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

Abstract

Provided is a machine-developable lithographic printing plate precursor, and a method for producing a lithographic printing plate or a lithographic printing method using the machine-developable lithographic printing plate precursor, the machine-developable lithographic printing plate precursor having a support and an image-recording layer on the support, the image-recording layer containing a polymerizable compound and a polymerization initiator, an infrared absorber, and a chromophore precursor, a chromophore generated from the chromophore precursor having: an absorption maximum wavelength in a range of 380 nm or more and less than 580 nm and having a difference of 0.1 or more from an absorbance of the chromophore precursor; and an absorption maximum wavelength in a range of 580 nm or more and 750 nm or less and having a difference of 0.07 or more from the absorbance of the chromophore precursor.

Description

Technical Field

[0001] This invention relates to an on-machine developing type lithographic printing plate master, a method for manufacturing lithographic printing plates, and a lithographic printing method. Background Technology

[0002] Typically, a lithographic printing plate consists of an oleophilic image area that receives ink during the printing process and a hydrophilic non-image area that receives dampening solution. Lithographic printing is a method that utilizes the repulsive property of water and oil-based inks. The oleophilic image area of ​​the lithographic printing plate serves as the ink receiving area, and the hydrophilic non-image area serves as the dampening solution receiving area (non-ink receiving area). This difference in ink adhesion is created on the surface of the lithographic printing plate, causing the ink to adhere only to the image area. The ink is then transferred to the substrate, such as paper, for printing.

[0003] To produce this lithographic printing plate, conventionally, lithographic printing master plates (PS plates) with an oleophilic photosensitive resin layer (image recording layer) on a hydrophilic support have been widely used. Typically, a lithographic printing plate is obtained by exposing the lithographic printing master plate to an original image such as high-contrast film, leaving a portion of the image recording layer as the image area. This image recording layer is then removed by dissolving and removing any unnecessary image recording layers using an alkaline developer or organic solvent, thus exposing the surface of the hydrophilic support and forming a non-image area.

[0004] Furthermore, due to increasing concern for the Earth's environment, environmental problems related to waste liquids accompanying wet processing such as developing processes have become apparent.

[0005] To address the aforementioned environmental issues, the focus shifted to simplifying or eliminating the need for pretreatment in development or plate making. As one of the simplest manufacturing methods, a method called "in-machine development" was developed. This involves exposing the original lithographic printing plate and then directly mounting it onto the printing press without the usual development process, while removing unnecessary portions of the image recording layer at the initial stage of the normal printing process.

[0006] In this invention, the lithographic printing plate original that can be used for such on-machine development is referred to as an "on-machine developing type lithographic printing plate original".

[0007] As a previous lithographic printing original, for example, the lithographic printing original described in Patent Document 1 can be cited.

[0008] Patent document 1 describes a lithographic printing plate original, characterized in that it has a layer on a support comprising a compound represented by formula 1 and an adhesive polymer.

[0009] [Chemical Formula 1]

[0010]

[0011] In Equation 1, R 1 R represents 1 -O bonds are broken down by heat or infrared exposure, R 2 and R 3 Each can be independently represented by a hydrogen atom or an alkyl group, R 2 and R 3 They can be connected to form a ring, Ar 1 and Ar 2 Each group independently represents a group that forms a benzene ring or a naphthalene ring, Y 1 and Y 2 Each of the oxygen atom, sulfur atom, and -NR atom can be represented independently. 0 -or dialkylmethylene, R 4 and R 5 Each independently represents an alkyl group, R 6 ~R 9 Each can be independently represented by a hydrogen atom or an alkyl group, R 0 It represents a hydrogen atom, alkyl group, or aryl group; Za represents a counterion that neutralizes the charge.

[0012] Patent Document 1: International Publication No. 2016 / 027886 Summary of the Invention

[0013] The technical problem to be solved by the invention

[0014] One embodiment of the present invention aims to solve the problem of providing an on-machine developing type offset printing plate with excellent visual recognition and sensor readability.

[0015] Another embodiment of the present invention aims to solve the problem of providing a method for manufacturing a lithographic printing plate or a lithographic printing method using the above-described on-machine developing type lithographic printing plate original.

[0016] means for solving technical problems

[0017] The following methods are among the ways to solve the above problems.

[0018] <1> An on-machine developing type lithographic printing plate master has a support and an image recording layer on the support. The image recording layer contains a polymerizable compound, a polymerization initiator, an infrared absorber, and a chromophore precursor. The chromophore generated from the chromophore precursor has: a maximum absorption wavelength in the range of wavelength 380 nm or more and less than 580 nm, with an absorbance difference of 0.1 or more from the chromophore precursor; and a maximum absorption wavelength in the range of wavelength 580 nm or more and less than 750 nm, with an absorbance difference of 0.07 or more from the chromophore precursor.

[0019] <2> according to <1> The aforementioned in-machine developing type offset printing plate original, wherein,

[0020] The molar absorptivity ε of the aforementioned chromophores at any of the aforementioned maximum absorption wavelengths is 35,000 or higher.

[0021] <3> according to <1> or <2> The aforementioned in-machine developing type offset printing plate original, wherein,

[0022] The aforementioned chromophore precursor is a colorless pigment.

[0023] <4> according to <1> to <3> The on-machine developable lithographic printing plate original as described in any one of the following:

[0024] The aforementioned chromophore precursor is an acid chromophore.

[0025] <5> according to <1> to <4> The on-machine developable lithographic printing plate original as described in any one of the following:

[0026] The aforementioned chromophore precursors include two or more chromophore precursors.

[0027] <6> according to <5> The aforementioned in-machine developing type offset printing plate original, wherein,

[0028] The aforementioned chromophore precursors include two types of chromophore precursors.

[0029] <7> according to <1> to <6> The on-machine developable lithographic printing plate original as described in any one of the following:

[0030] In the above-mentioned chromophores, the maximum absorption wavelength in the range of 380 nm or more and less than 580 nm, and the maximum absorption wavelength with an absorbance difference of 0.1 or more from the above-mentioned chromophore precursor, is in the range of 500 nm or more and less than 580 nm, and the maximum absorption wavelength with an absorbance difference of 0.1 or more from the above-mentioned chromophore precursor.

[0031] <8> according to <1> to <7> The on-machine developable lithographic printing plate original as described in any one of the following:

[0032] In the above-mentioned chromophores, the maximum absorption wavelength in the range of 580 nm or more and 750 nm less, and the absorption difference with the above-mentioned chromophore precursor is 0.07 or more, is the maximum absorption wavelength in the range of 580 nm or more and 660 nm less, and the absorption difference with the above-mentioned chromophore precursor is 0.07 or more.

[0033] <9> according to <1> to <8> The on-machine developable lithographic printing plate original as described in any one of the following:

[0034] The ring-opening rate of the above-mentioned chromophore precursor, calculated by the following formula, is 40 mol% to 99 mol%.

