JP2016171070A - Separator roll, method for producing battery, and method for producing separator roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator roll and the like including a core suited for reuse.SOLUTION: A separator roll (10) includes a core (8) around which a separator (12) that is a porous separator for a battery is wound. The outer circumferential surface (S) of the core (8) has an arithmetic mean roughness of 3.7 μm or more, the outer circumferential surface being in contact with the separator (12).SELECTED DRAWING: Figure 6

Description

  The present invention relates to a separator wound body used for a battery such as a lithium ion battery, a method for producing the separator wound body, and a method for producing the battery.

  Inside the lithium ion secondary battery, the positive electrode and the negative electrode are separated by a porous separator. In the production of a lithium ion secondary battery, a separator wound body is used in which this separator is wound around a cylindrical core.

  Patent Document 1 discloses a wound body in which a microporous film is wound around a core including a conductive member.

JP2013-139340 (released July 18, 2013)

  The core from which the separator is unwound is preferably reusable for winding the separator. Patent Document 1 does not describe the reuse of the core.

  The objective of this invention provides the separator winding body provided with the core suitable for reuse, the manufacturing method of a separator winding body, and the manufacturing method of the battery provided with the separator unwound from the separator winding body There is to do.

  In order to solve the above-described problems, a separator wound body of the present invention includes a core wound with a porous battery separator, and the arithmetic average roughness of the outer peripheral surface of the core in contact with the battery separator is 3 .7 μm or more.

  Moreover, the separator winding body of this invention is equipped with the core which wound the porous battery separator, and the root mean square roughness of the outer peripheral surface which contact | connects the said battery separator of the said core is 4.0 micrometers or more.

  The inventor determines the surface roughness (arithmetic average roughness or root mean square roughness) of the outer peripheral surface of the core and the peel strength which is the magnitude of the force required to peel the adhesive and battery separator from the outer peripheral surface. It was found that when the surface roughness satisfies a specific condition, the peel strength is remarkably reduced.

  According to the said structure, peeling strength can be remarkably small compared with the conventional core. Thereby, since an adhesive agent and a battery separator can be easily peeled from an outer peripheral surface, the core can be reused.

  Moreover, in the separator winding body of this invention, the end which contact | connects the said outer peripheral surface of the said battery separator may be fixed to the said outer peripheral surface.

  According to the above configuration, the battery separator can be prevented from shifting on the outer peripheral surface. In particular, if one end of the battery separator is fixed to the outer peripheral surface before the battery separator is wound around the core, the battery separator is displaced from the fixed position even when the battery separator is wound around the core. Can be suppressed. Therefore, it is possible to provide a separator wound body that can reuse the core and has little winding deviation.

  In the separator wound body of the present invention, the battery separator may include a functional layer facing the outer peripheral surface.

  When the adhesiveness of the functional layer is higher than that of the battery separator other than the functional layer, the functional layer easily adheres to the outer peripheral surface. For this reason, the reuse of the core may be prevented.

  According to the said structure, since a functional layer can be easily peeled from an outer peripheral surface, a core can be reused.

  In the separator wound body of the present invention, the core may contain a resin.

  When the adhesive and the battery separator are peeled from the outer peripheral surface, a force is applied to the portion on the outer peripheral surface side of the core in the direction of peeling from the core.

  According to the said structure, the outer peripheral surface side of a core becomes difficult to peel compared with a paper core, for example.

  The battery of the present invention includes a cathode and an anode, and the battery separator unwound from the above-described separator winding body disposed so as to be sandwiched between the cathode and the anode.

  The method for producing a battery of the present invention includes a step of unwinding the battery separator from the separator rolled body and a step of disposing the unwound battery separator so as to be sandwiched between a cathode and an anode. Including.

  According to the said structure, since the core of a separator winding body can be reused, the separator winding body and the battery separator unwound from the separator winding body can be provided at low cost. For this reason, a battery can be provided cheaply compared with the conventional battery.

  The method of manufacturing a separator roll according to the present invention includes a step of transporting a porous battery separator, and the transported battery separator as a core having an arithmetic mean roughness of an outer peripheral surface of 3.7 μm or more. A winding step.

  Further, the method for producing a separator wound body according to the present invention includes a step of transporting a porous battery separator, and the battery separator being transported, wherein the root mean square roughness of the outer peripheral surface is 4.0 μm or more. And winding it around a core.

