Method for developing lithographic printing plate precursor, method for producing lithographic printing plate, lithographic printing method, and plate surface treatment agent

Abstract

To provide a method for developing a lithographic printing plate precursor capable of improving ink receptivity, a method for manufacturing a lithographic printing plate, a lithographic printing method and a plate surface treating agent.SOLUTION: A step of applying a plate surface treatment agent different from a printing ink to a lithographic printing plate precursor including an imagewise exposed image recording layer before application of at least one of the printing ink or dampening water, and a step of removing the image recording layer in a non-image area with the plate surface treatment agent, there are provided a method for developing a lithographic printing plate precursor in which an oil phase contains an extender pigment, a lithographic printing method, and a plate surface treatment agent which is an emulsion containing a water phase and an oil phase, in which the oil phase contains a medium, the medium contains an extender pigment, and the ratio of the water phase is 50 mass% or more based on the total mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for developing a lithographic printing plate precursor, a method for producing a lithographic printing plate, a lithographic printing method, and a plate surface treatment agent. [Background technology]

[0002] Generally, a lithographic printing plate consists of an oleophilic image area that accepts printing ink during the printing process and a hydrophilic non-image area that accepts fountain solution. Lithographic printing utilizes the mutual repulsion properties of water and oil-based printing ink, with the oleophilic image area of ​​the lithographic printing plate acting as the ink-receptive area and the hydrophilic non-image area acting as the fountain solution-receptive area (ink-non-receptive area), creating a difference in the adhesion of printing ink on the surface of the lithographic printing plate, and after the printing ink is applied only to the image area, the printing ink is transferred to the printing substrate such as paper to print.

[0003] The image and non-image areas of a lithographic printing plate are formed by developing a lithographic printing plate precursor. Developing inks are known that are applied to the plate surface after the non-image areas of an exposed lithographic printing plate precursor are removed by washing with water or the like (Patent Documents 1 and 2). These developing inks make it easier to visually distinguish between the image and non-image areas, and can be attached to the lipophilic image areas to enhance the receptivity of printing ink. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 55-027355 [Patent Document 2] Japanese Patent Application Publication No. 08-108662 Summary of the Invention [Problem to be solved by the invention]

[0005] In addition to processed plates, unprocessed plates have been developed as printing plates for use in lithographic printing. In lithographic printing using unprocessed plates, poor ink adhesion, such as slow ink adhesion at the start of printing, can lead to increased paper waste. Therefore, it is conceivable to use developing inks such as those described in Patent Documents 1 and 2. However, for process-less plates, developing inks such as those described in Patent Documents 1 and 2 could not be used for the following two reasons.

[0006] First, the developing inks described in Patent Documents 1 and 2 are used in processing the image areas after removing the non-image areas, but in the case of process-free plates, the process of removing the non-image areas of the image recording layer after exposure is carried out by printing on a printing press, for example. In other words, because the removal of the non-image areas and printing are carried out as a series of processes by on-press development, there has been no situation in which conventional developing inks can be applied.

[0007] Second, the developing inks described in Patent Documents 1 and 2 are colored to make it easier to visually distinguish between image and non-image areas. However, as mentioned above, in the case of unprocessed plates, the process of removing the non-image areas of the image recording layer after exposure is carried out, for example, by supplying dampening water and / or printing ink to the surface of the lithographic printing plate precursor on a printing press, and therefore, even if processing with conventional developing inks could be carried out, there is a possibility that this could have an adverse effect on the color of the subsequent printing.

[0008] The present disclosure has been made in light of the above. An object of one embodiment of the present disclosure is to provide a method for developing a lithographic printing plate precursor, a method for manufacturing a lithographic printing plate, a lithographic printing method, and a plate surface treatment agent that can improve ink receptivity. [Means for solving the problem]

[0009] Specific means for solving the problems include the following aspects. <1> A method for developing a lithographic printing plate precursor, comprising: a step of applying a plate surface treatment agent different from the printing ink to a lithographic printing plate precursor including an image-wise exposed image recording layer before applying at least one of the printing ink and the dampening water; and a step of removing the image recording layer in non-image areas using the plate surface treatment agent, wherein the plate surface treatment agent is an emulsion including an aqueous phase and an oil phase, and the oil phase includes an extender pigment. <2> This is done before the lithographic printing plate precursor is loaded onto the printing press. <1> 1. A method for developing a lithographic printing plate precursor according to claim 1. <3> This is done after the lithographic printing plate precursor is mounted on the printing press. <1> 1. A method for developing a lithographic printing plate precursor according to claim 1. <4> The lithographic printing plate precursor is a non-processed plate. <1> ~ <3> 10. A method for developing a lithographic printing plate precursor according to any one of the above items 1 to 9. <5> A method for producing a lithographic printing plate, comprising: a step of exposing an image-wise image-recording layer of a lithographic printing plate precursor to light; and a step of removing the image-recording layer in non-image areas with a plate surface treatment agent different from printing ink, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment. <6> A lithographic printing method comprising the steps of: exposing an image-wise image-wise image recording layer of a lithographic printing plate precursor; preparing a lithographic printing plate by removing the image recording layer in non-image areas with a plate surface treatment agent different from the printing ink; and mounting the lithographic printing plate on a printing press and printing using the lithographic printing plate mounted on the press and the printing ink, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment. <7> A lithographic printing method comprising the steps of: exposing an image-wise image-recording layer of a lithographic printing plate precursor; mounting the lithographic printing plate precursor on a printing press and applying a plate surface treatment agent different from the printing ink before applying at least one of the printing ink and the fountain solution; and removing the image recording layer in non-image areas with the plate surface treatment agent, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment. <8> A lithographic printing method comprising the steps of applying a plate surface treatment agent different from the printing ink to the surface of a lithographic printing plate used for printing, and printing using the lithographic printing plate after the application of the plate surface treatment agent, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment. <9> A plate surface treatment agent which is an emulsion containing an aqueous phase and an oil phase, the oil phase containing a medium, the medium containing an extender pigment, and the proportion of the aqueous phase based on the total mass is 50 mass % or more. <10> The oil phase contains a solvent and an emulsifier, and the aqueous phase contains a water-soluble resin and a pH adjuster. <9> 1. The plate surface treatment agent according to claim 1. [Effects of the Invention]

[0010] According to one embodiment of the present disclosure, there are provided a developing method for a lithographic printing plate precursor, a printing method, and a plate surface treatment agent that can improve ink receptivity. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view of one embodiment of a support. [Figure 2] FIG. 2 is a schematic cross-sectional view of another embodiment of the support. [Figure 3] FIG. 3 is a graph illustrating the waveform of an AC power source used in the electrochemical graining treatment when preparing the support in the examples. [Figure 4] FIG. 4 is an explanatory diagram illustrating the electrolytic bath used in the electrochemical graining treatment when preparing the support in the examples. [Figure 5] FIG. 5 is an explanatory diagram illustrating the electrolytic bath used for anodizing treatment when preparing the support in the examples. [Figure 6] FIG. 6 is a table illustrating the appearance of the lithographic printing plate surface in the examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described. The present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present disclosure. In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the upper and lower limits. In the numerical ranges described in stages in the present disclosure, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the examples. In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. In the present disclosure, a combination of two or more preferred aspects or embodiments is a more preferred aspect or embodiment. In this disclosure, "mass%" and "wt%" are synonymous, and "parts by mass" and "parts by weight" are synonymous. In this disclosure, "%" indicating the amount of a component is based on mass unless otherwise specified. In this disclosure, pH is the value measured with a pH meter at 25°C.

[0013] Hereinafter, the method for developing a lithographic printing plate precursor, the method for producing a lithographic printing plate, the printing method, and the plate surface treatment agent according to the present disclosure will be described in detail.

[0014] The process leading to the embodiments of the present disclosure will be described. In printing using a lithographic printing plate, poor ink adhesion, such as slow ink adhesion at the start of printing, can sometimes result in increased paper waste. For example, when an untreated plate is used on a printing press such as a flatbed proofing machine, which is a printing condition that makes poor ink adhesion at the start of printing more likely, ink adhesion at the start of printing may be slower, resulting in more paper waste than when a treated plate is used. This ink retention problem at the start of printing can be addressed by a printing method in which the plate surface is wiped with dampening water beforehand, and development is carried out before moving on to the printing process. However, this printing method may not be effective enough in reducing paper waste because dampening water components may remain on the image area of ​​the plate.

[0015] Therefore, the present inventors investigated methods for reducing paper waste even under printing conditions that are prone to poor ink adhesion at the start of printing, and focused on the development process. They found that by using a specific plate surface treatment agent instead of the printing ink or dampening water used in the development process, it is possible to improve ink adhesion, suppress poor ink adhesion such as delayed ink adhesion at the start of printing, and reduce paper waste.

[0016] Although the detailed mechanism is unknown, the inventor speculates as follows. Specifically, when dampening water is used to remove non-image areas during development, the hydrophilic layer on the plate surface is not sufficiently removed, which may result in delayed ink-receiving ability with oil-based printing ink. On the other hand, when a specific plate surface treatment agent is used instead of dampening water to remove non-image areas, it is thought that a hydrophilic layer is less likely to form on the plate surface, allowing oil-based printing ink to quickly blend into the image areas after development. Therefore, the inventor speculates that the use of a specific plate surface treatment agent improves ink-receiving ability at the start of printing and enables appropriate removal of the image-recording layer in non-image areas.

[0017] A method for developing a lithographic printing plate precursor (hereinafter also referred to as a "method for developing a lithographic printing plate precursor") that is one embodiment of the present disclosure includes a step of removing the image recording layer in non-image areas of a lithographic printing plate precursor that includes an image-wise exposed image recording layer using a plate surface treatment agent that is an emulsion containing an aqueous phase and an oil phase (hereinafter also referred to as a "developing step").

[0018] (plate surface treatment agent) A plate surface treatment agent (hereinafter also referred to as "plate surface treatment agent") that is one embodiment of the present disclosure is an emulsion containing an aqueous phase and an oil phase, the oil phase containing a medium, the medium containing an extender pigment, and the proportion of the aqueous phase based on the total mass is 50 mass% or more. Plate surface treatment agents are emulsions containing an aqueous phase and an oil phase, and are different from printing inks. While printing inks are intended to transfer images to printing media, plate surface treatment agents are not. However, plate surface treatment agents that adhere to the printing plate surface may mix with printing ink or be transferred to the printing media. Even in such cases, printing inks transfer visible images when printed, while plate surface treatment agents contain extender pigments and transfer almost no visible images, and the two agents have different compositions.

[0019] In the plate surface treatment agent, the oil phase contains a medium, and the medium contains an extender pigment. Therefore, the oil phase contains a body pigment. In the present disclosure, the extender pigment means achromatic pigment. In the plate surface treatment agent, the oil phase contains an extender pigment, which allows printing ink to quickly blend into the image area after development without being affected by the hydrophilic layer, improving ink receptivity at the start of printing and preventing poor ink receptivity at the start of printing. In addition, the extender pigment is less likely to impair the color of the printing ink used in printing, thereby contributing to preventing an increase in paper waste.

[0020] In the plate surface treatment agent, the oil phase may contain one type of extender pigment or two or more types. The content of the extender pigment in the plate surface treatment agent is suitably 0.0001 to 0.1% by mass, and more preferably 0.0003 to 0.05% by mass, based on the total mass of the plate surface treatment agent. In the plate surface treatment agent, the oil phase may contain an extender pigment, and the method for incorporating the extender pigment into the oil phase may be a conventionally known method.

[0021] The plate surface treatment agent has an oil phase containing a medium. A medium is an achromatic ink used for diluting ink, in which only an extender pigment is dispersed, and is also called transparent white or trans white. By including a medium in the oil phase, the extender pigment can be incorporated into the oil phase.

[0022] Various media can be used as long as they contain an extender pigment and do not impair the effects of the plate surface treatment agent, including, for example, a medium for oil-based ink, a medium for UV (ultraviolet) curable ink, and a medium for offset web printing. The content of the extender pigment in the medium is preferably an amount such that the content of the extender pigment relative to the plate surface treatment agent falls within the above range. For example, the content of the extender pigment in the medium is preferably 0.5% to 10% by mass, more preferably 1% to 7% by mass, based on the total mass of the medium. The extender pigment contained in the medium may be any extender pigment used in printing inks, such as calcium carbonate and baryte powder. Specifically, commercially available products such as F Gloss Medium (manufactured by DIC Corporation) can be used as the medium.

[0023] The plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the proportion of the aqueous phase is 50% by mass or more based on the mass of the entire plate surface treatment agent (i.e., the entire emulsion). Preferably, it is 50% to 85% by mass, and more preferably 50% to 80% by mass. A proportion of the aqueous phase of 50% by mass or more means that the aqueous phase is contained in a larger amount than the oil phase components. By having the proportion of the aqueous phase in the plate surface treatment agent fall within the above range, when the plate surface treatment agent is used instead of dampening water or the like, the non-image areas of the image recording layer can be appropriately removed in an unprocessed plate. Furthermore, when the plate surface treatment agent is used, adhesion of the hydrophilic layer to the image areas can be suppressed, thereby improving ink receptivity. The aqueous phase contains water.

[0024] The pH of the plate surface treatment agent is preferably 1.0 to 7.0, more preferably 4.0 to 7.0. Because the medium may contain calcium carbonate and carbon dioxide may be generated in an acidic range, a neutral pH is preferred from the viewpoint of liquid stability.

[0025] The water phase, oil phase and other components of the plate surface treatment agent will be explained below. The plate surface treatment agent preferably has an oil phase containing a solvent and an emulsifier, and an aqueous phase containing a water-soluble resin and a pH adjuster. In addition, the plate surface treatment agent preferably has an oil phase containing a solvent and an emulsifier, and an aqueous phase containing a water-soluble resin, an acid or a base, a cleaning enhancer, and a pH adjuster. The acid includes the following (2), the base includes the following (10), and the cleaning enhancer includes at least one of the following (2) to (4).

[0026] In addition to the extender pigment, the plate surface treatment agent may be composed of, for example, (1) a water-soluble polymer compound that is a water-soluble resin, (2) at least one compound selected from the group consisting of phosphoric acid or polymerized phosphoric acid and their salts (e.g., alkali metal salts), and organic phosphonic acid and their salts, (3) at least one compound selected from the group consisting of nitric acid and nitrates, (4) at least one compound selected from the group consisting of sulfuric acid, sulfates, and bisulfates, and (5) an aqueous phase containing water, and (6) an oil phase containing a hydrocarbon solvent that is a solvent and has the ability to dissolve printing ink. The plate surface treatment agent may contain (7) a surfactant that is an emulsifier, (8) a wetting agent, (9) a thixotropic agent, (10) a pH adjuster, and (11) a salt that provides a cation, as needed. In addition to the above components, the plate surface treatment agent may also contain preservatives, disinfectants, etc.

[0027] Specific examples of the water-soluble polymer compound that is the water-soluble resin of component (1) above include natural products such as dextrin, cyclodextrin, alginate, cellulose derivatives (e.g., carboxymethyl cellulose, carboxyethyl cellulose, hydroxyethyl cellulose, methyl cellulose, etc.), gum arabic, and soybean polysaccharides, as well as modified products thereof, and synthetic products such as polyvinyl alcohol and its derivatives, polyvinylpyrrolidone, polyacrylamide and its copolymers, acrylic acid copolymers, vinyl methyl ether / maleic anhydride copolymers, vinyl acetate / maleic anhydride copolymers, and styrene / maleic anhydride copolymers.

[0028] Examples of polysaccharides extracted from soybeans that have film-forming properties include water-soluble soybean polysaccharides. Water-soluble soybean polysaccharides contain rhamnose, fucose, arabinose, xylose, galactose, glucose, uronic acid, and other constituent sugars, and have an average molecular weight of 50,000 to 1,000,000. The content of water-soluble soybean polysaccharides in the plate surface treatment agent is suitably in the range of 0.5% to 20% by mass, preferably 1% to 10% by mass. The water-soluble soybean polysaccharides are dissolved in water or warm water at 50°C or less to prepare a homogeneous aqueous solution. A method for producing such water-soluble soybean polysaccharides is described in JP-A-5-32701. Commercially available water-soluble soybean polysaccharides include soy gum and Soyafive-S-LN (manufactured by Fuji Oil Co., Ltd.). Soybean polysaccharides that can be used in the plate surface treatment agent preferably have a viscosity (25°C) of 5 to 100 cp in a 10% by mass aqueous solution.

[0029] These substances can be used alone or in combination, and in order to keep the plate surface treatment agent within the preferred viscosity range (approximately 100 cps to 1000 cps), the amount used is suitably 1% to 24% by mass based on the total mass of the plate surface treatment agent, and more preferably can be selected from the range of 3% to 20% by mass.

[0030] Examples of the component (2), which is at least one compound selected from the group consisting of phosphoric acid or polymerized phosphoric acid and salts thereof, and organic phosphonic acid and salts thereof, include phosphoric acid, sodium phosphate, potassium phosphate, lithium phosphate, pyrophosphoric acid, sodium pyrophosphate, potassium pyrophosphate, lithium pyrophosphate, triphosphoric acid, sodium triphosphate, potassium triphosphate, lithium triphosphate, tetraphosphoric acid, sodium tetraphosphate, potassium tetraphosphate, lithium tetraphosphate, metaphosphoric acid, sodium metaphosphate, potassium metaphosphate, lithium metaphosphate, trimetaphosphoric acid, sodium trimetaphosphate, potassium trimetaphosphate, lithium trimetaphosphate, hexametaphosphoric acid, sodium hexametaphosphate, potassium hexametaphosphate, lithium hexametaphosphate, methylene diphosphonic acid, 1-hydroxyethoxybenzoic acid, 1-hydroxy ... Examples of the carboxylic acid include ethane-1,1-disulfonic acid, nitrilotrisphosphonic acid, N-carboxymethyl-N,N-di(methylenephosphonic acid), hexamethylenediamine-tetra(methylenephosphonic acid), ethylenediamine-tetra(methylenephosphonic acid), diethylenetriamine-penta(methylenephosphonic acid), N,N-di(carboxymethyl)-N-methylenephosphonic acid, N-(2-hydroxyethyl)-N,N-di(methylenephosphonic acid), N-hydroxymethyl-N,N'N'-ethylenediaminetris(methylenephosphonic acid), N-hydroxyethyl-N',N'-diethylethylenediamine-N,N,N',N'-tetra(methylenephosphonic acid), di(2-hydroxypropylene)triaminepenta(methylenephosphonic acid), and tri(2-hydroxypropylene)tetraaminehexa(methylenephosphonic acid).

[0031] These compounds are commercially available, for example, as the "DEQUEST" series from Monsanto Chemical Company and as the "WAYPLEX" series from the Wayland Chemical Division of Philip A. Hunt Chemical Corp. The above compounds can be used alone or in combination of two or more, and are contained in an amount of 0.1% to 15% by weight, more preferably 0.5% to 10% by weight, based on the total weight of the plate surface treatment agent.

[0032] Component (3) used in the plate surface treatment agent is at least one member selected from the group consisting of nitric acid and nitrates, and includes, in addition to nitric acid, metal salts of nitric acid such as zinc nitrate, cobalt nitrate, magnesium nitrate, sodium nitrate, potassium nitrate, nickel nitrate, bismuth nitrate, tin nitrate, strontium nitrate, cesium nitrate, rubidium nitrate, and cerium nitrate, as well as ammonium nitrate. The total amount of component (3) used in the plate surface treatment agent is in the range of 0.1% to 10% by weight, and more preferably 0.5% to 5% by weight, based on the total weight of the plate surface treatment agent.

[0033] Component (4) used in the plate surface treatment agent is at least one member selected from the group consisting of sulfuric acid, sulfates, and bisulfates. Examples of sulfates or bisulfates include sodium sulfate, potassium sulfate, cesium sulfate, rubidium sulfate, and aluminum sulfate. Bisulfates are represented by the general formula M(HSO4)n (where M represents a metal and n represents the valence of M). Examples include strontium hydrogen sulfate, potassium hydrogen sulfate, calcium hydrogen sulfate, thallium hydrogen sulfate, sodium hydrogen sulfate, lead hydrogen sulfate, bismuth hydrogen sulfate, magnesium hydrogen sulfate, and rhodium hydrogen sulfate. These compounds can be used alone or in combination. The total content of component (4) is 0.01 to 5% by weight, preferably 0.1 to 3% by weight, based on the total weight of the plate surface treatment agent.

[0034] The remaining component of the aqueous phase of the plate surface treatment agent (5) is water, and the amount of water is preferably 45 to 85% by mass, more preferably 50 to 80% by mass, based on the total mass of the plate surface treatment agent.

[0035] On the other hand, the oil phase of the plate surface treatment agent can be used in combination with a hydrocarbon solvent (component (6)). Particularly useful examples of component (6) include petroleum fractions with a boiling point of 120 to 350°C that are commonly used to wash off printing inks. Specific examples of such hydrocarbon solvents include products from Nippon Petrochemical Co., Ltd., such as Cleansol, Dry Solvent, A Solvent, K Solvent, Mineral Spirit A, and Hyalom 25, all of which have boiling points of 150-200°C; Insecticide Solvent, Fog Solvent, and Non-Sulfur Solvent, all of which have boiling points of 200-250°C; No. 3 Solvent, No. 4 Solvent, No. 5 Solvent, No. 6 Solvent, No. 7 Solvent, and tall oil fatty acid esters, all of which have boiling points of 250-300°C; Swazol (aromatic high-boiling solvent, manufactured by Maruzen Petrochemical Co., Ltd.); Exozol (manufactured by ExxonMobil Corp.); and Exxol (naphthenic solvent, manufactured by ExxonMobil Corp.). The range of use of these hydrocarbon solvents is preferably 1% to 50% by weight, and more preferably 5% to 35% by weight, based on the total weight of the plate surface treatment agent. Because component (6) is immiscible with water (component (5)), it must be used as a thoroughly mixed and dispersed emulsion. To enhance the stability of the dispersion, it is useful to add a surfactant (component (7)). Usable surfactants include anionic and nonionic surfactants.

[0036] Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkanesulfonates, alkane sulfonates, dialkyl sulfosuccinates, linear alkylbenzene sulfonates, branched alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenoxypolyoxyethylenepropyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurate sodium salt, N-alkylsulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, and sulfuric acid of fatty acid alkyl esters. Acid ester salts, alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfate ester salts, fatty acid monoglyceride sulfate ester salts, polyoxyethylene alkylphenyl ether sulfate ester salts, polyoxyethylene styrylphenyl ether sulfate ester salts, alkyl phosphate ester salts, polyoxyethylene alkyl ether phosphate ester salts, polyoxyethylene alkylphenyl ether phosphate ester salts, partially saponified products of styrene-maleic anhydride copolymers, partially saponified products of olefin-maleic anhydride copolymers, naphthalenesulfonate-formaldehyde condensates, etc. Among these, dialkyl sulfosuccinates, alkyl sulfate ester salts, and alkylbenzenesulfonates are particularly preferably used.

[0037] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrylphenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylated castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides, etc. Among these, sorbitan fatty acid partial esters, polyoxyethylated castor oil ethers, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene-polyoxypropylene block polymers, etc. are preferably used. Two or more of these surfactants may be used in combination. The amount of surfactant used is not particularly limited, but a preferred range is 0.5% by mass to 10% by mass based on the total mass of the plate surface treatment agent.

[0038] In addition to the above components, one or more humectants (component (8)) are also useful to impart good spreading properties to the plate surface treatment agent, inhibit drying, and improve suitability for use. Suitable humectants are those of the general formula: HO-(RO) n -H (wherein R is C m H 2m(m=2 to 6, and n is 1 to 500). Specific examples of preferred compounds include ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, and tripropylene glycol, and other useful humectants include glycerin, sorbitol, and pentaerythritol. The amount of humectant used is generally in the range of 0.5% to 10% by mass, and more preferably 1% to 5% by mass, based on the total mass of the plate surface treatment agent.

[0039] The thixotropic agent of component (9) increases the viscosity when the viscosity of the liquid is reduced too much due to dynamic pressure, improving the workability when treating the plate surface with a sponge or the like. Suitable thixotropic agents include finely powdered silicic acid, pumice, calcium carbonate, zeolite, etc. The amount used is suitably in the range of 0.5% to 10% by mass, preferably 1% to 7% by mass, based on the total mass of the plate surface treatment agent.

[0040] The plate surface treatment agent is preferably prepared to be weakly acidic to neutral, and specifically, as described above, the pH is preferably 1.0 to 7.0, more preferably 4.0 to 7.0. A pH adjuster (component (10)) can be used to adjust the pH to this range. Examples of pH adjusters that can be used include phosphoric acid, nitric acid, sulfuric acid, and phosphorous acid, as well as organic carboxylic acids such as citric acid, acetic acid, malonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, butyric acid, maleic acid, and picolinic acid. Metal hydroxides, such as alkali hydroxides of alkali metals or alkaline earth metals, may also be used in combination. Examples of such metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide.

[0041] The plate surface treatment agent preferably contains, as a component thereof, (11) a salt that provides a cation. Salts that provide a cation include salts such as inorganic salts and organic salts, as well as hydroxides, and also include normal salts, hydrogen salts, basic salts, double salts, and complex salts. The salt that provides a cation can be selected, for example, from salts and hydroxides known as components of plate surface cleaners. The plate surface treatment agent preferably contains at least one cation derived from the salt described above, selected from potassium (K), cesium (Cs), and rubidium (Rb). That is, the plate surface treatment agent preferably contains a salt that provides at least one cation selected from potassium, cesium, and rubidium. Note that the cation derived from the salt contained in the plate surface treatment agent does not include cations derived from the water used to prepare the plate surface treatment agent.

