On-press developing type lithographic printing plate precursor, method for producing lithographic printing plate, and lithographic printing method

Abstract

The present invention provides an on-press developing type lithographic printing plate precursor, a method for producing a lithographic printing plate using the above-mentioned lithographic printing plate precursor, or a lithographic printing method. The above-mentioned on-press developing type lithographic printing plate precursor has a support, an image recording layer and an outermost layer in sequence. The above-mentioned image recording layer contains a polymerization initiator, a polymerizable compound and an infrared absorber. The decomposition rate of the above-mentioned infrared absorber after being stored in an environment with an ozone concentration of 150 ppb for 8 hours is less than 50%.

Description

Technical Field

[0001] The present invention relates to an on-press developing type planographic printing plate precursor, a method for producing a planographic printing plate and a planographic printing method. Background Art

[0002] Typically, a lithographic printing plate consists of an oleophilic image area that accepts ink during the printing process, and a hydrophilic non-image area that accepts fountain solution. Lithographic printing is a method that exploits the mutual repulsion between water and oil-based inks. This creates a difference in ink adhesion on the plate's surface, allowing the ink to adhere only to the image area. The ink is then transferred to a printed substrate, such as paper, to achieve printing.

[0003] To produce such lithographic printing plates, a lithographic printing plate precursor (also known as a PS plate) having an oleophilic photosensitive resin layer (also known as an image-recording layer) provided on a hydrophilic support has been widely used. Typically, a lithographic printing plate is obtained by exposing the lithographic printing plate precursor to an original image, such as a high-contrast film, leaving the image-recording layer as the image area. The remaining unnecessary image-recording layer is then removed by dissolving with an alkaline developer or organic solvent, exposing the hydrophilic support surface to form a non-image area.

[0004] Furthermore, as concern for the global environment increases, environmental problems associated with waste liquids associated with wet processes such as development processes have become apparent.

[0005] To address these environmental issues, the goal is to simplify or eliminate the development and platemaking processes. One of the simplest methods for producing lithographic printing plates is "on-press development." Specifically, on-press development involves exposing the lithographic printing plate precursor and then directly loading it onto a printing press without undergoing conventional development. This involves removing unnecessary portions of the image-recording layer during the initial stages of the normal printing process.

[0006] In the present invention, a lithographic printing plate precursor that can be used for such on-press development is referred to as an "on-press development type lithographic printing plate precursor."

[0007] Examples of conventional lithographic printing plate precursors include those described in Japanese Patent Application Laid-Open No. 2012-066577.

[0008] Japanese Patent Application Laid-Open No. 2012-066577 describes an on-press development type planographic printing plate precursor comprising, in order: a support; an image recording layer containing a radical polymerization initiator, a radical polymerizable compound, and a binder polymer having an alkylene oxide group; and an overcoat layer containing cellulose. Summary of the Invention

[0009] Technical issues to be solved by the invention

[0010] An object of one embodiment of the present invention is to provide an on-press developable lithographic printing plate precursor capable of suppressing discoloration caused by ozone exposure.

[0011] Another embodiment of the present invention aims to provide a method for producing a lithographic printing plate or a lithographic printing method using the above-mentioned on-press development type lithographic printing plate precursor.

[0012] Means for solving technical problems

[0013] Means for solving the above-mentioned problems include the following.

[0014] <1> An on-press developing type planographic printing plate precursor comprises, in order, a support, an image recording layer and an outermost layer,

[0015] The image recording layer contains a polymerization initiator, a polymerizable compound, and an infrared absorber.

[0016] The decomposition rate of the infrared absorber after storage for 8 hours in an environment with an ozone concentration of 150 ppb was 50% or less.

[0017] <2> according to <1> The on-press developed lithographic printing plate precursor, wherein

[0018] The thickness of the outermost layer is 0.005 μm to 2 μm.

[0019] <3> according to <1> or <2> The on-press developed lithographic printing plate precursor, wherein

[0020] The outermost layer is oxygen-permeable.

[0021] <4> according to <1> to <3> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0022] The outermost layer contains polysaccharides.

[0023] <5> according to <1> to <4> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0024] The outermost layer contains a cellulose derivative having a methoxyl substitution degree of 1 to 2.

[0025] <6> according to <1> to <5> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0026] The outermost layer further comprises a hydrophobic polymer.

[0027] <7> according to <1> to <6> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0028] The outermost layer further contains polymer particles.

[0029] <8> according to <1> to <7> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0030] The outermost layer contains a decomposable infrared absorber.

[0031] <9> according to <1> to <8> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0032] The polymerization initiator includes an electron-donating polymerization initiator and an electron-accepting polymerization initiator.

[0033] <10> according to <9> The on-press developed lithographic printing plate precursor, wherein

[0034] The value of HOMO of the infrared absorber minus HOMO of the electron-donating polymerization initiator is 0.70 eV or less.

[0035] <11> according to <9> or <10> The on-press developed lithographic printing plate precursor, wherein

[0036] The value of LUMO of the electron-accepting polymerization initiator minus LUMO of the infrared absorber is 0.80 eV or less.

[0037] <12> according to <1> to <11> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0038] The polymerizable compound includes a hexafunctional or higher-functional polymerizable compound.

[0039] <13> according to <1> to <12> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0040] The polymerizable compound includes a polymerizable compound having ten or more functional groups.

[0041] <14> according to <1> to <13> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0042] The image recording layer further contains polymer particles.

[0043] <15> according to <14> The on-press developed lithographic printing plate precursor, wherein

[0044] The polymer particles are addition polymerization type polymer particles having hydrophilic groups.

[0045] The hydrophilic group includes a group represented by the following formula Z.

[0046] Formula Z: *-QWY

[0047] In formula Z, Q represents a divalent linking group, W represents a divalent group having a hydrophilic structure or a divalent group having a hydrophobic structure, Y represents a monovalent group having a hydrophilic structure or a monovalent group having a hydrophobic structure, any of W and Y has a hydrophilic structure, and * represents a bonding site with another structure.

[0048] <16> according to <1> to <15> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0049] The image recording layer further contains a developer.

[0050] <17> according to <1> to <16> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0051] The color developer is a compound represented by any of the following formulas (Le-1) to (Le-3).

[0052] [Chemical Formula 1]

[0053]

[0054] In formula (Le-1) to formula (Le-3), ERG each independently represents an electron-donating group, X1 to X4 each independently represents a hydrogen atom, a halogen atom or a dialkylaniline group, and X5 to X 10 Each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 does not exist, when Y2 is N, X4 does not exist, Ra1 represents a hydrogen atom, an alkyl group or an alkoxy group, and Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group or an aryl group.

[0055] <18> according to <16> or <17> The on-press developed lithographic printing plate precursor, wherein

[0056] The above-mentioned developer is a compound represented by the following formula (Le-8),

[0057] [Chemical Formula 2]

[0058]

[0059] In formula (Le-8), X1 to X4 each independently represent a hydrogen atom, a halogen atom or a dialkylaniline group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 does not exist, when Y2 is N, X4 does not exist, Rb1 and Rb2 each independently represent an alkyl group, an aryl group or a heteroaryl group, and Rc1 and Rc2 each independently represent an aryl group or a heteroaryl group.

[0060] <19> according to <18> The on-press developed lithographic printing plate precursor, wherein

[0061] The Rc1 and Rc2 are each independently a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position.

[0062] <20> according to <16> or <17> The on-press developed lithographic printing plate precursor, wherein

[0063] The developer contains a compound represented by the following formula (Le-10).

[0064] [Chemical Formula 3]

[0065]

[0066] In formula (Le-10), Ar1 each independently represents an aryl group or a heteroaryl group, and Ar2 each 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.

[0067] <21> according to <20> The on-press developed lithographic printing plate precursor, wherein

[0068] The Ar1 groups are each independently an aryl group having an electron-donating group or a heteroaryl group having an electron-donating group, and the Ar2 groups are each independently a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position.

[0069] <22> according to <1> to <21> The on-press developing type lithographic printing plate precursor according to any one of the preceding claims, wherein

[0070] The support body comprises an aluminum plate and an aluminum anodic oxide film disposed on the aluminum plate.

[0071] The anodic oxide film is located closer to the image recording layer than the aluminum plate.

[0072] The anodic oxide film has micropores extending in the depth direction from the surface on the image recording layer side.

[0073] The average diameter of the micropores on the surface of the anodic oxide film is greater than 10 nm and less than 100 nm.

[0074] The L of the surface of the anodic oxide film on the image recording layer side is * a * b * Lightness L in the color system * The value is 70~100.

[0075] <23> according to <22> The on-press developed lithographic printing plate precursor, wherein

[0076] The micropores are composed of a large-diameter pore portion and a small-diameter pore portion, wherein the large-diameter pore portion extends from the surface of the anodic oxide film to a depth of 10 nm to 1,000 nm, and the small-diameter pore portion is connected to the bottom of the large-diameter pore portion and extends from the connection position to a depth of 20 nm to 2,000 nm.

[0077] The average diameter of the large-diameter pores on the surface of the anodic oxide film is 15 nm to 100 nm.

[0078] The average diameter of the small-diameter pores at the communication positions is 13 nm or less.

[0079] <24> A method for producing a lithographic printing plate, comprising:

[0080] Will <1> to <23> A step of exposing the on-press developed lithographic printing plate precursor as described in any one of the preceding claims to an image shape; and

[0081] A step of supplying at least one selected from printing ink and fountain solution on a printing press to remove the image recording layer in non-image areas.

[0082] <25> A lithographic printing method comprising: <1> to <23> A step of exposing the on-press developed lithographic printing plate precursor as described in any one of the preceding claims to an image shape;

[0083] A step of supplying at least one selected from printing ink and fountain solution to remove the image recording layer in the non-image portion on a printing press to produce a lithographic printing plate; and

[0084] The process of printing using the obtained planographic printing plate.

[0085] Effects of the Invention

[0086] According to one embodiment of the present invention, it is possible to provide an on-press development type planographic printing plate precursor capable of suppressing discoloration caused by ozone exposure.

[0087] Furthermore, according to another embodiment of the present invention, there can be provided a method for producing a lithographic printing plate or a lithographic printing method using the above-mentioned on-press development type lithographic printing plate precursor. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 This is a schematic cross-sectional view of one embodiment of a support body.

[0089] Figure 2 is a schematic cross-sectional view of another embodiment of a support body. DETAILED DESCRIPTION

[0090] The following describes the present invention in detail. The following description of the components is based on representative embodiments of the present invention, but the present invention is not limited to these embodiments.

[0091] In addition, in this specification, "to" which shows a numerical range is used to mean that the numerical values ​​described before and after it are included as a lower limit and an upper limit.

[0092] In the numerical ranges described in stages throughout the present invention, the upper limit or lower limit described in one numerical range may be replaced by the upper limit or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in the present invention, the upper limit or lower limit of the numerical range may be replaced by the value shown in the Examples.

[0093] Furthermore, in the notation of groups (atomic groups) in the present invention, the notation "unsubstituted" and "unsubstituted" include not only groups without substituents but also groups with substituents. For example, "alkyl" includes not only alkyl groups without substituents (unsubstituted alkyl groups) but also alkyl groups with substituents (substituted alkyl groups).

[0094] In the present invention, “(meth)acrylic acid” is a term used to include both acrylic acid and methacrylic acid, and “(meth)acryloyl” is a term used to include both acryloyl and methacryloyl.

[0095] Furthermore, the term "process" in the present invention includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0096] Furthermore, in the present invention, "mass %" has the same definition as "weight %", and "parts by mass" has the same definition as "parts by weight".

[0097] Furthermore, in the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.

[0098] Unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) in the present invention are molecular weights calculated using polystyrene as a standard substance, using a gel permeation chromatography (GPC) analyzer using TSKgel GMHxL, TSKgel G4000HxL, or TSKgel G2000HxL (all trade names manufactured by TOSOH CORPORATION) columns, and using a differential refractometer with a solvent of THF (tetrahydrofuran).

[0099] In the present invention, the term "lithographic printing plate precursor" includes not only lithographic printing plate precursors but also discarded plate precursors. Furthermore, the term "lithographic printing plate" includes not only lithographic printing plates produced by exposure, development, and other operations as needed from lithographic printing plate precursors, but also discarded plates. Discarded plates do not necessarily require exposure and development. Furthermore, discarded plates refer to lithographic printing plate precursors used to mount on unused plate cylinders, for example, when printing a portion of a page in single or two-color format in color newspaper printing.

[0100] In the present invention, “excellent printing durability” means that the lithographic printing plate can print a large number of sheets. Hereinafter, the printing durability when UV ink is used as the ink for printing is also referred to as “UV printing durability”.

[0101] On-press developed lithographic printing plate original

[0102] The on-press development type lithographic printing plate precursor involved in the present invention (hereinafter also referred to as "lithographic printing plate precursor") has a support body, an image recording layer and an outermost layer in sequence, and the image recording layer contains a polymerization initiator, a polymerizable compound and an infrared absorber. The decomposition rate of the above-mentioned infrared absorber after being stored in an environment with an ozone concentration of 150 ppb for 8 hours is less than 50%.

[0103] In a lithographic printing plate precursor having an image recording layer containing a polymerization initiator, a polymerizable compound, and an infrared absorber as described in Japanese Patent Application Laid-Open No. 2012-066577, atmospheric ozone decomposes the infrared absorber in the image recording layer, causing discoloration of the lithographic printing plate precursor.

[0104] In contrast, the decomposition rate of the infrared absorber in the image-recording layer of the lithographic printing plate precursor according to the present invention after storage for 8 hours in an environment with an ozone concentration of 150 ppb was 50% or less. In other words, even after storage for 8 hours in an environment with an ozone concentration as high as 150 ppb, the infrared absorber in the image-recording layer of the lithographic printing plate precursor according to the present invention did not decompose by 50% or more, and remained.

[0105] By having such characteristics, the lithographic printing plate precursor according to the present invention can suppress discoloration caused by ozone exposure.

[0106] Furthermore, the smaller the decomposition rate of the infrared absorber, the more discoloration caused by ozone exposure can be suppressed.

[0107] <Decomposition Rate of Infrared Absorber in Lithographic Printing Plate Precursor by Ozone Exposure>

[0108] The decomposition rate of the infrared absorber in the image recording layer of the lithographic printing plate precursor according to the present invention after being stored in an environment with an ozone concentration of 150 ppb for 8 hours is 50% or less.

[0109] That is, in the lithographic printing plate precursor according to the present invention, the amount of the decomposed infrared absorber in the image recording layer after storage for 8 hours in an environment with an ozone concentration of 150 ppb is 50% or less of the amount of the infrared absorber before storage.

[0110] In other words, in the lithographic printing plate precursor of the present invention, the amount of infrared absorber remaining in the image recording layer after storage for 8 hours in an environment with an ozone concentration of 150 ppb is 50% or more of the amount of infrared absorber in the image recording layer before storage.

[0111] The amount of the infrared absorber is determined by analyzing an extract extracted from the lithographic printing plate precursor using a solvent using high performance liquid chromatography (HPLC) to quantify the amount of the infrared absorber.

[0112] The smaller the decomposition rate of the infrared absorber, the more discoloration caused by ozone exposure can be suppressed in the lithographic printing plate precursor.

[0113] The decomposition rate of the infrared absorber is preferably 45% or less, more preferably 40% or less, further preferably 35% or less, and particularly preferably 30% or less.

[0114] The lower limit of the decomposition rate of the infrared absorbent may be 0%, but may be, for example, 1% or more, or 5% or more.

[0115] The decomposition rate of the infrared absorber is measured by the following method.

[0116] The lithographic printing plate precursor was cut into a size of 3 cm square when viewed from the outermost layer side, to obtain two samples of the same shape.

[0117] One of the two samples was extracted with 5 mL of acetonitrile in an ultrasonic bath for 30 minutes, and the resulting extract was passed through a 0.20 mm filter and subjected to HPLC analysis. The peak surface area of ​​the infrared absorber was determined by HPLC analysis and used as the amount of infrared absorber before ozone exposure (X).

[0118] Place the remaining one of the two samples into a 100 mL vial and place it on the bench.

[0119] The foot tube of the Kiriyama funnel flask (manufactured by Kiriyama Glass Works Co.) is inserted into and fixed to the medicine bottle containing the sample. On the other hand, a stirring blade is placed on the upper opening of the Kiriyama funnel flask (manufactured by Kiriyama Glass Works Co.) as a spacer. In addition, an ozone generator (manufactured by ASSOCIA OZONE, a refreshing positive ion CS-4 commercial ozone generator) is fixed above the stirring blade (here, the stirring blade is separated from the ozone generator by about 150 mm). In this device, the ozone generated by the ozone generator is swung by the stirring blade to become an air flow containing ozone, and reaches the sample in the medicine bottle through the Kiriyama funnel flask.

[0120] The sample was exposed to ozone using this device. During the ozone exposure period, the ozone concentration in the vial was measured and adjusted to 150 ppm. The ozone exposure was performed at 25°C and 50% RH.

[0121] The ozone exposure of the sample was continued for 8 hours. After the ozone exposure for 8 hours, the sample was subjected to HPLC analysis by the same method as above to determine the peak surface area of ​​the infrared absorber, which was used as the amount of the infrared absorber after ozone exposure (Y).

[0122] The amount (X) of the infrared absorber before ozone exposure and the amount (Y) of the infrared absorber after ozone exposure obtained in the above manner are substituted into the following formula 1 to determine the decomposition rate (Z) of the infrared absorber.

[0123] Formula 1: (Z)=100-[(Y) / (X)×100]

[0124] The various conditions for HPLC analysis were as follows.

[0125] ·Device: Alliance 2695, Waters Corporation

[0126] ·Column: Mightysil RP-18GP 250mm×φ4.6mm (5μm), KANTO CHEMICAL CO., INC.

[0127] Column temperature: 40°C

[0128] Eluent: MeOH (containing 0.1 mass% acetic acid + 0.1 mass% triethylamine), H2O (containing 0.1 mass% acetic acid + 0.1 mass% triethylamine)

[0129] ·gradient: =30 / 70(0min)-100 / 0(28min)-100 / 0(40min)-30 / 70(40.1min) equalization

[0130] Flow rate: 1.0 mL / min

[0131] Injection volume: 10mL

[0132] UV detector: PDA 2998, Waters Corporation

[0133] Next, the details of the constituent elements of the lithographic printing plate precursor according to the present invention will be described.

[0134] <Outermost layer>

[0135] The lithographic printing plate precursor according to the present invention has an outermost layer on the side of the image recording layer opposite to the support side.

[0136] From the viewpoint of achieving the above-mentioned decomposition rate of the infrared absorber by exposure to ozone, the outermost layer in the present invention is preferably an ozone barrier layer.

[0137] The ozone barrier layer is not particularly limited as long as it has an ozone barrier capability that enables the above-mentioned decomposition rate of the infrared absorber by exposure to ozone.

[0138] 〔Water-soluble polymer〕

[0139] From the viewpoint of development removability (more preferably on-press developability), the outermost layer in the present invention preferably contains a water-soluble polymer.

[0140] In the present invention, a water-soluble polymer refers to a polymer that dissolves 5 g or more in 100 g of pure water at 125°C and does not precipitate even when a solution obtained by dissolving 5 g of the polymer in 100 g of pure water at 125°C is cooled to 25°C.

[0141] Examples of the water-soluble polymer used in the outermost layer include polyvinyl alcohol, modified polyvinyl alcohol, poly(meth)acrylamide, polyethylene glycol, poly(meth)acrylonitrile, polyvinyl pyrrolidone, copolymers formed by combining raw material monomers of these polymers, and copolymers formed by combining raw material monomers of these polymers with other monomers.

[0142] There are no particular limitations on other monomers as long as they are copolymerizable with the above-mentioned raw material monomers. Examples thereof include vinyl acetate, alkyl (meth)acrylates such as methyl (meth)acrylate and butyl (meth)acrylate, and addition polymerization-type monomers having acid groups such as carboxyl groups, sulfonic groups, and salts thereof.

[0143] Furthermore, as the modified polyvinyl alcohol, acid-modified polyvinyl alcohol having a carboxyl group or a sulfonic group can be preferably used. Specific examples of the modified polyvinyl alcohol include those described in JP-A-2005-250216 and JP-A-2006-259137.

[0144] Furthermore, polysaccharides can also be used as the water-soluble polymer.

[0145] That is, the outermost layer in the present invention preferably contains a polysaccharide.

[0146] The polysaccharide used in the outermost layer is not particularly limited as long as it has the above-mentioned water solubility. However, from the viewpoint of forming an outermost layer having high ozone shielding capability and oxygen permeability, cellulose derivatives are preferred.

[0147] Examples of the polysaccharide used in the outermost layer include soybean polysaccharides, modified starch, gum arabic, dextrin, and pullulan.

[0148] Examples of cellulose derivatives include compounds in which the hydrogen atoms of at least some of the hydroxyl groups of cellulose are substituted with at least one group selected from an alkyl group, a hydroxyalkyl group, and a carboxyalkyl group. Examples of the alkyl group, the alkyl group in the hydroxyalkyl group, and the alkyl group in the carboxyalkyl group include a methyl group, an ethyl group, and a propyl group.

[0149] Among the above, more preferred cellulose derivatives are compounds in which at least a portion of the hydrogen atoms of the hydroxyl groups of cellulose are substituted with an alkyl group (preferably a methyl group). In other words, preferred cellulose derivatives are compounds in which at least a portion of the hydroxyl groups of cellulose are substituted with an alkoxy group (preferably a methoxy group).

[0150] Specific preferred examples of the cellulose derivative include methylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, and carboxymethylcellulose. Among them, methylcellulose and hydroxypropylmethylcellulose are preferred.

[0151] The degree of substitution of the hydroxyl groups in the cellulose derivative with the above-mentioned groups (preferably the degree of substitution with methoxy groups) is preferably 0.1 to 6.0, more preferably 1 to 4, and even more preferably 1 to 2.

[0152] That is, it is particularly preferred that the outermost layer contain a cellulose derivative having a methoxyl group substitution degree of 1 to 2.

