DD149225B1 - METHOD FOR PRODUCING A FLOW IMPROVER - Google Patents

Description

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JVus_ DE-OS 2413434 the production of ethylene-vinyl acetate-vinyl alcohol terpolyraeren by saponification of copolymers of ethylene and vinyl acetate with 25 to 40 wt .-% vinyl acetate and molecular weights of 500 to 30 000 is known. A disadvantage of the disclosed methods of copolymerization and terpolymerization is that they work by the solution polymerization method. Up to 45% by weight of vinyl acetate, however, have prevailed internationally in the high-pressure mass polymerization processes.

Finally, it is also known (DE-OS 2102469) to produce low molecular weight ethylene copolymers by the high pressure process at pressures above 100 MPa and temperatures of 423 K to 623 K in the presence of free-radical initiators and / or oxygen. The polymerization of ethylene and vinyl esters containing 4 to 10 carbon atoms and acrylic and methacrylic acid esters derived from alcohols having 1 to 12 carbon atoms takes place in the presence of 0.2 to 5% by volume of a polymerization regulator, whose transfer constant is C> 10, in the absence

of solvents.

A disadvantage of this process is that the additives can lead to by-products to a small extent.

Object of the invention

The aim of the invention is to develop a flow improver for middle distillates in the boiling range of 373 to 573 X with improved properties.

Explanation of the essence of the invention

The invention has for its object to develop a method that allows the preparation of a flow improver with improved properties. This object is achieved by a process for the preparation of a flow improver for fuels, in particular middle distillates, by terpolymerization of ethylene in the high-pressure tubular reactor, which is subdivided into one or more reaction zones, in the presence of a polymerization regulator, preferably hydrogen, at pressures above 50 ° C. preferably between 150 MPa and 300 MPa, and temperatures between 323 K and 673 K in the presence of radical-forming initiators, where according to the invention a mixture of 92 to 62% by volume of ethylene, 1C to 50 % by mass of vinyl acetate, preferably 20 % to J-0 Ma. -% vinyl acetate, and 3.001 to 10% by volume of carbon monoxide is terpolymerized.

Also suitable as chain transfer agents are paraffins, alcohols, aldehydes and ketones. As initiators, oxygen and / or organic peroxides and oxygen and peroxide mixtures can be used.

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The process can be carried out both in a stirred autoclave and in a tubular reactor.

The terpolymer prepared according to the invention can be used alone or in combination with other additives, such as other flow improvers, antioxidants, corrosion inhibitors, dewaxing agents as an additive for middle distillates.

embodiment

A mixture of 70.3 vol. Ethylene, 14% by volume of hydrogen, 12% by weight of vinyl acetate, 0.2% by volume of ethane and 3.5% by volume of carbon monoxide are mixed with a mixture of 40 kg of bis-3,5,5-trimethylhexanoyl peroxide and 10 kg of tert-butyl perbenzoate in 430 kg of paraffin oil as an initiator at a pressure of 160 MPa in a 300 m long tubular reactor of 30 mm diameter heated to the starting temperature of 413 K. The reactor is provided with a cooling jacket through which 55 mVh of water with a temperature of 428 K are constantly circulated. The metered amount of initiator mixture is such that a maximum reaction temperature of 538 K is maintained. After cooling to 433 K, the reaction mixture is released into a high-pressure separator under 27 MPa, and the terpolymer formed is separated from the gas mixture. The gas mixture is fed back to the reactor after passing through Xühl- and purification stages together with the fresh ethylene after the partially consumed reaction components and the initiator mixture were replenished. The polymer formed is discharged via a low-pressure separator. The conversion to the terpolymer is 16%.

Embodiment for the application

For the additization, a diesel fuel boiling range 453 K to 633 K with a CFPP point of 260 K was used. To compare the effectiveness, an ethylene-vinyl acetate copolymer was prepared and tested against the same diesel fuel

 Additive CFPP (K) / ~ Ccld Filter Plugging

Point_7 at Ma.- terpolymer

or copolymer

0.015 0.030

Terpolymer from: 32 Ma. -% vinyl acetate

0.1 Ma. -% carbon monoxide, 252 250

67.9 Ma.-7. ethylene; M _n = 2 050

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additive

CFPP (K) / Cold Filter Plugging Point_7 at wt% Terpolymer or Copolymer 0.015

0,030

Terpolymer of: 31% by weight of vinyl acetate, 1% by weight of carbon monoxide and 68% by weight of ethylene; M _n = 2000

250

243

Terpolymer of: 30% by weight of vinyl acetate, 3.5% by weight of carbon monoxide and 66.5% by weight of ethylene; I _n = 1 980 249

247

Terpolyner from: 32 Ma. % Vinyl acetate, 6.0% by weight carbon monoxide and 62 Ma. -% ethylene; M _n = 2 100

250

249

Comparative copolymer of: 32 Ma. -% vinyl acetate, 68 Ma. -% ethylene; M _n = 2000

254

253

The terpolymers according to the invention are clearly superior in their activity to the comparison copolymer. It is surprising that even the low content of carbon monoxide gives an erneoliche Veroesserung.

Claims (1)

- 1 - 219 126 Invention claim: Flow improvers for fuels, in particular middle distillates, prepared by terpolyraerization of ethylene in the high-pressure tubular reactor, which is subdivided into one or more reaction zones, in the presence of a polymerization regulator, at pressures above 50 TiPa, preferably between 150 MPa and 300 MPa, and temperatures between 323 K. and 673 K in the presence of radical-forming initiators, characterized in that it contains a terpolymer of 92 to 62% by volume of ethylene, 10 to 50 Ma. Represents -% vinyl acetate and 0.001 to 10 vol .-% carbon monoxide. Field of application of the invention The invention relates to a process for the preparation of a flow improver for middle distillates at pressures above 50 MPa, preferably between 150 MPa and 300 MPa, and temperatures between 323 K and 673 K in the presence of a polymerization regulator and radical-forming initiators. Characteristic of the known technical solutions It is known to use low molecular weight ethylene-vinyl acetate copolymers as flow improvers and pour point depressants for middle distillates (US Pat. No. 3,159,608). From DE-AS 11 ^ 7799 and the US-PS 3093623, US-PS 3126364, US-PS 3131168, US-PS 3159608 / US-PS 3254063. "JS-PS 3627838 are processes for the preparation of ethylene-vinyl acetate copolymers with 4,000 to 3,000 at temperatures of about 411 to 444 K and pressures of 4.8 MPa to 13.6 MPa in benzene polymerization medium A disadvantage of the said processes is that they have relatively high temperatures (> 373 X). To obtain low molecular weights and require special equipment, ie they are not feasible in the conventional equipment for the production of high molecular weight ethylene-vinyl acetate copolymers.Also known (DE-OS 2437490), low molecular weight ethylene-vinyl acetate copolymers having molecular weights of 500 to 10 000 in tert-butanol at pressures of 1 to 70 JiPa and temperatures "from 303 K to 423 K in the presence of 0.2 to 5 wt .-" o acetaldehyde as Xettenregler by radical polymerization to produce. Feiner is known (US-PS 3981850), ethylene-vinyl acetate Jopolymere and ethylene-vinyl acetate copolymers with a third monomer (vinyl laurate, ethyl acrylate, C ^ pC. / R alpha-olefins, di (C ₁ Q-oxo) fumarate ) having less than six methyl groups per 100 methylene groups and molecular weights of from 1 000 to 2 900 by solution polymerization at temperatures of from 343 K to 403 K and pressures of from 3.51 to 21.1 TiPa.