Method and device for changing the viscosity of a melt and filtering same

Abstract

The invention relates to a method and a device (1) for changing the viscosity of a melt, in particular a plastic melt, and filtering same. The device (1) comprises a first screw conveyor (3), a melt filter (4), a conveying device (2), and a granulation device (5). Gas-forming substances or a gas can be introduced into the first screw conveyor (3) by means of a supply device (7) such that the viscosity of the melt can be reduced so that a melt with a reduced viscosity can be provided to the melt filter (4), and the conveying device (2) has a transfer device (15) for introducing the filtered melt and a degassing device (16) for degassing the melt so that a melt with an increased viscosity can be provided to the granulation device (5).

Description

[0001] METHOD AND DEVICE FOR VISCOSITY CHANGE AND FILTRATION OF A MELT

[0002] The invention relates to a method and a device for changing the viscosity and filtering a melt.

[0003] It is well-known in the art that in plastics processing, and especially in plastics recycling, granules or plastic flakes are converted into a melt, which is then filtered and subsequently processed into granules to produce processed plastic granules. A filter device with a sieve with a specified mesh size can be used to filter the melt, with the melt being forced through the sieve by a conveyor screw. Depending on the temperature of the melt, a certain amount of energy is required for this process, which also depends, among other things, on the mesh size of the sieve in the filter device.

[0004] A disadvantage of known processes for filtering plastic melt is that sufficient throughput through a melt filter requires either high pressures or high melt temperatures, which must be provided to the melt filter by the upstream conveyor screw. Both high pressure and high melt temperatures pose a safety risk and can subject system components to unnecessary stress. Therefore, in addition to the required energy consumption, recurring maintenance and repair intervals are detrimental to the economical operation of such a device.

[0005] The object of the present invention was to overcome the disadvantages of the prior art and to provide a device and a method by means of which the energy consumption in the filtration of plastic melt can be reduced and at the same time the safety and economic efficiency of such a device are improved compared to known embodiments.

[0006] This object is achieved by a device and a method according to the claims.

[0007] The method according to the invention for changing the viscosity and filtering a melt comprises the method steps: - introducing gas-forming and / or outgassing substances or mixtures of substances or a gas into a granulate that can be converted into a melt in a first conveyor screw or into the first conveyor screw, wherein melt and / or granulate can be conveyed by means of the first conveyor screw, so that the viscosity of the melt is reduced by gas dissolved in the melt;

[0008] - filtering the melt with thus reduced viscosity by means of a melt filter, wherein the melt filter is arranged downstream of the first conveyor screw in a conveying direction of the melt;

[0009] - introducing the thus filtered melt into a conveying device downstream of the melt filter in the conveying direction of the melt, in particular into a second conveyor screw, wherein the filtered melt is introduced by means of a transfer device elongated in a first conveying direction of the conveying device and wherein the filtered melt is degassed by means of a degassing device elongated in the first conveying direction of the conveying device, so that the viscosity of the melt is increased by the outgassing of the gas dissolved in the melt

[0010] - Granulating the melt with thus increased viscosity by means of a granulation device;

[0011] In this context, granulate can be understood to mean, in particular, plastic granulate or granulate made of entraining agents or outgassing or gas-forming substances, whereby granulate is in any case a granular raw material.

[0012] In this context, reduced viscosity of the melt means that the viscosity of the melt has been reduced relative to its original state by the addition of gas or outgassing substances or mixtures of substances. This relative term was chosen because the method and the device described below cannot be restricted to individual definitive ranges of the viscosity of the melt, also with regard to possible different temperature and pressure ranges of the melt. This also applies with regard to the very different components of a melt, in particular a plastics melt, which can arise during the recycling of plastics or mixed plastics. The term “increased viscosity of the melt” used in this context is to be understood analogously. The gas-forming and / or outgassing substances or mixtures of substancesIn this context, mixtures of substances can include, for example, water, alcohols, entraining agents, alcoholic solutions, or granules impregnated or wetted with water, alcohols, entraining agents, or alcoholic solutions, in particular plastic granules or plastic flakes impregnated or wetted with them. A gas in this context is understood to mean, for example, water vapor, CO2, an inert gas, or another vaporized liquid.

