JP2018081924A - Separator film manufacturing method for nonaqueous electrolyte secondary battery and separator film cleaning device for nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress contamination of cleaning liquid in a washing tank on the downstream side in a transport path of a separator film of a nonaqueous electrolyte secondary battery.SOLUTION: A roller (m) and a roller (a) is in contact with one side of a heat resistant separator (S), and a roller (n) is in contact with the other side of the heat resistant separator (S) between the roller (m) and the roller (a), and wash water (W) is removed from the heat resistant separator (S), and then, the heat resistant separator (S) is conveyed to a washing tank (16), and the water (W) filled in the washing tank (15) and the water (W) filled in the washing tank (16) are the same type.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for producing a separator film for a non-aqueous electrolyte secondary battery used in a battery such as a lithium ion secondary battery and a cleaning device.

  Inside the lithium ion secondary battery, the positive electrode and the negative electrode are separated by a film-like and porous separator. The manufacturing process of this separator includes a cleaning process for later removing unnecessary substances from the film once formed.

  A cleaning apparatus for performing the above-described cleaning process is disclosed in Patent Document 1. The cleaning apparatus according to Patent Document 1 cleans the film through the film through two cleaning tanks.

JP 2001-228594 A (published on August 24, 2001)

  In the cleaning apparatus according to Patent Document 1, after being unloaded from the upstream cleaning tank (referred to herein as cleaning tank A) in the film conveyance path, the downstream cleaning tank (referred to herein as cleaning tank B). Before entering, especially the liquid adhering to the upper surface of the film is hardly removed. For this reason, in the cleaning apparatus according to Patent Document 1, there is a possibility that the liquid filled in the cleaning tank A enters the cleaning tank B.

  The cleaning tank A and the cleaning tank B are filled with liquid for film cleaning, but the liquid filled in the cleaning tank A on the upstream side of the transport path is usually more dirty than the liquid filled in the cleaning tank B. Yes. For this reason, when the liquid filled in the cleaning tank A enters the cleaning tank B, there arises a problem that the liquid filled in the cleaning tank B is contaminated.

  The present invention has been made in view of the above problems, and its purpose is to suppress contamination of the cleaning liquid in the downstream cleaning tank in the transport path of the separator film for the nonaqueous electrolyte secondary battery. It is providing the separator film manufacturing method for nonaqueous electrolyte secondary batteries, and the separator film washing | cleaning apparatus for nonaqueous electrolyte secondary batteries.

  A separator film manufacturing method for a non-aqueous electrolyte secondary battery according to an aspect of the present invention includes a cleaning step of cleaning the separator film for a non-aqueous electrolyte secondary battery in a first cleaning tank, and the unloading from the first cleaning tank. A first roller, a second roller, and a third roller are brought into contact with the separator film for a non-aqueous electrolyte secondary battery, and the separator film for a non-aqueous electrolyte secondary battery is conveyed to a second cleaning tank. The first roller and the third roller are in contact with one surface of the separator film for non-aqueous electrolyte secondary battery, and the first roller and the third roller. When the second roller is in contact with the other surface of the separator film for non-aqueous electrolyte secondary battery between the rollers, the separator film for non-aqueous electrolyte secondary battery is contacted. After the cleaning liquid is removed from the liquid, the non-aqueous electrolyte secondary battery separator film is transported to the second cleaning tank, and the cleaning liquid filled in the first cleaning tank and the second cleaning tank are filled. The cleaning liquid is the same type.

  A separator film cleaning device for a non-aqueous electrolyte secondary battery according to an aspect of the present invention includes a first cleaning tank and a second cleaning tank for cleaning a separator film for a non-aqueous electrolyte secondary battery, and the first cleaning. A first roller, a second roller, which are in contact with the non-aqueous electrolyte secondary battery separator film carried out of the tank and transport the non-aqueous electrolyte secondary battery separator film to a second cleaning tank; And a third roller, wherein the first roller and the third roller are in contact with one surface of the separator film for a non-aqueous electrolyte secondary battery, and the first roller and the third roller The second roller comes into contact with the other surface of the separator film for a non-aqueous electrolyte secondary battery in the meantime, so that the second roller becomes a separator fill for the non-aqueous electrolyte secondary battery. After removing the cleaning liquid from the above, the separator film for a non-aqueous electrolyte secondary battery is conveyed to a second cleaning tank, the cleaning liquid filled in the first cleaning tank, and the cleaning liquid filled in the second cleaning tank Are the same type.

  Moreover, it is preferable that the speed of the surface of the said 2nd roller differs from the conveyance speed of the said separator film for non-aqueous electrolyte secondary batteries.

  Moreover, it is preferable that the second roller is rotationally driven, and the second roller is a driving roller that is rotationally driven by power. The second roller is preferably driven to rotate, and the second roller is preferably a driving roller that is driven to rotate by power.

  Moreover, it is preferable that the uneven | corrugated shape is provided in the surface of the said 2nd roller.

  Further, it is preferable that a spiral, curved, or linear groove is provided on the surface of the second roller.

  The groove of the second roller preferably extends beyond the end of the separator film for nonaqueous electrolyte secondary battery in the width direction of the separator film for nonaqueous electrolyte secondary battery. .

  Moreover, it is preferable that the said surface of the said 2nd roller sliding with respect to the said separator film for nonaqueous electrolyte secondary batteries is formed with resin.

