JP2004009372A - Plate making process and plate making device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a plate making process in which writing can be carried out with an accurate density of image dot even if an ink ejecting means has a variation in the flight characteristics. <P>SOLUTION: In the plate making process for making a print plate by forming an image directly on a plate material with the signals of image data and then fixing the image is carried out in an ink jet system ejecting ink containing a lipophilic component in imaging using an imaging means performing halftone imaging by converting the density level of the image dot into the size of a recording dot, ink ejection means arrangement data indicating correspondence of each image dot and and each ink ejecting means for a plurality of image dots of the image is made previously. An ink ejection means corresponding to each image dot is determined with reference to the arrangement data, and the ink ejection quantity control value of each image dot is determined such that a recording dot size corresponding to each image dot density of the ejecting means thus determined can be obtained utilizing ejection characteristics table of image dot density corresponding to that ejecting means previously determined experimentally and the ink ejection quantity control value. <P>COPYRIGHT: (C)2004,JPO

Description

【００９０】
一般式（Ｉ）において、Ｘ１は−ＣＯＯ−、−ＯＣＯ−または−Ｏ−を表す。Ｒは、炭素数１０〜３２のアルキル基またはアルケニル基を表し、好ましくは炭素数１０〜２２のアルキル基またはアルケニル基を表し、これらは直鎖状でも分岐状でもよく、無置換のものが好ましいが、置換基を有していてもよい。
具体的には、デシル基、ドデシル基、トリデシル基、テトラデシル基、ヘキサデシル基、オクタデシル基、エイコサニル基、ドコサニル基、デセニル基、ドデセニル基、トリデセニル基、ヘキサデセニル基、オクタデセニル基、リノレニル基等が挙げられる。
【００９１】
ａ１およびａ２は、互いに同じでも異なっていてもよく、水素原子、ハロゲン原子（例えば、塩素原子、臭素原子等）、シアノ基、炭素数１〜３のアルキル基（例えば、メチル基、エチル基、プロピル基等）、−ＣＯＯ−Ｚ_１または−ＣＨ_２ＣＯＯ−Ｚ_１〔Ｚ_１は、置換されていてもよい炭素数２２以下の炭化水素基（例えば、アルキル基、アルケニル基、アラルキル基、脂環式基、アリール基等）を表す〕を表す。
【００９２】
Ｚ_１で表される炭化水素基のうち、好ましい炭化水素基としては、炭素数１〜２２の置換されてもよいアルキル基（例えば、メチル基、エチル基、プロピル基、ブチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ドデシル基、トリデシル基、テトラデシル基、ヘキサデシル基、オクタデシル基、エイコサニル基、ドコサニル基、２−クロロエチル基、２−ブロモエチル基、２−シアノエチル基、２−メトキシカルボニルエチル基、２−メトキシエチル基、３−ブロモプロピル基等）、炭素数４〜１８の置換されてもよいアルケニル基（例えば、２−メチル−１−プロペニル基、２−ブテニル基、２−ペンテニル基、３−メチル−２−ペンテニル基、１−ペンテニル基、１−ヘキセニル基、２−ヘキセニル基、４−メチル−２−ヘキセニル基、デセニル基、ドデセニル基、トリデセニル基、ヘキサデセニル基、オクタデセニル基、リノレニル基等）、炭素数７〜１２の置換されてもよいアラルキル基（例えば、ベンジル基、フェネチル基、３−フェニルプロピル基、ナフチルメチル基、２−ナフチルエチル基、クロロベンジル基、ブロモベンジル基、メチルベンジル基、エチルベンジル基、メトキシベンジル基、ジメチルベンジル基、ジメトキシベンジル基等）、炭素数５〜８の置換されてもよい脂環式基（例えば、シクロヘキシル基、２−シクロヘキシルエチル基、２−シクロペンチルエチル基等）、および炭素数６〜１２の置換されてもよい芳香族基（例えば、フェニル基、ナフチル基、トリル基、キシリル基、プロピルフェニル基、ブチルフェニル基、オクチルフェニル基、ドデシルフェニル基、メトキシフェニル基、エトキシフェニル基、ブトキシフェニル基、デシルオキシフェニル基、クロロフェニル基、ジクロロフェニル基、ブロモフェニル基、シアノフェニル基、アセチルフェニル基、メトキシカルボニルフェニル基、エトキシカルボニルフェニル基、ブトキシカルボニルフェニル基、アセトアミドフェニル基、プロピオンアミドフェニル基、ドデシロイルアミドフェニル基等）が挙げられる。
【００９３】
分散ポリマーにおいて一般式（Ｉ）で示される繰り返し単位とともに、他の繰り返し単位を共重合成分として含有してもよい。他の共重合成分としては、一般式（Ｉ）の繰り返し単位に相当する単量体と共重合可能な単量体よりなるものであればいずれの化合物でもよい。
【００９４】
分散ポリマーにおける一般式（Ｉ）で示される重合体成分の存在割合は、好ましくは５０重量％以上であり、より好ましくは６０重量％以上である。
これらの分散ポリマーの具体例としては、実施例で使用されている分散安定用樹脂（Ｑ−１）等が挙げられ、また市販品（ソルプレン１２０５、旭化成（株）製）を用いることもできる。
【００９５】
分散ポリマーは、前記の樹脂（Ｐ）粒子を分散物（ラテックス）等として製造するときには重合に際し予め添加しておくことが好ましい。
分散ポリマーを用いるときの添加量は粒子用樹脂（Ｐ）に対し１〜５０重量％程度とする。
【００９６】
本発明の油性インク中の分散樹脂粒子および着色粒子（あるいは色材粒子）は、好ましくは正荷電または負荷電の検電性粒子である。
これら粒子に検電性を付与するには、湿式静電写真用現像剤の技術を適宜利用することで達成可能である。具体的には、前記の「最近の電子写真現像システムとトナー材料の開発・実用化」１３９〜１４８頁、電子写真学会編「電子写真技術の基礎と応用」４９７〜５０５頁（コロナ社、１９８８年刊）、原崎勇次「電子写真」１６（Ｎｏ．２）、４４頁（１９７７年）等に記載の荷電調節剤などの検電材料および他の添加剤を用いることで行なわれる。
【００９７】
具体的には、例えば、英国特許第８９３４２９号、同第９３４０３８号、同第１１２２３９７号、米国特許第３９００４１２号、同等４６０６９８９号、特開昭６０−１７９７５１号、同６０−１８５９６３号、特開平２−１３９６５号公報等に記載されている。
上述のような荷電調節剤は、担体液体である分散媒１０００重量部に対して０．００１〜１．０重量部が好ましい。更に所望により各種添加剤を加えてもよい。
【００９８】
【実施例】
以下に実施例を示して、本発明を詳細に説明するが、本発明はこれらに限定されるものではない。
まず、インク用樹脂粒子（ＰＬ）の製造例について示す。
【００９９】
＜樹脂粒子（ＰＬ−１）の製造例＞
下記構造の分散安定用樹脂（Ｑ−１）１０ｇ、酢酸ビニル１００ｇおよびアイソパーＨ３８４ｇの混合溶液を窒素気流下撹拌しながら温度７０℃に加温した。重合開始剤として２，２′−アソビス（イソバレロニトリル）（略称Ａ．Ｉ．Ｖ．Ｎ．）０．８ｇを加え、３時間反応した。開始剤を添加して２０分後に白濁を生じ、反応温度は８８℃まで上昇した。更に、この開始剤０．５ｇを加え、２時間反応した後、温度を１００℃に上げ２時間撹拌し未反応の酢酸ビニルを留去した。冷却後２００メッシュのナイロン布を通し、得られた白色分散物は重合率９０％で平均粒径０．２３μｍの単分散性良好なラテックスであった。粒径はＣＡＰＡ−５００（堀場製作所（株）製）で測定した。
【０１００】
【化２】

【０１０１】
上記白色分散物の一部を、遠心分離機（回転数１×１０^４ｒ．ｐ．ｍ．、回転時間６０分）にかけて、沈降した樹脂粒子分を、捕集・乾燥した。樹脂粒子分の重量平均分子量（Ｍｗ：ポリスチレン換算ＧＰＣ値）は２×１０^５、ガラス転移点（Ｔｇ）は３８℃であった。
【０１０２】
次に、油性インクを作成した。
＜油性インク（ＩＫ−１）の作成＞
ドデシルメタクリレート／アクリル酸共重合体（共重合比；９５／５重量比）を１０ｇ、ニグロシン１０ｇおよびシェルゾール７１の３０ｇをガラスビーズとともにペイントシェーカー（東洋精機（株）製）に入れ、４時間分散し、ニグロシンの微小な分散物を得た。
インク用樹脂粒子の製造例１で製造した樹脂粒子（ＰＬ−１）６０ｇ（固体分量として）、上記ニグロシン分散物を２．５ｇ、ＦＯＣ−１４００（日産化学（株）製、テトラデシルアルコール）１５ｇ、およびオクタデセン−半マレイン酸オクタデシルアミド共重合体０．０８ｇをアイソパーＧの１リットルに希釈することにより黒色油性インクを作成した。
【０１０３】
次に、製版装置（図１、図３参照）１のインクジェット描画装置２に上記のように作成した油性インク（ＩＫ−１）２リットルをインクタンクに充填した。ここではインク吐出手段として９００ｄｐｉ、６４チャンネルマルチチャンネルヘッドを使用した。インク温度管理手段として投げ込みヒータと撹拌羽をインクタンク内に設け、インク温度は３０℃に設定し、撹拌羽を３０ｒｐｍで回転しながらサーモスタットで温度コントロールした。ここで撹拌羽は沈降・凝集防止用の攪拌手段としても使用した。またインク流路を一部透明とし、それを挟んでＬＥＤ発光素子と光検知素子を配置し、その出力シグナルによりインクの希釈液（アイソパーＧ）あるいは濃縮インク（上記インク（ＩＫ−１）の固形分濃度を２倍に調整したもの）投入による濃度管理を行った。
【０１０４】
版材として、砂目立ておよび陽極酸化処理を施した０．１２ｍｍ厚みのアルミ版を、製版装置のドラムに設けた機械的装置により版頭および版尻をくわえて装着した。エアーポンプ吸引により版材表面の埃除去を行った後、インク吐出手段を描画位置まで版材に近づけ、製版すべき画像データを画像データ演算制御部に伝送し、その際、インク吐出手段配列データを参照して各々の画像ドットに対応するインク吐出手段をインク吐出手段選択手段で求め、各インク吐出手段に対し吐出特性テーブルからインク吐出量制御値を決定し、ドラムを回転させながら６４チャンネルインク吐出手段を移動させることにより、アルミ版上に前記決定された吐出量の油性インクを吐出して画像を形成した。
この結果、各インク吐出手段の飛翔特性のばらつきが補正され、所望の濃度の描画が行われた。挨による描画不良等も全く見られず、また外気温の変化、製版数の増加によってもドット径変化等による画像劣化は全く見られず、良好な製版が可能であった。
これに対して吐出特性テーブルを備えない製版装置にあっては、各インク吐出手段の飛翔特性のばらつきがそのまま描画されるので、ドッド同士の重なりが生じ、所望の濃度の描画が行われなかった。
【０１０５】
さらにキセノンフラッシュ定着装置（ウシオ電機（株）製、発光強度２００Ｊ／パルス）による加熱により画像を強固にし、刷版を作成した。インクジェット吐出手段を保護するためにインクジェット描画装置を副走査手段ごとドラムと近接した位置から５０ｍｍ退避させ、次に刷版を製版装置から取り出して、オリバー２６６ＥＰＺ印刷機の版胴に装着し印刷をした。
【０１０６】
得られた印刷物は通し枚数一万枚後でも印刷画像に飛びやカスレや、不測のドット重なりがなく、極めて鮮明で所望の濃度の画像であった。
【０１０７】
また、上記同条件において、粘着ローラの粘着力を７ｈＰａ以上１８０ｈＰａ以下（実施例１）、４ｈＰａ以上７ｈＰａ以下（実施例２）、１８０ｈＰａ以上２５０ｈＰａ以下（実施例３）、４ｈＰａ以下（比較例１）、２５０ｈＰａ以上（比較例２）に設定した。この結果、実施例１では版材上に付着した粉塵の殆どが粘着ローラによって吸着除去でき、インク吐出手段に詰まり等の故障が生じず、印刷汚れ等の欠陥の無い鮮明な画像を得ることができた。また、実施例２では、僅かではあるが版板上に粉塵が残存したが、問題の無いレベルであった。更に、実施例３では、印刷条件によっては、僅かではあるが、印刷汚れが見られたが、実用的には問題の無いレベルであった。
これに対して、比較例１では、粉塵の吸着能力が小さく、粉塵除去が不可能であった。また、比較例２では、版材の親水面を傷つけ、印刷時に汚れが発生した。
【０１０８】
【発明の効果】
本発明によれば、画像データの信号に基づき、版材上に直接画像を形成し、該画像を定着して刷版を作成する製版方法であって、前記画像データの各々の画像ドットの濃度レベルを記録ドットの大きさに変換して階調記録する画像形成手段を用いて、前記刷版への画像の形成を、少なくとも親油性成分を含むインクを吐出させるインクジェット方式で行う製版方法において、画像の全部又は一部の複数画像ドットに対し各々の画像ドットと各々のインク吐出手段との対応を示したインク吐出手段配列データを予め作製しておき、このインク吐出手段配列データを参照して各々の画像ドットに対応するインク吐出手段を求め、このインク吐出手段に対応した予め実験的に求めた画像ドット濃度とインク吐出量制御値との吐出特性テーブルを利用して、前記求まった該当するインク吐出手段の各々の画像ドット濃度に対応する記録ドットサイズが得られるように、各々の画像ドットのインク吐出量制御値を決定することにより、インク吐出手段の飛翔特性にばらつきがあっても安価で簡便な方法で画像ドットの濃度が正確な描画を高速で行うことができ、安定した高画質の刷版が得られ、したがって安価で高速の平版印刷が可能となる。
【図面の簡単な説明】
【図１】本発明に用いる製版装置の一例を模式的に示す全体構成図である。
【図２】本発明に用いる製版装置の他の一例を模式的に示す全体構成図である。
【図３】本発明に用いる製版装置の描画部の一例を模式的に示す構成図である。
【図４】本発明に用いるインク吐出手段保護カバーの一実施例を模式的に示す構成図である。
【図５】隣接する記録ドットを描画したときに、それぞれ描画するのに用いたインク吐出手段の特性の差によって、記録ドットの重なり方が変化することを示す模式図である。
【図６】インク吐出手段の走査方法と、それに対応するインク吐出手段配列データの１例を示す模式図である。
【図７】インク吐出手段の別の走査方法と、それに対応するインク吐出手段配列データの別の例を示す模式図である。
【図８】本発明において、吐出特性テーブルやドットオーバーラップ補正テーブルを、実験的に求めるときに使用するグレースケール画像の例を示した模式図である。図８（ａ）はグレースケール画像Ａの全体図、（ｂ）は高濃度部、（ｃ）は低濃度部のそれぞれ拡大図である。
【図９】互いに隣接する２つのインク吐出手段を同一行で記録させた場合を示し、図９（ａ）は両ドッドともに大きくて重なり部分のある高濃度部、（ｂ）および（ｃ）はいずれも一方が大きく、他方が小さなドットで互いに重なる臨界状態の中濃度部、（ｄ）は両ドッドともに小さくて重なり部分のない低濃度部、（ｅ）はグレースケール画像を、それぞれ示している。
【図１０】互いに隣接する２つのインク吐出手段を各行で交互に記録させた場合を示し、図１０（ａ）は両ドッドともに大きくて重なり部分のある高濃度部、（ｂ）および（ｃ）はいずれも一方が大きく、他方が小さなドットで互いに重なる臨界状態の中濃度部、（ｄ）は両ドッドともに小さくて重なり部分のない低濃度部、（ｅ）はグレースケール画像を、それぞれ示している。
【図１１】隣接する記録ドットの重なり合いの例を示す模式図である。
【図１２】吐出特性テーブルを用いてインク吐出量制御値を求める方法の模式図である。
【符号の説明】
１　　　製版装置
２　　　インクジェット描画装置
５　　　定着装置
６　　　版面不感脂化装置
７　　　版材自動給版装置
８　　　版材自動排版装置
９　　　版材（印刷原版）
１０　　粘着性ローラ
１１　　ドラム
１２　　キャップスタンローラ
１３　　アース手段
２１　　画像データ演算制御部
２２　　インク吐出手段
２２１　インク吐出手段保護手段
２３　　油性インク
２４　　インク供給部
２５　　インクタンク
２６　　インク供給装置
２７　　撹拌手段
２８　　インク温度管理手段
２９　　インク濃度制御手段
３０　　エンコーダー
３１　　インク吐出手段離接装置
３２　　インク吐出手段副走査手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plate-making method and a plate-making apparatus for performing digital plate-making, and more particularly, to a plate-making method and a plate-making apparatus having good plate-making image quality and printing image quality using an oil-based ink.
[0002]
[Prior art]