[0013] In this context, a melt is understood to mean, in particular, a melt made of plastic or a plastic mixture, which is in any case flowable within certain limits and thus has a viscosity.

[0014] Application of the method according to the invention results in the advantage that the viscosity before passing through the melt filter is reduced by the gas absorbed therein, so that the resistance of the melt filter is reduced relative to the melt passing through it. This means that a plastic melt can, for example, be filtered at lower temperatures or the pressure applied to the melt filter can be reduced, while still enabling a constant throughput through the melt filter. As a result, less energy is required to provide the specified pressure upstream of the melt filter or the specified temperature upstream of the melt filter in order to ensure the same flow through the melt filter. Furthermore, this also protects the system components of a device for carrying out the method according to the invention and improves cost-effectiveness.

[0015] Furthermore, it can also be provided that the introduction of the melt into the conveying device is metered by means of a melt pump, so that a volumetric filling or filling of the conveying device is carried out. With this possible measure, the melt pump is therefore arranged downstream of the melt filter, as seen in the direction of melt flow. This allows for precise metering of the loading of the conveying device. Alternatively or additionally, it can also be provided that the melt pump or another melt pump is positioned upstream of the melt filter. This allows the resistance of the melt filter to be overcome in an improved manner and, subsequently, the loading or feeding of the conveying device to be metered.

[0016] Furthermore, the conveying device can be designed as a twin-screw conveyor or twin-screw extruder, wherein the melt is introduced into a first housing area, located closest to a first screw shaft, by means of the transfer device, and wherein the melt is degassed in a second housing area, located closest to a second screw shaft, by means of the degassing device. This makes it possible to simply and effectively prevent the melt introduced into the conveying device from being partially discharged again by the degassing device. This improves the degassing of the melt.

[0017] Furthermore, it can be provided that the gas-forming and / or outgassing substances or the gas are introduced into the first conveyor screw by means of a feed device elongated in a second conveying direction of the conveyor screw. This ensures the introduction of gas-forming substances or gas over the largest possible area, resulting in homogenization of the melt and thus further improved and efficient filtration.

[0018] The invention further relates to a device for changing the viscosity and filtering a melt, comprising, arranged downstream of one another in a conveying direction of the melt, a first conveyor screw for conveying melt or granules convertible to melt, a melt filter, a conveying device, in particular at least one second conveyor screw, and a granulation device,

[0019] - wherein gas-forming and / or outgassing substances or mixtures of substances or a gas can be introduced into the first conveyor screw by means of a feed device, so that the viscosity of the melt in the conveyor screw can be reduced by gas dissolved in the melt, so that melt with reduced viscosity can be provided to the melt filter.

[0020] The device is further characterized in that the conveying device has a transfer device, which is elongated in a first conveying direction of the conveying device, for introducing the filtered melt and a degassing device, which is elongated in the first conveying direction of the conveying device, for degassing the filtered melt, so that melt with increased viscosity can be provided to the granulation device.

[0021] The device has the advantage that the viscosity before passing through the melt filter is reduced by the gas absorbed therein, so that the resistance of the melt filter is reduced relative to the melt passing through it. This means that a plastic melt, for example, can be filtered at lower temperatures or the pressure applied to the melt filter can be reduced, while still allowing the same throughput through the melt filter. As a result, less energy is required to provide the specified pressure upstream of the melt filter or the specified temperature upstream of the melt filter in order to ensure the same flow through the melt filter, since the viscosity has already been reduced by the gas absorbed in the melt. Furthermore, this also protects the system components of the device and improves cost-effectiveness.

[0022] The transfer device can have a longitudinal extension relative to a mean diameter D of the conveying device from a range comprising 100% to 900%, in particular 200% to 700%, of the diameter D. This ensures that the outgassing of the melt is particularly effective because the melt can be spread out particularly thinly.

[0023] Furthermore, it may be expedient for the degassing device to be designed as a slot die, slot die, or strand die extending longitudinally along a housing of the conveying device, or for the degassing device to be designed as bores arranged in a row along the housing of the conveying device in the second conveying direction of the conveying device, so that the melt can be degassed to increase its viscosity. This enables degassing of the melt over a longitudinally extended area, providing an enlarged surface for degassing, thus enabling the most effective and complete degassing of the melt and thus the efficient increase in the viscosity of the melt.

