JP4105558B2 - Aluminum material for electrolytic capacitor electrode, electrode material for electrolytic capacitor, and electrolytic capacitor - Google Patents

Description

【００２４】
ここで、Ｃｊ（ｊ＝１，２，３，…ｎ）は各々結晶性酸化物粒子のアスぺクト比であり、透過型電子顕微鏡により観察される結晶性酸化物粒子の外周に対し外接する最小面積の直方形において、直方形が長方形の場合は長方形の長辺をＡ’、短辺をＢ’としたときＣｊ＝Ａ’／Ｂ’、直方形が正方形の場合はＣｊ＝１と規定する。
【００２５】
【数４】

【００２６】
（２） アスぺクト比の幾何標準偏差σ_gが１．６以下である前項１に記載の電解コンデンサ電極用アルミニウム材。
（３） 粒子径Ｄが７０ｎｍ以上の結晶性酸化物粒子のうち、７０〜ｌ００％の粒子の粒子径Ｄが８０〜１２００ｎｍである前項１または前項２に記載の電解コンデンナ電極用アルミニウム材。
（４） 粒子径Ｄが８０〜１２００ｎｍの結晶性酸化物粒子の密度が１×１０⁵〜５×１０⁶個／ｍｍ²である前項３に記載の電解ロンデンサ電極用アルミニウム材。
（５） 酸化膜の厚さが、ハンターホール法による測定値で２．５〜５ｎｍである前項１ないし前項４の何れかに記載の電解コンデンサ電極用アルミニウム材。
（６） アルミニウム材におけるＡｌ純度が９９．９質量％以上である前項１ないし前項５の何れかに記載の電解コンデンサ電極用アルミニウム材。
（７） 前記電解コンデンサ電極用アルミニウム材が陽極材である前項１ないし前項６の何れかに記載の電解コンデンサ電極用アルミニウム材。
【００２７】
また、本発明の電解コンデンサ用電極材は下記の構成を有する。
（８） 前項１ないし前項７の何れかの電解コンデンサ電極用アルミニウム材がエッチングされてなることを特徴とする電解コンデンサ用電極材。
（９） エッチングが直流エッチングである前項８に記載の電解コンデンサ用電極材。
【００２８】
さらに、本発明の電解コンデンサは下記の構成を有する。
（１０） 電極材として、前項８または前項９に記載の電解コンデンサ用電極材が用いられていることを特徴とする電解コンデンサ。
【００２９】
本発明の電解コンデンサ電極用アルミニウム材は、表層の酸化膜に存在する結晶性酸化物粒子のアスペクト比および密度を規定することによって、エッチングによる実効面積の拡大を確かなものとしている。
【００３０】
本発明の対象となる結晶性酸化物粒子は、長辺＝Ａ、短辺＝ＢとしたときにＤ＝（Ａ＋Ｂ）／２で規定される粒子径Ｄが７０ｎｍ以上の粒子である。粒子径Ｄが７０ｎｍ未満の粒子はエッチピット核になりにくいためである。
【００３１】
前記結晶性酸化物粒子のアスぺクト比が全て同一の場合、（Ｆ１）（Ｆ２）式で計算される幾何標準偏差σ_gは１であり、アスべクト比の分布範囲が広くなるに従って幾何標準偏差σ_gが大きくなる。従って幾何標準偏差σ_gが小さく１に近いほどアスペクト比の分布範囲が狭く、アスぺクト比の均一性が優れていることを示す。アスぺクト比が均一なほどエッチピットが均一に生成するため、結晶性酸化物粒子の幾何標準偏差σ_gはさらにｌ．６以下であることが好ましく、特に好ましい幾何標準偏差σ_gは１．４以下である。
【００３２】
また、粒子径Ｄが７０ｎｍ以上の結晶性酸化物微粒子の密度を１×１０⁴〜１×１０⁷個／ｍｍ²と規定するのは、密度が１×１０⁴個／ｍｍ²未満の場合はエッチピット核となる結晶性酸化物微粒子が少なすぎ、一方密度が１×１０⁷個／ｍｍ²より高い場合は結晶性酸化物微粒子を核として生成したエッチピットが結合することにより、いずれの場合も有効に実効面積の拡大を図ることができないからである。
【００３３】
より実効面積の拡大を図るには、粒子径Ｄが７０ｎｍ以上の結晶性酸化物微粒子のうち、７０〜１００％の粒子の粒子径Ｄが８０〜１２００ｎｍであることが好ましい。粒子径Ｄが８０ｎｍ未満の結晶性酸化物微粒子に比べ特にエッチピット核になりやすく、粒子径Ｄが１２００ｎｍを越える結晶性酸化物微粒子よりも隣接するエッチピットの結合が少ないためである。
【００３４】
さらに、粒子径Ｄが８０〜１２００ｎｍである粒子の密度が１×１０⁵〜５×ｌ０⁶個／ｍｍ²であることが好ましく、エッチングによって確実に実効面積を拡大することができる。
【００３５】
また、本発明において、電解コンデンサ電極用アルミニウム材の厚さは特に規定されない。箔と称される厚さ２００μｍ以下のものはもとより、それ以上の厚さの板、これらを用いた成形体も本発明に含まれる。
【００３６】
本発明の電解コンデンサ電極用アルミニウム材は、表層酸化膜に存在する結晶性酸化物粒子のアスぺクト比の均一性が高く粒子密度が適正なものとなされているため、エッチングによって結晶性酸化物粒子を核とするエッチピットが多数かつ均一に生成される。このため、実効面積が拡大されて静電容量が増大する。
【００３７】
前記結晶性酸化物粒子の種類としてはγ−Ａｌ₂Ｏ₃をはじめとするＡｌ₂Ｏ₃、べーマイトをはじめとするＡｌＯＯＨ、アルミニウム以外の含有金属（例えばＭｇ，Ｐｂ，Ｃｕ等）の酸化物および水酸化物、アルミニウムとアルミニウム以外の含有金属（例えばＭｇ，Ｐｂ，Ｃｕ等）との複合金属酸化物あるいは水酸化物であれば特に限定されるものではなく、単結晶、多結晶のどちらでも良い。また、単一もしくは複数の結晶が無定形物質に覆われて一つの粒子を形成する物でも良く、凝集した酸化物結晶の間に無定形酸化物が存在していても良い。作製した電解コンデンサ用アルミニウム材表面に存在する結晶性酸化物は、アルミニウム材の片面に支持膜としてカーボン等の蒸着膜を形成させた後、例えば臭素−メタノール液に浸漬させることによりアルミニウムを溶解させたサンプルを透過型電子顕微鏡で観察することにより確認できる。上記透過型電子顕微鏡観察サンプル作製時のアルミニウム溶解に用いる液としては臭素−メタノール液の他に、塩化第２水銀水溶液、ヨウ素−メタノール液等の適用も可能である。
【００３８】
前記透過型電子顕微鏡観察領域に存在する結晶性酸化物粒子は各々適切な倍率で観察され、結晶性酸化物であるか否かの区別や結晶性酸化物の同定は、電子線回折およびエネルギー分散型エックス線分析を用いることにより行うことができる。また、前記結晶性酸化物粒子の観察は、粒子径Ｄが７０ｎｍ以上の粒子が少なくとも５０個以上の存在する単一もしくは複数の領域において行うことが好ましい。
【００３９】
前記酸化膜の厚さは、ハンターホール法（M.S.Hunter and P.Fowle,J.Electrochem.Soc.,101[9],483(1954)参照）による測定値で２．５〜５ｎｍが好ましい。膜厚が上記範囲の場合は、深いトンネル状のエッチピットが形成される。２．５ｎｍ未満ではエッチング初期にアルミニウム材の表面溶解が多く発生してトンネル状のエッチピットが形成されず、５ｎｍを越えると結晶性酸化物粒子がエッチピット核として作用しない恐れがある。
