JP4110353B2 - Aluminum alloy base plate for lithographic printing plate and method for producing the same - Google Patents

Description

【００４６】
＜熱間圧延＞
次に、上記の鋳塊に、温度５００℃で２時間保持の均質化処理を行った後、同じ炉内で熱間圧延開始温度３９０℃に下げ１時間保持した。ワークロール径９００mmφの可逆式熱間圧延機を用い、圧延パス数１５回、各パス間時間１０秒〜１．５分の条件で熱間圧延を行い、厚さ６mmの熱間圧延板を得た。ここで、熱間圧延の最終パスは、１８mm厚さから６mm厚さへの圧下（圧下率６７％）、最終パス開始温度３６０℃で行い、３５０℃で熱間圧延を終了した。最終パスの圧延速度を１００ｍ／分とした。圧延時間は０．０４４秒であり、歪み（対数歪み）は１．１０、歪み速度ｖは２５．０ sec^-1であった。
【００４７】
＜冷間圧延＞
次に、室温（４０℃）の熱間圧延板を冷間圧延した。冷間圧延速度を５００〜２０００ｍ／分とした。ただし、板厚さが薄くなるに従い圧延速度を速くした。冷間圧延の方式は、各パス後に冷間圧延板を巻き取ってコイルとし、次パスに供する方式とした。
冷間圧延第一パスは、板厚さ６mm→３mmで行った。圧延終了温度は、９０℃であった。直ちに、冷間圧延第二パスを板厚さ３mm→１mmで行った。圧延終了温度は１５０℃であった。引続き、１１０℃まで冷却速度１０℃／分で急速冷却を行った。急速冷却は、コイルを槽内に置き油性の冷媒液を噴霧して冷却した。そして、冷間圧延第三パスを板厚さ１mm→０．５mmで行った。圧延終了温度は、１５０℃であった。直ちに、冷間圧延第四パスを０．５mm→０．２４mmで行った。圧延終了温度は１２０℃であった。冷間圧延の終了したコイルを、室温まで１０℃／分の冷却速度で急速冷却した。冷却方法は、冷間圧延第二パス後の急速冷却方法と同様に行った。その後、テンションレベラーによって矯正を行い、平版印刷版用アルミニウム合金素板を得た。
【００４８】
＜特性の評価＞
上記により得られた合金符号Ａ〜Ｊの本発明例および比較例の各アルミニウム合金素板について、下記(１）〜（１０）で説明する評価・測定法によって、（Ａ）熱間圧延板について、表面部の結晶粒幅（圧延方向に直角方向の結晶粒サイズ）および芯領域の結晶粒幅、（Ｂ）冷間圧延により得られたアルミニウム合金素板について、Ｆｅ、Ｃｕ、Ｚｒの各固溶量、単体Ｓｉ量および平均粒径０．５μｍ以上の単体Ｓｉの個数、表層領域の結晶粒幅および伸び率、芯領域の結晶粒幅、電解粗面化処理後の電解粗面化面の均一性、粗面化外観の均一性、引張強さ、バーニング処理後の耐力、インキ汚れ性を評価・測定した。結果を表２に示す。
【００４９】
（１）熱間圧延板の結晶粒サイズの測定
それぞれのアルミニウム合金の熱間圧延板を電解研磨等により、表面部および芯領域を露呈させ、バーカー氏液（１１ml／１ホウフッ酸溶液）による陽極酸化処理後、偏光顕微鏡によって、結晶粒観察を行った。直線法を用い結晶粒幅（圧延方向に対して直角方向のサイズ）を測定した。なお、偏光顕微鏡観察は４００倍で行い、写真上で長さ６０mm（実際の長さ１５０μｍ）の線分についての測定を１０箇所で行い、その平均値を用いた。結晶粒の大きなものは低倍率で観察を行った。
【００５０】
（２）Ｆｅ、Ｃｕ、Ｚｒの各固溶量の測定
アルミニウム合金素板を熱フェノールによって溶解し、溶解されたマトリックスと溶解残さとしての金属間化合物をろ過および、ろ過をくぐり抜けた微細な金属間化合物を１０％クエン酸溶液との抽出によって分離し、ろ液中の固溶された元素としてのＦｅ、Ｃｕ、Ｚｒの各量をＩＣＰ発光分析装置によって測定した。
【００５１】
（３）単体Ｓｉ量の測定
アルミニウム合金素板をＨＣｌ：Ｈ₂Ｏ₂＝１：１の溶液で溶解し、濾過残渣をＮａＯＨ溶液で分解し、中和し、モリブデン酸アンモニウムを加え、ケイモリブデン黄を生成させた。濃度が濃い場合には、スルホン酸還元液で還元し、モリブデン青を生成させ、その吸光度を測定し、検量線より換算し単体Ｓｉ量を求めた。
【００５２】
（４）粒径０．５μｍ以上の単体Ｓｉ個数の測定
アルミニウム合金支持体用素板を１％ＮａＯＨで非常にゆっくりと０．５μｍ深さエッチングし、次いでＸ線マイクロアナライザーでＦｅ、Ｓｉのマッピング分析を行った。この内Ｆｅと共存していないＳｉのみを画像解析装置（ニレコ（株）製ＬＵＺＥＸ Ｆ）を用い、該当粒子の占める面積を円換算しその直径を平均粒径とした。この円相当直径が０．５μｍ以上のものをカウントした。
なお、１％ＮａＯＨでエッチングした表面には、金属間化合物、単体Ｓｉが存在しており、Ｆｅ、Ｓｉマッピング分析で検出された粒子と、ＳＥＭ観察像が一致しており、エッチングによってこれらは残存していること、およびＸ線マイクロアナライザーでのＦｅ、Ｓｉのマッピング分析結果は、エッチングされた０．５μｍ深さ相当に存在するものであると考えられた。
【００５３】
（５）アルミニウム合金素板の結晶粒サイズの測定
アルミニウム合金素板を電解研磨等により、表面から１０μｍ深さの表層領域および表面から１２０μｍの芯領域を露呈させ、バーカー氏液（１１ml／１ホウフッ酸溶液）による陽極酸化処理後、偏光顕微鏡によって、結晶粒観察を行った。直線法を用い結晶粒幅（圧延方向に直角方向の結晶粒サイズ）、表層領域の結晶粒の伸び率（結晶粒幅に対する長さの比。長さ＝圧延方向の結晶粒サイズ）を測定した。なお、結晶粒幅については、偏光顕微鏡観察は４００倍で行い、写真上で長さ６０mm（実際の長さ１５０μｍ）の線分についての測定を１０箇所で行い、その平均値を用いた。結晶粒の大きなものは低倍率で観察を行った。結晶の伸び率については、偏光顕微鏡観察は１００倍で行い、任意の結晶粒５０個について幅と長さを測定し、その平均値を用いた。
基本的に、冷間圧延により得られた素板の結晶粒は、冷間圧延により伸されているのみであり、結晶粒幅は熱間圧延板の結晶粒幅と同等であった。更に、結晶粒の伸び率も熱間圧延板から冷間圧延された板の伸び率と同等であった。
【００５４】
（６）電解粗面化面の均一性の評価
アルミニウム合金素板をバミストン／水の懸濁液中でブラシグレイニングした後、アルカリエッチングおよびデスマット処理を施した。
次に、極性が交互に交換する電解波形をもつ電源を用いて、１％硝酸中で陽極時電気量が１５０クーロン／dm2 となる電解エッチングにより、電解粗面化を行った。
硫酸中で洗浄した後、走査型電子顕微鏡（ＳＥＭ）により表面を観察した。評価は、砂目均一なものは「良好（○）」、未エッチ部の多いものや砂目が不均一なものは「不良（×）」とした。
【００５５】
（７）電解粗面化面の外観の評価
アルミニウム合金素板をバミストン／水の懸濁液中でブラシグレイニングした後、アルカリエッチングおよびデスマット処理を施した。
次に、極性が交互に交換する電解波形をもつ電源を用いて、１％硝酸中で陽極時電気量が１５０クーロン／dm2 となる電解エッチングにより、電解粗面化を行った。
硫酸中で洗浄した後、硫酸中で陽極酸化皮膜を形成させてから、表面の目視観察により外観の均一性を評価した。評価は、外観が均一なものは「良好（○）」、外観が許容できる程均一でなく軽度なストリークス等が観察されたものは「やや不良（Δ）」、外観が均一でなくストリークス等が観察されたものは「不良（×）」とした。
【００５６】
（８）引張強さ測定
アルミニウム合金素板からＪＩＳ１３号Ｂ引張試験片を作製し、引張試験を行い、引張強さσ_Bを測定した。
【００５７】
（９）バーニング後の耐力の測定
アルミニウム合金素板を、２７０℃で７分間のバーニング処理をした後に、ＪＩＳ１３号Ｂ引張試験片を作製し、引張試験を行い、バーニング処理後の素板の耐力σ_0.2を測定した。
【００５８】
（１０）耐インキ汚れ性の評価
アルミニウム合金素板から印刷原版を作製し、オフセット印刷機ＫＯＲにセットし、１０万部印刷して非画像部のインキ汚れの有無を目視評価した。これによりインキ汚れの観察されなかったものを「良好（○）」、やや多く観察されたものを「やや不良（Δ）」、非常に多く観察されたものを「不良（×）」とした。
【００５９】
【表２】

【００６０】
表１および表２に示したように、本発明例である試料番号Ｉ−１〜Ｉ−６は、アルミニウム合金の化学成分が本発明の規定範囲内であること、本発明の規定範囲内の熱間圧延用加熱温度、熱間圧延条件、冷間圧延条件であることによって、アルミニウム合金素板のＦｅ、Ｃｕ、Ｚｒの固溶量が許容範囲内、単体Ｓｉ量および０．５μｍ径以上の大きな粒子も少なく、結晶粒サイズが許容範囲内にあることにより、均一な電解粗面化面が得られ、粗面化面がストリークスなどなく外観が均一で、必要な強度を持ち、耐熱性に優れ、耐インキ汚れ性の良好な素板が得られた。
【００６１】
これに対して、比較例である試料番号Ｉ−７〜Ｉ−１０は、アルミニウム合金の化学成分が本発明の規定範囲外であるため、熱間圧延および冷間圧延を本発明の規定範囲内の条件で行ったにもかかわらず、アルミニウム合金素板のＦｅ、Ｃｕ、Ｚｒの固溶量、または単体Ｓｉ量および０．５μｍ径以上の大きな粒子の粒子数や結晶粒サイズが許容範囲外となってしまい、その結果、本発明に必要な特性の内、均一な電解粗面化面、または粗面化面がストリークスであり外観が不均一となったり、必要な強度範囲外や、耐熱性が劣ったり、必要な耐インキ汚れ性が得られなかった。個々の比較例については下記のとおりである。
【００６２】
比較例の試料番号Ｉ−７は、アルミニウム合金の化学成分のうちＭｇ量が本発明の規定範囲よりも多いため、本発明の規定範囲内の条件で冷間圧延をおこなったにもかかわらず、引張強さが許容範囲外となってしまった。
比較例の試料番号Ｉ−８は、アルミニウム合金の化学成分のうちＭｇ量が本発明の規定範囲よりも少ないため、本発明の規定範囲内の条件で冷間圧延および急速冷却を実施したにもかかわらず、冷間圧延中の析出により単体Ｓｉ量および０．５μｍ以上の粗大な単体Ｓｉの個数が本発明の規定範囲を超えてしまい、必要な耐インキ汚れ性が得られなかった。
比較例の試料番号Ｉ−９は、アルミニウム合金の化学成分のうちＺｒ量が本発明の規定範囲よりも多いため、Ｚｒ固溶量も多くなってしまい、引張強さが本発明の許容範囲外となってしまった。
比較例の試料番号Ｉ−１０は、アルミニウム合金の化学成分のうちＺｒ量が本発明の規定範囲よりも少ないため、Ｚｒ固溶量も少なく、必要な耐バーニング後の耐力が得られない。
【００６３】
〔実施例２〕
＜鋳塊の準備＞
本発明の規定範囲内の化学組成であるＦｅ：０．３２ｗｔ％、Ｓｉ：０．０７ｗｔ％、Ｃｕ：０．０１２ｗｔ％、Ｔｉ：０．０２ｗｔ％、Ｍｇ：０．００８ｗｔ％、Ｚｒ：０．０１３ｗｔ％、Ｂ：０．０００４wt％、残部：実質的にアルミニウムおよび不可避不純物から成るアルミニウム合金の溶湯を溶製した。この溶湯を半連続鋳造法によって厚さ５６０mmのアルミニウム合金鋳塊とし、両面の面削によって厚さ５４０mmとした。
＜熱間圧延＞
次に、アルミニウム合金鋳塊を、均質化処理せずに、表3に示した種々の温度で２時間保持する均質化処理を行ってから、表3に示した種々の熱間圧延開始温度に１時間保持した。ワークロール径９００mmφの可逆式熱間圧延機を用い、圧延パス数１５回、各パス間時間１０秒〜１．５分の条件で熱間圧延を行い、表3に示した種々の厚さの熱間圧延板を得た。表3に、均質化処理温度、熱間圧延開始温度、熱間圧延最終パス開始温度、最終パス前板厚、最終板厚、最終パス歪み速度、熱間圧延終了温度をまとめて示す。
【００６４】
【表３】

