METHOD AND APPARATUS FOR ORIENTING PARTICLES IN A PASTE

Abstract

The invention relates to a method for orienting particles in a paste, comprising: providing the paste, which comprises particles that can be oriented in the paste, wherein the paste comprises, in particular, carbon-based particles, preferably graphite, and/or a volatile substance, and exposing the paste to the influence of a force field such that the particles experience a force due to the interaction with the force field, by means of which the particles are oriented relative to the field lines of the force field. For cost savings and improvement to productivity, the paste is heated in order to at least temporarily reduce the viscosity of the paste and to reduce the orientation time required for orienting the particles in the force field, wherein the paste is heated before exposing and/or while exposing the paste to the influence of the force field.

Claims

1. A method for orienting particles in a paste comprising: providing the paste, which comprises particles that can be oriented in the paste, wherein the paste comprises in particular carbon-based particles, preferably graphite, and/or a volatile substance, exposing the paste to the influence of a force field such that the particles experience a force due to the interaction with the force field, by means of which the particles are oriented relative to the field lines of the force field, characterized by heating the paste in order to at least temporarily reduce the viscosity of the paste and to reduce the orientation time required for orienting the particles in the force field, wherein heating of the paste is carried out before exposing and/or while exposing the paste to the influence of the force field.

2. The method as claimed in claim 1, wherein heating the paste is also carried out additionally after exposing the paste to the influence of the force field.

3. The method as claimed in claim 1, wherein heating the paste is used additionally: to reduce the proportion of volatile substance in the paste, and/or to increase the viscosity of the paste again after temporary reduction of the viscosity, and/or to immobilize the particles.

4. The method as claimed in claim 1, wherein the paste is set to a certain drying rate which lies in a range from 0 to 50 mg/(cm.sup.2×minute), in particular from 0-30 mg/(cm.sup.2×minute), preferably from 0-16 mg/(cm.sup.2×minute).

5. The method as claimed in claim 1, wherein the paste is exposed to the certain drying rate before and/or while and/or after: heating, and/or exposing the paste to the influence of the force field.

6. The method as claimed in claim 1, wherein to adapt the drying rate: the paste in a chamber is introduced at least at times into a limited ambient volume in order to be able to locally adapt the drying rate of the paste, and/or steam is used, and/or a saturated salt solution is introduced into the chamber, and/or the ambient pressure is adapted, in particular increased, and/or the paste in a chamber is introduced at least at times into a limited ambient volume and the temperature of the gas in contact with the paste in the chamber changes, in particular is reduced to reduce the drying rate, and/or the paste in a chamber is introduced at least at times into a limited ambient volume and the chamber is flooded with a gas.

7. The method as claimed in claim 1, wherein an in particular aqueous suspension is used as the paste.

8. A method for producing coatings of a substrate, in particular when manufacturing graphite-coated anodes for lithium ion batteries, wherein a method as claimed in claim 1 is used after the paste has been applied to the substrate to be coated.

9. An apparatus for orienting particles in a paste, wherein the paste comprises particles that can be oriented therein and wherein the paste has in particular carbon-based particles, preferably graphite, and/or a volatile substance, comprising: a force field source in order to expose the paste to a force field such that the particles experience a force due to the interaction with the force field, by means of which the particles are oriented relative to the field lines of the force field, a heating apparatus, in particular an infrared lamp and/or a heater fan and/or a microwave generator in order to heat the paste, to at least temporarily reduce the viscosity of the paste and to reduce the orientation time required for orienting the particles in the force field, wherein the heating apparatus is arranged with regard to the force field source and/or can be monitored such that the paste is heated before exposing and/or while exposing the paste to the influence of the force field.

10. The apparatus as claimed in claim 9, wherein the force field source, which is in particular configured to generate a magnetic field which is configured to generate a locally and/or chronologically changeable field.

11. The apparatus as claimed in claim 9, wherein a transport apparatus is provided in order to move the paste and/or the paste applied to a substrate along the force field source, in particular the force field source generating a locally changeable field such that a chronologically changeable field prevails at the paste.

12. The apparatus as claimed in claim 9, wherein the heating apparatus is arranged with regard to the force field source such that the paste is also additionally heated after exposing the paste to the influence of the force field.

