WO2014191103A2

WO2014191103A2 - Method for continuously performing a polymerization of monomers or comonomers

Info

Publication number: WO2014191103A2
Application number: PCT/EP2014/001444
Authority: WO
Inventors: Roland Kunkel; Pierre-Alain Fleury; Albina BLYUMIN
Original assignee: List Holding Ag
Priority date: 2013-05-29
Filing date: 2014-05-28
Publication date: 2014-12-04
Also published as: WO2014191103A3; DE102013105566A1

Abstract

The invention relates to a method for continuously performing a polymerization of monomers or comonomers, in particular a homopolymerization or copolymerization of dienes, such as butadienes, isoprenes, and piperylenes, into polymers in a reactor (1, 1.1, 1.2), in particular in a kneader mixer, having at least one inlet (2) for the product to be polymerized (feed), which inlet is adjoined by a feed zone (3) in the reactor (1, 1.1, 1.2). According to the invention the prepolymerized product is mixed back into the feed flow in the feed zone (3). The feed zone (3) in which the back-mixing occurs constitutes up to 50% (>0 - 0.5 of the product chamber) of the processing length.

Description

Process for carrying out a polymerization continuously

Monomers or co-monomers

The invention relates to a process for continuously carrying out a polymerization of monomers or co-monomers, in particular a homo- and copolymerization of dienes, such as butadienes, isoprenes, piperylenes, to polymers in a reactor, in particular in a mixing kneader, with at least one inlet for the product to be polymerized (feed), followed by a feed zone in the reactor.

State of the art

Devices for carrying out such methods are referred to as reactors and in particular as mixing kneaders. They serve very diverse purposes in these processes. First of all mention should be made of evaporation with solvent recovery, which is carried out batchwise or

CONFIRMATION COPY continuously and often under vacuum. As a result, for example, distillation residues and in particular toluene diisocyanates are treated, but also production residues with toxic or high-boiling solvents from chemistry and pharmaceutical production, washing solutions and paint sludge, polymer solutions, elastomer solutions from the solvent, adhesives and sealants.

With the apparatuses is also a continuous or batchwise contact drying, water and / or solvent-moist products, often also under vacuum, performed. The application is intended primarily for pigments, dyes, fine chemicals, additives such as salts, oxides, hydroxides, antioxidants, temperature-sensitive pharmaceutical and vitamin products, active ingredients, polymers, synthetic rubbers, polymer suspensions, latex, hydrogels, waxes, pesticides and residues from the chemical or pharmaceutical production, such as salts, catalysts, slags, waste liquors. These processes are also used in food production, for example in the production and / or treatment of block milk, sugar substitutes, starch derivatives, alginates, for the treatment of industrial sludges, oil sludges, biosludge, paper sludge, paint sludge and generally for the treatment of sticky, crusty viscose products, waste products and cellulose derivatives.

In a Mischkneter a polycondensation reaction, usually continuously and usually in the melt, take place and is mainly used in the treatment of polyamides, polyesters, polyacetates, polyimides, thermoplastics, elastomers, silicones, urea resins, phenolic resins, detergents and fertilizers. For example, it has application to polymer melts after bulk polymerization to derivatives of methacrylic acid. It is also possible to carry out a polymerization reaction, likewise usually continuously. This is applied to polyacrylates, hydrogels, polyols, thermoplastic polymers, elastomers, syndiotactic polystyrene and polyacrylamides.

In mixing kneaders, degassing and / or devolatilization may take place. This is applied to polymer melts, after (co) polymerization of monomer (s), after condensation of polyester or polyamide melts, on spinning solutions for synthetic fibers and on polymer or elastomer granules or powder in the solid state.

In general, solid, liquid or multiphase reactions can take place in the mixing kneader. This is especially true for baking reactions, in the treatment of hydrofluoric acid, stearates, cyanides, polyphosphates, cyanuric acids, cellulose derivatives, esters, ethers, polyacetal resins, sulfanilic acids, copper phthalocyanines, starch derivatives,

Ammonium polyphosphates, sulfonates, pesticides and fertilizers.

Furthermore, reactions may take place solid / gaseous (e.g., carboxylation) or liquid / gaseous. This is used in the treatment of acetates, acids, Kolbe-Schmitt reactions, e.g. BON, Na salicylates, parahydroxibenzoates and pharmaceuticals.

Reactions liquid / liquid occur in neutralization reactions and transesterification reactions.

Dissolving and / or degassing in such mixing kneaders takes place in spinning solutions for synthetic fibers, polyamides, polyesters and celluloses.

A so-called Flushing takes place in the treatment or production of pigments. A solid state postcondensation takes place in the production or treatment of polyesters, polycarbonates and polyamides, a continuous mashing, for example in the treatment of fibers, for example cellulose fibers with 5 solvents, a crystallization from the melt or from solutions in the treatment of salts , Fine chemicals, polyols, alcoholates, compounding, mixing (continuous and / or batchwise) with polymer blends, silicone compositions, sealants, fly ash, coagulating (especially continuously) in the treatment of polymer suspensions.