In lithographic printing, printing ink receptivity and printing ink repellent areas are provided on the surface of the printing plate corresponding to the image original, and printing is performed by attaching the printing ink to the ink receptivity areas. Usually, hydrophilic and oleophilic (ink-accepting) areas are formed in an image-like manner on the surface of the printing plate, and the hydrophilic areas are made ink repellent using dampening water.
[0003]
To record an image on a printing original (plate making), the image original is output to a silver salt photographic film in an analog or digital manner, through which a diazo resin or a photopolymerizable photopolymer photosensitive material (printing original) is exposed. The general method is to elute and remove the non-image area mainly using an alkaline solution.
[0004]
In recent years, in the planographic printing method, many systems for directly drawing digital image information on a printing original plate have been proposed because of recent demands for improvement of digital drawing technology and process efficiency. This is a technique called CTP (Computer-to-plate) or DDPP (Digital Direct Printing Plate). As a plate making method, for example, there is a system for recording an image in a light mode or a thermal mode using a laser, for example, and some of them are starting to be put into practical use.
[0005]
However, in this plate making method, both the light mode and the heat mode are generally preferable for environmental conservation, since the plate making is performed by dissolving and removing the non-image area by treating with an alkaline developer after laser recording. Absent.
[0006]
On the other hand, the above-described method using a laser is expensive and large, so an attempt has been made to apply an ink jet method which is an inexpensive and compact drawing apparatus.
[0007]
In JP-A-4-97848, a plate drum having a hydrophilic or oleophilic surface is provided in place of a conventional plate cylinder, and an oleophilic or hydrophilic image is formed on the surface by an ink jet method. A method for removing and cleaning the image after completion is disclosed. However, with this method, it is difficult to achieve both printing image removal (that is, ease of cleaning) and printing durability.
[0008]
As described above, when the ink jet method is applied to the plate making process, the development processing required in the conventional plate making operation becomes unnecessary, and thus there are merits such as further system simplification, running cost reduction, plate making time and the like.
[0009]
However, the inkjet method has the disadvantage that the drawing speed is slow, and by changing the size of the drawing dot by adjusting the ink discharge amount and discharge time, the resolution is reduced while maintaining the required number of gradations. Measures to improve speed are necessary.
[0010]
Furthermore, an attempt has been made to further improve efficiency by using two or more ink discharge means simultaneously. In this case, it is possible to draw an image having a dot interval finer than the interval of the ink discharge means by using the interlace scanning method. However, when a plurality of ink ejecting means are used at the same time, drawing unevenness occurs due to a slight difference in the ejecting characteristics. Therefore, it is necessary to produce ink ejecting means having the same ejecting characteristics, resulting in an increase in apparatus cost. It was.
[0011]
In addition, in the case of an ink jet method in which adjacent recording dots are overlapped to form an image, the recording position deviation characteristic of each ink discharging unit slightly causes a combination of ink discharging units corresponding to adjacent recording dots to be adjacent. The amount of recording dots to be overlapped may change, and the image density may be different.
This will be described with reference to FIG. In FIG. 5, it is assumed that there are ink discharge means 1 and ink discharge means 2, and it is assumed that the ink discharge characteristics of the ink discharge means 1 tend to be deflected slightly to the right on the paper surface from the landing target position. It is assumed that it is accurately headed to the landing target position. FIG. 5A shows a case where two normal ink ejection means 2 are adjacent to each other. In this case, of the two ink discharge means, the dot 2L recorded by the left discharge means 2 and the dot 2R recorded by the right discharge means 2 both land on the landing target position on the paper surface. A portion Sa where 2L and 2R overlap has a target area.
On the other hand, FIG. 5B shows a case where two ink ejection means 1 that tend to be deflected to the right are adjacent to each other. The dots 1L recorded by the left ejection means 1 and the dots 1R recorded by the right ejection means 1 are as follows. Both are eccentric from the landing target position. In this case, if the amount of eccentricity is the same, the overlapping portion Sb will be the same amount as Sa.
On the other hand, FIG. 5C shows a case where the ink discharge means 1 is adjacent to the left side of the paper and the ink discharge means 2 is adjacent to the right side. In this case, the dot 1L recorded by the left ejection unit 1 is eccentric to the right from the landing target position, and the center of the dot 2R recorded by the right ejection unit 2 is the landing target position. Therefore, in this case, the overlapping portion Sc is wider than a predetermined area.
Conversely, FIG. 5D shows a case where the ink discharge means 2 is adjacent to the left side of the paper and the ink discharge means 1 is adjacent to the right side. In this case, the dot 1L recorded by the right ejection unit 1 is eccentric to the right from the landing target position, and the center of the dot 2R recorded by the left ejection unit 2 is the landing target position. Therefore, in this case, the overlapping portion Sc is narrower than a predetermined area.
When there is an increase / decrease in the overlapping portion of dots due to the flying characteristics of the ink discharge means, there is a drawback that a predetermined density cannot be obtained.
[0012]
[Problems to be solved by the invention]
The present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is first to provide a digital plate-making method and plate-making apparatus that do not require development processing.
Second, there are provided a plate making method and a plate making apparatus for performing image drawing by an ink jet method that realizes high speed drawing with accurate density of image dots by an inexpensive device and a simple method even if the flight characteristics of the ink discharge means vary. It is to be.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the plate making method according to claim 1 is a plate making method for forming a printing plate by forming an image directly on a plate material based on a signal of image data and fixing the image. Ink containing at least an oleophilic component is used to form an image on the printing plate using image forming means for converting the density level of each image dot of the image data into a recording dot size and recording the gradation. In the plate making method performed by the ink jet method for ejecting ink, ink ejection unit array data indicating correspondence between each image dot and each ink ejection unit is prepared in advance for a plurality of image dots of all or part of the image. The ink discharge means corresponding to each image dot is obtained with reference to the ink discharge means arrangement data, and the image dot density and ink discharge determined in advance experimentally corresponding to this ink discharge means. Using the discharge characteristic table with the amount control value, the ink discharge amount control value of each image dot is obtained so that the recording dot size corresponding to the obtained image dot density of the corresponding ink discharge means can be obtained. It is characterized by determining.
