JP4617625B2

JP4617625B2 - Winding core

Info

Publication number: JP4617625B2
Application number: JP2001262776A
Authority: JP
Inventors: 哲夫赤澤; 寿孝内村
Original assignee: Ube Industries Ltd
Current assignee: Ube Corp
Priority date: 2001-08-31
Filing date: 2001-08-31
Publication date: 2011-01-26
Anticipated expiration: 2021-08-31
Also published as: JP2003073036A

Description

【０００１】
【発明の属する技術分野】
本発明は、シート状材料を巻き取るための巻芯に関する。特に、本発明の巻芯は電池製造時に用いられる電池用巻芯として好適に使用される。
【０００２】
【従来の技術】
リチウム二次電池のような円筒電池は、一般に電極とセパレータとを交互に挟み込む形で巻芯に巻き付けられて捲回された後、捲回された電極素子から巻芯を抜き取って渦巻状の電極体を作製し、これを電池缶内に挿入することにより製造されている。
【０００３】
ところが、前記捲回後に巻芯を電極体から抜き取る際に、ピン（巻芯）抜け不良や成形時のセンターピン（巻芯）挿入不良による素子形状異常等があり、電池の歩留まりの低下の大きな要因となっていた。そこで、ピン抜け性を改良するために、捲回用ピン（巻芯）として、従来の鉄製の巻芯に代えて、巻芯の表面をクロムメッキ処理鏡面加工されたものが使用されているが、いまだ十分とはいえず、巻芯の抜き取り時の滑りが悪いため、巻芯を抜き取った際に、電極素子の形状が竹の子状態になったり、抜けなかったりすることが起こっていた。これらの原因は、捲回後のセパレータと巻芯との滑りの悪さ、すなわちセパレータが巻芯に比較的強く巻かれるため、捲回後に巻芯を抜き取る際のセパレータと巻芯との摩擦係数に起因するものと考えられる。
【０００４】
そこで、摩擦係数の数値を下げる試みがいくつか提案されている。例えば、巻芯表面にシリコン離型剤を塗布する方法が提案されているが、この方法の場合には、電極体を巻き取る毎に、巻芯にシリコン離型剤を塗布する必要があり、製造工程が複雑になり、生産効率も悪い。また、特開平６−２５１７７４号公報には、巻芯表面のクロムメッキ処理鏡面加工の代わりに、カーボンをエポキシ樹脂等と混合し、これを巻芯の芯体表面に塗布して摩擦係数を低減させる方法が提案されている。
しかしながら、電極素子を形成する場合、比較的大きなテンションをかけて捲回されるため、前記特開平６−２５１７７４号公報の場合には、巻芯の耐久性に難点があり、巻芯の交換の頻度が高くなり、長期間連続した製造を行うことが困難であり、生産効率の面で難点を有しており、しかも、ピン抜け性も未だ十分とは言えなかった。そこで、巻芯表面をさらに改良したものとして、クロムめっきの耐磨耗性と４フッ化樹脂の低摩擦係数の特性を複合して有する巻芯として、自己潤滑性クロムめっきした巻芯が提案されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、自己潤滑性クロムめっきした巻芯は、比較的低い摩擦係数を有しているが耐久性の面では未だ十分ではなく、さらに優れた特性を有する巻芯の提供が望まれている。
【０００６】
【課題を解決するための手段】
本発明者は、前記課題を解決するために鋭意検討の結果、巻芯の表面粗さＲｚを特定の範囲とし、さらに巻芯表面の切断レベルの負荷長さ率ｔｐを特定の範囲とすることによって、低摩擦係数を有し、しかも耐久性に優れた巻芯が得られることを見出し、本発明に至った。
すなわち本発明は、シート状材料を巻き取るための巻芯において、前記巻芯表面の表面粗さＲｚが０．４〜５μｍであって、且つ切断レベル４０％におけるｔｐが２０〜９５％であることを特徴とする巻芯に関する。
【０００７】
また本発明において、前記巻芯表面がセラミック被覆された巻芯であることが好ましい。
本発明の巻芯は、シート状材料として比較的柔軟なフィルムが使用されるリチウム二次電池の電極体製造時の巻芯として好適に使用することができる。
【０００８】
【発明の実施の形態】
本発明において、巻芯のフィルムが当接する主表面部における表面粗さ（十点平均粗さ）Ｒｚが過度に小さい場合には、摩擦抵抗が大きくなり、巻芯抜き取り時に、ピン抜け不良となり易く、一方、Ｒｚが過度に大きい場合には、フィルムの損傷が起こり易くなる。したがって、表面粗さ（十点平均粗さ）Ｒｚは０．４〜５μｍ、特に１〜３．５μｍとするのが好ましい。また、切断レベル４０％における負荷長さ率ｔｐが過度に小さい場合には、使用されるフィルムが柔らかいために摩擦抵抗が大きくなり、巻芯抜き取り時に、ピン抜け不良となり易い。したがって、負荷長さ率ｔｐは大きい方が好ましいが、表面粗さ（十点平均粗さ）Ｒｚが上記の範囲の場合には、過度に大きくすることは製造上、困難な面があり通常ｔｐは最大８５％程度である。したがって、切断レベル４０％の負荷長さ率ｔｐは２５〜８５％とするのがよい。
特に本発明において、巻芯表面にセラミック被膜を形成させた巻芯は、低摩擦係数を有し、しかも耐久性に優れており好ましい。
【０００９】
本発明において、セラミック被膜はマグネトロンスパッタ−イオンプレーティング法（ＳＩＰ法）により形成される。セラミック被膜としては、Ｔｉ、Ａｌ、Ｃｒ等の炭化物、窒化物、酸窒化物が挙げられ、具体的には、ＴｉＣ、ＴｉＮ、ＴｉＣＮ、ＴｉＡｌＮ、ＴｉＡｌＮＯ、ＴｉＡｌＮＣ、ＣｒＮ、ＴｉＣｒＮ等が挙げられる。
セラミック被膜の形成は、マグネトロンスパッタイオンプレーティングＳＩＰ処理装置Ｚ７００（ドイツ、ライボルト社製）を用いて行うのが好ましい。以下にセラミック被覆法の一例を示す。
被体（巻芯本体）を予めガラス粒子♯１２０〜♯２００、Ａｌ_２Ｏ_３♯８０〜♯２２０等を用いてサンドブラスト処理を行った後、サンドペーパー♯４００で軽く研磨し、鋭い突起を除去する。
前記被体をマグネトロンスパッタイオンプレーティングＳＩＰ処理装置Ｚ７００を用いてＴｉＮ等のセラミック被膜を約２μｍ形成する。セラミック被膜を形成した被体の表面を軽く、研磨材入りナイロンタワシ等を用いて研磨し、鋭い突起を除去し、セラミック被膜を形成した巻芯を製作する。
【００１０】
本発明において、表面粗さ（十点平均粗さ）ＲｚはＪＩＳＢ０６０１に記載された方法により求めた。また、切断レベル４０％の負荷長さ率ｔｐもＪＩＳＢ０６０１に記載された方法により求めた。
表面粗さの測定方法を以下に示す。
（１）測定はＪＩＳＢ０６０１表面粗さ−定義および表示、ＪＩＳＢ０６５１触針式表面粗さ測定器に準拠した。
測定機器：表面粗さ計（小坂研究所製型式：ＳＥ−２３００、ダイヤモンド触針先端Ｒ５μｍ、接触圧４ｍＮ）
