JP2003073036A - Core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core having low frictional coefficient so that the sliding property in pulling out the core after a sheet material is taken up is improved and the sheet material is prevented from being scratched, and further having superior abrasion resistance, so that it can be continuously manufactured for a long time. SOLUTION: In this core for taking up the sheet material, the surface roughness (ten point average roughness) Rz of the core surface is 0.4-5 μm, and a load length ratio tp in 40% cutting level is 20-95%. Preferably, the core surface is coated with ceramics.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a winding core for winding a sheet-shaped material. In particular, the core of the present invention is preferably used as a core for a battery used during battery production.

[0002]

2. Description of the Related Art Cylindrical batteries such as lithium secondary batteries are
In general, the electrode and the separator are alternately sandwiched and wound around a winding core and wound, and then the winding core is extracted from the wound electrode element to produce a spiral electrode body, which is placed in a battery can. Manufactured by inserting.

However, when the winding core is removed from the electrode body after the winding, there are defects such as a pin (winding core) pull-out defect and a center pin (winding core) insertion defect at the time of molding.
This has been a major factor in the decrease in battery yield. Therefore, in order to improve the pin disengagement, a winding pin (core)
As a substitute for the conventional iron-made core, the one whose surface of the core is chrome-plated and mirror-finished is used.
It is still not sufficient, and the slipperiness when the core is removed is not good, so that when the core is removed, the shape of the electrode element may be in the form of bamboo shoot or may not come off. These causes are poor slippage between the separator and the core after winding, that is, since the separator is relatively strongly wound around the core, the friction coefficient between the separator and the core when the core is removed after winding It is considered to be caused by this.

Therefore, some attempts have been made to reduce the coefficient of friction. For example, a method of applying a silicone release agent to the surface of the core has been proposed, but in the case of this method, it is necessary to apply the silicon release agent to the core every time the electrode body is wound up, The manufacturing process is complicated and the production efficiency is poor. Further, in Japanese Patent Laid-Open No. 6-251774,
A method has been proposed in which carbon is mixed with an epoxy resin or the like and applied to the surface of the core body of the winding core to reduce the coefficient of friction, instead of the chrome-plated mirror surface treatment of the surface of the winding core. However, when forming the electrode element, the electrode element is wound by applying a relatively large tension, and therefore, the above-mentioned Japanese Patent Laid-Open No.
In the case of Japanese Patent No. 251774, there is a problem in the durability of the core, the frequency of replacement of the core is high, it is difficult to carry out continuous production for a long time, and there is a problem in terms of production efficiency. In addition, the pin removal property was not yet sufficient. Therefore, as a further improved core surface,
A self-lubricating chrome-plated core has been proposed as a core having a combination of the abrasion resistance of chrome plating and the low friction coefficient of tetrafluororesin.

[0005]

However, the self-lubricating chrome-plated core has a relatively low coefficient of friction, but is still insufficient in terms of durability, and has a further excellent characteristic. Is desired.

[0006]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have set the surface roughness Rz of the winding core within a specific range, and further, the load length at the cutting level of the winding core surface. The inventors have found that a core having a low coefficient of friction and excellent durability can be obtained by setting the rate tp within a specific range, and the present invention has been completed. That is, the present invention relates to a winding core for winding a sheet-shaped material, wherein the surface roughness Rz of the surface of the winding core is 0.4 to 5 μm, and the cutting level is 4.
The present invention relates to a winding core characterized in that tp at 0% is 20 to 95%.

In the present invention, it is preferable that the surface of the core is a ceramic-coated core. INDUSTRIAL APPLICABILITY The core of the present invention can be suitably used as a core when manufacturing an electrode body of a lithium secondary battery in which a relatively flexible film is used as a sheet material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the surface roughness (ten-point average roughness) of the main surface portion of the core film contacting the film
When Rz is excessively small, frictional resistance increases,
When pulling out the core, it is easy for pin failure to occur.
If z is excessively large, film damage is likely to occur. Therefore, the surface roughness (ten-point average roughness) Rz is preferably 0.4 to 5 μm, and particularly preferably 1 to 3.5 μm. Further, when the load length ratio tp at the cutting level of 40% is excessively small, the film used is so soft that the frictional resistance becomes large, and pin pull-out failure is likely to occur when the core is removed. Therefore, it is preferable that the load length ratio tp is large. However, when the surface roughness (ten-point average roughness) Rz is in the above range, it is difficult to make it excessively large in manufacturing, and it is usually tp. Is about 85% at maximum.
Therefore, the load length ratio tp at the cutting level of 40% is 25.
It is good to be set to ~ 85%. In particular, in the present invention, a core having a ceramic coating formed on the surface of the core has a low coefficient of friction and is excellent in durability, which is preferable.