[0042] The plate surface treatment agent preferably contains 0.5% by mass or more, preferably 1.0% by mass or more, and generally 10% by mass or less, of all cations derived from the salts contained therein, based on the total mass of the plate surface treatment agent, and it is preferred that 30% by mass or more of the total cations be at least one selected from potassium, cesium, and rubidium. All cations derived from salts contained in the plate surface treatment agent may be at least one selected from potassium, cesium, and rubidium.

[0043] In addition to the above components, preservatives (bactericides), colorants, etc. may be added. Examples of preservatives include phenol or its derivatives, formalin, imidazole derivatives, sodium dihydroacetate, 4-isothiazolin-3-one derivatives, benzisothiazolin-3-one derivatives, benztriazole derivatives, amidineguanidine derivatives, quaternary ammonium salts such as pyridine and quinolinic anthraquinone derivatives, diazine, triazole derivatives, oxazole, oxazine derivatives, and bromonitroalcohols such as 2-bromo-2-nitropropane-1,3-diol. The preservatives are preferably added in an amount that provides stable effectiveness against bacteria, mold, yeast, etc., typically in the range of 0.01% to 3% by weight based on the total weight of the plate surface treatment agent. It is also preferable to use two or more preservatives in combination to ensure effectiveness against various molds and bacteria.

[0044] (Method of manufacturing plate surface treatment agent) The plate surface treatment agent can be produced in the form of a general emulsified O / W (oil in water) emulsion (i.e., an emulsion) according to a conventional method. Specifically, the aqueous phase component and the oil phase component of the plate surface treatment agent are prepared separately, mixed, and passed through a homogenizer to form an emulsion.

[0045] The plate surface treatment agent can be preferably used in the development of an untreated lithographic printing plate precursor and for improving the ink receptivity of a lithographic printing plate used for printing. It can be preferably used in both on-press development and non-on-press development, but is particularly preferably used for on-press developable lithographic printing plate precursors.

[0046] (Developing method for lithographic printing plate precursor) A method for developing a lithographic printing plate precursor (hereinafter also referred to as "method for developing a lithographic printing plate precursor") that is one embodiment of the present disclosure includes the steps of applying a plate surface treatment agent different from the printing ink to a lithographic printing plate precursor that includes an image-wise exposed image recording layer before applying at least one of the printing ink and the fountain solution, and removing the image recording layer in non-image areas with the plate surface treatment agent, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment. The plate surface treatment agent used in the method for developing a lithographic printing plate precursor is the same as the plate surface treatment agent described above, and therefore, a description thereof will be omitted here.

[0047] In the development method for a lithographic printing plate precursor, the image recording layer in the non-image areas of a lithographic printing plate precursor containing an image-wise exposed image recording layer has been conventionally removed using at least one of printing ink and fountain solution. However, in this development method, the image recording layer in the non-image areas is removed using a specific plate surface treatment agent, which is an emulsion containing an aqueous phase and an oil phase, instead of fountain solution or the like. By using the above-described plate surface treatment agent in place of dampening water or the like for development, the plate surface treatment agent, which is an emulsion, contains, for example, a colorless ink medium. The extender pigment contained in the medium allows the oil-based printing ink to quickly blend into the image area after development, making it possible to improve ink-adhesion problems at the start of printing. Furthermore, in the printing process that follows development, poor ink-adhesion problems at the start of printing are improved, and the printing ink quickly adheres, thereby preventing an increase in paper waste. Furthermore, the extender pigment contributes to preventing an increase in paper waste by reducing the risk of impairing the color of the printing ink used in printing. According to the development method for a lithographic printing plate precursor, the hydrophilic layer on the plate surface is not removed during development, resulting in slow ink-adhesion with oil-based printing ink. This poor ink-adhesion is thought to be improved by the use of a plate surface treatment agent.

[0048] The developing method for the lithographic printing plate precursor may be carried out before the lithographic printing plate precursor is mounted on a printing press. Alternatively, the developing method for the lithographic printing plate precursor may be carried out after the lithographic printing plate precursor is mounted on a printing press, i.e., while the lithographic printing plate precursor is mounted on the printing press. The latter is a developing method called on-press development.

[0049] The developing method for a lithographic printing plate precursor can be applied to any type of lithographic printing plate precursor as long as the image recording layer in the non-image area is removed by a plate surface treatment agent during development. However, it is preferable that the lithographic printing plate precursor is an untreated plate. A specific method for developing the lithographic printing plate precursor will be described later.

[0050] (Method of manufacturing a lithographic printing plate) A method for producing a lithographic printing plate (hereinafter also referred to as a "method for producing a lithographic printing plate") according to one embodiment of the present disclosure includes the steps of imagewise exposing the image recording layer of a lithographic printing plate precursor to light, and removing the image recording layer in non-image areas with a plate surface treatment agent different from printing ink. The plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment. The method for producing a lithographic printing plate is a method for producing a lithographic printing plate in which a lithographic printing plate precursor is developed by the above-mentioned method for developing a lithographic printing plate precursor. A lithographic printing plate can be produced by developing the lithographic printing plate precursor by the above-mentioned method for developing a lithographic printing plate precursor. The plate surface treatment agent and the method for developing the lithographic printing plate precursor are the same as those described above, and therefore, a description thereof will be omitted here.

[0051] The lithographic printing plate manufactured by this method for manufacturing a lithographic printing plate has good ink receptivity at the start of printing, due to the adhesion of a medium containing an extender pigment to the image area, etc. Therefore, during printing, the printing ink is quickly absorbed, and an increase in paper waste can be suppressed. A specific method for producing a lithographic printing plate will be described later.

[0052] (lithographic printing method) A lithographic printing method (hereinafter also referred to as "printing method A") that is one embodiment of the present disclosure includes the steps of: exposing the image recording layer of a lithographic printing plate precursor to light in an imagewise manner; preparing a lithographic printing plate by removing the image recording layer in non-image areas with a plate surface treatment agent different from the printing ink; and mounting the lithographic printing plate on a printing press and printing using the lithographic printing plate mounted on the press and the printing ink, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment.

[0053] Printing method A is a printing method in which development is performed outside of a printing press. The plate surface treatment agent, the developing method for the lithographic printing plate precursor, and the manufacturing method for the lithographic printing plate are the same as those described above, and therefore will not be described here.

[0054] Furthermore, a lithographic printing method (hereinafter referred to as "printing method B") that is one embodiment of the present disclosure includes the steps of: exposing the image recording layer of a lithographic printing plate precursor to light in an imagewise manner; mounting the lithographic printing plate precursor on a printing press; and applying a plate surface treatment agent different from the printing ink before applying at least one of the printing ink and the dampening water; and removing the image recording layer in non-image areas with the plate surface treatment agent, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment.

[0055] Printing method B is an on-press development in which development is carried out on a printing press. The plate surface treatment agent, the developing method for the lithographic printing plate precursor, and the manufacturing method for the lithographic printing plate are the same as those described above, and therefore will not be described here. The specific printing method will be explained later.

[0056] (Flow of the lithographic printing plate precursor development method, lithographic printing plate manufacturing method, and printing method) Hereinafter, the specific flow of a method for developing a lithographic printing plate precursor using the plate surface treatment agent of the present disclosure, a method for producing a lithographic printing plate, and a lithographic printing method will be described using on-press development as an example.

[0057] <On-press development type lithographic printing plate original plate> An on-press development type lithographic printing plate precursor (also simply referred to as a "lithographic printing plate precursor") has a support and an image recording layer on the support, and the image recording layer preferably contains the following (1) or (2): (1) A borate compound represented by the following formula (1) and an electron-accepting polymerization initiator: (2) A borate compound represented by the following formula (1a):

[0058] [ka]

[0059] In formula (1), R 1 , R 2 , R 3 , and R 4 each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R 1 , R 2 , R 3 , and R 4 may each independently have a ring structure. 1 , R 2 , R 3 , and R 4 At least one of the M is different from the others. + represents a cation. (2) A borate compound represented by the following formula (1a):

[0060] [ka]

[0061] In formula (1a), R 1 , R 2 , R 3 , and R 4 each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R 1 , R 2 , R 3 , and R4 may each independently have a ring structure. 1 , R 2 , R 3 , and R 4 At least one of them is different from the others. + represents an iodonium cation. The lithographic printing plate precursor is preferably a negative-working lithographic printing plate precursor in which exposed areas are polymerized by infrared exposure.

[0062] Hereinafter, the above embodiment (1) of the image recording layer will also be referred to as "embodiment A." The above embodiment (2) of the image recording layer will also be referred to as "embodiment B." In the following description, unless otherwise specified, the borate compound represented by formula (1) and the borate compound represented by formula (1a) are also collectively referred to as "specific borate compounds."

[0063] (Image recording layer) The image recording layer in the lithographic printing plate precursor is preferably a water-soluble or water-dispersible negative image recording layer. From the viewpoint of on-press developability, the image recording layer in the lithographic printing plate precursor is preferably such that the unexposed areas of the image recording layer are removable with the above-mentioned plate surface treatment agent. The image recording layer may also be removable with at least one of fountain solution and printing ink.

[0064] Each component contained in the image recording layer will be described in detail below.

[0065] [Aspect A] <Borate Compound Represented by Formula (1) (Specific Borate Compound)> The image recording layer in embodiment A contains a borate compound represented by the following formula (1). The borate compound represented by formula (1) is used as an electron-donating polymerization initiator in the image recording layer. The specific borate compound is a compound that generates polymerization initiating species such as radicals or cations upon exposure to the energy of light, heat, or both.

[0066] [ka]

[0067] In formula (1), R 1 , R 2 , R 3 , and R 4 each independently represents an unsubstituted or substituted alkyl group, an unsubstituted or substituted aryl group, an unsubstituted or substituted alkenyl group, or an unsubstituted or substituted alkynyl group; R 1 , R 2 , R 3 , and R 4 teeth 、 Each of them may independently have a ring structure. 1 , R 2 , R 3 , and R 4 At least one of them is different from the others. + represents a cation.

[0068] R 1 , R 2 , R 3 , or R 4 Examples of the alkyl group represented by the formula (I) include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, s-butyl, t-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, and 2-norbornyl. The alkyl group may be linear, branched, or have a ring structure.

[0069] Also, R 1 , R 2 , R 3 , or R 4The alkyl group represented by the formula (I) may have a substituent. Examples of the substituent of the alkyl group include a halogen atom, an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, a sulfonyl group, an amino group, an amide group, and combinations thereof. R 1 , R 2 , R 3 , or R 4 The alkyl groups represented by the formula (I) are each independently preferably an unsubstituted, linear or branched alkyl group having 1 to 12 carbon atoms, more preferably an unsubstituted, linear or branched alkyl group having 1 to 10 carbon atoms, and even more preferably an unsubstituted, linear or branched alkyl group having 1 to 6 carbon atoms. Of these, from the viewpoint of suppressing development defects over time, branched, unsubstituted alkyl groups are particularly preferred.

[0070] R 1 , R 2 , R 3 , or R 4 Examples of the aryl group represented by the formula (I) include aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenabutenyl group, and a fluorenyl group. Examples of the substituent on the aryl group include the above-mentioned substituents on the alkyl group. R 1 , R 2 , R 3 , or R 4 The aryl groups represented by the following formula (I) are each independently preferably an unsubstituted or substituted phenyl group.

[0071] R 1 , R 2 , R 3 , or R 4 Examples of the alkenyl group represented by the formula (I) include alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, a 1-propenyl group, a 1-butenyl group, a cinnamyl group, and a 2-chloro-1-ethenyl group. R 1 , R 2 , R 3 , or R4 The alkenyl group represented by the formula (I) may be linear, branched, or have a ring structure. Examples of the substituent on the alkenyl group include the above-mentioned substituents on the alkyl group. R 1 , R 2 , R 3 , or R 4 The alkenyl groups represented by the following formula are each independently preferably an unsubstituted alkenyl group having 2 to 20 carbon atoms.

[0072] R 1 , R 2 , R 3 , or R 4 Examples of the alkynyl group represented by the formula (I) include alkynyl groups having 2 to 20 carbon atoms, such as an ethynyl group, a 1-propynyl group, a 1-butynyl group, a trimethylsilylethynyl group, and a phenylethynyl group. The alkynyl group may be linear or branched.

[0073] Among the above functional groups, R 1 , R 2 , R 3 , and R 4 are each preferably independently a substituted or unsubstituted aryl group. R 1 , R 2 , R 3 , and R 4 However, when each of the groups is independently a substituted or unsubstituted aryl group, the HOMO potential of the borate compound is lowered, improving the film stability of the image recording layer, thereby extending the life of the lithographic printing plate.

[0074] R 1 , R 2 , R 3 , and R 4 It is preferable that at least one of R is different from the others. 1 , R 2 , R 3 , and R 4 Among them, R 1 , R2 , and R 3 are identical and R 4 But R 1 , R 2 , and R 3 This makes it possible to obtain a high-purity borate compound. Furthermore, the generation of radicals can be suppressed, making it difficult for side reactions to occur. In the above case, R 1 , R 2 , and R 3 However, it is more preferably a phenyl group.

[0075] Also, R 1 , R 2 , R 3 , and R 4 It is also preferred that at least two of the groups be phenyl groups and at least one be a substituted aryl group. Furthermore, R 1 , R 2 , and R 3 is a phenyl group, and R 4 is more preferably an aryl group having a substituent (i.e., a substituted aryl group).

[0076] R 1 , R 2 , and R 3 is a phenyl group, and R 4 When the aryl group has a substituent, the total number of carbon atoms and oxygen atoms in the substituent of the aryl group is preferably 2 or more, and more preferably 3 or more. The upper limit is, for example, 8 or less.

[0077] The compound represented by formula (1) is preferably a compound represented by the following formula (II):

[0078] [ka]

[0079] In formula (II), R represents an alkyl group having two or more carbon atoms, or an alkoxy group having two or more carbon atoms and oxygen atoms in total. + represents an iodonium cation or an infrared absorbing dye cation.

[0080] In formula (II), the alkyl group represented by R preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 2 to 4 carbon atoms. Examples of the alkyl group include an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, an isobutyl group, a sec-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a neopentyl group, and an isopropyl group. The alkyl group may be linear, branched, or have a ring structure.

[0081] In formula (II), the alkoxy group for R preferably has 2 to 4 carbon atoms and oxygen atoms in total. Examples of the alkoxy group include a methoxy group, an n-propoxy group, an isopropoxy group, and an n-butoxy group. The alkoxy group may be linear or branched.

[0082] In addition, in formula (1), R 1 , R 2 , or R 3 The phenyl group represented by the formula (I) is preferably a phenyl group substituted with an electron-withdrawing group. Examples of the electron-withdrawing group include a halogen atom and a fluoroalkyl group, among which a fluorine atom, a chlorine atom, and a fluoroalkyl group having 1 to 3 carbon atoms are preferred.

[0083] In formula (1), R 4The substituent of the aryl group represented by the formula (I) is preferably an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, or an amide group, more preferably an alkyl group, an alkenyl group, or an alkoxy group, and still more preferably an alkyl group or an alkoxy group.

[0084] The compound represented by the above formula (1) may be a compound represented by the following formula (I):

[0085] [ka]

[0086] In formula (I), R represents a group having a total number of carbon atoms and oxygen atoms of 2 or more, X represents a halogen atom, an alkyl group, or an alkoxy group, and the sum of the Hammett values ​​of R and X is −0.09 to 0.09. + Li + , Na + , K. + , iodonium cation, or infrared absorbing dye cation.

[0087] Examples of R in formula (I) include an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, a sulfonyl group, an amide group, and combinations thereof.

[0088] In formula (I), examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, and a bromine atom. In formula (I), the alkyl group and alkoxy group represented by X are the same as the alkyl group and alkoxy group in formula (II) above, and preferred embodiments are also the same.

[0089] In particular, R in formula (I) is preferably an alkyl group having 2 to 4 carbon atoms or an alkoxy group having 2 to 4 carbon atoms in total, and more preferably an alkyl group having 2 to 4 carbon atoms. In the above cases, X is preferably a halogen atom. Here, the halogen atoms may be independently different halogen atoms, but it is more preferable that all of them are the same halogen atom.

[0090] In formula (I), the sum of the Hammett σ values ​​of the substituents (R and X) introduced into the aryl skeleton is preferably within the range of −0.2 to 0.2, more preferably −0.09 to 0.09. By keeping it within this range, the HOMO potential can be adjusted to a desired range, and an excellent balance between the film stability and printing durability of the image recording layer can be achieved. The total Hammett σ value of the substituents introduced into the aryl skeleton was calculated using the values ​​listed in the reference "Chemical Seminar 10: Hammett Side - Structure and Reactivity" (by Naoki Inamoto, Maruzen Co., Ltd., published in June 1983).

[0091] M in Equation (1) + represents a cation, i.e., M + is the counter cation of the boron anion. + is not particularly limited as long as it is a cation that can neutralize the boron anion, but from the viewpoint of suppressing staining during development, it is preferably at least one selected from the group consisting of inorganic cations, iodonium cations, and infrared absorbing dye cations. One type of counter cation may be used alone, or two or more types may be used in combination. In formula (I), M + Li + , Na + , K. + , iodonium cation, or infrared absorbing dye cation. + represents an iodonium cation or an infrared absorbing dye cation.

[0092] When two or more counter cations are used, the combination is not particularly limited, but is preferably a combination of inorganic cations, a combination of iodonium cations, or a combination of infrared absorbing dye cations, and more preferably a combination of iodonium cations or a combination of infrared absorbing dye cations, which further improves the ability to suppress development defects over time and printing durability.

[0093] The iodonium cation may be the cation moiety of an electron-accepting polymerization initiator described below, and the infrared absorbing dye cation may be the cation moiety of an infrared absorber described below. In the image recording layer, the cationic moiety of the electron-donating polymerization initiator and the cationic moiety of the infrared absorbing agent can bond with the anionic moiety of the borate compound represented by formula (1) to form a salt.

[0094] Examples of inorganic cations include lithium cations, sodium cations, potassium cations, calcium cations, and magnesium cations. Among these, sodium cations, lithium cations, and potassium cations are preferred, and sodium cations are more preferred.

[0095] The iodonium cation can be the cation moiety of an electron-accepting polymerization initiator described below. Specific examples are shown in the following structural formulas. In the following structural formulas, Me represents a methyl group. Note that the iodonium cation is not limited to the following specific examples.

[0096] [ka]

[0097] The infrared absorbing dye cation can be the cation moiety of the infrared absorber described below. Specific examples are shown in the following structural formulas. In the following structural formulas, Me represents a methyl group, and Bu represents a butyl group. Note that the infrared absorbing dye cation is not limited to the following specific examples.

[0098] [ka]

[0099] [ka]

[0100] The highest occupied molecular orbital (HOMO) of the specific borate compound is preferably −6.0 eV or more, more preferably −5.95 eV or more, and even more preferably −5.93 eV or more, from the viewpoints of chemical resistance and printing durability. The upper limit is preferably −5.00 eV or less, more preferably −5.40 eV or less, and particularly preferably −5.93 eV to −5.70 eV.

[0101] The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are calculated by the following method. First, the counter anion in the compound to be calculated is ignored. The quantum chemical calculation software Gaussian09 is used, and structural optimization is performed using DFT (B3LYP / 6-31G(d)). MO (molecular orbital) energy calculations are performed using DFT (B3LYP / 6-31+G(d,p) / CPCM(solvent=methanol)) on the structure obtained by the above structural optimization. The MO energy Ebare (unit: hartree) obtained in the above MO energy calculation is converted to Escaled (unit: eV) to be used as the HOMO and LUMO values ​​using the following formula: Escaled=0.823168×27.2114×Ebare-1.07634 Note that 27.2114 is simply a coefficient for converting hartrees to eV, and 0.823168 and -1.07634 are adjustment coefficients that determine the HOMO and LUMO of the compound being calculated so that the calculation matches the measured values.

[0102] Preferred specific examples of the borate compound represented by formula (1) (hereinafter also referred to as specific borate compound) are shown below, but are not limited to these: In the following structural formula, Me represents a methyl group.

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106] [ka]

[0107] [ka]

[0108] [ka]

[0109] [Aspect B] <Borate compound represented by formula (1a)> The image recording layer in embodiment B contains a borate compound represented by the following formula (1a). The borate compound represented by formula (1a) is one embodiment of the borate compound represented by formula (1), and is used as an electron-donating polymerization initiator in the image recording layer.

[0110] [ka]

[0111] In formula (1a), R1 , R 2 , R 3 , and R 4 each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R 1 , R 2 , R 3 , and R 4 may each independently have a ring structure. 1 , R 2 , R 3 , and R 4 At least one of them is different from the others. + represents an iodonium cation.

[0112] In formula (1a), R 1 , R 2 , R 3 , and R 4 is R in the above formula (1). 1 , R 2 , R 3 , and R 4 The same applies to the preferred embodiments.

[0113] In formula (1a), Ma + represents an iodonium cation. That is, the iodonium cation is a counter cation of the boron anion. The iodonium cation is not particularly limited as long as it is a cation that can neutralize the boron anion. Only one type of iodonium cation may be contained, or two or more types may be contained.

[0114] Examples of iodonium cations include those represented by the structural formulas explained in the section on embodiment A above.

[0115] The highest occupied molecular orbital (HOMO) of the borate compound represented by formula (1a) has the same preferred embodiments as the borate compound represented by formula (1). The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are calculated in the same manner as above.

[0116] Preferred specific examples of the borate compound represented by formula (1a) include, but are not limited to, the above-mentioned B-18, B-19, B-31 to B-33, B-45, and B-46.

[0117] The image recording layer may contain only one type of specific borate compound, or may contain two or more types. From the viewpoints of color development, color development over time after exposure, developability, and suppression of development defects over time in the resulting lithographic printing plate, the content of the specific borate compound is preferably 0.01% by mass to 30% by mass, more preferably 0.05% by mass to 25% by mass, and even more preferably 0.1% by mass to 20% by mass, in terms of the weight of the anion moiety of the specific borate compound, relative to the total mass of the image recording layer.

[0118] The specific borate compound may be a synthetic product. When preparing a specific borate compound by synthesis, in addition to the target borate compound, borate compounds with different structures as isomers may be by-produced. Furthermore, the obtained borate compound may contain small amounts of impurities derived from various components such as solvents used in the synthesis. According to the investigations of the present inventors, even if the obtained borate compound contains at least one of a borate compound having a different structure from that of the target borate compound and impurities, the total content thereof is very small. Therefore, it has been confirmed that even if the synthesized borate compound is directly applied to an image recording layer coating liquid without being subjected to a special purification step such as removing impurities, the performance of the obtained lithographic printing plate precursor is not affected.

[0119] Therefore, the image recording layer may contain at least one of borate compounds other than the specific borate compound and impurities unavoidable in the production process. Examples of at least one of borate compounds other than the specific borate compound and impurities unavoidable in the production process include starting materials used in the synthesis reaction, catalysts, by-products generated by the synthesis reaction, borate compounds other than the specific borate compound, etc.

[0120] <Electron-accepting polymerization initiator> The image-recording layer in embodiment A contains an electron-accepting polymerization initiator. The image recording layer in Aspect B preferably contains an electron-accepting polymerization initiator. The electron-accepting polymerization initiator contained in the image recording layer in Aspect B does not include the borate compound represented by Formula (1a). In one embodiment, the electron-accepting polymerization initiator is a compound that generates a polymerization initiating species such as a radical by accepting one electron through intermolecular electron transfer when electrons of an infrared absorber are excited by exposure to infrared light. The electron-accepting polymerization initiator is a compound that generates polymerization initiating species such as radicals or cations by the energy of light, heat, or both, and can be appropriately selected from known thermal polymerization initiators, compounds having a bond with small bond dissociation energy, photopolymerization initiators, and the like. As the electron-accepting polymerization initiator, a radical polymerization initiator is preferred, and an onium salt compound is more preferred. The electron-accepting polymerization initiator is preferably an infrared-sensitive polymerization initiator. Examples of the electron-accepting radical polymerization initiator include (a) organic halides, (b) carbonyl compounds, (c) azo compounds, (d) organic peroxides, (e) metallocene compounds, (f) azide compounds, (g) hexaarylbiimidazole compounds, (i) disulfone compounds, (j) oxime ester compounds, and (k) onium salt compounds.

[0121] (a) As the organic halide, for example, the compounds described in paragraphs 0022 to 0023 of JP-A No. 2008-195018 are preferred. (b) As the carbonyl compound, for example, the compound described in paragraph 0024 of JP-A No. 2008-195018 is preferable. (c) As the azo compound, for example, the azo compounds described in JP-A-8-108621 can be used. (d) As the organic peroxide, for example, the compound described in paragraph 0025 of JP-A No. 2008-195018 is preferable. (e) As the metallocene compound, for example, the compound described in paragraph 0026 of JP-A No. 2008-195018 is preferred. (f) Examples of the azide compounds include compounds such as 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone. (g) Preferred hexaarylbiimidazole compounds include, for example, compounds described in paragraph 0027 of JP-A No. 2008-195018. (i) Examples of disulfone compounds include compounds described in JP-A Nos. 61-166544 and 2002-328465. (j) Preferred oxime ester compounds are, for example, compounds described in paragraphs 0028 to 0030 of JP-A No. 2008-195018.

[0122] Among the electron-accepting polymerization initiators, preferred are oxime ester compounds and onium salt compounds from the viewpoint of curability. Among them, preferred are iodonium salt compounds, sulfonium salt compounds, and azinium salt compounds from the viewpoint of printing durability, more preferred are iodonium salt compounds or sulfonium salt compounds, and particularly preferred are iodonium salt compounds. Specific examples of these compounds are shown below, but are not limited thereto.

[0123] Preferred examples of iodonium salt compounds include diaryliodonium salt compounds, and more preferred are diphenyliodonium salt compounds substituted with electron-donating groups such as alkyl groups or alkoxy groups, and more preferred are asymmetric diphenyliodonium salt compounds. Specific examples include diphenyliodonium hexafluorophosphate, 4-methoxyphenyl-4-(2-methylpropyl)phenyliodonium hexafluorophosphate, 4-(2-methylpropyl)phenyl-p-tolyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium tetrafluoroborate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium hexafluorophosphate, and bis(4-t-butylphenyl)iodonium hexafluorophosphate.