In a mixing kneader also multifunctional processes can be combined, for example heating, drying, melting, crystallizing, mixing, degassing, reacting - all this continuously or in batches. Ί 5 Polymers, elastomers, inorganic products, residues, pharmaceutical products, food products, printing inks are thus manufactured or treated.

In mixed kneaders, vacuum sublimation / desublimation can also take place, whereby chemical precursors, e.g. Anthrachinon, metal chlorides, ferrocenes, iodine, organometallic compounds, etc. are purified. Furthermore, pharmaceutical intermediates can be prepared.

Continuous carrier gas desublimation finds e.g. for organic intermediates, e.g. Anthraquinone and fine chemicals instead.

Essentially, a single-shaft and two-shaft mixing kneader are distinguished. A single-shaft mixing kneader is known, for example, from AT 334 328, CH 658 798 A5 or CH 686 406 A5. In this case, an axially extending, occupied with disc elements and rotating about a rotational axis in a rotational direction shaft is arranged in a housing. This causes the transport of the product in the transport direction. Between Disc elements are counter-elements fixedly mounted on the housing. The disc elements are arranged in planes perpendicular to the kneader shaft and form between them free sectors, which form with the planes of adjacent disc elements Knüräume.

A multi-shaft mixing and kneading machine is described in CH-A 506 322. There are on a shaft radial disc elements and arranged between the discs axially aligned kneading. Between these discs engage from the other wave frame-like shaped mixing and kneading elements. These mixing and kneading elements clean the disks and kneading bars of the first shaft. The kneading bars on both shafts in turn clean the inside of the housing.

Another multiwell mixing kneader of the abovementioned type is known, for example, from EP 0 517 068 B1. With him turn in a mixer housing two axially parallel shafts either in opposite directions or in the same direction. In this case, mixing bars applied to disk elements interact with each other. In addition to the function of mixing, the mixing bars have the task of cleaning product-contacted areas of the mixer housing, the shafts and the disk elements as well as possible and thus avoid unmixed zones. Particularly in the case of strongly compacting, hardening and crusting products, the randomness of the mixing bars leads to high local mechanical loads on the mixing bars and the shafts. These force peaks occur in particular when engaging the mixing bars in those zones where the product can escape badly. Such zones are e.g. Given where the disc elements are placed on the shaft.

Furthermore, from DE 199 40 521 A1 a mixing kneader of the above-mentioned type is known in which the support elements form a recess in the region of the kneading bars so that the kneading bar has as large an axial extent as possible. Such a mixing kneader has an excellent self-cleaning However, all product-contacting surfaces of the housing and the waves, but has the property that the support elements of the kneading bars due to the paths of the kneading bars make recesses necessary, which lead to complicated Tragelementformen.

task

The object of the present invention is to improve a polymerization reaction, in particular of dienes.

Solution of the task

In order to achieve the object, back-mixing of the polymerized product with the feed stream takes place in the feed zone.

This back-mixing in the feed zone has the considerable advantage that the product, which is relatively liquid, is mixed with an already polymerized product which is slightly higher viscosity. As a result, the viscosity is increased at an early stage in the feed zone, so that heat is introduced into the product or the feed stream early on as a result of the shearing action by the corresponding kneading elements, so that the exotherm is also started quickly. This means that early degassing of solvent and / or unpolymerized monomers or co-monomers takes place.

Preferably, however, the viscosity of the product is kept as constant as possible in the feed zone. Constant maintenance is always at a level prior to the point of evaporation so that the product has enough time to react and degas. It is known that as a result of the heat input, the viscosity is increased until a point is reached at which the viscosity is so high that no solvent and / or monomer can get more from the interior of the product to the surface, so that no more degassing occurs. This is called the breaking point of the evaporation.

If a solvent is used, it can act according to the invention as a chain regulator. This means that by choosing the solvent, the chain lengths formed in the polymerization can be shortened.

For certain polymers, it is also thought to use water as a solvent. Incidentally, different solvents may be used, depending on the requirements imposed on the solvent. There are solvents which dissolve the product, so that above all the mixture becomes very homogeneous. There are other solvents that do not dissolve the product (non-solvent), which are usually used to cool the product. The cooling takes place with respect to the exotherm of the product and / or the heat developed by the kneading energy and / or with respect to the heat transferred through contact surfaces into the product.

In a preferred embodiment of the process according to the invention, the solvent is added to the monomer as soon as it is added, which nevertheless should be covered by the present invention, but only when the viscosity has already risen. This happens after about 1 / 3-3 / 4 of the length of the product space of the machine.