[0035] Ring-opening rate = Molar absorptivity of the chromophore precursor when 1 molar equivalent of acid is added / Molar absorptivity ε of the chromophore generated from the chromophore precursor × 100

[0036] <10> A method for producing a lithographic printing plate includes the following steps: [The text abruptly ends here, so the translation stops.] <1> to <9> The on-machine developing type lithographic printing plate master is exposed to an image; and at least one of printing ink and dampening solution is supplied on the printing press to remove the image recording layer that is not an image portion.

[0037] <11> according to <10> The method for making the offset printing plate further includes the following steps:

[0038] Sensors are used to identify the original lithographic printing plate after exposure.

[0039] <12> A planographic printing method includes the following steps: <1> to <9> The on-machine developable lithographic printing plate master is exposed to an image; an image recording layer, which is not an image portion, is removed from the printing press by supplying at least one of printing ink and dampening solution to produce a lithographic printing plate; and printing is performed using the obtained lithographic printing plate.

[0040] <13> according to <12> The aforementioned offset printing method further includes the following steps:

[0041] Sensors are used to identify the original lithographic printing plate after exposure.

[0042] Invention Effects

[0043] According to one embodiment of the present invention, an in-machine developing type offset printing plate with excellent visual recognition and sensor readability can be provided.

[0044] Furthermore, according to another embodiment of the present invention, a method for producing a lithographic printing plate or a lithographic printing method using the above-described on-machine developing type lithographic printing plate original can be provided. Attached Figure Description

[0045] Figure 1 This is a schematic cross-sectional view of one preferred embodiment of the aluminum support body used in the present invention.

[0046] Figure 2 This is a schematic cross-sectional view of one embodiment of an aluminum support having an anodized coating.

[0047] Figure 3This is a graph illustrating an example of an alternating current waveform used in the electrochemical roughening process during the manufacturing of an aluminum support with an anodic oxide film.

[0048] Figure 4 This is a side view illustrating an example of a radial unit in an electrochemical roughening process using alternating current in a method for manufacturing an aluminum support with an anodized film.

[0049] Figure 5 This is a side view representing the concept of a brushing and polishing process used in the mechanical roughening treatment of an aluminum support with an anodized film during the manufacturing process.

[0050] Figure 6 This is a schematic diagram of an anodizing apparatus used in the anodizing process of a method for manufacturing an aluminum support with an anodized film. Detailed Implementation

[0051] The present invention will now be described in detail. The description of the constituent elements described below is based on a representative embodiment of the present invention, but the present invention is not limited to this embodiment.

[0052] In addition, in this specification, the "~" sign indicating a numerical range is used to imply that the numerical values ​​before and after it are included as lower and upper limits.

[0053] Furthermore, in the designation of groups (atomic groups) in this specification, the designations without substitution and unsubstituted not only include groups without substituents but also groups with substituents. For example, "alkyl" includes not only alkyl groups without substituents (unsubstituted alkyl) but also alkyl groups with substituents (substituted alkyl).

[0054] In this specification, "(meth)acrylic acid" is used as a term that includes both acrylic acid and methacrylic acid, and "(meth)acryloyl" is used as a term that includes both acryloyl and methacryloyl.

[0055] Furthermore, the term "process" in this specification includes not only independent processes, but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process can be achieved. Also, in this invention, "mass%" and "weight%" are defined the same, and "parts by mass" and "parts by weight" are defined the same.

[0056] Unless otherwise specified, each component in the composition or each constituent unit in the polymer in this invention may be contained individually or in combination with two or more.

[0057] Furthermore, in this invention, the amount of each component in the composition or each constituent unit in the polymer, in the case where there are multiple substances or constituent units that correspond to each component in the composition or each constituent unit in the polymer, refers to the total amount of the corresponding multiple substances present in the composition or the corresponding multiple constituent units present in the polymer, unless otherwise specified.

[0058] Furthermore, in this invention, a combination of two or more preferred methods is a more preferred method.

[0059] Furthermore, unless otherwise specified, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in this invention are molecular weights converted from polystyrene and measured using a gel permeation chromatography (GPC) analysis apparatus with columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all trade names manufactured by TOSOH CORPORATION) and detected by solvent THF (tetrahydrofuran) and differential refractometer as standard substances.

[0060] In this invention, the term "lithographic printing plate original" includes not only lithographic printing plate originals but also discarded originals. Furthermore, the term "lithographic printing plate" includes not only lithographic printing plates made from lithographic printing plate originals through operations such as exposure and development as needed, but also discarded plates. In the case of discarded originals, exposure and development operations are not necessarily required. Additionally, a discarded plate refers, for example, a lithographic printing plate original used when printing a portion of the printing plate in monochrome or two colors in color newspaper printing, and is mounted on an unused printing cylinder.

[0061] Furthermore, in this invention, the "*" in the chemical structural formula indicates the bonding position with other structures.

[0062] The present invention will now be described in detail.

[0063] (Original plate for in-machine developing offset printing)

[0064] The on-machine developing type lithographic printing plate master (also simply referred to as "lithographic printing plate master") involved in this invention has a support and an image recording layer on the support. The image recording layer contains a polymerizable compound, a polymerization initiator, an infrared absorber, and a chromophore precursor. The chromophore generated from the chromophore precursor has: a maximum absorption wavelength in the range of wavelength 380 nm or more and less than 580 nm, with an absorbance difference of 0.1 or more from the chromophore precursor; and a maximum absorption wavelength in the range of wavelength 580 nm or more and less than 750 nm, with an absorbance difference of 0.07 or more from the chromophore precursor.

[0065] Furthermore, the on-machine developing type lithographic printing plate original involved in this invention is preferably a negative type lithographic printing plate original.

[0066] In the printing process, it is required that the original plate of the developing offset printing plate can be read with the naked eye to detect plate-making errors and distinguish which job the plate will be used for (date, printing press, color, etc.).

[0067] Furthermore, to save manpower in the printing process, a system is being implemented that exposes and reads codes (barcodes, QR codes, etc.) on in-press developing lithographic printing plates and uses readers to automatically identify which printing (date, printing press, color, etc.) the code is intended for. Therefore, the demand for in-press developing lithographic printing plates capable of reading codes using sensors is constantly increasing.

[0068] Through in-depth research, the inventors discovered that chromophores generated from one or more chromophore precursors generally possess: a maximum absorption wavelength in the range of wavelengths above 380 nm and below 580 nm with an absorbance difference of 0.1 or more from the aforementioned chromophore precursors; and a maximum absorption wavelength in the range of wavelengths above 580 nm and below 750 nm with an absorbance difference of 0.07 or more from the aforementioned chromophore precursors, thereby achieving excellent visual recognition and sensor readability.

[0069] The following is a detailed description of each component of the original offset printing plate involved in this invention.

[0070] <Image Recording Layer>

[0071] The lithographic printing plate of the present invention has an image recording layer formed on a support.

[0072] The aforementioned image recording layer contains a polymerizable compound, a polymerization initiator, an infrared absorber, and a chromophore precursor.

[0073] The image recording layer used in this invention is preferably a negative image recording layer, and more preferably a water-soluble or water-dispersible negative image recording layer.

[0074] Regarding the lithographic printing plate original involved in this invention, from the viewpoint of machine developability, it is preferable that the unexposed portion of the image recording layer can be removed by at least one of dampening solution and printing ink.

