JP4313526B2 - Aluminum plate for lithographic plate, method for producing the same, and lithographic plate - Google Patents

Description

【００２８】
（実施形態２）
図２は、本発明の一実施形態である平版の模式的な断面図である。
図２において本実施形態の平版２０は、前記実施形態１で説明し図１に示した平版用アルミニウム基板１０の陽極酸化皮膜１２上に感光膜２１が形成されてなっている。この感光膜２１は、ジアゾニウム塩系の感光剤を、目付け量が０．２g/m²となるようにバーコーターを用いてで塗布し形成したものである。
図２において符号１４は実施形態１で説明した何れかの元素を含む成分を粒塊として示しているが実際には陽極酸化皮膜１２の組織中に一様に分布している。
【００２９】
表１の実施例１〜実施例５、及び比較例１〜比較例５として示した平版用アルミニウム基板を用い、それぞれの陽極酸化皮膜上に前記と同様にして感光膜を形成し、平版を製造した。得られたそれぞれの平版について感光膜の接着性を以下の方法で評価した。
それぞれの平版を５０℃の湿潤環境に２４時間放置した後、感光膜の上からカッターで１mm角の升目を１００個形成し、セロファンテープによる剥離試験を行った。試験結果は
剥離面積が０％のものを◎、
５％未満のものを○、
５％以上２０％未満のものを△、
２０％以上のものを×
と判定した。接着性の評価結果を表１に示す。
【００３０】
それぞれの平版を同一条件でパターン露光し、現像して非画像部の感光膜を除去し、印刷原版を作成した。得られた印刷原版を印刷機にセットし、印刷原版に湿し水を施した後油性インクを展着し、コート紙に印刷した。
【００３１】
図３は、実施例の平版を用いて作成した印刷原版に湿し水と油性インクとを施した状態を示している。図３において、実施例の印刷原版３０は、平版の感光膜２１の一部がパターン露光と現像処理により除去されて陽極酸化皮膜１２の一部が露出し、露出部２２を形成している。この印刷原版３０の表面を水で湿らせた上で油性インクを塗布すると、油性インクは親油性の感光膜２１上に展着してインク膜３１を形成する。一方、露出部２２は親水性であるから前記の湿し水によって水膜３２が形成されていて油性インクをはじく。これによって印刷原版３０上にインクの乗った画像部とインクが乗らない非画像部とからなるパターンが形成される。この上に紙を置いて押圧すればインク層３１が紙に転写して文字・画像が印刷される。
【００３２】
それぞれ表１の実施例１〜実施例５、及び比較例１〜比較例５に対応する印刷原版を用いて印刷を繰り返し、耐刷性を評価した。耐刷性の評価は、
６万枚以上印刷しても画像に乱れが認められなかったものを◎、
４万枚以上６万枚の間で画像の乱れが認められなかったものを○、
４万枚未満で画像に乱れが生じたものを×と判定した。耐刷性の評価結果を表１に示す。
【００３３】
表１に示した測定・評価結果から、実施例１〜実施例５の平版用アルミニウム基板は、膜厚が０．００８μm〜２μmの範囲内であり、有孔度が３０％以下であり、かつＳｉ、Ｐ、Ｂ、Ｓ、又はＣのうち少なくとも１種の元素を成分として合計で５０ppm以上含有していることによって、陽極酸化皮膜１２の耐摩耗性及び陽極酸化皮膜１２と感光膜２１との接着性が共に良好〜優秀であり、結果として印刷原版としての耐刷性が何れも高い評価結果を得た。特に実施例２及び実施例３は陽極酸化皮膜に含まれる元素がそれぞれＳｉ又はＰであることによって、６万枚以上の優れた耐刷性が得られた。
【００３４】
一方、比較例１は、膜厚が薄すぎることによって特に陽極酸化皮膜の耐摩耗性が劣り、４万枚未満の印刷回数で基材のアルミニウム層が露出し、非画像部に水膜が形成されなくなって、耐刷性が×となった。比較例２は、電解が過度に進み有孔度が３０％を越えたことにより耐摩耗性も接着性も低く、結果として耐刷性が×となった。比較例３は、電解液が前記元素を含まなかったことと、有孔度が比較的小さかったことにより感光膜の接着性が劣り、結果として耐刷性が×となった。比較例４は、有孔度が０％でしかも含有元素量も５０ppm未満であったことにより感光膜の接着性が劣り、結果として耐刷性が×となった。比較例５は、陽極酸化皮膜の含水率が２０％を越えていたことにより感光膜が剥離しやすく、結果として耐刷性が×となった。
【００３５】
以下、本発明を更に詳しく説明する。
本発明に使用するアルミニウム基材としては、純アルミニウムの他に純アルミニウム系のＪＩＳ１０００系合金、Ａｌ−Ｍｎ系のＪＩＳ３０００系合金、あるいはＡｌ−Ｍｇ系のＪＩＳ５０００系合金などが適宜使用でき、材質については特に限定されるものではない。また、これらの合金に溶体化処理、時効処理など種々の調質処理を施したものも使用できる。これら素材の各種圧延板は特に好適である。またこれらアルミニウム基合金のクラッド材も使用できる。
【００３６】
前記アルミニウム基材には、陽極酸化処理に先立って前処理を施すことが好ましい。前処理は特に限定されるものではないが、例えばアルミニウム基材表面の不均質な酸化膜を除去するため弱アルカリ性の脱脂液などで洗浄した後、水酸化ナトリウム水溶液中でアルカリエッチングを施して粗面化し、次いで基材表面に付着した溶解残渣を除去するため硝酸水溶液中でデスマット処理を施すことが好ましい。また、前記脱脂液による洗浄後に酸洗浄などを行ってもよい。前記の粗面化処理はアルミニウム基材に比較的粗大な凹凸を形成するものであり、この粗大な凹凸は感光膜を陽極酸化皮膜に物理的に結合させるアンカーとしての効果を有する。従って粗面化処理は感光膜の接着性を向上させる観点から好ましくはあるが、高精度の解像度が要求される平版では施せない場合もある。前記の何れの前処理も、本発明にとって本質的なものではない。
【００３７】
次に、前処理が施されたアルミニウム基材を電解質溶液（電解液）中で電解し、表面にアルミニウムの酸化皮膜を形成するための陽極酸化処理を行う。
このとき用いる電解質としては、水溶性であって、Ｓｉ、Ｐ、Ｂ、Ｓ、及びＣのうち少なくとも１種の元素を塩基成分として含み、かつ生成した酸化皮膜が当該電解液に溶解しにくいものが選ばれる。本発明の製造方法に用いるに好適な前記元素を含む電解質としては、例えばケイ酸塩（Ｓｉ）、リン酸塩（Ｐ）、ホウ酸塩（Ｂ）、硫酸塩（Ｓ）、有機酸塩（Ｃ）などを挙げることができる。有機酸塩の例としては、例えばアジピン酸塩、マレイン酸塩、安息香酸塩、フタル酸塩、酒石酸塩、クエン酸塩、マロン酸塩などを挙げることができる。
