JP5453023B2 - Printing fountain solution and planographic printing plate printing method - Google Patents

Description

  The present invention relates to a fountain solution for lithographic printing. In particular, it relates to a fountain solution for lithographic printing that provides good on-press developability and stain resistance. The present invention further relates to a printing method using the fountain solution.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area, and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support is used. After exposure through a mask such as a film, development with an alkaline developer is performed to leave the image recording layer corresponding to the image area, and dissolve and remove the unnecessary image recording layer corresponding to the non-image area. And obtained a lithographic printing plate.

  Due to recent advances in this field, lithographic printing plates are now available with CTP (computer to plate) technology. That is, a lithographic printing plate can be obtained by scanning and exposing a lithographic printing plate precursor directly using a laser or a laser diode without a lith film, and developing it.

  Along with the above progress, problems related to the lithographic printing plate precursor have been changed to improvements in image formation characteristics, printing characteristics, physical characteristics and the like corresponding to the CTP technology. In addition, due to increasing interest in the global environment, environmental issues related to waste liquids associated with wet processing such as development processing have been highlighted as another issue related to lithographic printing plate precursors.

For the above environmental problems, simplification and no processing of development or plate making are directed. As one simple plate making method, a method called “on-press development” is performed. That is, after the exposure of the lithographic printing plate precursor, conventional development is not performed, but it is mounted on a printing machine as it is, and unnecessary portions of the image recording layer are removed at the initial stage of a normal printing process.
In addition, as a simple development method, a method called “gum development” in which unnecessary portions of the image recording layer are removed with a finisher or gum solution having a pH close to neutral instead of a conventional highly alkaline developer is also performed. ing.

  In the simplification of the plate making operation as described above, a system using a lithographic printing plate precursor and a light source that can be handled in a bright room or under a yellow light is preferable in terms of ease of work. A solid-state laser such as a semiconductor laser or a YAG laser emitting an infrared ray of 1200 nm is used. Further, a UV laser can be used.

  As a lithographic printing plate precursor capable of on-machine development, for example, in Patent Documents 1 and 2, a lithographic printing plate having an image recording layer (thermosensitive layer) containing a microcapsule containing a polymerizable compound on a hydrophilic support. The original edition is listed. Patent Document 3 describes a lithographic printing plate precursor in which an image recording layer (photosensitive layer) containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on a support. Further, in Patent Document 4, on-press development is possible in which an image recording layer containing a polymerizable compound and a graft polymer having a polyethylene oxide chain in the side chain or a block polymer having a polyethylene oxide block is provided on a support. A planographic printing plate precursor is described.

Conventionally, various proposals have been made as dampening water for lithographic printing that can be developed on-press.
For example, in a plate making and printing method from a photopolymerization type lithographic printing plate precursor provided with an oxygen-blocking protective layer, a means has been proposed to solve ink imperfection caused by the hydrophilic compound of the protective layer ( (See Patent Document 5).
In addition, a water-soluble polymer containing an adsorbable group and a sulfonic acid group that can be adsorbed to a support in the fountain solution as a fountain solution excellent in preventing non-image area staining of an unprocessed printing plate that can be developed on-machine. There has been proposed a means of containing (see Patent Document 6).
However, the on-press developability and stain resistance are still insufficient, and further improvements are required.

JP 2001-277740 A JP 2001-277742 A JP 2002-287334 A US Patent Application Publication No. 2003/0064318 JP 2008-62614 A JP 2007-38483 A

  An object of the present invention is to provide a fountain solution for lithographic printing that can provide good on-press developability and stain resistance. Another object of the present invention is to provide a printing method for a lithographic printing plate that can provide good on-press developability and stain resistance.

一般式（１）中、Ｒ ₁ 、Ｒ _２ はそれぞれ独立に、水素原子又はメチル基を表す。Ｌは−ＣＯ−、−Ｏ−、−ＮＨ−、二価の脂肪族基、二価の芳香族基及びそれらの組み合わせからなる群より選ばれる二価の連結基を表す。Ｙ _１ はエチレンオキシド、プロピレンオキシド、ポリエチレンオキシド、及びポリプロピレンオキシドから選ばれる鎖を表し、末端Ｘ _１ は水素原子又は炭素原子数１〜３のアルキル基を表す。Ｑはリン酸基、ホスホン酸基、スルホン酸基及びそれらの塩の基から選ばれる基を表す。
＜２＞ 前記Ｑがリン酸基又はその塩の基であることを特徴とする前記＜１＞に記載の印刷用湿し水。
＜３＞ 前記Ｙ _１ がポリエチレンオキシド鎖であることを特徴とする前記＜１＞又は＜２＞に記載の印刷用湿し水。
＜４＞ 前記ポリエチレンオキシド鎖のエチレンオキシド繰り返し単位数が２〜３０であることを特徴とする前記＜３＞に記載の印刷用湿し水。
＜５＞ 平版印刷版原版を画像露光した後、現像処理工程を経ることなく印刷機に取付け、（ａ１）一般式（Ａ）で表される基を有する繰り返し単位、並びに（ａ２）リン酸基、ホスホン酸基、スルホン酸基及びそれらの塩の基から選ばれる基を少なくとも一つ有する繰り返し単位を含むビニル共重合体を含有する印刷用湿し水と油性インキにより未露光部分を除去し、印刷することを特徴とする平版印刷版の印刷方法。

ここでＹはアルキレンオキシ基又はポリアルキレンオキシド鎖を表し、末端Ｘは炭素原子数３以下のアルキル基又は水素原子を表す。
＜６＞ 前記ビニル共重合体が一般式(１)で表されることを特徴とする前記＜５＞に記載の平版印刷版の印刷方法。

一般式（１）中、Ｒ ₁ 、Ｒ _２ はそれぞれ独立に、水素原子又はメチル基を表す。Ｌは−ＣＯ−、−Ｏ−、−ＮＨ−、二価の脂肪族基、二価の芳香族基及びそれらの組み合わせからなる群より選ばれる二価の連結基を表す。Ｙ _１ はエチレンオキシド、プロピレンオキシド、ポリエチレンオキシド、及びポリプロピレンオキシドから選ばれる鎖を表し、末端Ｘ _１ は水素原子又は炭素原子数１〜３のアルキル基を表す。Ｑはリン酸基、ホスホン酸基、スルホン酸基及びそれらの塩の基から選ばれる基を表す。
＜７＞ 前記Ｑがリン酸基又はその塩の基であることを特徴とする前記＜６＞に記載の平版印刷版の印刷方法。
＜８＞ 前記Ｙ _１ がポリエチレンオキシド鎖であることを特徴とする前記＜６＞又は＜７＞に記載の平版印刷版の印刷方法。
＜９＞ 前記ポリエチレンオキシド鎖のエチレンオキシド繰り返し単位数が２〜３０であることを特徴とする前記＜８＞に記載の平版印刷版の印刷方法。
＜１０＞ 平版印刷版原版が、陽極酸化皮膜を有するアルミニウム支持体上に、赤外線吸収染料、ラジカル重合開始剤、重合性化合物、及びポリアルキレンオキシド基を側鎖に有するポリマーを含有する画像記録層を有することを特徴とする前記＜５＞〜＜９＞のいずれか１項に記載の平版印刷版の印刷方法。
＜１１＞ 前記ポリマーが微粒子形状であることを特徴とする前記＜１０＞に記載の平版印刷版の印刷方法。
＜１２＞ 前記＜１０＞又は＜１１＞に記載のポリアルキレンオキシド基が、ポリエチレンオキシド基であることを特徴とする平版印刷版の印刷方法。
＜１３＞ 平版印刷版原版のアルミニウム支持体が、シリケートが付着した陽極酸化皮膜を有することを特徴とする前記＜１０＞〜＜１２＞のいずれか１項に記載の平版印刷版の印刷方法。
本発明は、上記＜１＞〜＜１３＞に記載の印刷用湿し水及び平版印刷版の印刷方法に関するものであるが、その他の事項についても参考のために記載する。
１．（ａ１）一般式（Ａ）で表される基を有する繰り返し単位、並びに（ａ２）リン酸基、ホスホン酸基、スルホン酸基及びそれらの塩の基から選ばれる基を少なくとも一つ有する繰り返し単位を含むビニル共重合体を含有する印刷用湿し水。 <1> A fountain solution for printing, comprising a vinyl copolymer represented by the general formula (1).

In general formula (1), R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group. L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Y ₁ represents a chain selected from ethylene oxide, propylene oxide, polyethylene oxide, and polypropylene oxide, and the terminal X ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Q represents a group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, and a salt thereof.
<2> The fountain solution for printing according to <1>, wherein the Q is a phosphate group or a salt group thereof.
<3> The fountain solution for printing according to <1> or <2>, wherein the Y ₁ is a polyethylene oxide chain.
<4> The fountain solution for printing according to <3>, wherein the polyethylene oxide chain has 2 to 30 ethylene oxide repeating units.
<5> After image exposure of the lithographic printing plate precursor, it is attached to a printing machine without passing through a development processing step, (a1) a repeating unit having a group represented by formula (A), and (a2) a phosphate group Removing an unexposed portion with a fountain solution and oil-based ink containing a vinyl copolymer containing a repeating unit having at least one group selected from a phosphonic acid group, a sulfonic acid group and a salt thereof; A printing method of a lithographic printing plate characterized by printing.

Here, Y represents an alkyleneoxy group or a polyalkylene oxide chain, and the terminal X represents an alkyl group having 3 or less carbon atoms or a hydrogen atom.
<6> The printing method of a lithographic printing plate as described in <5>, wherein the vinyl copolymer is represented by the general formula (1).