[0014]
3. A plate making apparatus according to claim 2, comprising: an image forming unit that directly forms an image on a plate material based on a signal of image data; and an image fixing unit that fixes the image formed by the image forming unit to obtain a printing plate. The image forming means converts the density level of each image dot of the image data into the size of the recording dot and performs gradation recording, and at least oleophilic In a plate making apparatus that is based on an ink jet system that is ejected from two or more ink ejecting means capable of ejecting ink containing a component simultaneously or sequentially, each image dot in advance for all or part of a plurality of image dots And ink discharge means array data for storing the correspondence between each ink discharge means in the memory and the ink discharge means array data with reference to the ink discharge means array data. The relationship between the ink ejection means selection means for obtaining the ejection means and the ink ejection amount control value corresponding to the image dot density recorded by each ink ejection means prepared for each ink ejection means is experimentally obtained in advance and stored in the memory. Ink discharge for determining an ink discharge amount control value for a recording dot of a target size to be recorded by the ink discharge unit selected by the ink discharge unit selection unit and the stored discharge characteristic table using the discharge characteristic table And a quantity control value determining means.
[0015]
As another invention, the following configuration is conceivable.
(1) In the plate making method according to claim 1, an ink first ejection unit corresponding to each image dot is obtained using the ink ejection unit array data, and the ejection characteristic table of the corresponding ink first ejection unit is used. When the ink discharge amount control value is determined, the ink second discharge means corresponding to the image dot adjacent to the image dot is also obtained, the discharge characteristic table of the ink first discharge means, the ink first discharge means and the ink determined in advance. The ink discharge amount control value of the recording dot corresponding to the corresponding image dot is determined using the dot overlap correction table when the recording dots recorded by the second ejection unit are adjacent to each other.
(2) In the plate making method described above, the dust existing on the plate material surface is removed before and / or during drawing on the plate material by the ink jet method using the ink discharge means and / or at least after the plate making is finished. The ink discharge means is cleaned.
(3) In the plate making apparatus according to claim 2, a third storage device for storing a dot overlap correction table for correcting an error of a recording dot area due to an overlap of adjacent recording dots, and this dot overlap correction table And a third control arithmetic device that corrects the density of the corresponding image dot.
(4) In the plate making apparatus, the direct image forming means includes plate material surface dust removing means for removing dust existing on the plate material surface before and / or during drawing on the plate material.
(5) In the plate making apparatus, at the time of drawing on the plate material, the image forming means performs main scanning by rotation of the plate cylinder on which the plate material is mounted.
(6) In the plate making apparatus, the image forming means performs sub-scanning when the ink discharge means moves in the axial direction of the plate cylinder when drawing on the plate material.
(7) In the plate making apparatus, the image forming means is a full line head having a length substantially the same as the width of the plate cylinder.
(8) In the plate making apparatus, the ink jet recording apparatus causes the ink discharge means to approach the plate material when drawing on the plate material, and the ink discharge means is removed from the plate cylinder except during drawing on the plate material. Ink discharge means for separating is provided.
(9) In the plate making apparatus, the direct image forming means includes an ink discharge means cleaning means for cleaning the ink discharge means at least after completion of the plate making.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, an image is formed on a printing plate (printing original plate) by an ink jet method in which ink containing at least an oleophilic component is ejected, and a plurality of ink ejecting units are used to refer to previously prepared ink ejecting unit array data. Further, the present invention is characterized in that a density error caused by a combination of adjacent ink ejection units is corrected, and an ink ejection amount control value is obtained from an ejection correction table corresponding to the ink ejection unit to be used and drawn.
[0017]
As the ink jet method according to the present invention, any method can be used as long as it can eject ink containing a lipophilic component. Specifically, for example, “Photograph part 2 latest hard copy printer technology” edited by the Society of Electrophotography, Chapter 3 Photo The piezo method, thermal jet method, electrostatic method, discharge method, etc. described in the books of Kogyo Publishing (1988), Hiroshi Komon "Recording and Storage Technology Handbook" Maruzen Co., Ltd. (1992), etc. Can be used. JP-A-10-175300, JP-A-6-23986, JP-A-5-131633, JP-A-10-114073, JP-A-10-34967, JP-A-3-104650, JP-A-8-300803. A system in which the inventions disclosed in the above publications are applied or combined is also preferably used.
As described above, according to the present invention, when plate making is performed by the ink jet method, the characteristics of each ink discharge means are corrected by using a plurality of ink discharge means, so that a clear and high quality image can be obtained with an inexpensive apparatus and a simple method. An image printing plate can be obtained.
[0018]
A configuration example of a plate making apparatus used for carrying out the plate making method of the present invention is shown below. 1 and 2 are overall configuration diagrams of the plate making apparatus. FIG. 3 is a schematic configuration example of a drawing unit including a control unit, an ink supply unit, and an ejection unit separation / contact mechanism of the plate making apparatus. 4 to 18 are for explaining the ink jet drawing apparatus provided in the plate making apparatus of FIGS.
[0019]
First, a plate making process according to the present invention will be described with reference to an overall configuration diagram of a plate making apparatus having a structure in which a plate material is mounted on a drawing drum 11 as shown in FIG. However, the present invention is not limited to the following configuration examples.
[0020]
The drum 11 is usually formed of a metal such as aluminum, stainless steel or iron, plastic, glass or the like. In particular, in the case of a metal drum, its surface is often subjected to, for example, alumite treatment or chrome plating in order to enhance wear resistance and rust prevention. The drum 11 may have a heat insulating material on its surface as described later.
[0021]
Further, the plate making apparatus 1 has an ink jet drawing apparatus 2, whereby oil-based ink is applied to the plate material 9 mounted on the drum 11 in accordance with the image data sent from the image data calculation control unit 21. An ejected image is formed.
[0022]
Further, the plate making apparatus 1 has a fixing device 5 for strengthening the oil-based ink image drawn on the plate material 9. A plate surface desensitizing device 6 used as necessary for the purpose of enhancing hydrophilicity on the surface of the plate material 9 may be installed.
[0023]
The plate making apparatus 1 is provided with an adhesive roller 10 for adsorbing and removing dust on the plate material on the upstream side of the ink jet drawing device 2 in the plate material moving direction so as to be able to roll on the plate material 9. Yes. Here, rolling refers to the relative movement of the adhesive roller 10 relative to the plate material 9 while contacting the plate material 9 and rotating (including driven rotation or rotation). In the configuration of the present embodiment, the adhesive roller 10 and the plate material 9 move relative to each other when the adhesive roller 10 rotates at a fixed position with respect to the rotating plate material 9.
[0024]
The adhesive roller 10 can be brought into contact with and separated from the plate material 9 by a separation / contact mechanism (not shown). The adhesive roller 10 removes dust existing on the surface of the plate material before and / or during drawing on the plate material 9. That is, the dust on the plate member 9 may be removed only before drawing, only during drawing, before drawing, or during drawing. The adhesive roller 10 can be formed, for example, by attaching an adhesive layer to the outer periphery of a cylindrical core made of metal. As the cylindrical core material, ceramic, plastic or the like is used in addition to metal. Examples of the adhesive layer include rubber adhesives and acrylic adhesives. The adhesive roller 10 is determined by a method in accordance with “Test for bonding two parallel metal plates with rubber” in the section “Adhesion test between metal and vulcanized rubber” in the physical test method of JIS-K6301. The obtained adhesive strength is preferably 4 hPa or more and 250 hPa or less, more preferably 7 hPa or more and 180 hPa or less.
[0025]
The adhesive roller 10 may be constituted by one or two or more adhesive rollers having different adhesive forces. In the present embodiment, the adhesive roller 10 is composed of two adhesive rollers 10a and 10b. In such a configuration, one adhesive roller 10a is rolled on the plate material 9, and the other adhesive roller 10b is brought into direct or indirect contact with the one adhesive roller 10a. The dust adhering to 10a is adsorbed and removed.
[0026]
Here, the term “directly” refers to a configuration (this embodiment) in which another adhesive roller 10b is directly rolled onto the adhesive roller 10a. Therefore, when there are two or more adhesive rollers 10b, a plurality of adhesive rollers 10b are simultaneously in contact with the adhesive roller 10a. Moreover, indirect means the structure which makes the adhesive roller 10b contact in series, when there are two or more adhesive rollers 10b. Therefore, in the case of this mechanism, one adhesive roller 10b always comes into contact with the adhesive roller 10a. Then, the adhesive force of the adhesive roller 10b is set larger than the adhesive force of the adhesive roller 10a. That is, the adhesive roller 10b functions as a cleaning roller for the adhesive roller 10a. In the case where there are two or more adhesive rollers 10b and the adhesive rollers 10b (adhesive rollers 10b1, 10b2, 10b3,...) Are contacted in series, the adhesive force is 10b1 <10b2 <10b3 <. ... and so on.
[0027]
According to the former direct contact, the dust on the adhesive roller 10a can be simultaneously adsorbed and removed by the plurality of adhesive rollers 10b. In addition, according to the latter indirect contact, the dust adhering to the adhesive roller 10a can be sequentially adsorbed and removed by the other adhesive roller 10b. The dust on the roller 10a can be adsorbed and removed, and the ability to adsorb and remove dust can be maintained for a long time, and the reverse adhesion from the adhesive roller 10a to the printing plate can be reliably prevented.
[0028]
Further, an automatic plate feeding device 7 for automatically supplying the plate material 9 onto the drum 11 and an automatic plate discharging device 8 for automatically removing the plate material 9 after drawing from the drum 11 may be installed. By using the automatic plate feeding device 7 and the automatic plate discharging device 8, the plate making operation becomes easier and the plate making time can be shortened, so that the effect of the present invention can be further enhanced.
[0029]
The plate making process by the plate making apparatus 1 will be described below with reference to FIG.
[0030]
First, the plate material 9 is mounted on the drum 11 using the automatic plate feeder 7. At this time, the plate material 9 is tightly fixed on the drum 11 by a mechanical method such as a known plate head / tail holding device, an air suction device, or an electrostatic method, whereby the plate bottom flutters and draws. At times, contact with the ink jet drawing apparatus 2 can be prevented from being damaged. Further, means for bringing the plate material 9 into close contact with the drum 11 only around the drawing position of the ink jet drawing apparatus 2 is provided, and at least when drawing is performed, the plate material 9 is prevented from coming into contact with the ink jet drawing apparatus 2. You can also Specifically, for example, there are methods such as arranging pressing rollers upstream and downstream of the drawing position on the drum 11. Further, when drawing is not performed, it is desirable to keep the ink discharge means away from the plate material, which can effectively prevent the ink jet drawing apparatus 2 from causing problems such as contact damage.
[0031]
The image data calculation control unit 21 includes an image scanner, a magnetic disk
It receives image data from a device, an image data transmission device, etc., performs color separation as necessary, and performs a division operation on the separated data into an appropriate number of pixels and gradations. Furthermore, in order to draw an oil-based ink image with halftone dots using the ink jet discharge means 22 (see FIG. 3, which will be described in detail later) included in the ink jet drawing apparatus 2, the dot area ratio is also calculated. Furthermore, a discharge amount is determined using a discharge characteristic table described later according to the present invention.
