JP2007222711A - Agitator, slurry manufacturing apparatus using the agitator, and manufacturing method of slurry using the slurry manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agitator capable of manufacturing slurry that powder is promptly sucked into a solvent and that the incorporation of foam into slurry is reduced when the powder raw material of slurry is charged from the upper part of the surface of liquid, to provide a slurry manufacturing apparatus using the agitator, and to provide a manufacturing method of slurry using the slurry manufacturing apparatus. <P>SOLUTION: In the agitator 7 consisting of an agitation shaft 3 and an agitation blades 4, 5, 6 the lateral cross-sectional profile of the agitation blade 4 located at the uppermost stage forms the triangle having the vertical angle 4a and the base 4b, and the lateral cross-sectional profile of the agitation blade 4 has such a constitution that the agitation blade 4 can be replaced to the agitation shaft 3 by converting the profile between the state of right triangle in which the vertical angle 4a is located upward and the base 4b is located downward and the state of inverse triangle in which the vertical angle 4a is located downward and the base 4b is located upward. When the slurry is manufactured, the powder raw material is charged into water while the agitation is performed with the state that the lateral cross-sectional profile of the agitation blade 4 is inverse triangle and after charging the powder raw material the agitation is performed with the state that the lateral cross-sectional profile of the agitation blade 4 is right triangle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a stirrer, a slurry manufacturing apparatus using the stirrer, and a slurry manufacturing method using the slurry manufacturing apparatus, and in particular, a method for manufacturing a slurry for forming an electrode for an electrochemical element and a method for manufacturing the slurry. The present invention relates to a slurry production apparatus that can be used directly.

  As an example of a method for producing a slurry, for example, in a method for producing a slurry for an electrode of an electrochemical element such as a lithium secondary battery, a binder, an electrode active material, and a conductive material added as necessary are dissolved or suspended in water. There is a method of making a slurry. (For example, refer to Patent Documents 1 and 2). The slurry is used not only in the production of electrochemical elements such as lithium secondary batteries, but also in the production of pharmaceuticals, cosmetics and the like.

  Moreover, as a manufacturing apparatus of a slurry, there exists a thing of the structure demonstrated below (for example, refer patent document 3). In FIG. 8, the structure of the conventional slurry manufacturing apparatus is shown. Note that the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG.

  The slurry manufacturing apparatus shown in FIG. 8 is installed at the bottom of the stirring tank 1, the stirring tank 1 for storing the processing object to be stirred, the stirrer 31 and the homogenizer 9 for stirring the processing object in the stirring tank 1. And a hopper 36 for charging the slurry powder raw material.

  The stirrer 31 is provided on the stirring shaft 32 that serves as a rotating shaft, the stirring blade 33 that rotates the stirring target 32 by rotating around the stirring shaft 32, and the slurry on the wall surface of the stirring tank. The adhesion prevention part 33a which prevents adhesion | attachment of this, the gear box 34 for rotating the stirring shaft 32, and the motor 35 are provided.

  The homogenizer 9 has a tooth-like rotor 9a and a stator 9b arranged concentrically, and sucks and pushes out the object to be stirred by the turbulence effect accompanying the rotation of the rotor.

  The hopper 36 is for supplying a powder raw material to the inside of the stirring tank 1, and is a powder injection port 36a into which the powder raw material is injected, and a raw material through which the powder injected from the powder injection port 36a flows. It has a supply pipe 36b and a raw material supply valve 36c that is provided in the raw material supply pipe 36b and opens and closes the raw material supply pipe 36b, and is connected to a powder inlet 36d provided near the homogenizer 9 of the stirring tank 1. Has been.

Although not shown, there is a stirring blade having a triangular cross-sectional shape unlike the stirring blade 33 included in the slurry manufacturing apparatus shown in FIG. 8 (see, for example, Patent Document 4).
Japanese Patent No. 3692965 JP 2005-85557 A Japanese Patent Laid-Open No. 2001-300280 Japanese Utility Model Publication No. 61-27627

  In the slurry production apparatus shown in FIG. 8, the powder inlet 36d is provided at the bottom of the agitation tank 1, and the powder inlet 36d is near the homogenizer 9, so that the binder (increase) is supplied from the powder inlet 36d. For example, when a high molecular weight water-soluble organic compound is used as the (viscous agent), the water-soluble organic compound and oxygen in the bubbles contained in the slurry are vigorously stirred by the homogenizer 9, and the water-soluble organic compound The molecular weight is reduced, causing a problem that it does not function as a thickener.

  Therefore, when the present inventors examined this countermeasure, it was found that the problem can be solved by changing the installation location of the powder inlet to the upper part of the stirring tank and taking the distance between the homogenizer and the powder inlet. I found it.

  However, when the position of the powder inlet is changed to the upper part of the stirring tank 1 with respect to the slurry manufacturing apparatus shown in FIG. 8, the powder raw material is supplied from above the solvent, and the powder raw material is put in the solvent with the stirring blade. As a result, the powder raw material is less likely to be sucked into the slurry as compared with the case before the change, which causes a problem that the powder charging time becomes longer.

  Here, as for the former problem, as an example of the reason why the powder inlet is provided in the upper part of the stirring tank, the problem in the case where the slurry manufacturing apparatus has a homogenizer has been described. However, the slurry manufacturing apparatus has a homogenizer. Even when the powder is not provided, there is a problem that the powder charging time becomes long when the powder charging port is provided in the upper part of the stirring tank.

  Further, it is desirable that the produced slurry does not contain bubbles.

  In addition, the method of changing the stirring blade 33 of the slurry manufacturing apparatus of the structure shown in FIG. 8 into the stirring blade whose cross-sectional shape is a triangle as shown in patent document 4 can be considered. However, as described in FIG. 1 of Patent Document 4, in the case where the cross-sectional shape of the stirring blade is a forward triangle and the stirring blade is always fixed to the stirring shaft in the same state, the stirring blade causes Since the flowing water is always upward, the suction of the powder is slow when the powder is introduced from above the water surface. Further, as described in FIGS. 2 and 5 of Patent Document 4, when the stirring blade has a portion with a different cross-sectional shape in the longitudinal direction, the water flow caused by the stirring blade is complicated. Therefore, it is suitable for stirring the slurry in which the powder has already been charged, but is not suitable for stirring in the powder charging stage.