【００６５】
＜冷間圧延＞
次に、室温（４０℃）の熱間圧延板を冷間圧延した。冷間圧延速度を５００〜２０００ｍ／分とした。ただし、板厚さが薄くなるに従い圧延速度を速くした。冷間圧延の方式は、各パス後に冷間圧延板を巻き取ってコイルとし、次パスに供する方式とした。
冷間圧延第一パスは、板厚さ６mm→３mmで行った。圧延終了温度は、９０℃であった。直ちに、冷間圧延第二パスを板厚さ３mm→１mmで行った。圧延終了温度は１５０℃であった。引続き、１１０℃まで冷却速度１０℃／分で急速冷却を行った。急速冷却は、油性の冷媒液の噴霧槽にコイルを置いて行った。そして、冷間圧延第三パスを板厚さ１mm→０．５mmで行った。圧延終了温度は、１５０℃であった。直ちに、冷間圧延第四パスを０．５mm→０．２４mmまで行った。圧延終了温度は１２０℃であった。冷間圧延の終了したコイルを、室温まで１０℃／分の冷却速度で急速冷却した。冷却方法は、冷間圧延第二パス後の急速冷却方法と同様に行った。その後、テンションレベラーによって矯正を行い、平版印刷版用アルミニウム合金素板を得た。
【００６６】
＜特性の評価＞
上記により得られた試料番号II−１〜II−６の本発明例およびII−７〜II−１５比較例の各アルミニウム合金素板について、実施例１において説明した評価・測定法によって、（Ａ）熱間圧延板の表面部の結晶粒幅および芯領域の結晶粒幅、（Ｂ）冷間圧延により得られたアルミニウム合金素板について、Ｆｅ、Ｃｕ、Ｚｒの各固溶量、単体Ｓｉ量および平均粒径０．５μｍ以上の単体Ｓｉの個数、表層領域の結晶粒幅、伸び率、芯領域の結晶粒幅、電解粗面化処理後の電解粗面化面の均一性、粗面化外観の均一性、引張強さ、バーニング処理後の耐力、インキ汚れ性の評価・測定を行った。結果を表４に示す。
【００６７】
【表４】

【００６８】
表３および表４において、本発明例である試料番号II−１〜II−６は、アルミニウム合金の化学成分が本発明の規定範囲内であり、かつ、熱間圧延条件・冷間圧延条件が本発明の規定範囲内であることによって、アルミニウム合金素板のＦｅ、Ｃｕ、Ｚｒの各固溶量が許容範囲内であり、単体Ｓｉ量および０．５μｍ径以上の大きな粒子も少なく、結晶粒サイズが許容範囲内にあり、その結果、均一な電解粗面化面が得られ、粗面化面がストリークスなどなく外観が均一で、必要な強度を持ち、耐熱性に優れ、耐インキ汚れ性の良好な素板が得られた。
【００６９】
これに対して、比較例である試料番号II−７〜II−１５は、熱間圧延用加熱温度、または熱間圧延条件が本発明の規定範囲外であるため、アルミニウム合金の化学成分および冷間圧延条件が本発明の規定範囲内であるにもかかわらず、アルミニウム合金素板のＦｅ、Ｃｕ、Ｚｒの各固溶量、または単体Ｓｉ量および０．５μｍ径以上の大きな粒子や結晶粒サイズが許容範囲外となってしまい、その結果、本発明に必要な特性のうち、均一な電解粗面化面、または粗面化面がストリークスであり外観が不均一となったり、必要な強度範囲外や、耐熱性が劣ったり、必要な耐インキ汚れ性が得られなかったりした。個々の比較例については下記のとおりである。
【００７０】
比較例の試料番号II−７は、熱間圧延開始温度が本発明の規定範囲よりも高いことによって、熱間圧延板表面部の結晶粒サイズが粗大となったため、冷間圧延された素板も表層領域の結晶粒が粗大となってしまい、その結果、粗面化面にストリークスがみられ外観が不均一となってしまう。更に、Ｆｅ、Ｃｕの固溶量が発明の規定範囲よりも高くなってしまって、本発明の規定範囲の条件で冷間圧延をしても、引張強さが許容範囲外となってしまった。
比較例の試料番号II−８は、本発明の制限範囲を超える温度で均質化処理を行ったため、Ｆｅ、Ｃｕの固溶量が本発明の規定範囲よりも高くなったばかりでなく微細な析出物がないため、本発明の規定範囲内の条件で熱間圧延を行っても、中芯部の結晶粒が本発明の規定範囲より小さくなってしまった。そのため、本発明の規定範囲内の条件で冷間圧延を行っても、加工硬化が促進され、引張強さが本発明の許容範囲よりも高くなってしまった。
比較例の試料番号II−９は、熱間圧延の最終パス開始温度が本発明の規定範囲よりも高いため、熱間圧延板表面部の結晶粒が粗大となってしまい、その結果、冷間圧延後の素板は粗面化面にストリークスがみられ外観が不均一となってしまった。
比較例の試料番号II−１０は、熱間圧延の最終パス開始温度および終了温度が本発明の規定範囲よりも低いため、熱間圧延板表面部の結晶粒サイズは非常に小さいが、芯領域が未再結晶となるため、素板の芯領域で加工歪みが非常に大きくなり、その結果、引張強さが高くなってしまった。また、この加工歪みが大きいことにより、冷間圧延中に単体Ｓｉの析出が促進され、耐インキ汚れ性がやや低下した。
比較例の試料番号II−１１は、熱間圧延の最終パス開始温度と終了温度が本発明の規定範囲よりも高いため、熱間圧延板表面部の結晶粒が粗大となる。その結果，冷間圧延により得られた素板の表層領域の結晶粒が粗大となってしまい、粗面化面にストリークスがみられ外観が不均一となってしまった。
比較例の試料番号II−１２は、熱間圧延最終パスの圧延速度が遅いことにより歪み速度が小さかったため、終了温度が本発明の規定範囲よりも低い。このため、熱間圧延板表面部の結晶粒が粗大になり、更に、芯領域が未再結晶となってしまう。これにより素板の表層領域の結晶粒が粗大となったため、粗面化面にストリークスがみられ外観が不均一になってしまうばかりか、素板の芯領域で加工歪みが非常に大きくなって、引張強さが本発明の規定範囲を超えてしまった。また、この加工歪みが大きいことにより、圧延中に単体Ｓｉ量が多くなってしまい、耐インキ汚れ性がやや劣ってしまう。
比較例の試料番号II−１３は、熱間圧延最終パス前の板厚が薄いため歪み速度が小さくなっており、熱間圧延板表面の結晶粒が粗大になり、更に、芯領域が未再結晶となってしまう。これにより支持体表層領域の結晶粒が粗大となってしまうことによって、粗面化面にストリークスがみられ外観が不均一になってしまうばかりか、支持体の芯領域で加工歪みが非常に大きなものとなって、引張強さが高くなってしまう。また、この加工歪みが大きいことにより、圧延中に単体Ｓｉ量が多くなってしまい、耐インキ汚れ性がやや劣ってしまう。
比較例の試料番号II−１４は、熱間圧延最終パスの圧延速度が遅いためことから歪み速度が小さくなっており、熱間圧延板表面の結晶粒サイズが粗大になってしまう。これにより支持体表層領域の結晶粒が粗大となってしまうことによって、粗面化面にストリークスがみられ外観が不均一になってしまう。
比較例の試料番号II−１５は、熱間圧延最終板厚が発明の規定範囲よりも薄いため、熱間圧延板表面の結晶粒サイズは発明の規定範囲内と小さかったが、中芯部にまで加工歪みが強く導入されたため、支持体の芯領域で加工歪みが非常に大きなものとなって、引張強さが高くなってしまう。
【００７１】
〔実施例３〕
＜鋳塊の準備＞
本発明の規定範囲内である表５に示した化学組成のアルミニウム合金の溶湯を溶製した。この溶湯を半連続鋳造法によって厚さ５６０mmのアルミニウム合金鋳塊とし、両面の面削によって厚さ５４０mmとした。
【００７２】
【表５】

【００７３】
＜熱間圧延＞
次に、アルミニウム合金鋳塊を、温度５００℃で２時間保持する均質化処理を行ってから、同じ炉内で熱間圧延開始温度３９０℃に下げて１時間保持した。ワークロール径９００mmφの可逆式熱間圧延機を用い、圧延パス数１５回、パス間時間１０秒〜１．５分の条件で熱間圧延を行い、厚さ６mmの熱間圧延板を得た。ここで、熱間圧延の最終パスは、１８mm厚さから６mm厚さへの圧下（圧下率６７％）、最終パス開始温度３６０℃で行い、３５０℃で熱間圧延を終了した。最終パスの圧延速度は１００ｍ／分とした。圧延時間は０．０４４ secであり、歪み（対数歪み）は１．１０、歪み速度εは２５．０ sec^-1であった。
【００７４】
<冷間圧延＞
次に、室温（４０℃）の熱間圧延板を冷間圧延した。冷間圧延速度を５００〜２０００ｍ／分とした。ただし、板厚さが薄くなるに従い圧延速度を速くした。冷間圧延の方式は、各パス後に冷間圧延板を巻き取ってコイルとし、次パスに供する方式とした。
表６に、冷間圧延の各パスにおける条件を示す。比較例の試料番号 III−１は６パスの冷間圧延を、板厚さ６mm→３．５mm→２mm→１．２mm→０．７mm→０．４２mm→０．２５mmで、表６に示した各圧延温度で行った。冷間圧延２パス後と冷間圧延４パス後の冷却はコイルをファンにより強制空冷した。これによる冷却速度は、０．２℃／分であった。
比較例の試料番号III−２、 III−３および実施例の試料番号 III−４、 III−５は４パスの冷間圧延を、板厚さ６mm→３mm→１mm→０．５mm→０．２４mmで行った。表６に示した各冷間圧延温度で行った。冷間圧延２パス後に冷却を行う場合は、コイルを冷間圧延３パス目の圧延開始まで１０℃／分の冷却速度で急速冷却した。最終の冷間圧延４パス後の冷却方法は、室温まで冷却速度１０℃／分で急速冷却を行う、油性の冷媒液の噴霧槽にコイルを置き行う方法と、室温まで冷却速度は、０．２℃／分で強制冷却を行う、ファンにより空冷する方法とした。比較例および実施例の冷間圧延温度および冷却を行った場合の冷却速度について、表６にまとめて示した。
その後、テンションレベラーによって矯正を行い、平版印刷版用アルミニウム合金支持体用素板を得た。
【００７５】
【表６】