[0075] The following is a detailed description of the components contained in the image recording layer.

[0076] [Chromosome precursor]

[0077] The image recording layer described above includes a chromophore precursor, and the chromophore generated from the chromophore precursor has: a maximum absorption wavelength in the range of wavelength 380 nm or more and less than 580 nm, with an absorbance difference of 0.1 or more from the chromophore precursor; and a maximum absorption wavelength in the range of wavelength 580 nm or more and less than 750 nm, with an absorbance difference of 0.07 or more from the chromophore precursor.

[0078] The aforementioned chromophore precursor can be one of the following: the generated chromophore has a maximum absorption wavelength in the range of wavelengths above 380 nm and below 580 nm, or in the range of wavelengths above 580 nm and below 750 nm. Alternatively, it can be one or more chromophore precursors with a maximum absorption wavelength in the range of wavelengths above 380 nm and below 580 nm, or one or more chromophore precursors with a maximum absorption wavelength in the range of wavelengths above 580 nm and below 750 nm. However, from the viewpoints of visual recognition, sensor readability, and ink turbidity suppression, it is preferable to include two or more chromophore precursors, and more preferably, two chromophore precursors.

[0079] From the viewpoint of visual recognition and ink turbidity suppression, the absorbance difference between the wavelength of the above-mentioned wavelength of 380 nm and 580 nm and that of the above-mentioned chromophore precursor is preferably 0.12 or more, more preferably 0.15 or more and 0.30 or less.

[0080] Furthermore, in the chromophore generated from the aforementioned chromophore precursor, from the viewpoint of visual recognition and ink turbidity suppression, the maximum absorption wavelength in the range of 380 nm or more and less than 580 nm, with an absorbance difference of 0.1 or more from the aforementioned chromophore precursor, is preferably in the range of 500 nm or more and less than 580 nm, with an absorbance difference of 0.1 or more from the aforementioned chromophore precursor; more preferably, it is in the range of 530 nm or more and less than 580 nm, with an absorbance difference of 0.1 or more from the aforementioned chromophore precursor; and especially preferably, it is in the range of 550 nm or more and less than 580 nm, with an absorbance difference of 0.1 or more from the aforementioned chromophore precursor.

[0081] From the viewpoints of visual recognition, sensor readability, and ink turbidity suppression, the absorbance difference between the wavelength of the chromophore precursor and the wavelength of the chromophore precursor is preferably 0.08 or more, more preferably 0.09 or more and 0.30 or less, within the wavelength range of 580 nm or more and 750 nm.

[0082] Furthermore, in the chromophore generated from the aforementioned chromophore precursor, from the viewpoints of visual recognition, sensor readability, and ink turbidity suppression, the maximum absorption wavelength in the range of 580 nm to 750 nm and with an absorbance difference of 0.07 or more from the aforementioned chromophore precursor is preferably in the range of 580 nm to 700 nm and with an absorbance difference of 0.07 or more from the aforementioned chromophore precursor. More preferably, it is in the range of 580 nm to 660 nm and with an absorbance difference of 0.07 or more from the aforementioned chromophore precursor. Particularly preferred is the maximum absorption wavelength in the range of 585 nm to 630 nm and with an absorbance difference of 0.07 or more from the aforementioned chromophore precursor.

[0083] From the viewpoint of visual recognition and ink turbidity suppression, the molar absorptivity ε of the chromophore generated from the chromophore precursor at any of the above-mentioned maximum absorption wavelengths is preferably 35,000 or more, more preferably 35,000 or more and 200,000 or less, and particularly preferably 50,000 or more and 150,000 or less.

[0084] From the viewpoint of visual recognition and ink turbidity suppression, the molar absorptivity ε of the chromophore generated from the chromophore precursor at the maximum absorption wavelength in the range of wavelengths above 380 nm and below 580 nm is preferably 35,000 or more, more preferably 35,000 or more and 200,000 or less, and particularly preferably 50,000 or more and 150,000 or less.

[0085] From the viewpoints of visual recognition, sensor readability, and ink turbidity suppression, the molar absorptivity ε of the chromophore generated from the aforementioned chromophore precursor at the maximum absorption wavelength in the range of 580 nm or more and 750 nm or less is preferably 10,000 or more, more preferably 12,000 or more and 100,000 or less, and particularly preferably 15,000 or more and 80,000 or less.

[0086] Furthermore, from the viewpoints of visual recognition, sensor readability, and ink turbidity suppression, the molar absorptivity ε of the chromophore generated from the aforementioned chromophore precursor at the aforementioned maximum absorption wavelength in the range of wavelengths above 380 nm and below 580 nm is preferably greater than the molar absorptivity ε of the chromophore generated from the aforementioned chromophore precursor at the aforementioned maximum absorption wavelength in the range of wavelengths above 580 nm and below 750 nm.

[0087] The maximum absorption wavelength and absorbance changes of the chromophore generated from the chromophore precursor in this invention are determined by the following method.

[0088] Using a Kodak Trendsetter Q800 equipped with an infrared semiconductor laser, the original lithographic printing plate was exposed (equivalent to an irradiation energy of 110 mJ / cm²) at an output power of 14 W, an external drum speed of 360 rpm, and a resolution of 2,400 dpi (dots per inch, 1 inch is 2.54 cm). 2 The exposed image includes a solid image. The reflectance spectra of the solid image portion and the non-image portion were measured using a Konica Minolta, Inc. CM-2600d spectrochromistate, and the absorbance was calculated based on the reflectance. The wavelength at which the difference in absorbance between the solid image portion and the non-image portion reaches its maximum value was defined as the maximum absorption wavelength, and the absorbance change at that wavelength was calculated.

[0089] The molar absorptivity ε of the chromophore produced from the chromophore precursor in this invention is determined by the following method.

[0090] Accurately weigh 0.04 mmol of the chromophore precursor into a 100 mL volumetric flask.

[0091] Add approximately 90 mL of acetic acid. After visually confirming that the sample has completely dissolved, dilute the solution to 100 mL with acetic acid to prepare pigment solution A.

[0092] After adding approximately 80 mL of acetic acid to another 100 mL volumetric flask, use a 5 mL full-volume pipette to add 5 mL of ion-exchanged water and 5 mL of the above-mentioned pigment solution A, and gently shake to mix.

[0093] After visually confirming that no chromophore precursor has precipitated, the solution was diluted to 100 mL with acetic acid to prepare pigment solution B. The concentration of the chromophore precursor in pigment solution B was 0.02 mmol / L.

[0094] Pigment solution B was filled into the measurement unit (quartz glass, optical path width 10 mm), and the measurement was performed using a UV-Vis spectrophotometer (manufactured by SHIMADZU CORPORATION, UV-1800).

[0095] The blank culture medium was set as a water:acetic acid = 5:95 solution.

[0096] The maximum absorption wavelengths in the range of wavelengths above 380 nm and below 580 nm and in the range of wavelengths above 580 nm and below 750 nm are read from the obtained spectrum, and the molar absorptivity ε is calculated based on the absorbance at these wavelengths.

