JP2019125525A - Method of cleaning kneader - Google Patents

Abstract

To provide a method of cleaning a kneader capable of cleaning the inside of a kneader without removing each component in the kneader.SOLUTION: A method of cleaning a kneader that is used for kneading a positive electrode paste includes the steps of: adding water to residual deposits generated from a positive electrode paste containing polyvinylidene fluoride (step S2); and cleaning the inside of a kneader 3 while kneading the residual deposits added with water (step S5). In the cleaning step (step 5), the viscosity of the residual deposits are adjusted to 40,000 mP s or more and 100,000 mP s or less.SELECTED DRAWING: Figure 1

Description

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

For example, a current collector on which a positive electrode paste is applied is used for the positive electrode of a secondary battery. The positive electrode paste is manufactured 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, the kneading machine which knead | mixes a positive electrode paste material by rotating the main axis | shaft to which several paddles were attached to patent document 1 is disclosed.

JP, 2015-109175, A

The inventor found the following problems regarding the cleaning method of the kneader for kneading the positive electrode paste material.
In the kneader disclosed in Patent Document 1, the main shaft on 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 main shaft rotates, the positive electrode paste material in the gap between the plurality of paddles is kneaded to produce a positive electrode paste.

  The positive electrode paste is sufficiently kneaded and then discharged from the discharge port. However, a part of the positive electrode paste remains in the gaps between parts such as a plurality of paddles and the like, and becomes a residual deposit. If the next positive electrode paste material is kneaded while the residual deposits adhere 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 deposit has adhered, and to remove the residual deposit from each part in the kneader.

  Since the residual deposits are highly sticky, human beings remove and wipe each of the parts in the kneader and wash them. However, the number of parts is large, and removal and wiping take time.

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

  A method for cleaning a kneader according to one aspect of the present invention is a method for cleaning a kneader for mixing a positive electrode paste, and adding water to a residual deposit produced from the positive electrode paste containing polyvinylidene fluoride; Cleaning the inside of the kneader while kneading the residual deposit to which water is added, and in the washing step, the viscosity of the residual adherent is 40,000 mP · s to 100,000 mP ···. Adjust to s or less.

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

  ADVANTAGE OF THE INVENTION By this invention, the washing | cleaning method of the kneading machine which can wash | clean the inside of a kneading machine can be provided, without removing each component in a kneading machine.

It is a schematic diagram showing the washing | cleaning apparatus of the kneading machine which concerns on this Embodiment. It is a graph which shows the relationship between a water injection rate and the viscosity of a residual deposit. It is a flowchart of the washing | cleaning method of the kneading machine 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 the drawings are simplified as appropriate.

  First, with reference to FIG. 1, an apparatus (cleaning apparatus for a kneader) for carrying out a method for cleaning a kneader according to an embodiment of the present invention will be described. FIG. 1 is a schematic view showing a cleaning device of a kneading machine according to the present embodiment. As shown in FIG. 1, the washing device 1 of the kneader includes a kneader 3, an injection valve 4, an injection control unit 4a, an injection device 4b, an injection pipe 4c, an air injection valve 42, an air injection device 42b, and an air injection device 42b. It has a pipe for insertion 42c, a cumulative flow meter 5, a valve for discharge 6, a discharge control unit 6a, a pipe for discharge 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 twin-screw kneader for kneading the positive electrode paste material. In the kneading space provided inside the kneading machine 3, two main shafts (not shown) are stored. Parts such as paddles and barrels are attached to the two main spindles at predetermined intervals. When the kneader 3 operates, the two main shafts rotate in the directions of the arrows shown in FIG. When the kneader 3 operates, the parts such as the paddle and the barrel rotate with the two main shafts to knead the positive electrode paste.

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

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

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

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

  Further, in the kneading machine 3, a discharge pipe 6c is extended from the lower side of the kneading space. For example, as shown in FIG. 1, the discharge pipe 6 c is extended from one end of the mixer 3. 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 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 from the kneading space of the kneading machine 3 to the outside.

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

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

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

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

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

  The positive electrode paste material is fed from the feeding device 4 b into the kneading space of the kneader 3 via the feeding pipe 4 c. The positive electrode paste material introduced into the kneading space of the kneader 3 enters the gap between parts such as a paddle and a barrel. When the kneader 3 operates, the positive electrode paste material that has entered the gap between the parts such as the paddle and the barrel is kneaded to become a 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 a powder of a positive electrode active material, a binder, a conductive agent and the like using a solvent which is a liquid, and has adhesiveness. Therefore, when the positive electrode paste material is kneaded, part of the positive electrode paste adheres to each component such as a paddle and a barrel. A part of the adhered positive electrode paste remains in the inside of the kneader 3 even after discharging the positive electrode paste, and becomes a residual adhered substance.

