JP5631666B2 - Planographic printing plate precursor and method for producing planographic printing plate precursor - Google Patents

Description

  The present invention relates to a lithographic printing plate precursor and a method for producing a lithographic printing plate precursor.

  Conventionally, PS plates having a configuration in which a lipophilic photosensitive resin layer is provided on a hydrophilic support are widely used as lithographic printing plate precursors. As the plate making method, a method of dissolving and removing a non-image part is usually mentioned after mask exposure (surface exposure) through a lith film. In recent years, digitization techniques that electronically process, store, and output image information using a computer have become widespread. Various new image output methods corresponding to such digitization techniques have come into practical use. As a result, computer-to-plate (CTP) technology that scans highly directional light such as laser light in accordance with digitized image information and directly produces printing plates without using a lithographic film is desired. Obtaining a lithographic printing plate precursor adapted to the above has become an important technical issue. Examples of such a lithographic printing plate precursor include lithographic printing plate precursors described in Patent Documents 1 to 3.

Japanese Patent Laid-Open No. 10-228109 Japanese Examined Patent Publication No. 7-103171 JP 11-38633 A

  In order to make it easy to confirm the formed image, the lithographic printing plate precursor generally contains a plate inspection agent (colorant, dye or pigment) in the image recording layer of the lithographic printing plate precursor. Among them, as a plate inspection agent to be contained in the image recording layer of a photopolymerization type lithographic printing plate precursor, a pigment is often used because it has an advantage of not inhibiting photopolymerization. In order to increase the dispersibility of the pigment, it is common to coat the pigment with a polymer (polymer pigment dispersant). However, when a conventional polymer dispersant is used, there is a problem that a fine residual film is generated in a non-image area after development due to natural aging of the lithographic printing plate precursor.

  An object of the present invention is to provide a lithographic printing plate precursor in which a minute residual film generated due to natural aging is suppressed, and a method for producing the lithographic printing plate precursor.

The above problems have been solved by the following means.
<1> A photosensitive layer containing (component f) an ionic polymerization initiator, (component a) a pigment, (component b) a pigment dispersant having a heterocyclic ring, and (component c) a pigment dispersant having a polar group. A lithographic printing plate precursor characterized by being provided on a support having a hydrophilic surface,
<2> The lithographic printing plate precursor as described in <1>, wherein the photosensitive layer further contains (Component d) a binder polymer, (Component e) a sensitizing dye, and (Component g) a radical polymerizable compound,
<3> The lithographic printing plate precursor as described in <1> or <2>, wherein component a is at least one selected from the group consisting of phthalocyanine pigments, dioxazine pigments, quinacridone pigments, and diketopyrrolopyrrole pigments ,
<4> The lithographic printing plate precursor as described in any one of <1> to <3>, wherein component b has at least one of the groups represented by formulas (b-2) to (b-4) ,

式（ｂ−２）〜式（ｂ−４）中、Ｘは、単結合、又は、アルキレン基、−Ｏ−、−Ｓ−、−ＮＲ^A−、若しくは、−Ｃ（＝Ｏ）−を表し、
Ｒ^Aは、水素原子、又は、アルキル基を表し、
Ｙ及びＺは、各々独立に、−Ｎ＝、−Ｎ（Ｒ^B）−、−Ｓ−、又は、−Ｏ−を表し、
Ｒ^Bは、水素原子、又は、アルキル基を表し、
少なくともＹ又はＺが、−Ｎ＝又は−Ｎ（Ｒ^B）−であり、
環Ａ、環Ｂ、環Ｃ及び環Ｄは、各々独立に、芳香環を表す。
＜５＞成分ｂが、式（Ａ−４）で表される基を有する、＜４＞に記載の平版印刷版原版、
＜６＞成分ｂが、重量平均分子量１，０００以上１００，０００以下のグラフト型高分子化合物である、＜１＞〜＜５＞いずれか１つに記載の平版印刷版原版、
＜７＞成分ｃの極性基が、塩基性基である、＜１＞〜＜６＞いずれか１つに記載の平版印刷版原版、
＜８＞成分ｃの極性基が、アミノ基である、＜１＞〜＜７＞いずれか１つに記載の平版印刷版原版、
＜９＞成分ｂ及び成分ｃの総重量に対する成分ｃの割合が１〜５０重量％である、＜１＞〜＜８＞いずれか１つに記載の平版印刷版原版、
＜１０＞成分ｆが、オニウム塩である、＜１＞〜＜９＞いずれか１つに記載の平版印刷版原版、
＜１１＞＜１＞〜＜１０＞いずれか１つに記載の感光層を構成する成分を含む組成物を支持体上に塗設する工程を含むことを特徴とする、平版印刷版原版の製造方法。

In the formulas (b-2) to (b-4), X represents a single bond, an alkylene group, —O—, —S—, —NR ^A —, or —C (═O) —. ,
R ^A represents a hydrogen atom or an alkyl group,
Y and Z each independently represent —N═, —N (R ^B ) —, —S—, or —O—;
R ^B represents a hydrogen atom or an alkyl group,
At least Y or Z is —N═ or —N (R ^B ) —,
Ring A, ring B, ring C and ring D each independently represent an aromatic ring.
<5> The lithographic printing plate precursor as described in <4>, wherein component b has a group represented by formula (A-4),
<6> The lithographic printing plate precursor as described in any one of <1> to <5>, wherein component b is a graft polymer compound having a weight average molecular weight of 1,000 or more and 100,000 or less,
<7> The lithographic printing plate precursor as described in any one of <1> to <6>, wherein the polar group of component c is a basic group,
<8> The lithographic printing plate precursor as described in any one of <1> to <7>, wherein the polar group of component c is an amino group,
<9> The lithographic printing plate precursor as described in any one of <1> to <8>, wherein the ratio of component c to the total weight of component b and component c is 1 to 50% by weight,
<10> The lithographic printing plate precursor as described in any one of <1> to <9>, wherein component f is an onium salt,
<11><1> to <10> Production of a lithographic printing plate precursor comprising a step of coating a composition containing a component constituting the photosensitive layer according to any one on a support. Method.

  According to the present invention, a lithographic printing plate precursor in which a minute residual film generated due to natural aging is suppressed is obtained, and a method for producing the lithographic printing plate precursor is also obtained.

It is a schematic block diagram which shows an example of the mechanical surface roughening apparatus used for preparation of the support body used for this invention. It is a graph which shows an example of the alternating waveform current waveform figure used for the electrochemical roughening process in preparation of the support body used for this invention.

The lithographic printing plate precursor of the present invention comprises (component f) an ionic polymerization initiator, (component a) a pigment, (component b) a pigment dispersant having a heterocyclic ring, and (component c) a pigment dispersant having a polar group. A photosensitive layer containing is provided on a support having a hydrophilic surface.
Hereinafter, the lithographic printing plate precursor according to the invention will be described in detail. In addition, description of “X to Y” representing a numerical range is synonymous with “X or more and Y or less”, and includes both ends of the numerical range.

(Component f) Ionic polymerization initiator The ionic polymerization initiator has a function of starting and advancing the curing reaction of the polymerizable compound described later. Component f is a thermal decomposition type radical generator that decomposes by heat to generate radicals, an electron transfer type radical generator that generates radicals by receiving excitation electrons of an infrared absorber, or an excited infrared absorber Electron transfer type radical generator that generates a radical by electron transfer to a substance, which generates radicals by applying energy (for example, heat or light), and any compound having an ionic structure can be used. May be. For example, onium salts and borate compounds are preferred, and these may be used in combination.

  The onium salt suitably used in the present invention is an onium salt represented by the following formulas (RI-I) to (RI-III).

In the formula (RI-I), Ar ₁₁ represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include an alkyl group having 1 to 12 carbon atoms and a carbon number. 1-12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1-C1 12 alkylamino groups, C1-C12 dialkylamino groups, C1-C12 alkylamide groups or arylamide groups, carbonyl groups, carboxy groups, cyano groups, sulfonyl groups, C1-C12 thioalkyl groups And a thioaryl group having 1 to 12 carbon atoms. Z ₁₁ ^- represents a monovalent anion, specifically a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion Is mentioned. Of these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion and sulfinate ion are preferable from the viewpoint of stability.

In the formula (RI-II), Ar ₂₁ and Ar ₂₂ each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include 1 to 1 carbon atoms. 12 alkyl groups, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, Halogen atom, C1-C12 alkylamino group, C1-C12 dialkylamino group, C1-C12 alkylamide group or arylamide group, carbonyl group, carboxy group, cyano group, sulfonyl group, carbon Examples thereof include a thioalkyl group having 1 to 12 carbon atoms and a thioaryl group having 1 to 12 carbon atoms.
Z ₂₁ ^- represents a monovalent anion. Specific examples include halide ions, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, thiosulfonate ions, sulfate ions, and carboxylate ions. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoint of stability and reactivity.

In the formula (RI-III), R ₃₁ , R ₃₂ and R ₃₃ are each independently an aryl group, alkyl group, alkenyl group or alkynyl group having 20 or less carbon atoms which may have 1 to 6 substituents. Represents. Among them, an aryl group is preferable from the viewpoint of reactivity and stability. Examples of the substituent include an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, C1-C12 aryloxy group, halogen atom, C1-C12 alkylamino group, C1-C12 dialkylamino group, C1-C12 alkylamide group or arylamide group, carbonyl group, carboxy group Group, a cyano group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms.
Z ₃₁ ^- represents a monovalent anion. Specific examples include halide ions, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, thiosulfonate ions, sulfate ions, and carboxylate ions. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoints of stability and reactivity. More preferred are the carboxylate ions described in JP-A No. 2001-343742, and particularly preferred are the carboxylate ions described in JP-A No. 2002-148790.

  In the present invention, a borate compound (organic boron salt) can also be suitably used as component f. Borate compounds that can be used as ionic polymerization initiators are described in paragraphs 0057 to 0064 of JP2009-168907A.

(Component a) Pigment The photosensitive layer contains a pigment for the purpose of coloring. As a result, it is possible to improve the so-called plate inspection properties such as the visibility of the image after plate making as a printing plate and the suitability of an image density measuring machine. Specific examples of the pigment are not limited in hue, but are black pigment, yellow pigment, magenta pigment, cyan pigment, orange pigment, brown pigment, red pigment, purple pigment, blue pigment, green pigment, fluorescent pigment. , Metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, disazo condensed pigments, disazo pigments, phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, aminoanthraquinone pigments, diketopyrrolopyrrole Pigments, perylene and perinone pigments, thioindigo pigments, indanthrone pigments, triarylcarbonium pigments, quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, isoindoline pigments, isoindolinone pigments, iso Biolantron pigments, pyranthrone pigments, quinophthalone pigments, benzimidazolone pigments, thioindigo pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, etc. It can be used.
Among them, the component a is preferably a dye selected from the group consisting of a phthalocyanine pigment, a dioxazine pigment, a quinacridone pigment, and a diketopyrrolopyrrole pigment.

The pigment is used for imparting visibility (plate inspection) of the original (character / picture) of the planographic printing plate after the exposure / development processing and before printing. In order to impart visibility, pigments that absorb light in a wavelength region of 500 nm or more, that is, magenta, red, cyan, blue, and green pigments are preferably used. On the contrary, for example, yellow that absorbs light only in a wavelength region of 500 nm or less is not suitable. The phthalocyanine pigments are blue, green, the dioxazine pigment is violet, the diketopyrrolopyrrole pigment is red, and the quinacridone pigment is magenta, both of which absorb light in the wavelength region of 500 nm or more, and are suitable for imparting visibility.
Examples of pigments include commercially available pigment and color index (CI) manuals, “Latest Pigment Handbook” (edited by the Japan Pigment Technology Association, published in 1977), “Latest Pigment Applied Technology” (published by CMC, published in 1986), “Printing” The pigments described in "Ink Technology", published by CMC Publishing, 1984) can be used.