[0024] According to a further development, it is possible for the conveying device to be designed as a twin-screw conveyor or twin-screw extruder with a housing, wherein the transfer device is formed in a first housing region closest to a first screw shaft, and wherein the degassing device is formed in a second housing region closest to a second screw shaft. This makes it possible to simply and effectively prevent the melt introduced into the conveying device from being partially discharged again by the degassing device. Thus, the degassing of the melt is improved.

[0025] Also advantageous is an embodiment according to which it can be provided that the first screw shaft is received in the housing in a first channel and that the second screw shaft is received in the housing in a second channel, wherein the first screw shaft and the second screw shaft are positioned so as to mesh with one another and the first channel and the second channel overlap in a meshing region of the screw shafts, wherein in an overlap region of the first channel and the second channel a housing section is formed which projects in the direction of the meshing region of the two screw shafts. This makes it possible to simply and effectively prevent the melt introduced into the conveying device from being partially discharged again by the degassing device. The degassing of the melt is thus further improved.

[0026] Furthermore, it can be provided that the feed device is designed as a slot die, slot die, or strand die extending longitudinally along a screw housing of the first conveyor screw, or that the feed device is designed as bores arranged in a row along the screw housing of the first conveyor screw in a second conveying direction of the conveyor screw, so that gas can be introduced into a first conveying channel of the first conveyor screw to reduce the viscosity of the melt. Thus, the introduction of gas-forming substances or gas is achieved over the largest possible area, which results in homogenization of the melt and thus further improved and efficient filtration.

[0027] Furthermore, the feed device can be designed as a feed hopper, wherein melt and / or granules convertible to melt and / or gas-forming and / or outgassing substances or mixtures of substances and / or gas can be introduced into the conveyor screw by means of the feed hopper. As a result, gas or a gas-forming substance can be introduced into the conveyor screw during the introduction of the granules convertible to melt or the plastic flakes convertible to melt, thereby improving the homogenization of the melt with the gas dissolved therein, which in turn leads to efficient filtration of the melt.

[0028] Furthermore, it may be expedient for the feed hopper to comprise a lock, in particular a pressure lock, and / or a gate valve or a cell lock, wherein gas can be introduced into the feed hopper and an excess pressure compared to ambient pressure can be maintained in the feed hopper by means of the lock. This makes it easy to dissolve more gas volume in the melt, whereby the viscosity of the melt can be further reduced in an efficient manner. Furthermore, it can be provided that the device further comprises a melt pump, wherein the melt pump is arranged downstream of the melt filter relative to the conveying direction or is formed between the melt filter and the conveying device, wherein the introduction of the melt into the conveying device can be metered by means of the melt pump, such that the conveying device can be fed with melt in a metered manner.With this possible measure, the melt pump is positioned downstream of the melt filter in the direction of melt flow. This allows for precise metering of the feed to the conveying device. Alternatively or additionally, the melt pump or another melt pump can be positioned upstream of the melt filter. This allows the resistance of the melt filter to be overcome in an improved manner and, subsequently, the feed to the conveying device can also be metered.

[0029] For a better understanding of the invention, it is explained in more detail using the following figures.

[0030] They show in a highly simplified, schematic representation:

[0031] Fig. 1 shows a possible first embodiment of a device for changing the viscosity and filtering a melt;

[0032] Fig. 2 shows a possible second embodiment of a device for changing the viscosity and filtering a melt;

[0033] Fig. 3 shows a cross section of the conveying device of the possible second embodiment of a device for changing the viscosity and filtering a melt.

[0034] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these positional information must be applied analogously to the new position in the event of a change in position.

[0035] Fig. 1 shows a possible first embodiment of a device 1 for changing the viscosity and filtering a melt in a highly simplified and schematic representation. Fig. 2 shows a further and possibly independent second embodiment of the device 1, wherein the same reference numerals or component designations as in the previous Fig. 1 are used for the same parts. The first embodiment of the device 1 and the second embodiment of the device 1 differ essentially in the design of a conveying device 2 of the device 1. For the sake of simplicity, the two embodiments of the device 1 are described together below, with specific differences being pointed out separately. In general, it can be provided that individual features of the respective embodiment can be combined with the other embodiment. Finally, Fig.3 a cross section of the conveying device 2 of the second possible embodiment of the device 1.