  Moreover, in the said conveyance process, the said 1st roller and the said 3rd roller contact one surface of the said separator film for nonaqueous electrolyte secondary batteries, and between the said 1st roller and the said 3rd roller. The second roller is in contact with the other surface of the separator film for a non-aqueous electrolyte secondary battery, so that the cleaning liquid adhered to the separator film for the non-aqueous electrolyte secondary battery in the first cleaning tank is removed. It is preferable to remove from the nonaqueous electrolyte secondary battery separator film. Further, the first roller and the third roller are in contact with one surface of the separator film for a nonaqueous electrolyte secondary battery, and the second roller is between the first roller and the third roller. Makes contact with the other surface of the separator film for non-aqueous electrolyte secondary battery, so that the second roller removes the cleaning liquid adhering to the separator film for non-aqueous electrolyte secondary battery in the first cleaning tank. It is preferable to remove from the nonaqueous electrolyte secondary battery separator film.

  Moreover, it is preferable to return the said washing | cleaning liquid removed from the said separator film for nonaqueous electrolyte secondary batteries by the said 2nd roller to the said 1st washing tank. Moreover, it is preferable that the said 2nd roller returns the said washing | cleaning liquid removed from the said separator film for nonaqueous electrolyte secondary batteries to the said 1st washing tank.

  The temperature of the cleaning liquid is preferably 20 ° C. or higher and 100 ° C. or lower.

  ADVANTAGE OF THE INVENTION According to this invention, the contamination of the washing | cleaning liquid of the downstream washing tank in the conveyance path | route of the separator film for nonaqueous electrolyte secondary batteries can be suppressed.

It is a schematic diagram which shows the cross-sectional structure of a lithium ion secondary battery. It is a schematic diagram which shows the detailed structure of the lithium ion secondary battery shown by FIG. It is a schematic diagram which shows the other structure of the lithium ion secondary battery shown by FIG. It is sectional drawing which shows the structure of the washing | cleaning apparatus which concerns on one Embodiment of this invention. It is sectional drawing of the 1st roller and 2nd roller in the washing | cleaning apparatus shown in FIG. It is sectional drawing which shows the example of arrangement | positioning of a ridge in the case of providing a ridge in a cleaning apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to FIGS.

(Lithium ion secondary battery)
Non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries have high energy density, and are therefore currently used for mobile devices such as personal computers, mobile phones, personal digital assistants, automobiles, airplanes, etc. As a battery, it is widely used as a stationary battery that contributes to the stable supply of electric power.

  FIG. 1 is a schematic diagram showing a cross-sectional configuration of a lithium ion secondary battery 1. As shown in FIG. 1, the lithium ion secondary battery 1 includes a cathode 11, a separator (film) 12, and an anode 13. An external device 2 is connected between the cathode 11 and the anode 13 outside the lithium ion secondary battery 1. Then, electrons move in the direction A when the lithium ion secondary battery 1 is charged, and in the direction B when the lithium ion secondary battery 1 is discharged.

(Separator)
The separator 12 is disposed between the cathode 11 that is the positive electrode of the lithium ion secondary battery 1 and the anode 13 that is the negative electrode thereof so as to be sandwiched between them. The separator 12 is a porous film that allows lithium ions to move between the cathode 11 and the anode 13 while separating them. The separator 12 includes, for example, polyolefin such as polyethylene and polypropylene as its material.

  FIG. 2 is a schematic diagram showing a detailed configuration of the lithium ion secondary battery 1 shown in FIG. 1, where (a) shows a normal configuration, and (b) shows a temperature rise of the lithium ion secondary battery 1. (C) shows a state when the temperature of the lithium ion secondary battery 1 is rapidly increased.

  As shown in FIG. 2A, the separator 12 is provided with a number of holes P. Usually, the lithium ions 3 of the lithium ion secondary battery 1 can come and go through the holes P.

  Here, for example, the lithium ion secondary battery 1 may be heated due to overcharge of the lithium ion secondary battery 1 or a large current caused by a short circuit of an external device. In this case, as shown in FIG. 2B, the separator 12 is melted or softened, and the hole P is closed. Then, the separator 12 contracts. Thereby, since the movement of the lithium ion 3 stops, the above-mentioned temperature rise also stops.

  However, when the lithium ion secondary battery 1 is rapidly heated, the separator 12 is rapidly contracted. In this case, as shown in FIG. 2C, the separator 12 may be broken. And since the lithium ion 3 leaks from the destroyed separator 12, the movement of the lithium ion 3 does not stop. Therefore, the temperature rise continues.

  FIG. 3 is a schematic diagram showing another configuration of the lithium ion secondary battery 1 shown in FIG. 1, where (a) shows a normal configuration, and (b) shows that the lithium ion secondary battery 1 is abruptly changed. The state when the temperature is raised is shown.

  As shown in FIG. 3A, the separator 12 may be a heat resistant separator (film) including a porous film 5 and a heat resistant layer 4. The heat-resistant layer 4 is laminated on one surface of the porous film 5 on the cathode 11 side. The heat-resistant layer 4 may be laminated on one surface of the porous film 5 on the anode 13 side, or may be laminated on both surfaces of the porous film 5. The heat-resistant layer 4 is also provided with holes similar to the holes P. Usually, the lithium ions 3 come and go through the holes P and the holes of the heat-resistant layer 4. The heat resistant layer 4 includes, for example, wholly aromatic polyamide (aramid resin) as a material thereof.

