Method and device for producing a dry film

Abstract

The invention relates to a method for producing a dry film (4) from dry film material (6), wherein a solvent-free dry film material (6) for the formation of the dry film (4) is conveyed into a roller gap (16) formed between a first roller (12) and a second roller (14), wherein the formed dry film (4) is cut to size, and wherein leftover material (48) from the forming of the dry film and / or the cutting to size of the dry film (4) is supplied to a device (8) for producing the solvent-free dry film material (6). The invention also relates to a device (2) for carrying out the method.

Description

[0001] Description

[0002] Method and device for producing a dry film

[0003] The invention relates to a device and a method for producing a dry film from solvent-free dry film material.

[0004] To produce a dry film, as known, for example, from WO 2018 / 210723 A1, a dry film material is conveyed between two rollers of a roller device using a powder conveyor. These rollers apply compressive and / or shear forces to the dry film material, forming the dry film.

[0005] The dry film is conveniently trimmed along its side edges to ensure sufficiently high film edge quality. The trimmed coating edge is typically disposed of as waste.

[0006] The invention is based on the object of providing a particularly suitable method and / or a particularly suitable device for producing a dry film. In particular, the formation of unused material waste should be avoided as far as possible.

[0007] With regard to the method, the object is achieved according to the invention by the features of claim 1. With regard to the device, the object is achieved according to the invention by the features of claim 6. Advantageous embodiments and further developments are the subject of the dependent claims. The statements made in connection with the device also apply mutatis mutandis to the method, and vice versa.

[0008] The process serves to produce a dry film. The resulting dry film is expediently used as a layer, in particular as a layer containing active material, for an anode or cathode of a lithium-ion battery. For this purpose, the dry film is applied to a substrate.

[0009] According to the process, in a first step to form the dry film, solvent-free

[0010] Dry film material is conveyed into a nip formed between a first roller and a second roller. A pressing and / or shearing force is applied to the dry film material by the first and second rollers, causing the particles of the dry film material to bond together and / or the dry film to adhere to one of the two rollers.

[0011] For example, the first and second rollers have different rotational speeds, i.e., different rotational speeds. This facilitates roller-supported further conveyance of the dry film, especially on the roller with the higher rotational speed.

[0012] For example, additional rollers and / or pairs of rollers are provided to compact and / or convey the dry film formed.

[0013] The dry film material is expediently a granular material, also referred to as granulate, for example a powder or a powder mixture. The dry film material suitably comprises a (dry) active material, a (dry) binder, and / or a (dry) conductive agent. In other words, the dry film material comprises a mixture of undissolved active material particles, undissolved binder particles, and / or undissolved conductive agent particles.

[0014] In a second step of the method, the dry film formed in the roll gap is cut to size. In particular, the dry film is cut off at its edge regions. In other words, the ends of the dry film are cut off in or against a direction, also referred to below as the axial direction, along the axes of the first and second rolls. This results in a straight edge of the dry film and / or an edge with a uniform thickness in the longitudinal direction of the dry film and / or a dry film with a predetermined, in particular constant, width (extension in the axial direction). Additionally or alternatively, any area of ​​the dry film that does not meet a predetermined criterion is cut off during cutting. Such an area is also referred to as a "not OK area" or "not OK area".For example, a minimum requirement for dry film homogeneity and / or a maximum dry film thickness variation are used as criteria. Such a "not-good" range arises, for example, during the start-up of the manufacturing process.

[0015] In a further, third step of the process, material residues from the formation of the dry film and / or the cutting of the dry film are fed, in particular automatically, to a device for producing the solvent-free dry film material. Material residues from the formation of the dry film are in particular dry film material, i.e. powder or granules, which were conveyed into the roller gap but were not processed into the dry film by the rollers, for example because they were removed as excess powder from the dry film material template, in particular by a doctor blade. Material residues from the cutting of the dry film are in particular the cut-off edge regions, in other words the edge trim of the dry film, and / or a not-good region cut off from the dry film.

[0016] In summary, the material residues generated during the production of the dry film are recycled, particularly directly, into the dry film material production process. The material residues are thus returned to the facility for producing the dry film material, and the dry film material, which thus at least partially contains the recycled material residues, is expediently processed into the dry film. This particularly advantageously avoids or at least reduces the formation of unused material waste.

