JP2005221615A - Processing method for lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing method by which decomposed matter and sediment can be diminished which are accumulated in the bath of an automatic developing machine in a processing step of processing the original plate of negative lithographic printing plate obtained by forming on an aluminum support a photosensitive layer containing an infrared absorbent, a polymerization initiator, an ethylenically unsaturated bond-containing monomer and a binder polymer, whereby long-term stable processing is made possible. <P>SOLUTION: The original plate of negative lithographic printing plate is imagewise exposed, and before and after development, the lithographic printing plate is processed with a washing liquid to which a preservative and a chelating agent have been added. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a processing method for a lithographic printing plate, and more particularly to a processing method for a so-called direct lithographic printing plate capable of direct plate making by scanning with an infrared laser based on a digital signal from a computer or the like.

  In recent years, the development of lasers has been remarkable, and high-power and small-sized lasers having a light emitting region from near infrared to infrared have become readily available. These lasers are very useful as a recording light source when a printing plate is directly made by digital data from a computer or the like (Computer to Plate: hereinafter abbreviated as CTP as appropriate). For example, a solid-state laser and a semiconductor laser that emit infrared rays having a wavelength of 760 nm to 1200 nm are useful because their outputs are higher than those of other wavelength regions.

  Such an image forming material is generally processed by an automatic processor. A processing process consists of a development process, a water washing process, a gum process, etc. Long-term use of the liquids used in these processes is required from the viewpoint of environment and cost, but the water-washing liquid used in the water-washing process tends to rot and precipitate, which is problematic for long-term treatment. It was. Various washing solutions have been proposed as countermeasures against these (see, for example, Patent Documents 1 to 4). However, especially for decay and precipitation when processing a lithographic printing plate using a so-called thermal photosensitive composition containing an infrared absorber, a polymerization initiator, an ethylenically unsaturated bond-containing monomer, and a binder polymer. Is still not fully effective.

Japanese Patent Laid-Open No. 10-10754 Japanese Patent Publication No. 4-14342 JP 2001-51404 A JP 2003-50474 A

  An object of the present invention is to treat a negative lithographic printing plate precursor in which a photosensitive layer containing an infrared absorber, a polymerization initiator, an ethylenically unsaturated bond-containing monomer, and a binder polymer is formed on an aluminum support. It is an object of the present invention to provide a treatment method capable of significantly reducing spoilage and precipitate accumulated in the washing solution used in the process and capable of stably treating for a long time.

The present inventor treated the lithographic printing plate with a washing solution before and after development after image exposure of the negative lithographic printing plate precursor, and added a preservative and a chelating agent to the washing solution for a long period of time. We found that it can be used stably and succeeded in achieving the above-mentioned problems.
That is, the present invention image-exposed a negative lithographic printing plate precursor in which a photosensitive layer containing an infrared absorber, an ethylenically unsaturated bond-containing monomer, a polymerization initiator, and a binder polymer is formed on an aluminum support. A processing method of a lithographic printing plate to be developed later, characterized in that the lithographic printing plate image-exposed with a washing solution before and after the development is treated, and the washing solution contains a preservative and a chelating agent. And a processing method for a lithographic printing plate.

  By using the processing method of the present invention, it is possible to greatly extend the number of days until the replacement of the washing solution used before and after development, and without causing precipitation of the washing solution bath, so-called infrared heat-sensitive negative lithographic printing The plate precursor can be processed stably.

The processing method of the lithographic printing plate of the present invention is a negative lithographic printing plate in which a photosensitive layer containing an infrared absorber, an ethylenically unsaturated bond-containing monomer, a polymerization initiator, and a binder polymer is formed on an aluminum support. A processing method of a lithographic printing plate for developing after image exposure of an original plate, wherein the lithographic printing plate subjected to image exposure with a washing solution before or after the development is processed, and the washing solution contains a preservative and a chelating agent It is a method characterized by containing.
The present invention is described in detail below.

<Washing liquid>
In the present invention, the washing solution refers to a washing solution used in a washing step before and after development. The washing solution used before and after development may have the same composition or a different composition. The washing solution used in the present invention contains water as a main solvent, and additionally contains at least one preservative and at least one chelating agent.

[Chelating agent]
In the present invention, the chelating agent contained in the washing solution is a compound that forms a chelate compound by coordinate bonding with metal ions. Specifically, for example, Na ₂ P ₂ O ₇ , Na ₅ P ₃ O ₃ , Na ₃ P ₃ O ₉ , Na ₂ O ₄ P (NaO ₃ P) PO ₃ Na ₂ , Calgon (sodium polymetaphosphate), etc. Polyethylene salt of, for example, ethylenediaminetetraacetic acid, potassium salt, sodium salt thereof; diethylenetriaminepentaacetic acid, potassium salt, sodium salt thereof; triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof; hydroxyethylethylenediaminetriacetic acid, Potassium salt, sodium salt thereof; nitrilotriacetic acid, potassium salt thereof, sodium salt thereof; 1,2-diaminocyclohexanetetraacetic acid, potassium salt thereof, sodium salt thereof; 1,3-diamino-2-propanoltetraacetic acid, potassium salt thereof Aminopolycarboxylic acid, such as its sodium salt 2-phosphonobutanetricarboxylic acid-1,2,4, its potassium salt, its sodium salt; 2-phosphonobutanone tricarboxylic acid-2,3,4, its potassium salt, its sodium salt; 1-phospho Noethanetricarboxylic acid-1,2,2, potassium salt thereof, sodium salt thereof; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt thereof, sodium salt thereof; aminotri (methylenephosphonic acid), potassium salt thereof; There may be mentioned organic phosphonic acids such as sodium salts thereof.

（式（Ｉ）中、Ｒ₁、Ｒ₂及びＲ₃はそれぞれ水素原子又は式



Among the above chelating agents, particularly preferred chelating agents from the effects of the present invention are compounds having two or more phosphonic acid groups in the molecule. A compound having two or more phosphonic acid groups in the molecule is considered to have particularly high chelating properties for Ca, Mg and the like. Specific examples of the “compound having two or more phosphonic acid groups” include organic phosphonic acids represented by the following formulas (I), (II) and (III) and salts thereof.

(In the formula (I), R ₁ , R ₂ and R ₃ are each a hydrogen atom or a formula

（式中Ｍ¹及びＭ²はそれぞれ水素原子、Ｎａ、ＮＨ₄又はＫを表す。）の基を表し、但しＲ₁、Ｒ₂及びＲ₃のうち少なくとも２つは該基を表す。）

(Wherein M ¹ and M ² each represent a hydrogen atom, Na, NH ₄ or K), provided that at least two of R ₁ , R ₂ and R ₃ represent the group. )

（式(II)中、Ｍ¹及びＭ²はそれぞれ水素原子、Ｎａ、ＮＨ₄又はＫを表す。）

(In formula (II), M ¹ and M ² each represent a hydrogen atom, Na, NH ₄ or K.)

（式（III）中、Ｒ₄、Ｒ₅、Ｒ₆、Ｒ₇及びＲ₈はそれぞれ水素原子又は式

(In the formula (III), R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each a hydrogen atom or a formula

（式中、ｑは１〜４の整数を表し、Ｍ¹及びＭ²はそれぞれ水素原子、Ｎａ、ＮＨ₄又はＫを表す。）の基を表し、但しＲ₄、Ｒ₅、Ｒ₆、Ｒ₇及びＲ₈のうち少なくとも２つは該基を表し、ｍは１〜４の整数を表し、ｍ'は１〜４の整数を表し、ｎは０又は１〜４の整数を表す。）

(Wherein q represents an integer of 1 to 4, and M ¹ and M ² each represent a hydrogen atom, Na, NH ₄ or K), provided that R ₄ , R ₅ , R ₆ , R _At least two of ₇ and R ₈ represent the group, m represents an integer of 1 to 4, m ′ represents an integer of 1 to 4, and n represents 0 or an integer of 1 to 4. )

  Specific examples of the compound represented by the formula (I) include aminotri (methylenephosphonic acid) and salts thereof, and commercially available products such as DQ2000 (aminotri (methylenephosphonic acid)) and DQ2006 (aminotri (methylenephosphonic acid)) manufactured by Nippon Monsanto Co., Ltd. Phosphonic acid) and 5Na salt).