[0097] Furthermore, using pigment solution A (chromophore precursor) and pigment solution B (chromophore), measurements were performed using the aforementioned UV-Vis spectrophotometer. Based on the obtained spectra, the absorbance changes at the aforementioned maximum absorption wavelengths within the range of wavelengths above 380 nm and below 580 nm, and the absorbance changes at the aforementioned maximum absorption wavelengths within the range of wavelengths above 580 nm and below 750 nm were calculated.

[0098] Regarding the aforementioned chromophore precursor, from the viewpoint of visual recognition, the ring-opening rate calculated by the following formula is preferably 2% to 100%, more preferably 5% to 60%, and especially preferably 10% to 40%.

[0099] Ring-opening rate = (Molar absorptivity of the chromophore precursor when 1 molar equivalent of acid is added) / (Molar absorptivity ε of the chromophore generated from the chromophore precursor) × 100

[0100] The ring-opening rate described above in this invention is determined by the following method.

[0101] -Preparation of Pigment Solution C-

[0102] Accurately weigh 0.1 mmol of the chromophore precursor into a 50 mL volumetric flask.

[0103] Add approximately 40 mL of acetonitrile. After visually confirming that the sample has completely dissolved, dilute the solution to 50 mL with acetonitrile to prepare pigment solution C.

[0104] Preparation of acid solution D-

[0105] Add 0.2 mmol of CSA (10-camphorsulfonic acid) to a 100 mL volumetric flask, and add about 80 mL of acetonitrile. After confirming that the CSA is completely dissolved, make up the volume to 100 mL with acetonitrile to prepare acid solution D.

[0106] -Preparation of assay solution E-

[0107] Add 5 mL of ion-exchanged water to a 100 mL volumetric flask using a full-volume pipette, and then add 80 mL of acetonitrile. Add 1 mL of pigment solution C and 1 mL of acid solution D, and dilute to 100 mL with acetonitrile to prepare the assay solution E.

[0108] The concentration of the chromophore precursor containing the chromophore generated in assay solution E is 0.02 mmol / L.

[0109] The test solution E was filled into the test unit (quartz glass, optical path width 10 mm), and the measurement was performed using a UV-Vis spectrophotometer (manufactured by SHIMADZU CORPORATION, UV-1800).

[0110] The blank culture medium was set as a water:acetonitrile solution of 5:95.

[0111] The maximum absorption wavelength in the visible light region (380 nm to 750 nm) is read from the obtained spectrum, and the molar absorptivity ε is calculated based on the absorbance at that wavelength.

[0112] Calculate the open-loop rate using the following formula.

[0113] Ring-opening rate = (Molar absorptivity of the chromophore precursor when 1 molar equivalent of acid is added) / (Molar absorptivity of the chromophore precursor) × 100

[0114] In addition, when the image recording layer has two or more chromophore precursors, the ring-opening rate of each chromophore precursor is measured to confirm whether it meets the above range.

[0115] From the viewpoint of visual recognition and color development, acid colorant is preferred as the chromophore precursor mentioned above.

[0116] Furthermore, from the viewpoint of visual recognition and color development, colorless pigments are preferred as chromophore precursors.

[0117] The "chromophore precursor" used in this invention refers to a compound that exhibits color development upon stimulation by light, acid, or the like, and changes the color of the image recording layer. Furthermore, the "acid chromophore" refers to a compound that exhibits color development upon heating in a state where it has received protons from an electron-accepting compound (e.g., an acid). As an acid chromophore, colorless compounds having partial skeletons such as lactones, lactams, sulfolactones, spiropyrans, esters, or amides are particularly preferred, and these partial skeletons rapidly undergo ring-opening or cleavage upon contact with an electron-accepting compound.

[0118] From the viewpoint of visual recognition and color development, the chromophore precursor used in this invention is preferably at least one compound selected from spiropyran compounds, spiroxazine compounds, spironolactone compounds, and spironolactam compounds.

[0119] From the perspective of visibility, the preferred hue for the chromophore after coloring is green, blue, or black.

[0120] Furthermore, from the viewpoint of visual recognition and color development, the aforementioned acid colorant is preferably a colorless pigment.

[0121] As for the aforementioned colorless pigment, there are no particular restrictions as long as it has a colorless structure, but it is preferred to have a helical structure, and more preferably to have a spironolactone ring structure.

[0122] Furthermore, from the viewpoint of colorimetric properties and visual recognition of the exposed portion, the colorless pigment described above is preferably a colorless pigment having a phthaloyl structure or a fluorane parent structure.

[0123] From the perspectives of visual recognition, UV printing durability, and stability over time, the aforementioned chromophore precursor preferably has two or more electron-donating groups that are directly bonded to the aromatic ring.

[0124] From the viewpoint of colorimetry and visual recognizability of the exposed portion, the electron-donating group is preferably amino, alkylamino, arylamino, dialkylamino, monoalkylmonoarylamino, diarylamino, alkoxy, aryloxy, or alkyl. More preferably, it is amino, alkylamino, arylamino, dialkylamino, monoalkylmonoarylamino, diarylamino, alkoxy, or aryloxy. Even more preferably, it is monoalkylmonoarylamino or diarylamino, and especially preferably monoalkylmonoarylamino.

[0125] Furthermore, from the viewpoints of visual recognition, UV printing durability, and stability over time, a zeolite structure is preferred as the aforementioned chromophore precursor.

[0126] Furthermore, from the viewpoints of visual recognition, UV printing durability and stability over time, the chromophore precursor preferably contains a compound represented by formula (Z-1) or formula (Z-2), and more preferably contains a compound represented by formula (Z-1).

[0127] [Chemical Formula 2]

[0128]

[0129] In formulas (Z-1) and (Z-2), EDG independently represents an electron-donating group, X represents O or NR, R represents a hydrogen atom, alkyl, aryl or heteroaryl, Y1 and Y2 independently represent CH or N, and Ra1 represents a hydrogen atom, alkyl or alkoxy.

[0130] From the viewpoint of colorimetry and visual recognizability of the exposed part, the electron-donating group in the EDG of formulas (Z-1) and (Z-2) is preferably amino, alkylamino, arylamino, dialkylamino, monoalkylmonoarylamino, diarylamino, alkoxy, aryloxy, or alkyl, more preferably amino, alkylamino, arylamino, dialkylamino, monoalkylmonoarylamino, diarylamino, alkoxy, or aryloxy, and even more preferably monoalkylmonoarylamino or diarylamino, especially monoalkylmonoarylamino.

[0131] Furthermore, from the viewpoints of visual recognition, UV printing durability and stability over time, it is more preferable for the chromophore precursor to contain a compound represented by the following formula (Z-3) or formula (Z-4), and it is especially preferable for the chromophore precursor to contain a compound represented by the following formula (Z-3).

[0132] [Chemical Formula 3]

[0133]

[0134] In formulas (Z-3) and (Z-4), Ra1 represents a hydrogen atom, alkyl or alkoxy group, Rb1 to Rb4 represent hydrogen atom, alkyl or aryl group, Rb1 and Rb2, Rb3 and Rb4 can form a ring, and Y1 and Y2 represent CH or N respectively.