13. The apparatus as claimed in claim 9, wherein a moisture chamber is provided with an air moisture source in order to generate a certain drying rate and to reduce vaporization of the volatile substances from the paste, wherein the moisture chamber is arranged such that the paste is at least at times exposed to the certain drying rate: before and/or while and/or after exposing the paste to the influence of the force field, and/or before and/or while and/or after heating, wherein in particular the transport apparatus is configured to transport the paste through the moisture chamber.

14. The apparatus as claimed in claim 9, wherein a monitoring apparatus is provided to monitor the air moisture source and/or the heating apparatus in order to monitor the drying rate and/or the temperature, wherein the monitoring apparatus comprises in particular at least one sensor a temperature sensor and/or a hygrometer and/or a pressure-measuring apparatus in order to determine the temperature and/or the air moisture and/or the pressure and/or the drying rate in the moisture chamber and/or in the paste.

15. The apparatus as claimed in claim 9, wherein the moisture chamber is divided into at least two sub-chambers in which respectively different temperatures and/or ambient air moistures and/or different pressure and/or a different drying rate can be produced by means of the monitoring apparatus, wherein in particular the transport apparatus is configured to transport the paste through the sub-chambers one after another.

16. The apparatus as claimed in claim 9, wherein at least one chamber is provided which has in particular an apparatus for introducing gas into the chamber, which is configured to change the temperature of the gas located in the chamber and/or introduced in order to generate a certain drying rate and to reduce the uptake of volatile substances from the paste into the gas, wherein the chamber is arranged such that the paste at least at times is exposed to the certain drying rate before and/or while and/or after exposing the paste to the influence of the force field, and/or before and/or while and/or after heating, wherein in particular the transport apparatus is configured to transport the paste through the chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Examples of the present invention are shown in the drawings and are illustrated in more detail below with statement of further details and advantages.

[0039] FIG. 1 is a schematic representation of an apparatus for orienting particles according to the present invention;

[0040] FIG. 2 is a further apparatus for orienting particles according to the present invention which provides adaptation of the air moisture with regulation; and

[0041] FIG. 3 is an apparatus for orienting particles according to the present invention which provides adaptation of the air moisture with regulation, a corresponding section of the manufacturing path is however divided into individual zones or sub-chambers with individual regulation.

DETAILED DESCRIPTION OF THE INVENTION

[0042] FIG. 1 shows a schematic representation of an apparatus 1 for orienting particles in a paste according to a basic structure. This apparatus 1 comprises a transport apparatus 2 for reel-to-reel transport. A substrate 3, which is coated with the paste, is transported via these reels 2. The transport apparatus 2 already shows that the method step shown here in part may be embedded in a continuous production process and the substrate to be processed is guided from processing station to processing station.

[0043] In FIG. 1, the coated substrate is introduced at times into a chamber 4 via the transport apparatus 2 so that the substrate 3 within this chamber 4 is exposed to certain ambient characteristics (for example, a certain air moisture, a certain pressure or the like). In the region of the chamber 4, the substrate 3 is exposed to a force field which is generated by means of a force field source 5 in the chamber 4 in the vicinity of the substrate 3. This force field source 5 may cause orientation of the particles in the paste. Furthermore, a heating apparatus 6 is provided which ensures that the coated substrate 3 is heated and the paste loses viscosity such that the particles located therein may be oriented more easily and more rapidly. Orientation may advantageously take place in this respect in the time in which the corresponding section of the substrate 3, which is moved continuously via the transport apparatus 2, is located in the chamber 4 in the region of the force field source 5. Chamber 4 and force field source 5 or heating apparatus 6 may have appropriate dimensions.

[0044] In the present example according to FIG. 1, the force field source 5 and the heating apparatus 6 are arranged such that, seen chronologically, precisely during orientation of the particles, heating also takes place. During transport of the substrate 3, the paste is thus exposed simultaneously to the heating apparatus 6 and also to the force field generated by the source 5.