  In view of the above points, the present invention provides a stirrer that can produce a slurry in which the powder is rapidly sucked into the solvent and contains less bubbles when the slurry powder raw material is introduced from above the liquid surface. Is the first purpose. A second object is to provide a slurry production apparatus using this stirrer. A third object is to provide a slurry production method using this slurry production apparatus.

  In order to achieve the above object, the stirrer of the present invention includes a stirring blade (4) fixed to the stirring shaft (3) and extending linearly from the stirring shaft (3) to the measurement of the stirring shaft. The stirring blade (4) has the same cross-sectional shape for the entire stirring blade, and the stirring target is processed when the stirring target is stirred by rotating about the stirring shaft (3). On the other hand, it has a surface that creates a flow in the direction of gravity or anti-gravity. The stirring blade (4) and the stirring shaft (3) are in a state in which the stirring blade (4) is removed from the stirring shaft (3) and a flow in the direction of gravity is created with respect to the workpiece to be stirred. On the other hand, it is characterized in that it has a structure in which the stirring blade (4) can be replaced with the stirring shaft (3) by changing between the state of creating a flow in the antigravity direction.

  In the present invention, since the stirring blade (4) can be replaced with the stirring shaft (3) in this way, the liquid flow generated by the stirring blade can be reduced by replacing the stirring blade (4) with the stirring shaft (3). The direction can be changed between the direction of gravity and the direction of antigravity. For this reason, if this stirrer is used in the production of the slurry, when the powder raw material of the slurry is introduced from above the liquid surface, the powder is quickly sucked into the solvent, and a slurry with less bubbles is produced. Can do.

  In the present invention, the number of stirring blades fixed to the stirring shaft is not limited to one, but includes a plurality of cases. When a plurality of stirring blades are fixed to the stirring shaft by changing the positions in the height direction, it is preferable that at least the uppermost stirring blade has such a structure.

  Specifically, the cross-sectional shape of the stirring blade (4) is, for example, a triangle having an apex angle (4a) and a base (4b), and the cross-sectional shape of the stirring blade (4) is the apex angle (4a). The stirring blades (4) are changed between a forward triangular state where the base (4b) is located above and an inverted triangle where the apex angle (4a) is located below and the bottom (4b) is located above. ) To the stirring shaft (3).

  Moreover, the manufacturing method of the slurry of this invention fixes a stirring blade (4) to the stirring shaft (3) in the state which can make the flow of a gravitational direction with respect to a to-be-stirred process thing, and in a stirring tank (1), After water is introduced so that the water surface is positioned above the stirring blade (4), the stirring shaft (3) is rotated to cause a water flow in the direction of gravity near the water surface, and the slurry powder raw material in the water After the step of supplying the powder and the step of supplying the powder raw material, the stirring blade (4) is detached from the stirring shaft (3), and the stirring blade (4) can be made to flow in the antigravity direction with respect to the stirring target. After changing the state into a state where the stirring blade (4) is replaced with the stirring shaft (3) and the step of replacing the stirring blade with the stirring shaft, the stirring shaft (3) is rotated so that the anti-gravity direction is near the water surface. A step of removing bubbles present in the slurry by causing a water flow of It is.

  Thereby, in the step of supplying the slurry powder raw material to the water, the step of facilitating the introduction of the powder at the start of slurry production and the removal of bubbles, compared to the case where the water flow in the direction of gravity is not generated near the water surface Then, compared with the case where the water flow of the antigravity direction does not occur near the water surface, bubbles can be easily removed.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
In FIG. 1, the whole structure of the slurry manufacturing apparatus in 1st Embodiment of this invention is shown.

As shown in FIG. 1, the slurry manufacturing apparatus of the present embodiment includes a stirring tank 1 that accommodates an object to be stirred, a hopper 2 provided on the top of the stirring tank 1, a stirring shaft 3, and a stirring blade 4. 5 and 6, a pump 8 disposed at the bottom of the stirring tank 1, and a homogenizer 9 disposed below the stirring tank 1 with respect to the pump 8.
And a circulation path 10 that connects the bottom and the top of the stirring tank 1.

  The stirring tank 1 has, for example, a shape in which a cylindrical portion 1b having a small diameter is connected to a lower side of a cylindrical portion 1a having a large diameter, and includes an upper surface 1c, a side surface 1d constituting the upper cylindrical portion, and a tapered surface 1e. , And has a side surface 1f constituting a lower cylindrical portion and a bottom surface 1g. Inside the upper cylindrical portion 1a, stirring blades 4, 5, and 6 are arranged. Inside the lower cylindrical portion 1b, a pump 8 and a homogenizer 9 are arranged.

  The hopper 2 guides the powder raw material of the slurry to the inside of the stirring tank 1 and communicates with an opening 11 provided on the upper surface 1 c of the stirring tank 1. By introducing the powder raw material into the hopper 2 from the opening 2 a of the hopper 2, the powder raw material is introduced into the stirring tank 1 from the opening 11 of the upper surface 1 c of the stirring tank 1. In the present embodiment, the position of the hopper 2 is located above the upper stirring blade 4, and the powder raw material can be introduced into the uppermost surface (liquid surface) of the liquid stored in the stirring tank 1. Is in position.

  The homogenizer 9 disperses the powder raw material in water. In the slurry manufacturing apparatus shown in FIG. 1, for example, a homogenizer 9 including a rotor 9a and a stator 9b is used. The rotor 9a rotates when power is applied from the motor 12 to the rotary shaft 13. Note that an ultrasonic homogenizer may be used instead of the homogenizer constituted by the rotor 9a and the stator 9b.

  The pump 8 creates a water flow from the upper cylindrical portion 1a to the lower cylindrical portion 1b of the agitation tank 1, and is composed of, for example, a disk-shaped pump blade 8. The pump blade 8 is fixed to the rotating shaft 13 of the rotor 9a, and the rotor 9a is rotated by the motor 12 so as to generate a water flow. Thereby, a slurry can be sent to the homogenizer 9 and the circulation path 10 from the upper cylindrical part 1a. In addition, when such a water flow is made by the stirring blade, the pump 8 may be omitted.

