CA2055417A1

CA2055417A1 - Middle distillates of crude oil having improved cold flow properties

Info

Publication number: CA2055417A1
Application number: CA002055417A
Authority: CA
Inventors: Gerd Konrad; Bernd Wenderoth; Klaus Barthold; Erich Schwartz; Heinrich Hartmann; Hans-Juergen Raubenheimer
Original assignee: Individual
Current assignee: BASF SE
Priority date: 1990-11-14
Filing date: 1991-11-13
Publication date: 1992-05-15
Also published as: FI915127A0; EP0485774A1; DE59101025D1; FI915127A; NO914444L; NO914444D0; DE4036226A1; ES2049072T3; EP0485774B1; ATE101640T1

Abstract

ABSTRACT OF THE DISCLOSURE

Crude oil middle distillates with improved cold flow properties, containing small amounts of A. conventional flow improver on an ethylene base, and B. copolymers which consist of a. of 10 to 90 mol-% of one or more alkylacrylates or alkylmethacrylates with C1- to C30-alkyl chains, and b. of 5 to 60 mol-% of one or more ethylenically unsaturated dicarboxylic acids or their anhydrides, and c. of 5 to 60 mol-% of one or several alkylvinylethers with C18- to C28-alkyl side chains, where the quantitative proportion of A to B is 40 to 60 and 95 to 5.

Description

2 ~

MIDDLE DISTILLATES OF CRUDE OIL HAVING IMPROVED
COLD FLOW PROPERT~ES

FIELD OF THE INVENTION

The present invention relates to middle distillates of crude oil containing small amounts of a conventional flow improver on an ethylene base and copolymers of ethylenically unsaturated carboxylic acid esters of long-chain n-alcanols with long-chain alkylvinyl ethers and ethylenically unsatuxated dicarboxylic acid derivates, which are distinguished by improved cold 10w properties.

BACKGROUND OF THE INVENTION

Middle distillates, such as gas oil, Diesel oil or heating oil, which are obtained from crude oil by distillation have, depending on the source of the crude oil and dep~nding on the type of processing in the refinery, different paraffin contents. The proportion of long-chain n-paraffins in particular determines the cold flow properties of such distillates. During cooling, the n-paraffins are separated in the form of platelet-like interlaced crystals which build up into a three-dimensiona network (house of caxds structure), where large amounts of still liquid distillate axe locked up and immobilized. A decrease of flowability and an increase of the viscosity occurs parallel with the cxystallization of the n-paraffins. The supply of middle distillates to the combustion means is made more difficult because of this. ~he precipitated paraffins plug filters ahead of ths combustion means so that in extreme cases it is possible that the entire supply is stopped.

.. . . . - . .. , . .: .

2 ~ 7 It has been known for a long time that the plugc;ing of the filters at low temperatures can be overcome by the addition of so-called flow improvers. By means of the formation of nuclei, the additives cause the formation of many small paraffin crystals in place of a few large ones. At the same time they change their crystal modification, so that there is no ~ormation of the above described platelets. The paraffin crystals formed in the presence of flow improvers are so small that they can pass through the filters, or they build up into a filter cake which is permeable to the still liquid portion of the middle distillate, so that operation free of disruption is assured even at low temperatures.
Middle distillate cuts are appearing in increasing amounts in the refineries, where the standard flow improvers do not have a sufficient effect or even fail completely. This applies particularly to so-called top draw oil, i.e. fractions with a high final boiling point (F.B.P. > 370C). However, the boiling properties are not the criteria. It may occur in connection with two fractions with similar boiling point curves but dissimilar provenance of the basic crude oil, that the standard flaw improver works well with one oil, but not with the other. In accordance with DIN 51 428, the effectiveness of the flow improver is indirectly expressed by measuring the cold filter plugging points (CFPP).
Ethylene copolymers, known per se, mainly copolymers of ethylene and unsaturated esters such as described in German Patent Disclosure DE-A-21 02 46~ or European Patent Disclosure EP-A-84 148, are used as standard cold flow improvers.
However, the technology requires new flow improvers which also show good effectiveness in connection with the above described critical oils.
The use of polymers with linear, saturated side chains with at least 18 carbon atoms for reducing the flow point of paraffin-.,,, ~ , . : ~

2 0 ~ 7 containing heating oil is known ~rom German Patent Disclosure DE-A-16 45 785. These are, for example, homo- or copolymers of alkylesters o~ unsaturated mono- or dicarboxylic acids as well as homo- or copolymers of various alkylvinylethers. Also recited are: "Reaction products of copolymers of aci~ anhydrides of unsaturated dicarboxylic acids and mono-olefins or other olefinic unsaturated compounds with an aliphatic amine containing a long hydrocarbon chain". In this case copolymers of mono-olefins are preferred.
In German Patent Disclosure DE-A-25 31 234 the addition of alternating copolymers containing maleic acid diamide or maleic imide structures are recommended as stabilizers in mineral oils, i.e. the carboxyl groups are completely reacted with amines into diamides or imides.
In accordance with US Letters Patent 3,506,625, reaction products of monoamines with maleic acid anhydride polymers to the corresponding imides are also described, where in case of use of less than one mol amine per mol unit of maleic acid anh~dride still remaining carboxyl groups are changed to metal salts by neutralization. Alkylvinylether and monovinylhydrocarbons are preferably used for the copolymerization with maleic acid anhydrides.
French Letters Patent 2.5g2.65~ describes mixtures of an ethylene polymer and a reaction product of a primary amine with a copolymer of, for example, acrylic acid alkylesters and/or alkyl-vinylesters, diisobutene and maleic acid anhydride and their use as an additive to middle distillates.
Middle distillates are described in European Patent Disclosure EP-A-360 419, which contain polymers of vinylethers with hydrocarbon radicals of 1 to 17 carbon atoms. ~lkylacrylates or -methacrylates, among others, are disclosed as ao-monomers.
However, the examples only describe polymers of alkylvinylethers 20~41~

