JP2018010858A - Separator winding core, separator wound body, and method of manufacturing separator wound body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a separator winding core which has a large frictional force between side faces and which is less likely to collapse even when stacked.SOLUTION: There is provided a separator winding core, at least two of which can be stacked while side faces where a separator is not wound are in an up-and-down direction, at least one face of the side faces having an arithmetic average roughness of 0.16 μm or more.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a separator core used when winding a separator for a non-aqueous electrolyte secondary battery, a separator wound body in which the separator is wound around the separator core, and a method for manufacturing the separator wound body About.

  In Patent Document 1, a separator for a non-aqueous electrolyte secondary battery that is continuously manufactured while being transported by a transport system such as a roller, and the separator that is wound when the manufactured separator is supplied as a product An example of a shape related to a winding core (hereinafter also referred to as “core”) is given.

  The core disclosed in Patent Document 1 includes an outer cylindrical member around which a separator is wound, an inner cylindrical member that functions as a bearing for fitting a shaft, and a support member (hereinafter referred to as “rib”) connected to the outer cylindrical member and the inner cylindrical member. The manufactured separator is supplied as a wound body wound around the outer cylindrical member.

JP 2013-139340 A (published July 18, 2013)

  When the outer peripheral surface is damaged by contact with other cores, the ground, or the like, the above-described core becomes a cause of damage to the separator wound around the outer peripheral surface. For this reason, when storing the core, it is required that the outer peripheral surface of the outer cylindrical member of the core be stored such that it does not come into contact with another core, the ground, or the like.

  As a method for storing the core so that the outer peripheral surface thereof does not come into contact with another core, the ground, or the like, a method for stacking and storing the core so that the side surface of the core is in the vertical direction can be mentioned.

  Moreover, the separator can be stored by winding the manufactured separator on a core and storing it as a separator winding body. Also in this case, since the separator width is usually narrower than the core width, the separator roll body has a side face in the vertical direction so that the separator does not come into contact with other cores, other separators, and the ground. A method of stacking and storing wound bodies is mentioned.

  However, it is assumed that a human hand or the like accidentally collides with the stacked core, or that the core is subjected to an impact or vibration, such as transporting the stacked core. In the above storage method, when the frictional force on the side surface of the core is small, there may be a problem that the core slides and the stacked core collapses due to the occurrence of impact or vibration. Similar problems can occur even when separator rolls are stacked and stored.

  In Patent Document 1, there is no specification regarding the storage method of the core and separator winding body and the frictional force on the side surface, and the same problem is assumed.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a separator core that is easy to handle by a large frictional force on the side surface and prevents slipping due to impact, and the like. It is to realize the revolution.

  In order to solve the above problems, a separator core according to the present invention is a separator core around which a separator for a non-aqueous electrolyte secondary battery is wound, and the separator core The arithmetic average roughness of at least one of the side surfaces that are not rotated is 0.16 μm or more. According to the above configuration, since the frictional force on the side surface is large, it is possible to provide a separator core that can be prevented from slipping and slipping and is easy to handle.

  In the above configuration, the average value of the surface roughness may be 3 μm or less. According to the said structure, the separator core which can be wash | cleaned easily can be provided, maintaining the above-mentioned advantage.

  The said structure WHEREIN: 0.9 micrometer or less may be sufficient as the average value of the said surface roughness. According to the said structure, the separator core which can wash | clean more easily can be provided, maintaining the above-mentioned advantage.

  The said structure WHEREIN: The said separator core may be able to pile up at least 2 by making the said side surface into an up-down direction. According to the said structure, a separator core can be piled up and stored.

  In the above configuration, the material may include any of ABS resin, polyethylene resin, polypropylene resin, polystyrene resin, polyester resin, and vinyl chloride resin. According to the said structure, a separator core can be manufactured by resin molding using a metal mold | die.