【００３８】
前記の陽極酸化処理は通常、電解浴槽中で当該アルミニウム基材を陽極とし炭素板を陰極として行われる。電解条件は、用いる電解質溶液の種類や求める陽極酸化皮膜の特性に応じて実験的に決定される。何れの場合も、生成した陽極酸化皮膜の膜厚が０．００８μm〜２μmの範囲内となり、有孔度が３０％以下となり、かつＳｉ、Ｐ、Ｂ、Ｓ、及びＣのうち少なくとも１種の元素が合計で５０ppm以上含有されるような電解条件が選択される。
【００３９】
前記の電解質溶液中でアルミニウム基材を陽極として電解すると、アルミニウム基材の表面は電解酸化されて酸化アルミニウムに変化すると共に、電解液中の前記元素を含む塩基イオンが＋電荷を有するアルミニウム基材に吸着され、基材の表面に露出した末端アルミニウム原子の一部と結合し、前記元素を含む金属化合物を形成すると考えられる。
【００４０】
これらの電解液を用いてアルミニウム又はアルミニウム合金からなる基材を陽極酸化すると、電解の初期段階においてバリア層と呼ばれる無孔質の陽極酸化皮膜が成長し、この無孔質の陽極酸化皮膜の成長が所定の膜厚まで進むと、無孔質の皮膜上に多孔質層が急速に成長して分厚い多孔質の陽極酸化皮膜が生成する。そこで、電解条件を調整して多孔質層の成長を制御すると、バリア層の上に比較的薄い多孔質層を形成することができる。多孔質層が比較的薄い段階では有孔度も比較的小さく維持されて微孔質状態となっているので、陽極酸化皮膜全体として、分厚く多孔質層が成長したものより緻密で堅牢な皮膜が形成される。すなわち有孔度が３０％以下の無孔質又は微孔質の陽極酸化皮膜を得るためには、陽極酸化皮膜の成長過程で有孔度が低い状態において電解処理を停止すればよいことになる。
【００４１】
本発明の平版において、陽極酸化皮膜とその上に形成される感光膜との接着性は、一方では陽極酸化皮膜に形成される孔に感光材が食い込むアンカー効果に依存する面もあるが、本発明の主旨は、この接着性を陽極酸化皮膜と感光膜との化学的結合力に依存するところにある。前記の元素を含む陽極酸化皮膜は活性サイトを有していて、有機物質からなる感光膜と水素結合やファンデルワールス力などにより化学的に結合し、強力な接着性を発現する。この接着性は陽極酸化皮膜中に前記元素が５０ppm以上含有されるとき、孔のアンカー効果による以上に強力になることがわかった。陽極酸化皮膜がＳｉ又はＰを含むとき特に接着性が強力になる。
【００４２】
陽極酸化皮膜が前記の元素を５０ppm以上含むようにするには、電解液中の電解質濃度を電解質の種類や電解条件に対応して調整する。通常、電解質濃度は２g/l〜１５０g/l程度とすることが好ましい。一般に電解液中前記元素を含む塩基イオンの濃度が高くなれば陽極酸化皮膜中に取り込まれる元素の量も多くなる。
【００４３】
電解中の電解液温度を高くすると陽極酸化皮膜中に取り込まれる前記元素の濃度も高くなる傾向がある。また電解時の電流密度を高くすると電解面での温度が上昇し、陽極酸化皮膜に取り込まれる前記元素の濃度が高くなる。これらの傾向を勘案して添加する各電解質毎に適正な濃度を決めればよい。一般的には、電解液の温度は３０℃〜６０℃、電流密度は０．３Ａ／ｄｍ²〜１０Ａ／ｄｍ²、 印加電圧は１．４Ｖ〜５７０Ｖの範囲内で適宜選択することが好ましい。陽極酸化処理をするに当たっての留意点は、穏和な条件で陽極酸化皮膜を形成させ、できるだけ孔を生じさせないようにすることである。
前記陽極酸化皮膜の膜厚は電解時間によって調整し、０．００８μm〜２μmの範囲内、好ましくは０．２μm〜０．７μmの範囲内とする。
【００４４】
前記の陽極酸化処理によって得られた陽極酸化皮膜は、厚さの均一な無孔質〜微孔質の皮膜となっている。陽極酸化皮膜の膜厚は０．００８μm〜２μmの範囲内とされている。膜厚が０．００８μm未満では、アルミニウム表面に自然に形成される酸化皮膜の膜厚程度であり、耐摩耗性は得られない。一方、膜厚が２μmを越えると、皮膜中に欠陥が生じやすくなり、皮膜が脆くなって耐久性が劣るようになる。従って、陽極酸化皮膜の適正な膜厚は０．００８μm〜２μmの範囲内、好ましくは０．２μm〜０．７μmの範囲内である。
【００４５】
陽極酸化皮膜の有孔度は３０％以下とされている。有孔度は電解液の種類や電解条件により前記の範囲内となるように調整されるが、アルミニウム又はアルミニウム基合金の表面にはシリコンや鉄などの微量不純物とアルミニウムとの金属間化合物が存在しており、これら不純物の上では陽極酸化皮膜が生成しにくく、陽極酸化皮膜に微小な孔が生じる場合があるので、この点も考慮する必要がある。本発明の平版用アルミニウム基板において陽極酸化皮膜の有孔度はゼロでもよいが、実際上、平版作成時に塗布する感光膜との接着性は、前記元素に依存するばかりでなく、補助的に孔のアンカー効果に依存してもよいので、耐摩耗性に影響を与えない範囲で僅少の孔は存在するほうが好ましい。この観点から有孔度の上限は３０％とされるが、より好ましくは２％〜５％の範囲内である。
【００４６】
前記のように有孔度が小さいか又はゼロの陽極酸化皮膜では、孔中に残存する水分をはじめとする腐食性の不純物も少なく、陽極酸化皮膜の表面に感光膜を形成する工程で加熱しても水分が放出されて感光膜を剥離することはない。
また、従来の多孔質アルマイト皮膜の場合には、感光膜にピンホールや亀裂が生じた際に、腐食性の物質が侵入して下地のアルミニウム基材を腐食させることがあるが、本発明の無孔質〜微孔質陽極酸化皮膜ではバリヤ性が高く、下地のアルミニウム基材の腐食を防ぐことができる。
【００４７】
本発明の平版用アルミニウム基板における陽極酸化皮膜の含水率は、皮膜全体で２０％以下とすることが好ましい。前記のように、陽極酸化皮膜中の水分は主として孔の中に包蔵されているので、有孔度が小さければ含水率も小さくなる。しかし有孔度がゼロと測定されても測定外の微小な孔ないし亀裂は存在し、この中に微量の水分は含まれるので含水率はゼロにならない。いずれにせよ陽極酸化皮膜中の水分は感光膜形成時の加熱により放出され感光膜の剥離、ひいては耐刷性の低下を招く原因となり得るので極力低いことが望ましい。この観点から含水率は５％以下とすることがより好ましい。