with up to four carbon atoms in the side chain. These Cl- to C4-vinylethers are copolymerized with derivatives o~ maleic or fumaric acid. No examples of copolymers with derivatives of acrylic acid are provided. The claimed additives can be used in conjunction with other flow improvers.
The use of polymers with at least one amide group from a secondary amine and a carboxyl group as an additive to middle distillates is known from European Patent Disclosure EP-A-283 293.
The polymers can be obtained, for example, by copolymerization of unsaturated esters with maleic acid anhydride and subsequent reaction with the secondary amine. Among others, dialkylfumarate and vinylacetate are disclosed as unsaturated ester monomers.
However, these polymers leave a lot to be desired in regard to their effectiveness as cold flow improvers for middle distillates.
For these reasons the problem arose of finding additives to middle distillates with improved efficiency as cold flow mprovers.

OBJECT AND SUMMARY OF THE INVENTION

It has been found accordingly that crude oil middle distillates containing small amounts of A): known flow improvers, and B): copolymers consisting a. of 10 to 90 mol-% of one or more alkylacrylates or alkylmethacrylates with C1- to C30-alkyl chains, and b. of 5 to 60 mol-% of one or more ethylenically unsaturated dicarboxylic acids or their anhydrides, and c. of 5 to 60 mol-% of one or several alkylvinylethers with C18- to C28-alkyl side chains, fulfill these requirements.

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2 ~ 7 The copolymers B consist of lo to 90 mol-~, preferably 40 to so mol-%, and particularly preferred 60 to 90 mol-% o~ al~yl-(meth)acrylates, of 5 to 60 mol-%, pre~erably 5 to 40 mol-% and particularly preferred 10 to 30 mol-% of olefinic unsaturated dicarboxylic acids or their anhydrides, of 5 to 60 mol-%, preferably 5 to 40 mol-% and particularly preferred 10 ~o 30 mol-%
of alkylvinylethers.
The quantitative proportion of flow improver A to copolymer B lies between 40:60 and 95:5, preferably between 60:40 and 95:5 and particularly preferred between 70:30 and 90:10.
The alkyl groups of the alkyl(meth)acrylates consist of 1 to 30, preferably 4 to 22 and particularly preferred 8 to 18 carbon atoms. They are preferably straight-chain and linear.
However, they may also contain up to 20% by weight of cyclical and/or branched portions.
Examples of particularly preferred alkyl(meth)acrylates are n-octyl(meth)acrylate, n-decyl(meth)acrylate, n-dodecyl(meth)-acrylate, n-tetradecyl(meth)acrylate, n-hexadecyl(meth)acrylate and n-octadecyl(meth)acrylate, as well as mixtures thereof.
Examples of ethylenic unsaturated dicarboxylic acids are maleic acid, tetrahydrophthalic acid, citraconic acid or itaconic acid or their anhydrides, fumaric acid as well as mixtures thereof. Maleic acid anhydride is pre~erred.
Examples of alkylvinylether are octadecylvinylether, eicosylvinylether, docosylvinylether, tetracosylvinylether, hexacosylvinylether and octacosylvinylether, as well as mixtures thereof.
The copolymers B show synergistic e~fects together with the flow improvers. Although the copolymers B by themselves show no or only little improvement of the flow, the combination of A and B
far exceeds the individual effects.

.: . . .. . .

The car~oxylic acid (anhydride) groupings at the copolymer B can be reacted wholly or partially with compounds containing amino or hydroxyl groups. This is not required for obtaining the desired effect. However, in some cases the effect can be increased by the reaction, and solubility in the middle distillate or the compatibility with other components can be favorably affected.
Alkylamines ~ -H

are preferred as compounds containing amino groups, where R1 is a straight-chain or branched alkyl radical with 1 to 30, preferably 8 to 26 and particularly preferred 12 to 2~ carbon atoms and R2 is hydrogen, methyl or Rl. Particularly to be mentioned are ethyl-hexylamine, octadecylamine, oleylamine, tallow fat amine, n-methyloctadecylamine and preferably behenylamine, dibehenylamine and hydrogenated di-tallow fat amine. However, al~ylaryl or aryl amines as well as cyclic amines which, if required, have a hetero-atom, can also be used.
Compounds of the formula Rl- ( oR2 ) n-t)H