[0153] Here, the methoxy substitution degree refers to the average number of hydroxyl groups substituted by methoxy groups per glucose ring unit of cellulose. This methoxy substitution degree can be measured by the Zeisel-GC method described in JG Gobler, EPSamscl, and GH Beaber, Talanta, 9, 474 (1962).

[0154] The water-soluble polymers may be used alone or in combination of two or more.

[0155] The content of the water-soluble polymer in the outermost layer is preferably 20 to 99 mass %, more preferably 30 to 98 mass %, and even more preferably 40 to 97 mass %, relative to the total mass of the outermost layer.

[0156] Furthermore, from the viewpoint of suppressing discoloration of the lithographic printing plate original caused by ozone exposure, the content of the polysaccharide (preferably a cellulose derivative) contained in the outermost layer is preferably 30% by mass to 98% by mass, more preferably 35% by mass to 98% by mass, and still more preferably 40% by mass to 97% by mass, relative to the total mass of the outermost layer.

[0157] 〔Hydrophobic polymer〕

[0158] The outermost layer may comprise a hydrophobic polymer.

[0159] The hydrophobic polymer refers to a polymer that dissolves less than 5 g or does not dissolve in 100 g of pure water at 125°C.

[0160] Examples of the hydrophobic polymer include polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyalkyl (meth)acrylates (e.g., polymethyl (meth)acrylate, polyethyl (meth)acrylate, polybutyl (meth)acrylate, etc.), and copolymers obtained by combining raw material monomers of these polymers (e.g., styrene acrylic resin, etc.).

[0161] The hydrophobic polymer may be used alone or in combination of two or more.

[0162] When the outermost layer contains a hydrophobic polymer, the content of the hydrophobic polymer is preferably 5 to 70 mass %, more preferably 7.5 to 50 mass %, and even more preferably 10 to 30 mass % relative to the total mass of the outermost layer.

[0163] 〔Polymer particles〕

[0164] The outermost layer may comprise polymer particles.

[0165] The polymer particles refer to polymers showing a particle shape in the outermost layer.

[0166] Even when the polymer contained in the polymer particles corresponds to the above-mentioned water-soluble polymer or hydrophobic polymer, as long as it is present in the form of particles in the outermost layer, it is also included in the "polymer particles".

[0167] Among them, the outermost layer preferably contains hydrophobic polymer particles.

[0168] The presence or absence of polymer particles in the outermost layer can be confirmed by observing the outermost layer surface using a scanning electron microscope (SEM).

[0169] The polymer particles are preferably in the form of, for example, microcapsules, microgels (ie, cross-linked polymer particles), and more preferably in the form of microgels.

[0170] Furthermore, the polymer particles preferably have a hydrophilic group at least on the surface.

[0171] Specifically, the polymer particles contained in the outermost layer are preferably microgels having hydrophilic groups on their surfaces. Examples of such microgels include the microgels used in the image recording layer described below.

[0172] The polymer particles may be used alone or in combination of two or more.

[0173] When the outermost layer contains polymer particles, the content of the polymer particles is preferably 10 to 80% by mass, more preferably 15 to 60% by mass, and even more preferably 20 to 40% by mass relative to the total mass of the outermost layer.

[0174] 〔Decomposable infrared absorber〕

[0175] From the viewpoint of improving the visibility of the exposed portion, the outermost layer may contain a decomposable infrared absorber.

[0176] The decomposable infrared absorber may be any compound that absorbs at least a portion of light in the infrared wavelength region (i.e., the wavelength region of 750 nm to 1 mm, preferably the wavelength region of 750 nm to 1,400 nm) and decomposes. Preferably, the compound has a maximum absorption wavelength in the wavelength region of 750 nm to 1,400 nm.

[0177] More specifically, the decomposable infrared absorber is preferably a compound that decomposes upon exposure to infrared rays to generate a compound having a maximum absorption wavelength in the wavelength range of 500 nm to 600 nm.

[0178] From the viewpoint of improving the visibility of the exposed portion, the decomposable infrared absorber preferably has a group that decomposes upon exposure to infrared light (specifically, R 1 ) anthocyanin pigments.

[0179] As the decomposable infrared absorber, from the viewpoint of improving the visibility of the exposed portion, a compound represented by the following formula 1-1 is more preferable.

[0180] [Chemical Formula 4]

[0181]

[0182] In formula 1-1, R 1 represents a group represented by any one of the following formulas 2 to 4, R 11 ~R 18 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-SR c or -NR d R e , R a ~R e Each independently represents a hydrocarbon group, A1, A2 and multiple R 11 ~R 18 They may be linked to form a monocyclic or polycyclic ring, 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 from 0 to 5, wherein n 11 and n 12 The total of n is 2 or more, 13 and n 14 Each independently represents 0 or 1, L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing the charge.

[0183] [Chemical Formula 5]

[0184]

[0185] In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with the group represented by L in the above formula 1-1.

[0186] If the compound represented by Formula 1-1 is exposed to infrared light, R 1 -L bond breaks, L becomes =0, =S or =NR 10 , thus changing color.

[0187] In formula 1-1, R 1 represents a group represented by any one of the above formulae 2 to 4.

[0188] Hereinafter, the group represented by Formula 2, the group represented by Formula 3, and the group represented by Formula 4 will be described respectively.

[0189] In formula 2, R 20 represents an alkyl group or an aryl group, and the wavy line portion represents a bonding site with the group represented by L in Formula 1-1.

[0190] As by R20 The alkyl group represented by is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and further preferably an alkyl group having 1 to 10 carbon atoms.

[0191] The above-mentioned alkyl group may be linear, branched, or have a ring structure.

[0192] As R 20 The aryl group represented by is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and further preferably an aryl group having 6 to 12 carbon atoms.

[0193] As R 20 From the viewpoint of improving the visibility of the exposed portion, an alkyl group is preferred.

[0194] Furthermore, from the viewpoint of improving the visibility of the exposed portion, as the 20 The alkyl group represented by is preferably a secondary alkyl group or a tertiary alkyl group, more preferably a tertiary alkyl group.

[0195] Furthermore, from the viewpoint of improving the visibility of the exposed portion, as the 20 The alkyl group represented by is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, further preferably a branched alkyl group having 3 to 6 carbon atoms, particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

[0196] Here, by R 20 The alkyl group represented by may be a substituted alkyl group substituted by a halogen atom (for example, a chloro group) or the like.

[0197] Specific examples of the group represented by the above formula 2 are given below, but the present invention is not limited thereto. In the following structural formula, ● represents a bonding site to the group represented by L in formula 1-1.

[0198] [Chemical Formula 6]

[0199]

[0200] In formula 3, R 30 represents an alkyl group or an aryl group, and the wavy line portion represents a bonding site with the group represented by L in Formula 1-1.

[0201] As R 30 The alkyl and aryl groups represented by R in formula 2 20 The alkyl group and aryl group represented are the same, and the preferred embodiments are also the same.

[0202] From the viewpoint of improving the visibility of the exposed portion, as 30 The alkyl group represented by is preferably a secondary alkyl group or a tertiary alkyl group, more preferably a tertiary alkyl group.

[0203] Furthermore, from the viewpoint of improving the visibility of the exposed portion, as the 30 The alkyl group represented by is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, further preferably a branched alkyl group having 3 to 6 carbon atoms, particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

[0204] Furthermore, from the viewpoint of improving the visibility of the exposed portion, the R 30 The alkyl group represented by is preferably a substituted alkyl group, more preferably a fluorine-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group.

[0205] From the perspective of improving the visibility of the exposed part, R 30 The aryl group represented by 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).

[0206] Specific examples of the group represented by the above formula 3 are given below, but the present invention is not limited thereto. In the following structural formula, ● represents a bonding site to the group represented by L in formula 1-1.

[0207] [Chemical Formula 7]

[0208]

[0209] In formula 4, R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line portion represents a bonding site with the group represented by L in Formula 1-1.

[0210] As R 41 or R 42 The alkyl and aryl groups represented by R in formula 2 20 The alkyl group and aryl group represented are the same, and the preferred embodiments are also the same.

[0211] As R 41 From the viewpoint of improving the visibility of the exposed portion, an alkyl group is preferred.

[0212] As R 42 From the viewpoint of improving the visibility of the exposed portion, an alkyl group is preferred.

[0213] From the viewpoint of improving the visibility of the exposed portion, as 41 The alkyl group represented by is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group.

[0214] From the viewpoint of improving the visibility of the exposed portion, as 42 The alkyl group represented by is preferably a secondary alkyl group or a tertiary alkyl group, and is preferably a tertiary alkyl group.

[0215] Furthermore, from the viewpoint of improving the visibility of the exposed portion, as the 42 The alkyl group represented by is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, further preferably a branched alkyl group having 3 to 6 carbon atoms, particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

[0216] Zb in Formula 4 may be any counter ion for neutralizing the charge, and may be included in Za in Formula 1-1 as the entire compound.

[0217] Zb is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion or a perchlorate ion, more preferably a tetrafluoroborate ion.

[0218] Specific examples of the group represented by the above formula 4 are given below, but the present invention is not limited thereto. In the following structural formula, ● represents a bonding site to the group represented by L in formula 1-1.

[0219] [Chemical Formula 8]

[0220]

[0221] In formula 1-1, L is preferably an oxygen atom or -NR 10 -, with an oxygen atom being particularly preferred.

[0222] And, -NR 10 -R in 10 Alkyl is preferred. 10 The alkyl group represented by is preferably an alkyl group having 1 to 10 carbon atoms. 10 The alkyl group represented by may be linear, branched, or have a ring structure.

[0223] In the R 10 Among the alkyl groups represented by , methyl, tert-butyl or cyclohexyl is preferred.

[0224] In-NR 10 -R in 10 In the case of an aryl group, an aryl group having 6 to 30 carbon atoms is more preferable, an aryl group having 6 to 20 carbon atoms is more preferable, and an aryl group having 6 to 12 carbon atoms is further preferable. These aryl groups may have a substituent.

[0225] In formula 1-1, R 11 ~R 18 Each independently represents a hydrogen atom, -R a 、-OR b 、-SR c or -NR d R e .

[0226] By R a ~R e The hydrocarbon group represented by is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and still more preferably a hydrocarbon group having 1 to 10 carbon atoms. a ~R e The hydrocarbon group represented by may be linear, branched, or have a ring structure.

[0227] As R a ~R e The hydrocarbon group represented by is particularly preferably an alkyl group.

[0228] 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 still more preferably an alkyl group having 1 to 10 carbon atoms.

[0229] The above-mentioned alkyl group may be linear, branched, or have a ring structure.

[0230] Specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, and 2-norbornyl.

[0231] Among these alkyl groups, a methyl group, an ethyl group, a propyl group or a butyl group is preferred.

[0232] The above-mentioned alkyl group may have a substituent.

[0233] Examples of the substituent include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group, and combinations thereof.

[0234] R in Formula 1-1 11 ~R 14 are each independently preferably a hydrogen atom or -R a (i.e., a hydrocarbon group), more preferably a hydrogen atom or an alkyl group, and further preferably a hydrogen atom except in the following cases.

[0235] Among them, R bonded to the carbon atom bonded to the carbon atom bonded to L 11 and R 13 Preferably, an alkyl group is linked to form a ring. The ring formed above may be a monocycle or a polycycle. Specifically, the ring formed includes 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.

[0236] And, in A1 + R bonded to the carbon atom to which it is bonded 12 Optimum with R 15 or R 16 (Preferably R 16 ) are linked to form a ring, and R bonded to the carbon atom to which A2 is bonded 14 Optimum with R 17 or R 18 (Preferably R 18 ) are connected to form a ring.

[0237] In formula 1-1, preferably n 13 is 1, R 16 -R a (i.e., hydrocarbon group).

[0238] And, R 16 Preferably with A1 + R bonded to the carbon atom to which it is bonded 12 The ring is preferably an indole ring, a pyrylium ring, a thiopyridinium ring, a benzoxazoline ring, or a benzimidazolinium ring. From the perspective of improving the visual recognition of the exposed portion, an indole ring is more preferred. These rings may further have a substituent.

[0239] In formula 1-1, preferably n 14 is 1, R 18 -R a (i.e., hydrocarbon group).

[0240] And, R 18 Preferably, R is bonded to the carbon atom to which A2 is bonded. 14 The ring is preferably an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring, or a benzimidazole ring. From the perspective of improving the visual recognition of the exposed portion, an indole ring is more preferred. These rings may further have a substituent.

[0241] R in Formula 1-1 16 and R 18 Preferably, they are the same groups. When they form a ring, they preferably form a ring except A1 + and rings other than A2 having the same structure.

[0242] R in Formula 1-1 15 and R 17 Preferably, they are the same group. 15 and R 17 Preferably -R a (i.e., a hydrocarbon group), more preferably an alkyl group, and even more preferably a substituted alkyl group.

[0243] In the compound represented by Formula 1-1, from the viewpoint of improving water solubility, R 15 and R 17 A substituted alkyl group is preferred.

[0244] As R 15 or R 17 Examples of the substituted alkyl group include groups represented by any one of the following formulae (a1) to (a4).

[0245] [Chemical Formula 9]

[0246]

[0247] -R W2 -CO2M (a2)

[0248] -R W3 -PO3M2 (a3)

[0249] -R W4 -SO3M (a4)

[0250] 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, R W1 represents an alkyl group having 1 to 12 carbon atoms or -C(=0)-R W5 , R W5 represents an alkyl group having 1 to 12 carbon atoms, 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.

[0251] In formula (a1), as R W0 Specific examples of the alkylene group represented by include ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, n-hexyl, isohexyl, etc., preferably ethylene, n-propylene, isopropylene or n-butylene, and particularly preferably n-propylene.

[0252] n W1 1-10 are preferred, 1-5 are more preferred, and 1-3 are particularly preferred.

[0253] As R W1 Specific examples of the alkyl group represented by include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-octyl, n-dodecyl, etc., preferably methyl, ethyl, n-propyl, isopropyl or n-butyl, tert-butyl, more preferably methyl or ethyl, and particularly preferably methyl.

[0254] By R W5 The alkyl group represented by R W1 The alkyl group represented by R is the same as that represented by W1 The preferred embodiment of the alkyl group represented is the same.

[0255] Specific examples of the group represented by formula (a1) are shown below, but the present invention is not limited thereto. In the following structural formula, Me represents a methyl group, Et represents an ethyl group, and * represents a bonding site.

[0256] [Chemical Formula 10]

[0257]

[0258] In formulas (a2) to (a4), as R W2 ~R W4 Specific examples of the alkylene group represented by include methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, n-hexyl, isohexyl, n-octylene, and n-dodecylene, among which ethylene, n-propylene, isopropylene, or n-butylene is preferred, and ethylene or n-propylene is particularly preferred.

[0259] In formula (a3), two M's may be the same or different.

[0260] In 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.

[0261] CO2M in formula (a2), PO3M2 in formula (a2), and SO3M in formula (a4) may all have an anionic structure in which M is dissociated. The counter cation of the anionic structure may be A1 + , or R in formula 1-1 1 -L can contain a cation.

[0262] Among the groups represented by formula (a1) to formula (a4), the group represented by formula (a1), formula (a2) or formula (a4) is preferred.

[0263] n in formula 1-1 11 and n 12 They are preferably the same, and are preferably integers of 1 to 5, more preferably integers of 1 to 3, further preferably 1 or 2, and particularly preferably 2.

[0264] A1 and A2 in Formula 1-1 each independently represent an oxygen atom, a sulfur atom or a nitrogen atom, preferably a nitrogen atom.

[0265] A1 and A2 in Formula 1-1 are preferably the same atom.

[0266] Za in Formula 1-1 represents a counter ion for neutralizing the charge.

[0267] If R 11 ~R 18 and R 1 If all -L groups are neutral, Za becomes a monovalent counter anion. 11 ~R 18 and R 1 -L can have an anionic structure or a cationic structure, for example, in R 11 ~R 18 and R 1 When -L has two or more anionic structures, Za can also serve as a counter cation.

[0268] In addition, if the cyanine dye represented by Formula 1-1 has an electrically neutral structure in the entire compound except Za, Za is not required.

[0269] When Za is a counter anion, examples thereof include sulfonate ion, carboxylate ion, tetrafluoroborate ion, hexafluorophosphate ion, p-toluenesulfonate ion, and perchlorate ion, and tetrafluoroborate ion is preferred.

[0270] When Za is a counter cation, examples include alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, and sulfonium ions, preferably sodium ions, potassium ions, ammonium ions, pyridinium ions, and sulfonium ions, and more preferably sodium ions, potassium ions, and ammonium ions.

[0271] As the decomposable infrared absorber, from the viewpoint of improving the visibility of the exposed portion, a compound represented by the following formula 1-2 (ie, a cyanine dye) is more preferable.

[0272] [Chemical Formula 11]

[0273]

[0274] In formula 1-2, R 1 represents a group represented by any one of the above formulae 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d R e , R 23 ~R 24 Each independently represents a hydrogen atom or -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 or R 23 With R 24 They can be linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 and W 1 ~W 2 Each independently represents an alkyl group which may have a substituent, and Za represents a counter ion for neutralizing the charge.

[0275] R in Formula 1-2 1 and R in formula 1-1 1 The meaning is the same and the preferred method is also the same.

[0276] In formula 1-2, R 19 ~R 22 Each of the above is preferably independently a hydrogen atom, a halogen atom, -R a 、-OR b or -CN.

[0277] More specifically, R 19 and R 21 Preferably, a hydrogen atom or -R a .

[0278] And, R 20 and R 22 Preferably, a hydrogen atom, -R a 、-OR b or -CN.

[0279] As R 19 ~R 22 -R a , preferably an alkyl or alkenyl group.

[0280] In R 19 ~R 22 All -R a In the case of R 19 With R 20 and R 21 With R 22 linked to form a single ring or multiple rings.

[0281] As R 19 With R 20 or R 21 With R 22 Examples of the ring formed by linking include a benzene ring, a cyclohexane ring, and a cyclopentane ring.

[0282] In Formula 1-2, preferably R 23 With R 24 linked to form a single ring or multiple rings.

[0283] As R 23 With R 24 The ring formed by linking may be a monocyclic ring or a polycyclic ring. Specific examples of the formed ring include monocyclic rings such as cyclopentene ring, cyclopentadiene ring, cyclohexene ring, and cyclohexadiene ring, and polycyclic rings such as indene ring and indole ring.

[0284] In formula 1-2, R d1 ~R d4 Preferably, it is an unsubstituted alkyl group. d1 ~R d4 are all the same groups.

[0285] Examples of the unsubstituted alkyl group include a methyl group and an ethyl group, and among these, a methyl group is preferred.

[0286] In Formula 1-2, from the viewpoint of improving the water solubility of the compound represented by Formula 1-2, W 1 ~W 2 A substituted alkyl group is preferred.

[0287] As W 1 ~W 2 The substituted alkyl group represented by may be a group represented by any one of formula (a1) to formula (a4) in formula 1-1, and preferred embodiments are also the same.

[0288] Za represents a counter ion that neutralizes the charge within the molecule.

[0289] If R 19 ~R 22 、R 23 ~R 24 、R d4 ~R d4 、W 1 ~W 2 and R 1 If all -L groups are neutral, Za becomes a monovalent counter anion. 19 ~R 22 、R 23 ~R 24 、R d1 ~R d4 、W 1 ~W 2 and R 1 -L can have an anionic structure or a cationic structure, for example, in 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 serve as a counter cation.

[0290] In addition, if the compound represented by Formula 1-2 has an electrically neutral structure in the entire compound except Za, Za is not required.

[0291] Examples when Za is a counter anion are the same as those for Za in Formula 1-1, and preferred embodiments are also the same. Furthermore, examples when Za is a counter cation are the same as those for Za in Formula 1-1, and preferred embodiments are also the same.

[0292] From the viewpoint of improving the visibility of the exposed portion, 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.

[0293] In particular, from the viewpoint of improving the visibility of the exposed portion, a compound represented by any one of Formula 1-3, Formula 1-5, and Formula 1-6 is preferred.

[0294] [Chemical Formula 12]

[0295]

[0296] In formulas 1-3 to 1-7, R 1 represents a group represented by any one of the above formulae 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d R e , R 25 ~R 26 Each independently represents a hydrogen atom, a halogen atom or -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 or R 25 With R 26 They can be linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 and W 1 ~W 2 Each independently represents an alkyl group which may have a substituent, and Za represents a counter ion for neutralizing the charge.

[0297] R in Formulas 1-3 to 1-7 1 、R 19 ~R 22 、R d1 ~R d4 、W 1 ~W 2 And L and R in formula 1-2 1 、R 19 ~R 22 、R d1 ~R d4 、W 1 ~W 2 and L have the same meanings and the preferred embodiments are also the same.

[0298] R in Formula 1-7 25 ~R 26 Each independently preferably represents a hydrogen atom or a methyl group.

[0299] Specific examples of cyanine dyes as decomposable infrared absorbers are given below, but the present invention is not limited to these.

[0300] [Chemical Formula 13]

[0301]

[0302] Furthermore, as the decomposable infrared absorber, the infrared absorbing compounds described in International Publication No. 2019 / 219560 can be preferably used.

[0303] The decomposable infrared absorbers may be used alone or in combination of two or more.

[0304] When the outermost layer contains a decomposable infrared absorber, the content of the decomposable infrared absorber is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and further preferably 10 to 30% by mass relative to the total mass of the outermost layer.

[0305] [Other ingredients]

[0306] The outermost layer in the present invention may contain known additives such as an inorganic layered compound and a surfactant in addition to the components described above.

[0307] [Method for forming the outermost layer]

[0308] The method for forming the outermost layer is not particularly limited, but the following method is preferably used from the viewpoint of improving ozone barrier properties.

[0309] Specifically, a coating liquid having a solid content concentration of 5% to 30% by mass is applied to an image recording layer formed on a support, and the resulting coating is dried at 70°C to 200°C for 5 to 30 seconds to form an outermost layer.

[0310] By using this method, it is easy to form an outermost layer in which the decomposition rate of the infrared absorber due to ozone exposure is 50% or less.

[0311] In forming the outermost layer, the solid content concentration of the coating liquid is preferably 7.5% by mass to 25% by mass, and more preferably 10% by mass to 20% by mass.

