JP2006172827A - Clearance determination method of gang edge cutting device, cutting method by gang edge cutting device, and gang edge cutting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clearance determination method of a gang edge cutting device in which determination of a clearance amount between upper and lower edges is facilitated. <P>SOLUTION: In the gang edge cutting device in which the web is cut in the longitudinal direction after the press working is carried out on the metallic web on which active materials are intermittently coated are dried in a manufacturing process of an electrode for a non-aqueous electrolytic solution secondary battery, and in the method to determine the clearance C between respective opposing end faces to which respective disk-shaped upper edge 18 and lower edge 20 adjacently arranged so as to have an overlapping part in the vertical direction, the clearance between the upper edge 18 and the lower edge 20 is determined by measuring a folded amount D of a folding part 23 of a non-coating part formed in a cutting edge part of tape-shaped electrode materials 22 after cutting. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a clearance quantification method for a gang blade-type cutting device, a cutting method using a gang blade-type cutting device, and a gang blade-type cutting device that are used in the manufacturing process of a non-aqueous electrolyte secondary battery electrode.

  In recent years, lithium ion secondary batteries, which are nonaqueous electrolyte secondary batteries, have been used as batteries for personal computers and mobile phones. Lithium ion secondary batteries have the advantage that they have a higher capacity than conventional rechargeable secondary batteries and do not cause a decrease in capacity even if they are charged frequently.

  An electrode to be a positive electrode and a negative electrode accommodated in a lithium ion secondary battery has an active material and a binder capable of inserting and removing lithium on a current collector made of metal foil, and a conductive auxiliary agent as required. In addition, a slurry obtained by adding water or an organic solvent and adding a thickener or the like to a slurry is applied and dried.

  For the positive electrode, a lithium-containing transition metal oxide (such as lithium cobaltate or lithium manganate) is mainly used as an active material. To this active material, carbon black such as acetylene black or graphite is added as a conductive additive, and N-methyl-2-pyrrolidone is added and mixed as necessary using a binder such as polyvinylidene fluoride. Use to adjust the slurry. This slurry is intermittently coated on a web such as an aluminum foil by die coating or comma coating in a coating process and dried. Then, in order to increase the capacity of the battery, the active material layer is densified by pressing the web in a pressing step. Then, in a slit process, it cuts along a longitudinal direction so that a plurality of tape-like electrode materials may be formed from the web. Finally, a positive electrode is obtained by cutting the tape-shaped electrode material into a predetermined length.

  On the other hand, for the negative electrode, graphite or the like that can mainly store and release lithium ions is used as an active material. A slurry is adjusted by mixing a rubber binder such as carboxymethyl cellulose or styrene butadiene rubber with this active material, and adding and dispersing water as necessary. This slurry is intermittently coated on a web such as a copper foil with a die coat or a comma coat in a coating process and dried. Then, in order to increase the capacity of the battery, the active material layer is densified by pressing the web in a pressing step. Then, in a slit process, it cuts along a length direction so that a plurality of tape-like electrode materials may be formed from the web. Finally, the tape-shaped electrode material is cut into a predetermined length to obtain a negative electrode.

  By winding the positive electrode and the negative electrode obtained as described above with a separator made of, for example, a polyethylene porous film sandwiched between them, and storing them in a predetermined can, and then injecting and sealing the electrolyte solution A lithium ion secondary battery is obtained.

  When the density of the active material layer on the web is increased by passing through the pressing step, the active material layer is hard, that is, the bending strength tends to increase. In addition, if the amount of the binder in the active material layer is reduced in order to obtain a high-capacity battery, the adhesion of the coating film to the web is reduced, and the active material layer is brittle, that is, the shear strength is reduced. easy. Such a web-like electrode base material having low adhesion to the web, low shear strength of the active material layer and high bending strength is obtained by cutting the tape-like electrode material when cutting into a predetermined width in the slitting process. The active material layer easily falls off at the edge.