are preferred as compounds containing hydroxyl ~roups, where indicates Cl- to C30-alkyl, C6- to C12-aryl or Cl- to C30-alkylaryl, and R2 indicates Cl- to C4-alkyl, and n is a whole number from O to 30.
Examples for compounds containing hydroxyl groups are~
alcohols such as 2-ethylhexanol, n-hexadecanol and n-octadecanol, alkylphenols such as iso-octylphenol, iso-nonylphenol and their reaction products with alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide.
Examples of the flow improvers A are the already mentioned polymers described in DE A-21 02 469 and EP-A-84 148, and copolymers of ethylene with vinylacetate, vinylpropionate, vinylbutyrate, vinylpivalate or with esters of (meth)acrylic acid which derive from alkanols wi~h l to 12 carbon atoms. Also suitable are mixtures of several copolymers of ethylene and vinylacetate (EP-A-261 951, Additive A), copolymers of ~thylene with ~-olefins (EP-A-261 957, Additive D) and t~le mixtures of terpolymers of ethylene, vinylacetate and diisobutane with oxidized polyethylene wax recited in DE-A-36 24 147. Copolymers of ethylene with vinylacetate or vinylpropionate or ethylhexyl-acrylate are particularly preferred.
The alkyl~meth)acrylates are easily accessible. They can be obtained by means of the known methods of esterification. For example, a solution of (meth~acrylic acid and an alkanol or a mixture of different alkanols is heated to boiling in an organic solvent with the addition of the usual polymerization inhibitors, for example hydroquinone derivatives and esterification catalysts, such as sulfuric acid, p-toluene sulfonic acid or acid ion exchangers, and the reaction water which forms is removed by azeotropic distillation. Because vinylethers can cationically polymerize under acid conditions or decompose in the presence of water while forming acetaldehyde, which upsets the polymerization of the radicals, neutralization of the catalyzer acid as well as surplus (meth)acrylic acid with, for example, amines, or their removal by washing of the ester solution with alkaline means and water for producing the copolymers B is indicated. Particularly pure esters can be obtained by distillation of the pre-cleaned ester solution.

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Further possibilities for producing alkyl(meth)acrylates are the reaction of ~meth)acrylic acid chloride or anhy~ride with the corresponding alkanols as well as the reaction, known as interesterification, of low (meth)acrylic acid esters with the corresponding C8- to C18 alkanols, with the addition of acidic or basic catalysts and removal by distillation of the low alkanol.
In this production method the ester should also be processed sufficiently so that no more acid is present.
The vinylethers can be obtained in accordance with known methods by the reaction of alkanols with acetaldehyde and subsequent splitting of f of water or by means of the catalytic addition of acetylene to alkanols. Particularly clean monomers can here also be obtained by distillation. Undecomposed distillation is technically difficult to perform with vinylethers with more than 20 to 22 carbon atoms. In these cases purification by filtration, extraction or recrystallization to remove the catalysts is to be recommended.
As a rule it is advantageous to use the dicarboxylic acids in the form of anhydrides to the extent available in copolymerization, for example malei¢ acid anhydride, itaconic acid anhydride, citraconic acid anhydride and tetrahydrophthalic acid anhydride, because as a rule the anhydrides copolymerize better with the (meth)acrylates. The anhydride groups of the copolymers can then be directly reacted with compounds containing amino or hydroxyl groups.
Reaction of the polymers with amines takes place at temperatures of 50 to 250C in the course of 0.3 to 30 hours. The amine is used in this case in amounts of approximately one to two mols per mo~ of polymerized dicarboxylic acid anhydride, i.e.
approximately 0.9 to 2.1 mol/mol. Use of larger or smaller amounts is possible but does not provide an advantage. The use of 2 mols of amine per mol of anhydri~e results in amine/ammonia .. . .... .