  The compound represented by the above formula (II) is 1-hydroxyethane-1,1-diphosphonic acid and its salts. As a commercial product, for example, DQ2010 (1-hydroxyethane-1,1-diphosphonic acid manufactured by Nippon Monsanto Co., Ltd.) ), DQ2016 (1-hydroxyethane-1,1-diphosphonic acid) · 4Na salt).

Examples of the compound represented by the formula (III) include ethylenediaminetetra (methylenephosphonic acid), hexamethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), and salts thereof. For example, DQ2041 (ethylenediaminetetra (methylenephosphonic acid)), DQ2042 (ethylenediaminetetra (methylenephosphonic acid) · 5NH ₄ salt), DQ2044 (ethylenediaminetetra (methylenephosphonic acid) · 5K salt) manufactured by Nippon Monsanto Co., Ltd. ), DQ2051 (hexamethylenediaminetetra (methylenephosphonic acid)), DQ2052 (hexamethylenediaminetetra (methylenephosphonic acid) · 6NH ₄ salt), DQ2054 (hexamethylenediaminetetra (methylenephosphonic acid) · 6K salt), DQ2060 ( Diethylenetriaminepenta (methylenephosphonic acid)) and DQ2066 (diethylenetriaminepenta (methylenephosphonic acid) .5Na salt).

When the chelating agent is used in the washing solution, its concentration is suitably 10 ⁻⁵ to 10% by mass, preferably 10 ⁻⁴ to 10 ⁻¹ % by mass, based on the total mass of the washing solution. More preferably, it is 10 ⁻³ to 10 ⁻² mass%.

[Preservative]
In addition, as the preservative contained in the washing solution, known products used in the fields of fiber, wood processing, food, medicine, cosmetics, agricultural chemicals, and the like can be used. For example, quaternary ammonium salts, monohydric phenol derivatives, dihydric phenol derivatives, polyhydric phenol derivatives, imidazole derivatives, pyrazolopyrimidine derivatives, monohydric naphthols, carbonates, sulfone derivatives, organotin compounds, cyclopentane derivatives, phenyl Derivatives, phenol ether derivatives, phenol ester derivatives, hydroxylamine derivatives, nitrile derivatives, naphthalenes, pyrrole derivatives, quinoline derivatives, benzothiazole derivatives, secondary amines, 1,3,5-triazine derivatives, thiadiazole derivatives, anilide derivatives, Pyrrole derivatives, halogen derivatives, dihydric alcohol derivatives, dithiols, cyanic acid derivatives, thiocarbamic acid derivatives, diamine derivatives, isothiazole derivatives, monohydric alcohols, saturated aldehydes Unsaturated monocarboxylic acids, saturated ethers, unsaturated ethers,

Lactone, amino acid derivative, hydantoin, cyanuric acid derivative, guanidine derivative, pyridine derivative, saturated monocarboxylic acid, benzenecarboxylic acid derivative, hydroxycarboxylic acid derivative, biphenyl, hydroxamic acid derivative, aromatic alcohol, halogenophenol derivative, benzenecarboxylic acid Derivatives, mercaptocarboxylic acid derivatives, quaternary ammonium salt derivatives, triphenylmethane derivatives, hinokitiol, furan derivatives, benzofuran derivatives, acridine derivatives, isoquinoline derivatives, arsine derivatives, thiocarbamic acid derivatives, phosphate esters, halogenobenzene derivatives, quinones Derivatives, benzenesulfonic acid derivatives, monoamine derivatives, organophosphates, piperazine derivatives, phenazine derivatives, pyrimidine derivatives, thiophane DOO derivatives, imidazoline derivatives, isoxazole derivatives, known preservatives in such as ammonium salt derivatives can be used.

  Particularly preferred preservatives include pyridinethiol-1-oxide salts, salicylic acid and its salts, 1,3,5-trishydroxyethylhexahydro-S-triazine, 1,3,5-trishydroxymethylhexahydro-S- Examples include triazine, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, and 2-bromo-2-nitro-1,3-propanediol. This is because these are particularly effective in both fungicidal and fungicidal properties. A preferable addition amount is an amount that exerts a stable effect on bacteria, mold, yeast, etc., and varies depending on the kind of bacteria, mold, yeast, but 0.001 to 10% by mass with respect to the washing solution. It is preferable that two or more kinds of preservatives are used in combination so as to be effective against various molds and bacteria.

[Additive]
The washing solution may contain a surfactant in addition to the above compound as an additive, and may further contain a pH adjuster, a lipophilic substance, an antifoaming agent, and the like.
Examples of the surfactant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.
Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, α-olefin sulfonates, dialkyl sulfosuccinates, alkyl diphenyl ether disulfonates, linear alkyl benzene sulfonates, branched Chain alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, sodium N-methyl-N-oleyl taurate, disodium N-alkylsulfosuccinate monoamide Salts, aminocarboxylates,

Petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, sulfate esters of fatty acid alkyl esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfate esters, fatty acid monoglyceride sulfate esters, polyoxyethylene alkyl phenyl ether sulfates Ester salts, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, partially saponified styrene-maleic anhydride copolymers , Partially saponified products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensate, and the like. Among these, dialkyl sulfosuccinates, alkyl sulfate esters, alkyl naphthalene sulfonates, α-olefin sulfonates, and alkyl diphenyl ether disulfonates are particularly preferably used.
As the cationic surfactant, alkylamine salts, quaternary ammonium salts and the like are used.

As the amphoteric surfactant, alkyl carboxybetaines, alkyl imidazolines, alkylaminocarboxylic acids and the like are used.
Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial esters, sorbitan fatty acid partial esters , Pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters ,

Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamine, triethanolamine fatty acid ester, trialkylamine oxide , Polypropylene glycol molecular weight 200 to 5000, trimethylolpropane, glycerin or sorbitol polyoxyethylene or polyoxypropylene adduct, acetylene glycol type, and the like. Fluorine-based and silicon-based nonionic surfactants can also be used in the same manner.

  Two or more surfactants can be used in combination. The amount used is not particularly limited, but a preferable range is 0.01 to 20% by mass, preferably 0.05 to 10% by mass, based on the total mass of the rinsing liquid.

<Developer>
In the method of the present invention, the lithographic printing plate precursor is subjected to development processing after being exposed (or after being subjected to exposure and heating steps). As the developer used in such development processing, an alkaline aqueous solution having a pH of 14 or less is particularly preferred, and an alkaline aqueous solution having a pH of 8 to 12 containing an anionic surfactant is more preferably used. For example, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, ammonium, sodium borate, Examples include inorganic alkaline agents such as potassium, ammonium, sodium hydroxide, ammonium, potassium and lithium. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are also used. These alkali agents are used alone or in combination of two or more.

In the present invention, in the development processing of a lithographic printing plate precursor, 1 to 20% by mass of a surfactant is added to the developer, but more preferably 2 to 10% by mass. If the amount is too small, the developability deteriorates. If the amount is too large, the strength such as the abrasion resistance of the image deteriorates.
It is also useful to contain various surfactants (nonionic, cationic, anionic).

[Photosensitive composition]
In the present invention, the composition forming the photosensitive layer is referred to as a photosensitive composition. Each component contained in the photosensitive composition will be described sequentially.
(Infrared absorber)
In the present invention, it is essential that the photosensitive composition contains an infrared absorber. The infrared absorber has a function of converting absorbed infrared rays into heat. Due to the heat generated at this time, a polymerization initiator (radical generator) described later is thermally decomposed to generate radicals. The infrared absorbent used in the present invention is preferably a dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm.

  As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

  Examples of preferable dyes include cyanine dyes described in, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, JP-A-58-112793, JP-A-58- Naphthoquinone dyes described in JP-A-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc. Examples include squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent 434,875.

  Further, near infrared absorption sensitizers described in US Pat. No. 5,156,938 are also preferably used, and substituted aryl benzoates described in US Pat. No. 3,881,924 are also preferably used. (Thio) pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, JP-A-58-220143 No. 59-41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, JP-A 59-216146 Cyanine dyes described in US Pat. No. 4,283,475, pentamethine thiopyrylium salt described in US Pat. No. 4,283,475, etc. Pyrylium compounds disclosed in JP same 5-19702 are also preferably used. Moreover, as another example preferable as a dye, the near-infrared absorptive dye described as the formula (I) and (II) in US Patent 4,756,993 can be mentioned.

