EP0900836B2 - Additive for mineral oils and mineral oil distillates flowability improvement - Google Patents

Abstract

The additive comprises a mixture containing either and/or ester as solvent agent. An additive to improve the flowability of paraffin-containing mineral oil distillate comprises a mixture containing an ethylene/vinylester co- or terpolymer and at least one paraffin disperser. The ether is of formula R-O-R', where R = 4-30C linear or branched alkyl or alkenyl groups and R' = 1-30C linear or branched alkyl or alkenyl groups. The ester is one or more CO(s) with 4-30C )oxygen residue) and one or more alcohol with 1-30C (alcohol residue). The ether and/or ester is/are cyclic, having a ring size of 6-30C. An Independent claim is also included for improving the flowability of mineral oils and mineral oil distillate.

Description

The invention relates to an additive for improving the flowability of paraffin-containing mineral oils and mineral oil distillates, containing flow improvers based on ethylene-vinyl ester copolymers and terpolymers, polar nitrogen compounds and ethers and / or esters as solubilizers.

Depending on the origin of the crude oils, crude oils and middle distillates obtained by distillation of crude oils, such as gas oil, diesel oil or fuel oil, contain different amounts of n-paraffins, which crystallize out as platelet-shaped crystals when the temperature is lowered and partly agglomerate with the inclusion of oil. As a result of this crystallization and agglomeration, the flow properties of the oils or distillates deteriorate, which can lead to disruptions in the extraction, transport, storage and / or use of the mineral oils and mineral oil distillates. When transporting mineral oils through pipelines, the crystallization phenomenon, especially in winter to deposits on the pipe walls, in some cases, eg. B. at standstill a pipeline, even lead to their complete blockage. During storage and further processing of the mineral oils, it may also be necessary in winter to store the mineral oils in heated tanks. In the case of mineral oil distillates, as a result of the crystallization, blockages of the filters in diesel engines and firing systems may occur, as a result of which reliable metering of the fuels is prevented and, under certain circumstances, a complete interruption of the fuel or heating agent supply occurs.

In addition to the classical methods for removing the crystallized paraffins (thermal, mechanical or with solvents), which relate only to the removal of already formed precipitates, chemical additives (so-called flow improvers) have been developed in recent years. By physical interaction with the precipitated paraffin crystals, these cause their shape, size and adhesion properties to be modified. The additives act as additional nuclei and partially crystallize out with the paraffins, resulting in a larger number of smaller paraffin crystals with altered crystal form. The modified paraffin crystals are less prone to agglomeration, so that the oils added with these additives can still be pumped or processed at temperatures that are often more than 20 ° lower than with non-additive oils.

Typical flow improvers for crude oils and middle distillates are copolymers and terpolymers of ethylene with carboxylic acid esters of vinyl alcohol.

Another object of flow improver additives is to disperse the precipitated paraffin crystals, i. the delay or prevention of the sedimentation of paraffin crystals and thus the formation of a paraffin-rich layer at the bottom of storage containers.

In the prior art, among others, polar nitrogen compounds are known as paraffin dispersants, which can generally be used together with co- or terpolymers of ethylene and vinyl esters for the addition of mineral oils and mineral oil distillates.

However, in many cases the desired use of concentrates of polar nitrogen compounds as paraffin dispersants together with copolymers and terpolymers of ethylene and vinyl esters encounters technical difficulties, since these substances are only very poorly soluble in one another. In the prior art, therefore, various solubilizers are proposed, the effect of which is often unsatisfactory.

DE-A-40 19 623 discloses crystallization inhibitors for paraffins in petroleum fractions consisting of fatty amines and solutions of benzoic or formic acid in methanol, ethanol, cyclohexanol or isopropanol.

EP-A-0 104 015 discloses the use of weak organic acids, especially aromatic acids such as benzoic acid, alkylphenols and alkarylsulfonic acids to improve the solubility of nitrogen compounds in oils.

U.S. 4,210,424 discloses the use of polymers derived from carboxylic acid esters bearing alkyl side chains of from 6 to 30 carbon atoms, and / or C ₈ -C ₁₈ alkanols as solubilizers in compositions of ethylene copolymers, paraffin waxes and nitrogen compounds.