2 ~ 1 7 salt. This can be changed into the diamide by heating to 150 to 2000C while water is split o~f. With the use of one mol o~ a primary amine per mol of anhydride, the monoamide which is generated can be changed into the imide by heating to 150 to 250C.
Reaction of the polymers with alcohols, alkylphenols or their alkoxylates also takes place at temperatures of 50 to 250C.
The alcohol or the phenol are used in amounts of 1 to 2 mol per mol of anhydride. If 1 mol of alcohol is used, the semi-ester is formed, with 2 mols of alcohol it is necessary to use an esterification catalyst and to remove the reaction water so that the complete formation of the diester can take place.
Reaction of the copolymers B can take place with a compound containing an amino groups as well as containing a hydroxyl group.
If reaction takes place first with an alcohol and then with an amine, an ester/ammonia salt is obtained, depending on the conditions, or, at a higher temperature and removal of the reaction water, an ester/amide. If reaction takes place first with an amine and then with an alcohol, an ester/amine is immediately obtained, if the reaction water is removed and a higher temperature used.
Instead of the later reaction of the carboxyl groups or the dicarboxylic acid anhydride with the compounds containing amino or hydroxyl groups, it may be advantageous in some cases to produce the monoamides, mono- or diesters, monoamide/monoester, etc. of the monomers and then to polymerize them directly during polymerization. However, in most cases this is technically more expensive, for example because amines can also hecome attached to the double bond of the dicarboxylic acids and then copolymerization is no longer possible.
The production of the copolymers B takes place in accordance with known discontinuous or continuous polymerization _g_ 2a~4l7 methods, such as mass, suspension, precipitation or solution polymerization, and initia~ion with the usual radical donors, such as acetylcyclohexanesulfonylperoxide, diacetylpercxidicarbonate, dicyclohexylperoxidicarbonate, di-2-ethylhexylperoxidicarbonate~ tert.-butylperneodecanoate, 2,2'-azobis(4-methoxy-2,4-dimethyl-valeronitrile), tert.-butylperpivalate, tert.-butylper-2-ethyl-hexanoate, tert.-butylpermaleinate, 2,2'-azobis(isobutyronitril~, bis-(tert.-butylperoxide)cyclohexane, tert.-butylperoxiisopropyl-carbonate, tert.-butylperacetate, di-cumylperoxide, di-tert.-amylperoxide, p-menthanehydroperoxide, cumolhydroperoxide or tert.-butylhydroperoxide and mixtures among these. Generally these initiators are used in amounts of 0.1 to 20% by weight, preferably 0.2 to 15% by weight, in respect to the monomers.
Polymerization as a rule takes place at temperatures of 40 to 400C, preferably 70 to 300C, where it is practical to operate under pressure when solvents with boiling temperatures below the polymerization temperature are used. It is practical to perform the polymerization with air excluded, i.e. if processing is not done under boiling conditions, for example in nitrogen or carbon dioxide, because oxygen delays polymerization.
The reaction can be accelerated by the simultaneous use of redox initiators, such as benzoin, dimethylaniline, ascorbic acid as well as organically soluble complexes of heavy metals such as copper, cobalt, manganese, iron, nickel and chromium. The amounts normally used lie around 0.1 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight. When selecting the initiator or the initiator system, it is practical in connection with the chosen polymerization temperature to see to it that the half-time of the initiator or initiator system i5 less than four hours.
It is often practical for obtaining low-molecular copolymers to operate in the presence of regulators. Suitable regulators are, for example, allylalcohols such as 1-butene-3-ol, , . . ,,: .. .:

"` 2 ~ 7 organic mercaptan compounds such as 2-mercaptoathanol, 2~mercapto-propanol, mercaptoacetic acid, mercaptopropionic acid, tert.-butylmercaptan, n-butylmercaptan, n-octylmercaptan, n-dodecyl-mercaptan and tert.-dodecylmercaptan, which generally are used in amounts of o.l to 10% by weight.
Apparatus suitable for polymerization consists of, for example, customary mixing vessels with, for example, anchor, blade, impeller or multistage-pulse countercurrent agitators, and for continuous production mixing vessel cascades, tube reactors and static mixers.
Mass polymerization is the simplest polymerization method.
In accordance with it the monomers are polymerized in ~he presence of an initiator and the absence of solvents. In a practical manner all monomers are mixed in the desired composition and a small amount, for example approxima~ely 5 to 10%, is first placed into the reactor, heated to the desired polymerization temperature while stirring and the remaining monomer mixture and the initiator and, if required, the coinitiator as well as the regulator are evenly admixed during l to 10 hours, preferably 2 to 5 hours. In this connection it is practicable to admix the initiator as well as the coinitiator separately in the form of solutions in a small amount of a suitable solvent. Then the copolymer can be added directly to the flow improver as a solidified molten mass or after having been placed in a suitable solvent.
A continuous high-pressure method is also suitable for producing the desired copolymers, which permits space-time yields of l to 10 kg polymer per liter of reactor and hour. For example, a pressure vessel, a pressure vessel cascade, a pressure pipe or a pressure vessel with a reaction pipe downstream, which is provided with a static mixer, can be used as polymerization apparatus.
Polymerization is preferably performed with monomers of (meth)acrylic acid esters, unsaturated dicarboxylic acids or their 2 a ~

anhydrides and vinylethers in at least two successive polymerization zones. One polymerization zone can consist of a pressure-proof vessel, the othsr of a heatable static mixer.
conversions of more than 99% are obtained in this case. For example, a copolymer of (meth)acrylic acid esters, maleic acid anhydride and octadecylvinylether can be produced by continuously supplying the monomers and a suitable initiator to a reactor ot two successive reaction zones, for example a reactor cascade, and continuously taking the reaction product from the reaction zone after a loitering time of 2 to 60, preferably 5 to 30 minutes, at temperatures between 200 and 400C. Polymerization is practically per~ormed at pressures of more than 1 bar, preferably between 1 and 200 bar. The copolymers obtained show solid contents of more than 99%.
Another simple method for producing the copolymers B is solution polymerization. It is performed in solvents in which the monomers and the formed copolymers are soluble. For this all those solvents are suitable which fulfill this condition and which do not react with the monomers. They are, for example, toluene, xylene, ethylbenzene~ cumene, high-boiling aromatic mixtures such as SolvessoR 100, 150 and 200, aliphatic and cycloaliphatic hydrocarbons such as n-hexane, cyclohexane, methylcyclohexane, n-octane, iso-octane, paraffin oils, ShellsolR TD, T and K as well as tetrahydrofuran and dioxane, where tetrahydrofuran and dioxane are particularly well suited for obtaining low-molecular copolymers. When performing the solution polymerization it is practical to place the solvent and a part of the monomer mixture (for example approximately 5 to 20%) first and to admix the remainder of the monomer mixture with the initiator and, if required, the coinitiator, regulator and solvent. It is also possible to admix the monomers individually at different speeds.
This is recommended in case of monomers with greatly differing . .. : :,.. :. , . . ., :