  More specifically, for example, C.I. I. Pigment red 190 (C.I. No. 71140), C.I. I. Pigment red 224 (C.I. No. 71127), C.I. I. Perylene pigments such as CI Pigment Violet 29 (C.I. No. 71129); I. Pigment orange 43 (C.I. No. 71105), or C.I. I. Perinone pigments such as CI Pigment Red 194 (C.I. No. 71100); I. Pigment violet 19 (C.I. No. 73900), C.I. I. Pigment violet 42, C.I. I. Pigment red 122 (C.I. No. 73915), C.I. I. Pigment red 192, C.I. I. Pigment red 202 (C.I. No. 73907), C.I. I. Pigment red 207 (C.I. No. 73900, 73906), or C.I. I. Pigment Red 209 (C.I. No. 73905), a quinacridone pigment; I. Pigment red 206 (C.I. No. 73900/73920), C.I. I. Pigment orange 48 (C.I. No. 73900/73920), or C.I. I. Quinacridone quinone pigments such as CI Pigment Orange 49 (C.I. No. 73900/73920); I. Anthraquinone pigments such as C.I. Pigment Yellow 147 (C.I. No. 60645); I. Anthanthrone pigments such as CI Pigment Red 168 (C.I. No. 59300); I. Pigment brown 25 (C.I. No. 12510), C.I. I. Pigment violet 32 (C.I. No. 12517), C.I. I. Pigment yellow 180 (C.I. No. 21290), C.I. I. Pigment yellow 181 (C.I. No. 11777), C.I. I. Pigment orange 62 (C.I. No. 11775), or C.I. I. Benzimidazolone pigments such as CI Pigment Red 185 (C.I. No. 12516); I. Pigment yellow 93 (C.I. No. 20710), C.I. I. Pigment yellow 94 (C.I. No. 20038), C.I. I. Pigment yellow 95 (C.I. No. 20034), C.I. I. Pigment yellow 128 (C.I. No. 20037), C.I. I. Pigment yellow 166 (C.I. No. 20035), C.I. I. Pigment orange 34 (C.I. No. 21115), C.I. I. Pigment orange 13 (C.I. No. 21110), C.I. I. Pigment orange 31 (C.I. No. 20050), C.I. I. Pigment red 144 (C.I. No. 20735), C.I. I. Pigment red 166 (C.I. No. 20730), C.I. I. Pigment red 220 (C.I. No. 20055), C.I. I. Pigment red 221 (C.I. No. 20065), C.I. I. Pigment red 242 (C.I. No. 20067), C.I. I. Pigment red 248, C.I. I. Pigment red 262, or C.I. I. Disazo condensation pigments such as CI Pigment Brown 23 (C.I. No. 20060); I. Pigment yellow 13 (C.I. No. 21100), C.I. I. Pigment yellow 83 (C.I. No. 21108), or C.I. I. Disazo pigments such as CI Pigment Yellow 188 (C.I. No. 21094); I. Pigment red 187 (C.I. No. 12486), C.I. I. Pigment red 170 (C.I. No. 12475), C.I. I. Pigment yellow 74 (C.I. No. 11714), C.I. I. Pigment red 48 (C.I. No. 15865), C.I. I. Pigment red 53 (C.I. No. 15585), C.I. I. Pigment orange 64 (C.I. No. 12760), or C.I. I. Azo pigments such as CI Pigment Red 247 (C.I. No. 15915); I. Indanthrone pigments such as CI Pigment Blue 60 (C.I. No. 69800); I. Pigment green 7 (C.I. No. 74260), C.I. I. Pigment Green 36 (C.I. No. 74265), Pigment Green 37 (C.I. No. 74255), Pigment Blue 16 (C.I. No. 74100), C.I. I. Phthalocyanine pigments such as CI Pigment Blue 75 (C.I. No. 74160: 2) or 15 (C.I. No. 74160); I. Pigment blue 56 (C.I. No. 42800), or C.I. I. Triarylcarbonium pigments such as CI Pigment Blue 61 (C.I. No. 42765: 1); I. Pigment violet 23 (C.I. No. 51319), or C.I. I. Dioxazine pigments such as CI Pigment Violet 37 (C.I. No. 51345); I. Aminoanthraquinone pigments such as CI Pigment Red 177 (C.I. No. 65300); I. Pigment red 254 (C.I. No. 56110), C.I. I. Pigment Red 255 (C.I. No. 561050), C.I. I. Pigment red 264, C.I. I. Pigment red 272 (C.I. No. 561150), C.I. I. Pigment orange 71, or C.I. I. Diketopyrrolopyrrole pigments such as CI Pigment Orange 73; I. Thioindigo pigments such as CI Pigment Red 88 (C.I. No. 7313); I. Pigment yellow 139 (C.I. No. 56298), C.I. I. Pigment Orange 66 (C.I. No. 48210) and other isoindoline pigments; I. Pigment yellow 109 (C.I. No. 56284), or C.I. I. Pigment Orange 61 (C.I. No. 11295) and other isoindolinone pigments; I. Pigment orange 40 (C.I. No. 59700), or C.I. I. Pyranthrone pigments such as CI Pigment Red 216 (C.I. No. 59710); I. And isoviolanthrone pigments such as CI Pigment Violet 31 (60010).

  Of these, pigment blue 15 (C.I. No. 74160), C.I. I. Pigment violet 23 (C.I. No. 51319), C.I. I. Pigment red 254 (C.I. No. 56110), C.I. I. Pigment red 122 (C.I. No. 73915). These preferred pigments may be used alone or in combination of two or more.

In addition, in the range which does not impair the effect of this invention, dye can be used together. Specific examples of the dye include ethyl violet, crystal violet, azo dye, anthraquinone dye, and cyanine dye.
In addition to the above plate inspection properties, a dye having an absorption maximum in the range of 500 to 700 nm can also be used from the viewpoint of the polymerization inhibition effect. Examples of the dye include those described in paragraphs 0013 to 0017 of JP-A-2005-107389.

  The addition amount of the pigment (including the dye when used in combination) is preferably 0.5 to 15% by mass, more preferably 0.8 to 10% by mass with respect to the non-volatile components in the photosensitive layer. %, And more preferably 1.0 to 10% by mass.

  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. Is included. 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.

(Component b) Pigment dispersant having a heterocyclic ring The lithographic printing plate precursor according to the invention contains (Component b) a pigment dispersant having a heterocyclic ring in the photosensitive layer. By using the pigment dispersant of component b, it is possible to suppress the aging residual film generated in the non-image area, and this suppresses the adsorptivity to the aluminum support as compared with the conventional amine pigment dispersant. It is estimated that it was because. The pigment dispersant component b is preferably a polymer compound having a heterocyclic ring in the main chain or side chain, and more preferably a polymer compound having a heterocyclic ring in the side chain. Such a polymer compound is preferably a polymer containing a structural unit derived from a monomer represented by the formula (b-1), a maleimide, or a monomer comprising a maleimide derivative. It is more preferable that it is a polymer containing the structural unit derived from the monomer represented by (b-1).

（式（ｂ−１）中、Ｒ¹は、水素原子、又は、アルキル基を表し、Ｒ²は、単結合、又は、２価の連結基を表し、Ｙは、−ＣＯ−、−Ｃ（＝Ｏ）Ｏ−、−ＯＣ（＝Ｏ）−、−Ｃ（＝Ｏ）ＮＨ−、又は、フェニレン基を表し、Ｚは含窒素複素環を有する基を表す。）

(In Formula (b-1), R ¹ represents a hydrogen atom or an alkyl group, R ² represents a single bond or a divalent linking group, and Y represents —CO— or —C ( ═O) O—, —OC (═O) —, —C (═O) NH—, or a phenylene group, and Z represents a group having a nitrogen-containing heterocyclic ring.

R ¹ represents a hydrogen atom or an alkyl group. As said alkyl group, a C1-C12 alkyl group is preferable, a C1-C8 alkyl group is more preferable, and a C1-C4 alkyl group is still more preferable. When the alkyl group represented by R ¹ has a substituent, examples of the substituent include a hydroxy group and an alkoxy group (preferably having 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, still more preferably methoxy group). Group, ethoxy group), cyclohexyloxy group and the like.
Preferred alkyl groups represented by R ¹ include methyl group, ethyl group, propyl group, n-butyl group, i-butyl group, t-butyl group, n-hexyl group, cyclohexyl group, 2-hydroxyethyl group, A 3-hydroxypropyl group, a 2-hydroxypropyl group, and a 2-methoxyethyl group are exemplified, and among them, a hydrogen atom or a methyl group is more preferable.

Y represents ^* -C (= O)-, ^* -C (= O) O-, ^* -OC (= O)-, ^* -C (= O) NH-, or a phenylene group. In formula (b-1), Y is bonded to the carbon atom to which R ¹ is bonded on the side marked with ^* . Y is preferably ^* —C (═O) O— or a phenylene group.

R ² represents a single bond or a divalent linking group. Examples of the divalent linking group include an alkylene group, an arylene group, a thio group (—S—), an etheric oxygen atom (—O—), an ester bond (—C (═O) O— or —OC (═O). -), An amide bond (-C (= O) NH- or -NHC (= O)-), a ureylene group (-NHC (= O) NH-), and a group obtained by combining these.
In formula (b-1), the first divalent linking group bonded to Y is preferably a substituted or unsubstituted alkylene group or a thio bond (—S—). The alkylene group is preferably an alkylene group having 1 to 12 carbon atoms, more preferably an alkylene group having 1 to 12 carbon atoms, still more preferably an alkylene group having 1 to 8 carbon atoms, and an alkylene group having 1 to 4 carbon atoms. Particularly preferred are a methylene group, an ethylene group, a propylene group, a trimethylene group, and a tetramethylene group. When the alkylene group has a substituent, examples of the substituent include a hydroxy group.
Examples of the divalent linking group represented by R ² include a hetero atom (for example, an oxygen atom, a nitrogen atom, or a sulfur atom) or a hetero atom at the terminal opposite to the side bonded to Y of the alkylene group. What couple | bonds with the partial structure containing an atom is also preferable. Examples of the divalent linking group represented by R ² include —O—, —S—, —C (═O) O—, —C (═O) NH—, —C at the terminal of the above alkylene group. (═O) S—, —NH (═O) NH—, —NHC (═O) O—, —NHC (═O) S—, —OC (═O) —, —OC (═O) NH— And a hetero atom selected from -NHC (= O)-or a partial structure containing a hetero atom is preferred, and -O-, -NHC (= O) NH-, -NHC (= O) Those that bind to S- are more preferred. Moreover, what couple | bonds with Z through the partial structure containing this hetero atom or a hetero atom is preferable.

