JP2004249261A - Die coating apparatus and die coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the sagging at a paste coated end part when coating one surface of a sheet after the other surfaces of the sheet is coated by a die coating. <P>SOLUTION: In a slit die 60 for performing back surface coating, both end parts of a collector sheet 20 is supported by a holding part 61 and the level of a paste discharge port 63 is made lower than the level of the holding part 61 by level difference H to coat the back surface of a collector sheet 20. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a die coating apparatus and a die coating method used in a coating step of coating a coating liquid on the front and back surfaces of a sheet.
[0002]
[Prior art]
In the process of applying the paste of the electrode active material on both surfaces of the current collector sheet, die coating is used. Usually, after the paste is applied to one surface of the sheet using a slit die with a back roller, the paste is applied to the uncoated surface using another slit die. However, since the back roller cannot be used for applying the paste on the uncoated surface, the paste is applied to the back surface of the sheet traveling on the slit die in a state where a predetermined tension is applied.
[0003]
For example, JP-A-2000-353514 discloses a die coater for applying a paste of an electrode active material to the front and back surfaces of a current collector sheet.
[0004]
[Patent Document 1]
JP 2000-353514 A [Patent Document 2]
JP-A-7-65816 [0005]
[Problems to be solved by the invention]
In the slit die for back coating, the current collector sheet is partially lifted by the discharge pressure of the paste. For this reason, as shown in FIG. 16, dripping occurs at the paste-coated end due to the tension of the current collector sheet.
[0006]
In addition, the discharge amount of the paste is not always constant in the width direction of the current collector sheet, and the discharge amount becomes uneven, so that the thickness of the paste coating film sometimes varies.
[0007]
Therefore, an object of the present invention is to provide a die coating apparatus and a die coating method that can solve the above-mentioned problems. More specifically, an object of the present invention is to prevent dripping of a paste-coated end portion when coating on one sheet surface by die coating and then coating on the other sheet surface.
[0008]
Another object of the present invention is to uniformly apply a paste coating film in the sheet width direction when coating one sheet surface by die coating and then coating the other sheet surface.
[0009]
[Means for Solving the Problems]
That is, a desirable mode of the present invention is a first die for applying a first coating liquid on one surface of a sheet, and a second coating on the other surface of the sheet after the application by the first die. A die coating apparatus including a second die for applying a liquid, wherein the second die includes a holding unit configured to hold both ends of the sheet, and a discharge port configured to discharge a coating liquid. The outlet is a concave portion with respect to the holding portion.
[0010]
Accordingly, since the coating is performed by the second die in a state where the both ends of the sheet are held by the holding unit and the sheet is stretched, dripping of the end of the application surface can be prevented. Note that the first coating liquid and the second coating liquid may be different.
[0011]
Another preferred embodiment of the present invention provides a first die for applying a first coating liquid on one surface of a sheet, and a second coating on the other surface of the sheet after application by the first die. A second die for applying a liquid, wherein the second die includes a suction unit for suctioning the sheet, behind a discharge port for discharging the coating liquid.
[0012]
Thereby, the clearance in the width direction between the second die and the sheet can be made constant, and the uneven coating by the second die can be prevented, and the coating quality can be improved.
[0013]
Another preferred embodiment of the present invention provides a first die for applying a first coating liquid on one surface of a sheet, and a second coating on the other surface of the sheet after application by the first die. A second die for applying a liquid, wherein the second die includes at least one rectifying unit in a flow path of the coating liquid.
[0014]
Accordingly, the discharge amount of the second coating liquid discharged from the second die in the width direction becomes uniform, so that coating unevenness by the second die can be prevented, and coating quality can be improved.
[0015]
In another preferred aspect of the present invention, the rectifying section is provided at a central portion of the flow path.
[0016]
Another preferred embodiment of the present invention provides a first die for applying a first coating liquid on one surface of a sheet, and a second coating on the other surface of the sheet after application by the first die. A die coating apparatus comprising: a second die for applying a liquid; and a blower for blowing a gas to the sheet in a direction in which the sheet advances in or after a discharge port of the second die; A film thickness detection unit that detects a coating film thickness of the working liquid in the sheet width direction, and the ejection amount control unit detects the second coating liquid in the sheet width direction detected by the film thickness detection unit. A control unit that controls an amount of the gas ejected in the sheet width direction according to a coating film thickness.