  The circulation path 10 communicates with the extrusion port 9c of the object to be stirred of the homogenizer 9 and the upper cylindrical portion 1a of the stirring tank 1 in the lower cylindrical part 1b of the stirring tank 1, and the slurry is stirred in the stirring tank 1 This is a path for circulating between the upper cylindrical portion 1a and the lower cylindrical portion 1b. The circulation path 10 is provided with a take-out path 10a for taking out the slurry from the slurry production apparatus and a valve 10b for opening and closing the take-out path.

  The agitator 7 is a reciprocating rotary type in which the rotation direction of the agitation shaft 3 is not unidirectional but is rotated in one direction, for example, 90 °, and then in the opposite direction. The agitation shaft 3 and the agitation blades 4, 5, 6 In addition, it has a gear box 14 for reciprocating the stirring shaft 3, a reciprocating rotation belt 15, and a motor 16, and the power from the motor 16 passes through the reciprocating rotation gear box 14 and the reciprocating rotation belt 15. , Transmitted to the stirring shaft 3. The stirrer 7 has a compressor 17 that communicates with the stirring shaft 3.

  The stirring shaft 3 is a portion serving as a rotation shaft of the stirring blades 4, 5, 6 and extends in the vertical direction.

  The stirring blades 4, 5, and 6 are disposed inside the upper cylindrical portion 1 a of the stirring tank 1, and rotate the stirring shaft 3 as a rotation axis, thereby the object to be stirred in the stirring tank 1 is rotated. Stirring. In the present embodiment, the stirring blades are fixed to the stirring shaft 3 at the upper, middle, and lower three-stage positions. Each stirring blade 4, 5, 6 extends linearly in a direction perpendicular to the stirring shaft 3 from the stirring shaft 3, for example, in the direction perpendicular to the stirring shaft 3. The stirring blade 5 located, the stirring blade 5 located in the middle stage, and the stirring blade 6 located in the lower stage are arranged orthogonal to each other when viewed in a direction parallel to the stirring shaft 3. In addition, the stirring shaft 3 and the stirring blades 4, 5, and 6 are made of metal, for example.

  2 and 3 show cross sections of the stirring blades 4, 5 and 6. As shown in FIGS. 2 and 3, the stirring blades 4, 5, 6 have a cross-sectional shape that is a plane perpendicular to the extending direction of the stirring blades, and the shape of each of the stirring blades 4, 5, 6 is the same. For example, it is an equilateral triangle.

  Specifically, as shown in FIG. 2, the agitating blade 5 at the middle stage has a forward triangle in which the apex angle 5a is on the top and the base 5b is on the bottom, as shown in FIG. In this case, a water flow in the antigravity direction is created in the stirring tank 1 by the surfaces constituting the two sides 5c and 5d forming the apex angle 5a.

  Further, as shown in FIG. 3, the lower stirring blade 6 has an inverted triangle in which the cross-sectional shape is an apex angle 6a at the bottom and the base 6b at the top, and when the stirring blade 6 rotates, A water flow in the antigravity direction is created by the surfaces constituting the two sides 6c and 6d forming the apex angle 6a. The middle and lower stirring blades 5 and 6 have a structure that cannot be detached from the stirring shaft 3.

  In addition, the upper stirring blade 4 has a structure that can be detached from the stirring shaft 3, and can be replaced with the stirring shaft 3 by inverting the cross-sectional shape of the stirring blade 4 up and down as will be described later. It has a simple structure. As shown in FIG. 2, the cross-sectional shape of the upper stirring blade 4 is a forward triangle in which the apex angle 4a is located on the upper side and the base 4b is located on the lower side, or as shown in FIG. 4b is an inverted triangle located on the upper side. For this reason, when the upper stirring blade 4 rotates, a water flow in the gravity direction or the antigravity direction is created by the surfaces constituting the two sides 4c and 4d forming the apex angle 4a.

  Next, a fixing mechanism between the upper stirring blade 4 and the stirring shaft 3 and a method of replacing the upper stirring blade 4 will be described. FIG. 4 shows a cross-sectional view of a region A surrounded by a broken line in FIG. 5A to 5E show a procedure for replacing the upper stirring blade 4 with the stirring shaft 3.

  As shown in FIG. 4 and FIG. 5C, the stirring shaft 3 has a convex portion 3 a as a fitting portion to be fitted to the stirring blade 4 at a fixed portion of the upper stirring blade 4. FIG. 5C shows a state where the upper stirring blade 4 is detached from the stirring shaft 3. The inside of the convex portion 3a is hollow, and a piston 21 and a spring 22 are provided inside the convex portion 3a. The piston 21 can move such as protruding upward from the inside of the convex portion 3a or returning to the inside of the convex portion 3a.

  And the stirring shaft 3 is hollow from the convex part 3a to the connection part 3c with the compressor 17, and the piston 21 is driven by the air pressure supplied from the compressor 17 connected to the connection part 3c via the resin hose 18. The upper surface 3b (see FIG. 5C) of the convex portion 3a moves upward. The spring 22 is fixed to the inside of the convex portion 3a and the piston. When the compressor 17 is stopped by this spring, the convex portion 3a is opposed to the piston protruding upward from the inside of the convex portion 3a. The power to return to the inside of is to work.

  The upper stirrer blade 4 has a concave portion 4a at the base thereof, which has a shape corresponding to the convex portion 3a of the stirring shaft 3 and is fitted to the convex portion 3a. Furthermore, this recessed part 4a has the recessed part 4b smaller than the recessed part 4a corresponding to the piston 21 on the inner side upper side and the lower side. Further, at the tip of the stirring blade, there is a screw hole 1 for attaching a rotating shaft used when the stirring blade 4 is turned upside down.

  As shown in FIG. 4, in a state where the concave portion 4 a of the upper stirring blade 4 is fitted to the convex portion 3 a of the stirring shaft 3, the piston 21 is moved by the air pressure (compressed air) supplied from the compressor 17. The stirring blade 4 is fixed by being pressed against the small concave portion 4 b of the stirring blade 4. That is, the piston 21 is caught in the small recess 4 b so that the stirring blade 4 does not come off the stirring shaft 3. Further, when the piston 21 is lowered, the stirring blade 4 can be inserted and removed from the stirring shaft 3.

