphthalene), pinene, cardinene, bornylene. Suitable crosslinked compounds include norbornene, bicycloheptane (norbornane), bicyclo octane and bicyclooctene.

When L, A and B form part of a cyclic structure, it is preferred that X and Y be bonded to adjacent reducers located completely within a single ring, whether monocyclic or polycycle. For example, if naphthalene should be used, these substituents are not bonded at the 1,8- or 4,5-positions, but 1,2-, 2,3-, 3,4-, 5,6-, 6, It must be bound to the 7- or 7,8-position

When L is ethylene and together with A and B are not part of the ring, the hydrogen and carbon-containing groups in substituents A and B are preferably alkyl, typically C ₁ to C ₂₄ alkyl or alkenyl, aryl, typically C ₆ to C ₄ aryl. In addition, such groups may preferably be halogenated to contain small amounts of halogen atoms (eg chlorine atoms), eg less than 20% by weight of halogen atoms. A and B groups are preferably aliphatic, for example alkylene. These are preferably straight chains. Unsaturated hydrocarbyl groups such as alkenyl can be used, but are not preferred.

When using the compound as a distillate fuel additive, Applicants have found that R ¹ , R ² and R ³ contain 10 to 24 carbon atoms, for example 14 to 22, preferably 18 to 22, and 1 or 2 It is preferred to be straight or branched in position. Suitable alkyl groups include decyl, dodecyl, tetradecyl, eicosyl and docosyl (behenyl). In addition, the group may be polyethylene oxide or polypropylene oxide, where the main chain of the group is the longest linear segment.

Particularly preferred compounds are the amide or amine salts of secondary amines. While two substituents are required for the cyclic derivatives described above, it should be appreciated that these cyclic compounds may contain one or more additional substituents bonded to their ring atoms.

These compounds can be prepared from reactants such as the following general formulas.

Wherein A, B, L are as defined above, X ² and Y ² are as defined for X and Y, and additionally X ² and Y ² together are both X oxy groups (O) It can form part of a cyclic anhydride structure that is common to ² and Y ² .

Preferred reactants are those wherein X ² is selected from —C (O) O— and —SO ₃ ⁽⁻⁾ , particularly preferred reactants are compounds of the general formula:

Most preferred reactants are compounds in which A, B and L together are part of a cyclic structure, in particular an aromatic ring, with particularly preferred reactants represented by the following general formula.

In the above formula, the aromatic ring may be substituted, and collectively represent A, B and L, and X ² and Y ² together form an anhydride ring.

These compounds are prepared by the reaction of both Y ² -H groups and X ² -H groups with amines, alcohols, quaternary ammonium salts and the like or mixtures thereof. If the final compound is an amide or amine salt, they are groups containing carbon and hydrogen containing at least 10 carbon atoms, preferably straight chain alkyl groups containing 10 to 30, more preferably 16 to 24 carbon atoms. It is preferable that it is a secondary amine containing. Such amides or salts may be prepared by the reaction of acids or anhydrides with secondary amines, or by reaction with amine derivatives. Removal and heating of water are generally required to prepare the amide from the acid. In addition, the Y ² -H and X ² -H groups can react with alcohols or mixtures of amines with alcohols containing at least 10 carbon atoms, or with amines and alcohols in series, or vice versa. .

Therefore, the final additive compounds include amides, ethers, primary, secondary or tertiary amine salts, amino amides, amino ethers and the like as a result of the identity of the XX ¹ and YY ¹ esters.

Preferred compounds of this type are

And a more preferable compound is a general formula

And Compound.

Hydrocarbon polymers may also be used in the additive mixtures of the present invention, which may be compounds of the general formula:

Wherein T is H or R ¹ , U is H, T or aryl, v is 1.0 to 0.0 (molar ratio) and w is 0.0 to 1.0 (molar ratio).

These polymers can be prepared directly from ethylenically unsaturated monomers or indirectly by hydrogenating polymers made from monomers such as isoprene, butadiene and the like.

Particularly preferred hydrocarbon polymers are copolymers of propylene and ethylene having an ethylene content of 20 to 60% (w / w) and are usually prepared by uniform catalysis.

One or more of these simultaneous additives may be used in the compositions of the present invention.

When using a mixture of additives, the relative amounts of additives used in the mixture are preferably 0.05 to 20 parts by weight, more preferably 0.1 to 5 parts by weight of itaconate or citraconate polymer or copolymer to 1 part of other additives.