  According to the said manufacturing method, the separator winding body which can reuse a core can be manufactured.

  According to the separator winding body of the present invention, since the adhesive and the battery separator can be easily peeled off from the outer peripheral surface of the core, the core can be reused.

  In addition, the battery of the present invention has an effect that it can be provided at a lower cost than conventional batteries.

  Moreover, according to the separator winding body manufacturing method of the present invention, it is possible to manufacture a separator winding body that can reuse the core.

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 a schematic diagram which shows the structure of the slit apparatus which slits a separator. It is a side view and a front view which show the structure of the cutting device of the slit apparatus shown by FIG. It is a schematic diagram which shows the structure of the separator winding body of embodiment of this invention. It is a schematic diagram which shows the structure for measuring the surface roughness of the outer peripheral surface of the core shown by FIG. FIG. 7 is a schematic diagram illustrating a configuration for measuring a tensile force applied to the adhesive tape when the adhesive tape attached to the outer peripheral surface of the core illustrated in FIG. 6 is peeled off, and a graph illustrating the measurement result.

[Basic configuration]
A lithium ion secondary battery, a separator, a heat-resistant separator, a heat-resistant separator manufacturing method, a slit device, and a cutting device will be described in this order.

(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 (battery).

  As shown in FIG. 1, the lithium ion secondary battery 1 includes a cathode 11, a separator 12 (battery separator), 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 the detailed configuration of the lithium ion secondary battery 1 shown in FIG. (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.

(Heat-resistant separator)
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 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.

(Manufacturing process of heat-resistant separator)
The production of 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 5 mainly contains polyethylene as the material is assumed and demonstrated. However, even when the porous film 5 contains other materials, the separator 12 can be manufactured by the same manufacturing process.

  For example, a method of adding a plasticizer to a thermoplastic resin to form a film and then removing the plasticizer with a suitable solvent can be mentioned. For example, when the porous film 5 is formed from a polyethylene resin containing ultrahigh molecular weight polyethylene, it can be produced by the following method.

  This method includes (1) a kneading step of kneading ultrahigh molecular weight polyethylene and an inorganic filler such as calcium carbonate to obtain a polyethylene resin composition, and (2) a rolling step of forming a film using the polyethylene resin composition. (3) Removal step of removing the inorganic filler from the film obtained in the step (2), and (4) Stretching step of obtaining the porous film 5 by stretching the film obtained in the step (3). including.

  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 which is a polyethylene microporous film having a predetermined thickness and air permeability is formed.

  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 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 5 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.

  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 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 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. Moreover, you may manufacture the adhesive separator which has another functional layer (for example, below-mentioned adhesive layer) instead of a heat resistant layer with the manufacturing method similar to a heat resistant separator.

(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 a direction substantially perpendicular to the longitudinal direction and the thickness 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 that is substantially perpendicular to the longitudinal direction (MD) and the thickness direction 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. . The slit device 6 is further provided with a cutting device 7 to be described later.

(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.

(After slitting)
As shown in FIG. 4B, a part of the plurality of slit separators is wound around each cylindrical core u (bobbin) fitted to the winding roller 70U. Further, the other part of the plurality of slit separators is wound around each cylindrical core l (bobbin) fitted to the winding roller 70L. A separator wound up in a roll shape is referred to as a “separator wound body”.

(Cutting device)
FIG. 5 is a diagram illustrating a configuration of the cutting device 7 of the slit device 6 illustrated in FIG. 4A, where FIG. 5A is a side view of the cutting device 7, and FIG. It is a front view.

  As shown in FIGS. 5A and 5B, the cutting device 7 includes a holder 71 and a blade 72. The holder 71 is fixed to a housing or the like provided in the slit device 6. The holder 71 holds the blade 72 so that the positional relationship between the blade 72 and the conveyed separator raw material is fixed. The blade 72 slits the raw material of the separator with a sharp edge.

Embodiment
≪Separator winding body configuration≫
6A and 6B are schematic views showing the configuration of the separator wound body 10 according to the embodiment of the present invention, in which FIG. 6A shows a state before the separator 12 is unwound from the core 8, and FIG. (C) shows the state of the core 8 after the separator 12 has been unwound and removed, and (d) shows the state of (b) from a different angle.