  Moreover, the separator wound body according to the present invention is characterized in that the separator is wound around the separator core. According to the above configuration, it is possible to provide a separator wound body that can be easily stored and a separator wound around the separator wound body.

  The separator winding body manufacturing method according to the present invention is a separator winding body manufacturing method in which a separator for a non-aqueous electrolyte secondary battery is wound around a separator core, and the separator is manufactured. In the separator manufacturing process, and in the separator core, the separator is wound around the separator core having an arithmetic average roughness of at least one side of the side surface, which is a surface on which the separator is not wound, of 0.16 μm or more. And a winding step.

  In the manufacturing method, the arithmetic average roughness may be 3 μm or less.

  In the manufacturing method, the arithmetic average roughness may be 0.9 μm or less.

  INDUSTRIAL APPLICABILITY The present invention can provide a separator core and a separator wound body that are not easily collapsed even when the side surfaces are stacked in the vertical direction and are easy to handle during storage.

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 mode in each state of the lithium ion secondary battery shown by FIG. It is a schematic diagram which shows the mode in each state of the lithium ion secondary battery of another structure. It is a schematic diagram which shows the structure of the slit apparatus which slits a separator. It is a front view of the separator winding body which wound the separator around the separator core and the separator core according to the embodiment of the present invention. It is a figure which shows the example of the storage method of the separator core which concerns on embodiment of this invention. It is a figure which shows the example of the storage method of the separator core which concerns on a reference form.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. Below, the heat-resistant separator for batteries, such as a lithium ion secondary battery, is demonstrated as an example of the battery separator film wound by the separator film core (core) based on this invention.

<Configuration of lithium ion secondary battery>
First, a lithium ion secondary battery will be described with reference to FIGS.

  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 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 allows the lithium ions to move between the cathode 11 and the anode 13 while separating them. As the material of the separator 12, for example, polyolefin such as polyethylene and polypropylene is used.

  FIG. 2 is a schematic diagram showing the state of each state of the lithium ion secondary battery 1 shown in FIG. 2A shows a normal state, FIG. 2B shows a state when the lithium ion secondary battery 1 is heated, and FIG. 2C shows when the lithium ion secondary battery 1 is rapidly heated. The state of is shown.

  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 an 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 traffic of the lithium ion 3 stops, the above-mentioned temperature rise is also stopped.

  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 traffic of the lithium ion 3 does not stop. Therefore, the temperature rise continues.

<Heat-resistant separator>
FIG. 3 is a schematic diagram showing a state of each state of the lithium ion secondary battery 1 having another configuration. 3A shows a normal state, and FIG. 3B shows a state when the temperature of the lithium ion secondary battery 1 is rapidly increased.

  As shown in FIG. 3A, the lithium ion secondary battery 1 may further include a heat resistant layer 4. This heat-resistant layer 4 can be provided on the separator 12. FIG. 3A shows a configuration in which the separator 12 is provided with a heat-resistant layer 4 as a functional layer. Hereinafter, a film in which the heat-resistant layer 4 is provided on the separator 12 is referred to as a heat-resistant separator 12a as an example of a separator with a functional layer. Moreover, the separator 12 in the separator with a functional layer is used as a base material with respect to the functional layer.

  In the configuration shown in FIG. 3A, the heat-resistant layer 4 is laminated on one side of the separator 12 on the cathode 11 side. The heat-resistant layer 4 may be laminated on one surface of the separator 12 on the anode 13 side, or may be laminated on both surfaces of the separator 12. 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 separator 12 melts or softens, the heat-resistant layer 4 assists the separator 12. The shape of is maintained. Therefore, the separator 12 is melted or softened, and the hole P is only blocked. Thereby, since the traffic of the lithium ion 3 stops, the above-mentioned overdischarge or overcharge is also stopped. Thus, destruction of the separator 12 is suppressed.

