Mixing device

Abstract

A mixing device comprises a mixing chamber with a first inlet 115 for receiving at least a first fluid for mixing and with a driven agitator. The agitator comprises a first driven rotor body 130 which divides the mixing chamber into a first compartment 151 and a second compartment 152, and a second driven rotor body 140 which divides the mixing chamber into the second compartment 152 and a third compartment 153. Both agitators comprise on either side mixing arms which act on the mixture during operation and which are provided with one or more passages for allowing transport of the mixture therethrough. A second inlet 120 for receiving at least a second fluid for mixing is provided in the second compartment 152. The third compartment 153 comprises an outlet 150 where the mixture is receivable.

Description

[0001] Mixing device

[0002] The present invention relates to a mixing device, comprising a mixing chamber with a first inlet for receiving at least a first fluid for mixing and with a driven agitator, wherein the mixing chamber is bounded by a cylinder wall and the agitator comprises a first driven rotor body which extends transversely of the cylinder wall in the mixing chamber and is rotatable around a cylinder axis of the mixing chamber, wherein the first rotor body divides the mixing chamber into a first compartment and a second compartment, wherein the first rotor body comprises on either side a first set of mixing arms extending therefrom in axial direction into respectively the first compartment and the second compartment and acting in the first compartment on the first fluid and at least one further fluid for mixing during operation in order to mix the first fluid and the at least one further fluid for mixing together into a first mixture, and 'wherein the first rotor body comprises at least one passage which allows for transport of the first mixture from the first compartment to the second compartment.

[0003] A fluid is here understood to mean a flowing product such as, besides a liquid, for instance also a powder or granules. Such a powder-form or granular product is particularly applied as starting material in the plastic processing industry, particularly for the purpose of thermoforming processes such as injection moulding and extrusion. Thermoplastic plastic granules are here heated beyond their liquid temperature so as to form a liquid mass therefrom, and in this state given a desired form by a suitable mould. After cooling, the product retains its shape and can be released from the mould. In order to preserve thermal stability or to impart a desired colour or mechanical properties to the end product, one or more additives are usually mixed into the plastic granules, such as pigments, lubricants and stabilizers. Fillers are also frequently mixed into the plastic mass in order to limit the proportion of plastic in the end product and thereby limit production costs. Examples of such fillers are calcium carbonate, sawdust and recycles plastic (recyclate). In standard plastic processing this is a discontinuous process. The plastic granules are here first mixed together with one or more additives at a greatly increased temperature into a granular premixture 'which is subsequently cooled to the order of 40 degrees Celsius in controlled manner, after which the mixture still needs to rest. In a subsequent treatment a proportion of filler is mixed into the premixture in order to produce the starting material, usually referred to as dry blend. This can for instance be fed to an extruder in order to form therefrom a liquid plastic mass from which the end product can be manufactured.

[0004] For this penultimate step, wherein a filler is added to the plastic, European patent application EP 3.140.625 describes a mixing device. The known mixing device comprises centrally in a mixing housing a rotating disc body from which a set of mixing arms extends axially. Opposite the disc body, a set of stator arms protrudes from either side into the mixing chamber between the mixing arms. Provided in the disc body is a set of passages so that the mixture which is formed in the first compartment will finally find its way to the second compartment and from there leave the mixer. Although this known mixing device provides excellent results for mixing of a pretreated plastic granulate with a powder-form filler such as calcium carbonate, this known discontinuous approach of hot and cold mixing has the drawback that a great deal of energy, which is needed for heating and then cooling the mixture, is lost. A discontinuous process furthermore does not provide an option to adapt to changing process parameters during forming of the end product.

[0005] The present invention therefore has for its object, among others, to provide a mixing device which obviates these drawbacks at least largely.

[0006] In order to achieve the stated object a mixing device of the type stated in the preamble has the feature according to the invention that the agitator comprises a second driven rotor body which extends transversely of the cylinder 'wall in the mixing chamber and is rotatable around the cylinder axis of the mixing chamber, wherein the second rotor body divides the mixing chamber into the second compartment and a third compartment, that the second compartment comprises a second inlet for receiving therein at least a second fluid for mixing, wherein the second rotor body comprises on either side a second set of mixing arms extending therefrom in axial direction into respectively the second compartment and the third compartment and acting in the second compartment on the first mixture and at least the second fluid for mixing during operation in order to mix the first mixture and at least the second fluid for mixing together into a second mixture, wherein the second rotor body comprises at least one passage which allows for transport of the second mixture from the second compartment to the third compartment, and that the third compartment comprises an outlet where the second mixture is receivable.