【００７６】
＜特性の評価＞
上記により得られた試料番号 III−１〜 III−５の本発明例および比較例の各アルミニウム合金素板について、実施例１において説明した評価・測定法によって、（Ａ）熱間圧延板の表面部の結晶粒幅および芯領域の結晶粒幅、（Ｂ）冷間圧延により得られたアルミニウム合金素板について、Ｆｅ、Ｃｕ、Ｚｒの各固溶量、単体Ｓｉ量および平均粒径０．５μｍ以上の単体Ｓｉの個数、表層領域の結晶粒幅、伸び率、芯領域の結晶粒幅、電解粗面化処理後の電解粗面化面の均一性、粗面化外観の均一性、引張強さ、バーニング処理後の耐力、インキ汚れ性の評価・測定を行った。結果を表７に示す。
【００７７】
【表７】

【００７８】
表５、６、７において、本発明例である試料番号 III−４〜 III−５は、アルミニウム合金の化学成分が本発明の規定範囲内であること、本発明の規定範囲内の熱間圧延用加熱温度、熱間圧延条件、冷間圧延条件であることによって、支持体用素板のＦｅ、Ｃｕ、Ｚｒの固溶量が許容範囲内、単体Ｓｉ量および０．５μｍ径以上の大きな単体Ｓｉ粒子個数も本発明の規定範囲内であり、結晶粒サイズが許容範囲内にあることにより、均一な電解粗面化面が得られ、粗面化面がストリークスなどなく外観が均一で、必要な強度を持ち、耐熱性に優れ、耐インキ汚れ性の良好な素板が得られた。
【００７９】
これに対して、比較例である試料番号 III−１〜 III−３は、冷間圧延条件、または冷間圧延途中または圧延後の冷却条件が本発明の規定範囲外であることから、本発明規定範囲内のアルミニウム合金の化学成分、熱間圧延用加熱温度、熱間圧延条件であるにもかかわらず、支持体用素板の単体Ｓｉ量および０．５μｍ径以外の大きな単体Ｓｉ粒子個数が本発明の許容範囲外となってしまい、その結果、本発明に必要な特性のうち、必要な耐インキ汚れ性が得られなかったり、必要な引張強さ範囲外であったりした。個々の比較例については下記のとおりである。
【００８０】
比較例の試料番号 III−１は、前記冷間圧延において回復温度以上に達していないことによって、本発明の規定範囲よりも引張強さが高くなってしまう。
比較例の試料番号 III−２、 III−３は、前記冷間圧延において、全冷間圧延４パスを連続して行い、回復温度以上の冷間圧延温度を得られたにもかかわらず、最終冷間圧延後に急速冷却を行わず、ファンによる強制冷却により、十分な冷却がなされていなかったために、単体Ｓｉ量および０．５μｍ径以上の大きな単体Ｓｉ粒子個数が本発明許容範囲外となってしまうことによって、本発明に必要な特性のうち、必要な耐インキ汚れ性が得られなかった。
【００８１】
【発明の効果】
本発明によれば、粗面化面の均一性および外観の均一性が高く、粗面化処理によりストリークスや画質ムラ等の処理ムラが発生せず、必要な強度と曲げ加工性を兼備するための適切な範囲の引張強さとバーニング処理後の十分な耐力とを有し、耐インキ汚れ性の優れた平版印刷版用アルミニウム合金素板が提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention provides a uniform (chemical or electrochemical) roughened surface, has a required strength and a uniform appearance with no streak or uneven surface quality after roughening, and causes ink stains during printing. It relates to an aluminum alloy base plate for lithographic printing plates with good heat resistance and good heat resistance, and further omits intermediate annealing during cold rolling, reduces the number of cold rolling passes, and simplifies the manufacturing process. Although the manufacturing cost is reduced, the present invention relates to a method for manufacturing an aluminum alloy base plate for a lithographic printing plate that satisfies the above characteristics.
[0002]
[Prior art]
Conventionally, as an aluminum alloy base plate for a lithographic printing plate, a thin plate of an aluminum alloy such as JIS 1050 having a thickness of 0.1 to 0.5 mm is generally used, and such an aluminum alloy thin plate is generally generally semi-continuous cast. The surface of the ingot obtained by the above is removed by chamfering, homogenized, and manufactured through hot rolling and cold rolling, intermediate annealing, and final cold rolling.
[0003]
The aluminum alloy base plate for a lithographic printing plate manufactured in this way is, as will be described below, “base plate” → roughening, etc. → “support” → photosensitive layer formation → “printing plate” → image portion formation → After going through the “printing master” stage, it is used for printing.
That is, first, the surface of the base plate is roughened by a process combining one or more of a mechanical method, a chemical method, or an electrochemical method, and further anodized, and optionally hydrophilic. To be a lithographic printing plate support.
Next, a photosensitive lithographic printing plate is obtained by applying a photosensitive material to the surface of the support to form a photosensitive layer.
[0004]
Next, the lithographic printing plate is subjected to a plate making process for sequentially performing image exposure, development, washing with water, lacquering and the like to obtain a printing original plate. At that time, the portion where the photosensitive layer remains undissolved by the development processing becomes a hydrophobic image portion, that is, an ink receiving portion, while the portion where the photosensitive layer dissolves and disappears is the roughened surface of the aluminum alloy support. Is exposed to become a hydrophilic non-image portion, that is, a water receiving portion. Further, as a means for improving the printing durability, a heat treatment at a high temperature (processing called burning) is generally performed after the development processing. The burning treatment is usually performed by holding at a temperature of about 200 to 280 ° C. for about 3 to 7 minutes, although it depends on the composition forming the image.
[0005]
Both ends of the printing original plate are bent, and are inserted into an attachment portion of a printing press plate cylinder, and fixed to a cylindrical plate cylinder. Therefore, the lithographic printing plate base plate is required to have bending workability and plate cylinder winding performance.
[0006]
During printing, dampening water is supplied to the plate surface of the printing original plate so that water is retained in the hydrophilic non-image area, and ink is supplied to adhere to the hydrophobic image area. Printing is performed by first transferring the ink adhering to the image portion to a blanket cylinder and then transferring the ink from the blanket cylinder to a final printing surface such as a paper surface.
The number of printed copies may be as large as 100,000 copies, for example, and the printing original plate must be able to withstand such a large number of times of printing, that is, printing durability is required. Various characteristics are required to ensure printing durability. That is, it is necessary to maintain water retention so that ink adhesion does not occur in non-image areas. In addition, if pitting occurs on the surface of the support (roughened surface) that is in contact with the fountain solution during printing, ink adheres to the pitting portion and stains in the non-image area, that is, ink stains. May occur. In order to prevent ink stains, it is important to ensure sufficient water retention and corrosion resistance. To that end, excellent rough surface uniformity and corrosion resistance of the support by electrochemical roughening treatment and It is necessary to obtain a healthy anodic oxide film.
[0007]
In the method for producing an aluminum base plate for a lithographic printing plate disclosed in Japanese Examined Patent Publication No. 5-28197, the normal homogenization temperature is 450 to 600 ° C., preferably at a temperature of 520 to 600 ° C. for 1 hour or more, In hot rolling, recrystallization and precipitation are repeatedly performed by several rolling passes, and hot rolling is completed at 300 ° C. or higher. Moreover, the intermediate annealing in the middle of cold rolling performs rapid cooling of 500 ° C./sec or more after reaching a predetermined temperature of 400 to 600 ° C.
[0008]
In the method for producing an aluminum base plate for a lithographic printing plate disclosed in JP-A-8-17996, homogenization treatment is performed at 500 to 600 ° C, hot rough rolling is started at 430 to 480 ° C, The dynamic recrystallization is repeatedly performed by repeatedly performing rough rolling, and the hot rough rolling is completed at a temperature of 380 to 430 ° C. and a plate thickness of 10 to 35 mm. The finish hot rolling finish temperature is completed at 260 to 350 ° C. or more, and a region that partially causes recrystallization is not formed.
[0009]
In the method for producing an aluminum base plate for a lithographic printing plate disclosed in JP-A-62-148295, a part of Fe is dissolved in a solid solution by performing a homogenization treatment at 500 to 600 ° C. for 3 hours or more. By cooling at 50 ° C./h or lower until 430 ° C. or lower, or holding at 350 to 450 ° C. for 30 minutes or longer, Si atoms present in the ingot are converted into Al—Fe—Si intermetallic compounds. Precipitate and fix, and reduce the amount of single Si precipitate in the subsequent process. Hot rolling is performed at 450 to 200 ° C. to prevent recrystallized grains between hot rolling passes from becoming coarser than 100 μm. The intermediate annealing after the hot rolling is performed at 350 to 500 ° C. for 2 to 5 hours or at 400 to 550 ° C. for 120 seconds or less in a continuous annealing furnace. According to this method, a uniform rough surface is obtained by the electrolytic roughing treatment, and the ink stain resistance of the non-image area during printing is improved. As an example, performing intermediate annealing in a cold rolling process following hot rolling is exemplified.
[0010]
Japanese Patent Application Laid-Open No. 61-201747 discloses a manufacturing method for obtaining an aluminum base plate for a lithographic printing plate having an appropriate tensile strength and excellent strength after burning treatment. In this method, hot rolling is started at a temperature of 480 to 550 ° C., and the hot rolling is completed at 320 ° C. or more and a plate thickness of 2.5 to 3.5 mm. A structure having both crystallized surfaces is obtained, and cold rolling is performed without intermediate annealing.
[0011]
Japanese Patent Laid-Open No. Hei 6-192579 discloses the inclusion of Mg to control the precipitation of elemental Si in the manufacturing process including casting, homogenization, hot rolling, cold rolling, intermediate annealing, and final cold rolling. Thus, a method for producing a lithographic printing plate excellent in ink stain resistance during printing has been proposed.
In JP-A-10-306355, the ingot is homogenized and then hot rolling is started from a predetermined temperature, the hot rolling is finished at a predetermined temperature, and then cooled to a predetermined temperature. In order to prevent streaks from occurring, a method for manufacturing a support is proposed in which strength is imparted to the support by rolling to a final thickness at a compression ratio of 60% or more without performing heat treatment.
In Japanese Patent Application No. 11-205251, the amount of elemental Si is 30 ppm or less, and the number of elemental Si particles of 0.5 μm or more in the anodized film is 200 / mm. ² A lithographic printing plate support having a tensile strength of 145 to 180 MPa, and a lithographic printing plate support having controlled the plate temperature at least after the final pass by cold rolling above the recovery temperature and the subsequent rapid cooling. The manufacturing method is shown.
[0012]
In JP-A-11-229101, in the steps of homogenization treatment, hot rolling and cold rolling, the hot rolled sheet thickness is 3.0 mm or less, and at least the end temperature of cold rolling is 100 to 200 ° C. A method of producing a lithographic printing plate that is excellent in surface quality and handling properties and is inexpensive has been proposed.
In JP-A-11-256293, lithographic printing is performed at a homogenization temperature of 350 to 480 ° C., hot rolling is performed in multiple passes, and non-recrystallized after the final pass to obtain crystal grains having an average grain size of less than 50 μm. A method of manufacturing a plate base plate has been proposed.
[0013]
Japanese Examined Patent Publication No. 63-15978 proposes a lithographic printing plate support having good heat resistance, which contains Zr 0.02 to 0.20% by weight and does not cause recrystallization up to a temperature of 320 ° C.
[0014]
[Problems to be solved by the invention]
The following characteristics are required for an aluminum base plate for planographic printing plates.
(1) In order to obtain good printing durability, it is necessary to improve water retention and adhesion of the photosensitive film. Therefore, it is necessary for the base plate to easily obtain a uniform and dense rough surface by roughening treatment.
(2) When the support is manufactured, processing unevenness called streaks or image quality unevenness does not appear.
(3) Sufficient strength is required to prevent scratches such as dents due to impact during transportation and handling. Furthermore, bending workability when fixing to a printing press plate cylinder is required. Also, fatigue strength is required to ensure durability against repeated stress during printing. For this purpose, it is necessary to increase the tensile strength of the base plate to about 145 to 190 MPa.
(4) As a means for improving the printing durability, a method of performing heat treatment (processing called burning) at a high temperature after development is generally performed. The normal burning treatment is heated at a temperature of 200 to 280 ° C. for about 3 to 7 minutes, although it depends on the composition forming the image. Although the strength of the base plate is reduced by this treatment, it is necessary that the proof stress after the burning treatment at 270 ° C. for 7 minutes is 100 MPa or more.
(5) It is necessary that ink does not easily adhere to the non-image area during printing. Such a property is called ink stain resistance.
However, in the conventional general printing plate and the manufacturing method thereof as described above, it is very difficult to satisfy all the above characteristics at the same time, though each has advantages.
Therefore, in order to satisfy all the characteristics of the present invention, the composition of the aluminum alloy, the solid solution amount of the alloy component, the composite component amount of the solid solution amount, the crystal grain size of the surface, the crystal of the core region other than the surface layer The purpose is to provide a base plate that satisfies all the characteristics necessary for a base plate for a lithographic printing plate by controlling the grain size, the elongation rate of the crystal grains, the amount of single Si and the number of single Si exceeding a certain size. And
[0015]
Further, in recent years, cost reduction is desired for an aluminum alloy support for a lithographic printing plate. As a countermeasure, simplification of the manufacturing process is being studied. In the present invention, in particular, the lithographic printing plate in which the hot rolling method and the cold rolling method are controlled in order to simplify the omission of intermediate annealing and to simplify the cold rolling process and to control the deterioration of quality which is a detrimental effect of the simplification. An object of the present invention is to provide a method for producing an aluminum alloy base plate.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, the aluminum alloy composition of the base plate, the solid solution amount and the composite solid solution amount of a specific alloy component, the crystal grain size and elongation (length / Width ratio), crystal grain size in the core region, single Si amount, and the number of single Si exceeding a specific size.
[0017]
That is, the aluminum alloy base plate for a lithographic printing plate according to the present invention is
(1) The following ingredients:
Fe: 0.10 to 0.40 wt%,
Si: 0.03-0.15 wt%,
Cu: 0.004 to 0.020 wt%,
Ti: 0.01 to 0.05 wt%,
Mg: 0.002-0.02 wt%,
Zr: 0.001 to 0.030 wt%,
B: 0.0001 to 0.02 wt%, and
The rest: aluminum and inevitable impurity elements
Consisting of
Fe solid solution amount is less than 30ppm,
Cu solid solution amount is less than 100ppm,
Zr solid solution amount is less than 200ppm,
Fe solid solution amount + (1/2) Zr solid solution amount ≧ 25 ppm,
(2) The surface layer region from the plate surface to a depth of at least 20 μm has the following conditions (A) and (B)
(A) The crystal grain width sD in the direction perpendicular to the rolling direction is less than 50 μm on average and less than 100 μm on the maximum, and
(B) The grain length sL in the rolling direction is 10 times or more than the grain width sD,
A cold-rolled processed structure satisfying
(3) The crystal grain width cD in the direction perpendicular to the rolling direction in the core region having a thickness of 2/3 or more of the plate thickness at the center of the plate thickness is 100 μm or more on average.
(4) The plate thickness is 0.1 to 0.5 mm, the tensile strength is 145 to 190 MPa, the proof stress after burning at 270 ° C. for 7 minutes is 100 MPa or more,
(5) The number of elemental Si is 30 ppm or less, and the number of elemental Si is 200 / mm with an equivalent circle diameter and a particle diameter of 0.5 μm or more per 0.5 μm depth of the base plate. ² Is
It is characterized by that.
[0018]
The method for producing an aluminum alloy base plate for a lithographic printing plate of the present invention,
Fe: 0.10 to 0.40 wt%,
Si: 0.03-0.15 wt%,
Cu: 0.004 to 0.020 wt%,
Ti: 0.01 to 0.05 wt%,
Mg: 0.002-0.02 wt%,
Zr: 0.001 to 0.030 wt%,
B: 0.0001 to 0.02 wt%, and
The rest: aluminum and inevitable impurity elements
An aluminum alloy slab comprising: a method of performing hot rolling after performing homogenization treatment at less than 550 ° C. without performing homogenization treatment, and then cold rolling, and correcting as necessary,
The above hot rolling is performed under the following conditions:
Hot rolling start temperature: 300-480 ° C.
Starting temperature of the final pass: 300-380 ° C
End temperature of the final pass: 320-380 ° C
Final path distortion rate: 15 / sec or more, and
Thickness after hot rolling: 4.5 to 10 mm,
And then
The cold rolling is performed without intermediate annealing.
It is characterized by that.
[0019]
In a desirable mode of the present invention, the plate temperature after at least the final pass of the cold rolling is not less than the recovery temperature Less than 190 ° C And the final path Within 10 minutes, with a cooling rate of 5 ° C / minute or more Perform rapid cooling.
[0020]
In a more desirable embodiment of the present invention, the recovery temperature after cold rolling is 100 ° C. or higher. is there .
[0021]
In the present invention, a chemical composition is controlled as a basic condition for satisfying all the characteristics in an aluminum alloy base plate for a lithographic printing plate having a thickness of 0.1 to 0.5 mm.
The tensile strength of the base plate for an aluminum alloy support for a lithographic printing plate is controlled to 145 to 190 MPa by limiting the amount of each solid solution of Fe, Cu, and Zr to a specific value or less.
On the other hand, by ensuring the combined solid solution amount of Fe and Zr, that is, the Fe solid solution amount + (1/2) Zr solid solution amount above a specific value, the heat resistance is 270 ° C. and the proof stress after treatment for 7 minutes is 100 MPa. Control above.
Further, in the surface layer region of the base plate, the crystal grain width sD (crystal grain size perpendicular to the rolling direction) is reduced to a specific value or less, and at the same time, the crystal grain length sL with respect to the crystal grain width sD (the crystal in the rolling direction) The ratio of grain size), that is, the elongation rate, is increased to a specific value or more, thereby suppressing the occurrence of streak and image quality unevenness when the base plate is roughened to form a support. Further, in the core region of the base plate, the tensile strength is controlled to 145 to 190 MPa by increasing the crystal grain width cD (crystal grain size perpendicular to the rolling direction) to a specific value or more.
In addition to restricting the amount of simple Si to a specific value or less, and by limiting the number of single Si having a large equivalent particle diameter of 0.5 μm or more in the surface layer region to a specific value or less, it has good resistance to resistance. Ensure ink smearing. Here, “single Si” refers to Si contained in the alloy that is not dissolved in the alloy but is precipitated as Si particles.
[0022]
Moreover, in the manufacturing method of the base plate for aluminum alloy support bodies for lithographic printing plates of this invention, a chemical composition is controlled as a basic condition for satisfying all the said characteristics.
When the homogenization treatment is not performed or is performed, the homogenization treatment temperature is limited to less than a specific value, and by controlling the hot rolling start temperature, the respective solid solution amounts of Fe, Cu, and Zr are reduced to a specific value or less. While being able to reduce, the composite solid solution amount of Fe and Zr, that is, the Fe solid solution amount + (1/2) Zr solid solution amount, can be ensured to a specific value or more.
By controlling the hot rolling start temperature, the hot rolling final pass starting temperature, the hot rolling finishing temperature, the hot rolling final pass strain rate, the hot rolling finish plate thickness, The grains can be fine and elongated, that is, the width can be reduced and the length can be increased, and at the same time, the crystal grains in the core region can be coarsened.
[0023]
Furthermore, by making the plate temperature after at least the final pass of the cold rolling equal to or higher than the recovery temperature of the plate, the work-hardened plate is softened without performing intermediate annealing in the middle of cold rolling, and the desired strength and The plate thickness can be secured. At the same time, precipitation of elemental Si is suppressed by rapid cooling from a temperature equal to or higher than the recovery temperature after cold rolling. As a result, it is possible to produce an aluminum alloy base plate for a lithographic printing plate that has an appropriate strength and that suppresses ink stains in non-image areas during printing.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
First, the reasons for limiting the components of the aluminum alloy in the present invention will be described.
<Fe: 0.10 to 0.40 wt%>
Fe is an element necessary for producing Al-Fe-based and Al-Fe-Si-based intermetallic compounds and refining crystal grains during casting. At the same time, there is an effect of securing strength. If the Fe content is less than 0.10 wt%, the grain refinement effect of the cast structure cannot be obtained, and coarse crystal grains are present, so that a rough surface obtained by chemical or electrochemical roughening treatment is present. The uniformity of the appearance of the chemical surface is impaired. On the other hand, when the Fe content exceeds 0.40 wt%, coarse compounds of Al—Fe and Al—Fe—Si are formed, and the local unevenness of chemical properties becomes remarkable, and the chemical rough surface The pit shape on the roughened surface or the electrochemically roughened surface becomes non-uniform and the water retention is reduced.
Since Fe is also an element usually contained as an impurity element in an Al alloy, it is necessary to use a high-purity Al alloy as a raw material in order to reduce the Fe content to less than 0.10 wt%. Also become.
<Si: 0.03-0.15 wt%>
Si is an element necessary for forming an Al—Fe—Si type fine intermetallic compound together with Fe, and its effect is insufficient when the Si content is less than 0.03 wt%. When the Si content exceeds 0.15 wt%, a coarse compound of Al—Fe—Si system is formed, and the local nonuniformity of chemical properties becomes remarkable, and the chemical roughened surface or the electrochemical roughened surface. The pit shape on the surface is non-uniform and water retention is reduced. Furthermore, if the Si content is excessive, simple Si is generated and the ink smearing property of the non-image area is promoted, which is not preferable.