[0124] Preferred examples of sulfonium salt compounds include triarylsulfonium salt compounds, particularly triarylsulfonium salt compounds in which electron-withdrawing groups, such as groups on the aromatic ring, are at least partially substituted with halogen atoms, and more preferably triarylsulfonium salt compounds in which the total number of halogen atoms substituted on the aromatic ring is 4 or more. Specific examples include triphenylsulfonium hexafluorophosphate, triphenylsulfonium benzoylformate, bis(4-chlorophenyl)phenylsulfonium benzoylformate, bis(4-chlorophenyl)-4-methylphenylsulfonium tetrafluoroborate, tris(4-chlorophenyl)sulfonium 3,5-bis(methoxycarbonyl)benzenesulfonate, tris(4-chlorophenyl)sulfonium hexafluorophosphate, and tris(2,4-dichlorophenyl)sulfonium hexafluorophosphate.

[0125] As the counter anion of the iodonium salt compound and the sulfonium salt compound, a sulfonamide anion or a sulfonimide anion is preferred, and a sulfonimide anion is more preferred. The sulfonamide anion is preferably an arylsulfonamide anion. The sulfonimide anion is preferably a bisarylsulfonimide anion. Specific examples of sulfonamide anions or sulfonimide anions are shown below, but are not limited to these. In the following specific examples, Ph represents a phenyl group, Me represents a methyl group, and Et represents an ethyl group.

[0126] [ka]

[0127] The electron-accepting polymerization initiator preferably contains a compound A represented by the following formula (Ia) and one or more compounds B selected from the group consisting of compounds represented by the following formula (Ib) or (Ic):

[0128] [ka]

[0129] In formulas (Ia) to (Ic), R1, R2, R3, R4, R5, and R6 each independently represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group having 2 to 9 carbon atoms; at least one of R3 and R4 is different from R1 or R2; the difference between the total number of carbon atoms in R1 and R2 and the total number of carbon atoms in R3 and R4 is 0 to 4 (i.e., 0, 1, 2, 3, or 4); the difference between the total number of carbon atoms in R1 and R2 and the total number of carbon atoms in R5 and R6 is 0 to 4; and X1, X2, and X3 are the same or different anions.

[0130] R1, R2, R3, R4, R5, and R6 are each independently preferably a substituted or unsubstituted alkyl group having 2 to 9 carbon atoms or a substituted or unsubstituted alkoxy group having 2 to 9 carbon atoms, more preferably a substituted or unsubstituted alkyl group having 3 to 6 carbon atoms or a substituted or unsubstituted alkoxy group having 3 to 6 carbon atoms, and even more preferably a substituted or unsubstituted alkyl group having 3 to 6 carbon atoms. The alkyl and alkoxy groups may be linear or branched, but are preferably branched. Examples of the substituted or unsubstituted alkyl group include an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, a t-pentyl group, a sec-pentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, a sec-hexyl group, a t-hexyl group, an n-heptyl group, an n-octyl group, an isooctyl group, a 2-ethylhexyl group, and an n-nonyl group. Examples of the substituted or unsubstituted alkoxy group include an ethoxy group, an n-propoxy group, an iso-propoxy group, a t-butoxy group, an n-butoxy group, and an n-octyloxy group.

[0131] The above X1, X2 and X3 are ClO4 - , PF6 - , BF4 - , SbF6 - , CH3SO3 - , CF3SO3 - , C6H5SO3 - , CH3C6H4SO3 - , HOC6H4SO3 - , ClC6H4SO3 - and the borate anion represented by the following structure (Id):

[0132] B - (R 1 )(R 2 )(R 3 )(R 4 ) Formula (Id)

[0133] In formula (Id), R1 , R 2 , R 3 and R 4 R each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group (including a halogen-substituted aryl group), a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group. 1 , R 2 , R 3 and R 4 may be linked together to form a substituted or unsubstituted heterocycle containing a boron atom, the resulting heterocycle having up to seven carbon, nitrogen, oxygen, or nitrogen atoms. R 1 , R 2 , R 3 and R 4 The substituent in the formula (I) may be a chlorine atom, a fluorine atom, a nitro group, an alkyl group, an alkoxy group, or an acetoxy group.

[0134] Above R 1 , R 2 , R 3 and R 4 Preferably, all of the groups are substituted or unsubstituted aryl groups, and more preferably all are unsubstituted phenyl groups.

[0135] At least one of X1, X2, and X3 is preferably a tetraarylborate anion containing the same or different aryl groups, more preferably one or more is a tetraphenylborate anion, and further preferably each of X1, X2, and X3 is a tetraphenylborate anion.

[0136] In a preferred embodiment, compound B includes a compound represented by formula (Ic), in which R1 is the same as R5 and R2 is the same as R6. In particular, it is preferred that R1 is the same as R2, and for example, both R1 and R2 are an iso-propyl group, an iso-butyl group, or a t-butyl group.

[0137] In another preferred embodiment, compound B includes a compound represented by formula (Ib), in which R1 is the same as R2, and R3 is the same as R4. In this case, it is preferable that both R1 and R2 are an isopropyl group, an isobutyl group, or a t-butyl group. It is also preferable that the difference in the number of carbon atoms between R1 and R3 is 1 or 2.

[0138] Compound B may be a mixture of a compound represented by formula (Ib) and a compound represented by formula (Ic).

[0139] The compounds represented by formula (Ia) to formula (Ic) may be obtained from Sigma-Aldrich or the like, or may be synthesized using known synthesis methods and readily available starting materials.

[0140] The molar ratio of compound A to compound B is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0141] Furthermore, from the viewpoints of developability and printing durability of the resulting lithographic printing plate, the electron-accepting polymerization initiator may contain a compound represented by formula (II) described in paragraphs 0186 to 0197 of WO 2022 / 019217.

[0142] The lowest unoccupied molecular orbital (LUMO) of the electron-accepting polymerization initiator is preferably −3.00 eV or less, more preferably −3.02 eV or less, from the viewpoint of improving sensitivity and preventing plate skipping. The lower limit is preferably −3.80 eV or more, and more preferably −3.60 eV or more.

[0143] The electron-accepting polymerization initiator may be used alone or in combination of two or more kinds. The content of the electron-accepting polymerization initiator is preferably 0.1% by mass to 50% by mass, more preferably 0.5% by mass to 30% by mass, and particularly preferably 0.8% by mass to 20% by mass, relative to the total mass of the image recording layer.

[0144] <Infrared absorber> The image recording layer preferably contains an infrared absorbing agent. The infrared absorbing agent is not particularly limited, and examples thereof include pigments and dyes. As the dye to be used as the infrared absorber, commercially available dyes and known dyes described in literature such as "Dye Handbook" (edited by the Organic Synthetic Chemistry Society, published in 1970) can be used. Specific examples include 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, and metal thiolate complex dyes.

[0145] Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Furthermore, cyanine dyes and indolenine cyanine dyes are also preferred. Of these, cyanine dyes are particularly preferred.

[0146] The infrared absorber is preferably a cationic polymethine dye having an oxygen or nitrogen atom at the meso position. Preferred examples of the cationic polymethine dye include cyanine dyes, pyrylium dyes, thiopyrylium dyes, and azulenium dyes. From the viewpoints of availability, solvent solubility during the introduction reaction, and the like, cyanine dyes are preferred.

[0147] Specific examples of cyanine dyes include the compounds described in paragraphs

[0017] to

[0019] of JP-A No. 2001-133969, the compounds described in paragraphs

[0016] to

[0021] of JP-A No. 2002-023360, and the compounds described in paragraphs

[0012] to

[0037] of JP-A No. 2002-040638, preferably the compounds described in paragraphs

[0034] to

[0041] of JP-A No. 2002-278057, and paragraphs

[0080] to

[0086] of JP-A No. 2008-195018, and particularly preferably the compounds described in paragraphs

[0035] to

[0043] of JP-A No. 2007-90850, and the compounds described in paragraphs

[0105] to

[0113] of JP-A No. 2012-206495. In addition, the compounds described in paragraphs 0008 to 0009 of JP-A No. 5-5005 and paragraphs 0022 to 0025 of JP-A No. 2001-222101 can also be preferably used. As the pigment, the compounds described in paragraphs 0072 to 0076 of JP-A No. 2008-195018 are preferred.

[0148] The infrared absorber preferably contains an infrared absorber that decomposes upon exposure to infrared rays (decomposable infrared absorber), and more preferably contains a decomposable color-forming infrared absorber. It is presumed that by using a decomposable infrared absorber as the infrared absorber, the infrared absorber or its decomposition products promote polymerization, and further, the decomposition products of the infrared absorber interact with the polymerizable compound, resulting in excellent printing durability. The decomposable infrared absorber is preferably an infrared absorber that has the function of absorbing infrared rays, decomposing, and developing color when exposed to infrared rays. Hereinafter, the colored compound formed when the decomposable infrared absorber absorbs infrared rays and decomposes upon exposure to infrared rays will also be referred to as a "colored body of the decomposable infrared absorber." The decomposable infrared absorber preferably has a function of absorbing infrared rays upon exposure to infrared rays and converting the absorbed infrared rays into heat. The decomposable infrared absorbent may be any that absorbs and decomposes at least a portion of light in the infrared wavelength range (wavelength 750 nm to 1 mm), but is preferably an infrared absorbent having a maximum absorption wavelength in the wavelength range of 750 nm to 1,400 nm, and more preferably an infrared absorbent having a maximum absorption wavelength in the wavelength range of 760 nm to 900 nm. More specifically, the decomposable infrared absorber is preferably a compound that decomposes upon exposure to infrared light to produce a compound having a maximum absorption wavelength in the wavelength range of 500 nm to 600 nm.

[0149] The decomposable infrared absorber is preferably an infrared absorber that decomposes due to heat, electron transfer, or both caused by infrared exposure, and more preferably an infrared absorber that decomposes due to electron transfer caused by infrared exposure. Here, "decomposes due to electron transfer" means that electrons excited from the HOMO (highest occupied molecular orbital) to the LUMO (lowest unoccupied molecular orbital) of the decomposable infrared absorber by infrared exposure undergo intramolecular electron transfer to an electron-accepting group in the molecule (for example, a group having an electric potential close to that of the LUMO), resulting in decomposition.

[0150] The infrared absorber preferably contains a compound represented by the following formula 1:

[0151] [ka]

[0152] In Formula 1, R1 and R2 each independently represent a hydrogen atom or an alkyl group, and R1 and R2 may be bonded to each other to form a ring; R3 to R6 each independently represent a hydrogen atom or an alkyl group; R7 and R8 each independently represent an alkyl group or an aryl group; Y1 and Y2 each independently represent an oxygen atom, a sulfur atom, -NR0-, or a dialkylmethylene group; R0 represents a hydrogen atom, an alkyl group, or an aryl group; Ar1 ​​and Ar2 each independently represent a group forming a benzene ring or a naphthalene ring which may have a group represented by Formula 2 described below; and A1 is -NR9R 10, -X1-L1 or a group represented by formula 2 described below, R9 and R 10 each independently represents an alkyl group, an aryl group, an alkoxycarbonyl group, or an arylsulfonyl group; X1 represents an oxygen atom or a sulfur atom; L1 represents a hydrocarbon group, a heteroaryl group, or a group whose bond to X1 is cleaved by heat or exposure to infrared light; Za represents a counter ion that neutralizes the charge; and at least one of Ar1 and Ar2 has a group represented by the following formula 2: -X expression 2 In Formula 2, X represents a halogen atom, -C(=O)-X2-R 11 , -C(=O)-NR 12 R 13 , -OC(=O)-R 14 , -CN, -SO2NR 15 R 16 or a perfluoroalkyl group, X2 represents a single bond or an oxygen atom, R 11 and R 14 each independently represents an alkyl group or an aryl group, R 12 , R 13 , R 15 and R 16 each independently represents a hydrogen atom, an alkyl group, or an aryl group.

[0153] Ar1 and Ar2 each independently represent a group forming a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have a substituent other than -X. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, and a combination thereof, but an alkyl group is preferred. In addition, in Formula 1, at least one of Ar1 and Ar2 has a group represented by the above Formula 2, and from the viewpoints of printing durability and visibility, it is preferable that both Ar1 and Ar2 have a group represented by the above Formula 2.

[0154] X in formula 2 is a halogen atom, -C(=O)-X2-R 11 , -C(=O)-NR 12R 13 , -OC(=O)-R 14 , -CN, -SO2NR 15 R 16 or a perfluoroalkyl group, and from the viewpoints of printing durability, visibility, and stability over time, a halogen atom, —C(═O)—X2—R 11 , -C(=O)-NR 12 R 13 , -OC(=O)-R 14 , CN, or -SO2NR 15 R 16 is preferably a halogen atom, —C(═O)—OR 11 , -C(=O)-NR 12 R 13 , or -OC(=O)-R 14 is preferably a halogen atom, —C(═O)—OR 11 , or -OC(=O)-R 14 It is more preferable that the group is a fluorine atom, a chlorine atom, a bromine atom, or —C(═O)OR 17 is particularly preferred, and a chlorine atom or a bromine atom is most preferred.

[0155] X2 represents a single bond or an oxygen atom, and is preferably an oxygen atom. R 11 and R 14 each independently represents an alkyl group or an aryl group, preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms. R 12 , R 13 , R 15 and R 16 each independently represents a hydrogen atom, an alkyl group, or an aryl group, and is preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and even more preferably an alkyl group having 1 to 12 carbon atoms. R 17represents an alkyl group or an aryl group, preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms.

[0156] A1 is -NR9R 10 , -X1-L1 or -X, and from the viewpoint of printing durability, visibility and stability over time, -NR9R 10 or -X1-L1, and -NR 18 R 19 , -SR 20 It is more preferable that: Furthermore, from the viewpoints of plate skip suppression, GLV suitability, and printing durability, A1 is preferably -X, more preferably a halogen atom, further preferably a chlorine atom or a bromine atom, and particularly preferably a chlorine atom. R9 and R 10 each independently represents an alkyl group, an aryl group, an alkoxycarbonyl group, or an arylsulfonyl group, and is preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms. X1 represents an oxygen atom or a sulfur atom, and when L1 is a hydrocarbon group or a heteroaryl group, it is preferably a sulfur atom, and L1 is preferably a group whose bond to X1 is cleaved by heat or exposure to infrared light. L1 represents a hydrocarbon group, a heteroaryl group, or a group whose bond to X1 is cleaved by heat or infrared exposure. From the viewpoint of printing durability, L1 is preferably a hydrocarbon group or a heteroaryl group, more preferably an aryl group or a heteroaryl group, and even more preferably a heteroaryl group. From the viewpoints of visibility and prevention of fading over time, L1 is preferably a group whose bond to X1 is cleaved by exposure to heat or infrared rays. The group whose bond to X1 is cleaved by heat or exposure to infrared rays will be described later. R 18 and R 19each independently represents an aryl group, preferably an aryl group having 6 to 20 carbon atoms, more preferably a phenyl group. R 20 represents a hydrocarbon group or a heteroaryl group, preferably an aryl group or a heteroaryl group, and more preferably a heteroaryl group.

[0157] L1 and R 20 Preferred examples of the heteroaryl group in the formula include the following groups:

[0158] [ka]

[0159] R1~R 10 The alkyl group in R0 is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear, branched, or have a ring structure. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group. Among these alkyl groups, a methyl group, an ethyl group, a propyl group, or a butyl group is particularly preferred.

[0160] The alkyl group may have a substituent, such as an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, or a combination thereof.

[0161] R9, R 10 , R 18 , R 19 The aryl group in R0 is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent, such as an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, or a combination thereof. Specific examples of the aryl group include a phenyl group, a naphthyl group, a p-tolyl group, a p-chlorophenyl group, a p-fluorophenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, a p-methylthiophenyl group, and a p-phenylthiophenyl group. Of these aryl groups, a phenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, or a naphthyl group is preferred.

[0162] It is preferred that R1 and R2 are linked to form a ring. When R1 and R2 are bonded to form a ring, the ring is preferably a 5- or 6-membered ring, more preferably a 6-membered ring. In addition, the ring formed by bonding R1 and R2 is preferably a hydrocarbon ring which may have an ethylenically unsaturated bond.

[0163] Y1 and Y2 each independently represent an oxygen atom, a sulfur atom, -NR0- or a dialkylmethylene group, preferably -NR0- or a dialkylmethylene group, and more preferably a dialkylmethylene group. R0 represents a hydrogen atom, an alkyl group or an aryl group, and is preferably an alkyl group.

[0164] It is preferred that R7 and R8 are the same group. Furthermore, R7 and R8 are each preferably a linear alkyl group or an alkyl group having a terminal sulfonate group, and more preferably a methyl group, an ethyl group, or a butyl group having a terminal sulfonate group. The counter cation of the sulfonate group may be the cation on the nitrogen atom in formula 1, or may be an alkali metal cation or an alkaline earth metal cation. Furthermore, in order to improve the water solubility of the compound represented by formula 1, R7 and R8 are each independently In particular, it is preferably an alkyl group having an anionic structure, more preferably an alkyl group having a carboxylate group or a sulfonate group, and even more preferably an alkyl group having a sulfonate group at the terminal. Furthermore, in order to lengthen the maximum absorption wavelength of the compound represented by Formula 1 and from the viewpoints of visibility and printing durability of the lithographic printing plate, R7 and R8 are each independently preferably an alkyl group having an aromatic ring, more preferably an alkyl group having an aromatic ring at the terminal, and particularly preferably a 2-phenylethyl group, a 2-naphthalenylethyl group, or a 2-(9-anthracenyl)ethyl group.

[0165] R3 to R6 each independently represent a hydrogen atom or an alkyl group, and are preferably a hydrogen atom.

[0166] Furthermore, from the viewpoints of stability over time and printing durability, the compound represented by Formula 1 preferably has one or more halogen atoms, more preferably at least one selected from the group consisting of A1, Ar1, and Ar2 has one or more halogen atoms, and particularly preferably A1, Ar1, and Ar2 each have one or more halogen atoms. Furthermore, from the viewpoints of stability over time and printing durability, the compound represented by Formula 1 more preferably has two or more halogen atoms, even more preferably has three or more halogen atoms, and particularly preferably has three to six halogen atoms. The halogen atom is preferably a chlorine atom or a bromine atom. Furthermore, from the viewpoints of stability over time and printing durability, the compound represented by Formula 1 preferably has a halogen atom in at least one of Ar1 and Ar2, more preferably has a chlorine atom or a bromine atom in at least one of Ar1 and Ar2, and particularly preferably has a bromine atom in at least one of Ar1 and Ar2.

[0167] Za represents a counter ion that neutralizes the charge, and examples of an anionic species include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a perchlorate ion, a sulfonamide anion, and a sulfonimide anion. Examples of a cationic species include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, or a sulfonium ion, more preferably a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion, still more preferably a sodium ion, a potassium ion, or an ammonium ion, and particularly preferably a sodium ion, a potassium ion, or a trialkylammonium ion. Among these, from the viewpoints of printing durability and visibility, Za is preferably an organic anion containing a carbon atom, more preferably a sulfonate ion, a carboxylate ion, a sulfonamide anion, or a sulfonimide anion, still more preferably a sulfonamide anion or a sulfonimide anion, and particularly preferably a sulfonimide anion. R1 to R8, R0, A1, Ar1, Ar2, Y1, and Y2 may have an anionic structure or a cationic structure. When all of R1 to R8, R0, A1, Ar1, Ar2, Y1, and Y2 are electrically neutral groups, Za is a monovalent counter anion. However, when, for example, R1 to R8, R0, A1, Ar1, Ar2, Y1, and Y2 have two or more anionic structures, Za can also be a counter cation. In addition, in formula 1, if the moieties other than Za are electrically neutral, Za may be omitted.

[0168] The sulfonamide anion is preferably an arylsulfonamide anion. The sulfonimide anion is preferably a bisarylsulfonimide anion. Specific examples of sulfonamide anions or sulfonimide anions are shown below, but are not limited to these. In the following specific examples, Ph represents a phenyl group, Me represents a methyl group, and Et represents an ethyl group.

[0169] [ka]

[0170] From the viewpoint of visibility, the group whose bond to X1 is cleaved by exposure to heat or infrared light is preferably a group represented by any one of the following formulas (1-1) to (1-7), and more preferably a group represented by any one of the following formulas (1-1) to (1-3).

[0171] [ka]

[0172] In formulas (1-1) to (1-7), ● represents a bonding site with X1 in formula 1, and R 10 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, -OR 14 , -NR 15 R 16 or -SR 17 represents R 11 each independently represents a hydrogen atom, an alkyl group, or an aryl group; R 12 is an aryl group, -OR 14 , -NR 15 R 16 , -SR 17 , -C(=O)R 18 , -OC(=O)R 18 or a halogen atom, R 13 represents an aryl group, an alkenyl group, an alkoxy group, or an onium group; R 14 ~R 17each independently represents a hydrogen atom, an alkyl group, or an aryl group; R 18 are each independently an alkyl group, an aryl group, or -OR 14 , -NR 15 R 16 or -SR 17 represents Z 1 represents a counter ion that neutralizes the charge.

[0173] R 10 , R 11 and R 14 ~R 18 In a preferred embodiment, when R is an alkyl group, 2 ~R 9 and R 0 The preferred embodiments of the alkyl group are the same as those in the above. R 10 and R 13 The alkenyl group in the formula (I) preferably has 1 to 30 carbon atoms, more preferably 1 to 15 carbon atoms, and even more preferably 1 to 10 carbon atoms. R 10 ~R 18 In a preferred embodiment, when R is an aryl group, 0 The preferred embodiments are the same as those of the aryl group in the above.

[0174] From the viewpoint of visibility, R in Equation (1-1) 10 represents an alkyl group, an alkenyl group, an aryl group, -OR 14 , -NR 15 R 16 or -SR 17 is preferably an alkyl group, -OR 14 , -NR 15 R 16 or -SR 17 More preferably, it is an alkyl group or -OR 14 More preferably, -OR 14 It is particularly preferred that: Furthermore, R in formula (1-1) 10 When is an alkyl group, the alkyl group is preferably an alkyl group having an arylthio group or an alkyloxycarbonyl group at the α-position. R in formula (1-1) 10 -OR 14 If R 14 is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, further preferably an isopropyl group or a t-butyl group, and particularly preferably a t-butyl group.

[0175] From the viewpoint of visibility, R in Equation (1-2) 11 is preferably a hydrogen atom. In addition, from the viewpoint of visibility, R in formula (1-2) 12 is -C(=O)OR 14 , -OC(=O)OR 14 or a halogen atom, preferably —C(═O)OR 14 or -OC(=O)OR 14 It is more preferable that R in formula (1-2) is 12 -C(=O)OR 14 or -OC(=O)OR 14 If R 14 is preferably an alkyl group.

[0176] From the viewpoint of visibility, R in Equation (1-3) 11 are each independently preferably a hydrogen atom or an alkyl group, and at least one R 11 However, it is more preferably an alkyl group. Also, R 11 The alkyl group in the formula (I) is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 3 to 10 carbon atoms. Furthermore, R 11 The alkyl group in is preferably a branched alkyl group or a cycloalkyl group, more preferably a secondary or tertiary alkyl group or a cycloalkyl group, and further preferably an isopropyl group, a cyclopentyl group, a cyclohexyl group, or a t-butyl group. In addition, from the viewpoint of visibility, R in Equation (1-3) 13is preferably an aryl group, an alkoxy group or an onium group, more preferably a p-dimethylaminophenyl group or a pyridinium group, and even more preferably a pyridinium group. R 13 Examples of the onium group in (I) include a pyridinium group, an ammonium group, and a sulfonium group. The onium group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a sulfo group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and a combination thereof, with an alkyl group, an aryl group, and a combination thereof being preferred. Among these, a pyridinium group is preferred, and examples thereof include an N-alkyl-3-pyridinium group, an N-benzyl-3-pyridinium group, an N-(alkoxypolyalkyleneoxyalkyl)-3-pyridinium group, an N-alkoxycarbonylmethyl-3-pyridinium group, an N-alkyl-4-pyridinium group, an N-benzyl-4-pyridinium group, an N-(alkoxypolyalkyleneoxyalkyl)-4-pyridinium group, and an N-alkoxycarbonylmethyl-4-pyridinium group. An N-methyl-3-pyridinium group, an N-octyl-3-pyridinium group, an N-methyl-4-pyridinium group, or an N-octyl-4-pyridinium group is particularly preferred, and an N-octyl-3-pyridinium group or an N-octyl-4-pyridinium group is most preferred. Also, R 13 is a pyridinium group, examples of the counter anion include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, and the like, with a p-toluenesulfonate ion or a hexafluorophosphate ion being preferred.

[0177] From the viewpoint of visibility, R in Equation (1-4)10 is preferably an alkyl group or an aryl group, and two R 10 It is more preferable that one of them is an alkyl group and the other is an aryl group. From the viewpoint of visibility, R in Equation (1-5) 10 is preferably an alkyl group or an aryl group, more preferably an aryl group, and even more preferably a p-methylphenyl group. From the viewpoint of visibility, R in Equation (1-6) 10 are each independently preferably an alkyl group or an aryl group, more preferably a methyl group or a phenyl group. From the viewpoint of visibility, Z in Eq. (1-7) 1 is any counter ion that neutralizes the charge, and the compound as a whole may be included in the above Za. Z 1 is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a p-toluenesulfonate ion or a hexafluorophosphate ion.

[0178] Furthermore, the group whose bond to X1 is cleaved by heat or infrared exposure is particularly preferably a group represented by formula (1-8).

[0179] [ka]

[0180] In formula (1-8), ● represents a bonding site with X1 in formula 1, and R 19 and R 20 each independently represents an alkyl group, and Za' represents a counter ion that neutralizes the charge.