  As shown in FIG. 6A, the separator wound body 10 includes a core 8 around which the separator 12 is wound. The separator 12 is slit as described above.

(core)
The core 8 includes an outer cylindrical portion 81, an inner cylindrical portion 82, and a plurality of ribs 83, and has the same function as the above-described core u · l.

  The outer cylindrical portion 81 is a cylindrical member for winding the separator 12 around its outer peripheral surface. The inner cylindrical portion 82 is a cylindrical member for fitting a winding roller on the inner peripheral surface thereof. The rib 83 is a support member that extends between the inner peripheral surface of the outer cylindrical portion 81 and the outer peripheral surface of the inner cylindrical portion 82 and supports the outer cylindrical portion 81 from the inner peripheral surface.

  The material of the core 8 includes ABS resin. However, the material of the core of the present invention is not limited to this. In addition to the ABS resin, the core material may include a resin such as a polyethylene resin, a polypropylene resin, a polystyrene resin, and a vinyl chloride resin. The core material is preferably not metal, paper, or fluororesin.

(Separator)
As shown in FIG. 6B, the outer surface of the separator 12 is provided with a tape 120 that is a mark representing the end of the product. Usually, such a tape is often applied as a mark, but a seal, a stamp, or a printed mark may be applied. The surface to which the tape 120 is applied is not limited to the outer surface of the separator 12 and may be the inner surface of the separator 12.

  The separator 12 is divided into an inner peripheral part 121 closer to the core 8 than the tape 120 and an outer peripheral part 122 farther from the core 8 than the tape 120. One end of the separator 12 is attached to the core 8 with an adhesive tape 130. Specifically, one end of the separator 12 is fixed to the outer peripheral surface S of the core 8 by an adhesive tape 130 provided with an adhesive. The means for fixing one end of the separator to the outer peripheral surface S may be applied by directly applying an adhesive to one end of the separator 12 in addition to the adhesive tape 130, or may be fixed by a clip.

  Unevenness on the outer peripheral surface of the core 8 is transferred to the separator 12. The unevenness is more easily transferred to the inner peripheral portion 121 than to the outer peripheral portion 122. For this reason, when the separator 12 is used as a battery component, the outer peripheral portion 122 divided by the tape 120 is used.

  The length of the inner peripheral part 121 is 3 m. The length of the inner peripheral part of the separator of the present invention is not limited to this length.

  The inventor is required to peel the surface roughness (for example, arithmetic average roughness Ra and root mean square roughness Rq) of the outer peripheral surface S of the core 8 and the adhesive (adhesive tape 130) and the separator 12 from the outer peripheral surface S. It was found that the core 8 can be easily reused because the peel strength is remarkably reduced when the surface roughness satisfies a specific condition when the peel strength, which is the magnitude of the force, is correlated. The surface roughness and peel strength will be described in order.

(Core surface roughness)
FIG. 7 is a schematic diagram showing a configuration for measuring the surface roughness of the outer peripheral surface S of the core 8 shown in FIG. 6C, where FIG. 7A shows the overall configuration, and FIG. A peripheral configuration of the measurement head 21 is shown. As shown in FIGS. 7A to 7B, the surface roughness of the outer peripheral surface S of the core 8 is measured by the surface roughness measuring device 20. As shown in (a) of FIG. 7, the core 8 is fixed to the pedestal 30 via a ring stopper 31.

  The surface roughness measuring device 20 includes a measuring head 21, a moving mechanism 22, a housing 23, and a cable 24, and is fixed to the pedestal 30 via a fixing member 32.

  The tip of the measurement head 21 is in contact with the outer peripheral surface S. The moving mechanism 22 moves the measuring head 21 in the direction D that is the width direction of the core 8. The housing 23 includes a module that receives a signal corresponding to the surface roughness of the outer peripheral surface S from the measurement head 21 and calculates the surface roughness. The cable 24 relays the calculation result / power of the surface roughness between the surface roughness measuring device 20 and the external device.

(Specifications of core surface roughness measuring device)
As the surface roughness measuring device 20, “Surftest (SJ-400)” manufactured by Mitutoyo was used. The tip of the stylus of the measuring head 21 has a 60 ° cone shape. The tip radius of the stylus tip is 2 μm. In this embodiment, the measurement force of the surface roughness measuring device 20 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.