研削面に対して直角方向に測定した。
（２）Ｒｚの求め方
Ｒｚは粗さ曲線からその平均線の方向に基準長さだけ抜き取り、この抜取り部分の平均線から縦倍率方向に測定した最も高い山頂から５番目までの山頂の標高の絶対値の平均値と最も低い谷底から５番目までの谷底の標高（深さ）の絶対値の平均値との和を求め、この値をμｍで表した。
（３）ｔｐの求め方
ｔｐは粗さ曲線からその平均線の方向に基準長さだけ抜き取り、この抜取り部分の粗さ曲線を山頂線に平行な切断レベルで切断したときに得られる切断長さの和の基準長さに対する比を百分率で表した。基準長さは０．２５ｍｍ、切断レベルは４０％とし、その時のｔｐを用いて評価項目とした
【００１１】
摩擦係数は、プラスチックフィルム及びシートの摩擦係数試験方法ＪＩＳＫ７１２５に準拠した方法により測定した。図１に摩擦係数測定の概略図を示す。
摩擦係数の測定方法を以下に示す。
（１）測定機器：スリップテスター（理学工業製Ｎｏ．３７８０）
（２）捲回時の巻芯を想定して、従来の荷重（２００ｇ）、面積（３９．６９ｃｍ^２）よりも高い荷重（３９０ｇ）、小さい面積（１．７６ｃｍ^２）とした。
（３）フィルム試験片は２３±２℃、相対湿度６５±５％に調整された雰囲気で２４時間コンディショニングを行う。
（４）滑り片表面（φ１５ｍｍ円柱）にフィルム試験片をセロハンテープで貼り付ける。
（５）表面粗し加工された試験板を測定器の試験テーブルにテープで固定する。
（６）表面粗し加工された試験板上に滑り片を乗せ、フックをロードセルのリングにかける。
（７）試験テーブルを１５０ｍｍ／ｍｉｎの速度で移動させる。
（８）ロードセルで移動時の荷重をチャート上に記録する。
静摩擦係数μｓ＝Ａ／Ｂ
動摩擦係数μｋ＝Ｃ／Ｂ
但し、Ａ：動き始めた時の荷重
Ｂ：滑り片および重りの総重量３９０ｇ
Ｃ：動き途中の最大、最小の荷重の平均値
【００１２】
磨耗試験はＪＩＳＫ７２０４に準拠して測定した。測定方法を以下に示す。
回転する試験片上に１対の磨耗輪を規定荷重の下で圧着させ、磨耗輪によって試験片を磨耗させ、磨耗質量を測定した。
測定機器：テーバー式磨耗試験機（東洋精機製）
磨耗輪：ＣＳ１０Ｆ
速度：６０ｒｐｍ
荷重：７５０ｇｆ
磨耗回数：１０００回
試験片：１００ｍｍ角×３ｔ
【００１３】
ピン抜け性評価は以下の方法で行った。図２にピン抜け性測定の概略図を示す。図中、１はセパレータ、２は金属棒（巻芯）を示す。
多孔フィルムの捲回時のピン抜け性を評価する方法として半月状の金属棒１対の間にセパレータを２枚挟み込み、もう一方の端にそれぞれ荷重による張力をかけながら数周巻きつけた。そして、巻き状態のセパレータから金属棒を引き抜きその時の引き抜き力を測定した。
金属棒：φ８ｍｍ半割り形状
多孔フィルム幅：６０ｍｍ、セパレータ長さ：８００ｍｍ
荷重：３００ｇ／１枚
【００１４】
本発明における巻芯の形状としては、特に限定されず、円柱状、円筒状、楕円形状、三角形状、多角形状、板状等が挙げられ、前記形状のスリットを有する巻芯が好適に使用される。さらに摩擦係数を軽減するために巻芯の縦方向に溝を形成して摩擦を軽減したもの、巻芯スリットをテーパ状として巻芯寸法を可変としたもの、あるいは巻芯外形寸法を可変に調整するもの等を使用することができる。
【００１５】
【実施例】
以下に実施例及び比較例を示し、本発明についてさらに詳細に説明する。
参考例１
金属板（材質：ＳＵＳ３０４）にガラス粒子（粒度♯２００）を縦横方向にショットブラストして表面を粗し下地加工を行った。次に、この金属板の表面粗さと滑り性を確認するために表面粗さと摩擦係数を前記した方法により測定した。表面粗さ（十点平均粗さ）Ｒｚ及び４０％切断レベルにおける負荷長さ率ｔｐを測定した。基準長さを０．２５ｍｍ、評価長さを１ｍｍとしたときのＲｚは１．７５μｍ、また４０％切断レベルにおける負荷長さ率ｔｐは２３％であった。摩擦係数を前記した方法により測定した。ＰＰ・ＰＥ複層セパレータ２５μｍ（宇部興産（株）製、ユーポア（Ｒ）ＵＰ３０２５）の静摩擦係数μｓは０．４３、動摩擦係数μｋは０．２５であった。また、ＰＰ・ＰＥ複層セパレータ２５μｍ（宇部興産（株）製、ユーポア（Ｒ）ＵＰ３０４５、高分子量グレード）の静摩擦係数μｓは０．４７、動摩擦係数μｋは０．３４であった。
【００１６】
参考例２
参考例１と同様にしてガラス粒子で表面粗し加工し、さらにサンドペーパー（♯４００）で軽く表面研磨して鋭い突起を取り除いた。表面特性は参考例１と同様に表面粗さと摩擦係数を測定した。Ｒｚは１．２３μｍ、ｔｐは３４％であり、参考例１と比較して、表面粗さが小さくなり接触面積も増加した。摩擦係数はユーポア（Ｒ）ＵＰ３０２５のとき、静摩擦係数μｓは０．２６、動摩擦係数μｋは０．１４であった。また、ユーポア（Ｒ）ＵＰ３０４５のとき、静摩擦係数μｓは０．３１、動摩擦係数μｋは０．１７であった。表面の鋭い突起を取り除くことでｔｐが大きくなり参考例１と比較して摩擦係数は低減された。
【００１７】
実施例１
参考例１と同様にガラス粒子で金属表面を粗し下地加工をし、磨耗性を向上させるためマグネトロンスパッタリングによるセラミック被膜処理を行った。セラミック被膜はマグネトロンスパッタイオンプレーティングＳＩＰ処理装置Ｚ７００（ドイツ、ライボルト社製）を用いＴｉＡｌＣＮ（４元組成）の被膜を形成した。膜厚は約２μｍであり、密着力はＣＳＥＭスクラッチ試験で１００Ｎまで被膜の破壊は観測されず、密着強度は他法（アーク放電法、ホローカソード法）と同等で優れている。被膜は最終仕上げに研磨材入りナイロンタワシで軽く研磨して鋭い突起を除去した。表面特性は参考例１と同様に表面粗さと摩擦係数を測定した。表面粗さＲｚは１．５８μｍ、ｔｐは５１％であった。摩擦係数はユーポア（Ｒ）ＵＰ３０２５のとき、静摩擦係数μｓは０．２５、動摩擦係数μｋは０．２０であった。また、ユーポア（Ｒ）ＵＰ３０４５のとき、静摩擦係数μｓは０．３２、動摩擦係数μｋは０．２９であった。セラミック被覆後の表面の鋭い突起を取り除くことにより摩擦係数は低かった。セラミック被覆の摩擦係数への影響は少なかった。
【００１８】
実施例２
参考例２と同様にしてガラス粒子で表面加工した後、さらにサンドペーパー（♯４００）で軽く表面研磨して鋭い突起を取り除いた。次いで実施例１と同様にしてセラミック被膜を形成した。表面特性は参考例１と同様に表面粗さと摩擦係数を測定した。表面粗さＲｚは１．３０μｍ、ｔｐは６６％であった。摩擦係数はユーポア（Ｒ）ＵＰ３０２５のとき、静摩擦係数μｓは０．２７、動摩擦係数μｋは０．２２であった。また、ユーポア（Ｒ）ＵＰ３０４５のとき、静摩擦係数μｓは０．３１、動摩擦係数μｋは０．２３であった。実施例１の場合と同様に、セラミック被膜の摩擦係数への影響は少なく、セラミック被覆後の表面の鋭い突起を取り除くことによりｔｐの上昇は見られるが摩擦係数は安定して低かった。参考例１〜２、実施例１〜２の処理条件を表１に、また表面粗さと摩擦係数の測定結果を表２に示す。
【００１９】
【表１】