[0135] From the viewpoints of visual recognition, UV printing durability and stability over time, Rb1 and Rb4 in formulas (Z-3) and (Z-4) are preferably alkyl or aryl, and more preferably aryl.

[0136] From the viewpoints of visual recognition, UV printing durability and stability over time, Rb2 and Rb3 in formulas (Z-3) and (Z-4) are preferably alkyl or aryl, and more preferably alkyl.

[0137] From the viewpoints of visual recognition, UV printing durability and stability over time, Ra1 in formula (Z-4) is preferably a hydrogen atom or an alkoxy group, and more preferably a hydrogen atom.

[0138] Furthermore, in Equations (Z-3) and (Z-4), from the viewpoint of color development and visual recognizability of the exposed part, Y1 and Y2 are preferably C.

[0139] The alkyl groups in formulas (Z-1) to (Z-4) can be straight chains, branched chains, or ring structures.

[0140] Furthermore, the number of carbon atoms of the alkyl group in formulas (Z-1) to (Z-4) is preferably 1 to 20, more preferably 1 to 8, even more preferably 1 to 4, and especially preferably 1 or 2.

[0141] The number of carbon atoms in the aryl group in formulas (Z-1) to (Z-4) is preferably 6 to 20, more preferably 6 to 10, and especially preferably 6 to 8.

[0142] Furthermore, the alkyl, aryl, and other groups in formulas (Z-1) to (Z-4) can have substituents. Examples of substituents include alkyl, aryl, halogen, amino, alkylamino, arylamino, dialkylamino, monoalkylmonoarylamino, diarylamino, hydroxyl, alkoxy, aryloxy, acyl, alkoxycarbonyl, aryloxycarbonyl, and cyano. Moreover, these substituents can be further replaced by other substituents.

[0143] Furthermore, from the viewpoints of visual recognition, sensor readability and color development, the chromophore precursor preferably contains a compound represented by the following formula (Z-5).

[0144] [Chemical Formula 4]

[0145]

[0146] In formula (Z-5), ERG represents electron-donating groups independently, n11 represents an integer from 1 to 5, X1 to X4 represent hydrogen atoms, halogen atoms or dialkylaniline groups independently, Y1 and Y2 represent C or N independently, X1 does not exist when Y1 is N, X4 does not exist when Y2 is N, and Rb5 and Rb6 represent hydrogen atoms, alkyl, aryl or heteroaryl groups independently.

[0147] From the viewpoint of visual recognizability and color development, the electron-donating group in the ERG of formula (Z-5) is preferably amino, alkylamino, arylamino, heteroarylamino, dialkylamino, monoalkyl monoarylamino, monoalkyl monoheteroarylamino, diarylamino, diheteroarylamino, monoaryl monoheteroarylamino, alkoxy, aryloxy, heteroaryloxy, or alkyl. More preferably, it is amino, alkylamino, arylamino, heteroarylamino, dialkylamino, monoalkyl monoarylamino, monoalkyl monoheteroarylamino, diarylamino, diheteroarylamino, monoaryl monoheteroarylamino, alkoxy, or aryloxy. Even more preferably, it is monoalkyl monoarylamino, diarylamino, diheteroarylamino, or monoaryl monoheteroarylamino, and especially preferably monoalkyl monoarylamino.

[0148] Furthermore, from the viewpoint of visual recognition and color development, the electron-donating group in the aforementioned ERG is preferably a disubstituted amino group having an aryl group with a substituent at at least one ortho position or a heteroaryl group with a substituent at at least one ortho position. More preferably, it is a disubstituted amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position. Even more preferably, it is an amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position, and an amino group having an aryl group or a heteroaryl group with an electron-donating group. In particular, it is an amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position, and an amino group having an aryl group or an electron-donating group with an electron-donating group.

[0149] In addition, in this invention, the adjacent position in aryl or heteroaryl groups other than phenyl refers to the bonding position (e.g., position 2, etc.) adjacent to the aforementioned position 1 when the bonding position of the aryl or heteroaryl group with other structures is set to position 1.

[0150] Furthermore, from the viewpoint of visual recognition and color development, the electron-donating group of the aforementioned aryl or heteroaryl group is preferably amino, alkylamino, arylamino, heteroarylamino, dialkylamino, monoalkylmonoarylamino, monoalkylmonoheteroarylamino, diarylamino, diheteroarylamino, monoarylmonoheteroarylamino, alkoxy, aryloxy, heteroaryloxy, or alkyl, more preferably alkoxy, aryloxy, heteroaryloxy, or alkyl, and especially preferably alkoxy.

[0151] From the viewpoint of visual recognition and color development, Rb5 in formula (Z-5) is preferably alkyl, aryl or heteroaryl, and more preferably alkyl.

[0152] From the viewpoint of visual recognition and color development, Rb6 in formula (Z-5) is preferably alkyl, aryl or heteroaryl, more preferably alkyl, and especially preferably methyl.

[0153] From the perspective of visual recognition and color development, Y1 and Y2 in formula (Z-5) are preferably at least one of them is C, and more preferably both Y1 and Y2 are C.

[0154] From the viewpoint of visual recognition and color development, X1 to X4 in formula (Z-5) are preferably hydrogen atoms or chlorine atoms, and more preferably hydrogen atoms.

[0155] In formula (Z-5), n11 is preferably an integer from 1 to 3, and more preferably 1 or 2.

[0156] The following compounds are examples of preferred colorless pigments. Additionally, Me represents methyl, Et represents ethyl, Oct represents octyl, and Ph represents phenyl.

[0157] [Chemical Formula 5]

[0158]

[0159] [Chemical Formula 6]

[0160]

[0161] Furthermore, from the viewpoint of visual recognition and ink turbidity suppression, the aforementioned chromophore precursor preferably includes a decomposition-type infrared absorber.

[0162] The aforementioned decomposition-type infrared absorber is preferably an infrared absorber that has the function of absorbing infrared rays through infrared exposure and decomposing them to produce color.

[0163] Hereinafter, the chromophore formed by the absorption and decomposition of infrared radiation by decomposition-type infrared absorbers through infrared exposure will also be referred to as the "chromophore of decomposition-type infrared absorbers".

[0164] Furthermore, the decomposition-type infrared absorber preferably has the function of absorbing infrared rays through infrared exposure and converting the absorbed infrared rays into heat.

[0165] Regarding the above-mentioned decomposition-type infrared absorber, it is sufficient to absorb at least a portion of the light in the infrared wavelength region (wavelength 750nm to 1mm) and decompose it. However, it is preferable to be an infrared absorber with a maximum absorption wavelength in the wavelength region of 750nm to 1,400nm, and more preferably an infrared absorber with a maximum absorption wavelength in the wavelength region of 760nm to 900nm.

[0166] More specifically, the decomposition-type infrared absorber is preferably a compound that decomposes upon infrared exposure and generates a compound with a large absorption wavelength in the range of wavelengths above 380 nm and below 580 nm.