Si is also an element contained as an impurity in the aluminum alloy, like Fe, and reducing the Si content to 0.03 wt% or less increases the cost as well as reducing Fe.
<Cu: 0.004 to 0.020 wt%>
Cu is an element that greatly affects electrochemical roughening. If the Cu content is 0.004 wt% or more, it is preferable because the pit density on the electrochemical roughened surface can be made appropriate. On the other hand, if the Cu content exceeds 0.020 wt%, the pit density on the electrochemically roughened surface becomes low, the pit size is too large, or an unetched region (roughened unfinished portion) occurs. . This impairs the water retention of the non-image area. Furthermore, it is not preferred because it promotes ink smearing during printing. Furthermore, as the Cu content increases, the Cu solid solution amount increases, and as a result, the tensile strength increases beyond the appropriate range.
<Ti: 0.01-0.05 wt%, B: 0.0001-0.02 wt%>
Ti and B are effective for refinement of crystal grains in the cast structure. Therefore, it is effective in preventing cracks during casting, and is effective in preventing the occurrence of streaks on the roughened surface due to the coarsening of crystal grains in the cast structure. B is added together with Ti and is effective for refining the crystal grain of the cast structure. The effect is greater than when only Ti is added. Ti is preferably 0.01 to 0.05 wt%, and B is preferably 0.0001 to 0.02 wt%.
[0025]
<Mg: 0.002 to 0.02 wt%>
Mg delays the precipitation of elemental Si and can extend the allowable time from the completion of cold rolling above the recovery temperature to the start of rapid cooling. Thereby, the operation | work of rapid cooling can be made easy. In addition, since the precipitation of elemental Si can be delayed by the presence of Mg, the temperature of the plate during cold rolling can be increased corresponding to the delay. Therefore, the tensile strength can be easily reduced by cold rolling at a high temperature. When the Mg content is less than 0.002 wt%, the above-described effects are small. On the other hand, if the Mg content exceeds 0.02 wt%, it becomes difficult to recover the cold-rolled sheet, and the tensile strength becomes too high to give desired strength.
[0026]
<Zr: 0.005-0.030 wt%>
Zr has the effect of improving heat resistance (burning resistance). If the Zr content is less than 0.005 wt%, the effect is insufficient. On the other hand, if the Zr content is 0.030 wt% or more, the heat resistance is good, but the tensile strength becomes too high. Further, the recrystallized grains of the aluminum alloy base plate are enlarged, and the presence of coarse crystal grains impairs the appearance uniformity of the chemically roughened surface or the electrochemically roughened surface.
[0027]
<Fe solid solution amount: less than 30 ppm, Cu solid solution amount: less than 100 ppm>
The amount of solid solution of Fe and the amount of solid solution of Cu affects the recovery of the cold rolled sheet. When the solid solution amount of Fe is 30 ppm or more and the solid solution amount of Cu is 100 ppm or more, it becomes difficult to recover the cold rolled sheet. The tensile strength becomes too high, and it becomes difficult to give a desired strength.
[0028]
<Zr solid solution amount is less than 200 ppm>
Solid solution Zr is effective in improving heat resistance (burning resistance). However, when the Zr solid solution amount is 200 ppm or more, the heat resistance is good, but it becomes difficult to recover the cold rolled sheet, and the tensile strength becomes too high. Furthermore, the recrystallized grains of the aluminum plate become large, and the presence of coarse crystal grains impairs the appearance uniformity of the chemically roughened surface or the electrochemically roughened surface.
[0029]
<Fe + (1/2) Zr solid solution amount ≧ 25 ppm>
Each of the Fe solid solution amount and the Zr solid solution amount is very small and is effective in heat resistance (burning resistance). However, as described above, as the solid solution amount of Fe and Zr increases, it becomes difficult to recover the cold-rolled sheet, and the tensile strength (tensile strength) becomes too high. Thus, as a result of examining the degree of the effect, it was found that heat resistance would not be impaired if the Fe solid solution amount + (1/2) Zr solid solution amount ≧ 25 ppm.
[0030]
<Impurity element>
As the impurity element, Mn, Cr, V, Zn, Ni, Ga, Li, Be, or the like may be contained. However, these impurities do not have a significant adverse effect as long as they are a trace amount of about 0.05 wt% or less.
[0031]
<Crystal width sD and length sL of surface layer region>
The surface layer region from the plate surface to at least 20 μm in depth is subjected to the following conditions (A) and (B)
(A) The crystal grain width sD in the direction perpendicular to the rolling direction is less than 50 μm on average and less than 100 μm on the maximum, and
(B) The grain length sL in the rolling direction is 10 times or more than the grain width sD,
A cold-rolled texture satisfying
As a result, the surface layer region of the base plate has a cold-rolled texture with a crystal grain size in the above specified range, thereby preventing the occurrence of image quality unevenness with a remarkable appearance during the surface roughening treatment. Here, the surface layer region of the base plate corresponds to a region removed by the roughening process of the base plate.
[0032]
<Grain width cD of core region>
The average value of the crystal grain width cD in the direction perpendicular to the rolling direction in the core region having a thickness of 2/3 or more of the plate thickness at the center of the plate thickness is set to 100 μm or more.
Thus, by limiting the crystal grain size of the core region, the cold rolled sheet recovers and a state having a predetermined tensile strength is ensured. When the core region has a non-recrystallized structure during hot rolling or has a particle size of less than 100 μm, it becomes difficult to recover the cold rolled sheet, and the tensile strength becomes too high. Moreover, in the non-recrystallized state, during cooling such as air cooling after the end of hot rolling, simple Si is likely to precipitate and the amount of simple Si increases, and also during the cold working, Precipitation is promoted, and as a result, the amount of elemental Si exceeds 30 ppm, which is not appropriate.
[0033]
<Amount of simple Si and the number of large simple Si>
The amount of simple Si is 30 ppm or less, and the number of simple Si having an equivalent circle diameter and a particle size of 0.5 μm or more is 200 / mm. ² The following.
Precipitation from Si dissolved in the Al matrix to elemental Si tends to occur intensively in a portion where the dislocation density is high, and there is always an opportunity for precipitation in the manufacturing process of the base plate where dislocations are repeatedly generated by rolling. In particular, precipitation is promoted in the recovery temperature range below the recrystallization temperature during the rolling process.
If the amount of single Si exceeds 30 ppm, a large number of coarse single Si precipitated, aggregated and clustered is likely to be generated, which is not preferable. The deposited single Si is not easily anodized, and it is difficult to pass an electric current in the anodic oxide film treatment of the base plate, so that the film formed at the deposited portion becomes thin and it is difficult to obtain a film having a uniform thickness. Thin film portions are easily corroded by dampening water or the like repeated during printing, and the ink is liable to adhere to the corroded portions, which causes ink stains. Since the thickness of the anodized film formed on the roughened surface of the base plate is usually 0.1 to 1.0 μm, when the size of the single Si is increased, the thickness of the film is not only extremely disturbed. Furthermore, coarse single Si exceeding the film thickness comes to exist. 200 pieces / mm of simple Si having an average particle size of 0.5 μm or more are formed on the surface of the support obtained by coating the base plate. ² If there are a large number exceeding, the ink smear defect becomes obvious. Preferably, 100 pieces / mm of single Si having an average particle size of 0.5 μm or more ² It is as follows. Here, the average particle diameter of the simple substance Si is the measurement area represented by the equivalent circle diameter.
[0034]
Next, a method for producing an aluminum alloy base plate for a lithographic printing plate according to the present invention that satisfies the above requirements will be described.
The production of the aluminum alloy base plate of the present invention is basically performed by casting, chamfering, heating for hot rolling, hot rolling, and cold rolling processes, but if necessary, prior to heating for hot rolling. May be subjected to a homogenization treatment, or leveler correction may be performed after the final cold rolling.
[0035]
<Casting-facing>
An aluminum alloy ingot having the above composition, which has been melted by removing the surface, is cast by a conventional method. As this casting method, semi-continuous casting is suitable. The thickness of the semi-continuously cast ingot is suitably 500 to 600 mm. The ingot surface is chamfered before hot rolling.
<Homogenization treatment>
You may perform the homogenization process heated to high temperature rather than the heating for hot rolling before the heating for hot rolling. The homogenization treatment may be performed before or after the chamfering. The temperature of the homogenization treatment is less than 550 ° C. The holding time of the homogenization treatment is appropriately selected from the range of about 30 minutes to 24 hours in order to make the temperature of the entire ingot uniform. At a temperature of 550 ° C. or higher and holding for 24 hours or longer, the amount of Fe solid solution, the amount of Cu solid solution, the amount of Zr solid solution, etc. in the ingot becomes excessive, which is suitable for controlling within the specified range of the present invention. Not only that, but the cost increases, which is not preferable. From the homogenization temperature, holding at the heating temperature for hot rolling may be started immediately without waiting for cooling. Specifically, the ingot extracted from the homogenization furnace may be directly charged into a hot rolling heating furnace without being cooled.
[0036]
<Hot rolling>
Hot-rolling the chamfered ingot. Heating for hot rolling is performed at a temperature of 300 to 480 ° C. The holding time for heating for hot rolling is appropriately selected in the range of about 30 minutes to 5 hours according to the thickness of the ingot in order to make the temperature of the entire ingot uniform.
[0037]
The starting temperature of hot rolling is 300 to 480 ° C. If it is lower than 300 ° C., stable hot rolling cannot be performed, and if it is higher than 480 ° C., not only coarse recrystallized grains are generated during the hot rolling pass, but also Fe solid solution amount, Cu solid solution amount, Zr The amount of solid solution becomes excessive and exceeds the specified range of the present invention. Hot rolling is usually performed in several or more rolling passes.
[0038]
In the present invention, after controlling the hot rolling start temperature as described above, by controlling the final pass and end plate thickness of hot rolling as described below, the respective solid solution amounts of Fe, Cu, and Zr The composite solid solution amount, the crystal grain size in the surface region, and the crystal grain size in the core region can be controlled within the specified range of the present invention.
[The final pass and end thickness of hot rolling]
Starting temperature of final pass: 300-380 ° C
End temperature of final pass: 320-380 ° C
Final path distortion speed: 15 / sec or more
Final thickness of final rolling: 4.5-10mm
In the hot rolling, by controlling each condition of the final pass and the plate thickness after completion of the hot rolling as described above, the crystal grain size is within the above-described range necessary for the aluminum alloy base plate for a lithographic printing plate of the present invention. Can be controlled within.
In the prior art, since only the end temperature and end plate thickness of hot rolling were controlled, the control of the crystal grain size was insufficient, but in the present invention, the start temperature of the final pass and the strain rate of the final pass are also controlled. By controlling it, we succeeded in controlling the grain size.
The size of the crystal grain structure or subgrain structure during hot working is determined by the temperature and strain rate during hot working, but is also influenced by the metal structure of the material. In the present invention, the metal structure of the material is controlled by its chemical composition, the heating temperature for hot rolling, and in some cases, a homogenization treatment of less than 550 ° C. Furthermore, since normal coiling is performed after hot rolling, the size of the crystal grains after hot rolling is determined by the size of the grain structure or subgrain structure during hot working and the end temperature of hot rolling. . Here, the strain rate v is v = ε / t (sec when the strain is ε and the rolling time is t. ^-1 ). Here, the strain ε is a logarithmic strain expressed by ε = 1n (h1 / h2) when the plate thicknesses before and after the final pass are h1 and h2, respectively.
[0039]
In order to control the crystal grain size of the surface layer region and the crystal grain size of the core region within the specified range required for the aluminum alloy base plate for a lithographic printing plate of the present invention, the final pass start temperature and the final pass during hot rolling It is necessary to control the end temperature, the final pass strain rate, and the hot rolling end plate thickness as described above. Each of these conditions affects the grain structure, and all conditions must be satisfied at the same time. The reasons for limiting each condition are as follows.
◇ Final pass start temperature
The final pass start temperature of hot rolling needs to be 300 to 380 ° C. When the final pass start temperature is less than 300 ° C., the core region of the hot-rolled sheet is not recrystallized, and crystal grains having an average grain size of 100 μm or more cannot be obtained. Further, when the final pass start temperature exceeds 380 ° C., sufficient strain is not introduced, so the crystal grains on the surface portion of the hot rolled sheet become coarse, and the average grain size in the surface layer region of the base sheet after cold rolling Fine crystal grains having a diameter of 50 μm or less and a maximum particle diameter of 100 μm or less cannot be obtained.
◇ End temperature of hot rolling
The end temperature of hot rolling needs to be 320 to 380 ° C. Since the hot-rolled sheet after hot rolling is usually wound into a coil, the hot-rolled sheet is held at a temperature substantially equal to the hot-rolling end temperature for a certain period of time. When the hot rolling finish temperature is less than 300 ° C., even if the coil is held at this temperature, the core region of the hot rolled plate remains unrecrystallized, and crystal grains having an average grain size of 100 μm or more are obtained. I can't. On the other hand, when the hot rolling finish temperature exceeds 380 ° C., recrystallization occurs when the temperature is maintained at this temperature in the coil state, and the crystal grains on the surface of the hot rolled sheet become coarse, and cold rolling is performed. Fine crystal grains having an average grain size of 50 μm or less and a maximum grain size of 100 μm or less cannot be obtained in the subsequent surface layer region of the base plate.
◇ Final path distortion speed
The strain rate of the final pass of hot rolling needs to be 15 / sec or more. As described above, the strain rate has parameters such as strain and rolling time, and is a function of the rolling speed, the roll diameter, the amount of reduction, and the like. When the strain rate is less than 15 / sec, (1) sufficient processing strain cannot be obtained, the crystal grains on the surface of the hot-rolled plate become coarse, and the average grain size in the surface layer region of the cold-rolled plate Fine crystal grains having a maximum grain size of 100 μm or less cannot be obtained. (2) No processing strain is introduced into the core region, the core region of the hot-rolled sheet is not recrystallized, and the average grain size is 100 μm or more. Crystal grains cannot be obtained.
◇ Hot rolled finished plate thickness
The finished thickness of the hot rolling needs to be 4.5 to 10 mm. If the finished plate thickness is less than 4.5 mm, the temperature drop during hot rolling is large, so the hot rolling finish temperature necessary for the present invention cannot be ensured. On the other hand, if the finished plate thickness of hot rolling is thicker than 10 mm, (1) no strain is introduced into the core region and the necessary recrystallized grain size cannot be obtained, and (2) necessary in the subsequent cold rolling. As a result, the number of passes increases, resulting in an increase in cost and at the same time limiting the omission of intermediate annealing.
[0040]
<Cold rolling>
After hot rolling, cold rolling is performed. Simplify the manufacturing process and reduce costs by omitting intermediate annealing during cold rolling. In order to eliminate the hardening due to the rolling process, the cold rolled sheet omitting the intermediate annealing is cold rolled so that at least the temperature of the sheet after the final cold rolling pass becomes equal to or higher than the recovery temperature of the sheet. The recovery temperature of the plate varies depending on the alloy composition of the ingot, the Fe solid solution amount, the Cu solid solution amount, the Zr solid solution amount, and the accumulated strain amount during processing. If the alloy composition and the respective solid solution amounts of Fe, Cu, and Zr are within the specified ranges of the present invention, recovery starts at a temperature of about 100 ° C. with a reduction of 50%. The lower the solid solution amount of Fe, Cu, and Zr, and the higher the degree of processing, the lower the recovery, and the higher the degree of recovery. On the other hand, when the amount of each solid solution of Fe, Cu, and Zr is high, or when the degree of processing is low, the recovery starts at a higher temperature and the degree of recovery is low.
In order to bring the temperature of the plate above the recovery temperature in cold rolling, the following methods are conceivable. For example, the initial temperature of the coil to be cold-rolled is heated to the recovery temperature or higher, and cold rolling is started. However, this method does not provide a significant energy saving effect. In addition, when the initial temperature of the coil to be cold rolled is started from around room temperature, the reduction rate of the cold working is set to be large so that the processing heat is generated on the plate. This method saves energy and reduces the number of rolling operations. For this purpose, the rolling reduction is preferably 40% or more, and more preferably 45% or more.
[0041]
The most preferable method for ensuring the recovery temperature or higher after at least the final pass is to rapidly bring the plate to the recovery temperature or higher with the processing heat due to the deformation while plastically deforming the plate as in the latter case.
For example, when cold rolling is performed at a rolling speed of 500 to 2000 m / min and a 6 mm thick plate at room temperature (40 ° C.) is cold rolled to 3 mm thickness (50% reduction), the plate temperature is The temperature rises to about 100 ° C. Subsequently, when this 100 ° C. plate is rolled to a thickness of 1 mm (rolling rate 67%), the plate temperature rises to about 150 ° C. When the plate that has risen above the recovery temperature is rolled to a thickness of 0.5 mm (rolling ratio 50%), the plate temperature rises to about 170 ° C. When this plate is further rolled as a final roll to a thickness of 0.25 mm (50% reduction), the heat dissipation per unit volume from the plate increases, and the plate temperature becomes about 130 ° C. This plate temperature is sufficient for the recovery. In this case, the amount of processing strain accumulated during cold rolling is also very high.
[0042]
Although the final cold-rolled sheet wound at this temperature is recovered, the amount of residual strain is large. Therefore, during cooling for a long time, such as air cooling, solid solution Si precipitates as simple substance Si. It is easy. Therefore, it is desirable that rapid cooling be performed to 80 ° C. or less immediately after the end of cold rolling or within 10 minutes. As a guideline, the cooling rate for rapid cooling is 5 ° C./min or more. As a method of rapid cooling, a method using a refrigerant such as a method of passing a cooling chamber immediately after the final cold rolling, a method of immersing a wound coil in a refrigerant, a method of applying a refrigerant to the coil, or the like is preferable. In this way, at least after the final cold rolling pass, preferably within 10 minutes, more preferably immediately after the final cold rolling, rapid cooling is performed to suppress precipitation of solute Si into elemental Si.
[0043]
On the other hand, even if the cold rolling process is performed at the above plate temperature, if at least one of the solid solution amounts of Fe, Cu, and Zr is larger than the limit range of the present invention, the solid solution atoms suppress recovery of strain. Therefore, recovery is not performed sufficiently. In this case, it is not appropriate to set the recovery temperature to a high temperature of 190 ° C. or more so as to ensure sufficient recovery, which not only promotes precipitation of simple Si but also deviates from normal cold rolling conditions. .
In the case of cold rolling in consideration of the above conditions, even if the intermediate annealing step is omitted, the tensile strength (tensile strength) of the cold rolled sheet is 145 to 190 MPa, and the amount of simple substance Si is 30 ppm or less. When an anodized film of 0.1 to 1.0 μm is formed on the roughened surface, a simple substance having a circle equivalent diameter and a particle size of 0.5 μm or more is obtained. 200 Si / mm ² The following aluminum alloy support for a lithographic printing plate can be obtained.
[0044]
【Example】
[Example 1]
<Preparation of ingot>
Aluminum alloy melts having various chemical compositions shown in Table 1 were melted. Each molten aluminum alloy was made into an aluminum alloy ingot having a thickness of 560 mm by a semi-continuous casting method, and was made to have a thickness of 540 mm by chamfering on both sides.
[0045]
[Table 1]