  As shown in FIG. 3B, even when the lithium ion secondary battery 1 is rapidly heated and the porous film 5 is melted or softened, the heat resistant layer 4 assists the porous film 5. Therefore, the shape of the porous film 5 is maintained. Therefore, the porous film 5 is melted or softened, and the holes P are only blocked. Thereby, since the movement of the lithium ion 3 is stopped, the above-described overdischarge or overcharge is also stopped. Thus, destruction of the separator 12 is suppressed.

  Manufacture of the separator of the lithium ion secondary battery 1 and a heat-resistant separator can be performed using the following method. Below, the case where the porous film 5 mainly contains polyethylene as the material is assumed and demonstrated. However, even when the porous film 5 contains other materials, the separator 12 (heat resistant separator) can be manufactured by the same manufacturing process.

  Examples thereof include a method in which an inorganic filler or a plasticizer is added to a thermoplastic resin to form a film, and then the inorganic filler and the plasticizer are washed away with an appropriate solvent. When the porous film 5 is a polyolefin separator formed from a polyethylene resin containing ultra-high molecular weight polyethylene, it can be produced by the following method.

  This method is (1) kneading to obtain a polyethylene resin composition by kneading ultrahigh molecular weight polyethylene and an inorganic filler (for example, calcium carbonate, silica) or a plasticizer (for example, low molecular weight polyolefin, liquid paraffin). A step, (2) a rolling step of forming a film using the polyethylene resin composition, (3) a removal step of removing the inorganic filler or plasticizer from the film obtained in step (2), and (4) It includes a stretching step of stretching the film obtained in the step (3) to obtain the porous film 5. In addition, the said process (4) can also be performed between the said processes (2) and (3).

  The removal step provides a large number of micropores in the film. The micropores of the film stretched by the stretching process become the above-described holes P. Thereby, the porous film 5 (separator 12 which does not have a heat-resistant layer) which is a polyethylene microporous film having a predetermined thickness and air permeability is obtained.

  In the kneading step, 100 parts by weight of ultra high molecular weight polyethylene, 5 to 200 parts by weight of a low molecular weight polyolefin having a weight average molecular weight of 10,000 or less, and 100 to 400 parts by weight of an inorganic filler may be kneaded.

  Thereafter, the heat-resistant layer 4 is formed on the surface of the porous film 5 in the coating process. For example, an aramid / NMP (N-methyl-pyrrolidone) solution (coating solution) is applied to the porous film 5 (coating step) and solidified (coagulating step), thereby heat-resistant layer 4 which is an aramid heat-resistant layer. Form. The heat-resistant layer 4 may be provided only on one side of the porous film 5 or on both sides.

  In the coating process, the surface of the porous film 5 is coated with a polyvinylidene fluoride / dimethylacetamide solution (coating liquid) (coating process) and solidified (coagulating process) to thereby form the porous film 5. An adhesive layer can also be formed on the surface. The adhesive layer may be provided only on one side of the porous film 5 or may be provided on both sides.

  In this specification, a layer having a function such as adhesion to an electrode or heat resistance equal to or higher than the melting point of polyolefin is referred to as a functional layer.

  The method for applying the coating liquid to the porous film 5 is not particularly limited as long as it is a method that enables uniform wet coating, and a conventionally known method can be employed. For example, a capillary coating method, a slit die coating method, a spray coating method, a dip coating method, a roll coating method, a screen printing method, a flexographic printing method, a bar coater method, a gravure coater method, a die coater method and the like can be employed. The thickness of the heat-resistant layer 4 can be controlled by the thickness of the coating wet film and the solid content concentration in the coating solution.

  A resin film, a metal belt, a drum, or the like can be used as a support for fixing or conveying the porous film 5 during coating.

  As described above, the separator 12 (heat resistant separator) in which the heat resistant layer 4 is laminated on the porous film 5 can be manufactured. The manufactured separator is wound around a cylindrical core. In addition, the object manufactured with the above manufacturing method is not limited to a heat-resistant separator. This manufacturing method does not need to include a coating process. In this case, the object to be manufactured is a separator having no heat-resistant layer.

(Washing process)
Hereinafter, the film manufacturing method and the cleaning apparatus 6 according to this embodiment will be described with reference to FIGS. 4 and 5.

  In the following embodiment, a cleaning method (film manufacturing method) of a heat-resistant separator that is a long and porous battery separator is described. The heat-resistant layer of the heat-resistant separator is formed by applying an aramid / NMP (N-methyl-pyrrolidone) solution (coating solution) to a porous film. At this time, NMP (substance to be removed) as a solvent also impregnates the pores of the porous film.

  The air permeability of the heat-resistant separator in which NMP remains in the holes is lower than the air permeability of the heat-resistant separator in which NMP does not remain in the holes. The lower the air permeability, the lower the output of the lithium ion secondary battery because the movement of lithium ions in the lithium ion secondary battery using the heat-resistant separator is hindered. For this reason, it is preferable that it can wash | clean so that NMP may not remain in the hole of a heat-resistant separator.

  FIG. 4 is a cross-sectional view showing the configuration of the cleaning device 6 according to the present embodiment. As shown in FIG. 4, the cleaning device 6 (film cleaning device) includes cleaning tanks 15 to 19. Each of the cleaning tanks 15 to 19 is filled with cleaning water W (cleaning liquid). The cleaning device 6 further includes a plurality of rotatable rollers that convey the heat-resistant separator S. Among these rollers, rollers a to n are rollers that convey the heat-resistant separator S that is cleaned in the cleaning tank 15.