  When the upper stirring blade 4 is replaced with the stirring shaft 3, the stirrer 7 is moved above the stirring tank 1 and the upper stirring blade 4 is moved out of the stirring tank 1. Subsequently, as shown in FIG. 5A, the reversing shaft 24 supported by the support portion 23 is inserted into the screw hole 4 c of the upper stirring blade 4.

  Subsequently, the compressor 17 is stopped as shown in FIG. Thereby, since the pressure applied to the piston 21 is released, the piston 21 is lowered toward the inside of the convex portion 3 a of the stirring shaft 3 by the spring 22. As a result, the fixing of the stirring blade 4 to the stirring shaft 3 is released.

  Subsequently, as shown in FIG. 5 (c), the stirring blade 4 is separated from the stirring shaft 3 by pulling the reversing shaft 24 in a direction away from the stirring shaft 3.

  Subsequently, as shown in FIG. 5 (d), the reversing shaft 24 is supported by the support portion 23, and the stirring blade 4 is rotated by 180 ° about the reversing shaft 24. It is reversed up and down around the longitudinal direction.

  Subsequently, as shown in FIG. 5 (e), the reversing shaft 24 is pushed toward the stirring shaft 3, and the concave portion 4 a of the stirring blade 4 is fitted into the convex portion 3 a of the stirring shaft 3. Thereafter, the compressor 17 is operated, and the piston 21 is raised by applying air pressure to the piston 21. Thereby, the stirring blade 4 turned upside down can be firmly fixed to the stirring shaft 3. The above-described work such as insertion and rotation of the reversing shaft 24 into the stirring blade is performed by a person or a machine.

  Thus, the stirrer 7 of this embodiment has a structure that allows the upper stirring blade 4 to be easily turned upside down.

  Next, the manufacturing method of the slurry performed using the slurry manufacturing apparatus having the above structure will be described. In the present embodiment, a method for producing an electrode slurry for a lithium secondary battery will be described as an example. The slurry for the electrode of the lithium secondary battery includes water as a solvent, powdery carbon as a powder raw material of the slurry, and a powdery water-soluble organic compound that functions as a binder and a surfactant, A powdered electrode active material and a liquid aqueous dispersion resin as a binder (particle adhesive) are dissolved or suspended.

  Here, as carbon, for example, amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), carbonaceous materials such as pitch-based carbon fiber, carbon fiber, activated carbon, carbon black, carbon nanotube, carbon nanohorn, fullerene Carbon airgel or the like can be used.

  Examples of the water-soluble organic compound include celluloses such as methylcellulose (MC), carboxymethylcellulose (CMC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylmethylcellulose (HPMC), and hydroxyethylmethylcellulose (HEMC). , Polyacrylate, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone, acrylic acid or a copolymer of acrylate and vinyl alcohol, maleic anhydride, maleic acid or fumaric acid and vinyl alcohol Copolymer, modified polyvinyl alcohol, modified polyacrylic acid, polyethylene glycol, polycarboxylic acid, oxidized starch, phosphate starch, casein, various modified starches, chitin Polymeric materials such as chitosan derivatives can be used. Two or more of these materials can be used in combination.

Examples of the active material include lithium-containing composite metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , and LiMn ₂ O ₄ , transition metal sulfides such as TiS ₂ , TiS ₃ , and amorphous MoS ₃ , Transition metal oxides such as Cu ₂ V ₂ O ₃ , amorphous V ₂ O—P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ , and conductive such as polyacetylene and poly-p-phenylene Conductive polymers, amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), carbonaceous materials such as pitch-based carbon fibers, conductive polymers such as activated carbon and polyacene, metal oxides such as ruthenium oxide (RuO ₂ ) Can be used.

  Examples of the aqueous dispersion resin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene. Fluororesin-based resins such as oloethylene-ethylene copolymer (ETFE) and tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPE), acrylic resins, diene polymers and hydrogenated products thereof, Olefins such as polyethylene and polyolefin, polyimide resin, polythiophene, polyacetylene, poly (2,5-pyridinediyl), poly-p-phenylene, polyaniline, poly (P-phenylene), polyphenylenes Fido, polyphenylene oxide, polypyrrole, polyacene, may be used polyazulene, polyphenylene vinylene and water-dispersible type resins such as these derivatives.

  First, a step of introducing carbon, a water-soluble compound, and an electrode active material (hereinafter referred to as carbon) into water is performed.

  In this step, in the slurry production apparatus described above, the cross-sectional shape of the upper stirring blade 4 is in an inverted triangular state in which the apex angle 4a is at the bottom and the base 4b is at the top, as shown in FIG. The upper stirring blade 4 is fixed to the stirring shaft 3.

  Then, water is poured into the stirring tank 1. At this time, the height of the water is a height at which the water surface is located above the upper stirring blade 4. Subsequently, when the operation of the stirrer 7 is started and the reciprocating rotation is performed about the stirring shaft 3, the cross section of the upper stirring blade 4 is an inverted triangle. Therefore, in the vicinity of the water surface, as shown in FIG. Happens. In the state where the water flow in the direction of gravity occurs, carbon or the like is supplied to the opening 2a of the hopper 2 to supply carbon or the like to the water from the powder inlet 11 of the stirring tank 1.

  Thereby, compared with the case where the water flow of a gravitational direction has not occurred, carbon etc. can be sucked into water early. In particular, since the carbon used in the present embodiment has water repellency, it is difficult for carbon to be sucked into water when there is no gravity flow, but according to the present embodiment, carbon is sucked into water. Becomes easy.

  After the introduction of carbon or the like is completed, the stirrer 7 is stopped and the upper stirring blade 4 is turned upside down. In this step, by replacing the upper stirring blade 4 with the stirring shaft 3 by the above-described method of replacing the stirring blade, the cross-sectional shape of the upper stirring blade 4 is as shown in FIG. And a forward triangle with the base 4b positioned below.

  Thereafter, a step of removing bubbles from the slurry is performed. In this step, the operation of the stirrer 7 is started again and reciprocally rotated around the stirring shaft 3. At this time, since the cross section of the upper stirring blade 4 is a forward triangle, a water flow in an antigravity direction occurs near the water surface as shown in FIG. Thereby, bubbles can be taken out from the liquid surface and removed from the slurry.