EP-A-0 733 694 discloses solvent mixtures of aliphatic or alicyclic alcohols having at least 4 carbon atoms and aromatic hydrocarbons in a ratio of 10: 1 to 1: 2. The solvents are used to form a homogeneous mixture together with oil-soluble additives containing NR groups wherein R is a hydrocarbon radical of 8 to 40 carbon atoms.

1. A) herkömmlicher Fließverbesserer auf Ethylenbasis und
2. B) Copolymere, die
   1. a) zu 10 bis 90 mol-% aus einem oder mehreren Alkylacrylaten oder Alkylmethacrylaten mit C₁- bis C₃₀-Alkylketten und
   2. b) zu 5 bis 60 mol-% aus einer oder mehreren ethylenisch ungesättigter Dicarbonsäuren oder deren Anhydride und
   3. c) zu 5 bis 60 mol-% aus einem oder mehreren Alkylvinylethem mit C₁₈bis C₂₈-Alkylseitenketten bestehen
   und das Gewichtsverhältnis von A zu B zu 60 bis 95 zu 5 beträgt, welche Phthalate enthalten können.

EP-A-0 485 774 discloses petroleum middle distillates having improved cold flow properties, containing small amounts

1. A) conventional ethylene-based flow improvers and
2. B) Copolymers which
   1. a) from 10 to 90 mol% of one or more alkyl acrylates or alkyl methacrylates having C ₁ to C ₃₀ alkyl chains and
   2. b) from 5 to 60 mol% of one or more ethylenically unsaturated dicarboxylic acids or their anhydrides and
   3. c) consist of 5 to 60 mol% of one or more alkyl vinyl ethers having C ₁₈ to C ₂₈ alkyl side chains
   and the weight ratio of A to B is from 60 to 95 to 5, which may include phthalates.

EP-A-0 398 101 discloses reaction products of aminoalkylene polycarboxylic acids with secondary amines and their use as an additive to middle distillates optionally together with as flow improvers known ethylene copolymers and conductivity improvers, wherein 2-EH-phthalate may be included.

The task was therefore to find more efficient solubilizers between the polar nitrogen compounds and the ethylene / vinyl ester copolymers and terpolymers.

Surprisingly, it has been found that ethers and esters as well as their mixtures are excellent solubilizers for these flow improver compositions.

1. a) die Ether der Formel 1 entsprechen
   
           R - O - R'     (1),
   
   worin R für lineare oder verzweigte Alkyl- oder Alkenylgruppen mit 4 bis 30 Kohlenstoffatomen und R' für lineare oder verzweigte Alkyl- oder Alkenylgruppen mit 1 bis 30 Kohlenstoffatomen steht,
2. b) die Ester sich von ein- oder mehrwertigen Carbonsäuren mit linearen oder verzweigten Alkyl- oder Alkenylgruppen mit 5 bis 22 Kohlenstoffatomen (Säurerest) und von ein- oder mehrwertigen Alkoholen mit linearen oder verzweigten Alkyl- oder Alkenylgruppen mit 2 bis 22 Kohlenstoffatomen (Alkoholrest) ableiten, oder
3. c) die Ether und/oder Ester cyclisch sind, wobei R und R' bzw. der Säure- und Alkoholrest einen Ring mit 8 bis 22 Ringgliedern bilden.

The invention provides an additive for improving the flowability of paraffin-containing mineral oils and mineral oil distillates, comprising a mixture of at least one EthylenNinylester co- or terpolymer and at least one nitrogen-containing paraffin dispersant, which is a polar, low molecular weight or polymeric oil-soluble compound having one or more at least one C ₈ -C ₂₆ alkyl chain containing substituted amide and / or imide groups, and / or carries one or more ammonium groups, which is derived from amines having one or two C ₈ -C ₂₆ alkyl groups, characterized in that said Contains mixture of ether and ester as a solubilizer, wherein