【００４８】
感光膜は感光剤塗料を陽極酸化皮膜上に塗布し、必要に応じてベーキング（加熱乾燥）することにより成膜することができる。本発明の平版製造に用いる感光剤は、通常この分野で使用されている感光剤の何れであってもよい。これらの感光剤の例としては例えばジアゾニウム塩系、アジド化合物系、光量化型化合物系、光重合型感光剤、及びこれらの樹脂組成物を挙げることができる。感光剤塗料の塗布方法としては、バーコート、ロールコート、ナイフコート、スピンコート、オフセットコート、スクリーンコートなど、従来この分野で用いられている塗布方法が何れも使用可能である。本発明の平版を用いて印刷原版を作成する方法、及びこれを用いた印刷方法は従来と変わらない。
【００４９】
【発明の効果】
本発明の平版用アルミニウム基板は陽極酸化皮膜の膜厚が０．００８μｍ〜２μｍの範囲内であり、有孔度が２％以下であり、かつ、Ｐ、Ｂ、Ｓ、又はＣのうち少なくとも１種の元素を成分として合計で５０ｐｐｍ以上含有してなるものであるので陽極酸化皮膜の耐摩耗性が高く、本発明の平版用アルミニウム基板の上に感光膜を形成してなる平版は感光膜と陽極酸化皮膜との接着性が良好であり、従って本発明の平版を用いて作成した印刷原版は耐刷性が優れている。
また、十分な接着性の確保と皮膜脆化の防止とを両立させる面から、陽極酸化皮膜に含有されるＰ、Ｂ、Ｓ、又はＣのうち少なくとも１種の元素を成分として２０００〜２００００ｐｐｍ含有してなることが好ましい。
また、接着性向上の面から、陽極酸化皮膜の含水率を１〜２％とすることが好ましい。
【図面の簡単な説明】
【図１】 本発明の一実施形態である平版用アルミニウム基板の１切片を示す模式的な斜視図。
【図２】 本発明の一実施形態である平版の模式的な断面図。
【図３】 前記の平版を用いて作成した印刷原版に湿し水と油性インクとを施した状態を示す断面図。
【図４】 従来の平版を用いて作成した印刷原版に湿し水と油性インクとを施した状態を示す断面図。
【符号の説明】
１０…平版用アルミニウム基板。１１…アルミニウム基材。１２…陽極酸化皮膜。１３…孔。１４…成分。２０…平版。２１…感光膜。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithographic aluminum substrate excellent in printing durability when used as a lithographic plate, a method for producing the same, and a lithographic plate using the aluminum substrate.
[0002]
[Prior art]
A lithographic plate used as a printing original plate is generally a porous material called anodized by, for example, subjecting the surface of an aluminum or aluminum-based alloy plate to surface roughening usually by electrolytic etching and electrolytic treatment in an electrolyte containing sulfate, for example. It is manufactured by forming a quality anodic oxide film and forming a photosensitive film thereon. In printing, first, this lithographic plate is subjected to pattern exposure, and development processing is performed to prepare a printing original plate. When the surface of the printing original plate is moistened with water and then the oil-based ink is applied, as shown in FIG. 4, the portion where the photosensitive film 121 remains on the porous anodic oxide film (alumite layer) 112 as a result of the development process is the parent. Since it is oily, the oil-based ink spreads to form the ink layer 31, and the alumite layer 112 is exposed and the exposed portion 122 is formed in the portion where the photosensitive film has been removed by the development process. The exposed portion 122 is hydrophilic. Therefore, the water film 32 is formed by the dampening water and repels oil-based ink. As a result, a printing pattern is formed on the printing original plate 130, which includes an image portion on which ink is placed and a non-image portion on which ink is not placed. If paper is placed thereon and pressed, the ink layer 31 is transferred to the paper and characters / images are printed.