In general formula (1), R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group. L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Y ₁ represents a chain selected from ethylene oxide, propylene oxide, polyethylene oxide, and polypropylene oxide, and the terminal X ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Q represents a group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, and a salt thereof.
<7> The printing method of a lithographic printing plate as described in <6>, wherein the Q is a phosphate group or a salt group thereof.
<8> The printing method of a lithographic printing plate as described in <6> or <7>, wherein Y ₁ is a polyethylene oxide chain.
<9> The printing method of a lithographic printing plate as described in <8>, wherein the polyethylene oxide chain has 2 to 30 ethylene oxide repeating units.
<10> An image recording layer in which the lithographic printing plate precursor contains an infrared absorbing dye, a radical polymerization initiator, a polymerizable compound, and a polymer having a polyalkylene oxide group in the side chain on an aluminum support having an anodized film The printing method of a lithographic printing plate as described in any one of the above items <5> to <9>, comprising:
<11> The printing method of a lithographic printing plate as described in <10>, wherein the polymer is in the form of fine particles.
<12> The printing method of a lithographic printing plate, wherein the polyalkylene oxide group according to <10> or <11> is a polyethylene oxide group.
<13> The printing method of a lithographic printing plate as described in any one of <10> to <12>, wherein the aluminum support of the lithographic printing plate precursor has an anodized film to which a silicate is adhered.
The present invention relates to a printing dampening solution and a printing method for a lithographic printing plate as described in <1> to <13> above, but other matters are also described for reference.
1. (A1) a repeating unit having a group represented by the general formula (A), and (a2) a repeating unit having at least one group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group and a salt thereof. A dampening solution for printing containing a vinyl copolymer containing

  Here, Y represents an alkyleneoxy group or a polyalkylene oxide chain, and the terminal X represents a hydrocarbon group having 3 or less carbon atoms or a hydrogen atom.

式中、Ｒ₁、Ｒ_２はそれぞれ独立に、水素原子又はメチル基を表す。Ｌは−ＣＯ−、−Ｏ−、−ＮＨ−、二価の脂肪族基、二価の芳香族基及びそれらの組み合わせからなる群より選ばれる二価の連結基を表す。Ｙ_１はエチレンオキシド、プロピレンオキシド、ポリエチレンオキシド、及びポリプロピレンオキシドから選ばれる鎖を表し、末端Ｘ_１は水素原子又は炭素数１〜３のアルキル基を表す。Ｑはリン酸基、ホスホン酸基、スルホン酸基及びそれらの塩の基から選ばれる基を表す。 2. 2. The fountain solution for printing according to 1 above, wherein the vinyl copolymer is represented by the general formula (1).

In the formula, R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group. L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Y ₁ represents a chain selected from ethylene oxide, propylene oxide, polyethylene oxide, and polypropylene oxide, and the terminal X ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Q represents a group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, and a salt thereof.

3. 3. The fountain solution for printing according to 2 above, wherein Q is a phosphate group or a salt group thereof.
4). 4. The fountain solution for printing according to 2 or 3, wherein Y ₁ is a polyethylene oxide chain.
5. 5. The fountain solution for printing according to 4 above, wherein the polyethylene oxide chain has 2 to 30 ethylene oxide repeating units.
6). After image exposure of the lithographic printing plate precursor, it is attached to a printing machine without going through a development processing step, and the unexposed part is removed with the fountain solution for printing and oil-based ink according to any one of 1 to 5 above, A printing method of a lithographic printing plate characterized by printing.
7). The lithographic printing plate precursor has an image recording layer containing an infrared absorbing dye, a radical polymerization initiator, a polymerizable compound, and a polymer having a polyalkylene oxide group in the side chain on an aluminum support having an anodized film. 7. The printing method of a lithographic printing plate as described in 6 above.
8). 8. The printing method of a lithographic printing plate as described in 7 above, wherein the polymer is in the form of fine particles.
9. The printing method of a lithographic printing plate, wherein the polyalkylene oxide group described in 7 or 8 is a polyethylene oxide group.
10. 10. The printing method of a lithographic printing plate as described in any one of 7 to 9 above, wherein the aluminum support of the lithographic printing plate precursor has an anodic oxide film having a silicate attached thereto.

In the present invention, (a1) a repeating unit having a group represented by the general formula (A), and (a2) a group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, and a salt group thereof. By adding a vinyl copolymer having at least one repeating unit to the fountain solution for printing, and further adding a polymer having a polyalkylene oxide group in the side chain to the image recording layer, other performance can be achieved. It was possible to achieve good on-press developability and stain resistance without damage.
Although the mechanism of this action is not always clear, the group represented by the general formula (A) of the vinyl copolymer in the fountain solution interacts with the polyalkylene oxide chain of the polymer in the image recording layer to cause the image recording layer. In addition, the vinyl copolymer is adsorbed on the surface of the support by acidic groups to prevent re-adhesion of the image recording layer components to the support. It is presumed that both the on-press developability and stain resistance are improved because the hydrophilicity is retained by the repeating unit.

  ADVANTAGE OF THE INVENTION According to this invention, the fountain solution for lithographic printing from which favorable on-machine developability and stain | fouling property are obtained, and the printing method of a lithographic printing plate can be provided.

[Dampening solution for lithographic printing]
Hereinafter, the present invention will be described in detail. Commercially available dampening water is usually a concentrated liquid type for reasons such as distribution convenience, and when used, the concentrated liquid is appropriately diluted and used as dampening water. In the present specification, the concentrated product is referred to as a fountain solution composition. The contents and addition amounts of various components mentioned below are values relative to the fountain solution at the time of use unless otherwise specified.

  The fountain solution for lithographic printing of the present invention (also simply referred to as “fountain solution”) is a repeating unit having a group represented by the general formula (A) (hereinafter also referred to as “hydrophilic group repeating unit”).

And a repeating unit having at least one group selected from the group consisting of a phosphonic acid group, a phosphoric acid group, a sulfonic acid group, and a group of these salts (hereinafter also referred to as “acidic repeating unit”). It contains a vinyl copolymer (hereinafter also referred to as “specific copolymer”).
Here, Y represents an alkyleneoxy group or a polyalkylene oxide chain, and the terminal X represents an alkyl group having 3 or less carbon atoms or a hydrogen atom.

(Specific copolymer)
The specific copolymer of the present invention is a vinyl copolymer having a hydrophilic group repeating unit and an acidic group repeating unit.
The specific copolymer of the present invention is preferably a copolymer represented by the following general formula (1).

In the formula, R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group. L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Y ₁ represents a connecting chain selected from ethylene oxide, propylene oxide, polyethylene oxide, and polypropylene oxide, and the terminal X ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Q represents a group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, and a salt thereof.
Formula (1), the unit comprising a -Y ₁ -X ₁ is a repeating unit hydrophilic groups, units containing a Q is a repeating unit acidic group.

In the hydrophilic group repeating unit, Y ₁ is particularly preferably a polyethylene oxide chain or a polypropylene oxide chain.
Furthermore, the hydrophilic group repeating unit is preferably a repeating unit represented by the following formula (T-1) or (T-2), and the repeating unit having a polyethylene oxide chain represented by (T-1) is Particularly preferred.

In formulas (T-1) and (T-2), R ¹ represents a hydrogen atom or a methyl group, and A ¹ represents a divalent linking group of —COO— or —CONH—. n represents an integer of 2 or more.

The terminal X ₁ of the group containing the polyalkylene oxide chain represents a hydrocarbon group having 3 or less carbon atoms or a hydrogen atom. A methyl group or a hydrogen atom is preferable. The propylene oxide group of (T-2) may be linear or branched.

  The number n of repeating alkylene oxide chains is preferably an integer of 2 to 30, more preferably 2 to 20, and particularly preferably 2 to 10.

The specific copolymer that can be used in the present invention may have only one type of hydrophilic group repeating unit, or two or more types.
The content ratio of the hydrophilic group repeating unit in the specific copolymer that can be used in the present invention is preferably 30 to 98 mol%, and preferably 40 to 90 mol%, based on all repeating units of the specific copolymer. It is more preferable that it is 50 to 80 mol%.

More specifically, Q in the general formula (1) is more specifically a phosphonic acid group [—PO (OH) ₂ ], a phosphoric acid group [—OPO (OH) ₂ ], a sulfonic acid group [—SO ₃ H], and these. Salt groups of [-PO (OH) (OM), -PO (OM) ₂ , -OPO (OH) (OM), -OPO (OM) ₂ , -SO ₃ M (where M is a proton (H ⁺ Represents a counter cation other than)))]. The counter cation other than the proton is not particularly limited, and may be an inorganic cation such as a metal cation, an organic cation such as a tetraalkylammonium ion, or a polymer cation. Good. The counter cation may be a monovalent counter cation or a divalent or higher counter cation.

  The phosphonic acid and phosphoric acid-based acidic group repeating unit is preferably a repeating unit represented by the following formula (U-1) or (U-2), and is a repeating unit represented by the formula (U-2). It is more preferable.

In formulas (U-1) and (U-2), R ² represents a hydrogen atom or a methyl group, and A ² represents a single bond or a (n + 1) -valent linking group. A ² is preferably an organic group composed of a combination of elements selected from a carbon atom, a hydrogen atom, an oxygen atom, and a nitrogen atom. X ¹ and X ² each independently represent a hydrogen atom or a counter cation other than a proton, and n represents an integer of 1 or more.

The counter cation other than protons in X ¹ and X ² is not particularly limited, and may be an inorganic cation such as a metal cation or an organic cation such as a tetraalkylammonium ion, or a polymer cation. It may be. The counter cation may be a monovalent counter cation or a divalent or higher counter cation.
The n is preferably an integer of 1 to 5, preferably 1 or 2, and particularly preferably 1.

  The acidic group repeating unit is more preferably a repeating unit represented by the following formula (U-3) or (U-4).

In formulas (U-3) and (U-4), A ³ represents a divalent organic group. R ^2, X ¹ and X ² has the same meaning as R ^2, X ¹ and X ² in the formula (U-1) and (U-2), and preferred ranges are also the same.

The divalent organic group in A ³ in the formula (U-4) is preferably an organic group composed of a combination of elements selected from a carbon atom, a hydrogen atom, and an oxygen atom. It is preferably an oxy group or a polyalkyleneoxy group. Further, the alkylene group and the polyalkyleneoxy group may be linear or branched. The number of carbon atoms of A ³ in (U-4) is preferably 1-30, more preferably 1-20, and even more preferably 2-10.

Specific examples of the acidic group repeating unit include those represented by the following (A-1) to (A-4). In (A-1) and (A-2), 1 to 12 is preferable for p, and 2 to 8 is particularly preferable.
In the present invention, the hydrocarbon chain of the compound or its partial structure may be described by a simplified structural formula in which symbols for carbon (C) and hydrogen (H) are omitted.