[0045] A similar example can be seen in FIG. 2. The corresponding apparatus 11 for orienting particles in a paste also comprises here a transport apparatus 12 in the form of reels, wherein a substrate film 13, which is coated with a paste 13a, is transported. The substrate 13 with the coating 13a is transported through a moisture chamber 14. As force field source 15, an arrangement of so-called magnet boards, which extend over the entire region of the moisture chamber 14 with regard to the transport path of the substrate 13, is provided below the chamber 14. These magnet boards 15 may consist, for example, of a bar-like arrangement of permanent magnets, wherein these bars are arranged in lines transversely or substantially transversely (at a predetermined angle offset, deviating from a 90° orientation) to the transport direction such that orientation of field lines changes from line to line and the coating 13a experiences a magnetic alternating field during transport through the chamber 14. Within the chamber 14, a heating apparatus 16 in the form of an IR lamp is provided first of all in the starting region thereof (in FIG. 2: from right to left). The air moisture in the chamber 14 is generated by a vapor source or a vaporizer 17. Both temperature and air moisture in the surroundings are determined via corresponding sensors 18a, 18b. Furthermore, a temperature sensor 18c is provided but which is configured and arranged such that measures only the temperature of the coating or of the paste 13a. The data of the sensors 18a, 18b, 18c are forwarded to a monitoring apparatus (not shown), which in turn regulates in particular the heating apparatus 16 and the vapor source 17.

[0046] An apparatus analogous in basic structure to that in FIG. 2 is shown in FIG. 3, but the chamber 24 is divided into individual sub-chambers 24.1, 24.2, 24.3, . . . , 24.n. FIG. 3 shows an apparatus 21 for orienting particles which first of all has in any case a transport apparatus 22 in the form of reels, via which a substrate film 23 with a coating 23a is guided and transported. Analogously to FIG. 2, so-called magnet boards 25, which serve as a force field source, are arranged below the substrate tape 23. Each sub-chamber 24.1, 24.2, 24.3, . . . , 24.n has a heating apparatus 26.1, 26.2, 26.3, . . . 26.n, and furthermore corresponding vapor generators 27.1, 27.2, 27.3, . . . , 27.n to set the air moisture in the respective sub-chambers 24.1, 24.2, 24.3, . . . , 24.n. Each sub-chamber 24.1, 24.2, 24.3, . . . , 24.n is fitted individually with sensors 28.1, 28.2, 28.3, . . . , 28.n such that air moisture and temperature for each of the sub-chambers may be regulated individually via one or more monitoring apparatuses.

[0047] Depending on the embodiment, the magnet boards 25 may extend over all sub-chambers 24.1, 24.2, 24.3, . . . , 24.n along the transport path or even already end beforehand; this is shown by indicating a magnet board section 25.n drawn as a dashed line. It is conceivable, for example, to lower air moisture in the sub-chamber 24.n lying thereabove even below the normal ambient value (by means of silica gel) or to lower the pressure in order to consciously increase the drying rate here in order to rapidly immobilize the particles.

LIST OF REFERENCE SIGNS

[0048] 1 Apparatus for orienting particles in a paste [0049] 2 Transport apparatus [0050] 3 Substrate [0051] 4 Chamber [0052] 5 Force field source [0053] 6 Heating apparatus [0054] 11 Apparatus for orienting particles in a paste [0055] 12 Transport apparatus [0056] 13 Substrate [0057] 13a Paste/coating [0058] 14 Moisture chamber [0059] 15 Magnet boards [0060] 16 IR lamp [0061] 17 Vapor source [0062] 18a Temperature sensor [0063] 18b Moisture sensor [0064] 18c Temperature sensor for coating [0065] 21 Apparatus for orienting particles in a paste [0066] 22 Transport apparatus [0067] 23 Substrate [0068] 23a Paste/coating [0069] 24 Chamber [0070] 24.1 Sub-chamber [0071] 24.2 Sub-chamber [0072] 24.3 Sub-chamber [0073] 24.n Sub-chamber [0074] 25 Magnet boards [0075] 25.n Magnet boards [0076] 26.1 IR lamp [0077] 26.2 IR lamp [0078] 26.3 IR lamp [0079] 26.n IR lamp [0080] 27.1 Vapor source [0081] 27.2 Vapor source [0082] 27.3 Vapor source [0083] 27.n Vapor source [0084] 28.1 Sensor [0085] 28.2 Sensor [0086] 28.3 Sensor [0087] 28.n Sensor