2~41 ~

reactivity, and when a particularly even distribution of the less reactive vinylether i5 desire~. In this case the less reactive monomer is admixed faster and the more reactive monomer slower.
It is also possible to place the entire amount of a monomer, preferably the less reac~ive anhydride or vinylether, ~irst and to admix only the (meth)acrylate. Finally, it is also possible to place all the monomers and the solvent first and to admix only the initiator and, if required, the coinitiator and regulator (batch processing). When using this type of processing on a larger scale, however, problems in regard to heat removal may occur, so that this type of processing should only be used with low concentrations of the monomers to be polymerized. The concentration of the monomers to be polymerized lies between 20 and 80% by weight, preferably 30 and 70~ by weight. The solid copolymers can be obtained without problems by evaporation of the solvent. However, it is practical to select a solvent for polymerization which is compatible with the middle distillate, so that the polymerisate solution can be directly added to the middle distillate. Solution polymerization is the preferred type of producing copolymers from (meth)acrylates and dicarboxylic acids (anhydride) There is the requirement in technology to provide the additives in accordance with the invention, consisting of a flow improver A and a copolymer B, in a form which is easy to handle.
For this purpose the polymers A and B should be available in the form of one concentrate, since the use of two concentrates - one each for polymer A and polymer B - makes handling more difficult.
Because of possible incompatibility of the polymers A and B, phase separation may occur if the two polymers are purely admixed in a common solvent. If necessary this can be suppressed by means of suitable solvents and/or additives. For example, alkanols, such as iso-butanol, n-hexanol, 2-ethylhexanol, iso-decanol and their adducts with ethylene oxide, propylene oxide and/or butylene oxide, alXylphenol and their adducts with ethylene oxide, propylene oxide and/or butylene oxide, as well as semi-esters or di-esters of dicarboxylic acids with alkanols or (oligo)alkylene-oxide semi-esters such as mono or dibutylphthalate, mono- or di-2-ethyl-hexylphthalate or di-(2~methoxyethyl)-phthalate are suitable.
Another method of preventing possible phase separation consists in grafting the copolymer B at leas~ in part on the flow improver. Mass or solution polymerization is preferably used for grafting. Polymerization can be performed in accordance with batch or feed processing. With batch processing, the entire amount of flow improver A on which the graft is to be made is placed first, together with the monomers, and the initiator and, if required, the coinitiator and regulator are admixed later.
With feed processing, the entire amount of flow improver A on which the graft is to be made is placed first, if desired together with a portion of the monomers, and the rest of the monomers, initiator and, if required, the coinitiator and regulator are admixed later~
As already mentioned, it is not necessary to graft the copolymer B on the entire portion of the flow improver A. For example, at the ratio A:B of 90:10, the copolymer B is grafted on only a portion of 2 to 20% by weight of the entire amount of A for reasons of the space-time yield. However, at a ratio of A:B of 40:60 on a portion of 30 to 100% by weight of the total amount of A.
It is also unnecessary to graft the entire amount of polymer B on a portion of the flow improver A. This is difficult anyway, because in general the graft yield does not reach 100%, so that it is possible that, besides graft copolymerisates and unreacted or 205~7 admixed flow improver A, there is also non-grafted copolymer B in the concentrates described.
The K values (according to H. Fikentscher, Cellulose Chemistry, Vol. 13, pp. 58 to 64 and 71 to 74 (1932)), determined in a 2% ~vol. by weight) xylolic solution of the copolymerisates B, lies between 10 and 50, preferably between 10 and 40 and particularly preferred between 13 and 30. The particularly preferred range corresponds to molecular weights between approximately 5000 and 25000 g/mol (numerical mean values detexmined by gel permeation chromatography against polystyrol standards).
The additives A and B in accordance with the invention are added to crude oil middle distillates in amounts of 50 to 5000 ppm, preferably 100 to 2000 ppm.
The middle distillates in accordance with the invention and containing small amounts of a Plow improver A and a copolymer B
may, depending on their intended use, contain other additives or added materials such as dispersants, anti-foaming additives, corrosion protection agents, anti-oxidants, dyes, and the like.
The invention will be explained by means of the following examples.