  In the slitting process, a gang blade type cutting device is used to cut a web-like electrode base material having an active material layer coated on the surface thereof into a tape-like electrode material. As shown in FIG. 6, this gang blade type cutting device is arranged in parallel to the upper shaft 50 and a plurality of upper blades 51, 52 having a disk shape externally fixed to the upper shaft 50 at predetermined intervals. In addition, a plurality of lower blades 54 and 55 having a disk shape fixed to the lower shaft 53 at predetermined intervals are provided. In the upper blades 51 and 52, two upper blades 51 and 52 forming a gap A having a desired electrode material width between each axial end face make a pair, and in the lower blades 54 and 55, a desired electrode is provided between each axial end face. Two lower blades 54 and 55 forming an interval A which is a material width form a pair.

  The upper blade 51 and the lower blade 55, and the upper blade 52 and the lower blade 54 are arranged adjacent to each other so as to have overlapping portions in the vertical direction, and the axial end surfaces of the upper blade 51 and the lower blade 55, and The axial end surfaces of the upper blade 52 and the lower blade 54 are in contact with each other. In this state, a plurality of tape-shaped electrode materials having a desired width A can be obtained by passing a web-shaped electrode substrate having an active material layer formed on the surface between the upper blades 51, 52 and the lower blades 54, 55. It will be cut and formed. However, there was a phenomenon in which the active material layer was missing and dropped off at the cut edge of the tape-like electrode material cut in this way.

  When the active material layer falls off, after the battery is assembled, the fallen pieces press the separator in the battery, causing rapid self-discharge even when the battery is not connected to the device (soft short, OCV failure <Open Circuit Voltage>), and there is a problem that the battery capacity decreases due to the loss of the active material layer.

Patent Document 1 discloses an electrode for a nonaqueous electrolyte battery intended to prevent the occurrence of burrs and whiskers in the metal part of the electrode sheet for a nonaqueous electrolyte battery and to reduce the undulation phenomenon in the cut surface of the electrode sheet. A sheet cutting apparatus is disclosed, but in this apparatus, the adhesion of the coating film to the web is low, the shear strength of the active material layer is low, and the active material layer of the electrode plate with high bending strength is not removed. Could not prevent.
Japanese Patent No. 3085101

  As a result of examining the method for preventing the active material layer from falling off in the slitting process, the inventor of the present application has found that there is a slight gap between the end surfaces of the upper blade 51 and the lower blade 55 and between the end surfaces of the upper blade 52 and the lower blade 54. It has been found that the problem of falling off of the active material layer can be solved by providing the clearance. Details thereof are described in Japanese Patent Application No. 2004-96480, which is another patent application of the present applicant.

  However, since the clearance amount is as small as about 30 μm, for example, it is difficult to directly measure and quantify it.

  Therefore, as a result of earnest research on the method for determining the clearance amount, the inventor of the present application has found that the amount of bending of the bent portion of the uncoated portion formed on the cut edge portion of the cut tape-shaped electrode material is the upper blade of the gang blade. And found that it is almost equivalent to the clearance amount of the lower blade.

The present invention has been made on the basis of this finding, and the first invention is to press a material obtained by intermittently applying and drying an active material on a metal web in the process of manufacturing a non-aqueous electrolyte secondary battery electrode. After processing, in the gang blade type cutting device for cutting the web in the longitudinal direction, the upper blade and the lower blade forming each disk shape adjacent to each other so as to have overlapping portions in the vertical direction are opposed to each other. In the method of quantifying the clearance between each end face,
What is characterized in that the clearance between the upper blade and the lower blade is quantified by measuring the amount of bending of the bent portion of the uncoated portion formed at the cut edge portion of the tape-shaped electrode material after cutting. It is.

  In the clearance quantification method of the gang blade cutting apparatus according to the first aspect of the invention, the clearance is optimally 30 ± 20 μm.

According to a second aspect of the present invention, after the active material is intermittently applied on the metal web and dried in the course of manufacturing the electrode for the non-aqueous electrolyte secondary battery, the web is cut in the longitudinal direction after being pressed. In the cutting method by the gang blade type cutting device to
Cutting is performed in a state where the clearance between the opposing end faces of the upper and lower blades that are arranged adjacent to each other so as to have overlapping portions in the vertical direction is set to 30 ± 20 μm. Is.