  The heat-resistant separator S that has been transported from the upstream process (for example, the coating process) of the cleaning process passes through the cleaning water W (hereinafter “water”) filled in the cleaning tank 15 via the rollers a to n. The rollers a to n (conveying rollers) define the conveying path of the heat-resistant separator S in the cleaning tank 15. Also in the cleaning tanks 17 and 18, the heat-resistant separator S is transported by the rollers a to n similar to the cleaning tank 15. In the cleaning tanks 16 and 19, the heat-resistant separator S is conveyed by the rollers a to m similar to the cleaning tank 15 except that the roller n is omitted.

  The cleaning device 6 further includes a driving roller R and auxiliary rollers p and q. The driving roller R is a roller that is rotationally driven by power such as a motor. The driving roller R is driven so that the speed of the surface of the driving roller R is the same as the conveyance speed of the heat-resistant separator S. The driving roller R applies a force in the transport direction (MD: Machine direction) to the heat-resistant separator S between the cleaning tanks. The auxiliary rollers p and q define a surface range (so-called “holding angle”) in contact with the heat-resistant separator S in the driving roller R. The holding angle means an angle with respect to the axis of the roller of the arc in contact with the film on the outer periphery of the roller. The driving roller R and the auxiliary rollers p and q may be disposed in the cleaning water W, but it is not necessary to perform waterproofing treatment. Therefore, it is preferable to dispose them between the cleaning tanks as shown in FIG. .

  As described above, the driving roller R applies a force for conveyance to the heat-resistant separator S between the position of the roller a of the cleaning tank 15 and the position of the roller m of the cleaning tank 19. Here, the roller a of the cleaning tank 15 is a roller immediately before the heat-resistant separator S is carried into the cleaning tank 15. The roller m of the cleaning tank 19 is a roller immediately after the heat-resistant separator S is carried out from the cleaning tank 19.

  And it is preferable that the force by the above-mentioned drive roller R is applied to the heat-resistant separator S between the roller 1 of the cleaning tank 16 and the roller b of the cleaning tank 17. For example, after the heat-resistant separator S is unloaded from the upstream cleaning tank 16 (from the water) and before the heat-resistant separator S is loaded into the downstream cleaning tank 17 (to the water) in the transport path, It is preferable to arrange the roller R and the auxiliary rollers p and q.

  In the cleaning method according to the present embodiment, the heat-resistant separator S is transported in the longitudinal direction, and the heat-resistant separator S being transported is sequentially passed through the cleaning water W filled in the cleaning tanks 15 to 19. And a step of performing cleaning. Thus, the heat-resistant separator S is sequentially conveyed from the upstream cleaning tank to the downstream cleaning tank. Here, unless otherwise specified, “upstream” and “downstream” mean upstream and downstream in the transport direction of the separator.

  After the cleaning in the cleaning tanks 15 to 19 is completed, the heat-resistant separator S is conveyed to a downstream process (for example, a drying process) of the cleaning process.

  By passing the heat-resistant separator S through the washing water W, NMP diffuses into the water from the holes of the heat-resistant separator S. Here, the diffusion amount of NMP increases as the NMP concentration of the cleaning water W decreases.

  Since the heat-resistant separator S is sequentially washed in the washing tanks 15 to 19, the NMP concentration of the washing water W is lower in the downstream washing tank than in the upstream washing tank. That is, since the diffusion of NMP proceeds step by step, NMP clogged in the holes can be reliably removed.

  As shown in FIG. 4, the cleaning water W may flow in the direction D from the downstream cleaning tank 19 to the upstream cleaning tank 15 in the separator conveyance direction. For this purpose, for example, the barrier between the cleaning tanks 15 to 19 may be lowered toward the upstream in the separator conveyance direction. At this time, in the cleaning method according to the present embodiment, the cleaning water W is supplied to the downstream cleaning tank, and the cleaning water W in the downstream cleaning tank is supplied to the upstream cleaning tank. The step of renewing the cleaning liquid is further included. A part of the cleaning water W is discharged from the upstream cleaning tank 15. According to this, the NMP concentration of the cleaning water W in the downstream cleaning tank in the separator transport direction can be made lower than the NMP concentration of the cleaning water W in the upstream cleaning tank while effectively using the cleaning water W. it can.

  By proceeding with the diffusion of NMP stepwise, it is possible to remove NMP more efficiently than cleaning with only one cleaning tank. For this reason, the conveyance distance of the heat-resistant separator S during washing | cleaning can be shortened. Therefore, the heat-resistant separator S having a lower mechanical strength than the non-porous film can be washed while suppressing breakage and tearing.

  The wider the heat-resistant separator S, the higher the productivity. Therefore, the width of the heat-resistant separator S (the length in the direction perpendicular to the MD) is often increased to near the width of the cleaning tanks 15-19. Moreover, the width | variety of the washing tanks 15-19 is designed according to the width | variety of the heat-resistant separator S. FIG.

  When the width of the heat-resistant separator S is increased and the gap between the end of the heat-resistant separator S and the cleaning tanks 15 to 19 is narrowed, the cleaning water W filled in the cleaning tanks 15 to 19 Of the cleaning tank) and the other side (both ends of the cleaning tank (left and right ends in FIG. 4)).

  In cleaning by the cleaning tanks 15 to 19, the cleaning water W is often supplied and discharged due to overflow between the cleaning tanks. At this time, the cleaning water W divided on one side of the heat-resistant separator S is supplied and discharged, but the cleaning water W divided on the other side of the heat-resistant separator S may stay.