[0181] The pyridinium ring and R in formula (1-8) 20The bonding position to the hydrocarbon group containing the following is preferably the 3rd or 4th position of the pyridinium ring, more preferably the 4th position of the pyridinium ring. R 19 and R 20 The alkyl group in the formula (I) may be linear, branched, or have a ring structure. The alkyl group may have a substituent, and preferred examples of the substituent include an alkoxy group and a terminal alkoxypolyalkyleneoxy group. R 19 is preferably an alkyl group having 1 to 12 carbon atoms, more preferably a linear alkyl group having 1 to 12 carbon atoms, even more preferably a linear alkyl group having 1 to 8 carbon atoms, and particularly preferably a methyl group or an n-octyl group. R 20 is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 8 carbon atoms, further preferably an isopropyl group or a t-butyl group, and particularly preferably an isopropyl group. Za' may be any counter ion that neutralizes the charge, and the entire compound may be included in the above Za. Za' is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a p-toluenesulfonate ion or a hexafluorophosphate ion.

[0182] In addition, from the viewpoint of enhancing the visibility of the exposed area, the decomposable infrared absorber is preferably a group that decomposes upon exposure to infrared light (specifically, R 1 ) is preferably a cyanine dye. From the viewpoint of improving the visibility of exposed areas, the decomposable infrared absorber is more preferably a compound represented by the following formula 1-1.

[0183] [ka]

[0184] In formula 1-1, R 1 represents a group represented by any one of the following formulas 2-1 to 4-1, and R 11 ~R 18 are each independently a hydrogen atom, a halogen atom, or -R a , -OR b , -SR c , or -NR d R e represents R a ~R e each independently represents a hydrocarbon group; A1, A2 and a plurality of R 11 ~R 18 may be linked to form a monocycle or polycycle, A1 and A2 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, n 11 and n 12 each independently represents an integer of 0 to 5, provided that n 11 and n 12 The sum of is 2 or more, and n 13 and n 14 each independently represents 0 or 1, and L represents an oxygen atom, a sulfur atom, or -NR 10 - represents R 10 represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes the charge.

[0185] [ka]

[0186] In formulas 2-1 to 4-1, R 20 , R 30 , R 41 and R 42 each independently represents an alkyl group or an aryl group, Zb represents a counter ion that neutralizes the charge, and the wavy line represents the bonding site with the group represented by L in the above formula 1-1.

[0187] When exposed to infrared light, the compound of formula 1-1 reacts with R 1 The -L bond is cleaved and L is =O, =S, or =NR10 and discoloration occurs.

[0188] In Formula 1-1, R 1 represents a group represented by any one of the above formulas 2-1 to 4-1. The group represented by formula 2-1, the group represented by formula 3-1, and the group represented by formula 4-1 will be explained below.

[0189] In formula 2-1, R 20 represents an alkyl group or an aryl group, and the wavy line portion represents the bonding site to the group represented by L in formula 1-1. R 20 The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear, branched, or have a ring structure. R 20 The aryl group represented by the formula (I) is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. R 20 From the viewpoint of visibility, the group is preferably an alkyl group.

[0190] In addition, from the viewpoint of decomposability and visibility, 20 The alkyl group represented by the formula (I) is preferably a secondary alkyl group or a tertiary alkyl group, and more preferably a tertiary alkyl group. Furthermore, from the viewpoint of decomposability and visibility, 20 The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and even more preferably a branched alkyl group having 3 to 6 carbon atoms, and is particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

[0191] Specific examples of the group represented by formula 2-1 above include, but are not limited to, the following: In the structural formula below, ● represents the bonding site with the group represented by L in formula 1-1.

[0192] [ka]

[0193] In formula 3-1, R 30 represents an alkyl group or an aryl group, and the wavy line portion represents the bonding site to the group represented by L in formula 1-1. R 30 The alkyl group and aryl group represented by the formula 20 The same applies to the alkyl group and aryl group represented by the following formula (1), and the preferred embodiments are also the same.

[0194] From the viewpoint of decomposability and visibility, R 30 The alkyl group represented by the formula (I) is preferably a secondary alkyl group or a tertiary alkyl group, and more preferably a tertiary alkyl group. In addition, from the viewpoint of decomposability and visibility, 30 The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and even more preferably a branched alkyl group having 3 to 6 carbon atoms, and is particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group. Furthermore, from the viewpoint of decomposability and visibility, 30 The alkyl group represented by the formula (I) is preferably a substituted alkyl group, more preferably a fluoro-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group.

[0195] From the viewpoint of decomposability and visibility, R 30The aryl group represented by the formula (I) is preferably a substituted aryl group, and examples of the substituent include an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms) and an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms).

[0196] Specific examples of the group represented by formula 3-1 above are listed below, but the group is not limited to these. In the structural formula below, ● represents the bonding site with the group represented by L in formula 1-1.

[0197] [ka]

[0198] In formula 4-1, R 41 and R 42 each independently represents an alkyl group or an aryl group, Zb represents a counter ion that neutralizes the charge, and the wavy line portion represents the bonding site with the group represented by L in formula 1-1. R 41 or R 42 The alkyl group and aryl group represented by the formula 20 The same applies to the alkyl group and aryl group represented by the following formula (1), and the preferred embodiments are also the same. R 41 From the viewpoints of decomposability and visibility, the group is preferably an alkyl group. R 42 From the viewpoints of decomposability and visibility, the group is preferably an alkyl group.

[0199] From the viewpoint of decomposability and visibility, R 41 The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group. From the viewpoint of decomposability and visibility, R 42 The alkyl group represented by the formula (I) is preferably a secondary alkyl group or a tertiary alkyl group, and more preferably a tertiary alkyl group. In addition, from the viewpoint of decomposability and visibility, 42The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and even more preferably a branched alkyl group having 3 to 6 carbon atoms, and is particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

[0200] Zb in formula 4-1 may be a counter ion for neutralizing the charge, and the entire compound may be included in Za in formula 1-1. Zb is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a tetrafluoroborate ion or a hexafluorophosphate ion.

[0201] Specific examples of the group represented by the above formula 4-1 are listed below, but the group is not limited to these. In the following structural formula, ● represents the bonding site with the group represented by L in formula 1-1.

[0202] [ka]

[0203] In formula 1-1, L is an oxygen atom or —NR 10 - is preferred, and an oxygen atom is particularly preferred. Also, -NR 10 -R in 10 is preferably an alkyl group. 10 The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 10 carbon atoms. 10 The alkyl group represented by the formula (I) may be linear, branched, or have a ring structure. Among the alkyl groups, a methyl group or a cyclohexyl group is preferred. -NR 10 -R in 10When is an aryl group, it is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. These aryl groups may have a substituent.

[0204] In Formula 1-1, R 11 ~R 18 are each independently a hydrogen atom, -R a , -OR b , -SR c , or -NR d R e It is preferable that: R a ~R e The hydrocarbon group represented by the formula (I) is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and even more preferably a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group may be linear, branched, or have a ring structure. As the hydrocarbon group, an alkyl group is particularly preferred.

[0205] The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear, branched, or have a ring structure. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group. Among the alkyl groups, a methyl group, an ethyl group, a propyl group or a butyl group is preferred.

[0206] The alkyl group may have a substituent. Examples of the substituent include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and groups formed by combining these groups.

[0207] R in Formula 1-1 11 ~R 14 are each independently a hydrogen atom or -R a (i.e., a hydrocarbon group), more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom, except in the following cases. Among them, R bonded to the carbon atom bonded to the carbon atom bonded to L 11 and R 13 is preferably an alkyl group, and more preferably the two are linked to form a ring. The ring formed may be a monocycle or a polycycle. Specific examples of the ring formed include monocycles such as a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring, and a cyclohexadiene ring, and polycycles such as an indene ring and an indole ring. Also, A1 + R attached to the carbon atom to which 12 is R 15 or R 16 (preferably R 16 ) to form a ring, and R bonded to the carbon atom to which A2 is bonded is preferably 14 is R 17 or R 18 (preferably R 18 ) to form a ring.

[0208] In Formula 1-1, n 13 is 1 and R 16 -R a (i.e., a hydrocarbon group) is preferred. Also, R 16 is A1 + R attached to the carbon atom to which 12It is preferable that the ring is linked to the above to form a ring. The ring formed is preferably an indolium ring, a pyrylium ring, a thiopyrylium ring, a benzoxazoline ring, or a benzimidazoline ring, and from the viewpoint of improving the visibility of the exposed area, an indolium ring is more preferable. These rings may further have a substituent. In Formula 1-1, n 14 is 1 and R 18 -R a (i.e., a hydrocarbon group) is preferred. Also, R 18 is the R bonded to the carbon atom to which A2 is bonded. 14 It is preferable that the ring is linked to the above to form a ring. The ring formed is preferably an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring, or a benzimidazole ring, and from the viewpoint of improving the visibility of the exposed area, an indole ring is more preferable. These rings may further have a substituent. R in Formula 1-1 16 and R 18 are preferably the same group, and when each of them forms a ring, A1 + and A2 preferably form a ring of the same structure.

[0209] R in Formula 1-1 15 and R 17 are preferably the same group. 15 and R 17 -R a (i.e., a hydrocarbon group), more preferably an alkyl group, and even more preferably a substituted alkyl group.

[0210] In the compound represented by formula 1-1, from the viewpoint of improving water solubility, R 15 and R 17 is preferably a substituted alkyl group. R 15 or R 17 Examples of the substituted alkyl group represented by the formula (a1) include groups represented by any of the following formulas (a1) to (a4).

[0211] [ka]

[0212] In formulas (a1) to (a4), R W0 represents an alkylene group having 2 to 6 carbon atoms, W represents a single bond or an oxygen atom, n W1 represents an integer from 1 to 45, and R W1 is an alkyl group having 1 to 12 carbon atoms or -C(=O)-R W5 represents R W5 represents an alkyl group having 1 to 12 carbon atoms, and R W2 ~R W4 each independently represents a single bond or an alkylene group having 1 to 12 carbon atoms, and M represents a hydrogen atom, a sodium atom, a potassium atom, or an onium group.

[0213] In formula (a1), R W0 Specific examples of the alkylene group represented by the formula (I) include an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, an n-pentylene group, an isopentylene group, an n-hexyl group, an isohexyl group, and the like. An ethylene group, an n-propylene group, an isopropylene group, or an n-butylene group is preferred, and an n-propylene group is particularly preferred. n W1 is preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3. R W1 Specific examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an n-octyl group, an n-dodecyl group, and the like. A methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, or a tert-butyl group is preferred, a methyl group or an ethyl group is more preferred, and a methyl group is particularly preferred. R W5 The alkyl group represented by R W1 The preferred embodiment is the same as the alkyl group represented by R W1 The preferred embodiments are the same as those of the alkyl group represented by the following formula:

[0214] Specific examples of the group represented by formula (a1) are shown below, but are not limited to these: In the following structural formula, Me represents a methyl group, Et represents an ethyl group, and * represents a bonding site.

[0215] [ka]

[0216] In formulas (a2) to (a4), R W2 ~R W4 Specific examples of the alkylene group represented by the formula (I) include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, an n-pentylene group, an isopentylene group, an n-hexyl group, an isohexyl group, an n-octylene group, an n-dodecylene group, and the like. An ethylene group, an n-propylene group, an isopropylene group, or an n-butylene group is preferred, and an ethylene group or an n-propylene group is particularly preferred. In formula (a3), two M's may be the same or different.

[0217] In the formulae (a2) to (a4), examples of the onium group represented by M include an ammonium group, an iodonium group, a phosphonium group, and a sulfonium group. CO2M in formula (a2), PO3M2 in formula (a2), and SO3M in formula (a4) may each have an anionic structure in which M is dissociated. The counter cation of the anionic structure is A1 + or R in Formula 1-1 1 - may be a cation that can be contained in L.

[0218] Among the groups represented by formulae (a1) to (a4), groups represented by formula (a1), formula (a2) or formula (a4) are preferred.

[0219] n in Formula 1-1 11 and n 12are preferably the same, and are both preferably integers of 1 to 5, more preferably integers of 1 to 3, further preferably 1 or 2, and particularly preferably 2.

[0220] In formula 1-1, A1 and A2 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, and a nitrogen atom is preferred. In formula 1-1, A1 and A2 are preferably the same atom.

[0221] Za in Formula 1-1 represents a counter ion that neutralizes the charge. R 11 ~R 18 and R 1 If all of -L are charge-neutral groups, Za is a monovalent counter anion. 11 ~R 18 and R 1 -L may have an anionic or cationic structure, for example, R 11 ~R 18 and R 1 When -L has two or more anionic structures, Za can also be a counter cation. If the cyanine dye represented by formula 1-1 has a charge-neutral structure as a whole compound except for Za, Za is not necessary. When Za is a counter anion, examples thereof include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, and a perchlorate ion, with a tetrafluoroborate ion being preferred. When Za is a counter cation, examples of the counter cation include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, and a sulfonium ion. Of these, a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion is preferred, and a sodium ion, a potassium ion, or an ammonium ion is more preferred.

[0222] From the viewpoint of improving the visibility of the exposed area, the decomposable infrared absorber is more preferably a compound represented by the following formula 1-2 (that is, a cyanine dye).

[0223] [ka]

[0224] In formula 1-2, R 1 represents a group represented by any one of the above formulas 2-1 to 4-1, and R 19 ~R 22 are each independently a hydrogen atom, a halogen atom, or -R a , -OR b , -CN, -SR c , or -NR d R e represents R 23 and R 24 are each independently a hydrogen atom or -R a represents R a ~R e each independently represents a hydrocarbon group, R 19 and R 20 , R 21 and R 22 , or R 23 and R 24 may be linked to form a monocycle or polycycle, and L is an oxygen atom, a sulfur atom, or -NR 10 - represents R 10 represents a hydrogen atom, an alkyl group, or an aryl group; R d1 ~R d4 , W 1 and W 2 each independently represents an alkyl group which may have a substituent, and Za represents a counter ion which neutralizes the charge.

[0225] R in Equation 1-2 1 is R in Equation 1-1 1 The same applies to the preferred embodiments.

[0226] In Formula 1-2, R 19 ~R 22are each independently a hydrogen atom, a halogen atom, or -R a , -OR b or -CN. More specifically, R 19 and R 21 is a hydrogen atom or -R a It is preferable that: Also, R 20 and R 22 is a hydrogen atom, -R a , -OR b or -CN. R 19 ~R 22 -R expressed as a is preferably an alkyl group or an alkenyl group. R 19 ~R 22 All of -R a If R 19 and R 20 and R 21 and R 22 are preferably linked to form a monocyclic or polycyclic ring. R 19 and R 20 or R 21 and R 22 Examples of the ring formed by linking include a benzene ring and a naphthalene ring.

[0227] In Formula 1-2, R 23 and R 24 are preferably linked to form a monocyclic or polycyclic ring. R 23 and R 24 The ring formed by linking may be a monocycle or a polycycle. Specific examples of the ring formed include monocycles such as a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring, and a cyclohexadiene ring, and polycycles such as an indene ring.

[0228] In Formula 1-2, R d1 ~R d4 is preferably an unsubstituted alkyl group. d1 ~R d4are preferably the same group. The unsubstituted alkyl group may be an unsubstituted alkyl group having 1 to 4 carbon atoms, and among these, a methyl group is preferred.

[0229] In Equation 1-2, W 1 and W 2 are each independently preferably a substituted alkyl group from the viewpoint of increasing the water solubility of the compound represented by formula 1-2. W 1 and W 2 Examples of the substituted alkyl group represented by the formula (a1) include groups represented by any one of formulas (a1) to (a4) in formula 1-1, and preferred embodiments are also the same. Also, W 1 and W 2 are each independently an alkyl group having a substituent, and preferably a group having at least one of —OCHCH—, a sulfo group, a salt of a sulfo group, a carboxy group, or a salt of a carboxy group, from the viewpoint of on-press developability.

[0230] Za represents a counter ion that neutralizes the charge within the molecule. R 19 ~R 22 , R 23 ~R 24 , R d1 ~R d4 , W 1 , W 2 , and R 1 If all of -L are charge-neutral groups, Za is a monovalent counter anion. 19 ~R 22 , R 23 ~R 24 , R d1 ~R d4 , W 1 , W 2 , and R 1 -L may have an anionic or cationic structure, for example, R 19 ~R 22 , R 23 ~R 24 , R d1 ~R d4 , W 1, W 2 , and R 1 When -L has two or more anionic structures, Za can also be a counter cation. If the compound represented by formula 1-2 has a charge-neutral structure as a whole except for Za, Za is not necessary. Examples of when Za is a counter anion are the same as Za in formula 1-1, and preferred embodiments are also the same. Examples of when Za is a counter cation are the same as Za in formula 1-1, and preferred embodiments are also the same.

[0231] From the viewpoints of decomposability and visibility, the cyanine dye as the decomposable infrared absorber is more preferably a compound represented by any one of the following formulas 1-3 to 1-7. In particular, from the viewpoints of decomposability and visibility, a compound represented by any one of formulas 1-3, 1-5, and 1-6 is preferred.

[0232] [ka]

[0233] In formulas 1-3 to 1-7, R 1 represents a group represented by any one of the above formulas 2-1 to 4-1, and R 19 ~R 22 are each independently a hydrogen atom, a halogen atom, or -R a , -OR b , -CN, -SR c , or -NR d R e represents R 25 and R 26 are each independently a hydrogen atom, a halogen atom, or -R a represents R a ~R e each independently represents a hydrocarbon group, R 19 and R 20 , R 21 and R 22 , or R 25 and R 26may be linked to form a monocycle or polycycle, and L is an oxygen atom, a sulfur atom, or -NR 10 - represents R 10 represents a hydrogen atom, an alkyl group, or an aryl group; R d1 ~R d4 , W 1 and W 2 each independently represents an alkyl group which may have a substituent, and Za represents a counter ion that neutralizes the charge.

[0234] R in Formulas 1-3 to 1-7 1 , R 19 ~R 22 , R d1 ~R d4 , W 1 , W 2 , and L is R in Formula 1-2 1 , R 19 ~R 22 , R d1 ~R d4 , W 1 , W 2 , and L, and the preferred embodiments are also the same. R in Equation 1-7 25 and R 26 are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group.

[0235] Specific examples of the cyanine dye as the decomposable infrared absorber are listed below, but the invention is not limited thereto.

[0236] [ka]

[0237] Moreover, from the viewpoint of color development properties, the infrared absorber preferably contains a compound represented by the following formula (X) as a decomposable infrared absorber.

[0238] [ka]

[0239] In formula (X), Ar 11 and Ar 12 each independently represents an atomic group necessary to form a substituted or unsubstituted aromatic ring or a substituted or unsubstituted heteroaromatic ring; R 11 and R 12 are each independently a substituted or unsubstituted alkyl group, and R 13 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R 14 represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; each Y independently represents an oxygen atom, a sulfur atom, or a C(R 15 R 16 ), and R 15 and R 16 each independently represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, A1 and A2 each independently represent a substituted or unsubstituted alkyl group or a group of atoms including 2 or 3 carbon atoms necessary to combine with each other to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbocyclic ring, and Za represents a counter ion that neutralizes the charge.

[0240] The above Ar 11 and Ar 12 each independently represents an atomic group necessary to form a substituted or unsubstituted aromatic ring, or a substituted or unsubstituted heteroaromatic ring. Examples of the substituent on the aromatic ring or heteroaromatic ring include an alkyl group, an alkoxy group, a halogen atom, a cyano group, a -COOR group, a -SOR group, or a -SOR group (R represents a substituted or unsubstituted alkyl group), and an alkyl group or a halogen atom is preferred. In addition, the above Ar 11 and Ar 12 is preferably an atomic group necessary for forming a substituted or unsubstituted aromatic ring, and more preferably an atomic group necessary for forming a substituted or unsubstituted benzene ring or naphthalene ring.

[0241] The above Ys each independently represent >C(R 15 R 16 ), and a dialkylmethylene group represented by >C(R 15 R 16 ) and R 15 and R 16 are preferably the same dialkylmethylene group. 15 and R 16 are preferably each independently a substituted or unsubstituted alkyl group having 1 or 2 carbon atoms. As the above Y, in particular, >C(R 15 R 16 ) and R 15 and R 16 is preferably a dialkylmethylene group in which R is a methyl group.

[0242] Above R 11 and R 12 is preferably a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms. 11 and R 12 may contain an ether bond or an ester bond in the carbon chain of the substituted or unsubstituted alkyl group having 1 to 12 carbon atoms.

[0243] Above R 13 is preferably a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, and more preferably a haloalkyl group in which one or more hydrogen atoms of the alkyl group having 1 to 12 carbon atoms have been substituted with a halogen atom. In this case, preferred examples of the halogen atom include a chlorine atom or a bromine atom. Among them, the above R 11 and R 12 are each independently preferably a perfluoroalkyl group.

[0244] Above R 14 is preferably a hydrogen atom or an unsubstituted alkyl group having 1 or 8 carbon atoms.

[0245] It is preferable that A1 and A2 each independently represent a substituted or unsubstituted alkyl group, or bond to each other to represent an atomic group containing two or three carbon atoms necessary to form a cyclopentene ring or a cyclohexene ring.

[0246] When Za is a counter anion, it is preferably an anion containing a halogen atom or an anion containing a boron atom. - , PF6 - , BF4 - , SbF6 - , CH3SO3 - , CF3SO3 - , C6H5SO3 - , CH3C6H5SO3 - , HOC6H5SO3 - , ClC6H5SO3 - , CH3C6H5SO3 - , tetraarylborate anions (for example, tetraphenylborate anions), and the like.

[0247] When Za is a counter cation, examples thereof include alkali metal ions, alkaline earth metal ions, tertiary ammonium ions, quaternary ammonium ions, and onium ions (iodonium ions, sulfonium ions, phosphonium ions, etc.).

[0248] Specific examples of the compound represented by formula (X) include, but are not limited to, the following: Ph represents a phenyl group.

[0249] [ka]

[0250] The decomposable infrared absorber preferably contains a compound represented by the following formula (P1).

[0251] [ka]

[0252] In formula (P1), R P1 represents a group represented by the following formula (P2) or formula (P3), and R P2 and R P3 each independently represents a hydrogen atom or an alkyl group, R P2 and R P3 may be linked to each other to form a ring, and Ar P1 and Ar P2 each independently represents a benzene ring or a naphthalene ring; Y P1 and Y P2 are each independently an oxygen atom, a sulfur atom, or -NR P0 - or a dialkylmethylene group, R P4 and R P5 each independently represents an alkyl group, R P6 ~RP 9 each independently represents a hydrogen atom or an alkyl group, R P0 represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes the charge.

[0253] [ka]

[0254] In formula (P2) and formula (P3), R P10 represents a monovalent organic group having an aryl group, and R P11 ~R P14 and R P17 ~R P20 each independently represents a hydrogen atom, an alkyl group, an aryl group, a hydroxy group, an alkoxy group, or a halogen atom; R P15 and R P16 each independently represents a hydrogen atom, an alkyl group, or an aryl group; R P11 ~R P20 At least two of these may be bonded to form a ring structure, and * represents a single bond bonding to the oxygen atom in formula (P1).

[0255] The compound represented by formula (P1) has the property of decomposing by heat or infrared energy to produce a highly visible colored substance. In the present disclosure, color development means that the compound becomes more strongly colored after heating or infrared exposure compared to before heating or infrared exposure, or that the absorption becomes shorter in wavelength and the compound has absorption in the visible light region. That is, the compound represented by formula (P1) is a compound that decomposes by heat or infrared exposure, and the absorption in the visible light region increases, or the absorption becomes shorter in wavelength and the compound has absorption in the visible light region compared to before heating or infrared exposure. The compound represented by formula (P1) is preferably a compound that decomposes by heat or infrared exposure to produce a compound having a maximum absorption wavelength in the range of 500 nm to 600 nm.

[0256] R P1 is preferably a group represented by the above formula (P2) from the viewpoints of visibility, printing durability, synthesis suitability, and raw material supplyability.

[0257] R P10 In terms of visibility, printing durability, on-press developability, and on-press developability after aging, the aryl group in is preferably an aryl group having 6 to 30 carbon atoms (also referred to as "number of carbon atoms"), more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. Also, R P10 In terms of visibility, printing durability, on-press developability, and on-press developability after aging, the aryl group in is preferably an aryl group having one or more substituents on the aromatic ring, more preferably a phenyl group having one or more substituents on the aromatic ring, even more preferably a phenyl group having one or more alkyl groups on the aromatic ring, and particularly preferably an alkylphenyl group. R P10From the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, is preferably a group having one or more substituents on the aromatic ring of an arylalkyl group, more preferably a group having one or more substituents on the aromatic ring of a benzyl group, still more preferably a benzyl group having one or more substituents (substituted benzyl group), and particularly preferably a benzyl group having an alkyl group on the benzene ring. Also, R P10 is preferably a group represented by formula (P4) from the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging.

[0258] [ka]

[0259] In formula (P4), X P2 represents a single bond or an alkylene group, Ar P3 represents an aryl group.

[0260] X P2 From the viewpoints of visibility, printing durability, and synthesis suitability, is preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms, even more preferably an alkylene group having 1 to 3 carbon atoms, particularly preferably an alkylene group having 1 or 2 carbon atoms, and most preferably a methylene group. Ar P3 From the viewpoints of visibility, printing durability, and synthesis suitability, the aryl group is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent, and preferably has one or more substituents. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof. Specific examples include a phenyl group, a naphthyl group, a p-tolyl group, a p-ethylphenyl group, a pt-butylphenyl group, a p-chlorophenyl group, a p-fluorophenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, a p-methylthiophenyl group, a p-phenylthiophenyl group, a p-phenylphenyl group, an o-tolyl group, an o-ethylphenyl group, an o-tBuphenyl group, an o-chlorophenyl group, an o-fluorophenyl group, an o-methoxyphenyl group, an o-dimethylaminophenyl group, an o-methylthiophenyl group, and an o-phenylthiophenyl group.