  Then, after removing bubbles of 100 μm or more, more preferably 50 μm or more, a step of supplying an aqueous dispersion resin is performed. In this step, the slurry is fed into the slurry containing carbon or the like from the powder inlet 11 by being supplied to the opening 2 a of the hopper 2.

  Here, the aqueous dispersion resin has flexibility and excellent electrolytic solution resistance. From this, at the time of manufacturing a lithium secondary battery, which will be described later, the electrode can be made flexible, and by giving the flexibility, the composite material when handling or winding the sheet-like positive electrode It is possible to prevent damage to the electrode due to cracking or falling off of the layer. In addition, the electrode can be made resistant to an electrolytic solution, and swelling and dissolution of the electrolytic solution can be prevented, and damage to the electrode can also be prevented.

  However, the aqueous dispersion resin has a surfactant on the surface, and this surfactant is often foamable. For this reason, the aqueous dispersion resin cannot be introduced into the slurry in which bubbles are present.

  On the other hand, bubbles of at least 100 μm or more can be eliminated by stirring the slurry in the stirring tank 1 by the upper stirring blade 4 whose cross section is a forward triangle. For this reason, according to this embodiment, an aqueous dispersion resin can be easily added to the end.

  Note that, between the step of removing bubbles and the step of supplying the aqueous dispersion resin, the upper stirring blade 4 is removed from the stirring shaft 3, the cross-sectional shape is changed to an inverted triangle, and the stirring blade 4 is The process of changing to the stirring shaft 3 is performed. Accordingly, the aqueous dispersion resin can be supplied to the water while causing a water flow in the direction of gravity near the water surface. Here, the process of replacing the stirring blade 4 with the stirring shaft 3 has been described, but this process may be omitted.

  As described above, in the present embodiment, in the step of supplying carbon or the like to the water, the carbon or the like is supplied to the water in a state where a water flow in the direction of gravity occurs near the water surface. In the step of removing the bubbles, the bubbles can be easily removed because an anti-gravity water flow is generated near the water surface.

  Moreover, in this embodiment, the powder inlet 11 is provided in the upper part of the stirring tank 1, and the water-soluble organic compound is injected | thrown-in from the upper direction of water. Thus, by taking the distance between the homogenizer 9 and the powder inlet 11, as shown in FIG. 8, it is contained in the slurry as compared with the case where the distance between the homogenizer 9 and the powder inlet 36 d is short. It can suppress that oxygen in a bubble is stirred strongly and the molecular weight of a water-soluble organic compound reduces.

  Further, the stirrer 7 of the present embodiment is of a reciprocating rotary type and has high stirring performance. Therefore, when powder is charged, the powder remaining without stirring at the time of powder charging is the wall surface of the stirring tank 1 and the stirring shaft. It is possible to suppress local existence near the interface between the liquid surface 3 and the liquid surface.

In this embodiment, a pump 8 and a homogenizer 9 are provided at the bottom of the stirring tank 1.
And a circulation path 10 that connects the workpiece outlet of the homogenizer 9 and the stirring tank 1 is provided. Thereby, compared with the case where these are not provided, the stirring time can be reduced significantly. In addition, when the dispersibility derived from the material of the slurry is high, a slurry manufacturing apparatus in which the homogenizer 9 and the circulation path 10 are omitted may be used.

  Next, the manufacturing method of the electrochemical element using the slurry of this embodiment is demonstrated. Here, a case where a cylindrical lithium secondary battery is manufactured as an electrochemical device will be described as an example.

  First, the process of manufacturing a sheet-like positive and negative electrode is performed. In this step, a slurry mixture is prepared by the above-described slurry manufacturing method, and the mixture slurry is applied to a substrate surface such as an appropriate current collector and dried, so that a sheet-like positive electrode containing carbon and A negative electrode is manufactured. At this time, the slurry is applied with a thin film of, for example, 100 μm or less. In this embodiment, since the carbon-containing slurry produced by the above-described production method is used, even in a thin film having a thickness of 100 μm or less, it is possible to produce a high-quality electrode with uniform dispersion of carbon and no coating streaks due to aggregation.

  Thereafter, a battery assembly process is performed. In this step, the positive electrode and the negative electrode are laminated with a microporous polyethylene film as a separator interposed therebetween, and wound around a spiral mold to produce an electrode body, and then with an electrolyte prepared in advance. A lithium secondary battery is manufactured by enclosing it in a case. In addition, a well-known thing can be used as electrolyte solution and a separator. Here, the case where the shape of the lithium secondary battery is a cylindrical shape has been described as an example, but the shape is not particularly limited, and various shapes such as a coin shape and a square shape can be used.

  The lithium secondary battery manufactured in this manner has a large manufacturing variation when the dispersibility of the carbon in the slurry is poor. Since the carbon-containing electrode in which the carbon is uniformly dispersed is used, the manufacturing variation is The effect is small and productivity can be improved.

  Examples and comparative examples are shown below.

  As Examples and Comparative Examples of the present invention, a stirrer, a slurry production apparatus, a slurry, an electrode, and an electrochemical element were produced.

Example 1
(1) Configuration of Slurry Manufacturing Device The slurry manufacturing device has the structure shown in FIG. 1 described in the first embodiment. The middle and lower stirring blades 5 and 6 are made by Shimazaki Seisakusho, the pump blade 8 is made by IKA: 2P, and the homogenizer 9 is composed of a rotor 9a and a stator 9b, and made by IKA: 6F. In the initial stage of slurry production, the upper stirring blade 4 has an inverted triangle cross-sectional shape.

(2) Production of positive electrode 87 parts by mass of lithium nickel oxide as a positive electrode active material, 2 parts by mass of activated carbon as carbon, 5 parts by mass of ketjen black (manufactured by Ketjen Black International: ECP), 1 mass of sodium carboxymethylcellulose powder Part and 1 part by mass of polyethylene oxide powder were mixed for 10 minutes to prepare 9600 g of mixed powder.

  And 96 mass parts water was thrown into the slurry manufacturing apparatus. Then, while operating the reciprocating rotary stirrer 7 at 0.2 kW and the peripheral speed of the homogenizer 9 at 20 m / sec, the mixed powder was charged into the stirring tank 1 of the slurry production apparatus at 1000 g / min. Further, the upper stirring blade 4 was moved so as to be always 10 mm below the liquid level in accordance with the movement of the liquid level accompanying the powder charging.