  Z represents a group having a heterocyclic structure. As the group having a heterocyclic structure, a group obtained by removing one hydrogen atom from a heterocyclic ring is preferable. Examples of the heterocyclic ring include phthalocyanine, insoluble azo, azo lake, anthraquinone, quinacridone, dioxazine, diketopyrrolopyrrole, anthrapyridine, ansanthrone, indanthrone, flavanthrone, perinone. Type, perylene type, thioindigo type dye structure, for example, thiophene, furan, xanthene, pyrrole, pyrroline, pyrrolidine, dioxolane, pyrazole, pyrazoline, pyrazolidine, imidazole, oxazole, thiazole, oxadiazole, triazole, thiadiazole, pyran, Pyridine, piperidine, dioxane, morpholine, pyridazine, pyrimidine, piperazine, triazine, trithiane, isoindoline, isoindolinone, benzimidazolone, benzothiazole Benzoxazole, succinimide, phthalimide, naphthalimide, hydantoin, indole, quinoline, carbazole, acridine, acridone, anthraquinone, pyrazine, tetrazole, phenothiazine, phenoxazine, phenothiazine, benzimidazole, benztriazole, naphthalenedicarboimide, cyclic amide And heterocyclic rings such as cyclic urea and cyclic imide. These heterocyclic rings may have a substituent. Examples of the substituent include an alkyl group, an aryl group, an alkoxy group, a halogen atom, an aliphatic ester group, an aromatic ester group, an alkoxycarbonyl group, Examples thereof include a 1,3-indandionyl group substituted with a halogen atom.

Z is preferably a group having a nitrogen-containing heterocycle having 6 or more carbon atoms, more preferably a group having a nitrogen-containing heterocycle having 6 to 18 carbon atoms, and 6 to 12 carbon atoms. A group having a nitrogen-containing heterocyclic ring is particularly preferred.
The group having a nitrogen-containing heterocyclic ring having 6 or more carbon atoms is preferably a structure represented by formula (b-2), formula (b-3) or formula (b-4).

（式（ｂ−２）〜式（ｂ−４）中、Ｘは、単結合、又は、アルキレン基、−Ｏ−、−Ｓ−、−ＮＲ^A−、若しくは、−Ｃ（＝Ｏ）−を表し、Ｒ^Aは、水素原子、又は、アルキル基を表し、Ｙ及びＺは、各々独立に、−Ｎ＝、−Ｎ（Ｒ^B）−、−Ｓ−、又は、−Ｏ−を表し、Ｒ^Bは、水素原子、又は、アルキル基を表し、少なくともＹ又はＺが、−Ｎ＝又は−Ｎ（Ｒ^B）−であり、環Ａ、環Ｂ、環Ｃ及び環Ｄは、各々独立に、芳香環を表す。）

(In the formulas (b-2) to (b-4), X represents a single bond or an alkylene group, —O—, —S—, —NR ^A —, or —C (═O) —. R ^A represents a hydrogen atom or an alkyl group, Y and Z each independently represent —N═, —N (R ^B ) —, —S—, or —O—, R ^B represents a hydrogen atom or an alkyl group, at least Y or Z is —N═ or —N (R ^B ) —, and ring A, ring B, ring C and ring D are each independently Represents an aromatic ring.)

In ^{* at} the upper part of Formula (b-2) to Formula (b-4), it is preferable to bind to R ² in Formula (b-1).
X represents a single bond, an alkylene group (for example, a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, etc.), -O-, -S-, -NR ^A- , and -C (= O). -Represents any group selected from the group consisting of Here, R ^A represents a hydrogen atom or an alkyl group. When R ^A represents an alkyl group, the alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, or an n-propyl group. I-propyl group, n-butyl group, t-butyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-octadecyl group and the like. Among these, as X, a single bond, a methylene group, —O—, or —C (═O) — is preferable, and —C (═O) — is particularly preferable.

Y and Z each independently represent —N═, —NH—, —N (R ^B ) —, —S—, or —O—, and at least Y or Z represents —N═ or —N ( R ^B ) —. R ^B represents a hydrogen atom or an alkyl group, and when R ^B represents an alkyl group, the alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. Yes, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, t-butyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-octadecyl group, etc. Is mentioned. Among these, as Y and Z, —N═, —NH—, and —N (R ^B ) — are particularly preferable. As a combination of Y and Z, a combination in which one of Y and Z is —N═ and the other is —NH— is preferable. As group represented by a formula (A-3), an imidazolyl group is mentioned preferably.

  Ring A, ring B, ring C, and ring D each independently represent an aromatic ring. Examples of the aromatic ring include a benzene ring, naphthalene ring, indene ring, azulene ring, fluorene ring, anthracene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyrrole ring, imidazole ring, indole ring, quinoline ring, acridine ring, Examples include phenothiazine ring, phenoxazine ring, acridone ring, anthraquinone ring, among others, benzene ring, naphthalene ring, anthracene ring, pyridine ring, phenoxazine ring, acridine ring, phenothiazine ring, phenoxazine ring, acridone ring, anthraquinone ring Are preferable, and a benzene ring, a naphthalene ring, and a pyridine ring are particularly preferable.

  Preferred examples of ring A and ring B in formula (b-2) include a benzene ring, a naphthalene ring, a pyridine ring, a pyrazine ring, and the like. Preferred examples of ring C in formula (b-3) include a benzene ring, naphthalene ring, pyridine ring, pyrazine ring and the like. Preferred examples of ring D in formula (b-4) include a benzene ring, naphthalene ring, pyridine ring, pyrazine ring and the like. Among these, from the viewpoint of dispersibility and stability over time of the dispersion, a benzene ring and a naphthalene ring are more preferable. In the formula (b-2) or the formula (b-4), a benzene ring is more preferable, and the formula (b In 3), a naphthalene ring is more preferable.

  Further, among the formulas (b-2), (b-3), and (b-4), the structure represented by the formula (b-4) is more preferable.

  Preferred examples of the group represented by the formula (b-2) include a group in which one hydrogen atom is extracted from carbazole, acridone, phenoxazine, or phenothiazine. Preferred examples of the group represented by the formula (b-3) include a group obtained by extracting one hydrogen atom from phthalimide, naphthalimide, and naphthalenedicarboimide. Preferred examples of the group represented by the formula (b-4) include a group in which one hydrogen atom has been extracted from benzimidazole, benzothiazole, or benzoxazole.

  Examples of the maleimide derivative include N-alkylmaleimide having an alkyl group having 1 to 3 carbon atoms and N-arylmaleimide having an aryl group having 6 to 12 carbon atoms. Specifically, N-methylmaleimide, N- Phenylmaleimide is preferred.

  Preferred specific examples of the monomer represented by the formula (b-1), maleimide, and maleimide derivatives are listed below, but the present invention is not limited thereto.

  Component b may contain only one type of structural unit derived from the monomer represented by formula (b-1), maleimide, or maleimide derivative, or may contain two or more types.

  In component b, the content of the structural unit derived from the monomer represented by formula (b-1), maleimide, or maleimide derivative is not particularly limited, but 100 mass of all structural units contained in component b. %, The structural unit derived from the monomer represented by the formula (b-1), maleimide, or maleimide derivative is preferably contained in an amount of 5% by mass or more, more preferably 5 to 50% by mass. The content is preferably 10 to 20% by mass. Among the monomer represented by formula (b-1), maleimide, and maleimide derivatives, the monomer represented by formula (b-1) is preferable because of its high adsorptivity to the pigment.

  Component b is a graft-type polymer compound (graft polymer), that is, a polymer compound having a structure in which a side chain (branch chain) having a predetermined molecular weight is bonded to a main chain (trunk chain). preferable.

The main chain of component b includes structural units derived from the monomer represented by the formula (b-1), maleimide, and maleimide derivatives, and includes structural units derived from macromonomers described later and acidic groups described later. It is preferable to have a structural unit.
Preferred examples of the side chain of the polymer pigment dispersant having a heterocyclic ring include those composed of polystyrene, polyethylene oxide, polypropylene oxide, poly (meth) acrylic acid ester, polycaprolactone, polyurethane, polyamide, polyester, and the like. . In the present invention, when referring to either or both of “acryl” and “methacryl”, they are also described as “(meth) acryl” or the like.

  As long as the graft polymer compound has a side chain structure, the main chain and the side chain may be formed of the same polymer species, or may be different from each other. The main chain and the side chain can contain various partial structures depending on the purpose. For example, by introducing a functional group having excellent pigment adsorptivity to the main chain, the adsorptivity of component b to the pigment surface can be further improved.

  When synthesizing component b, the copolymerization of a polymerizable oligomer having an ethylenically unsaturated bond at the terminal together with the monomer forming the main chain controls the chain length and properties of the introduced side chain, and provides the pigment. It is preferable from the viewpoint of obtaining a component b having excellent adsorptivity and excellent stability over time.

The polymerizable oligomer having an ethylenically unsaturated bond at the terminal, which is useful for forming a side chain, is also called a macromonomer because it is a compound having a predetermined molecular weight. In the following description, the “polymerizable oligomer having an ethylenically unsaturated bond at the terminal” in the present invention may be appropriately referred to as “polymerizable oligomer” or “macromonomer”.
The polymerizable oligomer optionally used in the present invention has a polymerizable functional group portion having an oligomer chain portion and a terminal ethylenically unsaturated bond. It is preferable to have such a group having an ethylenically unsaturated bond only at one end of the oligomer chain from the viewpoint of obtaining a desired graft polymer compound. As the group having an ethylenically unsaturated bond, a (meth) acryloyl group and a vinyl group are preferable, and a (meth) acryloyl group is particularly preferable.

  The macromonomer used for the synthesis of component b preferably has a polystyrene-equivalent number average molecular weight (Mn) in the range of 500 to 10,000, and more preferably in the range of 1,000 to 9,000.

The part of the oligomer chain in the macromonomer is alkyl (meth) acrylate, (meth) acrylamide, N-alkyl (meth) acrylamide, N, N′-dialkyl (meth) acrylamide, styrene, (meth) acrylonitrile, vinyl acetate, and Further, it may be a homopolymer or copolymer formed from at least one monomer selected from the group consisting of butadiene, or polyethylene oxide, polypropylene oxide, or polycaprolactone.
These oligomer chains may further have a substituent. Examples of the substituent that can be introduced include a halogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group, and a carbamoyl group. Is mentioned.

  In addition, specific examples of the alkyl group in the alkyl (meth) acrylate, N-alkyl (meth) acrylamide, etc. that form the polymer chain include an alkyl group or a substituted alkyl group, such as a methyl group, an ethyl group, Propyl group, butyl group, heptyl group, hexyl group, octyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, hexadecyl group, octadecyl group, 2-chloroethyl group, 2-bromoethyl group, 2-methoxycarbonylethyl group, 2-methoxyethyl group, 2-bromopropyl group, 2-butenyl group, 2-pentenyl group, 3-methyl-2-pentenyl group, 2-hexenyl group, 4-methyl-2-hexenyl group, benzyl group, phenethyl group 3-phenylpropyl group, naphthylmethyl group, 2-naphthylethyl group, chloroben Group, bromobenzyl group, methylbenzyl group, ethylbenzyl group, methoxybenzyl group, dimethylbenzyl group, dimethoxybenzyl group, cyclohexyl group, 2-cyclohexylethyl group, 2-cyclopentylethyl group, bicyclo [3.2.1] Examples include oct-2-yl group, 1-adamantyl group, dimethylaminopropyl group, acetylaminoethyl group, N, N-dibutylaminocarbamoylmethyl group and the like. Of these alkyl groups, an unsubstituted alkyl group, or an alkyl group substituted with a halogen atom, an aryl group, or a hydroxyl group is preferred, and an unsubstituted alkyl group is particularly preferred.