  Next, as the sulfonic acid-based acidic group repeating unit, repeating units represented by the following formulas (U-5) and (U-6) are preferable.

Wherein (U-5) and ^{(U-6), R 2} , X 1 and n are as defined R ^2, X ¹ and n in the formula (U-1) and (U-2), a preferred range Is the same.
R ³ and R ⁴ each independently represents a hydrogen atom or a monovalent hydrocarbon group. A monovalent hydrocarbon group is preferred, an alkyl group having 1 to 8 carbon atoms is more preferred, and a methyl group is still more preferred.
A ⁴ represents a single bond or an (n + 1) valent organic group, A ⁵ represents an (n + 1) valent organic group, and A ⁶ represents a divalent organic group.

Examples of the (n + 1) -valent organic group represented by A ⁴ in the formula (U-5) and the (n + 1) -valent organic group represented by A ⁵ in the formula (U-6) include carbon and hydrogen. A group formed from an element selected from the group consisting of oxygen and nitrogen is preferred, and a group formed from an element selected from the group consisting of carbon, hydrogen and oxygen is more preferred. In particular, a group having an ester bond or an amide bond is preferable.
The divalent organic group represented by A ⁶ in the formula (U-6) is preferably a group formed from an element selected from the group consisting of carbon, hydrogen, and oxygen. More preferably, it is a group.

  The sulfonic acid-based acidic group repeating unit is more preferably a repeating unit represented by the following formulas (U-7) to (U-9).

Formula (U-7) ~ R ² and X ¹ in (U-9) has the same meaning as R ² and X ¹ in Formula (U-1) ~ (U -2), and preferred ranges are also the same. R ³ and R ⁴ in the formula (U-9) has the same meaning as R ³ and R ⁴ in the formula (U-6), and preferred ranges are also the same.

A ^{7 in the} formulas (U-7) and (U-8) represents a divalent organic group, preferably a linear or branched alkylene group, and is a linear or branched alkylene group having 2 to 20 carbon atoms. It is more preferable that it is a linear or branched alkylene group having 2 to 10 carbon atoms.
A ^{8 in} formula (U-9) represents a divalent organic group, preferably a linear or branched alkylene group, more preferably a linear or branched alkylene group having 2 to 20 carbon atoms, A linear or branched alkylene group having a number of 2 to 10 is more preferable.
A ^{9 in} Formula (U-9) represents a divalent organic group, preferably a linear or branched alkylene group, more preferably a linear or branched alkylene group having 1 to 10 carbon atoms, A linear or branched alkylene group having 1 to 4 is more preferable.

  Specific examples of preferred acidic group repeating units of the sulfonic acid type include repeating units represented by the following (H-1) to (H-6). Moreover, the repeating unit in which the sulfonic acid group of the repeating unit represented by the following (H-1) to (H-4) forms a salt is also preferable.

The specific copolymer that can be used in the present invention may have only one type of acidic group repeating unit or two or more types.
The content ratio of the acidic group repeating unit in the specific copolymer that can be used in the present invention is preferably 2 to 80 mol%, preferably 10 to 60 mol%, based on all repeating units of the specific copolymer. It is more preferable that it is 20 to 50 mol%.

Moreover, the specific copolymer which can be used for this invention may have another repeating unit other than an acidic group repeating unit and a hydrophilic group repeating unit. There is no restriction | limiting in particular as another repeating unit, What is necessary is just a repeating unit obtained by copolymerizing a well-known monomer.
The content ratio of other repeating units in the specific copolymer that can be used in the present invention is preferably 40 mol% or less, and preferably 30 mol% or less, based on all repeating units of the specific copolymer. Is more preferable, and it is still more preferable that it is 20 mol% or less.

The specific copolymer is a vinyl copolymer.
The vinyl copolymer is, for example, a monomer having an ethylenically unsaturated bond such as acrylates, methacrylates, styrenes, aromatic vinyl compounds, aliphatic vinyl compounds, allyl compounds, acrylic acid, methacrylic acid, and the like. It is a copolymer obtained by copolymerizing two or more monomers.
The specific copolymer may be any copolymer such as a random copolymer, a block copolymer, or a graft copolymer, but is preferably a random copolymer.
The acidic group repeating unit, hydrophilic group repeating unit, and other repeating units are monomer units obtained from a monomer having an ethylenically unsaturated bond.

The mass average molar mass (Mw) of the specific copolymer of the present invention is preferably 5,000 to 200,000, and more preferably 10,000 to 150,000.
The number average molar mass (Mn) of the specific copolymer of the present invention is preferably 1,000 or more, and more preferably 2,000 to 2,000,000 or less.
The polydispersity (mass average molar mass / number average molar mass) of the specific copolymer of the present invention is preferably 1.1-10.

The fountain solution of the present invention may contain one specific copolymer alone or two or more.
The content of the specific copolymer in the fountain solution of the present invention is preferably 0.005 to 10% by mass, more preferably 0.01 to 5% by mass, and 0.05 to 3% by mass. More preferably. Within the above range, good on-press developability and anti-staining effect on the non-image area and the halftone image area can be obtained.

(Other ingredients used for fountain solution)
A water-soluble polymer compound may be further added to the fountain solution of the present invention.
Specific examples of water-soluble polymer compounds include gum arabic, starch derivatives (eg, dextrin, enzymatically degraded dextrin, hydroxypropylated enzymatically degraded dextrin, carboxymethylated starch, phosphate starch, octenyl succinated starch, etc.), alginate, fiber Natural products and modified products thereof, such as carboxymethylcellulose, carboxyethylcellulose, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, glyoxal modified products thereof, polyvinyl alcohol and derivatives thereof, polyvinylpyrrolidone, polyacrylamide and Its copolymer, polyacrylic acid and its copolymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride Synthesis of such acid copolymers. These polymer compounds can be used alone or as a mixture, and the addition amount thereof is 0.0001 to 5% by mass, more preferably 0.003 to 1% by mass in dampening water.

  In the present invention, among the above water-soluble polymer compounds, polyvinyl pyrrolidone can be particularly preferably used. The content of polyvinyl pyrrolidone in the fountain solution is suitably 0.001 to 0.3% by mass, preferably 0.005 to 0.2% by mass.

The fountain solution is generally desirably used in the acidic region, that is, in the range of pH around 3-6. When the pH is less than 3, the etching effect on the support becomes strong and the printing durability is lowered. In order to adjust the pH value to 3 to 6, generally, an organic acid and / or an inorganic acid or a salt thereof may be added. Preferred organic acids include, for example, citric acid, maleic acid, ascorbic acid, malic acid, tartaric acid, lactic acid, acetic acid, glycolic acid, gluconic acid, hydroxyacetic acid, succinic acid, malonic acid, levulinic acid, sulfanilic acid, p-toluenesulfonic acid , Phytic acid, organic phosphonic acid and the like. Examples of the inorganic acid include phosphoric acid, nitric acid, sulfuric acid, and polyphosphoric acid. Further, alkali metal salts, alkaline earth metal salts or ammonium salts of these organic acids and / or inorganic acids, and organic amine salts are also preferably used. These organic acids, inorganic acids and / or salts thereof can be used alone. Or you may use as a mixture of 2 or more types. The addition amount is generally 0.001 to 5% by mass in dampening water.
The fountain solution of the present invention can also contain an alkali metal hydroxide, an alkali metal phosphate, an alkali metal carbonate, a silicate, etc., and can be used in an alkaline region near pH 7-11.

  A small amount of a surfactant may be added to the fountain solution of the present invention. For example, anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinates, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfones. Acid salts, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, sodium N-methyl-N-oleyl taurate, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, hydrogenated castor oil , Sulfated beef oil, fatty acid alkyl ester sulfate ester salt, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, fatty acid monoglyceride Acid ester salts, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, styrene Examples thereof include partially saponified products of maleic anhydride copolymers, partially saponified products of olefin-maleic anhydride copolymers, and naphthalene sulfonate formalin condensates. Among these, dialkyl sulfosuccinates, alkyl sulfates and alkyl naphthalene sulfonates are particularly preferably used.

  Nonionic surfactants include polyoxyalkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyryl phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial esters, sorbitan fatty acid moieties. Esters, pentaerythritol fatty acid partial esters, propylene glycol mono fatty acid partial esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyglycerin fatty acid partial esters, poly Oxyethylenated castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N, N-bis-2-hydroxy Alkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, such as trialkylamine oxides. Of these, polyoxyethylene alkylphenyl ethers, polyoxyethylene-polyoxypropylene block polymers and the like are preferably used.

Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, polyethylene polyamine derivatives, and the like. Examples of amphoteric surfactants include alkyl imidazolines.
Further examples include fluorine-based surfactants. Examples of fluorine-based anionic surfactants include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphate esters, and fluorine-based nonionic surfactants. Examples of the perfluoroalkylethylene oxide adduct, perfluoroalkylpropylene oxide adduct, and fluorine-based cationic surfactant include perfluoroalkyltrimethylammonium salts.
The content of these surfactants is 10% by mass or less, preferably 0.01 to 3.0% by mass in dampening water in view of foaming.

Furthermore, the fountain solution of the present invention can contain glycols and / or alcohols as a wetting agent. Examples of such wetting agents include propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol and pentapropylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, butylene glycol, hexylene glycol, ethyl alcohol, n -Propyl alcohol, benzyl alcohol, glycerin, diglycerin, polyglycerin, pentaerythritol and the like.
These wetting agents can be contained alone or in combination of two or more in an amount of about 0.01 to 1% by mass in dampening water.

  In addition to the above components, the fountain solution of the present invention may contain a chelating agent, preservative, colorant, rust inhibitor, antifoaming agent, and the like.

The balance is water as a component of the fountain solution of the present invention. The water is preferably demineralized water, that is, pure water.
In the case where the fountain solution is used as a commercial product, the fountain solution composition that is a concentrated type of the above-described fountain solution is manufactured in consideration of the dilution rate during use. Such a concentrated solution is usually used as a dampening solution by diluting it about 10 to 200 times with tap water, well water or the like at the time of use.

