DK164792B - USING COLOPYMERS AS ADDITIVE TO IMPROVE FLOW PROPERTIES AND DISTILLATE FUEL AND ADDITIVE CONCENTRATE - Google Patents

Abstract

The flow properties of a distillate petroleum fuel oil whose 20% and 90% distillation points differ within the range of from 65 to 100 DEG C, and/or whose 90% to final boiling point is 10 to 20 DEG C is improved by the inclusion of a copolymer of ethylene and a vinyl ester of a carboxylic acid containing 1 to 4 carbon atoms containing 32 to 35 wt % of the vinyl ester and having a number average molecular weight of 1000 to 6000.

Description

in

DK 164792 B

Mineral oils containing paraffin wax have the property of becoming less fluid as the temperature of the oil decreases. This decrease in fluidity is due to the crystallization of wax to form plate-like crystals which then form a spongy mass into which the oil is contained.

It has long been known that various compositions act as wax crystal modifiers when mixed with wax mineral oils. These compositions modify the size and shape 10 of the wax crystals and reduce the adhesion forces between the wax and the oil in such a way that the oil remains readily liquid at a low temperature.

In the literature, various means for lowering the floating point have been described, and several of these are used commercially. Eg. U.S. Patent No. 3,048,479 discloses the use of copolymers of ethylene and C ^-Cg vinyl esters, e.g. vinyl acetate, as a means of reducing the point of flow of fuels, especially heating oils, diesel and jet fuels. Polymeric hydrocarbon flow point depressants based on ethylene and higher alpha olefins, e.g. propylene is also well known. U.S. Patent No. 3,961,916 discloses the use of a blend of ethylene / vinyl acetate copolymers, one of which is a wax crystallization agent and the other a growth inhibitor, for controlling the size of the wax crystals, and mixtures of growth inhibitor and nucleating agent are disclosed. in the ratios 3: 1, 2: 1 and 1: 1.

Similarly, in GB Patent No. 1,263,152, it is suggested that the size of the wax crystals can be controlled using a copolymer with a slight degree of side chain branching.

With the increasing diversity of distillate fuels, fuel types have emerged which cannot be treated with the existing additives or which require an uneconomically high concentration of 35 additives. A particular group of fuels that present such problems are fuels which have a relatively narrow boiling range.

Fuels are often characterized by their initial boiling point, final boiling point and intermediate temperatures, whereby a certain volume percentage of the original amount of fuel is distilled.

DK 164792 B

2 ret. Fuels for which the difference between 20% and 90% distillation points are in the range of from 65 to 100 ° C, especially from 70 to 100 ° C (ASTM D86) and for which 90% boiling temperature generally differs from 10 to 30, and in particular from 10 to 25 ° C from the final boiling point, have proved particularly difficult to treat, sometimes being in fact unaffected by additives or otherwise requiring very high additive concentrations. All of the distillates mentioned herein are determined according to ASTM D86.

10 With the increase in the cost of crude oil, it has also become important for refineries to increase distillate fuel production and to optimize operations using what is termed sharp fractionation, which in turn results in distillate fuels which are difficult to treat with traditional 15 additives or requiring a degree of treatment which is unacceptable from an economic point of view. Typically sharply fractionated fuels have a difference between 90% boiling point and final boiling point of 10 to 20 ° C and generally together with a difference between 20% and 90% boiling points of 90 to 110 ° C. Both types of fuel have 20 final boiling points of more than 350 ° C, usually a final boiling point of between 350 and 375 ° C, and in particular between 350 and 370 ° C.

The copolymers of ethylene and vinyl acetate, which have found widespread use in improving the flow of the previously widely used distillate fuels, generally contained up to about 5%. 30% by weight of vinyl acetate, the additive being used to control the size of the wax crystals formed in the fuel, or containing 36% by weight or more vinyl acetate in cases where the main function was to reduce the flow point of the distillate fuel.

None of these types of additives have been found to be effective in treating the above-mentioned narrow boiling and / or sharply fractionated fuels.

