DE202015104764U1 - Ring extruder for continuous preparation of rubber compounds with co-extruder - Google Patents

Abstract

Multi-screw extruder, in particular RingExtruder (59) for the continuous preparation of rubber material with at least six axially parallel, co-rotating screw shafts (1) arranged in a circle in a Etxrudergehäuse (3), characterized in that the multi-screw extruder at least one co-extruder (71, 105) which is arranged on the multi-shaft extruder and supplies material for the continuous rubber preparation to the multi-shaft extruder, wherein the co-extruder (71, 105) is suitable for masticating.

Description

The invention relates to an extruder according to the preamble of claim 1 and to an extruder plant according to the preamble of claims 1 and 9.

In the production of rubber compounds, a continuous extrusion process has a considerable advantage over the established internal mixer processes in terms of investment and operating costs and space requirements. Furthermore, continuous processes offer a pronounced consistency and reproducibility of the product quality, which are much more difficult to achieve in intermittent batch processes. They are also much easier to automate with regard to material handling and process control and regulation. The possibility of adapting the screw and housing configurations to the procedural requirements of different formulations leads to a pronounced flexibility of the extrusion plants ( F. Röthemeyer, Rubber Technology: Materials, Processing, Products, Carl Hanser Verlag (2nd revised edition, 2006), 413 ). For these reasons, for some years, the development of continuous processes for the production of rubber mixtures with different types of extruders, in particular co-rotating twin and multi-screw extruders, worked.

Nevertheless, the rubber industry is still dominated by batchwise working internal mixers with downstream rolling mills, although these aggregates often have to be passed through two or more times. In contrast, the ring extruder is available as an established extrusion system for the production of rubber compounds in a continuous process. Thanks to very good dispersing performance and a very differentiated adjustable temperature control at a comparatively low rotational speed, the rubber preparation processes can also be realized with larger machines such as RingExtruder5, RingExtruder7 and RingExtruder9, as sold by the Applicant. Due to the exceptionally high surface / volume ratios, a scale-up proceeding from the RingExtruder3 can easily be achieved even with the larger machine types RingExtruder7 and RingExtruder9.

Starting from the co-rotating, close-meshing twin-screw extruders, an increase in throughput in the RingExtruder concept is initially achieved by multiplying the number of screws to twelve. Therefore, with identical screw diameters, significantly higher throughputs are achieved in the ring extruder than with twin screws which can only be used to a limited extent for rubber preparation. At the same time, however, the mixing and dispersing effect is significantly improved (see below) and the specific energy input is minimized. A further increase in throughputs is also achieved by increasing the screw diameter in RingExtruder, on the other hand, but alternatively, the number of waves z. B. further increased to 18 or 24.

For the first time, the RingExtruder offers the possibility of applying a continuous process to the throughput requirements of the rubber industry. For some time, various ring extruders with a screw diameter of 70 mm ( 1 ) operated successfully in this industry in mass production and replaced both internal mixers and downstream rolling mills. Depending on the recipe, the throughputs are around 1200 to 3000 kg / h.

Nevertheless, this technical orientation involves problems with regard to the process heat, loading of the extruder material, processing of the material to be extruded, which make it desirable to further improve the process flow through the extruder, both quantitatively and qualitatively. but in particular rubber or rubber precursors are affected by RingExtrudern.

This object is achieved with the devices of the dependent claims 1 and 9.

• – Fußbodenbeläge, Gummiplatten und -Bahnen
• – Gummiprofile, Faltenbälge, Dichtungen, Schläuche
• – Reifen
• – Selbstversiegelnde Reifendichtmassen
• – Dehnungsfugenbänder und Bauelemente im Brücken- und Hochbau
• – Gummidämpfer
• – Kabelummantelungen
• – Kautschukbasierte Klebstoffe
• – Base-gum und Kaugummi
• – Thermoplastische Elastomere (TPE)
• – Thermoplastische Vulkanisate (TPV)
• – Thermomechanische und/oder chemische Devulkanisation
• – Entgasen und Strippen synthetischer Rohkautschuk-Massen
• – Mechanisches Abquetschen von Lösemitteln oder Wasser aus synthetischen Rohkautschuk-Massen

Application examples for the extruder according to the invention and an extruder system according to the invention are:

• - floor coverings, rubber sheets and sheets
• - Rubber profiles, bellows, gaskets, hoses
• - Tires
• - Self-sealing tire sealants
• - Expansion joints and construction elements in bridge and building construction
• - rubber damper
• - Cable sheathing
• - Rubber-based adhesives
• - Base gum and chewing gum
• - Thermoplastic elastomers (TPE)
• - Thermoplastic vulcanizates (TPV)
• - Thermomechanical and / or chemical devulcanization
• - Degassing and stripping synthetic raw rubber masses
• - Mechanical squeezing of solvents or water from synthetic raw rubber compounds

The terms rubber, rubber, rubber material, rubber material and rubber compounds are used as synonyms in the present application.

The term rubber material is understood to mean a material, in particular from the group of elastomers with viscoelastic properties. The rubber material may be based on rubber and / or other rubber-like vegetable juices which, upon drying, preferably harden to plastic-elastic solids through polymerization.

Natural rubber as well as synthetically produced rubber may also be used to practice the present invention.

The rubber material comprises a vulcanized rubber and is known in particular as an elastic and relatively hard-wearing solid.

In the production of the rubber material, the natural and / or the synthetic rubber further solid and / or liquid ingredients are supplied and mixed with this / n. In the present case, mixing is also understood to mean mixing.

Synthetic rubbers are z. Styrene rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, ethylene-propylene-diene rubber, chloroprene rubber and polyisoprene rubber. The list is only exemplary and in no way exclusively meant.

Such rubber mixtures or rubber mixtures all have a complex formulation with in the simplest case seven to eight components, for special requirements up to 20 components, each tailored to the application.

In the context of the present invention, ingredients are by way of example and by no means exclusively rubber, solvents, plasticizers, cure accelerator vulcanization accelerators, cure retarders, activators, silica, carbon blacks, pigments, fillers, resins, adhesives, flame retardant additives, ozone and anti-aging agents.

However, they are all characterized in that they are recipe-related, that is to say inherent, components for the production of a rubber material and are distinguished from external additives, such as the separate release agents or coating, wetting or dusting agents known in the prior art.