In the present invention, the ceramic coating is magnetron sputter-ion plating method (SIP method).
Is formed by. As the ceramic coating, Ti, A
Carbides such as 1 and Cr, nitrides, oxynitrides, and the like. Specifically, TiC, TiN, TiCN, TiAlN, T
Examples thereof include iAlNO, TiAlNC, CrN, TiCrN and the like. The ceramic coating is preferably formed using a magnetron sputter ion plating SIP processor Z700 (manufactured by Leibold, Germany). An example of the ceramic coating method is shown below. Body (core body)
Glass particles # 120 to # 200 and Al ₂ O ₃ # 8 in advance.
After sandblasting with 0 to # 220, sandpaper # 400 is lightly polished to remove sharp protrusions. A ceramic coating of TiN or the like is formed to a thickness of about 2 μm on the object using a magnetron sputter ion plating SIP processor Z700. The surface of the ceramic coating-formed body is lightly polished with a nylon scrubbing tool containing an abrasive to remove sharp protrusions, and a ceramic-coated core is manufactured.

In the present invention, the surface roughness (10-point average roughness) Rz was determined by the method described in JIS B0601. Also, the load length rate tp at the cutting level of 40% is J
It was determined by the method described in ISB0601. The method for measuring the surface roughness is shown below. (1) The measurement was based on JIS B0601 Surface Roughness-Definition and Display, and JIS B0651 Stylus Surface Roughness Measuring Instrument. Measuring instrument: Surface roughness meter (Model: SE-2, made by Kosaka Laboratory)
300, diamond stylus tip R 5 μm, contact pressure 4 mN) Measurement was performed in a direction perpendicular to the ground surface. (2) How to determine Rz Rz is the standard length from the roughness curve in the direction of the average line, and is the height of the fifth to the highest peak measured from the average line of this extracted portion in the longitudinal magnification direction. Calculate the sum of the average absolute value and the average absolute value of the elevations (depths) of the valleys from the lowest valley to the fifth valley, and calculate this value in μm.
Expressed as (3) How to obtain tp tp is a cutting length obtained when a reference length is extracted from the roughness curve in the direction of the average line and the roughness curve of this extracted portion is cut at a cutting level parallel to the crest line. The ratio of the sum of to the standard length was expressed as a percentage. Standard length is 0.25
mm, cutting level was 40%, and tp at that time was used as an evaluation item.

The friction coefficient was measured by a method in accordance with JIS K7125, which is a friction coefficient test method for plastic films and sheets. FIG. 1 shows a schematic diagram of the friction coefficient measurement. The method of measuring the friction coefficient is shown below. (1) Measuring device: Slip tester (Nigaku Rigaku N
o. 3780) (2) Assuming a winding core at the time of winding, the conventional load (200
g), the load (39.69 cm ² ) higher than the area (39.69 cm ² ).
0 g) and a small area (1.76 cm ² ). (3) Film test piece is 23 ± 2 ° C, relative humidity 65 ± 5
Condition for 24 hours in an atmosphere adjusted to%. (4) A film test piece is attached to the surface of the sliding piece (15 mm cylinder) with cellophane tape. (5) Fix the roughened test plate on the test table of the measuring instrument with tape. (6) A slide piece is placed on the surface-roughened test plate, and the hook is hooked on the ring of the load cell. (7) The test table is moved at a speed of 150 mm / min. (8) Record the load when moving with the load cell on the chart. Static friction coefficient μs = A / B Dynamic friction coefficient μk = C / B where A: load at the beginning of movement B: total weight of sliding piece and weight 390 g C: average value of maximum and minimum loads during movement