  In the present invention, other preferred examples of infrared absorbing dyes include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

Among these dyes, cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes are particularly preferable. Further, cyanine dyes and indolenine cyanine dyes are preferred, and particularly preferred examples include cyanine dyes represented by the following general formula (a).

In formula (a), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen 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 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. Here, the hetero atom represents N, S, O, a halogen atom, or Se. Xa ^- is defined as for Z ^1-to be described later, 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 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 or 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, carboxyl 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. Z ¹⁻ represents a counter anion. However, when the cyanine dye represented by the general formula (a) has an anionic substituent in its structure and charge neutralization is not necessary, Z ¹⁻ is not necessary. Preferred Z ¹⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of storage stability of the recording layer coating solution. Hexafluorophosphate ions and aryl sulfonate ions.

Specific examples of the cyanine dye represented by formula (a) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. be able to.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. When the particle diameter of the pigment is less than 0.01 μm, it is not preferable from the viewpoint of stability of the dispersion in the photosensitive layer coating solution, and when it exceeds 10 μm, it is not preferable from the viewpoint of uniformity of the photosensitive layer.

  As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

  In the negative planographic printing plate precursor, these infrared absorbers are usually contained in the photosensitive layer, but a layer different from the photosensitive layer may be provided and added thereto. When an infrared absorber is a negative planographic printing plate precursor, the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm of the photosensitive layer seems to be in the range of 0.5 to 1.2 by the reflection measurement method. Add to. Preferably, it is the range of 0.6-1.15. When the absorbance is outside this range, the strength of the image portion is reduced and the number of printed sheets is reduced. Although the cause is not clear, it can be assumed that when the absorbance is less than 0.5, the irradiated infrared rays cannot be sufficiently absorbed, and as a result, radical polymerization in the photosensitive layer as a whole does not proceed sufficiently. When the absorbance is greater than 1.2, only the outermost surface of the photosensitive layer absorbs infrared rays, and the infrared rays do not reach the vicinity of the support. As a result, radical polymerization does not occur in the vicinity of the support, and the support It can be assumed that the adhesive strength of the photosensitive layer is insufficient.

  The absorbance of the photosensitive layer can be adjusted by the amount of infrared absorber added to the photosensitive layer and the thickness of the photosensitive layer. Absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, a photosensitive layer having a thickness appropriately determined in a range where the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is measured by an optical densitometer. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.

(Polymerization initiator)
In the present invention, the photosensitive composition is a sulfonium salt that is a thermal decomposition type radical generator that decomposes by heat to generate radicals as a polymerization initiator for initiating and advancing the curing reaction of the polymerizable compound described later. Contains a polymerization initiator.
In the present invention, by using a sulfonium salt polymerization initiator in combination with the above-described infrared absorber, the infrared absorber generates heat when irradiated with an infrared laser, and a radical is generated by the heat. In the present invention, a combination of these enables high-sensitivity heat mode recording.

  Examples of the sulfonium salt polymerization initiator suitably used in the present invention include onium salts represented by the following general formula (A).

In general formula (A), R ¹¹ , R ¹² and R ¹³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. Z ¹¹⁻ represents a counter ion selected from the group consisting of a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a carboxylate ion, and a sulfonate ion, preferably a perchlorate ion, Hexafluorophosphate ions, carboxylate ions, and aryl sulfonate ions.

Specific examples ([OS-1] to [OS-10]) of the onium salt represented by the general formula (A) are shown below, but are not limited thereto.

  In addition to the above, specific aromatic sulfonium salts described in JP-A Nos. 2002-148790, 2002-148790, 2002-350207, and 2002-6482 are also preferably used. .

In the present invention, in addition to the sulfonium salt polymerization initiator contained as an essential component, other polymerization initiators (other radical generators) can be used in combination.
Other radical generators include onium salts other than sulfonium salts, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, quinonediazides, oxime ester compounds, triaryl monoalkylborate compounds Etc. Of these, onium salts are preferred because of their high sensitivity.

Other onium salts that can be suitably used in the present invention include iodonium salts and diazonium salts. In the present invention, these onium salts function not as acid generators but as radical polymerization initiators.
Other onium salts in the present invention include onium salts represented by the following general formulas (B) and (C).

In the general formula (B), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a carbon atom having 12 or less carbon atoms. An aryloxy group is mentioned. Z ^21- represents a counter ion having the same ^meaning as Z ^11- .

In the general formula (C), Ar ³¹ represents an aryl group having 20 or less carbon atoms which may have a substituent. Preferred examples of the substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, an aryloxy group having 12 or less carbon atoms, and 12 or less carbon atoms. Examples thereof include an alkylamino group, a dialkylamino group having 12 or less carbon atoms, an arylamino group having 12 or less carbon atoms, or a diarylamino group having 12 or less carbon atoms. Z ^31- represents a counter ion having the same ^meaning as Z ^11- .

  In the present invention, an onium salt represented by formula (B) ([OI-1] to [OI-10]) and an onium salt represented by formula (C) ([ Specific examples of ON-1] to [ON-5] are given below, but are not limited thereto.

  In the present invention, specific examples of onium salts that can be suitably used as a polymerization initiator (radical generator) include those described in JP-A-2001-133696.

  The polymerization initiator (radical generator) used in the present invention preferably has a maximum absorption wavelength of 400 nm or less, and more preferably 360 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the lithographic printing plate precursor can be handled under white light.

  In the present invention, the total content of the polymerization initiator in the photosensitive composition is 0.1 to 50% by mass, preferably 0.5 to 30% by mass, particularly preferably 1 to 20% by mass in the total solid content. is there. If the content is less than 0.1% by mass, the sensitivity tends to be low, and if it exceeds 50% by mass, stains tend to occur in the non-image area during printing when applied to a lithographic printing plate precursor.

If the polymerization initiator in this invention contains a sulfonium salt polymerization initiator as an essential component, only 1 type may be used and 2 or more types may be used together. When two or more polymerization initiators are used in combination, only a plurality of sulfonium salt polymerization initiators may be used, or a sulfonium salt polymerization initiator and another polymerization initiator may be used in combination.
The content ratio (mass ratio) when the sulfonium salt polymerization initiator and another polymerization initiator are used in combination is preferably 100/1 to 100/50, more preferably 100/5 to 100/25.
Further, the polymerization initiator may be added to the same photosensitive layer as the other components, or another layer may be provided and added thereto.

(Ethylenically unsaturated bond-containing monomer)
The ethylenically unsaturated bond-containing monomer in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and a compound having at least one ethylenically unsaturated bond, preferably two or more. Chosen from. 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, that is, dimers, trimers and oligomers, or mixtures thereof, and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.
Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.
Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.
Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, and JP-A-59-5240. And those having an aromatic skeleton described in JP-A-59-5241, JP-A-2-226149, and those containing an amino group described in JP-A-1-165613. Used. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

  In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (1) to a polyisocyanate compound having two or more isocyanate groups. Compounds and the like.

_{CH 2 = C (R 4)} COOCH 2 CH (R 5) OH Formula (1)
(However, R ₄ and R ₅ represent H or CH _3. )

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765, JP-B-58-49860, JP-B-56-17654, Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable. Further, by using addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238, It is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid compounds described in JP-A-2-25493 Etc. can also be mentioned. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combined use, and addition amount can be arbitrarily set according to the final performance design. For example, it is selected from the following viewpoints. From the viewpoint of photosensitive speed, a structure having a high unsaturated group content per molecule is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable, and further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether). It is also effective to adjust both photosensitivity and strength by using a compound of the type). A compound having a large molecular weight or a compound having high hydrophobicity is excellent in photosensitive speed and film strength, but is not preferable in terms of development speed and precipitation in a developer. Further, the selection / use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components in the composition (for example, binder polymer, initiator, colorant, etc.). In some cases, the compatibility can be improved by using a low-purity compound or using two or more of them together.
In addition, when the photosensitive composition is applied to a lithographic printing plate precursor, a specific structure may be selected for the purpose of improving the adhesion of a support or an overcoat layer described later.