[0017] Here and in the following, the facility for producing the dry film material is also referred to as the production facility.

[0018] According to an expedient development of the method, the feed rate of the material residues to the device for producing the solvent-free dry film material is and / or will be adjusted. For example, the feed rate is adjusted or regulated such that the feed rate remains constant over time. The feed rate is understood to mean the quantity of material residues per unit of time.

[0019] Preferably, the rate is adjusted such that the proportion of dry film material produced from the recycled material residue corresponds to a predetermined target proportion of the total amount of dry film material produced by the production device. For example, the feed rate is adjusted such that this proportion of dry film material from the material residue is between 0.1% and 50%.

[0020] In a suitable embodiment of the process, the material residues are fed to an extruder, in particular a twin-screw extruder, of the production facility. The extruder serves, in particular, to pretreat the feedstock material and / or to activate a binder of the feedstock material. According to this embodiment, the material residues and preferably additional feedstock material, in particular a powdered mixture of the binder, the conductive agent, and the active material, are fed to the extruder.

[0021] Alternatively or additionally, the material residues are fed to a finishing unit of the production facility according to a suitable embodiment. The finishing unit (finishing device) serves in particular to deagglomerate the material fed to it and / or, preferably according to a predetermined particle or granule size of the dry film material, to reduce it, in particular to cut it and / or grind it. The extrudate is expediently comminuted and then fed to the finishing device. In this case, the material residues are preferably fed to the finishing unit together with the, in particular comminuted, extrudate.

[0022] In summary, the production facility preferably comprises an extruder for pretreating the starting material fed to the extruder, as well as a finishing unit that finishes, in particular reduces the size of, the extrudate, in particular the dried and pre-cut extrudate. This allows the material residues from the formation of the dry film and / or the cutting of the dry film to be fed to the extruder and / or the finishing unit, so that dry film material for the formation of the dry film can be produced from them again.

[0023] According to a suitable embodiment, the material residues are crushed before being fed to the production device. This facilitates mixing of the material residues and the extrudate in the finishing device, or of the material residues and the starting material, particularly in powder form, in the extruder.

[0024] For example, the material residues, possibly shredded, are stored before being fed to the production facility. Preferably, however, the material residues are fed directly to the production facility, i.e., without external intermediate storage.

[0025] A further aspect of the invention relates to a device for producing a dry film from (solvent-free) dry film material. The device is intended and configured to carry out the method in one of the variants described above. For this purpose, the device has the device for producing the dry film material. The device further comprises a device for forming the dry film from the dry film material, wherein this device comprises the first and second rollers, and wherein the roller gap is formed between the first and second rollers.

[0026] The device expediently comprises a conveying device which serves to convey the dry film material into the roller gap.

[0027] The device further comprises a cutting device for cutting the dry film formed by the rollers, in particular for cutting off the lateral edges of the dry film, i.e. for trimming the dry film with a cutting edge perpendicular to the axial direction. For example, the cutting device for this purpose comprises a squeegee or roller knife. In particular, the dry film is cut on one of the rollers using the squeegee or roller knife. Expediently, the device further comprises a cutting and / or removal device, which comprises, for example, a scraper or a doctor blade. In this way, the not-good regions, in particular, can be cut off and removed from the dry film using the cutting and / or removal device.

[0028] Furthermore, the device comprises a return device (feed device) for, preferably automatically, feeding the material residues from the formation of the dry film and / or from the cutting of the dry film to the production device. The return device thus serves, in particular, to return powder or granulate residues from the dry film production and / or the edge trimming and / or the cut-off non-conforming areas to the production device.

[0029] As explained in connection with the method, it is advantageously possible with such a device to reuse the material residues for the production of the dry film material, so that the formation of unused material waste is avoided or at least reduced.

[0030] According to a suitable embodiment, the return device comprises a comminution unit for comminuting the material residues. For example, the comminution unit comprises a cutting unit and / or a grinding unit.

[0031] As already described in connection with the method, according to an expedient embodiment, the production facility comprises the finishing unit and / or the extruder. The material residues can be fed to the extruder and / or the finishing unit using the return device. Thus, the return device is designed such that, when the return device is in operation, the material residues are fed to the extruder and / or the finishing unit.