Among these oligomer chains, from the viewpoints of dispersion stability and developability of component b, unsubstituted or substituted hydroxyl group, alkyl (meth) acrylate having 1 to 4 carbon atoms, (meth) acrylamide, N-alkyl (meth) acrylamide having an unsubstituted or substituted alkyl group having 1 to 4 carbon atoms, N, N′-dialkyl (meth) acrylamide having an unsubstituted or substituted alkyl group having 1 to 4 carbon atoms , A homopolymer formed from at least one monomer selected from the group consisting of unsubstituted or substituted styrene having an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and (meth) acrylonitrile Alternatively, a copolymer, polycaprolactone, polyethylene oxide, and polypropylene oxide are preferable, and unsubstituted or substituted. Alkyl (meth) acrylate having a hydroxyl group and an alkoxy group having 1 to 4 carbon atoms as a substituent, N, N′-dialkyl (meth) acrylamide having an alkyl group having 1 to 4 carbon atoms as an unsubstituted or substituted group, unsubstituted Or the homopolymer or copolymer formed from the styrene which has a C1-C4 alkoxy group as a substituent, the at least 1 type of monomer chosen from the group which consists of (meth) acrylonitrile, and a polycaprolactone are especially preferable.
As a macromonomer useful for synthesizing component b, a macromonomer represented by the formula (b-5) is preferably exemplified.

In formula (b-5), R ¹¹ and R ¹³ each independently represent a hydrogen atom or a methyl group, R ¹² represents a linking group containing an alkylene group having 1 to 12 carbon atoms, and Y ¹¹ represents phenyl. group, -COOR ^14, cyano group, or an -CONR ¹⁵ R ^16, R ¹⁴ represents an alkyl group, a phenyl group or an or arylalkyl group having 7 to 10 carbon atoms having 1 to 12 carbon atoms, R ¹⁵ And R ¹⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and q represents an integer of 10 to 200.

R ¹² represents a linking group containing an alkylene group having 1 to ¹² carbon atoms, and the linking group may be an alkylene group having 1 to 12 carbon atoms, or a plurality of the alkylene groups may be ester bonds or ethers. It may be linked via a bond, an amide bond or the like. The alkylene group for R ¹² is preferably an alkylene group having 2 to 4 carbon atoms. The alkylene group for R ¹² may further have a substituent such as a hydroxyl group or an alkoxy group.
Y ¹¹ represents an optionally substituted phenyl group, —COOR ¹⁴ , a cyano group, or —CONR ¹⁵ R ¹⁶ . Here, R ¹⁴ represents an alkyl group having 1 to 12 carbon atoms, a phenyl group, or an arylalkyl group having 7 to 10 carbon atoms. R ¹⁵ and R ¹⁶ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. When R ¹⁴ , R ¹⁵ , R ¹⁶ , and Y ¹¹ represent an alkyl group or a phenyl group, these may further have a substituent. Examples of the substituent that can be introduced here include a hydroxyl group, an alkoxy group, A halogen atom is mentioned. Y ¹¹ is preferably a phenyl group, a cyano group or —COOR ¹⁴ , wherein R ¹⁴ represents an alkyl group having 1 to 12 carbon atoms. Y ¹¹ is most preferably —COOR ¹⁴ or a cyano group from the viewpoints of dispersion stability and developability.

In the macromonomer represented by the formula (b-5), q units may be linked to only one type, or may be a copolymer containing two or more types of structural units. , R ¹³ and Y ¹¹ may be present in two or more different from each other.

Specific examples of the polymerizable oligomer include 2-hydroxyethyl (meth) acrylate, styrene, methyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, (meth) acrylonitrile, acetoacetoxy Ethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-methoxyethoxyethyl (meth) acrylate, (meth) acrylamide, homopolymer of N, N′-dimethyl (meth) acrylamide or a copolymer thereof And a structure containing (meth) acryloyl group (H ₂ C═C (R ¹¹ ) C (═O) O—R ¹² —S— in formula (b-5)) is bonded to one end of the oligomer. Suitable macromonomers are mentioned.

The above-mentioned polymerizable oligomer may be a commercially available product or may be appropriately synthesized. Examples of the commercially available product include a one-end methacryloylated polystyrene oligomer (Mn = 6,000, trade name: AS -6, manufactured by Toagosei Co., Ltd.), one-end methacryloylated polymethyl methacrylate oligomer (Mn = 6,000, trade name: AA-6, manufactured by Toagosei Co., Ltd.), one-end methacryloylated poly-n-butyl Acrylate oligomer (Mn = 6,000, trade name: AB-6, manufactured by Toagosei Co., Ltd.), one-end methacryloylated polymethyl methacrylate / 2-hydroxyethyl methacrylate oligomer (Mn = 7,000, trade name: AA- 714, manufactured by Toagosei Co., Ltd.), one-end methacryloylated polybutyl methacrylate / 2-hydroxyethyl meta Relate oligomer (Mn = 7,000, trade name: 707S, manufactured by Toagosei Co., Ltd.), one-terminal methacryloylated poly 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate oligomer (Mn = 7,000, trade name: AY-) 707S, AY-714S, manufactured by Toagosei Co., Ltd.).
Component b may contain only one type of structural unit derived from the polymerizable oligomer, or may contain two or more types.

  The content of the structural unit derived from the macromonomer in component b is preferably 20 to 80% by mass, more preferably 40 to 80% by mass, with 100% by mass of all the structural units contained in component b.

Component b preferably has an acidic group in order to improve the development removability of the unexposed area. For this reason, it is preferable to copolymerize the monomer which has an acidic group in the case of the synthesis | combination of the component b.
Preferred examples of the “acidic group” include a carboxylic acid group, a sulfonic acid group, a monosulfate group, a phosphoric acid group, a monophosphate group, and a boric acid group. Sulfuric acid ester groups, phosphoric acid groups, and monophosphoric acid ester groups are more preferable, and carboxylic acid groups, sulfonic acid groups, and phosphoric acid groups are particularly preferable.
As an example of the monomer which has an acidic group which can be used for a synthesis | combination, the ethylenically unsaturated compound which has a carboxy group, and the ethylenically unsaturated compound which has a sulfonic acid group are mentioned.
Examples of the vinyl monomer having a carboxy group include (meth) acrylic acid, vinyl benzoic acid, maleic acid, maleic acid monoalkyl ester, fumaric acid, itaconic acid, crotonic acid, cinnamic acid, and acrylic acid dimer. Further, addition reaction product of a monomer having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate and a cyclic anhydride such as maleic anhydride, phthalic anhydride, or cyclohexanedicarboxylic anhydride, ω-carboxy-polycaprolactone Mono (meth) acrylates can also be used. Moreover, you may use anhydride containing monomers, such as maleic anhydride, itaconic anhydride, and citraconic anhydride, as a precursor of a carboxy group. Among these, (meth) acrylic acid is particularly preferable from the viewpoints of copolymerizability, cost, solubility, and the like.
Examples of the ethylenically unsaturated compound having a sulfonic acid group include 2-acrylamido-2-methylpropanesulfonic acid. Examples of the ethylenically unsaturated compound having a phosphoric acid group include mono (2-acryloyloxyethyl phosphate). Ester), mono (1-methyl-2-acryloyloxyethyl ester) phosphate, and the like.
Component b may contain only one type of structural unit derived from a monomer having an acidic group, or may contain two or more types.

  As content of the acidic group in the component b, it is preferable to include an acid group typified by a carboxy group in a range of 50 mgKOH / g to 200 mgKOH / g.

  A preferred embodiment of component b includes a structural unit derived from the monomer represented by the formula (b-1), maleimide, maleimide derivative, and structural unit derived from the macromonomer, more preferably It is an embodiment including a structural unit derived from a monomer having an acidic group.

The weight average molecular weight (Mw) of the component b is preferably 1,000 to 100,000, more preferably 10,000 to 50,000, and still more preferably 10,000 to 30,000.
In addition, the number average molecular weight (Mn) of component b is preferably 2,500 to 50,000, more preferably 5,000 to 30,000, and still more preferably 5,000 to 15,000.
Component b is preferably a graft polymer compound having a weight average molecular weight of 1,000 or more and 100,000 or less.

  The amount of component b added is not particularly limited, but is preferably in the range of 1 to 200 parts by weight, more preferably in the range of 5 to 150 parts by weight, and particularly preferably 15 to 150 parts by weight with respect to 100 parts by weight of the pigment particles. The range is 75 parts by mass. By setting it as the said range, it is favorable from a viewpoint of the hardness of a image part, a sensitivity, and printing durability, and the aggregation sedimentation of a pigment particle is suppressed.

(Component c) Pigment dispersant having a polar group In the lithographic printing plate precursor according to the invention, (Component a) has a heterocyclic ring in order to stably disperse the (Component a) pigment in the coating liquid used for the production thereof. (Component c) A pigment dispersant having a polar group is used in combination with the pigment dispersant.
The pigment dispersant having a polar group used in the present invention is preferably a compound having a polar group such as a compound having an amino group, a compound having a carboxylic acid group, a compound having a sulfonic acid group, or a compound having a phosphoric acid group. . The negative photosensitive layer for infrared laser is a high-polarity compound such as onium salt as the polymerization initiator, and the hydrophilic property (dissolves the polymerization initiator and others) and the hydrophobic property (dissolves the binder) as the coating solution solvent. The solvent is used. In order to stably disperse the pigment particles in such a solvent, a dispersant having both a polar repulsion function and a hydrophobic steric repulsion function is essential, compared to a conventional dispersant having only a hydrophobic steric repulsion function. is there. Examples of the group having a polar repulsion function include a polar group, and it is preferable to use a compound having the above polar group.
The polar group of the dispersant having a polar group used in the present invention is preferably a basic group such as an amino group or an ammonium group, and more preferably an amino group.

  In the lithographic printing plate precursor according to the invention, the component c is used in combination because the pigment cannot be stably dispersed in the coating solution only with the dispersant of the component b that brings about a residual film suppressing effect. However, since a large amount of component c causes adsorption to the aluminum support and failure of the remaining film occurs, the combined ratio of the two components becomes important.

When the preferable range of the blending ratio of component b and component c is described, the ratio of component c to the total weight of (component b) a polymer pigment dispersant having a heterocyclic ring and (component c) a pigment dispersant having a polar group is It is preferably 1 to 50% by weight, more preferably 3 to 30% by weight, and most preferably 5 to 20% by weight.
The pigment dispersion of the present invention is preferably used by mixing (component b) a polymer pigment dispersant having a heterocyclic ring and (component c) a pigment dispersant having a polar group. Two or more pigment dispersants to be mixed may be used, and the pigment dispersant species to be used is preferably 2 to 10 species, and more preferably 2 to 4 species.

  Examples of the dispersion solvent that can be used in the preparation of the pigment dispersion in the present invention include, for example, alcohol solvents, ketone solvents, ether solvents, aromatic solvents, carbon disulfide, aliphatic solvents, nitrile solvents, Examples thereof include sulfoxide solvents, halogen solvents, ester solvents, ionic solvents, and mixed solvents thereof. These solvents may be used by mixing with an aqueous solvent (for example, water or a solution mainly composed of water such as an aqueous solution of hydrochloric acid, an aqueous solution of sodium hydroxide, or an aqueous solution in which a surfactant is dissolved).

The photosensitive layer of the lithographic printing plate precursor according to the invention preferably contains the pigment as a pigment dispersion. The method for preparing the pigment dispersion may be a known method, for example, a pigment dispersant used as desired for the pigment. And a part of the mixed solvent, kneaded well, and then the remaining solvent is added and dispersed.
As a method for dispersing the pigment in the mixed solvent, a known dispersion technique used for 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).