[0261] Also, Ar P3 From the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, is preferably an aryl group having one or more substituents on the aromatic ring, more preferably a phenyl group having one or more substituents on the aromatic ring (substituted phenyl group), still more preferably an alkylphenyl group, particularly preferably a phenyl group having a branched alkyl group, and most preferably a t-butylphenyl group. Furthermore, the alkylphenyl group is preferably a p-alkylphenyl group from the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging.

[0262] R P11 ~R P14 and R P17 ~R P20 represents a hydrogen atom, an alkyl group, an aryl group, a hydroxy group, an alkoxy group, or a halogen atom, and may be the same group or different groups. P11 ~R P14 and R P17 ~R P20 may be linked to form a ring. R P11 ~R P14 and R P17 ~R P20 The alkyl group in the formula (I) may be linear, branched, or have a ring structure. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group. Among the alkyl groups, a methyl group, an ethyl group, a propyl group, or a butyl group is preferred.

[0263] R P11 ~R P14 and R P17 ~R P20 The alkyl group in may have a substituent. Examples of the substituent include an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof.

[0264] R P11 ~R P14 and R P17 ~R P20 The aryl group in is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent, such as an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, or a combination thereof. Specific examples include a phenyl group, a naphthyl group, a p-tolyl group, a p-chlorophenyl group, a p-fluorophenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, a p-methylthiophenyl group, and a p-phenylthiophenyl group. Among the aryl groups, a phenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, or a naphthyl group is preferred.

[0265] R P11 ~R P14 and R P17 ~R P20 are each independently preferably a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and particularly preferably a hydrogen atom, from the viewpoints of visibility and printing durability.

[0266] R P15 and R P16 represents a hydrogen atom, an alkyl group, or an aryl group, and may be the same group or different groups. R P15 is preferably a hydrogen atom from the viewpoints of visibility, printing durability, and synthesis suitability. R P16 From the viewpoints of visibility and printing durability, is preferably an alkyl group or an aryl group, more preferably an alkyl group, further preferably a branched alkyl group, and particularly preferably a t-butyl group. R P16 In terms of visibility and printing durability, preferred branched alkyl groups in R include an isopropyl group, a t-butyl group, an isobutyl group, a cyclopentyl group, and a cyclohexyl group. P16 In terms of visibility and printing durability, the aryl group in the formula (I) is preferably a phenyl group.

[0267] R P15 and R P16 The alkyl group in is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms. R P15 and R P16The alkyl group in the formula (I) may be linear, branched, or have a ring structure. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group. Among the alkyl groups, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a t-butyl group, an isobutyl group, a cyclopentyl group, or a cyclohexyl group is preferred. R P15 and R P16 The alkyl group in may have a substituent. Examples of the substituent include an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof. R P15 and R P16 A preferred embodiment of the aryl group in R P11 ~R P14 and R P17 ~R P20 The preferred embodiments are the same as those of the aryl group in the above.

[0268] R P2 , R P3 , R P6 , R P7 , R P8 , R P9 and R P0 A preferred embodiment of the alkyl group in R P11 ~R P14 and R P17 ~R P20 The preferred embodiments of the alkyl group are the same as those in the above. RP0 A preferred embodiment of the aryl group in R P11 ~R P14 and R P17 ~R P20 The preferred embodiments are the same as those of the aryl group in the above.

[0269] R P2 and R P3 are preferably linked to form a ring. R P2 and R P3 When they are linked to form a ring, it is preferably a 5-membered or 6-membered ring, and particularly preferably a 5-membered ring.

[0270] Y P1 and Y P2 are each independently an oxygen atom, a sulfur atom, or -NR P0 - or a dialkylmethylene group, -NR P0 - or dialkylmethylene groups are preferred, with dialkylmethylene groups being more preferred. R P0 represents a hydrogen atom, an alkyl group or an aryl group, and is preferably an alkyl group.

[0271] R P4 or R P5 The alkyl group in R is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. P4 or R P5 The alkyl group in the formula (I) may be linear, branched, or have a ring structure. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group.

[0272] R P4 or R P5 The alkyl group in may have a substituent. Examples of the substituent include an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof.

[0273] R P4 or R P5 Among the alkyl groups in the formula (I), a methyl group, an ethyl group, a propyl group, or a butyl group is preferred. The substituent on the alkyl group is preferably a methoxy group, a phenoxy group, a phenyl group or a naphthyl group. R P4 or R P5 In terms of solubility and developability, the alkyl group in is particularly preferably an ethyl group or a propyl group having a substituent (for example, the substituent of Dye-12 described below). Also, R P4 and R P5 are preferably the same group.

[0274] R P6 ~R P9 each independently represents a hydrogen atom or an alkyl group, and is preferably a hydrogen atom.

[0275] Ar P1 and Ar P2 each independently represents a group forming a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, Examples of the substituent include an alkyloxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a phosphonic acid group, and a group formed by combining these groups. The substituent is preferably an alkyl group or an alkoxy group. In addition, from the viewpoint of increasing the maximum absorption wavelength of the compound represented by formula (P1) and improving the color development property and printing durability of the lithographic printing plate, Ar P1 and Ar P2 are each independently preferably a group that forms a naphthalene ring or a benzene ring having an alkyl group or an alkoxy group as a substituent, more preferably a group that forms a naphthalene ring or a benzene ring having an alkoxy group as a substituent, and particularly preferably a group that forms a benzene ring having a methoxy group as a substituent.

[0276] In formula (P1), Ar P1 or Ar P2 is preferably a group that forms a group represented by the following formula:

[0277] [ka]

[0278] In the above formula, R P21 each independently represents an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group, or a halogen atom having 1 to 12 carbon atoms; nP3 represents an integer of 1 to 4; and P21 may be bonded to each other to form a ring, and * represents the bonding site.

[0279] Za represents a counter ion for neutralizing the charge. Depending on the valence to be neutralized, the counter ion may be one type of counter ion or two or more types of counter ions, or two or more counter ions of the same or different types may be present. However, if the compound represented by formula (P1) has a corresponding ionic substituent in its structure and charge neutralization is not required, Za is not required. When referring to an anion species, examples include sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, p-toluenesulfonate ions, and perchlorate ions, with tetrafluoroborate ions, hexafluorophosphate ions, and p-toluenesulfonate ions being preferred. When referring to a cation species, examples include alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, and sulfonium ions, with sodium ions, potassium ions, ammonium ions, pyridinium ions, and sulfonium ions being preferred, with sodium ions, potassium ions, and ammonium ions being more preferred.

[0280] R P2 ~R P9 , R P0 , Ar P1 , Ar P2 , Y P1 and Y P2 may have an anionic structure or a cationic structure, and R P2 ~R P9 , R P0 , Ar P1 , Ar P2 , Y P1 and Y P2 If all of the groups are charge-neutral, Za is a monovalent counter anion or a divalent counter anion, for example, R P2 ~R P9 , R P0 , Ar P1 , Ar P2 , Y P1 and Y P2 When the compound has two or more anionic structures, Za can also be a counter cation.

[0281] From the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, the compound represented by formula (P1) above is preferably a compound represented by formula (P5) or formula (P6) below, more preferably a compound represented by formula (P7) or formula (P8) below, and particularly preferably a compound represented by formula (P9) below.

[0282] [ka]

[0283] In formula (P5) and formula (P6), R P4 and R P5 each independently represents an alkyl group, R P10 represents a monovalent organic group having an aryl group, and R P11 ~R P14 and R P17 ~R P20 each independently represents a hydrogen atom, an alkyl group, an aryl group, a hydroxy group, an alkoxy group, or a halogen atom; R P15 and R P16 each independently represents a hydrogen atom, an alkyl group, or an aryl group; R P11 ~R P20 At least two of R may be bonded to form a ring structure; P21 each independently represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group or a halogen atom, and Za represents a counter ion that neutralizes the charge.

[0284] [ka]

[0285] In formula (P7) and formula (P8), X P2 represents a single bond or an alkylene group, Ar P3 represents an aryl group, and R 4 and R 5 each independently represents an alkyl group, R P15 and R P16each independently represents a hydrogen atom, an alkyl group, or an aryl group; R P15 and R P16 may be bonded to form a ring structure, and R P21 each independently represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group or a halogen atom, and Za represents a counter ion that neutralizes the charge.

[0286] [ka]

[0287] In formula (P9), Ar P4 represents an aryl group, and R P4 and R P5 each independently represents an alkyl group, R P21 each independently represents an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group, or a halogen atom having 1 to 12 carbon atoms; R P22 represents a hydrogen atom, an alkyl group, or an aryl group; R P23 each independently represents a hydrogen atom or an alkyl group, and Za represents a counter ion that neutralizes the charge.

[0288] R in formulas (P5) to (P9) P4 , R P5 , R P11 ~R P20 Preferred embodiments of and Za are R in formulas (P1) to (P3), respectively. P4 , R P5 , R P11 ~R P20 and Za are the same as the preferred embodiments. R in formulas (P5) to (P9) P21 Each of the preferred embodiments of R P21 This is the same as the preferred embodiment of the above. X in formula (P7) and formula (P8) P2 and Ar P3 In each of the preferred embodiments, X in formula (P4) P2 and Ar P3 This is the same as the preferred embodiment of the above.

[0289] Ar in formula (P9) P4 is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent, such as an alkyl group, an alkoxy group, an aryloxy group, or a combination thereof. Among these, an alkyl group is preferred as the substituent. Ar in formula (P9) P4 Specific examples of the alkyl group include a phenyl group, a naphthyl group, a p-tolyl group, a p-ethylphenyl group, a p-butylphenyl group, a p-fluorophenyl group, and a p-methoxyphenyl group. Among them, Ar P4 As the group, from the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, a phenyl group, a p-methoxyphenyl group, a p-tBuphenyl group, or a naphthyl group is preferable, a phenyl group, a p-methoxyphenyl group, or a pt-butylphenyl group is more preferable, and a pt-butylphenyl group is particularly preferable.

[0290] R in equation (P9) P22 is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, which may be interrupted by an oxygen atom or the like. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 3 to 5 carbon atoms, and particularly preferably 3 or 4 carbon atoms, from the viewpoints of visibility, printing durability, and synthetic suitability. In terms of visibility, printing durability and suitability for composition, R in equation (P9) P23 is preferably a hydrogen atom from the viewpoint of production suitability.

[0291] Preferred specific examples of the compound represented by formula (P1) are shown below, but are not limited to these. In the following structural formula, Me represents a methyl group, and TsO - represents the tosylate anion.

[0292] [ka]

[0293] [ka]

[0294] [ka]

[0295] [ka]

[0296] [ka]

[0297] [ka]

[0298] [ka]

[0299] [ka]

[0300] In addition, as the infrared absorber that decomposes upon exposure to infrared rays, those described in JP-A-2008-544322 or WO 2016 / 027886 can be suitably used. Furthermore, as the cyanine dye, which is a decomposable infrared absorber, the infrared absorbing compounds described in WO 2019 / 219560 can be suitably used.

[0301] The infrared absorbent may be used alone or in combination of two or more. In one embodiment, the image recording layer preferably contains two or more infrared absorbents. By using two or more infrared absorbents in combination, the ability to suppress development defects over time and printing durability are further improved. Furthermore, a pigment and a dye may be used in combination as the infrared absorbent. The total content of the infrared absorbing agent in the image recording layer is preferably 0.1% by mass to 10.0% by mass, and more preferably 0.5% by mass to 5.0% by mass, based on the total mass of the image recording layer.

[0302] [Relationship between specific borate compound (electron-donating polymerization initiator), electron-accepting polymerization initiator, and infrared absorber] The image recording layer contains a specific borate compound and an electron-accepting polymerization initiator, and preferably further contains an infrared absorbing agent. When the image recording layer contains a specific borate compound, an electron-accepting polymerization initiator, and an infrared absorber, it is preferred that the HOMO of the specific borate compound is −6.0 eV or more and the LUMO of the electron-accepting polymerization initiator is −3.0 eV or less. More preferred embodiments of the HOMO of the specific borate compound and the LUMO of the electron-accepting polymerization initiator are as described above. In the image recording layer, it is presumed that the specific borate compound, at least one infrared absorber, and electron-accepting polymerization initiator transfer energy, for example, as shown in the following chemical formula. Therefore, if the HOMO of the specific borate compound is −6.0 eV or more and the LUMO of the electron-accepting polymerization initiator is −3.0 eV or less, the radical generation efficiency is improved, and it is thought that the chemical resistance and printing durability are more likely to be excellent.

[0303] [ka]

[0304] From the viewpoints of printing durability and chemical resistance, the HOMO value of at least one HOMO-specific borate compound of the infrared absorber is preferably 1.0 eV or less, more preferably 0.70 eV or less, and particularly preferably 0.60 eV or less. From the same viewpoint, the HOMO value of at least one HOMO-specific borate compound of the infrared absorber is preferably −0.200 eV or more, more preferably −0.100 eV or more. A negative value means that the HOMO of the specific borate compound is higher than the HOMO of at least one of the infrared absorbers. From the viewpoint of printing durability and chemical resistance, the value of the LUMO of the electron-accepting polymerization initiator and the LUMO of at least one of the infrared absorbers is preferably 1.00 eV or less, and more preferably 0.700 eV or less. From the same viewpoint, the value of the LUMO of the electron-accepting polymerization initiator and the LUMO of at least one of the infrared absorbers is preferably −0.200 eV or more, more preferably −0.100 eV or more. From the same viewpoint, at least one of the LUMO of the electron-accepting polymerization initiator and the LUMO of the infrared absorber The value of one LUMO is preferably 1.00 eV to −0.200 eV, more preferably 0.700 eV to −0.100 eV, where a negative value means that the LUMO of at least one infrared absorber is higher than the LUMO of the electron-accepting polymerization initiator.

[0305] <Color former> The image recording layer preferably contains a color former, more preferably an acid color former. In the present disclosure, the term "color former" refers to a compound that has the property of developing or decoloring in response to a stimulus such as light or acid, thereby changing the color of the image recording layer, and the term "acid color former" refers to a compound that has the property of developing or decoloring in response to heating in a state in which it has accepted an electron-accepting compound (for example, a proton from an acid, etc.), thereby changing the color of the image recording layer. As the acid color former, particularly preferred are colorless compounds that have a partial skeleton such as a lactone, lactam, sultone, spiropyran, ester, or amide, and that rapidly open or cleave this partial skeleton when they come into contact with an electron-accepting compound.

[0306] Examples of such acid color formers include those described in paragraphs 0203 to 0210 of WO 2020 / 262689.

[0307] Among these, from the viewpoint of color development, the color former is preferably at least one compound selected from the group consisting of spiropyran compounds, spirooxazine compounds, spirolactone compounds, and spirolactam compounds. The hue of the dye after color development is preferably green, blue or black from the viewpoint of visibility.

[0308] The acid color former is preferably a leuco dye from the viewpoints of color development and visibility of exposed areas. The leuco dye is not particularly limited as long as it has a leuco structure, but preferably has a spiro structure, and more preferably has a spirolactone ring structure. Furthermore, the leuco dye is preferably a leuco dye having a phthalide structure or a fluoran structure from the viewpoint of color development and visibility of exposed areas.

[0309] Furthermore, preferred examples of the acid color former include those described in paragraphs 0212 to 0210 of WO 2020 / 262689.

[0310] Furthermore, from the viewpoints of color development and visibility of exposed areas, it is also preferable that the acid color former contains one or more compounds selected from the group consisting of compounds represented by the following formula (Le-10) and compounds represented by the following formula (Z-4): That is, it is preferable that the image recording layer in the lithographic printing plate precursor further contains one or more compounds selected from the group consisting of compounds represented by the following formula (Le-10) and compounds represented by the following formula (Z-4):

[0311] [ka]

[0312] In formula (Le-10), each Ar1 independently represents an aryl group or a heteroaryl group, and each Ar2 independently represents an aryl group having a substituent at at least one ortho-position, or a heteroaryl group having a substituent at at least one ortho-position.

[0313] Ar1 in formula (Le-10) has the same meaning as Rb1 and Rb2 in formulae (Le-7) to (Le-9), and preferred embodiments are also the same. Ar2 in formula (Le-10) has the same meaning as Rc1 and Rc2 in formulae (Le-7) to (Le-9), and preferred embodiments are also the same.

[0314] The alkyl group in formulae (Le-1) to (Le-9) may be linear, branched, or have a ring structure. The alkyl group in formulae (Le-1) to (Le-9) preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, even more preferably 1 to 4 carbon atoms, and particularly preferably 1 or 2 carbon atoms. The aryl group in formulae (Le-1) to (Le-10) preferably has 6 to 20 carbon atoms, more preferably 6 to 10 carbon atoms, and particularly preferably 6 to 8 carbon atoms. Specific examples of the aryl group in formulae (Le-1) to (Le-10) include a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group, each of which may have a substituent. Specific examples of the heteroaryl group in formulae (Le-1) to (Le-10) include a furyl group, a pyridyl group, a pyrimidyl group, a pyrazoyl group, and a thiophenyl group, each of which may have a substituent.

[0315] Furthermore, each of the monovalent organic groups, alkyl groups, aryl groups, heteroaryl groups, dialkylanilino groups, alkylamino groups, alkoxy groups, etc. in Formulae (Le-1) to (Le-10) may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a heteroaryl group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a monoalkylmonoheteroarylamino group, a diarylamino group, a diheteroarylamino group, a monoarylmonoheteroarylamino group, a hydroxy group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heteroaryloxycarbonyl group, and a cyano group. Furthermore, these substituents may be further substituted with other substituents.

[0316] [ka]

[0317] In formula (Z-4), Rza1 represents a hydrogen atom, an alkyl group, or an alkoxy group; Rzb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, or an aryl group; Rzb1 and Rzb2, and Rzb3 and Rzb4 may be linked to form a ring structure; X represents O or NR; R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group; and Y1 and Y2 each independently represent CH or N.

[0318] Rza1 in formula (Z-4) is preferably an alkyl group or an alkoxy group. In formula (Z-4), Rzb1 and Rzb2 each independently represent an alkyl group. In formula (Z-4), Rzb3 and Rzb4 each independently represent a hydrogen atom, an alkyl group, or an aryl group, and one of them is preferably an aryl group. In formula (Z-4), it is preferred that X is O, and Y1 and Y2 are CH.

[0319] The alkyl group in formula (Z-4) may be linear, branched, or have a ring structure. The alkyl group in formula (Z-4) preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 5 carbon atoms. The aryl group in formula (Z-4) preferably has 6 to 20 carbon atoms, more preferably 6 to 10 carbon atoms, and particularly preferably 6 to 8 carbon atoms. Each group in formula (Z-4), such as an alkyl group or an aryl group, may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a diarylamino group, a hydroxy group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a cyano group. These substituents may further be substituted with other substituents.

[0320] Suitable examples of the leuco dye having a phthalide structure or a fluoran structure include the acid color formers described in paragraphs 0160 to 0168 of WO 2023 / 032681.

[0321] As the color former, commercially available products can also be used, such as the products described in paragraph 0169 of WO 2023 / 032681.

[0322] These color formers may be used alone or in combination of two or more components. The content of the color former is preferably 0.5% by mass to 10% by mass, and more preferably 1% by mass to 5% by mass, based on the total mass of the image recording layer.

[0323] <Polymerizable compound> The image recording layer also preferably contains a polymerizable compound. The polymerizable compound refers to a compound having a polymerizable group. The polymerizable group is not particularly limited as long as it is a known polymerizable group, but is preferably an ethylenically unsaturated group. The polymerizable group may be either a radically polymerizable group or a cationically polymerizable group, but is preferably a radically polymerizable group. Examples of the radically polymerizable group include a (meth)acryloyl group, an allyl group, a vinylphenyl group, and a vinyl group, and from the viewpoint of reactivity, a (meth)acryloyl group is preferred. The molecular weight of the polymerizable compound (weight average molecular weight when the polymerizable compound has a molecular weight distribution) is preferably 50 or more and less than 2,500.

[0324] The polymerizable compound may be, for example, a radically polymerizable compound or a cationically polymerizable compound, but is preferably an addition-polymerizable compound (ethylenically unsaturated compound) having at least one ethylenically unsaturated bond. The ethylenically unsaturated compound is preferably a compound having at least one terminal ethylenically unsaturated bond, more preferably a compound having two or more terminal ethylenically unsaturated bonds. The polymerizable compound has a chemical form such as a monomer, a prepolymer, i.e., a dimer, a trimer, or an oligomer, or a mixture thereof. Among these, from the viewpoint of printing durability, the polymerizable compound preferably contains a trifunctional or higher polymerizable compound, more preferably a heptafunctional or higher polymerizable compound, and even more preferably a decafunctional or higher polymerizable compound. Furthermore, from the viewpoint of printing durability of the resulting lithographic printing plate, the polymerizable compound preferably contains a trifunctional or higher (preferably heptafunctional or higher, more preferably decafunctional or higher) ethylenically unsaturated compound, and even more preferably a trifunctional or higher (preferably heptafunctional or higher, more preferably decafunctional or higher) (meth)acrylate compound.

[0325] Furthermore, from the viewpoints of on-press developability and stain suppression, the polymerizable compound preferably contains a polymerizable compound having two or fewer functionalities, more preferably a bifunctional polymerizable compound, and particularly preferably a bifunctional (meth)acrylate compound. From the viewpoints of printing durability, on-press developability, and stain suppression, the content of the difunctional or less polymerizable compound (preferably a difunctional polymerizable compound) is preferably 5% by mass to 100% by mass, more preferably 10% by mass to 100% by mass, and particularly preferably 15% by mass to 100% by mass, relative to the total mass of the polymerizable compounds in the image recording layer.

[0326] (oligomer) The polymerizable compound contained in the image recording layer preferably contains a polymerizable compound that is an oligomer (hereinafter also simply referred to as "oligomer"). The oligomer refers to a polymerizable compound having a molecular weight (weight average molecular weight when the molecular weight has a distribution) of 600 or more and 15,000 or less and containing at least one polymerizable group. From the viewpoint of excellent chemical resistance and printing durability, the molecular weight of the oligomer is preferably 1,000 or more and 15,000 or less.

[0327] Furthermore, from the viewpoint of improving printing durability, the number of polymerizable groups in one oligomer molecule is preferably 2 or more, more preferably 3 or more, even more preferably 6 or more, and particularly preferably 10 or more. There is no particular upper limit to the number of polymerizable groups in the oligomer, but the number of polymerizable groups is preferably 20 or less.

[0328] From the viewpoints of printing durability and on-press developability, the oligomer preferably has 7 or more polymerizable groups and a molecular weight of 1,000 or more and 15,000 or less, and more preferably has 7 or more and 20 or less polymerizable groups and a molecular weight of 1,000 or more and 15,000 or less. The oligomer may contain polymer components that may be generated during the process of producing the oligomer.

[0329] From the viewpoints of printing durability, visibility, and on-press developability, the oligomer preferably contains at least one selected from the group consisting of a compound having a urethane bond, a compound having an ester bond, and a compound having an epoxy residue, and more preferably contains a compound having a urethane bond. In the present disclosure, the epoxy residue refers to a structure formed by an epoxy group, and means, for example, a structure similar to the structure obtained by the reaction of an acid group (such as a carboxylic acid group) with an epoxy group.

[0330] The compound having a urethane bond, which is an example of an oligomer, is preferably, for example, a compound having at least a group represented by the following formula (Ac-1) or formula (Ac-2), and more preferably a compound having at least a group represented by the following formula (Ac-1).

[0331] [ka]

[0332] In formula (Ac-1) and formula (Ac-2), L 1 ~L 4 each independently represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and the wavy line portion represents the bonding position to other structures. L 1 ~L 4are each independently preferably an alkylene group having 2 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms, and even more preferably an alkylene group having 4 to 8 carbon atoms. The alkylene group may have a branched or cyclic structure, but is preferably a linear alkylene group.

[0333] It is preferred that the wavy line portions in formula (Ac-1) or formula (Ac-2) are each independently directly bonded to the wavy line portions in the groups represented by formula (Ae-1) or formula (Ae-2) below.

[0334] [ka]

[0335] In formula (Ae-1) and formula (Ae-2), R each independently represents an acryloyloxy group or a methacryloyloxy group, and the wavy line portion represents the bonding position to the wavy line portion in formula (Ac-1) and formula (Ac-2).

[0336] Furthermore, as the compound having a urethane bond, a compound obtained by introducing a polymerizable group into polyurethane obtained by a reaction between a polyisocyanate compound and a polyol compound through a polymer reaction may be used. For example, a compound having a urethane bond may be obtained by reacting a polyurethane oligomer obtained by reacting a polyol compound having an acid group with a polyisocyanate compound, with a compound having an epoxy group and a polymerizable group.

[0337] The number of polymerizable groups in the compound having an ester bond, which is an example of an oligomer, is preferably 3 or more, and more preferably 6 or more.

[0338] As a compound having an epoxy residue, which is an example of an oligomer, a compound containing a hydroxy group within the compound is preferred. The compound having an epoxy residue preferably has 2 to 6 polymerizable groups, and more preferably has 2 to 3 polymerizable groups. The compound having an epoxy residue can be obtained, for example, by reacting a compound having an epoxy group with acrylic acid.

[0339] Specific examples of oligomers are shown in the table below, but the oligomers are not limited to these. As the oligomer, commercially available products may be used, and examples thereof include UA510H, UA-306H, UA-306I, UA-306T (all manufactured by Kyoeisha Chemical Co., Ltd.), UV-1700B, UV-6300B, UV7620EA (all manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), U-15HA (manufactured by Shin-Nakamura Chemical Co., Ltd.), EBECRYL450, EBECRYL657, EBECRYL885, EBECRYL800, EBECRYL3416, EBECRYL860 (all manufactured by Daicel Allnex Corporation), but are not limited thereto.