1. a) the ethers of formula 1 correspond
   
   R - O - R '(1),
   
   wherein R is linear or branched alkyl or alkenyl groups having 4 to 30 carbon atoms and R 'is linear or branched alkyl or alkenyl groups having 1 to 30 carbon atoms,
2. b) the esters are mono- or polybasic carboxylic acids having linear or branched alkyl or alkenyl groups having 5 to 22 carbon atoms (acid radical) and mono- or polyhydric alcohols having linear or branched alkyl or alkenyl groups having 2 to 22 carbon atoms (alcohol radical) derive, or
3. c) the ethers and / or esters are cyclic, where R and R 'or the acid and alcohol radical form a ring having 8 to 22 ring members.

Another object of the invention is a process for improving the flowability of mineral oils and mineral oil distillates, characterized in that they are added to the inventive additive.

R and the acid radical are preferably linear or branched alkyl or alkenyl groups having 5 to 22 carbon atoms. R 'and the alcohol radical are preferably linear or branched alkyl or alkenyl groups having 2 to 22 carbon atoms.

Examples of ethers are dihexyl ether, dioctyl ether, di (2-ethylhexyl) ether, and examples of esters are oleic acid ester, 2-ethylhexyl stearate, 2-ethylhexyl acid butyrate, ethyl octanoate, ethylhexanoate, butyl 2-ethylhexylate, 2-ethylhexyl butyrate and Called 2-ethylhexyl acid 2-ethylhexyl ester.

When the solubilizers are esters, the use of mono- and diesters of both dialcohols and dicarboxylic acids is preferred. As an example of esters, adipic acid di (2-ethylhexyl ester) may be mentioned.

It is furthermore preferred to add to the additive, in addition to the ethers and / or esters, up to 30% by weight of alkylphenol-aldehyde resins and / or up to 10% by weight of alcohols, aldehydes and / or acetals (in each case based on the entire preparation) , The mixtures may further contain aliphatic and / or aromatic solvents.
In a preferred embodiment of the invention, mixtures containing ethers and esters, such as, for example, as a by-product of the oxo process, are used.

In a further preferred embodiment of the invention, a solvent mixture originating from the oxosynthesis, hereinafter referred to as MS, is added as a solubilizer.

MS is a mixture of a number of aliphatic and cyclic non-aromatic hydrocarbons. The main components of MS can be found in the following table: component Concentration range (wt%) Di-2-ethylhexyl 10 - 25 2-ethylhexyl acid-2-ethylhexyl 10 - 25 C ₁₆ lactones 4 - 20 2-Ethylhexylbutyrat 3 - 10 2-ethylhexanediol- (1,3) glycol mono-n-butyrate 5 - 15 2-ethylhexanol 4 - 10 C ₄ to C ₈ acetals 2 - 10 2-ethylhexanediol- (1,3) 2 - 5 Ethers and esters ≥ C ₂₀ 0 - 20

• Ethylen-Vinylacetat-Copolymere mit 10- 40 Gew.-% Vinylacetat und 60 - 90 Gew.-% Ethylen;
• die aus DE-A-34 43 475 bekannten Ethylen-Vinylacetat-Hexen-Terpolymere;
• die in EP-A-0 203 554 beschriebenen Ethylen-Vinylacetat-Diisobutylen-Terpolymere;
• die aus EP-A-0 254 284 bekannte Mischung aus einem Ethylen-Vinylacetat-Diisobutylen-Terpolymerisat und einem EthylenNinylacetat-Copolymer;
• die in EP-A-0 405 270 offenbarten Mischungen aus einem Ethylen-Vinylacetat-Copolymer und einem Ethylen-Vinylacetat-N-Vinylpyrrolidon-Terpolymerisat;
• die in EP-A-0 463 518 beschriebenen Ethylen/Vinylacetat/i-Butylvinylether-Terpolymere;
• die in EP-A-0 491 225 offenbarten Mischpolymerisate des Ethylens mit Alkylcarbonsäurevinylestern;
• die aus EP-A-0 493 769 bekannten Ethylen/Vinylacetat/ Neononansäurevinylester bzw. Neodecansäurevinylester-Terpolymere, die außer Ethylen 10-35 Gew.-% Vinylacetat und 1 - 25 Gew.-% der jeweiligen Neoverbindung enthalten;
• die in DE-A-196 20 118 beschriebenen Terpolymere aus Ethylen, dem Vinylester einer oder mehrerer aliphatischer C₂-C₂₀-Monocarbonsäuren und 4-Methylpenten-1; und
• die in der nicht vorveröffentlichten deutschen Patentanmeldung mit dem Aktenzeichen 196 20 119.5 offenbarten Terpolymere aus Ethylen, dem Vinylester einer oder mehrerer aliphatischer C₂-C₂₀-Monocarbonsäuren und Bicyclo[2.2.1]hept-2-en.