(Separator peel strength)
The separator 12 is unwound from the separator wound body 10 shown in FIG. 6 (a) as shown in FIG. 6 (b), and the outer peripheral surface S of the core 8 is shown as shown in FIG. 6 (c). When the separator 12 is peeled off, a tensile force is applied to the separator 12. The magnitude of this tensile force means the peel strength of the separator 12 that is the magnitude of the force required to peel the separator 12 from the outer peripheral surface S.

(Peel strength of adhesive tape)
As shown in FIG. 6D, the adhesive tape 130 has one end of the separator 12 on the inner peripheral portion 121 side attached to the core 8. Then, the separator 12 is unwound from the separator wound body 10 shown in FIG. 6A as shown in FIG. 6B, and the outer periphery of the core 8 is shown as shown in FIG. 6C. When the adhesive tape 130 is peeled from the surface S, the adhesive tape 130 has a tensile force (usually the adhesive tape 130 peeled off from the outer peripheral surface S and the contact at the site where the adhesive tape 130 on the outer peripheral surface S is about to be peeled off. A force for peeling the adhesive tape 130 from the outer peripheral surface S is applied in a state where the peeling angle, which is an angle formed by the flat surface, is 90 ° or more. The magnitude of this tensile force means the peel strength of the adhesive tape 130 that is the magnitude of the force required to peel the adhesive tape 130 from the outer peripheral surface S.

  The adhesive force between the adhesive tape 130 and the outer peripheral surface S is proportional to the adhesive area where the adhesive tape 130 is attached to the outer peripheral surface S. When the peel angle is close to 0 °, the above-described tensile force is proportional to the adhesion area. On the other hand, when the peel angle is close to 90 °, the tensile force is proportional to the width of the adhesive tape 130.

(Quantification of peel strength)
Below, the above-mentioned peel strength is quantified as the force required to peel the adhesive tape from the core 8.

  FIG. 8 shows a configuration for measuring the tensile force applied to the adhesive tape 12a when the adhesive tape 12a attached in the circumferential direction of the outer peripheral surface S of the core 8 shown in FIG. And (a) to (c) are schematic views showing the situation when the adhesive tape 12a is peeled from the core 8, and (d) is the relationship between the distance and the tensile force. (E) is a graph showing the relationship between the arithmetic average roughness Ra and the standardized peel strength NF, and (f) is a schematic diagram showing the situation when measuring the average value of the tensile force. FIG.

  The adhesive tape 12a is “Scotch (Cat. No. 500-3-1235-10P, 12 mm width)” manufactured by 3M. The tester used for measuring the tensile force is a Tensilon universal material tester (Orientec Co., Ltd., model RTG-1310). The peel strength test was performed three times on each sample, and the average value of the test results was defined as the peel strength.

  As shown in FIGS. 8A to 8C, when the adhesive tape 12a is applied to the outer peripheral surface S and the adhesive tape 12a is peeled off from the outer peripheral surface S, the tensile force applied to the adhesive tape 12a is measured. Thus, the peel strength can be quantified. Specifically, it is as follows.

  As shown in FIG. 8A, the adhesive tape 12a is affixed to the outer peripheral surface S. In addition, the outer peripheral surface S of the core 8 is wiped off the dirt, oil, and the like attached thereto using ethanol in advance. As described above, the adhesive tape 12 a has a width of 12 mm and is attached to a length of 3/8 of the circumferential direction of the core 8. From this state, a tensile force is applied to the end portion p of the adhesive tape 12a in a direction substantially perpendicular to the outer peripheral surface S.

  The distance on the horizontal axis shown in FIG. 8D is the distance (mm) where the adhesive tape 12a peeled off from the outer peripheral surface S of the core 8 is pulled up. At this time, the adhesive tape 12a is pulled up at a speed of 100 mm / min. When the tensile force increases from 0 and exceeds a certain value, the adhesive tape 12a is peeled off from the outer peripheral surface S. The tensile force Fa is a tensile force immediately after the adhesive tape 12a starts to peel from the outer peripheral surface S.