[0036] As shown in Fig. 1, the device 1 can comprise a conveyor screw 3 for conveying melt or granules convertible into melt, wherein, in this context, "melt" is understood to mean, in particular, plastic melt, and "granules" is preferably understood to mean plastic granules or plastic flakes. Furthermore, in addition to the aforementioned conveyor device 2, the device 1 can also comprise a melt filter 4 and a granulation device 5. The individual components of the device 1 can be arranged downstream of one another in the following order in a conveying direction 6 of the melt: conveyor screw 3, melt filter 4, conveyor device 2, granulation device 5.

[0037] The device 1 or in particular the conveyor screw 3 can comprise a feed device 7, wherein gas-forming and / or outgassing substances or a gas can be introduced into the first conveyor screw 3 by means of the feed device 7, so that the viscosity of the melt in the conveyor screw 3 can be reduced by gas dissolved in the melt. This makes it possible in a simple manner to provide the melt filter 4 with melt with reduced viscosity, so that more throughput through the melt filter 4 can be achieved with the same energy expenditure or finer filtration with the same energy expenditure compared to filtering a melt with non-reduced viscosity. The feed device 7 can, as shown in Figs. 1 and 22, be designed as a feed hopper 8, wherein melt and / or granules convertible to melt and / or gas-forming and / or outgassing substances and / or gas can be introduced into the conveyor screw 3 by means of the feed hopper 8. Furthermore, in this context, it can also be provided that the feed hopper 8 comprises a lock 9, in particular a pressure lock, and / or a gate valve 10 or a cell lock, wherein gas can be introduced into the feed hopper 8 and an overpressure compared to an ambient pressure can be maintained in the feed hopper 8 by means of the lock 9.

[0038] Alternatively, however, it can also be provided that the feed device 7 is designed as a slot die, slot die, or strand die extending longitudinally along a screw housing 11 of the first conveyor screw 3, or that the feed device 7 is designed as bores arranged in a row along the screw housing 11 of the first conveyor screw 3 in a second conveying direction 12 of the conveyor screw 3, so that gas can be introduced into a first conveying channel 13 of the first conveyor screw 3 to reduce the viscosity of the melt. This alternative embodiment of the feed device 7 is not shown.

[0039] Furthermore, it can be provided that the conveying device 2 has a transfer device 15, which extends longitudinally in a first conveying direction 14 of the conveying device 2, for introducing the filtered melt, and a degassing device 16, which extends longitudinally in the first conveying direction 14 of the conveying device 2, for degassing the melt, so that melt with an increased viscosity can be provided to the granulation device 5. Thus, the filtering of the melt is initially promoted by reducing the viscosity, in order to then degas the melt again after filtering the melt and thus increase the viscosity of the melt again or to provide the viscosity of the melt back to the original viscosity.By degassing the melt, undesirable substances or contaminants can also be removed from the melt, provided that a suitable gas or carrier substance or carrier gas has been selected.

[0040] It can also be provided that the degassing device 16 is designed as a slot die, slot die or strand die that is elongated along a housing 17 of the conveying device 2 in the first conveying direction 14 or that the degassing device 16 is designed as bores that are lined up along the housing 17 of the conveying device 2 in the first conveying direction 14, so that the melt can be degassed to increase the viscosity of the melt.

[0041] As shown in Fig. 2, in the second possible embodiment of the device 1, it can be provided that the conveying device 2 is designed as a double conveyor screw 18 or twin-screw extruder with a housing 17, wherein the transfer device 15 is designed in a first housing region 20 closest to a first screw shaft 19 and wherein the degassing device 16 is designed in a second housing region 22 closest to a second screw shaft 21.

