laminate

Abstract

The present application provides a kind of laminated body, it is the laminated body of lithographic printing plate precursor and backing paper, above-mentioned lithographic printing plate precursor is in at least any layer contains acid developer on-press development type lithographic printing plate precursor, the pH of above-mentioned backing paper is 5 or more.

Description

TECHNICAL FIELD

[0001] The present application relates to a laminated body of a lithographic printing plate precursor and a backing paper. BACKGROUND

[0002] Generally, a lithographic printing plate is composed of an oleophilic image portion that accepts ink in a printing process and a hydrophilic non-image portion that accepts dampening water. Lithographic printing is a method in which, by utilizing the property that water and an oily ink repel each other, the oleophilic image portion of a lithographic printing plate is made as an ink-accepting portion and the hydrophilic non-image portion is made as a dampening water-accepting portion (non-ink-accepting portion), an adhesion difference of the ink is generated on the surface of the lithographic printing plate, the ink is inked only on the image portion, and then the ink is transferred to a printed matter such as paper to perform printing.

[0003] In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image-recording layer) is provided on a hydrophilic support has been widely used. Generally, a lithographic printing plate is obtained by producing a plate by the following method: after the lithographic printing plate precursor is exposed to light through an original image such as a high-contrast film, the portion of the image-recording layer that becomes an image portion is left, and the unnecessary image-recording layer other than this is dissolved and removed by an alkali developer or an organic solvent, so that the surface of the hydrophilic support is exposed and a non-image portion is formed.

[0004] Further, as the concern for the global environment has been increasing, environmental problems related to waste liquid accompanying wet processing such as development processing have become apparent.

[0005] In view of the above environmental problems, simplification and processing-free of development or plate production are directed. As one of the simple production methods, a method called "on-press development" is performed. That is, a method in which, after a lithographic printing plate precursor is exposed to light, it is directly mounted to a printing machine without the conventional development, and the removal of the unnecessary portion of the image-recording layer is performed at the initial stage of the usual printing process.

[0006] In the present application, 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] As a laminated body of the conventional lithographic printing plate precursor, for example, a lithographic printing plate precursor described in Patent Document 1 can be given.

[0008] In Patent Literature 1, a layered body of a lithographic printing plate precursor is described, which is characterized in that a lithographic printing plate precursor having an image recording layer containing (A) an infrared absorber, (B) a radical polymerization initiator, and (C) a polymerizable compound and capable of removing an unexposed portion by supplying a printing ink and a dampening solution, and a backing paper are alternately laminated on a support, the content of chloride ions in the backing paper is 0.5% by mass or less, and the center line average roughness (Ra) is 2.4 μm to 5 μm.

[0009] Patent Literature 1: Japanese Patent Application Publication No. 2010-76336 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] An embodiment of the present application aims to provide a layered body of a lithographic printing plate precursor, which is excellent in the suppression of mottling color defects.

[0012] MEANS FOR SOLVING THE PROBLEMS

[0013] Among the means for solving the above problems, the following means are included.

[0014] <1> A layered body of a lithographic printing plate precursor and a backing paper,

[0015] The above-described lithographic printing plate precursor is an on-press development type lithographic printing plate precursor containing an acid color developer in at least any layer, and the pH of the above-described backing paper is 5 or more.

[0016] <2> The layered body according to <1>, wherein the change ΔL in the lightness of the exposed portion of the above-described lithographic printing plate precursor before and after exposure when exposure is performed based on infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm 2

[0017] <3> The layered body according to <1> or <2>, wherein the maximum value of the molar absorption coefficient ε of a color-developed substance produced by the above-described acid color developer at 400 nm to 800 nm is 25,000 to 200,000.

[0018] <4> The layered body according to any one of <1> to <3>, wherein the above-described lithographic printing plate precursor has a support and an image recording layer.

[0019] <5> The layered body according to <4>, wherein the above-described image recording layer contains the above-described acid color developer.

[0020] <6> The layered body according to <5>, wherein the change ΔL in the lightness of the exposed portion of the above-described lithographic printing plate precursor before and after exposure when exposure is performed based on infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm 2 ​The maximum absorption wavelength of the image recording layer in the wavelength range of 380 nm to 750 nm is 400 nm to 650 nm when the image recording layer is exposed to infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm

[0021] <7> The laminate according to <5> or <6>, wherein the ratio of the color-developing substance to the total mass of the acid color developer and the color-developing substance generated from the acid color developer is 15 mol% to 100 mol% when the image recording layer is exposed to infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm 2

[0022] <8> The laminate according to any one of <4> to <7>, wherein the image recording layer contains a polymerizable compound having a molecular weight of 2,500 or less, and the content of the polymerizable compound having a molecular weight of 2,500 or less is 50 mass% or less with respect to the total mass of the image recording layer.

[0023] <9> The laminate according to any one of <4> to <8>, wherein the image recording layer contains a polymer having a weight average molecular weight of 10,000 or more, and the content of the polymer having a weight average molecular weight of 10,000 or more is 10 mass% or more with respect to the total mass of the image recording layer.

[0024] <10> The laminate according to any one of <4> to <9>, wherein the lithographic printing plate precursor further has an outermost layer on the image recording layer.

[0025] <11> The laminate according to <10>, wherein the outermost layer contains a color-changing compound.

[0026] <12> The laminate according to <11>, wherein the color-changing compound contains a compound that develops color due to infrared exposure.

[0027] <13> The laminate according to <11> or <12>, wherein the color-changing compound contains a decomposable compound that decomposes due to infrared exposure.

[0028] <14> The laminate according to any one of <11> to <13>, wherein the color-changing compound is a cyanine dye.

[0029] <15> The laminate according to any one of <11> to <14>, wherein the color-changing compound is a compound represented by the following Formula 1-1.

[0030] [Chemical Formula 1]

[0031]

[0032] ​In Formula 1-1, R 1 represents a group represented by any one of Formulas 2-1 to 4-1 below, 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 a plurality of R 11 ~R 18 may be linked to form a monocyclic or polycyclic ring, A1and A2each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, n 11 and n 12 each independently represent an integer of 0 to 5, wherein the total of n 11 and n 12 is 2 or more, n 13 and n 14 each independently represent 0 or 1, L represents an oxygen atom, a sulfur atom, or -N(R 10 )-, R 10 represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes a charge.

[0033] [Chemical Formula 2]

[0034]

[0035] In Formulas 2-1 to 4-1, R 20 , R 30 , R 41 , and R 42 each independently represent an alkyl group or an aryl group, Zb represents a counter ion that neutralizes a charge, and the wavy line represents a bonding site with the group represented by L in Formula 1-1 above.

[0036] <16> The laminate according to any one of <11> to <15>, wherein the color changing compound comprises the acid developer.

[0037] <17> The laminate according to any one of <10> to <16>, wherein the outermost layer comprises a water-soluble polymer.

[0038] <18> The laminate according to <17>, wherein the water-soluble polymer comprises a polyvinyl alcohol having a saponification degree of 50% or more.

[0039] <19> The laminate according to any one of <10> to <18>, wherein the outermost layer comprises a lipophilizing agent.

[0040] <20> The laminate according to any one of <4> to <19>, wherein the image recording layer contains an infrared absorber, an electron-accepting polymerization initiator, and an electron-donating polymerization initiator.

[0041] <21> The laminate according to <20>, wherein the image recording layer contains, as the electron-accepting polymerization initiator and the electron-donating polymerization initiator, a compound formed of a cation having an electron-accepting polymerization initiator structure and an anion having an electron-donating polymerization initiator structure as a salt.

[0042] <22> The laminate according to <20>, wherein the electron-accepting polymerization initiator contains a compound represented by the following formula (II).

[0043] [Chemical Formula 3]

[0044]

[0045] In formula (II), X A represents a halogen atom, R A represents an aryl group.

[0046] <23> The laminate according to any one of <20> to <22>, wherein a value of HOMO of the infrared absorber - HOMO of the electron-donating polymerization initiator is 0.70 eV or less.

[0047] <24> The laminate according to any one of <20> to <23>, wherein a value of LUMO of the electron-accepting polymerization initiator - LUMO of the infrared absorber is 0.70 eV or less.

[0048] <25> The laminate according to <8>, wherein the polymerizable compound having a molecular weight of 2,500 or less contains a polymerizable compound having 7 or more functions.

[0049] <26> The laminate according to <8> or <25>, wherein the polymerizable compound having a molecular weight of 2,500 or less contains a polymerizable compound having 10 or more functions.

[0050] <27> The laminate according to any one of <4> to <26>, wherein the support has an aluminum plate and an anodized film of aluminum disposed on the aluminum plate, the anodized film is located on the image recording layer side more than the aluminum plate, the anodized film has micropores extending in the depth direction from the surface on the image recording layer side, and the average diameter of the micropores at the surface of the anodized film is more than 10 nm and 100 nm or less.

[0051] <28> The laminate according to <27>, wherein the above-mentioned micropores are composed of a large-diameter pore portion and a small-diameter pore portion, the large-diameter pore portion extends from the surface of the anodic oxide film to a position at a depth of 10 nm to 1,000 nm, the small-diameter pore portion communicates with the bottom of the large-diameter pore portion and extends from the communicating position to a position at a depth of 20 nm to 2,000 nm, the average diameter of the large-diameter pore portion at the surface of the anodic oxide film is 15 nm to 100 nm, and the average diameter of the small-diameter pore portion at the communicating position is 13 nm or less.

[0052] Effects of the Invention

[0053] According to an embodiment of the present invention, it is possible to provide a laminate of a laminated lithographic printing plate precursor, which is excellent in the suppression of spot-like color defects. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is a schematic cross-sectional view of an embodiment of an aluminum support body preferably used in the present invention.

[0055] Figure 2 is a schematic cross-sectional view of an embodiment of an aluminum support body having an anodic oxide film.

[0056] Figure 3 is a graph showing an example of an alternating waveform current waveform in an electrochemical roughening treatment in a manufacturing method of an aluminum support body having an anodic oxide film. DETAILED DESCRIPTION

[0057] Hereinafter, the contents of the present invention will be explained in detail. The explanations of the constituent elements described below are based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0058] In addition, in the present specification, "~" indicating a numerical range is used in the meaning that the numerical values recited before and after it are included as lower limit values and upper limit values.

[0059] Also, in the notation of groups (radicals) in the present specification, the notation not marked with "substituted" or "unsubstituted" includes not only groups having no substituents (unsubstituted groups), but also groups having substituents (substituted groups). For example, "alkyl group" includes not only alkyl groups having no substituents (unsubstituted alkyl groups), but also alkyl groups having substituents (substituted alkyl groups).

[0060] In the present specification, "(meth)acrylic acid" is a term used as a meaning including both acrylic acid and methacrylic acid, and "(meth)acryloyl group" is a term used as a meaning including both acryloyl group and methacryloyl group.

[0061] Also, the term "step" in the present specification includes not only a single step, but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step can be achieved. Also, in the present application, "mass%" and "weight%" are defined identically, and "mass parts" and "weight parts" are defined identically.

[0062] As long as not particularly limited, each component in the composition or each constitutional unit in the polymer in the present application can be contained singly or in combination of two or more.

[0063] Also, in the present application, as for the amount of each component in the composition or each constitutional unit in the polymer, in the case where a plurality of substances or constitutional units corresponding to each component in the composition or each constitutional unit in the polymer is present, as long as not particularly mentioned, it means the total amount of the corresponding plurality of substances present in the composition or the corresponding plurality of each constitutional unit present in the polymer.

[0064] Also, in the present application, a combination of two or more of the preferable modes is more preferable.

[0065] Also, as long as not particularly mentioned, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present application are the molecular weight converted to polystyrene by using a gel permeation chromatography (GPC) analysis device using a column of TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL (all are trade names manufactured by TOSOH CORPORATION), and by solvent THF (tetrahydrofuran), differential refractometer detection, and using polystyrene as a standard substance.

[0066] In the present application, the term "lithographic printing plate precursor" includes not only a lithographic printing plate precursor, but also a waste plate precursor. Also, the term "lithographic printing plate" includes not only a lithographic printing plate produced by performing an operation such as exposure and development on a lithographic printing plate precursor as needed, but also a waste plate. In the case of a waste plate precursor, an operation such as exposure and development is not necessarily required. In addition, a waste plate refers to a lithographic printing plate precursor used for mounting on an unused printing plate cylinder, for example, in the case where a part of a plate surface is printed in monochrome or in two colors in color newspaper printing.

[0067] In the present application, "excellent printing durability" means that the number of printable sheets of a lithographic printing plate is large, and hereinafter, the printing durability when a UV ink is used as an ink at the time of printing will be referred to as "UV printing durability".

[0068] Hereinafter, the present application will be described in detail.

[0069] (Laminate)

[0070] The present application relates to a laminate of a lithographic printing plate precursor and a backing paper, and the lithographic printing plate precursor is an on-press development type lithographic printing plate precursor containing an acid color developer in at least any layer, and the backing paper has a pH of 5 or more.

[0071] The present inventors and others have found that the conventional laminate of a lithographic printing plate precursor containing an acid color developer and a backing paper has a problem of developing a spot-like (dot-like, round dot-like) color defect with the passage of time, as described in the conventional patent document 1.

[0072] As a result of intensive studies by the present inventors and others, it has been found that the laminate having the above structure can provide a laminate having excellent spot-like color defect inhibitory properties.

[0073] Conventionally, a laminate of a backing paper having a pH of less than 5 has been generally used, and it is inferred that in the case of a laminate of a lithographic printing plate precursor containing an acid color developer and a backing paper, a part of the image recording layer containing the acid color developer coagulates within the image recording layer with the passage of time, and the acid diffusing from the backing paper reacts with the acid color developer in the coagulated part to develop color, resulting in a spot-like color defect.

[0074] It is inferred that the diffusion of the acid is inhibited by using a backing paper having a pH of 5 or more as the backing paper, and thus the spot-like color defect inhibitory properties are excellent.

[0075] The laminate according to the present application is a laminate of two or more lithographic printing plate precursors and one or more backing papers, and preferably a laminate in which the lithographic printing plate precursors and the backing papers are alternately stacked.

[0076] The upper limit of the number of the stacked lithographic printing plate precursors and the backing papers is not particularly limited, and can be appropriately selected as needed, and for example, several thousand lithographic printing plate precursors can be stacked.

[0077] The stacking direction of the lithographic printing plate precursors in the laminate according to the present application is not particularly limited, and all the lithographic printing plate precursors can be stacked in the same direction, or can be stacked in a manner in which one backing paper contacts the outermost layer of the image recording layer side of two lithographic printing plate precursors, respectively. At this time, the backing papers can be stacked between the support bodies of the lithographic printing plate precursors, or can not be stacked.

[0078] The laminate according to the present application can be packaged with a packaging paper or a packaging container, or the like. As the packaging member, a publicly known packaging member can be used, and for example, a packaging member having light shielding properties and moisture-proof properties, or the like can be mentioned.

[0079] Further, the present application relates to a laminate which can have a protective member such as a backing paperboard on the upper and lower sides thereof.

[0080] 〔〔liner paper〕〕

[0081] The present application relates to a laminate of a lithographic printing plate precursor and a liner paper, and the pH of the liner paper is 5 or more.

[0082] From the viewpoints of the inhibition of the spot-like color defects and the on-press developability, the pH of the liner paper is preferably 6 or more, more preferably 6 to 8, and particularly preferably 6.5 to 7.5.

[0083] The pH of the liner paper in the present application is measured by the cold water extraction method prescribed in JIS P8133 (2012).

[0084] Specifically, it is measured by the following method.

[0085] The measured liner paper is cut or torn into a size of about 1 cm 2 . 2.0 g ± 0.1 g of the sample is weighed and put into a 250 mL ground glass flask. 100 mL of water is added to the ground glass flask with the sample pieces, and it is confirmed that all the test pieces are immersed in the water. The flask is capped with a ground glass stopper, and left to stand for 1 hour at 20°C to 25°C. During this period, the ground glass flask is shaken at least once.

[0086] The extract is filtered with a glass filter having a coarse mesh, and the filtrate is transferred to a small beaker. 2 mL of a 1 mol / L potassium chloride solution is added, and the pH is measured. The obtained pH is taken as the pH of the liner paper.

[0087] As the material of the liner paper used in the present application, in order to suppress the material cost, it is preferable to select a low-cost raw material, for example, a paper using 100 mass% of wood pulp, a paper using synthetic pulp in combination with wood pulp, and a paper having a low-density or high-density polyethylene layer provided on the surface thereof, and the like.

[0088] Specifically, an acidic paper using a pulp in which bleached kraft pulp is beaten, a sizing agent is added to a pulp diluted to a concentration of 4 mass%, the raw paper mass becomes 0.1 mass%, a paper strengthening agent becomes 0.2 mass%, and further aluminum sulfate is added until the pH reaches 5.0 can be cited, but a neutral paper in which a neutral sizing agent such as alkyl alkenyl ketone dimer (AKD), alkenyl succinic anhydride (ASA), and the like is used as a sizing agent, calcium carbonate is used as a filler instead of aluminum sulfate, and the pH is 7 to 8 can be preferably used.

[0089] Among them, as the backing paper, paper is preferable, more preferably paper containing aluminum sulfate or calcium carbonate, and particularly preferably paper containing calcium carbonate.

[0090] Further, as the material of the backing paper, paper containing 50% by mass or more of pulp is preferable, more preferably paper containing 70% by mass or more of pulp, and particularly preferably paper containing 80% by mass or more of pulp.

[0091] As the backing paper, the calcium content with respect to the entire backing paper is preferably 0.15% by mass to 0.5% by mass, more preferably 0.2% by mass to 0.45% by mass, and particularly preferably 0.25% by mass to 0.4% by mass.

[0092] The calcium content of the backing paper is obtained by performing fluorescent X-ray measurement on the backing paper.

[0093] The calcium contained in the paper is mainly calcium carbonate, which is widely used as a filler of neutral paper, and has an effect of improving the whiteness of the paper.

[0094] The basis weight of the backing paper (based on the measurement method specified in JIS P8124 (2011)) is not particularly limited, but is preferably 29 g / m 2 to 60 g / m 2 , more preferably 35 g / m 2 to 55 g / m 2 , and particularly preferably 40 g / m 2 to 50 g / m 2 .

[0095] The thickness of the backing paper (based on the measurement method specified in JTS P8118 (2014)) is not particularly limited, but is preferably 20 μm to 100 μm, more preferably 42 μm to 80 μm, further preferably 45 μm to 65 μm, and particularly preferably 45 μm to 55 μm.

[0096] Further, from the viewpoint of inhibition of spot-like color defects, the moisture content of the backing paper (moisture content when the backing paper is stored at 25°C / 50% RH and the moisture content of the backing paper is stabilized) is preferably 0% by mass to 20% by mass, more preferably 0% by mass to 15% by mass, and particularly preferably 0% by mass to 10% by mass, with respect to the total mass of the backing paper.

[0097] Further, as the backing paper, the backing paper in which the pH is 5 or more described in Japanese Patent Application Publication No. 2010-76336 can be preferably used.

[0098] The shape of the backing paper is not particularly limited, but a shape identical to or larger than the shape in the face direction of the lithographic printing plate precursor can be mentioned.

[0099] 〔〔lithographic printing plate original〕〕

[0100] The present application relates to a laminate of a lithographic printing plate original and a backing paper, and the above-mentioned lithographic printing plate original is an on-press development type lithographic printing plate original containing an acid color developer in at least any of the layers.

[0101] The above-mentioned lithographic printing plate original preferably has a support and an image recording layer, more preferably has a support, an image recording layer and an outermost layer in this order, and particularly preferably has a support, an undercoat layer, an image recording layer and an outermost layer in this order.

[0102] Further, the above-mentioned lithographic printing plate original preferably has an outermost layer on the above-mentioned image recording layer.

[0103] In the above-mentioned lithographic printing plate original, preferably at least one of the above-mentioned image recording layer and the above-mentioned outermost layer contains the above-mentioned acid color developer, and more preferably the above-mentioned image recording layer contains the above-mentioned acid color developer.

[0104] In the lithographic printing plate original in the laminate of the present application, the luminance change ΔL of the exposed part of the above-mentioned lithographic printing plate original before and after the exposure when the exposure based on infrared rays having a wavelength of 830 nm is performed at an energy density of 110 mJ / cm 2 is preferably 5.0 or more, more preferably 6.0 or more, more preferably 8 or more, and particularly preferably 10 to 20.

[0105] The energy density of the exposure by infrared laser having a wavelength of 830 nm is 110 mJ / cm 2 The measurement of the luminance change ΔL of the above-mentioned image recording layer before and after the exposure when the above-mentioned image recording layer is exposed is performed by the following method.

[0106] The lithographic printing plate original is exposed by Luxel PLATESETTER T-9800 manufactured by FUJIFILM Graphic Systems Co., Ltd. equipped with an infrared semiconductor laser having a wavelength of 830 nm, under the conditions (energy density: 110 mJ / cm 2 ) of output 99.5%, outer drum rotation speed 220 rpm (revolutions per minute), and resolution 2,400 dpi (dots per inch (1 inch = 25.4 mm)). As for the exposure, it is performed in an environment of 25°C, 50% RH.

[0107] The luminance change of the lithographic printing plate original before and after the exposure is measured. In the measurement, a spectrophotometer eXact manufactured by X-Rite Inc. is used. The L * a * b* L value (lightness) of the color system * the L value of the image recording layer after exposure * the L value of the image recording layer before exposure * the absolute value of the difference between the L value of the image recording layer after exposure

[0108] Also, in the above lithographic printing plate precursor, from the viewpoint of further exerting the effect of suppressing the spot-like color defect, the maximum value of the molar absorption coefficient ε of the color-developed body generated from the above acid color developer at 400 nm to 800 nm is preferably 10,000 to 200,000, more preferably 25,000 to 200,000, further preferably 35,000 to 200,000, and particularly preferably 50,000 to 150,000.

[0109] The molar absorption coefficient ε of the color-developed body generated from the above acid color developer is measured by the following method.

[0110] The measured acid color developer 0.04 mmol is accurately weighed into a 100 mL volumetric flask.

[0111] After adding about 90 mL of acetic acid, the sample is completely dissolved as confirmed by the naked eye, and the volume is made 100 mL with acetic acid to prepare a pigment solution A.

[0112] After adding about 80 mL of acetic acid to another 100 mL volumetric flask, 5 mL of ion exchange water and 5 mL of the above pigment solution A are added using a 5 mL total volume pipette, and the mixture is gently shaken.

[0113] After confirming that no acid color developer is precipitated by the naked eye, the volume is made 100 mL with acetic acid to prepare a pigment solution B. In the pigment solution B, the concentration of the color-developed body precursor is 0.02 mmol / L.

[0114] The pigment solution B is filled into a measuring cell (quartz glass, light path width 10 mm), and measurement is performed using a UV-visible spectrophotometer (manufactured by SHIMADZU CORPORATION, UV-1800).

[0115] The blank medium is set to water: acetic acid = 5:95 liquid.

[0116] The absorption maximum wavelength in the visible region (380 nm to 750 nm) is read from the obtained spectrum, and the molar absorption coefficient ε is calculated from the absorbance at the wavelength.

[0117] From the viewpoint of visual recognition, the exposure energy is set to 110 mJ / cm 2The maximum absorption wavelength λmax of the image recording layer in the wavelength range of 380 nm to 750 nm when exposed to infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm2is preferably 400 nm to 650 nm, more preferably 500 nm to 650 nm, further preferably 520 nm to 600 nm, particularly preferably 530 nm to 580 nm, and most preferably 540 nm to 570 nm.

[0118] The image recording layer was exposed to infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm2. 2 The ratio (opening ratio) of the above color developing body to the total mass of the above acid color developing agent and the color developing body generated from the above acid color developing agent when exposed to infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm2is preferably 1 mole% to 100 mole%, more preferably 5 mole% to 100 mole%, further preferably 15 mole% to 100 mole%, and particularly preferably 30 mole% or more and 99 mole% or less.

[0119] Opening ratio = molar absorption coefficient at the time of adding 1 mole equivalent of acid / molar absorption coefficient of acid color developing agent x 100

[0120] The above opening ratio and the above λmax in the present application are measured by the following method.

[0121] - Preparation of Pigment Solution C

[0122] The color developing body precursor 0.1 mmol was accurately weighed into a 50 mL volumetric flask.

[0123] After confirming that the sample was completely dissolved by the naked eye, the volume was made 50 mL with acetonitrile to prepare Pigment Solution C.