  Regarding the compounding ratio of the addition polymerizable compound in the composition, a larger amount is advantageous in terms of sensitivity, but if it is too large, undesirable phase separation occurs or the photosensitive layer is applied when applied to a lithographic printing plate precursor. Problems in the production process due to the adhesive property (for example, transfer of photosensitive layer components, production failure due to adhesion), and precipitation from the developer may occur. From these viewpoints, the addition polymerizable compound is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass, with respect to the nonvolatile component in the composition. These may be used alone or in combination of two or more. In addition, the use method of the addition polymerizable compound can arbitrarily select an appropriate structure, blending, and addition amount from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging property, refractive index change, surface adhesiveness, and the like. Further, when the photosensitive composition is applied to a lithographic printing plate precursor, a layer configuration / coating method such as undercoating or overcoating can be carried out.

(Binder polymer)
The binder polymer in the present invention is contained from the viewpoint of improving the film property, and various types can be used as long as it has a function of improving the film property. Among these, a binder polymer suitable for the present invention is a binder polymer having a repeating unit represented by the following general formula (i).

Hereinafter, the binder polymer having the repeating unit represented by the general formula (i) is appropriately referred to as “specific binder polymer” and will be described in detail.
First, R ¹ in the general formula (i) represents a hydrogen atom or a methyl group, and a methyl group is particularly preferable.

The linking group represented by R ² in the general formula (i) is composed of a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom and a halogen atom, and the number of atoms excluding the substituent is 2 to 30. is there. Specific examples include alkylene, substituted alkylene, arylene, substituted arylene, and the like, and a structure in which a plurality of these divalent groups are linked by an amide bond or an ester bond may be used.
Examples of the linking group having a chain structure include ethylene and propylene. A structure in which these alkylenes are linked via an ester bond can also be exemplified as a preferable example.

Among these, the linking group represented by R ² in the general formula (i) is preferably an (n + 1) -valent hydrocarbon group having an aliphatic cyclic structure having 3 to 30 carbon atoms. More specifically, a compound having an aliphatic cyclic structure such as cyclopropane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, dicyclohexyl, tercyclohexyl, norbornane and the like, which may be substituted by one or more arbitrary substituents And (n + 1) valent hydrocarbon groups by removing (n + 1) hydrogen atoms on an arbitrary carbon atom constituting. R ² preferably has 3 to 30 carbon atoms including a substituent.

One or more arbitrary carbon atoms of the compound constituting the aliphatic cyclic structure may be replaced with a heteroatom selected from a nitrogen atom, an oxygen atom, or a sulfur atom. In terms of printing durability, R ² represents a condensed polycyclic aliphatic hydrocarbon, a bridged cyclic aliphatic hydrocarbon, a spiro aliphatic hydrocarbon, an aliphatic hydrocarbon ring assembly (a plurality of rings are connected by a bond or a linking group). A (n + 1) valent hydrocarbon group having an aliphatic cyclic structure which may have a substituent of 5 to 30 carbon atoms containing two or more rings. . Also in this case, the carbon number includes the carbon atom of the substituent.

As the linking group represented by R ² , those having 5 to 10 atoms are further preferable, and structurally a chain structure having an ester bond in the structure, Those having a cyclic structure are preferred.

Examples of the substituent that can be introduced into the linking group represented by R ² include monovalent nonmetallic atomic groups other than hydrogen, such as halogen atoms (—F, —Br, —Cl, —I), hydroxyl groups. Group, alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N- Diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy , Arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-aryl Ureido group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N ′ -Alkyl-N-arylureido group, N ', N'-dialkyl-N-alkylureido group, N', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N ' -Aryl-N-arylureido group, N ', N'-diaryl-N-alkylureido group, N', N'-diaryl-N-arylureido group, N'-al Kill-N′-aryl-N-alkylureido group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group and its conjugate base group, Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, Alkylsulfinyl group An arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group (-SO ₃ H) and its conjugated base group, alkoxy sulfonyl group, aryloxy sulfonyl group, sulfinamoyl group, N- alkylsulfinamoyl group, N, N- Dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N -Dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, N-acylsulfamoyl group and its conjugate base group, N- alkylsulfonylsulfamoyl group (-SO ₂ NHSO ₂ alkyl)) and its conjugated base group, N- aryl sulfonylsulfamoyl group _{(-SO 2 NHSO 2 (aryl)} ) and its conjugated base group, N- alkylsulfonylcarbamoyl group (-CONHSO ₂ (alkyl)) and its conjugate Base group, N-arylsulfonylcarbamoyl group (—CONHSO ₂ (aryl)) and its conjugate base group, alkoxysilyl group (—Si (Oalkyl) ₃ ), aryloxysilyl group (—Si (Oaryl) ₃ ), hydroxysilyl Group (—Si (OH) ₃ ) and its conjugate base group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group, dialkylphosphono group (—PO ₃ (alkyl) ₂ ), diarylphosphono group (— PO ₃ (aryl) _2), alkyl aryl phosphono group _{(-PO 3 (alkyl) (aryl} )) , Monoalkylphosphono group (—PO ₃ H (alkyl)) and its conjugate base group, monoarylphosphono group (—PO ₃ H (aryl)) and its conjugate base group, phosphonooxy group (—OPO ₃ H ₂ ) And its conjugate base group, dialkylphosphonooxy group (—OPO ₃ (alkyl) ₂ ), diarylphosphonooxy group (—OPO ₃ (aryl) ₂ ), alkylarylphosphonooxy group (—OPO ₃ (alkyl) ( aryl)), monoalkylphosphonooxy group (—OPO ₃ H (alkyl)) and its conjugate base group, monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base group, cyano group, nitro group, group, ₍₂ -B (alkyl)) dialkyl boryl group, Jiariruboriru group (-B (aryl) _2), alkyl aryl boryl -B (alkyl) (aryl)) , dihydroxy boryl group (-B (OH) ₂₎ and its conjugated base group, an alkyl hydroxy boryl group (-B (alkyl) (OH) ) and its conjugated base group, an aryl hydroxy boryl And the group (—B (aryl) (OH)) and its conjugate base group, aryl group, alkenyl group and alkynyl group.

  In the present invention, although the binder polymer depends on the design of the photosensitive layer, a substituent having a hydrogen atom capable of hydrogen bonding, particularly a substituent having an acid dissociation constant (pKa) smaller than that of a carboxylic acid, This is not preferable because it tends to lower the printability. On the other hand, hydrophobic substituents such as halogen atoms, hydrocarbon groups (alkyl groups, aryl groups, alkenyl groups, alkynyl groups), alkoxy groups, aryloxy groups and the like are more preferable because they tend to improve printing durability. When the cyclic structure is a monocyclic aliphatic hydrocarbon having 6 or less members such as cyclopentane or cyclohexane, it preferably has such a hydrophobic substituent. If possible, these substituents may be bonded to each other or with a substituted hydrocarbon group to form a ring, and the substituent may be further substituted.

R ³ in the case where A in formula (i) is NR ³ — represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ³ include an alkyl group, an aryl group, an alkenyl group, and an alkynyl group.
Specific examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, isopropyl group, isobutyl group, sec-butyl group, 1 carbon number such as tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-norbornyl group Up to 10 linear, branched or cyclic alkyl groups.
Specific examples of the aryl group include carbon having one heteroatom selected from the group consisting of an aryl group having 1 to 10 carbon atoms such as a phenyl group, a naphthyl group, and an indenyl group, a nitrogen atom, an oxygen atom, and a sulfur atom. Examples include heteroaryl groups of 1 to 10, such as furyl, thienyl, pyrrolyl, pyridyl, and quinolyl groups.
Specific examples of the alkenyl group include those having 1 to 10 carbon atoms such as vinyl group, 1-propenyl group, 1-butenyl group, 1-methyl-1-propenyl group, 1-cyclopentenyl group, 1-cyclohexenyl group and the like. A linear, branched, or cyclic alkenyl group is mentioned.
Specific examples of the alkynyl group include alkynyl groups having 1 to 10 carbon atoms such as ethynyl group, 1-propynyl group, 1-butynyl group, and 1-octynyl group. The substituent that R ³ may have is the same as those exemplified as the substituent that R ² can introduce. However, the carbon number of R < ³ > is 1-10 including the carbon number of a substituent.
A in the general formula (i) is preferably an oxygen atom or —NH— because synthesis is easy.

  N in the general formula (i) represents an integer of 1 to 5, and is preferably 1 in terms of printing durability.

Although the preferable specific example of the repeating unit represented by general formula (i) below is shown, this invention is not limited to these.