  As a result, the charging of the mixed powder was completed in 9.6 (about 10) min. At this time, the powder in the slurry was well dispersed, the clogging of the circulation path 10 occurred, and there was no problem such as stopping.

  After charging the mixed powder, the upper stirring blade 4 was turned upside down, and the cross-sectional shape was a regular triangle. The upper stirring blade 4 is placed 20 mm below the liquid level, the stirrer 7 is set to 0.2 kW, the peripheral speed of the homogenizer 9 is set to 25 m / sec, and the slurry is defoamed by stirring for 20 minutes. It was.

  Then, PTFE (Daikin Kogyo: D-2CE) having a solid content ratio of about 60% as an aqueous dispersion resin was added so that the solid content was 2 parts by mass, the stirrer 7 was 0.2 kW, the homogenizer 9 The speed was set to 10 m / sec and stirred for 5 minutes to complete the carbon-containing slurry. In addition, the sum total of the solid content at the time of manufacture of a positive electrode was 98.0 mass parts.

The slurry thus obtained was applied onto both sides of an aluminum foil with a comma coater at a weight per unit area of 6.29 (mg / cm ² ), dried, and the positive electrode composite in which carbon was dispersed and the positive electrode composite. A positive electrode sheet carrying the material on an aluminum foil was obtained.

Next, this positive electrode sheet was passed through a roll press to increase the electrode density to 2.10 g / cm ³ . Next, this electrode was cut into a width of 5.4 cm) and a length of 90 cm, and an electrode mixture of 2.5 cm in length was scraped off as a lead tab weld for extracting current. Effective reaction area of the electrode is ^{5.4cm × 87.5cm × 2 = 945cm 2} .

(3) Production of negative electrode The production of the negative electrode mainly differs from the production of the positive electrode in the materials used, and the production method is substantially the same as the production of the positive electrode.

  Specifically, 98 parts by mass of scaly graphite as a negative electrode active material and 1 part by mass of sodium carboxymethyl cellulose powder were mixed for 10 minutes to prepare 4900 g of mixed powder.

  Then, 124.7 parts by mass of water is added to the slurry production apparatus, and the agitator 7 is mixed with the stirring tank 1 of the slurry production apparatus while operating with the peripheral speed of the homogenizer 9 set to 0.4 kW and 20 m / sec. The powder was put into a stirring tank at 500 g / min. At this time, charging was completed in 9.8 min.

  After charging the mixed powder, the upper stirring blade 4 was turned upside down, and the cross-sectional shape was a regular triangle. And deaeration was performed by setting the stirrer 7 to 0.2 kW and the peripheral speed of the homogenizer 9 to 10 m / sec and stirring for 20 minutes.

  Thereafter, SBR (manufactured by ZEON Corporation: AD-1021) having a solid content ratio of about 40% as an aqueous dispersion resin was added so that the solid content was 1 part by mass, the stirrer 7 was 0.4 kW, and the homogenizer 9 The speed was set to 20 m / sec and stirred for 5 minutes to complete the carbon-containing slurry. In addition, the sum total of the solid content at the time of manufacture of a negative electrode was 100.0 mass parts.

Subsequently, the carbon-containing slurry was applied on both sides with a basis weight of 4.29 mg / cm ² on one side of the copper foil using a comma coater in the same manner as the positive electrode. Thereafter, an electrode having an electrode density increased to 1.28 g / cm ³ was produced through a roll press. Next, this electrode was cut into a width of 5.6 cm and a length of 94 cm, and an electrode mixture for a length of 0.5 cm was scraped off as a lead tab weld for taking out the electrode. The effective reaction area of this electrode is 5.6 cm × 93.5 cm × 2 = 1047.2 cm ² .

(4) Assembly of battery The produced sheet-like positive electrode and sheet-like negative electrode were wound with a separator interposed therebetween to form a wound electrode body. A separator made of polyethylene having a thickness of 25 μm was used. The obtained wound electrode body was inserted into the case and held in the case. At this time, the current collecting lead having one end welded to the lead tab welded portion of the sheet-like positive electrode and the sheet-like negative electrode was joined to the positive electrode terminal or the negative electrode terminal of the case. Then, after inject | pouring electrolyte solution in the case where the winding type electrode body was hold | maintained, the case was sealed and sealed.

  A cylindrical lithium secondary battery having a diameter of 18 mm and an axial length of 65 mm was manufactured by the above procedure.

(Example 2)
Example 1 is the same as Example 1 except for the configuration of the slurry production apparatus described below and the method for producing the positive electrode.

(1) Configuration of Slurry Manufacturing Apparatus In the slurry manufacturing apparatus shown in FIG. 1, a liquid vane pump is used instead of the pump blade 8, and an ultrasonic homogenizer (Siebel Hegner Co., Ltd.) is used instead of the homogenizer 9 configured by the rotor 9a and the stator 9b. Example 1 except that UP-200S) was used.

(2) Manufacture of positive electrode Only differences from Example 1 are described. The ultrasonic homogenizer output was 0.2 kW at the time of powder charging and after the charging. The pump pressure was set to 0.3 MPa.

  Moreover, after adding the aqueous dispersion resin, in order to prevent destruction of the aqueous dispersion resin, the ultrasonic homogenizer is not operated, only the stirrer 7 is set to 0.2 kW, and the mixture is stirred for 5 minutes, and the carbon-containing slurry is removed. Completed.

(Example 3)
Example 1 is the same as Example 1 except for the configuration of the slurry production apparatus described below and the method for producing the positive electrode.

(1) Configuration of Slurry Manufacturing Device The slurry manufacturing device has a structure in which the homogenizer 9 and the circulation path 10 are omitted from the slurry manufacturing device shown in FIG. 1, and other configurations are the same as those in the first embodiment.

(2) Production of Positive Electrode The output of the agitator 7 was changed to 0.4 kW with respect to the production method of the positive electrode described in Example 1.

(Comparative Example 1)
Example 1 is the same as Example 1 except for the configuration of the slurry production apparatus described below and production of the positive electrode and the negative electrode.

(1) Configuration of slurry production apparatus Although not shown, instead of the stirrer 7 in FIG. 1, except that a stirrer in which the cross-sectional shape is an inverted triangle and the upper stirrer blade is always fixed to the stirrer shaft is used. The configuration is the same as that of the first embodiment. That is, in Comparative Example 1, the upper stirring blade cannot be turned upside down and the cross-sectional shape is always an inverted triangle.