The total amount of additives added to the fuel oil is preferably 0.0001 to 5.0% by weight, for example 0.001 to 0.5% by weight, based on the weight of the fuel oil (active material).

The additives may be dissolved in a suitable solvent, generally to form a concentrate of 20 to 90, such as 30 to 80% by weight of the polymer in the solvent.

Suitable solvents include kerosene, aromatic naphtha, inorganic lubricants and the like. Such concentrates are also within the scope of the present invention.

The invention is illustrated by the following examples using the following additives.

[Additive A]

N, N-dialkyl ammonium salt of 2-dialkylamidobenzene sulfonate with alkyl group nC _16-18 H _33-37 .

This ammonium salt is prepared by the reaction of 2 moles of di- (hydrogenated) tallow amine in xylene solvent with 1 mole of ortho-sulfobenzoic acid cyclic anhydride at 50% (w / w) concentration. The reaction mixture is stirred at 100 ° C. to reflux temperature. Solvents and chemicals should be kept as dry as possible to avoid hydrolysis of the anhydride.

The product was analyzed by 500 MHz nuclear magnetic resonance spectroscopy, and the spectrum showed the following structural formula.

[Additive B]

Ethylene vinyl acetate copolymer having a number average molecular weight of 3500 containing 13.5% by weight of vinyl acetate and containing 8 methyls per 100 methylene groups.

[Additive C]

Various itaconate polymers prepared by polymerizing monomers in a cyclohexane solvent using free radical catalysts.

Oligomeric materials with a number average molecular weight of 4000 and polymeric materials with a molecular weight of 80,000 were prepared for comparison. They each contained C ₁₂ to C ₁₈ linear alkyl groups in the itaconate esters. These are represented as C ₁₀ , PI, C ₁₂ PI, C ₁₄ PI and the like in the following table.

[Additive D]

Reaction product of 2 moles of isohydrated tallow amine and 1 mole of phthalic anhydride to form 0.5 amide / 0.5 amine salt.

[Additive E]

An ethylene vinyl acetate copolymer having a number average molecular weight of 3000, containing 29% vinyl acetate and containing 4 methyl groups per 100 methylene groups.

[Additive F]

Additive D blended with 10% by weight benzoic acid as stabilizer

[Additive G]

Three Nitro Derivatives of Additive D

Various additives were used together at a treatment rate of 250 ppm each for distillate fuel having the following characteristics.

Cloudy point: -2 ℃

Untreated CFPP -4 ℃

ASTM D-86 Distillation ℃

Initial boiling point 178

5% 227 50% 291

10% 243 60% 301

20% 261 70% 311

30% 272 80% 324

40% 282 90% 341

Final boiling point 368

These additives were tested as follows.

[exam]

The efficiency of the additive system as the filterability improving agent in the distillate fuel was determined by the following method.

As one method, the reaction of the oil to the additives was determined by cold filter plugging point test (CFPP), which is described in the Journal of the Insititute of Petroleum (Vol. 52, Number 510, June 1996, page). 173-285). These tests are designed to correlate with the cooling flow of intermediate distillates in automotive diesel.

In short, 40 mL of the sample of oil to be tested was cooled in a bath maintained at about -34 ° C to perform nonlinear cooling at about 1 ° C / min. Using a tester, a pipette with an inverted funnel located under the surface of the oil to be tested, attached to the lower end, the oil cooled within the prescribed time (at each 1 ° C starting from the cloud point) is passed through a fine screen. The ability to flow was periodically tested. At the spout of the funnel is placed a 350 mesh screen having an area defined by a diameter of 12 mm. A vacuum was applied to the top of the pipette to initiate the periodic tests, respectively, so that the oil was sucked into the pipette through the screen to the mark indicating 20 ml of oil. After each successful passage, the oil was immediately returned to the CFPP tube. The test was repeated by dropping the temperature 1 ° C each until the oil failed to fill the pipette within 60 seconds. This temperature was recorded as the CFPP temperature.

The difference between CFPP of the fuel without additives and CFPP of the same fuel containing the additive was recorded as the CFPP inhibition value by the additive (dCFPP). More effective flow modifiers provide greater CFPP inhibition at the same additive concentration.

Another measure of flow modifier efficiency was performed under the Programmed Cooling Test (PCT) condition of the flow modifier, which indicates whether the wax in the fuel passes through a filter as seen in a heating oil distribution system. This is a slow cooling test designed to be used.