[Lithographic printing plate precursor]
The lithographic printing plate precursor to which the fountain solution of the present invention is applied (hereinafter also referred to as the lithographic printing plate precursor of the present invention) preferably has an on-press developable image recording layer on the support. Moreover, the lithographic printing plate precursor according to the invention may optionally have a protective layer on the image recording layer and an undercoat layer between the support and the image recording layer.
The components and components of the lithographic printing plate precursor according to the invention will be described below.

(Image recording layer)
The image recording layer used in the lithographic printing plate precursor according to the invention (hereinafter also referred to as “image recording layer used in the invention” or “image recording layer of the invention”) is a polymer having a polyalkylene oxide group in the side chain. And an image recording layer that can be developed on-press. The image recording layer used in the present invention preferably further contains (A) an infrared absorbing dye (also referred to as an infrared absorber), (B) a radical polymerization initiator, and (C) a polymerizable compound. Below, each component which can be contained in an image recording layer is demonstrated one by one.

(A) Infrared-absorbing dye The infrared-absorbing dye has a function of converting absorbed infrared light into heat and a function of being excited by infrared light and transferring electrons and / or energy to a radical generator described later. The infrared absorbing dye used in the present invention is a dye having an absorption maximum at a wavelength of 760 to 1200 nm.

As the infrared absorbing dye, compounds described in paragraph numbers [0058] to [0087] of JP-A-2008-195018 can be used.
Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and nickel thiolate complexes. Particularly preferred examples include cyanine dyes represented by the following general formula (a).

In the general formula (a), X ¹ represents a hydrogen atom, a halogen ^{atom, -N (R 9) (R} 10), - X ² -L ¹ or a group shown below. Here, R ⁹ and R ¹⁰ may be the same or different, and may have a substituent, an aromatic hydrocarbon group having 6 to 10 carbon atoms, or an alkyl group having 1 to 8 carbon atoms. Represents a hydrogen atom, and R ⁹ and R ¹⁰ may be bonded to each other to form a ring. Of these, a phenyl group is preferred. X ² represents an oxygen atom or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a hydrocarbon group having 1 to 12 carbon atoms including a hetero atom. . In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. In the group shown below, Xa ^- has Za described later ^- is defined as for, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom .

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the image recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring. Alternatively, it is particularly preferable that a 6-membered ring is formed.

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxy groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (a) has an anionic substituent in its structure and charge neutralization is not necessary. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of the storage stability of the image recording layer coating solution. , Hexafluorophosphate ions, and aryl sulfonate ions.

  Specific examples of the cyanine dye represented by the general formula (a) that can be suitably used in the present invention include paragraph numbers [0017] to [0019] of JP-A No. 2001-133969 and JP-A No. 2002-023360. Examples thereof include those described in paragraph Nos. [0012] to [0021] of Japanese Patent Publication No. and paragraph Nos. [0012] to [0037] of JP-A No. 2002-040638.

  Moreover, only 1 type may be used for these (A) infrared absorption dyes, and 2 or more types may be used together, and infrared absorbers other than infrared absorption dyes, such as a pigment, may be used together. As the pigment, compounds described in JP 2008-195018 A [0072] to [0076] are preferable.

  The content of the infrared absorbing dye in the image recording layer in the present invention is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass of the total solid content of the image recording layer. .

(B) Radical generator The (B) radical generator used in the image recording layer of the invention is a compound that initiates and accelerates the polymerization of a polymerizable compound (C) described later. The radical generator that can be used in the present invention is preferably a radical polymerization initiator, and a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, and the like can be used.
Examples of the radical polymerization initiator include (a) organic halides, (b) carbonyl compounds, (c) azo compounds, (d) organic peroxides, (e) metallocene compounds, (f) azide compounds, ( g) hexaarylbiimidazole compound, (h) organic borate compound, (i) disulfone compound, (j) oxime ester compound, (k) onium salt compound.

  (A) As the organic halide, compounds described in paragraph numbers [0022] to [0023] of JP-A-2008-195018 are preferable.

  (B) As the carbonyl compound, compounds described in paragraph [0024] of JP-A-2008-195018 are preferable.

  (C) As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.

  (D) As the organic peroxide, for example, compounds described in paragraph [0025] of JP-A-2008-195018 are preferable.

  As the (e) metallocene compound, for example, the compound described in paragraph [0026] of JP-A-2008-195018 is preferable.

(F) Examples of the azide compound include 2,6-bis (4-azidobenzylidene) -4-methylcyclohexanone.
(G) As the hexaarylbiimidazole compound, for example, a compound described in paragraph [0027] of JP-A-2008-195018 is preferable.

  (H) As the organic borate compound, for example, a compound described in paragraph [0028] of JP-A-2008-195018 is preferable.

  (I) Examples of the disulfone compound include compounds described in JP-A Nos. 61-166544 and 2002-328465.

  (J) As the oxime ester compound, for example, compounds described in paragraph numbers [0028] to [0030] of JP-A-2008-195018 are preferable.

  (K) Examples of the onium salt compounds include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055, 4,069,056, phosphonium salts described in European Patent Nos. 104,143, U.S. Pat. Nos. 339,049, 410,201, U.S. Patent Application Publication No. 2008 No. 0311520, iodonium salts described in JP-A-2-150848, JP-A-2-296514, JP-A-2008-195018, European Patent Nos. 370,693 and 390,214. 233,567, 297,443, 297,442, U.S. Pat.Nos. 4,933,377, 161,811 410,201, 339,049, 4,760,013, 4,734,444, 2,833,827, German Patent 2,904,626, 3 , 604, 580, and 3,604, 581, the sulfonium salts described in the respective specifications; V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), and onium salts such as azinium salts described in JP-A-2008-195018.

  Of these, more preferred are onium salts, especially iodonium salts, sulfonium salts and azinium salts. Although the specific example of these compounds is shown below, it is not limited to this.

  As an example of the iodonium salt, a diphenyl iodonium salt is preferable, and a diphenyl iodonium salt substituted with an electron donating group such as an alkyl group or an alkoxyl group is particularly preferable, and an asymmetric diphenyl iodonium salt is more preferable. Specific examples include diphenyliodonium = hexafluorophosphate, 4-methoxyphenyl-4- (2-methylpropyl) phenyliodonium = hexafluorophosphate, 4- (2-methylpropyl) phenyl-p-tolyliodonium = hexa. Fluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium = tetrafluoroborate, 4-octyloxy Phenyl-2,4,6-trimethoxyphenyliodonium = 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, bis ( -t- butylphenyl) iodonium tetraphenylborate and the like.

  Examples of sulfonium salts include triphenylsulfonium = hexafluorophosphate, triphenylsulfonium = benzoylformate, bis (4-chlorophenyl) phenylsulfonium = benzoylformate, bis (4-chlorophenyl) -4-methylphenylsulfonium = Examples include tetrafluoroborate and tris (4-chlorophenyl) sulfonium = 3,5-bis (methoxycarbonyl) benzenesulfonate.

  Examples of azinium salts include 1-cyclohexylmethyloxypyridinium = hexafluorophosphate, 1-cyclohexyloxy-4-phenylpyridinium = hexafluorophosphate, 1-ethoxy-4-phenylpyridinium = hexafluorophosphate, 1-cyclohexyl (2-ethylhexyloxy) -4-phenylpyridinium = hexafluorophosphate, 4-chloro-1-cyclohexylmethyloxypyridinium = hexafluorophosphate, 1-ethoxy-4-cyanopyridinium = hexafluorophosphate, 3,4 -Dichloro-1- (2-ethylhexyloxy) pyridinium = hexafluorophosphate, 1-benzyloxy-4-phenylpyridinium = hexafluorophosphate, 1-phenethylo Ci-4-phenylpyridinium = hexafluorophosphate, 1- (2-ethylhexyloxy) -4-phenylpyridinium = p-toluenesulfonate, 1- (2-ethylhexyloxy) -4-phenylpyridinium = perfluorobutanesulfonate 1- (2-ethylhexyloxy) -4-phenylpyridinium bromide, 1- (2-ethylhexyloxy) -4-phenylpyridinium tetrafluoroborate.

  The radical generator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass with respect to the total solid content constituting the image recording layer. Can be added. Within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained.

(C) Polymerizable compound The polymerizable compound (C) that can be used in the image recording layer of the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and has a terminal ethylenically unsaturated bond. Is preferably selected from compounds having at least 1, preferably 2 or more. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and their (co) polymers.

  Specific examples include the compounds described in JP-A-2008-105018, paragraph numbers [0089] to [0098]. Among them, preferred are esters of aliphatic polyhydric alcohol compounds and unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and the like). Another preferred polymerizable compound is a polymerizable compound having an isocyanuric acid structure described in JP-A-2005-329708.

  Among them, tris (acryloyloxyethyl) isocyanurate, bis (acryloyloxyethyl) hydroxyethyl isocyanurate, etc. are excellent in the balance between the hydrophilicity involved in on-press developability and the polymerization ability involved in printing durability. Isocyanuric acid ethylene oxide modified acrylates are particularly preferred.

  In the present invention, the polymerizable compound (C) is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass, based on the total solid content of the image recording layer.

(D) Polymer having polyalkylene oxide group The image recording layer of the present invention contains a polymer in order to provide on-press developability. In particular, a polymer having a polyalkylene oxide group is preferable. A polymer having a polyalkylene oxide group, particularly a polymer having a polyalkylene oxide group in the side chain, does not have a specific shape such as a particle shape even if it is contained in the form of fine particles in the image recording layer, and image recording It may be included as a medium (hereinafter referred to as a binder in the present invention) for dissolving or bonding various materials in the layer.
In any case, by introducing a polyalkylene oxide group into the side chain of such a polymer, the permeability of the fountain solution is improved by interacting with the polymer having the polyalkylene oxide present in the fountain solution. On-machine developability is improved.

(D-1) Polymer fine particles In the present invention, polymer fine particles can be used in order to improve the on-press developability. The polymer fine particles in the present invention are preferably at least one fine particle selected from hydrophobic thermoplastic polymer fine particles, heat-reactive polymer fine particles, microcapsules enclosing a hydrophobic compound, and crosslinked polymer fine particles (microgel).