In addition, as will be described later, the image data calculation control unit 21 controls the movement of the inkjet discharge means 22 and the discharge timing of the oil-based ink, and also controls the operation timing of the drum 11 and the like as necessary.
The calculation data input to the image data calculation control unit 21 is temporarily stored in the buffer. The image data calculation control unit 21 rotates the drum 11 to bring the ink discharge means 22 closer to the position close to the drum 11 by the ink discharge means separating / connecting device 31. The distance between the ink discharge means 22 and the surface of the plate 9 on the drum 11 is drawn by mechanical distance control such as an abutting roller or by control of the ink discharge means separating / connecting device by a signal from an optical distance detector. During, it is controlled to a predetermined distance. By such distance control, the dot diameter does not become non-uniform due to the floating of the plate material or the dot diameter does not change especially when vibration is applied to the plate making machine, and good plate making can be performed.
[0032]
As the ink discharge means 22, a multi-channel head or a full line head can be used, and main scanning is performed by rotating the drum 11. In the case of a multi-channel head having a plurality of ejection units or a full line head, the arrangement direction of the ejection units is set to the axial direction of the drum 11. Further, in the case of a multi-channel head, the image data calculation control unit 21 moves the ink discharge means 22 in the axial direction of the drum 11 every rotation of the drum 11, and the discharge position and halftone dot area ratio obtained by the above calculation. From the discharge characteristic table according to the present invention, which will be described later, an ink discharge amount control value for each image dot of the ink discharge means is determined, and the plate material 9 having the discharge amount of oil-based ink attached to the drum 11 is determined. Discharge. As a result, a halftone image corresponding to the density of the printed document is drawn on the plate material 9 with oil-based ink. This operation continues until an oil ink image for one color of the printing original is formed on the plate material 9 and a printing plate is completed. On the other hand, when the ink discharge means 22 is a full line head having a length substantially the same as the width of the drum 11, an oil-based ink image for one color of the printed document is formed on the plate material 9 by the drum 11 rotating once. The printing plate is completed. By performing main scanning by rotating the drum 11 in this way, the positional accuracy in the main scanning direction can be improved and high-speed drawing can be performed.
[0033]
Next, in order to protect the ink discharge means 22, the ink discharge means 22 is retracted away from the position close to the drum 11. The separation / contact means operates so as to separate the ink discharge means from the drum by at least 500 μm except during drawing. The separation / contact operation may be a slide type, or the ink discharge means 22 may be fixed by an arm fixed to a certain axis, and the arm may be moved around the axis to move in a pendulum shape. Thus, by retracting the ink discharge means 22 during non-drawing, the ink discharge means 22 can be protected from physical damage or contamination, and a long life can be achieved.
[0034]
The formed oil-based ink image is reinforced by the fixing device 5. As the ink fixing means, known means such as heat fixing and solvent fixing can be used. In heat fixing, irradiation with an infrared lamp, halogen lamp or xenon flash lamp, hot air fixing using a heater, or heat roll fixing is generally used. In this case, in order to improve the fixability, the drum is heated, the plate material 9 is preheated, drawing is performed while hot air is applied, the drum 11 is coated with a heat insulating material, and from the drum 11 at the time of fixing. It is effective to separate the plate material 9 and heat only the plate material 9 alone or in combination. Flash fixing using a xenon lamp or the like is known as an electrophotographic toner fixing method, and has an advantage that fixing can be performed in a short time. In addition, when a paper plate material is used, moisture inside the plate material rapidly evaporates due to a sudden rise in temperature, and a phenomenon called blistering occurs where the surface of the plate material is uneven. It is preferable to gradually increase the power supply to the heat source while rotating the drum 11 so as to warm, or to change the rotation speed from high speed to low speed with constant power supply. Alternatively, a plurality of fixing devices may be arranged in the rotation direction of the drum 11 and the distance to the plate material 9 and / or the supplied power may be changed to gradually increase the temperature of the paper plate material.
[0035]
In the solvent fixing, a solvent capable of dissolving the resin component in the ink such as methanol or ethyl acetate is sprayed or exposed to vapor, and excess solvent vapor is recovered.
It should be noted that at least in the process from the formation of the oil-based ink image by the ink discharge means 22 to the fixing by the fixing device 5, it is desirable to keep nothing on the image on the plate material 9.
[0036]
A configuration example of a plate making apparatus that performs sub-scanning by running the plate material 9 will be described with reference to FIG. However, the present invention is not limited to the following configuration examples.
[0037]
The plate material 9 is nipped and conveyed by the two pairs of capstan rollers 12, and is drawn by the ink jet drawing apparatus 2 using the data divided and calculated by the image data calculation control unit 21 into an appropriate number of pixels and gradations.
[0038]
Although FIG. 2 shows an apparatus using a sheet plate material, a roll plate material is also preferably used. In this case, it is desirable to provide a sheet cutter upstream of the automatic plate discharging device.
[0039]
Further, the plate making apparatus 1 has a fixing device 5 for strengthening the oil-based ink image drawn on the plate material 9. Moreover, you may install the plate surface desensitizing apparatus 6 used as needed for the purpose of the hydrophilic reinforcement | strengthening of the plate material 9 surface. In the plate making apparatus 1, the above-described adhesive roller 10 is disposed on the plate material 9 so as to roll on the upstream side of the ink jet drawing apparatus 2. In the present embodiment, the adhesive roller 10 is constituted by two or more adhesive rollers 10a and 10b having different adhesive forces, and one adhesive roller 10a rolls on the plate material 9, and the adhesive roller 10a has an adhesive force. Another adhesive roller 10b having an adhesive force larger than the force is in contact with the adhesive roller 10a. Therefore, the dust adhering to the adhesive roller 10a can be adsorbed and removed by the adhesive roller 10b. That is, the adhesive roller 10b functions as a cleaning roller that sucks and removes dust from the adhesive roller 10a, and prevents reverse adhesion of dust from the adhesive roller 10a to the printing plate.
[0040]
Further, it is preferable to install an automatic plate feeding device 7 for automatically supplying the plate material 9 and an automatic plate discharging device 8 for automatically removing the plate material 9 after drawing. By using the automatic plate feeding device 7 and the automatic plate discharging device 8, the plate making operation becomes easier and the plate making time can be shortened, so that the effect of the present invention can be further enhanced.
[0041]
The plate making process by the plate making apparatus 1 will be described in more detail below with reference to FIG.
[0042]
First, the plate material 9 is conveyed using the automatic plate feeder 7 and the cap stun roller 12. At this time, if necessary, a plate material guide means (not shown) is provided to prevent the plate head / butt of the plate material from flapping and coming into contact with the ink jet drawing apparatus 2 and being damaged. Further, means for preventing the plate material 9 from slacking only around the drawing position of the ink jet drawing apparatus 2 is provided, and at least when drawing is performed, the plate material 9 is prevented from coming into contact with the ink jet drawing apparatus 2. You can also Specifically, for example, there is a method of arranging a pressing roller upstream and downstream of the drawing position. Further, when drawing is not performed, it is desirable to keep the ink discharge means 22 away from the plate material 9, thereby effectively preventing problems such as contact breakage in the ink jet drawing apparatus 2.
[0043]
Image data from a magnetic disk device or the like is given to an image data calculation control unit 21. The image data calculation control unit 21 calculates a discharge position of oil-based ink and a dot area ratio at the position according to input image data. The ink discharge amount control value of each image dot of the ink discharge means is determined from the discharge position and the halftone dot area ratio using the discharge characteristic table according to the present invention, which will be described later. Is discharged onto the plate material 9 mounted on the drum 11. These calculation data are temporarily stored in the buffer.
The image data calculation control unit 21 performs the movement of the ink discharge means 22, the discharge timing control of the oil-based ink, and the operation timing control of the cap stun roller, and the ink discharge means 22 by the ink discharge means attachment / detachment device 31 as necessary. The position is brought close to the plate material 9.
The distance between the ink discharge means 22 and the surface of the plate 9 is a predetermined distance during drawing by controlling the mechanical distance such as an abutting roller or by controlling the ink discharge means separating / connecting device based on a signal from an optical distance detector. To be kept. By such distance control, the dot diameter does not become non-uniform due to the floating of the plate material or the dot diameter does not change especially when vibration is applied to the plate making machine, and good plate making can be performed.
[0044]
A multi-channel head or a full line head can be used as the ink discharge means 22, and the sub-scan is performed by conveying the plate material 9. In the case of a multi-channel head having a plurality of ejection portions, the arrangement direction of the ejection portions is set substantially parallel to the traveling direction of the plate material. Further, in the case of a multi-channel head, the image data calculation control unit 21 moves the ink discharge means 22 in the direction orthogonal to the traveling direction of the plate material 9 every time the plate material is moved, and the discharge position and mesh obtained by the above calculation. From the point area ratio, an ink ejection amount control value for each image dot of the ink ejection means is determined using a later-described ejection characteristic table according to the present invention, and a plate in which oil ink of that ejection amount is mounted on the drum 11 is determined. The material 9 is discharged.
As a result, a halftone image corresponding to the density of the printed document is drawn on the plate material 9 with oil-based ink. This operation continues until an oil ink image for one color of the printing original is formed on the plate material 9 and a printing plate is completed. On the other hand, when the ink discharge means 22 is a full line head having a length substantially the same as the width of the plate member 9, the arrangement direction of the discharge portions is set to a direction substantially orthogonal to the traveling direction of the plate member, As 9 passes through the drawing portion, an oil-based ink image for one color of the printing document is formed on the plate material 9 and a printing plate is completed.
[0045]
In order to protect the ink discharge means 22, the ink discharge means 22 is preferably retracted away from a position close to the plate material 9. This separation / contact means operates so that the ink discharge means is separated from the plate material 9 by at least 500 μm or more except during drawing. The contact / separation operation may be a slide type, or the ink discharge means may be fixed by an arm fixed to a certain axis, and the arm may be moved around the axis to move like a pendulum. Thus, by retracting the ink discharge means during non-drawing, the ink discharge means can be protected from physical damage or contamination, and a long life can be achieved.
[0046]
The formed oil-based ink image is reinforced by the fixing device 5. As the ink fixing means, known means such as heat fixing and solvent fixing can be used. In heat fixing, irradiation with an infrared lamp, halogen lamp or xenon flash lamp, hot air fixing using a heater, or heat roll fixing is generally used. Flash fixing using a xenon lamp or the like is known as an electrophotographic toner fixing method, and has an advantage that fixing can be performed in a short time. In addition, when using a paper plate material, the moisture inside the plate material rapidly evaporates due to a sudden rise in temperature, resulting in a phenomenon called blistering that causes irregularities on the surface of the plate material. In order to prevent blistering of the plate material 9, it is preferable to change the distance between the power supply and / or the fixing device to the plate material 9 so that the temperature of the paper plate material gradually increases.
[0047]
In the solvent fixing, a solvent capable of dissolving the resin component in the ink such as methanol and ethyl acetate is sprayed or exposed to vapor, and excess solvent vapor is recovered.
It should be noted that at least in the process from the formation of the oil-based ink image by the ink discharge means 22 to the fixing by the fixing device 5, it is desirable to keep nothing on the image on the plate material 9.
[0048]
The obtained printing plate is printed by a known planographic printing method. That is, the printing plate on which this oil-based ink image is formed is mounted on a printing machine, printing ink and fountain solution are applied to form a printing ink image, and this printing ink image is placed on a blanket cylinder rotating with the plate cylinder. Printing for one color is performed by transferring the printing ink image on the blanket cylinder onto the printing paper that is transferred and then passed between the blanket cylinder and the impression cylinder. The printing plate after printing is removed from the plate cylinder, and the blanket on the blanket cylinder is cleaned by the blanket cleaning device to be ready for the next printing.