  The weight average particle diameter of the pigment is preferably 0.01 to 10 μm, more preferably 0.05 to 1 μm, and still more preferably 0.1 to 1 μm. Within this preferred particle size range, excellent dispersion stability of the pigment in the photosensitive layer can be obtained, and a uniform photosensitive layer can be obtained.

  A pigment dispersion using a polymer pigment dispersant having a heterocyclic ring can be contained in a negative-type or positive-type photosensitive layer, and is particularly preferably contained in a negative-type photosensitive layer.

In the photosensitive layer of the lithographic printing plate precursor according to the invention, in addition to the ionic polymerization initiator of component f and components a to c, (component d) binder polymer, (component e) sensitizing dye, and ( It is preferable to further contain component g) a radical polymerizable compound.
Hereinafter, these optional component d, component e, and component g will be sequentially described.

(Component d) Binder polymer The photosensitive layer in the lithographic printing plate precursor according to the invention preferably contains a binder polymer.
The chemical structure of the binder polymer that can be used in the present invention is not particularly limited, but is preferably an organic polymer having an acid group from the viewpoint of solubility in an alkaline processing liquid, that is, developability, and particularly a carboxylic acid or a salt thereof. The organic polymer to contain is more preferable.
Examples of the binder polymer that can be used in the present invention include carboxylic acid-containing alkaline water-soluble or swellable organic polymers. Examples of such organic polymers include addition polymers having a carboxylic acid group in the side chain, such as JP-A-59-44615, JP-B-54-34327, JP-B-58-12777, and JP-B-54-25957. , JP-A-54-92723, JP-A-59-53836, JP-A-59-71048, ie, methacrylic acid copolymer, acrylic acid copolymer, itacon Acid copolymers, crotonic acid copolymers, maleic acid copolymers, partially esterified maleic acid copolymers and the like are useful. As the binder polymer, a copolymer containing a monomer unit derived from a (meth) acrylic acid ester containing a carboxylic acid (salt) group is preferable.
Also useful are acidic cellulose derivatives having a carboxylic acid group in the side chain and those obtained by adding a cyclic acid anhydride to an addition polymer having a hydroxy group. Further, Japanese Patent Publication Nos. 7-120040, 7-120041, 7-120042, 8-12424, JP-A 63-287944, JP-A 63-287947, JP-A 1-1-2 Polyurethane resins described in JP-A Nos. 271741 and 11-352691 are also useful as alkaline water-soluble or swellable binders. As the binder polymer that can be used in the present invention, an acrylic resin, a methacrylic resin, or a urethane resin is preferably used.

  An example of a material suitable as a binder polymer that can be used in the present invention is a copolymer having (a) a monomer unit containing a carboxylic acid group (including a salt thereof) and (b) a monomer unit imparting radical crosslinkability. It is a polymer.

(A) Although it does not specifically limit as a monomer unit containing a carboxylic acid group, The structure of Paragraph 0059-0075 of Unexamined-Japanese-Patent No. 2002-40652 and Unexamined-Japanese-Patent No. 2005-300650 is used preferably.
(B) Although it does not specifically limit as a monomer unit which provides radical crosslinkability, The structure as described in Paragraph 0041-0053 of Unexamined-Japanese-Patent No. 2007-248863 is used preferably.

The binder polymer that can be used in the present invention includes a monomer unit derived from an ethylenically unsaturated compound that does not include (a) a monomer unit containing a carboxylic acid group and (b) a monomer unit imparting radical crosslinkability. You may have as a polymerization component.
As such a monomer unit, a monomer unit derived from (meth) acrylic acid ester or (meth) acrylic acid amide is preferable. In particular, a monomer unit derived from an amide group (meth) acrylic acid amide described in paragraphs 0061 to 0084 of JP-A-2007-272134 is preferably used. The content of this monomer is preferably 5 to 50 units, more preferably 5 to 35 units, even more preferably 5 to 25 units, when the total number of monomer units is 100. .

  In the photosensitive layer according to the invention, a urethane resin having a crosslinkable group in the side chain can be used as the binder polymer in addition to the addition polymer having the above-mentioned combination of monomer units. Here, the crosslinkable group is a group capable of crosslinking the binder polymer by a chemical reaction that occurs in the image forming layer when the lithographic printing plate precursor is exposed. The chemical structure is not particularly limited as long as it has such a function. For example, an ethylenically unsaturated group is preferable as a functional group capable of addition polymerization. Moreover, the functional group described in Paragraphs 0130 to 0139 of Unexamined-Japanese-Patent No. 2007-17948 can be illustrated.

  The polyurethane resin having a crosslinkable group in the side chain particularly preferably used in the present invention comprises (i) a diisocyanate compound, (ii) a diol compound having a carboxy group, (iii) a diisocyanate compound having a crosslinkable group, and If present, it can be obtained by polyaddition reaction of (iv) a diol compound having no carboxy group and (v) a compound having an amino group.

  Examples of the compounds (i), (ii) and (iii) include formulas (4) to (10) and specific examples described in paragraphs 0142 to 0167 of JP-A No. 2007-17948. The compound of (iv) includes the general formula (A ′), formulas (a) to (e), formulas (11) to (22) and specific examples described in paragraphs 0180 to 0225 of JP-A No. 2007-17948. Compounds. Examples of the compound (v) include Formula (31) and Formula (32) described in paragraphs 0227 to 0230 of JP-A No. 2007-17948 and specific compounds. In addition to the above-described polyurethane resin, a polyurethane resin obtained by introducing a crosslinkable group into a polyurethane having a carboxyl group as described in JP-A-2003-270775 by a polymer reaction can also be exemplified.

  In order to maintain the developability of the photosensitive layer, the binder polymer used preferably has an appropriate molecular weight, more preferably a weight average molecular weight of 5,000 to 300,000, and 20,000 to More preferably, it is 150,000.

  These binder polymers can be contained in an arbitrary amount in the photosensitive layer, and the content of the binder polymer in the photosensitive layer is preferably 10 to 90% by mass, and 30 to 80% by mass. More preferably.

(Component e) Sensitizing dye The photosensitive layer in the lithographic printing plate precursor according to the invention preferably contains a sensitizing dye. There is no restriction | limiting in particular as a sensitizing dye which can be used for this invention, A well-known sensitizing dye can be used. For example, by adding a sensitizing dye having a maximum absorption at 300 to 450 nm, a sensitizing dye having a maximum absorption at 500 to 600 nm, and a sensitizing dye (infrared absorber) having a maximum absorption at 750 to 1,400 nm. , A high-sensitivity lithographic printing plate precursor corresponding to a 405 nm violet laser, a 532 nm green laser, and a 830 nm IR laser, which are usually used in the industry, can be provided.

  The sensitizing dye having a maximum absorption at 750 to 1,400 nm that is preferably used in the present invention will be described in detail. In the present invention, the “sensitizing dye having maximum absorption at 750 to 1,400 nm” is also referred to as “infrared absorber”. The infrared absorber is preferably a dye or pigment having an absorption maximum at a wavelength of 750 to 1,400 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. Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferred, and particularly preferred examples include cyanine dyes represented by the following formula (a).

In the 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 carbon atom containing a hetero atom. Represents a hydrocarbon group of ˜12. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. X _a ^- is Z _a which will be described below ^- has the same definition as, 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. Ph represents a phenyl group.

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the photosensitive 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 also preferable to form a 6-membered ring.

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

  Other infrared absorbers include paragraphs 0013 to 0035 of JP-A-2002-40638, paragraphs 0231 to 0260 of JP-A-2005-91617, paragraphs 0145 to 0173 of JP-A-2005-250158, and JP-A 2007. Those described in paragraphs 0275 to 0304 of JP-47742, paragraphs 0115 to 0124 of JP 2007-249036, and paragraphs 0116 to 0145 of JP 2008-242093 can be preferably used.

Next, a sensitizing dye having a maximum absorption in the wavelength region of 300 to 450 nm will be described.
Examples of such a sensitizing dye include merocyanine dyes, benzopyrans, coumarins, aromatic ketones, anthracenes, and the like.
Of the sensitizing dyes having an absorption maximum in the wavelength range of 300 nm to 450 nm, a dye more preferable from the viewpoint of high sensitivity is a dye represented by the following formula (IX).

（式（ＩＸ）中、Ａは置換基を有してもよい芳香族環基又はヘテロ環基を表し、Ｘは酸素原子、硫黄原子又はＮＲ₃を表す。Ｒ₁、Ｒ₂及びＲ₃は、それぞれ独立に、一価の非金属原子団を表し、ＡとＲ₁及びＲ₂とＲ₃はそれぞれ互いに結合して、脂肪族性又は芳香族性の環を形成してもよい。）

(In the formula (IX), A represents an aromatic ring group or a heterocyclic group which may have a substituent, X represents an oxygen atom, a sulfur atom or NR _3. R ₁ , R ₂ and R ₃ represent Each independently represents a monovalent non-metallic atomic group, and A and R ₁ and R ₂ and R ₃ may be bonded to each other to form an aliphatic or aromatic ring.)

R ₁ , R ₂ and R ₃ each independently represents a monovalent non-metallic atomic group, preferably a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, It represents a substituted or unsubstituted aromatic heterocyclic residue, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a hydroxy group, or a halogen atom.

Next, A in Formula (IX) represents an aromatic ring group or a heterocyclic group which may have a substituent, and specific examples of the aromatic ring or heterocyclic ring which may have a substituent include The thing similar to what was described by R < ₁ >, R < ₂ > and R < ₃ > in Formula (IX) is mentioned.

As specific examples of such a sensitizing dye, compounds described in paragraphs 0047 to 0053 of JP-A-2007-58170 are preferably used.
Furthermore, paragraphs 0178 to 0230 of JP 2005-91617 A, paragraphs 0202 to 0250 of JP 2005-250438 A, paragraphs 0170 to 0176 of JP 2005-300817 A, paragraphs of JP 2007-17948 A. 0058 to 0081, paragraphs 0230 to 0265 of JP 2007-47742 A, paragraphs 0033 to 0036 of JP 2007-171406 A, paragraphs 0023 to 0055 of JP 2007-206216 A, JP 2007-225701 A. Paragraphs 0018 to 0037, paragraphs 0208 to 0243 of JP 2007-248863, paragraphs 0077 to 0112 of JP 2007-249036, paragraphs 0037 to 0046 of JP 2007-316582, and JP 2007-328243. issue It can also be preferably used sensitizing dyes described in broadcast paragraph 0027-0113.

These sensitizing dyes may be added to the same photosensitive layer as other components, or may be added to another photosensitive layer.
The content of these sensitizing dyes in the photosensitive layer is 0.01 to 50% by mass with respect to the total solid content constituting the photosensitive layer from the viewpoint of uniformity in the photosensitive layer and durability of the photosensitive layer. It is preferably 0.1 to 10% by mass, more preferably 0.5 to 10% by mass.

(Component g) Radical polymerizable compound The photosensitive layer in the lithographic printing plate precursor according to the invention preferably contains a polymerizable compound.
The polymerizable compound that can be used in the photosensitive layer in the invention is a compound having at least one ethylenically unsaturated group (also referred to as “ethylenically unsaturated compound”), and has at least a terminal ethylenically unsaturated bond. It is selected from compounds having 1, preferably 2 or more, more preferably 2 having. Such a compound group is widely known in the industrial field, and in the present invention, these can be used without any particular limitation.
Examples of ethylenically unsaturated compounds include unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof, preferably An ester of an unsaturated carboxylic acid and an alcohol compound and an amide of an unsaturated carboxylic acid and an amine compound are used.
Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxy group, an amino group or a 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 isocyanate group, an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group, and a monofunctional or polyfunctional alcohol, amine or thiol, further a halogeno group or 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.