  If the next positive electrode paste material is kneaded in a state in which the residual deposits remain inside the kneader 3, there is a possibility that the residual deposits will be kneaded with the next positive electrode paste material. That is, there is a possibility that the composition of the next positive electrode paste may change due to the residual deposit.

Therefore, after the positive electrode paste is discharged from the discharge valve 6, the inside of the kneader 3 is cleaned.
Although the details will be described later, in the cleaning method of the kneading machine according to the present embodiment, the inside of the kneading machine is cleaned while kneading the remaining adhering matter to which water is added.

  The residual deposit contains 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 as a binder. Polyvinylidene fluoride is a polymer represented by the following chemical formula (1). In Chemical Formula (1), n represents a positive integer.

Polyvinylidene fluoride causes dehydrofluorination reaction, for example, in alkaline conditions. The polyvinylidene fluoride which showed the dehydrofluorination reaction is shown, for example, by the following chemical formula (2).

The polyvinylidene fluorides in which the dehydrofluorination reaction has taken place polymerize in the form of a network as shown in the following chemical formula (3) and gelate.

  Since the residual deposit contains lithium metal oxide and polyvinylidene fluoride, it gels when it is kneaded with water. The gelled residual deposits are less sticky than the non-gelled residual deposits. Thus, the gelled residual deposits peel off from multiple parts such as paddles and barrels. That is, the inside of the kneader 3 can be effectively cleaned by adding water to the residual deposit and kneading.

  The higher the proportion of water added to the residual deposits, the more the residual deposits become gelled and the viscosity becomes higher. However, if the viscosity of the residual deposit is too high, the residual deposit may be clogged in the portion discharged from the kneading space of the kneader 3 to the discharge pipe 6c. Therefore, if the proportion of water added to the amount of residual deposits is too high, it becomes difficult to discharge the remaining deposits from the kneading space of the kneader 3.

  FIG. 2 is a graph showing the relationship between the water input rate and the viscosity of the residual deposit. In FIG. 2, the water input rate represents the ratio of the mass of water to the mass of the positive electrode active material. As shown in FIG. 2, the greater the amount of water added to the residual deposits, the higher the viscosity of the residual deposits. That is, the residual deposits become high in viscosity when gelled. When the viscosity of the residual deposit is greater 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 adhesion of the residual deposit is high because gelation has not progressed, and the residual deposit is difficult to peel off from multiple parts such as paddles and barrels. . Therefore, when 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 cleaned.

  Assuming that the weight of water added to the residual deposit is 45 wt% or more and 60 wt% or less of the residual deposit, as shown in FIG. 2, the viscosity of the residual deposit is adjusted to 40,000 mP · s or more and 100,000 mP · s or less can do.

  Next, with reference to FIG. 1 and FIG. 3, the washing | cleaning method of the kneader based on embodiment of this invention is demonstrated. FIG. 3 is a flowchart of the washing method of the kneading machine according to the present embodiment.

  First, the input valve 4 is opened, and water is supplied from the input device 4b to the inside of the kneader 3 through the input pipe 4c (step S1). In addition, when performing step S1, you may provide the water injection | throwing-in apparatus which injects water separately from the injection | throwing-in apparatus 4b, and may inject | pour water from a water injection | throwing-in apparatus.

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

  After the water of 45 wt% or more and 60 wt% or less of the residual deposit is fed into the inside of the kneader 3, the feeding valve 4 may be closed manually. Specifically, the time taken to introduce water is calculated in advance from the flow rate of the input pipe 4c. Then, after the input valve 4 is opened for a predetermined time to supply water to the inside of the kneading machine 3, the input valve 4 is manually closed.

  Next, the main shaft of the kneader 3 is rotated to knead the residual deposit and water (step S4). And it knead | mixes until the viscosity of a residual deposit becomes 40,000 mP * s or more and 100,000 mP * s or less (step S5). When the residual deposit is gelled to a viscosity of 40,000 mP · s or more, the tackiness is weakened and peeled off from a plurality of parts such as paddles and barrels. That is, the inside of the kneader 3 can be cleaned by kneading the residual adhering material to which water is added.