  In the present invention, the polymer fine particles preferably have a polyalkylene oxide structure. This polyalkylene oxide structure interacts with the polyalkylene oxide group of the specific copolymer in the fountain solution, and the on-press developability is improved. In particular, the alkylene oxide group is preferably an ethylene oxide group, and the ethylene oxide group is preferably a polyethylene oxide group having 12 to 250 repeating units.

  The introduction of the polyalkylene oxide structure into the polymer fine particles is, for example, a repeating unit represented by the formula (T-1) or (T-2) in the case of hydrophobic thermoplastic polymer fine particles / thermo-reactive polymer fine particles. There is a method of emulsion polymerization or suspension polymerization of a monomer having a polyalkylene oxide structure corresponding to. In this case, as a monomer to be copolymerized, specific examples of polymers constituting such polymer fine particles include ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride. , Acrylonitrile, vinyl carbazole, homopolymers or copolymers of monomers such as acrylates or methacrylates having a polyalkylene structure, or mixtures thereof. Among them, more preferable examples include a copolymer containing polystyrene, styrene and acrylonitrile, and polymethyl methacrylate.

Hydrophobic thermoplastic polymer fine particles refer to Research Disclosure No. 1 of January 1992. 33303, JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250 and European Patent No. 931647, etc. It means fine particles that become hydrophobized by fusing with heat generated during the process.
The heat-reactive polymer fine particles include polymer fine particles having a heat-reactive group, and these mean fine particles that form a hydrophobized region by crosslinking due to a thermal reaction and a functional group change at that time.
The thermally reactive group in the polymer fine particle having a thermally reactive group used in the present invention may be any functional group that performs a reaction as long as a chemical bond is formed, but is an ethylenically unsaturated group that performs a radical polymerization reaction. Group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.), cationically polymerizable group (for example, vinyl group, vinyloxy group, etc.), isocyanate group that performs addition reaction or its block, epoxy group, vinyloxy group And a functional group having an active hydrogen atom as a reaction partner (for example, an amino group, a hydroxy group, a carboxy group, etc.), a carboxy group for performing a condensation reaction, a hydroxy group or an amino group as a reaction partner, a ring-opening addition reaction Examples of suitable acid anhydrides and reaction partners are amino groups or hydroxy groups. .

In the case of microcapsules or microgels, the introduction of the polyalkylene oxide structure into the polymer fine particles is, for example, a known method such as a method of adding polyalkylene oxide monoalkyl ether to a component of interfacial polymerization using a polyfunctional isocyanate, This can be done as an application of the following description regarding polymer fine particles.
As the microcapsules used in the present invention, for example, as described in JP-A Nos. 2001-277740 and 2001-277742, all or part of the constituent components of the image recording layer are encapsulated in the microcapsules. Is. The constituent components of the image recording layer can also be contained outside the microcapsules. Furthermore, it is preferable that the image recording layer containing the microcapsule includes a hydrophobic constituent component in the microcapsule and a hydrophilic constituent component outside the microcapsule.

  In this invention, the aspect containing a crosslinked resin particle, ie, a microgel, may be sufficient. This microgel can contain a part of the components of the image recording layer in and / or on the surface thereof. In particular, the microgel has a reactive microgel by having (C) a polymerizable compound on the surface thereof. From the viewpoint of image formation sensitivity and printing durability, it is particularly preferable.

  As a method for microencapsulating or microgelling the constituent components of the image recording layer, known methods can be applied.

  The average particle size of the polymer fine particles is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is still more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

  The content of the polymer fine particles is preferably in the range of 5 to 90% by mass of the total solid content of the image recording layer.

(D-2) Binder polymer In the image recording layer of the present invention, a binder polymer can be used as a binder for each component of the image recording layer and for improving the film strength. As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and polymers having film properties are preferred. Of these, acrylic resins, polyvinyl acetal resins, and polyurethane resins are preferable.
It is particularly preferable that the binder polymer has an alkylene oxide structure as a hydrophilic group from the viewpoint of improving the on-press developability. The alkylene oxide group is preferably an ethylene oxide group, and is preferably a polyethylene oxide group having 2 to 8 repeating units of the ethylene oxide group. Particularly preferred is an acrylic resin obtained by copolymerizing a monomer having a polyalkylene oxide structure corresponding to the repeating unit represented by the formula (T-1) or (T-2).
It is considered that the alkylene oxide structure of the binder polymer interacts with the alkylene oxide group of the specific copolymer in the fountain solution used in the present invention, and the on-press developability is improved.

  In addition, in the binder polymer of the present invention, an oleophilic group such as an alkyl group, an aryl group, an aralkyl group, or an alkenyl group can be introduced in order to control the inking property. Specifically, a lipophilic group-containing monomer such as an alkyl methacrylate may be copolymerized.

  Among them, as a binder polymer suitable for the present invention, as described in JP-A-2008-195018, a crosslinkable functional group for improving the film strength of the image portion is a main chain or a side chain, preferably a side chain. Have the following. Crosslinking is formed between the polymer molecules by the crosslinkable group, and curing is accelerated.

  The crosslinkable functional group is preferably an ethylenically unsaturated group such as a (meth) acryl group, a vinyl group or an allyl group, or an epoxy group, and these groups can be introduced into the polymer by polymer reaction or copolymerization. . For example, a reaction between an acrylic polymer or polyurethane having a carboxy group in the side chain and polyurethane and glycidyl methacrylate, or a reaction between a polymer having an epoxy group and an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid can be used.

  The content of the crosslinkable group in the binder polymer is preferably 0.1 to 10.0 mmol, more preferably 1.0 to 7.0 mmol, and most preferably 2.0 to 5.5 mmol per 1 g of the binder polymer. .

The binder polymer can further have a hydrophilic group other than the polyalkylene oxide structure. Examples of other hydrophilic groups include a hydroxy group, a carboxy group, an amino group, an ammonium group, an amide group, a sulfo group, and a phosphoric acid group. The hydrophilic group contributes to imparting on-press developability to the image recording layer. In particular, the coexistence of the crosslinkable group and the hydrophilic group makes it possible to achieve both printing durability and developability.
In order to impart a hydrophilic group to the binder polymer, a monomer having a hydrophilic group may be copolymerized.

  Specific examples (1) to (11) of the binder polymer used in the present invention are shown below, but the present invention is not limited thereto.

  The binder polymer in the present invention preferably has a mass average molar mass (Mw) of 2000 or more, more preferably 5000 or more, and still more preferably 10,000 to 300,000.

  In the present invention, if necessary, hydrophilic polymers such as polyacrylic acid and polyvinyl alcohol described in JP-A-2008-195018 can be used. Further, a lipophilic binder polymer and a hydrophilic binder polymer can be used in combination.

  The content of the binder polymer is usually 5 to 90% by mass, preferably 5 to 80% by mass, and more preferably 10 to 70% by mass with respect to the total solid content of the image recording layer.

(E) Low molecular weight hydrophilic compound The image recording layer in the invention may contain a low molecular weight hydrophilic compound in order to improve the on-press developability without reducing the printing durability.
As the low molecular weight hydrophilic compound, for example, as the water-soluble organic compound, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like glycols and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol and tris (2-hydroxyethyl) isocyanurate, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfones such as alkylsulfonic acid, toluenesulfonic acid and benzenesulfonic acid Acids and salts thereof, organic sulfamic acids such as alkylsulfamic acid and salts thereof, organic sulfuric acids such as alkylsulfuric acid and alkylethersulfuric acid and salts thereof, phenylphosphone Organic phosphonic acids and their salts etc., tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, organic carboxylic acids and salts thereof such as amino acids, betaines, and the like.

  Among these, in the present invention, it is preferable to contain at least one selected from the group consisting of polyols, organic sulfates, organic sulfonates, and betaines.

  Specific examples of organic sulfonates include alkyl sulfonates such as sodium n-butyl sulfonate, sodium n-hexyl sulfonate, sodium 2-ethylhexyl sulfonate, sodium cyclohexyl sulfonate, and sodium n-octyl sulfonate. Sodium 5,8,11-trioxapentadecane-1-sulfonate, sodium 5,8,11-trioxaheptadecane-1-sulfonate, 13-ethyl-5,8,11-trioxaheptadecane-1; Alkyl sulfonates containing ethylene oxide chains such as sodium sulfonate, 5,8,11,14-tetraoxatetradecosane-1-sodium sulfonate; sodium benzenesulfonate, sodium p-toluenesulfonate, p-hydroxy Benzenesulfo Acid sodium, sodium p-styrenesulfonate, sodium dimethyl-5-sulfonate isophthalate, sodium 1-naphthylsulfonate, sodium 4-hydroxynaphthylsulfonate, disodium 1,5-naphthalenedisulfonate, 1,3,6 -Aryl sulfonates such as trisodium naphthalene trisulfonate. The salt may be a potassium salt or a lithium salt.

  Organic sulfates include sulfates of alkyl, alkenyl, alkynyl, aryl or heterocyclic monoethers of polyethylene oxide. The number of ethylene oxide units is preferably 1 to 4, and the salt is preferably a sodium salt, potassium salt or lithium salt.

  As the betaines, compounds having 1 to 5 carbon atoms of the hydrocarbon substituent on the nitrogen atom are preferable. Specific examples include trimethylammonium acetate, dimethylpropylammonium acetate, 3-hydroxy-4-trimethyl. Ammonioobylate, 4- (1-pyridinio) butyrate, 1-hydroxyethyl-1-imidazolioacetate, trimethylammonium methanesulfonate, dimethylpropylammonium methanesulfonate, 3-trimethylammonio-1-propanesulfonate, Examples include 3- (1-pyridinio) -1-propanesulfonate.

  The above low molecular weight hydrophilic compound has a small hydrophobic part structure and almost no surface-active action, so that dampening water penetrates into the exposed part of the image recording layer (image part) and the hydrophobicity and film strength of the image part. Ink acceptability and printing durability of the image recording layer can be maintained satisfactorily.

The amount of these low molecular weight hydrophilic compounds added to the image recording layer is preferably 0.5% by mass or more and 20% by mass or less of the total solid content of the image recording layer. More preferably, it is 1 mass% or more and 10 mass% or less, More preferably, it is 2 mass% or more and 8 mass% or less. In this range, good on-press developability and printing durability can be obtained.
These compounds may be used alone or in combination of two or more.