【００４０】
本発明に用いられるアルミニウム材の純度は電解コンデンサ用に使用される範囲内であれば特に限定されないが、過溶解を抑制してエッチング特性の低下を防止するために、純度９９．９質量％以上のものが好ましい。さらに好ましい純度は９９．９５質量％である。なお、本発明においてアルミニウム材の純度は１００質量％からＦｅ，Ｓｉ，Ｃｕ，Ｍｎ，Ｃｒ，Ｚｎ，ＴｉおよびＧａの合計濃度（質量％）を差し引いた値とする。
【００４１】
本発明の電解コンデンサ電極用アルミニウム材は、エッチング後の化成処理によって耐電圧性皮膜を形成させても大きい実効面積を有することから陽極材に適している。さらに、中圧用および高圧用電解コンデンサ電極材に適している。
【００４２】
この発明のアルミニウム材の製造に際し、アルミニウム材料の溶解・成分調整・スラブ鋳造、均熱処理、熱闘圧延、冷間圧延、中間焼鈍、仕上冷間圧延（低圧下圧延）、最終焼鈍は一般法に従えばよく、特に限定すべき工程の指定はない。アルミニウム材の（１００）面積率が９０％以上であることが好ましく、アルミニウム材のエッチング条件との関係で、アルミニウム材の製造工程条件は適宜変更される。
【００４３】
なお、圧延工程の途中において前工程の圧延により生じたアルミニウム材の結晶組織の歪みを解消する目的で焼鈍（以後中間焼鈍と称す。）されたものであっても良い。また、中間焼鈍以前の工程で表面の不純物や油分を除去する目的で洗浄を実施しても良い。
【００４４】
また、圧延工程を終了したアルミニウム材表面には油分や不純物が存在するため、焼鈍時に生成する結晶性酸化物粒子のアスぺクト比の均一性を高めるために洗浄を行いこれら油分や不純物を除去することが好ましい。
【００４５】
洗浄液は特に限定されるものではないが、有機溶剤、酸、アルカリ、界面活性剤を添加した水等を利用できる。
【００４６】
有機溶剤の例としては、アルコール、トルエン・キシレン等の芳香族炭化水素、ぺンタン・へキサン・脂肪族炭化水素、アセトン、ケトン、エステル等があげられ、特に限定されるものではなく複数の有機溶剤を混合して用いても良い。
【００４７】
酸の種類としては、塩酸、硫酸、リン酸、硝酸等の無機酸、シュウ酸、酢酸等の有機酸が例示でき、これら酸を少なくとも１種類以上含む水溶液を洗浄液として用いることができる。また、脱脂力を高めるために酸水溶液に界面活性剤を添加しても良い。
【００４８】
アルカリの種類としては、水酸化ナトリウム、水酸化カリウム、水酸化カルシウム、珪酸ナトリウム等を例示でき、少なくとも１種類以上のアルカリを含む水溶液を洗浄液として用いることができる。なおアルカリ洗浄後の酸洗浄等のように複数回浄液を実施しても良い。酸洗浄あるいはアルカリ洗浄後にアルミニウム表面に付着した洗浄液成分の残留物を除去する目的で水洗を行うことが好ましい。
【００４９】
アルミニウム表面に存在する結晶性酸化物粒子の数やアスペクト比を制御する方法の一つとして、接触加熱を例示することができる。
【００５０】
接触加熱の手段は熱ロール、加熱ベルト、加熱板などの加熱体をアルミニウム材表面に接触させる接触加熱であれば限定される物ではなく、複数の接触加熱手段を組み合わせても良い。また、箔の裏表同時に加熱しても良く、片面ずつ加熱しても良い。加熱体の加熱表面の材質はステンレス、メッキ、セラミックス、テフロン（登録商標）、シリコーン樹脂等自由に選択できるが、アルミニウム表層酸化膜が加熱表面に凝着しない物質が好ましい。
【００５１】
アルミニウムに接触させる加熱体の表面温度は５０〜４５０℃が好ましい。加熱体表面温度が５０℃未満であれば、焼鈍時の結晶性酸化物微粒子の数やアスぺクト比の制御が十分ではなく、４５０℃より高くなると酸化膜が厚くなりすぎ、加熱冷却時に皺が発生する等の操業上の問題が生じる恐れがあるからである。アルミニウム材表面が加熱体表面に接触する時間は０．００１〜６０秒が好ましい。接触時間が０．００１秒未満であるとアルミニウム表面を十分に加熱することが出来ず、６０秒より長く加熱すると酸化膜が厚くなりすぎエッチピットが発生しにくくなる可能性がある。
【００５２】
加熱体表面温度・接触時間は接触加熱前のアルミニウム表面酸化膜の特性を考慮して適宜選択されるものとする。接触加熱雰囲気は特に限定されず、特別な雰囲気制御も必要なく空気中でも十分である。
【００５３】
洗浄または洗浄後の接触加熱後、アルミニウム材の結晶組織の方位を（１００）方位に整えてエッチング特性を向上させることを主目的とし最終焼鈍がなされる。
【００５４】
この最終焼鈍における処理雰囲気は特に限定されるものではないが、酸化膜の厚さを増大させすぎないように、水分および酸素の少ない非酸化雰囲気中で加熱するのが好ましい。具体的には、アルゴン、窒素等の不活性ガス中あるいは０．１Ｐａ以下の真空中で加熱することが好ましい。
【００５５】
最終焼鈍の方法は特に限定されるものではなく、コイルに巻き取った状態でバッチ焼鈍しても良く、コイルを巻き戻しながら連続焼鈍した後コイルに巻き取っても良く、バッチ焼鈍と連続焼鈍の少なくともどちらかを複数回行っても良い。
【００５６】
最終焼鈍時の保持温度、時間は特に限定されるものではないが、たとえばコイルの状態でバッチ焼鈍を行なう場合は、アルミニウム実体温度４５０〜６００℃にて、１０分〜５０時間、さらに４５０〜５８０℃にて焼鈍するのが好ましい。また、昇温速度・パターンは特に限定されず、一定速度で昇温させてもよく、昇温、温度保持を繰り返しながらステップ昇温・冷却させてもよい。
【００５７】
アルミニウム実体温度が４５０℃未満、時間が１０分未満では酸化膜中のエッチピットの核と成り得る結晶性酸化物粒子の生成が十分ではなく、その分散状態が疎となりすぎて、結晶をエッチング核とするエッチング時の拡面効果が期待できない恐れがあり、（１００）面の結晶方位の発達も不十分であるからである。逆に６００℃を越える高温で焼鈍すると、コイルでバッチ焼鈍する場合はアルミニウム材が密着を起こし易くなり、５０時間を超えて焼鈍してもエッチング表面積拡大効果は飽和し、却って熱エネルギーコストの増大を招く。
【００５８】
前記最終焼鈍により、アルミニウム材表層酸化膜の厚さは、上述したハンターホール法による測定値で２．５〜５ｎｍとなされるとともに、（１００）面積率が９０％以上となされる。
【００５９】
本発明のエッチングされた電解コンデンサ用電極材は、上述した電解コンデンサ電極用アルミニウム材にエッチング処理を施して実効面積を拡大させたものである。エッチング処理によって、表層の酸化膜に存在する結晶性酸化物粒子がエッチピット核となり、多数のエッチピットが生成される。エッチング処理条件は特に限定されないが、トンネル状ピットが生成される直流エッチングを用いるのが良い。
【００６０】
エッチングされたアルミニウム材は、さらに化成処理を行って陽極材とすることができ、特に中圧および高圧用電解コンデンサ陽極材に適している。
【００６１】