[0032] In a suitable embodiment, the return device is configured for pneumatically conveying the material residues. The return device thus includes a suction system for removing the material residues from the device for forming the dry film and / or for conveying the material residues to the production device.

[0033] As an alternative to pneumatic conveying of the material residues, the return device includes a collecting container for the material residues. Preferably, the material residues are collected in the collecting container and then fed to the production facility. In summary, the material residues are fed to the production facility in batches.

[0034] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In the drawings:

[0035] Fig. 1 schematically shows an apparatus for producing a dry film from dry film material, the apparatus comprising a device for producing the dry film material and a device for forming the dry film from the dry film material,

[0036] Fig. 2 shows schematically in a side view the device for forming the dry film from the dry film material, which comprises a pair of rollers by means of which the dry film material is processed into the dry film,

[0037] Fig. 3 schematically shows in a plan view on the underside the device for forming the dry film from the dry film material, and

[0038] Fig. 4 shows a flow chart of a process for producing the dry film from the dry film material.

[0039] Corresponding parts and sizes are always provided with the same reference numerals in all figures. Figure 1 schematically shows a device 2 for producing a dry film 4 from dry film material 6, in particular powder or granular form. The device 2 comprises a (production) device 8 for producing the dry film material 6.

[0040] The dry film material 6 produced by the production device 8 is fed to a device 10 for forming the dry film 4. The device 10 for forming the dry film 4 is shown in more detail in Figures 2 and 3. This comprises a first pair of rollers with a first roller 12 and a second roller 14, wherein a (first) roller nip 16 is formed between the first and second rollers 14. The device 2 further comprises a conveyor device 18, which is shown schematically in Figure 2 and is designed, for example, as a material conveyor that particularly comprises a hopper. The conveyor device 18 is designed to convey the dry film material 6 produced by the production device 8 into the first roller nip 16, where it is processed into the (first) dry film 4 by the first and second rollers 12, 14.

[0041] As can also be seen in Figures 2 and 3, the device 10 for forming the dry film 4 comprises a second pair of rollers with a third roller 20 and a fourth roller 22. The axes A of the rollers 12, 14, 20 and 22 are preferably arranged parallel to one another and in a common plane, and a (second) roller nip 24 is formed between the third roller 20 and the fourth roller 22. A further conveyor device 18 is provided for conveying dry film material 6, in particular dry film material 6 produced by the production device 8, into the second roller nip 24, where it is processed into a second dry film 26 by the third roller 20 and the fourth roller 22.

[0042] The first dry film 4 is conveyed, supported by the second roller 14, into a third roller nip 28 formed between the second roller 14 and the third roller 20 adjacent thereto. In addition, the second dry film 26 is conveyed, supported by the third roller 20, into the third roller nip 28. A feed device 30 of the device 2, shown here as a guide roller by way of example, is configured to feed a substrate 32, in particular a film-like substrate, into the third roller nip 28 between the first dry film 4 and the second dry film 26. In the third roller nip 28, the first dry film 4 and the second dry film 26 are laminated onto the substrate 32 to form an electrode 34.

[0043] The device 10 further comprises crushing knives as a cutting device 36. Two of the crushing knives are arranged on the second roller 14 such that they are spaced apart in the axial direction, i.e., in a direction parallel to the axis A of the second roller, and laterally cut the dry film supported on the second roller 14. The edge trim 38 formed in this way is indicated in Fig. 3 by a dashed line.

[0044] Analogously, two further crushing blades of the cutting device 36 are arranged on the third roller 20 such that they are spaced apart in the axial direction, i.e., in a direction parallel to the axis A of the second roller 20, and that they laterally cut the second dry film 26 supported on the third roller 20. The edge trim 38 formed in this way is also indicated in Fig. 3 by a dashed line.

[0045] Doctor blades 40 of device 10 are provided for removing the respective edge trim 38 from the second roller 14 or from the third roller 20. For this purpose, the doctor blades 40 are arranged between the respective squeezing blade and the third roller gap 28 with respect to the direction of rotation shown by arrows in Fig. 2.