(F) Grease Sensitizer In the image recording layer of the present invention, a lipid sensitizer such as a phosphonium compound, a nitrogen-containing low molecular weight compound, or an ammonium group-containing polymer is used for the image recording layer in order to improve the inking property. be able to. In particular, when an inorganic layered compound is contained in the protective layer, these compounds function as a surface coating agent for the inorganic layered compound, and prevent a decrease in the inking property during printing by the inorganic layered compound.

  Suitable phosphonium compounds include phosphonium compounds described in JP-A-2006-297907 and JP-A-2007-50660. Specific examples include tetrabutylphosphonium iodide, butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 1,4-bis (triphenylphosphonio) butanedi (hexafluorophosphate), 1,7-bis (tri Phenylphosphonio) heptane sulfate, 1,9-bis (triphenylphosphonio) nonane = naphthalene-2,7-disulfonate, and the like.

  Examples of the nitrogen-containing low molecular weight compound include amine salts and quaternary ammonium salts. Also included are imidazolinium salts, benzoimidazolinium salts, pyridinium salts, and quinolinium salts. Of these, quaternary ammonium salts and pyridinium salts are preferable. Specific examples include tetramethylammonium = hexafluorophosphate, tetrabutylammonium = hexafluorophosphate, dodecyltrimethylammonium = p-toluenesulfonate, benzyltriethylammonium = hexafluorophosphate, benzyldimethyloctylammonium = hexafluorophosphate. Examples thereof include fert and benzyldimethyldodecyl ammonium = hexafluorophosphate.

  The ammonium group-containing polymer may be any polymer as long as it has an ammonium group in its structure, but a polymer containing 5 to 80 mol% of a (meth) acrylate having an ammonium group in the side chain as a copolymerization component is preferable. .

  The ammonium salt-containing polymer has a reduced specific viscosity (unit: cSt / g / ml) determined by the following measurement method, preferably in the range of 5 to 120, more preferably in the range of 10 to 110. The range of 15-100 is especially preferable.

<Measurement method of reduced specific viscosity>
Weigh 3.33 g of 30% polymer solution (1 g as solid content) into a 20 ml volumetric flask and make up with N-methylpyrrolidone. This solution is put in an Ubbelohde reduced viscosity tube (viscosity constant = 0.010 cSt / s), and the time to flow down at 30 ° C. is measured. The calculation formula (“kinematic viscosity” = “viscosity constant” × “ Time of passage (second) ") was calculated by a conventional method.

Specific examples of the ammonium group-containing polymer are shown below.
(1) 2- (trimethylammonio) ethyl methacrylate = p-toluenesulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 10/90)
(2) 2- (Trimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80)
(3) 2- (Ethyldimethylammonio) ethyl methacrylate = p-toluenesulfonate / hexyl methacrylate copolymer (molar ratio 30/70)
(4) 2- (Trimethylammonio) ethyl methacrylate = hexafluorophosphate / 2-ethylhexyl methacrylate copolymer (molar ratio 20/80)
(5) 2- (Trimethylammonio) ethyl methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40/60)
(6) 2- (butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80)
(7) 2- (Butyldimethylammonio) ethyl acrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80)
(8) 2- (butyldimethylammonio) ethyl methacrylate = 13-ethyl-5,8,11-trioxa-1-heptadecanesulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80 )
(9) 2- (butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate / 2-hydroxy-3-methacryloyloxypropyl methacrylate copolymer (molar ratio 15/80/5 )

  The content of the sensitizer is preferably 0.01 to 30.0% by mass, more preferably 0.1 to 15.0% by mass and 1 to 5% by mass with respect to the total solid content of the image recording layer. Is more preferable.

(G) Others As other components, surfactants, colorants, baking-out agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic fine particles, inorganic layered compounds, co-sensitizers or chain transfer agents, etc. Can be added. Specifically, paragraph numbers [0114] to [0159] of Japanese Patent Application Laid-Open No. 2008-284817, paragraph numbers [0023] to [0027] of Japanese Patent Application Laid-Open No. 2006-091479, and US Patent Publication No. 2008/0311520. [0060] The compounds and addition amounts described in [0060] are preferred.

(H) Formation of Image Recording Layer The image recording layer in the present invention is prepared by using the above-mentioned necessary components as known solvents as described in, for example, paragraph numbers [0142] to [0143] of JP-A-2008-195018. A coating solution is prepared by dispersing or dissolving in a coating solution, which is formed by applying the coating solution on a support by a known method such as bar coater coating and drying. The image recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the application, but is generally preferably 0.3 to 3.0 g / m ² . Within this range, good sensitivity and good film characteristics of the image recording layer can be obtained.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer (sometimes referred to as an intermediate layer) is preferably provided between the image recording layer and the support. The undercoat layer enhances the adhesion between the support and the image recording layer in the exposed area, and easily peels off the image recording layer from the support in the unexposed area. Contributes to improvement. In the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, thereby preventing the heat generated by the exposure from diffusing to the support and reducing the sensitivity.

Specific examples of the compound used for the undercoat layer include silane coupling agents having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, and JP-A-2- Examples thereof include phosphorus compounds having an ethylenic double bond reactive group described in Japanese Patent No. 304441. More preferable is a polymer resin having an adsorptive group, a hydrophilic group, and a crosslinkable group that can be adsorbed on the surface of the support, as described in JP-A Nos. 2005-125749 and 2006-188038. It is done. The polymer resin is preferably a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group. More specifically, a phenolic hydroxyl group, a carboxyl _{group, -PO 3 H 2, -OPO 3} H 2, -CONHSO 2 -, - SO 2 NHSO 2 -, - having an adsorptive group such as COCH ₂ COCH ₃ Examples thereof include a polymer resin that is a copolymer of a monomer, a monomer having a hydrophilic sulfo group, and a monomer having a polymerizable crosslinkable group such as a methacryl group or an allyl group. This polymer resin may have a crosslinkable group introduced by salt formation between a polar substituent of the polymer resin, a substituent having a counter charge and a compound having an ethylenically unsaturated bond, Other monomers, preferably hydrophilic monomers, may be further copolymerized.

The content of unsaturated double bonds in the polymer resin for the undercoat layer is preferably 0.1 to 10.0 mmol, and most preferably 2.0 to 5.5 mmol, per 1 g of the polymer resin.
The polymer resin for the undercoat layer preferably has a mass average molar mass of 5000 or more, more preferably 10,000 to 300,000.

  The undercoat layer of the present invention comprises, in addition to the above undercoat compound, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, an amino group, or a functional group having a polymerization inhibiting ability, in order to prevent contamination over time. Compounds having a group that interacts with the surface of an aluminum support (for example, 1,4-diazabicyclo [2,2,2] octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil , Sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, and the like.

The undercoat layer is applied by a known method. The coating amount (solid content) of the undercoat layer is preferably from 0.1-100 mg / m ^2, and more preferably 1 to 30 mg / m ^2.

(Support)
As the support used in the lithographic printing plate precursor according to the invention, a known support is used. Of these, an aluminum plate that has been roughened and anodized by a known method is preferred.

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  As the support used in the present invention, it is necessary to further improve the adhesion to the upper layer, hydrophilicity, dirt resistance, heat insulation, etc., on the substrate having the surface treatment as described above and having an anodized film. Accordingly, it is possible to appropriately select and perform micropore enlargement processing, sealing processing, and the like of the anodized film described in JP-A-2001-253181 and JP-A-2001-322365.

  The support used in the present invention is preferably subjected to silicate treatment at the end after being subjected to various surface treatments as described above. This treatment method is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. Such an alkali metal silicate aqueous solution treatment is preferably used, and the aluminum support is immersed or electrolytically treated with an aqueous solution of sodium silicate or the like, and then washed with water and dried.

Specific examples of the alkali metal silicate used for the hydrophilic surface treatment include sodium silicate, potassium silicate, and lithium silicate. Of these, sodium silicate and potassium silicate are preferable. Examples of sodium silicate include No. 3 sodium silicate, No. 2 sodium silicate, No. 1 sodium silicate, sodium orthosilicate, sodium sesquisilicate, and sodium metasilicate. Examples of potassium silicate include No. 1 potassium silicate.
The aqueous solution of alkali metal silicate preferably has a pH of 10 to 13 at 25 ° C. In order to increase the pH, an appropriate amount of a hydroxide such as sodium hydroxide, potassium hydroxide, or lithium hydroxide may be contained. Of these, sodium hydroxide and potassium hydroxide are preferable. The aqueous solution of alkali metal silicate may contain an alkaline earth metal salt or a Group 4 (Group IVB) metal salt. Examples of the alkaline earth metal salt include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate and barium nitrate; sulfates; hydrochlorides; phosphates; acetates; oxalates; Is mentioned. Examples of Group 4 (Group IVB) metal salts include titanium tetrachloride, titanium trichloride, potassium titanium fluoride, titanium oxalate potassium, titanium sulfate, titanium tetraiodide, zirconium chloride oxide, zirconium dioxide, zirconium oxychloride. And zirconium tetrachloride. These alkaline earth metal salts and Group 4 (Group IVB) metal salts are used alone or in combination of two or more.

In the surface treatment of the aluminum support of the present invention, this alkali metal silicate aqueous solution treatment (silicate treatment) is essential, and the amount of Si deposited on the silicate-treated aluminum support surface used in the present invention is 5 to 5. It is preferably 15 mg / m ² .
The support of the present invention preferably has a center line average roughness of 0.10 to 1.2 μm.

  If necessary, the support of the present invention includes an organic polymer compound described in JP-A-5-45885 and a silicon alkoxy compound described in JP-A-5-45885 on the back surface. A backcoat layer can be provided.

(Protective layer)
In the lithographic printing plate precursor according to the invention, a protective layer (overcoat layer) is preferably provided on the image recording layer. In addition to the function of suppressing the image formation inhibition reaction by blocking oxygen, the protective layer has a function of preventing scratches in the image recording layer and preventing ablation during high-illuminance laser exposure.