本発明の電解コンデンサは、電極材料として上述のエッチングされた電解コンデンサ用電極材が用いられたものである。電極材料の実効面積の拡大により高い静電容量が得られる。
【００６２】
【実施例】
以下に本発明の実施例および比較例を示す。なお、本発明は実施例に限定されない。
【００６３】
アルミニウム基材として、９９．９９質量％のアルミニウム材料を常法により１１０μｍに圧延したアルミニウム箔を使用した。
（実施例１）
アルミニウム基材をｎ−へキサンで洗浄した後、表面温度を２００℃に設定した２枚のステンレス製加熱板の間に挟んで大気中で５秒間接触加熱を行った。接触加熱後のアルミニウム基材を重ねた状態で、アルゴン雰囲気中においてアルミニウム基材の実体温度を室温から５５０℃まで５０℃／ｈで昇温させた後、５５０℃にて２４時間保持し、次いで冷却した後炉だしし、電解コンデンサ電極用アルミニウム材を得た。
（実施例２）
アルミニウム基材をｎ−へキサンで洗浄した後、表面温度を２５０℃に設定した２枚のステンレス製加熱板の間に挟んで大気中で２秒間接触加熱を行った。接触加熱後のアルミニウム基材を重ねた状態で、アルゴン雰囲気中においてアルミニウム基材の実体温度を室温から５５０℃まで５０℃／ｈで昇温させた後、５５０℃にて２４時間保持し、次いで冷却した後炉だしし、電解コンデンサ電極用アルミニウム材を得た。
（実施例３）
アルミニウム基材をｎ−へキサンで洗浄した後、表面温度を２００℃に設定した２枚のステンレス製加熱板の間に挟んで大気中で５秒間接触加熱を行った。接触加熱後のアルミニウム基材を重ねた状態で、アルゴン雰囲気中においてアルミニラム基材の実体温度を室温から５４０℃まで５０℃／ｈで昇温させた後、５４０℃にて２４時間保持し、次いで冷却した後炉だしし、電解コンデンサ電極用アルミニウム材を得た。
（実施例４〜１５）
アルミニウム基材をｎ−へキサンで洗浄した後、加熱時間および温度を変化させて接触加熱を行った。接触加熱後のアルミニウム基材を重ねた状態で焼鈍温度と時間を変化させ焼鈍し電解コンデンサ電極用アルミニウム材を得た。
（比較例１〜３）
アルミニウム基材をｎ−へキサンで洗浄した後、焼鈍温度と時間を変化させて焼鈍し、電解コンデンサ電極用アルミニウム材を得た。
【００６４】
各実施例および比較例で得られた電解コンデンサ電極用アルミニウム材の表層酸化膜について、酸化膜厚さ、粒子径Ｄが７０ｎｍ以上である結晶性酸化物粒子のアスぺクト比の幾何標準偏差、粒子径Ｄが７０ｎｍ以上の結晶性酸化物の密度、粒子径Ｄが８０〜１２００ｎｍの結晶性酸化物の密度を求めた。ここで、結晶性酸化物粒子径Ｄは、長径＝Ａ、短径＝ＢとしたときにＤ＝（Ａ＋Ｂ）／２で表わされるものとする。
【００６５】
酸化膜厚さは上述したハンターホール法により測定した。
【００６６】
結晶性酸化物粒子の粒子密度およびアスペクト比は、少なくとも５０個以上の粒子径Ｄ７０ｎｍ以上の結晶性酸化物粒子が存在する単一もしくは複数の視野を観察する（３０００〜６万倍で観察）ことにより求めた。また、結晶性酸化物粒子のアスぺクト比の幾何標準偏差σ_gは上述の（Ｆ１）（Ｆ２）式に基づいて求めた。なお、観察用サンプルは、電解コンデンサ電極用アルミニウム材の片面にカーボン蒸着膜を形成し、臭素−メタノール液に浸潰しアルミニウムを溶解させたものを用いた。
【００６７】
酸化膜厚さ、粒子径Ｄが７０ｎｍ以上である結晶性酸化物粒子のアスぺクト比の幾何標準偏差σ_g、粒子径Ｄが７０ｎｍ以上の結晶性酸化物粒子密度、粒子径Ｄが８０〜１２００ｎｍ以下の結晶性酸化物粒子密度、および粒子径Ｄが７０ｎｍ以上の結晶性酸化物粒子中の粒子径８０ｎｍ〜１２００ｎｍの結晶性酸化物粒子の比率（％）を表１に示す。
【００６８】
さらに、各実施例および比較例で得られた箔をＨＣｌ：１．０ｍｏｌ・ｄｍ^-3とＨ₂ＳＯ₄：３．５ｍｏｌ・ｄｍ^-3を含む液温７５℃の水溶液に浸潰した後、電流密度０．２Ａ／ｃｍ²で電解処理を施した。電解処理後の箔をさらに前記組成の塩酸−硫酸混合水溶液に９０℃にて３６０秒浸潰し、ピット径を太くしエッチド箔を得た。得られたエッチド箔を化成電圧２７０ＶにてＥＩＡＪ規格に従い化成処理し静電容量を測定した。測定した静電容量を、比較例１を１００とした時の相対値として表１に示す。
【００６９】
【表１】

【００７０】
上記のように、結晶性酸化物粒子のアスぺクト比の幾何標準偏差と粒子密度を制御することにより、エッチング特性を高めて静電容量を増大させ得ることを確認した。
【００７１】
【発明の効果】
以上説明したように、本発明の電解コンデンサ電極用アルミニウム材は、表層酸化膜において、粒子径Ｄが７０ｎｍ以上の結晶性酸化物粒子のアスペクト比が幾何標準偏差σ_g：２以下となされた均一性の高いものであり、かつ粒子密度が１×１０⁴〜１×１０⁷個／ｍｍ²となされているから、エッチングによって結晶性酸化物粒子を核とする深いトンネル状のエッチピットが多数かつ均一に生成される。このため、実効面積が拡大され、ひいては静電容量を増大できる。
【００７２】
前記電解コンデンサ電極用アルミニウム材において、アスぺクト比の幾何標準偏差σ_gが１．６以下である場合は、特にエッチピットが均一に生成される。
【００７３】
また、粒子径Ｄが７０ｎｍ以上の結晶性酸化物粒子のうち、７０〜ｌ００％の粒子の粒子径Ｄが８０〜１２００ｎｍである場合は、エッチピット核になりやすく、かつエッチピットの結合が少ないために、実効面積の拡大効果が大きい。さらに、粒子径Ｄが８０〜１２００ｎｍの結晶性酸化物粒子の密度が１×１０⁵〜５×１０⁶個／ｍｍ²である場合は、確実に実効面積を拡大することができる。
【００７４】
また、酸化膜の厚さが、ハンターホール法による測定値で２．５〜５ｎｍである場合は、深いトンネル状のエッチピットが形成される。
【００７５】
また、アルミニウム材におけるＡｌ純度が９９．９質量％以上である場合は、過溶解を抑制してエッチング特性の低下を防止することができる。
【００７６】
前記電解コンデンサ電極用アルミニウム材が陽極材として用いられる場合は、実効面積の拡大により高い静電容量を得ることができる。
【００７７】
本発明の電解コンデンサ用電極材は、上述した何れかの電解コンデンサ電極用アルミニウム材において、エッチピットが形成されてなるものであるから、多数の深いトンネル状ピットが形成されて静電容量の増大をなし得るものである。
【００７８】
また、エッチングが直流エッチングによってなされた場合は、トンネル状ピットが生成された電解コンデンサ用電極材となし得る。
【００７９】
本発明の電解コンデンサは、電極材料として、上記電解コンデンサ用電極材が用いられてなるものであるから、電極材料の実効面積の拡大により高い静電容量が得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aluminum material for electrolytic capacitor electrodes, an etched aluminum material for electrolytic capacitor electrodes, and an electrolytic capacitor.