【００２０】
【表２】

【００２１】
参考例３
金属板（材質：ＳＵＳ３０４）にガラス粒子（粒度♯１２０）を縦横方向にショットブラストして表面を粗し下地加工した。次に、この金属板の表面粗さと滑り性を確認するために表面粗さと摩擦係数を測定した。その測定結果を表３に示す。
【００２２】
参考例４
参考例３と同様にしてガラス粒子で表面を粗し下地加工した。さらにサンドペーパー（♯４００）で軽く表面研磨して鋭い突起を取り除いた。次に、この金属板の表面粗さと滑り性を確認するために表面粗さと摩擦係数を測定した。その測定結果を表３に示す。
【００２３】
比較例１
金属板（材質：ＳＵＳ３０４）にアルミナ粒子（粒度♯８０）を縦横方向にショットブラストして表面を粗し下地加工した。次に、この金属板の表面粗さと滑り性を確認するために表面粗さと摩擦係数を測定した。その測定結果を表３に示す。
【００２４】
参考例５
比較例１と同様にしてアルミナ粒子で表面を粗し下地加工した。さらにサンドペーパー（♯４００）で軽く表面研磨して鋭い突起を取り除いた。次に、この金属板の表面粗さと滑り性を確認するために表面粗さと摩擦係数を測定した。その測定結果を表３に示す。
【００２５】
参考例６
金属板（材質：ＳＵＳ３０４）にアルミナ粒子（粒度♯２２０）を縦横方向にショットブラストして表面を粗し下地加工した。さらにサンドペーパー（♯４００）で軽く表面研磨して鋭い突起を取り除いた。次に、この金属板の表面粗さと滑り性を確認するために表面粗さと摩擦係数を測定した。その測定結果を表３に示す。
【００２６】
【表３】

【００２７】
実施例３
金属板（材質：ＳＳ４００）にアルミナ粒子（粒度♯２２０）を縦横方向にショットブラストして表面を粗し下地加工した。さらにサンドペーパー（♯４００）で軽く表面研磨して鋭い突起を取り除いた。次に、この金属板の表面にＴｉＣｒＣＮ被覆、ＴｉＣｒＮ被覆、ＴｉＡｌＮ被覆、ＴｉＡｌＣＮ被覆を形成した。その後、最終仕上げとして研磨材で軽く研磨して鋭い突起を取り除いた。次に、この金属板の磨耗特性と滑り耐久特性の変化を調べた。すなわち、セラミック被覆表面の場合の磨耗特性と、被覆なし（比較例２）、クロムめっき（比較例３）、潤滑性クロムめっき（比較例４）の場合の磨耗特性の比較を行った。磨耗試験は磨耗輪による前記した磨耗試験方法により行った。その後磨耗表面の摩擦係数の変化を測定した。セパレータとしては、ユーポア（Ｒ）ＵＰ３０２５を使用した。その結果を表４に示す。
【００２８】
比較例２
セラミック被覆処理を行わなかったほかは、実施例３と同様にして磨耗特性と滑り耐久特性の変化（摩擦係数の変化）を測定した。その結果を表４に示す。
【００２９】
比較例３
実施例３におけるセラミック被覆処理の代わりに、金属板（材質：ＳＳ４００）に約７０μｍの硬質クロムめっきを行った後、実施例３と同様にして磨耗特性と滑り耐久特性の変化（摩擦係数の変化）を測定した。その結果を表４に示す。
【００３０】
比較例４
実施例３におけるセラミック被覆処理の代わりに、クロムめっきの耐磨耗性と４フッ化樹脂の低摩擦係数等の特性を複合して持つとされる自己潤滑性クロムめっきを金属板（材質：ＳＳ４００）に約３０μｍ被覆した後、実施例３と同様にして磨耗特性と滑り耐久特性の変化（摩擦係数の変化）を測定した。その結果を表４に示す。
【００３１】
【表４】

【００３２】
表４から、比較例２〜４に見られるように金属表面のままや、潤滑性クロムめっき（テフロン（Ｒ）被覆材）では研磨材入りの磨耗輪による磨耗試験では磨耗減量が大きい。一方、表面に硬質のクロムめっきやセラミック被覆を行うと、磨耗が低く抑えられ、効果が顕著に現れている。磨耗後の摩擦係数の変化はクロムめっきとセラミック被覆はほとんど変化がないのに対し、磨耗の激しい自己潤滑性クロムめっきや金属表面のままの場合には、摩擦係数が著しく変化して、大きくなっており、リチウム二次電池の連続製造を続けるとピン抜け性が悪くなることを示している。
【００３３】
実施例４
実施例３と同様の処理を金属棒に加工した。すなわち、金属棒（ＳＫＨ５１）をアルミナ粒子♯２２０で表面加工した後、セラミック（ＴｉＡｌＣＮ）を約２μｍ被膜した。その後、軽い研磨により表面突起を除いた。セパレータの捲回時のピン抜け性を評価する方法として金属棒引き抜き時の引張り荷重を測定した。金属棒はφ８ｍｍ半割形状で一対の間の隙間に２枚のセパレータを挟み込み、もう一方の端に荷重による張力をかけながら数回巻き付けた。そして巻き状態のセパレータから金属棒を引き抜く時の荷重を測定した。セパレータの長さは８００ｍｍ、それぞれ１枚毎に荷重３００ｇの張力をかけた。セパレータとして、ユーポア（Ｒ）ＵＰ３０２５（ＰＰ・ＰＥ複層２５μｍ）、ユーポア（Ｒ）ＵＰ３０４５（ＰＰ・ＰＥ複層２５μｍ、高分子量グレード）、ＰＥ単層２５μｍ、ＰＰ・ＰＥ複層１６μｍの４種について測定を行った。その測定結果を表５に示す。
【００３４】
比較例５
金属棒（ＳＫＨ５１）にクロムめっき約５０〜７０μｍ被膜をした。その後実施例４と同様に表面粗さ、引き抜き荷重（Ｎ）を測定した。その測定結果を表５に示す。
【００３５】
比較例６
金属棒（ＳＫＨ５１）に潤滑性クロムめっき約３０μｍ被覆をした。その後実施例４と同様に表面粗さ、引き抜き荷重（Ｎ）を測定した。その測定結果を表５に示す。
【００３６】
【表５】