Further, the third aspect of the present invention is to press a material obtained by intermittently applying and drying an active material on a metal web in the process of manufacturing a non-aqueous electrolyte secondary battery electrode, and then cutting the web in the longitudinal direction. In the gang blade type cutting device,
It is characterized in that the clearance between the opposing end faces of the upper and lower blades that are arranged adjacent to each other so as to have overlapping portions in the vertical direction is set to 30 ± 20 μm.

In the gang blade cutting apparatus according to the third aspect of the present invention, the clearance includes a plurality of upper blade spacers disposed between a plurality of upper blades sheathed on the upper shaft, and a plurality of lower blades sheathed on the lower shaft. You may set by the dimensional relationship with the spacer for several lower blades each arrange | positioned in between.
In this case, the gang blade cutting device is attached to the threaded portion of the end portion of the upper shaft, whereby the upper shaft nuts that tighten the plurality of upper blades and the plurality of upper blade spacers in the axial direction, A lower shaft nut that tightens the plurality of lower blades and the plurality of lower blade spacers in the axial direction by being attached to a threaded portion of an end portion of the lower shaft, and the upper shaft nut and the lower shaft The clearance may be adjusted by changing each tightening force of the nut, and each tightening force of the upper shaft nut and the lower shaft nut is preferably 30 to 75N.

  According to the gang blade type cutting device clearance quantification method, the gang blade type cutting device cutting method, and the gang blade type cutting device of the present invention, it becomes easy to optimize the clearance amount between the upper blade and the lower blade. Thus, it is possible to cut the tape-shaped electrode material that becomes the electrode for the non-aqueous electrolyte secondary battery without causing the active material layer to fall off by the gang blade type cutting device set to the optimum clearance amount. .

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a cutter unit 10 of a gang blade cutting apparatus according to an embodiment of the present invention. The cutter unit 10 includes a rod-shaped upper shaft 14 having one end fixed to the end piece 12 and a rod-shaped lower shaft having one end fixed to the end piece 12 and extending parallel to the upper shaft 14. 16. The other ends of the upper shaft 4 and the lower shaft 16 are threaded portions 14a and 16a, respectively, and an upper shaft nut 15 and a lower shaft nut 17 are screwed onto the threaded portions 14a and 16a, respectively. ing.

  The upper shaft 14 is provided with a plurality of upper blades 18 each having a metal disk shape with a thickness of 3 mm, for example. Between the end piece 12 and the upper blade 18, between the upper blades 18, and between the upper blade 18 and the base shaft nut 15, for example, a metal cylindrical upper blade spacer (not shown) is disposed on the upper shaft 14. Are arranged on the exterior. By this upper blade spacer, two upper blades 18 having a desired product width A set between the opposing axial end faces form a pair. Further, the upper shaft 14 is rotationally driven integrally with the assembled upper blade 18 and upper blade spacer by a driving mechanism (not shown).

  The lower shaft 16 is also provided with a plurality of lower blades 20 each having a metal disk shape with a thickness of 3 mm, for example. Between the end piece 12 and the lower blade 20, between the lower blades 20, and between the lower blade 20 and the lower shaft nut 17, for example, a metal cylindrical lower blade spacer (not shown) is attached to the lower shaft 20. They are arranged on the exterior. By this lower blade spacer, two lower blades 20 in which the distance between the opposed axial end faces is set to a desired product width A form a pair. Further, the lower shaft 16 is rotationally driven integrally with the assembled lower blade 20 and lower blade spacer by a drive mechanism (not shown).

  The upper blade 18 and the lower blade 20 are arranged in a positional relationship such that they have overlapping portions in the vertical direction. A clearance or clearance amount C is formed between the axial end surfaces of the upper blade 18 and the lower blade 20 adjacent to each other.

  The clearance C is basically set by the dimensional relationship between the upper blade spacer and the lower blade spacer. However, in the upper shaft 14, the tightening force of the upper shaft nut 15 that tightens the upper blade 18 and the upper blade spacer in the axial direction, and in the lower shaft 16, the lower force that tightens the lower blade 20 and the lower blade spacer in the axial direction. When the tightening force of the shaft nut 17 changes, the contact state between the plurality of upper blades 18 and the plurality of upper blade spacers changes, and the contact state between the plurality of lower blades 20 and the plurality of lower blade spacers also changes. As a result, the clearance amount C changes slightly.