  As shown in FIG. 8B, the adhesive tape 12a is further peeled off from the outer peripheral surface S from the situation shown in FIG. The tensile force Fb is the end of the adhesive tape 12a when the direction in which the portion peeled from the outer peripheral surface S of the adhesive tape 12a extends and the direction perpendicular to the outer peripheral surface S coincide (so-called 90 ° peeling). This is the tensile force applied to p. At this time, the distance or time at which the adhesive tape 12a is pulled up to the time when the angle between the peeled portion of the adhesive tape 12a and the outer peripheral surface S reaches 90 ° is recorded. Here, the average tensile force in a certain range including when the peel angle is 90 ° is specified as the tensile force Fb as follows. At this time, the core 8 is fixed so as not to move or rotate.

  Specifically, in the situation shown in FIG. 8 (a), the position qa representing the boundary between the part where the adhesive tape 12a is peeled off from the outer peripheral surface S and the part where the adhesive tape 12a is not peeled is shown in FIG. 8 (b). In the situation where the position is moved to the position qb.

  In this process, as shown in FIG. 8 (f), a line segment connecting a point representing the position qa and a point passing through the rotation axis CA of the core 8 and a point representing the position qb and the rotation axis CA of the core 8 are used. The angle θ formed by the line connecting the points passing through changes from an angle exceeding 30 ° to 0 °. The average value of the tensile force during the period in which the angle θ changes from 30 ° to 0 ° (including 0 °) is defined as a tensile force Fb.

  In the situation shown in (b) of Drawing 8, the length of adhesive tape 12a is 60 cm or more. For example, when the outer diameter of the core 8 is 6 inches (152 mm), when the angle θ changes from 30 ° to 0 °, the length of the portion peeled from the outer peripheral surface S of the adhesive tape 12a is 40 mm. is there. The average speed when the position qa moves to the position qb along the outer peripheral surface S is, for example, 100 mm / min. Further, the elapsed time at this time is, for example, 24 seconds.

  As shown in FIG. 8C, the adhesive tape 12a is further peeled off from the outer peripheral surface S from the situation shown in FIG. The tensile force Fc is a tensile force before the end q of the adhesive tape 12a is completely peeled off from the outer peripheral surface S.

  As shown in FIG. 8D, the tensile force changes in the order of the tensile forces Fa, Fb, and Fc. This change reflects the state of the outer peripheral surface S. And it means that it is difficult to peel the adhesive tape 12a from the outer peripheral surface S, so that this tensile force is large. Similarly, the greater the tensile force, the more difficult it is to peel the separator 12 from the outer peripheral surface S.

  (Relationship between surface roughness and peel strength)

  Table 1 shows the relationship between the arithmetic average roughness Ra, the root mean square roughness Rq, the peel strength F, and the normalized peel strength NF measured for various cores.

  The arithmetic average roughness Ra and the root mean square roughness Rq shown in Table 1 are measured by the surface roughness measuring device 20. Peel strength F is an average value of tensile force Fb measured for the cores of Comparative Examples 1 and 2 and Examples 1 to 3 having various surface roughness by the configuration shown in (a) to (c) of FIG. (Average value measured three times). The standardized peel strength NF means the tensile force Fb per unit width (m) in the transverse direction of the adhesive tape 12a.

  As shown in FIG. 8E, the standardized peel strength NF tends to be remarkably small in the vicinity of the value of the arithmetic average roughness Ra of Example 1.

  (Transfer of irregularities from the core to the separator)

  Table 2 shows the results of measuring the unevenness transferred from the core to the separator after winding the various separators around the various cores as the surface roughness of the separator.

  As the separator, a laminated separator produced by the following method was used.

(Manufacture of separators with functional layers)
<Manufacture of polyolefin porous film>
70% by weight of high molecular weight polyethylene powder (GUR4032 (manufactured by Ticona Corporation)), 30% by weight of polyethylene wax having a weight average molecular weight of 1000 (FNP-0115 (manufactured by Nippon Seiki Co., Ltd.)), 0.4 parts by weight of antioxidant (Irg1010 (manufactured by Ciba Specialty Chemicals)), 0.1 part by weight of antioxidant (P168 (manufactured by Ciba Specialty Chemicals)) with respect to 100 parts by weight in total Parts, 1.3 parts by weight of sodium stearate, and calcium carbonate (manufactured by Maruo Calcium Co., Ltd.) having an average particle size of 0.1 μm so as to be 38% by volume with respect to the total volume, and these are powder Polyolefin resin after mixing with a Henschel mixer and melt-kneading with a twin screw kneader It was formed products. The polyolefin resin composition was rolled with a pair of rolls having a surface temperature of 150 ° C. to produce a sheet. This sheet was immersed in an aqueous hydrochloric acid solution (hydrochloric acid 4 mol / L, nonionic surfactant 0.5% by weight) to remove calcium carbonate, and subsequently stretched at 105 ° C. at an arbitrary magnification to obtain a film thickness of 13 A polyolefin porous film of 5 μm was obtained.