(2, 3) Manufacture of positive electrode and negative electrode The difference from Example 1 is that the stirrer was operated with the cross-sectional shape of the upper stirring blade as an inverted triangle at the time of defoaming after charging the mixed powder.

(Comparative Example 2)
Example 1 is the same as Example 1 except for the configuration of the slurry production apparatus described below and production of the positive electrode and the negative electrode.

(1) Configuration of slurry production apparatus Although not shown, instead of the stirrer 7 in FIG. 1, except that a stirrer in which the cross-sectional shape is a regular triangle and the upper stirrer blade is always fixed to the stirrer shaft is used. The configuration is the same as that of the first embodiment. That is, in Comparative Example 2, the upper stirring blade cannot be turned upside down and the cross-sectional shape is always a forward triangle.

(2, 3) Manufacture of positive electrode and negative electrode The difference from Example 1 is that when the mixed powder was charged, the agitator was operated with the cross-sectional shape of the upper stirring blade as a forward triangle.

(Comparative Example 3)
Example of the slurry production apparatus except that the slurry production apparatus is of the structure shown in FIG. 8 described in the background art, except that IKA DBI-2000: MP10 was used and the slurry was produced at 0.4 kW of the stirrer. Same as 1.

  Table 1 shows the evaluation of slurry production in Examples 1 to 3 and Comparative Examples 1 to 3, and the evaluation of the slurry and the electrochemical device. In addition, as an evaluation of slurry production, the powder charging time, which is the time until the charging is completed when the powder is charged so that the slurry is not clogged in the circulation path 10, the side wall of the stirring tank 1, and the stirring shaft The presence or absence of the adhesion of the powder to 3 was investigated. As the evaluation of the slurry, the particle gauge and viscosity of the slurry after completion were measured, and the variation in room temperature output was measured as the evaluation of the electrochemical device. Each measuring method is as follows.

(Measurement of grain gauge)
Based on JIS K5600-2-5, the particle size distribution of the dispersion was determined using a double groove grindometer.

(Measurement of viscosity)
Using an E-type viscometer (manufactured by Hakke, Rheostress RS1), the viscosity at a shear rate of 2 sec ⁻¹ was determined.

(Room temperature output)
After the initial discharge capacity measurement, CC-CV charge was performed up to 3.750 V (SOC 60%) at a charge current of 1000 mA while maintaining at 25 ° C. Then, discharge for 10 seconds and charge for 10 seconds in the order of 300 mA, 900 mA, 2.7 A, 5.4 A, and 8.1 A, respectively, and linearly approximate each current value and closed circuit battery voltage. The output was obtained by reading the current value at the point of crossing and multiplying the current value by 3V. All measurements were performed at 25 ° C.

  As shown in Table 1, Examples 1 and 2 in which the cross-sectional shape of the upper stirring blade 4 at the time of charging the powder raw material was an inverted triangle were 5 minutes, and Example 3 It was 10 minutes and was shorter than 15 minutes of Comparative Example 2 which was a forward triangle. From this, it can be seen that when the powder is charged, the powder can be easily charged by making the cross-sectional shape of the upper stirring blade 4 an inverted triangle. The reason why Example 3 is longer than Examples 1 and 2 is that the homogenizer 9 is not provided.

  Regarding the particle gauge, Examples 1 to 3 in which the cross-sectional shape of the upper stirring blade 4 was a regular triangle after the powder raw material was charged were 65, 50, and 80 μm, respectively. On the other hand, even after the powder raw material was charged, Comparative Example 1 in which the cross-sectional shape of the upper stirring blade was an inverted triangle and stirred was 90 μm. The size of the particle gauge tends to be smaller as the number of bubbles present in the slurry is smaller. From this, it can be seen that, after the powder raw material is charged, bubbles can be removed by stirring with the cross-sectional shape of the upper stirring blade 4 as a forward triangle. In addition, as a slurry for electrode formation, it is preferable that the magnitude | size of a particle gauge is 80 micrometers or less.

  Moreover, about the viscosity of a slurry, Examples 1-3 are 2000, 1000, and 5000 MPa / sec, respectively, and are viscosity (1000-5000 MPa / sec) suitable for apply | coating to substrate surfaces, such as a collector. there were. The difference in viscosity is due to the difference in the stirring performance depending on the type and presence of the homogenizer 9.

  In Examples 1 to 3, there was no adhesion (solidification) of the powder to the central portion of the stirring shaft.

  Moreover, about battery evaluation, Examples 1-3 were 3 (sigma) = 1.1-1.2W, and Comparative Examples 1-3 were 3 (sigma) = 2.0-2.1W. From this, it can be said that the batteries produced in Examples 1 to 3 have little variation in the room temperature output, and the slurry produced in Examples 1 to 3 is suitable for mass production of batteries.

(Other embodiments)
(1) In the first embodiment, the case where the cross-sectional shape of the upper stirring blade 4 is an equilateral triangle has been described. However, the triangle is not limited to an equilateral triangle, and may be another triangle such as an isosceles triangle. There may be. Further, the cross-sectional shape of the upper stirring blade 4 may be other shapes as long as the shape has a surface that creates a water flow in the gravity direction and the anti-gravity direction.

  6 and 7 show a cross section of the upper stirring blade 4 in another embodiment. As shown in FIGS. 6 and 7, the cross-sectional shape of the upper stirring blade 4 may be a pentagon. This pentagon has an apex angle 4e and sides 4f, 4g, 4h, 4i, and 4j, the side 4h is horizontal, and the apex angle 4e faces the side 4h. ing.

  As shown in FIG. 6, when the apex angle 4e is on the upper side and the side 4h is on the lower side, the surfaces constituting the two sides 4f and 4g forming the apex angle 4e are surfaces that make a water flow in the antigravity direction. As shown, when the apex angle 4e is lower and the side 4h is upper, the surfaces forming the two sides 4f and 4g forming the apex angle 4e are surfaces that make a water flow in the direction of gravity.

  Thus, the cross-sectional shape of the upper stirring blade 4 may be any shape that allows the water flow to be generated in the gravity direction and the antigravity direction by the stirring blade.