[0124] - Preparation of Acid Solution D

[0125] CSA (10-camphorsulfonic acid) 0.2 mmol was added to a 100 mL volumetric flask, and acetonitrile was added to about 80 mL, and after confirming that the CSA was completely dissolved, the volume was made 100 mL with acetonitrile to prepare Acid Solution D.

[0126] - Preparation of Measurement Solution E

[0127] Using a full volume pipette, 5 mL of ion exchange water was added to a 100 mL volumetric flask, and acetonitrile was added to 80 mL. 1 mL of Pigment Solution C and 1 mL of Acid Solution D were added, and the volume was made 100 mL to prepare Measurement Solution E.

[0128] The concentration of the color developing body precursor containing the color developing body generated in Measurement Solution E was 0.02 mmol / L.

[0129] The pigment solution E was filled into a measuring cell (quartz glass, light path width: 10 mm), and measurement was performed using a UV-visible spectrophotometer (manufactured by SHIMADZU CORPORATION, UV-1800).

[0130] The blank medium was set to water: acetonitrile = 5:95 solution.

[0131] The absorption maximum wavelength λmax in the visible region (380 nm to 750 nm) was read from the obtained spectrum, and the molar absorption coefficient ε was calculated from the absorbance at this wavelength.

[0132] The ring-opening rate was calculated according to the following calculation formula.

[0133] Ring-opening rate = molar absorption coefficient of the chromogenic body precursor when 1 molar equivalent of acid is added / molar absorption coefficient of the chromogenic body precursor x 100

[0134] Hereinafter, the details of each component in the lithographic printing plate precursor according to the present application will be described.

[0135] <image recording layer>

[0136] The image recording layer used in the present application is preferably a negative type image recording layer, and more preferably a water-soluble or water-dispersible negative type image recording layer.

[0137] With regard to the lithographic printing plate precursor according to the present application, from the viewpoint of on-press developability, it is preferable that the unexposed portion of the image recording layer be removable by at least either of a fountain solution or a printing ink.

[0138] The above-mentioned image recording layer preferably contains the above-mentioned acid color developer.

[0139] Further, the above-mentioned image recording layer preferably contains an infrared absorber and an electron-accepting polymerization initiator, and more preferably contains an infrared absorber, an electron-accepting polymerization initiator, and an electron-donating polymerization initiator.

[0140] Further, from the viewpoints of spot-like color defect inhibitory property and on-press developability, the above-mentioned image recording layer preferably contains a polymerizable compound having a molecular weight of 2,500 or less, and more preferably contains the polymerizable compound having a molecular weight of 2,500 or less in an amount of 50% by mass or less relative to the total mass of the above-mentioned image recording layer.

[0141] Further, from the viewpoints of spot-like color defect inhibitory property and on-press developability, the above-mentioned image recording layer preferably contains a polymer having a weight average molecular weight of 10,000 or more, and more preferably contains the polymer having a weight average molecular weight of 10,000 or more in an amount of 10% by mass or more relative to the total mass of the above-mentioned image recording layer.

[0142] Next, the details of each component contained in the image recording layer will be described.

[0143] 〔Acid color developer〕

[0144] The image recording layer in the present application preferably contains an acid color developer. Also, as the acid color developer, a leuco compound is preferably contained.

[0145] The "acid color developer" used in the present application refers to a compound having a property of developing or fading color and changing the color of the image recording layer by being heated in a state of having received an electron-accepting compound (such as a proton of an acid). As the acid color developer, a leuco compound having a partial skeleton of a lactone, a lactam, a sultone, a spiropyran, an ester, an amide, or the like, and rapidly ring-opening or cleaving at the time of contact with an electron-accepting compound is particularly preferred.

[0146] As an example of such an acid color developer, the compounds described in paragraphs 0184 to 0191 of Japanese Patent Application Publication No. 2019-18412 can be given.

[0147] Among them, from the viewpoint of visual recognition, the acid color developer used in the present application is preferably at least one compound selected from the group consisting of a spiropyran compound, a spirooxazine compound, a spironolactone compound, and a spiroamide compound.

[0148] As the hue of the colorant after development, from the viewpoint of visibility, it is preferable to have an absorption maximum wavelength in the range of 450 to 650 nm. As the color tone, it is preferable to be red, purple, blue, or dark green.

[0149] Also, from the viewpoints of visual recognition and visual recognition of the exposed portion, the above acid color developer is preferably a leuco colorant.

[0150] As the above leuco colorant, there is no particular limitation as long as it is a colorant having a leuco structure, but it is preferable to have a helical structure, and more preferable to have a spironolactone ring structure.

[0151] Also, as the above leuco colorant, from the viewpoints of visual recognition and visual recognition of the exposed portion, it is preferable to be a leuco colorant having a phthaloperin structure or a fluoran parent structure.

[0152] Furthermore, from the viewpoints of visual recognition and visual recognition of the exposed portion, the above leuco colorant having a phthaloperin structure or a fluoran parent structure is preferably a compound represented by any one of the following Formulae (Le-1) to (Le-3), and more preferably a compound represented by the following Formula (Le-2).

[0153] [Chemical Formula 4]

[0154]

[0155] In formulae (Le-1) to (Le-3), ERG independently represents an electron-donating group, X1to X4independently represent a hydrogen atom, a halogen atom, or a dialkylanilino group, X5to X 10 independently represent a hydrogen atom, a halogen atom, or a monovalent organic group, Y1and Y2independently represent C or N, X1is not present in the case where Y1is N, X4is not present in the case where Y2is N, Ra1represents a hydrogen atom, an alkyl group, or an alkoxy group, and Rb1to Rb4independently represent a hydrogen atom, an alkyl group, or an aryl group.

[0156] As the electron-donating group in ERG of formulae (Le-1) to (Le-3), from the viewpoints of visual recognition and visual recognition of the exposure portion, an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoaryl amino group, a diarylamino group, an alkoxy group, an aryloxy group, or an alkyl group is preferable, an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoaryl amino group, a diarylamino group, an alkoxy group, or an aryloxy group is more preferable, an arylamino group, a monoalkylmonoaryl amino group, or a diarylamino group is further preferable, and an arylamino group or a monoalkylmonoaryl amino group is particularly preferable.

[0157] From the viewpoints of visual recognition and visual recognition of the exposure portion, X1to X4in formulae (Le-1) to (Le-3) are each independently preferably a hydrogen atom or a chlorine atom, and more preferably a hydrogen atom.

[0158] From the viewpoints of visual recognition and visual recognition of the exposure portion, X5to X 10 are each independently preferably a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoaryl amino group, a diarylamino group, a hydroxyl group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a cyano group, more preferably a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, or an aryloxy group, and further preferably a hydrogen atom, a halogen atom, an alkyl group, or an aryl group, and particularly preferably a hydrogen atom.

[0159] From the viewpoints of visual recognition and visual recognition of the exposure portion, Y1and Y2in formulae (Le-1) to (Le-3) are preferably at least one of C, and more preferably both of Y1and Y2are C.

[0160] From the viewpoints of visual recognition and visual recognition of the exposure portion, Ra1in formula (Le-3) is preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group.

[0161] From the viewpoint of visual recognition and visual recognition of the exposure portion, Rb1to Rb4in 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.

[0162] Further, from the viewpoint of visual recognition and visual recognition of the exposure portion, the above-mentioned leuco dye having a phthalide structure or a fluoran parent structure is more preferably a compound represented by any one of the following Formulae (Le-4) to (Le-6), and is further preferably a compound represented by the following Formula (Le-5).

[0163] [Chemical Formula 5]

[0164]

[0165] In Formulae (Le-4) to (Le-6), ERG each independently represents an electron-donating group, X1to X4each independently represent a hydrogen atom, a halogen atom, or a dialkylanilino group, Y1and Y2each independently represent C or N, X1is not present in the case where Y1is N, X4is not present in the case where Y2is N, Ra1represents a hydrogen atom, an alkyl group, or an alkoxy group, and Rb1to Rb4each independently represent a hydrogen atom, an alkyl group, or an aryl group.

[0166] ERG, X1to X4, Y1, Y2, Ra1, and Rb1to Rb4in Formulae (Le-4) to (Le-6) each have the same meaning as ERG, X1to X4, Y1, Y2, Ra1, and Rb1to Rb4in Formulae (Le-1) to (Le-3), and the preferable modes are also the same.

[0167] Further, from the viewpoint of visual recognition and visual recognition of the exposure portion, the above-mentioned leuco dye having a phthalide structure or a fluoran parent structure is more preferably a compound represented by any one of the following Formulae (Le-4) to (Le-6), and is further preferably a compound represented by the following Formula (Le-5).

[0168] [Chemical Formula 6]

[0169]

[0170] In Formulae (Le-7) to (Le-9), X1to X4each independently represent a hydrogen atom, a halogen atom, or a dialkylanilino group, Y1and Y2each independently represent C or N, X1is not present in the case where Y1is N, X4is not present in the case where Y2is N, Ra1to Ra4each independently represent a hydrogen atom, an alkyl group, or an alkoxy group, Rb1to Rb4each independently represent a hydrogen atom, an alkyl group, or an aryl group, and Rc1and Rc2each independently represent an aryl group.

[0171] X1to X4, Y1and Y2in formula (Le-7) to formula (Le-9) are the same in meaning as X1to X4, Y1and Y2in formula (Le-1) to formula (Le-3), and the preferable modes are also the same.

[0172] From the viewpoints of visual recognition and visual recognition of the exposure portion, Ra1to Ra4in formula (Le-7) are each independently preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group.

[0173] From the viewpoints of visual recognition and visual recognition of the exposure portion, Rb1to Rb4in formula (Le-7) to formula (Le-9) are each independently preferably a hydrogen atom, an alkyl group, or an aryl group substituted with 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.

[0174] From the viewpoints of visual recognition and visual recognition of the exposure portion, Rc1and Rc2in formula (Le-8) are each independently preferably a phenyl group or an alkylphenyl group, and more preferably a phenyl group.

[0175] Also, in formula (Le-8), from the viewpoints of visual recognition and visual recognition of the exposure portion, X1to X4are preferably hydrogen atoms, and Y1and Y2are preferably C.

[0176] Also, in formula (Le-8), from the viewpoints of visual recognition and visual recognition of the exposure portion, Rb1and Rb2are 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.

[0177] Also, as the acid color developer, from the viewpoints of color development and visual recognition of the exposure portion, a compound represented by the following formula (Le-10) is preferably contained.

[0178] [Chemical Formula 7]

[0179]

[0180] In formula (Le-10), Ar1indicates an aryl group or a heteroaryl group, and Ar2indicates 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.

[0181] Ar1in formula (Le-10) is the same in meaning as Rb1and Rb2in formula (Le-7) to formula (Le-9), and the preferable modes are also the same.

[0182] Ar2in formula (Le-10) is the same in meaning as Rc1and Rc2in formula (Le-7) to formula (Le-9), and the preferable modes are also the same.

[0183] The alkyl group in the formulae (Le-1) to (Le-9) can be linear, branched, or cyclic.

[0184] The number of carbon atoms of the alkyl group in the formulae (Le-1) to (Le-9) is preferably from 1 to 20, more preferably from 1 to 8, further preferably from 1 to 4, and particularly preferably 1 or 2.

[0185] The number of carbon atoms of the aryl group in the formulae (Le-1) to (Le-10) is preferably from 6 to 20, more preferably from 6 to 10, and particularly preferably from 6 to 8.

[0186] Specific examples of the aryl group in the formulae (Le-1) to (Le-10) include phenyl, naphthyl, anthryl, phenanthryl, and the like, which can have a substituent.

[0187] Specific examples of the heteroaryl group in the formulae (Le-1) to (Le-10) include furyl, pyridyl, pyrimidyl, pyrazolyl, and phenylthio, which can have a substituent.

[0188] Further, each of the monovalent organic group, the alkyl group, the aryl group, the heteroaryl group, the dialkylanilino group, the alkylamino group, the alkoxy group, and the like in the formulae (Le-1) to (Le-10) can have a substituent. Examples of the substituent include an alkyl group, an aryl group, a heteroaryl group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylaminogroup, 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, a cyano group, and the like. Further, these substituents can be further substituted with these substituents.

[0189] Specific examples of the above-mentioned colorless dyes having a phthaloperin structure or a fluoran parent structure, which can be preferably used, include the following compounds.

[0190] [Chemical Formula 8]

[0191]

[0192] [Chemical Formula 9]

[0193]

[0194] [Chemical Formula 10]

[0195]

[0196] [Chemical Formula 11]

[0197]

[0198] [Chemical Formula 13]

[0199]

[0200] [Chemical Formula 14]

[0201]

[0202] [Chemical Formula 15]

[0203]

[0204] As the acid color developer, marketed products can also be used, and ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H-3035, BLUE203, ATP, H-1046, H-2114 (manufactured by Fukui Yamada Chemical Co., Ltd.), ORANGE-DCF, Vermilion-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF, TH-107 (manufactured by HODOGAYA CHEMICAL CO., LTD.), ODB, ODB-2, ODB-4, ODB-250, ODB-Black XV, Blue-63, Blue-502, GN-169, GN-2, Green-118, Red-40, Red-8 (manufactured by YAMAMOTO CHEMICALS INC.), crystal violet lactone (manufactured by Tokyo Chemical Industry Co., Ltd.), and the like can be mentioned. Among these marketed 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, crystal violet lactone are preferable because the visible light absorbance of the formed film is good.

[0205] As the colorless dye that can be preferably used, the following compounds can be mentioned from the viewpoint of visual recognition and visual recognition of the exposed portion.

[0206] [Chemical Formula 16]

[0207]

[0208] [Chemical Formula 17]

[0209]

[0210] These color developers can be used singly or in combination of two or more kinds.

[0211] The content of the color developer is preferably 0.5 to 10 mass% and more preferably 1 to 5 mass% relative to the total mass of the image recording layer.

[0212] (Infrared absorber)

[0213] The image recording layer in the present application preferably contains an infrared absorber.

[0214] There is no particular limitation on the infrared absorber, and pigments and dyes can be given as examples.

[0215] As the dyes that can be used as the infrared absorber, commercially available dyes and well-known dyes described in documents such as "Dye Handbook" (The Society of Synthetic Organic Chemistry, Japan. Edited, published in 45 years of Showa) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinonimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiol complexes, and the like can be given.

[0216] As the preferred dyes among these dyes, cyanine dyes, squarylium dyes, pyrylium salts, nickel thiol complexes, indocyanine dyes can be given. More preferably, cyanine dyes or indocyanine dyes are given. Among them, cyanine dyes are particularly preferred.

[0217] As the above-mentioned infrared absorber, a cationic polymethine dye having an oxygen atom, a nitrogen atom, or a halogen atom at the meta position is preferred. As the cationic polymethine dye, cyanine dyes, pyrylium dyes, thiopyrylium dyes, azulene dyes, and the like are given, and from the viewpoints of ease of obtaining, solvent solubility at the time of introduction reaction, and the like, cyanine dyes are preferred.

[0218] As specific examples of the cyanine dye, the compounds described in paragraphs 0017 to 0019 of Japanese Patent Application Publication No. 2001-133969, paragraphs 0016 to 0021 of Japanese Patent Application Publication No. 2002-023360, and paragraphs 0012 to 0037 of Japanese Patent Application Publication No. 2002-040638 can be given, and the compounds described in paragraphs 0034 to 0041 of Japanese Patent Application Publication No. 2002-278057, paragraphs 0080 to 0086 of Japanese Patent Application Publication No. 2008-195018 are preferably given, and the compounds described in paragraphs 0035 to 0043 of Japanese Patent Application Publication No. 2007-90850 and paragraphs 0105 to 0113 of Japanese Patent Application Publication No. 2012-206495 are particularly preferably given.

[0219] Further, the compounds described in paragraphs 0008 to 0009 of Japanese Patent Application Publication No. 5-5005 and paragraphs 0022 to 0025 of Japanese Patent Application Publication No. 2001-222101 can also be preferably used.

[0220] As the pigment, the compounds described in paragraphs 0072 to 0076 of Japanese Patent Application Publication No. 2008-195018 are preferably given.

[0221] Further, as the above-described infrared absorber, the decomposable compound which is described later as a color-changing compound of the outermost layer and which is decomposed by infrared exposure can also be preferably used.

[0222] From the viewpoint of print durability and visual recognition, the highest occupied molecular orbital (HOMO) of the above-described infrared absorber is preferably -5.250 eV or less, more preferably -5.30 eV or less, further preferably -5.80 eV or more and -5.35 eV or less, and particularly preferably -5.65 eV or more and -5.40 eV or less.

[0223] From the viewpoint of temporal stability, improved sensitivity, and UV print durability, the lowest unoccupied molecular orbital (LUMO) of the above-described infrared absorber is preferably less than -3.70 eV, more preferably less than -3.80 eV, further preferably -4.20 eV or more and less than -3.80 eV, and particularly preferably -4.00 eV or more and less than -3.80 eV.

[0224] The infrared absorber can be used singly or in combination with two or more kinds.

[0225] Further, as the infrared absorber, a pigment and a dye can be used in combination.

[0226] The content of the infrared absorber is preferably 0.1 to 10.0 mass% and more preferably 0.5 to 5.0 mass% with respect to the total mass of the image-recording layer.

[0227] 〔Electron-accepting polymerization initiator〕

[0228] The image recording layer in the present application preferably contains an electron-accepting polymerization initiator.

[0229] The electron-accepting polymerization initiator is a compound which generates a polymerization initiator species such as a radical by accepting an electron through intermolecular electron transfer when the electron of an infrared absorber is excited by infrared exposure.

[0230] The electron-accepting polymerization initiator is a compound which generates a polymerization initiator species such as a radical or a cation by the energy of light, heat or both, and a publicly known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator or the like can be appropriately selected and used.

[0231] As the electron-accepting polymerization initiator, a radical polymerization initiator is preferred, and an onium salt compound is more preferred.

[0232] Further, as the electron-accepting polymerization initiator, an infrared photosensitive polymerization initiator is preferred.

[0233] Furthermore, as the electron-accepting polymerization initiator, from the viewpoints of stability over time, UV plate wear inhibition, improvement of sensitivity and UV print durability, an iodonium salt compound or a compound having a halogenated alkyl group is preferred, and a compound having a halogenated alkyl group is more preferred.

[0234] Furthermore, as the compound having a halogenated alkyl group, from the viewpoints of stability over time, UV plate wear inhibition, GLV suitability, improvement of sensitivity and UV print durability, a compound having a perhaloalkylsulfonyl group is preferred, a compound having a trihalomethylsulfonyl group is more preferred, and a compound having a tribromomethylsulfonyl group is particularly preferred.

[0235] Among the above-mentioned electron-accepting polymerization initiators, as the preferred electron-accepting polymerization initiator, from the viewpoint of curability, an oxime ester compound and an onium salt compound can be given. Among them, from the viewpoint of print durability, an iodonium salt compound, a sulfonium salt compound or an azinium salt compound is preferred, an iodonium salt compound or a sulfonium salt compound is more preferred, and an iodonium salt compound is particularly preferred.

[0236] Specific examples of these compounds are shown below, but the present application is not limited thereto.

[0237] As examples of the iodonium salt compound, a diaryliodonium salt compound is preferable, and more particularly, a diphenyl iodonium salt compound substituted with an electron-donating group such as an alkyl group or an alkoxy group is preferable, and an unsymmetrical diphenyl iodonium salt compound is preferable. As specific examples, diphenyl iodonium hexafluorophosphate, 4-methoxyphenyl-4-(2-methylpropyl)phenyl iodonium hexafluorophosphate, 4-(2-methylpropyl)phenyl-p-tolyl iodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyl iodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyl iodonium tetrafluoroborate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyl iodonium 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyl iodonium hexafluorophosphate, and bis(4-tert-butylphenyl) iodonium tetraphenylborate are given.

[0238] Further, as examples of the counter anion of the iodonium salt compound and the sulfonium salt compound, a sulfonic acid anion, a carboxylic acid anion, a tetrafluoroboric acid anion, a hexafluorophosphoric acid anion, a p-toluenesulfonic acid anion, a p-toluenesulfonic acid anion, a sulfonamide anion, or a sulfimide anion is given.

[0239] Among them, a sulfonamide anion or a sulfimide anion is preferable, and a sulfimide anion is more preferable.

[0240] As the sulfonamide anion, an arylsulfonamide anion is preferable.

[0241] Further, as the sulfimide anion, a diarylsulfimide anion is preferable.

[0242] As specific examples of the sulfonamide anion or the sulfimide anion, a compound described in International Publication No. 2019 / 013268 is given.

[0243] Further, as the above electron-accepting polymerization initiator, from the viewpoints of the visual recognition over time after exposure, the developability, and the UV printing durability in the obtained lithographic printing plate, a compound represented by the following formula (II) or formula (III) is preferable, and particularly, a compound represented by formula (II) is preferable.

[0244] [Chemical Formula 18]

[0245]

[0246] In formula (II) and formula (III), X A represents a halogen atom, R A , R A1 , and R A2 each independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0247] R in formula (II) A is preferably aryl.

[0248] As X in formula (II) and formula (III) A , a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom can be given. Among these, a chlorine atom or a bromine atom is preferable because of excellent sensitivity, and a bromine atom is particularly preferable.

[0249] Also, in formula (II) and formula (III), R A , R A1 , and R A2 are each independently preferably aryl, and more preferably aryl substituted with an amido group from the viewpoint of excellent balance between sensitivity and storage stability.

[0250] Also, as the above-mentioned electron-accepting polymerization initiator, a compound represented by formula (IV) is particularly preferable.

[0251] [Chemical Formula 19]

[0252]

[0253] In formula (IV), X A represents a halogen atom, R A3 , and R A4 each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and pA and qA each independently represent an integer of 1 to 5. Among these, pA + qA = 2 to 6.

[0254] As specific examples of the electron-accepting polymerization initiator, compounds shown in the following, and the like can be given, but the present application is not limited to these.

[0255] [Chemical Formula 20]

[0256]

[0257] [Chemical Formula 21]

[0258]

[0259] [Chemical Formula 22]

[0260]

[0261] [Chemical Formula 23]

[0262]

[0263] [Chemical Formula 24]

[0264]

[0265] [Chemical Formula 25]

[0266]

[0267] [Chemical Formula 26]

[0268]

[0269] From the viewpoints of stability with time, UV plate wear inhibitory property, GLV suitability, and UV printing durability, the lowest unoccupied molecular orbital (LUMO) of the electron-accepting polymerization initiator is preferably greater than -3.3 eV, more preferably greater than -3.2 eV.

[0270] Also, as an upper limit, from the viewpoints of improving sensitivity and not easily causing plate wear, it is preferably -3.00 eV or less, more preferably -3.02 eV or less.

[0271] The electron-accepting polymerization initiator can be used alone or in combination of two or more.

[0272] The content of the electron-accepting polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, particularly preferably 0.8 to 20% by mass, relative to the total mass of the image-recording layer.

[0273] [Electron-donating polymerization initiator (polymerization aid)]

[0274] The image-recording layer in the present application preferably contains an electron-donating polymerization initiator (also referred to as "polymerization aid") as a polymerization initiator.

[0275] The electron-donating polymerization initiator is a compound that generates a polymerization initiator species such as a radical by donating one electron through intermolecular electron transfer at an orbital from which one electron of the infrared absorber is detached when the electron of the infrared absorber is excited or moves within the molecule by infrared exposure.

[0276] As the electron-donating polymerization initiator, an electron-donating radical polymerization initiator is preferred.

[0277] From the viewpoint of printing durability, the image-recording layer preferably contains a borate compound.

[0278] As the borate compound, from the viewpoints of visual recognition and color development, a tetraarylborate compound or a monoalkyl triarylborate compound is preferred, more preferably a tetraarylborate compound.

[0279] Further, as the borate compound, from the viewpoints of UV plate wear inhibition, print durability, and visual recognition, a tetraaryl borate compound having one or more electron-donating groups is preferred, and a tetraaryl borate compound having one electron-donating group in each aryl group is more preferred.

[0280] As the above electron-donating group, from the viewpoints of UV plate wear inhibition, print durability, and visual recognition, an alkyl group or an alkoxy group is preferred, and an alkoxy group is more preferred.

[0281] As the counter cation of the borate compound, there is no particular limitation, but an alkali metal ion or a tetraalkylammonium ion is preferred, and a sodium ion, a potassium ion, or a tetrabutylammonium ion is more preferred.

[0282] Further, as the counter cation of the borate compound, among the infrared absorbers described in the present specification, a cationic poly-methine dye can be used. For example, as the counter cation of a cyanine dye, the above borate compound can be used.

[0283] As the borate compound, specifically, sodium tetraphenyl borate is preferred.