A release agent in the sense of this foreign admixture according to the prior art has the purpose of separating the particles. In contrast to this, for example, a plasticizer is not regarded as a foreign admixture in the sense of the prior art, but as an ingredient, because it influences the Shore hardness and thus is a necessary formulation constituent of the material.

The selection of ingredients depends u. a. from the application of the material and thus also from the product requirements as well as from the costs. These parameters have a not inconsiderable influence on the choice of the rubber and the reinforcement system.

For tire mixes z. As "silica" an important recipe ingredient. Car tires, for example, benefit from the reinforcement of a special SiO ₂ system, because they can save fuel compared with traditional rubber compounds that are traditionally filled with soot and at the same time improve the safety performance.

• – Calziumcarbonat für Fußbodenbelage, Dichtungsplatten,
• – Aluminiumsilikat für Schläuche, Schuhsohlen, Profile, Dichtungen, technische Produkte, Fußbodenbeläge
• – Kieselerde für Schläuche, Dichtungen, technische Produkte
• – Calciumsilikat für Schuhsohlen, Dichtungsplatten,
• – Magnesiumsilikat für technische Produkte,
• – Zinkcarbonat für helle Produkte,
• – Kaolin calziniert für Kabel, technische Produkte,
• – silanisierte Kaoline für technische Produkte
• – silanisierte Silikate für Reifen,
• – Magnesiumsilikat zur Beeinflussung der Gasdurchlässigkeit und Chemikalienbeständigkeit,
• – Aluminiumhydroxid zur Beeinflussung des Flammschutzes,
• – Magnesiumcarbonat zur Beeinflussung der Grünfestigkeit,
• – Bariumsulfat zum Einsatz bei Lärmdämmung, Strahlenschutz, zur Beeinflussung der Säurebeständigkeit,
• – Calziumoxid zur Verwendung als Wasser- und Säureakzeptor,
• – Titandioxid zur Verwendung als UV-Stabilisator,
• – Aluminiumoxid zur Verwendung als inerter Füllstoff,
• – Zinkoxid zur Verwendung als Vernetzungsmittel und zur Beeinflussung der Hitzebeständigkeit,
• – Magnesiumoxid zur Verwendung als Aktivator und zur Beeinflussung der Hitzebeständigkeit.

By way of example and not exhaustively, the following fillers are characterized as ingredients. The list below is also exemplary and non-exhaustive with respect to the ingredients as related to the use:

• - Calcium carbonate for flooring, gaskets,
• - Aluminum silicate for hoses, shoe soles, profiles, seals, technical products, floor coverings
• - Silica for hoses, gaskets, technical products
• - Calcium silicate for shoe soles, gaskets,
• - magnesium silicate for technical products,
• - zinc carbonate for light products,
• - kaolin calcined for cables, technical products,
• - silanized kaolins for technical products
• Silanized silicates for tires,
• - magnesium silicate for influencing the gas permeability and chemical resistance,
• - aluminum hydroxide to influence the flame retardant,
• Magnesium carbonate for influencing the green strength,
• - Barium sulfate for use in noise insulation, radiation protection, to influence the acid resistance,
• Calcium oxide for use as a water and acid acceptor,
• Titanium dioxide for use as a UV stabilizer,
• Alumina for use as an inert filler,
• Zinc oxide for use as a crosslinking agent and for influencing heat resistance,
• - Magnesium oxide for use as an activator and for influencing the heat resistance.

An example of a low to medium-strength reinforcing system is aluminum silicate, silica, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcined kaolin, silanized kaolins. A medium to high amplification system exemplify: aluminum silicate, silanized silicates.

An example of the liquid ingredients are the aforementioned plasticizers. These are preferably naphthenic or aromatic mineral oils.

The invention will be described below with reference to the figures. Showing:

1 : a process chamber of the RingExtruder with 12 co-rotating, tightly meshing screws.

2 : a snail package from the RingExtruder with 12 co-rotating, tightly meshing snails.

3a - 3f : Sample examples for Z-profiles; 3g -H Sample examples for T-profiles

4a : Principle of operation Z-profile elements; 4b Principle of the T-profiles

5 : RingExtruder housing with conventional housing design.

6 : RingExtruder housing with optimized cooling channel system and thin-walled wear protection insert.

7 : a screw cooling at the RingExtruder.

8th : Qualitative melt temperature curves over the outlet cross-section of the RingExtruder as well as with twin-screw extruders.

9 : an exemplary construction of a RingExtruder for continuous rubber preparation.

10 : An exemplary installation of a single-screw extruder as a co-extruder to the ring extruder for the feeding of endless rubber strips in the context of continuous rubber preparation.

11 : a RingExtruder control with user interface of the RingExtruder control.

12 : an exemplary addition of a barrel melter in combination with three heated, gravimetric dosing scales as liquid doses to the ring extruder for continuous rubber preparation.

13 A basic body of a dome housing for atmospheric venting or vacuum degassing.

14 : an installed assembly (right) of a dome housing for atmospheric venting or vacuum degassing.

15 a nozzle for producing special geometries; here: discharge of several strips.

16 : a tube slot nozzle.

17 : a discharge of easily flowable products.

18 : a free discharge without nozzle, z. B. for extruder or Kalanderbeschickung.

19 : A schematic representation of a continuous rubber processing plant with the RingExtruder to illustrate various peripheral options.

The RingExtruder often consists of six, according to the below-described embodiment of twelve coaxial screws 1 in a circular arrangement. All adjacent shaft centers 2 have the same center distance and interlock closely ( 1 ) The screws rotate with identical speed fixed around their own central axis. The motion conditions, at least when considering two adjacent screws in isolation, are very similar to the co-rotating, tightly meshing twin screw. From this it can be concluded that in principle the RingExtruder can not only fulfill all the tasks of the twin-screw extruder in at least the same quality, but is also available for completely new applications.

How out 1 shows, are formed by the arrangement of the screw shafts in a circular ring two oppositely acting areas. The outer area 3 is located between the extruder housing 4 and the snails, the inner area 5 between the snails and the stationary core 6 , While the material 7 in the outer area of a screw to the neighboring screw in a clockwise direction and at the same time is promoted to the outlet, the material transport takes place in the counterclockwise direction in the interior. This results in an opposite material transport in the circumferential direction. These conditions lead to optimal Conditions for intensive cross and longitudinal mixing. For this purpose, only a mass transfer between the two process spaces must be realized, for which a wide range of mixing elements is available.