[0003]
[Problems to be solved by the invention]
In general, a characteristic called “printing durability” is a problem in the printing industry. The printing durability is evaluated by the magnitude of a limit value that can maintain the original pattern (character / image) when printing is repeated many times. Of course, the printing durability is also an important evaluation item even in the lithographic printing plate. Factors that decrease the printing durability of conventional lithographic plates include the following. {Circle around (1)} The shape of the image portion is deformed due to the photosensitive film 121 being peeled off or displaced during development or printing. (2) The hydrophilic exposed portion 122 is worn during printing to expose the low-hydrophilic aluminum base material 11, and a water film is not formed on this portion, so that the non-image portion is contaminated with ink. .
[0004]
Among the above-mentioned problems in the conventional planographic plate, the peeling and displacement of the photosensitive film 121 of (1) is caused by the adhesiveness between the alumite layer 112 and the photosensitive film 121. That is, the hydrophilic alumite layer 112 and the lipophilic photosensitive film 121 are inherently poor in adhesiveness. This bonding is made possible by a large number of holes 113 formed in the alumite layer 112. When a photosensitive agent is applied onto the alumite layer 112 during the formation of the photosensitive film 121, the photosensitive agent bites into the holes 113 and solidifies, and the photosensitive film 121 is bonded to the alumite layer 112 by a so-called anchor effect. Furthermore, since the adhesive force is insufficient only with the holes 113..., The anchor effect is strengthened by previously roughening the aluminum base as described above. By the way, a large number of holes 113 are formed adjacent to each other in the alumite layer 112, and the porosity (total hole area included in the unit surface area) reaches 60% or more. Many of these holes 113 have a hydrophilic wall surface, and the individual holes formed by electrolytic treatment have a deep and complicated tunnel shape, in which moisture and electrolyte are contained in the total of the holes. Some tens of percent of the volume is stored. When the photosensitive film 121 is formed on the alumite layer 112 containing a large amount of moisture, the moisture is released by heating at the time of forming the photosensitive film or frictional heat during printing, and is interposed between the layers of the alumite layer and the photosensitive film. As a result, it was found that the photosensitive film 121 was peeled off or floated.
[0005]
Also, it was found that (2) the problem of wear of the exposed portion 122 is also due to the porosity of the anodized layer 112. That is, as described above, the alumite layer 112 having a porosity of 60% or more has a relatively thick film thickness exceeding 2 μm and is extremely brittle as a whole, and is easily worn or peeled off by external pressure.
The present invention has been made in order to solve the above-mentioned problems. Therefore, the object of the present invention is to improve the printing durability by preventing the peeling of the photosensitive film and improving the wear resistance of the anodized film. An object is to provide a planographic aluminum substrate and a planographic plate using the same.
[0006]
[Means for Solving the Problems]
  In order to solve the above-described problems, the present invention provides an anodized film formed on the surface of a base material made of aluminum or an aluminum-based alloy, and the anodized film has a thickness in the range of 0.008 μm to 2 μm. Yes, porosity (total pore area included in unit surface area)2%OrTsu, PA lithographic aluminum substrate characterized by comprising a total of 50 ppm or more of at least one element selected from B, S, or C as a component.
[0007]
In the planographic aluminum substrate of the present invention, the thickness of the anodized film is in the range of 0.008 μm to 2 μm and the porosity is 30% or less. Compared to the conventional anodized layer with a film thickness exceeding 2μm and porosity of 60% or more, the structure is dense and tough, and when it is used for printing repeatedly as a printing original plate, the exposed part wears and peels off. Hateful. It has also been found that when Si, P, B, S, or C is contained in the component forming the anodized film, the adhesion between the anodized film and the photosensitive film is remarkably enhanced. The fact that the porosity of the anodized film is small is considered to decrease the adhesion between the anodized film and the photosensitive film due to the anchor effect, but the anodized film contains 50 ppm or more in total with the above elements as components. In some cases, it was found that more adhesiveness was ensured by compensating for the lowering of adhesiveness due to a decrease in anchor effect. The reason why the adhesiveness is improved by the above elements is not clear, but it is considered that these elements are coordinated to the aluminum atom as a base component and chemically bonded to the organic component of the photosensitive film.
As described above, in the lithographic aluminum substrate of the present invention, the physical strength of the anodized film is improved to enhance the wear resistance of the exposed portion, and the photosensitive film is chemically bonded to the anodized film. Since the adhesion is enhanced, the printing durability when used repeatedly for printing as a printing original plate is generally improved.
[0008]
When the thickness of the anodized film is less than 0.008 μm, it is almost the same as the film thickness of the oxide film by air, and the wear resistance is low, and when it exceeds 2 μm, the porosity becomes excessively advanced and the porosity is reduced to 30% or less. In any case, the physical strength of the film is insufficient and the printing durability is lowered. From the viewpoint of wear resistance, the film thickness is preferably in the range of 0.2 μm to 0.7 μm.
[0009]
If the porosity of the anodized film exceeds 30%, the amount of water contained in the holes increases and the adhesion between the anodized film and the photosensitive film decreases. The smaller the porosity, the lower the amount of moisture contained and the better the adhesion. From this viewpoint, the porosity is preferably 5% or less.
[0010]
If the total content of Si, P, B, S, or C contained in the anodized film is less than 50 ppm, sufficient adhesion to the photosensitive film cannot be secured in the anodized film having a porosity of 30% or less. When the content of the element exceeded 20000 ppm, the adhesion was hardly improved and the tendency of the anodized film to become brittle was observed. From the viewpoint of ensuring both sufficient adhesion and prevention of film embrittlement, the content of the element in the anodized film is preferably in the range of 2000 ppm to 20000 ppm.