[0042] As can be seen from a combination of Fig. 2 and Fig. 3, it can also be provided that the first worm shaft 19 is received in the housing 17 in a first channel 23 and that the second worm shaft 21 is received in the housing 17 in a second channel 24, wherein the first worm shaft 19 and the second worm shaft 21 are positioned so as to mesh with one another and the first channel 23 and the second channel 24 overlap in a meshing area 25 of the worm shafts 19 and 21, wherein in an overlap area 26 of the first channel 23 and the second channel 24 a housing section 27 protruding in the direction of the meshing area 25 of the two worm shafts 19 and 21 is formed. Since the transfer device 15 is formed in the first housing area 20 and the degassing device 16 in the second housing area 22, the projecting housing section 27 orThe housing section 27 projecting into the overlapping region 26 largely prevents melt introduced into the first channel 23 by the transfer device 15 from flowing into the degassing device 16 or being discharged through it.

[0043] The device 1 is further configured to implement the method according to the invention. The method serves to change the viscosity and filter the melt and comprises the following process steps:

[0044] - Introducing gas-forming and / or outgassing substances or a gas into a granulate that can be converted into a melt in the first conveyor screw 3 or into the first conveyor screw 3, wherein melt and / or granulate can be conveyed by means of the first conveyor screw 3, so that the viscosity of the melt is reduced by gas dissolved in the melt;

[0045] - filtering the melt by means of the melt filter 4, wherein the melt filter 4 is arranged downstream of the first conveyor screw 3 in the conveying direction 6 of the melt;

[0046] - introducing the melt into the conveying device 2 downstream of the melt filter 4 in the conveying direction 6 of the melt, wherein the melt is introduced by means of the transfer device 15 which is elongated in the first conveying direction 14 of the conveying device 2 and wherein the melt is degassed by means of the degassing device 16 which is elongated in the first conveying direction 14 of the conveying device 2, so that the viscosity of the melt is increased by the outgassing of the gas dissolved in the melt;

[0047] - Granulating the melt using the granulation device 5.

[0048] As already explained above, with regard to the method, it can also be provided that the gas-forming and / or outgassing substances or the gas are introduced into the first conveyor screw 3 by means of the feed device 7 which is elongated in the second conveying direction 12 of the conveyor screw 3.

[0049] With reference to Fig. 2, with regard to the second possible embodiment of the device 1, it can also be provided that the conveying device 2 is designed as a double conveyor screw 18 or double-screw extruder, wherein the melt is introduced into the first housing area 20 closest to the first screw shaft 19 by means of the transfer device 15 and wherein the melt is degassed in the second housing area 22 closest to the second screw shaft 21 by means of the degassing device 16.

[0050] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with each other are also possible and this possibility of variation lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action by means of the objective invention.

[0051] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0052] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0053] For the sake of clarity, it should finally be pointed out that, in order to better understand the structure, some elements have been shown out of scale and / or enlarged and / or reduced in size.

[0054] Reference symbol list

[0055] device

[0056] Conveyor device Conveyor screw Melt filter

[0057] Granulation s - device conveying direction

[0058] Feeding device feed hopper

[0059] sluice

[0060] gate valve

[0061] S crew housing Second conveying direction First conveying channel

[0062] First conveying direction Transfer device Degassing device Housing

[0063] Double screw conveyor First screw shaft First housing section Second screw shaft Second housing section First channel

[0064] Second channel

[0065] Combing area Overlapping area Casing section

Claims

Patent claims 1. Process for changing the viscosity and filtering a melt, comprising the process steps: - introducing gas-forming substances or a gas into a granulate which can be converted into a melt in a first conveyor screw (3) or into the first conveyor screw (3), wherein the melt and granulate can be conveyed by means of the first conveyor screw (3), so that the viscosity of the melt is reduced by gas dissolved in the melt; - filtering the melt by means of a melt filter (4), wherein the melt filter (4) is arranged downstream of the first conveyor screw (3) in a conveying direction (6) of the melt; - Granulating the melt; characterized in that the process further comprises the following process steps: - introducing the melt into a conveying device (2) downstream of the melt filter (4) in the conveying direction (6) of the melt, wherein the melt is introduced by means of a transfer device (15) which is elongated in a first conveying direction (14) of the conveying device (2) and wherein the melt is degassed by means of a degassing device (16) which is elongated in the first conveying direction (14) of the conveying device (2), so that the viscosity of the melt is increased by the outgassing of the gas dissolved in the melt.

2. Method according to claim 1, characterized in that the introduction of the melt into the conveying device (2) is metered by means of a melt pump, so that a volumetric filling or filling or feeding of the conveying device (2) is carried out.