The process chamber unaffected by the housing in the transfer area from worm to worm, also gusset 8th is used in the RingExtruder as a central procedural instrument. In the gusset 8th the product is transferred to the adjacent screw by a flow across the flow. The volume of the gusset creates a three-dimensional expansion flow. This results in a Stoffaauchauch without partial overloads with excellent dispersing, wetting and Homogenisierwirkung instead.

In 1 beyond that is the free space 9 to recognize, which is used for the further processing of the material. This free space is required, for example, if additional formulation components are supplied in the side stream. In addition, this space is important when degassing processes are to be performed. Due to the free space melt surfaces are formed, which are necessary so that the gases can escape from the melt. In addition, free space is needed for the gases to move to the housing openings.

With each screw, two neighboring screws are simultaneously engaged in the ring extruder. The screw surface is thereby stripped twice each time the screw is rotated. Thus, the self-cleaning again designed significantly more intense than the same direction rotating double shaft. This results in the possibility of processing the material in the extruder within very narrow residence time spectra. This is especially in the implementation of chemical reaction processes such. B. in the silanization reaction of importance. In addition, the excellent self-cleaning leads to extremely short transition times with material and operating point changes. As a result, the extruder is much faster in a stable production state and the amount of waste is significantly reduced. Furthermore, new material surface is formed during each self-cleaning process. This results in a high surface recharge rate, which is of crucial importance for degassing operations.

Out 2 becomes a snail pack 10 of the RingExtruder with 12 co-rotating, tightly meshing snails 1 recognizable. The extruder housing and the fixed core are intensively coolable.

In addition to the familiar screw geometries of the twin-screw machines, elements of the T-profile specially developed for the RingExtruder as well as the Z-profile technology are available in the form of two- or multi-start kneading blocks or conveying elements. 3a - 3f (Z-profile) and 3g -H (T-profile).

The T-profile elements have an asymmetric cross-sectional area in which an enlarged gap is created between one of the screw flights and the extruder housing. Nevertheless, the elements are completely self-cleaning.

The Z-profile is a purposeful deviation from the self-cleaning Erdmenger profile. Thanks to an intelligent combination of the individual, adjacent worm shafts, the self-cleaning effect can nevertheless be fully guaranteed. In these elements, one of the screw combs has a reduced outside diameter. This creates an enlarged gap between the adjacent screws and between the screws and the extruder housing at this point.

For both types of elements, the increased gaps cause the material transported through this area to experience significantly lower shear rates compared to stress in the standard gap. On the other hand, it is known that in standard games, materials are mechanically and thermally overstressed in this area between the screw crest and the housing surface. This often causes mechanical and thermal damage to the extrudate. In this respect, increasing one of the gaps helps to reduce local shear and temperature spikes, thus decreasing the mean melt temperature and sparing the material.

The Z-profiles and T-profiles are described in more detail below:
The T-profile elements is a generalization of Erdmenger in the patent DE 862 668 described, self-cleaning design principle, so-called Erdmenger profile.

The 4a shows the principle of action of Z-profiles, the 4b the operating principle of T-profiles.

The 3a - 3c show embodiments of conveyor elements 15 while the 3d - 3f Embodiments of kneading blocks include.

In the Z-profile, one of the screw combs has a reduced outer diameter ( 3a ). Through this return 17 arises at this point the mentioned enlarged gap between the adjacent screws as well as between the screws and the extruder housing.

This enlargement of the gap 18 or the reduced outer diameter on one side of the cross section of the conveying element is a standard gap 19 or a standard outer diameter of the cross section of the conveying element on the other side, 3b , Next is the internal toothing 13 to recognize 3b , c, e, f.

The same applies analogously for the 3d - 3f illustrated kneading blocks. 3e shows the enlarged gap 22 the first kneading disc 23 of the kneading block 21 ,

In that regard, supplementary to the Austrian patent application AT 2A A / 608 / 2012-1 referenced, the disclosure content of which is part of the present application.

The already mentioned technology of the T-profile is in 3g -H shown. This is particularly advantageous in RingExtrudern. It shows a tight-fitting, self-cleaning profile. The cross-sectional area of the T-profiles is symmetrical. This creates the in 3g - 3h represented screw profiles or kneading elements. The 3g shows the conveyor element 24 , The other conveyor element is with 25 designated. The comb 26 the first gear of the first conveyor element 24 strips the inner wall of the housing as well as the flank and the core of the other conveyor element 25 substantially dense (not shown) with which it engages. The conveying element 25 has a crest 27 of the first corridor. The conveying elements shown there are each with an internal toothing 13 provided in order to secure them on two unrepresented axially parallel co-rotating waves.

The 3h shows a section of two intermeshing conveyor elements with ring sections and a section of a multi-screw extruder arranged on a circle waves. The conveyor elements 24 and 25 show up 3h Conveying sections, each with a concentric ring 33a respectively. 34a , The size H of the annular gap 35 . 35 ' between the rings 33a respectively. 34a and the dash-lined housing inner wall is between a 1/4 and 1/3 of the flight depth, or about half of the flight depth.

In the embodiment of an extruder according to 3h shown conveying elements 24 . 25 are rotatably mounted on axially parallel shafts, which are arranged along a circle, wherein the conveying elements 24 . 25 strip each other on the whole circumference. The conveyor elements 24 . 25 consist of conveyor sections with a profile offset by 180 °. In a 12-wave ring extruder, there are 12 conveying elements, that of those of the conveying elements 24 . 25 correspond.

With respect to this T-profile technology reproduced above is also based on the applicant to the applicant German patent application DE 10 2008 016 862 A1 whose content is also fully made the subject of the present application.

4a , b showed for the Z-profiles as well as for the T-profiles that the interplay between the enlarged and the standard gap leads to additional mass transfer. At the same time, a melt film is applied periodically to the metallic surfaces and then stripped off again.

In the in 4a illustrated embodiment of a RingExtruder with twelve coaxial screws with Z-profile shows the reference numeral 28 the black-colored rubber material while the white areas 29 specify the free volume. With 36 the aforementioned standard gap or annular gap is marked. In the area of the standard gap 36 the self-cleaning takes place. The mass transfer gap is indicated by the reference numeral 37 characterized. 38 stands for the (rubber) material coated housing surface.