The abrasion test was measured according to JIS K7204. The measuring method is shown below. A pair of wear wheels were crimped on a rotating test piece under a specified load, the test pieces were worn by the wear wheels, and the wear mass was measured. Measuring equipment: Taber abrasion tester (manufactured by Toyo Seiki Co., Ltd.) Abrasion wheel: CS10F Speed: 60 rpm Load: 750 gf Abrasion frequency: 1000 times Test piece: 100 mm square x 3 t

The pin removal property was evaluated by the following method. FIG. 2 shows a schematic diagram of measurement of pin detachability. In the figure, 1 is a separator and 2 is a metal rod (core). A half-moon shaped metal rod 1 as a method for evaluating the pin pull-out property when winding a porous film.
Two separators were sandwiched between the pair, and the other end was wound several times while applying tension by load. Then, the metal rod was pulled out from the wound separator, and the pulling force at that time was measured. Metal bar: φ8 mm Half-divided shape Porous film width: 60 mm, Separator length: 800 mm Load: 300 g / 1 sheet

The shape of the core in the present invention is not particularly limited, and examples thereof include a columnar shape, a cylindrical shape, an elliptical shape, a triangular shape, a polygonal shape, a plate shape, and the like, and a core having a slit having the above shape is preferable. Used for. Furthermore, to reduce the friction coefficient, a groove is formed in the longitudinal direction of the winding core to reduce friction, a taper slit is used to make the winding core dimensions variable, or the winding core outer dimensions are variably adjusted. What can be used can be used.

[0015]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples below. Example 1 A glass plate (particle size # 2) was formed on a metal plate (material: SUS304).
No. 00) was shot-blasted in the vertical and horizontal directions to roughen the surface, and the base was processed. Next, in order to confirm the surface roughness and the slidability of this metal plate, the surface roughness and the friction coefficient were measured by the above-mentioned methods. Surface roughness (10-point average roughness) Rz and 40
The load length rate tp at the% cut level was measured. R when the reference length is 0.25 mm and the evaluation length is 1 mm
The z was 1.75 μm, and the load length ratio tp at the 40% cleavage level was 23%. The coefficient of friction was measured by the method described above. PP / PE multi-layer separator 25 μm
(Ube Industries Co., Ltd., UPOR (R) UP3025) has a static friction coefficient μs of 0.43 and a dynamic friction coefficient μk of 0.25.
Met. Also, PP / PE multi-layer separator 25 μm
(Ube Industries, Ltd., Eupore (R) UP3045, high molecular weight grade) had a static friction coefficient μs of 0.47 and a dynamic friction coefficient μk of 0.34.

Example 2 The surface was roughened with glass particles in the same manner as in Example 1, and the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. As for the surface characteristics, the surface roughness and the coefficient of friction were measured as in Example 1. Rz is 1.23 μm, tp
Was 34%, and the surface roughness was smaller and the contact area was larger than that in Example 1. Friction coefficient is Eupore (R)
In the case of UP3025, the static friction coefficient μs was 0.26 and the dynamic friction coefficient μk was 0.14. In addition, Eupore (R)
In the case of UP3045, the static friction coefficient μs was 0.31 and the dynamic friction coefficient μk was 0.17. By removing the sharp protrusions on the surface, tp was increased and the friction coefficient was reduced as compared with Example 1.

Example 3 In the same manner as in Example 1, glass particles were used to roughen the metal surface for grounding, and a ceramic coating treatment by magnetron sputtering was carried out to improve the abrasion resistance. Ceramic coating is magnetron sputter ion plating SIP
T using the processor Z700 (made by Leibold, Germany)
A film of iAlCN (quaternary composition) was formed. The film thickness is about 2
μm, and adhesion is 100 in CSEM scratch test.
No damage to the coating film was observed up to N, and the adhesion strength was superior to other methods (arc discharge method, hollow cathode method). The coating was finished by lightly polishing with a nylon scrubbing brush containing abrasives to remove sharp protrusions. As for the surface characteristics, the surface roughness and the coefficient of friction were measured as in Example 1. Surface roughness Rz is 1.5
It was 8 μm and tp was 51%. The coefficient of friction is Eupore (R) UP3025, and the coefficient of static friction μs is 0.2.
5, the dynamic friction coefficient μk was 0.20. Also, in the case of Eupore (R) UP3045, the coefficient of static friction μs is 0.3.
2. The coefficient of dynamic friction μk was 0.29. The coefficient of friction was low by removing the sharp protrusions on the surface after ceramic coating. The effect of the ceramic coating on the coefficient of friction was small.

