JP6947049B2 - How to clean the kneader - Google Patents

Description

The present invention relates to a method for cleaning a kneader.

For example, a current collector coated with a positive electrode paste is used for the positive electrode of the secondary battery. The positive electrode paste is produced by kneading a positive electrode paste material such as a positive electrode active material, a binder, a conductive agent, and a solvent.
By the way, Patent Document 1 discloses a kneading machine for kneading a positive electrode paste material by rotating a spindle to which a plurality of paddles are attached.

Japanese Unexamined Patent Publication No. 2015-109175

The inventor has found the following problems with respect to the cleaning method of the kneader for kneading the positive electrode paste material.
In the kneading machine disclosed in Patent Document 1, a spindle to which a plurality of paddles are attached is rotated to knead the positive electrode paste material. The plurality of paddles are attached to the spindle at predetermined intervals. When the spindle rotates, the positive electrode pearl material that has entered the gaps between the plurality of paddles is kneaded to produce a positive electrode paste.

The positive electrode paste is thoroughly kneaded and then discharged from the discharge port. However, a part of the positive electrode paste remains in the gaps of each component such as a plurality of paddles and becomes residual deposits. If the next positive electrode paste material is kneaded with the residual deposits adhering to the inside of the kneader, the composition of the next positive electrode paste may change due to the residual deposits. Therefore, it is necessary to clean the inside of the kneader to which the residual deposits have adhered and remove the residual deposits from each component in the kneader.

Since the residual deposits are highly sticky, humans remove each part in the kneader, wipe it off, and clean it. However, each part has a large number and takes time to remove and wipe.

The present invention has been made in view of such problems, and an object of the present invention is to provide a method for cleaning a kneader, which can clean the inside of the kneader without removing each component in the kneader.

The method for cleaning the kneader according to one aspect of the present invention is a method for cleaning the kneader that kneads the positive electrode paste, and comprises a step of adding water to the residual deposits generated from the positive electrode paste containing vinylidene fluoride. A step of cleaning the inside of the kneader while kneading the residual deposit to which water has been added is provided, and in the cleaning step, the viscosity of the residual deposit is 40,000 mP · s or more and 100,000 mP ·. Adjust to s or less.

The method for cleaning the kneader according to the present invention includes a step of cleaning the inside of the kneader while kneading the residual deposits to which water has been added. That is, the inside of the kneader is cleaned by operating the kneader without removing each part from the kneader. With such a configuration, the inside of the kneader can be cleaned without removing each component in the kneader.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for cleaning a kneader, which can clean the inside of the kneader without removing each component in the kneader.

It is a schematic diagram which shows the washing apparatus of the kneader which concerns on this embodiment. It is a graph which shows the relationship between the water input rate and the viscosity of residual deposits. It is a flowchart of the washing method of the kneader which concerns on this embodiment.

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Further, in order to clarify the explanation, the following description and drawings have been simplified as appropriate.

First, with reference to FIG. 1, an apparatus for carrying out the method for cleaning the kneader according to the embodiment of the present invention (cleaning apparatus for the kneader) will be described. FIG. 1 is a schematic view showing a cleaning device for a kneader according to the present embodiment. As shown in FIG. 1, the kneader cleaning device 1 includes a kneader 3, a charging valve 4, a charging control unit 4a, a charging device 4b, a charging pipe 4c, an air charging valve 42, an air charging device 42b, and air. It includes a charging pipe 42c, an integrated flow meter 5, a discharge valve 6, a discharge control unit 6a, a discharge pipe 6c, a viscometer 7, a heater 8, and an inclination mechanism 9. In FIG. 1, the arrow indicates the direction in which the main shaft of the kneader 3 rotates.

The kneader 3 is a biaxial kneader that kneads the positive electrode paste material. Two spindles (not shown) are stored in the kneading space provided inside the kneading machine 3. Parts such as paddles and barrels are attached to the two spindles at predetermined intervals. When the kneader 3 operates, the two spindles rotate in the directions of the arrows shown in FIG. When the kneading machine 3 operates, each part such as a paddle and a barrel rotates together with the two spindles to knead the positive electrode paste.

As shown in FIG. 1, a charging device 4b is connected to the kneading machine 3 via a charging pipe 4c. The charging pipe 4c communicates with the kneading space of the kneading machine 3 and the charging device 4b. A charging valve 4 is provided in the middle of the charging pipe 4c. The charging valve 4 is an open / close type valve, and controls the flow rate of the charging pipe 4c. When the charging valve 4 is opened, the positive electrode paste material, water, and the like are charged from the charging device 4b into the kneading space of the kneading machine 3.

Further, as shown in FIG. 1, an air injection device 42b is connected to the kneader 3 via an air injection pipe 42c. The air charging pipe 42c communicates with the kneading space of the kneading machine 3 and the charging device 4b. An air injection valve 42 is provided in the middle of the air injection pipe 42c.