The object of the invention is to provide additives with which a particularly effective improvement of the flow properties and in particular the low temperature flow properties of such narrow boiling distillate fuels, namely distillate fuel oils derived from petroleum, and whose 20% and 11% distillation fuels can be obtained. deviate by a value between 70 ° C and 100 ° C and if 90% boiling

DK 164792B

3 point differs from the final boiling point by from 10 ° C to 30 ° C and whose final boiling point is above 350 ° C of a product.

This object is achieved according to the invention using an additive comprising: i) a copolymer of ethyl one and a vinyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, the copolymer containing, on average, from 32 to 35% by weight of the vinyl ester 2Q and having a or ii) a mixture of two copolymers of ethylene and a vinyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, one of the copolymers acting as a growth inhibitor for the wax crystals and the other acting as as a nucleating agent for the wax crystals, containing at least 10 parts by weight of the growth inhibitor for each part by weight of the nucleating agent and averaging from 32 to 35% by weight of the 20 vinyl ester and having an average molecular weight of from 1000 to 6000.

In a preferred embodiment of the invention, the distillate fuel oil has a final boiling point of between 350 ° C and 375 ° C.

25

Another preferred embodiment of the invention is characterized in that the vinyl ester is vinyl acetate.

The invention further relates to a distillate fuel whose 20% and 90% distillation points deviate from 70 ° C to 100 ° C, if 90% boiling point deviates from the final boiling point by 104 ° C to 30 ° C, and the final boiling point is above 350 ° C, which This fuel is characterized in that it contains from 50 to 500 ppm (millionths) of 35 i) a copolymer of ethylene and a new synthesis of a carboxylic acid containing from 1 to 4 carbon atoms, where the copolymer contains on average from 32 to 35% by weight of the vinyl ester and has an average molecular weight by number of from 1000 to

DK 164792 B

Or ii) a mixture of two ethylene copolymers and one ethylene ester of a carboxylic acid containing from 1 to 4 carbon atoms, one of the copolymers acting as a growth inhibitor for the wax crystals and the other acting as a nucleating agent for the wax crystals which contains at least 10 parts by weight of the growth inhibitor for each part by weight of the nucleating agent and an average of from 32 to 35% by weight of the 2Q vinyl ester and having an average molecular weight by number of from 1000 to 6000.

The distillate fuel according to the invention preferably has a boiling point of between 350T and 375 ° C and most preferably between 350eC and 370eC.

15

A preferred embodiment of the distillate fuel according to the invention is characterized in that the vinyl ester is vinyl acetate.

When the additive is a mixture, the wax growth stimulant or 2q nucleating agent is a synthetic polymeric material which is soluble in the distillate at temperatures substantially above the saturation temperature, but which upon cooling of the distillate is progressively separated in the form of small particles as near the distillate. say the saturation point, e.g. cool from a point slightly above (e.g., 10 ° C above and preferably about 5 ° C above)

kV

saturation. The term "saturation temperature" indicates the lowest temperature at which the dissolved component, e.g. wax, cannot be crystallized by the solution, even if known crystallization initiation methods are used.

30

Although not known with certainty, it is believed that additional nucleating particles are secreted in a more or less continuous manner as cooling continues. These additional particles act as nucleators for the continued wax crystallization, which would effectively prevent a substantial undercooling of the distillate. The advantage of having fresh nucleation particles formed continuously is that the saturation of the distillate with n-paraffins is kept at the lowest possible level, thereby facilitating a molecule of the growth inhibitor by being incorporated into the growth center in

DK 164792 B

5 the growing crystals and in this way to stop the further growth.

The inhibitory effect of a growth inhibitor is believed to result from the presence of bulky groups in the molecule. Additional nucleating agent should be secreted to replace the deactivated growth centers. The wax growth inhibitor is more soluble in the distillate than the nucleating agent and it acts as a growth inhibitor as the wax crystal is formed.