In the context of the invention, it is provided that the feed zone extends to about 50% of the process length, ie the length of the reactor. Incidentally, in the present case, a reactor having a length / diameter ratio of 1 to 6 is preferably used, which is preferably a single or twin-screw kneader. In a twin-screw mixer, the shafts can rotate in opposite directions or in the same direction, with the same or different speeds. The feed zone is then followed by a transport zone in which the product is discharged. This is preferably done in the plugflow, ie, without backmixing. The plugflow is done over a process length of 0.2 to 1, preferably from 0.4 to 1.

The discharge element for the reacted product from the reactor can be configured as desired, preferably a discharge screw.

Furthermore, it is intended to enter the product not only at an inlet into the reactor, but at several inlets within the feed zone. Furthermore, initiators may be added to the product prior to entry into the reactor or even after entry within the feed zone. These may preferably be metallocene catalysts or Ziegler-Natta catalysts.

A particular focus of the present invention is directed to the evaporation of the monomer. The product is preferably cooled by the evaporation of monomer in the reactor. This vaporized monomer then passes into a condenser, wherein in one embodiment, it is contemplated that the condenser sits directly on the reactor and the vaporized monomer is condensed in this condenser and fed directly to the feed stream again in the reflux process. In direct condensation, d. h., at the reflux, the condensate is still in the feed zone, d. H. recycled in the range of 0 to 50% of the process length from the feed and so ideally remixed together with the polymerized product.

In a second possibility, the vaporized monomer is condensed in a corresponding external heat exchanger and, if appropriate, after being treated, fed back to the reactor in the feed zone. In the external condensation, in turn, the condensation can be carried out directly or else by means of a spray condensation with a monomer, wherein it is optionally thought that this monomer contains inhibitors, whereby the further reaction of the condensed monomer is suppressed. One possibility is also to add oxygen to the condensed monomer to inhibit it.

The entire process may take place in a single reactor, but it is also intended to separate the polymerization from the degassing.

Furthermore, protection is automatically sought for a method for treating products in a product space, wherein the product is transported in the product space from an inlet to an outlet. In this case, a discharge device is connected to the outlet, in which discharge elements promote the product, but at the same time barriers are provided which counteract a promotion of the product and / or that the inlet is preceded by a corresponding inlet device .. Through the barriers, a pressure is built up in the product , This idea is mainly used for products that are held relatively low viscosity. With these products, there is a risk that they will flow through the discharge device in an uncontrolled manner. But if, for example, the discharge device, for example a discharge screw, a gear pump downstream, so this requires a product pressure of 2-5 bar, otherwise it runs irregularly. The barriers in the discharge device in this case have the purpose that the product can be pushed past them only when a certain pressure is generated, this pressure being maintained up to the gear pump. As a barrier can serve anything that increases the friction in the housing of the discharge. For example, these may be cams or bolts, which, starting from the housing wall into the worm threads of the discharge screw intervention. This is just an example. Even an increase in the roughness of the inner surface of the discharge screw can serve as a barrier.

If the inlet is preceded by a corresponding inlet device with barrier, the pressure for the product which is brought into the product space is also increased. In this case, the product is "flashed" into the product room.

With this corresponding embodiment of the entry or discharge device, a treatment of products of very different viscosities in a mixing kneader is possible throughout.

figure description

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing; this shows in the

1 shows a schematic representation of a reactor for carrying out a process according to the invention for carrying out a polymerization continuously;

Figure 2 is a schematic representation of the reactor of Figure 1, but with external condensate return;

Figure 3 is a schematic representation of the reactor of Figure 1 with a further embodiment of an external condensate return;

Figure 4 is a schematic representation of the reactor of Figure 1 with subsequent Austragssch tease; Figure 5 is a schematic representation of the two-stage process implementation.

In Figure 1, a mixing kneader 1 is shown schematically, which, as described in the prior art, can be configured. In particular, it has an inlet designated by an arrow 2 for a product (feed) which is to be polymerized in it.

According to FIG. 4, the mixing kneader 1 is subdivided into a feed zone 3 and a plugflow zone 4, in the feed zone 3 a backmixing of the product (feed) with already polymerized product, while in the plugflow zone the product is conveyed directly to a discharge 5 becomes. The Feed zone occupies about 0 to 0.5 of the process length, accordingly the plugflow zone 0.5 to 1.0.

During the treatment of the product in the mixing kneader 1, evaporation takes place, in particular of the monomer or comonomer. These vaporized components are withdrawn through a vapor nozzle 6, wherein the vaporized monomer is preferably condensed. For this purpose, a heat exchanger 7 is provided to the embodiment according to Figure 1 in the vapor pipe 6, on or in which the vaporized monomer is condensed directly. This monomer then preferably returns immediately back into the feed stream.