DETAIL~D D~SCRIPTION

Pxoduction of Copolymers B in Accordance with the Invention Example 1 In a reactor provided with an agitator, heater and feed device, 24.5 g of vinyloctadecylether, 8.1 g of maleic acid anhydride, 20 g of laurylacrylate (n-alkylacrylate mixture, prepared from a commercially available fatty alcohol mixture 205~A17 consisting maximally o~ 1.5% by weight o~ n-decanol, 51 to 57% by weight of n-dodecanol, 41 to 47% by weight of n-tetradecanol and maximally 1.5% by weight of n-hexadecanol) and 79 g of SolvessoR
150 (high-boiling aromatic mixture of the ESSO company) were heated to 100C in a weak nitrogen flow while being agitated and 147.4 g of laurylacrylate in 76 g of SolvessoR 150 were evenly admixed over a period of 2 hours. Simultaneously a solution of 0.6 g of tert.-butylper-2-ethylhexanoate in 30.0 g of So]vessoR
150 were evenly admixed over a period of 4 hours. Su~sequently a solution of 0.2 g of tert.-butylper-2-ethylhexanoate in 15 g of SolvessoR 150 was added and heating continued at 100C for one hour. A clear, yellowish solution of approximately 50~ by weight was obtained. The K value of the polymer was 16.9; the mol ratio of acrylate to maleic acid anhydride to vinylether was approximately 80:10:10.

Example 2 In a reactor in accordance with Example 1, 167.4 g of laurylacrylate, 8.1 g of maleic acid anhydride, 24.5 g of vinyloctadecylether and 163 g of SolvessoR 150 were heated to 100C in a weak nitrogen flow while being agitated and a solution of 0.6 g of tert.-butylper-2-ethylhexanoate in 30 g of SolvessoR
150 were evenly admixed over a period of 4 hours. Subsequently a solution of 0.2 g of tert.-butylper-2-ethylhexanoate in 7 g of Sol~essoR 150 was added and heating at 100C was continued for one hour. A clear yellowish polymer solution of approximately 50% by weight was obtained. The X value of the polymer was 18.9; the mol ratio of acrylate to maleic acid anhydride to vinylether was approximately 80:10:10.

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Bxample 3 Same as Example 2, but instead o~ SolvessoR 150, a high-boiling n- and iso-paraf~in mixture o~ the Shell company ~ShellsolR K) was used as solvent.
A clear, light-yellow viscous polymer solution of approximately 50% by weight was obtained. The K value of the polymer was 30.6; the mol ratio o~ acrylate to maleic acid anhydride to vinylether was approximately 80:10:10.

Example 4 Same as Example 2, but with 65.8 g of vinyloctadecyl ether, 21.7 g of maleic acid anhydride and 112.5 g of laurylacrylate.
A clear, yellowish solution of approximately 50% by weight was obtained. The K value of the polymer was 17.3; the mol ratio of acrylate to maleic acid anhydride to vinyletller was approximately 50:25:25.

Example 5 In a reactor in accordance with Example 1, 104 g of a C18-to C22-alkylvinylether (prepared from a commerically available fatty alcohol mixture consisting of maximally 41 to 43% by weight of n-octadecanol, 9 to 13% by weight of n-eicosanol, 43 to 46% by weight of n-docosanol), 29.8 g of malaic acid anhydride and 185 g of ShellsolR K were heated to 100C in a weak nitrogen flow while being agitated and were mixed with 50 g of a solution of 375 g of laurylacrylate in 202 g of ShellsolR K and the remainder of the solution was evenly admixed within a period of 2 hours.
Simultaneously a solution of 1.5 g of tert.-butylper-2-ethylhexanoate in 75.0 g of ShellsolR K was evenly admixed over a 2 ~

period of 4 hours. Subsequently a solution of 0.5 g of tert.-~utylper-2-ethylhexanoate in 37.5 g of sOlvessoR 150 was added and heating at 100C continued for one hour. A clear, yellowish solution of approximately 50% by weight was obtained. The K value of the polymer was 20.3; the mol ra~io o~ acrylate to maleic acid anhydride to vinylether was 70:15:15.

Example 6 Same as Example 5, but instead of laurylacrylate, an n-alkylacrylate mixture, prepared from a commerically available fatty alcohol mixture of the following composition was used:
5 to 8% by weight of n-octanol, 5 to 7% by weight of n-decanol, 44 to 50% by weight of n-dodecanol, 14 to 20% by weight of n-tetradecanol, 8 to 10% by weight of n-hexadecanol and 8 to 12% by weight of n-octadecanol.
A clear, light-yellow, viscous polymer solution of approximately 50% by weight was obtained. The K value of the polymer was 18.5; the mol ratio of acrylate to maleic acid anhydride to vinylether was approximately 70:15:15.

Example 7 Same as Example 5, but instead of the C18- to C22-vinylester, 94 g of n-octadecylvinylether were used. A clear, light-yellow, viscous polymer solution of approximately 50% by weight was obtained. Tha K value o~ the polymer was 20.3; the mol ratio of acrylate to maleic acid anhydride to vinylether was approximately 70:15:15.