【００３７】
セラミック被膜を有する金属棒の引き抜き時の引張り荷重を、クロムめっきした場合（比較例５）、潤滑性クロムめっきした場合（比較例６）と比較すると、適度な表面粗し加工した後にセラミック被膜を有する金属棒は低摩擦係数でピン抜け性に効果があるとされる潤滑性クロムめっきと同等の滑り特性が確認された。しかしながら、潤滑性クロムめっきは前記したように磨耗試験からも分るように耐久性に難点があり、一方耐磨耗性があるクロムめっきは引き抜き荷重が高い。したがって、適度な表面粗さを有するセラミック被膜金属が耐久性、低摩擦係数でピン抜け性に優れた良好な表面被膜手段であることを示している。
【００３８】
【発明の効果】
本発明の巻芯は、巻芯表面の摩擦係数が小さいのでシート状材料を巻き取った後に巻芯を抜き取る際の滑り特性が良く、シート材料を傷つけることがない。また、耐磨耗特性に優れており、長期間にわたり連続製造することができる。
【図面の簡単な説明】
【図１】本発明における摩擦係数測定の概略図を示す。
【図２】本発明におけるピン抜け性測定の概略図を示す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a core for winding up a sheet-like material. In particular, the core of the present invention is suitably used as a battery core used during battery production.
[0002]
[Prior art]
Cylindrical batteries such as lithium secondary batteries are generally wound and wound around a winding core with electrodes and separators alternately sandwiched, and then the winding core is removed from the wound electrode element. It is manufactured by making a body and inserting it into a battery can.
[0003]
However, when the core is pulled out from the electrode body after the winding, there is an element shape abnormality due to a pin (core) missing defect or a center pin (core) improper insertion at the time of molding, which greatly reduces the yield of the battery. It was a factor. Therefore, in order to improve the pin pull-out property, as the winding pin (core), instead of the conventional iron core, the surface of the core is chrome-plated and mirror-finished is used. However, it is still not sufficient, and slipping at the time of extracting the core is poor, so that when the core is extracted, the shape of the electrode element becomes a bamboo shoot state or cannot be removed. These causes are due to the poor sliding between the separator and the core after winding, i.e., because the separator is wound relatively strongly around the core, and the friction coefficient between the separator and the core when the core is removed after winding. It is thought to be caused.
[0004]
Thus, several attempts have been proposed to lower the friction coefficient. For example, a method of applying a silicon release agent to the surface of the core has been proposed, but in this method, it is necessary to apply a silicon release agent to the core every time the electrode body is wound up. The manufacturing process becomes complicated and the production efficiency is poor. Japanese Patent Laid-Open No. 6-251774 discloses a technique for reducing the friction coefficient by mixing carbon with an epoxy resin or the like and applying this to the core surface of the core instead of chrome plating mirror surface processing on the surface of the core. There is a proposed method.
However, when forming an electrode element, since it is wound with a relatively large tension, in the case of the above-mentioned JP-A-6-251774, there is a difficulty in the durability of the core, and the replacement of the core is difficult. The frequency is high, it is difficult to carry out continuous production for a long period of time, and there are difficulties in terms of production efficiency. Moreover, the pin pull-out property has not been sufficient. Therefore, a self-lubricating chrome-plated core has been proposed as a core that combines the wear resistance of chrome plating and the low friction coefficient characteristics of tetrafluororesin as a further improved core surface. ing.
[0005]
[Problems to be solved by the invention]
However, the self-lubricating chrome-plated core has a relatively low coefficient of friction, but is still not sufficient in terms of durability, and it is desired to provide a core having further excellent characteristics.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventor sets the surface roughness Rz of the core to a specific range, and further sets the load length ratio tp of the cutting level of the core surface to a specific range. Thus, it was found that a core having a low coefficient of friction and excellent durability was obtained, and the present invention was achieved.
That is, according to the present invention, in the core for winding the sheet-like material, the surface roughness Rz of the surface of the core is 0.4 to 5 μm, and tp at a cutting level of 40% is 20 to 95%. It is related with the winding core characterized by this.
[0007]
In the present invention, the core surface is preferably a core coated with a ceramic.
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-like material.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, when the surface roughness (ten-point average roughness) Rz in the main surface portion with which the film of the core is in contact is excessively small, the frictional resistance is increased, and pin pull-out failure is likely to occur when the core is removed. On the other hand, when Rz is excessively large, the film is easily damaged. Therefore, the surface roughness (ten-point average roughness) Rz is preferably 0.4 to 5 μm, particularly preferably 1 to 3.5 μm. In addition, when the load length ratio tp at a cutting level of 40% is excessively small, the film used is soft, so that the frictional resistance increases, and pin pull-out failure tends to occur when the core is removed. Accordingly, 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 because it is difficult to manufacture. Is about 85% at maximum. Therefore, the load length ratio tp at the cutting level of 40% is preferably 25 to 85%.
In particular, in the present invention, a core having a ceramic film formed on the surface of the core has a low coefficient of friction and is excellent in durability.
[0009]
In the present invention, the ceramic coating is formed by a magnetron sputtering-ion plating method (SIP method). Examples of the ceramic coating include carbides such as Ti, Al, and Cr, nitrides, and oxynitrides. Specific examples include TiC, TiN, TiCN, TiAlN, TiAlNO, TiAlNC, CrN, and TiCrN.
The ceramic coating is preferably formed using a magnetron sputter ion plating SIP processing apparatus Z700 (manufactured by Leibold, Germany). An example of the ceramic coating method is shown below.
The body (core body) is pre-sandblasted with glass particles # 120 to # 200, Al ₂ O ₃ # 80 to # 220, etc., and then lightly polished with sandpaper # 400 to remove sharp protrusions. To do.
About 2 μm of a ceramic film such as TiN is formed on the object using a magnetron sputter ion plating SIP processing apparatus Z700. The surface of the substrate on which the ceramic coating has been formed is lightly polished using a nylon scrubber with abrasives, etc., and sharp protrusions are removed to produce a winding core on which the ceramic coating is formed.
[0010]
In the present invention, the surface roughness (ten-point average roughness) Rz was determined by the method described in JIS B0601. Further, the load length ratio tp at a cutting level of 40% was also determined by the method described in JIS B0601.
The method for measuring the surface roughness is shown below.
(1) The measurement was based on JIS B0601 surface roughness-definition and display, JIS B0601 stylus type surface roughness measuring instrument.
Measuring instrument: Surface roughness meter (manufactured by Kosaka Laboratory Model: SE-2300, diamond stylus tip R 5 μm, contact pressure 4 mN)
Measurements were made at right angles to the ground surface.
(2) Rz calculation method Rz is extracted from the roughness curve by the reference length in the direction of the average line, and measured from the average line of this extracted part in the vertical magnification direction to the highest peak height from the highest peak to the fifth peak. The sum of the average value of the absolute values and the average value of the absolute values of the altitudes (depths) of the bottom valley from the lowest valley bottom to the fifth was obtained, and this value was expressed in μm.
(3) How to obtain 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 peak line. The ratio of the sum of to the reference length is expressed as a percentage. The reference length was 0.25 mm, the cutting level was 40%, and tp was used as an evaluation item.
The coefficient of friction was measured by a method based on JIS K7125, a coefficient of friction test method for plastic films and sheets. FIG. 1 shows a schematic diagram of friction coefficient measurement.
The method for measuring the friction coefficient is shown below.
(1) Measuring instrument: Slip tester (No. 3780, manufactured by Rigaku Corporation)
(2) Assuming the winding core during winding, the load (390 g) and the area (1.76 cm ² ) higher than the conventional load (200 g), area (39.69 cm ² ) were set.