3. Method according to one of the preceding claims, characterized in that the conveying device (2) is designed as a double conveyor screw (18) or double-screw extruder, wherein the melt is introduced into a first housing area (20) closest to a first screw shaft (19) by means of the transfer device (15) and wherein the melt is degassed in a second housing area (22) closest to a second screw shaft (21) by means of the degassing device (16).

4. Method according to one of the preceding claims, characterized in that the gas-forming and / or outgassing substances or the gas is introduced into the first conveyor screw (3) by means of a feed device (7) which is elongated in a second conveying direction (12) of the conveyor screw (3).

5. Device (1) for changing the viscosity and filtering a melt, comprising, arranged downstream of one another in a conveying direction (6) of the melt, a first conveyor screw (3) for conveying melt or granules convertible into melt, a melt filter (4), a conveying device (2) and a granulating device (5), - wherein gas-forming substances or a gas can be introduced into the first conveyor screw (3) by means of a feed device (7), so that the viscosity of the melt in the conveyor screw (3) can be reduced by gas dissolved in the melt, so that melt with reduced viscosity can be provided to the melt filter (4), characterized in that the conveyor device (2) has a transfer device (15) which is elongated in a first conveying direction (14) of the conveyor device (2) for introducing the filtered melt and a degassing device (16) which is elongated in the first conveying direction (14) of the conveyor device (2) for degassing the melt, so that melt with increased viscosity can be provided to the granulation device (5).

6. Device (1) according to claim 5, characterized in that the degassing device (16) is designed as a slot die, slot die or strand die extending longitudinally along a housing (17) of the conveying device (2) or that the degassing device (16) is designed as bores arranged in a row along the housing (17) of the conveying device (2) in the first conveying direction (14), so that the melt can be degassed to increase the viscosity.

7. Device (1) according to claim 5 or 6, characterized in that the conveying device (2) is designed as a double conveyor screw (18) or twin-screw extruder with a housing (17), wherein the transfer device (15) is designed in a first housing area (20) closest to a first screw shaft (19) and wherein the degassing device (16) is formed in a second housing region (22) closest to a second screw shaft (21).

8. Device (1) according to claim 7, characterized in that the first worm shaft (19) is received in the housing (17) in a first channel (23) and that the second worm shaft (21) is received in the housing (17) in a second channel (24), wherein the first worm shaft (19) and the second worm shaft (21) are positioned so as to mesh with one another and the first channel (23) and the second channel (24) overlap in a meshing region (25) of the worm shafts (19, 21), wherein in an overlapping region (26) of the first channel (23) and the second channel (24) a housing section (27) protruding in the direction of the meshing region (25) of the two worm shafts (19, 21) is formed.

9. Device (1) according to one of claims 5 or 8, characterized in that the feed device (7) is designed as a slot die, slot die or strand die extending longitudinally along a screw housing (11) of the first conveyor screw (3), or in that the feed device (7) is designed as bores arranged one after the other along the screw housing (11) of the first conveyor screw (3) in a second conveying direction (12) of the conveyor screw (3), so that gas can be introduced into a first conveying channel (13) of the first conveyor screw (3) to reduce the viscosity of the melt.

10. Device (1) according to one of claims 5 to 9, characterized in that the feed device (7) is designed as a feed hopper (8), wherein by means of the feed hopper (8) melt and / or granulate convertible to melt and / or gas-forming and / or outgassing substances and / or gas can be introduced into the conveyor screw (3).

11. Device (1) according to claim 10, characterized in that the feed hopper (8) comprises a lock (9), in particular a pressure lock, and / or a gate valve (10) or a cell lock, wherein gas can be introduced into the feed hopper (8) and an overpressure relative to an ambient pressure can be maintained in the feed hopper (8) by means of the lock (9).

12. Device (1) according to one of claims 5 to 11, characterized in that the device (1) further comprises a melt pump.

13. Device (1) according to claim 12, characterized in that the melt pump is arranged downstream of the melt filter (4) relative to the conveying direction (14) or is formed between the melt filter (4) and the conveying device (2), wherein the introduction of the melt into the conveying device (2) can be metered by means of the melt pump, so that the conveying device (2) can be fed with melt in a metered manner.

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