[0284] The following shows B-1 to B-9 as preferred specific examples of the electron-donating polymerization initiator, but of course, is not limited to these. Further, in the following chemical formulas, Ph represents a phenyl group, and Bu represents an n-butyl group.

[0285] [Chemical Formula 27]

[0286]

[0287] Further, from the viewpoints of improving sensitivity and not easily causing 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, further preferably -5.93 eV or higher, and particularly preferably greater than -5.90 eV.

[0288] Further, as the upper limit, -5.00 eV or lower is preferred, and -5.40 eV or lower is more preferred.

[0289] The electron-donating polymerization initiator can be used alone or in combination of two or more.

[0290] As the content of the electron-donating polymerization initiator, from the viewpoints of sensitivity and print durability, 0.01 to 30 mass% with respect to the total mass of the image recording layer is preferred, 0.05 to 25 mass% is more preferred, and 0.1 to 20 mass% is further preferred.

[0291] In the present application, the polymerization initiator can be a compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form a counter salt, and as the above-mentioned electron-accepting polymerization initiator and the above-mentioned electron-donating polymerization initiator, a compound formed by a salt in which a cation having the structure of an electron-accepting polymerization initiator and an anion having the structure of an electron-donating polymerization initiator are combined is preferred. As the cation having the structure of an electron-accepting polymerization initiator, for example, onium in the above-mentioned onium compound can be given, and as the anion having the structure of an electron-donating polymerization initiator, for example, borate in the above-mentioned borate compound can be given.

[0292] For example, in the present application, 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, a compound in which an onium cation and a borate anion form a counter salt is more preferred, a compound in which an iodonium cation or a sulfonium cation and a borate anion form a counter salt is further preferred, and a compound in which a diaryliodonium cation or a triarylsulfonium cation and a tetraarylborate anion form a counter salt is particularly preferred.

[0293] As the preferred mode of the anion in an electron-donating polymerization initiator and the cation in an electron-accepting polymerization initiator, the same as the preferred mode of the anion in an electron-donating polymerization initiator and the preferred mode of the cation in an electron-accepting polymerization initiator described above is given.

[0294] In the case where the image-recording layer contains an anion that is an electron-donating polymerization initiator and a cation that is an electron-accepting polymerization initiator (i.e., in the case where a compound that forms the above-mentioned counter salt is contained), the image-recording layer contains an electron-accepting polymerization initiator and the above-mentioned electron-donating polymerization initiator.

[0295] Further, the compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form a counter salt can be used as an electron-donating polymerization initiator and can be used as an electron-accepting polymerization initiator.

[0296] Further, the compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form a counter salt can be used in combination with the above-mentioned electron-donating polymerization initiator and can be used in combination with the above-mentioned electron-accepting polymerization initiator.

[0297] 〔Relationship between infrared absorber and electron-donating polymerization initiator〕

[0298] In the image recording layer of the present application, from the viewpoints of UV plate wear inhibition and print durability, the value of HOMO of the above-mentioned infrared absorber - HOMO of the above-mentioned electron- donating polymerization initiator is preferably 0.70 eV or less, more preferably 0.60 eV or less, further preferably 0.55 eV or less, particularly preferably 0.50 eV or less, and most preferably 0.50 eV to -0.10 eV.

[0299] Further, the negative value means that the HOMO of the above-mentioned electron- donating polymerization initiator is higher than the HOMO of the above-mentioned infrared absorber.

[0300] Relationship between electron-accepting polymerization initiator and infrared absorber

[0301] In the image recording layer of the present application, from the viewpoints of sensitivity improvement and print durability, the value of LUMO of the above-mentioned electron- accepting polymerization initiator - LUMO of the above-mentioned infrared absorber is preferably 1.00 eV or less, more preferably 0.80 eV or less, further preferably 0.70 eV or less, particularly preferably 0.70 eV to -0.10 eV, and most preferably 0.70 eV to 0.30 eV.

[0302] Further, the negative value means that the LUMO of the above-mentioned infrared absorber is higher than the LUMO of the above-mentioned electron- accepting polymerization initiator.

[0303] In the present application, the calculation of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is performed by the following method.

[0304] First, free counter ions in the compound as the calculation object are excluded from the calculation object. For example, in the case of a cationic electron- accepting polymerization initiator and a cationic infrared absorber, the counter anion is excluded from the calculation object, and in the case of an anionic electron- donating polymerization initiator, the counter cation is excluded from the calculation object. The free here means that the compound as the object is not linked to the counter ion by a covalent bond.

[0305] The structure optimization is performed under DFT (B3LYP / 6-31G(d)) using quantum chemistry calculation software Gaussian09.

[0306] Regarding the MO (molecular orbital) energy calculation, the structure obtained by the above-mentioned structure optimization is subjected to calculation under DFT (B3LYP / 6-31+G(d,p) / CPCM (solvent = methanol)).

[0307] The MO energy Ebare (unit: Hartree) obtained by the above MO energy calculation is converted into Escaled (unit: eV) which is used as the value of HOMO and LUMO in the present application according to the following formula.

[0308] Escaled = 0.823168 x 27.2114 x Ebare - 1.07634

[0309] Further, 27.2114 is a coefficient for converting Hartree into eV only, and 0.823168 and -1.07634 are adjustment coefficients, and the HOMO and LUMO of the compound which becomes the calculation object are determined so as to match the calculation with the measured value.

[0310] [Polymerizable compound]

[0311] The image recording layer in the present application contains a polymerizable compound.

[0312] In the present application, the polymerizable compound refers to a compound having a polymerizable group.

[0313] There is no particular limitation on the polymerizable group as long as it is a publicly known polymerizable group, but an ethylenically unsaturated group is preferred. Also, the polymerizable group can be a radical polymerizable group or a cationic polymerizable group, but a radical polymerizable group is preferred.

[0314] As the radical polymerizable group, (meth)acryloyl group, allyl group, vinylphenyl group, vinyl group, etc. can be mentioned, and from the viewpoint of reactivity, (meth)acryloyl group is preferred.

[0315] The molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the polymerizable compound is preferably 50 or more and less than 2,500.

[0316] The polymerizable compound used in the present application can be a radical polymerizable compound or a cationic polymerizable compound, and is preferably an addition polymerizable compound (ethylenically unsaturated compound) having at least one ethylenically unsaturated bond.

[0317] As the ethylenically unsaturated compound, a compound having at least one terminal ethylenically unsaturated bond is preferred, and a compound having two or more terminal ethylenically unsaturated bonds is more preferred. The polymerizable compound has, for example, a chemical form such as a monomer, a prepolymer (dimer, trimer or oligomer) or a mixture thereof.

[0318] Among them, as the above-mentioned polymerizable compound, from the viewpoint of UV printing durability, a polymerizable compound containing 3 or more functional groups is preferable, a polymerizable compound containing 7 or more functional groups is more preferable, and a polymerizable compound containing 10 or more functional groups is further preferable. Also, from the viewpoint of UV printing durability in the obtained lithographic printing plate, the above-mentioned polymerizable compound preferably contains 3 or more (preferably 7 or more, and more preferably 10 or more) ethylenically unsaturated compounds, and further preferably contains 3 or more (preferably 7 or more, and more preferably 10 or more) (meth)acrylate compounds.

[0319] <<oligomer>>

[0320] As the polymerizable compound contained in the image-recording layer, a polymerizable compound containing an oligomer (hereinafter, also simply referred to as "oligomer") is preferable.

[0321] In the present application, the oligomer means a polymerizable compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of 600 or more and less than 10,000, and containing at least one polymerizable group.

[0322] 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.

[0323] Also, 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.

[0324] Also, the upper limit value of the number of polymerizable groups in the oligomer is not particularly limited, but the number of polymerizable groups is preferably 20 or less.

[0325] From the viewpoint of UV printing durability and on-press developability, the number of polymerizable groups in the oligomer is preferably 7 or more, and the molecular weight is 1,000 or more and less than 10,000, and more preferably the number of polymerizable groups is 7 or more and 20 or less, and the molecular weight is 1,000 or more and 5,000 or less.

[0326] In addition, a polymer component that can be generated in the process of producing the oligomer can be contained.

[0327] From the viewpoint of UV printing durability, visual recognition, and on-press developability, the oligomer preferably has at least one selected from the group consisting of a compound having a urethane bond, a compound having an ester bond, and a compound having an epoxy residue, and more preferably has a compound having a urethane bond.

[0328] In the present application, an epoxy residue refers to a structure formed from an epoxy group, for example, a structure representing the same structure as that obtained by the reaction of an acid group (carboxylic acid group, etc.) with an epoxy group.

[0329] As an example of the compound having a urethane bond, for example, a compound having at least a group represented by the following formula (Ac-1) or formula (Ac-2) is preferable, and a compound having at least a group represented by the following formula (Ac-1) is more preferable.

[0330] [Chemical Formula 28]

[0331]

[0332] In formula (Ac-1) and formula (Ac-2), L 1 ~L 4 Each independently represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and the wavy line portion represents a bonding position with other structures.

[0333] As L 1 ~L 4 Each independently is preferably an alkylene group having 2 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms, and further preferably an alkylene group having 4 to 8 carbon atoms. Furthermore, the above alkylene group can have a branched chain or a ring structure, but is preferably a straight chain alkylene group.

[0334] The wavy line portion in formula (Ac-1) or formula (Ac-2) is preferably directly bonded to the wavy line portion in a group represented by the following formula (Ae-1) or formula (Ae-2), respectively.

[0335] [Chemical Formula 29]

[0336]

[0337] 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 with the wavy line portion in formula (Ac-1) and formula (Ac-2).

[0338] Furthermore, as the compound having a urethane bond, a compound in which a polymerizable group is introduced to a polyurethane obtained by the reaction of a polyisocyanate compound with a polyol compound by a polymer reaction can be used.

[0339] For example, the 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.

[0340] The number of polymerizable groups in the compound having an ester bond exemplified as the oligomer is preferably 3 or more, and further preferably 6 or more.

[0341] The compound having an epoxy residue exemplified as the oligomer is preferably a compound containing a hydroxyl group within the compound.

[0342] The number of polymerizable groups in the compound having an epoxy residue is preferably 2 to 6, and more preferably 2 to 3.

[0343] The compound having an epoxy residue exemplified above can be obtained, for example, by reacting acrylic acid with a compound having an epoxy group.

[0344] Specific examples of the oligomer are exemplified below, but the oligomer used in the present application is not limited thereto.

[0345] As the oligomer, commercially available products can be used, and examples thereof include UA-510H, UA-306H, UA-306I, UA-306T (all manufactured by KYOEISHA CHEMICAL CO., LTD.), UV-1700B, UV-6300B, UV7620EA (all manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), U-15HA (manufactured by Shin-Nakamura Chemical Co., Ltd.), EBECRYL 450, EBECRYL 657, EBECRYL 885, EBECRYL 800, EBECRYL 3416, EBECRYL 860 (all manufactured by DAICEL-ALLNEX LTD.), and the like, but is not limited thereto.

[0346] From the viewpoint of improving chemical resistance, UV printing durability, and inhibition 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 further preferably 80% by mass to 100% by mass, with respect to the total mass of the polymerizable compound in the image-recording layer.

[0347] <<Low Molecular Polymerizable Compound>>

[0348] The polymerizable compound can further include a polymerizable compound other than the above-described oligomer.

[0349] As the polymerizable compound other than the oligomer, from the viewpoint of chemical resistance, a low molecular polymerizable compound is preferred. As the low molecular polymerizable compound, it can be in a chemical form such as a monomer, a dimer, a trimer, or a mixture thereof.

[0350] Further, as the low molecular weight polymerizable compound, from the viewpoint of chemical resistance, at least one polymerizable compound selected from the group consisting of a polymerizable compound having three or more ethylenically unsaturated groups and a polymerizable compound having an isocyanurine ring structure is preferable.

[0351] In the present application, the low molecular weight polymerizable compound means a polymerizable compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of 50 or more and less than 600.

[0352] As the molecular weight of the low molecular weight polymerizable compound, from the viewpoint of excellent chemical resistance, UV print durability, and inhibition of on-press development residue, it is preferable to be 100 or more and less than 600, more preferable to be 300 or more and less than 600, and further preferable to be 400 or more and less than 600.

[0353] In the case where the polymerizable compound contains a low molecular weight polymerizable compound as a polymerizable compound other than the oligomer (in the case of containing two or more low molecular weight polymerizable compounds, the total amount thereof), from the viewpoint of chemical resistance, UV print durability, and inhibition of on-press development residue, the ratio of the above oligomer to the low molecular weight polymerizable compound (oligomer / low molecular weight polymerizable compound) is preferably 10 / 1 to 1 / 10, more preferably 10 / 1 to 3 / 7, and further preferably 10 / 1 to 7 / 3 on a mass basis.

[0354] Further, as the low molecular weight polymerizable compound, the polymerizable compound described in paragraphs 0082 to 0086 of International Publication No. 2019 / 013268 can also be preferably used.

[0355] From the viewpoint of inhibition of spot-like color defects and on-press developability, the above image recording layer preferably contains a polymerizable compound having a molecular weight of 2,500 or less.

[0356] As the polymerizable compound having a molecular weight of 2,500 or less, a compound having a molecular weight of 2,500 or less among the above oligomers and the above low molecular weight polymerizable compound are preferably selected.

[0357] Further, from the viewpoint of UV print durability, inhibition of spot-like color defects, and on-press developability, the polymerizable compound having a molecular weight of 2,500 or less preferably contains a polymerizable compound having 7 or more functions, and more preferably contains a polymerizable compound having 10 or more functions.

[0358] From the viewpoint of the inhibition of the spot-like color defects and the on-press developability, the content of the polymerizable compound having a molecular weight of 2,500 or less is preferably 60% by mass or less, more preferably 50% by mass or less, further preferably 15% by mass to 50% by mass, and particularly preferably 25% by mass to 45% by mass, with respect to the total mass of the image recording layer.

[0359] Further, from the viewpoint of the inhibition of the spot-like color defects and the on-press developability, the image recording layer preferably contains a polymer having a weight average molecular weight of 10,000 or more as the polymerizable compound.

[0360] The polymer having a weight average molecular weight of 10,000 or more is not particularly limited, and a polymer having a well-known polymerizable group and having a weight average molecular weight of 10,000 or more can be used.

[0361] From the viewpoint of the inhibition of the spot-like color defects and the on-press developability, the content of the polymer having a weight average molecular weight of 10,000 or more is more preferably 5% by mass or more, and more preferably 10% by mass or more, with respect to the total mass of the image recording layer.

[0362] Further, the content of the polymer having a weight average molecular weight of 10,000 or more is preferably 45% by mass or less, and more preferably 35% by mass or less, with respect to the total mass of the image recording layer.

[0363] Further, the polymer having a weight average molecular weight of 10,000 or more preferably has an ethylenic unsaturated group, and more preferably is a polymer having a weight average molecular weight of 10,000 or more and 150,000 or less and an ethylenic unsaturated bond value of 3.0 mmol / g or more.

[0364] From the viewpoint of the UV printing durability, the weight average molecular weight (Mw) of the polymer having a weight average molecular weight of 10,000 or more is preferably more than 15,000 and 150,000 or less, more preferably 20,000 or more and 150,000 or less, further preferably 40,000 or more and 150,000 or less, and particularly preferably 70,000 or more and 150,000 or less.

[0365] Further, from the viewpoint of the developability, the weight average molecular weight of the polymer having a weight average molecular weight of 10,000 or more is preferably 130,000 or less.

[0366] From the viewpoint of the durability of UV printing, the value of the ethylenic unsaturated bond (also referred to as "C=C value") of the above polymer having a weight average molecular weight of 10,000 or more is preferably 3.0 mmol / g or more, more preferably 5.0 mmol / g or more, more preferably 4.5 mmol / g to 12.0 mmol / g, further preferably 5.0 mmol / g to 10.0 mmol / g, and particularly preferably 5.5 mmol / g to 8.5 mmol / g.

[0367] The value of the ethylenic unsaturated bond in the polymerizable compound can be calculated by the following method.

[0368] First, the total amount (mmol) of the ethylenic unsaturated group is determined for a compound of a prescribed sample amount (for example, 0.2 g) using pyrolysis GC / MS, FT-IR, NMR, TOF-SIMS, or the like, for example, to determine the structure of the compound. The value of the ethylenic unsaturated bond in the compound is calculated by dividing the total amount (mmol) of the ethylenic unsaturated group thus determined by the sample amount (g) of the compound.

[0369] The structure of the above polymer having a weight average molecular weight of 10,000 or more is not particularly limited, and can be a graft polymer, a star polymer, a hyperbranched polymer, a dendrimer, or the like, for example, but as described later, a polymer obtained by sealing the terminal isocyanate groups of a multimer (including adducts) of a polyfunctional isocyanate compound with a compound having an ethylenic unsaturated group is preferred.

[0370] From the viewpoint of the durability of UV printing, the above polymer having a weight average molecular weight of 10,000 or more preferably has a hydrogen bonding group, and more preferably has three or more hydrogen bonding groups.

[0371] As for the above hydrogen bonding group, it can be any group that can hydrogen bond, and can be a hydrogen bond-donating group, a hydrogen bond-accepting group, or both.

[0372] As the above hydrogen bonding group, a hydroxyl group, a carboxyl group, an amino group, a carbonyl group, a sulfonyl group, a carbamate group, a urea group, an imide group, an amide group, a sulfonamide group, or the like can be given.

[0373] Among these, from the viewpoint of the durability of UV printing, the above hydrogen bonding group is preferably at least one selected from the group consisting of a carbamate group, a urea group, an imide group, an amide group, and a sulfonamide group, more preferably at least one selected from the group consisting of a carbamate group, a urea group, an imide group, and an amide group, further preferably at least one selected from the group consisting of a carbamate group, a urea group, and an imide group, and particularly preferably at least one selected from the group consisting of a carbamate group and a urea group.

[0374] Further, from the viewpoint of UV printing durability, the polymer having a weight average molecular weight of 10,000 or more is preferably one having a polymerizable group.

[0375] As the polymerizable group, it can be a cationic polymerizable group or a radical polymerizable group, but from the viewpoint of reactivity, it is preferably a radical polymerizable group.

[0376] As the polymerizable group, there is no particular limitation, but from the viewpoints of reactivity, UV printing durability, and UV plate wear inhibition, it is preferably an ethylenically unsaturated group, more preferably at least one group selected from the group consisting of a vinylphenyl group (styryl group), a vinyl ester group, a vinyl ether group, an allyl group, a (meth)acryloyloxy group, and a (meth)acrylamide group, further preferably at least one group selected from the group consisting of a vinylphenyl group (styryl group), a (meth)acryloyloxy group, and a (meth)acrylamide group, and particularly preferably a (meth)acryloyloxy group.

[0377] Further, from the viewpoints of UV printing durability and UV plate wear inhibition, the polymer having a weight average molecular weight of 10,000 or more is preferably one having a structure represented by the following formula (Po-1) or formula (Po-2) as the polymerizable group, and more preferably one having a structure represented by the following formula (Po-1).

[0378] [Chemical Formula 30]

[0379]

[0380] In formula (Po-1) and formula (Po-2), R P Each independently represents an acryloyl group or a methacrylic acid group, and the wavy line portion represents a bonding position to other structures.

[0381] In formula (Po-1) or formula (Po-2), R P are the same group.

[0382] Further, in formula (Po-1) or formula (Po-2), R P is preferably an acryloyl group.

[0383] Further, from the viewpoints of UV printing durability and UV plate wear inhibition, the polymer having a weight average molecular weight of 10,000 or more is preferably a (meth)acrylate compound having a urethane group, i.e., a urethane (meth)acrylate.

[0384] Further, from the viewpoint of UV printing durability and UV plate wear inhibition, the polymer having a weight average molecular weight of 10,000 or more is preferably a polymer having a structure in which a multifunctional isocyanate compound is polymeric, and is more preferably a polymer having a structure in which a difunctional isocyanate compound is polymeric.

[0385] Further, from the viewpoint of UV printing durability and UV plate wear inhibition, the polymer having a weight average molecular weight of 10,000 or more is preferably a polymer having a structure in which a multifunctional isocyanate compound is polymeric, and is more preferably a polymer having a structure in which a difunctional isocyanate compound is polymeric, and is particularly preferably a polymer having a structure in which a multifunctional isocyanate compound is polymeric.

[0386] As the multifunctional isocyanate compound, there is no particular limitation, and a publicly known multifunctional isocyanate compound can be used. It can be an aliphatic multifunctional isocyanate compound or an aromatic multifunctional isocyanate compound.

[0387] As the multifunctional isocyanate compound, specifically, for example, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,3-cyclopentane diisocyanate, 9H-fluorene-2,7-diisocyanate, 9H-fluorene-9-ketone-2,7-diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, 1,5-naphthalene diisocyanate, dimers and trimers (isocyanurate bonds) of these polyisocyanates, and the like are preferably selected. Further, a biuret body obtained by reacting the above polyisocyanate compound with a publicly known amine compound can be used.

[0388] Further, the multifunctional isocyanate compound having a hydroxyl group is preferably a 3-functional or more aliphatic unsaturated compound having a hydroxyl group, and is more preferably a 5-functional or more aliphatic unsaturated compound having a hydroxyl group.

[0389] Further, the above-mentioned multifunctional olefinically unsaturated compound having a hydroxyl group is preferably a multifunctional (meth)acrylate compound having a hydroxyl group.

[0390] From the viewpoint of UV printing durability and UV plate wear inhibitory properties, the above-mentioned polymer having a weight average molecular weight of 10,000 or more preferably has at least one structure selected from the group consisting of an adduct structure, a biuret structure, and an isocyanurate structure, more preferably has at least one structure selected from the group consisting of a trimethylolpropane adduct structure, a biuret structure, and an isocyanurate structure, and particularly preferably has a trimethylolpropane adduct structure.

[0391] Further, from the viewpoint of UV printing durability and UV plate wear inhibitory properties, the above-mentioned polymer having a weight average molecular weight of 10,000 or more preferably has a structure represented by any one of the following Formulae (A-1) to (A-3), and more preferably has a structure represented by the following Formula (A-1).

[0392] [Chemical Formula 31]

[0393]

[0394] In Formula (A-1), R A1 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and the wavy line portion represents a bonding position to other structures.

[0395] From the viewpoint of UV printing durability and UV plate wear inhibitory properties, R A1 in Formula (A-1) is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, further preferably a methyl group or an ethyl group, and particularly preferably an ethyl group.

[0396] The above-mentioned polymer having a weight average molecular weight of 10,000 or more preferably contains a resin represented by the following Formula (I).

[0397] A P -(B P ) nP Formula (I)

[0398] In Formula (I), A P represents an nP-valent organic group having a hydrogen-bonding group, B P represents a group having 2 or more polymerizable groups, and nP represents an integer of 2 or more.

[0399] The hydrogen-bonding group in A P in Formula (I) is preferably the same as the above-mentioned preferred hydrogen-bonding group.

[0400] A P in Formula (I) is preferably an organic group having no olefinic unsaturated bond.

[0401] and A in formula (I) is P is preferably a monovalent ~ nP-valent aliphatic hydrocarbon group, a monovalent ~ nP-valent aromatic hydrocarbon group, a group formed by combining two or more structures selected from a urethane bond, a urea bond, a biuret bond, and an allophanate bond, more preferably a monovalent ~ nP-valent aliphatic hydrocarbon group, a monovalent ~ nP-valent aromatic hydrocarbon group, a group formed by combining two or more structures selected from a urethane bond, a urea bond, and a biuret bond.

[0402] and A in formula (I) is P is preferably a group obtained by removing a terminal isocyanate group from a polymeric compound (including an adduct of a polyfunctional alcohol compound) obtained by polymericization of a polyfunctional isocyanate compound, more preferably a group obtained by removing a terminal isocyanate group from a polymeric compound (including an adduct of a polyfunctional alcohol compound) obtained by polymericization of a difunctional isocyanate compound, and particularly preferably a group obtained by removing a terminal isocyanate group from a polymeric compound (including an adduct of a polyfunctional alcohol compound) obtained by polymericization of hexamethylene diisocyanate.

[0403] and A in formula (I) is P The weight average molecular weight (Mw) of the compound of formula (I) is preferably 10,000 or more and 145,000 or less, more preferably 30,000 or more and 140,000 or less, and particularly preferably 60,000 or more and 140,000 or less.

[0404] and A in formula (I) is P The weight average molecular weight of the compound of formula (I) is preferably 120,000 or less.

[0405] B in formula (I) is P The preferable mode of the polymerizable group in B in formula (I) is the same as the preferable mode of the polymerizable group described above.