[0002]
In this specification, the term “aluminum” is used to include alloys thereof, and aluminum materials include foils and plates and molded bodies using these.
[0003]
[Prior art]
An aluminum material generally used as an electrode material for an aluminum electrolytic capacitor is subjected to electrochemical or chemical etching treatment to increase the effective area of the aluminum foil for the purpose of increasing the capacitance.
[0004]
In the production of aluminum materials for electrolytic capacitor anodes that generate tunnel-like pits by direct current etching, the final annealing is usually performed in an inert atmosphere or vacuum at a temperature of around 500 ° C. in order to develop the crystal orientation of the (100) plane. It is common. The final annealing is performed in a later process than the cold rolling for adjusting the final foil thickness.
[0005]
Crystalline oxide particles generated on the aluminum surface during this final annealing are known to be the core of etch pits, and controlling the density and crystallinity of the crystalline oxide particles is thought to lead to an increase in capacitance. (For example, refer nonpatent literature 1).
[0006]
The above-mentioned document states that the formation of pits with a crystalline oxide as a nucleus is considered to suggest that many cracks exist in the periphery of the crystal.
[0007]
Generally, in the production of an aluminum material for electrolytic capacitors, the final annealing is performed in an inert gas atmosphere or a vacuum atmosphere, and therefore the surface layer oxide film other than the crystalline oxide is amorphous. The crystalline oxide has a higher density than the amorphous oxide film, and the crystal density varies depending on the crystal form.
[0008]
The crystalline oxide particles formed on the aluminum surface layer have various shapes such as a spherical shape, a plate shape, and a needle shape depending on the manufacturing conditions, and the size of defects at the interface between the crystal and the amorphous oxide film varies depending on the shape of the crystal. Therefore, it is important to control the shape of the crystalline oxide particles in order to make the crystalline oxide particles act effectively as etch pit nuclei, and various proposals have been made regarding oxide films or crystalline oxide particles. (For example, refer to Patent Documents 1 to 3).
[0009]
Patent Document 1 proposes an aluminum material for electrolytic capacitors in which γ-alumina crystals are generated on the surface of an aluminum foil.
[0010]
Patent Document 2 discloses that the surface potential of an amorphous oxide film is uniform in location, and therefore etch pits corresponding to the electrolysis conditions are formed, and the crystallization rate of the oxide film is 1% or less. It is prescribed.
[0011]
Patent Document 3 proposes an aluminum foil for electrolytic capacitors in which crystals having an average particle diameter of 0.05 to 0.5 μm occupy 3 to 50% in area ratio.