  Therefore, in the cleaning method according to the present embodiment, in at least one of the cleaning tanks 15 to 19, the cleaning water is promoted so as to promote the replacement of the cleaning water W between the one surface side and the other surface side of the heat-resistant separator S. A step of circulating W may be included. At this time, the cleaning device 6 may further include a circulation device having a supply / discharge port for the cleaning water W in at least one of the cleaning tanks 15 to 19. Thereby, the NMP concentration of the cleaning water W in one cleaning tank can be made more uniform, and the efficient removal of NMP can be promoted.

  The cleaning water W is not limited to water and may be any cleaning liquid that can remove NMP from the heat-resistant separator S. Further, the cleaning water W may contain a cleaning agent such as a surfactant, an acid (for example, hydrochloric acid) or a base. And it is preferable that the temperature of the washing water W is 120 degrees C or less. At this temperature, the heat-resistant separator S is less likely to heat shrink. The temperature of the washing water W is more preferably 20 ° C. or higher and 100 ° C. or lower.

  The cleaning method for the heat-resistant separator S described above can also be applied to a method for cleaning a separator (for example, a polyolefin separator) that does not have a heat-resistant layer.

  The separator is formed, for example, by forming a polyolefin resin composition obtained by kneading a high molecular weight polyolefin such as ultrahigh molecular weight polyethylene and an inorganic filler or a plasticizer into a film and stretching it. Then, the pores of the separator are formed by washing away the inorganic filler or plasticizer (substance to be removed).

  The air permeability of the separator in which the removal target substance remains in the hole without being washed away is lower than the air permeability of the separator in which the removal target substance does not remain in the hole. The lower the air permeability, the lower the output of the lithium ion secondary battery because the movement of lithium ions in the lithium ion secondary battery using the separator is hindered. For this reason, it is preferable that it can wash | clean so that the said removal target substance may not remain in the hole of a separator.

  The cleaning liquid for cleaning the separator containing the inorganic filler may be any cleaning liquid that can remove the inorganic filler from the separator. Preferably, it is an aqueous solution containing an acid or a base.

  The cleaning liquid for cleaning the separator containing the plasticizer may be any cleaning liquid that can remove the plasticizer from the separator. An organic solvent such as dichloromethane is preferred.

  To summarize the above, the method for cleaning a polyolefin resin composition (film) formed into a film is a process of transporting a long film, which is an intermediate product of a separator, in its longitudinal direction, and this film being transported, And a step of performing cleaning by sequentially passing through the cleaning liquid filled in the above-described cleaning tanks 15 to 19.

  Thus, in FIG. 4, the heat-resistant separator S may be a film that is an intermediate product of the separator. The washing water W may be an aqueous solution containing an acid or a base.

  And the manufacturing method of a polyolefin separator is the intermediate | middle product of a long and porous separator, The shaping | molding process which shape | molds the elongate film which has polyolefin as a main component, The above-mentioned execution process is performed after this shaping | molding process. It can be interpreted that each step included in the film cleaning method is included.

  The manufacturing method of the heat-resistant separator S using the washing | cleaning method of the heat-resistant separator S which is a laminated separator is also contained in this invention. Here, the heat-resistant separator S is a laminated separator including the porous film 5 (base material) shown in FIG. 3 and the heat-resistant layer 4 (functional layer) laminated on the porous film 5. And this manufacturing method can be interpreted as including the formation process of shape | molding the long and porous heat-resistant separator S, and each process of the above-mentioned separator washing | cleaning method performed after the said formation process.

  In the “molding step”, in order to laminate the heat-resistant layer 4, an NMP (liquid material) containing an aramid resin (material) constituting the heat-resistant layer 4 is applied to the porous film 5. A coagulation step for coagulating the aramid resin.

  “Each step” refers to a step of transporting the heat-resistant separator S in the longitudinal direction, and the heat-resistant separator S being transported by sequentially passing through the cleaning water W filled in the cleaning tanks 15 to 19. It means a process to be performed.

  As described above, it is possible to produce a laminated separator that has less NMP and that is prevented from being broken or broken. The heat-resistant layer may be the above-described adhesive layer.

(M-shaped path)
From here, the roller m, the roller n, and the roller a with which the washing | cleaning apparatus 6 is provided are demonstrated in detail. Here, the roller m, the roller n, and the roller a which are arrange | positioned between the washing tank 15 and the washing tank 16 are demonstrated. However, the same applies to the rollers m, n, and a disposed between the cleaning tank 17 and the cleaning tank 19.

  FIG. 5 is a cross-sectional view of a pair of roller m, roller n, and roller a in the cleaning device 6 shown in FIG. A set of roller m (first roller), roller n (second roller), and roller a (third roller) includes an upstream cleaning tank 15 (first cleaning tank) and a downstream cleaning tank 16 in the transport path. (Second cleaning tank). The roller n is disposed between the roller m and the roller a. In the top view, the roller m and the roller n are positioned within the cleaning tank 15, and the roller a is positioned within the cleaning tank 16. The rollers m, n, and a may be drive rollers that are rotationally driven by power, or may be driven rollers that rotate by frictional force with the heat-resistant separator S. Here, the speed of the surface of each roller m, n, a and the conveyance speed of the heat-resistant separator S are the same.