[0167] The aforementioned decomposable infrared absorber is preferably an infrared absorber that decomposes through thermal or electron transfer caused by infrared exposure, or both. More preferably, it is an infrared absorber that decomposes through electron transfer caused by infrared exposure. Here, "decomposition through electron transfer" means that electrons excited from the HOMO (highest occupied molecular orbital) to the LUMO (lowest unoccupied molecular orbital) of the decomposable infrared absorber by infrared exposure are transferred within the molecule to electron-accepting groups (groups with potential close to the LUMO), thereby causing decomposition.

[0168] Furthermore, as an infrared absorber that decomposes through infrared exposure, the infrared absorber described in International Publication No. 2020 / 262692 is preferred.

[0169] Furthermore, as an infrared absorber that decomposes through infrared exposure, the infrared absorber described in Japanese Patent Publication No. 2008-544322 or International Publication No. 2016 / 027886 is preferred.

[0170] Furthermore, as a decomposable infrared absorber, anthocyanin is preferably an infrared absorbing compound described in International Publication No. 2019 / 219560.

[0171] The following are specific examples of infrared absorbers that decompose by infrared exposure, but the present invention is not limited to these.

[0172] [Chemical Formula 7]

[0173]

[0174] [Chemical Formula 8]

[0175]

[0176] [Chemical Formula 9]

[0177]

[0178] From the viewpoints of visual recognition, sensor readability and ink turbidity suppression, the chromophore precursor preferably contains two or more colorless pigments, or contains one or more decomposable infrared absorbers and one or more colorless pigments, and more preferably contains two colorless pigments, or contains one decomposable infrared absorber and one colorless pigment.

[0179] Furthermore, from the viewpoints of visual recognition, sensor readability, and ink turbidity suppression, the aforementioned chromophore precursor preferably comprises a compound represented by the above formula (Z-3) or formula (Z-4) in which Rb1 and Rb3 are each independently aryl and Rb2 and Rb4 are each independently hydrogen atoms or alkyl, and a compound represented by the above formula (Z-3) or formula (Z-4) in which Rb1 to Rb3 are each independently aryl.

[0180] Furthermore, from the viewpoints of visual recognition, sensor readability, and ink turbidity suppression, the chromophore precursor preferably includes the aforementioned decomposition-type infrared absorber and a compound represented by the above formula (Z-3) or formula (Z-4) in which Rb1 to Rb3 are each independently aryl.

[0181] These chromophore precursors can be used alone or in combination with two or more components.

[0182] The content of chromophore precursor is preferably 0.5% to 10% by mass, more preferably 1% to 5% by mass, relative to the total mass of the image recording layer.

[0183] [Infrared absorber]

[0184] The lithographic printing plate original involved in this invention contains an infrared absorber in the image recording layer.

[0185] There are no particular limitations on what can be used as an infrared absorber; for example, pigments and dyes can be cited.

[0186] As dyes that can be used as infrared absorbers, commercially available dyes and well-known dyes as described in publications such as "Dye Handbook" (The Society of Synthetic Organic Chemistry, Japan, 1955). Specifically, examples include azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methylene dyes, anthocyanin dyes, squaric acid pigments, pyranium salts, and metal thiol complexes.

[0187] Among these dyes, particularly preferred dyes include anthocyanins, squaric acid dyes, pyranonium salts, nickel thiol complexes, and indocyanine dyes. Anthocyanins and indocyanine dyes are also examples. Among these, anthocyanins are particularly preferred.

[0188] As the aforementioned infrared absorber, cationic polymethyl pigments having oxygen or nitrogen atoms at the meta position are preferred. Examples of cationic polymethyl pigments include anthocyanins, pyranonium pigments, thiopyridinium pigments, and azurites; from the viewpoints of ease of acquisition and solvent solubility during the induction reaction, anthocyanins are preferred.

[0189] Specific examples of anthocyanins include compounds described in paragraphs 0017-0019 of Japanese Patent Application Publication No. 2001-133969, paragraphs 0016-0021 of Japanese Patent Application Publication No. 2002-023360, and paragraphs 0012-0037 of Japanese Patent Application Publication No. 2002-040638. Preferably, compounds described in paragraphs 0034-0041 of Japanese Patent Application Publication No. 2002-278057 and paragraphs 0080-0086 of Japanese Patent Application Publication No. 2008-195018 are included. Particularly preferred are compounds described in paragraphs 0035-0043 of Japanese Patent Application Publication No. 2007-90850 and paragraphs 0105-0113 of Japanese Patent Application Publication No. 2012-206495.

[0190] Furthermore, compounds described in Japanese Patent Application Publication No. 5-5005, paragraphs 0008-0009, and Japanese Patent Application Publication No. 2001-222101, paragraphs 0022-0025, can be preferred.

[0191] As a pigment, compounds described in paragraphs 0072 to 0076 of Japanese Patent Application Publication No. 2008-195018 are preferred.

[0192] Furthermore, the infrared absorber described in International Publication No. 2020 / 262692 is preferred as the infrared absorber.

[0193] Furthermore, as an infrared absorber that decomposes through infrared exposure, the infrared absorber described in Japanese Patent Publication No. 2008-544322 or International Publication No. 2016 / 027886 is preferred.

[0194] Furthermore, from the viewpoint of print durability and dot reproducibility, the value of the highest occupied orbital (HOMO) of the infrared absorber used in this invention is preferably -5.00 eV or less, more preferably -5.30 eV or less.

[0195] Furthermore, as a lower limit, from the viewpoint of printing durability and dot reproducibility, it is preferably -5.90eV or higher, more preferably -5.75eV or higher, and even more preferably -5.60eV or higher.

[0196] In this invention, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are calculated using the following method.

[0197] First, free counterions in the compound being calculated are excluded from the calculation. For example, counterions are excluded from the calculation in cationic electron-accepting polymerization initiators and cationic infrared absorbers, and counterions are excluded from the calculation in anionic electron-donating polymerization initiators. Here, "free" means that the compound being calculated and its counterion are not covalently linked.

[0198] Structure optimization was performed using the quantum chemical calculation software Gaussian09 under DFT(B3LYP / 6-31G(d)).

[0199] The calculation of MO (molecular orbital) energies was performed using the structure obtained through the above structural optimization under DFT(B3LYP / 6-31+G(d,p) / CPCM(solvent=methanol)).

[0200] The MO energy Ebare (unit: Hartley) obtained through the above MO energy calculation is converted into Escaled (unit: eV) used as the value for HOMO and LUMO in this invention, according to the following formula.

[0201] Escaled=0.823168×27.2114×Ebare-1.07634

[0202] Additionally, 27.2114 is a coefficient used only to convert Hartley to eV, and 0.823168 and -1.07634 are adjustment coefficients to determine the HOMO and LUMO of the compounds to be calculated, so that the calculations match the measured values.

[0203] Infrared absorbers can be used in combination with one or more. Furthermore, pigments and dyes can be used in combination as infrared absorbers.

[0204] The total content of infrared absorber in the image recording layer is preferably 0.1% to 10.0% by mass relative to the total mass of the image recording layer, more preferably 0.5% to 5.0% by mass.

[0205] [Polymerizing compounds]

[0206] The image recording layer in this invention contains a polymeric compound.

[0207] In this invention, a polymerizable compound refers to a compound having polymerizable groups.