  Examples of unsaturated carboxylic acid esters include aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, and JP-A-59. Those having an aromatic skeleton described in JP-A No. 5241 and JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used. Furthermore, the ester monomers described above can also be used as a mixture.

  Examples of amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

  Further, 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, vinyl urethane compounds described in JP-B-48-41708. Etc.

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56- Urethane compounds having an ethylene oxide skeleton described in Japanese Patent No. 17654, Japanese Patent Publication No. 62-39417, and Japanese Patent Publication No. 62-39418 are also suitable. Furthermore, 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 are used. Depending on the case, 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, vinylphosphonic acid compounds described in JP-A-2-25493, and the like 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.

  In the present invention, di (meth) acrylate having a bisphenol skeleton is preferred. Di (meth) acrylates having a bisphenol skeleton include di (meth) acrylates of hydrogenated bisphenol A, di (meth) acrylates of hydrogenated bisphenol F, di (meth) acrylates of ethylene oxide adducts of bisphenol A, bisphenol A Of di (meth) acrylate of propylene oxide adduct, di (meth) acrylate of ethylene oxide adduct of bisphenol F, di (meth) acrylate of propylene oxide adduct of bisphenol F, ethylene oxide adduct of hydrogenated bisphenol A Examples include di (meth) acrylate and di (meth) acrylate of propylene oxide adduct of hydrogenated bisphenol A. Among them, bisphenol A type di (meth) acrylate is preferable, and bisphenol A type The (meth) acrylate, more preferably obtained by adding from 1 to 6 ethylene oxide groups per molecule.

The polymerizable compounds in the photosensitive layer may be used alone or in combination of two or more.
The content of the polymerizable compound in the photosensitive layer is preferably 5 to 75 mass%, more preferably 15 to 70 mass%, more preferably 25 to 60 mass%, based on the total solid content of the photosensitive layer. More preferably.

<Other photosensitive layer components>
The photosensitive layer in the lithographic printing plate precursor according to the invention may further contain various additives as required.
Additives include surfactants for improving developability and improving the surface of the coating, hydrophilic polymers for improving developability and improving the dispersion stability of microcapsules, and visual and non-image areas. A colorant and a print-out agent, a polymerization inhibitor for preventing unnecessary thermal polymerization of a radically polymerizable compound during production or storage of the photosensitive layer, a higher fat derivative for preventing polymerization inhibition by oxygen, Add inorganic fine particles to improve the cured film strength of the image area, hydrophilic low molecular weight compounds to improve developability, co-sensitizers and chain transfer agents to improve sensitivity, plasticizers to improve plasticity, etc. be able to. Any of these compounds can be used, for example, JP 2007-171406, JP 2007-206216, JP 2007-206217, JP 2007-225701, JP 2007-225702, The compounds described in JP-A 2007-316582 and JP-A 2007-328243 can be used.

<Formation of photosensitive layer>
The photosensitive layer in the lithographic printing plate precursor according to the invention can be formed by dispersing and / or dissolving the necessary components described above in a solvent to prepare and apply a coating solution. The solvent used here is a mixed solvent of an organic solvent having a solubility parameter (SP value) of 11 or more and an organic solvent having a solubility parameter (SP value) of less than 11 from the viewpoint of solubility of the ionic polymerization initiator. preferable.
Preferred solvents having a solubility parameter (SP value) of 11 or more include methanol (boiling point 65 ° C., SP value 14.5 to 14.8), ethanol (boiling point 79 ° C., SP value 12.7), 1-propanol (boiling point). 97 ° C, SP value 12.1), 2-propanol (boiling point 82 ° C, SP value 11.5), benzyl alcohol (boiling point 205 ° C, SP value 12.1), N, N-dimethylformamide (boiling point 153 ° C, SP value 11.9) and dimethyl sulfoxide (boiling point 189 ° C., SP value 12.9).

  Preferred solvents having a solubility parameter (SP value) of less than 11 include ethyl acetate (boiling point 77 ° C., SP value 8.7), acetone (boiling point 56 ° C., SP value 9.9), methyl ethyl ketone (MEK) (boiling point 79. 5 ° C, SP value 9.3), tetrahydrofuran (boiling point 66 ° C, SP value 9.1), acetonitrile (boiling point 82 ° C, SP value 11.9), hexane (boiling point 69 ° C, SP value 7.3), cyclohexanone (Boiling point 156 ° C., SP value 9.9), propylene glycol monomethyl ether (MFG) (boiling point 121 ° C., SP value 10.2), toluene (boiling point 111 ° C., SP value 8.8), and the like. .

  Among these, at least one organic solvent having an SP value of 11 or more and at least one organic solvent having an SP value of less than 11 are used in combination. Both the at least one organic solvent having an SP value of 11 or more and the at least one organic solvent having an SP value of less than 11 may have a boiling point of 100 ° C. or higher. From the viewpoint of drying.

Among the organic solvents having an SP value of 11 or more, alcohol solvents such as methanol and ethanol are more preferable.
Among the organic solvents having the SP value of less than 11, more preferable are methyl ethyl ketone and ethyl acetate.

  The blending ratio of the organic solvent having an SP value of 11 or more and the organic solvent having an SP value of less than 11 can be arbitrarily selected, but the proportion of the organic solvent having an SP value of 11 or more in the total solvent weight is 10 to 30% by weight. It is preferable that

  As described above, in addition to at least one organic solvent having an SP value of 11 or more and at least one organic solvent having an SP value of less than 11, as described above, the boiling point is further set to 100 from the viewpoint of improving coatability. It is a preferred embodiment to use an organic solvent at a temperature of ° C or higher in combination. The SP value of the organic solvent having a boiling point of 100 ° C. or higher is not particularly limited, but a solvent having an SP value of less than 11 is more preferable. An organic solvent having an SP value of 11 or more has high polarity as a characteristic of the solvent, and easily interacts with the polymerization initiator of the photosensitive layer. Further, when the boiling point is 100 ° C. or more, it takes a long time or a lot of energy to dry after applying the coating solution, or if the drying is insufficient, the solvent remains in the photosensitive layer and causes performance deterioration. And other harmful effects occur. For this reason, it is more preferable that the organic solvent having a boiling point of 100 ° C. or higher has an SP value of less than 11 and a low polarity.

Preferred organic solvents having a boiling point of 100 ° C. or higher include propylene glycol monomethyl ether and cyclohexanone.
The solid concentration of the coating solution is preferably 1 to 50% by mass.
The dry coating amount (solid content) of the photosensitive layer on the support obtained after coating and drying is preferably 0.3 to 3.0 g / m ² , although it varies depending on the application. Within the above range, good sensitivity and good film properties of the photosensitive layer can be obtained.

<Protective layer>
In the lithographic printing plate precursor according to the invention, a protective layer may be provided on the photosensitive layer, if necessary, in order to prevent scratches and the like in the photosensitive layer, to block oxygen, and to prevent ablation during high-intensity laser exposure.
In the present invention, the exposure is preferably performed in the atmosphere, but the protective layer is a photosensitive layer of a low-molecular compound such as oxygen or a basic substance present in the atmosphere that inhibits an image forming reaction caused by exposure in the photosensitive layer. Inhibition of image formation reaction due to exposure in the air is prevented. Therefore, the properties desired for the protective layer are low permeability of low molecular compounds such as oxygen, furthermore, good transparency of light used for exposure, excellent adhesion with the photosensitive layer, and It is preferable that it can be easily removed in the on-press development process after exposure. Various studies have been made on the protective layer having such characteristics, and are described in detail, for example, in US Pat. No. 3,458,311 and JP-B-55-49729. As the protective layer, the protective layers described in paragraphs 0200 to 0261 of JP2008-15503, JP2008-89916, and JP2008-139813 can be suitably used.

<Support>
The support that can be used for the lithographic printing plate precursor is not particularly limited as long as it is a dimensionally stable plate-like support, but is preferably a hydrophilic support, and more preferably an aluminum plate. .
Examples of the support include paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), and plastic film (eg, cellulose diacetate, triacetic acid). Cellulose, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the metal is laminated or deposited. A preferable support includes a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.
Specifically as an aluminum support body and a processing method, the aluminum support body and the processing method which are described in Unexamined-Japanese-Patent No. 2005-88300 can be illustrated preferably.

<Undercoat layer (intermediate layer)>
In the lithographic printing plate precursor, an undercoat layer (also referred to as “intermediate layer”) is preferably provided on the support. When an undercoat layer is used, the photosensitive layer is provided on the undercoat layer. The undercoat layer reinforces the adhesion between the support and the photosensitive layer in the exposed area, and easily peels the photosensitive layer from the support in the unexposed area, thereby improving the developability.
The undercoat layer preferably contains a compound containing a polymerizable group.
As the undercoat layer, specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of description are mentioned suitably. Particularly preferred compounds include compounds having a polymerizable group such as a methacryl group and an allyl group and a support-adsorptive group such as a sulfonic acid group, a phosphoric acid group and a phosphoric acid ester. A compound having a hydrophilicity-imparting group such as an ethylene oxide group in addition to the polymerizable group and the support-adsorbing group can also be exemplified as a suitable compound.
Dry coating amount (solid content) of the undercoat layer is preferably 0.1-100 mg / m ^2, more preferably 1 to 30 mg / m ^2.

<Back coat layer>
After the surface treatment is performed on the support or after the undercoat layer is formed, a backcoat layer can be provided on the back surface of the support, if necessary.
Examples of the back coat layer include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organic metal compounds or inorganic metal compounds described in JP-A-6-35174, and the like. Preferable examples include a coating layer made of a metal oxide. Among them, it is inexpensive to use a silicon alkoxy compound such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4. It is preferable in terms of easy availability.
When a backcoat layer is provided, the “back surface of the support” in the laminate of the planographic printing plate precursor according to the invention includes a backcoat layer. That is, in that case, the laminated body of the lithographic printing plate precursor of the present invention is obtained by laminating a plurality of lithographic printing plate precursors of the present invention by directly contacting the third protective layer and the backcoat layer (back surface of the support). It becomes.

[Plate making method of planographic printing plate]
The plate making method of the lithographic printing plate of the present invention is not particularly limited as long as it is a method using the lithographic printing plate precursor of the present invention. However, the step of image exposure of the lithographic printing plate precursor (hereinafter also referred to as “exposure step”). ), A plate making method including a step of developing with a developer (hereinafter also referred to as “developing step”), and a plate surface processing step using a plate surface treating agent (hereinafter referred to as “plate surface processing step”). It is more preferable that the plate-making method includes:

<Exposure process and development process>
The plate making method of the lithographic printing plate of the present invention preferably includes a step of exposing the lithographic printing plate precursor to an image and a step of developing with a developer.
Here, the development processing means that an unexposed portion of the photosensitive layer is removed with a developer to form an image corresponding to the exposed portion.

  In the present invention, in the plate making process for producing a lithographic printing plate from a lithographic printing plate precursor, the entire surface of the lithographic printing plate precursor may be heated before exposure, during exposure, and between exposure and development, as necessary. . By such heating, an image forming reaction in the image forming layer is promoted, and the advantages of improved sensitivity, improved printing durability, and stabilized sensitivity are obtained. Further, for the purpose of improving the image strength and printing durability, it is also effective to post-heat the image obtained by development or to expose the entire surface. Usually, heating before development is preferably performed under mild conditions of 150 ° C. or less. Stronger conditions are used for heating after development. A temperature range of 200-500 ° C is preferred.