[0406] wherein the polymerizable group in B in formula (I) preferably contains a (meth)acryloyloxy group, B in formula (I) is P wherein the polymerizable group in B in formula (I) preferably contains a (meth)acryloyloxy group, B in formula (I) is P more preferably a group having 3 or more (meth)acryloyloxy groups, further preferably a group having 5 or more (meth)acryloyloxy groups, and particularly preferably a group having 5 or more and 12 or less (meth)acryloyloxy groups.

[0407] wherein the polymerizable group in B in formula (I) preferably contains a (meth)acryloyloxy group, B in formula (I) isP The structure is preferably represented by the above formula (Po-1) or formula (Po-2), and more preferably by the structure represented by the above formula (Po-1).

[0408] Moreover, the preferred formula (I) of B P They are all the same group.

[0409] Furthermore, from the perspective of UV printing durability and UV plate wear inhibition, B in formula (I) P The molecular weight is preferably 300 or more and 1,000 or less, more preferably 400 or more and 800 or less.

[0410] Furthermore, in equation (I), from the viewpoint of UV printing durability and UV plate wear inhibition, A P Weight-average molecular weight / (B P The value of (molecular weight × nP) is preferably 1 or less, more preferably 0.1 or more and 0.9 or less, and especially preferably 0.2 or more and 0.8 or less.

[0411] The details of the polymeric compound's structure, whether it is used alone or in combination, the amount added, and other usage methods can be set arbitrarily.

[0412] From the perspective of UV printing durability, the image recording layer preferably contains two or more polymeric compounds.

[0413] The content of polymeric compounds (the total content of polymeric compounds when two or more polymeric compounds are included) is preferably 5% to 75% by mass, more preferably 10% to 70% by mass, and even more preferably 15% to 60% by mass, relative to the total mass of the image recording layer.

[0414] 〔particle〕

[0415] From the viewpoint of developability and UV printing durability, the image recording layer in this invention preferably contains particles. These particles can be inorganic or organic.

[0416] The particles preferably include organic particles, and more preferably resin particles.

[0417] As inorganic particles, known inorganic particles can be used, and metal oxide particles such as silicon dioxide particles and titanium dioxide particles can be preferred.

[0418] <<Resin Particles>>

[0419] As the resin particles, for example, there can be mentioned particles containing an addition polymerization type resin (i.e., addition polymerization type resin particles), particles containing a polyaddition type resin (i.e., polyaddition type resin particles), particles containing a polycondensation type resin (i.e., polycondensation type resin particles), and the like, but among them, addition polymerization type resin particles or polyaddition type resin particles are preferred.

[0420] Further, as the resin particles, from the viewpoint of being able to be heat-fused, there can be particles containing a thermoplastic resin (i.e., thermoplastic resin particles).

[0421] Further, the resin particles can be in the form of microcapsules, microgels (i.e., crosslinked resin particles), and the like.

[0422] As the resin particles, it is preferred to be selected from among thermoplastic resin particles, thermally reactive resin particles, resin particles having a polymerizable group, microcapsules containing a hydrophobic compound, and microgels (crosslinked resin particles). Among them, resin particles having a polymerizable group are preferred.

[0423] In an especially preferred embodiment, the resin particles contain at least one olefinic unsaturated group. Due to the presence of such resin particles, it is possible to obtain the effect of improving the print durability of the exposed portions and the on-press developability of the unexposed portions.

[0424] As the thermoplastic resin particles, it is preferred to be the thermoplastic resin particles described in Research Disclosure No. 33303, January 1992, Japanese Patent Application Laid-Open No. 9-123387, Japanese Patent Application Laid-Open No. 9-131850, Japanese Patent Application Laid-Open No. 9-171249, Japanese Patent Application Laid-Open No. 9-171250, and European Patent No. 931647, and the like.

[0425] As specific examples of the resin constituting the thermoplastic resin particles, there can be mentioned homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, acrylate or methacrylate having a polyalkylene structure, and mixtures thereof.

[0426] As the thermoplastic resin particles, from the viewpoints of ink adhesion and UV print durability, it is preferred to contain a resin having a constitutional unit formed from an aromatic vinyl compound and a constitutional unit having a nitrile group.

[0427] As the above-mentioned aromatic vinyl compound, there can be mentioned compounds having a structure in which a vinyl group is bonded to an aromatic ring, but there can be mentioned styrene compounds, vinyl naphthalene compounds, and the like, with styrene compounds being preferred, and styrene being more preferred.

[0428] As the styrene compound, styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene, etc. can be mentioned, and styrene is preferred.

[0429] From the viewpoint of ink adhesion, the content of the constitutional unit formed from the aromatic vinyl compound is preferably more than the content of the constitutional unit having a nitrile group described later, and more preferably 15 to 85 mass% and further preferably 30 to 70 mass% with respect to the total mass of the thermoplastic resin.

[0430] The constitutional unit having a nitrile group is preferably introduced using a monomer having a nitrile group.

[0431] As the monomer having a nitrile group, an acrylonitrile compound can be mentioned, and (meth)acrylonitrile is preferred.

[0432] As the constitutional unit having a nitrile group, a constitutional unit formed from (meth)acrylonitrile is preferred.

[0433] From the viewpoint of ink adhesion, the content of the constitutional unit having a nitrile group is preferably less than the content of the constitutional unit formed from the aromatic vinyl compound described above, and more preferably 55 to 90 mass% and further preferably 60 to 85 mass% with respect to the total mass of the resin.

[0434] Also, in the case where the resin contained in the thermoplastic resin particles contains the constitutional unit formed from the aromatic vinyl compound and the constitutional unit having a nitrile group, the content ratio of the constitutional unit formed from the aromatic vinyl compound and the constitutional unit having a nitrile group (constitutional unit formed from the aromatic vinyl compound : constitutional unit having a nitrile group) is preferably 5 : 5 to 9 : 1 and more preferably 6 : 4 to 8 : 2 on a mass basis.

[0435] From the viewpoint of UV printing durability and chemical resistance, the resin contained in the thermoplastic resin particles preferably further has a constitutional unit formed from an N-vinyl heterocyclic compound.

[0436] As the N-vinyl heterocyclic compound, for example, N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam, and N-vinylimidazole can be mentioned, and N-vinylpyrrolidone is preferred.

[0437] The content of the constitutional unit formed from the N-vinyl heterocyclic compound is preferably 5 to 50 mass% and more preferably 10 to 40 mass% with respect to the total mass of the thermoplastic resin.

[0438] The resin contained in the thermoplastic resin particles can contain a constitutional unit having an acidic group, but from the viewpoints of on-press developability and ink adhesion, it is preferable that the constitutional unit having an acidic group be not contained.

[0439] Specifically, the content of the constitutional unit having an acidic group in the thermoplastic resin is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less. The lower limit of the above content is not particularly limited and can be 0% by mass.

[0440] Further, the acid value of the thermoplastic resin is preferably 160 mgKOH / g or less, more preferably 80 mgKOH / g or less, and further preferably 40 mgKOH / g or less. The lower limit of the above acid value is not particularly limited and can be 0 mgKOH / g.

[0441] In the present application, the acid value is found by a measurement method in accordance with JIS K0070:1992.

[0442] From the viewpoint of ink adhesion, the resin contained in the thermoplastic resin particles can contain a constitutional unit containing a hydrophobic group.

[0443] As the above hydrophobic group, an alkyl group, an aryl group, an aralkyl group, and the like can be given.

[0444] As the constitutional unit containing a hydrophobic group, a constitutional unit formed of an alkyl (meth)acrylate compound, an aryl (meth)acrylate compound, or an aralkyl (meth)acrylate compound is preferable, and a constitutional unit formed of an alkyl (meth)acrylate compound is more preferable.

[0445] The content of the constitutional unit having a hydrophobic group in the resin contained in the thermoplastic resin particles is preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 30% by mass, with respect to the total mass of the resin.

[0446] From the viewpoints of UV printing durability and on-press developability, the thermoplastic resin contained in the thermoplastic resin particles preferably has a hydrophilic group.

[0447] As the hydrophilic group, if it is a structure having a hydrophilic property, there is no particular limitation, but an acid group such as a carboxyl group, a hydroxyl group, an amino group, a nitrile group, a polyalkylene oxide structure, and the like can be given.

[0448] As the above hydrophilic group, from the viewpoints of UV printing durability and on-press developability, a group having a polyalkylene oxide structure, a group having a polyester structure, or a sulfonic acid group is preferable, a group having a polyalkylene oxide structure or a sulfonic acid group is more preferable, and a group having a polyalkylene oxide structure is further preferable.

[0449] 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 preferable.

[0450] Further, from the viewpoint of on-press developability, among the above hydrophilic groups, as the polyalkylene oxide structure, a polypropylene oxide structure is preferable, and a polyethylene oxide structure and a polypropylene oxide structure are further preferable.

[0451] From the viewpoint of on-press developability, the number of alkylene oxide structures in the above polyalkylene oxide structure is preferably 2 or more, more preferably 5 or more, further preferably 5 to 200, and particularly preferably 8 to 150.

[0452] Further, from the viewpoint of on-press developability, as the above hydrophilic group, a group represented by Formula Z described later is preferable.

[0453] Among the hydrophilic groups possessed by the thermoplastic resin, a group represented by Formula PO described below is preferable.

[0454] [Chemical Formula 32]

[0455]

[0456] In Formula PO, L P Each independently represents an alkylene group, R P represents a hydrogen atom or an alkyl group, n represents an integer of 1 to 100, and * represents a bonding position to other structures.

[0457] In Formula PO, L P Each independently is preferably an ethylene group, a 1-methylethylene group, or a 2-methylethylene group, and more preferably an ethylene group.

[0458] In Formula PO, R P 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.

[0459] In Formula PO, n is preferably an integer of 1 to 10, and more preferably an integer of 1 to 4.

[0460] The content of the constitutional unit having the hydrophilic group is preferably 5% by mass to 60% by mass, and more preferably 10% by mass to 30% by mass, with respect to the total mass of the resin.

[0461] The resin included in the thermoplastic resin particles can further contain other constitutional units. As the other constitutional units, constitutional units other than the above constitutional units can be contained without particular limitation, and for example, constitutional units formed from an acrylamide compound, a vinyl ether compound, or the like can be mentioned.

[0462] The content of other constitutional units in the resin contained in the thermoplastic resin particles, relative to the total mass of the resin, is preferably 5 to 50 mass%, more preferably 10 to 30 mass%.

[0463] As the thermally reactive resin particles, resin particles having a thermally reactive group can be given. The thermally reactive resin particles form a hydrophobic region by crosslinking based on thermal reaction and a change in functional group at the time of crosslinking.

[0464] As the thermally reactive group in the resin particles having a thermally reactive group, as long as a chemical bond can be formed, any reactive functional group can be given, but a polymerizable group is preferred, and as examples thereof, an ethylenically unsaturated group (e.g., acryloyl group, methacryloyl group, vinyl group, allyl group, etc.) that undergoes radical polymerization, a cationically polymerizable group (e.g., vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.), an isocyanate group or a block thereof that undergoes addition reaction, an epoxy group, a vinyloxy group, and a functional group having an active hydrogen atom as a target of reaction thereof (e.g., amino group, hydroxyl group, carboxyl group, etc.), a carboxyl group and a hydroxyl group or an amino group as a target of reaction, an acid anhydride and an amino group or a hydroxyl group as a target of reaction that undergo ring-opening addition reaction, etc. are preferably given.

[0465] As the resin having the above thermally reactive group, an addition polymerization type resin, a polyaddition type resin, or a polycondensation type resin can be given, and a thermoplastic resin can also be given.

[0466] As the microcapsule, for example, a microcapsule that contains at least a part of the components (preferably, a hydrophobic compound) constituting the image recording layer in the inside thereof, as described in Japanese Patent Application Publication No. 2001-277740, Japanese Patent Application Publication No. 2001-277742, is preferred. A preferred form of the image recording layer containing the microcapsule as the resin particles is a structure in which a hydrophobic component (i.e., a hydrophobic compound) of the components constituting the image recording layer is contained in the inside of the microcapsule, and a hydrophilic component (i.e., a hydrophilic compound) is contained outside the microcapsule.

[0467] The microgel (crosslinked resin particles) can contain a part of the components constituting the image recording layer in at least one of the surface or the inside thereof. In particular, from the viewpoint of the sensitivity of the lithographic printing plate precursor and the printing durability of the obtained lithographic printing plate, a reactive microgel having a polymerizable group on the surface thereof is preferred.

[0468] In order to obtain a microcapsule containing the components constituting the image recording layer, a publicly known synthesis method can be applied.

[0469] The microgel (crosslinked resin particles) can have at least one of the surface or the inside thereof contain a part of the constituent components of the image recording layer. In particular, from the viewpoint of the sensitivity of the lithographic printing plate precursor and the printing durability of the obtained lithographic printing plate, it is preferable that the reactive microgel have a polymerizable group on the surface thereof.

[0470] In order to obtain the microgel containing the constituent components of the image recording layer, a publicly known synthesis method can be applied

[0471] As the resin particles, from the viewpoint of the printing durability, the stain resistance, and the storage stability of the obtained lithographic printing plate, it is preferable that the resin particles be addition polymerization type resin particles having a hydrophobic backbone and containing both i) a constituent unit having a nitrile group directly bonded to the hydrophobic backbone and ii) a constituent unit having a side group containing a hydrophilic polyalkylene oxide segment. Specifically, it is preferable that the particles described in paragraph 0156 of Japanese Patent Application Publication No. 2019-64269 be used.

[0472] As the above-mentioned polyhydric phenol compound, it is preferable that a compound having a plurality of benzene rings having a phenolic hydroxyl group be used.

[0473] As the compound having the above-mentioned active hydrogen, it is preferable that a polyol compound or a polyamine compound be used, and more preferably a polyol compound. Further, it is preferable that at least one compound selected from the group consisting of propylene glycol, glycerol, and trimethylolpropane be used. Also, as the above-mentioned active hydrogen compound, water can be used. In the case where water is used, an amine generated by the reaction of an isocyanate group with water can form a urea bond, and thus the particles can be formed.

[0474] As the particles of the resin obtained by the reaction of the polyisocyanate compound which is an adduct of a polyhydric phenol compound having 2 or more hydroxyl groups in the molecule and isophorone diisocyanate and the compound having an active hydrogen, it is preferable that the resin particles described in paragraphs 0230 to 0234 of International Publication No. 2018043259 be selected.

[0475] Further, as the resin particles, from the viewpoint of the printing durability and the solvent resistance of the obtained lithographic printing plate, it is preferable that the addition polymerization type resin particles have a hydrophobic backbone and contain both i) a constituent unit having a nitrile group directly bonded to the hydrophobic backbone and ii) a constituent unit having a side group containing a hydrophilic polyalkylene oxide segment. Specifically, it is preferable that the particles described in paragraph 0156 of Japanese Patent Application Publication No. 2019-64269 be used.

[0476] < Group represented by Formula Z >

[0477] The resin particles in the present application preferably have a group represented by the following Formula Z as a hydrophilic group.

[0478] *-Q-W-Y Formula Z

[0479] 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 other structures.

[0480] Also, it is preferable that the hydrophilic structures included in formula Z each include a polyalkylene oxide structure.

[0481] Q in 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.

[0482] Also, Q in 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.

[0483] The divalent group having a hydrophilic structure in W in formula Z is preferably a group including a polyalkylene oxide structure, and preferably a polyalkyleneoxy group or a group in which -CH2CH2NR W - is bonded to one terminal of a polyalkyleneoxy group. Also, R W represents a hydrogen atom or an alkyl group.

[0484] The divalent group having a hydrophobic structure in W in formula Z is preferably -R WA -, -O-R WA -O-, -R w N-R WA -NR W -, -OC(=O)-R WA -O-, or -OC(=O)-R WA -O-. Also, 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 6 to 120 carbon atoms, or an aralkylene group having 6 to 120 carbon atoms.

[0485] The monovalent group having a hydrophilic structure in Y in formula Z is preferably -OH, -C(=O)OH, a polyalkyleneoxy group in which one terminal is a hydrogen atom or an alkyl group or in which the other terminal is bonded to -CH2CH2N(R Wgroup represented by the formula Z. Among them, as the monovalent group having a hydrophilic structure, a group containing a polyalkylene oxide structure is preferable, and a polyalkylene oxide group having a hydrogen atom or an alkyl group at the terminal or a polyalkylene oxide group having a hydrogen atom or an alkyl group at the other terminal bonded to -CH2CH2N(R W )- group.

[0486] 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 alkylaryl (alkylaryl) group having 6 to 120 carbon atoms, an arylalkyl group having 6 to 120 carbon atoms, -OR WB , -C(=O)OR WB , or -OC(=O)R WB . R WB represents an alkyl group having 6 to 20 carbon atoms.

[0487] In the resin particle having a group represented by the above formula Z, from the viewpoints of print durability, ink receptivity and on-press developability, it is more preferable that W be a divalent group having a hydrophilic structure, it is more preferable that Q be a phenylene group, an ester bond or an amide bond, W be a polyalkylene oxide group, and Y be a polyalkylene oxide group having a hydrogen atom or an alkyl group at the terminal.

[0488] In addition, the group represented by the formula Z can function as a dispersibility group for improving the dispersibility of the resin particle.

[0489] From the viewpoints of print durability and on-press developability, the resin particle in the present application preferably has a polymerizable group (preferably an olefinically unsaturated group), and it is more preferable to contain a resin particle having a polymerizable group particularly on the surface. By using a resin particle having a polymerizable group, plate wear (preferably UV plate wear) can be easily suppressed, and print durability (preferably UV print durability) can be improved.

[0490] From the viewpoint of print durability, the resin particle in the present application is preferably a resin particle having a hydrophilic group and a polymerizable group.

[0491] The above polymerizable group can be a cationic polymerizable group or a free radical polymerizable group, but from the viewpoint of reactivity, a free radical polymerizable group is preferable.

[0492] As the above polymerizable group, there is no particular limitation as long as it is a group that can be polymerized, but from the viewpoint of reactivity, an olefinically unsaturated group is preferable, a vinylphenyl group (styryl group), a (meth)acryloxy group or a (meth)acrylamido group is more preferable, and a (meth)acryloxy group is particularly preferable.

[0493] Further, the resin constituting the resin particles having a polymerizable group preferably has a constituting unit having a polymerizable group.

[0494] Further, the polymerizable group can be introduced to the surface of the resin particles by a polymer reaction.

[0495] Further, from the viewpoints of print durability, ink receptivity, on-press developability, and development residue inhibitory property during on-press development, the resin particles preferably contain an addition polymerization type resin having a urea bond, more preferably contain an addition polymerization type resin having a structure obtained by at least reacting an isocyanate compound represented by the following formula (Iso) with water, and particularly preferably contain an addition polymerization type resin having a structure obtained by at least reacting an isocyanate compound represented by the following formula (Iso) with water and having a polyethylene oxide structure and a polypropylene oxide structure as a polyoxyalkylene structure. Further, the particles containing the addition polymerization type resin having the above-described urea bond are preferably microgels.

[0496] [Chemical Formula 33]

[0497]

[0498] In formula (Iso), n represents an integer of 0 to 10.

[0499] As an example of the reaction of the isocyanate compound represented by the above-described formula (Iso) with water, the following reaction can be given. Further, the following example is for the case where n = 0 and 4, 4-isomer is used.

[0500] As shown below, if the isocyanate compound represented by the above-described formula (Iso) is reacted with water, amino groups are generated by partial hydrolysis of water isocyanate groups, the generated amino groups react with isocyanate groups, urea bonds are generated, and dimers are formed. Further, the following reaction is repeated, and an addition polymerization type resin having a urea bond is formed.

[0501] Further, in the following reaction, a compound (a compound having active hydrogen) reactive with isocyanate groups such as an alcohol compound and an amine compound is added, whereby the structure of the alcohol compound and the amine compound can also be introduced into the addition polymerization type resin having a urea bond.

[0502] As the compound having the above-described active hydrogen, a compound having the above-described active hydrogen is preferably selected.

[0503] [Chemical Formula 34]

[0504]

[0505] Further, the addition polymerization type resin having the above-described urea bond preferably has an ethylenic unsaturated group, and more preferably has a group represented by the following formula (PETA).

[0506] [Chemical Formula 35]

[0507]

[0508] In formula (PETA), the wavy line portion indicates a bonding position with other structures.

[0509] <Synthesis of Resin Particles>

[0510] The method of synthesizing the resin particles is not particularly limited, and can be any method that can synthesize the particles using the various resins described above. As the method of synthesizing the resin particles, for example, known methods of synthesizing resin particles such as emulsion polymerization, suspension polymerization, dispersion polymerization, soap-free polymerization, microemulsion polymerization, and the like can be mentioned.

[0511] In addition, known methods of synthesizing microcapsules, methods of synthesizing microgels (crosslinked resin particles), and the like can be used in the synthesis of the resin particles.

[0512] <Average Particle Diameter of Particles>

[0513] The average particle diameter of the particles is preferably from 0.01 μm to 3.0 μm, more preferably from 0.03 μm to 2.0 μm, and further preferably from 0.10 μm to 1.0 μm. Within this range, good resolution and stability over time can be obtained.

[0514] The average particle diameter of the particles is measured by a light scattering method, or an electron micrograph of the particles is taken, the particle diameters of a total of 5,000 particles on the photograph are measured, and the average value is calculated. In addition, in the case of non-spherical particles, the circular equivalent diameter of the particles on the photograph is taken as the average particle diameter.

[0515] In addition, the average particle diameter of the particles in the present application is the volume average particle diameter unless otherwise specified.

[0516] The particles (preferably resin particles) can be used singly or in combination of two or more.

[0517] From the viewpoint of development properties and print durability, the content of the particles (preferably resin particles) is preferably from 5 mass% to 90 mass%, more preferably from 10 mass% to 90 mass%, further preferably from 20 mass% to 90 mass%, and particularly preferably from 50 mass% to 90 mass%, relative to the total mass of the image recording layer.

[0518] [Other Components]

[0519] The image recording layer in the present application can contain other components in addition to the components described above.

[0520] As other components, coloring agents, ink-out agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic particles, low-molecular hydrophilic compounds, and the like disclosed in paragraphs 0181 to 0190 of Japanese Patent Application Publication No. 2009-255434 can be given.

[0521] As other components, coloring agents, ink-out agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic particles, low-molecular hydrophilic compounds, and the like disclosed in paragraphs 0181 to 0190 of Japanese Patent Application Publication No. 2009-255434 can be given.

[0522] Further, as other compounds, hydrophobizing precursors (microparticles capable of converting the image recording layer into hydrophobic upon application of heat), low-molecular hydrophilic compounds, lipid-sensing agents (for example, phosphonium compounds, nitrogen-containing low-molecular compounds, ammonium salt-containing polymers), and chain transfer agents disclosed in paragraphs 0191 to 0217 of Japanese Patent Application Publication No. 2012-187907 can be given.

[0523] - Binder polymer -

[0524] The image recording layer can contain a binder polymer as needed.

[0525] Here, the binder polymer refers to a polymer other than the resin particles, that is, a polymer that is not in the form of particles.

[0526] Further, regarding the binder polymer, ammonium salt-containing polymers in lipid-sensing agents and polymers used as surfactants are excluded.

[0527] The binder polymer can preferably use a known binder polymer (for example, (meth)acrylic resins, polyvinyl acetal resins, polyurethane resins, and the like) used in the image recording layer of a lithographic printing plate precursor.

[0528] As an example, the binder polymer used in an on-press development type lithographic printing plate precursor (hereinafter, also referred to as an on-press development binder polymer) is described in detail.

[0529] As the on-press development binder polymer, a binder polymer having an alkylene oxide chain is preferred. The binder polymer having an alkylene oxide chain can have a poly(alkylene oxide) site in the main chain or in the side chain. Further, it can be a graft polymer having a poly(alkylene oxide) in the side chain, or a block copolymer of a block composed of a repeating unit containing a poly(alkylene oxide) and a block composed of a repeating unit not containing an (alkylene oxide).

[0530] In the case of having a poly(alkylene oxide) site in the main chain, a polyurethane resin is preferred.

[0531] As the polymer that is the main chain when having a poly(alkylene oxide) moiety in the side chain, a (meth)acrylic resin, a polyvinyl acetal resin, a polyurethane resin, a polyurea resin, a polyimide resin, a polyamide resin, an epoxy resin, a polystyrene resin, a novolak phenol resin, a polyester resin, a synthetic rubber, a natural rubber, and the like can be given, and a (meth)acrylic resin is particularly preferable.