[0011]
In the lithographic aluminum substrate of the present invention, the element is preferably Si or P.
Si and P have been found to be particularly effective in improving both the abrasion resistance of the anodized film and the adhesion of the photosensitive film. Any one of these elements may be contained alone or in combination of both in an anodized film of 50 ppm or more.
[0012]
In the lithographic aluminum substrate of the present invention, the water content of the anodized film is preferably 20% or less.
If the water content exceeds 20%, the moisture is interposed between the anodized film and the photosensitive film as described above, causing a decrease in adhesiveness. A moisture content of 20% or less can be achieved by setting the film thickness of the anodized film to 2 μm or less, setting the porosity to 30% or less, and sufficiently drying the anodized film.
[0013]
  The present invention also provides a surface of a base material made of aluminum or an aluminum-based alloy when the lithographic aluminum substrate is manufactured., P, B, S, or C is anodized in an aqueous solution of an electrolyte containing at least one element as a base component, and the film thickness is within the range of 0.008 μm to 2 μm on the surface of the base material. Degree2%And, PThere is provided a method for producing an aluminum substrate for lithographic printing, in which an anodized film is formed so as to contain a total of 50 ppm or more of at least one element of B, S, or C as a component.
[0014]
According to the production method of the present invention, an electrolyte containing the element as a base component is used, and the voltage, current density, temperature, etc. are almost unchanged without changing the conventional production process for producing the lithographic aluminum substrate. By suitably setting the electrolysis conditions, the lithographic aluminum substrate of the present invention having improved printing durability can be obtained.
[0015]
The present invention further provides a lithographic plate in which a photosensitive film is formed on the anodized film of the lithographic aluminum substrate.
The lithographic plate of the present invention is less susceptible to peeling of the photosensitive film during printing than the conventional lithographic plate in which a photosensitive film is formed on the alumite layer, and is less resistant to abrasion and peeling of the exposed portion of the anodized film exposed by development. The printability is greatly improved.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described by way of specific examples, but these specific examples do not limit the present invention in any way.
(Embodiment 1)
FIG. 1 is a schematic perspective view showing one section of a planographic aluminum substrate according to an embodiment of the present invention. In FIG. 1, an aluminum substrate 10 for lithographic printing according to this embodiment has an anodized film 12 formed on the surface of an aluminum base 11 having a thickness of 0.3 mm. As shown in Example 1 to Example 5 in Table 1, the film thickness of the anodic oxide film 12 is adjusted within the range of 0.008 μm to 2.0 μm.
[0017]
Depending on the manufacturing method described below, minute holes 13 are formed on the surface of the anodized film 12 (see Examples 2 to 5 in Table 1). The porosity of the holes 13, that is, the total area of the holes 13 included in the unit surface area of the anodized film 12 is 30% or less. As shown in Example 1 of Table 1, this embodiment also includes a case where the porosity is zero.
[0018]
As shown in Example 1 to Example 5 in Table 1, this anodic oxide film 12 contains 50 ppm or more of any element of C, Si, P, B, or S as a component 14, respectively. In FIG. 1, the component 14 is shown as an agglomerate for explanation, but actually, it is uniformly distributed in the structure of the anodized film 12.
The anodized film 12 contains moisture in the holes 13. As shown in Examples 1 to 5 of Table 1, the moisture content is 20% or less, and in particular, except in Example 5, it is in the range of 1% to 5%.
[0019]
The lithographic aluminum substrates of Examples 1 to 5 and Comparative Examples 1 to 5 in Table 1 were produced by the method shown below.
(Preparation of aluminum substrate)
As the aluminum base material, a 1050-H18 material having a thickness of 0.3 mm was used, and this was immersed in a 10% aqueous sodium hydroxide solution at 50 ° C. for 10 seconds to perform a roughening treatment. The aluminum substrate was washed with water for 10 seconds and then immersed in a 10% nitric acid solution to perform a desmut treatment. By this desmutting treatment, the dissolved residue adhering to the substrate surface was removed. Subsequently, it was washed with water for 10 seconds and dried at 110 ° C. for 5 minutes to obtain a substrate sample.
[0020]
(Formation of anodized film)
Next, each base material sample is immersed in an electrolytic aqueous solution (electrolyte solution) containing the elements shown in Table 1 as base components in an electrolytic bath, and electrolytic treatment is performed using the aluminum base material as an anode and the carbon plate as a cathode. Each anodized film was formed. After the electrolytic treatment, the plate was washed with water for 10 seconds and then dried at 110 ° C. for 5 minutes to obtain respective lithographic aluminum substrate samples.
[0021]
About the lithographic aluminum substrate samples of Examples 1 to 5 and Comparative Examples 1 to 5, the type of electrolyte used when forming the anodized film, the type of elements contained in this electrolyte The electrolytic voltage, current density, and temperature data are shown in the manufacturing condition column of Table 1.
[0022]
About each obtained lithographic aluminum substrate sample, the film thickness of the anodic oxide film was measured. The measurement was performed by cutting a sample embedded in an epoxy resin with a diamond cutter called a super microtome to create a cross-sectional thin piece and observing it with a transmission electron microscope of 50,000 to 100,000 times. Table 1 shows the film thickness measurement results.
[0023]
The porosity of each lithographic aluminum substrate sample was measured. The measurement was performed by selecting 20 locations on the surface of the sample and observing with a 100,000 times electron microscope, and determining the ratio of the total area of the pores to the total area of the measured anodic oxide film as the porosity. However, the hole was determined based on a diameter of 50 to 2000 mm and a depth exceeding 50 mm. In addition, the portion where the anodized film was discontinuous or irregular due to an intermetallic compound composed of aluminum and impurities present on the surface of the substrate was excluded from the measurement range. The measurement results of the porosity are shown in Table 1.
In addition to the measurement method, the porosity can be obtained from the surface opening state by cross-sectional observation similar to the film thickness measurement.