[0017]
According to this, the film thickness of the second coating liquid in the sheet width direction is set as a parameter, and the feedback control is performed so that the air amount in the width direction of the gas sprayed on the sheet on the second die does not vary. Therefore, uneven coating by the second die can be prevented, and coating quality can be improved. The gas is, for example, air.
[0018]
In another preferred embodiment of the present invention, a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. A die coating method for applying a liquid, wherein in the application by the second die, a discharge port for discharging the coating liquid to a holding unit for holding the sheet at both ends is a concave portion, It is characterized in that a coating liquid is applied to the sheet.
[0019]
In another preferred embodiment of the present invention, a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. A die coating method for applying a liquid, wherein, in the application by the second die, a second coating liquid is applied to the second die in a state where the sheet is sucked into the second die behind a discharge port for discharging the coating liquid. Is applied to the sheet.
[0020]
In another preferred embodiment of the present invention, a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. A die coating method of applying a liquid, wherein in the application by the second die, a second coating liquid is provided while at least one rectifying unit is provided in a flow path of the coating liquid of the second die. It is characterized in that it is applied to the sheet.
[0021]
In another preferred aspect of the present invention, the rectifying section is provided at a central portion of the flow path.
[0022]
In another preferred embodiment of the present invention, a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. A die coating method of applying a liquid, wherein a coating thickness of the second coating liquid in the sheet width direction is detected, and an ejection amount in the sheet width direction is controlled according to the detected coating thickness. The second coating liquid is applied to the sheet in a state where the discharged gas is blown in the sheet advancing direction or behind the discharge port of the second die.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the claimed invention, and all combinations of features described in the embodiments are solutions of the invention. It is not always necessary for the means.
[0024]
The embodiment described below is an application example in the case of manufacturing a battery sheet electrode as a specific example.
[0025]
FIG. 1 is a schematic diagram illustrating a die coating apparatus 10 according to the embodiment.
[0026]
The current collector sheet 20 is unreeled from the unwinding unit 30 and travels partially wound by the back roller 40. The tank 42 contains an electrode active material paste, and the electrode active material paste sucked by the pump 44 is supplied to the slit die 50. The slit die 50 is provided such that the discharge port faces the back roller 40 at a predetermined interval with the current collector sheet 20 interposed therebetween. The paste of the electrode active material is applied to one surface (hereinafter, referred to as a surface for convenience) of the traveling current collector sheet 20 by the slit die 50.
[0027]
The current collector sheet 20 having the surface coated with the electrode active material paste is partially wound by a roller 52 and then sent to a slit die 60. The current collector sheet 20 travels on the slit die 60 while receiving a predetermined tension. The paste of the electrode active material sucked from the tank 42 by the pump 46 is supplied to the slit die 60. The paste of the electrode active material is applied to the back surface of the current collector sheet 20 by the slit die 60.
[0028]
Thereafter, the current collector sheet 20 travels in the drying oven 70, the coated electrode active material is dried, and the current collector sheet 20 is partially wound by the rollers 54 and 56. Winded by 80.
[0029]
When the current collector sheet is a positive electrode, for example, an aluminum foil is used for the current collector sheet 20, and the electrode active material is, for example, a positive electrode active material, a conductive material for imparting conductivity to the positive electrode active material. A material obtained by mixing and dissolving a material (e.g., carbon graphite) and a binder (e.g., an organic binder) that binds them to an organic solvent or the like is used. When the current collector sheet is a negative electrode, for example, a copper foil is used for the current collector sheet 20, and a material obtained by dissolving a negative electrode active material (such as graphite) in a solvent is used as an electrode active material. Can be
[0030]
FIG. 2 is a perspective view of the slit die 60. FIG. 3 is a sectional view of the slit die 60. In the slit die 60 of the present embodiment, a step H is provided between the paste discharge port 63 and the holding portion 61 that holds the current collector sheet 20.