  Experience has shown that the clearance amount C is in the optimum range of 30 ± 20 μm. If the clearance amount C is set within this range, as shown in FIG. 2A, the inclination of the cutting edge portion of the upper active material layer 24 of the electrode material 22 cut into a tape shape by the cutter unit 10 is performed. The amount B can be suppressed to about 0 to 30 μm, and the upper active material layer 24 can be prevented from falling off at the cutting edge. When the clearance amount C is smaller than the above range, a dropout portion 25 of the upper active material layer 24 is generated at the cut edge as shown in FIG. On the other hand, when the clearance amount C is larger than the above range, as shown in FIG. 2C, the inclined portion 26 of the upper active material layer 24 at the cutting edge portion protrudes in the lateral direction. Will come into contact with the upper blade 18 and the lower blade 20 and will easily fall off. In FIG. 2, reference numeral 28 denotes a current collector made of a metal foil, and reference numeral 30 denotes a lower active material layer.

  As described above, the clearance C is in the optimum range of 30 ± 20 μm and is basically set by the dimensional relationship between the upper blade spacer and the lower blade spacer. The clearance C varies slightly depending on the tightening force of the lower shaft nut 17. For this reason, until now, due to the structure of the cutting apparatus in which the cutter unit 10 is incorporated, the clearance amount cannot be directly measured and accurately quantified.

  Therefore, as a result of intensive studies on the method for determining the clearance amount C, the inventor of the present application, as shown in FIG. 3, the bent portion of the uncoated portion formed at the cut edge portion of the cut tape-shaped electrode material 22. 23 is the clearance between the upper blade 18 and the lower blade 20 of the gang blade (the same applies to the length of the bent portion 23 in the width direction of the tape-like electrode material 22 (left and right direction in FIG. 3)). It has been found that it corresponds approximately to the quantity C.

  The bending amount D of the bent portion 23 can be accurately measured by observing the cut edge portion of the cut tape-shaped electrode material 22 with a microscope, but the measurement method is not limited to that using a microscope.

  Based on the bending amount D of the bent portion 23 quantified in this way, the clearance amount C between the upper blade 18 and the lower blade 20 is set to be within the optimum range.

  In the gang blade type cutting device equipped with the cutter unit 10 in which the clearance amount D is set in the optimum range, the metal foil web having an active material layer densified by press working on at least one surface is a cutter. When passed between the upper shaft 14 and the lower shaft 16 of the unit 10, the web is cut between the upper blade 18 and the lower blade 20 provided with the clearance C, and a desired product width A (for example, 40 mm) of a plurality of tape-shaped electrode materials 22 are formed.

  As described above, in the gang blade type cutting apparatus of the present embodiment, the upper blade 18 is measured by measuring the amount D of the bent portion 23 of the uncoated portion formed at the cutting edge portion of the cut tape-like electrode material 22. By quantifying the clearance amount C between the upper blade 18 and the lower blade 20, it becomes easy to optimize the clearance amount C between the upper blade 18 and the lower blade 20, and as a result, the gang set to the optimum clearance amount C. The tape-shaped electrode material 22 that becomes the electrode for the non-aqueous electrolyte secondary battery can be cut without causing the active material layer 24 to fall off by the blade-type cutting device.

Next, adjustment of the clearance amount D will be described.
As described above, the optimum clearance amount D is 30 μm, but the optimum range is allowed up to 20 μm before and after that. Here, the cutter unit 10 is assembled by setting the dimensional relationship between the upper blade spacer and the lower blade spacer so that the clearance amount D is 30 μm, and the tightening forces of the upper shaft nut 15 and the lower shaft nut 17 are set. It changed into 30N, 45N, and 60N, and the said amount D of folding was measured about 13 samples of the alphabet AM. The result is shown in the graph of FIG.