As the lithographic printing plate precursor that can be used in the plate making method of the lithographic printing plate of the present invention, those described above can be suitably used. The lithographic printing plate precursor that can be used in the present invention is preferably a lithographic printing plate precursor that can be recorded with a laser such as a visible light laser or an infrared laser. Thermal recording with an ultraviolet lamp or a thermal head is also possible.
The exposure light source that can be used in the present invention can be appropriately selected according to the mode of the photosensitive layer, but a visible light laser having a wavelength of 350 nm to 450 nm, a solid-state laser and a semiconductor laser emitting infrared light having a wavelength of 760 nm to 1,200 nm. It is preferable that the lithographic printing plate precursor is image-exposed.

The lithographic printing plate precursor according to the invention is preferably developed with a developer (preferably water or an aqueous alkaline solution) after exposure. As a developer and a replenisher for a lithographic printing plate precursor, a conventionally known alkaline aqueous solution can be used.
Examples of the inorganic alkali salt used in the preparation of the aqueous alkali solution include sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium Inorganic alkali salts such as ammonium, sodium bicarbonate, potassium, ammonium, sodium borate, 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 can also be used.
These alkaline agents can be used alone or in combination of two or more.
The pH of the developer or replenisher is preferably 14 or less, more preferably 8 to 13, and still more preferably 11 to 13.

  Furthermore, when developing using an automatic developing machine, the developer in the developing tank can be developed for a long time by adding an aqueous solution (replenisher) that is the same as the developer or having a higher alkali strength than the developer to the developer. It is known that a large amount of a lithographic printing plate precursor can be processed without changing the liquid. This replenishment method is also preferably applied in the present invention.

Various surfactants, organic solvents, and the like can be added to the developer and the replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving the ink affinity of the printing plate image area.
Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants.
Preferred organic solvents include benzyl alcohol. Further, addition of polyethylene glycol or a derivative thereof, or polypropylene glycol or a derivative thereof is also preferable. In addition, non-reducing sugars such as arabit, sorbit and mannitol can be added.

  Further, in the developer and replenisher, if necessary, inorganic salt-based reducing agents such as hydroquinone, resorcin, sulfite or sodium bisulfite, and organic carboxylic acid, antifoaming agent, water softener Can also be added.

<Plate surface treatment process>
The method for producing a lithographic printing plate precursor according to the invention preferably includes a step of performing plate surface treatment using a plate surface treating agent.
The use mode of the plate surface treating agent is not particularly limited, but it is preferable to use an automatic gum applicator because it can be applied uniformly.
The treatment with the plate surface treatment agent can be carried out immediately after the development step by anhydrous washing, or after the development treatment (including a washing step, washing with circulating water or a small amount of water to be applied) or a rinsing solution containing a surfactant. It can also be done after processing.

An example of the plate surface treating agent is a gum solution.
The gum solution that can be used in the present invention is not particularly limited, and known ones can be used, but it is preferable that a water-soluble polymer compound and a surfactant are included.
There are no particular limitations on the water-soluble polymer compound in the gum solution, soy polysaccharides, modified starch, gum arabic, dextrin, fibrin derivatives (eg, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.) and modified products thereof, pullulan, polyvinyl Examples include alcohols and derivatives thereof, polyvinylpyrrolidone, polyacrylamide and acrylamide copolymers, vinyl methyl ether / maleic anhydride copolymers, vinyl acetate / maleic anhydride copolymers, styrene / maleic anhydride copolymers, and the like.

The surfactant that can be used in the gum solution is not particularly limited, and known compounds can be used.
Surfactants include anionic surfactants such as polyoxyethylene aryl ether sulfonates, dialkyl sulfosuccinates, alkyl sulfate esters and alkyl naphthalene sulfonates; alkylamine salts, quaternary ammonium salts, polyoxy Cationic surfactants such as ethylene alkylamine salts and polyethylene polyamine derivatives; ethylene oxide adducts of sorbitol and / or sorbitan fatty acid esters, polypropylene glycol ethylene oxide adducts, dimethylsiloxane-ethylene oxide block copolymers, dimethylsiloxane- (propylene oxide- Nonionic surfactants such as ethylene oxide block copolymers and fatty acid esters of polyhydric alcohols; Sid, alkyl betaines, and amphoteric surfactants such as sodium alkylamino fatty acid.

The gum solution treatment in the present invention can be carried out immediately after the development step by anhydrous washing, or after the development treatment (including a water washing step, washing with circulating water or a small amount of applied water washing) or a rinse containing a surfactant. It can also be carried out after treatment with a liquid. The gum solution treatment is also suitably performed using an automatic developing machine.
In the present invention, it is also preferable to carry out the removal of the protective layer, the development treatment and the gum solution treatment in one bath.

The plate surface treatment with the plate surface treating agent is also suitably performed using an automatic developing machine. This automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes a device for transporting a lithographic printing plate precursor, each processing liquid tank and a spray device, while horizontally transporting the exposed lithographic printing plate precursor, Each processing liquid pumped up by a pump is sprayed from a spray nozzle to develop and post-process. In addition, a method of immersing and transporting in a processing liquid tank filled with the processing liquid by a guide roll in the liquid and developing processing, or supplying a small amount of rinsing water after development to the plate surface and rinsing the waste water A method of reusing as a diluting water for a developer stock solution is also known.
In such automatic processing, processing can be performed while each replenisher is replenished with each replenisher according to the processing amount, operating time, and the like. In addition, a so-called disposable processing method in which processing is performed with a substantially unused processing solution can also be applied. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing a large number of sheets.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” and “%” are based on mass.

<Synthesis of Polymer Pigment Dispersant Having Heterocycle>
[Synthesis Example 1: Polymer No. Synthesis of 1]
10.0 parts of M-11, terminal methacryloylated polymethyl methacrylate [number average molecular weight 6,000: AA-6: manufactured by Toagosei Co., Ltd., described as (MM-1) in Table 1] 75.0 parts, 15.0 parts of methacrylic acid and 334.0 parts of 1-methoxy-2-propanol were introduced into a nitrogen-substituted three-necked flask and stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor). The mixture was heated to 90 ° C. while flowing in the flask.
To this, 0.5 part of 2,2-azobis (2,4-dimethylvaleronitrile) (“V-65” manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred at 90 ° C. for 2 hours. It was. Two hours later, 0.5 part of V-65 was further added, and after 3 hours of heating and stirring, a graft polymer compound having a side chain derived from MM-1 in the main chain derived from methyl methacrylate and methacrylic acid (polymer) A 30% solution of No. 1) was obtained.
It was 20,000 as a result of measuring the weight average molecular weight of the obtained high molecular compound (polymer No. 1) by the gel permeation chromatography method (GPC) which used the polystyrene as a standard substance.
Moreover, according to the titration using sodium hydroxide, the acid value per solid content was 98 mgKOH / g.

[Synthesis Example 2: Polymer No. Synthesis of 2] Hereinafter, the specific graft-type polymer compound weight was determined in the same manner as in Synthesis Example 1 except that the monomers as listed in Table 1 below were used as the starting material monomers and the addition amount of the polymerization initiator was appropriately changed. Combined 2 was synthesized.

  Details of the monomers and macromonomers used in the synthesis of the pigment dispersant described in Table 1 are shown below.

MM-1: terminal methacryloylated polymethyl methacrylate (number average molecular weight 6,000)
MM-3: terminal methacryloylated methyl methacrylate / acrylonitrile copolymer (60/40% by mass) (number average molecular weight 5,000)
・ MAA: Methacrylic acid

Example 1
(Preparation of pigment dispersion)
C. I. Pigment Blue 15: 6 15.0 parts, 7.5 parts of a dispersant described in Table 2 below, 31.0 parts of methyl ethyl ketone as a solvent, 15.5 parts of methanol, 31.0 parts of 1-methoxy-2-propanol A total of 100 parts were mixed and dispersed with a dynomill for 30 minutes to prepare a pigment dispersion (No. 1).

(Pigment dispersion 2 to 10)
Pigment dispersions 2 to 10 were prepared in the same manner as in Example 1 except that the pigments and dispersants described in Table 2 were changed. The amount of each component in Table 2 is the same as each component in Example 1.

The dispersants listed in Table 2 are shown below.
Azisper PB822: polyallylamine / polycaprolactone pigment dispersant (manufactured by Ajinomoto Fine Techno Co., Ltd.)
・ Hinoact T-8000: polyalkylene polyamine dispersant (manufactured by Kawaken Fine Chemical Co., Ltd.)
-It shows below about the structure of the dye (ethyl violet EV-1) of Table 2.

(Production of support)
<Surface treatment>
In the surface treatment, the following various treatments (a) to (j) were continuously performed. In addition, after each process and water washing, the liquid was drained with the nip roller.
(A) Mechanical surface roughening treatment Using an apparatus as shown in FIG. 1, a suspension of a polishing agent (pumice) having a specific gravity of 1.12 and water is supplied as a polishing slurry to the surface of the aluminum plate. However, a mechanical surface roughening treatment was performed with a rotating roller-like nylon brush. In FIG. 1, 21 is an aluminum plate, 22 and 24 are roller brushes, 23 is a polishing slurry, and 25, 26, 27 and 28 are support rollers. 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 26 mass%, an aluminum ion concentration of 6.5 mass%, and a temperature of 70 ° C. 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 supply waveform is the waveform shown in FIG. 2, the time TP until the current value reaches the peak from zero is 0.8 msec, the duty ratio is 1: 1, a trapezoidal rectangular wave AC is used with the carbon electrode as the counter electrode An electrochemical roughening treatment was performed. 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 The aluminum plate was subjected to etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass to dissolve the aluminum plate by 0.50 g / m ² . Removes the smut component mainly composed of aluminum hydroxide that was generated when electrochemical roughening treatment was performed using the alternating current of 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.
(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 in the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in the nitric acid aqueous solution.
(G) 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 hydrochloric acid 5.0 g / L aqueous solution (containing 5 g / L of aluminum ions) at a temperature of 35 ° C. The waveform of the AC power supply is electrochemically roughened using a trapezoidal trapezoidal wave AC with a time TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal trapezoidal wave AC. Processed. 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) Alkali etching treatment The aluminum plate was subjected to 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 that was generated when electrochemical roughening treatment was performed using the alternating current of 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 is carried out using an anodizing apparatus (first and second electrolysis section length 6 m, first and second feeding section length 3 m each, first and second feeding electrode section length 2.4 m each). went. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 50 g / L (containing 0.5 mass% of aluminum ions) and a temperature of 20 ° C. Then, water washing by spraying was performed.

Next, the following intermediate layer coating solution (B) was coated on the aluminum support subjected to the above surface treatment so as to have a dry coating amount of 10 mg / m ² and dried.
<Intermediate layer coating solution (B)>
-Polymer compound A having the following structure (weight average molecular weight: 30,000) 0.017 parts-Methanol 9.00 parts-Water 1.00 parts

  In addition, the number on the lower right of the parenthesis representing each monomer unit in the polymer compound A represents a molar ratio.

(Formation of photosensitive layer)
The following photosensitive layer forming coating solution 1 was prepared, and applied on the undercoat layer (on the intermediate layer) formed as described above using a wire bar. Drying was performed at 125 ° C. for 34 seconds using a warm air dryer. The coating amount after drying was 1.0 g / m ² .

