METHOD FOR PRODUCING A COATED, TENSION-FREE SUBSTRATE

Abstract

The invention relates to a method for producing a substrate coated with a paste or dry coating, the method comprising: providing a film; providing a paste/dry coating; coating the film with the paste in order to obtain a coated substrate; and drying the paste or solidifying the dry coating on the substrate, the substrate being transported in a transport direction between its provision and the drying and/or solidification process, and the particles in the force field being oriented perpendicular to the transport direction. In order to improve the transport process, the substrate is shaped before and/or during the drying/solidification process in order to counteract tensioning of the substrate caused by shrinkage of the coating.

Claims

1. A process for producing a coated carrier with a paste and/or a dry coating, comprising: providing a foil, providing a paste and/or dry coating, coating the foil with the paste and/or dry coating in order to obtain a coated carrier, drying the paste and/or consolidating the dry coating on the carrier, wherein the carrier, between provision thereof and drying and/or consolidation, is transported in a transport direction and the particles are aligned in the force field at right angles to the transport direction, wherein, before and/or during the drying and/or consolidation, shaping of the carrier is undertaken in order to counteract warpage of the carrier resulting from shrinkage of the coating.

2. The process according to claim 1, wherein the shaping of the carrier is undertaken by bending the carrier, such that the carrier is bent toward the coating and/or away from the coating.

3. The process according to claim 1, wherein, before the carrier is coated, a thermoresponsive material is added to the paste and/or the paste has thermoresponsive characteristics.

4. The process according to claim 1, wherein the paste used, with which the foil is coated, is one containing platelet-shaped and/or spherical and/or acicular particles.

5. The process according to claim 1, wherein the force field applied is a locally and/or temporally variable magnetic field.

6. The process according to claim 1, wherein a carrier comprising a copper foil and/or consisting of a copper foil is used.

7. The process according to claim 1, wherein the paste used is an aqueous suspension.

8. The process according to claim 1, wherein the process is used as part of a production of graphite-coated negative electrodes for lithium ion batteries.

9. The process according to claim 1, wherein a paste and/or a dry coating comprising alignable particles is used, wherein the particles are orientable under the influence of a force field in that the particles interacting with the force field experience a force that aligns them relative to the field lines of the force field, and the particles are aligned by exposing the coated carrier to the influence of the force field.

10. The process according to claim 1, wherein shaping of the carrier is undertaken during the alignment and/or between the alignment and the drying.

11. The process according to claim 1, wherein the carrier is bent toward the coating and/or away from the coating with the theoretical lines connecting two points within the plane of curvature running outside the coating on the carrier.

12. The process of claim 9, wherein the particles are carbon-based particles.

13. The process of claim 10, wherein the particles are graphite particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] A working example of the present invention is shown in the drawings and will be elucidated in detail hereinafter with reference to further details and advantages.

[0028] FIG. 1 is a schematic diagram of a carrier foil with curved surface after drying and with preshaped surface as compensation according to the present invention; and

[0029] FIG. 2 is a schematic diagram of a coating apparatus with transport zone.

DETAILED DESCRIPTION OF THE INVENTION

[0030] FIG. 1 firstly shows a carrier 1 comprising a foil 2 in the form of a sheet, and additionally a coating 3 that has been applied as paste on the foil 2. The situation I shows the carrier 1 after application of the coating but before drying, such that the paste 3 still takes the form of an aqueous suspension on the foil 2.

[0031] If the carrier 1 has been subjected to a drying process, the coating 2 would shrink in terms of volume. With increasing consolidation of the coating 3, therefore, the paste would exert a force on the foil 2. The foil 2, as shown in situation II, would become increasingly warped and would curve, especially along its width (at right angles to the transport direction T). The curved foil 2 is then difficult to align, which can complicate transport and any processing, especially the alignment of particles in a force field. If lateral guiding is used, the lateral portion can slide out of this guide at the edge of the foil 2.

[0032] In situation III, by contrast, unlike in situation II, the carrier foil 2 is already preshaped, for example, during drying, and in the opposite direction with respect to II. The drying process correspondingly eliminates this bending, such that the ready-coated and -dried carrier in turn forms a flat plane, as shown in situation IV.

[0033] FIG. 2 shows a schematic diagram of a coating apparatus 30 for coating of a foil or carrier 1. The foil or carrier 1 is provided with paste in the application station 31 and then sent to a drying module 32 for drying of the paste in transport direction T. The drying module 32 comprises a particular number n of individual stations 32.1, 32.2, ..., 32.n-1, 32.n, which are connected in series. By means of the return station 33, the carrier 1 is returned with a reversal of direction, for example, in order to be coated on the other side.

List of Reference Numerals

[0034] 1 carrier

[0035] 2 foil

[0036] 3 coating/paste

[0037] 30 coating apparatus

[0038] 31 application station

[0039] 32 drying station

[0040] 32.1, 32.2,..., 32.n individual stations (drying)

[0041] 33 return station

[0042] I situation: aqueous suspension on foil

[0043] II situation: bending as a result of drying

[0044] III situation: preshaped carrier

[0045] IV situation: compensation for bending after drying

[0046] T transport direction