(3) The film test piece is conditioned for 24 hours in an atmosphere adjusted to 23 ± 2 ° C. and relative humidity 65 ± 5%.
(4) A film test piece is affixed to the surface of the sliding piece (φ15 mm cylinder) with a cellophane tape.
(5) Fix the surface-roughened test plate to the test table of the measuring instrument with tape.
(6) Place a sliding piece on the test plate having a roughened surface and place the hook 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
Coefficient of dynamic friction μk = C / B
However, A: Load at the start of movement B: Total weight of sliding piece and weight 390 g
C: Average value of maximum and minimum load during movement
The abrasion test was measured according to JIS K7204. The measuring method is shown below.
A pair of wear wheels were pressed onto the rotating test piece under a specified load, the test piece was worn by the wear ring, and the wear mass was measured.
Measuring equipment: Taber type abrasion tester (manufactured by Toyo Seiki)
Wear wheel: CS10F
Speed: 60rpm
Load: 750gf
Number of wears: 1000 times Test piece: 100 mm square x 3 t
[0013]
The pin pull-out evaluation was performed by the following method. FIG. 2 shows a schematic diagram of pin-out property measurement. In the figure, 1 is a separator, and 2 is a metal rod (core).
As a method for evaluating the pin pull-out property at the time of winding the porous film, two separators were sandwiched between a pair of half-moon shaped metal rods and wound around the other end while applying tension by a load. Then, the metal rod was pulled out from the rolled separator, and the pulling force at that time was measured.
Metal rod: φ8mm Half-divided porous film width: 60mm, Separator length: 800mm
Load: 300g / sheet [0014]
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 of the above shape is preferably used. The In order to further reduce the friction coefficient, the friction is reduced by forming a groove in the longitudinal direction of the core, the core slit is tapered and the core dimension is variable, or the core outer dimension is variably adjusted. Can be used.
[0015]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
Reference example 1
A glass plate (particle size: # 200) was shot blasted in a vertical and horizontal direction on a metal plate (material: SUS304) to roughen the surface and perform a base processing. Next, in order to confirm the surface roughness and slipperiness of the metal plate, the surface roughness and the friction coefficient were measured by the above-described methods. The surface roughness (ten-point average roughness) Rz and the load length ratio tp at a 40% cutting level were measured. When the reference length was 0.25 mm and the evaluation length was 1 mm, Rz was 1.75 μm, and the load length ratio tp at the 40% cutting level was 23%. The coefficient of friction was measured by the method described above. PP / PE multilayer separator 25 μm (manufactured by Ube Industries, Ltd., UPORE (R) UP3025) had a static friction coefficient μs of 0.43 and a dynamic friction coefficient μk of 0.25. The PP / PE multilayer separator 25 μm (manufactured by Ube Industries, Ltd., UPORE® UP3045, high molecular weight grade) had a static friction coefficient μs of 0.47 and a dynamic friction coefficient μk of 0.34.
[0016]
Reference example 2
The surface was roughened with glass particles in the same manner as in Reference 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 in the same manner as in Reference Example 1 . Rz was 1.23 μm and tp was 34%. Compared to Reference Example 1 , the surface roughness was reduced and the contact area was also increased. When the friction coefficient was UPORE (R) UP3025, the static friction coefficient μs was 0.26, and the dynamic friction coefficient μk was 0.14. When UPORE (R) UP3045, the static friction coefficient μs was 0.31, and the dynamic friction coefficient μk was 0.17. By removing sharp protrusions on the surface, tp was increased, and the friction coefficient was reduced as compared with Reference Example 1 .
[0017]
Example 1
In the same manner as in Reference Example 1 , the metal surface was roughened with glass particles and the base was processed, and a ceramic coating treatment by magnetron sputtering was performed to improve the wear resistance. As the ceramic coating, a TiAlCN (quaternary composition) coating was formed using a magnetron sputter ion plating SIP processing device Z700 (manufactured by Leibold, Germany). The film thickness is about 2 μm, and the adhesion strength is not observed up to 100 N in the CSEM scratch test, and the adhesion strength is equal to and superior to other methods (arc discharge method, hollow cathode method). The coating was lightly polished with a nylon scrubbing abrasive for final finishing to remove sharp protrusions. As for the surface characteristics, the surface roughness and the coefficient of friction were measured in the same manner as in Reference Example 1 . The surface roughness Rz was 1.58 μm and tp was 51%. When the friction coefficient was UPORE (UP) UP3025, the static friction coefficient μs was 0.25, and the dynamic friction coefficient μk was 0.20. When UPORE (R) UP3045, the static friction coefficient μs was 0.32, and the dynamic friction coefficient 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 friction coefficient was small.
[0018]
Example 2
After surface treatment with glass particles in the same manner as in Reference Example 2 , the surface was further lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, a ceramic coating was formed in the same manner as in Example 1 . As for the surface characteristics, the surface roughness and the coefficient of friction were measured in the same manner as in Reference Example 1 . The surface roughness Rz was 1.30 μm and tp was 66%. When the friction coefficient was UPORE (R) UP3025, the static friction coefficient μs was 0.27 and the dynamic friction coefficient μk was 0.22. When UPORE (R) UP3045, the static friction coefficient μs was 0.31, and the dynamic friction coefficient μk was 0.23. As in Example 1 , the influence of the ceramic coating on the friction coefficient was small, and by removing sharp protrusions on the surface after the ceramic coating, an increase in tp was observed, but the friction coefficient was stable and low. Table 1 shows the treatment conditions of Reference Examples 1 and 2 and Examples 1 and 2, and Table 2 shows the measurement results of the surface roughness and the friction coefficient.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
Reference example 3
Glass particles (particle size # 120) were shot blasted in a vertical and horizontal direction on a metal plate (material: SUS304) to roughen the surface and perform a base processing. Next, in order to confirm the surface roughness and slipperiness of this metal plate, the surface roughness and the friction coefficient were measured. The measurement results are shown in Table 3.
[0022]
Reference example 4
In the same manner as in Reference Example 3 , the surface was roughened with glass particles and the substrate was processed. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, in order to confirm the surface roughness and slipperiness of this metal plate, the surface roughness and the friction coefficient were measured. The measurement results are shown in Table 3.
[0023]
Comparative Example 1
Alumina particles (particle size # 80) were shot blasted in the vertical and horizontal directions on a metal plate (material: SUS304), and the surface was roughened and ground. Next, in order to confirm the surface roughness and slipperiness of this metal plate, the surface roughness and the friction coefficient were measured. The measurement results are shown in Table 3.
[0024]
Reference Example 5
In the same manner as in Comparative Example 1, the surface was roughened with alumina particles and the substrate was processed. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, in order to confirm the surface roughness and slipperiness of this metal plate, the surface roughness and the friction coefficient were measured. The measurement results are shown in Table 3.
[0025]
Reference Example 6
Alumina particles (particle size # 220) were shot blasted in the vertical and horizontal directions on a metal plate (material: SUS304), and the surface was roughened and ground. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, in order to confirm the surface roughness and slipperiness of this metal plate, the surface roughness and the friction coefficient were measured. The measurement results are shown in Table 3.
[0026]
[Table 3]