2 ~ 7 Example 8 In a reactor in accordance with Example 1, 207.5 g of vinyloctadecylether and 138 g of ShellsolR K were heated to lOO~C
in a weak nitrogen flow while being agikated and a solution of 1.45 g of tert.-butylper-2-ethylhexanoate in 95 g of ShellsolR K
was evenly admixed within a period of 4 hours and a solution of 88.9 g of laurylacrylate in 10 g of shellsolR K as w~ll as 68.6 g of maleic acid anhydride in liquid form were evenly admixed within a period of 2 hours. Subsequently heating was continued at 100C
for one hour and the solution was thinned with 115 g of SolvessoR
150. A clear yellowish polymer solution of approximately 50% by weight was obtained. ~he K value of the polymer was 21.5; the mol ratio of acrylate to maleic acid anhydride to vinylether was approximately 20:40:40.

Example 9 Grafting of laurylacrylate, maleic acid anhydride and octa-decylvinylether on a flow improver, consisting of 60~ by weight of ethylene and 40% by weight of vinylpropionate with a mean molecular weight of approximately 2500 (determined by vapor pressure osmometry) = Fl(A).
In a reactor in accordance with Example 1, 170 g of the flow improver Fl(A), 28.7 g of maleic acid anhydride, 51 g of octadecylvinylether, 53.9 g of laurylacrylate and 76 g of SolvessoR 150 were heated in a weak nitrogen fIow to 100C while being agitated. A mixure of 170 g of laurylacrylate, 36.2 g of octadecylvinylether and 23 g of SolvessoR 150 was evenly admixed over a period of 2 hours, and a solution of 1.02 g of tert~-butylper-2-ethylhexanoate, dissolved in 71.1 g of SolvessoR 150, was evenly admixed over a period o~ 4 hours. Subsequently a 205~3.~

solution of 0.34 g of tert.-butylper-2-ethylhexanoate in 25.5 g of SolvessoR 150 was added, heating continued for an hour and the solution thinned with 314.5 y of so1veSsoR 150. A slightly cloudy polymer solution of approximately 50% by weight, having a K value of 23.1, was obtained.

Examples 10 to 18 Reaction of the Copolymers of Examples 1 to 8 with Amines and Alcohols.

The reaction was performed by reactin~ the above polymer solutions with the appropriate amount of the amine and agitating at 100C until the anhydride bands had disappeared ~rom the infrared spectrum. Reaction with alcohols and their alkoxilates took place at 150C in 3 to 6 hours and was catalyzed with 1 mol-%
of methanesulfonic acid.

Example Polymer from Reacted Mol per No. Example No. with Mol Msa 11 1 A , 2 16 7 . EH

. : .:: ~ . , : : :.

`` ~ 0 ~ . 7 Example 19 93.5 g of the polymer solution of Example 9 were mixed with 105 g of FI(A) and 105 y of SolvessoR 150 at 60C. A mixture, cloudy at room temperature, was obtained consisting of a total of ~0 parts flow improver FI(A) and 20 parts copolymer B. The mixture is stable at room temperature for more than 10 weeks.

Example 20 25 g of a 50% by weight polymer solution in accordance with Example 13 were agitated for 30 minutes at 40C with 0.84 g of 2-ethylhexylamine and 0.84 g of SolvessoR 150. In this example the monoester is transferred into the ester/ammonia salt.

A Commercially available amine mixture of a hydrogenated di-tallow fat-amine with the following chain length distribution: 1% n-C12, 4% n-Cl4, 31%
n-C16~ 59% n-C18, the rest is unsaturated O n-octadecylamine T Tallow fat alcohol (aprx. 30% by weight of C16 and 70% by weight of C18) AP-8 Lutensol AP 8 (Alkylphenol 8 mol ethylene oxide) AT-ll Lutensol AT 11 (C16/C18 fatty alcohol ~ 11 mol ethylene oxide) 2 ~

Application Examples The following meanings apply to what follows:

FI Flow improver, in particular FI(A) Ethylene/vinylpropionate (with aprx. 40% by weight of vinylpropionate) of a mean molecular weight of approximately 2500 (determined by vapor pressure osmometry) FI(B) Ethylene/vinylacetate (with aprx. 30~ by weight of vinylacetate) of a mean molecular weight of approximately 2500 The flow improvers FI(A) and FI(B) are commercially available products, for example the KerofluxR brands of BASF.

Heating oil and Diesel fuel of a quality commercially available in West Germany were used as middle distillates. They have been designated as middle distillates I, II, III and IV.

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Middle Distillate I II III IV

Cloud point (C) +6 ~2 +4 +5 CFPP ( C) O - 3 -1 -2 Initial boiling point (C) 155 175 169 ~74 20% boiling point (C) 232 247 222 219 50% boiling point (C) 280 285 262 272 90% boiling point (C) 352 354 351 365 Final boiling point (C) 382 375 381 385 Test Method The cold filter plugging point ~CFPP) in accordance with DIN 51 428 was measured. The results are combined in the Table below.