The air injection valve 42 is, for example, an open / close valve that can be opened and closed manually. The air injection valve controls the flow rate of the air injection pipe 42c. When the air injection valve 42 is opened, air is introduced from the air injection device 42b into the kneading space of the kneader 3.

An integrated flow meter 5 is attached to the charging pipe 4c. As shown in FIG. 1, the integrated flow meter 5 is connected to the closing control unit 4a by wiring. The integrated flow meter 5 measures the flow rate of the positive electrode paste material, water, etc. in the charging pipe 4c, and outputs the measurement data to the charging control unit 4a. The closing control unit 4a opens and closes the closing valve 4 based on the measurement data of the integrated flow meter 5.

Further, in the kneading machine 3, a discharge pipe 6c extends from below the kneading space. The discharge pipe 6c extends from one end of the kneader 3, for example, as shown in FIG. The discharge pipe 6c communicates the kneading space of the kneading machine 3 to the outside. A discharge valve 6 is provided in the middle of the discharge pipe 6c. The discharge valve 6 is an open / close type valve, and controls the flow rate of the discharge pipe 6c. When the discharge valve 6 is opened, the positive electrode paste, water, and the like are discharged to the outside from the kneading space of the kneading machine 3.

A viscometer 7 is attached to the kneader 3. As shown in FIG. 1, the viscometer 7 is connected to the discharge control unit 6a by wiring. The viscometer 7 measures the viscosity of the positive electrode paste or the like in the kneading space of the kneading machine 3, and outputs the measurement data to the discharge control unit 6a. The discharge control unit 6a opens and closes the discharge valve 6 based on the measurement data of the viscometer 7.

Further, as shown in FIG. 1, the viscometer 7 is connected to the closing control unit 4a by wiring. The viscometer 7 outputs the measurement data to the input control unit 4a. The closing control unit 4a opens and closes the closing valve 4 based on the measurement data of the viscometer 7. As described above, the closing control unit 4a opens and closes the closing valve 4 based on the measurement data of the integrated flow meter 5. That is, the closing control unit 4a opens and closes the closing valve 4 based on the measurement data of the integrated flow meter 5 and the viscometer 7.

Further, the entire kneading machine 3 or the kneading space is heated by using the heater 8. The heater 8 is, for example, a plate-shaped heating mechanism. Further, the position where the heater 8 is installed is not limited as long as the heater 8 can heat the kneader 3.

When discharging the positive electrode paste or the like from the inside of the kneading machine 3, the kneading machine 3 may be tilted by using the tilting mechanism 9. The tilting mechanism 9 is configured by using, for example, a handle-type tilting mechanism. The tilting mechanism 9 is installed, for example, at the other end of the kneader 3 (the end where the discharge pipe 6c is not extended). When the tilting mechanism 9 is activated, the end of the kneader 3 is lifted and tilted. When the kneader 3 is tilted, the discharge of the positive electrode paste, water, and the like is promoted.

By the way, the positive electrode paste material is composed of a positive electrode active material, a binder, a conductive agent, a solvent and the like. Specifically, the positive electrode active material is composed of a lithium metal oxide such as lithium cobalt oxide. The binder is constructed using polyvinylidene fluoride (PVDF). The conductive agent is composed of, for example, activated carbon, graphite fine powder, carbon fiber and the like. The solvent is constructed using, for example, an organic solvent such as N-methylpyrrolidone (NMP).

The positive electrode paste material is charged from the charging device 4b into the kneading space of the kneading machine 3 via the charging pipe 4c. The positive electrode paste material put into the kneading space of the kneading machine 3 enters the gaps between parts such as paddles and barrels. When the kneading machine 3 is operated, the positive electrode paste material that has entered the gaps between the parts such as the paddle and the barrel is kneaded to become the positive electrode paste. Then, the positive electrode paste kneaded in the kneading space of the kneading machine 3 is discharged to the outside through the discharge pipe 6c.

The positive electrode paste is a paste obtained by kneading powders such as a positive electrode active material, a binder, and a conductive agent using a liquid solvent, and has adhesiveness. Therefore, when the positive electrode paste material is kneaded, a part of the positive electrode paste adheres to each component such as a paddle and a barrel. A part of the attached positive electrode paste remains inside the kneader 3 even after the positive electrode paste is discharged, and becomes a residual deposit.

If the next positive electrode paste material is kneaded with the residual deposits remaining inside the kneader 3, the residual deposits may be kneaded with the next positive electrode paste material. That is, the composition of the next positive electrode paste may change due to the residual deposits.

Therefore, after the positive electrode paste is discharged from the discharge valve 6, the inside of the kneader 3 is washed.
Details will be described later, but in the method for cleaning the kneader according to the present embodiment, the inside of the kneader is cleaned while kneading the residual deposits to which water has been added.