[0312] Furthermore, in forming the outermost layer, the coating is dried under conditions preferably at 80°C to 170°C for 7.5 seconds to 25 seconds, and more preferably at 90°C to 150°C for 10 seconds to 20 seconds.

[0313] The coating amount (solid content) of the outermost layer is preferably 0.01 g / m 2 ~10g / m 2 , more preferably 0.02g / m 2 ~3g / m 2 , especially preferably 0.1g / m 2 ~2g / m 2 .

[0314] The thickness of the outermost layer is preferably 0.005 μm to 2 μm, more preferably 0.05 μm to 5 μm, and even more preferably 0.1 μm to 3 μm.

[0315] In the present invention, the film thickness of each layer in the planographic printing plate precursor is set to the following film thickness, that is, a slice cut in a direction perpendicular to the surface of the planographic printing plate precursor is prepared, and the average film thickness when the cross section of the above slice is observed within a range of 50 μm in a direction horizontal to the surface of the planographic printing plate using a scanning electron microscope (SEM).

[0316] 〔Oxygen permeability〕

[0317] The outermost layer may be oxygen permeable.

[0318] Here, “the outermost layer has oxygen permeability” means that the dot area ratio calculated by the method described below exceeds 0.9.

[0319] If the outermost layer is oxygen-permeable, that is, if the dot area ratio exceeds 0.9, it is possible to suppress the occurrence of streaky unevenness (also known as swathe ununiformity) in printed materials, which is observed when the dot image thickens in the exposure scanning direction. This streaky unevenness is easily affected by the type of platemaking machine. Therefore, by making the outermost layer oxygen-permeable, it can also be used in platemaking machines that are prone to streaky unevenness, thereby expanding the selection of platemaking machines.

[0320] From the viewpoint of suppressing streak-like unevenness, the dot area ratio is preferably 0.92 or more, more preferably 0.94 or more, further preferably 0.96 or more, and particularly preferably 0.98 or more.

[0321] The upper limit of the dot area ratio is 1.00, for example.

[0322] Hereinafter, a method for obtaining the dot area ratio and the dot area ratio ratio will be described.

[0323] First, two lithographic printing plate precursors differing only in the presence or absence of the outermost layer (ie, a lithographic printing plate precursor with an outermost layer and a lithographic printing plate precursor without an outermost layer) are prepared.

[0324] Using two planographic printing plate precursors, the dot area ratio was determined by the following method, and the dot area ratio ratio, which is an indicator of oxygen permeability, was calculated based on the determined dot area ratio.

[0325] Two prepared lithographic printing plate precursors were exposed using a Luxel PLATESETTER T-9800II manufactured by Fujifilm Corporation, equipped with an infrared semiconductor laser, at an external drum speed of 220 rpm (revolutions per minute), laser outputs of 99.7, 99.6, and 99.5%, a resolution of 2,400 dpi (dots per inch, 1 inch = 2.54 cm), and extinction ratios of 1:14, 1:17, and 1:19. The exposed images included a solid image and a 50% dot pattern of FM screening with 20 μm dots.

[0326] The exposed lithographic printing plate precursor thus obtained was mounted on the plate cylinder of a Lithrone 26 printing press manufactured by Komori Corporation without undergoing development. After decelerating the water supply roller relative to the plate cylinder by 5%, a fountain solution of Ecolity-2 (manufactured by Fujifilm Corporation) / tap water = 2 / 98 (volume ratio) and Space Color Fusion G black ink (manufactured by DIC Corporation) were supplied with the fountain solution and ink using the standard automatic print start method of the Lithrone 26. After on-press development, 1,000 sheets were printed on Tokubishi Art (manufactured by Mitsubishi Paper Mills Limited, continuous weight 76.5 kg) paper at a printing speed of 10,000 sheets per hour.

[0327] For the 1,000th print, let the density of the solid image area (i.e., solid density) be DS, and the density of the halftone dot area be DT. The dot area ratio is derived using the following equation: M: Murray-Davies equation. Next, substitute the obtained dot area ratio value into the following equation: OT to calculate the dot area ratio ratio.

[0328] Formula M: Dot area ratio = (1-10 -DT ) / (1-10 -DS )×100

[0329] Formula OT: Dot area ratio = (dot area ratio of the lithographic printing plate without the outermost layer) / (dot area ratio of the lithographic printing plate with the outermost layer)

[0330] A larger value of the dot area ratio indicates better oxygen permeability.

[0331] <Image Recording Layer>

[0332] The lithographic printing plate precursor according to the present invention has an image recording layer between the outermost layer described above and the support.

[0333] The image recording layer in the present invention contains a polymerization initiator, a polymerizable compound, and an infrared absorber.

[0334] The image recording layer in the present invention is a negative image recording layer, preferably a water-soluble or water-dispersible negative image recording layer.

[0335] Regarding the image recording layer in the present invention, from the viewpoint of on-press developability, it is preferred that the unexposed portion of the image recording layer be removable by at least one of a fountain solution and a printing ink.

[0336] Hereinafter, the details of each component contained in the image recording layer will be described.

[0337] 〔Polymerization initiator〕

[0338] The image-recording layer in the present invention contains a polymerization initiator.

[0339] The polymerization initiator preferably contains an electron-accepting polymerization initiator, and more preferably contains an electron-accepting polymerization initiator and an electron-donating polymerization initiator.

[0340] [Electron-accepting polymerization initiator]

[0341] The image recording layer preferably contains an electron-accepting polymerization initiator as a polymerization initiator.

[0342] The electron-accepting polymerization initiator is a compound that, when electrons of an infrared absorber are excited by infrared ray exposure, accepts an electron through intermolecular electron transfer to generate a polymerization initiating species such as a radical.

[0343] The electron-accepting polymerization initiator is a compound that generates polymerization initiating species such as radicals or cations by energy from light, heat, or both. Known thermal polymerization initiators, compounds having bonds with low bond dissociation energy, photopolymerization initiators, and the like can be appropriately selected and used.

[0344] As the electron-accepting polymerization initiator, a radical polymerization initiator is preferred, and an onium salt compound is more preferred.

[0345] Furthermore, as the electron-accepting polymerization initiator, an infrared-sensitive polymerization initiator is preferable.

[0346] Among the above-mentioned electron-accepting polymerization initiators, preferred examples include oxime ester compounds and onium salt compounds from the perspective of curability of the image recording layer. Among them, from the perspective of printing durability, iodonium salt compounds, sulfonium salt compounds, or azinium salt compounds are preferred, iodonium salt compounds or sulfonium salt compounds are more preferred, and iodonium salt compounds are particularly preferred.

[0347] Specific examples of these compounds are shown below, but the present invention is not limited thereto.

[0348] Examples of the iodonium salt compound include preferably diaryliodonium salt compounds, and more preferably diphenyliodonium salt compounds substituted with an electron-donating group such as an alkyl group or an alkoxy group. Furthermore, asymmetric diphenyliodonium salt compounds are preferred. 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-tert-butylphenyl)iodonium tetraphenylborate.

[0349] Examples of counter anions for iodonium salt compounds and sulfonium salt compounds include sulfonate anions, carboxylate anions, tetrafluoroborate anions, hexafluorophosphate anions, p-toluenesulfonate anions, p-toluenesulfonate anions, sulfonamide anions, and sulfonimide anions. Among these, sulfonamide anions and sulfonimide anions are preferred, and sulfonimide anions are more preferred.

[0350] As the sulfonamide anion, an arylsulfonamide anion is preferred.

[0351] Furthermore, as the sulfonyl imide anion, a bisarylsulfonyl imide anion is preferred.

[0352] Specific examples of the sulfonamide anion or the sulfonimide anion include the compounds described in paragraph 0034 of International Publication No. 2019 / 013268.

[0353] Furthermore, from the viewpoint of developability and UV printing durability of the obtained lithographic printing plate, the electron-accepting polymerization initiator is preferably a compound represented by either of the following formulas (II) and (III), and particularly preferably a compound represented by formula (I).

[0354] [Chemical Formula 14]

[0355]

[0356] In formula (II) and (III), X represents a halogen atom, R 3 、R 4 and R 5 Each independently represents a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0357] In formula (II), preferably, X represents a halogen atom, R 3 Represents an aryl group.

[0358] Specific examples of X in formulae (II) and (III) include fluorine, chlorine, bromine, and iodine atoms. Of these, chlorine and bromine atoms are preferred due to their excellent sensitivity, and bromine atoms are particularly preferred.

[0359] Furthermore, in formulas (II) and (III), R 3 、R 4 and R 5 Each of these groups is independently preferably an aryl group, and among these, an aryl group substituted with an amide group is preferred from the viewpoint of excellent balance between sensitivity and storage stability.

[0360] Among the above-mentioned electron-accepting polymerization initiators, compounds represented by formula (IV) are particularly preferred.

[0361] [Chemical Formula 15]

[0362]

[0363] In formula (IV), R 4 and R 5 Each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. p and q each independently represent an integer from 1 to 5. In this case, p+q=2 to 6.

[0364] Specific examples of the electron-accepting polymerization initiator represented by any of the above formulae (II) to (IV) include compounds represented by the following formulae, but the present invention is not limited thereto.

[0365] [Chemical Formula 16]

[0366]

[0367] [Chemical Formula 17]

[0368]

[0369] [Chemical Formula 18]

[0370]

[0371] [Chemical Formula 19]

[0372]

[0373] [Chemical Formula 20]

[0374]

[0375] [Chemical Formula 21]

[0376]

[0377] [Chemical Formula 22]

[0378]

[0379] From the viewpoint of improving sensitivity and preventing plate wear, 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.

[0380] Furthermore, the lower limit of the lowest unoccupied molecular orbital (LUMO) of the electron-accepting polymerization initiator is preferably -3.80 eV or higher, and more preferably -3.50 eV or higher.

[0381] In the present invention, the calculation of the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) is performed by the following method.

[0382] First, when the compound to be calculated has a counter ion that is not a main structure forming the HOMO or LUMO, the counter ion can be ignored.

[0383] The structure optimization was performed using the quantum chemical calculation software Gaussian09 under DFT (B3LYP / 6-31G(d)).

[0384] MO (molecular orbital) energy calculations were performed using the structure obtained by the above-mentioned structural optimization under DFT (B3LYP / 6-31+G(d, p) / CPCM (solvent = methanol).

[0385] The MO energy Ebare (unit: Hartree) obtained by the above MO energy calculation is converted into Esca]ed (unit: eV) used as the values ​​of HOMO and LUMO in the present invention according to the following formula.

[0386] Escaled=0.823168×27.2114×Ebare-1.07634

[0387] In addition, 27.2114 is a coefficient used only for Hartree conversion to eV, and 0.823168 and -1.07634 are adjustment coefficients used to determine the HOMO and LUMO of the compound to be calculated so that the calculated values ​​match the measured values.

[0388] The electron-accepting polymerization initiator may be used alone or in combination of two or more.

[0389] The content of the electron-accepting polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass, relative to the total mass of the image recording layer.

[0390] [Electron-donating polymerization initiator (polymerization aid)]

[0391] The image recording layer in the present invention preferably contains an electron donating polymerization initiator (also referred to as a polymerization aid) as a polymerization initiator.

[0392] The electron-donating polymerization initiator is a compound that generates polymerization initiating species such as free radicals by donating an electron to an orbital from which an electron of the infrared absorber is released through intermolecular electron transfer when the electron of the infrared absorber is excited or moves within the molecule by infrared exposure.

[0393] As the electron donating polymerization initiator, an electron donating radical polymerization initiator is preferred.

[0394] From the viewpoint of printing durability, the image recording layer preferably contains a borate compound as an electron-donating polymerization initiator.

[0395] As the borate compound, from the viewpoint of printing durability, a tetraaryl borate compound or a monoalkyltriaryl borate compound is preferred, and a tetraaryl borate compound is more preferred.

[0396] The counter cation of the borate compound is not particularly limited, but is preferably an alkali metal ion or a tetraalkylammonium ion, and more preferably a sodium ion, a potassium ion, or a tetrabutylammonium ion.

[0397] Furthermore, the counter cation of the borate compound may be the cationic polymethine dye described as the infrared absorber in the present invention. For example, the above-mentioned borate compound may be used as the counter cation of the cyanine dye.

[0398] Specifically, as the borate compound, preferably, sodium tetraphenylborate is used.

[0399] Preferred specific examples of electron-donating polymerization initiators B-1 to B-9 are shown below, but the present invention is not limited thereto. In the following chemical formula, Ph represents a phenyl group, and Bu represents an n-butyl group.

[0400] [Chemical Formula 23]

[0401]

[0402] Furthermore, from the viewpoint of improving sensitivity and preventing plate wear, the highest occupied molecular orbital (HOMO) of the electron donating polymerization initiator is preferably -6.00 eV or higher, more preferably -5.95 eV or higher, and even more preferably -5.93 eV or higher.

[0403] Furthermore, the upper limit of the highest occupied molecular orbital (HOMO) of the electron donating polymerization initiator is preferably -5.00 eV or less, and more preferably -5.40 eV or less.

[0404] The electron donating polymerization initiator may be used alone or in combination of two or more.

[0405] The content of the electron-donating polymerization initiator is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and even more preferably 0.1 to 20% by mass, relative to the total mass of the image recording layer, from the viewpoint of sensitivity and printing durability.

[0406] The polymerization initiator may be a compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form a counter salt.

[0407] For example, a compound in which an anion in an electron-donating polymerization initiator and a cation in an electron-accepting polymerization initiator form a counter salt is preferred. As the above-mentioned electron-accepting polymerization initiator and the above-mentioned electron-donating polymerization initiator, a compound in which a cation having an electron-accepting polymerization initiator structure and an anion having an electron-donating polymerization initiator structure form a salt is more preferred. Specifically, a compound in which an onium cation and a borate anion form a counter salt is preferred, more preferably a compound in which an iodonium cation or a sulfonium cation and a borate anion form a counter salt, and particularly preferably a compound in which a diaryliodonium cation or a triarylsulfonium cation and a tetraarylborate anion form a counter salt.

[0408] Preferred embodiments of the anion in the electron-donating polymerization initiator and the cation in the electron-accepting polymerization initiator are the same as the preferred embodiments of the anion in the electron-donating polymerization initiator and the cation in the electron-accepting polymerization initiator described above.

[0409] When the image recording layer contains an anion as an electron donating polymerization initiator and a cation as an electron accepting polymerization initiator (ie, contains a compound forming the counter salt), the image recording layer contains the electron accepting polymerization initiator and the electron donating polymerization initiator.

[0410] Furthermore, a compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form a counter salt can be used as either the electron-donating polymerization initiator or the electron-accepting polymerization initiator.

[0411] Furthermore, a compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form a counter salt may be used in combination with the electron-donating polymerization initiator described above, or may be used in combination with the electron-accepting polymerization initiator described above.

[0412] [Preferred Embodiments of Infrared Absorber and Electron Donating Polymerization Initiator]

[0413] In the image recording layer of the present invention, from the viewpoint of improving sensitivity and printing durability, the value of the HOMO of the infrared absorber minus the HOMO of the electron-donating polymerization initiator (i.e., the value obtained by subtracting the HOMO of the electron-donating polymerization initiator from the HOMO of the infrared absorber) is preferably 0.70 eV or less, more preferably 0.70 eV to -0.10 eV.

[0414] In addition, a negative value means that the HOMO of the electron donating polymerization initiator is higher than the HOMO of the infrared absorber.

[0415] -Preferred Embodiments of Infrared Absorber and Electron-Accepting Polymerization Initiator-

[0416] In the image recording layer of the present invention, from the viewpoint of improving sensitivity and printing durability, the value of the LUMO of the electron-accepting polymerization initiator minus the LUMO of the infrared absorber (i.e., the value obtained by subtracting the LUMO of the infrared absorber from the LUMO of the electron-accepting polymerization initiator) is preferably 1.00 eV or less, more preferably 0.80 eV or less, and even more preferably 0.70 eV or less.

[0417] Furthermore, the value of the LUMO of the electron-accepting polymerization initiator and the LUMO of the infrared absorber is preferably 1.00 eV to -0.10 eV, and more preferably 0.80 eV to 0.30 eV.

[0418] A negative value means that the LUMO of the infrared absorber is higher than the LUMO of the electron-accepting polymerization initiator.

[0419] 〔Polymerizable compounds〕

[0420] The image recording layer in the present invention contains a polymerizable compound.

[0421] In the present invention, the polymerizable compound refers to a compound having a polymerizable group.

[0422] The polymerizable group is not particularly limited as long as it is a known polymerizable group, but is preferably an ethylenically unsaturated group. Furthermore, the polymerizable group may be a free radical polymerizable group or a cationic polymerizable group, but is preferably a free radical polymerizable group.

[0423] Examples of the radical polymerizable group include a (meth)acryloyl group, an allyl group, a vinylphenyl group, and a vinyl group. From the viewpoint of reactivity, a (meth)acryloyl group is preferred.

[0424] The molecular weight (weight average molecular weight when having a molecular weight distribution) of the polymerizable compound is preferably 50 or more and less than 40,000.

[0425] The polymerizable compound used in the present invention may be, for example, a radical polymerizable compound or a cation polymerizable compound, and is preferably an addition polymerizable compound (ethylenically unsaturated compound) having at least one ethylenically unsaturated bond.

[0426] The ethylenically unsaturated compound is preferably a compound having at least one terminal ethylenically unsaturated bond, and 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.

[0427] Among these, 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, from the perspective of UV printing durability. Furthermore, from the perspective of UV 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 contains a trifunctional or higher (preferably heptafunctional or higher, more preferably decafunctional or higher) (meth)acrylate compound.

[0428] [Oligomer]

[0429] 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").

[0430] In the present invention, the oligomer refers to a polymerizable compound having a molecular weight (weight average molecular weight when having a molecular weight distribution) of 600 or more and 30,000 or less and containing at least one polymerizable group.

[0431] Preferred examples of the molecular weight of the oligomer include 1,000 or more and 25,000 or less.

[0432] Furthermore, from the viewpoint of excellent chemical resistance and UV printing durability, the molecular weight of the oligomer is preferably 1,000 or more and 5,000 or less.

[0433] Furthermore, from the viewpoint of improving UV printing durability, the number of polymerizable groups in one molecule of the oligomer is preferably 2 or more, more preferably 3 or more, further preferably 6 or more, and particularly preferably 10 or more.

[0434] Furthermore, the upper limit of the number of polymerizable groups in the oligomer is not particularly limited, but the number of polymerizable groups is preferably 20 or less.

[0435] From the viewpoint of UV 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 10,000 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 5,000 or less.

[0436] Furthermore, when an oligomer is included as the polymerizable compound, a polymer component that may be generated in the process of producing the oligomer may also be included.

[0437] From the viewpoint of UV printing durability and on-press developability, the oligomer preferably comprises at least one selected from a compound having a urethane bond, a compound having an ester bond, and a compound having an epoxy residue, and preferably comprises a compound having a urethane bond.

[0438] In the present invention, the epoxy residue refers to a structure formed of an epoxy group, and for example, refers to the same structure as that obtained by the reaction of an acid group (carboxylic acid group, etc.) with an epoxy group.

[0439] (Compound having a urethane bond)

[0440] As an example of the oligomer, the compound having a urethane bond is preferably 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).

[0441] [Chemical Formula 24]

[0442]

[0443] 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 indicates a bonding position to other structures.

[0444] As L 1 ~L 4 , are each independently preferably an alkylene group having 2 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms, and still more preferably an alkylene group having 4 to 8 carbon atoms. Furthermore, the alkylene group may have a branched or cyclic structure, but is preferably a straight-chain alkylene group.

[0445] It is preferred that the wavy line portion in formula (Ac-1) or formula (Ac-2) is independently directly bonded to the wavy line portion in the group represented by the following formula (Ae-1) or formula (Ae-2).

[0446] [Chemical Formula 25]

[0447]

[0448] 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 a bonding position to the wavy line portion in formula (Ac-1) and formula (Ac-2).

[0449] Furthermore, as the compound having a urethane bond, a compound obtained by introducing a polymerizable group into a polyurethane obtained by a reaction between a polyisocyanate compound and a polyol compound through a polymer reaction can be used.

[0450] For example, a compound having a urethane bond can be obtained by reacting a compound having an epoxy group and a polymerizable group with a polyurethane oligomer obtained by reacting a polyol compound having an acid group with a polyisocyanate compound.

[0451] (Compounds having an ester bond)

[0452] The number of polymerizable groups in the compound having an ester bond as an example of the oligomer is preferably 3 or more, more preferably 6 or more.

[0453] (Compounds having epoxy residues)

[0454] The compound having an epoxy residue as an example of the oligomer is preferably a compound containing a hydroxyl group within the compound.

[0455] Furthermore, the number of polymerizable groups in the compound having an epoxy residue is preferably 2 to 6, more preferably 2 to 3.

[0456] The compound having an epoxy residue can be obtained, for example, by reacting acrylic acid with a compound having an epoxy group.

[0457] Although commercially available products are shown below as specific examples of the oligomer, the oligomer used in the present invention is not limited thereto.

[0458] Examples of commercially available oligomers include UA-510H, UA-306H, UA-306I, and UA-306T (all from KYOEISHA CHEMICAL CO., LTD.), UV-1700B, UV-6300B, and UV7620EA (all from Nippon Synthetic Chemical Industry Co., Ltd.), U-15HA (from Shin-Nakamura Chemical Co., Ltd.), EBECRYL 450, EBECRYL 657, EBECRYL 885, EBECRYL 800, EBECRYL 3416, and EBECRYL 860 (all from DAICEL-ALLNEXL T.).

[0459] From the viewpoint of improving chemical resistance, UV 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 compound in the image recording layer.

[0460] [Low molecular weight polymerizable compounds]

[0461] The polymerizable compound may contain polymerizable compounds other than the above-mentioned oligomers.

[0462] As polymerizable compounds other than oligomers, low molecular weight polymerizable compounds are preferred from the viewpoint of chemical resistance. The low molecular weight polymerizable compounds may be in the chemical form of monomers, dimers, trimers, or mixtures thereof.

[0463] Furthermore, the low-molecular polymerizable compound is preferably at least one polymerizable compound selected from polymerizable compounds having three or more ethylenically unsaturated groups and polymerizable compounds having an isocyanurate ring structure, from the viewpoint of chemical resistance.