As ethylene / vinyl ester copolymers or terpolymers, it is possible to use all known copolymers or terpolymers of this type and mixtures thereof which, taken alone, improve the cold flow properties of mineral oils or mineral oil distillates. Suitable copolymers or terpolymers include, for example:

• Ethylene-vinyl acetate copolymers with 10-40% by weight of vinyl acetate and 60-90% by weight of ethylene;
• from DE-A-34 43 475 known ethylene-vinyl acetate-hexene terpolymers;
• in the EP-A-0 203 554 described ethylene-vinyl acetate-diisobutylene terpolymers;
• from EP-A-0 254 284 known mixture of an ethylene-vinyl acetate-diisobutylene terpolymer and an ethylene-vinyl acetate copolymer;
• in the EP-A-0 405 270 disclosed blends of an ethylene-vinyl acetate copolymer and an ethylene-vinyl acetate-N-vinylpyrrolidone terpolymer;
• in the EP-A-0 463 518 described ethylene / vinyl acetate / i-butyl vinyl ether terpolymers;
• in the EP-A-0 491 225 disclosed copolymers of ethylene with alkylcarboxylic vinyl esters;
• from EP-A-0 493 769 known ethylene / vinyl acetate / vinyl neononanoate or vinyl neodecanoate terpolymers containing, in addition to ethylene, 10-35% by weight of vinyl acetate and 1-25% by weight of the respective neo compound;
• in the DE-A-196 20 118 described terpolymers of ethylene, the vinyl ester of one or more aliphatic C ₂ -C ₂₀ monocarboxylic acids and 4-methylpentene-1; and
• the disclosed in the non-prepublished German patent application with the file number 196 20 119.5 terpolymers of ethylene, the vinyl ester of one or more aliphatic C ₂ -C ₂₀ monocarboxylic acids and bicyclo [2.2.1] hept-2-ene.

Preferred are such ethylene-vinyl ester copolymers or terpolymers having an ethylene content of 60-90 wt .-% and mixtures thereof.

aufweisen, worin R³ für gesättigtes, verzweigtes C₆-C₁₆-Alkyl steht, das ein tertiäres Kohlenstoffatom aufweist. Die für die Additivmischung verwendeten Co- und Terpolymere können neben den genannten Monomereinheiten auch noch bis zu 5 Mol-% von Monomereinheiten enthalten, die sich von Olefinen wie etwa Vinylether, Acrylsäurealkylester, Methacrylsäurealkylester, Isobutylen oder von höheren Olefinen mit mindestens 5 Kohlenstoffatomen wie beispielsweise Hexen, 4-Methylpenten, Octen oder Diisobutylen ableiten.Particularly preferred terpolymers of ethylene and vinyl esters are those which, in addition to 65 to 94 mol% of the structural units derived from ethylene and 5 to 35 mol% of vinyl acetate, contain 1 to 25 mol% of structural units of the formula (2)

wherein R ^{3 is} saturated, branched C ₆ -C ₁₆ alkyl having a tertiary carbon atom. The copolymers and terpolymers used for the additive mixture may also contain up to 5 mol% of monomer units derived from olefins such as vinyl ethers, alkyl acrylates, alkyl methacrylates, isobutylene or higher olefins having at least 5 carbon atoms such as Witches, 4-methylpentene, octene or diisobutylene derived.