10

The nucleating agent should not be insoluble in the distillate at elevated temperatures, nor should it begin to precipitate at a temperature substantially above that at which wax crystallization can occur. If nucleating agents are secreted at a temperature substantially above the temperature at which crystallization can occur, they tend to settle on the bottom of the container containing the distillate, rather than remain dispersed in the distillate. This factor is particularly important when the distillate is subjected to repeated heating and cooling, e.g.

20 during the hot and cold periods of the day, with no suitable redispersion of nucleating particles in the distillate being obtained. The synthetic polymeric materials used as wax growth stimulants and wax growth inhibitors may contain the same or different synthetic agents.

25

The terms wax crystal growth stimulants, wax nucleating agents and nucleating agents for wax are herein considered equivalent terms and used interchangeably.

30 Wax growth inhibitors (hereinafter sometimes referred to as wax inhibitors) usually contain in the molecular structure wax-like polymethylene segments which are capable of incorporating themselves into the lattice of the wax crystals at the lattice offset point, and also contain bulky groups which prevent the incorporation of 35 additional molecules of n-paraffin. at the lattice offset point, and by doing so, further growth of the crystal stops.

A good synthetic polymeric wax germinating agent can be selected by visually comparing a transparent container containing a

DK 164792 B

1.3% by weight solution of the potential nucleating agent in a distillate with an identical container with the same distillate but without additive content as the temperature of the two materials is reduced. The onset of wax crystallization from distillate 5 containing a polymeric material having nucleating properties will occur at a higher temperature than the temperature at which crystallization starts, without the presence of a nucleating agent. Similarly, a wax inhibitor is generally characterized by its ability to delay the initiation of crystal in the station.

The synthetic polymers used as nucleating agents and as wax growth inhibitors are copolymers of ethylene and vinyl ester and may contain the same or different ester monomers.

When the additive is a mixture of two copolymers, the vinyl ester content and molecular weight are the average of the entire mixture. However, the additive may also be a single polymer by which is meant a material formed by a single polymerization. In this case, the materials may be made by the known high-pressure or solution polymerization techniques previously proposed for the preparation of ethylene vinyl ester, especially vinyl acetate copolymers for use as fuel additives.

Typical vinyl esters for both blends and single polymers are vinyl acetate, vinyl propionate and vinyl butyrate.

The agents for improving the flow properties when incorporated into the distillate fuels are preferably effective in: 1. keeping these fuels liquid at operating temperatures, 2. inhibiting the growth of separating wax crystals when the oils are subjected to a slow cooling, i.e.. 0.1 to 1.1 ° C per day. hour, which is typical of the rates that occur when oil in bulk is subjected to atmospheric cooling, 3. to inhibit the growth of separating wax crystal! is when the oils

DK 164792 B

7 is subjected to rapid cooling, i.e. 5.6-56eC per hour, which is typical of the velocities that occur when relatively hot oil is introduced into transport lines and suddenly exposed to low temperatures.

5

All three of the above criteria are desired to be met to ensure that the fuel can be pumped and filtered under the distribution and application conditions.

When mixtures of polymers are used, the molecular weight is, as mentioned, the average molecular weight of the two polymers, and generally the preferred average molecular weight (VPO) of the nucleating agent will be in the range of 500-6000 and particularly preferably between 1200 and 6000. eg. a relatively low molecular weight ethylene vinyl ester copolymer with a relatively large vinyl ester content was found to act as a wax growth inhibitor.

On the other hand, a relatively high molecular weight copolymer of ethylene and vinyl ester and with a relatively low content of vinyl ester acts as a nucleating agent. Even more particularly, mixtures have 20 containing ethylene-vinyl acetate copolymers having average molecular weights by number of from 1200 to 6000 (VPO) having a vinyl acetate content of approx. 32-50% by weight (e.g., about 11 to 25 mol% ester) as a wax inhibitor and ethylene-vinyl acetate copolymers having an average molecular weight by number of from about 500 to 10,000 (VPO) and vinyl acetate comonomer weight ratios of from 1 to 30 weight percent (e.g., about 0.3 to 12 mole percent ester) as wax growth stimulant have been found to be highly effective. When the nucleating agent is an ethylene-vinyl acetate copolymer, its average molecular weight by number is preferably at least 500, preferably 1000, 30 lower and / or the ester content is at least 5% lower than the corresponding values of the wax growth inhibitor.