<Manufacture of slurry for functional layer formation>
The manufacturing conditions of para-aramid for obtaining a functional layer having heat resistance are as follows.

  Para-aramid (poly (paraphenylene terephthalamide)) was produced using a 3 liter separable flask having a stirring blade, a thermometer, a nitrogen inlet tube and a powder addition port. To the well-dried flask, 2200 g of N-methyl-2-pyrrolidone (NMP) was charged, and then 151.07 g of calcium chloride powder vacuum-dried at 200 ° C. for 2 hours was added. This was heated to 100 ° C. to completely dissolve calcium chloride in NMP. The calcium chloride solution was returned to room temperature, and 68.23 g of paraphenylenediamine was added and completely dissolved. While maintaining this solution at 20 ° C. ± 2 ° C., 124.97 g of terephthalic acid dichloride was added in 10 divided portions every about 5 minutes. Thereafter, with stirring, the solution was aged for 1 hour while being kept at 20 ° C. ± 2 ° C. to obtain a para-aramid solution having a para-aramid concentration of 6% by weight.

To 100 g of the obtained para-aramid solution, 243 g of NMP was added and stirred for 60 minutes to obtain a para-aramid solution having a para-aramid concentration of 1.75% by weight. On the other hand, alumina powder (alumina C (made by Nippon Aerosil Co., Ltd.), true specific gravity: 3.2 g / cm ³ ) and alumina powder (advanced alumina AA-03 (made by Sumitomo Chemical Co., Ltd.), true specific gravity: 4.0 g / Cm ³ ) 6 g was mixed to obtain 12 g of an alumina powder mixture. Then, 12 g of the alumina powder mixture is mixed with the para-aramid solution having a para-aramid concentration of 1.75% by weight and stirred for 240 minutes to obtain an alumina powder-containing para-aramid solution. Filtered through a wire mesh. Thereafter, 0.73 g of calcium oxide was added to the filtrate, and the mixture was neutralized by stirring for 240 minutes, and defoamed under reduced pressure to obtain a slurry.

<Manufacture of laminated separator>
A polyolefin porous film (width 300 mm, length 300 m) was attached to an unwinder, and the slurry was applied to one side of the polyolefin porous film drawn out from the polyolefin porous film with a bar coater to obtain a coating film. Next, the coated film was passed through a constant temperature and humidity chamber (temperature: 50 ° C., relative humidity: 70%) to deposit para-aramid from the coated film. Subsequently, the film was passed through a water washing apparatus to remove NMP and calcium chloride from the film.

  Thereafter, moisture was dried and removed through a hot roll while hot air was sent to the washed film with a dryer. As a result, a laminated separator having a thickness of 17 μm obtained by laminating a heat-resistant layer (functional layer) on one side of the polyolefin porous film was obtained.

  The obtained laminated separator was slit to a width of 60 mm, and wound around the core with the heat-resistant layer inside (core side) to prepare a wound body. The winding tension was 1900 gram. After storing the wound body at room temperature for 2 weeks, the surface roughness on the polyolefin side (outside) of the innermost (first) to sixth-round film unwound from the wound body is orthogonal to the circumferential direction. Measured in the direction.

(Measurement equipment specifications)
The surface roughness of the film shown in Table 2 was measured with a non-contact surface shape measurement system (Ryoka System Co., Ltd. VertScan (registered trademark) 2.0 R5500 GML). The measurement conditions are as follows.
Objective lens: 5x (Michelson type)
Intermediate lens: 1x wavelength filter: 530nm
CCD camera: 1/3 inch measurement mode: Wave
Image field: 700 μm (direction perpendicular to the circumferential direction) × 940 μm (circumferential direction)
Number of connected images: 5 in the direction orthogonal to the circumferential direction Data horizontal correction: 4th cut-off: None (Core specification)
The diameter of the core used in Comparative Example 2a and Examples 1a to 3a is 152 mm, the width is 65 mm, and the material thereof is ABS.