The residual deposit contains a lithium metal oxide which is a positive electrode active material. Therefore, when water is added to the residual deposit, lithium ions are eluted and the residual deposit becomes an alkaline paste.

In addition, the residual deposit contains polyvinylidene fluoride, which is a binder. Polyvinylidene fluoride is a polymer represented by the following chemical formula (1). In the chemical formula (1), n represents a positive integer.

Polyvinylidene fluoride causes a defluorination hydrogen reaction, for example, under alkaline conditions. The polyvinylidene fluoride that has shown a defluorinated hydrogen reaction is represented by, for example, the following chemical formula (2).

The polyvinylidene fluorides that have undergone the hydrogen fluoride reaction are polymerized in a network shape as shown in the following chemical formula (3) and gelled.

Since the residual deposit contains lithium metal oxide and polyvinylidene fluoride, it gels when kneaded with water. Gelled residual deposits are less sticky than non-gelled residual deposits. Therefore, the gelled residual deposit is peeled off from a plurality of parts such as paddles and barrels. That is, the inside of the kneading machine 3 can be effectively washed by adding water to the residual deposits and kneading them.

The greater the proportion of water added to the residual deposit, the more the residual deposit will gel and the higher the viscosity. However, if the viscosity of the residual deposit is too high, the residual deposit may be clogged at the portion discharged from the kneading space of the kneading machine 3 to the discharge pipe 6c. Therefore, if the ratio of water added to the amount of residual deposits is too large, it becomes difficult to discharge the residual deposits from the kneading space of the kneading machine 3.

FIG. 2 is a graph showing the relationship between the water input rate and the viscosity of residual deposits. In FIG. 2, the water input rate represents the ratio of the mass of water to be added to the mass of the positive electrode active material. As shown in FIG. 2, the larger the amount of water added to the residual deposit, the higher the viscosity of the residual deposit. That is, the residual deposit becomes highly viscous when gelled. If the viscosity of the residual deposit is larger than 100,000 mP · s, it becomes difficult to discharge the residual deposit from the inside of the kneader 3.

On the other hand, if the viscosity of the residual deposit is less than 40,000 mP · s, the gelation has not progressed, so that the residual deposit has high adhesiveness and the residual deposit is difficult to peel off from a plurality of parts such as paddles and barrels. .. Therefore, if water is added to the residual deposit so that the viscosity of the residual deposit is 40,000 mP · s or more and 100,000 mP · s or less, the inside of the kneader 3 can be effectively washed.

Assuming that the mass of water added to the residual deposit is 45 wt% or more and 60 wt% or less of the residual deposit, the viscosity of the residual deposit is adjusted to 40,000 mP · s or more and 100,000 mP · s or less as shown in FIG. can do.

Next, a method of cleaning the kneader according to the embodiment of the present invention will be described with reference to FIGS. 1 and 3. FIG. 3 is a flowchart of a method for cleaning the kneader according to the present embodiment.

First, the charging valve 4 is opened, and water is charged into the kneader 3 from the charging device 4b via the charging pipe 4c (step S1). When performing step S1, a water charging device for charging water may be provided separately from the charging device 4b, and water may be charged from the water charging device.

Water of 45 wt% or more and 60 wt% or less of the residual deposit is added (step S2), and the charging valve 4 is closed (step S3). The amount of water input is measured using the integrated flow meter 5. When it is detected based on the measurement data of the integrated flow meter 5 that water of 45 wt% or more and 60 wt% or less of the residual deposit is charged into the kneader 3, the charging control unit 4a controls to close the charging valve 4. To execute.

The charging valve 4 may be manually closed after water of 45 wt% or more and 60 wt% or less of the residual deposit has been charged into the kneader 3. Specifically, the time required for charging water is calculated in advance from the flow rate of the charging pipe 4c. Then, after opening the charging valve 4 for a predetermined time and charging water into the kneader 3, the charging valve 4 is manually closed.

Next, the spindle of the kneader 3 is rotated to knead the residual deposits and water (step S4). Then, the residue is kneaded until the viscosity of the residual deposit is 40,000 mP · s or more and 100,000 mP · s or less (step S5). When the residual deposit is gelled until the viscosity becomes 40,000 mP · s or more, the adhesiveness becomes weak and the residual deposit is peeled off from a plurality of parts such as paddles and barrels. That is, the inside of the kneading machine 3 can be washed by kneading the residual deposits to which water has been added.

When performing step S4. The kneader 3 may be heated by using the heater 8. When the residual deposit and water are kneaded while heating the kneader 3, gelation of the residual deposit is promoted. For example, when the residual deposits are kneaded in the kneading machine 3 heated to 80 ° C., gelation of the residual deposits proceeds in about one-eighth of the time as compared with the case of kneading at room temperature.