[0046]
<Hot rolling>
Next, the above ingot was subjected to a homogenization treatment that was held at a temperature of 500 ° C. for 2 hours, and then the hot rolling start temperature was lowered to 390 ° C. in the same furnace and held for 1 hour. Using a reversible hot rolling mill with a work roll diameter of 900 mmφ, hot rolling is performed under the conditions of 15 rolling passes and a time between passes of 10 seconds to 1.5 minutes to obtain a hot rolled plate having a thickness of 6 mm. It was. Here, the final pass of the hot rolling was reduced from 18 mm thickness to 6 mm thickness (rolling rate 67%), the final pass starting temperature was 360 ° C., and the hot rolling was finished at 350 ° C. The rolling speed of the final pass was 100 m / min. The rolling time is 0.044 seconds, the strain (logarithmic strain) is 1.10, and the strain rate v is 25.0 sec. ^-1 Met.
[0047]
<Cold rolling>
Next, the hot rolled sheet at room temperature (40 ° C.) was cold-rolled. The cold rolling speed was 500 to 2000 m / min. However, the rolling speed was increased as the plate thickness decreased. The cold rolling method was a method in which a cold rolled plate was wound up after each pass to form a coil and used for the next pass.
The first cold rolling pass was performed with a plate thickness of 6 mm → 3 mm. The rolling end temperature was 90 ° C. Immediately, a second cold rolling pass was performed with a plate thickness of 3 mm → 1 mm. The rolling end temperature was 150 ° C. Subsequently, rapid cooling was performed to 110 ° C. at a cooling rate of 10 ° C./min. In the rapid cooling, the coil was placed in the tank and cooled by spraying an oily refrigerant liquid. And the cold rolling 3rd pass was performed by plate | board thickness 1mm-> 0.5mm. The rolling end temperature was 150 ° C. Immediately, the fourth cold rolling pass was performed from 0.5 mm to 0.24 mm. The rolling end temperature was 120 ° C. The coil after the cold rolling was rapidly cooled to room temperature at a cooling rate of 10 ° C./min. The cooling method was the same as the rapid cooling method after the second cold rolling pass. Thereafter, correction was performed by a tension leveler to obtain an aluminum alloy base plate for a lithographic printing plate.
[0048]
<Evaluation of characteristics>
With respect to each of the aluminum alloy base plates of the present invention examples and comparative examples of alloy codes A to J obtained as described above, (A) hot-rolled plate according to the evaluation and measurement methods described in (1) to (10) below , Crystal grain width of the surface portion (crystal grain size perpendicular to the rolling direction) and crystal grain width of the core region, and (B) aluminum alloy base plate obtained by cold rolling, each of Fe, Cu, Zr solid Amount of dissolved Si, the amount of simple Si and the number of simple Si having an average grain size of 0.5 μm or more, the crystal grain width and elongation of the surface layer region, the crystal grain width of the core region, the electrolytic roughened surface after the electrolytic roughing treatment The uniformity, roughness of the roughened appearance, tensile strength, proof stress after burning treatment, and ink stain resistance were evaluated and measured. The results are shown in Table 2.
[0049]
(1) Measurement of crystal grain size of hot rolled sheet
Each aluminum alloy hot-rolled plate is exposed to the surface and core region by electrolytic polishing, etc., anodized with Barker's solution (11 ml / 1 borofluoric acid solution), and then observed with a polarizing microscope It was. The crystal grain width (size in the direction perpendicular to the rolling direction) was measured using a linear method. The observation with a polarizing microscope was performed at a magnification of 400 times, and a line segment having a length of 60 mm (actual length: 150 μm) was measured at 10 positions on the photograph, and the average value was used. Large crystal grains were observed at a low magnification.
[0050]
(2) Measurement of each solid solution amount of Fe, Cu, Zr
The aluminum alloy base plate is dissolved with hot phenol, the dissolved matrix and the intermetallic compound as the dissolution residue are filtered, and the fine intermetallic compound that has passed through the filtration is separated by extraction with a 10% citric acid solution. Each amount of Fe, Cu, and Zr as solid-dissolved elements in the liquid was measured with an ICP emission analyzer.
[0051]
(3) Measurement of the amount of simple Si
Aluminum alloy base plate with HCl: H ₂ O ₂ = Dissolved with a 1: 1 solution, the filter residue was decomposed with NaOH solution, neutralized, and ammonium molybdate was added to produce silicomolybdenum yellow. When the concentration was high, it was reduced with a sulfonic acid reducing solution to produce molybdenum blue, the absorbance was measured, and converted from a calibration curve to obtain the amount of simple Si.
[0052]
(4) Measurement of the number of elemental Si with a particle size of 0.5 μm or more
The base plate for an aluminum alloy support was etched very slowly with 1% NaOH to a depth of 0.5 μm, and then mapping analysis of Fe and Si was performed with an X-ray microanalyzer. Of these, only Si that does not coexist with Fe was used as an average particle diameter by converting the area occupied by the corresponding particles into a circle by using an image analyzer (LUZEX F manufactured by Nireco Co., Ltd.). Those having an equivalent circle diameter of 0.5 μm or more were counted.
The surface etched with 1% NaOH contains intermetallic compounds and simple substance Si, and the particles detected by Fe and Si mapping analysis coincide with the SEM observation images. These remain after etching. And the results of mapping analysis of Fe and Si using an X-ray microanalyzer were considered to exist at an etching depth of 0.5 μm.
[0053]
(5) Measurement of crystal grain size of aluminum alloy base plate
An aluminum alloy base plate is exposed by electrolytic polishing or the like to expose a surface layer region having a depth of 10 μm from the surface and a core region of 120 μm from the surface. After anodizing with Barker's solution (11 ml / 1 borofluoric acid solution), using a polarizing microscope, Crystal grain observation was performed. Using the linear method, the crystal grain width (crystal grain size perpendicular to the rolling direction) and the elongation ratio of the crystal grains in the surface region (the ratio of the length to the crystal grain width. Length = the crystal grain size in the rolling direction) were measured. . In addition, about the crystal grain width, the polarizing microscope observation was performed by 400 time, the measurement about the line segment of length 60mm (actual length of 150 micrometers) on the photograph was performed at ten places, and the average value was used. Large crystal grains were observed at a low magnification. With respect to the elongation rate of the crystal, observation with a polarizing microscope was performed at a magnification of 100, the width and length of 50 arbitrary crystal grains were measured, and the average value was used.
Basically, the crystal grains of the base plate obtained by cold rolling were only stretched by cold rolling, and the crystal grain width was equivalent to the crystal grain width of the hot rolled plate. Furthermore, the elongation of the crystal grains was equivalent to the elongation of the cold-rolled plate from the hot-rolled plate.
[0054]
(6) Evaluation of uniformity of electrolytic roughened surface
The aluminum alloy base plate was subjected to brush graining in a Bamiston / water suspension, and then subjected to alkali etching and desmutting treatment.
Next, electrolytic surface roughening was performed by electrolytic etching using a power source having an electrolytic waveform with alternating polarities in 1% nitric acid so that the amount of electricity during anode becomes 150 coulomb / dm2.
After washing in sulfuric acid, the surface was observed with a scanning electron microscope (SEM). The evaluation was “good (◯)” for those with uniform grain, and “bad (×)” for those with many unetched parts or uneven grain.
[0055]
(7) Evaluation of appearance of electrolytic roughened surface
The aluminum alloy base plate was subjected to brush graining in a Bamiston / water suspension, and then subjected to alkali etching and desmutting treatment.
Next, electrolytic surface roughening was performed by electrolytic etching using a power source having an electrolytic waveform with alternating polarities in 1% nitric acid so that the amount of electricity during anode becomes 150 coulomb / dm2.
After washing in sulfuric acid, an anodized film was formed in sulfuric acid, and the appearance uniformity was evaluated by visual observation of the surface. The evaluation is “good (◯)” when the appearance is uniform, “slightly poor (Δ)” when the streaks are not uniform enough and the appearance is acceptable, and streaks are not uniform. Those in which, for example, were observed were defined as “defective (×)”.
[0056]
(8) Tensile strength measurement
A JIS No. 13 B tensile test piece was prepared from the aluminum alloy base plate, a tensile test was performed, and the tensile strength σ _B Was measured.
[0057]
(9) Measurement of yield strength after burning
After subjecting the aluminum alloy base plate to a burning treatment at 270 ° C. for 7 minutes, a JIS No. 13 B tensile test piece was prepared and subjected to a tensile test. _0.2 Was measured.
[0058]
(10) Evaluation of ink stain resistance
A printing original plate was produced from an aluminum alloy base plate, set on an offset printing machine KOR, printed 100,000 copies, and visually evaluated for the presence of ink stains in non-image areas. As a result, “good (◯)” indicates that no ink smear was observed, “slightly defective (Δ)” indicates that a large amount was observed, and “defective (×)” indicates that a very large amount was observed.
[0059]
[Table 2]