  The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729. As the low oxygen permeability polymer used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used. Specific examples include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble cellulose derivatives, poly (meth) acrylonitrile, and the like.

Further, in order to enhance the oxygen barrier property, the protective layer preferably contains an inorganic layered compound such as natural mica and synthetic mica as described in JP-A-2005-119273.
Further, the protective layer may contain known additives such as a plasticizer for imparting flexibility, a surfactant for improving coating properties, and inorganic fine particles for controlling surface slipperiness. Further, the protective layer can contain the sensitizer described in the description of the image recording layer.

The protective layer is applied by a known method. The coating amount of the protective layer, the coating amount after drying is preferably in the range of 0.01 to 10 g / ^{m 2,} more preferably in the range of 0.02 to 3 g / ^{m 2,} and most preferably 0. in the range of 02~1g / ^{m 2.}

[Plate making method]
The plate making of the lithographic printing plate precursor according to the invention is preferably carried out by an on-press development method. The on-press development method comprises the steps of image exposure of the lithographic printing plate precursor, and supply of the oil-based ink and the fountain solution for printing of the present invention without any development treatment to the exposed lithographic printing plate precursor. And a printing process for printing, and unexposed portions of the lithographic printing plate precursor are removed in the course of the printing process. Imagewise exposure may be performed on the printing machine after the lithographic printing plate precursor is mounted on the printing machine, or may be separately performed with a plate setter or the like. In the latter case, the exposed lithographic printing plate precursor is mounted on a printing machine without undergoing a development process. Thereafter, the printing machine is used to supply the oil-based ink and the fountain solution for printing of the present invention and print it as it is, so that the on-press development process is performed at the initial stage of printing, that is, the image recording in the unexposed area. The layer is removed, and accordingly, the hydrophilic support surface is exposed to form a non-image area. As the oil-based ink, a normal lithographic printing ink is used.
This will be described in more detail below.

In the present invention, the light source used for image exposure is preferably a laser. Although the laser used for this invention is not specifically limited, The solid laser and semiconductor laser etc. which irradiate infrared rays with a wavelength of 760-1200 nm are mentioned suitably.
Regarding the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is preferably 10 to 300 mJ / cm ² . In the laser, it is preferable to use a multi-beam laser device in order to shorten the exposure time.

  The exposed lithographic printing plate precursor is mounted on a plate cylinder of a printing press. In the case of a printing press equipped with a laser exposure device, image exposure is performed after a lithographic printing plate precursor is mounted on a plate cylinder of the printing press.

  When the image-exposed lithographic printing plate precursor is supplied with the fountain solution and the printing ink presented in the present invention and printed, the image recording layer cured by exposure has an oleophilic surface in the exposed portion of the image recording layer. Forming a printing ink receiving portion having On the other hand, in the unexposed area, the uncured image recording layer is removed by dissolution or dispersion by the supplied dampening water and / or printing ink, and a hydrophilic surface is exposed in that area. As a result, the fountain solution adheres to the exposed hydrophilic surface, and the printing ink is deposited on the image recording layer in the exposed area and printing is started.

Here, dampening water or printing ink may be supplied to the printing plate first, but printing is first performed in order to prevent the dampening water from being contaminated by the removed image recording layer components. It is preferable to supply ink.
In this way, the lithographic printing plate precursor according to the invention is developed on the machine on an offset printing machine and used as it is for printing a large number of sheets.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

[Examples 1 to 20 and Comparative Examples 1 to 13]

1. Preparation of lithographic printing plate precursor (1) (1) Preparation of support In order to remove rolling oil from the surface of an aluminum plate (material JIS A 1050) having a thickness of 0.3 mm, a 10 mass% sodium aluminate aqueous solution was used. After degreasing treatment at 30 ° C. for 30 seconds, the aluminum surface was sanded using ^three bundled nylon brushes with a bristle diameter of 0.3 mm and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) with a median diameter of 25 μm. Conspicuous and washed well with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. At this time, the etching amount of the grained surface was about 3 g / m ² .

Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power supply waveform is electrochemical roughening treatment using a trapezoidal rectangular wave AC with a time TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave AC. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Subsequently, nitric acid electrolysis was performed with an aqueous solution of 0.5% by mass of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was the anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying.
Next, the plate was provided with a direct current anodic oxide film having a current density of 15 A / dm ² and a current density of 15 g / m ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolytic solution, followed by washing with water. It dried and produced the support body (1).
Thereafter, in order to ensure the hydrophilicity of the non-image area, the support (1) was subjected to a silicate treatment at 60 ° C. for 10 seconds using an aqueous 2.5 mass% No. 3 sodium silicate solution, and then washed with water for support. Body (2) was obtained. The adhesion amount of Si was 10 mg / m ² . The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

(2) Formation of undercoat layer Next, the following undercoat layer coating solution (1) is applied onto the support (2) so that the dry coating amount is 20 mg / m ² , and used in the following experiments. A support having a layer was prepared.

<Coating liquid for undercoat layer (1)>
-Undercoat layer compound (1) having the following structure: 0.18 g
・ Hydroxyethyliminodiacetic acid 0.10g
・ Methanol 55.24g
・ Water 6.15g

(3) Formation of image recording layer The following image recording layer coating solution (1) was bar-coated on the above support having an undercoat layer, followed by oven drying at 70 ° C. for 60 seconds, and a dry coating amount of 0.6 g. / M ² image recording layer was prepared to obtain a lithographic printing plate precursor (1) [for Examples 1 to 18 and Comparative Examples 1 to 5].

<Image recording layer coating solution (1)>
-Polymer fine particle aqueous dispersion (1) 20.0 g
・ Infrared absorbing dye (1) [The following structure] 0.2g
・ Radical generator 0.5g
Irgacure 250 (manufactured by Ciba Specialty Chemicals)
Polymerizable compound SR-399 (Sartomer) 1.50 g
・ Mercapto-3-triazole 0.2g
・ Byk336 (byk chimie) 0.4g
・ Klucel M (Hercules) 4.8g
・ ELVACITE 4026 (manufactured by Ineos Acrylica) 2.5g
・ N-propanol 55.0g
・ 2-butanone 17.0g

In addition, the compounds described by trade names in the above composition are as follows.
Irgacure 250: (4-methoxyphenyl) [4- (2-methylpropyl) phenyl] iodonium = hexafluorophosphate (75% by mass propylene carbonate solution)
SR-399: dipentaerythritol pentaacrylate
Byk336: modified dimethylpolysiloxane copolymer (25% by mass xylene / methoxypropyl acetate solution)
・ Klucel M: Hydroxypropyl cellulose (2% by mass aqueous solution)
ELVACITE 4026: Hyperbranched polymethyl methacrylate (10% by mass 2-butanone solution)

(Production of polymer fine particle aqueous dispersion (1))
A 1000 ml four-necked flask was equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser, and nitrogen gas was introduced to perform deoxygenation, while polyethylene glycol methyl ether methacrylate (average of PEGMA ethylene glycol) The repeating unit was 50) 10 g, distilled water 200 g and n-propanol 200 g were added and heated until the internal temperature reached 70 ° C. Next, a premixed mixture of 10 g of styrene (St), 80 g of acrylonitrile (AN) and 0.8 g of 2,2′-azobisisobutyronitrile was added dropwise over 1 hour. After completion of the dropwise addition, the reaction was continued for 5 hours, and then 0.4 g of 2,2′-azobisisobutyronitrile was added to raise the internal temperature to 80 ° C. Subsequently, 0.5 g of 2,2′-azobisisobutyronitrile was added over 6 hours. Polymerization progressed 98% or more at the stage of reaction for a total of 20 hours, and a polymer fine particle aqueous dispersion (1) having a mass ratio of PEGMA / St / AN = 10/10/80 was obtained. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 150 nm.

  Here, the particle size distribution is obtained by taking an electron micrograph of polymer fine particles, measuring a total of 5000 fine particle sizes on the photograph, and a logarithmic scale between 0 and the maximum value of the obtained particle size measurement values. And the frequency of appearance of each particle size was plotted and obtained. For non-spherical particles, the particle size of spherical particles having the same particle area as that on the photograph was used as the particle size.

2. Preparation of lithographic printing plate precursor (2) On the undercoat layer formed as in the lithographic printing plate precursor (1), an image recording layer coating solution (2) having the following composition was bar-coated, and then at 100 ° C. for 60 seconds. Oven drying was performed to form an image recording layer having a dry coating amount of 1.0 g / m ² .
The image recording layer coating solution (2) was obtained by mixing and stirring the following photosensitive solution (2) and microgel solution (1) immediately before coating.

<Photosensitive solution (2)>
-Binder polymer (1) [the following structure] 0.240 g
Infrared absorbing dye (2) [following structure] 0.030 g
-Radical generator (1) [the following structure] 0.162 g
Polymerizable compound tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.192 g
・ Low molecular weight hydrophilic compound Tris (2-hydroxyethyl) isocyanurate 0.062g
・ Low molecular weight hydrophilic compound (1) [the following structure] 0.050 g
-Sensitizing agent Phosphonium compound (1) [the following structure] 0.055 g
・ Sensitizer Benzyl-dimethyl-octylammonium ・ PF ₆ salt 0.018g
-Sensitizing agent Ammonium group-containing polymer [the following structure, reduced specific viscosity 44 cSt / g / ml] 0.035 g
・ Fluorosurfactant (1) [The following structure] 0.008g
・ 2-butanone 1.091g
・ 1-methoxy-2-propanol 8.609g

<Microgel solution (1)>
・ Microgel (1) 2.640 g
・ Distilled water 2.425g

  The binder polymer (1), infrared absorbing dye (2), radical generator (1), phosphonium compound (1), low molecular weight hydrophilic compound, (1) ammonium group-containing polymer, and fluorine-based surfactant ( The structure of 1) is as shown below.