In the test, the cooling fluidity of the described fuels containing additives was determined as follows. 300 ml of fuel was linearly cooled to the test temperature at 1 ° C./hour, and the temperature was kept constant. After 2 hours at -12 ml, about 20 ml of surface layer migrated as abnormal large wax crystals that tend to form on the oil / air interface during cooling. The wax precipitated in the bottle was dispersed by stirring and then a CFPP filter combination was inserted. The stopper was opened and a vacuum of 500 mm of mercury was applied and the stopper was closed when 200 ml of fuel had passed through the filter into the graduated container. Record PASS when 200 ml of fuel is collected within 60 seconds through a given mesh size, and FAIL if the flow rate is too low to indicate that the filter is clogged.

20, 30, 40, 60, 80, 100, 120, 150, 200, 250, 350, VW, LTFT and 500 Mesush followed by a combination of 25, 20, 15 and 10 micron filter screens and CFPP filters To determine the finest filter through which the fuel passes. The larger the number of meshes through which the wax-containing fuel passes, the smaller the wax crystals are, and the greater the efficiency of the flow modifier additive. It should be noted that for the same flow improving additive, it is not possible for two fuels to provide exactly the same test results at the same treatment level. Relative order is given in the table of text, with higher numbers indicating finer filters passed.

In addition, wax sedimentation studies were also performed prior to PCT filtration. The extent of sedimentation layer (WAS) was determined visually as the volume of total fuel by placing the treated fuel in a measuring flask. Sedimentation of this wide range of waxes is given in low numbers, while non-settled fluid fuel is given in 100% state. Poor samples of gelled fuel with large wax crystals are almost always high values, so care should be taken and therefore these results should be recorded as gels.

The efficiency of the additives of the present invention in lowering the cloud point of the distillation filter can be measured by standard cloud point test (IP-219 or ASTM-D 2500), and other measures of initiation of crystallization are the wax appearance (WAP) test ( ASTM D. 3117-72) and the wax appearance temperature (WAT) measured by differential scanning calorimetry using a Mettler TA 200 B differential scanning calorimeter. In this test, 25 μl of fuel sample is cooled to 2 ° C./min from a temperature at least 30 ° C. above the expected cloud point of the fuel. The observed crystallization initiation was measured without correction for the heating lag (about 2 ° C.) as the wax appearance temperature as indicated by the differential scanning calorimeter. This method is preferred because of its accuracy and reproducibility, and thus is the method of choice in the text.

The wax appearance temperature (WAT) of the fuel is measured by differential scanning calorimetry (DSC). In this test, a small fuel sample (25 μl) was cooled to 2 ° C./min with a reference sample (eg kerosene) having a similar heat capacity but which did not precipitate wax within the temperature range of interest. An exotherm is observed when crystallization starts in the sample. For example, the WAT of fuel can be measured by extrapolation techniques for Mettler TA 2000 B. dWAT is a suppression value of the wax appearance temperature from the base fuel by incorporation of additives in the fuel.

The wax content is derived from the DSC results by integrating the area surrounded by the baseline and the exotherm below the temperature described above. Calibration was already performed with known amounts of crystallized wax.

The average particle diameter of the wax crystal is determined by analyzing the optical micrograph of the fuel sample and measuring the longest axis in the crystal.

The crystal shape is determined by taking an enlarged picture of the wax crystals in the fuel.

The results of the test are shown in Table 1 below.

TABLE 1

In a further series of tests, the following additional additives were used.

[Additive H]

A mixture of two ethylene vinyl acetate copolymers, one containing 2580 Mn, containing 36.5 wt% vinyl acetate, the other containing 5000 Mn, containing 13.5% wt% vinyl acetate, The ratio of coalescence is 3: 1 (weight: weight).

[Additive I]

Same as Additive H, except the ratio of the two copolymers is 13: 1 (weight: weight).

[Additive J]

Ethylene vinyl acetate copolymer having a number average molecular weight of 2000 containing 28.0% by weight of vinyl.

Additives were tested in fuels having the properties described in Table 2.

TABLE 2

The treatment rate in the test is 250 ppm active ingredient of each additive. The sedimentation resistance of the wax was measured as follows.

(a) Visual inspection of the container as described in the above examples.

The numbers indicate the degree of sedimentation of the wax water, and the grades are further divided by the following letters.