[0046] The device further comprises a doctor blade 42 for the second roller 14 and for the third roller 20. These serve to remove and / or cut off a region of the dry film 4 from the second roller 14 or a region of the second dry film 26 from the third roller 20 that does not meet a specified quality criterion. Such a region, also referred to as a "non-conforming region," arises particularly when the device 10 starts up to form the dry film 4.

[0047] In the area of ​​the doctor blades 40, 42, a suction device 44 of a return device 46 of the device 2 is arranged. In other words, the return device 46 is provided and configured to remove the material residues 48 from the cutting of the dry film or the second dry film 26 from the device 10. Thus, the return device 46 is configured to absorb the edge trimmings and / or the "non-conforming area" of the dry film 4 and / or the second dry film 26 as material residues 46.

[0048] According to an alternative not shown in detail, a collecting container for the material residues 48 is arranged in the area of ​​each of the doctor blades 40, 42.

[0049] During the production of the dry film 4, the dry film material 6, which is particularly solvent-free, is conveyed, in particular poured, into the roller gap 16. This accumulates in the roller gap 16 before its narrowest point. Thus, a material backlog forms in the roller gap 16. In the edge region of this so-called dry film material supply, i.e., at its axial ends, a further suction device 44 of the return device (or, according to a variant not shown in detail, a collecting container) is arranged, which removes excess dry film material 6 from the device 10.

[0050] In summary, the device 2 comprises the return device 46, by means of which the material residues from the cutting process and / or the excess dry film material 6 are removed from the device 10 as material residues 48 from the formation of the dry film 4 and fed (returned) to the production device 8. The material residues 48 are conveyed pneumatically.

[0051] Optionally, the return device 46 comprises a cutting unit or a grinding unit as a comminution unit 50, by means of which the material residues 48 can be comminuted. If appropriate, the return unit is provided and configured to feed the possibly comminuted material residues 48 to the production device 8.

[0052] As can be seen in Fig. 1, the production device comprises an extruder 52, which is designed in particular as a twin-screw extruder, and a finishing unit 58.

[0053] The extruder 52 is provided and configured to pretreat a mixture 54, in particular a powdered mixture, of a binder, an active material, and a conductive agent as a starting material, and / or to activate the binder and process it into an extrudate 56. For example, the preferably comminuted material residues 48 are additionally fed to the extruder 52 at the inlet side as starting material. Thus, in this case, the mixture 54 and the material residues 48 are mixed by the extruder 52 and processed into the extrudate 56.

[0054] The extrudate 56 is preferably cured, in particular cooled, and / or comminuted. If necessary, the extrudate 56 is fed to the finishing unit 58. This serves to further reduce and / or grind the possibly cooled and comminuted extrudate 56 to form the dry film material 6. For example, in addition to the extrudate 56, the material residues 48 are fed to the finishing unit 58 and comminuted using these. In this case, both the extrudate and the material residues 48 are comminuted by the finishing unit 58 to form the dry film material 6. For example, a portion of the material residues 48 is fed to the extruder 52 and the remaining material residues 48 is fed to the finishing unit 58. Preferably, the material residues 48 are fed only to the extruder 52 or the finishing unit 58. In summary, the material residues 48 can be fed to the extruder 52 and / or the finishing unit 58 using the return device 46.

[0055] In further summary, the material residues are recycled due to their return from the device 10 for forming the dry film 4 to the production device 8. Thus, the formation of unused material waste is avoided or at least reduced by the material residues 48.

[0056] In Fig. 4, a method for producing the dry film 4 by means of the device 2 is shown using a flow chart.

[0057] In a first step I, the solvent-free dry film material 6, produced in particular by the production device 8, is conveyed into the (first) roller gap 16 formed between the first roller 12 and the second roller 14. There, the dry film material 6 is processed into the (first) dry film 4 by the two rollers 12, 14.

[0058] Optionally, solvent-free dry film material 6, preferably also produced using the production device 8, is conveyed in an analogous manner into the (second) nip 24 formed between the third roller 20 and the fourth roller 22. There, the dry film material 6 is processed into the (second) dry film 26 using the two rollers 20, 22. Further optionally, the dry film 4 and the second dry film 26 are conveyed into the third nip 28, where the dry film 4 and the second dry film 26 are each laminated to one side of the substrate 32.