[0532] Further, as other preferable examples of the binder polymer, a high molecular compound having a 6 or more and 10 or less functional polyfunctional mercaptan as a core moiety, and having a polymer chain bonded to the core moiety through a thioether bond, and the polymer chain having a polymerizable group (hereinafter, also referred to as a star-shaped high molecular compound) can be given.

[0533] As the star-shaped high molecular compound, for example, a compound described in Japanese Patent Application Publication No. 2012-148555 can be preferably used.

[0534] As the star-shaped high molecular compound, a compound having a polymerizable group such as an olefinically unsaturated bond for improving the film strength of the image portion described in Japanese Patent Application Publication No. 2008-195018 in the main chain or the side chain, preferably the side chain can be given. Crosslinking is formed between the molecules of the star-shaped high molecular compound by the polymerizable group possessed by the star-shaped high molecular compound, and the curing is promoted.

[0535] As the polymerizable group, an olefinically unsaturated group such as a (meth)acrylic group, a vinyl group, an allyl group, a vinylphenyl group (styryl group), an epoxy group, and the like is preferable, and from the viewpoint of the polymerizability, a (meth)acrylic group, a vinyl group, a vinylphenyl group (styryl group) is more preferable, and a (meth)acrylic group is particularly preferable. These groups can be introduced to the polymer by a high molecular reaction or copolymerization. Specifically, for example, a reaction of a polymer having a carboxyl group in the side chain with glycidyl methacrylate, or a reaction of a polymer having an epoxy group with a carboxylic acid containing an olefinically unsaturated group such as methacrylic acid can be utilized.

[0536] As the molecular weight of the binder polymer, the weight average molecular weight (Mw) based on the polystyrene conversion value by the GPC method is preferably 2,000 or more, more preferably 5,000 or more, and further preferably 10,000 to 300,000.

[0537] As the binder polymer, a hydrophilic polymer such as a polyacrylic acid and a polyvinyl alcohol described in Japanese Patent Application Publication No. 2008-195018 can be used as needed in combination. Further, a lipophilic polymer and a hydrophilic polymer can also be used in combination.

[0538] The binder polymer can be used alone or in combination of two or more.

[0539] The binder polymer can be contained in the image recording layer in any amount, but the content of the binder polymer is preferably 1 to 90 mass%, more preferably 5 to 80 mass%, relative to the total mass of the image recording layer.

[0540] (Formation of image recording layer)

[0541] The image recording layer in the lithographic printing plate precursor according to the present application can be formed, for example, by preparing a coating solution by dispersing or dissolving the necessary components described above in a known solvent, as described in paragraphs 0142 to 0143 of Japanese Patent Application Publication No. 2008-195018, and coating the coating solution on a support by a known method such as bar coater coating, and drying. The coating amount (solid content) of the image recording layer after coating and drying varies depending on the use, but is preferably 0.3 g / m2to 3.0 g / m2. 2 2 In this range, good sensitivity and good film properties of the image recording layer can be obtained.

[0542] As the solvent, a known solvent can be used. Specifically, for example, water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, dichloroethane, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy-1-propanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, ethyl lactate, and the like can be given. The solvent can be used singly or in combination of two or more. The solid content concentration in the coating solution is preferably 1 to 50 mass%.

[0543] The coating amount (solid content) of the image recording layer after coating and drying varies depending on the use, but is preferably 0.3 g / m2to 3.0 g / m2from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer. 2 2

[0544] Further, the film thickness of the image recording layer in the lithographic printing plate precursor according to the present application is preferably 0.1 to 3.0 μm, more preferably 0.3 to 2.0 μm.

[0545] ​​​In the present application, the film thickness of each layer in the lithographic printing plate precursor is confirmed by preparing a section cut along a direction perpendicular to the surface of the lithographic printing plate precursor, and observing the cross section of the section cut by a scanning electron microscope (SEM).

[0546] <outermost layer>

[0547] The lithographic printing plate precursor according to the present application can have an outermost layer (sometimes also referred to as an overcoat layer) on the image recording layer.

[0548] The outermost layer described above can have a function of preventing scratches in the image recording layer and a function of preventing ablation at the time of high-intensity laser exposure in addition to a function of inhibiting an image formation hindering reaction by oxygen blocking.

[0549] The on-press development type lithographic printing plate precursor according to the present application can have, in order, a support, an image recording layer, and an outermost layer.

[0550] Further, the outermost layer described above is an outermost layer on the image recording layer side of the support in the on-press development type lithographic printing plate precursor.

[0551] The outermost layer described above preferably contains a water-soluble polymer, and more preferably contains a water-soluble polymer and a hydrophobic polymer.

[0552] Further, the outermost layer described above preferably contains a color changeable compound.

[0553] Furthermore, the outermost layer described above can contain other components such as a lipophilic sensitizer, an infrared absorber, and the like.

[0554] -Color changeable compound-

[0555] The outermost layer described above preferably contains a color changeable compound.

[0556] In the present application, the "color changeable compound" refers to a compound in which the absorption in the visible light region (wavelength: 400 nm or more and less than 750 nm) changes due to infrared exposure. That is, in the present application, "color change" refers to a change in the absorption in the visible light region (wavelength: 400 nm or more and less than 750 nm) due to infrared exposure.

[0557] Specifically, as the color changeable compound in the present application, (1) a compound in which the absorption in the visible light region increases due to infrared exposure compared to before infrared exposure, (2) a compound which has an absorption in the visible light region due to infrared exposure, and (3) a compound which does not have an absorption in the visible light region due to infrared exposure can be mentioned.

[0558] In addition, the infrared in the present application is light having a wavelength of 750 nm to 1 mm, and preferably light having a wavelength of 750 nm to 1,400 nm.

[0559] As the color changeable compound, a compound which develops color due to infrared exposure is preferable.

[0560] Further, as the color changeable compound, a decomposable compound which decomposes due to infrared exposure is preferable, and a decomposable compound which decomposes by heat, electron transfer or both caused by infrared exposure is preferable.

[0561] More specifically, the color changeable compound in the present application is preferably a compound which decomposes due to infrared exposure (more preferably decomposes by heat, electron transfer or both caused by infrared exposure), and which increases absorption in the visible region or has absorption in the visible region with shorter wavelength compared to before the infrared exposure.

[0562] Here, "decomposes by electron transfer" means that an electron excited from the HOMO (highest occupied molecular orbital) to the LUMO (lowest unoccupied molecular orbital) of the color changeable compound by infrared exposure is transferred to an electron-accepting group (a group having a potential close to the LUMO) within the molecule, and decomposition occurs as a result.

[0563] Hereinafter, a decomposable compound which is an example of the color changeable compound will be described.

[0564] As the decomposable compound, a compound which absorbs at least a part of light in the infrared wavelength region (wavelength region of 750 nm to 1 mm, preferably wavelength region of 750 nm to 1,400 nm) and decomposes is acceptable, but a compound having a large absorption wavelength in the wavelength region of 750 nm to 1,400 nm is preferable.

[0565] More specifically, the decomposable compound is preferably a compound which decomposes due to infrared exposure and generates a compound having a large absorption wavelength in the wavelength region of 500 nm to 600 nm.

[0566] From the viewpoint of improving the visual recognition of the exposed portion, the decomposable compound is preferably a cyanine dye having a group which decomposes by infrared exposure (specifically, R 1 in the following Formulae 1-1 to 1-7).

[0567] As the decomposable compound, from the viewpoint of improving the visual recognition of the exposed portion, a compound represented by the following Formula 1-1 is more preferable.

[0568] [Chemical Formula 36]

[0569]

[0570] In Formula 1-1, R 1 represents a group represented by any one of the following Formulae 2-1 to 4-1, and R11 ~R 18 respectively independently represent a hydrogen atom, a halogen atom, -R a , -OR b , -SR c or -NR d R e , R a ~R e respectively independently represent a hydrocarbon group, A1, A2 and a plurality of R 11 ~R 18 may be linked to form a monocyclic or polycyclic ring, A1 and A2 respectively independently represent an oxygen atom, a sulfur atom or a nitrogen atom, n 11 and n 12 respectively independently represent an integer of 0 to 5, wherein the total of n 11 and n 12 is 2 or more, n 13 and n 14 respectively independently represent 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 a charge.

[0571] [Chemical Formula 37]

[0572]

[0573] In Formulae 2-1 to 4-1, R 20 , R 30 , R 41 and R 42 respectively independently represent an alkyl group or an aryl group, Zb represents a counter ion for neutralizing a charge, and a wavy line represents a bonding site with a group represented by L in Formula 1-1.

[0574] If a compound represented by Formula 1-1 is exposed to infrared rays, R 1 -L bond is broken, and L becomes =O, =S or =NR 10 , thereby changing color.

[0575] In Formula 1-1, R 1 represents a group represented by any one of Formulae 2-1 to 4-1.

[0576] Hereinafter, a group represented by Formula 2-1, a group represented by Formula 3-1 and a group represented by Formula 4-1 will be described.

[0577] In Formula 2-1, R 20 represents an alkyl group or an aryl group, and a wavy line portion represents a bonding site with a group represented by L in Formula 1-1.

[0578] As the group represented byR20 The alkyl group indicated is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms.

[0579] The alkyl groups mentioned above can be straight-chain, branched, or have a cyclic structure.

[0580] As a result of R 20 The aryl group represented is preferably an aryl group with 6 to 30 carbon atoms, more preferably an aryl group with 6 to 20 carbon atoms, and even more preferably an aryl group with 6 to 12 carbon atoms.

[0581] As R 20 From the point of view of visual recognizability, alkyl groups are preferred.

[0582] Furthermore, from the perspective of visual recognizability and color rendering, as a result of R 20 The alkyl group indicated is preferably a secondary alkyl group or a tertiary alkyl group, with a preference for a tertiary alkyl group.

[0583] Moreover, from the perspective of decomposition and visual recognition, as a product of R 20 The alkyl group represented is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, even more preferably a branched alkyl group having 3 to 6 carbon atoms, particularly preferably isopropyl or tert-butyl, and most preferably tert-butyl.

[0584] Hereinafter, specific examples of groups represented by Formula 2-1 above will be given, but the present invention is not limited to these. In the following structural formulas, ● indicates the bonding site with the group represented by L in Formula 1-1.

[0585] [Chemical Formula 38]

[0586]

[0587] In Equation 3-1, R 30 The wavy line indicates an alkyl or aryl group, and the wavy line indicates the bonding site with the group represented by L in Formula 1-1.

[0588] As a result of R 30 The alkyl and aryl groups represented are related to R in formula 2-1. 20 The alkyl and aryl groups are represented by the same terms, and the preferred methods are also the same.

[0589] From the perspective of visual recognition and color rendering, as a result of R 30 The alkyl group indicated is preferably a secondary alkyl group or a tertiary alkyl group, with a preference for a tertiary alkyl group.

[0590] Furthermore, from the perspective of decomposition and visual recognition, as a result of R 30The alkyl group represented by R is preferably a substituted alkyl group, more preferably a fluorine-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group.

[0591] The alkyl group represented by R is preferably a substituted alkyl group, more preferably a fluorine-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group. 30 The alkyl group represented by R is preferably a substituted alkyl group, more preferably a fluorine-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group.

[0592] The alkyl group represented by R is preferably a substituted alkyl group, more preferably a fluorine-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group. 30 The aryl group represented by R 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), an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms), and the like.

[0593] Hereinafter, specific examples of the group represented by the above Formula 3-1 will be shown, but the present application is not limited to these. In the following structural formula, • indicates a bonding site with the group represented by L in Formula 1-1.

[0594] [Chemical Formula 39]

[0595]

[0596] In Formula 4-1, R 41 and R 42 independently represent an alkyl group or an aryl group, Zb represents a counter ion for neutralizing a charge, and the wavy line portion indicates a bonding site with the group represented by L in Formula 1-1.

[0597] The alkyl group and the aryl group represented by R 41 or R 42 are the same as the alkyl group and the aryl group represented by R 20 in Formula 2, and the preferred modes are also the same.

[0598] R 41 is preferably an alkyl group from the viewpoints of decomposability and visual recognition.

[0599] R 42 is preferably an alkyl group from the viewpoints of decomposability and visual recognition.

[0600] The alkyl group represented by R 41 is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group from the viewpoints of decomposability and visual recognition.

[0601] The alkyl group represented by R 42 is preferably a secondary alkyl group or a tertiary alkyl group, and preferably a tertiary alkyl group from the viewpoints of visual recognition and color development.

[0602] Also, from the viewpoints of decomposition and visual recognition, as the alkyl group represented by R 42 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, and particularly preferably isopropyl or tert-butyl, and most preferably tert-butyl.

[0603] As for Zb in Formula 4-1, it is only required to be a counter ion for neutralizing a charge, and can also be included in Za in Formula 1-1 as a whole of the compound.

[0604] Zb is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a tetrafluoroborate ion.

[0605] Hereinafter, specific examples of the group represented by Formula 4-1 described above will be given, but the present application is not limited to these. In the structural formulae described below, • indicates a bonding site with the group represented by L in Formula 1-1.

[0606] [Chemical Formula 40]

[0607]

[0608] In Formula 1-1, L is preferably an oxygen atom or -NR 10 , and particularly preferably an oxygen atom.

[0609] Also, R 10 in -NR 10 is preferably an alkyl group. As the alkyl group represented by R 10 , an alkyl group having 1 to 10 carbon atoms is preferred. Also, the alkyl group represented by R 10 may be linear, branched, or cyclic.

[0610] In the alkyl group, a methyl group or a cyclohexyl group is preferred.

[0611] In the case where R 10 in -NR 10 is an aryl group, an aryl group having 6 to 30 carbon atoms is preferred, an aryl group having 6 to 20 carbon atoms is more preferred, and an aryl group having 6 to 12 carbon atoms is further preferred. Also, these aryl groups can have a substituent.

[0612] In Formula 1-1, R 11 to R 18 each independently represent a hydrogen atom, -R a , -OR b , -SR c , or -NR d R e.

[0613] R a R e The hydrocarbon group represented by R is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and further preferably a hydrocarbon group having 1 to 10 carbon atoms.

[0614] The above hydrocarbon group can be linear, can have a branched chain, and can have a ring structure.

[0615] As the above hydrocarbon group, an alkyl group is particularly preferable.

[0616] The above 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 further preferably an alkyl group having 1 to 10 carbon atoms.

[0617] The above alkyl group can be linear, can have a branched chain, and can have a ring structure.

[0618] Specific examples of the above alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group.

[0619] Among the above alkyl groups, a methyl group, an ethyl group, a propyl group, or a butyl group is preferable.

[0620] The above alkyl group can have a substituent.

[0621] 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 a group formed by combining them.

[0622] R 11 R 14 are each independently preferably a hydrogen atom or a group represented by -R a (i.e., a hydrocarbon group), more preferably a hydrogen atom or an alkyl group, and further preferably a hydrogen atom except for the following cases.

[0623] wherein R 11 and R 13 are preferably an alkyl group, and more preferably the two are linked to form a ring. As the above formed ring, a monocyclic ring or a polycyclic ring can be mentioned. As the formed ring, specific examples include a monocyclic ring such as a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring, a cyclohexadiene ring, and a polycyclic ring such as an indene ring and an indole ring.

[0624] Furthermore, in A1 + R bonded to the bonded carbon atom 12 Preferred and R 15 or R 16 (preferably R) 16 The links form a ring, with R bonded to the carbon atom bonded to A2. 14 Preferred and R 17 or R 18 (preferably R) 18 They are connected to form a ring.

[0625] In Equation 1-1, n is preferred. 13 R is 1 16 -R a (i.e., hydrocarbon group).

[0626] Furthermore, R 16 Preferred and in A1 + R bonded to the bonded carbon atom 12 The rings are linked together to form a ring. Preferably, the ring is an indole ring, a pyranonium ring, a thiopyridinium ring, a benzoxazoline ring, or a benzimidazolinium ring; from the viewpoint of improving the visual recognizability of the exposed portion, an indole ring is more preferred. These rings may also have substituents.

[0627] In Equation 1-1, n is preferred. 14 R is 1 18 -R a (i.e., hydrocarbon group).

[0628] Furthermore, R 18 Preferably, R is bonded to the carbon atom bonded to A2. 14 The rings are linked together to form a ring. Preferably, the ring is an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring, or a benzimidazole ring; from the viewpoint of improving the visual recognizability of the exposed portion, an indole ring is more preferred. These rings may also have substituents.

[0629] R in Equation 1-1 16 and R 18 Preferably, the same groups are formed, and if each forms a ring, it is preferable to form a ring other than A1. + All rings except A2 have the same structure.

[0630] R in Equation 1-1 15 and R 17 Preferably, they are the same group. And, R 15 and R 17 Preferred is -R a (i.e., hydrocarbon group), more preferably alkyl, and even more preferably substituted alkyl.

[0631] In the compounds represented by formula 1-1, from the viewpoint of improving water solubility, R15 and R 17 is preferably a substituted alkyl group.

[0632] as R 15 or R 17 , a group represented by any one of the following formulae (al) to (a4) can be mentioned.

[0633] [Chemical Formula 41]

[0634]

[0635] In formulae (al) 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 of 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 to R W4 each independently represent 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.

[0636] In formula (al), as the alkylene group represented by R W0 , ethylene, n-propylene, i-propylene, n-butylene, i-butylene, n-pentylene, i-pentylene, n-hexylene, i-hexylene and the like can be mentioned, with ethylene, n-propylene, i-propylene or n-butylene being preferred, and n-propylene being particularly preferred.

[0637] n w1 is preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3.

[0638] As the alkyl group represented by R W1 , methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, neopentyl, n-hexyl, n-octyl, n-dodecyl and the like can be mentioned, with methyl, ethyl, n-propyl, i-propyl or n-butyl, t-butyl being preferred, methyl or ethyl being further preferred, and methyl being particularly preferred.

[0639] The alkyl group represented by R W5 is the same as the alkyl group represented by R W1 , and the preferred modes are also the same as those of the alkyl group represented by R W1 .

[0640] Specific examples of the group represented by formula (al) are shown below, but the present application is not limited to these. In the following structural formulae, Me represents a methyl group, Et represents an ethyl group, and * represents a bonding site.

[0641] [Chemical Formula 42]

[0642]

[0643] In formula (a2) to formula (a4), as the alkylene group represented by R W2 ~R W4 , ethylene group, n-propylene group, i-propylene group, n-butylene group, i-butylene group, n-pentylene group, i-pentylene group, n-hexylene group, i-hexylene group, n-octylene group, n-dodecylene group, and the like, preferably ethylene group, n-propylene group, i-propylene group, or n-butylene group, and particularly preferably ethylene group or n-propylene group.

[0644] In formula (a3), the two Ms can be the same or different.

[0645] In formula (a2) to formula (a4), as the onium group represented by M, there can be mentioned an ammonium group, an iodonium group, a phosphonium group, a sulfonium group, and the like.

[0646] CO2M in formula (a2), PO3M2 in formula (a2), and SO3M in formula (a4) can each have an anion structure dissociated from M. The counter cation of the anion structure can be A1 + , or R 1 -L can include.

[0647] In the group represented by formula (a1) to formula (a4), the group represented by formula (a1), formula (a2), or formula (a4) is preferred.

[0648] n 11 and n 12 are preferably the same, and each is preferably an integer of 1 to 5, more preferably an integer of 1 to 3, further preferably 1 or 2, and particularly preferably 2.

[0649] A1 and A2 in formula 1-1 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, and preferably a nitrogen atom.

[0650] A1 and A2 in formula 1-1 are preferably the same atom.

[0651] Za in formula 1-1 represents a counter ion that neutralizes the electric charge.

[0652] If R 11 ~R 18 , and R 1 -L are all electrically neutral groups, Za becomes a monovalent counter anion. However, R 11 ~R 18 , and R 1 -L can have an anion structure or a cation structure, for example, in the case of R11 ~R 18 and R 1 -L has two or more anionic structures, Za can also be a counter cation.

[0653] In addition, if the cyanine dye represented by Formula 1-1 is an electrically neutral structure in the entirety of the compound other than Za, Za is not required.

[0654] In the case where Za is a counter anion, sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, p-toluenesulfonate ions, perchlorate ions, and the like can be given, with tetrafluoroborate ions being preferred.

[0655] In the case where Za is a counter cation, alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, sulfonium ions, and the like can be given, with sodium ions, potassium ions, ammonium ions, pyridinium ions, or sulfonium ions being preferred, and sodium ions, potassium ions, or ammonium ions being more preferred.

[0656] As the decomposing compound, from the viewpoint of improving the visual recognition of the exposed portion, a compound represented by the following Formula 1-2 (i.e., a cyanine dye) is more preferred.

[0657] [Chemical Formula 43]

[0658]

[0659] In Formula 1-2, R 1 represents a group represented by any of the above Formulae 2-1 to 4-1, R 19 ~R 22 each independently represent a hydrogen atom, a halogen atom, -R a , -OR b , -CN, -SR c , or -NR d R e , R 23 , and R 24 each independently represent a hydrogen atom or -R a , R a ~R e each independently represent a hydrocarbon group, R 19 and R 20 , R 21 and R 22 , or R 23 and R 24 may be linked to form a 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 , W 1 , and W2 Each of these can independently represent an alkyl group that may have substituents, and Za represents a counterion that neutralizes the charge.

[0660] R in Equation 1-2 1 R in Equation 1-1 1 The meanings are the same, and the preferred selection methods are also the same.

[0661] In equation 1-2, R 19 ~R 22 Each is independently preferred to be a hydrogen atom, a halogen atom, or -R. a -OR b Or -CN.

[0662] More specifically, R 19 and R 21 Preferably hydrogen atoms or -R a .

[0663] Furthermore, R 20 and R 22 Preferably hydrogen atoms, -R a -OR b Or -CN.

[0664] As a result of R 19 ~R 22 -R indicates a Preferably alkyl or alkenyl groups.

[0665] In R 19 ~R 22 All are -R a In the case of R, it is preferred 19 With R 20 and R 21 With R 22 They can be linked together to form single or multiple rings.

[0666] As R 19 With R 20 or R 21 With R 22 Examples of rings formed by linkages include benzene rings and naphthalene rings.

[0667] In Equation 1-2, R is preferred. 23 With R 24 They can be linked together to form single or multiple rings.

[0668] As R 23 With R 24 The ring formed by the linkage can be a monocyclic or polycyclic ring. Specifically, examples of the formed rings include monocyclic rings such as cyclopentene ring, cyclopentadiene ring, cyclohexene ring, and cyclohexadiene ring, as well as polycyclic rings such as indene ring.

[0669] In equation 1-2, Rd1 ~R d4 is preferably unsubstituted alkyl. Also, R d1 ~R d4 are all the same group.

[0670] As the unsubstituted alkyl group, there can be mentioned unsubstituted alkyl groups having 1 to 4 carbon atoms, of which methyl group is preferred.

[0671] In formula 1-2, from the viewpoint of improving the water solubility of the compound represented by formula 1-2, W 1 and W 2 are each independently preferably substituted alkyl groups.

[0672] As the substituted alkyl group represented by W 1 and W 2 , there can be mentioned the group represented by any of formulae (al) to (a4) in formula 1-1, and the preferred modes are the same.

[0673] Also, from the viewpoint of on-press developability, W 1 and W 2 are each independently preferably an alkyl group having a substituent, and are a group having at least -(OCH2CH2)-, sulfo group, salt of sulfo group, carboxyl group or salt of carboxyl group as the substituent.

[0674] Za represents a counter ion that neutralizes the charge within the molecule.

[0675] If R 19 ~R 22 , R 23 ~R 24 , R d1 ~R d4 , W 1 , W 2 and R 1 -L are all electrically neutral groups, Za becomes a monovalent counter anion. However, R 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-L has 2 or more anionic structures, Za can also be a counter cation.

[0676] In addition, if the compound represented by Formula 1-2 is electrically neutral in the entire compound except for Za, Za is not required.

[0677] Examples of Za when it is a counter anion are the same as those of Za in Formula 1-1, and the preferred modes are also the same. Also, examples of Za when it is a counter cation are the same as those of Za in Formula 1-1, and the preferred modes are also the same.

[0678] From the viewpoints of decomposability and visual recognition, the cyanine dye that is a decomposable compound is further preferably a compound represented by any one of the following Formulas 1-3 to 1-7.

[0679] In particular, from the viewpoints of decomposability and visual recognition, a compound represented by any one of Formula 1-3, Formula 1-5, and Formula 1-6 is preferred.