  And from the result shown in FIG. 4, the average value of the folding amount D in each clamping force was 47.8 μm at 30N, 40.3 μm at 45N, and 36.3 μm at 60N. FIG. 5 is a graph showing the relationship between the tightening force and the average value of the folding amount D. From this graph, it was found that the tightening force of the nuts 15 and 17 needs to be 75 N in order to set the bending amount D, that is, the clearance amount C to the optimum value of 30 μm. However, since tightening with 75N is difficult as a practical problem, the clearance amount C can be set to 50 μm or less, which is the optimum range, as long as the tightening force is within a range of 30 to 75N. It became clear that.

The figure which shows the cutter unit of the gang blade cutting device of this embodiment. The figure which shows the cutting state of a tape-shaped electrode material in case the clearance between an upper blade and a lower blade is larger than an optimal range when it is in the optimal range and smaller than an optimal range. The figure which shows the bending part of the uncoated part formed in the cutting edge part of the cut tape-shaped electrode material. The graph which shows the relationship between clamping force and the amount of bending about 13 samples. A graph showing the relationship between the tightening force and the amount of bending with an approximate straight line. The figure which shows the cutter unit of the conventional gang blade type cutting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Cutter unit 12 ... End piece 14 ... Upper shaft 15 ... Upper shaft nut 16 ... Lower shaft 17 ... Lower shaft nut 18 ... Upper blade 20 ... Lower blade 22 ... Tape-shaped electrode material 23 ... Folding part C ... Clearance or Clearance amount D ... Folding amount

Claims (7)

A gang blade type cutting device that presses a material obtained by intermittently applying an active material on a metal web and drying it in the manufacturing process of a non-aqueous electrolyte secondary battery electrode, and then cutting the web in the longitudinal direction. Then, in the method of quantifying the clearance between the opposing end surfaces of the upper and lower blades in the shape of each disk arranged adjacent to each other so as to have an overlapping portion in the vertical direction,
A gang characterized in that the clearance between the upper blade and the lower blade is quantified by measuring the amount of bending of the bent portion of the uncoated portion formed on the cut edge portion of the tape-shaped electrode material after cutting. A clearance quantification method for blade-type cutting devices.   2. The clearance quantification method for a gang blade cutting apparatus according to claim 1, wherein the clearance is optimally 30 ± 20 [mu] m. By a gang blade type cutting device that presses a material obtained by intermittently applying an active material on a metal web and drying it in the process of manufacturing a non-aqueous electrolyte secondary battery electrode, and then cutting the web in the longitudinal direction. In the cutting method,
Cutting is performed in a state where the clearance between the opposing end faces of the upper and lower blades that are arranged adjacent to each other so as to have overlapping portions in the vertical direction is set to 30 ± 20 μm. A cutting method using a gang blade cutting device. A gang blade type cutting device that presses a material obtained by intermittently applying an active material on a metal web and drying it in the manufacturing process of a non-aqueous electrolyte secondary battery electrode, and then cutting the web in the longitudinal direction. In
A gang blade type cutting apparatus characterized in that the clearance between the opposing end faces of the upper and lower blades which are arranged adjacent to each other so as to have overlapping portions in the vertical direction is set to 30 ± 20 μm. .   The clearances are respectively disposed between a plurality of upper blade spacers disposed between a plurality of upper blades sheathed on an upper shaft and a plurality of lower blades sheathed on a lower shaft parallel to the upper shaft. The gang blade type cutting device according to claim 4, wherein the gang blade cutting device is set according to a dimensional relationship with the plurality of lower blade spacers.   Attached to the upper shaft nut that tightens the plurality of upper blades and the plurality of upper blade spacers in the axial direction by being attached to the threaded portion of the upper shaft end, and to the threaded portion of the lower shaft end A plurality of lower blades and a lower shaft nut for tightening the plurality of lower blade spacers in the axial direction, and changing each tightening force of the upper shaft nut and the lower shaft nut The gang blade type cutting device according to claim 5, wherein the clearance is adjusted.   The gang blade type cutting apparatus according to claim 6, wherein each of the tightening forces of the upper shaft nut and the lower shaft nut is 30 to 75N.

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