  One type of repeating unit represented by the general formula (i) may be contained in the binder polymer, or two or more types may be contained. The specific binder polymer in the present invention may be a polymer composed only of the repeating unit represented by the general formula (i), but is usually used as a copolymer in combination with other copolymerization components. The total content of the repeating unit represented by the general formula (i) in the copolymer is appropriately determined depending on the structure, the design of the composition, etc., but preferably 1 to 99 mol% with respect to the total molar amount of the polymer component. More preferably, it is contained in the range of 5 to 40 mol%, more preferably 5 to 20 mol%.

  As a copolymerization component in the case of using as a copolymer, a conventionally well-known thing can be used without a restriction | limiting, if it is a monomer which can be radically polymerized. Specific examples include monomers described in “Polymer Data Handbook—Basic Edition” (Edition of Polymer Society, Bafukan, 1986). One type of such copolymerization component may be used, or two or more types may be used in combination.

  The molecular weight of the specific binder polymer in the present invention is appropriately determined from the viewpoint of image formability and printing durability of the lithographic printing plate precursor. Usually, when the molecular weight increases, the printing durability is excellent, but the image formability tends to deteriorate. On the other hand, if it is low, the image forming property is improved, but the printing durability is lowered. The molecular weight is preferably in the range of 2,000 to 1,000,000, more preferably 5,000 to 500,000, and still more preferably 10,000 to 200,000.

  The binder polymer used in the present invention may be a specific binder polymer alone or a mixture of one or more other binder polymers. The binder polymer used in combination is used in the range of 1 to 60% by mass, preferably 1 to 40% by mass, and more preferably 1 to 20% by mass with respect to the total mass of the binder polymer component. As the binder polymer that can be used in combination, a conventionally known binder polymer can be used without limitation, and specifically, an acrylic main chain binder, a urethane binder, or the like often used in the industry is preferably used.

Although the total amount of the specific binder polymer in the composition and the binder polymer that may be used in combination can be determined as appropriate, it is usually 10 to 90% by mass, preferably, based on the total mass of nonvolatile components in the composition. It is 20-80 mass%, More preferably, it is the range of 30-70 mass%.
Moreover, as an acid value (meg / g) of such a binder polymer, it is preferable that it is the range of 2.00-3.60.

<Other binder polymers that can be used in combination>
The other binder polymer that can be used in combination with the specific binder polymer is preferably a binder polymer having a radical polymerizable group. The radical polymerizable group is not particularly limited as long as it can be polymerized by radicals, but α-substituted methylacrylic group [—OC (═O) —C (—CH ₂ Z) ═CH ₂ , Z = A hydrocarbon group starting from a hetero atom], an acryl group, a methacryl group, an allyl group, and a styryl group. Among these, an acryl group and a methacryl group are preferable.
The content of the radical polymerizable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1 per 1 g of the binder polymer. 0.0 to 7.0 mmol, most preferably 2.0 to 5.5 mmol. If this content is less than 0.1 mmol, the curability may be low and the sensitivity may be low. Moreover, when content is larger than 10.0 mmol, it may become unstable and a preservability may fall.

  Further, the other binder polymer that can be used in combination is preferably one having an alkali-soluble group. The content of alkali-soluble groups in the binder polymer (acid value by neutralization titration) is preferably 0.1 to 3.0 mmol, more preferably 0.2 to 2.0 mmol, most preferably 0, per 1 g of the binder polymer. .45-1.0 mmol. When this content is less than 0.1 mmol, it may be deposited during development to generate development residue. On the other hand, if the content is more than 3.0 mmol, the hydrophilicity is too high and the printing durability may be lowered when applied to a lithographic printing plate precursor.

  The weight average molecular weight of such a binder polymer is preferably in the range of 2,000 to 1,000,000, more preferably 10,000 to 300,000, and most preferably 20,000 to 200,000. When this mass average molecular weight is less than 2,000, the film property may be lowered and the printing durability may be deteriorated. On the other hand, if the mass average molecular weight is larger than 1,000,000, the coating property may be poorly dissolved in the coating solvent.

Further, the glass transition point (Tg) of such a binder polymer is preferably in the range of 70 to 300 ° C, more preferably 80 to 250 ° C, and most preferably 90 to 200 ° C. When this glass transition point is lower than 70 ° C., the storage stability is lowered, and the printing durability may be deteriorated when applied to a lithographic printing plate precursor. On the other hand, if the glass transition point is higher than 300 ° C., the radical mobility in the composition may be lowered, resulting in low sensitivity.
As a means for increasing the glass transition point of the binder polymer, the molecule preferably contains an amide group or an imide group, and particularly preferably contains a methacrylamide methacrylamide derivative.

  In the present invention, in addition to the above basic components, other components suitable for the use, production method, and the like can be appropriately added to the photosensitive composition. Hereinafter, preferred additives will be exemplified.

(Polymerization inhibitor)
In the present invention, it is desirable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of a polymerizable compound having an ethylenically unsaturated double bond, that is, a polymerizable compound. Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxyamine primary cerium salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the nonvolatile components in the entire composition. If necessary, a higher fatty acid derivative such as behenic acid or behenic acid amide may be added to prevent polymerization inhibition due to oxygen, and it may be unevenly distributed on the surface of the photosensitive layer in the course of drying after coating. . The addition amount of the higher fatty acid derivative is preferably about 0.5% by mass to about 10% by mass with respect to the nonvolatile components in the entire composition.

(Coloring agent)
Further, a dye or pigment may be added to the present invention for the purpose of coloring. Thereby, so-called plate inspection properties such as visibility after plate making and suitability for an image density measuring machine as a printing plate can be improved. As the colorant, many dyes cause a decrease in the sensitivity of the photopolymerization type photosensitive layer. Therefore, it is particularly preferable to use a pigment as the colorant. Specific examples include pigments such as phthalocyanine pigments, azo pigments, carbon black and titanium oxide, and dyes such as ethyl violet, crystal violet, azo dyes, anthraquinone dyes, and cyanine dyes. The addition amount of the dye and the pigment as the colorant is preferably about 0.5% by mass to about 5% by mass with respect to the non-volatile components in the entire composition.

(Other additives)
Furthermore, you may add well-known additives, such as an inorganic filler for improving the physical property of a cured film, other plasticizers, and a fat-sensitizing agent which can improve the ink deposition property of the photosensitive layer surface. Examples of plasticizers include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerin, and addition polymerization with binder polymer. Generally, it can be added in a range of 10% by mass or less based on the total mass with the compound. Further, in the lithographic printing plate precursor described later, a UV initiator, a thermal crosslinking agent, or the like can be added to enhance the effect of heating and exposure after development for the purpose of improving the film strength (printing durability).

[Negative lithographic printing plate precursor]
In the present invention, the negative lithographic printing plate precursor is a lithographic printing plate precursor obtained by sequentially laminating a photosensitive layer and optionally a protective layer on a support, and the photosensitive layer is the photosensitive composition described above. It is characterized by including a thing. Such a lithographic printing plate precursor is coated on a suitable support or intermediate layer by dissolving a photosensitive layer coating solution containing the above-described photosensitive composition or a coating layer component of a desired layer such as a protective layer in a solvent. Can be manufactured.

(Photosensitive layer)
The photosensitive layer according to the present invention comprises, as essential components, an infrared absorber, a polymerization initiator, an ethylenically unsaturated bond-containing compound (also referred to as an addition polymerizable compound), and a binder polymer. It is. Such a heat-polymerizable negative photosensitive layer has a mechanism in which a polymerization initiator is decomposed by heat to generate radicals, and a polymerizable compound causes a polymerization reaction by the generated radicals. Furthermore, such a lithographic printing plate precursor is particularly suitable for plate making by direct drawing with a laser beam having a wavelength of 300 to 1,200 nm, and has higher printing durability and image quality than conventional lithographic printing plate precursors. Expresses formability.

  When coating the photosensitive layer, the photosensitive composition having the components described above is dissolved in various organic solvents and coated on the support or the intermediate layer. Solvents used here include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 3-methoxypropanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, Ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, lactic acid There are ethyl and the like. These solvents can be used alone or in combination. The solid content in the coating solution is suitably 2 to 50% by mass.