C = clear upper layer, ie completely dewaxed as the fuel lowered to test temperature, causing all wax to settle in the base layer.

F = emergency mass indicating the presence of large undesirable crystals

CL = the base layer is cloudy but results in good sedimentation resistance

In these results, the letter H stands for Hazy, M stands for Milky, C stands for transparent, and F stands for agglomerates.

(b) Take 5 ml of top and base samples.

At this time, they were examined by measuring the WAT on the DSC as described above. The two numbers in the unsettled sample are the same. The larger the difference between the numbers, the larger the settling of the wax.

Therefore, T-B range = WAT base-WAT top (° C.).

The results are shown in Table 3 below.

TABLE 3

In addition, a further series of tests was performed. The additives used are represented by the letters A ¹ , B ¹ , D ¹ , E ¹ and F ¹ to M ¹ as follows, and the fuels used are those exhibiting properties as described later.

A ¹ : For the tests on fuels I and II, A is a mixture of two ethylene / vinyl acetate copolymers, namely Mn 2580 containing 3-4 weight percent vinyl acetate and 3 to 4 methyl groups per 100 methylene groups Copolymer of Mn 5000 containing 13.5% by weight of vinyl acetate and 6 methyl groups per 100 methylene groups (the ratio of the two copolymers is 93: 7 (weight: weight)) and the residual fuel For the test, A is an ethylene / vinyl acetate copolymer of Mn 3000 containing 29.0% by weight of vinyl acetate and 4 methyl groups per 100 groups of methylene group.

B ¹ : Reaction product of 2 moles of dihydrogenated tallow amine and 1 mole of phthalic anhydride to form 0.5 amide / 0.5 amine salt.

D ¹ : Homopolymer (Mw 4000) of esters of itaconic acid having 16 carbon atoms, linear alkyl groups, prepared by polymerizing monomers using free radical catalysts.

E ¹ : Blend of D ¹ with a second polyitaconate (Mw 4000) made in the same manner as additive D ¹ except that the alkyl group has 18 carbon atoms.

F ¹ : Second polyitaconate contained in additive E ¹ .

It should be understood that any additives are the same as those used in the experiments described above herein. There is not necessarily any relationship between additives given the same letter, with or without subscript 1.

The additive (which includes the combination of the individual additive components as evidenced by the juxtaposition of the letters in the results described later) is 200 ppm (active ingredient) for additive A ¹ , 200 ppm (active ingredient) and additive for additive B ¹ For D ¹ , E ¹ or F ¹ it was added to the diesel fuel at an additive concentration of 200 ppm (active ingredient) (these additives are as described above). Then, the following tests were performed on the fuel thus treated. Measurement of CFPP, WAS and Crystal Size (these are as described above respectively). The fuels used are fuels (I) to (iii) and their properties are recorded in diagram 1 below (all temperatures are in degrees Celsius).

[Diagram 1]

[fuel]

Additives A ¹ , B ¹ and D ¹ to F ¹ or combinations thereof were tested for fuels (I) through (iii), respectively, as described above. The results of CFPP, WAS and crystal size are shown in the following three tables, Tables 4, 5 and 6, respectively, with the following comments.

Table 4 (CFFF): All results are negative.

Table 5 (WAS): All results are% of dispersion, 100 indicates complete dispersion, observations are made after 2-3 hours at the test temperature.

Table 6 (crystal size): All values are expressed as ratios of 1 to 10, where 10 is less than 10 microns, 9 is 10 microns, 8 is 10 to 20 microns, 7 is 20 to 50 microns, and 6 is 50 to 100 microns, 5 to 100 to 200 microns, 4 to 200 to 300 microns, 3 to 300 to 500 microns, 2 to 500 to 700 microns, and 1 to greater than 700 microns.

The following general conclusions can be derived from the results shown in Tables 4-6.

Additives A ¹ and A ¹ B ¹ (comparative example) provide good CFPP performance and less good WAS and crystal size performance.

Additives A ¹ B ¹ D ¹ and A ¹ B ¹ F ¹ provide good WAS and crystal size performance, but provide a reduction in CFPP performance.

The reduction is at least improved by additive A ¹ B ¹ E ¹ in fuels I to V (fbp 365 ° C.).

Table 4 (CEPP)

[fuel]

Table 5 (WAS)

[fuel]

Table 6 (crystal size)

[fuel]

* Contains small defects.