[0464] In the present invention, the low-molecular polymerizable compound refers to a polymerizable compound having a molecular weight (weight average molecular weight when there is a molecular weight distribution) of 50 or more and less than 600.

[0465] 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, UV printing durability, and suppression of on-press development residue.

[0466] When the polymerizable compound contains a low molecular weight polymerizable compound as a polymerizable compound other than the oligomer (the total amount when two or more low molecular weight polymerizable compounds are contained), from the viewpoint of chemical resistance, UV 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 on a mass basis, more preferably 10 / 1 to 3 / 7, and even more preferably 10 / 1 to 7 / 3.

[0467] Specific examples of the low-molecular polymerizable compound include the compounds described in paragraphs 0082 to 0086 of International Publication No. 2019 / 013268.

[0468] The details of the polymerizable compound such as the structure, whether to use the compound alone or in combination, and the amount to be added can be arbitrarily set.

[0469] Among them, from the viewpoint of UV printing durability, the image recording layer preferably contains two or more polymerizable compounds.

[0470] The content of the polymerizable compound (the total content of the polymerizable compounds when two or more polymerizable compounds are contained) 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.

[0471] 〔Infrared absorber〕

[0472] The image recording layer in the present invention contains an infrared absorber.

[0473] The infrared absorber is not particularly limited, and examples thereof include pigments and dyes.

[0474] As dyes that can be used as infrared absorbers, commercially available dyes and known dyes described in documents such as "Dye Handbook" (edited by The Society of Synthetic Organic Chemistry, Japan, published in 1977) can be used. Specifically, dyes such as azo dyes, metal complex salt 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 thiol complexes can be used.

[0475] Preferred dyes among these dyes include cyanine dyes, squarylium dyes, pyrylium salts, nickel thiol complexes, and indocyanine dyes. More preferred dyes include cyanine dyes and indocyanine dyes. Among them, cyanine dyes are particularly preferred.

[0476] As the above-mentioned infrared absorber, preferably a cationic polymethine dye having an oxygen atom, a nitrogen atom or a halogen atom at the meta position. As the cationic polymethine dye, preferably cyanine dye, pyrylium dye, thiopyridinium dye, azulene dye etc. are mentioned. From the viewpoint of the ease of acquisition, the solvent solubility during the introduction reaction etc., cyanine dye is preferably used.

[0477] Specific examples of cyanine pigments include compounds described in paragraphs 0017 to 0019 of Japanese Patent Application Laid-Open No. 2001-133969, paragraphs 0016 to 0021 of Japanese Patent Application Laid-Open No. 2002-023360, and paragraphs 0012 to 0037 of Japanese Patent Application Laid-Open No. 2002-040638. Preferably, the compounds described in paragraphs 0034 to 0041 of Japanese Patent Application Laid-Open No. 2002-278057 and paragraphs 0080 to 0086 of Japanese Patent Application Laid-Open No. 2008-195018 are mentioned. Particularly preferably, the compounds described in paragraphs 0035 to 0043 of Japanese Patent Application Laid-Open No. 2007-90850 and the compounds described in paragraphs 0105 to 0113 of Japanese Patent Application Laid-Open No. 2012-206495 are mentioned.

[0478] Furthermore, compounds described in paragraphs 0008 to 0009 of JP-A-5005 and paragraphs 0022 to 0025 of JP-A-2001-222101 can also be preferably used.

[0479] As the pigment, the compounds described in paragraphs 0072 to 0076 of JP-A-2008-195018 are preferred.

[0480] Furthermore, as the infrared absorber, an infrared absorber that decomposes by exposure to infrared rays can also be preferably used.

[0481] As the infrared absorber that decomposes by infrared exposure, those described in JP-A-2008-544322, WO-2016 / 027886, WO-2017 / 141882, or WO-2018 / 043259 can be preferably used.

[0482] Furthermore, as the infrared absorber that decomposes by exposure to infrared rays, the decomposable infrared absorber used in the outermost layer as described above can be used.

[0483] The infrared absorbent may be used alone or in combination of two or more.

[0484] Furthermore, as the infrared absorber, a pigment and a dye may be used in combination.

[0485] The content of the infrared absorber is preferably 0.1% by mass to 10.0% by mass, more preferably 0.5% by mass to 5.0% by mass, relative to the total mass of the image recording layer.

[0486] 〔particle〕

[0487] From the viewpoint of developability and UV printing durability, the image recording layer in the present invention preferably contains particles. The particles may be inorganic particles or organic particles.

[0488] Among these, the particles preferably include organic particles, and more preferably include polymer particles.

[0489] That is, the image recording layer in the present invention preferably contains polymer particles.

[0490] As the inorganic particles, known inorganic particles can be used, and metal oxide particles such as silica particles and titania particles can be preferably used.

[0491] [Polymer particles]

[0492] Examples of polymer particles include particles containing an addition polymerization type resin (i.e., addition polymerization type polymer particles), particles containing an addition polymerization type resin (i.e., addition polymerization type polymer particles), and particles containing a condensation type resin (i.e., condensation type polymer particles). Among these, addition polymerization type polymer particles or addition polymerization type polymer particles are preferred.

[0493] Furthermore, the polymer particles may be particles containing a thermoplastic resin (ie, thermoplastic polymer particles) from the viewpoint of enabling thermal fusion.

[0494] Furthermore, the polymer particles may be in the form of microcapsules, microgels (ie, cross-linked polymer particles), and the like.

[0495] The polymer particles are preferably selected from thermoplastic polymer particles, thermoreactive polymer particles, polymer particles having polymerizable groups, microcapsules containing hydrophobic compounds, and microgels (crosslinked polymer particles). Among them, polymer particles having polymerizable groups are preferred.

[0496] In a particularly preferred embodiment, the polymer particles contain at least one ethylenically unsaturated group. The presence of such polymer particles can improve the printing durability of the exposed area and the on-press developability of the unexposed area.

[0497] Preferred thermoplastic polymer particles include those described in Research Disclosure No. 33303 of January 1992, Japanese Patent Application Laid-Open Nos. 9-123387, 9-131850, 9-171249, and 9-171250, and European Patent No. 931647.

[0498] Specific examples of the thermoplastic resin constituting the thermoplastic polymer particles include homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and acrylates or methacrylates having a polyalkylene structure, or mixtures thereof.

[0499] The thermoplastic polymer particles preferably contain a thermoplastic resin having a structural unit composed of an aromatic vinyl compound and a structural unit having a nitrile group, from the viewpoint of ink acceptability and UV printing durability.

[0500] The aromatic vinyl compound may be any compound having a structure in which a vinyl group is bonded to an aromatic ring, and examples thereof include styrene compounds and vinylnaphthalene compounds. Styrene compounds are preferred, and styrene is more preferred.

[0501] Examples of the styrene compound include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene.

[0502] From the viewpoint of ink adherence, the content of the structural unit formed from the aromatic vinyl compound is preferably greater than the content of the structural unit having a nitrile group described later, and is more preferably 15% to 85% by mass, and even more preferably 30% to 70% by mass, relative to the total mass of the thermoplastic resin.

[0503] The structural unit having a nitrile group is preferably introduced using a monomer having a nitrile group.

[0504] Examples of the monomer having a nitrile group include acrylonitrile compounds, and preferably (meth)acrylonitrile.

[0505] As the structural unit having a nitrile group, a structural unit composed of (meth)acrylonitrile is preferred.

[0506] From the viewpoint of ink adherence, the content of the structural unit having a nitrile group is preferably less than the content of the structural unit formed from the above-mentioned aromatic vinyl compound, and is more preferably 55% to 90% by mass, and even more preferably 60% to 85% by mass, relative to the total mass of the resin.

[0507] Furthermore, when the resin contained in the thermoplastic polymer particles contains constituent units formed from an aromatic vinyl compound and constituent units having a nitrile group, the content ratio of the constituent units formed from the aromatic vinyl compound to the constituent units having a nitrile group (constituent units formed from an aromatic vinyl compound:constituent units having a nitrile group) is preferably 5:5 to 9:1, more preferably 6:4 to 8:2, on a mass basis.

[0508] From the viewpoint of UV printing durability and chemical resistance, the resin contained in the thermoplastic polymer particles preferably further has a structural unit composed of an N-vinyl heterocyclic compound.

[0509] Examples of the N-vinyl heterocyclic compound include N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam, and N-vinylimidazole, with N-vinylpyrrolidone being preferred.

[0510] The content of the structural unit formed from the N-vinyl heterocyclic compound is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 40% by mass, relative to the total mass of the thermoplastic resin.

[0511] The resin contained in the thermoplastic polymer particles may contain a structural unit having an acidic group, but preferably does not contain a structural unit having an acidic group from the viewpoint of on-press developability and ink adherence.

[0512] Specifically, the content of the structural unit having an acidic group in the thermoplastic resin is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. The lower limit of the content is not particularly limited and may be 0% by mass.

[0513] The acid value of the thermoplastic resin is preferably 160 mgKOH / g or less, more preferably 80 mgKOH / g or less, and even more preferably 40 mgKOH / g or less. The lower limit of the acid value is not particularly limited and may be 0 mgKOH / g.

[0514] In the present invention, the acid value is determined by a measurement method in accordance with JIS K 0070-1992.

[0515] From the viewpoint of ink adherence, the thermoplastic resin contained in the thermoplastic polymer particles may contain a structural unit containing a hydrophobic group.

[0516] Examples of the hydrophobic group include an alkyl group, an aryl group, and an aralkyl group.

[0517] The structural unit containing a hydrophobic group is preferably a structural unit formed from an alkyl (meth)acrylate compound, an aryl (meth)acrylate compound, or an arylalkyl (meth)acrylate compound, and more preferably a structural unit formed from an alkyl (meth)acrylate compound.

[0518] The content of the structural unit having a hydrophobic group in the thermoplastic resin contained in the thermoplastic polymer particles is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, relative to the total mass of the resin.

[0519] From the viewpoint of UV printing durability and on-press developability, the thermoplastic resin contained in the thermoplastic polymer particles preferably has a hydrophilic group.

[0520] The hydrophilic group is not particularly limited as long as it has a hydrophilic structure, and examples thereof include acid groups such as a carboxyl group, a hydroxyl group, an amino group, a nitrile group, and a polyalkylene oxide structure.

[0521] From the viewpoint of UV printing durability and on-press developability, the hydrophilic group is preferably a group having a polyalkylene oxide structure, a group having a polyester structure, or a sulfonic acid group. A group having a polyalkylene oxide structure or a sulfonic acid group is more preferred, and a group having a polyalkylene oxide structure is still more preferred.

[0522] As the polyalkylene oxide structure, from the viewpoint of on-press developability, a polyethylene oxide structure, a polypropylene oxide structure, or a poly(ethylene oxide / propylene oxide) structure is preferred.

[0523] Furthermore, from the viewpoint of on-press developability, among the hydrophilic groups, the polyalkylene oxide structure preferably has a polypropylene oxide structure, and more preferably has a polyethylene oxide structure and a polypropylene oxide structure.

[0524] From the viewpoint of on-press developability, the number of alkylene oxide structures in the polyalkylene oxide structure is preferably 2 or more, more preferably 5 or more, further preferably 5 to 200, and particularly preferably 8 to 150.

[0525] Furthermore, from the viewpoint of on-press developability, the hydrophilic group is preferably a group represented by Formula Z described later.

[0526] Furthermore, among the hydrophilic groups possessed by the thermoplastic resin, a group represented by the following formula PO is preferred.

[0527] [Chemical Formula 26]

[0528]

[0529] In the formula PO, L P Each independently represents an alkylene group, R P represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 100.

[0530] In the formula PO, L P Each independently preferably is ethylene, 1-methylethylene or 2-methylethylene, and more preferably is ethylene.

[0531] In the formula PO, R P It is preferably a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, further preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

[0532] In the formula PO, n is preferably an integer of 1-10, and more preferably an integer of 1-4.

[0533] The content of the structural unit having a hydrophilic group is preferably 5% by mass to 60% by mass, more preferably 10% by mass to 30% by mass, relative to the total mass of the resin.

[0534] The resin contained in the thermoplastic polymer particles may further contain other structural units.

[0535] As other structural units, structural units other than the above-mentioned structural units can be contained without particular limitation, and examples thereof include structural units formed from acrylamide compounds, vinyl ether compounds, and the like.

[0536] The content of other structural units in the thermoplastic resin is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 30% by mass, relative to the total mass of the thermoplastic resin.

[0537] Examples of the thermoreactive polymer particles include polymer particles having a thermoreactive group.

[0538] The thermo-reactive resin particles form hydrophobic regions through cross-linking due to a thermal reaction and changes in functional groups during cross-linking.

[0539] The thermoreactive group in the polymer particles having a thermoreactive group may be any functional group that undergoes any reaction as long as it can form a chemical bond, but a polymerizable group is preferred. Examples thereof include ethylenically unsaturated groups that undergo free radical polymerization (e.g., acryloyl, methacryloyl, vinyl, allyl, etc.), cationically polymerizable groups (e.g., vinyl, vinyloxy, epoxy, oxetanyl, etc.), isocyanate groups or their blocks that undergo addition reactions, epoxy groups, vinyloxy groups, and functional groups having active hydrogen atoms that are the reaction targets of these groups (e.g., amino, hydroxyl, carboxyl, etc.), carboxyl groups that undergo condensation reactions and hydroxyl or amino groups that are the reaction targets, acid anhydrides that undergo ring-opening addition reactions and amino or hydroxyl groups that are the reaction targets, and the like.

[0540] The resin having the heat-reactive group may be an addition polymerization type resin, an addition polymerization type resin, a condensation polymerization type resin, or a thermoplastic resin.

[0541] Preferred microcapsules include, for example, those described in Japanese Patent Application Laid-Open Nos. 2001-277740 and 2001-277742, which contain at least a portion of the components of the image-recording layer (preferably a hydrophobic compound). A preferred embodiment of the image-recording layer containing microcapsules as polymer particles is a structure in which the hydrophobic component (i.e., the hydrophobic compound) of the components of the image-recording layer is contained within the microcapsules, while the hydrophilic component (i.e., the hydrophilic compound) is contained on the outside of the microcapsules.

[0542] In order to obtain microcapsules containing the constituent components of the image recording layer, a known synthesis method can be applied.

[0543] The microgel (cross-linked polymer particles) can contain a portion of the components of the image-recording layer on at least one of its surface or interior. In particular, reactive microgels having polymerizable groups on their surfaces are preferred from the perspectives of the sensitivity of the lithographic printing plate precursor and the printing durability of the resulting lithographic printing plate.

[0544] In order to obtain a microgel containing constituent components of the image recording layer, a known synthesis method can be applied.

[0545] From the viewpoint of printing durability, stain resistance, and storage stability of the resulting lithographic printing plate, the polymer particles are preferably addition-polymerized polymer particles obtained by reacting a polyvalent isocyanate compound, which is an adduct of a polyvalent phenol compound having two or more hydroxyl groups in its molecule and isophorone diisocyanate, with a compound having active hydrogen.

[0546] As the polyphenol compound, a compound having a plurality of benzene rings having a phenolic hydroxyl group is preferable.

[0547] The compound having active hydrogen is preferably a polyol compound or a polyamine compound, more preferably a polyol compound, and still more preferably at least one compound selected from propylene glycol, glycerin, and trimethylolpropane.

[0548] Furthermore, water can be used as the compound having active hydrogen. When water is used, amines generated by the reaction between the isocyanate groups of the polyvalent isocyanate compound and water can form urea bonds to form particles.

[0549] As resin particles obtained by reacting a polyvalent isocyanate compound which is an adduct of a polyphenol compound having two or more hydroxyl groups in the molecule and isophorone diisocyanate, and a compound having active hydrogen, preferably, microgels obtained by the preparation method described in paragraphs 0230 to 0234 of International Publication No. 2018 / 043259 are mentioned.

[0550] Furthermore, from the viewpoint of printing durability and solvent resistance of the obtained lithographic printing plate, the polymer particles are preferably addition-polymerized polymer particles having a hydrophobic main chain and comprising both i) a structural unit having a nitrile group directly bonded to the hydrophobic main chain and ii) a structural unit having a side group containing a hydrophilic polyalkylene oxide segment.

[0551] Specifically, preferred examples of such addition polymerization-type polymer particles are those described in paragraph 0156 of JP-A-2019-64269.

[0552] (Group represented by formula Z)

[0553] The polymer particles in the present invention preferably have a group represented by the following formula Z as a hydrophilic group.

[0554] In particular, the polymer particles in the present invention are preferably addition polymerization type polymer particles having a hydrophilic group including a group represented by the following formula Z.

[0555] Formula Z: *-QWY

[0556] In formula Z, Q represents a divalent linking group, W represents a divalent group having a hydrophilic structure or a divalent group having a hydrophobic structure, Y represents a monovalent group having a hydrophilic structure or a monovalent group having a hydrophobic structure, any of W and Y has a hydrophilic structure, and * represents a bonding site with another structure.

[0557] Furthermore, it is preferred that the hydrophilic structures included in formula Z all include a polyalkylene oxide structure.

[0558] Q in the above formula Z is preferably a divalent linking group having 1 to 20 carbon atoms, and more preferably a divalent linking group having 1 to 10 carbon atoms.

[0559] Furthermore, Q in the above formula Z is preferably an alkylene group, an arylene group, an ester bond, an amide bond, or a group obtained by combining two or more of these, and more preferably a phenylene group, an ester bond, or an amide bond.

[0560] The divalent group having a hydrophilic structure in W of the above formula Z is preferably a group containing a polyalkylene oxide structure, preferably a polyalkyleneoxy group or a group having -CH2CH2NR bonded to one end of the polyalkyleneoxy group. W - group. In addition, R W represents a hydrogen atom or an alkyl group, the following R W It has the same meaning.

[0561] The divalent group having a hydrophobic structure in W of the above formula Z is preferably -R WA -、-OR WA -O-、-R W NR WA -NR W -、-OC(=O)-R WA -O-or-OC(=O)-R WA -O-. In addition, R WA Each independently represents a linear, branched or cyclic alkylene group having 6 to 120 carbon atoms, a halogenated alkylene group having 6 to 120 carbon atoms, an arylene group having 6 to 120 carbon atoms, an alkarylene group (a divalent group obtained by removing one hydrogen atom from an alkylaryl group) having 7 to 120 carbon atoms, or an aralkylene group having 7 to 120 carbon atoms.

[0562] The monovalent group having a hydrophilic structure in Y of the above formula Z is preferably -OH, -C(=O)OH, a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end, or a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the other end thereof bonded with -CH2CH2N(R W Among them, as a monovalent group having a hydrophilic structure, a group containing a polyalkylene oxide structure is preferred, and -CH2CH2N(R W )-group.

[0563] The monovalent group having a hydrophobic structure in Y of the above formula Z is preferably a linear, branched or cyclic alkyl group having 6 to 120 carbon atoms, a halogenated alkyl group having 6 to 120 carbon atoms, an aryl group having 6 to 120 carbon atoms, an alkaryl group (alkylaryl group) having 7 to 120 carbon atoms, an aralkyl group having 7 to 120 carbon atoms, -OR WB 、-C(=O)OR WB or -OC(=O)R WB . R WB It represents an alkyl group having 6 to 20 carbon atoms.

[0564] In the polymer particles having a group represented by the above formula Z, from the viewpoints of printing durability, ink adhesion, and on-press developability, it is more preferred that W is a divalent group having a hydrophilic structure, more preferably Q is a phenylene group, an ester bond, or an amide bond, W is a polyalkyleneoxy group, and Y is a polyalkyleneoxy group having a terminal hydrogen atom or an alkyl group.

[0565] Furthermore, the group represented by formula Z can function as a dispersing group that improves the dispersibility of polymer particles.

[0566] From the perspectives of printing durability and on-press developability, the polymer particles of the present invention preferably have polymerizable groups (preferably ethylenically unsaturated groups), and more preferably have polymerizable groups on the surface. The use of polymer particles having polymerizable groups can easily suppress plate wear (preferably UV plate wear) and improve printing durability (preferably UV printing durability).

[0567] From the viewpoint of printing durability, the polymer particles in the present invention are preferably resin particles having a hydrophilic group and a polymerizable group.

[0568] The polymerizable group may be a cationically polymerizable group or a radically polymerizable group, but is preferably a radically polymerizable group from the viewpoint of reactivity.

[0569] The polymerizable group is not particularly limited as long as it is a polymerizable group. However, from the viewpoint of reactivity, an ethylenically unsaturated group is preferred, a vinylphenyl (styryl) group, a (meth)acryloyloxy group, or a (meth)acrylamide group is more preferred, and a (meth)acryloyloxy group is particularly preferred.

[0570] Furthermore, the resin constituting the polymer particles having a polymerizable group preferably includes a structural unit having a polymerizable group.

[0571] Alternatively, polymerizable groups can be introduced onto the surface of polymer particles by polymer reaction.

[0572] Furthermore, from the perspectives of printing durability, ink adherence, on-press developability, and suppressing development residue during on-press development, the polymer particles preferably contain an addition-polymerized resin having a urea bond, more preferably contain an addition-polymerized resin having a structure obtained by reacting at least an isocyanate compound represented by the following formula (Iso) with water, and particularly preferably contain an addition-polymerized resin having a structure obtained by reacting at least an isocyanate compound represented by the following formula (Iso) with water, and having a polyethylene oxide structure and a polypropylene oxide structure as the polyoxyalkylene structure. Furthermore, the particles containing the addition-polymerized resin having a urea bond are preferably microgels.

[0573] [Chemical Formula 27]

[0574]

[0575] In formula (Iso), n represents an integer of 0-10.

[0576] As an example of the reaction between the isocyanate compound represented by the above formula (Iso) and water, the reaction shown below can be mentioned. In the following example, n=0 and a 4,4-isomer is used.

[0577] As shown below, when the isocyanate compound represented by the above formula (Iso) is reacted with water, a portion of the isocyanate groups in the water are hydrolyzed to generate amino groups. The generated amino groups then react with the isocyanate groups to form urea bonds, thereby forming a dimer. The following reaction is then repeated to form an addition-polymerized resin having urea bonds.