[0208] There are no particular limitations on the polymerizable group; any known polymerizable group is acceptable, but an olefinically unsaturated group is preferred. Furthermore, the polymerizable group can be a free radical polymerizable group or a cationic polymerizable group, but a free radical polymerizable group is preferred.

[0209] Examples of free radical polymerizable groups include (meth)acryloyl, allyl, vinylphenyl, and vinyl groups. From a reactivity point of view, (meth)acryloyl is preferred.

[0210] The molecular weight (weight-average molecular weight in the case of a molecular weight distribution) of the polymeric compound is preferably 50 or more and less than 2,500.

[0211] The polymerizable compounds used in this invention can be, for example, free radical polymerizable compounds or cationic polymerizable compounds, and are preferably addition polymerizable compounds (olefinic unsaturated compounds) having at least one olefinic unsaturated bond.

[0212] As an olefinically unsaturated compound, it is preferred to be a compound having at least one terminal olefinically unsaturated bond, and more preferably a compound having two or more terminal olefinically unsaturated bonds. The polymerizable compound may be in the chemical form of a monomer, prepolymer (i.e., dimer, trimer), oligomer, or mixture thereof.

[0213] Of these, from the viewpoint of print durability, polymeric compounds containing 3 or more functional groups are preferred, polymeric compounds containing 7 or more functional groups are more preferred, and polymeric compounds containing 10 or more functional groups are even more preferred. Furthermore, from the viewpoint of print durability in the obtained lithographic printing plate, the polymeric compounds preferably contain olefinically unsaturated compounds with 3 or more functional groups (preferably 7 or more functional groups, more preferably 10 or more functional groups), and even more preferably (meth)acrylate compounds with 3 or more functional groups (preferably 7 or more functional groups, more preferably 10 or more functional groups).

[0214] Furthermore, from the viewpoint of machine developability and contamination inhibition, the polymeric compound containing two or fewer functions is preferred, more preferably containing a difunctional polymeric compound, and especially preferably containing a difunctional (meth)acrylate compound.

[0215] From the viewpoints of print durability, machine developability, and contamination inhibition, the content of polymeric compounds with two or fewer functions (preferably difunctional polymeric compounds) is preferably 5% to 100% by mass, more preferably 10% to 100% by mass, and especially preferably 15% to 100% by mass, relative to the total mass of the polymeric compounds in the aforementioned image recording layer.

[0216] -Oligomers-

[0217] As a polymeric compound contained in the image recording layer, it is preferable to contain a polymeric compound as an oligomer (hereinafter also simply referred to as "oligomer").

[0218] In this invention, oligomers refer to polymeric compounds with a molecular weight (weight average molecular weight in the case of a molecular weight distribution) of 600 or more and 10,000 or less, and containing at least one polymeric group.

[0219] From the viewpoint of excellent chemical resistance and printability, the molecular weight of the oligomer is preferably 1,000 or more and 5,000 or less.

[0220] Furthermore, from the viewpoint of improving printability, the number of polymeric groups in one molecule of oligomer is preferably two or more, more preferably three or more, even more preferably six or more, and particularly preferably ten or more.

[0221] Furthermore, there is no particular upper limit to the number of polymerizable groups in the oligomer, but the number of polymerizable groups is preferably 20 or less.

[0222] From the viewpoint of printability and machine developability, the oligomer preferably has 7 or more polymeric groups and a molecular weight of 1,000 or more and 10,000 or less. More preferably, it has 7 or more and 20 or less polymeric groups and a molecular weight of 1,000 or more and 5,000 or less.

[0223] In addition, it may contain polymer components that may be generated during the manufacturing process of oligomers.

[0224] From the viewpoints of printability, visual recognizability, and machine developability, the oligomer preferably comprises at least one selected from compounds having urethane bonds, compounds having ester bonds, and compounds having epoxy residues, and more preferably comprises a compound having urethane bonds.

[0225] In this invention, an epoxy residue refers to a structure formed by an epoxy group, for example, representing a structure identical to the structure obtained by reacting an acid group (carboxylic acid group, etc.) with an epoxy group.

[0226] As a compound having a carbamate bond, the compound described in International Publication No. 2020 / 262692 is preferred.

[0227] Furthermore, as a compound having urethane bonds, a compound in which polymerizable groups are introduced into a polyurethane obtained by reacting a polyisocyanate compound with a polyol compound can be used.

[0228] For example, a compound having urethane bonds can be obtained by reacting a compound having epoxy and polymerizable groups with a polyurethane oligomer, which is obtained by reacting a polyol compound having acid groups with a polyisocyanate compound.

[0229] The number of polymerizable groups in compounds having ester bonds, which are examples of oligomers, is preferably three or more, and more preferably six or more.

[0230] Examples of oligomers include compounds containing epoxy residues, preferably compounds containing hydroxyl groups within the compound.

[0231] Furthermore, the number of polymerizable groups in the compound having epoxy residues is preferably 2 to 6, more preferably 2 to 3.

[0232] For example, the above-mentioned compound having epoxy residues can be obtained by reacting acrylic acid with a compound having epoxy groups.

[0233] Specific examples of oligomers are shown below, but the oligomers used in this invention are not limited thereto.

[0234] As oligomers, commercially available products can be used, such as 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.), EBECRYL450, EBECRYL657, EBECRYL885, EBECRYL800, EBECRYL3416, and EBECRYL860 (all manufactured by DAICEL-ALLNEX LTD.), but are not limited to these.

[0235] From the viewpoint of improving chemical resistance, printing durability, and the inhibition of on-machine developing residue, the content of oligomers is preferably 30% to 100% by mass relative to the total mass of polymeric compounds in the image recording layer, more preferably 50% to 100% by mass, and even more preferably 80% to 100% by mass.

[0236] -Low molecular weight polymeric compounds-

[0237] Polymerizable compounds may also include polymerizable compounds other than the oligomers mentioned above.

[0238] From the viewpoint of chemical resistance, low molecular weight polymeric compounds are preferred as polymeric compounds other than oligomers. These low molecular weight polymeric compounds can be in chemical forms such as monomers, dimers, trimers, or mixtures thereof.

[0239] Furthermore, from the viewpoint of chemical resistance, the polymeric compound is preferably selected from at least one polymeric compound having three or more olefinic unsaturated groups and polymeric compounds having an isocyanurate ring structure.

[0240] In this invention, low molecular weight polymeric compounds refer to polymeric compounds with a molecular weight (weight-average molecular weight in the case of a molecular weight distribution) of 50 or more and less than 600.

[0241] From the viewpoint of excellent chemical resistance, printing durability, and inhibition of machine-developed residues, the molecular weight of the low-molecular-weight polymeric compound is preferably 100 or more and less than 600, more preferably 300 or more and less than 600, and even more preferably 400 or more and less than 600.

[0242] When the polymeric compound includes low-molecular-weight polymeric compounds as polymeric compounds other than oligomers (the total amount when two or more low-molecular-weight polymeric compounds are included), from the viewpoints of chemical resistance, printing durability, and inhibition of machine-developed residues, the ratio of the oligomer to the low-molecular-weight polymeric compound (oligomer / low-molecular-weight polymeric compound) is preferably 10 / 1 to 1 / 10 by mass, more preferably 10 / 1 to 3 / 7, and even more preferably 10 / 1 to 7 / 3.