<Manufacturing process of separator / heat-resistant separator>
The production of the separator and the heat-resistant separator of the lithium ion secondary battery 1 is not particularly limited, and can be performed using a known method. Below, the case where the porous film which is a raw material of a separator (heat-resistant separator) mainly contains polyethylene as the material is demonstrated. However, even when the porous film contains other materials, a separator (heat-resistant separator) can be manufactured by the same manufacturing process.

  For example, after adding an inorganic filler or a plasticizer to a thermoplastic resin to form a film, the inorganic filler and the plasticizer are washed and removed with an appropriate solvent. For example, when the porous film 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 step (3) to obtain a porous film. 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, a porous film (separator 12) 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, in the coating process, the heat-resistant layer 4 is formed on the surface of the porous film. For example, an aramid / NMP (N-methyl-pyrrolidone) solution (coating solution) is applied to the porous film to form the heat-resistant layer 4 that is an aramid heat-resistant layer. The heat-resistant layer 4 may be provided only on one side of the porous film or on both sides. Moreover, you may apply the liquid mixture containing fillers, such as an alumina / carboxymethylcellulose, as the heat-resistant layer 4. FIG.

  In the coating process, a polyvinylidene fluoride / dimethylacetamide solution (coating solution) is applied (coating process) to the surface of the porous film, and then precipitated (precipitation process). An adhesive layer can also be formed. The adhesive layer may be provided only on one side of the porous film or on both sides.

  The method for applying the coating solution to the porous film is not particularly limited as long as it can uniformly wet coat, and a conventionally known method can be adopted. For example, a capillary coating method, a spin 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, etc. Can do. 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 polyolefin-based porous film during coating.

  As described above, the separator 12 (heat resistant separator) in which the heat resistant layer 4 is laminated on the porous film 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.

<Slit device>
The heat-resistant separator or the separator having no heat-resistant layer (hereinafter referred to as “separator”) preferably has a width (hereinafter referred to as “product width”) suitable for application products such as the lithium ion secondary battery 1. However, in order to increase productivity, the separator is manufactured such that its width is equal to or greater than the product width. Once manufactured, the separator is cut (slit) to the product width.

  The “separator width” means the length of the separator in the direction parallel to the plane in which the separator extends and perpendicular to the longitudinal direction of the separator. Hereinafter, the wide separator before being slit is referred to as “original fabric”, and the slit separator is particularly referred to as “slit separator”. The slit means that the separator is cut along the longitudinal direction (film flow direction in manufacturing, MD: Machine direction), and the cut means that the separator is cut along the transverse direction (TD). Means to cut. The transverse direction (TD) means a direction parallel to the plane in which the separator extends and substantially perpendicular to the longitudinal direction (MD) of the separator.

  4A and 4B are schematic views showing the configuration of the slit device 6 that slits the separator. FIG. 4A shows the overall configuration, and FIG. 4B shows the configuration before and after slitting the original fabric.

  As shown in FIG. 4A, the slit device 6 includes a cylindrically-shaped unwinding roller 61, rollers 62 to 69, and a plurality of winding rollers 70U and 70L that are rotatably supported. .

<Before slit>
In the slit device 6, a cylindrical core c around which an original fabric is wound is fitted on the unwinding roller 61. As shown in FIG. 4B, the original fabric is unwound from the core c to the path U or L. The unwound original fabric is conveyed to the roller 68 via the rollers 63 to 67. In the transporting process, the original fabric is slit into a plurality of separators. In addition, in order to convey an original fabric by a desired track | orbit, you may change the number and arrangement | positioning of the rollers 62-69.

<After slit>
As shown in (b) of FIG. 4, some of the plurality of slit separators are respectively wound around cylindrical cores u fitted to the winding roller 70U. Further, the other part of the plurality of slit separators is wound around each of the cylindrical cores 1 (separator cores) fitted to the winding roller 70L. Note that an integrated body of the slit separator and the core u · l wound up in a roll shape is referred to as a “rolled body (separator wound body)”.