[0007] The mixing device thus has a multiple agitator which separates the second compartment from a third compartment. The second compartment has a separate inlet for a second component for mixing, which can be added after a first component for mixing was already brought into contact and mixed in the first compartment with one or more fluids for forming the final mixture. This has the advantage that the premixture can be mixed with the second fluid immediately after in the same mixing device without the usual interim cooling being required therefor. The mixture can be fed while still warm to a plastic processing installation, such as an extruding device or injection moulding device, whereby this will require less energy to bring the mixture up to a flow point at operating temperature.

[0008] The mixing device according to the invention furthermore allows for a fully continuous process, wherein the required components of the mixture are accurately dosed, for instance gravimetrically, at the inlets of the mixing device, after which the mixture formed therefrom is processed in the subsequent installation. If process parameters change during this processing, these can be adapted to seamlessly by adjusting the dosage at the inlets accordingly. After a processing operation by the mixing device, the installation is subsequently fed with the thus modified composition in order to adapt to the changing process parameters. For an improved effect on the components for mixing in the first compartment a preferred embodiment of the mixing device has the feature according to the invention that the mixing chamber is bounded at a first outer end by a first end wall, that a first set of stator arms extend from the first end wall and extend along mixing arms of the first set of mixing arms into the first compartment. The mixing arms thus move between the stator arms extending into the first compartment from the opposite side. This achieves a more powerful agitation of the first mixture, which enhances a good homogenization of the mixture. In a particular embodiment the mixing device is characterized here in that the first stator arms and the mixing arms of the first set of mixing arms maintain in the first compartment laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres. It has been found that this mutual spacing provides an optimal balance between a good mixing and a heat development as a result of internal friction in the mixture.

[0009] To enhance mixing of the components for mixing in the second compartment a further preferred embodiment of the mixing device has the feature according to the invention that the mixing arms of the first set of mixing arms extend along mixing arms of the second set of mixing arms into the second compartment. The mixing arms of the first set of mixing arms thus move between the mixing arms of the second set of mixing arms, which extend into and rotate in the second compartment alternately from the rotor bodies on opposite sides. This achieves a particularly powerful agitation of the second mixture, which enhances a homogenization and absorption into the mixture of, particularly, a powder-form second fluid for mixing. In a particular embodiment the mixing device is characterized here in that the mixing arms of the first set of mixing arms and the mixing arms of the second set of mixing arms maintain in the second compartment laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres. It has been found that this mutual distance results in a good mixing and effectively counteracts lump formation of powders.

[0010] In order to enhance a further homogenization of the mixture a preferred embodiment of the mixing device has the feature according to the invention that the mixing chamber is bounded at a second outer end by a second end wall, that a second set of stator arms extend from the second end wall and extend along mixing arms of the second set of mixing arms into the third compartment. The mixing arms thus move between the stator arms extending from the opposite side into the third compartment. A powerful agitation of the mixture is here also achieved hereby, this resulting in an optimal distribution of the different components in the final mixture. In a particular embodiment the mixing device is characterized here in that the second stator arms and the mixing arms of the second set of mixing arms maintain in the third compartment laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres. It has been found that this intermediate distance results in a highly homogeneous mixture.

[0011] In a further preferred embodiment the mixing device is characterized according to the invention in that the first rotor body is driveable by a first drive, particularly comprising a first electric motor, and that the second rotor body is driveable by a second drive, particularly comprising a second electric motor. Both rotor bodies thus have their own drive. This provides particularly the option of adapting a revolutions of the rotor bodies to the components to be mixed thereby. In this respect a further particular embodiment of the mixing device has the feature according to the invention that the first drive and the second drive impose independently of each other an optionally differing first and second number of revolutions on respectively the first rotor body and the second rotor body.