• eine oder mehrere mit mindestens einer C₈-C₂₆-Alkylkette substituierte Ester-, Amid- und/oder Imidgruppen enthalten
• und/oder eine oder mehrere Ammoniumgruppen tragen, die sich von Aminen mit einer oder zwei C₈-C₂₆-Alkylgruppen ableiten.

As paraffin dispersants, for example, polar, low molecular weight or polymeric oil-soluble compounds are suitable, the

• contain one or more substituted with at least one C ₈ -C ₂₆ alkyl chain ester, amide and / or imide groups
• and / or carry one or more ammonium groups derived from amines having one or two C ₈ -C ₂₆ alkyl groups.

Of the above-mentioned paraffin dispersants, the polar nitrogen-containing compounds are preferred.

As monomeric polar nitrogen-containing compounds, for example, the following substances can be used:

In EP-A-0 413 279 Suitable reaction products of Alkenylspirobislactonen be described with amines.

Also in EP-A-0 061 894 disclosed oil-soluble reaction products of phthalic anhydride with amines can be used in admixture with ethylene-vinyl acetate copolymers.
Furthermore, the off EP-A-0 597 278 known reaction products of Aminoalkylencarbonsäuren with primary or secondary amines suitable as monomeric nitrogen-containing compounds.

• Die aus EP-A-0 154 177 bekannten Umsetzungsprodukte von alternierenden Copolymeren auf der Basis von α,β-ungesättigten Verbindungen und Maleinsäureanhydrid mit primären Monoalkylaminen und aliphatischen Alkoholen;
• die aus EP-A-0 436 151 bekannten Umsetzungsprodukte von Copolymeren auf der Basis von Maleinsäureanhydrid und α,β-ungesättigten Verbindungen wie Styrol mit Dialkylaminen;
• die in EP-A-0 283 293 offenbarten Copolymere auf der Basis von aliphatischen Olefinen und Maleinsäureanhydrid, wobei das Copolymere sowohl Ester- als auch Amidgruppen aufweist, von denen jede eine Alkylgruppe mindestens 10 Kohlenstoffatome enthält;
• die aus EP-A-0 436 151 bekannten Umsetzungsprodukte von Copolymeren auf der Basis von Maleinsäureanhydrid und α,β-ungesättigten Verbindungen wie Styrol mit Dialkylaminen;
• die in EP-A-0 606 055 beschriebenen Terpolymere auf der Basis von α,β-ungesättigten Dicarbonsäureanhydriden, α,β-ungesättigten Verbindungen und Polyoxyalkylenethern von niederen, ungesättigten Alkoholen;
• die aus EP-A-0 688 796 bekannten Copolymere auf der Basis von α,β-ungesättigten Olefinen mit mindestens 3 C-Atomen und α,β-ungesättigten Dicarbonsäureanhydriden, wobei die Dicarbonsäureanhydrideinheiten durch polymeranaloge Umsetzung mit Polyetheraminen oder Alkanolaminen in Imid-, Amid- und Ammonium-Einheiten überführt wurden;
• die in der nicht vorveröffentlichten deutschen Patentanmeldung mit dem Aktenzeichen 196 45 603.7 beschriebenen statistischen Co- und Terpolymere auf der Basis von Ethylen, α,β-ungesättigten Dicarbonsäureanhydriden sowie gegebenenfalls weiteren α,β-ungesättigten Verbindungen, wobei die Dicarbonsäureanhydrideinheiten zu einem hohen Anteil als Imideinheiten vorliegen und in geringerem Anteil als Amid/Ammoniumsalzeinheiten.