[0578] Furthermore, in the following reaction, by adding a compound reactive with an isocyanate group (a compound having active hydrogen), such as an alcohol compound or an amine compound, the structure of the alcohol compound or amine compound can be introduced into the addition-polymerized resin having a urea bond.

[0579] As the compound having active hydrogen, preferably, the compounds having active hydrogen mentioned above are mentioned.

[0580] [Chemical Formula 28]

[0581]

[0582] Furthermore, the polyaddition resin having a urea bond preferably has an ethylenically unsaturated group, and more preferably has a group represented by the following formula (PETA).

[0583] [Chemical Formula 29]

[0584]

[0585] In formula (PETA), the wavy line portion indicates the bonding position to other structures.

[0586] (Synthesis of Polymer Particles)

[0587] There are no particular limitations on the method for synthesizing the polymer particles, as long as the particles can be synthesized using the various resins described above. Examples of the method for synthesizing the polymer particles include well-known methods for synthesizing polymer particles, such as emulsion polymerization, suspension polymerization, dispersion polymerization, soap-free polymerization, and microemulsion polymerization.

[0588] Furthermore, for the synthesis of polymer particles, known microcapsule synthesis methods, microgel (cross-linked resin particles) synthesis methods, and the like can be used.

[0589] (Average particle size)

[0590] The average particle size of the particles is preferably 0.01 μm to 3.0 μm, more preferably 0.03 μm to 2.0 μm, and even more preferably 0.10 μm to 1.0 μm. Within this range, good resolution and temporal stability can be obtained.

[0591] The average particle size of the particles is measured by light scattering or by taking an electron micrograph of the particles, measuring the particle sizes of 5,000 particles in total on the photograph, and calculating the average value. For non-spherical particles, the equivalent circle diameter of the particles in the photograph is used.

[0592] In addition, the average particle size of the particles in the present invention refers to the volume average particle size unless otherwise specified.

[0593] The particles (preferably polymer particles) may be used alone or in combination of two or more.

[0594] From the viewpoint of developability and printing durability, the content of particles (preferably polymer particles) relative to the total mass of the image recording layer is preferably 5% by mass to 90% by mass, more preferably 10% by mass to 90% by mass, further preferably 20% by mass to 90% by mass, and particularly preferably 50% by mass to 90% by mass.

[0595] [Other ingredients]

[0596] The image recording layer in the present invention may contain other components in addition to the components already described.

[0597] Examples of other components include a binder polymer, a color developer, a chain transfer agent, a low-molecular-weight hydrophilic compound, a sensitizer, and other additives.

[0598] [Binder polymer]

[0599] The image-recording layer may contain a binder polymer as needed.

[0600] Here, the binder polymer refers to a polymer other than polymer particles, that is, a polymer that is not in a particle shape.

[0601] Furthermore, regarding the binder polymer, ammonium salt-containing polymers in sensitizers and polymers used as surfactants are excluded.

[0602] As the binder polymer, known binder polymers (eg, (meth)acrylic resins, polyvinyl acetal resins, polyurethane resins, etc.) used in the image recording layer of the lithographic printing plate precursor can be preferably used.

[0603] As an example, a binder polymer used in an on-press development type planographic printing plate precursor (hereinafter also referred to as a binder polymer for on-press development) will be described in detail.

[0604] As a binder polymer for on-press development, a binder polymer having an alkylene oxide chain is preferred. The binder polymer having an alkylene oxide chain may have a poly(alkylene oxide) moiety in the main chain or in a side chain. Furthermore, it may be a graft polymer having a poly(alkylene oxide) moiety in a side chain, or a block copolymer comprising a block composed of repeating units containing poly(alkylene oxide) and a block composed of repeating units not containing poly(alkylene oxide).

[0605] When the main chain has a poly(alkylene oxide) moiety, a polyurethane resin is preferred.

[0606] Examples of polymers having a poly(alkylene oxide) moiety in a side chain include (meth)acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, polystyrene resins, novolac-type phenolic resins, polyester resins, synthetic rubbers, and natural rubbers, with (meth)acrylic resins being particularly preferred.

[0607] Furthermore, as other preferred examples of binder polymers, there can be cited polymer compounds (hereinafter also referred to as star-shaped polymer compounds) having a polyfunctional thiol having more than 6 functions and less than 10 functions as a core portion, a polymer chain bonded to the core portion via a sulfide bond, and the polymer chain having a polymerizable group.

[0608] As the star-shaped polymer compound, for example, the compounds described in JP-A-2012-148555 can be preferably used.

[0609] Examples of star-shaped polymer compounds include compounds having polymerizable groups such as ethylenically unsaturated bonds in the main chain or side chain, preferably in the side chain, for improving the film strength of the image area, as described in Japanese Patent Application Laid-Open No. 2008-195018. The polymerizable groups in the star-shaped polymer compound form crosslinks between molecules of the star-shaped polymer compound, accelerating curing.

[0610] As the polymerizable group, preferably, an ethylenically unsaturated group such as (meth) acrylic acid, vinyl, allyl, vinylphenyl (styryl), or an epoxy group, etc., from the viewpoint of polymerization reactivity, more preferably a (meth) acrylic acid, vinyl, vinylphenyl (styryl), and particularly preferably a (meth) acrylic acid. These groups can be introduced into the polymer by polymer reaction or copolymerization. Specifically, for example, the reaction of a polymer having a carboxyl group on the side chain with glycidyl methacrylate, or the reaction of a polymer having an epoxy group with a carboxylic acid containing an ethylenically unsaturated group such as methacrylic acid can be utilized.

[0611] The molecular weight of the binder polymer is preferably a weight average molecular weight (Mw) of 40,000 or more, more preferably 40,000 to 300,000, as a polystyrene conversion value determined by GPC.

[0612] When the binder polymer does not have a polymerizable group, the weight average molecular weight (Mw) is preferably 10,000 to 300,000.

[0613] As the binder polymer, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in JP-A-2008-195018 may be used in combination as needed. Furthermore, a lipophilic polymer and a hydrophilic polymer may also be used in combination.

[0614] The binder polymer may be used alone or in combination of two or more.

[0615] The binder polymer may be contained in any amount in the image recording layer, but the content of the binder polymer is preferably 1 to 90% by mass, more preferably 5 to 80% by mass, relative to the total mass of the image recording layer.

[0616] [Developer]

[0617] The image-recording layer may contain a developer.

[0618] The color developer is preferably an acid color developer and preferably contains a colorless compound.

[0619] The "developer" used in the present invention refers to a compound having the property of developing or fading color by stimulation of light, acid, or the like, thereby changing the color of the image recording layer. Furthermore, an "acid developer" refers to a compound having the property of developing or fading color by heating while receiving an electron-accepting compound (e.g., a proton such as an acid), thereby changing the color of the image recording layer.

[0620] As the acid color developer, a colorless compound having a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, or amide, which undergoes rapid ring-opening or cleavage when in contact with an electron-accepting compound, is particularly preferred.

[0621] Examples of the acid developer include the compounds described in paragraphs 0184 to 0191 of JP-A-2019-18412.

[0622] Among them, the color developer is preferably at least one compound selected from the group consisting of spiropyran compounds, spirooxazine compounds, spirolactone compounds, and spirolactam compounds, from the viewpoint of color development.

[0623] The color of the developer after color development preferably has a maximum absorption wavelength in the range of 450 nm to 650 nm from the viewpoint of visibility. The color tone of the developer after color development is preferably red, purple, blue, or dark green.

[0624] Furthermore, from the viewpoint of improving the visibility of the exposed portion, it is preferable to use a colorless dye as the developer (preferably an acid developer).

[0625] Here, the colorless pigment is not particularly limited as long as it has a colorless structure, but preferably has a helical structure, and more preferably has a spirolactone ring structure.

[0626] Furthermore, as the colorless dye, from the viewpoint of improving the visibility of the exposed portion, a colorless dye having a phthalide structure or a fluoran matrix structure is preferred.

[0627] Moreover, as a color developer (preferably an acid color developer), from the viewpoint of improving the visual recognizability of the exposed portion, it is preferred that the compound be a colorless pigment having a phthalide structure or a fluoran matrix structure and represented by any of the following formulas (Le-1) to (Le-3), and more preferably a compound represented by the following formula (Le-2).

[0628] [Chemical formula 30]

[0629]

[0630] In formula (Le-1) to formula (Le-3), ERG each independently represents an electron-donating group, X1 to X4 each independently represents a hydrogen atom, a halogen atom or a dialkylaniline group, and X5 to X 10 Each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 does not exist, when Y2 is N, X4 does not exist, Ra1 represents a hydrogen atom, an alkyl group or an alkoxy group, and Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group.

[0631] As the electron-donating group in the ERG of formula (Le-1) to formula (Le-3), from the viewpoint of color development and visual recognition of the exposed portion, preferably 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, an alkoxy group, an aryloxy group, a heteroaryloxy group or an alkyl group, more preferably 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, an alkoxy group or an aryloxy group, further preferably a monoalkylmonoarylamino group, a diarylamino group, a diheteroarylamino group or a monoarylmonoheteroarylamino group, and particularly preferably a monoalkylmonoarylamino group.

[0632] Furthermore, from the perspective of color development and visibility of the exposed portion, the electron-donating group in the ERG is preferably a disubstituted amino group having 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, and more preferably a disubstituted amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position. Furthermore, for the same reason, the electron-donating group in the ERG is further preferably an amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position, and an aryl or heteroaryl group. Especially preferred is an amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position, and an aryl or heteroaryl group having an electron-donating group.

[0633] Here, in the present invention, the ortho position in an aryl group or heteroaryl group other than a phenyl group refers to a bonding position adjacent to the 1st position (e.g., the 2nd position) when the bonding position of the aryl group or heteroaryl group to another structure is set as the 1st position.

[0634] As the electron-donating group possessed by the above-mentioned aryl group or heteroaryl group, from the viewpoint of color development and visual recognition of the exposed portion, preferably 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, an alkoxy group, an aryloxy group, a heteroaryloxy group or an alkyl group, more preferably an alkoxy group, an aryloxy group, a heteroaryloxy group or an alkyl group, and particularly preferably an alkoxy group.

[0635] From the viewpoint of improving the visibility of the exposed portion, X1 to X4 in Formulae (Le-1) to (Le-3) are each independently preferably a hydrogen atom or a chlorine atom, and more preferably a hydrogen atom.

[0636] From the viewpoint of improving the visibility of the exposed portion, X5 to X6 in formula (Le-2) or formula (Le-3) are 10 Each independently preferably is a hydrogen atom, a halogen atom, an alkyl group, an aryl group, 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 hydroxyl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heteroaryloxycarbonyl group or a cyano group; more preferably is a hydrogen atom, a halogen atom, an alkyl group, an aryl, an alkoxy group or an aryloxy group; further preferably is a hydrogen atom, a halogen atom, an alkyl group or an aryl group; and particularly preferably is a hydrogen atom.

[0637] From the viewpoint of improving the visibility of the exposed portion, at least one of Y1 and Y2 in Formulas (Le-1) to (Le-3) is preferably C, and both Y1 and Y2 are more preferably C.

[0638] From the viewpoint of improving the visibility of the exposed portion, Ra1 in formula (Le-3) is preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group.

[0639] From the viewpoint of improving the visibility of the exposed portion, Rb1 to Rb4 in formula (Le-1) are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group.

[0640] Furthermore, from the perspective of improving the visual recognition of the exposed portion, the above-mentioned colorless pigment having a phthalide structure or a fluoran matrix structure is more preferably a compound represented by any of the following formulas (Le-4) to (Le-6), and further preferably a compound represented by the following formula (Le-5).

[0641] [Chemical Formula 31]

[0642]

[0643] In formulas (Le-4) to (Le-6), ERG independently represents an electron-donating group, X1 to X4 independently represent a hydrogen atom, a halogen atom or a dialkylaniline group, Y1 and Y2 independently represent C or N, when Y1 is N, X1 does not exist, and when Y2 is N, X4 does not exist, Ra1 represents a hydrogen atom, an alkyl group or an alkoxy group, and Rb1 to Rb4 independently represent a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group.

[0644] ERG, X1~X4, Y1, Y2, Ra1 and Rb1~Rb4 in formula (Le-4) to formula (Le-6) have the same meanings as ERG, X1~X4, Y1, Y2, Ra1 and Rb1~Rb4 in formula (Le-1) to formula (Le-3), and the preferred embodiments are also the same.

[0645] Moreover, from the perspective of improving the visual recognition of the exposed part, the above-mentioned colorless pigment having a phthalide structure or a fluoran matrix structure is further preferably a compound represented by any of the following formulas (Le-7) to (Le-9), and is particularly preferably a compound represented by the following formula (Le-8).

[0646] [Chemical Formula 32]

[0647]

[0648] In formulas (Le-7) to (Le-9), X1 to X4 each independently represent a hydrogen atom, a halogen atom or a dialkylaniline group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 does not exist, and when Y2 is N, X4 does not exist, Ra1 to Ra4 each independently represent a hydrogen atom, an alkyl group or an alkoxy group, Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group, and Rc1 and Rc2 each independently represent an aryl group or a heteroaryl group.

[0649] X1 to X4, Y1 and Y2 in formulas (Le-7) to (Le-9) have the same meanings as X1 to X4, Y1 and Y2 in formulas (Le-1) to (Le-3), and preferred embodiments are also the same.

[0650] From the viewpoint of improving visibility of the exposed portion, Ra1 to Ra4 in Formula (Le-7) or Formula (Le-9) are each independently preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group.

[0651] From the perspective of improving the visual recognition of the exposed part, Rb1 to Rb4 in formula (Le-7) to formula (Le-9) are each independently preferably a hydrogen atom, an alkyl group, or an aryl group substituted by an alkyl group or an alkoxy group, more preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom or a methyl group.

[0652] From the viewpoint of improving the visibility of the exposed portion, Rc1 and Rc2 in formula (Le-8) are each independently preferably a phenyl group or an alkylphenyl group, and more preferably a phenyl group.

[0653] Furthermore, in formula (Le-8), from the viewpoint of improving the visibility of the exposed portion, it is preferred that X1 to X4 are hydrogen atoms, and Y1 and Y2 are C.

[0654] Furthermore, in formula (Le-8), from the viewpoint of improving visibility of the exposed portion, Rb1 and Rb2 are each independently preferably a hydrogen atom, an alkyl group, or an aryl group substituted with an alkyl group or an alkoxy group, and more preferably a hydrogen atom or an alkyl group.

[0655] Furthermore, as Rb1, Rb2, Rc1, and Rc2 in formula (Le-8), the following aspects are also preferred.

[0656] From the perspective of color development and visual recognition of the exposed portion, Rb1 and Rb2 in formula (Le-8) are each independently preferably an aryl group or a heteroaryl group, more preferably an aryl group, further preferably an aryl group having an electron-donating group, and particularly preferably a phenyl group having an electron-donating group at the para position.

[0657] From the viewpoint of color development and visual recognition of the exposed portion, Rc1 and Rc2 in formula (Le-8) are each independently preferably 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, more preferably an aryl group having a substituent at at least one ortho position, further preferably a phenyl group having a substituent at at least one ortho position, and particularly preferably a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position. As the substituents in Rc1 and Rc2, the substituents described below can be mentioned.

[0658] Furthermore, in formula (Le-8), Rc1 and Rb1, and Rc2 and Rb1 may each independently bond at an ortho position to form a ring (eg, a carbazole ring).

[0659] Furthermore, as the above-mentioned electron-donating group in Rb1, Rb2, Rc1 and Rc2, from the viewpoint of color development and visual recognition of the exposed portion, preferably it is 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, an alkoxy group, an aryloxy group, a heteroaryloxy group or an alkyl group, more preferably an alkoxy group, an aryloxy group, a heteroaryloxy group or an alkyl group, and especially preferably an alkoxy group.

[0660] Furthermore, as the developer (preferably an acid developer), from the viewpoint of color development and visibility of the exposed portion, a compound represented by the following formula (Le-10), which is a colorless pigment having the above-mentioned phthalide structure or fluoran matrix structure, is preferred.

[0661] [Chemical Formula 33]

[0662]

[0663] In formula (Le-10), Ar1 each independently represents an aryl group or a heteroaryl group, and Ar2 each 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.

[0664] Preferred aspects of Ar1 in formula (Le-10) are the same as those of Rb1 and Rb2 in formula (Le-8).

[0665] Preferred aspects of Ar2 in formula (Le-10) are the same as those of Rc1 and Rc2 in formula (Le-8).

[0666] The alkyl groups in formula (Le-1) to formula (Le-9) may be linear, branched, or have a ring structure.

[0667] Furthermore, the number of carbon atoms in the alkyl groups in formula (Le-1) to formula (Le-9) is preferably 1 to 20, more preferably 1 to 8, further preferably 1 to 4, and particularly preferably 1 or 2.

[0668] The number of carbon atoms in the aryl group in formula (Le-1) to formula (Le-10) is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8.

[0669] Specific examples of the aryl group in formula (Le-1) to formula (Le-10) include phenyl, naphthyl, anthryl, and phenanthryl groups, which may have a substituent.

[0670] Specific examples of the heteroaryl group in formula (Le-1) to formula (Le-10) include optionally substituted furyl, pyridyl, pyrimidyl, pyrazolyl, and phenylthio groups.

[0671] Furthermore, each group such as a monovalent organic group, an alkyl group, an aryl group, a heteroaryl group, a dialkylanilino group, an alkylamino group, and an alkoxy group in Formula (Le-1) to Formula (Le-9) may have a substituent.

[0672] Examples of the substituents in formulas (Le-1) to (Le-10) include alkyl groups, aryl groups, heteroaryl groups, halogen atoms, amino groups, alkylamino groups, arylamino groups, heteroarylamino groups, dialkylamino groups, monoalkylmonoarylamino groups, monoalkylmonoheteroarylamino groups, diarylamino groups, diheteroarylamino groups, monoarylmonoheteroarylamino groups, hydroxyl groups, alkoxy groups, aryloxy groups, heteroaryloxy groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, heteroaryloxycarbonyl groups, and cyano groups. These substituents may be further substituted with these substituents.

[0673] Specific examples of the colorless dye having a phthalide structure or a fluoran base structure that can be preferably used include the following compounds (S-1 to S-21).

[0674] [Chemical Formula 34]

[0675]

[0676] [Chemical Formula 35]

[0677]

[0678] [Chemical Formula 36]

[0679]

[0680] [Chemical Formula 37]

[0681]

[0682] [Chemical Formula 38]

[0683]

[0684] [Chemical Formula 39]

[0685]

[0686] [Chemical Formula 40]

[0687]

[0688] As the acid developer, a commercially available product can also be used. Commercially available products of the acid developer include, for example, ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H-3035, BLUE203, ATP, H-1046, H-2114 (all manufactured by FukuiYamada Chemical Co., Ltd.), ORANGE-DCF, Vermilion-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF, TH-107 (all manufactured by HODOGAYA CHEMICAL CO., LTD.), ODB, ODB-2, ODB-4, ODB-250, ODB-BlackXV, Blue-63, Blue-502, GN-169, GN-2, Green-118, Red-40, Red-8 (all manufactured by YAMAMOTO CHEMICALS INC.), crystal violet lactone (manufactured by Tokyo Chemical Industry Co., Ltd.), etc.

[0689] Among these commercially available products, ETAC, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, Blue-63, GN-169, and crystal violet lactone are preferred because the films formed therefrom (i.e., image recording layers) have good visible light absorptivity.

[0690] As the colorless dye, from the viewpoint of improving the visibility of the exposed portion, the following compounds can also be mentioned as dyes that can be preferably used.

[0691] [Chemical Formula 41]

[0692]

[0693] The color developer may be used alone or in combination of two or more.

[0694] The content of the developer is preferably 0.5% by mass to 10% by mass, more preferably 1% by mass to 5% by mass, relative to the total mass of the image recording layer.

[0695] The image-recording layer may further contain components other than those described above.

[0696] Components other than the above include those described in paragraphs 0181 to 0190 of JP-A-2009-255434, colorants, printout agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic fine particles, and low-molecular-weight hydrophilic compounds.

[0697] In addition, components other than the above-mentioned ones include hydrophobic precursors (fine particles capable of converting the image recording layer into a hydrophobic state when heat is applied), low-molecular-weight hydrophilic compounds, sensitizers (e.g., phosphonium compounds, nitrogen-containing low-molecular-weight compounds, ammonium-containing polymers), and chain transfer agents, as described in paragraphs 0191 to 0217 of Japanese Patent Application Laid-Open No. 2012-187907.

[0698] [Formation of image recording layer]

[0699] The image recording layer in the lithographic printing plate precursor involved in the present invention can be formed, for example, by dispersing or dissolving the necessary components mentioned above in a known solvent to prepare a coating liquid, applying the coating liquid to a support by a known method such as rod coating, and drying the coating liquid.

[0700] As the solvent used in the coating liquid, a known solvent can be used. Specific examples include 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, and ethyl lactate.

[0701] The solvent may be used alone or in combination of two or more.

[0702] The solid content concentration in the coating liquid is preferably 1% by mass to 50% by mass.

[0703] The coating weight (solid content) of the image recording layer after coating and drying varies depending on the application, but is preferably 0.3 g / m2 from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer. 2 ~3.0g / m 2 .

[0704] Furthermore, the film thickness of the image recording layer in the lithographic printing plate precursor according to the present invention is preferably 0.1 μm to 3.0 μm, more preferably 0.3 μm to 2.0 μm.

[0705] <Support>

[0706] The lithographic printing plate precursor according to the present invention has a support.

[0707] The support may be appropriately selected from known supports for lithographic printing plate precursors and used.

[0708] As the support, a support having a hydrophilic surface (hereinafter also referred to as a "hydrophilic support") is preferred.

[0709] The support in the present invention is preferably an aluminum plate that has been roughened and anodized by a known method. That is, the support in the present invention preferably comprises an aluminum plate and an aluminum anodic oxide film disposed on the aluminum plate.

[0710] [Preferred Embodiments of Support]

[0711] An example of a preferred embodiment of the support used in the present invention is shown below (the aluminum support according to this example is also referred to as "support (1)").