The material coated surface of the screw is with 39 designated. Because the snails 1 Fixed around their own metal axis and rotate in the same direction, as mentioned above, and have the above-described structural design, are also cleaned areas of the housing surface 40 and cleaned areas of the screw surface 41 recognizable.

4b shows an analogous embodiment of the T-profile. digit 28 shows the rubber material while 29 stands for the free volume. Im with 42 designated standard gap area is the self-cleaning. The numeral 43 shows the enlarged gap. Here the mass transfer takes place. The coated with rubber material housing surface is with 44 characterized. The cleaned housing surface is through 45 characterized.

In addition, this gap area can be used for process mixing and dispersing tasks. Due to the fact that a significant leakage flow ( 4 ) forms over the screw comb, an additional mass transfer between the individual screw channels can be achieved, which contributes to the homogenization. Furthermore, the area can be used as a shear gap, in which the material is exposed to a defined mechanical stress. These Shear stress can be used for dispersive mixing effects, as the shear stresses that occur contribute to the dispersion of particles and agglomerates. This is additionally supported by the fact that the reduction of the comb height in this area inevitably leads to a broadening of the comb. This results in addition to the increased height and at the same time an enlarged length of the gap. This is equivalent to an extension of the gap in the circumferential direction, so that the residence time of the material in the shear gap and thus the dispersive mixing effect can be increased. At the same time, additional expansion flows are generated shortly before the passage of the material through the gap, since in this region the flow cross-section tapers in the circumferential direction. This effect is well known from studies of flow fields in kneading blocks of twin screw extruders. These increased expansion flow rates can be used extremely efficiently for dispersing tasks.

When applying the design principle on conveyor elements, it is still possible to divide the component in the axial direction into individual sections. In each of these segments, the cross-sectional profile by an offset angle in the circumferential direction, z. B. 180 °, to be twisted. This alternates in the process direction of the conventional and the enlarged gap. Such screw mixing elements are, for example, outstandingly suitable for use in the area of the side stream metering of a ring extruder. In this case, through targeted utilization of the leakage current over the enlarged housing gap, mass transfer between the screw channels with minimal energy input can help to gently distribute and wet the secondary components supplied to the extruder. In this way, for example, the formation of agglomerates of powdered components can be prevented by compression.

Further advantages of such elements arise in the degassing of the extruder. By spreading wall-mounted plasticates on the screw and cylinder surface over the enlarged gap, a melt film with adjustable layer thickness can be produced, which can outgas under the influence of vacuum. After half a turn of the screw, it is forced to be stripped off and then renewed again. Furthermore, it is to be expected that the heat transfer from the melt to the extruder barrel is intensified. This is also due to the formation of a material film and its constant renewal, whereby the heat transfer coefficient can be increased.

In the production of rubber compounds with the RingExtruder whose excellent dispersing effect with minimal mechanical energy input into the plasticizer comes into play. In the case of rubber compounds, extremely high proportions of filler (in particular also carbon blacks and silicates) and liquid components often have to be finely dispersed and distributed. Due to the 12 intervention areas of the extruder screws ( 1 ), the ring extruder unfolds high expansion flow rates in the gussets. These can be used very efficiently and energy-saving for dispersion.

Important here is the relationship between dispersing effect and flow form. In various investigations it could be shown that a droplet separation from a certain viscosity ratio between matrix and droplets is only possible in the extensional flow field. A droplet in a pure shear flow differs in part from the stress with a rotational movement. Therefore, a breakdown at such viscosity ratios is not possible and the mechanical energy input results only in an undesirable increase in melt temperatures. The droplet fragmentation is, however, almost independent of the viscosity ratio in the presence of increased Dehnströmungsanteile. In addition, the dispersion takes place at considerably lower mechanical material stress. This results in addition to the improved dispersion at the same time a significant reduction of the specific energy input and thus the melt temperatures.

Based on three-dimensional flow simulations, it could be demonstrated that the expansion flow rate in a ring extruder is significantly higher than in a twin-screw extruder with comparable output. The increased expansion flow components concentrate in the gusset areas 8th ( 1 ).

Comparing machine types under identical conditions resulted in an integral value that was 41% higher on average than the free cross-sectional area of the process rooms. This is due to the strong deflection and compression of the material in the gusset gap and the higher number of gussets in the ring extruder. Due to the increase in the number of screws, the plasticates also go through the gusset areas much more frequently. From this it can be deduced that cutting and mixing processes in the RingExtruder are carried out much more effectively. As a result, a significantly better product quality can be generated at a lower melt temperature. Consequently, the specific energy input into the plasticizer is significantly lower and the production process is considerably more economical.

Rubber compounds produced in the RingExtruder have convincing advantages for articles which are crosslinked by microwave irradiation. In this vulcanization method, polar molecules absorb the radiant energy and thus heat the compound. In contrast, nonpolar substances can not be heated by means of UHF. However, the absorption of weakly polar or nonpolar rubbers can be increased by admixing polar polymers or fillers, in particular active carbon blacks.

The excellent dispersing effect of the RingExtruder leads to extremely small particle sizes of the fillers used and avoids agglomeration. Likewise, finely dispersed morphologies are produced when compounding incompatible rubber types with widely differing polarities. This leads to a homogeneous distribution of the polar mixture components and thus to a very homogeneous radiation absorption in the volume of the product. As a result, local overheating in UHF networking is prevented. As a result, the anode voltages of the magnetrons can be significantly increased. This considerably speeds up the crosslinking process and leads to a huge increase in production efficiency.

The control of the melt temperatures plays a central role in the production of rubber compounds in order to avoid material degradation or unwanted vulcanization. The RingExtruder is characterized in this context by a very high surface / volume ratio. Therefore, based on the amount of plasticizer in the extruder, a very large heat exchange surface is available. Constructively optimized designs of the extruder housing with two or more independent cooling channels as well as the central core with maximum cooling channel cross-section thus allow efficient cooling of the process part.

Particularly noteworthy in this context is the use of innovative wear protection inserts in the extruder barrel (inliner) with minimal wall thickness. In contrast to the conventional inliner constructions acc. 5 allows the thin-walled design to place the cooling channel bores much closer to the process space surface ( 6 ). In addition, thermally conductive materials can be introduced between the main body of the extruder housing and the wear protection insert in order to intensify the thermal contact. In this way, the heat transfer coefficient and consequently the cooling capacity can be significantly increased while ensuring a high level of anti-fouling and / or corrosion protection.