  The heat-resistant separator S carried out from the washing tank 15 (from the water) contacts the roller m, the roller n, and the roller a in this order, and is carried into the washing tank 16 (in the water). The roller m, the roller n, and the roller a convey the heat-resistant separator S between the cleaning tanks (conveying step).

  The rollers m and a are in contact with one surface Sm of the heat resistant separator S. Between the roller m and the roller a, the roller n contacts the other surface Sn of the heat-resistant separator S. The rollers m and a support one side (lower side) of the heat resistant separator S, and the roller n presses the heat resistant separator S from the other side (upper side) of the heat resistant separator S. With the roller n as a boundary, the conveyance direction of the heat-resistant separator S changes from descending to ascending. The heat-resistant separator S passes through the M-shaped conveyance path when viewed from the axial direction of the roller m. The cleaning water W adhering to the surface Sm side of the heat resistant separator S is removed from the heat resistant separator S by the contact of the roller m. Moreover, the cleaning water W adhering to the surface Sn side of the heat-resistant separator S is removed from the heat-resistant separator S by the contact of the roller n. The cleaning water W adhering to the heat-resistant separator S carried out from the cleaning tank 15 has the same degree of contamination as the cleaning water W filled in the cleaning tank 15 (equivalent concentration of the removal object).

  The cleaning water W removed from the surface Sm by the roller m returns to the upstream cleaning tank 15. Similarly, the cleaning water W removed from the surface Sn by the roller n returns to the upstream cleaning tank 15. For example, the washing water W moves on the upper surface Sn of the heat-resistant separator S along the roller n in the width direction of the heat-resistant separator S, and spills from the end of the heat-resistant separator S.

  If the rollers m and n are within the range of the cleaning tank 15 in the top view, the cleaning water W that has fallen from the rollers m and n returns to the cleaning tank 15. Alternatively, if at least the lower ends of the rollers m and n are within the range of the cleaning tank 15, the cleaning water W that has fallen from the rollers m and n returns to the cleaning tank 15. Alternatively, a tub may be provided below the rollers m and n, and the removed cleaning water W may be returned to the cleaning tank 15 through the tub.

  Thereby, the moisture adhering to both surfaces of the heat-resistant separator S carried out from the cleaning tank 15 is removed from the heat-resistant separator S and dropped into the cleaning tank 15. As a result, the amount of cleaning water W filled in the cleaning tank 15 (which is dirty from the cleaning water W filled in the cleaning tanks 16 to 19) is brought into the cleaning tanks 16 to 19 on the downstream side of the cleaning tank 15. Can be reduced. Therefore, it becomes possible to prevent contamination of the cleaning water W filled in the cleaning tanks 16 to 19 (increase in the concentration of the removal target). In addition, by removing the liquid having a high concentration of the removal object attached to the surface of the heat-resistant separator S from the surface of the heat-resistant separator S between the washing tanks, it is more efficiently removed from the heat-resistant separator S in the downstream washing tank. Things can be diffused.

  FIG. 6 is a cross-sectional view showing an example of the arrangement of the scissors when the scissors are provided in the cleaning device. As shown in FIG. 6, a gutter 20 may be provided between the cleaning tank 15 and the cleaning tank 16. Here, in the top view, the lowest point of the rollers n and a is included in the range of the ridge 20. When a ridge is provided on the lower side of the roller m, the roller n, or the roller a, the roller does not need to be located within the range of the cleaning tank 15. Here, the roller n is located between the cleaning tank 15 and the cleaning tank 16. The washing water W that has fallen from the roller m returns to the washing tank 15 as it is. The washing water that has fallen from the rollers n and a is received by the basket 20 and returns to the washing tank 15 through the basket 20.

  When viewed from the transverse direction (TD), the rotational axes of the three rollers m, n, and a are preferably arranged in a straight line. In other words, it is preferable that the rotation axes of the three rollers m, n, and a are located on one plane. Further, the holding angle of the roller n is preferably less than 180 degrees. The hugging angle means an angle of an arc with which the heat resistant separator S is in contact with the roller axis. That is, the conveyance direction of the heat-resistant separator S before and after the roller is changed by the holding angle of the roller.

(Roller rotation)
The speed of the surface np of the roller n may be different from the transport speed of the heat resistant separator S. That is, the surface np (curved surface) of the roller n and the heat resistant separator S slide. In this case, the roller n may be a driving roller that is rotationally driven at a predetermined speed, or may be a driven roller. When the surface np of the roller n and the heat resistant separator S slide, it is preferable that the surface np of the roller n (portion in contact with the heat resistant separator S) is formed of a resin. If the surface np of the roller n is a resin, the frictional force with the heat-resistant separator S can be reduced, and wear and breakage of the heat-resistant separator S can be suppressed.

  When the roller n is a driven roller, the surface np of the roller n can be dragged by the heat-resistant separator S by increasing the frictional force between the roller n and its shaft to some extent.

  When the roller n is a driving roller, the direction in which the surface np of the roller n rotates may be the same as or different from the conveyance direction of the heat-resistant separator S. When the direction in which the surface np of the roller n rotates is different from the conveying direction of the heat-resistant separator S, the cleaning water W is more efficiently removed from the surface Sn of the heat-resistant separator S by sliding between the roller n and the heat-resistant separator S. be able to.

  The roller n may be fixed so as not to rotate. The surface of the roller n may be made of metal.

  The rollers m and a may have the same configuration as the roller n.