[0031]
If one specific example of the dimensions and coating conditions of the slit die 60 is given, the slit width S of the slit die 60 is 500 μm, the step H is 100 μm, the width A is 100 mm, the width B is 10 mm, and the width C is 104 mm. The electrode active material paste application amount was 15 mg / cm 2, the electrode active material paste discharge pressure was 100 KPa, and the electrode active material paste viscosity was 3000 mPa · S.
[0032]
According to this, since the current collector sheet 20 is held by the holding portions 61 on both sides thereof, receives a predetermined tension, and is stretched in the width direction, the paste of the electrode active material is applied to the back surface. In addition, it is possible to prevent dripping at the edge of the coating film and uneven thickness of the coating film, thereby improving coating accuracy or coating film quality.
[0033]
Next, a die coating apparatus 12 according to another embodiment will be described. FIG. 4 is a schematic view showing the die coating device 12. Since the basic configuration of the die coating apparatus 12 is the same as that of FIG. 1, the description of the same configuration will be omitted.
The die coating apparatus 12 includes a slit die 62 instead of the slit die 60. The slit die 62 is connected to the vacuum pump 48, and the current collector sheet 20 is sucked by applying a negative pressure to a suction hole described later. As the vacuum pump, it is preferable to use a dry pump or an oil rotary pump in combination with a cold trap in order to prevent contamination of the current collector sheet.
[0034]
FIG. 5 is a perspective view of the slit die 62. Both ends of the slit 104 of the slit die 62 are partitioned by the shim 102. The slit width T (or shim thickness) is typically 0.2 to 0.7 mm. A suction hole 100 is provided on a base of the slit die 62 on the side of the slit die 50. The suction hole 100 is connected to the vacuum pump 48, and the current collector sheet 20 traveling above the suction hole 100 is sucked toward the suction hole 100. The suction pressure is preferably 0.1 to 1 kPa. The step I of the slit die 62 is, for example, 50 to 100 μm.
[0035]
As described above, the current collector sheet 20 is sucked by the suction holes 100, whereby the current collector sheet 20 can be prevented from being inclined above the slit 104, and the back surface of the current collector sheet 20 can be uniformly coated evenly. be able to.
[0036]
In addition, since the current collector sheet is prevented from fluttering (vibrating) during coating, the weight per unit area can be reduced.
[0037]
In the present embodiment, the suction holes 100 are provided on the base of the slit die 62 on the side of the slit die 50 (that is, before paste application).
[0038]
Next, a die coating apparatus 14 according to still another embodiment will be described. FIG. 6 is a schematic diagram showing the die coating device 14. Since the basic configuration of the die coating apparatus 14 is the same as that of FIG. 1, the description of the same configuration will be omitted. FIG. 7 is a perspective view of the slit die 64. A pipe for supplying a paste is connected to the slit die 64a. The slit die 64a and the slit die 64b are assembled via the shim 300 to form a paste flow path. The upper surfaces of the slit die 64a and the slit die 64b may have a step.
[0039]
FIG. 8 shows an AA ′ cross-sectional view of the shim 300. The shim 300 includes a rectifying column 302 at the center. The width W of the rectifying column 302 is, for example, 3 mm. The slit width U is, for example, 200 mm. The rectifying column 302 is desirably shorter than the upper surface of the shim 300, and the offset L is preferably, for example, 10 mm. Further, the width R of the connecting portion of the slit die 64a with the supply port is longer than the slit width U.
[0040]
FIG. 9 is a sectional view of the slit die 64a taken along the line BB '. The slit die 64a is provided with a rectangular paste supply port having a width R and a height V, and paste is supplied to a space formed by the shim 300 and the slit dies 64a and 64b.
[0041]
Thus, by providing the rectifying pillars at the center of the shim, the amount of paste discharged at the center of the current collector sheet can be suppressed, and the influence of the tension applied to the current collector sheet can be reduced. The swelling at the center can be suppressed. For this reason, it is possible to uniformly apply the paste to the current collector sheet.