[0012]
[Non-Patent Document 1]
Nobuo Osawa, Kiyoshi Fukuoka, “Effect of Crystalline Oxide on DC Etching Behavior of Aluminum Foil for Electrolytic Capacitors”, Surface Technology, 1999, Vol. 50, No. 7, p. 643-647
[0013]
[Patent Document 1]
Japanese Patent Laid-Open No. 63-116417
[Patent Document 2]
JP-A-8-222488
[Patent Document 3]
JP-A-8-222487
[Problems to be solved by the invention]
However, Patent Document 1 does not describe the particle density and shape of γ-alumina crystals.
[0017]
In Patent Document 2, uniform pit formation is achieved by suppressing the crystallization rate (occupation ratio of the crystalline film in the oxide film), and the crystalline oxide is not effectively used as an etch pit nucleus. Moreover, there is no provision regarding the density and shape of the crystalline oxide particles, and the effective area is not sufficiently expanded.
[0018]
Although Patent Document 3 defines the particle diameter, particle density, and area ratio of the crystalline oxide, there is no description regarding the shape of the crystal.
[0019]
As described above, in the conventional technique, the shape of the crystalline oxide particles present in the aluminum surface layer oxide film is not studied, and there is a problem that the effective area is not sufficiently expanded by etching.
[0020]
The present invention solves the above-mentioned problems of the prior art, and provides an electrolytic capacitor electrode aluminum material, an etched electrolytic capacitor electrode material, and an electrolytic capacitor that can increase the effective area by etching. Objective.
[0021]
[Means for Solving the Problems]
The above problems are present in the surface oxide film of the aluminum material for electrodes for electrolytic capacitors, and the variation in the aspect ratio of the crystalline oxide particles that effectively act as etch pit nuclei is reduced, and the particle density is made appropriate. Is solved.
[0022]
That is, the aluminum material for electrolytic capacitor electrodes of the present invention has the following configuration.
(1) Regarding a crystalline oxide particle having a particle diameter D defined by D = (A + B) / 2 of 70 nm or more when a major axis = A and a minor axis = B in a surface oxide film of an aluminum material, (F1 ) The geometric standard deviation σ _{g of the} aspect ratio of the particles calculated by the formula (F2) using the geometric average aspect ratio Mg shown by the formula is 2 or less, and the density is 1 × 10 ⁴ to 1 × 10 ⁷ pieces / mm ² An aluminum material for electrolytic capacitor electrodes.
[0023]
[Equation 3]

[0024]
Here, Cj (j = 1, 2, 3,... N) is an aspect ratio of the crystalline oxide particles, and circumscribes the outer periphery of the crystalline oxide particles observed with a transmission electron microscope. In the rectangular shape with the smallest area, when the rectangular shape is a rectangle, C ′ = A ′ / B ′ when the long side of the rectangle is A ′ and B ′ as the short side, and Cj = 1 when the rectangular shape is a square. To do.
[0025]
[Expression 4]

[0026]
(2) The aluminum material for electrolytic capacitor electrodes as recited in the aforementioned Item 1, wherein the geometric standard deviation σ _{g of the} aspect ratio is 1.6 or less.
(3) The aluminum material for electrolytic condenser electrodes according to the preceding item 1 or 2, wherein the particle size D of 70 to 100% of the crystalline oxide particles having a particle size D of 70 nm or more is 80 to 1200 nm.
(4) The aluminum material for electrolytic roncer electrodes according to item 3 above, wherein the density of crystalline oxide particles having a particle diameter D of 80 to 1200 nm is 1 × 10 ^{5 to} 5 × 10 ⁶ particles / mm ² .
(5) The aluminum material for electrolytic capacitor electrodes as described in any one of 1 to 4 above, wherein the thickness of the oxide film is 2.5 to 5 nm as measured by the Hunter Hall method.
(6) The aluminum material for electrolytic capacitor electrodes according to any one of the preceding items 1 to 5, wherein the Al purity in the aluminum material is 99.9% by mass or more.
(7) The aluminum material for electrolytic capacitor electrodes according to any one of the preceding items 1 to 6, wherein the aluminum material for electrolytic capacitor electrodes is an anode material.
[0027]
Moreover, the electrode material for electrolytic capacitors of the present invention has the following configuration.
(8) An electrolytic capacitor electrode material, wherein the electrolytic capacitor electrode aluminum material according to any one of (1) to (7) is etched.
(9) The electrode material for electrolytic capacitors as described in 8 above, wherein the etching is direct current etching.
[0028]
Furthermore, the electrolytic capacitor of the present invention has the following configuration.
(10) An electrolytic capacitor characterized in that the electrode material for an electrolytic capacitor described in (8) or (9) is used as an electrode material.
[0029]
The aluminum material for electrolytic capacitor electrodes of the present invention ensures the expansion of the effective area by etching by defining the aspect ratio and density of the crystalline oxide particles present in the surface oxide film.
[0030]
The crystalline oxide particles that are the subject of the present invention are particles having a particle diameter D defined by D = (A + B) / 2 of 70 nm or more when long side = A and short side = B. This is because particles having a particle diameter D of less than 70 nm are less likely to become etch pit nuclei.
[0031]
When all the aspect ratios of the crystalline oxide particles are the same, the geometric standard deviation σ _g calculated by the formulas (F1) and (F2) is 1, and the geometric ratio increases as the distribution range of the aspect ratio increases. The standard deviation σ _g increases. Therefore, the smaller the geometric standard deviation σ _g is, the narrower the aspect ratio distribution range is, and the better the aspect ratio uniformity is. Since the etch pits are uniformly generated as the aspect ratio is uniform, the geometric standard deviation σ _g of the crystalline oxide particles is further set to l. The geometric standard deviation σ _g is preferably 1.4 or less.
[0032]
Further, the particle diameter D defines the density of the crystalline oxide particles of more than 70 nm 1 × 10 ⁴ to 1 × 10 ⁷ cells / mm ² and, if the density is less than 1 × 10 ⁴ cells / mm ² crystalline oxide particles become etch pit nuclei is too small, whereas when the density is higher than 1 × 10 ⁷ cells / mm ² by the etch pits generated the crystalline oxide particles as nuclei are bound, in either case This is because the effective area cannot be effectively increased.