[0340] From the viewpoint of improving chemical resistance, printing durability, and suppression of on-press development residue, the content of the oligomer is preferably 30% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass, relative to the total mass of the polymerizable compounds in the image recording layer.

[0341] (Low molecular polymerizable compound) The polymerizable compound may further contain a polymerizable compound other than the above-mentioned oligomer. From the viewpoint of chemical resistance, the polymerizable compound other than the oligomer is preferably a low molecular weight polymerizable compound, which may be in any chemical form such as a monomer, a dimer, a trimer, or a mixture thereof. Furthermore, from the viewpoint of chemical resistance, the low molecular weight polymerizable compound is preferably at least one polymerizable compound selected from the group consisting of polymerizable compounds having three or more ethylenically unsaturated groups and polymerizable compounds having an isocyanuric ring structure.

[0342] In the present disclosure, a low molecular weight polymerizable compound refers to a polymerizable compound having a molecular weight (weight average molecular weight when the compound has a molecular weight distribution) of 50 or more and less than 600. The molecular weight of the low-molecular-weight polymerizable compound is preferably 100 or more and less than 600, more preferably 300 or more and less than 600, and even more preferably 400 or more and less than 600, from the viewpoint of excellent chemical resistance, printing durability, and suppression of on-press development residue.

[0343] When the polymerizable compound contains a low-molecular-weight polymerizable compound as a polymerizable compound other than an oligomer (when two or more types of low-molecular-weight polymerizable compounds are contained, the total amount thereof), from the viewpoints of chemical resistance, printing durability, and suppression of on-press development residue, the ratio of the oligomer to the low-molecular-weight polymerizable compound (oligomer / low-molecular-weight polymerizable compound) is preferably 10 / 1 to 1 / 10, more preferably 10 / 1 to 3 / 7, and even more preferably 10 / 1 to 7 / 3, by mass.

[0344] Furthermore, as the low molecular weight polymerizable compound, the polymerizable compounds described in paragraphs 0082 to 0086 of WO 2019 / 013268 can also be suitably used.

[0345] Details of the method of use such as the structure of the polymerizable compound, whether it is used alone or in combination, and the amount added can be set arbitrarily. In particular, from the viewpoint of printing durability, the image recording layer preferably contains two or more polymerizable compounds. The content of the polymerizable compounds (when two or more polymerizable compounds are contained, the total content of the polymerizable compounds) is preferably 5% by mass to 75% by mass, more preferably 10% by mass to 70% by mass, and even more preferably 15% by mass to 60% by mass, relative to the total mass of the image recording layer.

[0346] <particle> The image recording layer preferably contains particles, which are described in paragraphs 0162 to 0210 of JP-A No. 2024-062746.

[0347] <Binder polymer> The image recording layer may contain a binder polymer. As the binder polymer, a binder polymer used in the image recording layer of an on-press development type lithographic printing plate precursor can be used. Specifically, as the binder polymer, the binder polymers described in paragraphs 0288 to 0317 of WO 2022 / 019217 can be suitably used.

[0348] In the image recording layer, the binder polymer may be used alone or in combination of two or more kinds. The binder polymer can be contained in any amount in the image recording layer, but the content of the binder polymer is preferably 1% by mass to 90% by mass, and more preferably 5% by mass to 80% by mass, relative to the total mass of the image recording layer. Furthermore, when the image recording layer contains another binder polymer, the content of the other binder polymer relative to the total mass of the thermoplastic resin particles and the other binder polymer is preferably more than 0 mass% and not more than 99 mass%, more preferably 20 mass% to 95 mass%, and even more preferably 40 mass% to 90 mass%.

[0349] <Oil agent> The image recording layer also preferably contains an oil agent. The oil agent in this disclosure refers to a hydrophobic compound that is in a liquid state at 80°C and is immiscible and separates when mixed with the same mass of water. When two or more oil agents are used, even if a compound with a melting point of 80°C or higher is included, it is sufficient that the two or more oil agents are in a liquid state at 80°C when mixed. Furthermore, from the viewpoints of on-press developability and suppression of turbidity of the dampening water, the oil agent is preferably a compound having a molecular weight of less than 1,000, more preferably a compound having a molecular weight of 200 to 800, and particularly preferably a compound having a molecular weight of 300 to 500. Furthermore, from the viewpoints of on-press developability and suppression of turbidity of the dampening water, the oil agent is preferably a compound having a boiling point of 200°C or higher at 1 atmosphere, more preferably a compound having a boiling point of 250°C or higher at 1 atmosphere, even more preferably a compound having a boiling point of 300°C or higher at 1 atmosphere, and particularly preferably a compound having a boiling point of 400°C or higher and 500°C or lower at 1 atmosphere. In this disclosure, unless otherwise specified, the term "boiling point" refers to the boiling point at 1 atmosphere. Furthermore, from the viewpoints of on-press developability and suppression of turbidity of the dampening water, the melting point of the oil agent at 1 atmosphere is preferably 50°C or lower, more preferably 30°C or lower, and particularly preferably −200°C or higher and 25°C or lower. In this disclosure, unless otherwise specified, the term "melting point" refers to the melting point at 1 atmosphere.

[0350] Examples of oil agents include phosphate ester compounds, aromatic hydrocarbon compounds, glyceride compounds, fatty acid compounds, and aromatic ester compounds. Among these, from the viewpoints of printing durability, ink receptivity, on-press developability, and suppression of turbidity of the dampening water, at least one compound selected from the group consisting of a phosphate ester compound, an aromatic hydrocarbon compound, a glyceride compound, and an aromatic ester compound is preferred, at least one compound selected from the group consisting of a phosphate ester compound, an aromatic hydrocarbon compound, and a glyceride compound is more preferred, at least one compound selected from the group consisting of a phosphate ester compound and an aromatic hydrocarbon compound is even more preferred, and a phosphate ester compound is particularly preferred.

[0351] As the phosphate ester compound, from the viewpoints of printing durability, ink receptivity, on-press developability, and suppression of turbidity in fountain solution, a phosphate triester compound is preferred, a phosphate triaryl ester compound is more preferred, tricresyl phosphate is even more preferred, and a mixture of two or more of the ortho-, meta-, and para-tricresyl phosphate is particularly preferred. As the aromatic hydrocarbon compound, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, a compound having two or more aromatic rings is preferred, and a compound having two or more non-fused benzene rings is more preferred. As the glyceride compound, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, a triglyceride compound is preferred, a fatty oil is more preferred, and a fatty oil that is liquid at 25°C, such as castor oil, is particularly preferred. As the fatty acid compound, from the viewpoint of on-press developability and suppression of turbidity of the fountain solution, unsaturated fatty acids are preferred, unsaturated fatty acids having 8 to 30 carbon atoms are more preferred, and unsaturated fatty acids having 12 to 24 carbon atoms are particularly preferred. As the aromatic ester compound, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, aromatic diester compounds are preferred, and aromatic diester compounds having an aliphatic ring are more preferred. As the aliphatic ester compound, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, an aliphatic ester compound having a branched alkyl group is preferred, and an aliphatic ester compound having a branched alkyl group and 10 to 24 carbon atoms is more preferred.

[0352] From the viewpoints of printing durability, ink receptivity, on-press developability, and suppression of turbidity of dampening water, the oil agent preferably contains an oil agent having a phosphorus atom, and more preferably is an oil agent having a phosphorus atom. Furthermore, from the viewpoints of on-press developability and suppression of turbidity of the dampening water, the oil agent preferably contains an oil agent having an aromatic ring, more preferably contains an oil agent having two or more aromatic rings, and particularly preferably contains an oil agent having two or more non-fused benzene rings.

[0353] From the viewpoints of printing durability, ink receptivity, on-press developability, and suppression of turbidity of dampening water, the clogP value of the oil agent is preferably 5.0 or more, more preferably 5.50 or more, even more preferably 5.50 or more and 10.0 or less, and particularly preferably 5.60 or more and 7.00 or less. The clogP value is a value obtained by calculating the common logarithm logP of the partition coefficient P between 1-octanol and water. Although publicly known methods and software can be used to calculate the clogP value, unless otherwise specified, the present disclosure will use the ClogP program incorporated into Cambridge Soft's ChemBioDraw Ultra 12.0.

[0354] Specific examples of oil agents include tricresyl phosphate, dimethyl(1-phenylethyl)benzene, 2,4-diphenyl-4-methyl-1-pentene, dicyclohexyl phthalate, castor oil, α-linolenic acid, and tri(2-ethylhexyl) phosphate.

[0355] The oil agent may be used alone or in combination of two or more types. However, from the viewpoints of on-press developability and suppression of turbidity of the dampening water, it is preferable that the image recording layer contains two or more types of oil agents having different structures. The content of the oil agent is preferably 0.0001 to 10.0% by mass, more preferably 0.0002 to 1.0% by mass, still more preferably 0.0005 to 0.5% by mass, and particularly preferably 0.001 to 0.05% by mass, relative to the total mass of the image recording layer.

[0356] <Chain transfer agent> The image recording layer may contain a chain transfer agent. As the chain transfer agent, a chain transfer agent used in the image recording layer of an on-press development type lithographic printing plate precursor can be used. Specifically, as the chain transfer agent, the chain transfer agents described in paragraphs 0388 to 0393 of WO 2022 / 019217 can be suitably used.

[0357] The chain transfer agent may be used alone or in combination of two or more kinds. The content of the chain transfer agent is preferably 0.01% by mass to 50% by mass, more preferably 0.05% by mass to 40% by mass, and even more preferably 0.1% by mass to 30% by mass, based on the total mass of the image recording layer.

[0358] <Oil sensitizer> The image recording layer may contain an oil sensitizer to improve ink receptivity. As the oil sensitizer, an oil sensitizer used in the image recording layer of an on-press development type lithographic printing plate precursor can be used. Specifically, as the oil sensitizer, the oil sensitizers described in paragraphs 0395 to 0404 of WO 2022 / 019217 can be suitably used.

[0359] The content of the oil sensitizer is preferably from 1 to 40.0% by mass, more preferably from 2 to 25.0% by mass, and even more preferably from 3 to 20.0% by mass, based on the total mass of the image recording layer.

[0360] The image recording layer may contain one kind of oil sensitizer alone, or two or more kinds of oil sensitizers in combination. One preferred embodiment of the image recording layer is an embodiment in which the image recording layer contains two or more compounds as oil sensitizers. Specifically, from the viewpoint of achieving both on-press developability and ink receptivity, the image recording layer preferably uses, as the oil sensitizer, a phosphonium compound, a nitrogen-containing low-molecular-weight compound, and an ammonium group-containing polymer in combination, and more preferably uses, as the oil sensitizer, a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer in combination.

[0361] <Development accelerator> The image-recording layer preferably further contains a development accelerator. The development accelerator preferably has a polarity term SP value of 6.0 to 26.0, more preferably 6.2 to 24.0, even more preferably 6.3 to 23.5, and particularly preferably 6.4 to 22.0.

[0362] The SP value in this disclosure (solubility parameter, unit: (cal / cm 3 ) 1 / 2The value of the polar term in (3) is the value of the polar term δp in the Hansen solubility parameter. The Hansen solubility parameter is a solubility parameter introduced by Hildebrand, which is divided into three components: a dispersion term δd, a polar term δp, and a hydrogen bonding term δh, and is expressed in a three-dimensional space. In this disclosure, the polar term δp is used. δp[cal / cm 3 ] is the Hansen solubility parameter dipole-dipole term, V [cal / cm 3 ] is the molar volume, μ[D] is the dipole moment. For δp, the following formula, simplified by Hansen and Beerbower, is generally used:

[0363]

number

[0364] The development accelerator is preferably a hydrophilic high molecular weight compound or a hydrophilic low molecular weight compound. In the present disclosure, hydrophilicity refers to a value of the polar term of the SP value of 6.0 to 26.0, a hydrophilic polymer compound refers to a compound having a molecular weight (weight average molecular weight if there is a molecular weight distribution) of 3,000 or more, and a hydrophilic low molecular weight compound refers to a compound having a molecular weight (weight average molecular weight if there is a molecular weight distribution) of less than 3,000.

[0365] Examples of hydrophilic polymer compounds include cellulose compounds, and cellulose compounds are preferred. Examples of the cellulose compound include cellulose and a compound in which at least a part of cellulose is modified (that is, a modified cellulose compound), and the modified cellulose compound is preferred. Preferred examples of modified cellulose compounds include compounds in which at least a portion of the hydroxy groups of cellulose have been substituted with at least one group selected from the group consisting of alkyl groups and hydroxyalkyl groups. The degree of substitution of the compound in which at least a portion of the hydroxy groups of the cellulose are substituted with at least one group selected from the group consisting of alkyl groups and hydroxyalkyl groups is preferably 0.1 to 6.0, and more preferably 1 to 4. The modified cellulose compound is preferably an alkyl cellulose compound or a hydroxyalkyl cellulose compound, more preferably a hydroxyalkyl cellulose compound. A preferred example of the alkyl cellulose compound is methyl cellulose. A preferred example of the hydroxyalkyl cellulose compound is hydroxypropyl cellulose.

[0366] The molecular weight of the hydrophilic polymer compound (however, when the molecular weight distribution is present, the weight average molecular weight) is preferably 3,000 to 5,000,000, and more preferably 5,000 to 200,000.

[0367] Examples of the hydrophilic low-molecular-weight compound include glycol compounds, polyol compounds, organic amine compounds, organic sulfonic acid compounds, organic sulfamine compounds, organic sulfuric acid compounds, organic phosphonic acid compounds, organic carboxylic acid compounds, and betaine compounds, and polyol compounds, organic sulfonic acid compounds, and betaine compounds are preferred.

[0368] Examples of glycol compounds include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, and ether or ester derivatives of these compounds. Examples of the polyol compound include glycerin, pentaerythritol, and tris(2-hydroxyethyl)isocyanurate. Examples of the organic amine compound include triethanolamine, diethanolamine, monoethanolamine, and salts thereof. Examples of the organic sulfonic acid compound include alkylsulfonic acid, toluenesulfonic acid, benzenesulfonic acid, and salts thereof, and preferred examples include alkylsulfonic acids in which the alkyl group has 1 to 10 carbon atoms. The organic sulfamine compounds include alkylsulfamic acids and salts thereof. Examples of the organic sulfate compound include alkyl sulfate, alkyl ether sulfate, and salts thereof. The organic phosphonic acid compounds include phenylphosphonic acid and salts thereof. Examples of the organic carboxylic acid compound include tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, and salts thereof. Examples of the betaine compound include a phosphobetaine compound, a sulfobetaine compound, and a carboxybetaine compound, and a preferred example is trimethylglycine.

[0369] The molecular weight of the hydrophilic low-molecular-weight compound (however, if it has a molecular weight distribution, the weight-average molecular weight) is preferably 100 or more and less than 3,000, and more preferably 300 to 2,500.

[0370] The development accelerator is preferably a compound having a cyclic structure. The cyclic structure is not particularly limited, but examples thereof include a glucose ring in which at least a portion of the hydroxy groups may be substituted, an isocyanuric ring, an aromatic ring which may have a heteroatom, and an aliphatic ring which may have a heteroatom, and preferably includes a glucose ring or an isocyanuric ring. Examples of compounds having a glucose ring include the above-mentioned cellulose compounds. Examples of compounds having an isocyanuric ring include the above-mentioned tris(2-hydroxyethyl) isocyanurate. Examples of compounds having an aromatic ring include the above-mentioned toluenesulfonic acid and benzenesulfonic acid. Examples of the compound having an aliphatic ring include the above-mentioned alkyl sulfates in which the alkyl group has a ring structure.

[0371] The compound having a cyclic structure preferably has a hydroxy group. Preferred examples of the compound having a hydroxy group and a cyclic structure include the above-mentioned cellulose compounds and the above-mentioned tris(2-hydroxyethyl)isocyanurate.

[0372] The development accelerator is preferably an onium salt compound. Examples of the onium salt compound include ammonium compounds and sulfonium compounds, with ammonium compounds being preferred. Examples of the development accelerator which is an onium salt compound include trimethylglycine. The onium salt compounds in the electron-accepting polymerization initiators are compounds in which the value of the polarity term of the SP value is not 6.0 to 26.0, and are not included in the development accelerators.

[0373] The image recording layer may contain one type of development accelerator alone, or two or more types may be used in combination. One preferred embodiment of the image recording layer is an embodiment in which the image recording layer contains two or more compounds as development accelerators. Specifically, from the viewpoint of on-press developability and ink receptivity, the image recording layer preferably contains, as a development accelerator, the above-mentioned polyol compound and the above-mentioned betaine compound, the above-mentioned betaine compound and the above-mentioned organic sulfonic acid compound, or the above-mentioned polyol compound and the above-mentioned organic sulfonic acid compound.

[0374] The content of the development accelerator relative to the total mass of the image recording layer is preferably from 0.1 to 20% by mass, more preferably from 0.5 to 15% by mass, and even more preferably from 1 to 10% by mass.

[0375] <Surfactant> The image recording layer preferably contains a surfactant from the viewpoints of accelerating on-press developability and improving the coated surface condition. Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, fluorine-based surfactants, etc. The surfactants may be used alone or in combination of two or more.

[0376] The nonionic surfactant is not particularly limited, and conventionally known surfactants can be used.For example, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrylphenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono-fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylenated castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxide, polyethylene glycol, and copolymers of polyethylene glycol and polypropylene glycol can be mentioned.

[0377] The anionic surfactant is not particularly limited, and conventionally known surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkanesulfonates, alkanesulfonates, dialkylsulfosuccinate salts, linear alkylbenzenesulfonates, branched alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylphenoxypolyoxyethylenepropylsulfonates, polyoxyethylene alkylsulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkylsulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef tallow oil, sulfate ester salts of fatty acid alkyl esters, alkane sulf ... dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate Examples of such esters include alkyl sulfate salts, polyoxyethylene alkyl ether sulfate salts, fatty acid monoglyceride sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, polyoxyethylene styrylphenyl ether sulfate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, polyoxyethylene alkylphenyl ether phosphate salts, partially saponified products of styrene / maleic anhydride copolymers, partially saponified products of olefin / maleic anhydride copolymers, and naphthalenesulfonate formalin condensates.

[0378] The cationic surfactant is not particularly limited, and conventionally known surfactants can be used, such as alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives. The amphoteric surfactant is not particularly limited, and conventionally known surfactants can be used, such as carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid esters, and imitazolines.

[0379] In addition, among the above surfactants, "polyoxyethylene" can be read as "polyoxyalkylene" such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc., and these surfactants can also be used.

[0380] More preferred surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorine-based surfactants include anionic surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric surfactants such as perfluoroalkyl betaines; cationic surfactants such as perfluoroalkyl trimethyl ammonium salts; and nonionic surfactants such as perfluoroalkyl amine oxides, perfluoroalkyl ethylene oxide adducts, oligomers containing perfluoroalkyl groups and hydrophilic groups, oligomers containing perfluoroalkyl groups and lipophilic groups, oligomers containing perfluoroalkyl groups, hydrophilic groups, and lipophilic groups, and urethanes containing perfluoroalkyl groups and lipophilic groups. In addition, preferred examples of the fluorine-based surfactants described in JP-A-62-170950, JP-A-62-226143, and JP-A-60-168144 are also included.

[0381] Furthermore, the surfactant preferably contains polymer BB. Polymer BB has a structural unit (Bb1) represented by the following formula (BI).

[0382] [ka]

[0383] In formula (BI), R B11 and R B12 each independently represents a hydrogen atom or an alkyl group, R B13 represents a hydrogen atom or a monovalent substituent, L B11 and L B12 each independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms.

[0384] R B11 and R B12Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R B11 and R B12 are preferably all hydrogen atoms.

[0385] R B13 Examples of the monovalent substituent represented by the formula (I) include an alkyl group, an alkenyl group, and an aryl group. The alkyl group, the alkenyl group, and the aryl group can be represented by the formula (I) 1 , R 2 , and R 3 The preferred embodiments are the same as those of the alkyl group, alkenyl group, and aryl group represented by the following formula: R 6 is preferably a hydrogen atom or a methyl group.

[0386] L B11 Examples of the divalent linking group represented by the formula include -C(=O)-O- (a so-called ester bond) and -C(=O)-NH-. In addition, L B11 The divalent linking group represented by the formula: is preferably an ester bond, -C(=O)-O-.

[0387] L B12 The divalent linking group represented by L B11 There are no particular limitations on the group as long as it can link L to Rh. B12 Examples of the divalent linking group represented by the formula include an alkylene group. The alkylene group is preferably an alkylene group having 2 to 10 carbon atoms, and more preferably an alkylene group having 4 to 8 carbon atoms.

[0388] The substituent containing two or more silicon atoms, represented by Rh, is not particularly limited as long as the atomic group constituting the substituent contains two or more silicon atoms. From the viewpoint of on-press developability, the substituent containing two or more silicon atoms preferably contains the silicon atoms as silicon-oxygen bonds (Si-O bonds). The substituent containing two or more silicon atoms preferably has two or more silicon-oxygen bonds, preferably three or more, and preferably 3 to 12. The substituent containing two or more silicon atoms preferably contains the silicon-oxygen bonds as a polysiloxane structure. Furthermore, from the viewpoint of on-press developability, the substituent containing two or more silicon atoms preferably has a branched structure, and more preferably has a branched structure that branches from the silicon atom at the center.

[0389] Specifically, the substituent containing two or more silicon atoms is preferably a group containing two or more structures represented by the following formula (BIa).

[0390] [ka]

[0391] In the above formula (BIa), * represents a bonding position, and R b11 , R b12 , and R b13 each independently represents an alkyl group, an alkenyl group, an aryl group, or an alkylenearyl group.

[0392] R b11 , R b12 , and R b13 Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R b11 , R b12 , and R b13Examples of the alkenyl group represented by the formula (I) include alkenyl groups having 2 to 12 carbon atoms. Specific examples of the alkenyl group include a vinyl group, a 1-propenyl group, a 1-butenyl group, a 1-methyl-1-propenyl group, a 1-cyclopentenyl group, and a 1-cyclohexenyl group. R b11 , R b12 , and R b13 Examples of the aryl group represented by the formula include aryl groups having a carbon number of 6 to 12. Specific examples of the aryl group include a phenyl group, an α-methylphenyl group, and a naphthyl group. R b11 , R b12 , and R b13 Examples of the alkylenearyl group represented by the formula include alkylenearyl groups having 7 to 30 carbon atoms.

[0393] In formula (BIa), R b11 , R b12 , and R b13 are each independently preferably an alkyl group, more preferably all the same alkyl group, further preferably all alkyl groups having 1 to 4 carbon atoms, and particularly preferably all methyl groups.

[0394] The substituent containing two or more silicon atoms is preferably a group containing three or more structures represented by the above formula (BIa), and more preferably a group containing three to six structures.

[0395] The substituent containing two or more silicon atoms is preferably a group represented by the following formula (Ba2). [ka]

[0396] In the above formula (Ba2), * represents a bonding position, and R b1 , R b2 , and R b3 each independently represents an alkyl group, an alkenyl group, an aryl group, or an alkylenearyl group. R b1, R b2 , and R b3 Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R b1 , R b2 , and R b3 Examples of the alkenyl group represented by the formula (I) include alkenyl groups having 2 to 12 carbon atoms. Specific examples of the alkenyl group include a vinyl group, a 1-propenyl group, a 1-butenyl group, a 1-methyl-1-propenyl group, a 1-cyclopentenyl group, and a 1-cyclohexenyl group. R b1 , R b2 , and R b3 Examples of the aryl group represented by the formula include aryl groups having a carbon number of 6 to 12. Specific examples of the aryl group include a phenyl group, an α-methylphenyl group, and a naphthyl group. R b1 , R b2 , and R b3 Examples of the alkylenearyl group represented by the formula include alkylenearyl groups having 7 to 30 carbon atoms.

[0397] In formula (Ba2), R b1 , R b2 , and R b3 are each independently preferably an alkyl group, more preferably all the same alkyl group, further preferably all alkyl groups having 1 to 4 carbon atoms, and particularly preferably all methyl groups.

[0398] Specific examples of the structural unit (Bb1) represented by formula (BI) include the monomers represented by K-1 to K-12. Specific examples of the monomer unit that forms the structural unit having a substituent containing two or more silicon atoms in its side chain are not limited to these. In the following structures, n is an integer from 2 to 1000.

[0399] [ka]

[0400] From the viewpoint of obtaining better on-press developability, the polymerizable BB is preferably a copolymer containing a structural unit having a substituent containing two or more silicon atoms in a side chain and a structural unit having a hydrophilic group in a side chain.

[0401] The structural unit contained in the polymerizable BB and having a hydrophilic group on the side chain is preferably a structural unit represented by the following formula (a4).

[0402] [ka]

[0403] In formula (Ba4), R B7 and R B8 each independently represents a hydrogen atom or an alkyl group, R B9 represents a hydrogen atom or a monovalent substituent, L B2 represents -C(=O)-O- or -C(=O)-NH-; L B2 and L B3 represents a single bond or a divalent linking group, and X B represents a hydrophilic group.

[0404] R B7 and R B8 The alkyl group represented by R 4 and R 5 each independently represents a hydrogen atom or an alkyl group. R B7 and R B8 Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R B7 and R B8are preferably all hydrogen atoms.

[0405] R B9 Examples of the monovalent substituent represented by the formula (I) include an alkyl group, an alkenyl group, and an aryl group. The alkyl group, the alkenyl group, and the aryl group can be represented by the formula (I) B11 , R B12 , and R B13 The preferred embodiments are the same as those of the alkyl group, alkenyl group, and aryl group represented by the following formula: R B9 is preferably a hydrogen atom or a methyl group.

[0406] L B3 The divalent linking group represented by L B2 and X B There are no particular limitations on the group as long as it can link L B3 Examples of the divalent linking group represented by the formula include an alkylene group. The alkylene group is preferably an alkylene group having 2 to 10 carbon atoms, and more preferably an alkylene group having 4 to 8 carbon atoms.