The coating amount of the photosensitive layer mainly affects the sensitivity of the photosensitive layer, the developability, and the strength and printing durability of the exposed film, and is preferably selected as appropriate according to the application. When the coating amount is too small, the printing durability is not sufficient. On the other hand, if the amount is too large, the sensitivity is lowered, it takes time for exposure, and a longer time is required for development processing, which is not preferable. For the lithographic printing plate precursor for scanning exposure which is the main object of the present invention, the coating amount is suitably in the range of about 0.1 g / m ² to about 10 g / m ² in terms of the mass after drying. More preferably from 0.5 to 5 g / m ^2.

[Support]
As the support for the lithographic printing plate precursor used in the present invention, a conventionally known hydrophilic support for use in the lithographic printing plate precursor can be used without limitation.
The support used is preferably a dimensionally stable plate, for example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc). , Copper, etc.), plastic films (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), Paper or plastic film, etc. on which such metals are laminated or vapor-deposited are included. Appropriately known physical and chemical treatments are applied to these surfaces for the purpose of imparting hydrophilicity and improving strength as necessary. You may give it.

  In particular, preferred supports include paper, polyester film or aluminum plate, among which dimensional stability is good, relatively inexpensive, and a surface with excellent hydrophilicity and strength is provided by surface treatment as required. An aluminum plate that can be formed is more preferable. A composite sheet in which an aluminum sheet is bonded on a polyethylene terephthalate film as described in Japanese Patent Publication No. 48-18327 is also preferable.

An aluminum plate is a metal plate mainly composed of dimensionally stable aluminum. In addition to a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or aluminum (alloy) is laminated. Or it is chosen from the vapor-deposited plastic film or paper. In the following description, the above-described substrates made of aluminum or aluminum alloy are collectively referred to as an aluminum substrate. Examples of the foreign element contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of the foreign element in the alloy is 10% by mass or less. In the present invention, a pure aluminum plate is suitable. However, since pure aluminum is difficult to manufacture in terms of refining technology, it may contain slightly different elements. Thus, the composition of the aluminum plate applied to the present invention is not specified, and it is a conventionally known material such as JIS A 1050, JIS A 1100, JIS A 3103, JIS A 3005, etc. Can be used as appropriate.
The thickness of the aluminum substrate used in the present invention is about 0.1 mm to 0.6 mm. This thickness can be appropriately changed depending on the size of the printing press, the size of the printing plate, and the user's desire. The aluminum substrate may be subjected to a substrate surface treatment described later as necessary. Of course, it may not be applied.

(Roughening treatment)
Examples of the roughening treatment method include mechanical roughening, chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. Furthermore, the electrochemical surface roughening method in which the surface is electrochemically roughened in hydrochloric acid or nitric acid electrolyte solution, the aluminum surface is scratched with a metal wire, the wire brush grain method, the surface of the aluminum is polished with a polishing ball and an abrasive. A mechanical graining method such as a pole grain method, a brush grain method in which the surface is roughened with a nylon brush and an abrasive, can be used, and the above roughening methods can be used alone or in combination. Among them, a method usefully used for roughening is an electrochemical method in which roughening is performed chemically in hydrochloric acid or nitric acid electrolyte, and a suitable amount of electricity at the time of anode is 50 C / dm ^{2 to} 400 C / dm ² . It is a range. More specifically, in the electrolytic solution containing from 0.1 to 50% hydrochloric acid or nitric acid, the temperature 20 to 80 ° C., for 1 second to 30 minutes, alternating at a current density of 100C / dm ² ~400C / dm ² It is preferable to perform direct current electrolysis.

  The roughened aluminum substrate may be chemically etched with acid or alkali. Etching agents suitably used are caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, and the like. Preferred ranges of concentration and temperature are 1 to 50% and 20%, respectively. ~ 100 ° C. Pickling is performed to remove dirt (smut) remaining on the surface after etching. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borohydrofluoric acid and the like are used. In particular, as a method for removing smut after the electrochemical surface roughening treatment, contact with 15 to 65 mass% sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739 is preferable. And the alkali etching method described in Japanese Patent Publication No. 48-28123. After the treatment as described above, the method condition is not particularly limited as long as the center line average roughness Ra of the treatment surface is 0.2 to 0.5 μm.

(Anodizing treatment)
The aluminum substrate that has been processed as described above to form an oxide layer is then anodized.
In the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid, or an aqueous solution of boric acid / sodium borate is used alone or in combination as a main component of the electrolytic bath. In this case, the electrolyte solution may of course contain at least components normally contained in at least an Al alloy plate, an electrode, tap water, groundwater and the like. Further, the second and third components may be added. Here, the second and third components are, for example, metal ions such as Na, K, Mg, Li, Ca, Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and ammonium ions. Examples include cations, nitrate ions, carbonate ions, chloride ions, phosphate ions, fluorine ions, sulfite ions, titanate ions, silicate ions, borate ions and the like, and the concentration is 0 to 10,000 ppm. May be included. There are no particular limitations on the conditions of the anodizing treatment, but the treatment is preferably carried out by direct current or alternating current electrolysis at a current density of 0.1 to 40 A / m ² at 30 to 500 g / liter, a treatment liquid temperature of 10 to 70 ° C. . The thickness of the formed anodic oxide film is in the range of 0.5 to 1.5 μm. Preferably it is the range of 0.5-1.0 micrometer. The support prepared by the above treatment is treated so that the pore diameter of the micropores existing in the anodized film is in the range of 5 to 10 nm and the pore density is in the range of 8 × 10 ¹⁵ to 2 × 10 ¹⁶ pieces / m ^2. Conditions can be selected.

A widely known method can be applied as the hydrophilic treatment on the surface of the support. As a particularly preferable treatment, a hydrophilic treatment with silicate or polyvinylphosphonic acid is performed. A film | membrane is formed by 2-40 mg / m < ² > as Si or P element amount, More preferably, it is 4-30 mg / m < ² >. The coating amount can be measured by fluorescent X-ray analysis.

  The hydrophilization treatment is carried out by applying an anodized film to an aqueous solution containing 1 to 30% by mass, preferably 2 to 15% by mass of alkali metal silicate or polyvinylphosphonic acid, and having a pH of 10 to 13 at 25 ° C. This is carried out by immersing the aluminum substrate on which is formed, for example, at 15 to 80 ° C. for 0.5 to 120 seconds.

  As the alkali metal silicate used for the hydrophilization treatment, sodium silicate, potassium silicate, lithium silicate, or the like is used. Examples of the hydroxide used for increasing the pH of the aqueous alkali metal silicate solution include sodium hydroxide, potassium hydroxide, and lithium hydroxide. In addition, you may mix | blend alkaline-earth metal salt or Group IVB metal salt with said process liquid. Alkaline earth metal salts include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate, and water-soluble substances such as sulfate, hydrochloride, phosphate, acetate, oxalate, and borate. Salt. Group IVB metal salts include titanium tetrachloride, titanium trichloride, potassium fluoride titanium, potassium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride, zirconium tetrachloride, etc. Can be mentioned.

  Alkaline earth metal salts or Group IVB metal salts can be used alone or in combination of two or more. A preferable range of these metal salts is 0.01 to 10% by mass, and a more preferable range is 0.05 to 5.0% by mass. Silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective. Surface obtained by combining a support with electrolytic grains as disclosed in JP-B-46-27481, JP-A-52-58602, JP-A-52-30503, and the above anodizing treatment and hydrophilization treatment Processing is also useful.

The lithographic printing plate precursor may be provided with an intermediate layer for the purpose of improving adhesion between the photosensitive layer and the support and soiling. As specific examples of such an intermediate layer, those described in the following publications or specifications can be suitably applied.
JP-B-50-7481, JP-A-54-72104, JP-A-59-101651, JP-A-60-149491, JP-A-60-232998, JP-A-3-56177, JP-A-4-56177 No. 282637, JP-A-5-16558, JP-A-5-246171, JP-A-7-159983, JP-A-7-314937, JP-A-8-202025, JP-A-8-320551, JP-A-9-34104 JP-A-9-236911, JP-A-9-269593, JP-A-10-69092, JP-A-10-115931, JP-A-10-161317, JP-A-10-260536, JP-A-10-282682. JP-A-11-84684, JP-A-10-69092, JP-A-10-115931, JP-A-11-38635, Kaihei 11-38629, JP 10-282645, JP 10-301262, JP 11-24277, JP 11-109641, JP 10-319600, JP 11-84684, JP 11-327152, JP-A 2000-10292, JP-A 2000-235254, JP-A 2000-352824, JP-A 2001-175001, JP-A 2001-209170, and the like.

