DE102014112268A1 - Device for transporting compact polymer masses - Google Patents

Abstract

In a device for transporting compact polymer masses (P) by means of at least one pressure-building pump (3), a pipeline (4 to 4.3) should connect to the pump (3).

Description

The invention relates to a device for transporting compact polymer compositions by means of at least one pressure-building pump and a method for this purpose.

State of the art

There are a variety of devices in which a product is subjected to treatment. The present invention relates primarily to the industrial sector and here to the treatment of chemical products, in particular of plastics. Apart from vertical stirred vessels, horizontally arranged devices are also known, in particular, but not restrictively, extruders and mixing kneaders being mentioned. Both, however, are fundamentally different. Whereas a screw rotates in an extruder in a corresponding tubular housing jacket and thus conveys the product to be treated from an inlet to an outlet in the screw flights, a product space and a gas space are formed in a mixing kneader. The product space is, as the name says, filled with product, the gas space, which is usually located above the product space, fills with the treatment of the product with gas, which is then withdrawn by appropriate vapors. An actual treatment of the product, namely a mixing and kneading and transporting takes place only in the product space, the gas space is free of product.

In particular, mixing kneaders serve very diverse purposes. First of all mention should be made of evaporation with solvent recovery, which is carried out batchwise or 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, sulphanilic 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.

Solid state post-condensation occurs in the preparation or treatment of polyesters, polycarbonates and polyamides, continuous mulling, e.g. in the treatment of fibers, e.g. Cellulose fibers with solvents, a melt crystallization or from solutions in the treatment of salts, fine chemicals, polyols, alcoholates, compounding, mixing (continuous and / or batchwise) in polymer blends, silicone compositions, sealants, fly ash, coagulating (in particular continuous) 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. This produces and / or treats polymers, elastomers, inorganic products, residues, pharmaceutical products, food products, printing inks.

In mixed kneaders, vacuum sublimation / desublimation may also occur, thereby reducing 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 for example from AT 334 328 , of the CH 658 798 A5 or the CH 686 406 A5 known. 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 the disc elements counter elements are 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 in the CH-A 506 322 described. 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.

These known two-shaft mixing kneaders have the disadvantage that they have a weak point due to the eight-shaped housing cross section in the region of the connection of the two shaft housing. In this area, the processing of tough products and / or processes that take place under pressure, high voltages that can be controlled only by complex design measures.

A Mischkneter of the above type is for example from the EP 0 517 068 B1 known. 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 given, for example, where the disc elements are mounted on the shaft.

Furthermore, from the DE 199 40 521 A1 a mixing kneader of the above type is known, in which the support elements form a recess in the region of the kneading bars, so that the kneading bar has the largest possible axial extent. Such a mixing kneader has an excellent self-cleaning of all product-contacting surfaces of the housing and the waves, but has the property that the support elements of the kneading due to the paths of the kneading bars recesses required that too complicated Carry support element shapes. This results in a complex manufacturing process on the one hand and on the other hand local stress peaks on the shaft and the supporting elements in the event of mechanical stress. These stress peaks, which occur mainly in the sharp-edged recesses and thickness changes, especially in the area where the support elements are welded onto the shaft core, are triggers for cracks in the shaft and the support elements due to material fatigue.

In the present invention is the transport of compact polymer masses in particular between individual processing stages, for example, between a main evaporation and derailment, as shown in the WO2010 / 089137 are described. However, the invention should not be restricted to this, it generally deals with the transport of compact polymer compositions.

The direct evaporation of polymers from temperature-sensitive polymers is a multi-step process in which the polymer is degassed directly and thus high viscosities occur during the process or the viscosities continue to rise. A dilution or suspension would reverse the process and is therefore impractical.

Heating above the melting point to lower the viscosity is not possible with temperature-sensitive polymers, since the polymer is damaged in the process.

• a) Die Polymermasse fliesst bei diesen Viskositäten nicht mehr selbstständig.
• b) Zahnradpumpen werden nicht mehr gespiesen.
• c) Schneckenkonstruktionen können den notwendigen Transportdruck nicht aufbauen bzw. schädigen das Polymer.
• d) Weder Schneckenkonstruktionen noch Zahnradpumpen sind für sich allein in der Lage diese Polymermassen zu fördern.
• e) Aufgrund der hohen Viskositäten der Polymermassen treten sehr hohe Drücke auf.
• f) Hohe Scherungen führen zu Produktschädigungen.
• g) Der Abstand der Kneter zur ist konstruktionstechnisch bedingt grösser als 1 Meter.