  When performing step S4. The kneader 3 may be heated using the heater 8. When the remaining deposit and water are kneaded while heating the kneader 3, the gelation of the remaining deposit is promoted. For example, when the residual deposit is kneaded in the kneader 3 heated to 80 ° C., the gelation of the residual deposit progresses in about one eighth of the time than in the case of kneading at normal temperature.

  Alternatively, washing beads may be introduced into the interior of the kneader 3 together with water when step S3 is performed, and the washing beads may be kneaded with the remaining deposits and water in step S4. The size of the beads for cleaning is preferably one-half to three-quarters of the gap between the plurality of parts such as the paddle and the barrel, because the residual deposit can be rubbed off, which is preferable. The washing beads are made of, for example, a resin. If the hardness of the washing beads is less than 50% of the surface hardness of the plurality of parts such as the paddle and the barrel, the plurality of parts such as the paddle and the barrel may not be damaged, which is preferable.

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

  In addition, after the year of the residual deposit becomes 40,000 mP · s or more and 100,000 mP · s or less, the input valve 4 and the discharge valve 6 may be opened manually. Specifically, the relationship between the amount of water input and the kneading time of the residual deposit and the viscosity of the residual deposit is examined in advance. Then, after kneading the remaining adhering matter for a predetermined time using a timer or the like, the input valve 4 and the discharge valve 6 are manually opened.

  The discharge valve 6 is opened (step S6), the introduction valve 4 is opened (step S7), and water is introduced into the interior of the kneader 3 from the introduction device 4b. When water is introduced into the interior of the kneader 3 with the discharge valve 6 open, the remaining deposits are pushed out by the water and discharged from the discharge pipe 6c. The residual deposit is discharged from the discharge pipe 6c without clogging in the interior of the kneader 3 because the viscosity is 100,000 mP · s or less. After discharging the residual deposit, water is further introduced into the interior of the kneader 3 to carry out 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 from the washing pipe is provided. It is possible to discharge the attached water.

  Further, when discharging the gelled residual deposits and water, the mixer 3 may be inclined using the inclination mechanism 9. When the tilting mechanism 9 operates, the end of the kneader 3 on which the discharge pipe 6c is not provided is lifted and tilted. When the mixer 3 is inclined, discharge of positive electrode paste, water and the like is promoted.

  Then, the rotation of the main shaft of the kneader 3 is stopped (step S8), and the inlet valve 4 and the outlet valve 6 are closed (step S9). Step S9 may be performed before step S8. Also, step S8 and step S9 may be performed simultaneously.

  When the final cleaning is performed, water remains in the kneading space of the kneading machine 3. If the next positive electrode material paste is kneaded while water remains, there is a possibility that the remaining positive electrode paste may gel due to the remaining water. Then, after performing step S7, the kneading space of the kneading machine 3 is dried.

  The kneading space of the kneading machine 3 is dried, for example, by injecting dry air into the kneading space of the kneading machine 3 from the air charging device 42b. Specifically, the air charging valve 42 is opened, and air is supplied from the air charging device 42b to the kneading space of the kneading machine 3 through the air charging pipe 42c. Furthermore, 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.

  In addition, the water in the kneading space of the kneading machine 3 may be discharged by performing dumping without drying the kneading space of the kneading machine 3. Specifically, a small amount of positive electrode paste material is introduced into the kneading space of the kneading machine 3. When a small amount of positive electrode paste material is kneaded with water remaining in the kneading space of the kneader 3, a small amount of positive electrode paste containing water is produced. A small amount of moisture-containing positive electrode paste 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.

  The invention according to the present embodiment described above can provide a method for cleaning a kneader that can clean the inside of the kneader without removing parts in the kneader.

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

Reference Signs List 1 kneader washing apparatus 3 kneader 4 charging valve 4a charging control unit 4b charging device 4c charging pipe 42 air charging valve 42b air charging device 42c air charging pipe 5 integrating flow meter 6 discharging valve 6a discharge control unit 6c Discharge pipe 7 Viscometer 8 Heater 9 Tilting mechanism

Claims (1)

A cleaning method of a kneader for kneading a positive electrode paste, comprising
Adding water to a residual deposit produced from a positive electrode paste containing polyvinylidene fluoride;
Washing the interior of the kneader while kneading the residual deposit to which water has been added;
In the washing 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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