5 shows a RingExtruder housing as well as a thick, thick inliner 47 and a number of cooling holes 48 ,

6 : shows a RingExtruder housing 46 with optimized cooling channel system 49 and thin-walled wear protection insert 50 in comparison to the conventional housing construction. The shown RingExtruder housing with double, near-surface cooling channel system and thin-walled inliner is intensively coolable. The cooling holes are with 51 designated.

Such a preferred inliner is in detail in the German utility model DE 20 2014 002 902 the applicant described. This entire disclosure is hereby expressly incorporated into the description of the present application.

Furthermore, with large ring extruders it is possible to cool the screws directly. The cooling can be considered as open ( 7 ) or closed system (Heat pipe 52 or thermosyphon, 7 ). In this way, the enormous surface of the twelve screws is used to control the melt temperature.

In addition to a lowering of the melt temperature, the screw cooling also causes a significant unification of the temperature distribution of the product at the outlet of the extruder. It is known that occurs in extruders of various designs, a local mass temperature increase in the area of the screw tips 53 on. Due to the smaller screw diameter and the lower peripheral speeds, these are significantly lower for the RingExtruder due to the system than for twin-screw extruders. By using cooled screws, these temperature peaks can be significantly reduced ( 8th ). Show here 54 the worm shaft, 55 the fluid line, 56 the flow of the incoming cooling liquid, 57 the exit of the heated cooling liquid, 58 the direction of the steam.

8th : shows qualitative mass temperature curves over the outlet cross-section of the RingExtruder as well as with twin-screw extruders.

Another major difference to the internal mixer systems is the possibility of degassing the plasticizer in the process chamber of the RingExtruder at ambient pressure or under vacuum. Due to the distribution of the mass flow to the twelve screw channels in the ring extruder (cf. 1 . 2 ) is an enormous plastic surface at extremely small volumes available. Furthermore, the twelve engagement areas of the snails lead to a strong Shifting of the material and thus to a high surface recharge rate. This results in a very efficient degassing performance of the RingExtruder. In this way, the moisture or other volatile substances contained in the individual mixture components can be removed efficiently, so that a pore-free extrudate is ensured. Likewise by-products, which can arise during chemical reactions, are eliminated. This promotes the reaction kinetics in many applications and leads to improved product properties.

The ring extruder is used in the elastomer or rubber sector for various tasks in continuous compounding. In so-called "premixing", in addition to the addition of a wide variety of fillers and liquids, partial reaction or coupling processes are carried out. In "Final mixing", inter alia, the crosslinking chemicals are mixed in, so that incipient vulcanization must be prevented by a very accurate temperature control. In this context, however, it has repeatedly been shown that the tolerable upper limits of the melt temperatures in the RingExtruder can be set much higher than in the internal mixer systems. This is due to the fact that the residence times in the extruder are many times lower than in the internal mixer. Furthermore, comparatively thin extrudates can be cooled much faster than a compact rubber mass of several hundred kilograms from an internal mixer. This results in the possibility for some formulations to carry out coupling reactions and the mixing in of the crosslinking chemicals in one step. If necessary, however, two ring extruders can also be connected in series as a cascade system, so that certain sub-processes can proceed at different temperature levels.

In the overall concept, rubbers that are available as bales are first crushed. In order to prevent sticking of the material to be ground, powdering with a release agent is carried out during the grinding if necessary. In general, a powder can be used for this purpose, which is contained in the rubber mixture anyway, z. As chalk, talc, kaolin, carbon black or silica, so that contamination by foreign substances is excluded. This process has proven to be reliable even for very sticky rubbers such as butadiene rubber.

The supply of material (including natural and synthetic rubbers, solid and liquid polymers, fillers such as carbon black, silica, kaolin, talc and chalk, and resins, fats and oils as plasticizers, zinc oxide, sulfur, pigments, additives such as protective agents against Aging processes as well as various other chemicals, slums, and suspensions) in the extruder by means of gravimetric or volumetric dosing systems ( 9 ), which can also be meaningfully combined for certain processes. Commercially available equipment for solids and liquids can be used. These have been used for decades in the processing of thermoplastics and ensure a long-term constant compliance with the recipe specifications within minimal tolerances.

9 : shows an exemplary structure of a RingExtruder 59 for continuous rubber preparation. The structure of a RingExtruder can be seen that in the part shown on the left the addition of the main components 60 , in particular the polymers 61 , the rubber 62 , the additive 63 as well as the fillers 64 takes place in the actual extruder strand. The part of the system on the right shows further optional additives 65 partly via so-called SideFeeder 66 or other lines supplied to the system. A vacuum system 67 can be optional and a vacuum stuffer 68 , Further, the drive 69 and the power split transmission 70 of the RingExtruder 59 shown.

In principle, the modular design of the extruder cylinder and the screw geometries ensure maximum flexibility with regard to material supply points. Solids of different particle size and shape or material mixtures are the process space as bulk material together or separately via the feeder housing, in the modular arrangement, the first housing of the RingExtruder supplied. Additionally or alternatively, material can also be supplied via an installed on the feed housing and / or a laterally mounted attachment to one of the further downstream arranged housing.

Depending on the material properties and process requirements, aggregates such as single-screw extruders, twin-screw extruders or gear pumps ( 9 . 10 and 11 ). The attachment position on the left or right side is freely selectable. It is even possible to operate two opposing feed units on an extruder housing. Depending on the system, a gravimetric or a volumetric dosage or a combination of both systems can be used. The control of the RingExtruder, RingExtruder-Control, allows uncomplicated handling even of complex metering processes on a panel ( 11 ) or a central process control system and offers extensive possibilities of recipe management as well as automated start-up procedures.

10 : shows an exemplary cultivation of a single-screw extruder as co-extruder 71 to the ring extruder 59 for the supply of endless rubber strips in the context of continuous rubber preparation. To recognize further include the ring worm shafts 1 as well as the discharge with nozzle 114 , Evident is also composed of engine, safety clutch and gear drive 69 , Furthermore, the system has two side feeders 66 . 107 , It also has two vacuum stuffers 68 on.

11 : shows an embodiment of a RingExtruder control unit with user interface of the RingExtruder control.