Table Te~t Additive Dosage CFPP (C) in the Middle Distillate No. (ppm)*
I II , III IV
.
1 Without - 0 (~3) (-1) t-2 2 FI~A) 300 - (-6) 3 FI(A) 500 (-3) - (-2) (-3) 4 FI(B) 500 (-3) - (~4) (-2) Copolymer 1 500 (-1) - _ _ 6 FI(A) 2S0 (~10) - - -Copolymer 1 250 ' ' ' ' ' '' ' ' ' ' ' ! . . ' 7 FI(A) 400 (-13) _ (-19) (-16) Copolymer 1 100 8 FI(A) 240 (-13) Copolymer 1 60 9 FI(B) 400 (-16 Copolymer 1 100 FI(A) 400 (-15) ~ (-15) (-16) Copolymer 2 100 ll FI(A) 240 - (-13) Copolymer 2 60 12 FI(A) 400 (-17~ - _ _ Copolymer 3 lO0 13 FI(A) 400 (-13) Copolymer 4 lO0 14 FI(A) 400 (-16) Copolymer 5 100 FI(A) 400 (-14) Copolymer 6 100 16 FI(A) 400 (-15) _ _ _ Copolymer 7 100 17 FI(A) 400 (-14) - _ _ Copolymer 8 100 18 FI(A) 400 (-14) - S
Copolymer 10 100 l9 FI(A) 400 (-16) Copolymer 11 100 FI(A) 400 (-13) Copolymer 12 lO0 21 FI(A) 400 (-16) - - -Copolymer 13 100 22 FI(A) 400 ~-15) _ =
Copolymer 14 lO0 -2~-2 0 ~

23 FI(A) 400 (~
Copolymer 15 100 24 FI(A) 400 (-13) ~ - _ Copolymer 16 100 FI(A) 400 (-15) Copolymer 17 100 26 FI(A) 400 (-18) Copolymer 18 100 27 Copolymer 19 500 (-13) ~ ~ ~
28 FI(A) 400 t-15) - _ _ Copolymer 20 100 * 50% by weight solutions of each one of the flow improvers FI(A) and FI(B) as well as of the copolymers were admixed, i.e.
the admixture of the active substance corresponds ~o one-half of the values recited in the Table.
As shown by the above examples, the conventional flow improvers FI(A) and FI(B) show unsatis~actory effects in the middle distillates. Adding only the copolymers of the invention even worsens the CFPP of the middle distillates. The synergistic effect of the flow improvers and the copolymers of the invention are made clear by Examples 6 to 28.

.~

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WHAT IS CLAIMED IS:

1. Crude oil middle distillates with improved cold ~low properties, containing small amounts of A. conventional flow improver on an ethylene base, and B. copolymers which consist of a. of 10 to 90 mol-% of one or more alkylacrylates or alkylmethacrylates with c1- to C3o-alkyl chains, and b. o~ 5 to 60 mol-% of one or more ethylenically unsaturated dicarboxylic acids or their anhydrides, and c. of 5 to 60 mol-% of one or several alkylvinylethers with C18- to C28-alkyl side chains, where the quantitative proportion of A to B is 40 to 60 and 95 to 5.

2. Crude oil middle distillates in accordance with claim 1, characterized in that the copolymers B consist of 40 to 90 mol-~ of the monomers recited under a. and of 5 to 40 mol-% of each of the monomers recited under b. and c.

3. Crude oil middle distillates in accordance with claim 1, characterized in that the copolym~rs consist of C4- to C22-alkyl(meth)acrylates and maleic acid anhydride or itaconic acid anhydride and C18- to C2~-alkyl~inylethers.

4. Crude oil middle distillates in accordance with claim 1, characterized in that the alkyl substituents in the copolymers are straight-chain and linear.

-2~-. 2 ~

5. Crude oil middle distillates in accordance with claim 1, characterized in that the dicarboxylic acids or their anhydrides in the copolymers B are reacted with compounds containing amino groups and/or hydroxyl groups.

6. Crude oil middle distillates in accordance with claim 1, characterized in that the conventional flow improvers are copolymers of ethylene with vinylacetate, vinylpropionate or ethylhexylacrylate.

7. Crude oil middle distillates in accordance with claim 1, characterized in that the copolymers are grafted from 0 to 100%
on the conventional flow improvers.

8. Crude oil middle distillates in accordance with claim 1, characterized in that crude oil middle distillates contain the flow improvers A and the copolymers B together in shares of 50 to 5000 ppm.

Claims

1. Crude oil middle distillates with improved cold flow properties, containing small amounts of A. conventional flow improver on an ethylene base, and B. copolymers which consist of a. of 10 to so mol-% of one or more alkylacrylates or alkylmethacrylates with C1- to C30-alkyl chains, and b. of 5 to 60 mol-% of one or more ethylenically unsaturated dicarboxylic acids or their anhydrides, and c. of 5 to 60 mol-% of one or several alkylvinylethers with C18- to C28-alkyl side chains, where the quantitative proportion of A to B is 40 to 60 and 95 to 5.

2. Crude oil middle distillates in accordance with claim 1, characterized in that the copolymers B consist of 40 to 90 mol-% of the monomers recited under a. and of 5 to 40 mol-% of each of the monomers recited under b. and c.

3. Crude oil middle distillates in accordance with claim 1, characterized in that the copolymers consist of C4- to C22-alkyl(meth)acrylates and maleic acid anhydride or itaconic acid anhydride and C18- to C28-alkylvinylethers.

4. Crude oil middle distillates in accordance with claim 1, characterized in that the alkyl substituents in the copolymers are straight-chain and linear.