[0033]
In order to further increase the effective area, it is preferable that the particle diameter D of 70 to 100% of the crystalline oxide fine particles having a particle diameter D of 70 nm or more is 80 to 1200 nm. This is because, compared with crystalline oxide fine particles having a particle diameter D of less than 80 nm, it is particularly easy to become etch pit nuclei, and there are fewer bonds of adjacent etch pits than crystalline oxide fine particles having a particle diameter D exceeding 1200 nm.
[0034]
Furthermore, the density of particles having a particle diameter D of 80 to 1200 nm is preferably 1 × 10 ^{5 to} 5 × 10 ⁶ particles / mm ² , and the effective area can be reliably expanded by etching.
[0035]
In the present invention, the thickness of the aluminum material for electrolytic capacitor electrodes is not particularly specified. The present invention includes not only foils having a thickness of 200 μm or less, which are called foils, but also plates having a thickness greater than that, and molded bodies using these.
[0036]
The aluminum material for electrolytic capacitor electrodes of the present invention has a high uniformity of the aspect ratio of the crystalline oxide particles present in the surface oxide film and an appropriate particle density. A large number of etch pits with particles as nuclei are generated uniformly. For this reason, an effective area is expanded and an electrostatic capacitance increases.
[0037]
The crystalline oxide for Al ₂ O ₃ types of particles including the γ-Al ₂ O _3, including boehmite AlOOH, oxides containing metal other than aluminum (for example Mg, Pb, Cu, etc.) There is no particular limitation as long as it is a composite metal oxide or hydroxide of hydroxide, aluminum and a metal contained other than aluminum (for example, Mg, Pb, Cu, etc.), either single crystal or polycrystal good. Further, a single crystal or a plurality of crystals may be covered with an amorphous material to form one particle, and an amorphous oxide may exist between aggregated oxide crystals. The crystalline oxide present on the surface of the aluminum material for electrolytic capacitors was prepared by forming a deposited film such as carbon as a support film on one side of the aluminum material and then dissolving the aluminum by immersing it in a bromine-methanol solution, for example. This can be confirmed by observing the sample with a transmission electron microscope. In addition to bromine-methanol solution, a solution of mercuric chloride, iodine-methanol solution, or the like can be used as the solution used for dissolving aluminum during the preparation of the transmission electron microscope observation sample.
[0038]
Crystalline oxide particles present in the transmission electron microscope observation region are each observed at an appropriate magnification. Whether or not it is a crystalline oxide or identification of the crystalline oxide is determined by electron diffraction and energy dispersion. This can be done by using type X-ray analysis. The crystalline oxide particles are preferably observed in a single region or a plurality of regions where at least 50 particles having a particle diameter D of 70 nm or more are present.
[0039]
The thickness of the oxide film is preferably 2.5 to 5 nm as measured by the Hunter Hall method (see MSHunter and P. Fowl, J. Electrochem. Soc., 101 [9], 483 (1954)). When the film thickness is in the above range, deep tunnel-like etch pits are formed. If the thickness is less than 2.5 nm, the surface of the aluminum material is often dissolved in the initial stage of etching, and tunnel-like etch pits are not formed. If the thickness exceeds 5 nm, the crystalline oxide particles may not act as etch pit nuclei.
[0040]
The purity of the aluminum material used in the present invention is not particularly limited as long as it is within the range used for an electrolytic capacitor. However, in order to suppress overmelting and prevent deterioration of etching characteristics, the purity is 99.9% by mass or more. Are preferred. A more preferred purity is 99.95% by mass. In the present invention, the purity of the aluminum material is a value obtained by subtracting the total concentration (mass%) of Fe, Si, Cu, Mn, Cr, Zn, Ti and Ga from 100 mass%.
[0041]
The aluminum material for electrolytic capacitor electrodes of the present invention is suitable as an anode material because it has a large effective area even when a voltage-resistant film is formed by chemical conversion after etching. Furthermore, it is suitable for medium pressure and high pressure electrolytic capacitor electrode materials.
[0042]
When manufacturing the aluminum material of this invention, melting, component adjustment, slab casting of aluminum material, soaking, hot-rolling, cold rolling, intermediate annealing, finish cold rolling (low pressure rolling), and final annealing are in accordance with general methods. There is no designation of a process that should be particularly limited. The (100) area ratio of the aluminum material is preferably 90% or more, and the manufacturing process conditions of the aluminum material are appropriately changed in relation to the etching conditions of the aluminum material.
[0043]
It may be annealed (hereinafter referred to as intermediate annealing) for the purpose of eliminating the distortion of the crystal structure of the aluminum material produced by rolling in the previous process during the rolling process. Moreover, you may implement washing | cleaning in order to remove surface impurities and oil in the process before intermediate annealing.
[0044]
In addition, since oil and impurities exist on the surface of the aluminum material after the rolling process, the oil and impurities are removed by washing to improve the uniformity of the aspect ratio of the crystalline oxide particles generated during annealing. It is preferable to do.
[0045]
Although the cleaning liquid is not particularly limited, an organic solvent, an acid, an alkali, water to which a surfactant is added, or the like can be used.
[0046]
Examples of organic solvents include alcohols, aromatic hydrocarbons such as toluene / xylene, pentane / hexane / aliphatic hydrocarbons, acetone, ketones, esters, and the like. You may mix and use a solvent.
[0047]
Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, and organic acids such as oxalic acid and acetic acid, and an aqueous solution containing at least one of these acids can be used as a cleaning liquid. Further, a surfactant may be added to the acid aqueous solution in order to increase the degreasing power.
[0048]
Examples of the alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium silicate and the like, and an aqueous solution containing at least one alkali can be used as the cleaning liquid. In addition, you may implement a cleaning liquid in multiple times like the acid cleaning after alkali cleaning. It is preferable to perform water washing for the purpose of removing the residue of the cleaning liquid component adhering to the aluminum surface after acid cleaning or alkali cleaning.
[0049]
One method for controlling the number and aspect ratio of the crystalline oxide particles present on the aluminum surface is contact heating.
[0050]
The contact heating means is not limited as long as it is contact heating in which a heating body such as a heat roll, a heating belt, or a heating plate is brought into contact with the surface of the aluminum material, and a plurality of contact heating means may be combined. Moreover, the front and back of the foil may be heated simultaneously, or one side may be heated. The material of the heating surface of the heating body can be freely selected from stainless steel, plating, ceramics, Teflon (registered trademark), silicone resin, etc., but a substance in which the aluminum surface oxide film does not adhere to the heating surface is preferable.