Finally, the cloud point of any of the fuels was measured as described in the text when the fuel itself contained any of the additives described above. The obtained result is as follows (degreeC).

Table 7 (Blur Point)

[fuel]

The results show that the additive composition of the present invention can achieve a cloud point drop.

Claims (35)

Use of the polymer of the number average molecular weights 1,000-20,000 which has the following repeating units as a low temperature flow improving agent in a distillate fuel oil. Wherein x is an integer, y is 0 or an integer, the sum of x and y in the entire polymer is at least 2, and the ratio of unit (II) to unit (I) is 0 to 2 and unit (II) to The ratio of units (III) is 0 to 2, R ¹ and R ² are the same or different and are C ₁₀ to C ₃₀ alkyl, R ³ is H, -OOCR ⁶ , C ₁ to C ₃₀ alkyl, -COOR ⁶ , aryl Or an aralkyl group or halogen, R ⁴ is H or methyl, R ⁵ is H, C ₁ to C ₃₀ alkyl or -COOR ⁶ , R ⁶ is C ₁ to C ₂₂ alkyl, provided that R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ groups may each be inactively substituted. The method of claim 1 wherein the polymer is a homopolymer of dialkyl itaconate or citraconate, or an aliphatic olefin, vinyl ether, vinyl ester of alkanoic acid, alkyl ester of unsaturated acid, aromatic olefin, vinyl halide, or dialkyl fumar Use of a late or maleate with a copolymer of dialkyl itaconate or citraconate. 3. Dialkyl itaconate or dialkyl citraco according to claim 1 or 2, wherein the polymer is an aliphatic olefin, a vinyl ester or alkyl substituted vinyl ester of C ₂ to C ₃₁ alkanoic acid or R ³ is an aryl group. Use is a copolymer with a nate. The use according to claim 1, wherein the polymer has a molecular weight of 1,000 to 10,000. The method of claim 1, wherein the low temperature flow improver comprises at least two polymers as defined in claim 1, wherein the first polymer is selected to suppress the tendency of wax to precipitate from the fuel at reduced temperature. 2 The polymer is different from the first polymer, wherein it is chosen to counter any tendency of the first polymer to inhibit the CFPP performance of the fuel. 6. The method of claim 5, wherein the first and second polymers are homopolymers of dialkylitaconate, the alkyl groups of the first polymer are identical to each other, the alkyl groups of the second polymer are identical to each other, and the alkyl of the first polymer Each group having at least two carbon atoms less than the alkyl group of the second polymer. The method of claim 6, wherein when the alkyl groups of the second polymer each have 18 carbon atoms, the alkyl groups of the first polymer each have 16 carbon atoms, or the alkyl groups of the second polymer each have 20 carbon atoms. Wherein the alkyl groups of the first polymer each have 18 carbon atoms. 2. Use according to claim 1, in which the polymer is mixed with other low temperature flow modifiers for distillate fuels. 9. Use according to claim 8, wherein the other low temperature flow improver is a comb polymer of the general formula Wherein D is R, C (O) .OR, OC (O) .R, R ¹ C (O) .OR or OR, E is H or CH ₃ or D or R ¹ , and G is H or D, m is 1.0 (homopolymer) to 0.4 (molar ratio), J is H, R ¹ , aryl or heterocyclic group, R ¹ CO.OR, K is H, C (O) .OR ¹ , OC (O) .R ¹ , OR ¹ , C (O) OH, L is H, R ¹ , C (O) .OR ¹ , OC (O) .R ¹ , aryl, C (O) OH, n Is 0.0 to 0.6 (molar ratio), R ¹ is a hydrocarbyl group containing 10 or more, preferably 10 to 30 carbon atoms, and R ¹ is a C ₁ to C ₃₀ hydrocarbyl group. 9. Use according to claim 8, wherein the other low temperature flow improver is an ethylenically unsaturated ester copolymer. 