[0012] With a view to a fully continuous operation of a plastic processing machine line a further particular embodiment of the mixing device has the feature according to the invention that the outlet is in open communication with an inlet of driven receiving means, particularly a dosing screw, more particularly a double dosing screw, which receive the second mixture in dosed manner. Reception of the mixture is determined here by an intake by the driven transport means coupled to the outlet. These transport means, such as particularly a driven dosing screw, feed for instance an inlet of an extruding device or injection moulding device, which can thereby remain in fully continuous operation, always with fresh supply of a mixture from which a product is formed.

[0013] In order to enhance transport inside the mixing chamber a further particular embodiment of the mixing device has the feature here that the mixing chamber maintains an incline relative to the force of gravity, so that the cylinder axis inclines downward in a direction from the first compartment to the third compartment. Owing to such a configuration of the mixing device, transport from one to the next compartment in the mixing chamber is stimulated not only by the rotor bodies but also by gravitation.

[0014] Such a continuous process particularly provides the option of gradually adjusting a composition of the mixture, if desired, to optimal process parameters in a subsequent device which is fed directly or indirectly by the mixing device. With this in mind, a further particular embodiment of the mixing device has the feature that the first inlet is provided with first dosing means, particularly gravimetric ones, whereby the first fluid for mixing and the at least one further fluid are dosable, and that the second inlet is provided with second dosing means, particularly gravimetric ones, whereby the second fluid for mixing and optionally a further fluid are dosable. The mixing device thus provides the option of gradually adjusting the dosage of at least a number of the components for mixing in order to thereby adjust the composition of the finai mixture optimally to the operation of the installation fed thereby.

[0015] In a further particular embodiment the mixing device according to the invention is characterized here in that the first inlet is provided 'with a first mixing hopper in which the first fluid for mixing can be mixed with at least one of the at least one further fluid, and that the first dosing means feed the first mixing hopper with the first fluid for mixing and the at least one of the at least one further fluid. The first fluid for mixing is thus already premixed in the mixing hopper with at least one, and preferably each, of the at least one further fluid. This premixture is let into the first compartment of the mixing device and homogenized further therein. The tribological heat occurring therein results at least partially in a temperature increase in the mixture, which enhances adhesion of the further fluids to the first fluid.

[0016] In order to also enable inlet of the second fluid for mixing in dosed manner together with a further fluid a further preferred embodiment of the mixing device has the feature according to the invention that the second inlet is provided with a second mixing hopper in which the second fluid for mixing is mixable 'with the further fluid, and that the second dosing means feed the second mixing hopper with the second fluid for mixing and the further fluid. Similarly, the second fluid can thus be premixed with at least one further fluid and then be let jointly into the second compartment of the mixing device, in which a further homogenization in the first mixture takes place.

[0017] Although the mixing device according to the invention is widely applicable for various fluids, the device is eminently suitable for mixing of plastics. A specific embodiment of the mixing device is therefore characterized in that the first fluid for mixing comprises a plastic, particularly granules of a plastic, more particularly granules of a plastic from a group of polyvinyl chloride, polypropylene, polyethylene and polystyrene. A further particular embodiment of the mixing device has the feature here according to the invention that the at least one further fluid comprises one or more additives, particularly one or more additives from a group comprising stabilizers for thermal stabilization of the applied plastic, lubricants and pigments. The mixing device according to the invention is therefore suitable for granular fluids, particularly also for powders. In a specific embodiment the mixing device is therefore characterized in that the second fluid comprises a filler, particularly a powder, more particularly calcium carbonate powder, and / or granules of a plastic, particularly of a recycled plastic. Addition of such a filler helps reduce the proportion of a usually expensive plastic component in the mixture and thereby a raw material cost price of the product to be manufactured therefrom. This moreover reduces the carbon dioxide footprint of the material.

[0018] The invention will be further elucidated hereinbelow with reference to an exemplary embodiment and an accompanying drawing. In the drawing:

[0019] Figure 1 is a first perspective view of an exemplary embodiment of the mixing device according to the invention;

[0020] Figure 2 is a second perspective view of the mixing device of figure 1;

[0021] Figure 3 is a side view of the mixing device of figure 1; and

[0022] Figure 4 is a longitudinal section along the line Ill-Ill in figure 2 of the mixing device of figure 1. it is otherwise noted here that the figures are purely schematic and not all drawn to (the same) scale. Some dimensions in particular may be exaggerated to greater or lesser extent for the sake of clarity. Corresponding parts are designated in the figures with the same reference numeral. The mixing device of figure 1 comprises a steel mixing housing 15 which bounds with a cylinder wall 15 a cylindrical mixing chamber 20 around a cylinder axis Ill-ill. The mixing housing comprises at a first outer end a first end wall 11 and at an opposite outer end a second end wall 12, these together axially bounding the mixing chamber. The structural parts of the mixing device, such as the walls 1 1, 12, 15, are formed substantially from a robust, form-retaining material, such as high-grade stainless steel, although other dimensionally stable materials can also be applied for this purpose, such as for instance optionally preserved steel, aluminium or copper.