-Synthesis of microgel (1)-
As the oil phase component, 4.46 g of a polyfunctional isocyanate having the following structure (Mitsui Chemical Polyurethane; 75% ethyl acetate solution), trimethylolpropane and xylene diisocyanate, methyl-terminated polyoxyethylene adduct (Mitsui Chemical Polyurethane) 50% ethyl acetate solution) 0.86 g, pentaerythritol tetraacrylate (manufactured by Sartomer, SR399E) 1.72 g, and Pionein A-41C (manufactured by Takemoto Yushi; methanol 70% solution) 0.05 g in ethyl acetate 4.46 g Dissolved. 17.30 g of water as an oil phase component and an aqueous phase component were mixed and emulsified for 15 minutes at 10,000 rpm using a homogenizer. The obtained emulsion was stirred at 40 ° C. for 4 hours. The solid content concentration of the microgel solution thus obtained was diluted with water so as to be 21.8% by mass. The average particle size was 0.25 μm.

A protective layer coating solution (1) having the following composition was further bar coated on the image recording layer, followed by oven drying at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.15 g / m ^2. A lithographic printing plate precursor (2) [for Example 19 and Comparative Examples 6 to 9] was obtained.

<Coating liquid for protective layer (1)>
・ Inorganic layered compound dispersion (1) 1.5 g
-Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd. CKS50, sulfonic acid modification,
Saponification degree 99 mol% or more, polymerization degree 300) 6% by mass aqueous solution 0.55 g
・ Polyvinyl alcohol (PVA-405 manufactured by Kuraray Co., Ltd.)
Degree of saponification 81.5 mol%, degree of polymerization 500) 6% by weight aqueous solution 0.03 g
・ Nippon Emulsion Co., Ltd. surfactant (Emalex 710) 1% by weight aqueous solution 0.86g
・ Ion-exchanged water 6.0g

(Preparation of inorganic layered compound dispersion (1))
6.4 g of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co., Ltd.) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed particles was 100 or more.

3. Preparation of lithographic printing plate precursor (3) The lithographic printing plate precursor (2) is the same as the lithographic printing plate precursor (2) except that the image recording layer in the lithographic printing plate precursor (2) is changed to the following image recording layer coating solution (3). A printing plate precursor (3) was prepared.

<Image recording layer coating solution (3)>
The image recording layer coating solution (3) was prepared in the same manner as the image recording layer coating solution (2) except that the microgel solution (1) used in the image recording layer coating solution (2) was changed to the following microgel solution (2). Produced.

<Microgel solution (2)>
-Microgel (2) 2.640 g
・ Distilled water 2.425g

-Synthesis of microgel (2)-
As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (Mitsui Chemical Polyurethane Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g, And 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12,000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 50 ° C. for 3 hours. The microgel solution thus obtained was diluted with distilled water to a solid content concentration of 15% by mass, and this was used as the microgel (2). When the average particle size of the microgel was measured by a light scattering method, the average particle size was 0.2 μm.

  An image recording layer was formed as described above to obtain a lithographic printing plate precursor (3) [for Example 20 and Comparative Examples 10 to 13].

4). Preparation of dampening water Each component described in the following component table was mixed and dissolved to prepare dampening water at a liquid temperature of 20 ° C.

<Composition of fountain solution>
・ Pure water 35.6g
・ 28.4 g of propylene glycol mono n-butyl ether
・ Propylene glycol 25.0g
・ Octanediol 4.7g
・ Glycerin 1.0g
* KOH (48 mass% aqueous solution) 2.3g
・ Ammonium nitrate 0.3g
・ Diammonium phosphate 0.3g
・ Magnesium sulfate 0.8g
・ Citric acid 0.2g
・ 0.7g diammonium citrate
・ Specific copolymer 0.8g

  The structures of the specific copolymers (P-1 to P-18) used for the fountain solution and the polymers (P-19 to P-22) used for comparison are shown below.

5. Evaluation The lithographic printing plate precursor produced as described above was subjected to a Trendsetter 3244VX manufactured by Creo with an infrared semiconductor laser, with an output of 7.0 W, an outer drum rotation speed of 150 rpm, and a resolution of 2400 dpi. And an image containing 97% dot chart was exposed. The exposed plate was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without being developed as it was. Using a 3% by volume aqueous solution of the printing chemical prepared as described above as the fountain solution, TRANS-G (N) Beni Ink (Dainippon Ink Chemical Co., Ltd.) / Varnish = 90/10 was used as the ink, After supplying the fountain solution and the ink, 500 sheets were printed at a printing speed of 6000 sheets per hour. The number of print sheets required until the on-press development on the printing press of the unexposed portion of the image recording layer was completed and the ink was not transferred to the non-image portion was measured as on-press developability. The non-image area was printed with no stain.
Then, after the supply of dampening water was squeezed and the plate surface was completely soiled with ink, the supply amount of dampening water was restored to the original value. Then, after stopping the printing machine for one hour, the number of sheets until the dampening water and ink were supplied again to obtain a good print was measured as “stain performance”. The small number of sheets indicates that the lithographic printing method can maintain the hydrophilicity and water retention of the non-image area in an excellent state.

  Table 1 shows the evaluation results of Examples 1 to 18 and Comparative Examples 1 to 5 using the planographic printing plate precursor (1).

  Example 11 and Comparative Examples 6 to 9 were evaluated in the same manner as in Examples 1 to 18 and Comparative Examples 1 to 5 except that the planographic printing plate precursor (2) was used. The evaluation results are shown in Table 2.

  Example 20 and Comparative Examples 10 to 13 were evaluated in the same manner as in Examples 1 to 18 and Comparative Examples 1 to 5 except that the planographic printing plate precursor (3) was used. The evaluation results are shown in Table 3.

  From Tables 1 to 3, it can be seen that the on-press developability and stain resistance are improved by the fountain solution of the present invention and the printing method of the lithographic printing plate of the present invention.

[Example 21 and Comparative Example 14]
6). Preparation of a lithographic printing plate precursor (4) A lithographic printing plate precursor (1) except that the image recording layer coating solution (1) in the lithographic printing plate precursor (1) is replaced by the following image recording layer coating solution (4) A lithographic printing plate precursor (4) was prepared in the same manner as described above.

<Image recording layer coating solution (4)>
The image recording layer coating liquid (1) except that 72 g of the following polymer fine particle aqueous dispersion (2) was added instead of 20.0 g of the polymer fine particle aqueous dispersion (1) used in the image recording layer coating liquid (1). An image recording layer coating solution (4) was prepared in the same manner as described above.

Preparation of Polymer Fine Particle Aqueous Dispersion (2) To a 200 ml three-necked flask equipped with a mechanical stirrer, 85 g of water, 0.3 g of sodium dodecyl sulfate (SDS), 4.5 g of acrylonitrile and 0.5 g of styrene were added and completely dissolved. Next, after the inside of the system was purged with nitrogen, nitrogen flow (flow rate: 10 ml / min) was performed. Next, after heating up to 70 degreeC, potassium persulfate aqueous solution (0.27g of potassium persulfate, 10g of water) was dripped over 2 hours, stirring at the rotational speed of 300 rpm. After completion of dropping, the mixture was stirred at 70 ° C. for 3 hours, then heated to 80 ° C. and stirred for 2 hours. An aqueous polymer fine particle dispersion (2) having a mass ratio of St / AN = 10/90 was obtained. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 125 nm. The solid content was 5.5% by mass.

  Example 21 and Comparative Example 14 were evaluated in the same manner as in Examples 1 to 18 and Comparative Examples 1 to 5 except that the planographic printing plate precursor (4) was used. The results are shown in Table 4. Table 4 also shows the results of Example 1 and Comparative Example 2.

  From Table 4, it can be seen that the on-press developability and stain resistance are improved by including an ethylene oxide chain in the polymer side chain contained in the image recording layer.

Claims (13)

Printing dampening water, characterized in that it contains a vinyl copolymer represented by the general formula (1).

In general formula (1) , R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group. L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Y ₁ represents a chain selected from ethylene oxide, propylene oxide, polyethylene oxide, and polypropylene oxide, and the terminal X ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Q represents a group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, and a salt thereof. The fountain solution for printing according to claim 1, wherein Q is a phosphate group or a salt group thereof. Printing dampening water according to claim 1 or 2, wherein said Y ₁ is a polyethylene oxide chain. The fountain solution for printing according to claim 3 , wherein the polyethylene oxide chain has 2 to 30 ethylene oxide repeating units. The lithographic printing plate precursor is subjected to image exposure and then attached to a printing machine without undergoing a development processing step. (A1) A repeating unit having a group represented by the general formula (A), and (a2) a phosphoric acid group and a phosphonic acid Removing an unexposed portion with a fountain solution for printing and an oil-based ink containing a vinyl copolymer containing a repeating unit having at least one group selected from a group, a sulfonic acid group and a salt thereof , and printing. A printing method of a lithographic printing plate characterized by the above.

Here, Y represents an alkyleneoxy group or a polyalkylene oxide chain, and the terminal X represents an alkyl group having 3 or less carbon atoms or a hydrogen atom. The lithographic printing plate printing method according to claim 5, wherein the vinyl copolymer is represented by the general formula (1).

  In general formula (1), R ₁ , R ₂ Each independently represents a hydrogen atom or a methyl group. L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Y ₁ Represents a chain selected from ethylene oxide, propylene oxide, polyethylene oxide, and polypropylene oxide; ₁ Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Q represents a group selected from a phosphoric acid group, a phosphonic acid group, a sulfonic acid group, and a salt thereof. The lithographic printing plate printing method according to claim 6, wherein Q is a phosphate group or a salt group thereof. Y ₁ The printing method of a lithographic printing plate according to claim 6 or 7, wherein is a polyethylene oxide chain. The number of ethylene oxide repeating units in the polyethylene oxide chain is 2 to 30
The lithographic printing plate printing method according to claim 8, wherein: The lithographic printing plate precursor has an image recording layer containing an infrared absorbing dye, a radical polymerization initiator, a polymerizable compound, and a polymer having a polyalkylene oxide group in the side chain on an aluminum support having an anodized film. The printing method of the lithographic printing plate of any one of Claims 5-9 characterized by these. The lithographic printing plate printing method according to claim 10, wherein the polymer is in the form of fine particles. The printing method of a lithographic printing plate, wherein the polyalkylene oxide group according to claim 10 or 11 is a polyethylene oxide group. The printing method of a lithographic printing plate according to any one of claims 10 to 12 , wherein the aluminum support of the lithographic printing plate precursor has an anodized film to which a silicate is adhered.