[0712] That is, the support (1) has an aluminum plate and an aluminum anodized film arranged on the above-mentioned aluminum plate, the above-mentioned anodized film is located closer to the above-mentioned image recording layer than the above-mentioned aluminum plate, the above-mentioned anodized film has micropores extending from the surface of the above-mentioned image recording layer side along the depth direction, and the average diameter of the above-mentioned micropores at the surface of the above-mentioned anodized film is greater than 10nm and is less than 100nm.

[0713] In addition, the L of the surface of the anodic oxide film on the image recording layer side is * a * b * Lightness L in the color system * The value of is preferably 70 to 100.

[0714] Figure 1 It is a schematic cross-sectional view of one embodiment of the aluminum support 12a.

[0715] The aluminum support 12a has a laminated structure in which an aluminum plate 18 and an aluminum anodic oxide film 20a (hereinafter referred to as "anodic oxide film 20a") are laminated in this order. Furthermore, the anodic oxide 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 of the present invention preferably has at least an anodic oxide film, an image recording layer, and an outermost layer in this order on the aluminum plate.

[0716] -Anodic oxide film-

[0717] Hereinafter, preferred embodiments of the anodic oxide film 20 a will be described.

[0718] The anodic oxide film 20a is formed on the surface of the aluminum plate 18 by anodizing, and has ultrafine pores 22a that are substantially perpendicular to the film surface and uniformly distributed. The pores 22a extend from the surface of the anodic oxide film 20a on the image recording layer side (the surface of the anodic oxide film 20a on the side opposite to the aluminum plate 18) in the thickness direction (on the aluminum plate 18 side).

[0719] The average diameter (average opening diameter) of the micropores 22a on the surface of the anodic oxide film 20a is preferably greater than 10 nm and less than 100 nm. From the perspective of balancing printing durability, stain resistance, and image visibility, the average diameter is more preferably 15 nm to 60 nm, further 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 the surface layer.

[0720] When the average diameter exceeds 10 nm, printing durability and image visibility are further improved, and when the average diameter is 100 nm or less, printing durability is further improved.

[0721] Regarding the average diameter of the micropores 22a, the surface of the anodized film 20a was observed using a field emission scanning electron microscope (FE-SEM) with a magnification of 150,000 times with N = 4 images. In the 4 images obtained, the diameters of 50 micropores within the range of 400nm×600nm were measured and calculated as the arithmetic mean.

[0722] When the shape of the micropore 22a is not circular, the equivalent circle diameter is used. The "equivalent circle diameter" refers to the diameter of a circle assuming the shape of the opening to have the same projected area as the projected area of ​​the opening.

[0723] The depth of the micropores 22 a is not particularly limited, but is preferably 10 nm to 3,000 nm, more preferably 50 nm to 2,000 nm, and further preferably 300 nm to 1,600 nm.

[0724] The depth is obtained by taking a photograph of the cross section of the anodic oxide film 20 a (magnification 150,000), measuring the depths of 25 or more micropores 22 a , and averaging the measured depths.

[0725] The shape of the micropores 22a is not particularly limited. Figure 2 The micropore 22a is generally straight (generally cylindrical), but may be conical in shape with a diameter decreasing in the depth direction (thickness direction). The shape of the bottom of the micropore 22a is not particularly limited and may be curved (convex) or flat.

[0726] The L of the surface on the image recording layer side of the aluminum support 12a (the surface on the image recording layer side of the anodic oxide film 20a) is * a * b * Lightness L in the color system * The value of is preferably 70 to 100. Of these, 75 to 100 is preferred, and 75 to 90 is more preferred from the viewpoint of achieving a better balance between printing durability and image visibility.

[0727] Regarding the above lightness L * The color difference meter Spectro Eye manufactured by X-Rite Inc. was used for the measurement.

[0728] The following method is also preferably mentioned (hereinafter, the support body involved in the following method will also be referred to as "support body (2)"): in the support body (1), the above-mentioned micropores are composed of a large-diameter pore portion and a small-diameter pore portion, the above-mentioned large-diameter pore portion extends from the surface of the above-mentioned anodized film to a depth of 10nm to 1,000nm, the above-mentioned small-diameter pore portion is connected to the bottom of the above-mentioned large-diameter pore portion, and extends from the connected position to a depth of 20nm to 2,000nm, the average diameter of the above-mentioned large-diameter pore portion at the surface of the above-mentioned anodized film is 15nm to 100nm, and the average diameter of the above-mentioned small-diameter pore portion at the above-mentioned connected position is less than 13nm.

[0729] Figure 2 The aluminum support 12a is Figure 1 Schematic cross-sectional views of various embodiments of aluminum supports are shown.

[0730] exist Figure 2 In the embodiment, the aluminum support 12 b includes an aluminum plate 18 and an anodic oxide film 20 b having micropores 22 b composed of large-diameter pores 24 and small-diameter pores 26 .

[0731] The micropores 22b in the anodic oxide film 20b are composed of large-diameter pores 24 and small-diameter pores 26. The large-diameter pores 24 extend from the surface of the anodic oxide film to a depth of 10 nm to 1,000 nm (depth D: reference φ). Figure 2 ), the small-diameter hole portion 26 is connected to the bottom of the large-diameter hole portion 24 and further extends from the connection position to a depth of 20 nm to 2,000 nm.

[0732] In addition, details of the large-diameter hole portion 24 and the small-diameter hole portion 26 are described in, for example, paragraphs 0107 to 0114 of Japanese Patent Application Laid-Open No. 2019-162855, and this aspect is also applied to the present invention.

[0733] [Method for producing an aluminum support]

[0734] As a method for producing the aluminum support in the present invention, for example, a method of performing the following steps in sequence is preferable.

[0735] Roughening process: The process of roughening the aluminum plate

[0736] Anodizing process: Anodizing the roughened aluminum plate

[0737] Pore ​​enlargement step: The aluminum plate having an anodic oxide film obtained in the anodizing step is brought into contact with an acid aqueous solution or an alkaline aqueous solution to enlarge the diameter of the micropores in the anodic oxide film.

[0738] Hereinafter, the steps of each process will be described in detail.

[0739] (Roughening process)

[0740] The roughening treatment step is a step of performing a roughening treatment including an electrochemical roughening treatment on the surface of the aluminum plate.

[0741] This step is preferably performed before the anodizing step described later. However, if the surface of the aluminum plate already has a preferred surface shape, this step does not need to be performed.

[0742] The roughening treatment of the aluminum plate can be performed by the method described in paragraphs 0086 to 0101 of Japanese Patent Application Laid-Open No. 2019-162855.

[0743] (Anodizing process)

[0744] The procedure of the anodizing treatment step is not particularly limited as long as the above-mentioned micropores can be obtained, and a known method can be used.

[0745] In the anodizing step, an aqueous solution of sulfuric acid, phosphoric acid, oxalic acid, etc. can be used as an electrolytic cell. For example, the concentration of sulfuric acid can be 100 g / L to 300 g / L.

[0746] The conditions for the anodic oxidation treatment can be appropriately set according to the electrolyte used, but examples thereof include a liquid temperature of 5°C to 70°C (preferably 10°C to 60°C), a current density of 0.5 A / dm 2 ~60A / dm 2 (Preferably 5A / dm 2 ~60A / dm 2 ), voltage 1V~100V (preferably 5V~50V), electrolysis time 1 second~100 seconds (preferably 5 seconds~60 seconds) and film weight 0.1g / m 2 ~5g / m 2 (Preferably 0.2 g / m 2 ~3g / m 2 ).

[0747] (Hole expansion treatment)

[0748] The pore expansion treatment is a treatment for increasing the diameter (pore size) of micropores present in the anodic oxide film formed by the above-mentioned anodic oxidation treatment step (pore size expansion treatment).

[0749] The pore expansion treatment can be performed by contacting the aluminum plate obtained by the above-mentioned anodizing treatment step with an acid aqueous solution or an alkaline aqueous solution. The contact method is not particularly limited, and examples thereof include immersion and spraying.

[0750] <Base Coating>

[0751] The lithographic printing plate precursor of the present invention preferably has an undercoat layer (sometimes also referred to as an intermediate layer) between the image-recording layer and the support. The undercoat layer enhances adhesion between the support and the image-recording layer in the exposed areas and facilitates peeling of the image-recording layer from the support in the unexposed areas. Thus, the undercoat layer helps to suppress a decrease in printing durability while improving developability. Furthermore, in the case of infrared laser exposure, the undercoat layer acts as a heat-insulating layer, thereby preventing heat generated by exposure from diffusing to the support and causing a decrease in sensitivity.

[0752] 〔polymer〕

[0753] Examples of compounds used in the undercoat layer include polymers having adsorptive groups and hydrophilic groups that can adsorb to the support surface. To improve adhesion to the image-recording layer, polymers having adsorptive and hydrophilic groups, as well as crosslinkable groups, are preferred. The compounds used in the undercoat layer may be low molecular weight compounds or polymers. Two or more compounds may be mixed as needed.

[0754] When the compound used in the primer layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group is preferred.

[0755] Preferred adsorbable groups capable of adsorbing to the support surface include phenolic hydroxyl groups, carboxyl groups, -PO3H2, -OPO3H2, -CONHSO2-, -SONHSO2-, and -COCH2COCH3. Preferred hydrophilic groups include sulfonic groups or salts thereof, and salts of carboxyl groups. Preferred crosslinking groups include acryloyl groups, methacryloyl groups, acrylamide groups, methacrylamide groups, and allyl groups.

[0756] The polymer may have a crosslinkable group introduced by forming a salt between a polar substituent of the polymer and a compound having a substituent having a charge opposite to that of the polar substituent and an ethylenically unsaturated bond, and may further be copolymerized with monomers other than the above, preferably hydrophilic monomers.

[0757] Specifically, preferably enumerate the phosphorus compound with olefinic double bond reactive group of writing down in the silane coupling agent with the olefinic double bond reactive group that can addition polymerization in Japanese Unexamined Patent Publication No. 10-282679 communique, Japanese Unexamined Patent Publication No. 2-304441 communique. Also can preferably use the low molecule or the macromolecular compound with crosslinking group (being preferably olefinic unsaturated bond group) of writing down in each communique of Japanese Unexamined Patent Publication No. 2005-238816, Japanese Unexamined Patent Publication No. 2005-125749, Japanese Unexamined Patent Publication No. 2006-239867, Japanese Unexamined Patent Publication No. 2006-215263, with the interactive functional group of support surface and hydrophilic group.

[0758] More preferred compounds include polymers having an adsorbable group adsorbable on the surface of a support, a hydrophilic group, and a crosslinkable group, as described in Japanese Patent Application Laid-Open Nos. 2005-125749 and 2006-188038.

[0759] The content of the ethylenically unsaturated bond group in the polymer used for the primer layer is preferably 0.1 mmol to 10.0 mmol, more preferably 0.2 mmol to 5.5 mmol per 1 g of the polymer.

[0760] The weight average molecular weight (Mw) of the polymer used in the primer layer is preferably 5,000 or more, more preferably 10,000 to 300,000.

[0761] 〔Hydrophilic compounds〕

[0762] From the viewpoint of developability, the undercoat layer preferably contains a hydrophilic compound.

[0763] The hydrophilic compound is not particularly limited, and a known hydrophilic compound used in a primer layer can be used.

[0764] Preferred hydrophilic compounds include phosphonic acids having an amino group such as carboxymethyl cellulose and dextrin, organic phosphonic acid, organic phosphoric acid, organic phosphinic acid, amino acids, and hydrochlorides of amines having a hydroxyl group.

[0765] In addition, as hydrophilic compounds, preferred examples include compounds having an amino group or a functional group having polymerization inhibition ability and a group that interacts with the surface of the support (for example, 1,4-diazabicyclo[2.2.2]octane (DABCO), 2,3,5,6-tetrahydroxy-p-benzoquinone, chloranil, sulfophthalic acid, ethylenediaminetetraacetic acid (EDTA) or its salts, hydroxyethylethylenediaminetriacetic acid or its salts, dihydroxyethylethylenediaminediacetic acid or its salts, hydroxyethyliminodiacetic acid, etc. or its salts, etc.).

[0766] As the hydrophilic compound, from the viewpoint of scratch staining inhibition, it is preferred to contain a hydroxycarboxylic acid or a salt thereof.

[0767] Furthermore, from the perspective of scratch stain suppression, a hydrophilic compound, preferably a hydroxycarboxylic acid or a salt thereof, is preferably contained in the layer on the aluminum support. Furthermore, the layer on the aluminum support is preferably located on the side where the image recording layer is formed, and is preferably in contact with the aluminum support.

[0768] As the layer on the aluminum support, preferably, the layer in contact with the aluminum support is a primer layer or an image recording layer. In addition, a layer other than the layer in contact with the aluminum support, such as the outermost layer or the image recording layer, may contain a hydrophilic compound, preferably a hydroxycarboxylic acid or a salt thereof.

[0769] In the lithographic printing plate precursor according to the present invention, the image recording layer preferably contains a hydroxycarboxylic acid or a salt thereof from the viewpoint of scratch staining inhibition.

[0770] Furthermore, in the lithographic printing plate precursor according to the present invention, a method in which the surface of the image-recording layer side of the aluminum support is surface-treated with a composition (e.g., an aqueous solution, etc.) containing at least a hydroxycarboxylic acid or a salt thereof is also preferred. In this method, the treated hydroxycarboxylic acid or salt thereof can be at least partially detected as contained in a layer (e.g., an image-recording layer or an undercoat layer) on the image-recording layer side in contact with the aluminum support.

[0771] By including a hydroxycarboxylic acid or a salt thereof in a layer on the image recording layer side that contacts the aluminum support, such as a primer layer, the surface on the image recording layer side of the aluminum support can be hydrophilized, and the contact angle with water on the surface on the image recording layer side of the aluminum support based on an aerial water drop method can be easily set to 110° or less, resulting in excellent scratch contamination inhibition.

[0772] Hydroxycarboxylic acid is a general term for organic compounds having one or more carboxyl groups and one or more hydroxyl groups in one molecule, and is also called hydroxy acid, oxyacid, hydroxycarboxylic acid, or alkyd acid (see Iwanami Physical and Chemical Dictionary, 5th edition, published by Iwanami Shoten (1998)).

[0773] The hydroxycarboxylic acid or a salt thereof is preferably represented by the following formula (HC).

[0774] Formula (HC): R HC (OH) mhc (COOM HC ) nhc

[0775] In formula (HC), R HC Represents an organic group with MHC+NHC valence, M HC Each independently represents a hydrogen atom, an alkali metal or an onium, and mhc and nhc each independently represent an integer greater than or equal to 1. When n is greater than or equal to 2, M may be the same or different.

[0776] In formula (HC), as R HC The organic group with MHC+NHC valence represented by includes a hydrocarbon group with MHC+NHC valence, etc. The hydrocarbon group may have a substituent and / or a linking group.

[0777] Examples of the hydrocarbon group include groups with MHC+NHC valences derived from aliphatic hydrocarbons, such as alkylene, alkanetriyl, alkanetetrayl, alkanepentayl, alkenylene, alkenetriyl, alkenetetrayl, alkenepentayl, alkynylene, alkynetriyl, alkynetetrayl, alkynepentayl, and the like; and groups with MHC+NHC valences derived from aromatic hydrocarbons, such as arylene, arenetriyl, arenetetrayl, arenepentayl, and the like. Examples of the substituent include alkyl, alkenyl, alkynyl, aralkyl, and aryl groups. Specific examples of the substituent include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, 2-norbornyl, methoxymethyl, methoxyethoxyethyl, allyloxymethyl, phenoxymethyl, acetoxymethyl, benzoyloxy Examples include methyl, benzyl, phenethyl, α-methylbenzyl, 1-methyl-1-phenethyl, p-methylbenzyl, cinnamyl, allyl, 1-propenylmethyl, 2-butenyl, 2-methylallyl, 2-methylpropenylmethyl, 2-propynyl, 2-butynyl, 3-butynyl, phenyl, biphenyl, naphthyl, tolyl, xylyl, mesityl, cumenyl, methoxyphenyl, ethoxyphenyl, phenoxyphenyl, acetoxyphenyl, benzoyloxyphenyl, methoxycarbonylphenyl, ethoxycarbonylphenyl, and phenoxycarbonylphenyl. The linking group is composed of at least one atom selected from hydrogen, carbon, oxygen, nitrogen, sulfur, and halogen atoms, and preferably has 1 to 50 atoms. Specifically, examples include alkylene, substituted alkylene, arylene, and substituted arylene groups, and may have a structure in which a plurality of these divalent groups are linked by amide, ether, urethane, urea, and ester bonds.

[0778] As M HC Examples of the alkali metal represented by include lithium, sodium, potassium, and the like, with sodium being particularly preferred. Examples of the onium include ammonium, phosphonium, and sulfonium, with ammonium being particularly preferred.

[0779] Furthermore, from the perspective of scratch contamination suppression, M HC An alkali metal or onium is preferred, and an alkali metal is more preferred.

[0780] The total number of MHCs and NHCs is preferably 3 or more, more preferably 3 to 8, and even more preferably 4 to 6.

[0781] The molecular weight of the hydroxycarboxylic acid or its salt is preferably 600 or less, more preferably 500 or less, and particularly preferably 300 or less. Furthermore, the molecular weight is preferably 76 or more.

[0782] Specific examples of the hydroxycarboxylic acids or the hydroxycarboxylic acids constituting the salts thereof include gluconic acid, glycolic acid, lactic acid, tartronic acid, hydroxybutyric acid (2-hydroxybutyric acid, 3-hydroxybutyric acid, γ-hydroxybutyric acid, etc.), malic acid, tartaric acid, citramalic acid, citric acid, isocitric acid, leucine, mevalonic acid, pantoic acid, ricinoleic acid, ricinoleic acid, hydroxyethyl ester, quinic acid, shikimic acid, monohydroxybenzoic acid derivatives (salicylic acid, lignoceric acid (high water content), linalool, ... Salicylic acid, hydroxy(methyl)benzoic acid), vanillic acid, syringic acid, etc.), dihydroxybenzoic acid derivatives (pyrocatechuic acid, dihydroxybenzoic acid, protocatechuic acid, gentisic acid, lysine acid, etc.), trihydroxybenzoic acid derivatives (gallic acid, etc.), phenylacetic acid derivatives (mandelic acid, benzilic acid, atrolactic acid, etc.), hydrocinnamic acid derivatives (o-hydroxyphenylpropionic acid, phloric acid, coumaric acid, umbelliferyl acid, caffeic acid, ferulic acid, sinapic acid, hydroxyethyl ester, carminic acid, etc.), etc.

[0783] Among these, the hydroxycarboxylic acid or the hydroxycarboxylic acid constituting the salt of the hydroxycarboxylic acid is preferably a compound having two or more hydroxyl groups, more preferably a compound having three or more hydroxyl groups, further preferably a compound having five or more hydroxyl groups, and particularly preferably a compound having 5 to 8 hydroxyl groups, from the viewpoint of scratch stain inhibition.

[0784] Furthermore, as the compound having one carboxyl group and two or more hydroxyl groups, gluconic acid or shikimic acid is preferred.

[0785] As the compound having two or more carboxyl groups and one hydroxyl group, citric acid or malic acid is preferred.

[0786] As the compound having two or more carboxyl groups and two or more hydroxyl groups, tartaric acid is preferred.

[0787] Among them, gluconic acid is particularly preferred as the hydroxycarboxylic acid.

[0788] The hydrophilic compound may be used alone or in combination of two or more.

[0789] When the primer layer contains a hydrophilic compound (preferably a hydroxycarboxylic acid or a salt thereof), the content of the hydrophilic compound (preferably a hydroxycarboxylic acid or a salt thereof) is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 40% by mass, and particularly preferably 1.0% by mass to 30% by mass, relative to the total mass of the primer layer.

[0790] The undercoat layer may contain, in addition to the above-mentioned undercoat layer compound, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, and the like in order to prevent staining over time.

[0791] The undercoat layer is formed by dissolving the necessary components described above in a known solvent to prepare a coating solution, applying the coating solution on a support by a known method, and drying the solution.

[0792] The coating amount (solid content) of the primer layer is preferably 0.1 mg / m 2 ~300 mg / m 2 , more preferably 5 mg / m 2 ~200 mg / m 2 .

[0793] The lithographic printing plate precursor according to the present invention may have other layers in addition to the above-mentioned layers.

[0794] The other layers are not particularly limited and may be known layers. For example, a back coat layer may be provided on the side of the support opposite to the image recording layer side, as needed.

[0795] Method for producing lithographic printing plate precursor

[0796] The lithographic printing plate precursor according to the present invention is preferably produced by a production method comprising forming an image recording layer on a support by the above-described method and forming an outermost layer on the formed image recording layer by the following method.

[0797] The process for forming the outermost layer is the method for forming the outermost layer already described, that is, a process for forming the outermost layer by coating a coating liquid having a solid content concentration of 5% to 30% by mass on the image recording layer formed on the support, and drying the obtained coating film at 70°C to 200°C under drying conditions of 5 seconds to 30 seconds.

[0798] The details of the process of forming the outermost layer are described in the section "Method for forming the outermost layer" and are therefore omitted here.

[0799] According to this method for producing a lithographic printing plate precursor, a lithographic printing plate precursor having a decomposition rate of an infrared absorber by ozone exposure of 50% or less can be easily obtained.

[0800] Method for producing lithographic printing plates and lithographic printing methods

[0801] A lithographic printing plate can be produced by subjecting the lithographic printing plate precursor of the present invention to imagewise exposure and development treatment.

[0802] The method for producing a lithographic printing plate involved in the present invention preferably includes: a process of exposing the lithographic printing plate precursor involved in the present invention to an image state (hereinafter also referred to as the "exposure process"); and a process of supplying at least one selected from printing ink and fountain solution on a printing press to remove the image recording layer of the non-image part (hereinafter also referred to as the "on-press development process").

[0803] The lithographic printing method involved in the present invention preferably includes: a process of exposing the lithographic printing plate precursor involved in the present invention into an image shape (exposure process); a process of supplying at least one selected from printing ink and fountain solution to remove the image recording layer of the non-image part on the printing press to produce a lithographic printing plate (on-press development process); and a process of printing using the obtained lithographic printing plate (hereinafter also referred to as "printing process").