[0049]
Next, the ink jet drawing apparatus 2 will be described.
As shown in FIG. 3, the ink jet drawing apparatus 2 used in the plate making apparatus includes an ink jet discharge means 22, an ink jet discharge means protection means 221, and an ink supply unit 24. The ink supply unit 24 further includes an ink tank 25, an ink supply device 26, and an ink density control unit 29, and the ink tank 25 includes a stirring unit 27 and an ink temperature management unit 28. Ink may be circulated in the ink ejection means 22, and in this case, the ink supply unit 24 also has a recovery and circulation function. The agitation means 27 suppresses the precipitation and aggregation of the solid component of the ink, and the necessity for cleaning the ink tank 25 is reduced. As the stirring means 27, a rotary blade, an ultrasonic vibrator, or a circulation pump can be used, and these are used in combination or in combination. The ink temperature management means 28 is arranged so that high-quality images can be stably formed without changing the physical properties of the ink due to changes in the surrounding temperature and without changing the dot diameter. As the ink temperature control means, a heater, a Peltier element or other heat generating element or a cooling element is arranged in the ink tank 25 together with the stirring means 27 so as to make the temperature distribution in the ink tank 25 constant, and a temperature sensor, for example, A known method such as control by a thermostat or the like can be used. The ink temperature in the ink tank 27 is desirably 15 ° C. or more and 60 ° C. or less, more preferably 20 ° C. or more and 50 ° C. or less. Further, the stirring means for keeping the temperature distribution in the ink tank 25 constant may be shared with the stirring means for the purpose of suppressing precipitation and aggregation of the solid components of the ink.
[0050]
The plate making apparatus preferably has ink density control means 29 in order to perform high-quality drawing. As a result, it is possible to effectively suppress the occurrence of bleeding on the plate due to a decrease in the solid content concentration in the ink, the jumping or blurring of the printed image, or the change in the dot diameter on the plate due to the increase in the solid content concentration. The ink density is measured by optical detection, conductivity measurement, physical property measurement such as viscosity measurement, or management based on the number of drawn images. In the case of management by physical property measurement, an optical detector, a conductivity measuring device, and a viscosity measuring device are provided alone or in combination in the ink tank 25 or in the ink flow path, and the drawing is performed according to the output signal. When managing by the number of sheets, the supply of liquid from a replenishment concentrated ink tank or dilution ink carrier tank (not shown) to the ink tank 25 is controlled according to the number of plates and the frequency.
Examples of the ink discharge means protection means 221 include a foreign matter adhesion prevention means to the ink discharge means 22 and a drawing stop means when an abnormality occurs, and examples of the foreign matter adhesion prevention means include an ink discharge protection cover. That is, when drawing is not being performed, the ink ejection means 22 can be stored in the cover to prevent foreign matter from adhering. FIG. 4 shows an embodiment of the cover according to the present invention. As shown in FIG. 4, the ink discharge means is stored in a cover with a shutter, and when drawing is performed, the shutter is opened and the ink discharge means is moved to the drawing position. Advance and draw. The cover can be filled with ink or an ink solvent. In this case, troubles due to sticking of ink to the ink discharge means can be prevented even when drawing is not performed for a long period of time. As the drawing stop means at the time of occurrence of abnormality, for example, a dust sensing device or an abnormal current sensing device of the head is connected to the image data calculation control unit 21, and when an abnormality signal is generated from the device, to the ink ejection means 22 By providing a mechanism that stops the voltage signal, the ink discharge means 22 can be prevented from being damaged.
[0051]
As described above, the image data calculation control unit 21 calculates the input image data and moves the ink discharge means 22 by the ink discharge means separating / connecting device 31 or the ink discharge means sub-scanning means 32. The timing pulse from the encoder 30 installed on the capstan roller is taken in, and the ink ejection means 22 is driven in accordance with the timing pulse. Thereby, positional accuracy can be improved.
Further, the above-described ink ejection means protection means 221 is also controlled.
[0052]
The ink discharge means 22 can also include a maintenance device such as a cleaning means as required. For example, when the resting state continues or when image quality problems occur, wipe the tip of the ink ejection means with a flexible brush, brush, cloth, etc., circulate only the ink solvent, or supply only the ink solvent Alternatively, it is possible to maintain a good drawing state by performing a means such as sucking the discharge part while circulating it alone or in combination. In order to prevent the ink from sticking, it is also effective to cool the ink discharge means and suppress the evaporation of the ink solvent. Furthermore, if the dirt is severe, the ink is forcibly sucked from the discharge part, or the jet of air, ink, or ink solvent is forcibly inserted from the ink flow path, or the ultrasonic wave is applied while the head is immersed in the ink solvent. Applying these is also effective, and these methods can be used alone or in combination.
[0053]
Next, a method for determining the ink discharge amount control value will be described.
First, ink ejection unit array data describing which ink ejection unit each print dot on the output image is drawn is created in advance from the recording dot density, the ink ejection unit interval, and the ink ejection unit scanning feed pitch.
FIG. 6 is a diagram for explaining an example of a method for creating the ink ejection means array data. In FIG. 6, the ink discharge means H is composed of continuous channels of four unit discharge means H1, H2, H3, and H4. At the beginning of recording, the position shown in FIG. Suppose it is in position. When the recording medium P moves in the direction of the white arrow in the figure, the ink discharge means H moves relative to the recording medium P in the illustrated main scanning direction. At this time, the discharge means H1 can record in the row indicated by 1 of the recording medium P. Similarly, the discharge means H2 in the row indicated by 2 of the recording medium P and the discharge means H3 in the row indicated by 3 of the recording medium P. The ejection means H4 can record in the columns indicated by 4 of the recording medium P. After the ink discharge means H has recorded to the recording end in the main scanning direction M, the recording medium P then returns to the position of FIG. 6A, the ink discharge means H moves in the sub-scanning direction, and the discharge means H1 records. When the medium P moves to an unrecorded row adjacent to the row indicated by 4, it stops. FIG. 6B shows this state. Therefore, when the recording medium P moves in the direction of the white arrow in the figure, the ink ejection means H moves again in the main scanning direction M, while the ejection means H1 is in the row indicated by 1 of the recording medium P, and the ejection means H2 is the recording. In the row indicated by 2 of the medium P, the discharge means H3 can record in the row indicated by 3 of the recording medium P, and the discharge means H4 can record in the row indicated by 4 of the recording medium P. Hereinafter, similarly, by continuing the recording as described above, the ink indicating which ejection unit is in charge of recording for each pixel arranged vertically and horizontally in the main and sub-scanning directions of the recording medium P as shown in FIG. Thus, the ejection means array data is obtained.
[0054]
There is a method of preparing the ink discharge unit arrangement data corresponding to all the image dots of the input image. If does not change, it is sufficient to prepare only array data for one line and use it repeatedly.
[0055]
FIG. 7 is a diagram for explaining another example of the method for creating the ink ejection means array data.
In FIG. 7, the ink discharge means H is composed of four unit discharge means H1, H2, H3, and H4 arranged at intervals of one channel, and at the beginning of recording, the position shown in FIG. , At the upper left position of the recording medium P. Accordingly, when the recording medium P moves in the direction of the white arrow in the figure, the ink discharge means H records relative to the main scanning direction shown in the figure, while the discharge means H1 records at the position indicated by 1 on the recording medium P, and so on. Further, the ejection means H2 is at a position indicated by 2 which jumps in the sub-scanning direction for one channel of the recording medium P. Similarly, the ejection means H3 is at a position indicated by 3 on the recording medium P, and the ejection means H4 is at 4 on the recording medium P. Each of the recorded positions is recorded at a position skipped by one channel. When the ink ejection means H has recorded to the end in the main scanning direction M, the recording medium P then returns to the position of FIG. 6A, and the ink ejection means H is unrecorded next to the recorded position 1 of the recording medium P. It moves in the sub-scanning direction of FIG. 7B so that the ejection means H1 comes to the position, and the ink ejection means H moves again in the main scanning direction M, while the ejection means H1 moves to the position indicated by 1 on the recording medium P. Recording is performed at a position indicated by 2 on the recording medium P by the ejection means H2, at a position indicated by 3 on the recording medium P by the ejection means H3, and at a position indicated by 4 on the recording medium P by the ejection means H4. By continuing the recording in this way, ink ejection unit arrangement data indicating which ejection unit performs recording for each pixel arranged in the vertical and horizontal directions of the recording medium P as shown in FIG. 7C is obtained.
[0056]
Next, an ejection characteristic table is created in advance for each of the ink ejection means in advance. The ejection characteristic table is a table that associates the image dot density to be drawn with the ink ejection control value in each ink ejection unit, and outputs the recording dot size corresponding to the target image dot density by using the ejection characteristic table. An ink discharge control value that can be obtained can be obtained.
[0057]
As a method for creating the ejection characteristic table, for example, a grayscale image A recorded by the ink ejection unit and having the drawing dot density gradually changed for every arbitrary number of dots as shown in FIG. 8 is used as input data. FIG. 8A is an overall view of the gray scale image A, FIG. 8B is an enlarged view of a high density portion, and FIG. 8C is an enlarged view of a low density portion. Therefore, a gray scale image A in which the drawing dot density is gradually changed for each arbitrary number of dots as shown in the figure is used as input data, and only a target ink ejection means is used, and a temporary ejection characteristic table, for example, an image minimum density is used. Use a table that responds so that the ink discharge control value linearly decreases from the maximum value to the minimum value or increases from the minimum value to the maximum value for the dot density that increases linearly from the image to the maximum image density. The image density of the recording dot drawn with the ink discharge control value obtained in this way is measured. A true ejection characteristic table is created from the measured image density and the corresponding ink ejection control value.
Cx: density of image dot x
CM: Measurement density of recording dot x
TEtemp (C): Temporary ejection characteristic table
TEi (C): ejection characteristic table of ink ejection means i
TEi (CM) = TEtemp (Cx)
[0058]
The grayscale image A (FIG. 8) used at this time needs to have each recording dot not overlapped with other recording dots in order to accurately obtain the relationship between the measured density of the recording dots and the ink ejection control value. As shown in FIG. 8B (high density scale) and (c) [low density scale], image dots are arranged in a grid pattern every other dot or more, and the lowest density dot, for example, a white dot (in the figure) Fill with +).
[0059]
Next, a dot overlap correction table is experimentally created in advance.
The dot overlap correction table is data for correcting an error in recording dot size due to the overlapping of adjacent recording dots.
As a method for creating the dot overlap correction table, for example, adjacent recording dots are drawn on a grayscale image B in which the drawing dot density is gradually changed for each arbitrary number of dots as shown in FIG. Drawing is performed by the two ink discharge means 1 and 2, and the measured density of the drawn recording dots and the recording dots of the gray scale image C (FIG. 10E) drawn without being adjacent to each other so that the recording dots do not overlap. A dot overlap correction table is created using the density difference from the measured density as a table value with the ink ejection control values of the two ink ejection means used as indexes.