(Summary of uneven transfer)
In Table 2, “Criteria” is the surface roughness of the separator before being wound around the core.

  The numerical value in the “first round” column means the surface roughness of the separator measured at a position from the outer peripheral surface of the core to one round of the separator wound around the core. In addition, the numerical value of this column is a value of the surface roughness measured at the position of the separator after being unwound from the wound body.

  The numerical values in the "2nd to 6th lap" columns are the separators measured at the positions of the 2nd to 6th laps corresponding to the positions measured at the 1st lap among the separators wound around the core. It means that the surface roughness is. That is, each measured value is a value measured with an interval of one round. Among the separators wound around the core, the position of six rounds from the outer peripheral surface of the core is approximately 2 in the direction from one end of the separator attached with the adhesive tape to the other end when the separator starts to be wound around the core. .5m away.

  As shown in Table 2, regarding the surface roughness of the separator of Comparative Example 2a, the value of “first round” is larger than the value of “reference”, but is about the same as the value of “reference”.

  As for the surface roughness of the separators of Examples 1a and 2a, the value of “1st round” is larger than the value of “reference”, but the value of “6th round” is the same as the value of “reference”. Further, regarding the surface roughness of the separator of Example 3a, although the value of “1st round” is larger than the value of “reference”, the value of “12th round” is almost the same as the value of “reference”.

  As described above, even when the separator is wound around the cores of Examples 1a and 2a having a surface roughness higher than that of the core of Comparative Example 2a, the separator is located around the sixth lap (2.5 m) from the outer peripheral surface of the core. There are no irregularities transferred from the core. Further, even when the separator is wound around the core of Example 3a having a larger surface roughness, the separator located near the 12th lap (about 5 m) from the outer peripheral surface of the core leads to the surface roughness of the separator due to the unevenness of the core. The effect of is getting smaller. As in Example 3a, if the surface roughness Ra or Rq of the core is large, the standardized peel strength NF can be further reduced. However, considering the influence of the unevenness of the core being transferred to the separator, the surface roughness Ra of the core is preferably less than 13.1 or Rq is less than 15.7.

  (Surface roughness and functional layer adhesion)

  Table 3 shows the surface roughness (arithmetic mean roughness Ra and root mean square roughness Rq) measured for the various cores shown in Table 2, and the outer surface of the core after removing the separator wound around the core. It shows the adhesion amount of the functional layer in.

  In Examples 1a, 2a and 3a, the adhesion amount of the functional layer was small, but in Comparative Example 2a, this adhesion amount was large.

<< Effects of this embodiment >>
It is considered that the larger the standardized peel strength NF is, the stronger the force with which the separator functional layer adheres to the core. Therefore, it is considered that in the core of Comparative Example 2a having a large standardized peel strength NF, that is, having a small surface roughness Ra, Rq, the functional layer is peeled off from the separator and remains attached to the core. On the other hand, in the cores of Examples 1a to 3a where the standardized peel strength NF is small, that is, the core surface roughness Ra, Rq is large, the adhesion force of the functional layer to the core is small. Therefore, in the cores of Examples 1a to 3a, almost no functional layer remains on the core (without peeling from the separator), and the separator including the functional layer can be easily peeled from the core.

  As shown in Table 1, in the separator wound body including the core having the arithmetic average roughness Ra of the specific outer peripheral surface, the peel strength can be significantly reduced as compared with the conventional separator wound body. At this time, the adhesive and the battery separator can be easily peeled off from the outer peripheral surface of the core, and the core can be reused.

  Moreover, as shown in Table 1, in the separator wound body including the core having the root mean square roughness Rq of the specific outer peripheral surface, the peel strength can be significantly reduced as compared with the conventional separator wound body. Also at this time, the adhesive and the battery separator can be easily peeled off from the outer peripheral surface of the core, and the core can be reused.

(Manufacturing method of separator roll)
Further, as shown in FIG. 4A, a method of manufacturing the separator wound body 10 including a step of transporting the separator 12 and a step of winding the separator 12 being transported around the core is also provided. Included in the invention.

  By the above, the separator winding body which can reuse a core can be manufactured.