[0804] Hereinafter, the preferred embodiment of each step of the method for producing a lithographic printing plate and the lithographic printing method according to the present invention will be described in order. The lithographic printing plate precursor according to the present invention can also be developed with a developer.

[0805] The exposure process and the on-press development process in the method for producing a lithographic printing plate are described below. However, the exposure process in the method for producing a lithographic printing plate involved in the present invention is the same process as the exposure process in the lithographic printing method involved in the present invention, and the on-press development process in the method for producing a lithographic printing plate involved in the present invention is the same process as the on-press development process in the lithographic printing method involved in the present invention.

[0806] <Exposure Process>

[0807] The method for producing a lithographic printing plate according to the present invention preferably includes an exposure step of exposing the lithographic printing plate precursor according to the present invention in an imagewise manner to form exposed and unexposed areas. The lithographic printing plate precursor according to the present invention is preferably exposed in an imagewise manner by laser exposure using a transparent original image having a line image, a halftone dot image, or the like, or by laser beam scanning based on digital data.

[0808] A light source with a wavelength of 750 nm to 1,400 nm is preferably used. Solid-state lasers and semiconductor lasers that radiate infrared light are preferred as light sources with a wavelength of 750 nm to 1,400 nm. For infrared lasers, the output power is preferably 100 mW or higher, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy is preferably 10 mJ / cm 2 ~300mJ / cm 2 Furthermore, in order to shorten the exposure time, it is preferable to use a multi-beam laser device. The exposure mechanism may be any of an inner drum method, an outer drum method, and a flatbed method.

[0809] Image exposure can be performed by a conventional method using a plate-making machine, etc. In the case of on-press development, the lithographic printing plate precursor can be mounted on a printing press and then image exposure can be performed on the printing press.

[0810] <On-press development process>

[0811] The method for producing a lithographic printing plate according to the present invention preferably includes an on-press development step of supplying at least one selected from printing ink and fountain solution on a printing press to remove non-image areas of the image recording layer.

[0812] The on-press development method is described below.

[0813] [On-press development method]

[0814] In the on-press development method, the image-exposed lithographic printing plate precursor is preferably supplied with an oil-based ink and an aqueous component on a printing press, and the image recording layer in the non-image area is removed to produce a lithographic printing plate.

[0815] That is, if after the lithographic printing plate precursor is subjected to image exposure, it is directly mounted on a printing press without any development treatment, or after the lithographic printing plate precursor is mounted on a printing press, image exposure is performed on the printing press, and then an oil-based ink and an aqueous component are supplied and printing is performed, then in the initial stage of printing, in the non-image area, the image recording layer that has not been solidified by the supplied oil-based ink and aqueous component or both is dissolved or dispersed and removed, thereby exposing the hydrophilic surface to this part. On the other hand, in the exposure area, the image recording layer solidified by exposure forms an oil-based ink receiving area with an oleophilic surface. The compound initially supplied to the plate surface can be an oil-based ink or an aqueous component, but from the perspective of preventing contamination by the components of the image recording layer from which the aqueous component has been removed, it is preferred to initially supply an oil-based ink. In this way, the lithographic printing plate precursor is developed on the printing press and used directly in multiple printings. As the oil-based ink and aqueous component, it is preferred to use conventional lithographic printing ink and fountain solution.

[0816] As the laser light source for image-wise exposure of the lithographic printing plate precursor according to the present invention, a wavelength of 300 nm to 450 nm or 750 nm to 1,400 nm is preferably used. In the case of a 300 nm to 450 nm light source, it is preferable to use a lithographic printing plate precursor containing a sensitizing dye having maximum absorption in this wavelength region in the image recording layer. For a 750 nm to 1,400 nm light source, the aforementioned light sources are preferably used. As a 300 nm to 450 nm light source, a semiconductor laser is preferably used.

[0817] <Printing process>

[0818] The planographic printing method according to the present invention includes a printing step of supplying printing ink to a planographic printing plate and printing a recording medium.

[0819] There are no particular limitations on the printing ink, and various known inks can be used as needed. Preferred printing inks include oil-based inks and ultraviolet curable inks (UV inks).

[0820] Furthermore, during the printing step, a fountain solution may be supplied as needed.

[0821] Furthermore, the printing process does not need to stop the printing press, but can be continued during the on-press development process.

[0822] The recording medium is not particularly limited, and a known recording medium can be used as needed.

[0823] In the method for producing a lithographic printing plate from a lithographic printing plate precursor and the lithographic printing method of the present invention, the entire surface of the lithographic printing plate precursor can be heated as needed before, during, or between exposure and development. This heating can promote 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 performed under mild conditions of 150°C or less. This prevents problems such as solidification of non-image areas. Heating after development is preferably performed under very strong conditions, preferably within the range of 100°C to 500°C. Within this range, sufficient image enhancement can be achieved, and problems such as degradation of the support and thermal decomposition of the image area can be suppressed.

[0824] Example

[0825] The present invention will be described in detail below by way of examples, but the present invention is not limited thereto. In addition, in the present examples, "%" and "parts" refer to "mass %" and "mass parts," respectively, unless otherwise specified. In addition, in polymer compounds, except for those specifically specified, molecular weights are weight-average molecular weights (Mw), and the ratios of structural repeating units are molar percentages. Furthermore, weight-average molecular weights (Mw) are values ​​measured as polystyrene equivalents based on gel permeation chromatography (GPC).

[0826] <Preparation of Support Body>

[0827] (Production of Support Body (1))

[0828] A 0.3 mm thick aluminum alloy plate of material 1S was subjected to mechanical roughening (brush method) (Aa) described in paragraph 0126 of JP-A-2012-158022 to desmearing in an acidic aqueous solution (Ai) described in paragraph 0134.

[0829] Next, the treatment conditions of the first-stage anodizing treatment (Aj) described in paragraph 0135 of Japanese Patent Application Laid-Open No. 2012-158022 to the third-stage anodizing treatment (Am) described in paragraph 0138 are appropriately adjusted to form an anodic oxide film, which serves as a support (1).

[0830] In addition, water washing was performed between all treatment steps, and drainage was performed using nip rollers after the water washing.

[0831] The details of the obtained support body (1) are summarized.

[0832] Support (1): L on the surface of the microporous anodic oxide film * a * b * Lightness L in the color system * The value is: 83, the average diameter of the large-diameter pores in the micropores at the oxide film surface is 35nm (depth is 100nm), the average diameter of the small-diameter pores in the micropores at the connecting position is 10nm (depth is 1,000nm), and the ratio of the depth of the large-diameter pores to the average diameter of the large-diameter pores is 2.9

[0833] (Production of Support Body (2))

[0834] (a) Alkali etching treatment

[0835] The aluminum plate was etched by spraying a caustic soda aqueous solution with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at a temperature of 70°C. The plate was then rinsed with water using a spray. The surface was then electrochemically roughened to a concentration of 5 g / m2 of aluminum dissolved thereon. 2 .

[0836] (b) Decontamination treatment using an acidic aqueous solution (first decontamination treatment)

[0837] Next, decontamination treatment was performed using an acidic aqueous solution. A 150 g / L sulfuric acid solution was used. The solution temperature was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate using a sprayer for 3 seconds. The plate was then rinsed with water.

[0838] (c) Electrochemical roughening treatment

[0839] Next, electrochemical roughening treatment was performed using an electrolyte solution with a hydrochloric acid concentration of 14 g / L, an aluminum ion concentration of 13 g / L, and a sulfuric acid concentration of 3 g / L, with alternating current. The electrolyte temperature was 30° C. Aluminum chloride was added to adjust the aluminum ion concentration.

[0840] The waveform of the AC current is a sine wave with symmetrical positive and negative waveforms, a frequency of 50 Hz, a 1:1 ratio between the anode reaction time and the cathode reaction time in one cycle of the AC current, and a current density of 75 A / dm2 based on the peak current of the AC current waveform. 2 The total amount of electricity consumed by the aluminum plate in the anode reaction is 450C / dm 2 For electrolysis, the current was applied at 112.5C / dm 2 This was done in four steps. A carbon electrode was used as the counter electrode for the aluminum plate. The aluminum plate was then rinsed with water.

[0841] (d) Decontamination treatment using an acidic aqueous solution

[0842] Next, a decontamination treatment was performed using an acidic aqueous solution. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate using a sprayer for 3 seconds. The acidic aqueous solution used for decontamination had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The solution temperature was 30°C.

[0843] (e) Anodizing

[0844] Anodizing was performed in a sulfuric acid solution using a direct current electrolysis anodizing device to obtain a 3.6 g / m 2 The amount of oxide film.

[0845] In this way, the support body (2) was manufactured.

[0846] (Production of Support Body (3))

[0847] Hydro 1052 aluminum alloy strips or sheets with a thickness of 0.28 mm (available from Norsk Hydro ASA, Norway) were used as aluminum-containing supports.

[0848] Both pre-etching and post-etching steps were performed using an alkaline solution under known conditions. Roughening (or graining) was performed electrochemically in a hydrochloric acid solution at approximately 23°C to achieve a calculated average roughness (Ra) of 0.5 μm on the flat surface of the aluminum support. These treatment steps were performed in a continuous process on a typical production line for producing lithographic printing plate precursors.

[0849] Next, the obtained grained and etched aluminum-containing support was washed with water, dried, and cut into individual grained and etched aluminum-containing sheets.

[0850] Next, each sheet was anodized twice, with each anodizing bath containing approximately 100 liters of anodizing solution. The first anodizing conditions were an electrolyte concentration of 175 g / liter, a temperature of 60°C, and a current density of 5.8 A / dm 2 The second anodizing condition was an electrolyte concentration of 280 g / liter, a temperature of 23°C, and a current density of 10 A / dm 2 The first anodizing process for forming the outer aluminum oxide layer was performed using phosphoric acid as the electrolyte, and the second anodizing process for forming the inner aluminum oxide layer was performed using sulfuric acid as the electrolyte.

[0851] In this way, the support body (3) was manufactured.

[0852] (Production of Support Body (4))

[0853] To remove rolling oil from the surface of a 0.3 mm thick aluminum plate (material: JIS A 1050), a degreasing treatment was performed using a 10 mass % sodium aluminate aqueous solution at 50°C for 30 seconds, and then a brush with three bundles of nylon bristles with a bristle diameter of 0.3 mm and a pumice-water suspension with a median particle size of 25 μm (specific gravity 1.1 g / cm 3 ) to grain the aluminum surface and then clean it with water. The plate was immersed in a 25% by mass sodium hydroxide aqueous solution at 45°C for 9 seconds to etch it, and then rinsed with water. It was then immersed in a 20% by mass nitric acid aqueous solution at 60°C for 20 seconds and rinsed with water. The amount of etching on the frosted surface at this time was about 3g / m 2 .

[0854] Next, electrochemical roughening treatment was continuously performed using an AC voltage of 60 Hz. The electrolyte at this time was a 1% by mass aqueous solution of nitric acid (containing 0.5% by mass of aluminum ions), and the liquid temperature was 50°C. Regarding the AC power waveform, a trapezoidal rectangular wave AC with a time TP of 0.8 msec, a duty ratio of 1:1, and a current value from zero to peak was used, and electrochemical roughening treatment was performed using a carbon electrode as a counter electrode. Ferrite was used as an auxiliary anode. The current density was 30 A / dm 2 , so that 5% of the current flowing from the power supply is diverted to the auxiliary anode. The amount of electricity in nitric acid electrolysis is 175C / dm when the aluminum plate is the anode. 2 Then, a spray-based water wash was performed.

[0855] Next, a 0.5 mass % aqueous solution of hydrochloric acid (containing 0.5 mass % of aluminum ions) and an electrolyte at a temperature of 50°C were used, and the charge was 50 C / dm when the aluminum plate was the anode. 2 Under the conditions of , electrochemical roughening treatment was carried out in the same way as nitric acid electrolysis, and then spray water washing was performed.

[0856] Next, 15 mass % sulfuric acid (containing 0.5 mass % aluminum ions) was used as an electrolyte on the plate at a current density of 15 A / dm 2 Set 2.5g / m 2 After the DC anodic oxidation film was removed, the support A was obtained by washing with water and drying.

[0857] Then, in order to ensure the hydrophilicity of the non-image area, the support A was subjected to silicate treatment at 60°C for 10 seconds using a 2.5% by mass sodium silicate No. 3 aqueous solution, and then washed with water to obtain a support (4). The adhesion amount of Si was 10 mg / m 2 The centerline average roughness (Ra) of the support (4) was measured using a needle having a diameter of 2 μm and was found to be 0.51 μm.

[0858] <Preparation of Undercoat Layer Coating Liquid>

[0859] (Preparation of Undercoat Layer Coating Liquid (1))

[0860] An undercoat layer coating liquid (1) having the following composition was prepared.

[0861] · Undercoat compound (hereinafter referred to as (P-1), 11% aqueous solution): 0.10502 parts

[0862] Sodium gluconate: 0.07000 parts

[0863] Surfactant (EMALEX (registered trademark) 710, manufactured by NIHON EMULSION Co., Ltd.): 0.00159 parts

[0864] Preservative (Biohope L, K.I Chemical Industry Co., LTD.): 0.00149 parts

[0865] Water: 2.87190 parts

[0866] [Chemical Formula 42]

[0867]

[0868] (Preparation of Undercoat Layer Coating Liquid (2))

[0869] An undercoat layer coating liquid (2) having the following composition was prepared.

[0870] · Undercoat compound (the above (P-1), 11% aqueous solution): 0.10502 parts

[0871] · Hydroxyethyl diiminodiacetic acid: 0.01470 parts

[0872] Sodium EDTA: 0.06575 parts

[0873] Surfactant (EMALEX (registered trademark) 710, manufactured by NIHON EMULSION Co., Ltd.): 0.00159 parts

[0874] Preservative (Biohope L, K.I Chemical Industry Co., LTD.): 0.00149 parts

[0875] Water: 2.86144 parts

[0876] (Preparation of Undercoat Layer Coating Liquid (3))

[0877] An undercoat layer coating liquid (3) having the following composition was prepared.

[0878] · Compound for primer layer (hereinafter referred to as (P-2)): 0.18 parts

[0879] · Hydroxyethyliminodiacetic acid: 0.10 parts

[0880] Methanol: 55.24 parts

[0881] Water: 6.15 parts

[0882] [Chemical Formula 43]

[0883]

[0884] <Preparation of Image Recording Layer Coating Liquid>

[0885] (Preparation of Image Recording Layer Coating Liquid (1-1))

[0886] An image recording layer coating liquid (1-1) was prepared by mixing a mixed liquid in which components other than the microgel liquid 1 described below were mixed with the microgel liquid 1 described below and stirring the mixture before coating.

[0887] Infrared absorber IR-1 (structure shown below, HOMO: -5.35 eV, LUMO: -3.75 eV): 0.02000 parts

[0888] Color developer S-1 (structure shown below): 0.02500 parts

[0889] Electron-accepting polymerization initiator Int-1 (structure shown below, HOMO: -6.70 eV, LUMO: -3.08 eV): 0.11000 parts

[0890] Electron-donating polymerization initiator TPB (structure shown below, HOMO: -5.90 eV): 0.02500 parts

[0891] Polymerizable compound M-1 (obtained by the following synthesis method): 0.27500 parts

[0892] Anionic surfactant A-1 (structure shown below): 0.00600 parts

[0893] Fluorine-based surfactant W-1 (structure shown below): 0.00416 parts

[0894] 2-Butanone: 4.3602 parts

[0895] 1-Methoxy-2-propanol: 4.4852 parts

[0896] Methanol: 2.2838 parts

[0897] Microgel solution 1 (obtained by the following preparation method): 2.3256 parts

[0898] (Preparation of Image Recording Layer Coating Liquid (1-2))

[0899] An image-recording layer coating liquid (1-2) was prepared in the same manner as in the preparation of the image-recording layer coating liquid (1-1), except that developer S-3 (structure shown below) was used instead of developer S-1.

[0900] (Preparation of Image Recording Layer Coating Liquid (1-3))

[0901] An image-recording layer coating liquid (1-3) was prepared in the same manner as in the preparation of the image-recording layer coating liquid (1-1), except that developer S-4 (structure shown below) was used instead of developer S-1.

[0902] (Preparation of Image Recording Layer Coating Liquid (2-1))

[0903] An image recording layer coating liquid (2-1) was prepared by mixing a mixed liquid in which components other than the microgel liquid 2 described below were mixed with the microgel liquid 2 described below and stirring the mixture before coating.

[0904] Infrared absorber IR-1 (structure shown below, HOMO: -5.35 eV, LUMO: -3.75 eV): 0.00600 parts

[0905] Infrared absorber IR-2 (structure shown below, HOMO: -5.31 eV, LUMO: -3.78 eV): 0.0200 parts

[0906] Color developer S-1 (structure shown below): 0.02500 parts

[0907] Electron-accepting polymerization initiator Tnt-1 (structure shown below, HOMO: -6.70 eV, LUMO: -3.08 eV): 0.11000 parts

[0908] Electron-donating polymerization initiator TPB (structure shown below, HOMO: -5.90 eV): 0.02500 parts

[0909] Polymerizable compound M-1 (obtained by the following synthesis method): 0.27500 parts

[0910] Anionic surfactant A-1 (structure shown below): 0.09000 parts

[0911] Fluorine-based surfactant W-1 (structure shown below): 0.00416 parts

[0912] 2-Butanone: 4.9200 parts

[0913] 1-Methoxy-2-propanol: 3.1000 parts

[0914] Methanol: 2.7900 parts

[0915] Microgel solution 2 (obtained by the following preparation method): 2.90700 parts

[0916] (Preparation of Image Recording Layer Coating Liquid (2-2))

[0917] An image-recording layer coating liquid (2-2) was prepared in the same manner as in the preparation of the image-recording layer coating liquid (2-1), except that developer S-3 (structure shown below) was used instead of developer S-1.

[0918] (Preparation of Image Recording Layer Coating Liquid (2-3))

[0919] An image-recording layer coating liquid (2-3) was prepared in the same manner as in the preparation of the image-recording layer coating liquid (2-1), except that developer S-4 (structure shown below) was used instead of developer S-1.

[0920] (Preparation of Image Recording Layer Coating Liquid (3))

[0921] An image-recording layer coating liquid (3) was prepared by mixing the following components.

[0922] Electron-accepting polymerization initiator Int-2 (structure shown below, HOMO: -6.96 eV, LUMO: -3.18 eV): 0.060 parts

[0923] Infrared absorber IR-3 (structure shown below, HOMO: -5.43 eV, LUMO: -3.95 eV): 0.026 parts

[0924] Electron-donating polymerization initiator TPB (structure shown below, HOMO: -5.90 eV): 0.050 parts

[0925] Polymerizable compound M-2 (structure shown below): 0.250 parts

[0926] Polymerizable compound M-3 (structure shown below): 0.250 parts

[0927] Binder polymer BP-1 (the following structure, S-LEC BX-5 (Z), SEKISUI CHEMICAL CO., LTD.: 0.150 parts

[0928] 1-Methoxy-2-propanol: 4.988 parts

[0929] 2-Butanone: 9.262 parts

[0930] (Preparation of Image Recording Layer Coating Liquid (4))

[0931] An image-recording layer coating liquid (4) was prepared by mixing the following components.

[0932] Electron-accepting polymerization initiator Int-3 (structure shown below, HOMO: -7.34 eV, LUMO: -3.26 eV): 0.041 parts

[0933] Infrared absorber IR-4 (structure shown below, HOMO: -5.42 eV, LUMO: -3.82 eV): 0.027 parts

[0934] Infrared absorber IR-5 (structure shown below, HOMO: -5.43 eV, LUMO: -3.84 eV): 0.015 parts

[0935] Polymerizable compound M-4 (structure shown below): 0.100 parts

[0936] Polymerizable compound M-5 (structure shown below): 0.096 parts

[0937] Polymerizable compound M-6 (structure shown below): 0.096 parts

[0938] Polymer particles PP-1 (particles containing a polymer having the following structure, average particle size 100 μm): 0.300 parts

[0939] Color developer S-2 (structure shown below): 0.041 parts

[0940] Hydroxypropyl cellulose: 0.030 parts

[0941] n-Propanol: 5.168 parts

[0942] 2-Butanone: 6.460 parts

[0943] 1-Methoxy-2-propanol: 1.615 parts

[0944] Methanol: 2.907 parts

[0945] The details of the components used in the above-mentioned and later-described image recording layer coating solutions are as follows.

[0946] In BP-1, l was 72 mol%, m was 1 mol%, n was 27 mol%, and the weight-average molecular weight was 130,000.

[0947] In PP-1, n is 40 and the weight average molecular weight is 90,000.

[0948] Int-3 is a mixture of compounds formed of each of the following two iodonium cation structures and the following counter anion (ie, tetraphenylborate ion).

[0949] [Chemical Formula 44]

[0950]

[0951] [Chemical Formula 45]

[0952]

[0953] [Chemical Formula 46]

[0954]

[0955] [Chemical Formula 47]

[0956]

[0957] [Chemical Formula 48]

[0958]

[0959] [Synthesis of polymerizable compound M-1]

[0960] A mixed solution of 4.7 parts by mass of Takenate D-160N (polyisocyanate-trimethylolpropane adduct, manufactured by Mitsui Chemicals, Inc.), ARONIX M-403 (manufactured by TOAGOSEI CO., LTD.) (the NCO value of Takenate D-160N and the hydroxyl value of ARONIX M-403 being in a ratio of 1:1), 0.02 parts by mass of tert-butylbenzoquinone, and 11.5 parts by mass of methyl ethyl ketone was heated to 65°C. 0.11 parts by mass of NEOSTANN U-600 (a bismuth-based polycondensation catalyst, manufactured by NITTO KASEI CO., LTD.) was added to the reaction solution, and the mixture was heated at the same temperature for 4 hours. The reaction solution was cooled to room temperature (25°C), and methyl ethyl ketone was added to synthesize a urethane acrylate solution having a solid content of 50% by mass.