9. Use according to claim 8, wherein the other low temperature flow improver is an amine salt and / or an amide formed by the reaction of hydrocarbyl acid with hydrocarbyl substituted amines having 1 to 4 carbolic acid groups or corresponding anhydride groups. Distillate fuel oil containing 0.0001 to 5.0% by weight of a polymer having a number average molecular weight of 1,000 to 20,000 having the following repeating unit. Wherein x is an integer, y is an integer of 0 degrees, the sum of x and y in the entire polymer is at least 2, the ratio of units (II) to units (I) is from 0 to 2, and units (II) to The ratio of units (III) is 0 to 2, R ¹ and R ² are the same or different and are C ₁₀ to C ₃₀ alkyl, R ³ is H, -OOCR ⁶ , C ₁ to C ₃₀ alkyl, -COOR ⁶ , aryl Or an aralkyl group or halogen, R ⁴ is H or methyl, R ⁵ is H, C ₁ to C ₃₀ alkyl or -COOR ⁶ , R ⁶ is C ₁ to C ₂₂ alkyl, provided that R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ groups may each be inactively substituted. The method of claim 12 wherein the polymer is a homopolymer of dialkyl itaconate or citraconate, or an aliphatic olefin, vinyl ether, vinyl ester of alkanoic acid, alkyl ester of unsaturated acid, aromatic olefin, vinyl halide, or dialkyl fumar Distillate fuel oil, which is a copolymer of late or maleate with dialkyl itaconate or citraconate. The monomer and dialkyl itaconate or dialkyl citraco according to claim 12 or 13, wherein the polymer is an aliphatic olefin, a vinyl ester or alkyl substituted vinyl ester of C ₂ to C ₃₁ alkanoic acid or R ³ is an aryl group. Distillate fuel oil which is a copolymer with nate. 13. The distillate fuel oil of claim 12, wherein the polymer has a molecular weight of 1,000 to 10,000. 13. The method of claim 12, wherein the low temperature flow improver comprises at least two polymers as defined in claim 1, wherein the first polymer is selected to suppress the tendency of wax to precipitate from the fuel at reduced temperature. 2 distillate fuel oil wherein the polymer is different from the first polymer and it is chosen to counter any tendency of the first polymer to inhibit the CFPP performance of the fuel. 17. The method of claim 16, wherein the first and second polymers are homopolymers of dialkylitaconate, the alkyl groups of the first polymer are identical to each other, the alkyl groups of the second polymer are identical to each other, and the alkyl of the first polymer A distillate fuel oil wherein the groups each have at least two carbon atoms less than the alkyl group of the second polymer. 18. The method of claim 17, wherein when the alkyl groups of the second polymer each have 18 carbon atoms, the alkyl groups of the first polymer each have 16 carbon atoms, or the alkyl groups of the second polymer each have 20 carbon atoms. Distillate fuel oil having alkyl atoms of the first polymer each having 18 carbon atoms. 13. The distillate fuel oil according to claim 12, which further contains another low temperature flow improving agent for the distillate fuel. 20. The distillate fuel oil of claim 19, wherein the other low temperature flow modifier is a comb polymer of the general formula: Wherein D is R, C (O) .OR, OC (O) .R, R ¹ C (O) .OR or OR, E is H or CH ₃ or D or R ¹ , and G is H or D, m is 1.0 (homopolymer) to 0.4 (molar ratio), J is H, R ¹ , aryl or heterocyclic group, R ¹ CO.OR, K is H, C (O) .OR ¹ , OC (O) .R ¹ , OR ¹ , C (O) OH, L is H, R ¹ , C (O) .OR ¹ , OC (O) .R ¹ , aryl, C (O) OH, n Is 0.0 to 0.6 (molar ratio), R is a hydrocarbyl group containing 10 or more, preferably 10 to 30, carbon atoms, and R ¹ is a C ₁ to C ₃₀ hydrocarbyl group. 20. The distillate fuel oil of claim 19, wherein the other low temperature flow improver is an ethylenically unsaturated ester copolymer. 20. The distillate fuel oil of claim 19, wherein the other cold flow modifier is an amine salt and / or an amide formed by the reaction of a hydrocarbyl acid with a hydrocarbyl substituted amine having from 1 to 4 a carboxylic acid groups or corresponding anhydride groups. An additive concentrate comprising a solution containing 20 to 80% by weight of a polymer having a number average molecular weight of 1,000 to 20,000 having the following repeating unit. Wherein x is an integer, y is 0 or an integer, the sum of x and y in the entire polymer is at least 2, and the ratio of unit (II) to unit (I) is 0 to 2 and unit (II) to The ratio of units (III) is 0 to 2, R ¹ and R ² are the same or different and are C ₁₀ to C ₃₀ alkyl, R ³ is H, -OOCR ⁶ , C ₁ to C ₃₀ alkyl, -COOR ⁶ , aryl Or an aralkyl