Here are the following problems:

• a) The polymer mass does not flow independently at these viscosities.
• b) Gear pumps are no longer powered.
• c) Screw constructions can not build up the necessary transport pressure or damage the polymer.
• d) Neither screw designs nor gear pumps are in themselves capable of promoting these polymer compositions.
• e) Due to the high viscosities of the polymer compositions very high pressures occur.
• f) High shear causes product damage.
• g) The distance between the kneader and the construction is greater than 1 meter.

The conventional technique for transporting polymer compositions utilizes dilution, suspension, or melting of the polymer to yield the viscosity in a processable order of less than 1000 Pas of zero shear viscosity. However, this is undesirable in many cases, since subsequently the polymer composition has to be returned to the original viscosity or the original state which was achieved by the desired polymerization.

Object of the invention

The object of the invention is to find a possibility which makes it possible to transport a polymer composition with very high viscosity of 100,000 Pas to 10 million Pas zero shear viscosity uniformly, continuously and without product damage from one process stage to the next process stage.

Solution of the task

To solve the problem results in that connects to the pump a pipe. The pipeline must be designed so that it can withstand the resulting pressure of 250 bar (PN 320), especially during start-up processes and very low flow velocities.

To improve the flow properties of the polymer composition, the pipeline should be heated. In a simple embodiment, this is provided for that the wall of the pipe is double-walled. An inner coating with thermally introduced surface tension-changing materials has brought further significant advantages in the flow properties.

To solve the problem, various transport options for polymer compositions were investigated.

The method mentioned in the prior art for the direct evaporation of polymers ( WO2010 / 089137 ) consists of two main components, main exhaust and degassing. The discharge from the main evaporation takes place via a discharge screw design. This screw design can reach a pressure of 20 to 30 bar, in extreme cases briefly when starting the process up maximum 100 bar, build up. This pressure build-up is insufficient to transport the concentrated polymer mass over a distance of more than one meter. The experiments have shown that this pressure build-up but sufficient to feed a downstream gear pump.

The preferably directly flanged gear pump transports the polymer mass in the pipeline and builds up the necessary pressure for transport of 50 to 250 bar.

By adding additives, the flow properties can also be significantly improved. The additive was added at different points either in the previous process stage, directly in the screw design or between the screw design and gear pump.

The control of the combination of screw design, gear pump and piping follows a complex cascade control. Both conveyor and pressure building devices can not meet the task alone and hinder each other under normal circumstances. An intelligent controller compensates for both characteristics and drives the speeds in parallel. This parallelism must be corrected by changing the feed pressure or feed pressure upstream of the gear pump at different throughputs, which leads to the development of the complex cascade control. The pre-pressure in front of the gear pump serves only for fine adjustment of the relation of the speeds.

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

1 a block diagram of a device for the transport of compact polymer masses;

2 a block diagram-like representation of another embodiment of an apparatus for transporting compact polymer masses;

3 to 6 Block diagram-like representations of various configuration options of parts of the inventive device for transporting compact polymer masses in a vertical embodiment;

7 to 9 block diagram-like representations of various configuration options of parts of the inventive device for transporting compact polymer compositions in a horizontal embodiment.

In 1 becomes a polymer in a process stage in a main steam generator 1 treated, as for example in the WO2010 / 089137 is described. This polymer exits the main exhaust and enters a screw design 2 , wherein in between an additive A can be added.

Directly to the screw design 2 closes a gear pump 3 on, over a pipeline 4 with a degasser 5 connected is. Various configurations of the screw design, gear pump and piping are in the 3 to 6 indicated. According to 3 is the screw design 2 a drive 5 assigned. In the embodiment shown here is a twin screw, as used in the prior art for the discharge of polymer compositions from a mixing kneader. The polymer mass passes at P in this screw design. The screw design 2 itself is of a coat 6 at least partially encompassed, in which a tempering medium from an inlet 7 to an outlet 8th can be performed.

To the screw design 2 directly flanged is the gear pump 3 , She too gets a coat 9 surrounded, wherein a tempering medium within this shell 9 from an inlet 10 to an outlet 11 is guided.