All molecular weights given herein are average molecular weights by number which are molecular weights measured by vapor phase osmometry (VPO), e.g. using "Mechrolab Vapor Phase Osmometer 301A". The vinyl acetate content is determined by saponification. Thus, in relation to the growth inhibitor, the nucleating agent may comprise an ethylene-vinyl acetate copolymer having a larger molecular weight if the vinyl acetate content of both polymeric materials is about

DK 164792 B

8 the same. When two synthetic polymers are used, they can be prepared separately or they can be prepared one after the other in one batch by varying the reaction conditions. The reaction conditions can be selected such that the initial polymerization reaction yields a polymer having primarily nucleating properties, and the reaction conditions can be altered to form a polymer having primarily wax growth inhibiting properties or vice versa. In this way, a mixture of polymers having both functions can be prepared.

When using two different copolymers of ethylene and vinyl acetate according to the invention, the ratios of the concentrations of vinyl acetate in the copolymer to the molecular weight of the copolymers are important, being factors that determine the role of the copolymer in question in fuel. That is, provided that the other polymeric properties are similar, they determine whether the copolymer as a whole in the mixture will act as a wax inhibitor or as a wax nucleating agent. As a very general rule of thumb, the nucleating agents should have relatively long polymethylene segments, and thus the amount of vinyl acetate should also decrease as these synthetic polymers approach low molecular weight ranges. On the other hand, the content of vinyl acetate should also increase as the molecular weight increases. Thus, the specific wax nucleating agents will comprise a copolymer of ethylene and a relatively small amount of relatively high molecular weight vinyl acetate. On the other hand, the wax inhibitor will generally be a relatively low molecular weight copolymer with a relatively high vinyl acetate content, with the wax inhibiting function more dependent on the presence of bulky groups such as ester groups attached to the copolymer's molecular skeleton.

30

The invention further relates to an additive concentrate for use in distillate fuels, the additive concentrate being characterized in that it comprises a solution in a hydrocarbon solvent of from 5 to 60% by weight of 35 i) a copolymer of ethylene and a viyl ester of a carboxylic acid containing from 1 to 4 carbon atoms where the copolymer contains, on average, from 32 to 35% by weight of the vinyl ester and has an average molecular weight by number of 1000 to

DK 164792 B

Or ii) a mixture of two copolymers of ethylene and a vinyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, one of the copolymers acting as a growth inhibitor for the wax crystals and the other acting as a nucleating agent for the wax crystals, which mixture contains at least 10 parts by weight of the growth inhibitor for each part by weight of the nucleating agent and an average of from 32 to 35% by weight of 10 µl of the new ester and with an average molecular weight by number of from 1000 to 6000.

Although separate copolymers can be mixed directly into the fuel, it will usually be advantageous to prepare a concentrate. This can be done by first reconciling each with a separate solvent, but most preferably it is dissolved each in a common solvent.

Thus, both the preferred relatively low molecular weight (second) copolymer with a high vinyl content and the preferred first relatively high molecular weight copolymer with a low vinyl acetate content can be dissolved in petroleum or a heavy aromatic naphtha. Preferred concentrates contain 5-60%, preferably 10-50% total copolymer, the remainder being a hydrocarbon oil solvent.

The wax inhibiting copolymers can be prepared by known methods using free radical initiators, preferably organic peroxides. Suitable methods are high temperature and high pressure methods or the dissolution methods described in U.S. Patents 3,048,479 and 3,093,623 and British Patent Specification No. 1,263,152.

In one respect, the fuels to which the invention relates are difficult to treat with traditional additives due to the relatively narrow boiling range of the 20-90% fractions of the fuel, with the 90% fraction boiling at temperatures of 70 ° C. 100 ° C above the boiling point of the 20% fraction and / or due to the relatively narrow gap between the 90% boiling point and the final boiling point which is less than 30 ° C and even in some cases less than 20 ° C.