[0060]
FIG. 9 shows a case where two ink ejecting means 1 and 2 adjacent to each other are recorded in the same line. A gray scale image B shown in FIG. The recording changes from large dots to small dots and from large dots to small dots recorded by the ink discharge means 2 from left to right on the horizontal axis. Accordingly, FIG. 9 (a) shows a high-density portion where both dods are large and have overlapping portions, and (b) and (c) are both medium-density portions in a critical state where one is large and the other overlaps with a small dot. d) shows both low density parts which are small and have no overlapping parts.
[0061]
FIG. 10 shows a case where two ink ejection units 1 and 2 adjacent to each other are alternately recorded in each row. The gray scale image B shown in FIG. Change from large dots to small dots, and from large to small dots recorded by the ink discharge means 2 from left to right on the horizontal axis. Therefore, FIG. 10A shows a case where both the dodds are large, (b) and (c) show that both are large and the other is a small dot, and (d) shows a case where both the dods are small. The feature is that there is no overlap.
As described above, according to the present invention, the dot overlap between adjacent ink ejection means is corrected regardless of whether the dot position is normal or not, and an image having no dot overlap as shown in FIG. This is because the method for correcting dot overlap according to the present invention is based on the image density when dots do not overlap. This is because the overlap correction table is prepared from the image density of each dot obtained from the ejection characteristic table of each ink ejection means and the actually measured image density.
TCi-j (Cx, Cy): dot overlap correction table between the recording dot x of the measured density Cx drawn by the ink discharge means i and the recording dot y of the measured density Cy drawn by the ink discharge means j located on the left side
CMol: measured density of recording dots x and y drawn adjacent to each other so that they can overlap
Cmop: measured density of recording dots x and y drawn with a gap so that they cannot overlap
TCi-j (Cx, Cy) = Cx.times. (CMop-CMol) / CMop
[0062]
The grayscale image B (FIG. 9) at this time is between the non-overlapping dots so that the respective recording dots drawn by the two ink ejection units 1 and 2 can overlap at only one place. A minimum density dot of 1 dot or more, for example, a white dot is arranged.
[0063]
First, a procedure for correcting the density error due to the overlap between the recording dots will be described. In FIG. 11, first, the ink discharge means 1 for drawing the image dot a is obtained with reference to the ink discharge means arrangement data for the image dot a of the input image data to be output. Furthermore, referring to the ink discharge means arrangement data, ink discharge means for drawing each of the adjacent recording dots b, c, d, e is also obtained (for the dots b, d, the ink discharge means 1, the dot c, e is determined to be the ink discharge means 2.) Using the dot overlap correction table corresponding to them, density correction values ΔCa-b, ΔCa-c, ΔCa-d, ΔCa-e are obtained, and these are obtained as image dots a. The correction density is obtained by adding to the density.
ΔCa−b: Overlap density correction value of the recording dot a having the measured density Ca and the recording dot b having the measured density Cb
ΔCa-c: Overlap density correction value of the recording dot a with the measured density Ca and the recorded dot c with the measured density Cc
ΔCa−d: Overlap density correction value of the recording dot a with the measured density Ca and the recording dot d with the measured density Cd
ΔCa-e: Overlap density correction value of the recording dot a having the measured density Ca and the recording dot e having the measured density Ce
Ca ′: correction density of image dot a
Tci-i (Cx, Cy): dot overlap correction table TCi-j (Cx, Cy): recording dot x of the measured density Cx drawn by the ink ejection means i and recording dot y of the measured density Cy: ink ejection A dot overlap correction table between the recording dot x of the measured density Cx drawn by the means i and the recording dot y of the measured density Cy drawn by the ink discharge means j located on the left side
ΔCa−b = Tc1-1 (Ca, Cb)
ΔCa−c = Tc1-2 (Ca, Cc)
ΔCa−d = Tc1-1 (Ca, Cd)
ΔCa−e = Tc2-1 (Ce, Ca)
Ca ′ = Ca + ΔCa−b + ΔCa−c + ΔCa−d + ΔCa−e
As described above, the dot overlap correction table is a two-dimensional table in which the input is the dot density of two adjacent dots (dot density drawn without overlapping by a single ink ejection means) and the output is the dot correction density. When the dots are drawn adjacent to the two ink discharge means with and without overlap (drawing using the respective discharge characteristic tables obtained in advance), the difference in density is measured (that is, , The dot correction density obtained by distributing the density loss due to the overlapping of dots) at the ratio of the respective dot densities, and the dot correction density becomes a dot overlap correction table (for the density of the two drawn dots).
[0064]
Next, a procedure for determining the ink discharge amount control value will be described.
FIG. 12 shows an outline of the procedure for determining the ink discharge amount control value according to the present invention. FIG. 12A shows input data (image dot density) of each pixel, FIG. 12B shows ink ejection means arrangement data, and FIG. 12C shows correction using the dot overlap correction table according to the present invention. FIG. 12D shows the ejection characteristic table of the ink ejection means 1 and FIG. 12E shows the ink ejection amount control value of each pixel. Therefore, for each image dot a of the image data to be output (for example, the dot a in the first row and the first column), first, the image dot is set by referring to the ink ejection means array data (FIG. 12B). The ink discharge means for drawing is obtained (in the figure, the charge of the dot a in the first row and the first column is determined to be the ink discharge means 1).
On the other hand, the density of the input data of the image dot a (value 28 in FIG. 12A) is corrected as follows. First, by using the ink discharge means arrangement data of FIG. 12B, an ink discharge means for drawing the target dot a and an ink discharge means for drawing a dot adjacent to the target dot a are obtained (here, ink discharge). Means 1 and 2), an overlap density correction value is obtained using a dot overlap correction table between dots adjacent to the target dot a vertically and horizontally based on the expression of the correction density Ca ′ of the image dot a, All the overlap density correction values thus obtained are added to the target dot a density, and this is used as the correction density of the target dot. Here, the correction density (value 30 in FIG. 12C) is obtained.
Then, using the ejection characteristic table of the ink ejection means (in this case, the ink ejection means 1) for drawing the target dot a, the ink ejection amount control value for the correction density (value 30 in FIG. 12C) of the target dot. (Value 1.5 in FIG. 12E) is obtained.
Ea: ink discharge amount control value of the recording dot a having the measured density Ca
TEi (C): ejection characteristic table of ink ejection means i
Ca ′: correction density of image dot a
Ea = TE1 (Ca ')
[0065]
Next, the plate material (printing original plate) used in the present invention will be described.
Examples of the printing original plate include metal plates such as aluminum and chrome-plated steel plates. In particular, an aluminum plate having excellent surface water retention and abrasion resistance by graining and anodizing treatment is preferable. As a cheaper plate material, a plate material in which an image receiving layer is provided on a water-resistant support such as water-resistant paper, plastic film, and plastic-laminated paper can be used. The thickness of the plate material is suitably in the range of 100 to 300 μm, and the thickness of the image receiving layer provided therein is suitably in the range of 5 to 30 μm.
[0066]
As the image receiving layer, a hydrophilic layer made of an inorganic pigment and a binder, or a layer that can be made hydrophilic by a desensitizing treatment can be used.
[0067]
As the inorganic pigment used in the hydrophilic image-receiving layer, clay, silica, calcium carbonate, zinc oxide, aluminum oxide, barium sulfate and the like can be used. As the binder, hydrophilic binders such as polyvinyl alcohol, starch, carboxymethyl cellulose, hydroxyethyl cellulose, casein, gelatin, polyacrylate, polyvinyl pyrrolidone, polymethyl ether-maleic anhydride copolymer and the like can be used. Moreover, you may add a melamine formalin resin, urea formalin resin, and other crosslinking agents which provide water resistance as needed.
[0068]
On the other hand, examples of the image receiving layer used after desensitizing treatment include a layer using zinc oxide and a hydrophobic binder.
[0069]
The zinc oxide used in the present invention is, for example, zinc oxide, zinc white, wet zinc white as described in “New Edition Pigment Manual”, page 319 edited by Japan Pigment Technical Association, Sebundo Co., Ltd. (1968). Or what is marketed as activated zinc white may be sufficient.
That is, there are zinc oxides called French method (indirect method), American method (direct method) and wet method as a dry method, depending on the starting materials and production method. For example, Zodo Chemical Co., Ltd., Sakai Chemical Co., Ltd. ), Hakusui Chemical Co., Ltd., Honjo Chemical Co., Ltd., Toho Zinc Co., Ltd., Mitsui Kinzoku Kogyo Co., Ltd., and other companies.
[0070]
Specific examples of resins used as binders include styrene copolymers, methacrylate copolymers, acrylate copolymers, vinyl acetate copolymers, polyvinyl butyral, alkyd resins, epoxy resins, epoxy ester resins, and polyester resins. And polyurethane resin. These resins may be used alone or in combination of two or more.
The content of the resin in the image receiving layer is preferably 9/91 to 20/80 expressed as a weight ratio of resin / zinc oxide.
[0071]
Desensitization of zinc oxide is carried out by a conventional method using a desensitizing treatment solution, and conventionally, a cyanide-containing treatment solution mainly composed of ferrocyanate and ferricyan salt as this type of desensitization treatment solution. , Cyan-free treatment solution based on ammine cobalt complex, phytic acid and its derivatives, guanidine derivatives, treatment solution based on inorganic or organic acids that form chelates with zinc ions, or water-soluble polymers Treatment liquids and the like are known.
Examples of the cyanide-containing treatment liquid include those described in JP-B Nos. 44-9045, 46-39403, JP-A Nos. 52-76101, 57-107889, 54-117201, and the like. .
[0072]
The surface of the plate material opposite to the image receiving layer preferably has a Beck smoothness in the range of 150 to 700 (second / 10 cc). As a result, the formed printing plate can be satisfactorily printed without causing displacement or slippage on the plate cylinder even during printing.
[0073]
Here, the Beck smoothness can be measured by a Beck smoothness tester. The Beck smoothness tester is a test piece placed on a circular glass plate with a hole in the center that has been finished with a high degree of smoothness (1 kgf / cm). ² (9.8 N / cm ² )) To measure the time required for a certain amount (10 cc) of air to pass between the glass surface and the test piece under reduced pressure.
[0074]
The oil-based ink used in the present invention will be described below.
The solvent for the oil-based ink used in the present invention is preferably a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon, and halogen-substituted products of these hydrocarbons. For example, hexane, heptane, octane, isooctane, decane, isodecane, decalin, nonane, dodecane, indodecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L (Isopar: trade name of Exxon), Shellsol 70, Shellsol 71 (Shellsol: trade name of Shell Oil), Amsco OMS, Amsco 460 solvent (Amsco: Trade name of Spirits), silicone oil, etc. Use alone or in combination.
[0075]
The resin particles dispersed in the non-aqueous solvent may be hydrophobic resin particles that are solid at a temperature of 35 ° C. or lower and have a good affinity with the non-aqueous solvent. Is preferably a resin (P) having a temperature of -5 ° C to 110 ° C or a softening point of 33 ° C to 140 ° C, more preferably a glass transition point of 10 ° C to 100 ° C or a softening point of 38 ° C to 120 ° C, and still more preferably a glass transition. The point is 15 ° C to 80 ° C, or the softening point is 38 ° C to 100 ° C.
[0076]
By using a resin having such a glass transition point or softening point, the affinity between the image receiving layer surface of the printing original plate and the resin particles is increased, and the bond between the resin particles on the printing original plate is strengthened. The adhesion between the portion and the image receiving layer is improved, and the printing durability is improved. On the other hand, even if the glass transition point or softening point is lowered or increased, the affinity between the image receiving surface and the resin particles is lowered, or the bond between the resin particles is weakened.