[0027]
Example 3
Alumina particles (particle size # 220) were shot blasted in the vertical and horizontal directions on a metal plate (material: SS400) to roughen the surface and perform the base processing. Further, the surface was lightly polished with sandpaper (# 400) to remove sharp protrusions. Next, TiCrCN coating, TiCrN coating, TiAlN coating, and TiAlCN coating were formed on the surface of the metal plate. Thereafter, the sharp finish was removed by lightly polishing with an abrasive as the final finish. Next, changes in the wear characteristics and sliding durability characteristics of the metal plate were examined. That is, the wear characteristics in the case of the ceramic coated surface were compared with the wear characteristics in the case of no coating (Comparative Example 2), chromium plating (Comparative Example 3), and lubricious chromium plating (Comparative Example 4). The abrasion test was performed by the above-described abrasion test method using an abrasion wheel. Thereafter, the change in the friction coefficient of the worn surface was measured. As a separator, UPORE (R) UP3025 was used. The results are shown in Table 4.
[0028]
Comparative Example 2
Except that the ceramic coating treatment was not performed, changes in wear characteristics and sliding durability characteristics (changes in friction coefficient) were measured in the same manner as in Example 3 . The results are shown in Table 4.
[0029]
Comparative Example 3
Instead of the ceramic coating treatment in Example 3, after applying a hard chromium plating of about 70 μm to a metal plate (material: SS400), changes in wear characteristics and sliding durability characteristics (changes in friction coefficient) were performed in the same manner as in Example 3. ) Was measured. The results are shown in Table 4.
[0030]
Comparative Example 4
Instead of the ceramic coating treatment in Example 3, a self-lubricating chromium plating, which is said to have a combination of wear resistance of chromium plating and low friction coefficient of tetrafluororesin, is applied to a metal plate (material: SS400). After coating with about 30 μm, the changes in the wear characteristics and the sliding durability characteristics (changes in the friction coefficient) were measured in the same manner as in Example 3 . The results are shown in Table 4.
[0031]
[Table 4]