[0024]
With respect to each of the lithographic aluminum substrate samples, the amount (content) of the element contained in the anodized film was measured. The glow discharge mass meter (GDMS) is used for the measurement, and the contained elements are analyzed from the surface of the anodized film, the etching time where Al and O cross each other is regarded as the film thickness, and the obtained element concentration is averaged with respect to the film thickness. The obtained value was defined as element content. The measurement results of the element content are shown in Table 1 as “element amount”.
The element content can also be measured by using, for example, a secondary ion mass meter (SIMS) other than the measurement method.
[0025]
The water content of the anodized film was measured for each lithographic aluminum substrate sample. The thermogravimetric analyzer is used for the measurement, and the lithographic aluminum substrate sample is heated to 500 ° C. at a rate of 10 ° C./min. The reduced weight is considered to be due to moisture, and the ratio of the weight loss to the weight of the anodized film is determined. The water content was determined. Table 1 shows the measurement results of the moisture content.
[0026]
The wear resistance of the anodized film was evaluated for each of the lithographic aluminum substrate samples. The abrasion resistance test was performed according to JIS H8682. Each sample was installed at an angle of 45 °, and silicon carbide sand was dropped on the sample at a rate of 320 g / min for 1000 seconds. Observe the state of wear after the test,
◎ wear less than 10%
○ 10% or more and less than 30%
X 30% or more
It was determined. Table 1 shows the evaluation results of the wear resistance.
[0027]
[Table 1]

[0028]
(Embodiment 2)
FIG. 2 is a schematic cross-sectional view of a planographic plate that is an embodiment of the present invention.
In FIG. 2, a lithographic plate 20 of this embodiment has a photosensitive film 21 formed on the anodized film 12 of the lithographic aluminum substrate 10 described in the first embodiment and shown in FIG. This photosensitive film 21 is made of a diazonium salt-based photosensitive agent with a basis weight of 0.2 g / m 2.²It was formed by coating with a bar coater so that
In FIG. 2, reference numeral 14 indicates a component containing any of the elements described in Embodiment 1 as agglomerates, but in reality, it is uniformly distributed in the structure of the anodized film 12.
[0029]
Using the lithographic aluminum substrates shown as Examples 1 to 5 and Comparative Examples 1 to 5 in Table 1, a photosensitive film is formed on each anodized film in the same manner as described above to produce a lithographic plate. did. For each of the resulting lithographic plates, the adhesiveness of the photosensitive film was evaluated by the following method.
Each lithographic plate was allowed to stand in a humid environment at 50 ° C. for 24 hours, and 100 squares of 1 mm square were formed on the photosensitive film with a cutter, and a peel test using cellophane tape was performed. The test results are
◎ with 0% peel area
○ less than 5%
△, 5% or more and less than 20%
X 20% or more
It was determined. The adhesive evaluation results are shown in Table 1.
[0030]
Each lithographic plate was subjected to pattern exposure under the same conditions, developed to remove the non-image portion of the photosensitive film, and a printing original plate was prepared. The obtained printing original plate was set in a printing machine, dampening water was applied to the printing original plate, oil-based ink was spread, and printing was performed on coated paper.
[0031]
FIG. 3 shows a state in which dampening water and oil-based ink are applied to the printing original plate produced using the planographic plate of the example. In FIG. 3, in the printing original plate 30 of the embodiment, a part of the lithographic photosensitive film 21 is removed by pattern exposure and development processing, and a part of the anodic oxide film 12 is exposed to form an exposed portion 22. When the surface of the printing original plate 30 is moistened with water and oil-based ink is applied, the oil-based ink spreads on the oleophilic photosensitive film 21 to form an ink film 31. On the other hand, since the exposed portion 22 is hydrophilic, a water film 32 is formed by the dampening water and repels oil-based ink. As a result, a pattern composed of an image portion on which ink is placed and a non-image portion on which ink is not placed is formed on the printing original plate 30. If paper is placed thereon and pressed, the ink layer 31 is transferred to the paper and characters / images are printed.
[0032]
Printing was repeated using printing original plates corresponding to Examples 1 to 5 and Comparative Examples 1 to 5 in Table 1, respectively, and printing durability was evaluated. Evaluation of printing durability is
◎ If you can print more than 60,000 copies,
○ If there is no image distortion between 40,000 and 60,000 images,
An image with less than 40,000 images with a disordered image was judged as x. Table 1 shows the evaluation results of printing durability.
[0033]
From the measurement and evaluation results shown in Table 1, the planographic aluminum substrates of Examples 1 to 5 have a film thickness in the range of 0.008 μm to 2 μm, a porosity of 30% or less, and By containing 50 ppm or more in total of at least one element of Si, P, B, S, or C as a component, the wear resistance of the anodized film 12 and the anodized film 12 and the photosensitive film 21 Both the adhesive properties were good to excellent, and as a result, the printing durability as a printing original plate was highly evaluated. In particular, in Examples 2 and 3, excellent printing durability of 60,000 sheets or more was obtained because the element contained in the anodized film was Si or P, respectively.
[0034]
On the other hand, in Comparative Example 1, since the film thickness is too thin, the wear resistance of the anodized film is particularly inferior, and the aluminum layer of the base material is exposed with the number of printing less than 40,000 sheets, and a water film is formed in the non-image area. As a result, the printing durability became x. In Comparative Example 2, the electrolysis progressed excessively and the porosity exceeded 30%, so both the wear resistance and the adhesiveness were low, and as a result, the printing durability was x. In Comparative Example 3, the adhesiveness of the photosensitive film was inferior due to the fact that the electrolytic solution did not contain the element and the porosity was relatively small, and as a result, the printing durability was x. In Comparative Example 4, the porosity was 0% and the element content was also less than 50 ppm, so that the adhesion of the photosensitive film was inferior, and as a result, the printing durability was x. In Comparative Example 5, since the moisture content of the anodic oxide film exceeded 20%, the photosensitive film was easily peeled off, and as a result, the printing durability was x.