[0060]
As shown in Tables 1 and 2, Sample Nos. I-1 to I-6, which are examples of the present invention, indicate that the chemical composition of the aluminum alloy is within the specified range of the present invention, and within the specified range of the present invention. Due to the hot rolling heating temperature, hot rolling conditions, and cold rolling conditions, the solid solution amount of Fe, Cu, and Zr of the aluminum alloy base plate is within an allowable range, the amount of single Si and 0.5 μm diameter or more Fewer large particles and a crystal grain size within an acceptable range, a uniform electrolytic roughened surface is obtained, the roughened surface has a uniform appearance without streak, has the required strength, and is heat resistant. A base plate excellent in ink stain resistance was obtained.
[0061]
On the other hand, sample numbers I-7 to I-10, which are comparative examples, are hot and cold rolled within the specified range of the present invention because the chemical composition of the aluminum alloy is outside the specified range of the present invention. In spite of the above conditions, the solid solution amount of Fe, Cu, Zr of the aluminum alloy base plate, or the amount of single Si and the number of large particles having a diameter of 0.5 μm or more and the crystal grain size are outside the allowable range. As a result, among the characteristics required for the present invention, the uniform electrolytic roughened surface, or the roughened surface is streaks and the appearance is non-uniform, out of the required strength range, The ink was inferior and the necessary ink stain resistance was not obtained. The individual comparative examples are as follows.
[0062]
Sample number I-7 of the comparative example, because the amount of Mg is more than the specified range of the present invention among the chemical components of the aluminum alloy, even though cold rolling was performed under conditions within the specified range of the present invention, The tensile strength is outside the allowable range.
Sample No. I-8 in Comparative Example has a lower Mg content than the prescribed range of the present invention among the chemical components of the aluminum alloy, so cold rolling and rapid cooling were performed under conditions within the defined range of the present invention. Regardless of this, precipitation during cold rolling caused the amount of simple Si and the number of coarse single Si of 0.5 μm or more to exceed the specified range of the present invention, and the necessary ink stain resistance was not obtained.
Sample No. I-9 in Comparative Example has a larger amount of Zr in the chemical composition of the aluminum alloy than the specified range of the present invention, so the amount of Zr solid solution also increases, and the tensile strength is outside the allowable range of the present invention. It has become.
Sample No. I-10 of the comparative example has a Zr amount of the chemical components of the aluminum alloy that is less than the specified range of the present invention, so that the Zr solid solution amount is also small and the required proof strength after burning cannot be obtained.
[0063]
[Example 2]
<Preparation of ingot>
The chemical composition within the specified range of the present invention is Fe: 0.32 wt%, Si: 0.07 wt%, Cu: 0.012 wt%, Ti: 0.02 wt%, Mg: 0.008 wt%, Zr: 0.0. 013 wt%, B: 0.0004 wt%, balance: A molten aluminum alloy substantially consisting of aluminum and inevitable impurities was melted. This molten metal was made into an aluminum alloy ingot having a thickness of 560 mm by a semi-continuous casting method, and was made to have a thickness of 540 mm by chamfering on both sides.
<Hot rolling>
Next, the aluminum alloy ingot was subjected to a homogenization treatment for 2 hours at various temperatures shown in Table 3 without being homogenized, and then to various hot rolling start temperatures shown in Table 3. Hold for 1 hour. Using a reversible hot rolling mill with a work roll diameter of 900 mmφ, hot rolling was performed under the conditions of 15 rolling passes and a time between passes of 10 seconds to 1.5 minutes, and various thicknesses shown in Table 3 were obtained. A hot rolled sheet was obtained. Table 3 summarizes the homogenization temperature, the hot rolling start temperature, the hot rolling final pass start temperature, the plate thickness before the final pass, the final plate thickness, the final pass strain rate, and the hot rolling end temperature.
[0064]
[Table 3]