[0680] [Chemical Formula 44]

[0681]

[0682] In Formulas 1-3 to 1-7, R 1 represents a group represented by any one of the above Formulas 2-1 to 4-1, R 19 to R 22 each independently represent a hydrogen atom, a halogen atom, -R a , -OR b , -CN, -SR c , or -NR d R e , R 25 , and R 26 each independently represent a hydrogen atom, a halogen atom, or -R a , R a to R e each independently represent a hydrocarbon group, R 19 and R 20 , R 21 and R 22 , or R 25 and R 26 may be linked to form a monocyclic or polycyclic ring, 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 to R d4 , W 1 , and W 2 each independently represent an alkyl group that can have a substituent, and Za represents a counter ion that neutralizes the electric charge.

[0683] R in formulae 1-3 to 1-7 1 R 19 R 22 R d1 R d4 W 1 W 2 and L have the same meanings as R 1 R 19 R 22 R d1 R d4 W 1 W 2 and L in formula 1-2, and the preferable modes are also the same.

[0684] R in formula 1-7 25 and R 26 are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group.

[0685] Hereinafter, specific examples of cyanine pigments of the decomposable compound will be shown, but the present application is not limited to these.

[0686] [Chemical Formula 45]

[0687]

[0688] Further, as the cyanine pigment of the decomposable compound, the infrared-absorbing compound described in International Publication No. 2019 / 219560 can be preferably used.

[0689] Further, the above discoloring compound preferably contains an acid developer.

[0690] As the acid developer, the acid developer described in the image recording layer as the acid developer can be used, and the preferable modes are also the same.

[0691] The discoloring compound can be used alone or two or more components can be used in combination.

[0692] As the discoloring compound, the above-described decomposable compound and the above acid generator can be used in combination.

[0693] From the viewpoint of visual recognition, the content of the discoloring compound in the outermost layer is preferably 0.10 to 50 mass%, more preferably 0.50 to 30 mass%, and further preferably 1.0 to 20 mass% relative to the total mass of the outermost layer.

[0694] From the viewpoint of visual recognition, the content M X of the discoloring compound in the above outermost layer is preferably 0.10 to 50 mass%, more preferably 0.50 to 30 mass%, and further preferably 1.0 to 20 mass% relative to the total mass of the outermost layer. YThe ratio M of the thickness of the outermost layer to the thickness of the intermediate layer X / M Y The ratio M is preferably 0.1 or more, more preferably 0.2 or more, and particularly preferably 0.3 or more and 3.0 or less.

[0695] - Water-soluble polymer -

[0696] From the viewpoint of development removability (more preferably on-press development), the above-mentioned outermost layer preferably contains a water-soluble polymer.

[0697] In the present application, a water-soluble polymer refers to a polymer that dissolves 1 g or more in 100 g of pure water at 70°C, and a polymer that does not precipitate even when a solution obtained by dissolving 1 g of the polymer in 100 g of pure water at 70°C is cooled to 25°C.

[0698] As the water-soluble polymer used in the outermost layer, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose derivatives, polyethylene glycol, poly(meth)acrylonitrile, and the like can be given.

[0699] As the modified polyvinyl alcohol, an acid-modified polyvinyl alcohol having a carboxyl group or a sulfo group can be preferably used. Specifically, the modified polyvinyl alcohol described in Japanese Patent Application Publication No. 2005-250216 and Japanese Patent Application Publication No. 2006-259137 can be given.

[0700] As the above-mentioned water-soluble polymer, polyvinyl alcohol can be given as a preferable example. Among them, a polyvinyl alcohol having a saponification degree of 50% or more is further preferable as the water-soluble polymer.

[0701] The above-mentioned saponification degree is preferably 60% or more, more preferably 70% or more, and further preferably 85% or more. The upper limit of the saponification degree is not particularly limited, and can be 100% or less.

[0702] The above-mentioned saponification degree can be measured according to the method described in JIS K 6726: 1994.

[0703] As the above-mentioned water-soluble polymer, polyvinylpyrrolidone can be given as a preferable example.

[0704] As the water-soluble polymer, a combination of polyvinyl alcohol and polyvinylpyrrolidone is also preferable.

[0705] The water-soluble polymer can be used alone or in combination of two or more.

[0706] In the case where the outermost layer contains a water-soluble polymer, the content of the water-soluble polymer is preferably 1 to 99 mass%, more preferably 3 to 97 mass%, and further preferably 5 to 95 mass% with respect to the total mass of the outermost layer.

[0707] - lipid sensitizer -

[0708] The above-mentioned outermost layer preferably contains a lipid sensitizer.

[0709] As the lipid sensitizer, a phosphonium compound, a nitrogen-containing low-molecular compound, an ammonium group-containing polymer, or the like can be given.

[0710] As the lipid sensitizer, a phosphonium compound, a nitrogen-containing low-molecular compound, and an ammonium group-containing polymer are preferably used in combination, and a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer are more preferably used in combination.

[0711] As the phosphonium compound, a phosphonium compound described in Japanese Patent Application Publication No. 2006-297907 and Japanese Patent Application Publication No. 2007-50660 can be given. As specific examples, tetrabutylphosphonium iodide, butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 1,4-bis(triphenylphosphine)butane di(hexafluorophosphate), 1,7-bis(triphenylphosphine)heptane sulfate, 1,9-bis(triphenylphosphine)nonane naphthalene-2,7-disulfonate, and the like can be given.

[0712] As the nitrogen-containing low-molecular compound, an amine salt, a quaternary ammonium salt, and the like can be given. Furthermore, an imidazolinium salt, a benzimidazolinium salt, a pyridinium salt, a quinolinium salt, and the like can be given. Among these, a quaternary ammonium salt and a pyridinium salt are preferred. As specific examples, tetramethylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate, dodecyltrimethylammonium p-toluenesulfonate, benzyltriethylammonium hexafluorophosphate, benzyl dimethyl octyl ammonium hexafluorophosphate, benzyl dimethyl dodecyl ammonium hexafluorophosphate, a compound described in paragraphs 0021 to 0037 of Japanese Patent Application Publication No. 2008-284858, paragraphs 0030 to 0057 of Japanese Patent Application Publication No. 2009-90645, and the like can be given.

[0713] As the ammonium group-containing polymer, a polymer having an ammonium group in the side chain at a content of 5 to 80 mol% of a (meth)acrylate having an ammonium group as a copolymerization component is preferred. As specific examples, a polymer described in paragraphs 0089 to 0105 of Japanese Patent Application Publication No. 2009-208458 can be given.

[0714] As for the ammonium salt-containing polymer, the value of the specific viscosity (unit: ml / g) obtained by the measurement method described in Japanese Patent Application Publication No. 2009-208458 is preferably in the range of 5 to 120, more preferably in the range of 10 to 110, and particularly preferably in the range of 15 to 100. When the above-mentioned specific viscosity is converted into the weight average molecular weight (Mw), it is preferably 10,000 to 150,000, more preferably 17,000 to 140,000, and particularly preferably 20,000 to 130,000.

[0715] The following shows specific examples of the ammonium group-containing polymer.

[0716] (1) 2-(trimethylammonio)ethyl methacrylate = p-toluenesulfonate / 3,6-dioxymethylpropyl methacrylate copolymer (molar ratio 10 / 90, Mw 4.5 million)

[0717] (2) 2-(trimethylammonio)ethyl methacrylate = hexafluorophosphate / 3,6-dioxymethylpropyl methacrylate copolymer (molar ratio 20 / 80, Mw 6.0 million)

[0718] (3) 2-(ethyldimethylammonio)ethyl methacrylate = p-toluenesulfonate / hexyl methacrylate copolymer (molar ratio 30 / 70, Mw 4.5 million)

[0719] (4) 2-(trimethylammonio)ethyl methacrylate = hexafluorophosphate / 2-ethylhexyl methacrylate copolymer (molar ratio 20 / 80, Mw 6.0 million)

[0720] (5) 2-(trimethylammonio)ethyl methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40 / 60, Mw 7.0 million)

[0721] (6) 2-(butyldimethylammonio)ethyl methacrylate = hexafluorophosphate / 3,6-dioxymethylpropyl methacrylate copolymer (molar ratio 25 / 75, Mw 6.5 million)

[0722] (7) 2-(butyldimethylammonio)ethyl methacrylate = hexafluorophosphate / 3,6-dioxymethylpropyl methacrylate copolymer (molar ratio 20 / 80, Mw 6.5 million)

[0723] (8) 2-(butyldimethylammonio)ethyl methacrylate = 13-ethyl-5,8,11-trioxa-1-heptadecanesulfonate / 3,6-dioxymethylpropyl methacrylate copolymer (molar ratio 20 / 80, Mw 7.5 million)

[0724] (9) 2-(butyldimethylammonio)ethyl methacrylate = hexafluorophosphate / 3,6-dioxymethylpropyl methacrylate / 2-hydroxy-3-methacryloyloxypropyl methacrylate copolymer (molar ratio 15 / 80 / 5, Mw 6.5 million)

[0725] The lipophilizing agent can be used singly or in combination of two or more.

[0726] The content of the lipophilizing agent is preferably 0.01 to 30.0 mass%, more preferably 0.1 to 15.0 mass%, and further preferably 1 to 10 mass%, relative to the total mass of the outermost layer.

[0727] - Other Components -

[0728] The outermost layer described above can contain, in addition to the discoloration compound and the water-soluble polymer described above, a hydrophobic polymer, an acid generator, an infrared absorber, and the like as other components.

[0729] The other components will be described below.

[0730] <<Hydrophobic Polymer>>

[0731] The outermost layer described above preferably contains a hydrophobic polymer.

[0732] The hydrophobic polymer refers to a polymer that dissolves less than 1 g or does not dissolve in 100 g of pure water at 70°C.

[0733] As the hydrophobic polymer, for example, polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, poly(alkyl) (meth)acrylate (e.g., polymethyl (meth)acrylate, polyethyl (meth)acrylate, polybutyl (meth)acrylate, and the like), a copolymer obtained by combining raw material monomers of these polymers, and the like can be given.

[0734] Further, as the hydrophobic polymer, a polyvinylidene chloride resin is preferably contained.

[0735] Furthermore, as the hydrophobic polymer, a styrene-acrylic acid copolymer is preferably contained.

[0736] Furthermore, from the viewpoint of on-press developability, the hydrophobic polymer is preferably a hydrophobic polymer particle.

[0737] The hydrophobic polymer can be used alone or in combination with two or more.

[0738] In the case where the outermost layer contains a hydrophobic polymer, the content of the hydrophobic polymer is preferably 1 to 80% by mass, and more preferably 5 to 50% by mass, with respect to the total mass of the outermost layer.

[0739] <<Acid Generator>>

[0740] The outermost layer described above preferably contains an acid generator as the discoloration compound.

[0741] The "acid generator" in the present application is a compound that generates an acid using light or heat, and specifically refers to a compound that generates an acid by decomposition upon infrared exposure.

[0742] As the acid generated, a strong acid having a pKa of 2 or less, such as sulfonic acid or hydrochloric acid, is preferred. The acid described above can be caused to discolor by the acid generated from the acid generator.

[0743] Specifically, as the acid generator, an onium salt compound is preferred from the viewpoint of sensitivity and stability.

[0744] As specific examples of the onium salt preferably used as the acid generator, the compounds described in paragraphs 0121 to 0124 of International Publication No. 2016 / 047392 can be given.

[0745] Among them, the sulfonic acid salt, carboxylic acid salt, BPh4 - , BF4 - , PF6 - , CIO4 - , etc. of triarylsulfonium or diaryliodonium are preferred. Here, Ph represents a phenyl group.

[0746] The acid generator can be used singly or in combination of two or more.

[0747] In the case where the acid generator is contained in the outermost layer, the content of the acid generator is preferably 0.5% by mass to 30% by mass, more preferably 1% by mass to 20% by mass, with respect to the total mass of the outermost layer.

[0748] The above-mentioned outermost layer can contain, in addition to the components described above, a known additive such as a lubricant, an inorganic layered compound, a surfactant, etc.

[0749] The outermost layer is formed by applying and drying using a known method.

[0750] The application amount (solid content) of the outermost layer is preferably 0.01 g / m 2 to 10 g / m 2 , more preferably 0.02 g / m 2 to 3 g / m 2 , and particularly preferably 0.1 g / m 2 to 2.0 g / m 2 .

[0751] The film thickness of the outermost layer is preferably 0.1 μm to 5.0 μm, more preferably 0.3 μm to 4.0 μm.

[0752] The film thickness of the above-mentioned outermost layer is preferably 0.1 times to 5.0 times, more preferably 0.2 times to 3.0 times, with respect to the film thickness of the image recording layer described later.

[0753] The outermost layer can contain a known additive such as a plasticizer for imparting flexibility, a surfactant for improving coatability, an inorganic particle for controlling surface slip property, etc.

[0754] <Support>

[0755] The lithographic printing plate precursor according to the present application preferably has a support.

[0756] As the support, a known support for a lithographic printing plate precursor can be appropriately selected and used.

[0757] As the support, a support having a hydrophilic surface (hereinafter, also referred to as "hydrophilic support") is preferable.

[0758] As the support in the present application, an aluminum plate which has been subjected to roughening treatment by a publicly known method and anodization treatment is preferable. That is, the support in the present application preferably has an aluminum plate and an anodized film of aluminum provided on the aluminum plate.

[0759] Further, the support preferably has an aluminum plate and an anodized film of aluminum provided on the aluminum plate, the anodized film is located on the image recording layer side more than the aluminum plate, and the anodized film has micro-holes extending in the depth direction from the surface on the image recording layer side, the average diameter of the micro-holes at the surface of the anodized film is more than 10 nm and 100 nm or less.

[0760] Further, the micro-holes are preferably composed of a large-diameter hole portion extending from the surface of the anodized film to a position at a depth of 10 nm to 1,000 nm and a small-diameter hole portion communicating with the bottom of the large-diameter hole portion and extending from the communication position to a position at a depth of 20 nm to 2,000 nm, the average diameter of the large-diameter hole portion at the surface of the anodized film is 15 nm to 100 nm, and the average diameter of the small-diameter hole portion at the communication position is 13 nm or less.

[0761] Figure 1 is a schematic cross-sectional view of one embodiment of the aluminum support 12a.

[0762] The aluminum support 12a has a laminated structure in which an aluminum plate 18 and an anodized film 20a of aluminum (hereinafter, also simply referred to as "anodized film 20a") are laminated in this order. Further, the anodized film 20a in the aluminum support 12a is located on the image recording layer side more than the aluminum plate 18. That is, the lithographic printing plate precursor according to the present application preferably has at least an anodized film, an image recording layer, and a water-soluble resin layer in this order on an aluminum plate.

[0763] Anodized Film

[0764] Hereinafter, a preferable mode of the anodized film 20a will be described.

[0765] The anodized film 20a is a film produced on the surface of the aluminum plate 18 by anodization treatment, and has ultra-fine micro-holes 22a which are substantially perpendicular to the film surface and are uniformly distributed respectively. The micro-holes 22a extend in the thickness direction (aluminum plate 18 side) from the surface of the anodized film 20a on the image recording layer side (the surface of the anodized film 20a on the side opposite to the aluminum plate 18 side).

[0766] 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 viewpoint of balancing print durability, stain resistance, and image visual recognizability, 15 nm to 60 nm is more preferred, 20 nm to 50 nm is even more preferred, and 25 nm to 40 nm is particularly preferred. The diameter inside the pore can be wider or narrower than the surface layer.

[0767] Excellent printing durability and image visual recognition are achieved when the average diameter exceeds 10 nm. Furthermore, excellent printing durability is also achieved when the average diameter is below 100 nm.

[0768] The average diameter of the micropores 22a is as follows: Using a field emission scanning electron microscope (FE-SEM) at 150,000x magnification, the surface of the anodic oxide film 20a was observed in N=4 images. In the four images obtained, 50 micropores were measured at 400×600 nm. 2 The value is obtained by averaging the diameter of the micropores within a certain range.

[0769] In addition, when the shape of the micropore 22a is not circular, the equivalent diameter of the circle is used. The "equivalent diameter of the circle" refers to the diameter of a circle when the shape of the opening is assumed to be a circle with a projected area equal to the projected area of ​​the opening.

[0770] The shape of the micropore 22a is not particularly limited, in Figure 1 The core is generally straight tubular (generally cylindrical), but it can also be conical with a diameter that decreases towards the depth direction (thickness direction). Furthermore, the shape of the bottom of the micropore 22a is not particularly limited; it can be curved (convex) or planar.

[0771] In the support (1), the micropores can be composed of a large-diameter pore portion and a small-diameter pore portion. The large-diameter pore portion extends from the surface of the anodic oxide film to a certain depth, 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 certain depth.

[0772] For example, such as Figure 2 As shown, the aluminum support 12b can be in the form of an aluminum plate 18 and an anodized film 20b having micropores 22b composed of large-diameter holes 24 and small-diameter holes 26.

[0773] For example, the micropores 22b in the anodic oxide film 20b are composed of large-diameter pores 24 and small-diameter pores 26, wherein the large-diameter pores 24 extend from the surface of the anodic oxide film to a depth of 10 nm to 1000 nm (depth D: reference). Figure 2The small-diameter hole portion 26 communicates with the bottom of the large-diameter hole portion 24 at a position that is further extended to a depth of 20 nm to 2,000 nm from the communication position. Specifically, for example, the method described in paragraphs 0107 to 0114 of Japanese Patent Application Publication No. 2019-162855 can be used.

[0774] Method for manufacturing support

[0775] As the method for manufacturing the support used in the present application, for example, a manufacturing method in which the following processes are sequentially performed is preferable.

[0776] • Roughening treatment process: a process of performing roughening treatment on an aluminum plate

[0777] • Anodizing treatment process: a process of anodizing the aluminum plate subjected to the roughening treatment

[0778] • Hole expansion treatment process: a process of bringing the aluminum plate having an anodized film obtained in the anodizing treatment process into contact with an acid aqueous solution or an alkaline aqueous solution, and expanding the diameter of the micropores in the anodized film

[0779] Hereinafter, the steps of each process will be described in detail.

[0780] << Roughening treatment process >>

[0781] The roughening treatment process is a process of performing roughening treatment including electrochemical roughening treatment on the surface of an aluminum plate. This process is preferably performed before the anodizing treatment process described later, but if the surface of the aluminum plate already has a preferable surface shape, this process does not need to be particularly performed. It can be performed by the method described in paragraphs 0086 to 0101 of Japanese Patent Application Publication No. 2019-162855.

[0782] << Anodizing treatment process >>

[0783] As for the steps of the anodizing treatment process, there is no particular limitation as long as the micropores described above can be obtained, and well-known methods can be cited.

[0784] In the anodizing treatment process, an aqueous solution of sulfuric acid, phosphoric acid, oxalic acid, or the like can be used as an electrolytic bath. For example, the concentration of sulfuric acid can be cited as 100 g / L to 300 g / L.

[0785] The conditions of the anodizing treatment can be appropriately set according to the electrolyte used, but for example, the liquid temperature can be cited as 5°C to 70°C (preferably 10°C to 60°C), the current density can be cited as 0.5 A / dm 2 to 60 A / dm 2 (preferably 1 A / dm 2 to 60 A / dm 2), a voltage of 1 V to 100 V (preferably 5 V to 50 V), an electrolysis time of 1 second to 100 seconds (preferably 5 seconds to 60 seconds), and a film amount of 0.1 g / m 2 ~ 5 g / m 2 (preferably 0.2 g / m 2 ~ 3 g / m 2 ).

[0786] <Enlarging treatment>

[0787] The enlarging treatment is a treatment for enlarging the diameter (pore diameter) of the micropores present in the anodized film formed by the anodizing treatment process described above (pore diameter enlarging treatment).

[0788] The enlarging treatment can be performed by contacting the aluminum plate obtained by the anodizing treatment process described above with an acid aqueous solution or an alkali aqueous solution. The method of contact is not particularly limited, and for example, dipping and spraying can be mentioned.

[0789] The support can have a back coating layer containing an organic high molecular compound described in Japanese Patent Laid-Open No. 5-45885 or a siloxane compound described in Japanese Patent Laid-Open No. 6-35174, etc. on the side opposite to the image recording layer, as needed.

[0790] <Undercoat layer>

[0791] The lithographic printing plate precursor according to the present application 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 the adhesion of the support to the image recording layer in the exposed portion, and makes the image recording layer easy to be peeled from the support in the unexposed portion, and thus the undercoat layer contributes to the improvement of the developability without impairing the print durability. Furthermore, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, and thus also has the effect of preventing the heat generated by exposure from diffusing to the support, resulting in the decrease of sensitivity.

[0792] As the compound used in the undercoat layer, a polymer having an adsorptive group and a hydrophilic group which can be adsorbed to the surface of the support can be mentioned. In order to improve the adhesion to the image recording layer, a polymer having an adsorptive group and a hydrophilic group, and also a cross-linkable group is preferable. The compound used in the undercoat layer can be a low molecular compound or a polymer. The compound used in the undercoat layer can be used by mixing two or more kinds as needed.

[0793] In the case where the compound used in the undercoat layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a cross-linkable group is preferable.

[0794] As the adsorptive group capable of adsorbing to the surface of the support, a phenolic hydroxyl group, a carboxyl group, -PO3H2, -OPO3H2, -CONHSO2-, -SO2NHSO2-, -COCH2COCH3 are preferable. As the hydrophilic group, a sulfo group or a salt thereof, a salt of a carboxyl group are preferable. As the crosslinking group, an acryloyl group, a methacryloyl group, an acrylamide group, a methacrylamide group, an allyl group, etc. are preferable.

[0795] The polymer can have a crosslinking group introduced by a salt of a polar substituent of the polymer and a compound having a substituent having a charge opposite to the above-mentioned polar substituent and an ethylenically unsaturated bond, and can further be copolymerized with a monomer other than the above-mentioned, preferably a hydrophilic monomer.

[0796] Specifically, it is preferable to select a silane coupling agent having an ethylenic double bond reactive group capable of addition polymerization described in Japanese Patent Application Laid-Open No. 10-282679, a phosphorus compound having an ethylenic double bond reactive group described in Japanese Patent Application Laid-Open No. 2-304441. It is also preferable to use a low molecular or high molecular compound having a crosslinking group (preferably an ethylenically unsaturated bond group), a functional group interacting with the surface of the support, and a hydrophilic group described in Japanese Patent Application Laid-Open Nos. 2005-238816, 2005-125749, 2006-239867, 2006-215263.

[0797] As a more preferable compound, a high molecular polymer having an adsorptive group capable of adsorbing to the surface of the support, a hydrophilic group, and a crosslinking group described in Japanese Patent Application Laid-Open Nos. 2005-125749 and 2006-188038 can be mentioned.

[0798] The content of the ethylenically unsaturated bond group in the polymer used in the primer layer is preferably 0.1 mmol to 10.0 mmol per 1 g of the polymer, more preferably 0.2 mmol to 5.5 mmol.

[0799] 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.

[0800] -Hydrophilic Compound-

[0801] From the viewpoint of development, the primer layer preferably contains a hydrophilic compound.

[0802] As the hydrophilic compound, there is no particular limitation, and a publicly known hydrophilic compound used in the primer layer can be used.

[0803] As the hydrophilic compound, a salt of a phosphonic acid having an amino group, an organic phosphonic acid, an organic phosphoric acid, an organic phosphinic acid, an amino acid, and a hydroxyl group-containing amine hydrochloride are preferably selected.

[0804] Further, as the hydrophilic compound, a compound having an amino group or a functional group having a polymerization inhibiting ability and a group interacting 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 a salt thereof, hydroxyethylethylenediaminetriacetic acid or a salt thereof, dihydroxyethylenediaminediacetic acid or a salt thereof, hydroxyethyliminodiacetic acid or a salt thereof, and the like) is preferably selected.

[0805] As the hydrophilic compound, from the viewpoint of scratch contamination inhibiting ability, a hydroxycarboxylic acid or a salt thereof is preferably contained.

[0806] Further, from the viewpoint of scratch contamination inhibiting ability, the hydrophilic compound, preferably a hydroxycarboxylic acid or a salt thereof, is preferably contained in the layer on the above-mentioned aluminum support. Further, the layer on the above-mentioned aluminum support is preferably a layer on the side where the image recording layer is formed, and is preferably a layer in contact with the above-mentioned aluminum support.

[0807] As the layer on the above-mentioned aluminum support, as the layer in contact with the above-mentioned aluminum support, a primer layer or an image recording layer is preferably selected. Further, the hydrophilic compound, preferably a hydroxycarboxylic acid or a salt thereof, can be contained in a layer other than the layer in contact with the above-mentioned aluminum support, for example, a protective layer or an image recording layer.

[0808] In the lithographic printing plate precursor according to the present application, from the viewpoint of scratch contamination inhibiting ability, the image recording layer preferably contains a hydroxycarboxylic acid or a salt thereof.