[0051]
As for the surface temperature of the heating body made to contact aluminum, 50-450 degreeC is preferable. If the surface temperature of the heating body is less than 50 ° C., the number of crystalline oxide fine particles and the aspect ratio are not sufficiently controlled during annealing, and if the temperature exceeds 450 ° C., the oxide film becomes too thick. This is because there is a risk that operational problems such as the occurrence of a problem will occur. The time for which the aluminum material surface is in contact with the heated body surface is preferably 0.001 to 60 seconds. If the contact time is less than 0.001 seconds, the aluminum surface cannot be heated sufficiently, and if the contact time is longer than 60 seconds, the oxide film becomes too thick and etch pits may not easily occur.
[0052]
The heating body surface temperature and contact time are appropriately selected in consideration of the characteristics of the aluminum surface oxide film before contact heating. The contact heating atmosphere is not particularly limited, and no special atmosphere control is necessary, and it is sufficient even in the air.
[0053]
After the cleaning or the contact heating after the cleaning, final annealing is performed mainly for the purpose of improving the etching characteristics by adjusting the orientation of the crystal structure of the aluminum material to the (100) orientation.
[0054]
The processing atmosphere in the final annealing is not particularly limited, but it is preferable to heat in a non-oxidizing atmosphere with less moisture and oxygen so as not to increase the thickness of the oxide film. Specifically, it is preferable to heat in an inert gas such as argon or nitrogen or in a vacuum of 0.1 Pa or less.
[0055]
The method of final annealing is not particularly limited, and batch annealing may be performed in a state of being wound around the coil, and continuous annealing may be performed while rewinding the coil, and winding may be performed on the coil. At least one of them may be performed a plurality of times.
[0056]
The holding temperature and time during the final annealing are not particularly limited. For example, when batch annealing is performed in the state of a coil, the aluminum body temperature is 450 to 600 ° C., 10 minutes to 50 hours, and further 450 to 580. It is preferable to anneal at 0 ° C. Further, the temperature raising rate / pattern is not particularly limited, and the temperature may be raised at a constant rate, or the step temperature raising / cooling may be performed while repeating the temperature raising and temperature holding.
[0057]
If the aluminum body temperature is less than 450 ° C. and the time is less than 10 minutes, the generation of crystalline oxide particles that can be the nucleus of etch pits in the oxide film is not sufficient, and the dispersion state becomes too sparse, and the crystal is etched This is because the surface expansion effect during etching may not be expected, and the crystal orientation of the (100) plane is not sufficiently developed. Conversely, if annealing is performed at a high temperature exceeding 600 ° C., the aluminum material tends to adhere when batch annealing is performed with a coil, and the effect of expanding the etching surface area is saturated even if annealing is performed for more than 50 hours, and the heat energy cost is increased. Invite.
[0058]
By the final annealing, the thickness of the aluminum surface oxide film is 2.5 to 5 nm as measured by the Hunter Hall method described above, and the (100) area ratio is 90% or more.
[0059]
The etched electrolytic capacitor electrode material of the present invention is obtained by etching the above-described electrolytic capacitor electrode aluminum material to increase the effective area. By the etching process, the crystalline oxide particles present in the surface oxide film become etch pit nuclei, and a large number of etch pits are generated. Although the etching process conditions are not particularly limited, it is preferable to use direct current etching that generates tunnel-like pits.
[0060]
The etched aluminum material can be further subjected to a chemical conversion treatment to be an anode material, and is particularly suitable for an electrolytic capacitor anode material for medium pressure and high pressure.
[0061]
The electrolytic capacitor of the present invention uses the above-described etched electrode material for an electrolytic capacitor as an electrode material. High capacitance can be obtained by expanding the effective area of the electrode material.
[0062]
【Example】
Examples of the present invention and comparative examples are shown below. In addition, this invention is not limited to an Example.
[0063]
As the aluminum base, an aluminum foil obtained by rolling 99.99% by mass of an aluminum material to 110 μm by a conventional method was used.
(Example 1)
After washing the aluminum substrate with n-hexane, contact heating was performed in the atmosphere for 5 seconds, sandwiched between two stainless steel heating plates whose surface temperature was set to 200 ° C. With the aluminum base material after contact heating being stacked, the solid temperature of the aluminum base material was raised from room temperature to 550 ° C. at 50 ° C./h in an argon atmosphere, then held at 550 ° C. for 24 hours, and then After cooling, a furnace was started to obtain an aluminum material for electrolytic capacitor electrodes.
(Example 2)
After the aluminum substrate was washed with n-hexane, contact heating was performed in the air for 2 seconds by sandwiching it between two stainless steel heating plates whose surface temperature was set to 250 ° C. With the aluminum base material after contact heating being stacked, the solid temperature of the aluminum base material was raised from room temperature to 550 ° C. at 50 ° C./h in an argon atmosphere, then held at 550 ° C. for 24 hours, and then After cooling, a furnace was started to obtain an aluminum material for electrolytic capacitor electrodes.
(Example 3)
After washing the aluminum substrate with n-hexane, contact heating was performed in the atmosphere for 5 seconds, sandwiched between two stainless steel heating plates whose surface temperature was set to 200 ° C. With the aluminum substrate after contact heating being stacked, the actual temperature of the aluminum nilam substrate was raised from room temperature to 540 ° C. at 50 ° C./h in an argon atmosphere, then held at 540 ° C. for 24 hours, and then After cooling, a furnace was started to obtain an aluminum material for electrolytic capacitor electrodes.
(Examples 4 to 15)
After the aluminum substrate was washed with n-hexane, contact heating was performed while changing the heating time and temperature. The aluminum base material for electrolytic capacitor electrodes was obtained by changing the annealing temperature and time while the aluminum base material after contact heating was stacked.
(Comparative Examples 1-3)
The aluminum substrate was washed with n-hexane, and then annealed while changing the annealing temperature and time to obtain an aluminum material for electrolytic capacitor electrodes.
[0064]
For the surface oxide film of the aluminum material for electrolytic capacitor electrodes obtained in each example and comparative example, the oxide film thickness, the geometric standard deviation of the aspect ratio of the crystalline oxide particles having a particle diameter D of 70 nm or more, The density of a crystalline oxide having a particle diameter D of 70 nm or more and the density of a crystalline oxide having a particle diameter D of 80 to 1200 nm were determined. Here, the crystalline oxide particle diameter D is represented by D = (A + B) / 2 when the major axis = A and the minor axis = B.
[0065]
The oxide film thickness was measured by the Hunter Hall method described above.