(Roller surface shape)
Moreover, the uneven | corrugated shape may be provided in the surface np of the roller n. For example, a spiral groove, a curved groove, or a linear groove may be formed on the surface np of the roller n as an uneven shape. The groove on the surface np of the roller n preferably extends beyond the end of the heat resistant separator S in the width direction of the heat resistant separator S. Thereby, the washing water removed between the roller n and the heat resistant separator S passes through the groove and is discharged to the outside in the width direction from the heat resistant separator S. It is preferable that the spiral groove is formed in such a direction that the portion facing the heat resistant separator S is shifted to the outside in the width direction of the heat resistant separator S with time. Moreover, the linear groove | channel may be formed so that it may become parallel to the axis | shaft of the roller n.

  Similarly, uneven shapes (grooves) may be formed on the surfaces of the rollers m and a. A trough may be provided on the lower side of the roller a so that the cleaning water W removed by the roller a returns to the cleaning tank 15.

  In the cleaning device 6, instead of the heat-resistant separator S, various types of films such as a separator having no functional layer or a plastic film having no holes may be cleaned.

[Another interpretation of this embodiment]
This embodiment can also be interpreted as follows.

  In the film manufacturing method according to the present embodiment, the first roller, the second roller, and the third roller are brought into contact with the film that has been washed out from the first washing tank and the washing process for washing the film in the first washing tank. And transporting the film to a second cleaning tank, wherein the first roller and the third roller are in contact with one surface of the film, and the first roller and When the second roller comes into contact with the other surface of the film between the third roller, the cleaning liquid is removed from the film, and the cleaning liquid removed from the film by the second roller is removed from the first roller. Return to the washing tank.

  According to said structure, the washing | cleaning liquid adhering to both surfaces of the film is removed by the 1st roller and the 2nd roller between washing tanks. The cleaning liquid removed by the second roller is returned to the upstream first cleaning tank. Therefore, the amount of the cleaning liquid in the first cleaning tank brought into the downstream second cleaning tank can be reduced. Therefore, contamination of the cleaning liquid in the second cleaning tank can be suppressed.

  Moreover, the speed of the surface of the second roller may be different from the transport speed of the film.

  According to said structure, a 2nd roller and a film slide. Therefore, the cleaning liquid adhering to the film can be removed more efficiently.

  Further, the second roller may be rotationally driven.

  According to said structure, a film can be pulled in a conveyance direction by making the speed of the surface of a 2nd roller more than the conveyance speed of a film. The film passing through the liquid is resisted by the viscosity of the liquid. By driving the second roller between the cleaning tanks, it is possible to reduce the film tension on the upstream side of the second roller and prevent the film from being broken. Moreover, the washing | cleaning liquid adhering to a film can be more efficiently removed by making the speed of the surface of a 2nd roller less than the conveyance speed of a film.

  Moreover, the uneven | corrugated shape may be provided in the surface of the said 2nd roller.

  According to said structure, the washing | cleaning liquid removed from the film by uneven | corrugated shape can be efficiently discharged | emitted to the outer side of a film.

  A spiral, curved, or linear groove may be provided on the surface of the second roller.

  According to said structure, the washing | cleaning liquid removed from the film can be discharged | emitted through a groove | channel.

  The groove of the second roller may extend beyond the end of the film in the width direction of the film.

  According to said structure, the washing | cleaning liquid removed from the film can be discharged | emitted to the outer side in the width direction of a film through a groove | channel.

  Moreover, the said surface of the said 2nd roller sliding with respect to the said film may be formed with resin.

  According to said structure, abrasion or a fracture | rupture of a film can be prevented.

  The film cleaning apparatus according to the present embodiment is in contact with the first cleaning tank and the second cleaning tank for cleaning the film, and the film carried out from the first cleaning tank, and the second cleaning tank A first roller, a second roller, and a third roller, wherein the first roller and the third roller are in contact with one surface of the film, and the first roller and the third roller When the second roller contacts the other surface of the film between the rollers, the second roller removes the cleaning liquid from the film, and the cleaning liquid removed from the film by the second roller is It is the structure which returns to 1 washing tank.

  The surface speed of the second roller may be different from the film transport speed.

  The second roller may be configured to be driven to rotate.

  Moreover, it is good also as a structure by which the uneven | corrugated shape is provided in the surface of the said 2nd roller.

  Moreover, it is good also as a structure by which the spiral or linear groove | channel is provided in the said surface of the said 2nd roller.

  Further, the groove of the second roller may extend beyond the end of the film in the width direction of the film.

  Moreover, the said surface of the said 2nd roller sliding with respect to the said film is good also as a structure currently formed with resin.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

6 Cleaning device (film cleaning device)
12 Separator (film)
15, 16 Cleaning tank (first cleaning tank, second cleaning tank)
S Heat-resistant separator (film)
W Wash water (cleaning liquid)
m Roller (first roller)
n Roller (second roller)
a Roller (3rd roller)

Claims (20)