[0032]
From Table 4, as seen in Comparative Examples 2 to 4, the wear loss is large in the wear test with the wear ring containing the abrasive in the case of the metal surface as it is or in the lubricating chrome plating (Teflon (R) coating 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 coefficient of friction after wear is almost the same for chrome plating and ceramic coating, whereas the friction coefficient changes drastically and increases when the self-lubricating chrome plating or metal surface with severe wear remains. This shows that the continuous removal of the lithium secondary battery continues to deteriorate the pin pull-out property.
[0033]
Example 4
The same treatment as in Example 3 was processed into a metal bar. That is, after a metal rod (SKH51) was surface-treated with alumina particles # 220, a ceramic (TiAlCN) film was coated by about 2 μm. Thereafter, surface protrusions were removed by light polishing. As a method for evaluating the pin pull-out property during winding of the separator, the tensile load at the time of pulling out the metal rod was measured. The metal bar had a half-diameter shape of φ8 mm, and two separators were sandwiched between a pair of gaps, and the other end was wound several times while applying tension due to a load. Then, the load when the metal rod was pulled out from the rolled separator was measured. The length of the separator was 800 mm, and a tension of 300 g load was applied to each separator. As separators, 4 types of Eupore (R) UP3025 (PP / PE multilayer 25 μm), Eupore (R) UP3045 (PP / PE multilayer 25 μm, high molecular weight grade), PE single layer 25 μm, PP / PE multilayer 16 μm Measurements were made. The measurement results are shown in Table 5.
[0034]
Comparative Example 5
A metal rod (SKH51) was coated with a chrome plating of about 50 to 70 μm. Thereafter, the surface roughness and the drawing load (N) were measured in the same manner as in Example 4 . The measurement results are shown in Table 5.
[0035]
Comparative Example 6
A metal rod (SKH51) was coated with about 30 μm of lubricious chromium plating. Thereafter, the surface roughness and the drawing load (N) were measured in the same manner as in Example 4 . The measurement results are shown in Table 5.
[0036]
[Table 5]