As polymeric polar nitrogen-containing compounds it is preferred to use copolymers or terpolymers based on α, β-unsaturated compounds and maleic acid. Suitable examples are:

• From EP-A-0 154 177 known reaction products of alternating copolymers based on α, β-unsaturated compounds and maleic anhydride with primary monoalkylamines and aliphatic alcohols;
• from EP-A-0 436 151 known reaction products of copolymers based on maleic anhydride and α, β-unsaturated compounds such as styrene with dialkylamines;
• in the EP-A-0 283 293 disclosed copolymers based on aliphatic olefins and maleic anhydride, said copolymer having both ester and amide groups, each of which contains an alkyl group of at least 10 carbon atoms;
• from EP-A-0 436 151 known reaction products of copolymers based on maleic anhydride and α, β-unsaturated compounds such as styrene with dialkylamines;
• in the EP-A-0 606 055 described terpolymers based on α, β-unsaturated dicarboxylic anhydrides, α, β-unsaturated compounds and polyoxyalkylene ethers of lower, unsaturated alcohols;
• from EP-A-0 688 796 known copolymers based on α, β-unsaturated olefins having at least 3 C atoms and α, β-unsaturated dicarboxylic anhydrides, wherein the dicarboxylic anhydride were converted by polymer analogous reaction with polyetheramines or alkanolamines in imide, amide and ammonium units;
• in the not previously published German patent application with the file number 196 45 603.7 described statistical copolymers and terpolymers based on ethylene, α, β-unsaturated dicarboxylic anhydrides and optionally further α, β-unsaturated compounds, wherein the dicarboxylic acid anhydride units are present in a high proportion as imide units and less than amide / ammonium salt units.

The mixtures according to the invention are added to mineral oils or mineral oil distillates in the form of concentrates. These concentrates preferably contain 1 to 70, in particular 5 to 60 wt .-% of vinyl ester copolymers and paraffin dispersants in the ratio 1:10 to 10: 1, in particular in the ratio 1: 5 to 5: 1 and 1 to 60 wt .-% in particular from 5 to 50% by weight of the solvents according to the invention. The remainder to 100% may be aliphatic, aromatic solvents and alkylphenol resins, alcohols, aldehydes and / or acetals. Mineral oils or mineral oil distillates improved in their rheological properties by the mixtures according to the invention contain from 0.001 to 2, preferably from 0.005 to 0.5,% by weight of the mixtures, based on the distillate.

With the same result, to optimize the effectiveness as a flow improver for certain substrates, the mixtures according to the invention can also be used together with one or more oil-soluble co-additives, which already by itself the cold flow properties of crude oils, lubricating oils or fuel oils improve, such as comb polymers. Comb polymers are polymers in which hydrocarbon radicals having at least 8, in particular at least 10, carbon atoms are bonded to a polymer backbone. Preferably, they are homopolymers whose alkyl side chains contain at least 8 and in particular at least 10 carbon atoms. In the case of copolymers, at least 20%, preferably at least 30% of the monomers have side chains (compare Comb-like Polymers - Structure and Properties, NA Platé and VP Shibaev, J. Polym, Sci Macromolecular Revs 1974, 8, 117 ff). Examples of suitable comb polymers are, for. As fumarate / vinyl acetate copolymers (see. EP-A-0 153 176 ), Copolymers of a C ₆ -C ₂₄ -α-olefin and a NC ₆ - to C ₂₂ -alkylmaleimide (cf. EP-A-0 320 766 Further, esterified olefin / maleic anhydride copolymers, polymers and copolymers of α-olefins and esterified copolymers of styrene and maleic anhydride.

The mixing ratio (in parts by weight) of the mixtures according to the invention with comb polymers is 1:10 to 20: 1, preferably 1: 1 to 10: 1.

The mixtures according to the invention are suitable for improving the cold flow properties of animal, vegetable or mineral oils. They are particularly well suited for use with middle distillates. As middle distillates are in particular those mineral oils which are obtained by distillation of crude oil and boil in the range of 120 to 450 ° C, for example kerosene, jet fuel, diesel and fuel oil. The concentrates show a significantly improved storage stability, especially at low temperatures.

The novel mixtures may be used alone or together with other additives, for example dewaxing aids, corrosion inhibitors, antioxidants, lubricity additives or sludge inhibitors. The addition of these additives to the oil can be carried out together with the mixture according to the invention or else separately.