[0065]
<Cold rolling>
Next, the hot rolled sheet at room temperature (40 ° C.) was cold-rolled. The cold rolling speed was 500 to 2000 m / min. However, the rolling speed was increased as the plate thickness decreased. The cold rolling method was a method in which a cold rolled plate was wound up after each pass to form a coil and used for the next pass.
The first cold rolling pass was performed with a plate thickness of 6 mm → 3 mm. The rolling end temperature was 90 ° C. Immediately, a second cold rolling pass was performed with a plate thickness of 3 mm → 1 mm. The rolling end temperature was 150 ° C. Subsequently, rapid cooling was performed to 110 ° C. at a cooling rate of 10 ° C./min. The rapid cooling was performed by placing a coil in an oil-based refrigerant liquid spray tank. And the cold rolling 3rd pass was performed by plate | board thickness 1mm-> 0.5mm. The rolling end temperature was 150 ° C. Immediately, a fourth cold rolling pass was performed from 0.5 mm to 0.24 mm. The rolling end temperature was 120 ° C. The coil after the cold rolling was rapidly cooled to room temperature at a cooling rate of 10 ° C./min. The cooling method was the same as the rapid cooling method after the second cold rolling pass. Thereafter, correction was performed by a tension leveler to obtain an aluminum alloy base plate for a lithographic printing plate.
[0066]
<Evaluation of characteristics>
About each aluminum alloy base plate of the present invention example of sample numbers II-1 to II-6 obtained by the above and II-7 to II-15 comparative example, by the evaluation and measurement method explained in Example 1, (A ) The crystal grain width of the surface portion of the hot rolled sheet and the crystal grain width of the core region, (B) The solid solution amount of Fe, Cu, Zr and the amount of simple substance Si for the aluminum alloy base plate obtained by cold rolling In addition, the number of elemental Si having an average grain size of 0.5 μm or more, the crystal grain width in the surface layer region, the elongation rate, the crystal grain width in the core region, the uniformity of the electrolytic roughened surface after the electrolytic roughening treatment, and roughening Evaluation and measurement of appearance uniformity, tensile strength, proof stress after burning treatment, and ink stain resistance were performed. The results are shown in Table 4.
[0067]
[Table 4]