Example 4 After being surface-treated with glass particles in the same manner as in Example 2, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Then, a ceramic coating was formed in the same manner as in Example 3. As for the surface characteristics, the surface roughness and the coefficient of friction were measured as in Example 1. Surface roughness Rz is 1.30
μm and tp were 66%. The coefficient of friction is Eupore (R) UP3025, and the coefficient of static friction μs is 0.2.
7. The dynamic friction coefficient μk was 0.22. Also, in the case of Eupore (R) UP3045, the coefficient of static friction μs is 0.3.
1, the dynamic friction coefficient μk was 0.23. As in Example 3, the effect of the ceramic coating on the friction coefficient was small, and removal of sharp protrusions on the surface after coating the ceramic showed an increase in tp, but the friction coefficient was stable and low. Table 1 shows the treatment conditions of Examples 1 to 4, and Table 2 shows the measurement results of the surface roughness and the friction coefficient.

[0019]

[Table 1]

[0020]

[Table 2]

Example 5 A glass plate (particle size # 1) was formed on a metal plate (material: SUS304).
20) was shot-blasted in the vertical and horizontal directions to roughen the surface and process the groundwork. Next, the surface roughness and friction coefficient were measured in order to confirm the surface roughness and the slidability of this metal plate. The measurement results are shown in Table 3.

Example 6 In the same manner as in Example 5, the surface was roughened with glass particles and ground processing was performed. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, the surface roughness and friction coefficient were measured in order to confirm the surface roughness and the slidability of this metal plate. The measurement results are shown in Table 3.

Comparative Example 1 Alumina particles (particle size #
80) was shot blasted in the vertical and horizontal directions to roughen the surface and process the groundwork. Next, the surface roughness and friction coefficient were measured in order to confirm the surface roughness and the slidability of this metal plate. The measurement results are shown in Table 3.

Example 7 In the same manner as in Comparative Example 1, the surface was roughened with alumina particles and grounded. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, the surface roughness and friction coefficient were measured in order to confirm the surface roughness and the slidability of this metal plate. The measurement results are shown in Table 3.

Example 8 Alumina particles (particle size #
220) was subjected to shot blasting in the vertical and horizontal directions to roughen the surface and process the groundwork. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, the surface roughness and friction coefficient were measured in order to confirm the surface roughness and the slidability of this metal plate. The measurement results are shown in Table 3.

[0026]

[Table 3]

Example 9 Alumina particles (particle size # 2) were formed on a metal plate (material: SS400).
20) was shot-blasted in the vertical and horizontal directions to roughen the surface and process the groundwork. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, the surface of this metal plate was coated with TiCrCN, TiCrN, and TiAl.
An N coating and a TiAlCN coating were formed. Then, as a final finish, light polishing was performed with an abrasive to remove sharp protrusions. Next, changes in wear characteristics and slip durability characteristics of this metal plate were investigated. That is, the wear characteristics in the case of a ceramic coated surface were compared with the wear characteristics in the case of no coating (Comparative Example 2), chrome plating (Comparative Example 3), and lubricious chrome plating (Comparative Example 4). The abrasion test was performed by the above-described abrasion test method using an abrasion wheel. The change in the friction coefficient of the worn surface was then measured. As a separator, Eupore (R)
UP3025 was used. The results are shown in Table 4.

Comparative Example 2 Changes in wear characteristics and slip durability characteristics (changes in friction coefficient) were measured in the same manner as in Example 9 except that the ceramic coating treatment was not performed. The results are shown in Table 4.

Comparative Example 3 In place of the ceramic coating treatment in Example 9, a metal plate (material: SS400) was plated with hard chrome of about 70 μm, and then abrasion resistance and slip durability were evaluated in the same manner as in Example 9. The change (change in friction coefficient) was measured. The results are shown in Table 4.