<Separator core and separator wound body>
FIG. 5 is a front view of a core and a wound body in which a separator is wound around the core.

  A shaft such as a winding roller is fitted to the inner cylindrical member 102 of the core 100 shown in FIG. 5A, and the separator 12 is rubbed against the outer cylindrical member 101 with a constant tension while rotating the core 100. The wound body 110 shown in (b) can be manufactured.

  The above-described core 100 can be applied to, for example, the cores u and l of the slit device 4 shown in FIG. That is, winding of the separator 12 using the core 100 can be performed in the same manner as described above.

<Core structure>
A core 100 shown in FIG. 5A includes an outer cylindrical member 101, an inner cylindrical member 102, and a plurality of ribs 103. The outer cylindrical member 101 defines the outer peripheral surface of the core 100 around which the separator 12 is wound. The inner cylindrical member 102 is provided inside the outer cylindrical member 101 and functions as a bearing into which a shaft such as a winding roller that rotates the core is fitted. The rib 103 is a support member that extends in the radial direction between the outer cylindrical member 101 and the inner cylindrical member 102 and is connected to both.

  In the present embodiment, the ribs 103 are equally spaced from each other, and are arranged at positions where the circumference is equally divided into eight so as to be perpendicular to the outer cylindrical member 101 and the inner cylindrical member 102. However, the number of ribs and the arrangement interval are not limited thereto.

  Further, it is preferable that the circumferential centers of the outer cylindrical member 101 and the inner cylindrical member 102 substantially coincide with each other, but the present invention is not limited to this. Furthermore, the thickness of the outer cylindrical member 101 and the inner cylindrical member 102, the width of the outer peripheral surface, the radius, and other dimensions can be appropriately designed according to the type of separator to be manufactured.

  The mass of the core 100 is usually 250 g to 800 g.

Side area of the separator 12 of the core 100 is not wound is ^usually 10cm ² ~80cm 2.

  Moreover, the mass of the wound body 110 is 400g-6000g normally.

  As the material of the core 100, a resin including any one of an ABS resin, a polyethylene resin, a polypropylene resin, a polystyrene resin, a polyester resin, and a vinyl chloride resin can be suitably used. Thereby, the core 100 can be manufactured by resin molding using a mold.

<Stacking of cores>
FIG. 6 is a diagram illustrating a state in which the cores 100 are stacked.

  If the outer peripheral surface of the outer cylindrical member 101 around which the separator 12 is wound is damaged by contact with the ground or the like, the separator 12 wound by the scratch is damaged. In addition, foreign matter may accumulate on the scratch, and the foreign matter deposited on the wound separator 12 may be attached, which may cause the separator 12 to become defective.

  For this reason, when storing the core, it is required that the outer peripheral surface of the outer cylindrical member 101 is not brought into contact with the ground or the like as much as possible.

  As shown in FIG. 6, the plurality of cores 100 are stacked and stored with the side surface of the core 100 where the separator 12 is not wound up and down, so that the outer peripheral surface of the outer cylindrical member 101 can be stored without contacting the ground. It can be carried out.

  In FIG. 6, three cores 100 are stacked, but it is sufficient that at least two cores 100 can be stacked. It is also possible to store four or more cores stacked.

  However, at the time of actual storage, it is conceivable that a person or an object accidentally contacts the stacked core 100. Further, when the stacked cores 100 are transported together, it is assumed that the cores 100 are vibrated.

  As described above, when an impact, vibration, or the like occurs in the stacked cores 100, if the frictional force between the side surfaces of the stacked cores 100 is small, the cores 100 may be greatly displaced and the stacked cores 100 may be collapsed. Conceivable.

<Fixing method of core>
As an example of a method of fixing the stacked cores 100 so as not to collapse, a method of using a pedestal 120 having a substantially vertical long cylindrical shaft at the approximate center of a cylindrical plane as shown in FIG. Can be considered.