[0077]
The weight average molecular weight Mw of the resin (P) is 1 × 10 ³ ~ 1x10 ⁶ Preferably 5 × 10 ³ ~ 8x10 ⁵ , More preferably 1 × 10 ⁴ ~ 5x10 ⁵ It is.
[0078]
Specific examples of such a resin (P) include olefin polymers and copolymers (for example, polyethylene, polypropylene, polyisobutylene, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, ethylene-methacrylate copolymers). , Ethylene-methacrylic acid copolymers, etc.), vinyl chloride polymers and copolymers (eg, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, etc.), vinylidene chloride copolymers, vinyl alkanoate polymers and copolymers Polymers, allyl alkanoic acid polymers and copolymers, polymers and copolymers of styrene and its derivatives (eg butadiene-styrene copolymers, isoprene-styrene copolymers, styrene-methacrylate copolymers, styrene-acrylates) Copolymer), acrylonitrile copolymer, methacrylate Ronitrile copolymer, alkyl vinyl ether copolymer, acrylic acid ester polymer and copolymer, methacrylic acid ester polymer and copolymer, itaconic acid diester polymer and copolymer, maleic anhydride copolymer, acrylamide copolymer Polymer, methacrylamide copolymer, funinol resin, alkyd resin, polycarbonate resin, ketone resin, polyester resin, silicone resin, amide resin, hydroxyl group and carboxyl group modified polyester resin, butyral resin, polyvinyl acetal resin, urethane resin, rosin type Resin, hydrogenated rosin resin, petroleum resin, hydrogenated petroleum resin, maleic acid resin, terpene resin, hydrogenated terpene resin, coumarone-indene resin, cyclized rubber-methacrylic acid ester copolymer, cyclized rubber-acrylic acid ester Copolymer containing a heterocyclic ring containing no nitrogen atom (for example, a furan ring, tetrahydrofuran ring, thiophene ring, dioxane ring, dioxofuran ring, lactone ring, benzofuran ring, benzothiophene ring, 1 , 3-dioxetane ring, etc.), epoxy resins and the like.
[0079]
The content of the dispersed resin particles in the oil-based ink of the present invention is preferably 0.5 to 20 wt% of the entire ink. If the content is reduced, the affinity between the ink and the surface of the printing original plate is difficult to obtain, and it is difficult to obtain a good image or the printing durability is lowered. When the amount of water increases, there is a problem that it is difficult to obtain a uniform dispersion, or that the flow of ink in the ink discharge means tends to be uneven, and stable ink discharge is difficult to obtain.
[0080]
The oil-based ink used in the present invention preferably contains a coloring material as a coloring component for the purpose of inspecting the plate after plate making together with the dispersed resin particles.
As the coloring material, any pigments and dyes conventionally used in oil-based ink compositions or electrophotographic liquid developers can be used.
[0081]
As the pigment, regardless of inorganic pigments and organic pigments, those generally used in the technical field of printing can be used. Specifically, for example, carbon black, cadmium red, molybdenum red, chrome yellow, Cadmium yellow, titanium yellow, chromium oxide, viridian, cobalt green, ultramarine blue, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, dioxazine pigment, selenium pigment, Conventionally known pigments such as perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, metal complex pigments and the like can be used without any particular limitation.
[0082]
As dyes, azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthene dyes, aniline dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes, Oil-soluble dyes such as metal phthalocyanine dyes are preferred.
These pigments and dyes may be used alone or in appropriate combinations, but are desirably contained in the range of 0.01 to 5% by weight with respect to the total ink.
[0083]
These color materials may be dispersed in the non-aqueous solvent as the dispersed particles separately from the dispersed resin particles, or may be contained in the dispersed resin particles. In the case of inclusion, a method such as pigment is generally coated with a resin material of dispersed resin particles to form resin-coated particles, and a dye or the like is a method of coloring the surface of dispersed resin particles to form colored particles. It is common.
[0084]
The average particle diameter of these particles, including resin particles dispersed in the non-aqueous solvent of the present invention, as well as colored particles, is preferably 0.05 μm to 5 μm. More preferably, it is 0.1 micrometer-1.0 micrometer. This particle size is determined by CAPA-500 (trade name, manufactured by Horiba, Ltd.).
[0085]
The non-aqueous dispersed resin particles used in the present invention can be produced by a conventionally known mechanical pulverization method or polymerization granulation method. As a mechanical pulverization method, if necessary, materials for resin particles are mixed, melted, kneaded and directly pulverized by a conventionally known pulverizer to form fine particles, combined with a dispersion polymer, and further wet dispersed. A method of dispersing with a machine (for example, a ball mill, paint shaker, ketid mill, dyno mill, etc.), a material that is a resin particle component, and a dispersion auxiliary polymer (or coating polymer) are kneaded in advance to obtain a kneaded product, which is then pulverized Examples thereof include a method in which a polymer is coexisted and dispersed. Specifically, methods for producing paints or liquid developers for electrophotography can be used. For example, Kenji Ueki, “Paint Flow and Pigment Dispersion”, Kyoritsu Shuppan (1971), Solomon “ "Science of paint" Hirokawa Shoten (1969), Yuji Nagasaki "Coating Engineering" Asakura Shoten (1971), Yuji Harasaki "Basic Science of Coating" Tsuji Shoten (1977)
[0086]
The polymerization granulation method includes a conventionally known non-aqueous dispersion polymerization method. Specifically, Chapter 2 such as “Latest technology of ultrafine particle polymer” supervised by Soichi Muroi, CMC Publishing (1991), Nakamura Koichi, “Recent development and commercialization of recent electrophotographic development systems and toner materials”, Chapter 3 (published in 1985, Japan Science Information Co., Ltd.) E. J. et al. It is described in a book such as Barrett “Dispersion Polymerization Organic Media” John Wiley (1975).
[0087]
Usually, a dispersion polymer is used in combination in order to stabilize dispersion particles in a non-aqueous solvent. The dispersion polymer contains a repeating unit soluble in a non-aqueous solvent as a main component, and the average molecular weight is 1 × 10 in terms of weight average molecular weight Mw. ³ ~ 1x10 ⁶ Is preferred, more preferably 5 × 10 ³ ~ 5x10 ⁵ Range.
[0088]
A preferable soluble repeating unit of the dispersion polymer used in the present invention includes a polymerization component represented by the following general formula (I).
[0089]
[Chemical 1]

[0090]
In general formula (I), X1 represents -COO-, -OCO-, or -O-. R represents an alkyl group or alkenyl group having 10 to 32 carbon atoms, preferably an alkyl group or alkenyl group having 10 to 22 carbon atoms, which may be linear or branched and is preferably unsubstituted. May have a substituent.
Specific examples include a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an eicosanyl group, a docosanyl group, a decenyl group, a dodecenyl group, a tridecenyl group, a hexadecenyl group, an octadecenyl group, and a linolenyl group. .
[0091]
a1 and a2 may be the same or different from each other, and are a hydrogen atom, a halogen atom (for example, a chlorine atom, a bromine atom, etc.), a cyano group, an alkyl group having 1 to 3 carbon atoms (for example, a methyl group, an ethyl group, Propyl group, etc.), -COO-Z ₁ Or -CH ₂ COO-Z ₁ [Z ₁ Represents an optionally substituted hydrocarbon group having 22 or less carbon atoms (for example, an alkyl group, an alkenyl group, an aralkyl group, an alicyclic group, an aryl group, etc.).
[0092]
Z ₁ Among the hydrocarbon groups represented by general formula (1), preferred hydrocarbon groups are alkyl groups having 1 to 22 carbon atoms which may be substituted (for example, methyl group, ethyl group, propyl group, butyl group, hexyl group, heptyl group). Octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, hexadecyl group, octadecyl group, eicosanyl group, docosanyl group, 2-chloroethyl group, 2-bromoethyl group, 2-cyanoethyl group, 2-methoxycarbonyl An ethyl group, 2-methoxyethyl group, 3-bromopropyl group, etc.), an alkenyl group having 4 to 18 carbon atoms which may be substituted (for example, 2-methyl-1-propenyl group, 2-butenyl group, 2-pentenyl). Group, 3-methyl-2-pentenyl group, 1-pentenyl group, 1-hexenyl group, 2-hexenyl group, 4-methyl-2 A hexenyl group, a decenyl group, a dodecenyl group, a tridecenyl group, a hexadecenyl group, an octadecenyl group, a linolenyl group, etc., an aralkyl group having 7 to 12 carbon atoms which may be substituted (for example, a benzyl group, a phenethyl group, a 3-phenylpropyl group) Naphthylmethyl group, 2-naphthylethyl group, chlorobenzyl group, bromobenzyl group, methylbenzyl group, ethylbenzyl group, methoxybenzyl group, dimethylbenzyl group, dimethoxybenzyl group, etc.), substituted with 5 to 8 carbon atoms Alicyclic groups (for example, cyclohexyl group, 2-cyclohexylethyl group, 2-cyclopentylethyl group, etc.) and optionally substituted aromatic groups having 6 to 12 carbon atoms (for example, phenyl group, naphthyl group, Tolyl, xylyl, propylphenyl, butylphenyl, octyl Phenyl group, dodecylphenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group, decyloxyphenyl group, chlorophenyl group, dichlorophenyl group, bromophenyl group, cyanophenyl group, acetylphenyl group, methoxycarbonylphenyl group, ethoxycarbonylphenyl Group, butoxycarbonylphenyl group, acetamidophenyl group, propionamidophenyl group, dodeciloylamidophenyl group, etc.).
[0093]
In addition to the repeating unit represented by formula (I) in the dispersion polymer, another repeating unit may be contained as a copolymerization component. The other copolymer component may be any compound as long as it is composed of a monomer copolymerizable with a monomer corresponding to the repeating unit of the general formula (I).
[0094]
The ratio of the polymer component represented by the general formula (I) in the dispersion polymer is preferably 50% by weight or more, and more preferably 60% by weight or more.
Specific examples of these dispersion polymers include the dispersion stabilizing resin (Q-1) used in Examples, and commercially available products (Solprene 1205, manufactured by Asahi Kasei Co., Ltd.) can also be used.
[0095]
The dispersion polymer is preferably added in advance during polymerization when the resin (P) particles are produced as a dispersion (latex) or the like.
The addition amount when using the dispersion polymer is about 1 to 50% by weight with respect to the resin for particles (P).
[0096]
The dispersed resin particles and colored particles (or colorant particles) in the oil-based ink of the present invention are preferably positively charged or negatively charged electrophoretic particles.
The electroanalytical property can be imparted to these particles by appropriately utilizing the wet electrophotographic developer technique. Specifically, “Recent development and practical use of recent electrophotographic development systems and toner materials” described above, pages 139 to 148, “Basics and Applications of Electrophotographic Technology” pages 497 to 505 (Corona, 1988). Annual publication), Yuji Harasaki “Electrophotography” 16 (No. 2), p. 44 (1977), etc., and using an electroanalyzing material such as a charge control agent and other additives.
[0097]
Specifically, for example, British Patent Nos. 893429, 934038, 11222397, U.S. Pat. No. 3,940,332, equivalent No. 460689, JP-A-60-179751, JP-A-60-185963, JP-A-2 No. 13965 and the like.
The charge control agent as described above is preferably 0.001 to 1.0 part by weight with respect to 1000 parts by weight of the dispersion medium as the carrier liquid. Further, various additives may be added as desired.
[0098]
【Example】
The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.
First, an example of producing ink resin particles (PL) will be described.