[0042]
FIG. 10 is a modified example of the shim. The shim 304 includes rectifying columns 306, 308, 310. As described above, a plurality of rectifying columns may be provided, and the rectifying effect is optimized by changing the number of rectifying columns or changing the offset L according to conditions such as the width of the current collector sheet and the viscosity of the paste. It is possible to make.
[0043]
FIG. 11 is a schematic view showing a die coating apparatus 16 according to still another embodiment. FIG. 12 is a perspective view near the slit die 66. Since the basic configuration of the die coating apparatus 16 is the same as that of FIG. 1, the description of the same configuration will be omitted. On the drying furnace 70 side of the paste discharge port of the slit die 66, an air nozzle 400 for ejecting air sent from the blower 404 is provided. The air ejected from the air nozzle 400 hits the surface of the current collector sheet 20. The amount of air ejected from the air nozzle 400 can be adjusted by the air valve 402. The air valve 402 is controlled by the control unit 406. Specifically, as shown in FIG. 12, the air nozzle 400 includes air nozzles 400a to 400d, and the air nozzles 400a to 400d are provided with air valves 402a to 402d, respectively. Therefore, the amount of air jet from the air nozzles 400a to 400d can be controlled independently.
[0044]
The coating thickness sensor 408 detects the thickness of the coating on the back surface of the current collector sheet 20 that has come out of the drying furnace 70. The coating film thickness is detected at a plurality of locations in the width direction of the current collector sheet 20. Information on the detected coating film thickness is transmitted to the control unit 406.
[0045]
The control unit 406 controls the air valves 402a to 402d based on the information about the coating film thickness from the coating film thickness sensor 408, and adjusts the amount of air jetted from the air nozzles 400a to 400d. Specifically, the air ejection amount is increased in a portion where the coating thickness is large in the width direction of the current collector sheet 20, and conversely, the air ejection amount is decreased in a portion where the coating thickness is small. To do.
[0046]
Thereby, as shown in FIG. 13, the paste is uniformly applied in the width direction of the current collector sheet 20, and uneven coating is prevented.
[0047]
A die coating device 18 shown in FIG. 14 is a modified example of the die coating device 16 of FIG. In the die coating device 18, an air nozzle 500 and an angle changing device 502 are provided instead of the air nozzles 400a to 400d and the air valves 402a to 402d. The air nozzle 500 specifically includes air nozzles 500a to 500d provided at predetermined intervals in the width direction of the current collector sheet 20, as shown in FIG. The air sent from the blower 404 is blown toward the surface of the current collector sheet 20 from each of the air nozzles 500a to 500d.
[0048]
The angle of the air nozzle 500 can be changed by an angle changing device 502. The angle changing device 502 is controlled by the control unit 406.
[0049]
The control unit 406 controls the angle changing device 502 based on the information about the coating film thickness from the coating film thickness sensor 408, and adjusts the amount of air blown from the air nozzles 500a to 500d onto the surface of the current collector sheet 20. Specifically, when there is a portion where the coating film thickness is large in the width direction of the current collector sheet 20, the direction in which the air nozzle is moved away from the current collector sheet 20 so that the amount of air blown to that portion is reduced. Next, the angle of the air nozzle 500 is changed.
[0050]
As a result, the paste is uniformly applied in the width direction of the current collector sheet 20, and coating unevenness is prevented.
[0051]
The air nozzles 400 and 500 may be provided above the surface of the current collector sheet 20 before the paste is applied by the slit die 66.
[0052]
【The invention's effect】
As is clear from the above description, according to the present invention, after coating on one sheet surface by die coating, when coating on the other sheet surface, it is possible to prevent dripping of the paste coated end. Can be.
[0053]
In addition, when coating on one sheet surface by die coating and then coating on the other sheet surface, a paste coating in the sheet width direction can be uniformly performed.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a die coating apparatus 10 according to an embodiment.
FIG. 2 is a perspective view of a slit die 60.
FIG. 3 is a sectional view of a slit die 60.
FIG. 4 is a schematic view showing a die coating apparatus 12.
FIG. 5 is a perspective view of a slit die 62.
FIG. 6 is a schematic view showing a die coating apparatus 14.