Further, when performing step S3, the cleaning beads may be thrown into the kneading machine 3 together with water, and the cleaning beads may be kneaded together with the residual deposits and water in step S4. When the size of the cleaning beads is ½ or more and 3/4 or less of the gap between a plurality of parts such as paddles and barrels, residual deposits can be scraped off, which is preferable. The cleaning beads are constructed using, for example, resin. When the hardness of the cleaning beads is less than 50% of the surface hardness of a plurality of parts such as paddles and barrels, there is no risk of damaging the plurality of parts such as paddles and barrels, which is preferable.

In step S5, the viscosity of the residual deposit is measured using a viscometer 7. When it is detected based on the measurement data of the viscometer 7 that the viscosity of the residual deposit is 40,000 mP · s or more and 100,000 mP · s or less, the discharge control unit 6a detects the charging valve 4 and the discharge valve 6. Control to open.

The injection valve 4 and the discharge valve 6 may be manually opened after the year of the residual deposit is 40,000 mP · s or more and 100,000 mP · s or less. Specifically, the relationship between the amount of water input, the kneading time of the residual deposit, and the viscosity of the residual deposit is investigated in advance. Then, after kneading the residual deposits for a predetermined time using a timer or the like, the charging valve 4 and the discharging valve 6 are manually opened.

The discharge valve 6 is opened (step S6), the charging valve 4 is opened (step S7), and water is charged into the kneader 3 from the charging device 4b. When water is poured into the kneader 3 with the discharge valve 6 open, the residual deposits are pushed out by the water and discharged from the discharge pipe 6c. Since the residual deposit has a viscosity of 100,000 mP · s or less, it is discharged from the discharge pipe 6c without clogging inside the kneader 3. After discharging the residual deposits, water is further added to the inside of the kneader 3 to perform finish cleaning.

When discharging the gelled residual deposits and water, a cleaning pipe for discharging the gelled residual deposits and water is provided separately from the discharge pipe 6c, and the gelled residue is provided from the cleaning pipe. Adhesive water may be drained.

Further, when discharging the gelled residual deposits and water, the kneading machine 3 may be tilted by using the tilting mechanism 9. When the tilting mechanism 9 is activated, the kneader 3 is tilted by lifting the end portion on the side where the discharge pipe 6c is not provided. When the kneader 3 is tilted, the discharge of the positive electrode paste, water, and the like is promoted.

Then, the rotation of the spindle of the kneader 3 is stopped (step S8), and the charging valve 4 and the discharging valve 6 are closed (step S9). Note that step S9 may be performed before step S8. Further, step S8 and step S9 may be performed at the same time.

When the finish washing is performed, moisture remains in the kneading space of the kneading machine 3. If the next positive electrode material paste is kneaded with water remaining, the next positive electrode paste may gel due to the remaining water. Therefore, after performing step S7, the kneading space of the kneading machine 3 is dried.

The kneading space of the kneading machine 3 is dried by, for example, charging dry air from the air charging device 42b into the kneading space of the kneading machine 3. Specifically, the air injection valve 42 is opened, and air is injected from the air injection device 42b into the kneading space of the kneader 3 via the air injection pipe 42c. Further, the kneading space of the kneading machine 3 may be dried by heating the entire kneading machine 3 or the kneading space using the heater 8.

Further, the kneading space of the kneading machine 3 may be discharged without drying the kneading space of the kneading machine 3 by throwing away the kneading space. Specifically, a small amount of positive electrode paste material is put into the kneading space of the kneading machine 3. When a small amount of the positive electrode paste material is kneaded together with the water remaining in the kneading space of the kneading machine 3, a small amount of the positive electrode paste containing the water is produced. A small amount of the positive electrode paste containing water is discharged from the discharge pipe 6c. That is, the water remaining in the kneading space of the kneading machine 3 is discharged together with a small amount of positive electrode paste.

According to the invention according to the present embodiment described above, it is possible to provide a method for cleaning the kneader, which can clean the inside of the kneader without removing each component in the kneader.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit.

1 Kneader cleaning device 3 Kneading machine 4 Input valve 4a Input control unit 4b Input device 4c Input pipe 42 Air input valve 42b Air input device 42c Air input pipe 5 Integral flow meter 6 Discharge valve 6a Discharge control unit 6c Discharge pipe 7 Viscometer 8 Heater 9 Tilt mechanism

Claims (1)

It is a cleaning method of a kneader that kneads the positive electrode paste.
The process of adding water to the residual deposits produced from the positive electrode paste containing polyvinylidene fluoride, and
A step of cleaning the inside of the kneader while kneading the residual deposits to which water has been added is provided.
In the cleaning step, the viscosity of the residual deposit is adjusted to 40,000 mP · s or more and 100,000 mP · s or less.
How to clean the kneader.

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