[0023] Mounted on the first end wall 1 1 is a first drive 30, comprising an electric motor 31 ■which is coupled via a right-angle transmission 33 to a first drive shaft 41, see figure 3. Similarly, the second end wall 12 carries a second drive 40 in the form of a second electric motor 32 'which is coupled via a right-angle transmission 34 to a second drive shaft 42, see figure 3. The right-angle couplings 33, 34 limit an overall length of the device in axial direction so that the whole remains relatively compact. If desired, use can however also be made of a straight drive line, 'wherein such right-angle transmissions 33, 34 can be dispensed with. In both cases a gear transmission can if desired be connected between the drive motor 31, 32 and the drive shaft 41, 42 driven thereby, this transmission providing for an optionally adjustable desired transmission ratio, particularly a delay, between an output motor shaft of the motor 31, 32 and the drive shaft 41, 42 driven thereby. The mixing housing 15 comprises at the position of a primary inlet a flange coupling 110 for placing of a first mixing hopper 100 which with an outlet is in open connection with the primary inlet. A first fluid for mixing is introduced into the mixing chamber via the mixing hopper 100. For this purpose the mixing hopper comprises a primary inlet 115 on an upper side thereof for receiving the first fluid for mixing. Provided laterally in the mixing hopper 100 is a set of secondary inlets 116, 117, 118 for lateral supply of one or more further fluids for mixing with the primary fluid. The inlets 110, 116, 117, 118 are preferably gravimetrically dosed, for instance in the manner as provided in European patent application EP 3.140.625, the content of which should be deemed as cited and included herein. In this case the first fluid comprises a flow of PVC granules, while desired additives, such as for instance a pigment, plasticizers and thermal stabilizers, can be mixed in via the lateral inlets 116, 117, 118. The thus combined mixture flows via the primary inlet 110 into the mixing chamber, see also figure 3.

[0024] Situated in the mixing chamber is a first rotor body 130 which is connected to the drive shaft 41 of the first drive 31. This rotor body 130 comprises centrally a disc body which almost connects all around against the cylindrical wall 15 of the mixing chamber and is set into rotation around the cylinder axis ill-ill by the first drive 31. A set of first mixing arms 131, 132 extends laterally from the first rotor body 130 on either side. Rotor body 130 thus separates a first compartment 151 and a second compartment 152 in mixing chamber 205 from each other, wherein the mixing members 131, 132 thereof protrude both into the first compartment 151 and into the second compartment 152 to act on the mixture. In the central disc body 130 one or more passages are provided outside of the plane of drawing, which aiiow material to move from the first compartment 151 to the second compartment 152. This is contributed to in that the mixing housing 15 maintains an incline relative to the direction of the force of gravity, see also figure 2, so that a cylinder axis C of mixing chamber 10 inclines downward from the first compartment 151 to the second compartment 152 and the intended material transport is aided by the force of gravity.

[0025] A first set of stator arms 111, which extends for this purpose from the first end wall 11, moreover protrudes into the first compartment. In the first compartment 151 the stator arms 111 and the mixing arms 131 maintain laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres. This example is in this respect based on an intermediate distance of on average about 8 millimetres. The friction imparted to the mixture thereby results in a heat development, whereby the temperature of the mixture increases to a level where an adequate adhesion of the one or more further fluids and the first fluid for mixing occurs. This temperature is in the order of between 100 and 120°C and can optionally be monitored 'with an internal temperature sensor.