[0407] X B Examples of the hydrophilic group represented by the formula (I) include a hydroxyl group, a phosphate group, a polyalkyleneoxy group, or a group combining two or more of these. Here, examples of the polyalkyleneoxy group include a polyethyleneoxy group, a polypropyleneoxy group, a polybutyleneoxy group, or a group combining these.

[0408] Specific examples of monomer units for forming a structural unit having a hydrophilic group on a side chain include monomers represented by H-1 to H-40. Specific examples of monomer units for forming a structural unit having a hydrophilic group on a side chain are not limited to these. In the following structures, n and m each independently represent an integer of 2 to 100. In the following structures, the term "random" means that multiple types of polyalkyleneoxy groups are arranged randomly.

[0409] [ka]

[0410] [ka]

[0411] The polymer BB may contain one type of structural unit having a substituent containing two or more silicon atoms in the side chain, or may contain two or more types of structural units. In polymer BB, the content of the structural unit having a substituent containing two or more silicon atoms in its side chain may be 100% by mass, preferably 15% by mass to 70% by mass, more preferably 20% by mass to 60% by mass, and even more preferably 25% by mass to 50% by mass, relative to the mass of polymer BB. Furthermore, the polymer BB may contain one type of structural unit having a hydrophilic group on the side chain, or may contain two or more types. In polymer BB, the content of the structural unit having a hydrophilic group in the side chain is preferably 30% by mass to 85% by mass, more preferably 40% by mass to 80% by mass, and even more preferably 50% by mass to 75% by mass, relative to the mass of polymer BB.

[0412] The polymer BB may further contain other structural units. Examples of other structural units include structural units having a carboxylic acid group on the side chain. Examples of structural units having a carboxylic acid group on the side chain include (meth)acrylic acid, itaconic acid, and itaconic acid derivatives. It is preferable that the structural unit having a carboxylic acid group on the side chain is included as a structural unit separate from the structural unit having a hydrophilic group on the side chain described above. Other structural units include alkyl (meth)acrylate (alkyl group having 1 to 24 carbon atoms), styrene derivatives, maleic anhydride, maleimide anhydride, (meth)acrylonitrile, vinyl ether derivatives, and alkyl (meth)acrylamide derivatives. In polymer BB, the content of other structural units is preferably 0% by mass to 20% by mass relative to the mass of polymer BB.

[0413] The weight average molecular weight of the polymer BB is preferably from 5,000 to 100,000, more preferably from 8,000 to 60,000, from the viewpoint of obtaining an image recording layer with excellent surface condition.

[0414] Specific examples of the polymer BB include BP-1 to BP-10 shown below, but the specific examples of the polymer BB are not limited to these.

[0415] [ka]

[0416] The content of polymer BB is preferably 0.001% by mass to 0.1% by mass, and more preferably 0.002% by mass to 0.01% by mass, relative to the total mass of the image recording layer coating liquid.

[0417] In addition to the surfactants described above, other surfactants may be added, within the scope of not impairing the effects of the present disclosure, to enhance the stability of the development process or to improve the coatability, such as amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149; siloxane compounds as described in EP950517; fluorine-containing monomer copolymers as described in JP-A-11-288093; and fluorine-containing surfactants as described in JP-A-62-170950.

[0418] Specific examples of amphoteric surfactants include alkyldi(aminoethyl)glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, and N-tetradecyl-N,N-betaine (for example, trade name "Amogene K" manufactured by Daiichi Kogyo Co., Ltd.). Preferred siloxane compounds are block copolymers of dimethylsiloxane and polyalkylene oxide, and specific examples include polyalkylene oxide-modified silicones such as DBE-224, DBE-621, DBE-712, DBP-732, and DBP-534 manufactured by Chisso Corporation, and Tego Glide 100 manufactured by Tego GmbH, Germany.

[0419] Specific examples of commercially available surfactants include the following: "DOWSIL," "XIAMETER," and "SYLGARD" are registered trademarks. In the following, the fact that "DOWSIL," "XIAMETER," and "SYLGARD" are registered trademarks will be omitted.

[0420] Products manufactured by Dow Corning Toray Co., Ltd. include DOWSIL BY 16-205, DOWSIL BY 16-849 Fluid, DOWSIL FZ-3710 Fluid, DOWSIL FZ-3760, DOWSIL FZ-3785, DOWSIL SF 8417 Fluid, DOWSIL BY 16-891, DOWSIL FZ-3789, DOWSIL BY 16-839 Fluid, DOWSIL SF 8411 Fluid, DOWSIL SF 8413 Fluid, DOWSIL SF 8421 Fluid, DOWSIL BY 16-880 Fluid, DOWSIL BY 16-201, DOWSIL SF 8427 Fluid, DOWSIL SF 8428 Fluid, DOWSIL 580 WAX, DOWSIL BY 16-606, DOWSIL BY 16-846 Fluid, XIAMETER OFX-0203 Fluid, XIAMETER OFX-0230 Fluid, DOWSIL SF 8416 Fluid, DOWSIL SF 8419 Fluid, DOWSIL 501W Additive, DOWSIL FZ-2110, DOWSIL FZ-2123, DOWSIL L-7001, SYLGARD OFX-0309 Fluid, XIAMETER OFX-5211 Fluid, DOWSIL SF 8410 Fluid, DOWSIL SH 3746 Fluid, DOWSIL SH 8400 Fluid, DOWSIL SH 8700 Fluid, DOWSIL SH 510 Fluid (100 cSt, 500 cSt), DOWSIL SH 550 Fluid, DOWSIL SH 710 Fluid, DOWSIL FS 1265 Fluid, etc.

[0421] Shin-Etsu Chemical Co., Ltd.'s Shin-Etsu Silicone (registered trademark) products include the KP series: KP-124, KP-109, KP-110, KP-121, KP-118, KP-341, KP-112, KP-125, KP-101, KP-106, KP-120, KP-105, KP-104, KP-611, KP-626, KP-327, KP-323, KP-322, KP-625, KP-623, KP-624, KP-620, and KP-651 KP-652, KP-650, KP-310, KP-306, KP-301, KP-621, KP-369, KP-368, KP-126, etc., KF series, FL series, and X series, etc., KF-868, KF-865, KF-864, KF-859, KF-393, KF-860, KF-880, KF-8004, KF-8002, KF-8005, KF-867, KF-8021, KF-869, KF-861, X-22-3939A, KF-877, X-22-343, KF-101, KF-1001, X-22-2000, X-22-20 46, KF-102, X-22-4741, KF-1002, KF-1005, X-22-4039, X-22-4015, KF-200 1, KF-2004, X-22-3701E, KF-99, KF-9901, PAM-E, KF-8010, X-22-161A, X-2 2-161B, KF-8012, KF-8008, X-22-1660B-3, X-22-9409, X-22-163A, KF-105 , X-22-163A, X-22-163B, X-22-163C, X-22-169AS, X-22-169B, KF-6000, KF- 6001, KF-6002, KF-6003, X-22-164, X-22-164AS, X-22-164A, X-22-164B, X -22-164C, X-22-164E, X-22-4952, X-22-4272, KF-6123, X-22-167B, X-22- 167C, X-22-162C, X-21-5841, KF-9701, X-22-2445, X-22-168AS, X-22-168 A, X-22-168B, X-22-168-P5-B, X-22-173BX, X-22-173DX, X-22-170BX, X-2 2-170DX, X-22-176DX, X-22-176F, X-22-176GX-A, X-22-174ASX, X-22-174 BX, KF-2012, X-22-2426, X-22-2404, X-22-3710, KF-857, KF-862, KF-858, X -22-9002, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945 , KF-640, KF-642, KF-643, KF-644, KF-6020, KF-6204, X-22-4515, KF-6011,KF-6012, KF-6015, KF-6017, X-22-2516, KF-410, FL-5, X-22-821, X-22-822, FL-100-100 cs, FL-100-450cs, FL-100-1,000cs, FL-100-10,000cs, KF-412, KF-413, KF-414, KF-415, Examples include KF-4003, KF-4701, KF-4917, KF-7235B, X-22-7322, X-22-1877, X-22-715, KF-3935, KF-50-100cs, KF-50-300cs, KF-50-1,000cs, KF-50-3,000cs, KF-53, KF-54, and KF-6004.

[0422] BYK products include BYK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-313, BYK-315 N, BYK-320, BYK-322, BYK-323, BYK-325 N, BYK-326, BYK-327, BYK-330, BYK-331, BYK-333, BYK-342, BYK-345 / 346, BYK-347, BYK-348, BYK-34 9, BYK-370, BYK-375, BYK-377, BYK-378, BYK-3450, BYK-3451, BYK-3455, BYK-3456, BYK-3760, BYK-UV 3500, BYK-UV 3505, BYK-UV 3510, BYK-UV 3530, BYK-UV 3535, BYK-UV 3570, BYK-UV 3575, BYK-UV 3576, BYK-350, BYK-354, BYK-355 / 356 Acrylic Copolymer, BYK-358 N / 361 N, BYK-381 Acrylic Copolymer, BYK-392 Acrylic Copolymer, BYK-394 Acrylic Copolymer, BYK-3441 Acrylic Copolymer, BYK-399, BYK-3440, BYK-3550, BYK-3560, BYK-3565, BYK-3566, BYK-SILCLEAN 3700, BYK-SILCLEAN 3701, BYK-SILCLEAN 3720, BYK-DYNWET 800 N, etc.

[0423] <Other ingredients> The image recording layer may contain other components such as a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic particles, an inorganic layer compound, etc. For specific details, see paragraphs 0121 to 0159 of JP-A No. 2008-284817.

[0424] <<Formation of image recording layer>> The image recording layer in the lithographic printing plate precursor can be formed by dispersing or dissolving the necessary components in a known solvent to prepare a coating solution, applying the coating solution to a support by a known method such as bar coater coating, and drying, as described in paragraphs

[0142] and

[0143] of JP-A No. 2008-195018, for example. The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but is generally 0.3 g / m 2 ~3.0g / m 2 In this range, good sensitivity and good film properties of the image recording layer can be obtained. As the solvent, known solvents can be used, specifically, for example, water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy-1-propanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, ethyl lactate, etc. The solvent may be used alone or in combination of two or more. The solid content concentration in the coating liquid is preferably 1% by mass to 50% by mass. The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer, it is 0.3 g / m 2 ~3.0g / m 2 is preferred. The thickness of the image recording layer in the lithographic printing plate precursor is preferably 0.1 μm to 3.0 μm, and more preferably 0.3 μm to 2.0 μm. The film thickness of each layer in the lithographic printing plate precursor is confirmed by preparing a slice by cutting the lithographic printing plate precursor in a direction perpendicular to its surface and observing the cross section of the slice with a scanning electron microscope (SEM).

[0425] (Support) The lithographic printing plate precursor has a support. The support can be appropriately selected from known supports for lithographic printing plate precursors. The support is preferably one having a hydrophilic surface.

[0426] The support is preferably an aluminum plate that has been subjected to a surface roughening treatment and anodizing treatment by a known method, i.e., the support preferably comprises an aluminum plate and an anodized aluminum coating disposed on the aluminum plate.

[0427] Furthermore, it is preferable that the support has an aluminum plate and an anodized aluminum film disposed on the aluminum plate, the anodized film being located closer to the image recording layer than the aluminum plate, the anodized film having micropores extending in the depth direction from the surface on the image recording layer side, and the average diameter of the micropores on the surface of the anodized film being greater than 10 nm and not greater than 100 nm. Furthermore, it is preferable that the micropores are composed of large-diameter pores extending from the surface of the anodized film to a depth of 10 nm to 1,000 nm, and small-diameter pores that communicate with the bottoms of the large-diameter pores and extend from the communicating positions to a depth of 20 nm to 2,000 nm, and that the average diameter of the large-diameter pores at the surface of the anodized film is 15 nm to 100 nm, and the average diameter of the small-diameter pores at the communicating positions is 13 nm or less.

[0428] FIG. 1 is a schematic cross-sectional view of one embodiment of an aluminum support 12a. The aluminum support 12a has a laminated structure in which an aluminum plate 18 and an aluminum anodized film 20a (hereinafter simply referred to as "anodized film 20a") are laminated in this order. The anodized film 20a in the aluminum support 12a is located closer to the image recording layer than the aluminum plate 18. In other words, the lithographic printing plate precursor preferably has at least an anodized film, an image recording layer, and a water-soluble resin layer, in this order, on an aluminum plate.

[0429] -Anodic oxide film- A preferred embodiment of the anodic oxide coating 20a will now be described. The anodized film 20a is a film formed on the surface of the aluminum plate 18 by anodizing, and has extremely fine micropores 22a that are substantially perpendicular to the film surface and are distributed substantially uniformly. The micropores 22a extend from the surface of the anodized film 20a on the image recording layer side (i.e., the surface of the anodized film 20a opposite the aluminum plate 18 side) along the thickness direction (i.e., toward the aluminum plate 18 side).

[0430] The average diameter (i.e., average opening diameter) of the micropores 22a in the anodized coating 20a at the surface of the anodized coating is preferably more than 10 nm and not more than 100 nm. From the viewpoint of a balance between printing durability, stain resistance, and image visibility, the average diameter is more preferably 15 nm to 60 nm, even more preferably 20 nm to 50 nm, and particularly preferably 25 nm to 40 nm. The diameter inside the pores may be wider or narrower than that at the surface. When the average diameter exceeds 10 nm, printing durability and image visibility are excellent, and when the average diameter is 100 nm or less, printing durability is excellent. The average diameter of the micropores 22a was determined by observing the surface of the anodized film 20a using a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times, and measuring the diameter (here, diameter) of micropores present in an area of ​​400 nm x 600 nm at 50 locations in the four images obtained, and averaging the measured values. When the shape of the micropores 22a is not circular, the equivalent circle diameter is used. The "equivalent circle diameter" is the diameter of a circle when the shape of the opening is assumed to be a circle having the same projected area as the projected area of ​​the opening.

[0431] The shape of the micropores 22a is not particularly limited, and although they are generally straight (i.e., generally cylindrical) in Fig. 1, they may also be conical with a diameter that decreases in the depth direction (thickness direction). The shape of the bottom of the micropores 22a is also not particularly limited, and may be curved (convex) or flat.

[0432] In the support, the micropores may be composed of large-diameter pores extending from the surface of the anodized coating to a certain depth, and small-diameter pores communicating with the bottoms of the large-diameter pores and extending from the communicating position to a certain depth. For example, as shown in FIG. 2, an aluminum support 12b may include an aluminum plate 18 and an anodized film 20b having micropores 22b each composed of a large diameter pore portion 24 and a small diameter pore portion . For example, the micropores 22b in the anodized coating 20b are composed of large-diameter pores 24 that extend from the surface of the anodized coating to a depth of 10 nm to 1,000 nm (depth D: see FIG. 2), and small-diameter pores 26 that communicate with the bottoms of the large-diameter pores 24 and extend from the communicating position to a depth of 20 nm to 2,000 nm. Specifically, for example, the embodiments described in paragraphs 0107 to 0114 of JP 2019-162855 A can be used.

[0433] <<Support Manufacturing Method>> As a method for producing a support, for example, a production method in which the following steps are carried out in order is preferred. Surface roughening process: A process of roughening the surface of aluminum plates. Anodizing process: A process of anodizing a roughened aluminum plate. Pore ​​widening process: The aluminum plate with the anodized film obtained in the anodizing process is brought into contact with an acidic or alkaline aqueous solution to widen the diameter of the micropores in the anodized film. The procedure for each step will be described in detail below.

[0434] <<Surface roughening process>> The surface roughening step is a step of roughening the surface of an aluminum plate, including electrochemical roughening. This step is preferably performed before the anodizing step described below, but may not be necessary if the surface of the aluminum plate already has a desired surface shape. This step can be performed by the method described in paragraphs 0086 to 0101 of JP 2019-162855 A.

[0435] <<Anodizing process>> The procedure for the anodizing treatment step is not particularly limited as long as the above-mentioned micropores can be obtained, and known methods can be used. In the anodizing treatment step, an aqueous solution of sulfuric acid, phosphoric acid, oxalic acid, etc. can be used as the electrolytic bath. For example, the concentration of sulfuric acid can be 100 g / L to 300 g / L. The conditions for anodizing treatment are appropriately set depending on the electrolyte used, but for example, the solution temperature is 5°C to 70°C (preferably 10°C to 60°C), the current density is 0.5 A / dm 2 ~60A / dm 2 (preferably 1A / dm 2 ~60A / dm 2 ), voltage 1V to 100V (preferably 5V to 50V), electrolysis time 1 second to 100 seconds (preferably 5 seconds to 60 seconds), and coating amount 0.1g / m 2 ~5g / m 2 (preferably 0.2g / m 2 ~3g / m 2 ) are mentioned.

[0436] <<Porewide processing>> The pore widening treatment is a treatment for enlarging the diameter (ie, pore diameter) of the micropores present in the anodized film formed by the above-mentioned anodizing treatment step (ie, pore diameter enlarging treatment). The pore widening treatment can be carried out by bringing the aluminum plate obtained by the above-mentioned anodizing treatment step into contact with an acid aqueous solution or an alkaline aqueous solution. The contacting method is not particularly limited, and examples thereof include a dipping method and a spraying method.

[0437] If necessary, the support may have a backcoat layer on the side opposite the image recording layer, which contains an organic polymer compound described in JP-A-5-45885 or a silicon alkoxy compound described in JP-A-6-35174.

[0438] <Undercoat layer> The lithographic printing plate precursor preferably has an undercoat layer (sometimes called an intermediate layer) between the image recording layer and the support. The undercoat layer strengthens adhesion between the support and the image recording layer in exposed areas and facilitates peeling of the image recording layer from the support in unexposed areas, thereby contributing to improving developability while suppressing a decrease in printing durability. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, thereby preventing heat generated by exposure from diffusing to the support and reducing sensitivity.

[0439] Compounds used in the undercoat layer include polymers having an adsorptive group and a hydrophilic group that can be adsorbed to the support surface. Polymers having an adsorptive group and a hydrophilic group and also a crosslinkable group are preferred to improve adhesion to the image recording layer. The compounds used in the undercoat layer may be low-molecular-weight compounds or polymers. Two or more compounds may be mixed together as needed.

[0440] When the compound used in the undercoat layer is a polymer, it is preferably a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group. Preferred adsorptive groups that can be adsorbed onto the surface of a support include phenolic hydroxy groups, carboxy groups, -PO3H2, -OPO3H2, -CONHSO2-, -SON2NHSO2-, and -COCH2COCH3. Preferred hydrophilic groups include sulfo groups or salts thereof, and carboxy group salts. Preferred crosslinkable groups include acrylic groups, methacrylic groups, acrylamide groups, methacrylamide groups, and allyl groups. The polymer may have a crosslinkable group introduced by salt formation between a polar substituent of the polymer and a compound having an ethylenically unsaturated bond and a substituent having an opposite charge to the polar substituent, or may be further copolymerized with a monomer other than the above, preferably a hydrophilic monomer.

[0441] Specific examples of suitable compounds include a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group, as described in JP-A-10-282679, and a phosphorus compound having an ethylenic double bond reactive group, as described in JP-A-2-304441. Also preferred are low-molecular-weight or high-molecular-weight compounds having a crosslinkable group (preferably an ethylenically unsaturated bond group), a functional group that interacts with the support surface, and a hydrophilic group, as described in JP-A-2005-238816, JP-A-2005-125749, JP-A-2006-239867, and JP-A-2006-215263. More preferred examples include high molecular weight polymers having adsorptive groups, hydrophilic groups, and crosslinkable groups capable of being adsorbed onto the surface of a support, as described in JP-A Nos. 2005-125749 and 2006-188038.

[0442] The content of the ethylenically unsaturated bond group in the polymer used in the undercoat layer is preferably 0.1 mmol to 10.0 mmol, and more preferably 0.2 mmol to 5.5 mmol, per 1 g of the polymer. The weight average molecular weight (Mw) of the polymer used in the undercoat layer is preferably 5,000 or more, more preferably 10,000 to 300,000.

[0443] In addition to the above-described compounds for the undercoat layer, the undercoat layer may contain, in order to prevent contamination over time, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, a compound having an amino group or a functional group having polymerization inhibitory ability and a group that interacts with the support surface (e.g., 1,4-diazabicyclo[2.2.2]octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, etc.), etc.

[0444] The undercoat layer is applied by a known method. The coating amount (solid content) of the undercoat layer is 0.1 mg / m 2 ~100mg / m 2 is preferred, and 1 mg / m 2 ~30mg / m 2 is more preferred.

[0445] <Outermost layer> The lithographic printing plate precursor may have an outermost layer (sometimes called a "protective layer" or "overcoat layer") on the surface of the image recording layer opposite to the support side. The lithographic printing plate precursor preferably has a support, an image recording layer, an outermost layer, and an on-press development type lithographic printing plate precursor in this order. The outermost layer may have the function of preventing image formation inhibiting reactions by blocking oxygen, as well as the function of preventing scratches on the image recording layer and ablation during exposure to high-intensity laser light.

[0446] The outermost layer can be a known outermost layer ("protective layer" or "overcoat layer") in an on-press development type lithographic printing plate precursor. Specifically, the outermost layer described in paragraphs 0444 to 0462 of WO 2022 / 019217 can be suitably used.

[0447] The lithographic printing plate precursor may have layers other than those described above. The other layers are not particularly limited, and any known layers may be used. For example, a backcoat layer may be provided on the side of the support opposite to the image recording layer side, as needed.

[0448] (Method for manufacturing a lithographic printing plate and lithographic printing method) A lithographic printing plate can be produced by imagewise exposing a lithographic printing plate precursor and then subjecting it to a development treatment. The method for manufacturing a lithographic printing plate preferably includes a step of exposing a lithographic printing plate precursor to light in an imagewise manner (hereinafter also referred to as an "exposure step"), and a step of supplying a plate surface treatment agent on a printing press to remove the image recording layer in non-image areas (hereinafter also referred to as an "on-press development step"). The lithographic printing method preferably includes a step of exposing a lithographic printing plate precursor imagewise (i.e., an exposure step), a step of supplying a plate surface treatment agent and removing the image recording layer in the non-image area on the printing press to prepare a lithographic printing plate (i.e., an on-press development step), and a step of printing with the obtained lithographic printing plate (i.e., a printing step).

[0449] Further, a method for producing a lithographic printing plate includes a step of imagewise exposing a lithographic printing plate precursor to an infrared laser, and a step of supplying a plate surface treatment agent on a printing press to remove the image recording layer in a non-image area, wherein the lithographic printing plate precursor has a support and an image recording layer on the support, the image recording layer contains an infrared absorber capable of donating an electron to the initiator, and a color former precursor, and the energy density of the infrared laser exposure at a wavelength of 830 nm is 110 mJ / cm. 2 Preferably, the method for producing a lithographic printing plate is such that when the image recording layer is exposed to light at a rate of 1000 kJ / cm², the change in lightness ΔL of the image recording layer before and after the exposure is 3.0 or more. Furthermore, the method for producing a lithographic printing plate preferably includes a step of imagewise exposing a lithographic printing plate precursor to an infrared laser, and a step of supplying a plate surface treatment agent on a printing press to remove the image recording layer in non-image areas, wherein the lithographic printing plate precursor has a support and an image recording layer on the support, the image recording layer contains an initiator, an infrared absorber, and a color former precursor, and the image recording layer satisfies the following formula L: 2.0≦L1-L0 Formula L In the formula L, L1 represents the visibility of the image recording layer, and L0 represents the visibility of a layer that is the same as the image recording layer except for the absence of the color former precursor. Furthermore, with regard to the lithographic printing method, each of these embodiments preferably further includes the printing step described above.

[0450] Hereinafter, preferred embodiments of each step of the method for producing a lithographic printing plate and the lithographic printing method will be described in order. The lithographic printing plate precursor can also be developed using a developer. The exposure step and on-press development step in the method for producing a lithographic printing plate will be described below. The exposure step in the method for producing a lithographic printing plate and the exposure step in the lithographic printing method are the same step, and the on-press development step in the method for producing a lithographic printing plate and the on-press development step in the lithographic printing method are the same step.

[0451] <Exposure process> The method for preparing a lithographic printing plate preferably includes an exposure step in which a lithographic printing plate precursor is imagewise exposed to form exposed and unexposed areas. The lithographic printing plate precursor is preferably imagewise exposed to laser light through a transparent original having a line image, a halftone dot image, or the like, or by laser light scanning using digital data. The wavelength of the light source used is preferably 750 nm to 1,400 nm. As a light source with a wavelength of 750 nm to 1,400 nm, a solid-state laser or semiconductor laser that emits infrared light is suitable. With regard to the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably 20 microseconds or less, and the irradiation energy amount is preferably 10 mJ / cm. 2 ~300mJ / cm 2 It is preferable to use a multi-beam laser device in order to shorten the exposure time. The exposure mechanism may be any of an internal drum type, an external drum type, a flatbed type, or the like. Image exposure can be carried out by a conventional method using a plate setter, etc. In the case of on-press development, the lithographic printing plate precursor may be mounted on a printing press and then image exposure may be carried out on the printing press.

[0452] <On-press development process> The method for preparing a lithographic printing plate preferably includes an on-press development step in which a plate surface treatment agent is supplied on the printing press to remove the image recording layer in the non-image areas. The on-press development method will be described below.

[0453] [On-press development method] In the on-press development method, it is preferred that a plate surface treatment agent is supplied to the image-exposed lithographic printing plate precursor on the printing press, and the image recording layer in the non-image areas is removed to prepare a lithographic printing plate. That is, after imagewise exposure of a lithographic printing plate precursor, a plate surface treatment agent is applied and then the plate is mounted on a printing press; alternatively, after the lithographic printing plate precursor is mounted on a printing press and imagewise exposed on the press, a plate surface treatment agent is applied and then printing is performed. The uncured image-recording layer is dissolved or dispersed and removed by the plate surface treatment agent, exposing a hydrophilic surface in that area. Meanwhile, in the exposed areas, the image-recording layer cured by exposure forms an oil-based ink-receptive area with an oleophilic surface. In this way, the lithographic printing plate precursor is developed on the printing press and used as is for printing a large number of sheets. As the plate surface treatment agent, one containing the specific components described above is preferably used, and as the oil-based ink used for printing, a printing ink for ordinary lithographic printing is preferably used.