[0099]
<Production example of resin particles (PL-1)>
A mixed solution of 10 g of dispersion stabilizing resin (Q-1) having the following structure, 100 g of vinyl acetate and 384 g of Isopar H was heated to a temperature of 70 ° C. while stirring under a nitrogen stream. As a polymerization initiator, 0.8 g of 2,2′-azobis (isovaleronitrile) (abbreviation AIVN) was added and reacted for 3 hours. 20 minutes after the addition of the initiator, white turbidity occurred, and the reaction temperature rose to 88 ° C. Further, 0.5 g of this initiator was added and reacted for 2 hours, and then the temperature was raised to 100 ° C. and stirred for 2 hours to distill off unreacted vinyl acetate. After cooling, it was passed through a 200-mesh nylon cloth, and the resulting white dispersion was a latex with a good monodispersity having a polymerization rate of 90% and an average particle size of 0.23 μm. The particle size was measured with CAPA-500 (manufactured by Horiba, Ltd.).
[0100]
[Chemical 2]

[0101]
A part of the white dispersion is separated into a centrifuge (rotation speed: 1 × 10 ⁴ r. p. m. The resin particles settled over a rotation time of 60 minutes) were collected and dried. The weight average molecular weight of resin particles (Mw: polystyrene equivalent GPC value) is 2 × 10 ⁵ The glass transition point (Tg) was 38 ° C.
[0102]
Next, an oil-based ink was prepared.
<Creation of oil-based ink (IK-1)>
10 g of dodecyl methacrylate / acrylic acid copolymer (copolymerization ratio; 95/5 weight ratio), 10 g of nigrosine and 30 g of shellsol 71 are placed in a paint shaker (manufactured by Toyo Seiki Co., Ltd.) together with glass beads for 4 hours. Thus, a fine dispersion of nigrosine was obtained.
60 g of resin particles (PL-1) produced in Production Example 1 of resin particles for ink (as solid content), 2.5 g of the above nigrosine dispersion, 15 g of FOC-1400 (Nissan Chemical Co., Ltd., tetradecyl alcohol) A black oil-based ink was prepared by diluting 0.08 g of octadecene-half-maleic acid octadecylamide copolymer to 1 liter of Isopar G.
[0103]
Next, 2 liters of the oil-based ink (IK-1) prepared as described above was filled in the ink jet drawing apparatus 2 of the plate making apparatus (see FIGS. 1 and 3) in an ink tank. Here, a 900 dpi, 64-channel multi-channel head was used as the ink discharge means. As the ink temperature control means, a throw-in heater and a stirring blade were provided in the ink tank, the ink temperature was set to 30 ° C., and the temperature was controlled with a thermostat while rotating the stirring blade at 30 rpm. Here, the stirring blade was also used as a stirring means for preventing sedimentation and aggregation. Further, the ink flow path is partially transparent, and the LED light emitting element and the light detecting element are disposed between the ink flow paths, and the ink dilution liquid (Isopar G) or concentrated ink (solid state of the ink (IK-1) is determined depending on the output signal. Concentration control was carried out by charging.
[0104]
As the plate material, a 0.12 mm thick aluminum plate subjected to graining and anodizing treatment was mounted with a plate head and a plate bottom in addition to a mechanical device provided on the drum of the plate making apparatus. After removing dust on the surface of the plate material by air pump suction, the ink discharge means is brought close to the plate material to the drawing position, and image data to be made is transmitted to the image data calculation control unit. The ink discharge means corresponding to each image dot is obtained by the ink discharge means selection means, the ink discharge amount control value is determined from the discharge characteristic table for each ink discharge means, and the 64-channel ink is rotated while rotating the drum. By moving the ejection means, the determined amount of oil-based ink was ejected onto the aluminum plate to form an image.
As a result, the variation in the flight characteristics of each ink ejection unit was corrected, and drawing with a desired density was performed. There was no drawing defect due to dust, and no image deterioration due to a change in the dot diameter or the like was observed even when the outside air temperature changed or the number of plate making increased, and good plate making was possible.
On the other hand, in a plate making apparatus that does not include an ejection characteristic table, variations in flight characteristics of each ink ejection means are drawn as they are, so that dods overlap each other, and drawing at a desired density is not performed. .
[0105]
Further, the image was strengthened by heating with a xenon flash fixing device (Ushio Electric Co., Ltd., emission intensity 200 J / pulse) to prepare a printing plate. In order to protect the ink jet discharge means, the ink jet drawing apparatus was retracted 50 mm from the position close to the drum together with the sub scanning means, and then the printing plate was taken out from the plate making apparatus and mounted on the plate cylinder of the Oliver 266EPZ printing machine for printing. .
[0106]
The obtained printed matter was an extremely clear image having a desired density, with no skipping, blurring or unexpected dot overlap even after 10,000 sheets.
[0107]
Further, under the same conditions, the adhesive force of the adhesive roller is 7 hPa to 180 hPa (Example 1), 4 hPa to 7 hPa (Example 2), 180 hPa to 250 hPa (Example 3), 4 hPa or less (Comparative Example 1). , 250 hPa or higher (Comparative Example 2). As a result, in Example 1, most of the dust adhering to the plate material can be adsorbed and removed by the adhesive roller, and the ink discharge means does not cause a failure such as clogging, and a clear image free from defects such as printing stains can be obtained. did it. In Example 2, although a small amount of dust remained on the plate, the level was satisfactory. Furthermore, in Example 3, although it was slight, depending on the printing conditions, printing stains were observed, but this was a level with no problem in practical use.
On the other hand, in Comparative Example 1, the dust adsorption capability was small, and the dust removal was impossible. Further, in Comparative Example 2, the hydrophilic surface of the plate material was damaged and stains were generated during printing.
[0108]
【The invention's effect】
According to the present invention, there is provided a plate making method in which an image is directly formed on a plate material based on a signal of image data, and the image is fixed to create a printing plate, and the density of each image dot of the image data In a plate making method in which an image forming unit that converts a level into a recording dot size and performs gradation recording, an image is formed on the printing plate by an ink jet method that discharges ink containing at least a lipophilic component. Ink discharge unit array data indicating the correspondence between each image dot and each ink discharge unit is prepared in advance for a plurality of image dots of all or part of the image, and the ink discharge unit array data is referred to. Ink discharge means corresponding to each image dot is obtained, and a discharge characteristic table of image dot density and ink discharge amount control value obtained in advance experimentally corresponding to this ink discharge means is used. Thus, by determining the ink discharge amount control value of each image dot so as to obtain the recording dot size corresponding to each image dot density of the corresponding ink discharge unit obtained, the flying characteristics of the ink discharge unit Even if there is variation, it is possible to perform drawing with accurate image dot density at a high speed by an inexpensive and simple method, and a stable and high-quality printing plate can be obtained, thus enabling low-speed and high-speed lithographic printing. .
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram schematically showing an example of a plate making apparatus used in the present invention.
FIG. 2 is an overall configuration diagram schematically showing another example of a plate making apparatus used in the present invention.
FIG. 3 is a configuration diagram schematically illustrating an example of a drawing unit of a plate making apparatus used in the present invention.
FIG. 4 is a configuration diagram schematically showing an embodiment of an ink discharge means protective cover used in the present invention.
FIG. 5 is a schematic diagram illustrating how recording dots overlap when the adjacent recording dots are drawn, depending on the difference in the characteristics of the ink ejection means used to draw the dots.
FIG. 6 is a schematic diagram showing an example of a scanning method of ink ejection means and ink ejection means array data corresponding to the scanning method.
FIG. 7 is a schematic diagram showing another example of the ink ejection unit scanning method and the corresponding ink ejection unit array data.
FIG. 8 is a schematic diagram showing an example of a gray scale image used when an ejection characteristic table and a dot overlap correction table are experimentally obtained in the present invention. FIG. 8A is an overall view of the gray scale image A, FIG. 8B is an enlarged view of a high density portion, and FIG. 8C is an enlarged view of a low density portion.
FIG. 9 shows a case where two ink ejection units adjacent to each other are recorded in the same line, FIG. 9 (a) is a high density portion where both dods are large and have overlapping portions, and (b) and (c) are In either case, one is large, and the other is a small dot in the critical state that overlaps each other, (d) is a low-density part where both dods are small and there is no overlapping part, and (e) shows a grayscale image. .
FIG. 10 shows a case where two ink ejection units adjacent to each other are alternately recorded in each row, and FIG. 10 (a) is a high-density portion where both dods are large and have overlapping portions, and (b) and (c). Is a critical density medium density part where one is large and the other is a small dot and overlaps each other, (d) is a low density part where both dods are small and have no overlapping part, and (e) is a gray scale image. Yes.
FIG. 11 is a schematic diagram illustrating an example of overlapping of adjacent recording dots.
FIG. 12 is a schematic diagram of a method for obtaining an ink ejection amount control value using an ejection characteristic table.
[Explanation of symbols]
1 Plate making equipment
2 Inkjet drawing device
5 Fixing device
6 Plate surface desensitizing device
7 Plate material automatic plate feeder
8 Plate material automatic plate removal device
9 Plate material (printing master)
10 Adhesive roller
11 drums
12 Cap stun roller
13 Grounding means
21 Image data calculation control unit
22 Ink ejection means
221 Ink discharge means protection means
23 Oil-based ink
24 Ink supply unit
25 Ink tank
26 Ink supply device
27 Stirring means
28 Ink temperature management means
29 Ink density control means
30 Encoder
31 Ink ejection means separating / attaching device
32 Ink discharge means Sub-scanning means

Claims (2)

A plate making method in which an image is directly formed on a plate material based on a signal of image data, and the image is fixed to create a printing plate, wherein the density level of each image dot of the image data is set to the size of the recording dot. In the plate making method, using an image forming means that converts the image into a gradation and forms an image on the printing plate by an ink jet method that discharges ink containing at least a lipophilic component,
Ink discharge unit array data indicating the correspondence between each image dot and each ink discharge unit is prepared in advance for a plurality of image dots of all or part of the image, and the ink discharge unit array data is referred to. An ink ejection unit corresponding to each image dot is obtained, and the obtained corresponding is obtained using an ejection characteristic table of an image dot density and an ink ejection amount control value obtained in advance experimentally corresponding to the ink ejection unit. A plate making method, wherein an ink discharge amount control value of each image dot is determined so that a recording dot size corresponding to each image dot density of the ink discharge means can be obtained. A plate making apparatus comprising at least image forming means for directly forming an image on a plate material based on a signal of image data, and image fixing means for fixing the image formed by the image forming means to obtain a printing plate The image forming means converts the density level of each image dot of the image data into a recording dot size and performs gradation recording, and simultaneously or sequentially contains ink containing at least a lipophilic component. In a plate making apparatus that is based on an ink jet method discharged from two or more dischargeable ink discharge means,
Ink discharge means array data for storing in a memory the correspondence between each image dot and each ink discharge means in advance for all or some of the plurality of image dots in the image, and referring to this ink discharge means array data, respectively. The relationship between the ink discharge means selecting means for obtaining the ink discharge means corresponding to the image dots and the ink discharge amount control value corresponding to the image dot density recorded by each ink discharge means prepared for each ink discharge means is previously set. The ejection characteristic table obtained experimentally and stored in the memory, and the ink ejection amount control value for the recording dot of the target size to be recorded by the ink ejection means selected by the ink ejection means selection means are stored in this ejection characteristic table. And a plate making apparatus comprising: an ink discharge amount control value determining means that determines the ink discharge amount using the determined value.

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