  The diameter of the shaft of the pedestal 120 is slightly smaller than the inner diameter of the inner cylindrical member 102 of the core 100. As shown in FIG. 7B, the core 100 can be fixed by stacking the core 100 through the hole of the inner cylindrical member 102 of the core 100 through the shaft of the pedestal 120.

  However, when the core 100 is stored using the pedestal 120, when the core 100 is stacked on the pedestal, it is necessary to move the core 100 greatly from the top to the bottom of the axis of the pedestal 120. Conversely, when the core 100 is taken out from the pedestal 120, it is necessary to move the core 100 from the bottom to the top of the pedestal 120. For this reason, it takes time and labor to handle the core 100, which causes inefficiency of work.

  Further, when the core 100 is stacked on the pedestal 120 or removed from the pedestal 120, the shaft of the pedestal 120 and the inner peripheral surface of the inner cylindrical member 102 may be rubbed. As a result, the inner cylindrical member 102 is also scratched, and foreign matter or the like accumulates on the scratch and adheres to the separator 12.

<Surface roughness of the side>
From the above problems, it is required to prevent the stacked core 100 from being displaced without requiring a fixture such as the pedestal 120. As a method of solving this problem, a method of improving the frictional force on the side surface of the core 100 and reducing the deviation between the cores 100 can be considered.

  When the frictional force between the side surfaces of the core 100 is sufficiently large, even if a certain amount of external force is generated in the stacked cores 100, the core 100 can be prevented from collapsing because the cores 100 are not displaced.

  The inventor has focused on improving the surface roughness on the side surfaces of the cores 100 as a method for improving the frictional force between the cores 100.

  As a reference for the surface roughness, for example, an arithmetic average roughness that represents the size per unit area of the absolute value of the unevenness of the surface based on the average height of the surface can be employed. The frictional force between the surfaces having a large arithmetic average roughness tends to increase. However, if the arithmetic average roughness is too large, it becomes close to point contact and may be rather small. Therefore, from the viewpoint of improving the frictional force on the side surface of the core 100, the arithmetic average roughness on the side surface of the core 100 is preferably 10 μm or less, and more preferably 3 μm or less.

  The arithmetic average roughness on the side surface of the core 100 is more preferably in the above range on both side surfaces of the core 100.

  The arithmetic average roughness of the side surface of the core 100 can be adjusted by roughening the surface of the separator core by blasting or the like, or smoothing by polishing or the like. In addition, the arithmetic average roughness of the side surface of the core 100 can be adjusted by processing the mold itself used for manufacturing the separator core.

<Ease of cleaning>
However, a surface having a very large arithmetic average roughness has a problem that it is difficult to clean when a fine foreign matter adheres.

  Actually, in the battery manufacturing process, after the separator 12 is rolled out from the wound body 110, the core 100 can be reused by washing the core 100 and winding a new separator 12. At the time of this cleaning, it is necessary to remove foreign substances adhering to the core 100. This is to prevent the foreign matter remaining in the core 100 from adhering to the separator 12 and becoming defective.

  At this time, if the side surface of the core 100 has an average roughness that is larger than necessary, foreign substances cannot be sufficiently removed in the cleaning process, and the core 100 may not be reused. Even if the foreign matter can be removed, if the cleaning takes a long time, there is a problem that the process for reuse becomes longer.

  As described above, the inventor has found that the side surface of the core 100 is required to have an appropriate surface roughness in order to have both the frictional force between the side surfaces and the ease of cleaning.

  In addition, when the side surface roughness of the core 100 is in the above range, even in the wound body 110 in which the separator 12 is wound around the core 100, the wound bodies 110 are not easily displaced when the wound body 110 is stacked. Is advantageous. In order to express the effect, the separator 12 having a width narrower than the length in the thickness direction of the core 100 having the side roughness in the above range may be wound around the core 100 to form the wound body 110.