[0037]
Compared with the case of chrome plating (Comparative Example 5) and the case of lubricating chrome plating (Comparative Example 6), the tensile load at the time of pulling out the metal rod having the ceramic coating was compared with the case where the ceramic coating was applied after moderate surface roughening. It was confirmed that the metal rods had the same sliding characteristics as the lubricious chrome plating, which is said to have a low coefficient of friction and an effective pin-removability. However, as described above, the lubricating chrome plating has a drawback in durability as seen from the wear test, while the chrome plating having wear resistance has a high pulling load. Therefore, it has been shown that a ceramic coating metal having an appropriate surface roughness is a good surface coating means having durability, a low friction coefficient and excellent pin pull-out property.
[0038]
【The invention's effect】
Since the core of the present invention has a small coefficient of friction on the surface of the core, it has good sliding characteristics when the core is removed after winding the sheet-like material, and does not damage the sheet material. Moreover, it is excellent in wear resistance and can be continuously produced over a long period of time.
[Brief description of the drawings]
FIG. 1 shows a schematic diagram of friction coefficient measurement in the present invention.
FIG. 2 shows a schematic diagram of pin-out measurement in the present invention.

Claims

A core which is withdrawn after Tsu taken up the sheet material, the core surface are ceramic coating, the surface roughness of the core surface (ten-point average roughness) Rz is 1~3.5μm The load length ratio tp at a cutting level of 40% is 25 to 85% .

The core according to claim 1, wherein the surface of the core is subjected to shot blasting.