FIG. 7 is a perspective view of a slit die 64.
FIG. 8 shows an AA ′ cross-sectional view of the shim 300.
FIG. 9 is a sectional view of the slit die 64a taken along the line BB '.
FIG. 10 shows an AA ′ cross-sectional view of the shim 304.
FIG. 11 is a schematic view showing a die coating apparatus 16;
FIG. 12 is a perspective view of the vicinity of a slit die 66.
FIG. 13 is a view showing a state of back surface coating by the die coating device 16;
FIG. 14 is a schematic view showing a die coating apparatus 18.
FIG. 15 is a diagram showing a state of back surface coating by the die coating device 18;
FIG. 16 is a view showing dripping of a paste edge caused by conventional die coating.
[Explanation of symbols]
10, 12, 14, 16, 18 die coating device, 20 current collector sheet, 30 unwinding section, 40 back roller, 42 tank, 44, 46 pump, 48 vacuum pump, 50, 60, 62, 64, 66 slit Die, 52, 54, 56 Roller, 61 Holder, 63 Paste Discharge Port, 70 Drying Furnace, 80 Winding Unit, 100 Suction Hole, 102, 300, 304 Shim, 302, 306, 308, 310 Rectification Column, 400,500 air nozzle, 402 air valve, 404 blower, 406 control unit, 408 coating thickness sensor, 502 angle changing device.

Claims (10)

A first die for applying a first coating liquid to one surface of the sheet,
A second die for applying a second coating liquid to the other surface of the sheet after the application by the first die,
The second die, a holding portion for holding both ends of the sheet,
A discharge port for discharging the coating liquid,
Wherein the discharge port is a concave portion with respect to the holding portion. A first die for applying a first coating liquid to one surface of the sheet,
A second die for applying a second coating liquid to the other surface of the sheet after the application by the first die,
The said 2nd die is provided with the suction part which suctions the said sheet | seat behind the discharge opening which discharges a coating liquid, The die coating apparatus characterized by the above-mentioned. A first die for applying a first coating liquid to one surface of the sheet,
A second die for applying a second coating liquid to the other surface of the sheet after the application by the first die,
The die coating apparatus according to claim 1, wherein the second die includes at least one rectifying unit in a flow path of the coating liquid. The die coating apparatus according to claim 3, wherein the rectifying unit is provided at a center of the flow channel. A first die for applying a first coating liquid to one surface of the sheet,
A second die for applying a second coating liquid to the other surface of the sheet after the application by the first die,
A blower for blowing gas to the sheet, in the sheet advancing direction or behind the discharge port of the second die,
A film thickness detection unit that detects a film thickness of the second coating liquid in the sheet width direction,
The ejection amount control unit controls an ejection amount of the gas in the sheet width direction according to a film thickness of the second coating liquid in the sheet width direction detected by the film thickness detection unit. A control unit;
A die coating apparatus comprising: A die coating method in which a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. hand,
In the application by the second die, applying a second coating liquid to the sheet in a state in which a discharge port for discharging the coating liquid to a holding unit that holds the sheet at both ends is a concave portion. Die coating method characterized. A die coating method in which a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. hand,
In the application by the second die, the second coating liquid is applied to the sheet in a state where the sheet is suctioned to the second die in the sheet advancing direction or behind the discharge port for discharging the coating liquid. A die coating method comprising: A die coating method in which a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. hand,
In the application by the second die, a second coating liquid is applied to the sheet in a state where at least one rectifying section is provided in the flow path of the coating liquid of the second die. Coating method. The die coating method according to claim 3, wherein the rectifying unit is provided at a center of the flow path. A die coating method in which a first coating liquid is applied to one surface of a sheet using a first die, and then a second coating liquid is applied to the other surface of the sheet using a second die. hand,
Detecting the coating thickness of the second coating liquid in the sheet width direction,
The second coating liquid is applied in a state where the gas whose ejection amount in the sheet width direction is controlled is sprayed in the sheet advancing direction or the rear of the ejection port of the second die in accordance with the detected coating film thickness. Is applied to the sheet.

Images