[Protective layer (overcoat layer)]
In the present invention, it is preferable to provide a protective layer on the photosensitive layer. The protective layer is basically provided to protect the photosensitive layer. However, when the photosensitive layer has a radical polymerizable image forming mechanism as in the present invention, it has a role as an oxygen blocking layer and has a high illuminance. When exposed with an infrared laser, it functions as an ablation preventing layer.
In addition to the properties desired for the protective layer, in addition to the above, the transmission of light used for exposure is not substantially inhibited, it has excellent adhesion to the photosensitive layer, and can be easily removed in the development process after exposure. Is desirable. Such a protective layer has been conventionally devised and described in detail in US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729.

  As a material that can be used for the protective layer, for example, a water-soluble polymer compound having relatively excellent crystallinity is preferably used. Specifically, polyvinyl alcohol, vinyl alcohol / vinyl phthalate copolymer, vinyl acetate / vinyl are used. Examples include water-soluble polymers such as alcohol / vinyl phthalate copolymer, vinyl acetate / crotonic acid copolymer, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, polyacrylic acid, polyacrylamide, etc. Or they can be mixed. Of these, the use of polyvinyl alcohol as the main component gives the best results in terms of basic properties such as oxygen barrier properties and development removability.

The polyvinyl alcohol used for the protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains an unsubstituted vinyl alcohol unit for having necessary oxygen barrier properties and water solubility. Similarly, some of them may have other copolymer components.
Specific examples of polyvinyl alcohol include those that are hydrolyzed by 71 to 100% and have a polymerization repeating unit in the range of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, L-8 and the like.

Components of the protective layer (selection of PVA, use of additives), coating amount, and the like are selected in consideration of fogging, adhesion, and scratch resistance in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of the PVA used (the higher the content of unsubstituted vinyl alcohol units in the oxygen barrier layer), the thicker the film thickness, the higher the oxygen barrier property, which is advantageous in terms of sensitivity. is there. However, when the oxygen barrier property is extremely increased, there arises a problem that unnecessary polymerization reaction occurs during production and raw storage, and unnecessary fogging and image line thickening occur during image exposure.
Accordingly, the oxygen permeability A at 25 ° C. and 1 atm is preferably 0.2 ≦ A ≦ 20 (cc / m ² · day).
The molecular weight of the (co) polymer such as polyvinyl alcohol (PVA) can be in the range of 2000 to 10 million, preferably in the range of 20,000 to 3 million.

As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers to the (co) polymer Mass% can be added.
The thickness of the protective layer is suitably from 0.5 to 5 μm, particularly preferably from 0.5 to 2 μm.

  In addition, adhesion to the image area and scratch resistance are also extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on a new oil-based polymer layer, film peeling due to insufficient adhesion tends to occur, and the peeled part causes defects such as poor film hardening due to inhibition of oxygen polymerization. On the other hand, various proposals have been made to improve the adhesion between these two layers. For example, in U.S. Patent Application No. 292,501 and U.S. Patent Application No. 44,563, an acrylic emulsion or a water-insoluble vinyl pyrrolidone-vinyl acetate copolymer is contained in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesiveness can be obtained by mixing 20 to 60% by mass and laminating on a polymerization layer. Any of these known techniques can be applied to the protective layer in the present invention. Such a coating method for the protective layer is described in detail in, for example, US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729.

In the method of the present invention, at least exposure and development processes are performed in order to make a lithographic printing plate from a lithographic printing plate precursor.
As a light source for exposing the lithographic printing plate precursor according to the invention, an infrared laser is preferable, and thermal recording with an ultraviolet lamp or a thermal head is also possible.
In particular, in the present invention, image exposure is preferably performed by a solid-state laser and a semiconductor laser that emit infrared rays having a wavelength of 750 nm to 1400 nm. The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec. The energy applied to the planographic printing plate precursor is preferably 10 to 300 mJ / cm ² . If the exposure energy is too low, the image recording layer does not sufficiently cure. If the exposure energy is too high, the image recording layer may be laser ablated and the image may be damaged.

  The exposure in the present invention can be performed by overlapping the light beams of the light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the present invention, the overlap coefficient is preferably 0.1 or more.

  The scanning method of the light source of the exposure apparatus used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, or the like can be used. The channel of the light source may be a single channel or a multi-channel, but in the case of a cylindrical outer surface system, a multi-channel is preferably used.

In the method of the present invention, after the exposure, first, a treatment (hereinafter also referred to as a pre-development washing step) is performed with a washing solution containing at least one preservative and at least one chelating agent. In the pre-development washing step, for the purpose of mainly removing the protective layer, the pre-development washing solution is first sprayed or dipped to wet the plate surface, and then the protective layer is removed using a brush such as a rotating brush. Scraping and removing while dissolving. The treatment temperature is not particularly limited, but it is usually performed near room temperature. The processing time by the brush naturally varies depending on the type and size of the brush and the area to be processed, but is, for example, 3 to 10 seconds. The pre-development washing solution is processed while replenishing, for example, 10 to 100 cc / m ² depending on the processing amount.
In addition, you may heat-process between an exposure process and the pre-development washing process. The heat treatment condition is preferably 5 seconds to 5 minutes in the temperature range of 60 to 150 ° C.
The heat treatment can be appropriately selected from conventionally known various methods. Specific examples include a method of heating the lithographic printing plate precursor while being in contact with a panel heater or a ceramic heater, a non-contact heating method using a lamp or hot air, and the like. By performing the heat treatment, it is possible to reduce the amount of laser energy required for image recording of the laser to be irradiated.

  Furthermore, when developing an exposed lithographic printing plate using an automatic developing machine, the developer will be fatigued depending on the amount of processing, so the processing capacity will be restored using a replenisher or fresh developer. You may let them. In this case, it is preferable to replenish by the method described in US Pat. No. 4,882,246. Further, the developers described in JP-A Nos. 50-26601, 58-54341, 56-39464, 56-42860, and 57-7427 are also preferable.

The lithographic printing plate thus developed is then treated with a washing solution containing at least one preservative and at least one chelating agent (hereinafter also referred to as a post-development washing step). The post-development water-washing step is mainly intended to lower the pH of the plate surface by removing the developer, and includes the post-development water-washing solution to wet the plate surface with a spray or the like, or immersing the plate in the water-washing solution. . The processing time naturally varies depending on the processing area and the like, but is usually about 3 to 10 seconds. The treatment temperature is not particularly limited, but it is usually performed near room temperature. The post-development washing solution is processed, for example, while replenishing 10 to 100 cc / m ² depending on the amount of processing. Further, as described in JP-A Nos. 54-8002, 55-1115045, 59-58431, etc., a rinsing solution, a gum arabic and starch containing a washing solution, a surfactant, etc. You may post-process with the desensitizing liquid containing a derivative etc. These treatments can be used in various combinations for the post-treatment of the planographic printing plate of the present invention.

In plate making of a lithographic printing plate precursor according to the method of the present invention, it is effective to carry out full post-heating or full exposure of an image after development for the purpose of improving image strength and printing durability.
Very strong conditions can be used for heating after development. Usually, the heating temperature is 200 to 500 ° C. If the heating temperature after development is low, sufficient image reinforcing action cannot be obtained, and if it is too high, problems such as deterioration of the support and thermal decomposition of the image area may occur.

The planographic printing plate obtained by the above processing is loaded on an offset printing machine and used for printing a large number of sheets.
As plate cleaners used for removing stains on the plate during printing, conventionally known plate cleaners for PS plates are used. For example, CL-1, CL-2, CP, CN-4, CN, CG-1, PC-1, SR, IC (made by Fuji Photo Film Co., Ltd.), etc. are mentioned.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.
(Production of support)
<Aluminum plate>
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.001 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: It contains 0.03% by mass, and the balance is prepared using Al and an inevitable impurity aluminum alloy. After the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Produced. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, it was kept soaked at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Furthermore, after performing heat processing using a continuous annealing machine at 500 degreeC, it finished by cold rolling to 0.24 mm in thickness, and obtained the aluminum plate of JIS1050 material. After making this aluminum plate width 1030mm, it used for the surface treatment shown below.

<Surface treatment>
The surface treatment was performed by continuously performing the following various treatments (a) to (j). In addition, after each process and water washing, the liquid was drained with the nip roller.