The controller leaves the panels for the vacuum stuffer 68 detect. The plant has three gravimetric solids dosing devices 102 that have at least two side feeders 66 . 107 supply with cloth. The gravimetric liquid dosing device carries the numeral 103 , The barrel press is a tandem barrel press with single presses 81 . 82 designed. The rubber strip original device 112 populates the co-extruder 71 that as a conveyor 106 having a gear pump, and to the ring extruder 59 connected. Furthermore, the system has a metal separator 100 , The drive 69 has a power dividing gearbox 70 , At the left end of the RingExtruder 59 is the discharge with nozzle 114 recognizable.

High and medium viscosity materials such as rubber masterbatches or polymer-bound chemical concentrates can be added to the RingExtruder 59 with the help of a single-screw rubber extruder 71 The addition deposit may also be selected according to the process requirements either at the intake housing or further downstream.

These co-extruders 71 mentioned device differs in principle from those shown above and in 9 SideFeeders shown 66 . 107 , In principle, the function of SideFeeders is to optionally pick up further additives or other fillers and feed them to the actual extruder for processing. In these SideFeedern regularly no processing or processing of these substances supplied; if necessary, the substances are densified.

In the present invention, however, the co-extruder assumes the task of a preprocessing device. Its mode of action goes beyond that of a pure dosing station.

The co-extruder can be configured as a single-screw extruder or as a multi-screw extruder.

In the co-extruder, for example, endless rubber strips can be introduced.

After the introduction of the material to be processed, that is about in the form of polymers, rubber, fillers, endless rubber strips, etc., a processing of this material takes place. This feature will hereinafter also be referred to simplifying and summary as a rubber material. This material is masticated and then forwarded to the actual ring extruder. This can be done for example via a gear pump or directly in such a way that in this way masticated material is transported further in the ring extruder.

This gives the RingExtruder an already preprocessed material. This brings surprising benefits. By using such a co-extruder, a partial displacement of the torque required for the overall extrusion process takes place in the co-extruder. As a result, the ring extruder is relieved of torque. This leads to a faster, more effective further processing of the preprocessed material fed into the ring extruder. As a result, in particular, the throughput is improved. Likewise, a significant increase in product quality was observed.

Due to the preprocessing of the rubber material, its more uniform absorption into the ring extruder takes place because it has already been plasticized to a considerable extent in the co-extruder. The product stream flowing into the ring extruder is thus more uniform.

This means that it is precisely the combination of the co-extruder in combination with the ring extruder that allows finer, more efficient, faster and quantitatively larger processing of the rubber material.

As stated, the co-extruder may be disposed at any angle on the main line of the ring extruder. The arrangement can be done by flanging, screwing, welding or similar measures.

Especially through the adoption of essential processing steps by the co-extruder, so in particular the masticating, its mode of action goes far beyond the mode of action of conventional side feeders, which are ultimately limited to dosing functions. The RingExtruder is not only supplied with material, for instance by means of a SideFeeder or another receiving part, but already preprocessed material. The fact that the masticating and thus plasticizing of the material to be processed is at least partially displaced into the co-extruder, the ring extruder is in significantly influenced his way of working. As a result, he receives more process length and thus has more opportunities to carry out the other necessary process steps, such as the further mixture of the product. He needs less torque. The temperature can be lower in the ring extruder, which greatly facilitates the processing of the rubber material. An increase in throughput is also given to a considerable extent.

The advantages according to the invention already occur when the masticating process has been started. An extensive or complete mastication can have advantages. An incipient mastication, however, already contributes significantly to the mentioned advantages.

Thus, this solution also differs from about in particular series connected main extruders, where this solution can be described as a cascade solution. In this cascade solution, the processing of the material takes place in the respective extruder. This main extruder must have the necessary torque forces, it must be able to absorb significant temperatures, which can lead to premature material fatigue. This procedure is not influenced by the fact that several extruders are connected in series. All extruders must be able to meet the same high parameters. Above all, the further transport from the first extruder into the following extruder takes place regularly without pressurization, ie. H. it occurs by this series process process rather a slowing down of the extrusion process implementation instead.

In the case of the co-extruder according to the invention, however, pressurization may preferably take place.

The co-extruder may be a single-screw or multi-screw extruder, as shown. The choice of the right extruder will be made according to the process parameters to be performed. In most cases, the use of a single-screw extruder will be evasive, which represents the technically less expensive device in this respect. Thus, a single-screw extruder is also cheaper. Due to its channel depth he has even procedurally favorable parameters, especially when it comes to the collection of rubber strips of material or the like.

A particularly advantageous embodiment can be achieved if the co-extruder, for example, from a feed roller 111 (not shown) is fed with the material to be processed. This feed roller can be grown on the co-extruder in a spatially suitable manner and continuously push rubber strips continuously into the co-extruder.

By arranging several of these apparatuses, a process interruption can be avoided if the material to be processed, which is intended for a co-extruder, has been worked up.

In a further advantageous embodiment, the device may be provided with a pressure monitoring device, which is preferably arranged at a transfer point of the material.

In the co-extruder can be entered in addition to the aforementioned rubber strip, preferably endless rubber strip and free-flowing or chopped good.

Material strips, skins, cords, ribbons or profiles of different cross sections and lengths as well as endless materials can be processed.

To optimize the intake of such strips of material can be used in addition to the feed hopper of the single screw extruder, a feed roller.

The material is masticated in the co-extruder and via a special, attached to the side opening of the RingExtruder, adapter 72 (not shown) entered into the process space of the RingExtruder. One to max. 500 bar extendible pressure sensor in the adapter serves as a signal generator of an integrated emergency shutdown of the side unit at too high pressure. In order to achieve a uniform volumetric dosing, a gear pump can be integrated between discharge of the side extruder and adapter on the ring extruder housing. The throughput is set by the set pump speed, and the speed of the rubber extruder is controlled so that a preselected mass pressure at the inlet of the gear pump is achieved.

The dosage of liquids or suspensions can be realized by means of volumetrically or gravimetrically controlled pumps of various types or by means of barrel presses.

Of course, several liquid feeds can be operated simultaneously at different positions of the process part ( 12 ).