In a further embodiment according to FIG. 2, an external condensation is provided, for which purpose the heat exchanger 7.1 is arranged. From this heat exchanger 7.1 there is a return of the condensed monomer directly into the inlet 2 of the mixing kneader. 1

In a third embodiment of the invention according to FIG. 3, a spray condensation 8 is provided which likewise takes place with a monomer. This monomer may contain inhibitors that prevent further reaction of the condensed monomer. In order to prevent oxygen can also, as indicated by the arrow 9, the condensed and back to leading monomer are supplied. In a further embodiment of the invention according to FIG. 5, it is intended to carry out the polymerization in a mixing kneader 1.1, but then the devolatilization, ie the degassing of the product in a further mixing kneader 1.2. For this further mixing kneader 1.2 the withdrawal of the vaporized monomer via the vapor pipe 6 takes place to the heat exchanger 7. A pump 10 then takes the return back into the inlet 2 of the mixing kneader 1.1. Dres. WEISS & ARAT

Patent attorneys and lawyer

European Patent Attorney

Reference: P 4717 / PCT Date: 28.05.2014

LIST OF REFERENCE NUMBERS

1 mixing kneader 34 67

2 product (feed) 35 68

3 Feed zone 36 69

4 Plugflow zone 37 70

5 discharge 38 71

6 vents 39 72

7 heat exchanger 40 73

8 spray condensation 41 74

9 oxygen addition 42 75

10 pump 43 76

11 44 77

12 45 78

13 46 79

14 47

15 48

16 49

17 50

18 51

19 52

20 53

21 54

22 55

23 56

24 57

25 58

26 59

27 60

28 61

29 62

30 63

31 64

32 65

33 66

Claims

claims

1. A process for continuously carrying out a polymerization of monomers or co-monomers, in particular a homo- and copolymerization of dienes, such as butadienes, isoprenes, piperylenes, to polymers in a product space of a reactor (1, 1.1, 1.2), in particular in a mixing kneader , with at least one inlet (2) for the product to be polymerized (feed) to which a feed zone (3) adjoins the product space of the reactor (1, 1.1, 1.2), characterized in that in the feed zone (3) a backmixing of the polymerized product with the feed stream, wherein the feed zone (3), in which the back-mixing takes place, to 50% (> 0 - 0.5 of the product space) of the process length makes up.

2. The method according to claim 1, characterized in that a viscosity of the product in the feed zone (3) is kept constant by controlling the feed flow rate and the backmixing.

3. The method according to claim 1 or 2, characterized in that solvent (including water) and / or further monomer is added to the product space when the viscosity of the product has risen, in particular in the range between 1/3 - 3/4 of the length of the product room.

4. The method according to at least one of the preceding claims, characterized in that the product after the feed zone (3) in the plug flow (4) is led to a discharge (5).

5. The method according to claim 4, characterized in that the guide in the plug flow (4) in the range of 0.2-1, 0 of the process length, preferably 0.4-1, 0 of the process length, seen from the feed, takes place.

6. The method according to at least one of the preceding claims, characterized in that the product via a Austragssch tease (5) from the reactor (1, 1.1, 1.2) is discharged.

7. The method according to at least one of the preceding claims, characterized in that the product at several points within the feed zone (3) in the reactor (1, 1.1, 1.2) is given.

8. The method according to at least one of the preceding claims, characterized in that as initiators metallocene catalysts or Ziegler-

Natta catalysts, such as TiC, VOCl ₃ and BF ₃ -O (C ₂ H ₅ ) 2, are added to the feed stream.

9. The method according to at least one of the preceding claims, characterized in that the product is preferably by evaporation of

Monomer in the reactor (1, 1.1, 1.2) is cooled.

10. The method according to claim 9, characterized in that the vaporized monomer is condensed.

11. The method according to claim 10, characterized in that the vaporized monomer is fed back into the feed stream directly in the reflux.

12. The method according to claim 10, characterized in that the vaporized monomer is externally condensed and fed to the feed stream again after a treatment.

13. The method according to claim 12, characterized in that the condensation takes place by means of a spray condensation (8) with a monomer.

14. The method according to claim 13, characterized in that the monomer contains inhibitors.

15. The method according to claim 13 or 14, characterized in that the condensed monomer is supplied with oxygen.

16. The method according to at least one of claims 9-15, characterized in that the polymerization in a first stage in a first reactor (1.1) and the evaporation or degassing in a second reactor (1.2), wherein the evaporated monomer in the Feed zone (3) of the first reactor (1.1) is returned.

17. A method for treating products in a product space, wherein the product is transported in the product space from an inlet to an outlet, characterized in that at the outlet of a discharge device connects, in which discharge organs promote the product, but at the same time barriers are provided which counteract a promotion of the product and / or that the inlet is preceded by a corresponding entry device.

18. The method according to claim 17, characterized in that a back pressure is built up by the barriers in the product.