group or halogen, R ⁴ is H or methyl, R ⁵ is H, C ₁ to C ₃₀ alkyl or -COOR ⁶ , R ⁶ is C ₁ to C ₂₂ alkyl, provided that R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ groups may each be inactively substituted. The method of claim 23, wherein the polymer is a homopolymer of dialkyl itaconate or citraconate, or an aliphatic olefin, vinyl ether, vinyl ester of alkanoic acid, alkyl ester of unsaturated acid, aromatic olefin, vinyl halide, or dialkyl fumar An additive concentrate that is a copolymer of latex or maleate with dialkyl itaconate or citraconate. The copolymer of claim 23 or 24, wherein the copolymer is an aliphatic olefin, a vinyl ester or alkyl substituted vinyl ester of C ₂ to C ₃₁ alkanoic acid, an alkyl ester of unsaturated acid, C ₁ to C ₂₂ dialkyl fumarate or Mali An additive concentrate which is a copolymer of dialkyl itaconate or dialkyl citraconate with a monomer wherein the ate or R ³ is an aryl group. The additive concentrate of claim 23 wherein the polymer has a molecular weight of 1,000 to 10,000. 24. The method according to claim 23, wherein the low temperature flow improver comprises at least two polymers as defined in claim 1, wherein the first polymer is selected to suppress the tendency of the wax to settle out of the fuel at reduced temperature, The additive concentrate is selected from the first polymer to interfere with any tendency of the first polymer to inhibit the CFPP performance of the fuel. 28. The method of claim 27, wherein the first and second polymers are homopolymers of dialkylitaconate, the alkyl groups of the first polymer are identical to each other, the alkyl groups of the second polymer are identical to each other, and the alkyl of the first polymer An additive concentrate wherein each group has at least two carbon atoms less than the alkyl group of the second polymer. 29. The method of claim 28, wherein when the alkyl groups of the second polymer each have 18 carbon atoms, the alkyl groups of the first polymer each have 16 carbon atoms, or the alkyl groups of the second polymer each have 20 carbon atoms. The additive concentrate of the first polymer when each has 18 carbon atoms. 24. The additive concentrate of claim 23 which also contains other low temperature flow improvers for distillate fuels. 31. The additive concentrate of claim 30 wherein the other cold flow improver is a comb polymer of the general formula: Wherein D is R, C (O) .OR, OC (O) .R, R ¹ C (O) .OR or OR, E is H or CH ₃ or D or R ¹ , and G is H or D, m is 1.0 (homopolymer) to 0.4 (molar ratio), J is H, R ¹ , aryl or heterocyclic group, R ¹ CO.OR, K is H, C (O) .OR ¹ , OC (O) .R ¹ , OR ¹ , C (O) OH, L is H, R ¹ , C (O) .OR ¹ , OC (O) .R ¹ , aryl, C (O) OH, n Is 0.0 to 0.6 (molar ratio), R is a hydrocarbyl group containing 10 or more, preferably 10 to 30, carbon atoms, and R ¹ is a C ₁ to C ₃₀ hydrocarbyl group. 31. The additive concentrate of claim 30, wherein the other cold flow improver is an ethylenically unsaturated ester copolymer. 31. The additive concentrate of claim 30, wherein the other cold flow improver is an amine salt and / or an amide formed by the reaction of a hydrocarbyl acid with a hydrocarbyl substituted amine having from 1 to 4 carboxylic acid groups or corresponding anhydride groups. A polymer having a number average molecular weight of 1,000 to 20,000 having the following repeating unit Wherein x is an integer, y is 0 or an integer, the sum of x and y in the entire polymer is at least 2, and the ratio of unit (II) to unit (I) is 0 to 2 and unit (II) to The ratio of units (III) is 0 to 2, R ¹ and R ² are the same or different and are C ₁₀ to C ₃₀ alkyl, R ³ is H, -OOCR ⁶ , C ₁ to C ₃₀ alkyl, -COOR ⁶ , aryl Or an aralkyl group or halogen, R ⁴ is H or methyl, R ⁵ is H, C ₁ to C ₃₀ alkyl or -COOR ⁶ , R ⁶ is C ₁ to C ₂₂ alkyl, provided that R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ groups may each be inactively substituted. 35. A method for improving the low temperature performance of distillate fuel oils comprising incorporating additives comprising a polymer as defined in claim 34 into the oil.