In the 12 shown attachment 73 an embodiment for the continuous preparation of rubber material shows a RingExtruder 59 with drive 69 and Power split transmission 70 , The attachment 73 is doing by the controller 74 either centrally controlled. But it is also possible to control the individual components decentralized. The power split transmission 70 includes the annularly arranged worm shafts 1 , Furthermore, the system has the solids metering device 75 on. The feeder controller 76 is a control unit for the dosage of added substances. The system shown has three liquid metering devices in this embodiment 77 . 78 . 79 ,

Furthermore, the facility has 73 via a tandem barrel press 80 that from their individual barrel presses 81 and 82 is formed.

The ring extruder 59 has injection valves at various areas of its process space 83 . 84 . 85 . 86 on, the supply, in particular amount, throughput of the added liquids or pasty materials accomplish.

Barrel presses in the design of barrel melters also allow the melting of low-melting components such. As waxes or fats or heating poorly flowable liquids or suspensions to reduce the viscosity.

With appropriate design such materials can be dosed with heatable pumps, if they were melted or heated in an upstream process step. Temperable storage tanks and pipes or hoses ensure the necessary temperature stability and operational safety.

Tandem devices are available for both drum presses and barrel melting plants in order to achieve long-term, uninterrupted metering.

They can also be combined with downstream gear pumps, which meter the liquids or suspensions with improved dosing accuracy in the extruder. Again, the supplied volume flows are determined by selecting the pump speed and the barrel presses or -schmelzanlagen regulate a constant pump pressure.

Of course, such arrangements can be arbitrarily combined with flow meters and static or dynamic mixing devices.

It is also possible to use the units to feed a dosing station when a liquid or suspension is to be distributed to several injection points on RingExtruder. A press feeds two or more gear pumps, which inject the material into the ring extruder at different points in a defined quantity distribution.

The aforementioned barrel press is preferably constructed so that it has a punch 87 (not shown), which is received by a receiving device, for example a barrel. In this recording device to be inserted in the context of the extrusion process Good. It may be about a liquid or a pasty mass. The stamp is designed movable and compacted at a controllable speed.

By this measure, the good is pressed into a tube or about in a hose. In this way, the good is discharged from the receiving device and simultaneously transported. Transport can take place to the ring extruder. The good can also be pressed directly into the ring extruder.

Preferably, the barrel press can be configured as a fiber melting plant. In this case, it is particularly preferable for the stamp to be heatable, which can also heat very poorly flowable materials, melt solids, so that they become liquid and then easier to compact.

It is particularly advantageous if barrel presses are designed as tandem devices. These then have two punches. If a preparatory device is empty due to the processing operation, otherwise the process would have to be interrupted and a new barrel press would be installed. In a tandem device this is not necessary. The whole process does not have to be interrupted.

The design of a tandem press can be done so that a stamp then anfährt when on the other side, the receiving device is empty.

A tandem drum system is therefore particularly suitable for volumetric liquid metering.

The drum melt may preferably be connected to one or more gear pumps. The press pushes this one or more gear pumps. The one or more gear pumps run at constant speed, which ensures that the volume flow is constant. The barrel press regulates the admission pressure of these one or more gear pumps.

But it is also possible that the barrel press fed a dosing, so that from the barrel press one or more gear pumps with Run corresponding throughput and feed the material to be transported directly or indirectly at one or at different points the RingExtruder.

The entry of liquids or suspensions into the ring extruder takes place via housing bores with corresponding connection geometry. Alternatively, the plugs for SideFeeder or Stufferöffnungen can be provided with appropriate injection holes. This provides additional flexibility as the plugs can be positioned at different locations depending on the design of the extruder. Depending on the type and amount of aggregates and the screw configuration, the injection takes place via tubular connecting sleeves or special injectors ( 12 ).

Analogously, dosing systems with mass flow control and corresponding injection valves for the injection of gases - even in supercritical state - are available and can be integrated into the control of the RingExtruder. Typical applications are, for example, foam extrusion or the optimization of degassing processes by stripping. In the process, inert gases and / or liquids which can be vaporized under the conditions of degassing are mixed homogeneously into the material to be processed in the extruder. When passing into the degassing zone, the gas and / or the evaporating liquid leads to foaming. In this way, the surface of the material is extremely enlarged and significantly reduces the diffusion paths of the volatile components to be degassed to the material surface. This enormously increases the efficiency of subsequent atmospheric or vacuum degassing.

13 : shows a degassing housing 87 with a connection opening 88 for a vacuum dome.

The removal of the substances to be degassed and the stripping agent via a large, overhead housing opening to which a vacuum dome can be connected if necessary (Domgehäuse 89 . 14 ).

14 : shows an installed assembly of a dome housing 89 for atmospheric venting or vacuum degassing.

Alternatively, stuffers can be used. These are compact, identical or opposite double-screw units, which fulfill the task of keeping the housing opening free and to prevent the escape of product from the degassing. Up to three stuffer can be connected on both sides as well as on top of the same housing module. Furthermore, of course, several stuffer can be operated on different extruder housings and combined as needed with the Dom degassing. Furthermore, the degassing can be constructed in several stages, whereby individual sections can be operated at different negative pressures or also atmospherically. Dusting areas within the screw configuration provide the necessary sealing between individual degassing sections.

Depending on the process requirement, viscosity, material quality, temperature and connection to downstream systems, the extrudate is discharged via nozzle plates with process-oriented design of the openings (FIG. 15 ). Examples are slot dies, tube slot nozzles ( 16 ), or for liquid discharge pipes with multi-way valves ( 17 ). The tube slot nozzle leaves the slot device 90 as well as the exit area 91 detect leaking, tubular material.

17 : lets the end 92 of the RingExtruder. Furthermore, the tubular discharge 93 for easily flowable products.

In Austragsvarianten with increased pressure requirements and / or to ensure a highly constant output of the discharge nozzle can also be preceded by a gear pump. Additionally or alternatively, a filtration (Strainer) of the product can be realized in front of the nozzle or a static mixer can be integrated. Also feasible is the direct extrusion to semi-finished or finished parts of different geometries. On the other hand, the extrudate can also without shaping as a more or less coherent mass or crumb on a free discharge without nozzle back pressure ( 18 ) are processed, for. B. for feeding downstream units such as extruders, calenders or rolling mills.

In 18 is the central core 92 , So the inner part of the extruder housing shown. Further, the worm shafts 1 recognizable.

With the described process options, it becomes clear that the ring extruder can be expanded into a complex processing plant for the continuous production of rubber compounds. The flexibility that is available when needed is unique.