Conveniently, a total amount of from 0.005 to 0.05 is used

DK 164792 B

10% by weight of additive, based on the weight of the fuel, and preferably from 0.01 to 0.04%, all percentages being weight percentages. When a blend is used, the polymeric materials in relation to 10 to 15 parts by weight of growth inhibitor are used per day. part nucleating agent.

5

The invention will then be further illustrated with reference to the following Examples wherein an additive of the invention (additive A) was an oil solution containing 63% by weight of a combination of polymers comprising 13 parts by weight of a wax crystal -10 growth inhibitor comprising an ethylene-vinyl acetate copolymer having an average molecular weight of number of 2500 and a vinyl acetate content of 36% by weight and 1 part by weight of a wax crystal stimulant having an average molecular weight of 3500 and a vinyl acetate content of approx. 13% by weight, with additive B being an oil solution containing 45% by weight of an additive combination of 3 parts by weight of the above-mentioned wax crystal growth inhibitor and 1 part of wax crystal stimulant according to US Patent No. 3,691,916, and additive C being a 50% by weight solution in oil of a ethylene acetate copolymer having an average molecular weight of 2000 and a vinyl acetate content of 30% by weight.

The fuels used in the Examples were as follows: 25 Initial 20% Boil 90% Boil End Boil

boiling point.8C point. C_punkt °. DC_punkt. ° C

Fuel 1 200 248 334 360

Fuel 2 228 280 351 374 30 Fuel 3 220 266 346 367

Fuel 4 224 268 341 359

Fuel 5 221 259 331 361

Fuel 6 244 264 336 360

Fuel 7 163 240 344 362 35 Fuel 8 160 234 344 358

Fuel 9 200 257 336 362

Fuel 10 213 264 338 360 In the examples, the wax crystal size was determined by rapid cooling

DK 164792B

11 by the "Cold Filter Plugging Point" test method (CFPP). This method is carried out as described in "Journal of the Institute of Petroleum", Volume 52, No. 510, June 1966, pages 173-185. Briefly, the CFPP test is performed with a 45 ml sample of the oil to be tested. The oil, 5 which is placed in an ASTM mist point jar, is cooled in a bath which is kept at approx. -34.4 * C. For every two degrees of temperature drop starting from 2.2 ° C above the fog point, the oil is forced under a 30 cm water column through a filter element fitted with a 350 mesh screen into a pipette to a mark indicating a volume of 20 10 ml. , at which time the oil is allowed to return to the cooling chamber under the influence of gravity. The sample is repeated for each temperature drop of 2 ° C in the oil until the oil is unable to fill the pipette at the above mark for a period of 60 seconds. The results of the experiment are stated as "Cold Filter Plugging 15 Points", which is the highest temperature at which the oil is unable to fill the pipette.

The amounts of Additive A, Additive B and Additive C required to achieve a reduction of 6 ° C, 8 ° C and 10 ° C, respectively, of the temperature at which these fuels could pass the CFPP test were determined as follows:

DK 164792 B

12 cn cn φ-ι- oo OQ) · γ- i— = i OOO - r ^ 3 O - ·> - · - * i 3 C_) * 1— '£ f — 1 i — II — I —i— £

Φ Oh

V) W τι— OOO ^ r- = I i i i i i 0) LO LO CM 17

O + ·> CO LO 00 * i— E

o + J CQ i — I

O & j I — I (Λ

D

<u σ> Z 0) -ι- Ο OOO i— OOOO o O LO CM O - ^ 3 (i — i O LO o = C i— cm lo o lo cn cr> Q) ·> - OOO Φ -r - j— OO LO OI— s ojkJscmi o cn o 3 • i— ε lo i — ir— (-i— ε Φ IΛ D) r— O Φ -r-