(A) Mechanical surface roughening treatment While supplying a suspension of a polishing agent (pumice) having a specific gravity of 1.12 and water as a polishing slurry liquid to the surface of the aluminum plate, mechanical roughening is performed by a rotating nylon brush. Surface treatment was performed. The average particle size of the abrasive was 30 μm, and the maximum particle size was 100 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 45 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkali etching treatment The aluminum plate obtained above was subjected to an etching treatment by spraying using an aqueous solution having a caustic soda concentration of 2.6% by mass, an aluminum ion concentration of 6.5% by mass and a temperature of 70 ° C. / M ² dissolved. Then, water washing by spraying was performed.

(C) Desmutting treatment The desmutting treatment was performed by spraying with a 1% by mass aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by mass of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a process of performing an electrochemical surface roughening treatment using alternating current in a nitric acid aqueous solution.

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10.5 g / L aqueous solution of nitric acid (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions) at a liquid temperature of 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio 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 alternating current. Went. Ferrite was used for the auxiliary anode.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Then, water washing by spraying was performed.

(E) Alkali etching treatment An aluminum plate was subjected to an etching treatment by spraying at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% to dissolve the aluminum plate by 0.50 g / m ^2. The smut component mainly composed of aluminum hydroxide generated when the electrochemical surface roughening process is performed using the alternating current of the previous stage is removed, and the edge portion of the generated pit is melted to smooth the edge portion. I made it. Then, water washing by spraying was performed.

(F) Desmut treatment Desmut treatment was performed by spraying with a 15% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 4.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a process of performing an electrochemical surface roughening treatment using alternating current in a nitric acid aqueous solution.

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 5.0 g / L aqueous solution (containing 5 g / L of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform is subjected to electrochemical surface roughening using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1. went. Ferrite was used for the auxiliary anode.
The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. Then, water washing by spraying was performed.

(H) Alkaline etching treatment An aluminum plate was subjected to an etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass%, and the aluminum plate was dissolved at 0.10 g / m ² . Removes the smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening treatment was performed using alternating current in the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

(I) Desmutting treatment A desmutting treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid at a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

(J) Anodizing treatment Anodizing treatment was performed using an anodizing apparatus to obtain a lithographic printing plate support. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 170 g / L (containing 0.5 mass% of aluminum ions) and a temperature of 38 ° C. Then, water washing by spraying was performed. The final oxide film amount was 2.7 g / m ² .
The Ra of the support obtained by the above treatment was 0.45.

〔undercoat〕
Next, the following undercoat liquid was applied to this aluminum support with a wire bar, and dried at 90 ° C. for 30 seconds using a hot air drying apparatus. The coating amount after drying was 10 mg / m ² .

<Undercoat liquid>
A copolymer of ethyl acrylate and 2-acrylamido-2-methyl-1-propane sulfonic acid sodium salt in a molar ratio of 75:15 0.1 g
・ 2-aminoethylphosphonic acid 0.1g
・ Methanol 50g
・ Ion exchange water 50g

(Photosensitive layer)
Next, the following photosensitive layer coating solution [P-1] was prepared and applied to the above-mentioned undercoated aluminum plate using a wire bar. Drying was performed at 122 ° C. for 43.5 seconds with a hot air drying apparatus to form a photosensitive layer. The coating amount after drying was 1.4 g / m ² .

<Photosensitive layer coating solution [P-1]>
・ Infrared absorber (IR-1) 0.08g
-Polymerization initiator (OS-1) 0.25g
・ Dipentaerythritol hexaacrylate 1.00g
・ Binder polymer (BT-1) 1.00g
・ Ethyl violet chloride 0.04g
・ Fluorine surfactant 0.03g
(Megafuck F-780-F Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 10.4g
・ Methanol 4.83g
・ 10.4 g of 1-methoxy-2-propanol

The structures of the infrared absorber (IR-1), the polymerization initiator (OS-1), and the binder polymer (BT-1) used in the photosensitive layer coating solution are shown below.

[Protective layer (overcoat layer)]
On the surface of the photosensitive layer, a mixed aqueous solution of polyvinyl alcohol (saponification degree 98 mol%, polymerization degree 500) and polyvinylpyrrolidone (manufactured by BASF Corp., Rubiscor K-30) is applied using a wire bar. It was dried at 125 ° C. for 75 seconds with a drying apparatus. The content of PVA was 85% by mass, and the coating amount (coating amount after drying) was 2.45 g / m ² .
As described above, a lithographic printing plate precursor was obtained.

<Developer>
The following components were dissolved in water, and a developer was prepared so that the pH became 12 with KOH.
New Coal B4SN (Nippon Emulsifier) 4% by mass
Olfin AK-02 (Nisshin Chemical) 0.05% by mass
Ethylenediaminetetraacetic acid, 4Na salt (chelating agent) 0.2% by mass
Potassium carbonate 0.2% by mass

<Washing liquid additive liquid>
5-Chloro-2-methyl-4-isothiazolin-one 5% by mass
2-Bromo-2-nitro-1,3-propanediol 5% by mass
Diethylenetriaminepenta (methylenephosphonic acid), 5Na salt 4% by mass
86% by weight of water

Example 1 The above-mentioned washing solution addition liquid was added at a rate of 2 cc / L to the washing solution before development and the washing solution after development.
Example 2: The above-mentioned washing solution addition solution was added to the washing solution before development and the washing solution after development at a rate of 7 cc / L.
Comparative Example 1: Processing was performed without adding anything to the pre-development washing solution and the post-development washing solution.

[Processing of plate material]
The obtained lithographic printing plate precursor was changed by 0.15 at log E in a range of resolution 175 lpi, external drum rotation speed 150 rpm, output 0-8 W in a Trendsetter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser. Exposed. In addition, after performing exposure on the conditions of 25 degreeC50% RH, it processed with the washing | cleaning liquid mentioned above (20 degreeC, 5 second), the overcoat layer was removed, and then Fuji Photo Film LP-1310NEWS was used, It developed with the developing solution of an Example at 30 degreeC for 12 second. After the development, it was treated with the above-described washing solution (20 ° C., 5 seconds), and then treated with a finisher. As the finisher, a 1: 1 water dilution of GN-2K manufactured by Fuji Film Co., Ltd. was used.

(Evaluation: Evaluation of wash rot and tank bottom sedimentation)
The above-mentioned coated photosensitive material is treated 50 m ² per day, and the number of days until the liquid needs to be changed due to generation of mold and bacteria in the washing solution (gel, mold, etc. adhere to the plate after treatment, The number of days until bubbles are overflowed and the normal treatment is practically impossible is evaluated. The longer the number of days, the more stable the liquid can be used.
Further, the state of the washing bath precipitation was examined. In the evaluation of precipitation, ○ indicates no precipitation, Δ indicates a slight amount of precipitation, and × indicates a large amount of precipitation.

Table 1 LP-1310NEWS Pre-development (pre) washing with water, post-development washing with water, observation of precipitation

  As can be seen from Table 1, when preservatives and chelating agents are added to the washing solution, the precipitation in the washing solution before development and in the washing solution after development is improved, and long-term use over a month without solution exchange. Became possible. Moreover, when the pre-development washing solution and the post-development washing solution were treated for 5 days and evaluated for precipitation, no precipitation occurred in any of the washing solutions of the present invention. On the other hand, precipitation has already occurred on the 5th day in the washing solution to which no preservative and chelating agent are added, and the number of days for replacement of the washing solution before development and the washing solution after development is as short as 5 days and 8 days, respectively. It was.

Claims (4)

  Lithographic printing in which a negative lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, an ethylenically unsaturated bond-containing monomer, a polymerization initiator, and a binder polymer formed on an aluminum support is image-exposed and then developed. A method for processing a plate, comprising: treating a lithographic printing plate image-exposed with a washing solution before and after the development; and the washing solution contains a preservative and a chelating agent. Processing method. The processing method of a lithographic printing plate according to claim 1, further comprising a protective layer on the photosensitive layer of the negative lithographic printing plate precursor. The lithographic printing plate treatment method according to claim 1 or 2, wherein the preservative contains at least one 4-isothiazolin-3-one compound. The processing method of a lithographic printing plate according to any one of claims 1 to 3, wherein the chelating agent is a compound containing two or more phosphonic acid groups.