[0961] The urethane acrylate solution was then subjected to molecular weight fractionation using a reusable GPC (equipment: LC908-C60, columns: JAIGEL-1H-40 and 2H-40 (manufactured by Japan Analytical Industry)) with tetrahydrofuran (THF) as the eluent. The weight-average molecular weight of the obtained polymerizable compound M-1 was 20,000.

[0962] [Preparation of microgel solution 1]

[0963] -Preparation of polyisocyanate compounds-

[0964] To a suspension of 17.78 parts (80 molar equivalents) of isophorone diisocyanate and 7.35 parts (20 molar equivalents) of the following polyphenol compound (1) in ethyl acetate (25.31 parts) was added 0.043 parts of bismuth tris(2-ethylhexanoate) (NEOSTANN U-600, manufactured by NITTO KASEI CO., LTD.), followed by stirring. When heat generation was suppressed, 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 polyisocyanate compound (1).

[0965] [Chemical Formula 49]

[0966]

[0967] - Preparation of microgels -

[0968] The following oil phase components and aqueous phase components 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, followed by the addition of 5.20 g of a 10% by mass aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene-octanoate (U-CAT SA102, manufactured by San-Apro Ltd.). The mixture was 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 mass with distilled water to obtain an aqueous dispersion of microgels (i.e., Microgel Solution 1). The average particle size of the microgels, measured by light scattering, was 0.28 μm.

[0969] ~Oil phase ingredients~

[0970] (Component 1) Ethyl acetate: 12.0 parts

[0971] (Component 2) 3.76 parts of an adduct prepared by adding trimethylolpropane (6 mol equivalents) to xylene diisocyanate (18 mol equivalents) and adding mono-terminal methylated polyoxyethylene (1 mol equivalent, number of repeating oxyethylene units: 90) (50% by mass ethyl acetate solution, manufactured by Mitsui Chemicals, Inc.)

[0972] (Component 3) Polyisocyanate compound (1) (as a 50% by mass ethyl acetate solution): 15.0 parts

[0973] (Component 4) 65% by mass ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Company, Inc.): 11.54 parts

[0974] (Component 5) 10% ethyl acetate solution of sulfonate surfactant (PIONIN A-41-C, manufactured by Takemoto Oil & Fat Co., Ltd.): 4.42 parts

[0975] ~Aqueous phase components~

[0976] Distilled water: 46.87 parts

[0977] [Preparation of microgel solution 2]

[0978] -Preparation of oil phase components-

[0979] A polyfunctional isocyanate compound (PM-200: manufactured by Wanhua Chemical Co.): 6.66 g; a 50% by mass ethyl acetate solution of "Takenate (registered trademark) D-116N (an adduct of trimethylolpropane (TMP), meta-xylylenediisocyanate (XDI), and polyethylene glycol monomethyl ether (EO90) (the following structure)" manufactured by Mitsui Chemicals, Inc.): 5.46 g; a 65% by mass ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Company, Inc.): 11.24 g; ethyl acetate: 14.47 g; and PIONIN (registered trademark) A-41-C manufactured by Takemoto Oil & Fat Co., Ltd.: 0.45 g were mixed and stirred at room temperature (25°C) for 15 minutes to obtain an oil phase component.

[0980] [Chemical Formula 50]

[0981]

[0982] -Preparation of aqueous phase components-

[0983] As the aqueous phase component, 47.2 g of distilled water was prepared.

[0984] -Microcapsule formation process-

[0985] The aqueous phase component was added to the oil phase component and mixed, and the obtained mixture was emulsified at 12,000 rpm for 16 minutes using a homogenizer to obtain an emulsion.

[0986] 16.8 g of distilled water was added to the obtained emulsion, and the obtained liquid was stirred at room temperature for 10 minutes.

[0987] The stirred liquid was then heated to 45°C and stirred for 4 hours while maintaining the liquid temperature at 45°C to distill off the ethyl acetate. Subsequently, 5.12 g of a 10% by mass aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene-octanoate (U-CAT SA102, manufactured by San-Apro 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 mass with distilled water to obtain an aqueous dispersion of microgels. The volume average particle size of the microgels, measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by HORIBA, Ltd.), was 165 nm.

[0988] The obtained aqueous dispersion of microgel is referred to as microgel solution 2.

[0989] (Preparation of Image Recording Layer Coating Liquid (5))

[0990] An image recording layer coating liquid (5) was prepared by mixing a mixed liquid in which components other than the microgel liquid 3 described below were mixed with the microgel liquid 3 described below and stirring the mixture before coating.

[0991] Binder polymer BP-2 (structure shown below): 0.240 parts

[0992] Infrared absorber IR-6 (structure shown below, HOMO: -5.38 eV, LUMO: -3.70 eV): 0.030 parts

[0993] Polymerization initiator Int-4 (structure shown below, HOMO: -6.70 eV, LUMO: -3.08 eV): 0.162 parts

[0994] Polymerizable compound: 0.192 parts

[0995] (Tris(acryloyloxyethyl)isocyanurate, NK Ester A-9300, Shin-Nakamura Chemical Co., Ltd.)

[0996] Low molecular weight hydrophilic compound (tris(2-hydroxyethyl)isocyanurate): 0.062 parts

[0997] Low molecular weight hydrophilic compound A-1 (the above structure): 0.050 parts

[0998] Sensitizer C-1 (structure shown below): 0.055 parts

[0999] Sensitizer (benzyl-dimethyl-octylammonium PF6 salt): 0.018 parts

[1000] Sensitizer C-2 (structure shown below, reduced viscosity 44 ml / g): 0.035 parts

[1001] Fluorine-based surfactant W-1 (structure described above): 0.008 parts

[1002] 2-Butanone: 1.091 parts

[1003] 1-Methoxy-2-propanol: 8.609 parts

[1004] Microgel solution 3 (obtained by the following preparation method): 5.065 parts

[1005] The details of the components used in the image recording layer coating liquid (5) are as follows.

[1006] [Chemical Formula 51]

[1007]

[1008] [Preparation of microgel solution 3]

[1009] As the oil phase component, 10 g of an adduct of trimethylolpropane and xylene diisocyanate (TAKENATE D-110N, manufactured by Mitsui Chemicals & SKC Polyurethanes Inc.), 3.15 g of pentaerythritol triacrylate (SR444, manufactured by Nippon Kayaku Co., Ltd.), and 0.1 g of PIONIN A-41C (manufactured by Takemoto Oil & Fat Co., Ltd.) were dissolved in 17 g of ethyl acetate. As the aqueous phase component, 40 g of a 4% by mass aqueous solution of polyvinyl alcohol (PVA-205, manufactured by KURARAY CO., LTD.) was prepared.

[1010] The oil phase and aqueous phase components were mixed and emulsified using a homogenizer at 12,000 rpm for 10 minutes. The resulting emulsion was added to 25 g of distilled water and stirred at room temperature for 30 minutes, followed by stirring at 50°C for 3 hours. The resulting microgel solution was diluted with distilled water to a solids concentration of 15% by mass.

[1011] The average particle size of the microgel was measured by a light scattering method and found to be 0.2 μm.

[1012] Microgel liquid 3 was obtained by mixing 2.640 parts of the microgel liquid obtained in the above manner with 2.425 parts of distilled water.

[1013] <Preparation of outermost coating liquid>

[1014] The components listed in Table 1 below were mixed to obtain outermost layer coating solutions (1) to (27).

[1015]

[1016] The details of the components used in Table 1 are shown below.

[1017] -Water-soluble polymer-

[1018] GOHSENX L-3266: Sulfonic acid-modified polyvinyl alcohol having the following structure, GOHSENX (registered trademark) L-3266 manufactured by Mitsubishi Chemical Corporation

[1019] [Chemical Formula 52]

[1020]

[1021] GOHSENX CKS-50: Sulfonic acid-modified polyvinyl alcohol of the following structure, GOHSENX (registered trademark) CKS-50 manufactured by Mitsubishi Chemical Corporation.

[1022] [Chemical Formula 53]

[1023]

[1024] Water-soluble polymer 1: a polymer having the following structure

[1025] [Chemical Formula 54]

[1026]

[1027] Mowiol 4-88: polyvinyl alcohol particles with a saponification degree of 88 mol%, Mowiol (registered trademark) 4-88 manufactured by Sigma Aldrich

[1028] METOLOSE SM04: methylcellulose (methoxyl substitution degree 1.8), METOLOSE (registered trademark) SM04 manufactured by Shin-Etsu Chemical Co., Ltd.

[1029] METOLOSE SM15: Methylcellulose (methoxyl substitution degree 1.8, high viscosity), METOLOSE (registered trademark) SM15 manufactured by Shin-Etsu Chemical Co., Ltd.

[1030] METOLOSE 60SH 50: Hydroxypropyl methylcellulose (methoxyl substitution degree 1.9), METOLOSE (registered trademark) 60SH 50 manufactured by Shin-Etsu Chemical Co., Ltd.

[1031] CELLOGEN F 5A: Sodium carboxymethylcellulose, CELLOGEN (registered trademark) F5A manufactured by DKS Co. Ltd.

[1032] Penon JE-66: Modified starch, manufactured by NIPPON STARCH CHEMICAL CO., LTD.

[1033] -Hydrophobic polymer-

[1034] Fine Sphere FS-102: Aqueous dispersion of styrene acrylic resin particles having the following structure, with a glass transition temperature (Tg) of 103°C and a softening point of 225°C. Fine Sphere (registered trademark) FS-102 manufactured by Nipponpaint Industrial Coatings Co., Ltd.

[1035] [Chemical Formula 55]

[1036]

[1037] Polymaron 385: A dispersion of styrene acrylic resin, manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD.

[1038] AQUAMAT 263: Oxidized high-density polyethylene wax dispersion, AQUAMAT (registered trademark) 263 manufactured by BYK

[1039] Takeseal PCeco Primer: Emulsion of styrene acrylic resin, manufactured by Takebayashi Chemical Industry Co., Ltd.

[1040] Diofan A50: Aqueous dispersion of polyvinylidene chloride, Diofan (registered trademark) A50 manufactured by Solvin

[1041] Diofan A602: Polyvinylidene chloride dispersion, Diofan (registered trademark) A602 manufactured by Solvin

[1042] -Other ingredients-

[1043] Microgel 2: Microgel 2 described above

[1044] Decomposable infrared absorber 1: Compound with the following structure

[1045] [Chemical Formula 56]

[1046]

[1047] [Examples 1 to 29 and Comparative Examples 1 and 2]

[1048] Lithographic printing plate precursors of Examples 1 to 29 and Comparative Examples 1 and 2 were produced by the following methods.

[1049] On the support described in Table 2, the dry coating amount was 20 mg / m 2 The primer coating liquid described in Table 2 was applied in a manner to form a primer layer.

[1050] Next, the primer layer was coated with a dry coating weight of 1.0 g / m 2 The image recording layer coating liquid described in Table 2 was bar-coated and dried at 120° C. for 40 seconds to form an image recording layer.

[1051] In addition, for the planographic printing plate precursor having no undercoat layer, the support described in Table 2 was coated with a dry coating amount of 1.0 g / m2 under the same conditions as above. 2 The image recording layer coating liquid described in Table 2 was bar-coated to form an image recording layer.

[1052] Then, on the obtained image recording layer, a coating was applied in a dry amount of 0.2 g / m 2 The outermost layer coating liquid described in Table 2 was bar-coated and dried under the drying conditions described in Table 2 to form the outermost layer.

[1053] In this manner, an on-press development type lithographic printing plate precursor was obtained.

[1054] In the obtained on-press development type planographic printing plate precursor, the film thickness of the outermost layer was in the range of 0.005 μm to 2 μm.

[1055] <Evaluation of the original lithographic printing plate>

[1056] 〔Decomposition rate of infrared absorber〕

[1057] For the obtained lithographic printing plate precursor, the decomposition rate of the infrared absorber in the image recording layer was determined by the method described above.

[1058] The results are shown in Table 2.

[1059] [Evaluation of discoloration due to ozone exposure]

[1060] When the decomposition rate of the infrared absorbent was determined as described above, the L values ​​of the samples before ozone exposure were measured using a colorimeter (eXact from X-Rite Inc.). * 、a * 、b * and L of samples after ozone exposure * 、a * 、b * , and according to the obtained L * 、a * and b * The color difference ΔE was calculated using the CIE 1976 color difference calculation formula. Based on the difference in the obtained color difference ΔE values ​​before and after ozone exposure, the discoloration of the lithographic printing plate precursor caused by ozone exposure was evaluated according to the following criteria. The results are shown in Table 2.

[1061] -Evaluation Criteria-

[1062] 10: The difference in color difference ΔE before and after ozone exposure is less than 0.5

[1063] 9: The difference in color difference ΔE before and after ozone exposure is 0.5 or more and less than 1.0

[1064] 8: The difference in color difference ΔE before and after ozone exposure is 1.0 or more and less than 1.5

[1065] 7: The difference in color difference ΔE before and after ozone exposure is 1.5 or more and less than 2.0

[1066] 6: The difference in color difference ΔE before and after ozone exposure is 2.0 or more and less than 2.5

[1067] 5: The difference in color difference ΔE before and after ozone exposure is 2.5 or more and less than 3.0

[1068] 4: The difference in color difference ΔE before and after ozone exposure is 3.0 or more and less than 3.5

[1069] 3: The difference in color difference ΔE before and after ozone exposure is 3.5 or more and less than 4.0

[1070] 2: The difference in color difference ΔE before and after ozone exposure is 4.0 or more and less than 4.5

[1071] 1: The difference in color difference ΔE before and after ozone exposure is 4.5 or more

[1072] 〔Oxygen permeability〕

[1073] The dot area ratio of the obtained lithographic printing plate precursor was calculated by the method described above, and the presence or absence of oxygen permeability was confirmed.

[1074] The results are shown in Table 2.

[1075] [Evaluation of streaky unevenness (banding unevenness)]

[1076] When confirming the oxygen permeability, streak-like unevenness (banding unevenness) was evaluated using the 1000th print based on the lithographic printing plate obtained from the lithographic printing plate precursor having the outermost layer.

[1077] More specifically, the 50% dot pattern portion of the FM screen of the 1000th printed material was observed, and streak-like unevenness (banding unevenness) was evaluated according to the following criteria.

[1078] -standard-

[1079] 5: Unable to visually confirm uneven banding using a 6x magnifying glass

[1080] 4: A slight uneven banding can be confirmed by the naked eye using a 6x magnifying glass

[1081] 3: The uneven banding can be clearly confirmed by the naked eye using a 6x magnifying glass

[1082] 2: A slight uneven band can be confirmed by the naked eye

[1083] 1: Uneven banding can be clearly confirmed with the naked eye

[1084] 〔On-press development〕

[1085] The prepared lithographic printing plate precursor was exposed using a Kodak Magnus 800 Quantum equipped with an infrared semiconductor laser at an output of 27 W, an external drum rotation speed of 450 rpm, and a resolution of 2,400 dpi (equivalent to an irradiation energy of 110 mJ / cm 2 The exposure image includes a solid image and an amplitude modulation screen (Amplitude Modulation Screen) 10% dot image.

[1086] The exposed original plate was mounted on the cylinder of a Heidelberger Druckmaschinen AG SX-74 printing press with a 636 mm x 939 mm plate size without undergoing development. A 100-liter fountain solution circulation tank with a built-in nonwoven filter and temperature control system was connected to the press. 80 liters of 2.0% by mass fountain solution S-Z1 (Fujifilm Corporation) was placed in the circulation system. UV-curable ink, T&K UV OFS K-HS Ink GE-M (T&K TOKA Corporation), was used as the printing ink. After supplying the fountain solution and ink using a standard automatic print start method, printing was performed on 500 sheets of Tokubishi Art paper (continuous capacity: 76.5 kg, Mitsubishi Paper Mills Limited) at a printing speed of 10,000 sheets per hour.

[1087] During printing, the number of sheets required to prevent ink from transferring to non-image areas was measured as on-press developability. The fewer the number, the better the on-press developability. The results are shown in Table 2.

[1088] [Table 2]

[1089]

[1090] As is clear from Table 2, the lithographic printing plate precursors according to Examples suppress discoloration caused by ozone exposure as compared to the lithographic printing plate precursors according to Comparative Examples.

[1091] Furthermore, the lithographic printing plate precursors according to the examples include an outermost layer having oxygen permeability, and therefore, it is considered that streak-like unevenness (banding unevenness) is suppressed.

[1092] [Explanation of symbols]

[1093] 18-aluminum plate, 12a, 12b-aluminum support, 20a, 20b-anodized film, 22a, 22b-micropores, 24-large diameter pores, 26-small diameter pores

[1094] The disclosures of Japanese Patent Application No. 2020-095073 filed on May 29, 2020, and Japanese Patent Application No. 2021-002219 filed on January 8, 2021, are incorporated herein by reference in their entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, or technical standard were specifically and individually set forth by reference.

Claims

1. An on-press developing type lithographic printing plate precursor comprising, in order, a support, an image recording layer, and an outermost layer, The image recording layer contains a polymerization initiator, a polymerizable compound, and an infrared absorber. After being stored in an environment with an ozone concentration of 150 ppb for 8 hours, the decomposition rate of the infrared absorber is 50% or less. The outermost layer comprises any water-soluble polymer selected from polyvinyl alcohol, modified polyvinyl alcohol, poly(meth)acrylamide, copolymers obtained by combining raw monomers of these polymers with other monomers, and polysaccharides.

2. The on-press development type lithographic printing plate precursor according to claim 1, wherein The thickness of the outermost layer is 0.005 μm to 2 μm.

3. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The outermost layer is oxygen permeable.

4. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The outermost layer comprises polysaccharides.

5. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The outermost layer comprises a cellulose derivative having a methoxyl substitution degree of 1 to 2.

6. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The outermost layer also comprises a hydrophobic polymer.

7. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The outermost layer further comprises polymer particles.

8. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The outermost layer contains a decomposable infrared absorber.

9. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The polymerization initiator includes an electron-donating polymerization initiator and an electron-accepting polymerization initiator.

10. The on-press development type lithographic printing plate precursor according to claim 9, wherein The value of HOMO of the infrared absorber minus HOMO of the electron-donating polymerization initiator is 0.70 eV or less.

11. The on-press development type lithographic printing plate precursor according to claim 9, wherein The value of LUMO of the electron-accepting polymerization initiator minus LUMO of the infrared absorber is 0.80 eV or less.

12. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The polymerizable compound includes a polymerizable compound having seven or more functional groups.

13. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The polymerizable compound includes a polymerizable compound having ten or more functional groups.

14. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The image-recording layer further comprises polymer particles.

15. The on-press development type lithographic printing plate precursor according to claim 14, wherein The polymer particles are addition polymerization type polymer particles having hydrophilic groups, The hydrophilic group includes a group represented by the following formula Z, Formula Z: *-QWY In formula Z, Q represents a divalent linking group, W represents a divalent group having a hydrophilic structure or a divalent group having a hydrophobic structure, Y represents a monovalent group having a hydrophilic structure or a monovalent group having a hydrophobic structure, any of W and Y has a hydrophilic structure, and * represents a bonding site with another structure.

16. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The image-recording layer further contains a developer.

17. The on-press development type lithographic printing plate precursor according to claim 16, wherein The color developer is a compound represented by any of the following formulas (Le-1) to (Le-3), In formula (Le-1) to formula (Le-3), ERG each independently represents an electron-donating group, X1 to X4 each independently represents a hydrogen atom, a halogen atom or a dialkylaniline group, and X5 to X 10 Each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 does not exist, when Y2 is N, X4 does not exist, Ra1 represents a hydrogen atom, an alkyl group or an alkoxy group, and Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group.

18. The on-press developing type lithographic printing plate precursor according to claim 16, wherein The developer is a compound represented by the following formula (Le-8): In formula (Le-8), X1 to X4 each independently represent a hydrogen atom, a halogen atom or a dialkylaniline group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 is absent, when Y2 is N, X4 is absent, Rb1 and Rb2 each independently represent an alkyl group, an aryl group or a heteroaryl group, and Rc1 and Rc2 each independently represent an aryl group or a heteroaryl group.

19. The on-press development type lithographic printing plate precursor according to claim 18, wherein The Rc1 and Rc2 are each independently a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position.

20. The on-press development type lithographic printing plate precursor according to claim 16, wherein The developer includes a compound represented by the following formula (Le-10), In formula (Le-10), Ar1 each independently represents an aryl group or a heteroaryl group, and Ar2 each 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.

21. The on-press development type lithographic printing plate precursor according to claim 20, wherein The Ar1s are each independently an aryl group having an electron-donating group or a heteroaryl group having an electron-donating group, and the Ar2s are each independently a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position.

22. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein The support body includes an aluminum plate and an aluminum anodic oxide film disposed on the aluminum plate. The anodic oxide film is located closer to the image recording layer than the aluminum plate. The anodic oxide film has micropores extending in the depth direction from the surface on the image recording layer side. The average diameter of the micropores on the surface of the anodic oxide film is greater than 10 nm and less than 100 nm. The L of the surface of the anodic oxide film on the image recording layer side * a * b * Lightness L in the color system * The value is 70~100.

23. The on-press development type lithographic printing plate precursor according to claim 22, wherein The micropores are composed of a large-diameter pore portion and a small-diameter pore portion, wherein the large-diameter pore portion extends from the surface of the anodic oxide film to a depth of 10 nm to 1000 nm, and the small-diameter pore portion is connected to the bottom of the large-diameter pore portion and extends from the connected position to a depth of 20 nm to 2000 nm. The average diameter of the large-diameter pores on the surface of the anodic oxide film is 15 nm to 100 nm. The average diameter of the small-diameter pores at the communication positions is 13 nm or less.

24. A method for producing a lithographic printing plate, comprising: A step of exposing the on-press developed lithographic printing plate precursor according to any one of claims 1 to 23 to an image shape; and A step of supplying at least one selected from printing ink and fountain solution on a printing press to remove the image recording layer in non-image areas.

25. A lithographic printing method comprising: A step of exposing the on-press developed lithographic printing plate precursor according to any one of claims 1 to 23 to an image shape; A step of supplying at least one selected from printing ink and fountain solution to remove the image recording layer in the non-image portion on a printing press to produce a lithographic printing plate; and The process of printing using the obtained planographic printing plate.

Images