Φ LO O O i— = i i i i i

4-> O «0- LO 3

04-3 CQ i-i IOCO-r-S

o Path CO (Λ Ό Φ z o ooo o o o o o o lo σι o o o- co cm o r- »r · ^

<C LO r — c LO CO CO (O LO LO CO LO

σ> • r- OOO CD -I— Ό> OO OOO-iii— = Ό ·! - OO * 3 "i 000 ^ 3 et + j« * rc -i- ε 'cn * r— φ -r— UT )> OOO -Si i— = III ii oOi- CO LO OO -M3 LO <-P h- «^ -l ^ -1-ε i • i— ~ a> o ooo o oooo o

D -r- <~ H CO CM o CO LO Γ "- O LO CO

<+) «S- i — c et" r>. F ~. CM LO LO CM LO

-o c

Path I— 5- Φ o CQ 00 in CM CO -3- LO vor-θθσι r — 1 13

DK 164792 B

In a further series of experiments, the amount of additive required to give a reduction of 6, 8 and 10 ° C in the CFPP value for various fuels was determined and a comparison was made with the amounts required by the use of additives which are not according to 5 the invention.

The fuels used were as follows:

Fuel Initial 20% boiling 90% boiling Final boiling point 20 boiling point, ° C point, ° C point, ° C point, ° C

II 107 244 351 381 12 113 242 355 375 13 200 248 334 360 15 14 220 263 350 373 15 220 266 346 367 16 221 259 331 361 17 222 260 328 354 18 228 280 351 374 20 and the additives used were the additives A, B and C, used in the previous example, together with the additives DH which had the following properties: 25

Additive Weight percent vi nvi acetate Molecular weight D 34.8 2650 E 27.1 3170 F 28.9 2590 G 28.2 2940 30 H 29.9 2300

The results obtained are given in the table below.

35

DK 164792 B

14 X ΟιΛιΛΟΟΟΟΟΟΟΟΟΟΟ 0 | Q OOOOOOO OO 03 Ί1 I coo {T-Mnin (NioNi / iooinoooinooooininiii cm cn r * »-« - {NfMmoonO '^ r ^ rvor ^ ooO'-fNvooor-r ^ f-' r ^ cooo ' - <- '- T— t— τ— (Ί (\ | Λ Λ Λ Λ Λ Λ om U omomoooooooooooooooooooo νοοοοο Φ ^ fp.N'ir.oooo ^ ecooininoinooooininin σ \ * - co ή »-r-cMcncMdin ^ Tt ^ iDior '··' —f'iTS'inoor-r ^ r · 'inr-r ^

Ο) - OJCNAAA / S A A

Ό A

0) +> a 0 Gu lommootnoooooooooooooooooo τ-cooo

NnconoMnooMCNOiflinoooinininooinm ^> co »r r-cNCJvocoon ^ rminr ^ co | id γ ^ οοποοοιγ'Γ ^ γ ^ m id co

π T- «- * - <N A A A A

e · «.

> M OOOOOOOOOOOOOOOOOOOOOOOO JZ JZ JZ

T \ ocMooooooooooooomooooominin cn cn cn CNinininmooocoaocointnincoooooor-r ^ r- --4 - ^ - h

ZJ ΛΛΛΛ (ΝΜ0ΙΛΛΛ-Γ · - (Ν0Ι0Ι01ίΝΛΛΛ XXX)

A A / \ AAAAAAAA

nS

1¾ Q oinommoooooooooooooooooom cnvor- w, inhounoiMnooiomcoooujoair'coiiiNflMor tn r- o r> NiflOonnnifMOoirHooinnnr-r-r · n ^ rvo 33 <“e ο»

-H

cj ιηοοίΛοοοοοοοοοοοο ooooooo flno cn c; ΓητΓ-, σνοιηιηοοοοοΓ'Ο * —iDinomooor ^ om r ~ m co 0 r-tsfninoonTr-srior ^ over '' - mooinminio t * id r ~