[0035]
Hereinafter, the present invention will be described in more detail.
As the aluminum substrate used in the present invention, in addition to pure aluminum, a pure aluminum-based JIS1000-based alloy, an Al-Mn-based JIS3000-based alloy, or an Al-Mg-based JIS5000-based alloy can be used as appropriate. Is not particularly limited. Also, those alloys subjected to various tempering treatments such as solution treatment and aging treatment can be used. Various rolled plates of these materials are particularly suitable. Further, a clad material of these aluminum base alloys can also be used.
[0036]
The aluminum substrate is preferably pretreated prior to the anodizing treatment. The pretreatment is not particularly limited. For example, after washing with a weak alkaline degreasing solution to remove a heterogeneous oxide film on the surface of the aluminum substrate, the surface is roughened by alkaline etching in an aqueous sodium hydroxide solution. It is preferable to perform a desmut treatment in an aqueous nitric acid solution to remove the dissolved residue adhering to the substrate surface and then adhering to the substrate surface. Further, acid cleaning or the like may be performed after the cleaning with the degreasing liquid. The roughening treatment forms relatively coarse irregularities on the aluminum substrate, and the coarse irregularities have an effect as an anchor that physically bonds the photosensitive film to the anodized film. Accordingly, the surface roughening treatment is preferable from the viewpoint of improving the adhesiveness of the photosensitive film, but it may not be performed on a lithographic plate that requires high-precision resolution. None of the above pretreatments are essential to the present invention.
[0037]
Next, the pretreated aluminum base material is electrolyzed in an electrolyte solution (electrolytic solution), and an anodizing treatment for forming an aluminum oxide film on the surface is performed.
The electrolyte used at this time is water-soluble and contains at least one element of Si, P, B, S, and C as a base component, and the generated oxide film is difficult to dissolve in the electrolyte. Is selected. Examples of the electrolyte containing the element suitable for use in the production method of the present invention include silicate (Si), phosphate (P), borate (B), sulfate (S), and organic acid salt ( C). Examples of the organic acid salt include adipate, maleate, benzoate, phthalate, tartrate, citrate, malonate and the like.
[0038]
The anodizing treatment is usually performed in an electrolytic bath using the aluminum base as an anode and a carbon plate as a cathode. The electrolysis conditions are experimentally determined according to the type of electrolyte solution used and the characteristics of the desired anodic oxide film. In any case, the thickness of the produced anodic oxide film is in the range of 0.008 μm to 2 μm, the porosity is 30% or less, and at least one of Si, P, B, S, and C The electrolysis conditions are selected so that the elements contain a total of 50 ppm or more.
[0039]
When electrolysis is performed using the aluminum base as an anode in the electrolyte solution, the surface of the aluminum base is electrolytically oxidized to change to aluminum oxide, and the base ion containing the element in the electrolytic solution has a positive charge. It is considered that the metal compound containing the element is formed by binding to a part of the terminal aluminum atoms that are adsorbed on the surface and exposed on the surface of the substrate.
[0040]
When a substrate made of aluminum or an aluminum alloy is anodized using these electrolytes, a nonporous anodized film called a barrier layer grows in the initial stage of electrolysis, and this nonporous anodized film grows. As the film thickness reaches a predetermined film thickness, the porous layer rapidly grows on the nonporous film to form a thick porous anodic oxide film. Therefore, when the electrolytic conditions are adjusted to control the growth of the porous layer, a relatively thin porous layer can be formed on the barrier layer. When the porous layer is relatively thin, the porosity is kept relatively small and is in a microporous state, so the whole anodized film has a denser and more robust film than the thickly grown porous layer. It is formed. That is, in order to obtain a nonporous or microporous anodic oxide film having a porosity of 30% or less, the electrolytic treatment should be stopped in a state where the porosity is low during the growth process of the anodic oxide film. .
[0041]
In the lithographic plate of the present invention, the adhesion between the anodized film and the photosensitive film formed thereon depends on the anchor effect that the photosensitive material bites into the holes formed in the anodized film. The gist of the invention is that this adhesion depends on the chemical bonding force between the anodized film and the photosensitive film. The anodic oxide film containing the above elements has active sites, and is chemically bonded to a photosensitive film made of an organic material by hydrogen bonding, van der Waals force, etc., and exhibits strong adhesiveness. It has been found that this adhesion becomes stronger when the above elements are contained in the anodized film in an amount of 50 ppm or more than by the anchor effect of the holes. The adhesion becomes particularly strong when the anodized film contains Si or P.
[0042]
In order for the anodic oxide film to contain 50 ppm or more of the above elements, the electrolyte concentration in the electrolytic solution is adjusted in accordance with the type of electrolyte and the electrolysis conditions. Usually, the electrolyte concentration is preferably about 2 g / l to 150 g / l. Generally, when the concentration of the base ion containing the element in the electrolytic solution increases, the amount of the element taken into the anodized film also increases.
[0043]
When the electrolyte temperature during electrolysis is increased, the concentration of the element taken into the anodized film tends to increase. Further, when the current density during electrolysis is increased, the temperature on the electrolysis surface increases, and the concentration of the element taken into the anodized film increases. Considering these tendencies, an appropriate concentration may be determined for each electrolyte to be added. In general, the temperature of the electrolyte is 30 ° C. to 60 ° C., and the current density is 0.3 A / dm.²-10 A / dm²The applied voltage is preferably selected as appropriate within the range of 1.4V to 570V. The point to be noted in performing the anodizing treatment is to form the anodized film under mild conditions so as not to generate pores as much as possible.
The film thickness of the anodized film is adjusted according to the electrolysis time, and is in the range of 0.008 μm to 2 μm, preferably in the range of 0.2 μm to 0.7 μm.