[0066]
The particle density and aspect ratio of the crystalline oxide particles are such that at least 50 or more fields of crystalline oxide particles having a particle diameter D of 70 nm or more are observed (observed at 3000 to 60,000 times). Determined by Further, the geometric standard deviation σ _g of the aspect ratio of the crystalline oxide particles was determined based on the above-described formulas (F1) and (F2). In addition, the sample for observation used what formed the carbon vapor deposition film | membrane on the single side | surface of the aluminum material for electrolytic capacitor electrodes, was immersed in bromine-methanol liquid, and dissolved aluminum.
[0067]
Oxide film thickness, geometric standard deviation σ _{g of} aspect ratio of crystalline oxide particles having a particle diameter D of 70 nm or more, density of crystalline oxide particles having a particle diameter D of 70 nm or more, particle diameter D of 80 to Table 1 shows the crystalline oxide particle density of 1200 nm or less and the ratio (%) of the crystalline oxide particles having a particle diameter of 80 nm to 1200 nm in the crystalline oxide particles having a particle diameter D of 70 nm or more.
[0068]
Furthermore, the foil obtained in Examples and Comparative Examples HCl: After crushing immersed in an aqueous solution of a liquid temperature 75 ° C. containing ^{3.5mol · dm -3,: 1.0mol ·} dm -3 and H ₂ SO ₄ Electrolytic treatment was performed at a current density of 0.2 A / cm ² . The foil after electrolytic treatment was further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having the above composition at 90 ° C. for 360 seconds to increase the pit diameter to obtain an etched foil. The obtained etched foil was subjected to chemical conversion treatment at a chemical conversion voltage of 270 V in accordance with EIAJ standards, and the capacitance was measured. The measured capacitance is shown in Table 1 as a relative value when Comparative Example 1 is 100.
[0069]
[Table 1]

[0070]
As described above, it was confirmed that by controlling the geometric standard deviation of the aspect ratio of the crystalline oxide particles and the particle density, the etching characteristics can be enhanced and the capacitance can be increased.
[0071]
【The invention's effect】
As described above, the aluminum material for electrolytic capacitor electrodes of the present invention has a uniform surface ratio oxide film in which the aspect ratio of crystalline oxide particles having a particle diameter D of 70 nm or more is a geometric standard deviation σ _g : 2 or less. In addition, since the particle density is 1 × 10 ⁴ to 1 × 10 ⁷ particles / mm ² , a large number of deep tunnel-like etch pits having crystalline oxide particles as a nucleus are obtained by etching. Uniformly generated. For this reason, an effective area is expanded, and an electrostatic capacitance can be increased by extension.
[0072]
In the aluminum material for electrolytic capacitor electrodes, particularly when the geometric standard deviation σ _g of the aspect ratio is 1.6 or less, etch pits are generated uniformly.
[0073]
Further, among the crystalline oxide particles having a particle diameter D of 70 nm or more, when the particle diameter D of the 70 to 100% particle is 80 to 1200 nm, it tends to become an etch pit nucleus and has few etch pit bonds. For this reason, the effect of expanding the effective area is great. Furthermore, if the particle diameter D is the density of the crystalline oxide particles 80~1200nm is 1 × 10 ⁵ ~5 × 10 ⁶ cells / mm ^2, it is possible to reliably enlarge the effective area.
[0074]
When the thickness of the oxide film is 2.5 to 5 nm as measured by the Hunter hole method, deep tunnel-like etch pits are formed.
[0075]
Moreover, when the Al purity in an aluminum material is 99.9 mass% or more, it can suppress overmelting and can prevent the fall of an etching characteristic.
[0076]
When the aluminum material for electrolytic capacitor electrodes is used as an anode material, a high capacitance can be obtained by expanding the effective area.
[0077]
Since the electrolytic capacitor electrode material of the present invention is formed by forming etch pits in any of the above-described electrolytic capacitor electrode aluminum materials, a large number of deep tunnel pits are formed, thereby increasing the capacitance. It can be done.
[0078]
Further, when the etching is performed by direct current etching, it can be formed as an electrode material for an electrolytic capacitor in which tunnel-like pits are generated.
[0079]
Since the electrolytic capacitor of the present invention uses the electrode material for electrolytic capacitors as an electrode material, a high capacitance can be obtained by expanding the effective area of the electrode material.

Claims (10)

In the surface oxide film of an aluminum material, when the major axis is A and the minor axis is B, D = (A + B) / 2 for crystalline oxide particles having a particle diameter D defined by 70 nm or more, The geometric standard deviation σ _{g of the} aspect ratio of the particles calculated by the formula (F2) using the geometric average aspect ratio Mg shown is 2 or less, and the density is 1 × 10 ⁴ to 1 × 10 ^7. An aluminum material for electrolytic capacitor electrodes, characterized in that the number is 1 / mm ² .

Here, Cj (j = 1, 2, 3,... N) is an aspect ratio of the crystalline oxide particles, and circumscribes the outer periphery of the crystalline oxide particles observed with a transmission electron microscope. In the rectangular shape with the smallest area, when the rectangular shape is a rectangle, C ′ = A ′ / B ′ when the long side of the rectangle is A ′ and B ′ as the short side, and Cj = 1 when the rectangular shape is a square. To do.

The aluminum material for electrolytic capacitor electrodes according to claim 1, wherein the geometric standard deviation σ _{g of the} aspect ratio is 1.6 or less. The aluminum material for electrolytic condenser electrodes according to claim 1 or 2, wherein the particle diameter D of 70 to 100% of the crystalline oxide particles having a particle diameter D of 70 nm or more is 80 to 1200 nm. 4. The aluminum material for electrolytic londensa electrodes according to claim 3, wherein the density of the crystalline oxide particles having a particle diameter D of 80 to 1200 nm is 1 × 10 ^{5 to} 5 × 10 ⁶ particles / mm ² . The aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 4, wherein the thickness of the oxide film is 2.5 to 5 nm as measured by a Hunter Hall method. The aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 5, wherein the aluminum material has an Al purity of 99.9% by mass or more. The aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 6, wherein the aluminum material for electrolytic capacitor electrodes is an anode material. An electrolytic capacitor electrode material according to any one of claims 1 to 7, wherein the electrolytic capacitor electrode aluminum material is etched. The electrode material for electrolytic capacitors according to claim 8, wherein the etching is direct current etching. An electrolytic capacitor, wherein the electrode material for an electrolytic capacitor according to claim 8 or 9 is used as the electrode material.