Z

GQ OOOOOOOOOOOOOOOOOOOOOOOO —- ID o cri ^ 'vmcNootnoo ^ aj'T'DiDvDinincDinoiDor ^^ r id ^ in r — r — cNmmr ^ oo <r> nm "c3''3, inr ^ inn ~ cDcocT \' - · µ · an id

C ΐηΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟΟ r- 03 IT

• ^ r'OOioæoinnaDinr ^ r'inr ^ æomooorj'iooo 04 cm r- ^ t-r-r-iruDMNnnn'T ^ mcDcoiOMO '-'- r- m - <r - <j <1 ^

• o CD 0) 1fl G H

i a) a

Di + J ο ιοσοοιοαοοιοαοοιοοοοιοαοοοοοοιοοοοοοοοο CU 4-1 · ~ · - '-' - '- * -— - * -

Pu 8 aw +1

G

• w * H £

Ό G S

C - cm | m * r in o | r- | co | ^

Jh fl) I I I I I s

GQ W I- I I I I I U

Claims (7)

Use as an additive to improve the flow characteristics of a petroleum-derived distillate fuel oil whose 5 20% and 90% distillation points differ by a value between 70 ° C and 100 ° C and if 90% s boiling point differs from the final boiling point by from 10 ° C to 30 ° C, and if the final boiling point is above 350 ° C, of a product comprising 2Q i) a copolymer of ethyl one and a new ethyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, wherein the copolymer average contains from 32 to 35% by weight of the vinyl ester and has an average molecular weight by number of from 1000 to 6000; or ii) a mixture of two copolymers of ethyl one and one vinyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, one of which is of the copolymers acts as a growth inhibitor for the wax crystals, and the other acts as a nucleating agent 2Q for the wax crystals, which mixture contains at least 10 parts by weight of the growth inhibitor for each weight portion of the nucleating agent and averages from 32 to 35% by weight of the vinyl ester and has an average molecular weight by number of from 1000 to 6000. 25 Use according to claim 1, wherein the distilled fuel sol in one has a final boiling point of between 350 and 375 ° C. Use according to any one of the preceding claims, wherein the novel ester is vinyl acetate. 4. Distillate fuel whose 20% and 90% distillation points differ by 70 ° C to 100 ° C, if 90% boiling point deviates from the final boiling point by 10eC to 30eC, and the final boiling point exceeds 350 ° C, characterized by: it contains from 50 to 0 w 500 ppm (millionths) of 1 a copolymer of ethyl one and a new ethyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, the copolymer DK 164792 B containing, on average, from 32 to 35% by weight of the vinyl ester and has an average molecular weight by number of from 1000 to 6000, or 5 ii) a mixture of two copolymers of ethyl one and one vi of ester of a carboxylic acid containing from 1 to 4 carbon atoms, one of the copolymers acting as a growth inhibitor for the wax crystals and the other acts as a nucleating agent for the wax crystals, containing at least 10 10 parts by weight of the growth inhibitor for each part by weight of the nucleating agent and an average of from 32 to 35% by weight of the novel ester and with an average molecular weight by number of from 1000 to 6000. Distillate fuel according to claim 4, characterized in that the final boiling point is between 350 and 375 ° C. Distillate fuel according to claim 4 or 5, characterized in that we are the new ester vinyl acetate. 20 An additive concentrate for use in distillate fuels, characterized in that it comprises a solution in a hydrocarbon solvent of from 5 to 60% by weight of 25 i) an ethylene copolymer and a vinyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, wherein the copolymer contains, on average, from 32 to 35% by weight of the vi ester, and has an average molecular weight by number of 1000 to 6000, or ii) a mixture of two copolymers of ethyl one and one vinyl ester of a carboxylic acid containing from 1 to 4 carbon atoms, wherein one of the copolymers acts as a growth inhibitor for the wax crystals and the other acts as a nucleating agent 35 for the wax crystals containing at least 10 parts by weight of the growth inhibitor for each part by weight of the nucleating agent and an average of from 32 to 35% by weight of the vinyl ester and with a average molecular weight by number of from 1000 to 6000.