A cleaning step of cleaning the separator film for the non-aqueous electrolyte secondary battery in the first cleaning tank;
The first roller, the second roller, and the third roller are brought into contact with the separator film for a non-aqueous electrolyte secondary battery carried out from the first washing tank, and the separator film for the non-aqueous electrolyte secondary battery is brought into contact with the separator film for the non-aqueous electrolyte secondary battery. A transporting process for transporting to the second cleaning tank,
In the transport process,
The first roller and the third roller are in contact with one surface of the separator film for a non-aqueous electrolyte secondary battery, and the second roller is between the first roller and the third roller. The non-aqueous electrolyte secondary battery separator film is contacted with the other surface of the non-aqueous electrolyte secondary battery separator film to remove the cleaning liquid from the non-aqueous electrolyte secondary battery separator film. To the second washing tank,
A method for producing a separator film for a non-aqueous electrolyte secondary battery, wherein the cleaning liquid filled in the first cleaning tank and the cleaning liquid filled in the second cleaning tank are the same type.   The speed of the surface of the said 2nd roller is a separator film manufacturing method for non-aqueous-electrolyte secondary batteries of Claim 1 different from the conveyance speed of the said separator film for non-aqueous-electrolyte secondary batteries. The second roller is driven to rotate,
The separator film manufacturing method for a non-aqueous electrolyte secondary battery according to claim 1, wherein the second roller is a driving roller that is rotationally driven by power.   The method for producing a separator film for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein an uneven shape is provided on a surface of the second roller.   The separator film manufacturing method for a nonaqueous electrolyte secondary battery according to claim 4, wherein a spiral, curved, or linear groove is provided on the surface of the second roller.   The groove of the second roller extends in the width direction of the non-aqueous electrolyte secondary battery separator film beyond the end of the non-aqueous electrolyte secondary battery separator film. Manufacturing method of separator film for non-aqueous electrolyte secondary battery.   The method for producing a separator film for a non-aqueous electrolyte secondary battery according to claim 2, wherein the surface of the second roller that slides with respect to the separator film for the non-aqueous electrolyte secondary battery is formed of a resin. . In the transport process,
The first roller and the third roller are in contact with one surface of the separator film for a non-aqueous electrolyte secondary battery, and the second roller is between the first roller and the third roller. By contacting the other surface of the separator film for a non-aqueous electrolyte secondary battery, the cleaning liquid adhering to the separator film for the non-aqueous electrolyte secondary battery in the first cleaning tank is removed from the non-aqueous electrolyte secondary battery. The method for producing a separator film for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein the separator film is removed from the battery separator film.   The nonaqueous electrolyte secondary battery according to any one of claims 1 to 8, wherein the cleaning liquid removed from the separator film for a nonaqueous electrolyte secondary battery by the second roller is returned to the first cleaning tank. Separator film manufacturing method.   The method for producing a separator film for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 9, wherein the temperature of the cleaning liquid is 20 ° C or higher and 100 ° C or lower. A first washing tank and a second washing tank for washing a separator film for a non-aqueous electrolyte secondary battery;
A first roller that contacts the separator film for a non-aqueous electrolyte secondary battery unloaded from the first cleaning tank and conveys the separator film for a non-aqueous electrolyte secondary battery to a second cleaning tank; A second roller and a third roller;
The first roller and the third roller are in contact with one surface of the separator film for a non-aqueous electrolyte secondary battery, and the second roller is between the first roller and the third roller. By contacting the other surface of the separator film for a nonaqueous electrolyte secondary battery, the second roller removes the cleaning liquid from the separator film for the nonaqueous electrolyte secondary battery, and then the nonaqueous electrolyte solution. Transport the secondary battery separator film to the second washing tank,
A separator film cleaning apparatus for a non-aqueous electrolyte secondary battery, wherein the cleaning liquid filled in the first cleaning tank and the cleaning liquid filled in the second cleaning tank are the same type.   The separator film cleaning device for a non-aqueous electrolyte secondary battery according to claim 11, wherein a speed of the surface of the second roller is different from a conveyance speed of the separator film for a non-aqueous electrolyte secondary battery. The second roller is driven to rotate,
The separator film cleaning device for a non-aqueous electrolyte secondary battery according to claim 11 or 12, wherein the second roller is a driving roller that is rotationally driven by power.   The separator film washing | cleaning apparatus for nonaqueous electrolyte secondary batteries as described in any one of Claim 11 to 13 with which uneven | corrugated shape is provided in the surface of the said 2nd roller.   The separator film cleaning device for a non-aqueous electrolyte secondary battery according to claim 14, wherein a spiral, curved, or linear groove is provided on the surface of the second roller.   The groove of the second roller extends in the width direction of the non-aqueous electrolyte secondary battery separator film beyond the end of the non-aqueous electrolyte secondary battery separator film. Separator film cleaning device for non-aqueous electrolyte secondary battery.   The separator film cleaning device for a non-aqueous electrolyte secondary battery according to claim 12, wherein the surface of the second roller that slides with respect to the separator film for the non-aqueous electrolyte secondary battery is formed of a resin. .   The first roller and the third roller are in contact with one surface of the separator film for a non-aqueous electrolyte secondary battery, and the second roller is between the first roller and the third roller. By contacting the other surface of the separator film for a non-aqueous electrolyte secondary battery, the second roller removes the cleaning liquid adhering to the separator film for the non-aqueous electrolyte secondary battery in the first cleaning tank. The separator film washing | cleaning apparatus for nonaqueous electrolyte secondary batteries as described in any one of Claim 11 to 17 removed from the separator film for water electrolyte secondary batteries.   The non-aqueous electrolyte secondary battery according to any one of claims 11 to 18, wherein the second roller returns the cleaning liquid removed from the non-aqueous electrolyte secondary battery separator film to the first cleaning tank. Separator film cleaning device.   The separator film cleaning device for a non-aqueous electrolyte secondary battery according to any one of claims 11 to 19, wherein the temperature of the cleaning liquid is 20 ° C or higher and 100 ° C or lower.

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