Examples

A) ethylene-vinyl acetate copolymer with 31 wt .-% vinyl acetate and a measured at 140 ° C melt viscosity of 160 mPas, 58 wt .-% in kerosene.
B) ethylene vinyl acetate-Versaticsäurevinylester terpolymer with 31 wt .-% vinyl acetate, 4 wt .-% Versaticsäurevinylester and measured at 140 ° C melt viscosity of 180 mPas.
C) Reaction product of a terpolymer of C _14/16 α-olefin, maleic anhydride and allyl polyglycol with 2 equivalents of di-tallow fatty amine, 50% strength by weight in solvent naphtha (according to US Pat EP-A-0 606 055 ).
D) nonylphenol-formaldehyde resin according to DE-A-31 42 955 prepared by acid catalyzed condensation of p-nonylphenol and formaldehyde, 50% in solvent naphtha.
E) mixture of C + D in the ratio 1: 1
F) Amide ammonium salt of a spirobislactone according to EP-A-0 413 279 , 50% by weight in solvent naphtha.
MS) solvent mixture consisting of the following main components: Di-2-ethylhexyl 20% 2-ethylhexyl acid-2-ethylhexyl 14% C ₁₆ lactones 17% 2-ethylhexanediol- (1,3) glycol mono-n-butyrate 10% 2-Ethylhexylbutyrat 5% 2-ethylhexanol 5% C ₄ to C ₈ acetals 10% Ether / ester ≥C ₂₀ 19%

The active compounds listed above are homogenized according to the amounts shown in Tables 1 and 2 at 80 ° C with stirring. Subsequently, the stability of the solutions after 3 days of storage at room temperature or at 60 ° C is visually assessed. Table 1: Ethers and esters as solubilizers. All data in% by weight. A B C F e solubilizers 23 ° C 60 ° C 50 50 - (Comparison) 2-phase 2-phase 50 50 - (Comparison) 2-phase 2-phase 50 50 - (Comparison) 2-phase 2-phase 67 33 - (Comparison) 2-phase 2-phase 40 40 20% kerosene (comparison) 2-phase cloudy 40 40 20% kerosene (comparison) 2-phase clear 40 40 20% solvent naphtha (comparison) 2-phase cloudy 40 40 20% solvent naphtha (comparison) 2-phase cloudy 60 30 10% MS cloudy, cloudy, homogeneously homogeneously 40 40 20% MS cloudy, clear, homogeneously homogeneously 40 40 20% MS cloudy, clear, homogeneously homogeneously 53 27 20% MS cloudy, clear, homogeneously homogeneously 40 40 20% dihexyl ether (comparison) cloudy, clear, 50 50 -(Comparison) 2-phase 2-phase homogeneously homogeneously 40 40 20% dihexyl ether (comparison) cloudy, clear, homogeneously homogeneously 40 40 20% dihexyl ether (comparison) cloudy, clear, homogeneously homogeneously 53 27 20% dihexyl ether (comparison) cloudy, clear, homogeneously homogeneously 40 40 20% adipic acid di (2-EH ester) (comparative) cloudy, clear, homogeneously homogeneously 40 40 20% adipic acid di (2-EH ester) (comparative) cloudy, clear, homogeneously homogeneously 40 40 20% adipic acid di (2-EH ester) (comparative) cloudy, clear, homogeneously homogeneously 53 27 20% adipic acid di (2-EH ester) (comparative) cloudy, clear, homogeneously homogeneously 40 40 20% hexanoic acid ethyl ester (comparison) cloudy, clear, homogeneously homogeneously 53 27 20% octanoic acid ethyl ester (comparison) cloudy, clear, homogeneously homogeneously 25 50 25% MS clear, clear, homogeneously homogeneously 34 33 33% MS cloudy, clear, homogeneously homogeneously 25 50 25% dihexyl ether (comparative) clear, clear, homogeneously homogeneously 34 33 33% dihexyl ether (comparative) cloudy, clear, homogeneously homogeneously 25 50 25% adipic acid di (2-EH ester) (comparative) cloudy, clear, homogeneously homogeneously 34 33 33% adipic acid di (2-EH ester) (comparative) cloudy, cloudy, homogeneously homogeneously 53 27 20% oleic acid eicosyl ester (comparative) cloudy, clear, homogeneously homogeneously 53 27 20% 2-ethylhexyl stearate (comparison) cloudy, clear, homogeneously homogeneously 50 50 - (Comparison) 2-phase 2-phase 53 27 20% 2-ethylhexyl stearate (comparison) cloudy, clear, homogeneously homogeneously 53 27 20% 2-ethylhexyl stearate (comparison) cloudy, clear, homogeneously homogeneously

Upon reheating, the mixtures according to the invention remain homogeneous.