[0059] In a subsequent second step II, the first dry film 4 and, if applicable, the second dry film 26 are cut using the cutting device 36. In this process, the side edges of the first dry film 4 and the second dry film 4 are cut off.

[0060] In a third step III, the material residues 48 from the formation of the first dry film 4 and / or the cutting of the first dry film 4 and, if applicable, the material residues 48 from the formation of the second dry film 26 and / or the cutting of the second dry film 26 are removed from the device 10 for forming the dry film 4 using the return device 46. Optionally, the material residues 48 are comminuted. The material residues 48, or the comminuted material residues 48, are then fed to the production device 8, i.e., the device 8 for producing the solvent-free dry film material 6, using the return device 46.

[0061] Here, the material residues 48 are fed to the finishing unit 58 and / or the extruder 52 of the production facility HE. Optionally and preferably, the material residues 48 are fed to the extruder 52 or the finishing unit 58 in such a way that the feed rate of the material residues is adjusted. The rate is expediently adjusted or regulated according to a target rate.

[0062] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can be derived from them by those skilled in the art within the scope of the claims without departing from the subject matter of the invention. In particular, all individual features described in connection with the exemplary embodiments and / or in the claims can also be combined with one another in other ways without departing from the subject matter of the invention.

[0063] List of reference symbols

[0064] device

[0065] dry film

[0066] Dry film material

[0067] Dry film material production facility / production facility

[0068] Device for forming the dry film

[0069] First roller

[0070] Second roller

[0071] (first) roll gap

[0072] conveyor system

[0073] Third roller

[0074] Fourth reel

[0075] (second) nip second dry film

[0076] (third) nip

[0077] Feed device

[0078] Substrat

[0079] electrode

[0080] Cutting device / roller knife

[0081] Edge trimming

[0082] Squeegee

[0083] Squeegee

[0084] Extraction

[0085] Return device 48 material residue

[0086] 50 shredding unit

[0087] 52 extruders

[0088] 54 Mixture

[0089] 56 Extrudate

[0090] 58 finishing unit

[0091] A axis of the roller

[0092] I Formation of the dry film from dry film material

[0093] II Cutting the dry film

[0094] III Supply of material residues to the manufacturing facility

Claims

Patent claims 1. A method for producing a dry film (4) from dry film material (6), - wherein, to form the dry film (4), solvent-free dry film material (6) is conveyed into a nip (16) formed between a first roller (12) and a second roller (14), - wherein the formed dry film (4) is cut to size, and - wherein material residues (48) from the formation of the dry film (4) and / or the cutting of the dry film (4) are fed to a device (8) for producing the solvent-free dry film material (6).

2. Method according to claim 1, characterized in that the rate of supply of the material residues (48) to the device (8) is and / or is set, in particular constant over time.

3. Method according to claim 1 or 2, characterized in that the material residues (48) are fed to a finishing unit (58) of the device (8) for producing the solvent-free dry film material (6).

4. Method according to one of claims 1 to 3, characterized in that the material residues (48) are fed to an extruder (52) of the device (8) for producing the solvent-free dry film material (6).

5. Method according to one of claims 1 to 4, characterized in that the material residues (48) are crushed before being fed to the device (8).

6. Device (2) for producing a dry film (4) from dry film material (6) according to the method according to one of claims 1 to 5, comprising - a device (8) for producing the dry film material (6), - a first roller (12) and a second roller (14), wherein a roller gap (16) is formed between the first roller (12) and the second roller (14) for forming the dry film (4), - a cutting device (36) for cutting the formed dry film (4), and - a return device (46) for feeding material residues (48) from the formation of the dry film (4) and / or from cutting the dry film (4) to the device (8) for producing the dry film material (6).

7. Device (2) according to claim 6, characterized in that the return device (46) has a comminution unit (50) for comminuting the material residues.

8. Device (2) according to claim 6 or 7, characterized in that the device (8) for producing the dry film material (6) comprises an extruder (52) and / or a finishing unit (58), wherein the material residues (48) can be fed to the extruder (52) and / or the finishing unit (58) by means of the return device (46).

9. Device (2) according to one of claims 6 to 8, characterized in that the return device (46) is designed for pneumatic conveyance of the material residues (48).

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