[0809] Further, in the lithographic printing plate precursor according to the present application, a method of surface-treating the surface of the image recording layer side of the aluminum support with a composition (for example, an aqueous solution or the like) containing at least a hydroxycarboxylic acid or a salt thereof is also preferably selected. In the case of the above-mentioned method, the treated hydroxycarboxylic acid or a salt thereof can be detected in at least a part in the state of being contained in a layer on the image recording layer side in contact with the aluminum support (for example, an image recording layer or a primer layer).

[0810] By containing a hydroxycarboxylic acid or a salt thereof in a layer on the image recording layer side in contact with the aluminum support, such as a primer layer, the surface of the image recording layer side of the aluminum support can be hydrophilized, and the contact angle with water based on the air bubble drop method on the surface of the image recording layer side of the aluminum support can be easily set to 110° or less, and the scratch contamination inhibiting ability is excellent.

[0811] The hydroxycarboxylic acid is a general term for an organic compound having one or more carboxyl groups and one or more hydroxyl groups in one molecule, and is also referred to as a hydroxy acid, an oxo acid, a hydroxycarboxylic acid, or an alcoholic acid (see Iwanami Shoten, published (1998), "Iwanami Rikagaku Jiten (5th edition)".

[0812] The above hydroxycarboxylic acid or salt thereof is preferably represented by the following formula (HC).

[0813] R HC (OH) mhc (COOM HC ) nhc Formula (HC)

[0814] In formula (HC), R HC represents an organic group having mhc+nhc valence, M HC independently represents a hydrogen atom, an alkali metal, or onium, and mhc and nhc independently represent an integer of 1 or more. In the case where n is 2 or more, M can be the same or different.

[0815] In formula (HC), as the organic group having mhc+nhc valence represented by R HC , mhc+nhc-valent hydrocarbon groups and the like can be given. The hydrocarbon group can have a substituent and / or a linking group.

[0816] As the hydrocarbon group, there can be mentioned mhc+nhc-valent groups derived from aliphatic hydrocarbons such as alkylene, alkane triyl, alkane tetrayl, alkane pentayl, alkenylene, alkene triyl, alkene tetrayl, alkene pentayl, alkynylene, alkyn triyl, alkyn tetrayl, alkyn pentayl, etc., and mhc+nhc-valent groups derived from aromatic hydrocarbons such as arylene, aralkane triyl, aralkane tetrayl, aralkane pentayl, etc. As the substituent, there can be mentioned alkyl, alkenyl, alkynyl, aralkyl, aryl, etc. As specific examples of the substituent, there can be mentioned methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, sec-butyl, t-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, 2-norbornyl, methoxymethyl, methoxyethoxymethyl, allyloxymethyl, phenoxymethyl, acetyloxymethyl, benzoyloxymethyl, benzyl, phenethyl, α-methylbenzyl, 1-methyl-1-phenylethyl, p-methylbenzyl, cinnamyl, allyl, 1-propenylmethyl, 2-butenyl, 2-methylallyl, 2-methylpropenylmethyl, 2-propynyl, 2-butynyl, 3-butynyl, phenyl, biphenyl, naphthyl, tolyl, xylyl, mesityl, cuminyl, methoxyphenyl, ethoxyphenyl, phenoxyphenyl, acetoxyphenyl, benzoyloxyphenyl, methoxycarbonylphenyl, ethoxycarbonylphenyl, phenoxycarbonylphenyl, etc. Furthermore, the linking group is composed of at least one atom selected from the group consisting of hydrogen atom, carbon atom, oxygen atom, nitrogen atom, sulfur atom and halogen atom, and the number of atoms is preferably 1 to 50. Specifically, there can be mentioned alkylene, substituted alkylene, arylene, substituted arylene, etc., and it can have a structure in which a plurality of these divalent groups are linked by any one of amide bond, ether bond, urethane bond, urea bond and ester bond.

[0817] As the alkali metal represented by M HC Lithium, sodium, potassium, etc. are mentioned, and sodium is particularly preferred. As the onium, there can be mentioned ammonium, phosphonium, sulfonium, etc., and ammonium is particularly preferred.

[0818] Furthermore, from the viewpoint of scratch contamination inhibitory properties, M HC It is preferably an alkali metal or onium, and more preferably an alkali metal.

[0819] The total number of mhc and nhc is preferably 3 or more, more preferably 3 to 8, and further preferably 4 to 6.

[0820] The molecular weight of the above hydroxycarboxylic acid or salt thereof is preferably 600 or less, more preferably 500 or less, and particularly preferably 300 or less. Furthermore, the above molecular weight is preferably 76 or more.

[0821] As the hydroxycarboxylic acid or the hydroxycarboxylic acid constituting the salt of the hydroxycarboxylic acid, specifically, there can be mentioned 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, leucic acid, mevalonic acid, pantothenic acid, ricinolic acid, erucic acid, cerebric acid, quinic acid, shikimic acid, monohydroxybenzoic acid derivatives (salicylic acid, pyroligneous acid (homosalicylic acid, hydroxy(methyl)benzoic acid), vanillic acid, syringic acid, etc.), dihydroxybenzoic acid derivatives (pyrogallol, dihydroxybenzoic acid, protocatechuic acid, gentisic acid, orsellinic acid, etc.), trihydroxybenzoic acid derivatives (gallic acid, etc.), phenylacetic acid derivatives (mandelic acid, benzoinic acid, atrolactic acid, etc.), hydrogenated cinnamic acid derivatives (o-hydroxyphenylpropionic acid, phloretic acid, coumaric acid, umbellic acid, caffeic acid, ferulic acid, sinapic acid, cerebric acid, kermesic acid, etc.), and the like.

[0822] Among these, as the hydroxycarboxylic acid or the hydroxycarboxylic acid constituting the salt of the hydroxycarboxylic acid, from the viewpoint of scratch contamination inhibition, a compound having two or more hydroxyl groups is preferable, a compound having three or more hydroxyl groups is more preferable, a compound having five or more hydroxyl groups is further preferable, and a compound having five to eight hydroxyl groups is particularly preferable.

[0823] Further, as the compound having one carboxyl group and two or more hydroxyl groups, gluconic acid or shikimic acid is preferable.

[0824] As the compound having two or more carboxyl groups and one hydroxyl group, citric acid or malic acid is preferable.

[0825] As the compound having two or more carboxyl groups and one hydroxyl group, citric acid or malic acid is preferable.

[0826] Among these, as the hydroxycarboxylic acid, gluconic acid is particularly preferable.

[0827] The hydrophilic compound can be used singly or in combination of two or more.

[0828] In the case where the base coat layer contains the hydrophilic compound, preferably the hydroxycarboxylic acid or the salt thereof, the content of the hydrophilic compound, preferably the hydroxycarboxylic acid and the salt thereof, is preferably 0.01 to 50 mass%, more preferably 0.1 to 40 mass%, and particularly preferably 1.0 to 30 mass%, relative to the total mass of the base coat layer.

[0829] In the base coat layer, in addition to the above-mentioned base coat layer compound, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, or the like can be further contained for the purpose of preventing contamination over time.

[0830] The base coat layer can be applied by a publicly known method.

[0831] 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 .

[0832] The lithographic printing plate precursor according to the present application can have other layers in addition to the above.

[0833] There is no particular limitation on the other layers, and publicly known layers can be used. For example, a back coating layer can be provided on the side of the support opposite to the image-recording layer side, as needed.

[0834] <Method for producing lithographic printing plate and lithographic printing method>

[0835] The method for producing a lithographic printing plate using the lithographic printing plate precursor according to the present application is not particularly limited, but preferably includes a step of exposing the lithographic printing plate precursor to light in an image shape (exposure step) and a step of supplying at least one selected from the group consisting of a printing ink and a dampening solution to the exposed lithographic printing plate precursor on a printing machine to remove the image-recording layer from the non-image area (on-press development step).

[0836] The method for producing a lithographic printing plate using the lithographic printing plate precursor according to the present application is not particularly limited, but preferably includes a step of exposing the lithographic printing plate precursor to light in an image shape (exposure step) and a step of supplying at least one selected from the group consisting of a printing ink and a dampening solution to the exposed lithographic printing plate precursor on a printing machine to remove the image-recording layer from the non-image area (on-press development step).

[0837] <Exposure step>

[0838] The method for producing a lithographic printing plate using the lithographic printing plate precursor according to the present application preferably includes an exposure step of exposing the lithographic printing plate precursor to light in an image shape and forming an exposed area and an unexposed area. The lithographic printing plate precursor according to the present application is preferably exposed to light in an image shape by laser exposure using a transparent original image having a line image, a dot image, or the like or by laser beam scanning based on digital data.

[0839] A light source having a wavelength of 750 nm to 1,400 nm is preferably used. As the light source having a wavelength of 750 nm to 1,400 nm, a solid laser and a semiconductor laser that radiate infrared rays are preferable. With respect to the infrared laser, the output power is preferably 100 mW or more, the exposure time per 1 pixel is preferably within 20 microseconds, and the irradiation energy is preferably 10 mJ / cm 2 ~ 300 mJ / cm 2Further, in order to shorten the exposure time, it is preferable to use a multi-beam laser device. The exposure mechanism can be any one of an inside drum system, an outside drum system, a flat plate system, and the like.

[0840] As for the image exposure, it can be performed by a conventional method using a plate making machine or the like. In the case of on-press development, the image exposure can be performed on a press after mounting the lithographic printing plate precursor on the press.

[0841] <On-press development step>

[0842] The method for producing a lithographic printing plate using the lithographic printing plate precursor of the present application preferably includes an on-press development step of supplying at least one selected from a printing ink and a dampening solution to the press to remove the image recording layer from the non-image area.

[0843] Hereinafter, the on-press development method will be described.

[0844] <On-press development method>

[0845] In the on-press development method, the image-exposed lithographic printing plate precursor is preferably made into a lithographic printing plate by supplying an oily ink and an aqueous component to the press and removing the image recording layer from the non-image area.

[0846] That is, if, after the image exposure of the lithographic printing plate precursor, no development treatment is performed and it is directly mounted on a press, or if, after the lithographic printing plate precursor is mounted on a press, the image exposure is performed on the press, and then an oily ink and an aqueous component are supplied and printing is performed, at the initial stage of the middle of the printing, in the non-image area, the image recording layer that has not been cured by either or both of the supplied oily ink and aqueous component is dissolved or dispersed and removed, and thus a hydrophilic surface is exposed in that portion. On the other hand, in the exposed area, the image recording layer that has been cured by the exposure forms an oily ink-accepting portion having an oleophilic surface. The compound that is initially supplied to the plate can be either an oily ink or an aqueous component, but from the aspect of preventing contamination by the component of the image recording layer that has been removed from the aqueous component, it is preferable to initially supply an oily ink. In this way, the lithographic printing plate precursor is on-press developed on the press and directly used for multiple printing. As the oily ink and the aqueous component, a general printing ink and dampening solution for lithography are preferably used.

[0847] As the laser for the image exposure of the lithographic printing plate precursor using the lithographic printing plate precursor of the present application, a light source having a wavelength of 750 nm to 1,400 nm is preferably used. The light source having a wavelength of 750 nm to 1,400 nm can be preferably used as the light source described above.

[0848] <Printing step>

[0849] The lithographic printing method using the lithographic printing plate precursor of the present application includes a printing step of supplying a printing ink to the lithographic printing plate and printing a recording medium.

[0850] There is no particular limitation on the printing ink, and various known inks can be used as needed. Also, as the printing ink, an oily ink or an ultraviolet-curable ink (UV ink) is preferably selected.

[0851] Also, in the above printing step, a dampening solution can be supplied as needed.

[0852] Also, in the above printing step, it is not necessary to stop the printing machine, and the printing can be continuously performed in the above on-press development step or the above development with a developer solution step.

[0853] There is no particular limitation on the recording medium, and a known recording medium can be used as needed.

[0854] In the production method of the lithographic printing plate using the lithographic printing plate precursor of the present application and the lithographic printing method, the entire surface of the lithographic printing plate precursor can be heated as needed before exposure, during exposure, from exposure to development. By this heating, the image formation reaction in the image recording layer can be promoted, and advantages such as an increase in sensitivity or printing durability, stabilization of sensitivity, and the like can be obtained. As for the heating before development, it is preferable to perform it under mild conditions at 150°C or lower. If the above mode is adopted, problems such as hardening of the non-image area can be prevented. As for the heating after development, it is preferable to use very strong conditions, and it is preferable to be in the range of 100°C to 500°C. If it is in the above range, sufficient image enhancement can be obtained, and problems such as deterioration of the support, thermal decomposition of the image area, and the like can be suppressed.

[0855] Example

[0856] Hereinafter, the present application will be described in detail by examples, but the present application is not limited thereto. Also, in the present examples, the " % " and the " part " mean " mass % " and " mass part ", respectively, unless otherwise specified. Also, in the high molecular compound, the molecular weight is the weight average molecular weight (Mw), and the ratio of the structural repeating unit is the mole percentage, except for the high molecular compound specifically specified. Also, the weight average molecular weight (Mw) is a value determined as a polystyrene conversion value based on the gel permeation chromatography (GPC) method.

[0857] (Examples 1 to 27 and Comparative Examples 1 to 12)

[0858] <Production of Supports A and B>

[0859] <<Treatment (A)>>

[0860] (A-a) Alkaline Etching Treatment

[0861] Etching treatment was performed by spraying an aqueous caustic soda solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% to the aluminum plate using a spray at a temperature of 70°C. Then, water washing based on the spray was performed. The amount of aluminum dissolved from the surface subjected to the electrochemical roughening treatment was 5 g / m 2 .

[0862] (A-b) Stain removal treatment using an acidic aqueous solution (1st stain removal treatment)

[0863] Next, a stain removal treatment was performed using an acidic aqueous solution. As the acidic aqueous solution used for the stain removal treatment, an aqueous solution of sulfuric acid at 150 g / L was used. The liquid temperature thereof was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate using a spray, and a stain removal treatment was performed for 3 seconds. Then, a water washing treatment was performed.

[0864] (A-c) Electrochemical roughening treatment

[0865] Next, an electrochemical roughening treatment was performed using an electrolyte having 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, and using an alternating current. The liquid temperature of the electrolyte was 30°C. The aluminum ion concentration was adjusted by adding aluminum chloride.

[0866] The waveform of the alternating current was a sine wave symmetrical between positive and negative waveforms, the frequency was 50 Hz, the anodic reaction time and the cathodic reaction time in one period of the alternating current were 1 : 1, and the current density was 75 A / dm 2 , calculated from the peak value of the current waveform of the alternating current. Also, the electric quantity was 450 C / dm 2 , calculated from the sum of the electric quantity of the aluminum plate participating in the anodic reaction. As to the electrolysis treatment, it was performed in four times at 112.5 C / dm 2 , with an electric conduction interval of 4 seconds. A carbon electrode was used as the counter electrode of the aluminum plate. Then, a water washing treatment was performed.

[0867] (A-d) Alkaline etching treatment

[0868] Etching treatment was performed by spraying an aqueous caustic soda solution having a caustic soda concentration of 5 mass% and an aluminum ion concentration of 0.5 mass% to the aluminum plate subjected to the electrochemical roughening treatment using a spray at a temperature of 45°C. The amount of aluminum dissolved from the surface subjected to the electrochemical roughening treatment was 0.2 g / m 2 . Then, a water washing treatment was performed.

[0869] (A-e) Stain removal treatment using an acidic aqueous solution

[0870] Next, an acidic aqueous solution was used for decontamination. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate using a sprayer and the decontamination was carried out for 3 seconds. The acidic aqueous solution used for decontamination was an aqueous solution with a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The solution temperature was 30°C.

[0871] (Af) Stage 1 Anodizing Treatment

[0872] Using based Figure 3 The DC electrolytic anodizing apparatus with the structure shown underwent the first stage of anodizing treatment. Anodizing was performed under the conditions specified in the "First Anodizing Treatment" column of Table 1, resulting in an anodized film of a predetermined amount.

[0873] (Ag) Hole Enlargement Treatment

[0874] Under the time conditions shown in Table 1, the aluminum plates that had undergone the above anodizing treatment were immersed in an aqueous solution of caustic soda at a temperature of 40°C, a sodium hydroxide concentration of 5% by mass, and an aluminum ion concentration of 0.5% by mass, and then subjected to a pore-expanding treatment. Afterwards, a spray-based water washing process was performed.

[0875] (Ah) Stage 2 Anodizing Treatment

[0876] Using based Figure 3 The DC electrolytic anodizing apparatus with the structure shown underwent a second-stage anodizing process. Anodizing was performed under the conditions listed in the "Second Anodizing Process" column of Table 1, resulting in an anodized film of a specified amount. However, as shown in Table 1, the second-stage anodizing process was not performed in surface treatment B.

[0877] [Table 1]

[0878]

[0879]

[0880] <Fabrication of Support C>

[0881] <<Processing (C)>>

[0882] -Alkali etching treatment-

[0883] Etching was performed on an aluminum plate by spraying an aqueous solution of caustic soda (26% by mass) and aluminum ions (6.5% by mass) using a sprayer at 70°C. A spray-based water wash was then performed. The aluminum dissolution rate on the surface after electrochemical roughening was 5 g / m². 2 .

[0884] - Dirt removal treatment using an acidic aqueous solution (1st dirt removal treatment)

[0885] Next, a dirt removal treatment was performed using an acidic aqueous solution. As the acidic aqueous solution for the dirt removal treatment, a sulfuric acid 150 g / L aqueous solution was used. The liquid temperature thereof was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate by a sprayer, and a dirt removal treatment was performed for 3 seconds. Then, a water washing treatment was performed.

[0886] - Electrochemical roughening treatment

[0887] Next, an electrochemical roughening treatment was performed using an electrolyte having 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, and using an alternating current. The liquid temperature of the electrolyte was 30°C. The aluminum ion concentration was adjusted by adding aluminum chloride.

[0888] The waveform of the alternating current was a sine wave symmetrical between positive and negative waveforms, the frequency was 50 Hz, the anode reaction time and the cathode reaction time in one period of the alternating current were 1:1, and the current density was 75 A / dm 2 , calculated from the current peak value of the waveform of the alternating current. Also, the electric quantity was 450 C / dm 2 , calculated from the sum of the electric quantity of the aluminum plate participating in the anode reaction. As to the electrolysis treatment, it was performed 4 times at 112.5 C / dm 2 , with an electric conduction interval of 4 seconds. A carbon electrode was used as the counter electrode of the aluminum plate. Then, a water washing treatment was performed.

[0889] - Dirt removal treatment using an acidic aqueous solution (1st dirt removal treatment)

[0890] Next, a dirt removal treatment was performed using an acidic aqueous solution. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate by a sprayer, and a dirt removal treatment was performed for 3 seconds. As the acidic aqueous solution for the dirt removal treatment, a sulfuric acid 170 g / L aqueous solution and an aluminum ion 5 g / L aqueous solution were used. The liquid temperature thereof was 30°C.

[0891] - Anodic oxidation treatment

[0892] An anodic oxidation treatment was performed using an anodic oxidation device based on direct current electrolysis in a sulfuric acid solution.

[0893] <Method for forming a base coat>

[0894] A base coat coating solution (1) having the following composition was applied to the support obtained so that the dry coating amount became 20 mg / m 2 , and dried using an oven at 100°C for 30 seconds, thereby forming a base coat.

[0895] - Composition of base coat coating solution (1)

[0896] • Compound for undercoat layer (P-1, 11% aqueous solution): 0.10502 parts

[0897] • Chelest 3EAF (chelating agent manufactured by CHELEST CORPORATION, sodium ethylenediaminetetraacetate): 0.0147 parts by mass

[0898] • Chelest 400 (chelating agent manufactured by CHELEST CORPORATION): 0.0658 parts by mass

[0899] • Surfactant (EMALEX 710, manufactured by NIHON EMULSION Co., Ltd.): 0.00159 parts by mass

[0900] • Preservative (Biohope L, manufactured by K I Chemical Industry Co., LTD.): 0.00149 parts

[0901] • Water: 2.87190 parts

[0902] [Chemical Formula 46]

[0903]

[0904] <Formation of image recording layer>

[0905] Any one of the image recording layer coating solutions 1 to 3 described in Table 3 was bar coated on the undercoat layer, and dried at 120°C for 40 seconds, thereby forming an image recording layer having a dry coating weight of 1.0 g / m 2 .

[0906] <Composition of image recording layer coating solution 1>

[0907] • Infrared absorber IR-1: 0.02000 parts

[0908] • Acid color developer C-1 to C-13 described in Table 3: 0.02500 parts

[0909] • Electron-accepting polymerization initiator Int-1: 0.11000 parts

[0910] • Electron-donating polymerization initiator sodium tetraphenylborate (TPB): 0.02500 parts

[0911] • Polymerizable compound M-1 to M-3 or MP-1 described in Table 3: 0.27500 parts

[0912] • Anionic surfactant A-1: 0.00600 parts

[0913] • Fluorine-based surfactant W-1: 0.00416 parts

[0914] • 2-butanone: 4.3602 parts

[0915] • 1-methoxy-2-propanol: 4.4852 parts

[0916] • Methanol: 2.2838 parts

[0917] • Microgel liquid 1: 2.3256 parts

[0918] Method for synthesizing microgel liquid 1

[0919] Preparation of polyisocyanate compound

[0920] To a suspension of isophorone diisocyanate 17.78 parts (80 molar equivalents) and the following polyphenol compound (1) 7.35 parts (20 molar equivalents) in ethyl acetate 25.31 parts, bismuth tris(2-ethylhexanoate) (NEOSTANN U-600, manufactured by NITTO KASEI CO., LTD.) 0.043 parts was added and stirred. The reaction temperature was set at 50°C at the time when the heat generation was suppressed, and stirred for 3 hours to obtain an ethyl acetate solution of polyisocyanate compound (1) (50 mass%).

[0921] [Chemical Formula 47]

[0922]

[0923] Preparation of microgel

[0924] The following oil phase ingredients and water phase ingredients were mixed and emulsified using a homogenizer at 12,000 rpm for 10 minutes. After the obtained emulsion was stirred at 45°C for 4 hours, 1,8-diazabicyclo[5.4.0]undec-7-ene-octanoate (U-CAT SA102, manufactured by San-Apro Ltd.) 10 mass% aqueous solution 5.20 g was added, stirred at room temperature for 30 minutes, and left to stand at 45°C for 24 hours. The solid content concentration was adjusted to 20 mass% with distilled water to obtain a water dispersion of microgel (1). The average particle diameter was 0.28 μm as a result of measurement by a light scattering method.

[0925] ~ Oil phase ingredients ~

[0926] (In component 1) Ethyl acetate: 12.0 parts

[0927] (Ingredient 2) Adduct of trimethylolpropane (6 mole equivalents) with xylene diisocyanate (18 mole equivalents) and addition of a mono-terminal methylated polyoxyethylene (1 mole equivalent, repeating number of oxyethylene units: 90) (50 mass% ethyl acetate solution, manufactured by Mitsui Chemicals, Inc.): 3.76 parts

[0928] (Ingredient 3) Polyisocyanate compound (1) (as a 50 mass% ethyl acetate solution): 15.0 parts

[0929] (Ingredient 4) 65 mass% ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Company, Inc.): 11.54 parts

[0930] (Ingredient 5) 10% ethyl acetate solution of sulfonate type surfactant (PIONiN A-41-C, manufactured by Takemoto Oil & Fat Co., Ltd.): 4.42 parts

[0931] ~ Water phase component ~

[0932] Distilled water: 46.87 parts

[0933] <Composition of image recording layer coating liquid 2>

[0934] Electron-accepting type polymerization initiator Int-3: 0.041 parts

[0935] Infrared absorber IR-4: 0.027 parts

[0936] Infrared absorber IR-5: 0.015 parts

[0937] Polymerizable compound M-1: 0.100 parts

[0938] Polymerizable compound M-4: 0.096 parts

[0939] Polymerizable compound M-5: 0.096 parts

[0940] Polymer particle 1: 0.300 parts

[0941] Acid color developer C-4 or C-13: 0.041 parts

[0942] Hydroxypropyl cellulose: 0.030 parts

[0943] n-Propyl alcohol: 5.168 parts

[0944] 2-Butanone: 6.460 parts

[0945] 1-Methoxy-2-propanol: 1.615 parts

[0946] Methanol: 2.907 parts

[0947] <Composition of image recording layer coating liquid 3>

[0948] • Electron-accepting polymerization initiator Int-2: 0.060 parts by weight

[0949] • Infrared absorber IR-3: 0.026 parts by weight

[0950] • Electron-donating polymerization initiator TPB: 0.050 parts by weight

[0951] • Polymerizable compound M-6: 0.250 parts by weight

[0952] • Polymerizable compound M-7: 0.250 parts by weight

[0953] • Acid color developer C-6: 0.030 parts by mass

[0954] • Binder polymer (S-LEC BL-10 manufactured by SEKISUI CHEMICAL CO., LTD., polyvinyl butyral): 0.150 parts by weight

[0955] • 1-methoxy-2-propanol: 4.988 parts

[0956] • 2-butanone: 9.262 parts

[0957] The following shows each component used in the image recording layer.