[0454] The wavelength of the laser light source used for imagewise exposure of the lithographic printing plate precursor is preferably 300 nm to 450 nm or 750 nm to 1,400 nm. In the case of a light source of 300 nm to 450 nm, a lithographic printing plate precursor containing in the image recording layer a sensitizing dye having an absorption maximum in this wavelength region is preferably used, and for a light source of 750 nm to 1,400 nm, the above-mentioned light sources are preferably used. As a light source of 300 nm to 450 nm, a semiconductor laser is suitable.

[0455] <Printing process> The lithographic printing method includes a printing step in which printing ink is supplied to a lithographic printing plate to print a recording medium. The printing ink is not particularly limited, and various known inks can be used as desired. Preferred examples of the printing ink include oil-based ink and ultraviolet-curable ink (i.e., UV ink). In the printing process, dampening water may be supplied as needed. The printing step may be carried out consecutively to the on-press development step without stopping the printing press. The recording medium is not particularly limited, and any known recording medium can be used as desired.

[0456] In the method for preparing a lithographic printing plate from a lithographic printing plate precursor and in the lithographic printing method, the entire surface of the lithographic printing plate precursor may be heated, as necessary, before exposure, during exposure, or between exposure and development. Such heating promotes the image-forming reaction in the image-recording layer, resulting in advantages such as improved sensitivity and printing durability and stabilized sensitivity. Heating before development is preferably carried out under mild conditions at 150°C or less. This embodiment can prevent problems such as hardening of non-image areas. Heating after development is preferably carried out under very strong conditions, preferably in the range of 100°C to 500°C. Within this range, sufficient image strengthening effect can be obtained and problems such as support deterioration and thermal decomposition of image areas can be suppressed.

[0457] (Lithographic printing method that improves ink adhesion) A lithographic printing method that is one embodiment of the present disclosure comprises the steps of applying a plate surface treatment agent, different from the printing ink, to the surface of a lithographic printing plate used for printing, and printing using the lithographic printing plate after the application of the plate surface treatment agent, wherein the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, and the oil phase contains an extender pigment.

[0458] The lithographic printing method includes a step of applying a plate surface treatment agent different from the printing ink to the surface of the lithographic printing plate used for printing (hereinafter also referred to as the "plate surface treatment agent application step"). The plate surface treatment agent is the same as that described above, so a description thereof will be omitted here.

[0459] In the plate surface treatment agent application step, the lithographic printing plate to which the plate surface treatment agent is applied may be a lithographic printing plate that has been used for printing, and any development method may be used. For example, by applying the above-mentioned plate surface treatment agent to the plate surface of a lithographic printing plate that has poor ink receptivity, the ink receptivity of the lithographic printing plate can be improved. Therefore, the above-mentioned lithographic printing method is a lithographic printing method that improves ink receptivity, allowing printing while improving the ink receptivity of a lithographic printing plate that has been used for printing.

[0460] Although a plate surface treatment agent is different from printing ink, it can be used as ink in the process. Therefore, in the plate surface treatment agent application step in a lithographic printing method for improving ink receptivity, printing can be carried out using ink as a plate surface treatment agent while the lithographic printing plate is still attached to the printing press, thereby applying a plate surface treatment agent different from the printing ink to the plate surface of the lithographic printing plate used for printing, or the plate surface treatment agent can be applied after the lithographic printing plate is removed from the printing press. The plate surface treatment agent is the same as that described above, and therefore a description thereof will be omitted here. [Example]

[0461] The present disclosure will be described in further detail below based on examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present disclosure. Therefore, the scope of the present disclosure should not be construed as being limited by the following examples. In the following, unless otherwise specified, "parts" and "%" are by mass.

[0462] Example 1 Plate surface treatment agent a was prepared as follows: 7.2 parts by weight of water-soluble resin was dissolved in 64 parts by weight of pure water while heating. Next, 2 parts by weight of sodium hexametaphosphate was dissolved with stirring, and 0.6 parts by weight of potassium sulfate and 0.6 parts by weight of potassium nitrate were added and mixed to prepare an aqueous phase. Phosphoric acid was then added little by little to adjust the aqueous phase to pH 2.0. Meanwhile, an oil phase was prepared by dissolving 10 parts by weight of tetrahydronaphthalene, 10 parts by weight of medium ink, 0.14 parts by weight of Pionin A-51G, and then 0.05 parts by weight of Nonion OP-80R. Next, the aqueous phase prepared as described above was stirred and heated to 35°C, and the oil phase was slowly added dropwise to prepare a dispersion. Finally, water was added to make the total amount 100 parts by mass. After that, the mixture was passed through a homogenizer to prepare a milky white plate surface treatment agent a. The plate surface treatment agent a thus obtained had the same pH as the aqueous phase, 2.0. The composition of plate surface treatment agent a is shown in Table 1. Details of the materials shown in Table 1 are as follows.

[0463] Soy Gum K-31: Fuji Oil Co., Ltd. Snowtex OL: Nissan Chemical Co., Ltd. BioHope L: Manufactured by K.I. Chemicals Medium ink: F Gloss Medium, manufactured by DIC Black ink: F Gloss Medium, manufactured by DIC Paionin A-51G: Takemoto Oil & Fat Co., Ltd. Nonion OP-80R: Nissan Chemical Co., Ltd. Water: Distilled water

[0464] (Example 2, Comparative Examples 1 to 3) In the same manner as in Example 1, plate surface treatment agents b to e were prepared according to the compositions shown in Table 1. Plate surface treatment agent E was composed of only an aqueous phase. The aqueous phase consisted of a dampening solution (PRESSMAX S-Z1 manufactured by Fujifilm Corporation) diluted twice (by mass) with water. In Table 1, blank spaces indicate no addition.

[0465] [Table 1]

[0466] (Preparation of on-press development type lithographic printing plate precursor) An on-press development type lithographic printing plate precursor to which a plate surface treatment agent was applied was prepared as follows.

[0467] <Preparation of support> A 0.3 mm thick aluminum plate (aluminum alloy plate) made of 1050 material was subjected to the following treatments to manufacture a support 1. Note that water rinsing treatment was performed between all treatment steps, and after the water rinsing treatment, the liquid was removed using nip rollers.

[0468] <<Alkaline etching treatment>> The aluminum plate obtained above was subjected to an etching treatment by spraying an aqueous solution of caustic soda containing 26% by mass of caustic soda and 6.5% by mass of aluminum ions at a temperature of 70°C. Thereafter, the plate was washed with water by spraying. The amount of dissolved aluminum was 5 g / m 2 It was.

[0469] <<Desmutting treatment using an acidic aqueous solution>> Next, a desmutting treatment was carried out using an aqueous nitric acid solution. Specifically, the nitric acid solution was sprayed onto the aluminum plate for 3 seconds. The nitric acid solution used in the desmutting treatment was the waste nitric acid solution used in the subsequent electrochemical graining treatment. The liquid temperature was 35°C.

[0470] <<Electrochemical roughening treatment>> Continuous electrochemical roughening treatment was carried out using nitric acid electrolysis at a 60 Hz AC voltage. The electrolyte used was an aqueous solution of 10.4 g / L nitric acid with aluminum nitrate added to adjust the aluminum ion concentration to 4.5 g / L, and the solution temperature was 50°C. The AC power waveform was as shown in Figure 3, with a time tp from zero to peak of 0.8 msec, a duty ratio of 1:1, and a trapezoidal square wave AC current. Electrochemical roughening treatment was carried out using a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The electrolytic cell used was as shown in Figure 4. The current density was 71 A / dm at the peak current value of the AC current waveform. 2 5% of the current flowing from the power supply was diverted to the auxiliary anode. 2 ) is the total amount of electricity when the aluminum plate is the anode, 205C / dm 2 After that, the surface was washed with water using a spray.

[0471] <<Alkaline etching treatment>> The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda containing 5% by mass of caustic soda and 0.5% by mass of aluminum ions onto the aluminum plate at a temperature of 35°C. The aluminum plate was then rinsed with water by spraying. The amount of dissolved aluminum was 0.2 g / m2 It was.

[0472] <<Desmutting treatment using an acidic aqueous solution>> Next, a desmutting treatment was carried out using an aqueous sulfuric acid solution. Specifically, the aqueous sulfuric acid solution was sprayed onto the aluminum plate for 3 seconds. The aqueous sulfuric acid solution used for the desmutting treatment had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The liquid temperature was 30°C.

[0473] <<Electrochemical roughening treatment>> Continuous electrochemical roughening treatment was carried out using hydrochloric acid electrolysis at 60 Hz AC voltage. The electrolyte used was an aqueous solution of 5.0 g / L hydrochloric acid with aluminum chloride added to adjust the aluminum ion concentration to 4.5 g / L, with a solution temperature of 35°C. The AC power waveform was as shown in Figure 3, with a time tp from zero to peak of the current being 0.8 msec, a duty ratio of 1:1, and a trapezoidal square wave AC, and electrochemical roughening treatment was carried out using a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The electrolytic cell used was as shown in Figure 4. The current density was 71 A / dm2 at the peak current value of the AC current waveform. 5% of the current flowing from the power source was shunted to the auxiliary anode. The quantity of electricity (C / dm 2 ) is the total amount of electricity when the aluminum plate is an anode, 75C / dm 2 After that, the surface was washed with water using a spray.

[0474] <<Alkaline etching treatment>> The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda containing 5% by mass of caustic soda and 0.5% by mass of aluminum ions onto the plate at a temperature of 35°C. The plate was then rinsed with water using a spray. The amount of dissolved aluminum was 0.05 g / m 2 It was.

[0475] <<Desmutting treatment using an acidic aqueous solution>> Next, a desmutting treatment was carried out using an aqueous sulfuric acid solution. Specifically, the aqueous sulfuric acid solution was sprayed onto the aluminum plate for 3 seconds. The aqueous sulfuric acid solution used for the desmutting treatment was specifically wastewater generated in the anodizing treatment process (an aqueous solution with a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L). The liquid temperature was 35°C.

[0476] <<First stage anodizing treatment>> The first stage of anodizing treatment was carried out using a DC electrolysis anodizing apparatus with the structure shown in Figure 5. The electrolyte used was adjusted to 170 g / L of sulfuric acid and 7.5 g / L of aluminum ion concentration, with a liquid temperature of 43°C. The current density was 30 A / dm 2 The coating amount was 0.2 g / m 2 An anodic oxide film was formed.

[0477] <Pore-wide processing> The anodized aluminum plate was immersed in an aqueous solution of caustic soda with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass at 35°C to perform a pore widening treatment, followed by spray washing with water.

[0478] <Second stage anodizing treatment> The second stage of anodizing treatment was carried out using a DC electrolysis anodizing apparatus with the structure shown in Figure 5. The electrolyte used was adjusted to 170 g / L of sulfuric acid and 7.5 g / L of aluminum ion concentration, with a liquid temperature of 52°C. The current density was 13 A / dm 2 The coating amount was 2.3g / m 2 An anodic oxide film of the above formula was formed on the aluminum substrate to prepare an aluminum support.

[0479] <Formation of undercoat layer> On the support prepared above, a coating solution for an undercoat layer having the following composition was applied in a dry amount of 0.1 g / m 2 The undercoat layer was formed by coating the mixture so that the thickness became

[0480] [Coating liquid for undercoat layer] Undercoat layer compound (U-1 below, 11% aqueous solution): 0.10502 parts Sodium gluconate: 0.0700 parts Surfactant (Emalex (registered trademark) 710, Nippon Emulsion Co., Ltd.): 0.00159 parts Preservative (BioHope L, K.I. Chemical Co., Ltd.): 0.00149 parts ·Wed: 3.29000 copies

[0481] [ka]

[0482] <Formation of image recording layer> The image recording layer coating solution described below was applied onto the undercoat layer with a bar and dried in an oven at 120°C for 40 seconds to give a dry coating amount of 1.0 g / m 2 An image recording layer of the above formula was formed.

[0483] -Image recording layer coating liquid- Each of the components shown below was dissolved or dispersed in a mixed solvent of 1-methoxy-2-propanol (MFG), methyl ethyl ketone (MEK) and methanol (MFG:MEK:methanol = 4:4:1 (mass ratio)) to prepare an image recording layer coating solution with a solid content of 6%.

[0484] <Formation of image recording layer> Infrared absorber (A-1): 0.0080 parts Infrared absorber (A-2): 0.0270 parts Borate compound (B-1): 0.0200 parts Iodonium compound (C-1): 0.1000 parts Color precursor (D-1): 0.0300 parts Color precursor (D-2): 0.0120 parts Polymerizable compound (M-1 below): 0.1908 parts Anionic surfactant (W-1): 0.0060 parts Fluorine-based surfactant (W-2): 0.0042 parts Additive (P-1): 0.0125 parts Microgel (1): 2.0000 parts

[0485] [ka]

[0486] <Polymerizable compound (M-1) synthesis method> A mixed solution of Takenate D-160N (polyisocyanate trimethylolpropane adduct, manufactured by Mitsui Chemicals, Inc., 4.7 parts), Aronix M-403 (manufactured by Toagosei Co., Ltd., in an amount such that the NCO value of Takenate D-160N and the hydroxyl value of Aronix M-403 were 1:1), t-butylbenzoquinone (0.02 parts), and methyl ethyl ketone (11.5 parts) was heated to 65°C. Neostan U-600 (bismuth-based polycondensation catalyst, manufactured by Nitto Kasei Co., Ltd., 0.11 parts) was added to the reaction solution, and the mixture was heated at 65°C for 4 hours. The reaction solution was cooled to room temperature (25°C), and methyl ethyl ketone was added to synthesize a urethane acrylate (M-1) solution with a solids content of 50% by mass.

[0487] <Preparation method of microgel (1)> The method for preparing the above microgel (1) is as follows.

[0488] (Preparation of polyisocyanate compound (1)) To a suspension of 17.78 g (80 mmol) of isophorone diisocyanate and 7.35 g (20 mmol) of the following polyhydric phenol compound (1) in 25.31 g of ethyl acetate, 43 mg of bismuth tris(2-ethylhexanoate) (Neostan U-600, manufactured by Nitto Kasei Co., Ltd.) was added and stirred. Once the heat generation subsided, the reaction temperature was set to 50°C, and the mixture was stirred for 3 hours to obtain an ethyl acetate solution (50% by mass) of the polyhydric isocyanate compound (1).

[0489] [ka]

[0490] (Preparation of Microgel (1)) The oil phase and aqueous phase components listed below were mixed and emulsified using a homogenizer at 12,000 rpm for 10 minutes. The resulting emulsion was stirred at 45°C for 4 hours, after which 5.20 g of a 10% by weight aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene-octylate (U-CAT SA102, manufactured by San-Apro Co., Ltd.) was added, stirred at room temperature for 30 minutes, and allowed to stand at 45°C for 24 hours. The solids concentration was adjusted to 20% by weight with distilled water, yielding an aqueous dispersion of microgel (1). The average particle size was measured by light scattering and found to be 0.28 μm.

[0491] -Oil phase components- (Component 1) Ethyl acetate: 12.0g (Component 2) 3.76 g of an adduct (50% by mass ethyl acetate solution, manufactured by Mitsui Chemicals, Inc.) obtained by adding trimethylolpropane (6 moles) and xylene diisocyanate (18 moles) to which methyl-terminated polyoxyethylene (1 mole, number of repeating oxyethylene units: 90) was added. (Component 3) Polyisocyanate compound (1) (as a 50% by mass ethyl acetate solution): 15.0 g (Component 4) 65% by weight ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Corporation): 11.54 g (Component 5) 10% ethyl acetate solution of sulfonate surfactant (Paionin A-41-C, manufactured by Takemoto Oil & Fat Co., Ltd.): 4.42 g

[0492] -Aqueous phase components- Distilled water: 46.87g

[0493] <Formation of protective layer> A protective layer coating solution having the following composition was applied onto the image recording layer with a bar, and dried in an oven at 120°C for 60 seconds to obtain a dry coating weight of 0.15 g / m 2 A protective layer of the above was formed to prepare planographic printing plate precursors to be used in Example 4, Comparative Example 4 and Comparative Example 5 below.

[0494] -Protective layer coating liquid- Inorganic layered compound dispersion (1) [below]: 1.948 parts Hydrophilic polymer (1) (structure shown below, Mw: 30,000) (solid content): 0.057 parts Polyvinyl alcohol (CKS50, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., sulfonic acid modified, saponification degree 99 mol% or more, polymerization degree 300): 0.013 parts Polyvinyl alcohol (PVA-405, manufactured by Kuraray Co., Ltd., saponification degree 81.5 mol%, polymerization degree 500): 0.001 part Surfactant (Rapisol A-80 (see below), manufactured by NOF Corporation): 0.013 parts ·Pure water: 6,000 parts

[0495] The method for preparing the inorganic layer compound dispersion (1) used in the protective layer coating solution is described below.

[0496] <Preparation of Inorganic Layered Compound Dispersion (1)> 6.4 parts of synthetic mica (Somasif ME-100, manufactured by Co-op Chemical Co., Ltd.) was added to 193.6 parts of ion-exchanged water, and the mixture was dispersed using a homogenizer until the average particle size (laser scattering method) reached 3 μm. The aspect ratio of the resulting dispersed particles was 100 or more.

[0497] [ka]

[0498] [ka]

[0499] (evaluation) The following tests were carried out on the plate surface treatment agents obtained in Examples 1 and 2 and Comparative Examples 1 to 3. The evaluation results are shown in Table 2.

[0500] <Evaluation method 1: Evaluation of ink receptivity after development> The plate surface treatment agent was soaked into a sponge or cloth, and applied to a lithographic printing plate exposed under the following conditions, followed by manual development. The exposure conditions were a thermal laser setter (Quantum manufactured by CREO) at 200 lpi (lines per inch), and the exposed areas were, in the longitudinal direction, exposed in order to form a solid area and an image with a 30% to 100% gradation mesh pattern. After the development was completed, printing ink was supplied to the developed lithographic printing plate with an ink roller, and the ink receptivity of the exposed image area was visually evaluated. The lithographic printing plate precursor used was the on-press development type lithographic printing plate precursor prepared above.

[0501] The evaluation criteria were as follows: A: Printing ink is applied to the image area. B: The image area is covered with printing ink, but some areas are not covered with ink. C: Printing ink does not adhere to the image area

[0502] <Evaluation method 2: Ink receptivity evaluation by printing> The above-mentioned exposed lithographic printing plate was attached to a printing press, and before printing, the exposed plate was developed with a sponge or cloth soaked in a plate surface treatment agent. After development, printing was carried out according to the following printing conditions, and the number of ink-bearing sheets was evaluated. The lithographic printing plate precursor used was the on-press development type lithographic printing plate precursor prepared above. The printing conditions are as follows: Printing machine: Oliver (manufactured by Sakurai Graphic Systems) Printing ink: DIC Fusion G Red oil-based process ink Dampening water: Dilute Fujifilm PRESSMAX S-Z1

[0503] The evaluation criteria were as follows: 1) Fleshability A: It was printed for the first time within 15 pages. B: The first ink was applied when the number of printed sheets was between 16 and 30. C: The first ink was applied to 31 or more printed sheets. 2) Ink turbidity A: The color of the printing ink did not change. B: The color of the printing ink has changed slightly. C: The color of the printing ink has clearly changed.

[0504] <Evaluation method 3: Evaluation of improvement in ink receptivity> The exposed lithographic printing plate was developed on the printing press, and then removed, the printing ink on the plate was removed, and a surface treatment agent was applied to the plate surface using a sponge or cloth soaked in the agent. The plate was then reattached to the printing press and reprinted, and the number of sheets until the first ink was applied was evaluated. The lithographic printing plate precursor used was the on-press development type lithographic printing plate precursor prepared above. The printing conditions are as follows: Printing machine: Oliver (manufactured by Sakurai Graphic Systems) Printing ink: DIC Fusion G Red oil-based process ink Dampening water: Dilute Fujifilm PRESSMAX S-Z1

[0505] The evaluation criteria were as follows: 1) Fleshability A: It was printed for the first time within 15 pages. B: The first ink was applied when the number of printed sheets was between 16 and 30. C: The first ink was applied to 31 or more printed sheets. 2) Ink turbidity A: The color of the printing ink did not change. B: The color of the printing ink has changed slightly. C: The color of the printing ink has clearly changed.

[0506] [Table 2]

[0507] (Example 4, Comparative Examples 4 and 5) The on-press development type lithographic printing plate precursor prepared above was developed using plate surface treatment agent a (Example 1), a plate cleaner (PRESSMAX MC-E2 manufactured by FUJIFILM Corporation), and dampening water (Comparative Example 3, PRESSMAX S-Z1 manufactured by FUJIFILM Corporation diluted twice (by mass) with distilled water). Then, using printing ink (Fusion-G Beni manufactured by DIC Corporation) and a printing press (Oliver, manufactured by Sakurai Graphic Systems Co., Ltd.), the rollers were reciprocated twice to produce the resulting plates, which were used as Example 4, Comparative Example 4, and Comparative Example 5, respectively. After development, each lithographic printing plate was reciprocated twice by a roller on a printing press, and the plate surface was visually inspected to evaluate the ink receptivity for printing. Photographs of each plate surface and the evaluation results are shown in Figure 6. The evaluation criteria were as follows: A: It was visually confirmed that the printing ink was applied to the entire surface. B: It was visually confirmed that printing ink was only partially applied. C: It was visually confirmed that the printing ink had not adhered.

[0508] In the examples, the developing method and printing method using the plate surface treatment agent had excellent ink receptivity and resulted in ink being receptive with relatively little paper waste, but in the comparative examples, when the plate surface treatment agent was not used, the ink receptivity was poor and the amount of paper waste increased. Specifically, in Example 4, which used a plate surface treatment agent for an on-press development type lithographic printing plate precursor, inking was achieved that accurately reflected the exposure gradation, and improved inking properties were confirmed, whereas in Comparative Examples 4 and 5, which did not use a plate surface treatment agent, it was demonstrated that suitable inking was not achieved. [Explanation of symbols]

[0509] 12a, 12b: Aluminum support 14: Undercoat layer 16: Image recording layer 18: Aluminum plate 20a, 0b: Anodic oxide film 22a, 22b: Micropore 24: Large diameter hole 26: Small diameter hole D: Depth of the large diameter hole ta Anode reaction time tc cathode reaction time tp Time it takes for the current to reach its peak from 0 Ia Peak current in the anode cycle Ic Peak current on the cathode cycle side 50 Main electrolyzer 51 AC power supply 52 Radial drum roller 53a,53b Main pole 54 Electrolyte supply port 55 Electrolyte 56 Auxiliary anode 60 Auxiliary anode tank W Aluminum Plate 610 Anodizing treatment equipment 612 Power supply tank 614 Electrolytic treatment tank 616 Aluminum Plate 618,626 Electrolyte 620 Power supply electrode 622,628 Laura 624 Nip Roller 630 Electrolytic electrode 632 Tank wall 634 DC power supply

Claims

1. a step of applying a plate surface treatment agent different from the printing ink to a lithographic printing plate precursor including an image-wise exposed image recording layer before applying at least one of the printing ink and the fountain solution; removing the image recording layer in non-image areas with the plate surface treatment agent; the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, The oil phase contains an extender pigment. A method for developing a lithographic printing plate precursor.

2. The method for developing a lithographic printing plate precursor according to claim 1 , wherein the method is carried out before the lithographic printing plate precursor is mounted on a printing press.

3. The method for developing a lithographic printing plate precursor according to claim 1 , wherein the method is carried out after the lithographic printing plate precursor is mounted on a printing press.

4. The method for developing a lithographic printing plate precursor according to claim 1, wherein the lithographic printing plate precursor is a non-processed plate.

5. a step of exposing the image recording layer of the lithographic printing plate precursor to light in an imagewise manner; removing the image-recording layer in non-image areas with a plate surface treatment agent different from the printing ink; the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, The oil phase contains an extender pigment. A method for manufacturing a lithographic printing plate.

6. a step of exposing the image recording layer of the lithographic printing plate precursor to light in an imagewise manner; a step of preparing a lithographic printing plate by removing the image recording layer in non-image areas using a plate surface treatment agent different from the printing ink; a step of mounting the lithographic printing plate on a printing press and performing printing using the lithographic printing plate mounted on the printing press and printing ink; Including, the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, The oil phase contains an extender pigment. Lithographic printing method.

7. a step of exposing the image recording layer of the lithographic printing plate precursor to light in an imagewise manner; a step of mounting the lithographic printing plate precursor on a printing press and applying a plate surface treatment agent different from the printing ink before applying at least one of the printing ink and the dampening water; removing the image recording layer in non-image areas with the plate surface treatment agent; Including, the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, The oil phase contains an extender pigment. Lithographic printing method.

8. a step of applying a plate surface treatment agent different from the printing ink to the plate surface of the lithographic printing plate used for printing; and performing printing using the lithographic printing plate after the application of the plate surface treatment agent, the plate surface treatment agent is an emulsion containing an aqueous phase and an oil phase, The oil phase contains an extender pigment. Lithographic printing method.

9. An emulsion comprising an aqueous phase and an oil phase, The oil phase comprises a medium, The medium contains an extender pigment, The proportion of the aqueous phase is 50% by mass or more based on the total mass. Plate surface treatment agent.

10. the oil phase comprises a solvent and an emulsifier; The plate surface treatment agent according to claim 9 , wherein the aqueous phase comprises a water-soluble resin and a pH adjuster.

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