  (2) In the first embodiment, the case where only the upper stirring blade 4 has a structure that can be turned upside down has been described as an example. However, the middle and lower stirring blades 5 and 6 are also similar to the upper stirring blade 4. Alternatively, a structure that can be turned upside down may be used.

  (3) In the first embodiment, the number of stirring blades is three (the number of fixing portions in the longitudinal direction of the stirring shaft is three stages), but may be changed to another number as long as it is one or more. . When the number of the stirring blades is plural, at least the stirring blades positioned near the water surface may have the same structure as the upper stirring blade 7 described in the first embodiment.

  In the first embodiment, two stirring blades 4 are fixed to the same height portion of the stirring shaft 3, but the number of stirring blades 4 attached to the same height portion of the stirring shaft 3 is changed. You may do it.

  (4) In the first embodiment, the case where the air pressure sent from the compressor 17 is used as the power for raising the piston 21 that fixes the upper stirring blade 7 to the stirring shaft 3 has been described as an example. Other power may be used.

  Similarly, the case where the spring 22 is used as the means for lowering the piston 21 has been described as an example. However, when the piston 21 is lowered by gravity, the spring 22 may be omitted.

  Thus, the fixing method of the stirring blade described in the first embodiment is an example, and may be fixed by another method.

  (5) In the first embodiment, in the production of the positive electrode and the negative electrode, the case of applying the slurry production method of the present invention has been described as an example. However, only the production of the slurry used for forming one electrode is described. The invention may be applied. In this case, a known electrode can be used as it is for an electrode that does not employ the electrode for the lithium secondary battery of the present invention.

  (6) In the first embodiment, the case where a lithium secondary battery is manufactured as an electrochemical device has been described as an example. However, the present invention can be applied to the manufacture of other electrochemical devices such as a fuel cell and a capacitor.

  In addition, when manufacturing the slurry for fuel cell formation, the active material used in the manufacturing method of the slurry demonstrated in 1st Embodiment is abbreviate | omitted.

  (7) Moreover, this invention is applicable not only to the manufacturing method of the slurry for electrode formation of an electrochemical device but the whole process which mixes powder with the water as a solvent.

It is a front view containing the partial cross section of the slurry manufacturing apparatus in 1st Embodiment of this invention. It is a cross-sectional view of the stirring blade in FIG. It is a cross-sectional view of the stirring blade in FIG. It is sectional drawing of the stirring shaft in FIG. 1, and the uppermost stirring blade. It is a figure which shows the process of reversing the uppermost stirring blade in FIG. 1 upside down, and changing to a stirring shaft. It is a figure which shows the process following Fig.5 (a). It is a figure which shows the process of following FIG.5 (b). It is a figure which shows the process following FIG.5 (c). It is a figure which shows the process following FIG.5 (d). It is a cross-sectional view of the stirring blade in other embodiment of this invention. It is a cross-sectional view of the stirring blade in other embodiment of this invention. It is a front view including the partial cross section of the conventional slurry manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Stirrer tank, 2 ... Hopper, 3 ... Stirring shaft, 4, 5, 6 ... Stirring blade, 7 ... Stirrer,
11 ... Powder raw material inlet, 17 ... Compressor, 21 ... Piston.

Claims (5)

A stirring shaft (3) serving as a rotating shaft;
A stirring blade (4) fixed to the stirring shaft (3) and extending linearly from the stirring shaft (3) to the measurement of the stirring shaft;
The stirring blade (4) has the same cross-sectional shape as the entire stirring blade, and the stirring blade (4) rotates when the stirring shaft (3) is used as a rotating shaft to stir the object to be stirred. It has a surface that creates a flow in the direction of gravity or antigravity with respect to the processed material,
The stirring blade (4) and the stirring shaft (3) have a state in which the stirring blade (4) is detached from the stirring shaft (3) to create a flow in the direction of gravity with respect to the stirring target, and the stirring processing The stirrer has a structure in which the stirring blade (4) can be replaced with the stirring shaft (3) by changing between a state in which an anti-gravity flow is generated with respect to an object. . The stirring blade (4) is a triangle having a cross-sectional shape having an apex angle (4a) and a base (4b),
The agitating blade (4) and the agitating shaft (3) are shaped like a forward triangle in which the cross-sectional shape of the agitating blade (4) is positioned with the apex angle (4a) on the top and the base (4b) on the bottom. The stirring blade (4) is replaced with the stirring shaft (3) by changing between the state and the inverted triangular state in which the apex angle (4a) is down and the base (4b) is up. The stirrer according to claim 1, wherein the stirrer has a structure capable of. A fitting portion (3a) provided on the stirring shaft (3) and fitted with the stirring blade (4);
It is provided in the fitting part (3a) and is pushed onto the stirring blade (4) from a position where the stirring blade (4) can be removed from the stirring shaft (3) by supplying compressed air. A piston (21) that moves to a position where the stirring shaft (3) is fixed to the stirring blade (4).
The stirrer according to claim 1 or 2, further comprising a compressor (17) for supplying compressed air to the piston (21). A stirrer (7) according to any one of claims 1 to 3,
A stirring tank (1) in which the powder raw material of the solvent and slurry is stored, and the stirring blade (4) of the stirrer is disposed inside;
A slurry production apparatus comprising: a powder raw material inlet (11) provided at an upper portion of the stirring tank (1). A slurry production method using the slurry production apparatus according to claim 4,
The stirring blade (4) is fixed to the stirring shaft (3) in a state where a flow in the direction of gravity can be created with respect to the workpiece to be stirred, and the surface of the stirring tank (1) is more water than the stirring blade (4). Supplying the slurry powder raw material to the water while rotating the agitation shaft (3) and causing a water flow in the direction of gravity near the water surface. ,
After the step of supplying the powder raw material, the stirring blade (4) is removed from the stirring shaft (3), and the stirring blade (4) is brought into a state in which a flow in the antigravity direction can be created with respect to the workpiece to be stirred. Changing and replacing the stirring blade (4) with the stirring shaft (3);
By making the flow in the antigravity direction and making the stirring blade (3) rotate after the step of replacing the stirring blade with the stirring shaft, by causing the water flow in the antigravity direction near the water surface, And a step of removing bubbles present in the slurry.

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