[0958] [Infrared absorber]

[0959] IR-1, IR-3 to IR-5: compounds of the following structure

[0960] [Chemical Formula 48]

[0961]

[0962] [Electron-accepting polymerization initiator]

[0963] Int-1 to Int-3: compounds of the following structure

[0964] In addition, Int-3 is a salt formed from 0.5 molar equivalent of each of the following two cations and 1 molar equivalent of the following one anion.

[0965] [Chemical Formula 49]

[0966]

[0967] [Acid color developer]

[0968] C-1 to C-9: The following compounds

[0969] [Chemical Formula 50]

[0970]

[0971] C-10 to C-13: The following compounds

[0972] [Chemical Formula 51]

[0973]

[0974] [Chemical Formula 52]

[0975]

[0976] [Chemical Formula 53]

[0977]

[0978] [Polymerizable compound]

[0979] M-1: Dipentaerythritol pentaacrylate, SR-399 manufactured by Sartomer Company, Inc.

[0980] M-2: ε-Caprolactone-modified tris(2-acryloyloxyethyl) isocyanurate, A-9300-CL1 manufactured by Shin-Nakamura Chemical Co., Ltd.

[0981] M-3: A compound synthesized by the following

[0982] M-4 to M-7: The following compounds

[0983] MP-1: A compound synthesized by the following

[0984] [Chemical Formula 54]

[0985]

[0986] [Chemical Formula 55]

[0987]

[0988] <Method for synthesizing polymerizable compound M-3>

[0989] A mixed solution of Takenate D-160N (polyisocyanate-trimethylolpropane adduct, manufactured by Mitsui Chemicals, Inc.) 4.7 parts by mass, ARONIX M-403 (manufactured by TOAGOSEI CO., LTD.) in an amount such that the NCO value of Takenate D-160N and the hydroxyl value of ARONIX M-403 become 1:1, t-butylbenzoquinone 0.02 parts by mass, and methyl ethyl ketone 11.5 parts by mass was heated to 65°C. NEOSTANN U-600 (bismuth-based polycondensation catalyst, manufactured by NITTOKASET CO., LTD.) 0.11 parts by mass was added to the reaction solution, and heating was performed at the same temperature for 4 hours. The reaction solution was cooled to room temperature (25°C), and methyl ethyl ketone was added, whereby a urethane acrylate (polymerizable compound M-3) solution having a solid content of 50% by mass was synthesized.

[0990] Next, a molecular weight fraction of the urethane acrylate solution was performed using a recycling GPC (apparatus: LC908-C60, columns: JAIGEL-1H-40 and 2H-40 (manufactured by Japan Analytical Industry.)) with tetrahydrofuran (THF) eluent. The weight average molecular weight of the polymerizable compound M-3 was 20,000.

[0991] <Synthesis of Polymerizable Compound MP-1>

[0992] To a three-necked flask, 1-methoxy-2-propanol: 78.0 parts was weighed and heated to 70°C under a stream of nitrogen. To this reaction vessel, a mixed solution of BLEMMER PME-100 (methoxy diethylene glycol monomethacrylate, manufactured by Nippon Oil and Fats Company, Limited): 52.1 parts, methyl methacrylate: 21.8 parts, methacrylic acid: 14.2 parts, hexakis (3-mercaptopropionic acid) dipentaerythritol ester: 2.15 parts, V-601 (2,2'-azobis (isobutyric acid) dimethyl ester, manufactured by Wako Pure Chemical Industries, Ltd.): 0.38 parts, 1-methoxy-2-propanol: 54 parts was added dropwise over 2 hours and 30 minutes. After the completion of the dropwise addition, the temperature was raised to 80°C, and the reaction was further continued for 2 hours. A mixed solution containing V-601: 0.04 parts, 1-methoxy-2-propanol: 4 parts was added, the temperature was raised to 90°C, and the reaction was continued for 2.5 hours. After the completion of the reaction, the reaction solution was cooled to room temperature.

[0993] After the reaction solution was stirred uniformly, heating was performed at 90°C.

[0994] After 18 hours, the reaction solution was cooled to room temperature (25°C), and then diluted by adding 1-methoxy-2-propanol: 99.4 parts.

[0995] The thus obtained polymerizable compound MP-1 had a solid content of 23 mass%, and a polystyrene-conversion weight average molecular weight of 3.5 x 104 as measured by GPC.

[0996] [Chemical Formula 56]

[0997]

[0998] [Anionic surfactant]

[0999] A-1: a compound of the following structure

[1000] [Chemical Formula 57]

[1001]

[1002] [Fluorine-based surfactant]

[1003] W-1: a compound of the following structure

[1004] [Chemical Formula 58]

[1005]

[1006] [Polymer particles]

[1007] Polymer particles 1: resin particles containing a resin represented by the following formula (n = 45, Mw = 50,000, average particle diameter: 200 nm)

[1008] [Chemical Formula 59]

[1009]

[1010] [Formation of outermost layer]

[1011] An outermost layer coating solution (in which the above-mentioned outermost layer coating solution contains each component described in Table 2, and is prepared to have a solid content of 6 mass% by ion exchange water) of the composition described in Table 3 was bar coated on the image recording layer, and dried at 120°C for 60 seconds, thereby forming an outermost layer having a dry coating amount of 0.15 g / m 2 ​

[1012] [Table 2]

[1013]

[1014] The detailed contents of each component described in Table 2 are shown below.

[1015] μ water-soluble polymer

[1016] GOHSENIX L3266: Sulfonic acid-modified polyvinyl alcohol, Mw = 17,000, manufactured by Mitsubishi Chemical Corporation

[1017] METOLOSE SM04: Methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd.

[1018] Mowiol 4-88: Polyvinyl alcohol, manufactured by Sigma-Aldrich Co. LLC

[1019] Mowiol 8-88: Polyvinyl alcohol, manufactured by Sigma-Aldrich Co. LLC

[1020] WP-1: The following compound (Mw 45,000)

[1021] [Chemical Formula 60]

[1022]

[1023] 〔Hydrophobic polymer〕

[1024] Fine Sphere FS102: The following resin shown below, manufactured by Nippon paint Industrial Coatings Co., LTD.

[1025] [Chemical Formula 61]

[1026]

[1027] 〔Acid color developer〕

[1028] Phenol red: The following compound

[1029] [Chemical Formula 62]

[1030]

[1031] 〔Others〕

[1032] Microgel 2: The following resin prepared by

[1033] WR-1: The following compound

[1034] EMALEX710: polyoxyethylene lauryl ether, surfactant, manufactured by NIHON EMULSION Co., Ltd.

[1035] [Chemical Formula 63]

[1036]

[1037] <Preparation of microgel 2>

[1038] Polymeric MDI WANNATE (registered trademark) PM-200 manufactured by Wanhua Chemical Group Co., Ltd.: 6.66 g; 50 mass% ethyl acetate solution of "Takenate (registered trademark) D-116N (adduct of trimethylolpropane (TMP), m-xylylene diisocyanate (XDI), and polyethylene glycol monomethyl ether (EO90) (the following compound)": 5.46 g; 65 mass% ethyl acetate solution of the polymeric compound M-2 of the following structure: 11.53 g; ethyl acetate: 18.66 g, 1-docosanol (KALCOL 220-80 manufactured by Kao Corporation, solubility in water: <1 mass%): 0.36 g, and PIONIN (registered trademark) A-41-C manufactured by Takemoto Oil & Fat Co., Ltd.: 0.45 g were added, and an oil phase component was obtained by stirring at room temperature (25°C) for 15 minutes.

[1039] [Chemical Formula 64]

[1040]

[1041] To the obtained oil phase component, 46.89 g of distilled water as an aqueous phase component was added and mixed, and the obtained mixture was emulsified at 12,000 rpm for 12 minutes using a homogenizer to obtain an emulsified product.

[1042] To 16.66 g of distilled water, the obtained emulsified product was added, and then the stirred liquid was heated to 45°C, and the liquid was stirred for 4 hours while maintaining the liquid temperature at 45°C, whereby the ethyl acetate was distilled off from the liquid. Then, the liquid from which the ethyl acetate was distilled off was heated to 45°C, and the liquid was stirred for 48 hours while maintaining the liquid temperature at 45°C, whereby the microcapsule-type particles 2 based on the addition-polymerization-type resin were obtained in the liquid. Then, the liquid containing the particles 2 was diluted with distilled water so that the solid content concentration became 20 mass%, whereby an aqueous dispersion of the particles 2 was obtained.

[1043] The arithmetic average particle diameter of the particles 2 was measured by the above-described method, and the result was 200 nm.

[1044] <Manufacture of Lithographic Printing Plate Precursor>

[1045] The lithographic printing plate precursors used in Examples 1 to 27 and Comparative Examples 1 to 12 were each manufactured according to the support and the method of forming each layer as described in Table 3.

[1046] <Manufacture of Liner Paper>

[1047] Liner paper at pH 7: Liner paper manufactured by the following manufacturing method

[1048] Liner paper at pH 5: Liner paper manufactured by the following manufacturing method

[1049] Liner paper at pH 4: Liner paper manufactured by the following manufacturing method

[1050] Liner paper at pH 2: Liner paper manufactured by the following manufacturing method

[1051] - Manufacturing method of liner paper at pH 7 -

[1052] A bleached kraft pulp was beaten, and a neutral sizing agent of 0.4 mass% of alkyl ketene dimer (AKD) was added to the pulp diluted to a concentration of 4 mass%, and 5.0 mass% of calcium carbonate was added. A paper strength agent of 3.0 mass% with starch as the main component was applied to the pulp and papermaking was performed, and calendering was performed using a soft roll calender with a roll nip number of two and using a resin roll with a line pressure of 18 kg / cm held by a roll nip, thereby manufacturing a liner paper at pH 7.0 (determined by the above-described method. The same applies hereafter), a basis weight of 48 g / m 2 , and a moisture content of 5.5 mass%.

[1053] - Manufacturing method of liner paper at pH 5 -

[1054] A bleached kraft pulp was beaten, and a rosin-based sizing agent of 0.4 mass% was added to the pulp diluted to a concentration of 4 mass%, and aluminum sulfate was added until the pH reached 5.0. A paper strength agent of 3.0 mass% with starch as the main component was applied to the pulp and papermaking was performed, and calendering was performed in the same manner as in the manufacture of the liner paper at pH 7 described above, thereby manufacturing a liner paper at pH 5.0, a basis weight of 42 g / m 2 , and a moisture content of 7.0 mass%.

[1055] - Manufacturing method of liner paper at pH 4 -

[1056] A bleached kraft pulp was beaten, and a rosin-based sizing agent was added to the pulp diluted to a concentration of 4% by mass, and aluminum sulfate was added until the pH reached 4.0. A paper strength agent containing starch as a main component was applied to the pulp at 3.0% by mass, and papermaking was performed, and calendering was performed in the same manner as in the production of the backing paper having a pH of 7 described above, thereby producing a backing paper having a pH of 4.0, a basis weight of 42 g / m2, and a moisture content of 7.0% by mass. 2

[1057] Method for producing backing paper having a pH of 2

[1058] A bleached kraft pulp was beaten, and a rosin-based sizing agent was added to the pulp diluted to a concentration of 4% by mass, and aluminum sulfate was added until the pH reached 2.0. A paper strength agent containing starch as a main component was applied to the pulp at 3.0% by mass, and papermaking was performed, and calendering was performed in the same manner as in the production of the backing paper having a pH of 7 described above, thereby producing a backing paper having a pH of 2.0, a basis weight of 42 g / m2, and a moisture content of 7.0% by mass. 2

[1059] <Production of a laminate>

[1060] The above-mentioned lithographic printing plate precursor of 62 cm x 40 cm, the backing paper shown below having the same size as the above-mentioned lithographic printing plate precursor, a backing paper board (ABC-5), and an aluminum kraft paper were conditioned at 25°C, 70% RH for 1 hour, and it was confirmed that the humidity of the backing paper and the backing paper board reached equilibrium. The above-mentioned lithographic printing plate precursor and the above-mentioned backing paper were alternately stacked 50 sheets each under the condition of 25°C, 70% RH, and a backing paper board (ABC-5) was further overlapped above and below, and the package was performed using an aluminum kraft paper. The above-mentioned package was left to stand for 3 days in a 50°C environment without artificial control of humidity, and the laminate of Example 1 to Example 27 and Comparative Example 1 to Comparative Example 12 was produced. In addition, in the above-mentioned laminate, the above-mentioned lithographic printing plate precursor was all stacked with the support side down.

[1061] <Evaluation of a laminate>

[1062] 〔Inhibitory property of spot-like color defects〕

[1063] The above-mentioned lithographic printing plate precursor in the laminate produced in the above-mentioned manner was observed, and the number of spot-like defects in 1 cm x 1 cm square was counted and evaluated in the following manner. The higher the score, the fewer the spot-like defects.

[1064] 5 points: The number of spot-like defects was 0 or more and less than 5

[1065] 4 points: The number of spot-like defects was 5 or more and less than 30 ​​

[1066] 3 points: the number of spot defects is 30 or more and less than 80

[1067] 2 points: the number of spot defects is 80 or more and less than 120

[1068] 1 point: the number of spot defects is 120 or more

[1069] 〔On-press developability〕

[1070] The above-mentioned lithographic printing plate precursor was exposed (equivalent to an irradiation energy of 110 mJ / cm2) under the conditions of an output power of 27 W, an outer drum rotation speed of 450 rpm, and a resolution of 2,400 dpi (dot per inch, 1 inch = 2.54 cm) using Magnus 800 Quantum manufactured by Kodak Company equipped with an infrared semiconductor laser. 2 The exposure image contained a solid image and an Amplitude Modulated Screening 3% dot image.

[1071] The obtained exposed precursor was mounted on a cylinder of a printing machine SX-74 manufactured by Heidelberger Druckmaschinen AG without developing treatment. A fountain solution circulation tank with a capacity of 100 L equipped with a non-woven fabric filter and a temperature control device was connected to the printing machine. The fountain solution S-Z1 (manufactured by Fujifilm Corporation) 2.0 mass% of 80 L was charged into the circulation device, and a UV-curable ink (UV ink), T&K UV OFS K-HS ink GE-M (manufactured by T&K TOKA Corporation) was used as a printing ink, and after the fountain solution and the ink were supplied by a standard automatic printing start method, printing was performed on 500 sheets of Tokubishi Art (continuous amount: 76.5 kg, manufactured by Mitsubishi Paper Mills Limited) paper at a printing speed of 10,000 sheets per hour.

[1072] In the printing, the number of sheets of the printing paper required until the state where the ink was not transferred to the non-image area was measured as on-press developability. The smaller the number, the better the on-press developability can be said to be. The results are shown in Table 3.

[1073] 〔Visual recognition evaluation conditions〕

[1074] The exposure of the lithographic printing plate precursor was performed on a "Fuji" character having a size of 3 to 14 dots as an image of the exposed portion under the same conditions as in the on-press developability evaluation. The exposed lithographic printing plate precursor was placed vertically with respect to the ground under a white light of 800 lux, and a tester stood at a distance of 1 m from the plate after the exposure, and the minimum number of dots of the character accurately read with both eyes was evaluated. The evaluation was performed within 30 minutes after the exposure of the lithographic printing plate precursor. The average of 10 testers was calculated, and the visual recognition was evaluated according to the following criteria.

[1075] Evaluation criteria

[1076] A 3 dots or more and less than 5 dots

[1077] B 5 dots or more and less than 6 dots

[1078] C 6 dots or more and less than 7 dots

[1079] D 7 dots or more and less than 9 dots

[1080] E 9 dots or more and less than 11 dots

[1081] F 11 dots or more

[1082] [Table 3]

[1083]

[1084] Further, ΔL represents the change in lightness of the exposed portion of the lithographic printing plate precursor before and after exposure when the lithographic printing plate precursor is exposed based on infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm 2 , ε represents the maximum value of the molar absorption coefficient ε of the chromophore produced by the above-mentioned acid developer in the range of 400 nm to 800 nm, and λmax represents the maximum absorption wavelength (and the second largest maximum absorption wavelength) of the image-recording layer in the wavelength range of 380 nm to 750 nm when exposed based on infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm 2 .

[1085] From the results described in Table 3, it was found that the spot-like color defect inhibitory property of the laminated lithographic printing plate precursor was excellent in the laminated body according to the present application compared to the laminated body according to the comparative example.

[1086] Further, it was found that the on-press developability of the laminated lithographic printing plate precursor was also excellent in the laminated body according to the present application.

[1087] The embodiment with a larger ΔL was evaluated as good in visual recognition compared with the embodiment with a smaller ΔL. Also, in the embodiments with a larger ΔL (e.g., Embodiment 1 to Embodiment 3), a laminate with excellent resistance to spot-like color defects over time was obtained in the case where the liner paper was used in a neutral state (pH 7).

[1088] The entire disclosure of Japanese Patent Application 2020-095074, filed May 29, 2020, is incorporated by reference herein.

[1089] All of the literature, patent applications and technical standards cited in this specification are hereby incorporated by reference to the same extent as if each individual publication, application, or document was specifically and individually indicated to be incorporated by reference.

[1090] Explanation of symbols

[1091] 12a, 12b - aluminum support, 14 - base coat layer, 16 - image recording layer, 18 - aluminum plate, 20a, 20b - anodized film, 22a, 22b - micropores, 24 - large-diameter hole portion, 26 - small-diameter hole portion, D - depth of large-diameter hole portion, 610 - anodizing treatment device, 612 - power supply tank, 614 - electrolytic treatment tank, 616 - aluminum plate, 618, 26 - electrolytic solution, 620 - power supply electrode, 622, 628 - rollers, 624 - pinch roller, 630 - electrolytic electrode, 632 - tank wall, 634 - direct current power source.

Claims

1. A laminate, which is a laminate of a lithographic printing plate and a backing paper, The lithographic printing plate master is an on-machine developing lithographic printing plate master containing acid developer in at least any one layer. The pH of the liner paper is above 5. The acid colorimetric agent comprises a compound represented by any of the following formulas (Le-1) to (Le-3) or the following compound CL-5. In formulas (Le-1) to (Le-3), ERG independently represents an electron-donating group, X1 to X4 independently represent a hydrogen atom, a halogen atom, or a dialkylaniline group, and X5 to X 10 Each of the following groups independently represents a hydrogen atom, a halogen atom, or a monovalent organic group. Y1 and Y2 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. Rb1 to Rb4 independently represent a hydrogen atom, an alkyl group, or an aryl group.

2. The laminated body according to claim 1, wherein, At 110mJ / cm 2 When the energy density is used for exposure to infrared light with a wavelength of 830 nm, the brightness change ΔL of the exposed portion of the original offset printing plate before and after the exposure is 5.0 or more.

3. The laminate according to claim 1 or 2, wherein, The maximum value of the molar absorptivity ε of the chromogen generated by the acid chromogenic agent at 400 nm to 800 nm is 25,000 to 200,000.

4. The laminate according to claim 1 or 2, wherein, The original lithographic printing plate has a support and an image recording layer.

5. The laminated body according to claim 4, wherein, The image recording layer contains the acid colorimetric agent.

6. The laminate according to claim 5, wherein, At 110mJ / cm 2 When the energy density is used for exposure to infrared light with a wavelength of 830 nm, the maximum absorption wavelength of the image recording layer in the wavelength range of 380 nm to 750 nm is 400 nm to 650 nm.

7. The laminate according to claim 5, wherein, At 110mJ / cm 2 The ratio of the chromogenic agent to the total mass of the acid chromogenic agent and the chromogenic agent produced by the acid chromogenic agent when exposed to infrared light at an energy density of 830 nm is 15 mol% to 100 mol%.

8. The laminate according to claim 4, wherein, The image recording layer contains polymeric compounds with a molecular weight of less than 2500. The content of the polymeric compound with a molecular weight of 2500 or less is 50% by mass or less relative to the total mass of the image recording layer.

9. The laminate according to claim 4, wherein, The image recording layer contains a polymer with a weight-average molecular weight of 10,000 or more. The content of the polymer with a weight-average molecular weight of 10,000 or more is 10% by mass or more relative to the total mass of the image recording layer.

10. The laminate according to claim 4, wherein, The original lithographic printing plate also has an outermost layer on the image recording layer.

11. The laminate according to claim 10, wherein, The outermost layer contains a color-changing compound.

12. The laminate according to claim 11, wherein, The color-changing compounds include compounds that develop color upon exposure to infrared light.

13. The laminate according to claim 11, wherein, The color-changing compound includes decomposable compounds that decompose upon exposure to infrared light.

14. The laminate according to claim 11, wherein, The color-changing compound is anthocyanin.

15. The laminate according to claim 11, wherein, The color-changing compound is a compound represented by the following formula 1-1. In Equation 1-1, R 1 R represents a group represented by any of the following formulas 2-1 to 4-1. 11 ~R 18 Each of the following can be used independently to represent a hydrogen atom, a halogen atom, and -R. a -OR b -SR c or -NR d R e R a ~R e Each of the following groups independently represents a hydrocarbon group: A1, A2, and multiple R groups. 11 ~R 18 The links can be chosen to form a single ring or multiple rings, where A1 and A2 independently represent oxygen, sulfur, or nitrogen atoms, respectively, and n 11 and n 12 Each of the integers from 0 to 5 can be represented independently, where n 11 and n 12 The total is 2 or more, n 13 and n 14 Each can be independently represented as 0 or 1, and L represents an oxygen atom, a sulfur atom, or -N (R). 10 )-,R 10 Represents a hydrogen atom, alkyl group, or aryl group; Za represents a counter ion that neutralizes the charge. In equations 2-1 to 4-1, R 20 R 30 R 41 and R 42 Each group independently represents an alkyl or aryl group, Zb represents a counterion that neutralizes the charge, and the wavy line represents the bonding site with the group represented by L in Formula 1-1.

16. The laminate according to claim 11, wherein, The color-changing compound contains the acid color-developing agent.

17. The laminate according to claim 10, wherein, The outermost layer contains a water-soluble polymer.

18. The laminate according to claim 17, wherein, The water-soluble polymer contains polyvinyl alcohol with a saponification degree of 50% or higher.

19. The laminate according to claim 10, wherein, The outermost layer contains an esterifying agent.

20. The laminate according to claim 4, wherein, The image recording layer contains an infrared absorber, an electron-accepting polymerization initiator, and an electron-donating polymerization initiator.

21. The laminate according to claim 20, wherein, The image recording layer comprises a compound formed by a salt of a cation having an electron-accepting polymerization initiator structure and an anion having an electron-donating polymerization initiator structure, which serves as the electron-accepting polymerization initiator and the electron-donating polymerization initiator.

22. The laminate according to claim 20, wherein, The electron-accepting polymerization initiator comprises a compound represented by the following formula (II), In equation (II), X A R represents a halogen atom. A It represents an aryl group.

23. The laminate according to claim 20, wherein, The HOMO value of the infrared absorber and the HOMO value of the electron-donating polymerization initiator are below 0.70 eV.

24. The laminate according to claim 20, wherein, The LUMO of the electron-accepting polymerization initiator and the LUMO of the infrared absorber are both below 0.70 eV.

25. The laminate according to claim 8, wherein, The polymeric compounds with a molecular weight of less than 2500 include polymeric compounds with 7 or more functions.

26. The laminate according to claim 8, wherein, The polymeric compounds with a molecular weight of less than 2500 include polymeric compounds with more than 10 functions.

27. The laminate according to claim 4, wherein, The support has an aluminum plate and an anodized aluminum 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 along the depth direction from the surface of 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.

28. The laminate according to claim 27, wherein, The micropores consist of a large-diameter pore portion and a small-diameter pore portion. The large-diameter pore portion extends from the surface of the anodic oxide film to a depth of 10 nm to 1000 nm. The small-diameter pore portion is connected to the bottom of the large-diameter pore portion and extends from the connection point to a depth of 20 nm to 2000 nm. The average diameter of the large-diameter aperture on the surface of the anodic oxide film is 15 nm to 100 nm. The average diameter of the small-diameter hole at the connecting position is less than 13 nm.

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