  The core 100 may protrude from at least one side surface of the separator 12 wound around the core 100 in the wound body 110. From the viewpoint of preventing damage to the separator 12, the length that the core 100 protrudes from the side surface of the wound separator 12 is preferably 1 mm or more.

<Core measurement experiment>
Based on the above, the inventor conducted an experiment to verify the frictional force and the ease of cleaning with respect to the core 100 having different surface roughness.

  First, a plurality of cores A having the same shape as the core 100 were prepared, and the arithmetic average roughness of the side surfaces was measured. In addition, the structure and physical property of the several core A are substantially the same.

  Specifically, the arithmetic average roughness of each side surface was measured for a plurality of cores A. As the surface roughness measuring device, “Handy Surf E-35A” (manufactured by Tokyo Seimitsu Co., Ltd.) was used. The stylus tip of the measuring head has a 60 ° conical shape. The tip radius of the stylus tip is 2 μm. In the present embodiment, the measurement force of the surface roughness measuring device was set to 0.75 mN, the measurement speed was set to 0.5 mm / s, the evaluation length was set to 4.0 mm, and the cutoff value was set to 0.8 mm. Since it can be considered that the roughness of the side surface of the core 100 exists substantially evenly, the average value of the arithmetic average roughness measured at 10 locations with different side surfaces was defined as the arithmetic average roughness on the side surface of the core.

  Next, an experiment for measuring the frictional force on the side surface of the core A was performed.

First, as shown in FIG. 5 (a), the outer cylinder has an outer diameter of 6 inches, the inner cylindrical member has an inner diameter of 3 inches, a thickness of 65 mm, and eight ribs at positions where the circumference is divided into eight equal parts. On the outer peripheral surface of the outer cylindrical member 101 of the core A having a side area of 41 cm ² and a weight of 0.36 kg, the separator 12 having a width of 60 mm is wound around the central portion of the outer peripheral surface of the core A, A 1.25 kg wound body A was prepared. Next, two wound bodies A that were created were stacked on a horizontal carriage with a non-slip rubber mat so that the cores A overlapped in plan view. After that, the truck was transported 5 m at a constant speed of 30 m / min on a flat road, and then suddenly stopped.

  The largest of the deviations between the wound bodies A caused by the sudden stop was measured, and the frictional force was evaluated. The evaluation was ◯ if the deviation was less than 2 mm, Δ if it was 2 mm or more and less than 5 mm, and x if it was 5 mm or more.

  Finally, an experiment was conducted to verify the ease of cleaning of the side surface of the core A.

  Acetylene black particles were sprinkled on the side surface of the core A, and this was rubbed with a non-woven fabric of pulp to adhere black stains. The black dirt assumes a positive electrode material, a negative electrode material, or the like of a battery having conductivity, which may be actually attached to the core 100 in the battery manufacturing process.

  This was rubbed with a non-woven fabric adhered with ethanol, visually confirmed, and it was repeatedly confirmed whether black stains could be removed.

  The ease of cleaning on the side surface of the core A was evaluated based on the number of times the above cleaning was performed. The evaluation was ○ if the stain could be removed within 3 times, or ○ if it could not be removed within 3 times, but if it could be removed within 5 times, and x if it could not be removed even after 5 times.

<Experimental result>
Similar to the core A, the above experiments were performed on the cores B to G having different surface roughnesses on the side surfaces, and the same evaluation was performed. The cores B to G also have the same shape as the core 100. Table 1 below shows the results of evaluations of experiments performed on the cores A to G, respectively.

  In Table 1, the column of “arithmetic average roughness (μm)” represents the magnitude of the arithmetic average roughness on each side surface measured for the cores A to G. The columns of “friction force” and “easy cleaning” represent the evaluation of the frictional force and the ease of cleaning for the cores A to G, respectively.

<Evaluation of core>
The experimental result of the core A shows that when the arithmetic average roughness of the side surface of the core 100 is 0.15 μm or less, the frictional force on the side surface of the wound body 110 in which the separator 12 is wound around the core 100 is small. . From this, it is suggested that there is a high possibility that the stored wound body 110 is collapsed due to a large displacement of the stacked wound bodies 110.