In summary, the 19 a selection of the possibilities of variation shown schematically, which can be implemented in reality in almost unlimited combinations.

19 : shows a schematic representation of a continuous rubber processing plant 110 with the ring extruder 59 to illustrate various peripheral options. The ring extruder 59 has a drive 69 and a power split transmission 70 on. You can also see the worm shafts 1 ,

The drive 69 has in this case drive shafts, which are connected to the coaxial rotatably. Each drive shaft has a pinion. The drive pinion mesh with a provided on a central drive shaft, externally toothed drive wheel. The torque of each drive pinion is introduced proportionally via the central externally toothed drive wheel and half via the complete internally toothed ring gear. In that regard, for further description of the drive 69 on the German registration DE 103 15 200 A1 which is incorporated herein by reference. The same applies to the in DE 10 2008 022 421 A1 in detail described extruder gear.

On display is an extruder plant that includes a ring extruder 59 , Furthermore, it has a rubber bale-loading device 93 on. Likewise, a bale splitter 94 be provided. The bales crushed in this way then become a mill 95 fed. In further processing, a release agent metering takes place via a release agent metering device 96 , In addition, in this respect, a release agent-return device 97 provided that the one or more release agents are not completely used up.

Furthermore, the facility can be powered by a blower 98 and over a cyclone 99 have, by means of which the hitherto processed good the further process section are fed. Here, the estate can be a metal separator 100 run through. It occurs in a stirrer storage container 101 to which a device for gravimetric solid dosing 102 can be connected.

A device for gravimetric liquid metering 103 may be provided as one or more injectors 83 . 84 , The plant preferably has a tandem barrel melting plant 80 . 81 . 82 for a volumetric metering of the material to be introduced, in particular for a volumetric liquid metering.

The extrusion line preferably has a rubber strip template 112 containing one or more co-extruders 71 . 105 preferably equipped with a strip-shaped rubber material. The co-extruder is preferably a single-screw extruder and can via an additional conveyor, in particular a gear pump 106 for a strip dosing. The extruder 59 preferably has a feed funnel 109 on. The co-extruder 71 . 105 preferably each has a feed hopper 115 . 116 on.

In addition, the system can have one or more side feeders 66 . 107 have, in which optional auxiliaries or additives are supplied to the process process.

Preferably, a metering station 113 intended for (supercritical) gases with mass flow control.

A stuffer 68 for atmospheric venting or vacuum degassing is also a preferred device of the plant. Furthermore, the system can be powered by a vacuum pump 108 or via a nozzle / on-discharge tool.

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

• DE 862668 [0054]
• AT 608 / 2012-1 2AA [0060]
• DE 102008016862 A1 [0064]
• DE 202014002902 U [0082]
• DE 10315200 A1 [0150]
• DE 102008022421 A1 [0150]

Cited non-patent literature

• F. Röthemeyer, Rubber Technology: Materials, Processing, Products, Carl Hanser Verlag (2nd revised edition, 2006), 413 [0002]

Claims (11)

Multi-screw extruder, in particular ring extruder ( 59 ) for the continuous preparation of rubber material with at least six in a circle in a Etxruder housing ( 3 ) arranged axially parallel, co-rotating screw shafts ( 1 ) characterized in that the multi-shaft extruder comprises at least one co-extruder ( 71 . 105 ), which is arranged on the multi-shaft extruder and feeds material for the continuous rubber preparation to the multi-shaft extruder, wherein the co-extruder ( 71 . 105 ) is suitable for mastication. Multi-screw extruder according to claim 1, characterized in that the co-extruder ( 71 . 105 ) is a single-screw extruder or multi-screw extruder. Multi-screw extruder according to claim 1 or 2, characterized in that the co-extruder ( 71 . 105 ) at the input housing of the multi-shaft extruder ( 59 ) or further downstream. Multi-screw extruder according to one or more of the preceding claims, characterized in that the co-extruder ( 71 . 105 ) is suitable for receiving material for the continuous preparation of rubber in the form of strips of material, skins, strings, tapes or profiles of different cross-sections and lengths and endless materials. Multi-screw extruder according to one or more of the preceding claims, characterized in that the co-extruder ( 71 . 105 ) via a feed funnel ( 115 . 116 ). Multi-screw extruder according to claim 5, characterized in that the co-extruder ( 71 . 105 ) in the feed hopper a feed roller ( 111 ) for optimizing the collection of strips of material. Multi-shaft extruder according to one or more of the preceding claims, characterized in that the multi-shaft extruder ( 59 ) has a side opening on which an adapter is arranged, over which the partially or fully masticated material for the continuous rubber preparation of the co-extruder ( 71 . 105 ) can be supplied to the multi-shaft extruder. Multi-shaft extruder according to one or more of the preceding claims, characterized in that between multi-shaft extruder ( 59 ) and co-extruders ( 71 . 105 ) a conveyor ( 106 ) is arranged in particular a gear pump. Investment ( 73 . 110 ) for continuous rubber preparation, characterized in that it comprises a multi-shaft extruder ( 59 ) according to claim 1. Investment ( 73 . 110 ) for continuous rubber preparation according to claim 9, characterized in that the co-extruder ( 71 . 105 ) is designed according to one or more of claims 2 to 8. Investment ( 73 . 110 ) for the continuous preparation of rubber according to claim 9 or 10, characterized in that it comprises a rubber ball feeding device ( 93 ) and / or a bale splitter ( 94 ) and / or a mill ( 95 ) and / or a release agent dosing device ( 96 ) and / or a release agent recirculation device ( 97 ) and / or a blower ( 98 ) and / or a cyclone ( 99 ) and / or a metal separator ( 100 ) and / or a stirrer storage container ( 101 ) and / or a gravimetric solids metering device ( 102 ) and / or a gravimetric liquid metering device ( 103 ) and / or at least one injection valve ( 83 . 84 . 85 . 86 ) and / or at least one barrel press ( 80 . 81 . 82 ) for the volumetric liquid metering and / or a rubber strip template device ( 112 ) and / or at least one SideFeeder ( 66 . 107 ) and / or dosing station ( 113 ) for gases with mass flow control and / or at least one stuffer ( 68 ) for atmospheric venting or vacuum degassing and / or a vacuum pump ( 108 ) and / or a nozzle / a dispensing tool.

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