List of used trade names

Solvent Naphtha®Shellsol AB® Solvesso 150 aromatic solvent mixtures with boiling range 180 to 210 ° C ® Solvesso 200 aromatic solvent mixture with boiling range 230 to 287 ° C ®Exxsol Dearomatized solvents in various boiling ranges, for example ®Exxsol D60: 187 to 215 ° C ®ISOPAR (Exxon) isoparaffinic solvent mixtures in various boiling ranges, for example ®ISOPAR L: 190 to 210 ° C ®Shellsol D mainly aliphatic solvent mixtures in different boiling ranges

Claims (8)

1. An additive for improving the flow properties of paraffin-containing mineral oils and mineral oil distillates, comprising a mixture of at least one ethylene/vinyl ester copolymer or terpolymer and at least one nitrogen-containing paraffin dispersant which is a polar, low-molecular-weight or polymeric oil-soluble compound which contains one or more amide and/or imide groups substituted by at least one C₈-C₂₆-alkyl chain and/or carries one or more ammonium groups derived from amines having one or two C₈-C₂₆-alkyl groups, wherein said mixture contains ethers and esters as a solubilizer, where

   a) the ethers conform to the formula 1
   
           R - O - R'     (1),
   
   in which R is a linear or branched alkyl or alkenyl group having 4 to 30 carbon atoms, and R' is a linear or branched alkyl or alkenyl group having 1 to 30 carbon atoms,

   b) the esters are derived from monobasic or polybasic carboxylic acids having linear or branched alkyl or alkenyl groups having 5 to 22 carbon atoms (acid radical) and from monohydric or polyhydric alcohols having linear or branched alkyl or alkenyl groups having 2 to 22 carbon atoms (alcohol radical), or

   c) the ethers and esters are cyclic, with R and R' or the acid and alcohol radicals forming a ring having 8 to 22 ring members.
2. An additive as claimed in claim 1, wherein the radicals R have from 5 to 22 carbon atoms and the radicals R' have from 2 to 22 carbon atoms.
3. An additive as claimed in claim 1 and/or 2, wherein the solubilizer is MS, MS having the following composition: Constituent Concentration range (% by wt.) Di-2-ethylhexyl ether 10 - 25 2-Ethylhexyl 2-ethylhexanoate 10 - 25 C16 lactones 4 - 20 2-Ethylhexyl butyrate 3 - 10 2-Ethylhexane-1,3-diol mono-n-butyrate 5 - 15 2-Ethylhexanol 4 - 10 C4- to C8-acetals 2 - 10 2-Ethylhexane-1,3-diol 2 - 5 Ethers and esters ≥ C₂₀ 0 - 20.
4. An additive as claimed in one or more of claims 1 to 3, which additionally contains up to 10% by weight of alcohols and/or up to 30% by weight of alkylphenol-aldehyde resins.
5. An additive as claimed in one or more of claims 1 to 4, which contains at least one copolymer of ethylene and one or more vinyl esters.
6. An additive as claimed in one or more of claims 1 to 5, which contains a terpolymer which, in addition to from 65 to 94 mol% of structural units derived from ethylene and from 5 to 35 mol% of structural units derived from vinyl acetate, also contains from 1 to 25 mol% of structural units of the formula (2)

   

   in which R³ is saturated, branched C₆-C₁₆-alkyl containing a tertiary carbon atom.
7. A process for improving the flow properties of mineral oils and mineral oil distillates, which comprises adding additives as claimed in one or more of claims 1 to 6.
8. Mineral oils and mineral oil distillates containing additives as claimed in one or more of claims 1 to 6.