[0068]
In Tables 3 and 4, Sample Nos. II-1 to II-6, which are examples of the present invention, are such that the chemical composition of the aluminum alloy is within the specified range of the present invention, and the hot rolling conditions and cold rolling conditions are By being within the specified range of the present invention, the solid solution amounts of Fe, Cu, and Zr of the aluminum alloy base plate are within the allowable range, and there are few simple Si amounts and large particles having a diameter of 0.5 μm or more. The size is within the allowable range. As a result, a uniform electrolytic roughened surface is obtained, the roughened surface has a uniform appearance without streak, etc., has the required strength, excellent heat resistance, and ink stain resistance. A base plate with good properties was obtained.
[0069]
In contrast, Sample Nos. II-7 to II-15, which are comparative examples, have a hot rolling heating temperature or a hot rolling condition outside the specified range of the present invention. Despite the fact that the hot rolling conditions are within the specified range of the present invention, the solid solution amount of Fe, Cu, Zr of the aluminum alloy base plate, or the amount of single Si and large particles or crystal grain sizes of 0.5 μm diameter or more As a result, among the characteristics required for the present invention, the uniform electrolytic roughened surface, or the roughened surface is streak and the appearance is not uniform, or the required strength Out of range, heat resistance was inferior, and necessary ink stain resistance was not obtained. The individual comparative examples are as follows.
[0070]
Sample No. II-7 of Comparative Example is a cold-rolled base plate because the hot-rolling start temperature is higher than the specified range of the present invention and the crystal grain size of the hot-rolled plate surface portion becomes coarse. In addition, the crystal grains in the surface layer region become coarse, and as a result, streaks are observed on the roughened surface and the appearance becomes non-uniform. Furthermore, the solid solution amount of Fe and Cu has become higher than the specified range of the invention, and the tensile strength is out of the allowable range even if cold rolling is performed under the conditions of the specified range of the present invention. .
Sample No. II-8 of Comparative Example was subjected to homogenization at a temperature exceeding the limit range of the present invention, so that not only the solid solution amount of Fe and Cu became higher than the specified range of the present invention but also fine precipitates. Therefore, even when hot rolling was performed under the conditions within the specified range of the present invention, the crystal grains in the core portion were smaller than the specified range of the present invention. Therefore, even when cold rolling is performed under conditions within the specified range of the present invention, work hardening is promoted and the tensile strength is higher than the allowable range of the present invention.
In Comparative Example Sample No. II-9, the final pass start temperature of hot rolling is higher than the specified range of the present invention, so the crystal grains on the surface of the hot rolled plate become coarse, and as a result, cold The base plate after rolling had streaks on the roughened surface, and the appearance was uneven.
Sample No. II-10 of the comparative example has a very small crystal grain size on the surface of the hot rolled plate because the final pass start temperature and end temperature of the hot rolling are lower than the specified range of the present invention. Since this was not recrystallized, the processing strain was very large in the core region of the base plate, and as a result, the tensile strength was high. Moreover, due to the large processing strain, precipitation of simple Si during cold rolling was promoted, and the ink stain resistance was slightly lowered.
Since the sample number II-11 of the comparative example has a hot rolling final pass start temperature and an end temperature higher than the specified range of the present invention, the crystal grains on the surface of the hot rolled plate become coarse. As a result, the crystal grains in the surface region of the base plate obtained by cold rolling became coarse, streaks were observed on the roughened surface, and the appearance became non-uniform.
Since the sample number II-12 of the comparative example had a low strain rate due to the slow rolling speed of the final hot rolling pass, the end temperature was lower than the specified range of the present invention. For this reason, the crystal grains on the surface of the hot rolled sheet become coarse, and the core region becomes unrecrystallized. As a result, the crystal grains in the surface layer region of the base plate become coarse, streaks appear on the roughened surface and the appearance becomes non-uniform, and the processing strain in the core region of the base plate becomes very large. Therefore, the tensile strength exceeded the specified range of the present invention. In addition, since the processing strain is large, the amount of simple Si increases during rolling, and the ink stain resistance is slightly inferior.
Sample No. II-13 of the comparative example has a low strain rate because the plate thickness before the final pass of hot rolling is small, the crystal grains on the surface of the hot rolled plate become coarse, and the core region has not been re-executed. It becomes a crystal. As a result, the crystal grains in the surface layer region of the support become coarse, streaks appear on the roughened surface and the appearance becomes non-uniform, and processing distortion is very high in the core region of the support. It becomes large and the tensile strength becomes high. In addition, since the processing strain is large, the amount of simple Si increases during rolling, and the ink stain resistance is slightly inferior.
Sample No. II-14 of the comparative example has a low strain rate because the rolling speed of the final hot rolling pass is low, and the crystal grain size on the surface of the hot rolled sheet becomes coarse. As a result, the crystal grains in the support surface layer region become coarse, streaks appear on the roughened surface, and the appearance becomes non-uniform.
Sample No. II-15 of Comparative Example has a hot rolled final plate thickness thinner than the prescribed range of the invention, so the crystal grain size on the surface of the hot rolled plate was small within the prescribed range of the invention. Since the processing strain has been strongly introduced, the processing strain becomes very large in the core region of the support and the tensile strength becomes high.
[0071]
Example 3
<Preparation of ingot>
A molten aluminum alloy having the chemical composition shown in Table 5 within the specified range of the present invention was melted. This molten metal was made into an aluminum alloy ingot having a thickness of 560 mm by a semi-continuous casting method, and was made to have a thickness of 540 mm by chamfering on both sides.
[0072]
[Table 5]

[0073]
<Hot rolling>
Next, the aluminum alloy ingot was subjected to a homogenization treatment of holding at a temperature of 500 ° C. for 2 hours, and then lowered to a hot rolling start temperature of 390 ° C. in the same furnace and held for 1 hour. Using a reversible hot rolling mill with a work roll diameter of 900 mmφ, hot rolling was performed under the conditions of 15 rolling passes and a time between passes of 10 seconds to 1.5 minutes to obtain a hot rolled plate having a thickness of 6 mm. . Here, the final pass of the hot rolling was reduced from 18 mm thickness to 6 mm thickness (rolling rate 67%), the final pass starting temperature was 360 ° C., and the hot rolling was finished at 350 ° C. The rolling speed in the final pass was 100 m / min. The rolling time is 0.044 sec, the strain (logarithmic strain) is 1.10, and the strain rate ε is 25.0 sec. ^-1 Met.
[0074]
<Cold rolling>
Next, the hot rolled sheet at room temperature (40 ° C.) was cold-rolled. The cold rolling speed was 500 to 2000 m / min. However, the rolling speed was increased as the plate thickness decreased. The cold rolling method was a method in which a cold rolled plate was wound up after each pass to form a coil and used for the next pass.
Table 6 shows the conditions in each pass of cold rolling. Sample No. III-1 of the comparative example is shown in Table 6 with 6-pass cold rolling, thickness 6 mm → 3.5 mm → 2 mm → 1.2 mm → 0.7 mm → 0.42 mm → 0.25 mm. Performed at each rolling temperature. For cooling after 2 passes of cold rolling and 4 passes of cold rolling, the coil was forcibly cooled by a fan. The cooling rate by this was 0.2 degreeC / min.
Sample Nos. III-2 and III-3 of Comparative Examples and Sample Nos. III-4 and III-5 of Examples were subjected to 4 passes of cold rolling, thickness 6 mm → 3 mm → 1 mm → 0.5 mm → 0.24 mm. I went there. It carried out at each cold rolling temperature shown in Table 6. When cooling was performed after two passes of cold rolling, the coil was rapidly cooled at a cooling rate of 10 ° C./min until the start of rolling in the third pass of cold rolling. The cooling method after the final four cold rolling passes is to cool rapidly to room temperature at a cooling rate of 10 ° C./min, by placing a coil in an oil-based refrigerant liquid spray tank, The forced cooling was performed at 2 ° C./min, and the method was air cooling with a fan. Table 6 summarizes the cold rolling temperatures and cooling rates when cooling is performed in the comparative examples and examples.
Thereafter, correction was performed with a tension leveler to obtain a base plate for an aluminum alloy support for a lithographic printing plate.
[0075]
[Table 6]

[0076]
<Evaluation of characteristics>
About each aluminum alloy base plate of the present invention example and comparative example of sample numbers III-1 to III-5 obtained by the above, by the evaluation and measurement method described in Example 1, the surface of (A) hot rolled plate Crystal grain width of core part and crystal grain width of core region, (B) about aluminum alloy base plate obtained by cold rolling, each solid solution amount of Fe, Cu, Zr, simple substance Si amount and average grain size 0.5 μm The number of the above single Si, the crystal grain width of the surface layer region, the elongation rate, the crystal grain width of the core region, the uniformity of the electrolytic roughened surface after the electrolytic roughening treatment, the uniformity of the roughened appearance, the tensile strength The proof stress after burning treatment and the ink stain resistance were evaluated and measured. The results are shown in Table 7.
[0077]
[Table 7]

[0078]
In Tables 5, 6, and 7, sample numbers III-4 to III-5, which are examples of the present invention, indicate that the chemical composition of the aluminum alloy is within the specified range of the present invention, and hot rolling within the specified range of the present invention. The amount of solid solution of Fe, Cu, Zr in the base plate for the support is within an allowable range due to the heating temperature, the hot rolling conditions, and the cold rolling conditions. The number of Si particles is also within the specified range of the present invention, and because the crystal grain size is within the allowable range, a uniform electrolytic roughened surface is obtained, and the roughened surface is uniform in appearance without streak, A base plate having the required strength, excellent heat resistance, and good ink stain resistance was obtained.
[0079]
On the other hand, sample numbers III-1 to III-3 which are comparative examples have cold rolling conditions, or cooling conditions during or after cold rolling are outside the specified range of the present invention. Regardless of the chemical composition of the aluminum alloy within the specified range, the heating temperature for hot rolling, and the hot rolling conditions, the amount of single Si in the base plate for the support and the number of large single Si particles other than 0.5 μm in diameter are large. Out of the allowable range of the present invention, as a result, among the characteristics required for the present invention, the necessary ink stain resistance could not be obtained, or it was out of the required tensile strength range. The individual comparative examples are as follows.
[0080]
Since the sample number III-1 of the comparative example does not reach the recovery temperature or higher in the cold rolling, the tensile strength becomes higher than the specified range of the present invention.
Sample numbers III-2 and III-3 of the comparative examples were used in the cold rolling in which all cold rolling 4 passes were continuously performed and a cold rolling temperature equal to or higher than the recovery temperature was obtained. Since rapid cooling was not performed after cold rolling and sufficient cooling was not performed by forced cooling with a fan, the amount of single Si and the number of large single Si particles having a diameter of 0.5 μm or more were outside the allowable range of the present invention. As a result, the necessary ink stain resistance among the characteristics required for the present invention could not be obtained.
[0081]
【The invention's effect】
According to the present invention, the uniformity of the roughened surface and the uniformity of the appearance are high, and the roughening treatment does not cause processing unevenness such as streak and image quality unevenness, and has both necessary strength and bending workability. Therefore, there is provided an aluminum alloy base plate for a lithographic printing plate having an appropriate range of tensile strength and sufficient strength after burning, and having excellent ink stain resistance.

Claims (4)

An aluminum alloy base plate for a lithographic printing plate,
(1) The following ingredients:
Fe: 0.10 to 0.40 wt%,
Si: 0.03-0.15 wt%,
Cu: 0.004 to 0.020 wt%,
Ti: 0.01 to 0.05 wt%,
Mg: 0.002-0.02 wt%,
Zr: 0.001 to 0.030 wt%,
B: 0.0001 to 0.02 wt%, and the balance: aluminum and inevitable impurity elements, provided that
Fe solid solution amount is less than 30ppm,
Cu solid solution amount is less than 100ppm,
Zr solid solution amount is less than 200ppm,
Fe solid solution amount + (1/2) Zr solid solution amount ≧ 25 ppm,
(2) The surface layer region from the plate surface to a depth of at least 20 μm has the following conditions (A) and (B)
(A) The crystal grain width sD in the direction perpendicular to the rolling direction is less than 50 μm on average and less than 100 μm on the maximum, and
(B) The grain length sL in the rolling direction is 10 times or more than the grain width sD,
A cold-rolled processed structure satisfying
(3) The crystal grain width cD in the direction perpendicular to the rolling direction in the core region having a thickness of 2/3 or more of the plate thickness at the center of the plate thickness is 100 μm or more on average.
(4) The plate thickness is 0.1 to 0.5 mm, the tensile strength is 145 to 190 MPa, the proof stress after burning at 270 ° C. for 7 minutes is 100 MPa or more,
(5) The amount of elemental Si is 30 ppm or less, and the number of elemental Si having a circle equivalent diameter and a particle diameter of 0.5 μm or more per 200 μm depth is 0.5 / m ² or less per 0.5 μm depth of the base plate.
An aluminum alloy base plate for a lithographic printing plate characterized by the above. In the method for producing an aluminum alloy base plate for a lithographic printing plate,
Fe: 0.10 to 0.40 wt%,
Si: 0.03-0.15 wt%,
Cu: 0.004 to 0.020 wt%,
Ti: 0.01 to 0.05 wt%,
Mg: 0.002-0.02 wt%,
Zr: 0.001 to 0.030 wt%,
B: 0.0001 to 0.02 wt%, and balance: hot rolling after aluminum alloy slab composed of aluminum and inevitable impurity elements is subjected to homogenization treatment at a temperature of less than 550 ° C. And then cold rolling and correcting as necessary,
The above hot rolling is performed under the following conditions:
Hot rolling start temperature: 300-480 ° C.
Starting temperature of the final pass: 300-380 ° C
End temperature of the final pass: 320-380 ° C
Strain rate of final pass: 15 / sec or more, and plate thickness after hot rolling: 4.5 to 10 mm,
And then
The cold rolling is performed without intermediate annealing.
A method for producing an aluminum alloy base plate for a lithographic printing plate. The plate temperature at least after the final pass of the cold rolling is not less than the recovery temperature and less than 190 ° C , and rapid cooling is performed at a cooling rate of 5 ° C / min or more within 10 minutes after the final pass. Item 3. A method for producing an aluminum alloy base plate for a lithographic printing plate according to Item 2. Method of manufacturing an aluminum alloy material plate for a lithographic printing plate as claimed in claim 3, wherein the recovery temperature after the cold rolling is 100 ° C. or higher.