[0026] A secondary inlet 120 with a corresponding flange coupling, which debouches directly into the second compartment 152, is also provided on mixing housing 15. A second mixing hopper 200 'with a main inlet 125 for a second fluid for mixing is mounted here. One or more further fluid can also be mixed in here, if desired. For this purpose the second mixing hopper is also provided with a set of lateral inlets 126, 127, 128. The inlets 120, 126, 127, 128 are preferably gravimetrically closed, for instance in the manner as provided in European patent application EP 3.140.625, the content of which should be deemed as cited and included herein. In this case the second fluid comprises calcium carbonate powder, which is thus added to the PVC mixture. The mixing arms 132, which extend from the first rotor body 130 and protrude into the second compartment 152, are flanked in second compartment 152 by a number of mixing arms 142 of a set of mixing arms extending from a second rotor body 140. This second rotor body 140 is connected to the drive shaft 42 which is driven by the second drive 32.

[0027] In the second compartment 152 the mixing arms 132 of the first rotor body 130 and the mixing arms 142 of the second rotor body 140 maintain laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres. This example is in this respect based on an intermediate distance of on average about 8 millimetres. The mixing arms 132, 142 act on the mixture immediately following the mixing in the first compartment 151. The mixture thereby requires no cooling in the interim but can be processed further immediately, wherein a content of calcium carbonate is added to the plastic as relatively inexpensive filler. It has been found in practice that, relative to the plastic, a fourfold of filler can thus be mixed in without being detrimental to a future thermoplastic processability of the mixture. Instead of calcium carbonate powder, recycled plastic (recyclate) or sawdust, as well as combinations thereof, can for instance also be used as second fluid for mixing, to serve as relatively inexpensive filler. The second rotor body 140 divides the mixing chamber 20 into the second compartment and a third compartment 153 and is simiiar to the first rotor body in respect of construction, but has its own, independent drive 32. A number of mixing arms 143 of the second rotor body 140 also protrudes into the third compartment 153 in order to act on the mixture there as well. A number of passages in the second rotor body 140 here also allow for material transport from one compartment 152 to the next compartment 153, likewise aided therein by the force of gravity. In the third compartment 153 the mixing arms 143 of the second rotor body 140 are flanked by a second set of stator arms 123, here extending from the second end wall 12. In the third compartment 153 the mixing arms 143 and the stator arms 123 maintain a mutual distance in the order of between 2 and 10 millimetres. The number of revolutions of the first drive 31 and the second drive 32 can be set independently of each other, adapted to the nature and fineness of the fluids for mixing so as to ultimately achieve an optimal mixing result.

[0028] In the third compartment 153 the mixing housing 15 comprises an outlet 150 with mounting flange where a receiving device in the form of a double displacing screw 300 is connected to mixing chamber 203. The displacing screw 300 is provided with a separate drive 35, in this case a frequency-controlled electric motor which imposes a controllable number of revolutions thereon. The receiving device thus determines a material flow rate and transport speed through the mixing chamber and also a dosing to a processing device connected downstream, such as for instance an extrusion or injection moulding machine, which is fed with the mixture in order to form a product therefrom at an increased temperature beyond a flow point of the mixture under pressure and with subsequent cooling via a suitable mould.

[0029] Although the invention has been further elucidated above with reference to only a single exemplary embodiment, it will be apparent that the invention is by no means limited thereto. On the contrary, many variations and embodiments are still possible within the scope of the invention for a person with ordinary skill in the art. Use is thus made in the example of PVC as primary component of the mixture for forming, but the invention is likewise applicable to other plastic fluids for mixing, such as for instance also polypropylene granules, polyethylene granules and polystyrene granules, and the mixing device can also be utilized for mixing in the food industry.

Claims

Claims:

1. Mixing device, comprising a mixing chamber with a first inlet for receiving at least a first fluid for mixing and with a driven agitator,, wherein the mixing chamber is bounded by a cylinder wall and the agitator comprises a first driven rotor body which extends transversely of the cylinder wall in the mixing chamber and is rotatable around a cylinder axis of the mixing chamber, wherein the first rotor body divides the mixing chamber into a first compartment and a second compartment, 'wherein the first rotor body comprises on either side a first set of mixing arms extending therefrom in axial direction into respectively the first compartment and the second compartment and acting in the first compartment on the first fluid and at least one further fluid for mixing during operation in order to mix the first fluid and the at least one further fluid for mixing together into a first mixture, and 'wherein the first rotor body comprises at least one passage which allows for transport of the first mixture from the first compartment to the second compartment, characterized in that the agitator comprises a second driven rotor body which extends transversely of the cylinder wall in the mixing chamber and is rotatable around the cylinder axis of the mixing chamber, wherein the second rotor body divides the mixing chamber into the second compartment and a third compartment, that the second compartment comprises a second inlet for receiving therein at least a second fluid for mixing, wherein the second rotor body comprises on either side a second set of mixing arms extending therefrom in axial direction into respectively the second compartment and the third compartment and acting in the second compartment on the first mixture and at least the second fluid formixing during operation in order to mix the first mixture and at least the second fluid for mixing together into a second mixture, wherein the second rotor body comprises at least one passage which allows transport of the second mixture from the second compartment to the third compartment, and that the third compartment comprises an outlet where the second mixture is receivable,2. Mixing device according to claim 1, characterized in that the mixing chamber is bounded at a first outer end by a first end wall, that a first set of stator arms extend from the first end wall and extend along mixing arms of the first set of mixing arms into the first compartment.

3. Mixing device according to claim 2, characterized in that the first stator arms and the mixing arms of the first set of mixing arms maintain in the first compartment laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres.

4. Mixing device according to one or more of the preceding claims, characterized in that the mixing arms of the first set of mixing arms extend along mixing arms of the second set of mixing arms into the second compartment.

5. Mixing device according to claim 4, characterized in that the mixing arms of the first set of mixing arms and the mixing arms of the second set of mixing arms maintainin the second compartment laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres.

6. Mixing device according to one or more of the preceding claims., characterized in that the mixing chamber is bounded at a second outer end by a second end wall, that a second set of stator arms extend from the second end wall and extend along mixing arms of the second set of mixing arms into the third compartment.

7. Mixing device according to claim 6, characterized in that the second stator arms and the mixing arms of the second set of mixing arms maintain in the third compartment laterally a mutual distance of at most 15 millimetres and preferably of between 2 and 10 millimetres.

8. Mixing device according to one or more of the preceding claims, characterized in that the first rotor body is driveable by a first drive, particularly comprising a first electric motor, and that the second rotor body is driveable by a second drive, particularly comprising a second electric motor.

9. M ixing device according to claim 8, characterized in that the first drive and the second drive impose independently of each other an optionally differing first and second number of revolutions on respectively the first rotor body and the second rotor body.

10. Mixing device according to one or more of the preceding claims, characterized in that the outlet is in open communication with an inlet of driven receiving means, particularly a dosing screw, more particularly a double dosing screw, which receive the second mixture in dosed manner.

11. Mixing device according to one or more of the preceding claims, characterized in that the mixing chamber maintains an incline relative to the force of gravity, so that the cylinder axis inclines downward in a direction from the first compartment to the third compartment.

12. Mixing device according to one or more of the preceding claims, characterized in that the first inlet is provided 'with first dosing means, particularly gravimetric ones, whereby the first fluid for mixing and the at least one further fluid are dosable, and that the second inlet is provided with second dosing means, particularly gravimetric ones, whereby the second fluid for mixing and optionally a further fluid are dosable.

13. Mixing device according to claim 12, characterized in that the first inlet is provided 'with a first mixing hopper in 'which the first fluid for mixing can be mixed with at least one of the at least one further f iu id, and that the first dosing means feed the first mixing hopper with the first fluid for mixing and the at least one of the at least one further fluid.

14. Mixing device according to claim 12 or 13, characterized in that the second inlet is provided with a second mixing hopper in which the second fluid for mixing is mixable with the further fluid, and that the second dosing means feed the second mixing hopper with the second fluid for mixing and the further fluid.

15. Mixing device according to one or more of the preceding claims, characterized in that the first fluid for mixing comprises a plastic, particularly granules of a plastic, more particularly granules of a plastic from a group of polyvinyl chloride, polypropylene, polyethylene and polystyrene.

16. Mixing device according to claim 15, characterized in that the at least one further fluid comprises one or more additives, particularly one or more additives from a group comprising stabilizers for thermal stabilization of the applied plastic, lubricants and pigments.

17. Mixing device according to claim 14 or 15, characterized in that the second fluid comprises a filler, particularly a powder, more particularly calcium carbonate powder, and / or granules of a plastic, particularly of a recycled plastic.

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