COMPARATIVE EXAMPLE 4 Instead of the ceramic coating treatment in Example 9, a self-lubricating chromium plating, which has a combination of abrasion resistance of chromium plating and low friction coefficient of tetrafluororesin, is used. After coating a metal plate (material: SS400) with a thickness of about 30 μm, changes in wear characteristics and slip durability characteristics (changes in friction coefficient) were measured in the same manner as in Example 9. The results are shown in Table 4.

[0031]

[Table 4]

From Table 4, it can be seen from Comparative Examples 2 to 4 that the metal surface remains as it is, or the lubricity chrome plating (Teflon (R) coating material) has a large wear loss in the wear test using the wear wheel containing the abrasive material. . On the other hand, when hard chrome plating or ceramic coating is applied to the surface, wear is suppressed to a low level, and the effect is remarkable. The change in the friction coefficient after wear is almost unchanged between the chrome plating and the ceramic coating, whereas in the case of self-lubricating chrome plating, which is subject to severe wear, or on the metal surface, the friction coefficient changes significantly and becomes large. That is, the pin removal property deteriorates when continuous production of the lithium secondary battery is continued.

Example 10 A metal rod was processed in the same manner as in Example 9. That is,
A metal rod (SKH51) was surface-treated with alumina particles # 220, and then a ceramic (TiAlCN) was coated to a thickness of about 2 μm. Then, the surface protrusion was removed by light polishing. As a method for evaluating the pin detachability when the separator was wound, the tensile load when pulling out the metal rod was measured. The metal rod is φ8m
Two separators were sandwiched in a space between a pair of m-divided shapes, and were wound several times while applying tension by a load to the other end. Then, the load when pulling out the metal rod from the wound separator was measured. The length of the separator is 80
A tension of 0 mm and a load of 300 g was applied to each sheet. As a separator, UPOR (R) UP3025
(PP / PE multi-layer 25 μm), UPOR (R) UP30
45 (PP / PE multi-layer 25 μm, high molecular weight grade),
The measurement was performed for four types of PE single layer 25 μm and PP / PE multiple layer 16 μm. The measurement results are shown in Table 5.

Comparative Example 5 A metal rod (SKH51) is plated with chrome to a thickness of about 50 to 70 μm.
Coated. After that, the surface roughness and the withdrawal load (N) were measured in the same manner as in Example 10. The measurement results are shown in Table 5.

Comparative Example 6 Metal rod (SKH51) is plated with lubricious chrome about 30 μm
It was coated. After that, the surface roughness and the withdrawal load (N) were measured in the same manner as in Example 10. The measurement results are shown in Table 5.

[0036]

[Table 5]

When the tensile load at the time of pulling out the metal rod having the ceramic coating is compared with the case of chrome plating (Comparative Example 5) and the case of lubricating chrome plating (Comparative Example 6), after the surface roughening is appropriately performed. It was confirmed that the metal rod having a ceramic coating has a low friction coefficient and a sliding property equivalent to that of the lubricating chrome plating which is said to be effective for pin removal. However, as described above, the lubricious chrome plating has a difficulty in durability, while the wear-resistant chrome plating has a high pulling load. Therefore, it is shown that the ceramic coating metal having an appropriate surface roughness is a good surface coating means having excellent durability, a low friction coefficient and excellent pin detachability.

[0038]

EFFECT OF THE INVENTION Since the core of the present invention has a small coefficient of friction on the surface of the core, it has good slip characteristics when the core is removed after winding the sheet-like material, and does not damage the sheet material. Further, it has excellent wear resistance and can be continuously manufactured for a long period of time.

[Brief description of drawings]

FIG. 1 shows a schematic view of friction coefficient measurement in the present invention.

FIG. 2 shows a schematic diagram of pin detachability measurement in the present invention.

Claims (2)

[Claims] 1. A winding core for winding a sheet-shaped material, wherein the surface roughness (ten-point average roughness) Rz of the surface of the winding core.
Is 0.4 to 5 μm, and the load length ratio tp at a cutting level of 40% is 20 to 95%. 2. The core according to claim 1, wherein the surface of the core is a ceramic-coated core.