  Further, the experimental results of the core F and the core G show that when the arithmetic average roughness of the side surface of the core 100 is 1 μm or more, cleaning becomes difficult. This suggests that it is likely to be a cause of failure.

  On the other hand, since the core B and the core E have both frictional force and ease of cleaning to some extent, it is shown that they are suitably employed as the actual core 100. In addition, the core C and the core D have excellent physical properties in both frictional force and ease of cleaning, indicating that they are very suitable for the actual core 100.

<Summary>
Based on the above experimental results, it can be inferred that the wound body 110 is preferably wound around the core 100 having an arithmetic average roughness on the side surface of at least 0.16 μm. If it is the above structure, the winding body 110 which is hard to collapse even if piled up or stored can be realized. At this time, by stacking and storing the wound body 110, it is possible to easily store not only the core 100 but also the wound separator 12 without contacting other objects such as the ground.

  For the same reason, the core 100 preferably has an arithmetic average roughness on the side surface of at least 0.16 μm or more. According to the above configuration, it is possible to realize the core 100 that does not collapse even when the core 100 that is not wound with the separator 12 is stored alone.

  When two cores 100 are stacked and stored, the arithmetic average roughness on the side surface of the core 100 may be within the above-described desirable range for either one surface. At this time, the surfaces having arithmetic average roughness within the above-described desirable range are brought into contact with each other and the cores 100 are stacked, thereby reducing the slippage between the cores 100 and facilitating stacking and storing the two cores 100. Become.

  When both sides of the core 100 are within the above-described desirable range, it is easy to stack and store three or more cores 100. Moreover, since the frictional force with the ground on which the core 100 is installed during storage can be increased and slipping can be prevented, the stacked cores 100 can be more efficiently prevented from collapsing.

  In addition, the core 100 preferably has an arithmetic average roughness on the side surface of at least 0.9 μm or less. According to the said structure, the core 100 which can be wash | cleaned easily can be provided. A wound body 110 formed by winding the separator 12 around the core 100 is preferable in that it can be easily washed after use.

  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.

DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery 2 External apparatus 3 Lithium ion 4 Heat-resistant layer 11 Cathode 12 Separator 12a Heat-resistant separator 13 Anode 100 Core 110 Winding body 120 Base

Claims (10)

A separator core around which a separator for a non-aqueous electrolyte secondary battery is wound,
In the separator core, the arithmetic mean roughness of at least one surface of the side surface that is a surface on which the separator is not wound is 0.16 μm or more.   The separator core according to claim 1, wherein the arithmetic average roughness is 3 μm or less.   The separator core according to claim 2, wherein the arithmetic average roughness is 0.9 μm or less.   The separator core according to any one of claims 1 to 3, wherein at least two of the separator cores can be stacked with the side surface in the vertical direction.   The separator core according to any one of claims 1 to 4, wherein the material includes any of ABS resin, polyethylene resin, polypropylene resin, polystyrene resin, polyester resin, and vinyl chloride resin.   The separator winding body formed by winding the said separator on the separator core of any one of Claim 1 to 5.   The separator wound body according to claim 6, wherein a width of the separator core is larger than a width of the separator. A separator wound body obtained by winding a separator for a non-aqueous electrolyte secondary battery on a separator core,
Separator manufacturing process for manufacturing the separator,
In the separator core, a winding step of winding the separator on the separator core having an arithmetic average roughness of at least one side of the side surface, which is a surface on which the separator is not wound, of 0.16 μm or more. A method for producing a separator roll, comprising:   The method for producing a separator roll according to claim 8, wherein the arithmetic average roughness is 3 µm or less.   The method of manufacturing a separator roll according to claim 9, wherein the arithmetic average roughness is 0.9 µm or less.

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