<Photosensitive layer forming coating solution 1>
Infrared absorber (IR-1: Structural formula below) 0.038 parts Polymerization initiator A (S-1: Structural formula below) 0.061 parts Polymerization initiator B (I-1: Structural formula below) 0 .094 parts / mercapto compound (E-1: structural formula below) 0.015 part / polymerizable compound (A-BPE-4: structural formula below) (trade name: A-BPE-4 Shin-Nakamura Chemical Co., Ltd.) ) 0.425 parts Binder polymer A (B-1: Structural formula below) 0.311 parts Binder polymer B (B-2: Structural formula below) 0.250 parts Binder polymer C (B-3: Structural formula below) Formula) 0.062 parts Additive (sensitization aid) (T-1: Structural formula below) 0.079 parts Polymerization inhibitor (Q-1: Structural formula below) 0.0012 parts Pigment dispersion 2 0.137 parts ・ Fluorosurfactant (Megafac F-780-F Dai Nippon Ink Gaku Kogyo Co., Ltd., methyl isobutyl ketone (MIBK) 30% by mass solution) 0.0081 parts · methyl ethyl ketone (MEK) 6.000 parts · methanol (MA) 3.000 parts · 1-methoxy-2-propanol (MFG) 6.000 parts

  In addition, the infrared absorber (IR-1), polymerization initiator A (S-1), polymerization initiator B (I-1), and mercapto compound (E-1) used for the coating liquid A for forming the photosensitive layer. , Polymerizable compound (M-1), binder polymer A (B-1), binder polymer B (B-2), binder polymer C (B-3), additive (T-1) and polymerization inhibitor (Q The structure of -1) is shown below.

(Coating solution for photosensitive layer formation)
In Examples 2 to 7 and Comparative Examples 1 to 8, coating solutions for forming a photosensitive layer were prepared in the same manner as in Example 1 except that the pigment dispersions and mixed solvent types shown in Table 3 were changed. The amount of each component in Table 3 is the same as each component in Example 1.

(Formation of lower protective layer)
On the formed photosensitive layer, synthetic mica (Somasif MEB-3L, 3.2% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.), polyvinyl alcohol (Goselan CKS-50: saponification degree 99 mol%, polymerization degree 300) , Sulfonic acid-modified polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), surfactant A (Emalex 710, manufactured by Nippon Emulsion Co., Ltd.), and surfactant B (Adeka Pluronic P-84, Inc.) A mixed solution of ADEKA) was applied with a wire bar and dried at 125 ° C. for 30 seconds using a hot air dryer.
The content ratio of synthetic mica (solid content) / polyvinyl alcohol / surfactant A / surfactant B in this mixed aqueous solution (coating liquid for forming the lower protective layer) was 7.5 / 89/2 / 1.5. The coating amount (the coating amount after drying) was 0.5 g / m ² .

(Formation of upper protective layer)
On the lower protective layer, an organic filler (Art Pearl J-7P, manufactured by Negami Industrial Co., Ltd.), synthetic mica (Somasif MEB-3L, 3.2% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.), polyvinyl alcohol ( L-3266: degree of saponification 87 mol%, degree of polymerization 300, sulfonic acid-modified polyvinyl alcohol Nippon Synthetic Chemical Industry Co., Ltd.), thickener (Serogen FS-B, Daiichi Kogyo Seiyaku Co., Ltd.), and A mixed aqueous solution of the surfactant (manufactured by Nippon Emulsion Co., Ltd., Emalex 710) was applied with a wire bar and dried at 125 ° C. for 30 seconds with a hot air dryer. .
The content ratio of the organic filler / synthetic mica (solid content) / polyvinyl alcohol / thickening agent / surfactant in the mixed aqueous solution (coating liquid for forming the upper protective layer) was 4.8 / 2.9 / 69. It was 0 / 19.0 / 4.3 (mass%), and the coating amount (the coating amount after drying) was 1.2 g / m ² .

(Formation of back coat layer and plate making process)
On the surface opposite to the side provided with the protective layer, the following back coat coating composition was applied with a wire bar and dried at 100 ° C. for 70 seconds to obtain a back coat layer containing an organic polymer compound. The coating amount was 0.46 g / m ² .

<Backcoat coating solution>
-Tetraethoxysilane 2.17 parts-Dibutylmaleic acid ester 0.16 parts-Pyrogallol resin (weight average molecular weight 3,000: Structural formula below) 0.16 parts-MegaFac F-780-F (manufactured by DIC Corporation) ) 0.005 part · methyl ethyl ketone 22.5 parts · 1-methoxy-2-propanol 2.5 parts

The lithographic printing plate precursor thus obtained is conveyed from the setting part to a Trendsetter 3244 manufactured by Creo by an autoloader, and a 50% flat screen image is output at a resolution of 2,400 dpi, output 7 W, outer drum rotation speed 150 rpm, plate energy 110 mJ / Exposed at cm ² . After the exposure, neither heat treatment nor water washing treatment was performed, and development processing was performed using an automatic developing machine LP-1310HII manufactured by Fuji Film Co., Ltd. at a conveyance speed (line speed) of 2 m / min and a development temperature of 30 ° C. The developer used was a 1: 4 water diluted solution of DH-N manufactured by Fuji Film Co., Ltd., and the developer replenisher used was a 1: 1.4 water diluted solution of FCT-421 manufactured by Fuji Film Co., Ltd.

(1-1) Evaluation of initiator solubility in photosensitive layer forming coating solution After preparing the photosensitive layer forming coating solutions of the above-described Examples and Comparative Examples, stirring was performed at 25 ° C for 1 hour, and after stirring was completed. The solubility of the initiator was evaluated. The case where the initiator was dissolved and the residue was not observed was evaluated as ◯, and the case where the initiator was not dissolved and the residue was observed was evaluated as ×.

(1-2) Evaluation of pigment sedimentation property in photosensitive layer forming coating solution The photosensitive layer forming coating solutions of the above-described Examples and Comparative Examples were allowed to stand at 25 ° C. for 5 days, and the solution immediately after preparation and 5 days. The difference in absorbance derived from the pigment with the supernatant after standing was measured to evaluate pigment sedimentation. Absorbance measurement was performed using an absorbance meter U-3010 manufactured by Hitachi High-Technology Co., Ltd., and using an absorbance value at a wavelength of 600 nm derived from the pigment. As the absorbance measurement liquid, 1 cc of the coating liquid was sampled and used after dilution 500 times with MEK. Evaluation was performed in 1 to 5 stages, 3 was a practical lower limit level, and 2 or less was a practically unusable level.
5: Immediately after preparation and after 5 days supernatant absorbance difference 0-1%
4: Immediately after preparation and after 5 days supernatant absorbance difference 1-5%
3: Immediately after preparation and after 5 days supernatant absorbance difference 5-10%
2: Immediately after preparation and after 5 days supernatant absorbance difference 10-30%
1: Immediately after preparation and after 5 days supernatant absorbance difference 30-100%

(1-3) Evaluation of image density / sensitivity Using the Macbeth reflection densitometer RD-918, the red density filter equipped on the densitometer is used to measure the image area density of each lithographic printing plate obtained by development. The cyan density was measured. Table 3 shows the reciprocal of the exposure necessary to obtain a measured density of 0.9 as an index of sensitivity. In the evaluation results, the sensitivity of the lithographic printing plate obtained in Example 1 was set to 100, and the sensitivity of other lithographic printing plates was set as a relative evaluation. The larger the value, the better the sensitivity.

(1-4) Evaluation of Micro Residual Film Each lithographic printing plate after 6 months of room temperature natural aging was developed, and the non-image part was observed with a microscope (KEYENCE VHX-100F) at 1,000 times, so that The minute residual film generated was observed. The results are shown in Table 3. Evaluation was performed by sensory evaluation of 1 to 5, 3 being a practical lower limit level, and 2 or less being a practically impossible level. The evaluation criteria are as follows.
5: No minute residual film in observation field 4: 2 to 5 minute residual films in observation field 3: 5 to 20 minute residual films in observation field 2: 20 to 100 minute residual films in observation field 1: Observation field More than 100 minute residual films

As is clear from the results shown in Table 3, component b and component c were used in combination with component a, and a mixed solvent of an organic solvent having an SP value of 11 or more and an organic solvent having an SP value of less than 11 was used. By using the coating solution for forming the photosensitive layer, it can be seen that it is possible to achieve both high sensitivity, solubility of the ionic polymerization initiator, pigment sedimentation stability in the coating solution, and suppression of a small residual film over time.
Further, by setting the ratio of the component c to the total weight of the pigment dispersant component b and the component c to 5 to 20% by weight which is the most preferable range, the pigment sedimentation stability in the coating liquid is maintained, and the minute residual film It can be seen that the suppression performance is further improved.
On the other hand, the one using only the pigment dispersant component b is effective for suppressing the residual film, but the pigment sedimentation stability is poor, and the one using only the component c is against the pigment sedimentation stability. Although effective, a minute residual film is generated. In addition, by preparing a coating solution that does not use a solvent having an SP value of 11 or more, the pigment sedimentation property is greatly improved, but the solubility of the ionic polymerization initiator is deteriorated.

21: Aluminum plate 22, 24: Roller brush 23: Polishing slurry liquid 25, 26, 27, 28: Support roller

Claims (11)

The photosensitive layer containing (component f) an ionic polymerization initiator, (component a) a pigment, (component b) a pigment dispersant having a heterocyclic ring, and (component c) a pigment dispersant having a polar group is treated as a hydrophilic surface. provided on a support having,
Component b has at least one of the groups represented by formula (b-2) to formula (b-4),
The polar group of component c is a basic group ,
A lithographic printing plate precursor.

In the formulas (b-2) to (b-4), X represents a single bond, an alkylene group, —O—, —S—, —NR ^A —, or —C (═O) —. ,
R ^A represents a hydrogen atom or an alkyl group,
Y and Z each independently represent —N═ , —N (R ^B ) —, —S—, or —O—;
R ^B represents a hydrogen atom or an alkyl group,
At least Y or Z is —N═ or —N (R ^B ) —,
Ring A, ring B, ring C and ring D each independently represent an aromatic ring.   The lithographic printing plate precursor according to claim 1, wherein the photosensitive layer further comprises (Component d) a binder polymer, (Component e) a sensitizing dye, and (Component g) a radical polymerizable compound.   The lithographic printing plate precursor according to claim 1 or 2, wherein component a is at least one selected from the group consisting of phthalocyanine pigments, dioxane pigments, quinacridone pigments, and diketopyrrolopyrrole pigments. The lithographic printing plate precursor as claimed in any one of claims 1 to 3 , wherein the component b has a group represented by the formula (b-4).   The lithographic printing plate precursor according to claim 4, wherein either one of Y and Z in formula (b-4) is -N = and the other is -NH.   The lithographic printing plate precursor as claimed in any one of claims 1 to 5, wherein the component b is a graft polymer compound having a weight average molecular weight of 1,000 or more and 100,000 or less.   The lithographic printing plate precursor according to claim 6, wherein the component b comprises a structural unit derived from a polymerizable oligomer having an ethylenically unsaturated bond at the terminal.   The lithographic printing plate precursor as claimed in any one of claims 1 to 7, wherein the polar group of component c is an amino group.   The lithographic printing plate precursor as claimed in any one of claims 1 to 8, wherein the ratio of the component c to the total weight of the components b and c is 1 to 50% by weight.   The lithographic printing plate precursor as claimed in any one of claims 1 to 9, wherein component f is an onium salt.   A method for producing a lithographic printing plate precursor, comprising a step of coating a support comprising a composition comprising the components constituting the photosensitive layer according to any one of claims 1 to 10.

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