(Lithium ion battery)
Further, as shown in FIGS. 1 and 2 (a) to (c) or FIGS. 3 (a) to (b), the cathode 11 and the anode 13 are sandwiched between the cathode 11 and the anode 13. The lithium ion secondary battery 1 provided with the separator 12 unwound from the separator winding body 10 provided with the above-described core is also included in the present invention.

  A method for manufacturing a battery (for example, a lithium ion secondary battery 1) according to one embodiment of the present invention includes a step of preparing the cathode 11 and the anode 13, a step of unwinding the separator 12 from the separator winding body 10, Disposing the separator 12 unwound so that the separator 12 is sandwiched between the anodes 13. Thereafter, the stacked cathode 11, anode 13, and separator 12 are cut to a size corresponding to the battery.

  Thereby, since the core 8 of the separator winding body 10 can be reused, the separator winding body 10 and the separator 12 unwound from the separator winding body 10 can be provided at low cost. For this reason, the lithium ion secondary battery 1 can be provided at a low cost as compared with the conventional battery.

(Separator roll with separator with functional layer)
As shown in FIGS. 3A to 3B, the separator 12 is a heat-resistant separator provided with the heat-resistant layer 4, and the heat-resistant layer 4 faces the outer peripheral surface S of the core 8. The body 10 is also included in the present invention.

  Furthermore, the separator winding body in which the separator 12 is an adhesive separator provided with an adhesive layer and the adhesive layer faces the outer peripheral surface S of the core 8 is also included in the present invention. Examples of the adhesive layer include a layer formed by applying a coating liquid of an adhesive resin such as polyvinylidene fluoride to the porous film 5.

  Since the heat-resistant layer 4 and the adhesive layer have higher adhesiveness than the porous film 5, they easily adhere to the outer peripheral surface S of the core 8. Therefore, in a separator having a functional layer such as the heat-resistant layer 4 or an adhesive layer, the reuse of the core may be hindered by the adhesion of the functional layer to the core. According to the present invention, adhesion of the functional layer to the core can be suppressed.

(Fix one end of the separator)
As shown in FIGS. 6B and 6D, one end of the separator 12 in contact with the outer peripheral surface S is fixed to the outer peripheral surface S.

  Thereby, it can suppress that the separator 12 slip | deviates on the outer peripheral surface S. FIG. In particular, if one end of the separator 12 is fixed to the outer peripheral surface S before the separator 12 is wound around the core 8, the separator 12 is prevented from being displaced from the fixed position even when the separator 12 is wound around the core 8. it can. Therefore, it is possible to provide the separator wound body 10 in which the core 8 can be reused and the winding deviation is small.

[Additional Notes]
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.

  The present invention relates to a film roll obtained by winding a general film other than a battery separator around a core, a method for producing the film roll, and a general application product using a film other than a lithium ion secondary battery. Can also be used.

1 Lithium ion secondary battery (battery)
4 Heat-resistant layer (functional layer)
5 Porous film 8 · u · l Core 10 Separator roll 11 Cathode 12 Separator (Battery separator)
13 Anode S Outer peripheral surface

Claims (8)

It has a core wrapped with a porous battery separator,
An arithmetic mean roughness of an outer peripheral surface of the core in contact with the battery separator is 3.7 μm or more. It has a core wrapped with a porous battery separator,
The separator roll, wherein the root mean square roughness of the outer peripheral surface of the core in contact with the battery separator is 4.0 μm or more.   The separator winding body according to claim 1 or 2, wherein one end of the battery separator in contact with the outer peripheral surface is fixed to the outer peripheral surface.   4. The separator wound body according to claim 1, wherein the battery separator includes a functional layer facing the outer peripheral surface. 5.   The separator winding body according to any one of claims 1 to 4, wherein the core includes a resin. Unwinding the battery separator from the separator roll according to any one of claims 1 to 5,
And disposing the unwound battery separator so as to be sandwiched between a cathode and an anode. A step of conveying a porous battery separator;
Winding the battery separator being conveyed around a core having an arithmetic average roughness of the outer peripheral surface of 3.7 μm or more;
The separator winding body characterized by including this. A step of conveying a porous battery separator;
Winding the battery separator being conveyed around a core having a root mean square roughness of 4.0 μm or more on the outer peripheral surface;
The separator winding body characterized by including this.

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