[0044]
The anodized film obtained by the anodizing treatment is a nonporous to microporous film having a uniform thickness. The thickness of the anodized film is in the range of 0.008 μm to 2 μm. When the film thickness is less than 0.008 μm, it is about the film thickness of an oxide film that is naturally formed on the aluminum surface, and wear resistance cannot be obtained. On the other hand, when the film thickness exceeds 2 μm, defects are likely to occur in the film, the film becomes brittle and the durability becomes inferior. Therefore, an appropriate film thickness of the anodized film is in the range of 0.008 μm to 2 μm, preferably in the range of 0.2 μm to 0.7 μm.
[0045]
The porosity of the anodized film is 30% or less. Porosity is adjusted to be within the above range depending on the type of electrolytic solution and electrolysis conditions, but there is an intermetallic compound of aluminum and trace impurities such as silicon and iron on the surface of aluminum or aluminum-based alloy Therefore, it is difficult to form an anodic oxide film on these impurities, and minute holes may be formed in the anodic oxide film. This point needs to be taken into consideration. In the lithographic aluminum substrate of the present invention, the porosity of the anodic oxide film may be zero, but in practice, the adhesiveness with the photosensitive film applied at the time of lithographic preparation is not only dependent on the above elements, but also supplementary pores. Therefore, it is preferable that a small number of holes exist within a range that does not affect the wear resistance. From this viewpoint, the upper limit of the porosity is set to 30%, but more preferably in the range of 2% to 5%.
[0046]
As described above, the anodic oxide film having a low porosity or zero porosity has few corrosive impurities including moisture remaining in the pores, and is heated in the process of forming a photosensitive film on the surface of the anodized film. However, moisture is not released and the photosensitive film is not peeled off.
Further, in the case of a conventional porous anodized film, when a pinhole or crack occurs in the photosensitive film, a corrosive substance may enter and corrode the underlying aluminum substrate. Non-porous to microporous anodic oxide films have high barrier properties and can prevent corrosion of the underlying aluminum substrate.
[0047]
The water content of the anodized film in the lithographic aluminum substrate of the present invention is preferably 20% or less for the entire film. As described above, since the moisture in the anodized film is mainly contained in the pores, the moisture content is reduced if the porosity is small. However, even if the porosity is measured to be zero, there are minute pores or cracks outside the measurement, and a minute amount of moisture is contained therein, so the moisture content does not become zero. In any case, it is desirable that the moisture in the anodic oxide film be as low as possible because it can be released by heating at the time of forming the photosensitive film and cause peeling of the photosensitive film, which in turn causes a decrease in printing durability. From this viewpoint, the water content is more preferably 5% or less.
[0048]
The photosensitive film can be formed by applying a photosensitive agent coating on the anodized film and baking (heat drying) as necessary. The photosensitizer used for the lithographic production of the present invention may be any photosensitizer that is usually used in this field. Examples of these photosensitizers include diazonium salt-based, azide compound-based, light-intensifying compound-based, photopolymerizable photosensitizer, and resin compositions thereof. As a coating method of the photosensitive paint, any of coating methods conventionally used in this field such as bar coating, roll coating, knife coating, spin coating, offset coating, and screen coating can be used. A method for producing a printing original plate using the planographic plate of the present invention and a printing method using the same are not different from conventional ones.
[0049]
【The invention's effect】
  In the lithographic aluminum substrate of the present invention, the thickness of the anodized film is in the range of 0.008 μm to 2 μm, and the porosity is2%OrTsu, P, B, S, or C contains at least one element as a component in total of 50 ppm or more, so the anodized film has high wear resistance, and is exposed on the lithographic aluminum substrate of the present invention. The lithographic plate formed with the film has good adhesion between the photosensitive film and the anodic oxide film, and therefore the printing original plate prepared using the lithographic plate of the present invention has excellent printing durability.
  In addition, from the aspect of ensuring both sufficient adhesion and prevention of film embrittlement, it contains 2000 to 20000 ppm of P, B, S, or C contained in the anodized film as a component. It is preferable that
  Moreover, it is preferable that the moisture content of an anodized film shall be 1-2% from the surface of an adhesive improvement.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing one section of a planographic aluminum substrate according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a planographic plate that is an embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a state in which dampening water and oil-based ink are applied to a printing original plate prepared using the lithographic plate.
FIG. 4 is a cross-sectional view showing a state in which dampening water and oil-based ink are applied to a printing original plate produced using a conventional lithographic plate.
[Explanation of symbols]
10 ... A lithographic aluminum substrate. 11 ... Aluminum base material. 12: Anodized film. 13 ... hole. 14 ... component. 20 ... Flat plate. 21: Photosensitive film.

Claims (5)

An anodized film is formed on the surface of a substrate made of aluminum or an aluminum-based alloy, and the anodized film has a thickness in the range of 0.008 μm to 2 μm, and has a porosity (total included in the unit surface area). hole area) is 2% or less, or one, P, B, S or lithographic an aluminum substrate, characterized by containing more than 50ppm in total of at least one element as a component of C,. The lithographic aluminum substrate according to claim 1, comprising 2000 to 20000 ppm of at least one element selected from P, B, S, and C contained in the anodized film . The lithographic aluminum substrate according to claim 1 or 2, wherein the water content of the anodized film is 1 to 2% . When the lithographic aluminum substrate according to any one of claims 1 to 3 is produced, the surface of the base material made of aluminum or an aluminum-based alloy is at least one element selected from P 2 , B, S, and C. was anodized in an aqueous solution of electrolyte containing as a base component, a surface of the substrate, the film thickness is in the range of 0.008Myuemu～2myuemu, Yuanado becomes 2% or less, or one P, B, S Or a method for producing an aluminum substrate for lithographic printing, wherein the anodized film is formed so as to contain a total of 50 ppm or more of at least one element of C as a component. A lithographic plate, wherein a photosensitive film is formed on the anodized film of the lithographic aluminum substrate according to any one of claims 1 to 3.

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