To the gear pump 3 closes the pipeline 4 due to a further surrounding coat 12 is formed double-walled. Inside this coat 12 In turn, a temperature control from an inlet 13 to an outlet 14 guided.

The configuration according to 4 differs from the one after 3 by omitting the tempering medium. Accordingly, neither the screw design 2 still around the gear pump 3 still around the pipeline 4 appropriate coats provided. But there is an addition of an additive A, which significantly improves the flow properties of the polymer.

In the 5 and 6 is further indicated that the corresponding pipeline 4.1 respectively. 4.2 may also be curved or guided in arches.

The 7 to 9 show a horizontal arrangement of the screw design 2 , where the main steamer 1 this vertical screw design 2 seated. Again, the pipes can be either straight, curved or in curves. In 2 is hinted that even on a degasser 5 a corresponding screw design 2.1 with flanged gear pump 3.1 can follow. The latter is then via a pipeline 4.3 with a crushing 15 connected. 1 Hauptausdampfer 2 screw design 3 gear pump 4 pipeline 5 drive 6 coat 7 inlet 8th outlet 9 coat 10 inlet 11 outlet 12 coat 13 inlet 14 outlet 15 crushing A additive P polymer composition

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• AT 334328 [0017]
• CH 658798 A5 [0017]
• CH 686406 A5 [0017]
• CH 506322 A [0018]
• EP 0517068 B1 [0020]
• DE 19940521 A1 [0021]
• WO 2010/089137 [0022, 0031, 0040]

Claims (17)

Apparatus for transporting compact polymer masses (P) by means of at least one pressure-building pump ( 3 ), characterized in that to the pump ( 3 ) a pipeline ( 4 to 4.3 ). Device according to claim 1, characterized in that the pipeline ( 4 to 4.3 ) is heated. Device according to claim 2, characterized in that the pipeline ( 4 to 4.3 ) of 20-280 ° C is indirectly heated. Apparatus according to claim 2 or 3, characterized in that a wall of the pipeline ( 4 to 4.3 ) is double-walled. Device according to at least one of the preceding claims, characterized in that the pipeline ( 4 to 4.3 ) is designed as a high-pressure line of nominal pressure rating of at least PN 100 (EN 1333). Device according to at least one of the preceding claims, characterized in that in the pipeline ( 4 to 4.3 ) Constrictions or extensions are installed. Device according to at least one of the preceding claims, characterized in that in the pipeline ( 4.1 . 4.2 ) Bows are installed. Device according to at least one of the preceding claims, characterized in that in the pipeline ( 4 to 4.3 ) at least one compensator is installed. Device according to at least one of the preceding claims, characterized in that the pipeline ( 4 to 4.3 ) is coated inside for the transport of polymer masses. Device according to at least one of the preceding claims, characterized in that the pump is a gear pump ( 3 ). Device according to at least one of the preceding claims, characterized in that the pump has a screw construction ( 2 ) is connected upstream, which the pump ( 3 ) feeds with the polymer composition. Apparatus according to claim 11, characterized in that the screw construction ( 2 ) is designed one or more waves with axially identical or different elements. Device according to at least one of the preceding claims, characterized in that the screw construction ( 2 ) and / or the gear pump ( 3 ) is preferably indirectly heated / are, preferably at 20-280 ° C. Device according to at least one of claims 11 to 13, characterized in that a delivery volume of the screw construction ( 2 ) and the gear pump ( 3 ) are coordinated with each other so that the gear pump ( 3 ) is always filled accordingly and a pressure build-up of the screw construction ( 2 ) in the gear pump ( 3 ) is less than 50 bar. Device according to at least one of claims 11 to 14, characterized in that the combination of screw construction ( 2 ) and gear pump ( 3 ) is executed vertically, horizontally or at any angle between the preceding and the subsequent process stage. Method for transporting compact polymer masses (P) by means of at least one pressure-building pump ( 3 ), characterized in that the compact polymer mass (P) from one process stage to the next process stage in a pipeline ( 4 to 4.3 ) is transported at least one meter. Method for transporting compact polymer masses (P) by means of at least one pressure-building pump ( 3 ), characterized in that one or more additives (A) are added to the polymer composition (P), which change the flow properties of the polymer composition (P).

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