[0243] Furthermore, as a low-molecular-weight polymerizable compound, the polymerizable compound described in paragraphs 0082 to 0086 of International Publication No. 2019 / 013268 is preferred.

[0244] 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.

[0245] From the viewpoint of print durability, the image recording layer preferably contains two or more polymeric compounds.

[0246] 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.

[0247] [Polymerization initiator]

[0248] The image recording layer in this invention contains a polymerization initiator.

[0249] Furthermore, from the viewpoints of sensitivity, printing durability, on-machine developability, and ink adhesion, the polymerization initiator preferably includes an electron-donating polymerization initiator, and more preferably includes both an electron-accepting polymerization initiator and an electron-donating polymerization initiator.

[0250] -Electron-received polymerization initiators-

[0251] The image recording layer described above preferably includes an electron-accepting polymerization initiator as a polymerization initiator.

[0252] Electron-accepting polymerization initiators are compounds that, when exposed to infrared light and the electrons of the infrared absorber are excited, accept an electron through intermolecular electron movement to generate free radicals and other polymerization initiators.

[0253] The electron-accepting polymerization initiator used in this invention is a compound that generates polymerization initiators such as free radicals or cations through the energy of light, heat or both, and can appropriately select and use known thermal polymerization initiators, compounds with bonds having low bond dissociation energy, photopolymerization initiators, etc.

[0254] As an electron-accepting polymerization initiator, a free radical polymerization initiator is preferred, and an onium salt compound is more preferred.

[0255] Furthermore, an infrared-sensitive polymerization initiator is preferred as the electron-receiving polymerization initiator.

[0256] Examples of electron-accepting free radical polymerization initiators include (a) organohalides, (b) carbonyl compounds, (c) azo compounds, (d) organic peroxides, (e) metallocene compounds, (f) azide compounds, (g) hexaaryl biimidazole compounds, (i) disulfone compounds, (j) oxime ester compounds, and (k) onium salt compounds.

[0257] (a) As an organohalide, the compounds described in paragraphs 0022 to 0023 of Japanese Patent Application Publication No. 2008-195018 are preferred, for example.

[0258] (b) As a carbonyl compound, the compounds described in paragraph 0024 of Japanese Patent Application Publication No. 2008-195018 are preferred, for example.

[0259] (c) As an azo compound, for example, the azo compound described in Japanese Patent Application Publication No. 8-108621 can be used.

[0260] (d) As an organic peroxide, the compounds described in paragraph 0025 of Japanese Patent Application Publication No. 2008-195018 are preferred, for example.

[0261] (e) As a metallocene compound, the compounds described in paragraph 0026 of Japanese Patent Application Publication No. 2008-195018 are preferred, for example.

[0262] (f) As azide compounds, examples include 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone.

[0263] (g) As a hexaaryl biimidazole compound, the compound described in paragraph 0027 of Japanese Patent Application Publication No. 2008-195018 is preferred, for example.

[0264] (i) As disulfone compounds, examples include compounds described in Japanese Patent Application Publication Nos. 61-166544 and 2002-328465.

[0265] (j) As an oxime ester compound, the compounds described in paragraphs 0028 to 0030 of Japanese Patent Application Publication No. 2008-195018 are preferred, for example.

[0266] Among the aforementioned electron-accepting polymerization initiators, oxime ester compounds and onium salt compounds are preferred from the viewpoint of curability. Of these, iodonium salt compounds, sulfonium salt compounds, or azazine onium salt compounds are preferred from the viewpoint of print durability, iodonium salt compounds or sulfonium salt compounds are more preferred, and iodonium salt compounds are particularly preferred.

[0267] Specific examples of these compounds are shown below, but the invention is not limited thereto.

[0268] Examples of iodonium salt compounds include diaryl iodonium salt compounds, especially, more preferably, diphenyl iodonium salt compounds obtained by substitution with electron-donating groups, such as alkyl or alkoxy groups, and asymmetric diphenyl iodonium salt compounds. Specific examples include diphenyliodonium = hexafluorophosphate, 4-methoxyphenyl-4-(2-methylpropyl)phenyliodonium = hexafluorophosphate, 4-(2-methylpropyl)phenyl-p-tolyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium = tetrafluoroborate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium = 1-perfluorobutylsulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, and bis(4-tert-butylphenyl)iodonium = tetraphenylborate.

[0269] Examples of sulfonium salt compounds include triarylsulfonium salt compounds, particularly those obtained by substituting at least a portion of electron-withdrawing groups, such as those on the aromatic ring, with halogen atoms. More preferably are triarylsulfonium salt compounds with a total number of halogen atoms substituting four or more on the aromatic ring. Specific examples include triphenylsulfonium-hexafluorophosphate, triphenylsulfonium-benzoylformate, bis(4-chlorophenyl)phenylsulfonium-benzoylformate, bis(4-chlorophenyl)-4-methylphenylsulfonium-tetrafluoroborate, tri(4-chlorophenyl)sulfonium-3,5-bis(methoxycarbonyl)benzenesulfonate, tri(4-chlorophenyl)sulfonium-hexafluorophosphate, and tri(2,4-dichlorophenyl)sulfonium-hexafluorophosphate.

[0270] Furthermore, as counter anions for iodonium salt compounds and sulfonium salt compounds, sulfonamide anions or sulfonamide anions are preferred, and sulfonamide anions are more preferred.

[0271] As a sulfonamide anion, arylsulfonamide anion is preferred.

[0272] Furthermore, bis(aryl)sulfonamide anion is preferred as the sulfonamide anion.

[0273] As a specific example of a sulfonamide anion or a sulfonamide anion, the anion described in International Publication No. 2020 / 262692 is preferably cited.

[0274] Furthermore, from the viewpoint of developability and printing durability in the obtained lithographic printing plate, the aforementioned electron-receiving polymerization initiator may contain a compound represented by the following formula (II).

[0275] [Chemical Formula 10]

[0276]

[0277] In equation (II), X A R represents a halogen atom. A It represents an aryl group.

[0278] As X in equation (II) A Specifically, examples include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Among these, chlorine atoms or bromine atoms are preferred due to their excellent sensitivity, and bromine atoms are particularly preferred.

[0279] Furthermore, in equation (II), as R A From the perspective of achieving an excellent balance between sensitivity and storage stability, aryl groups substituted with amide groups are preferred.

[0280] As a specific example of an electron-receiving polymerization initiator represented by the above formula (II), the polymerization initiator described in International Publication No. 2020 / 262692 can be preferred.

[0281] From the viewpoint of improving sensitivity and reducing wear, the minimum unoccupied molecular orbital (LUMO) of the electron-receiving polymerization initiator is preferably -3.00 eV or less, more preferably -3.02 eV or less.

[0282] Furthermore, as a lower limit, it is preferably -3.80 eV or higher, and more preferably -3.60 eV or higher.

[0283] Electron-accepting polymerization initiators can be used alone or in combination with two or more.

[0284] The content of the electron-receiving polymerization initiator is preferably 0.1% to 50% by mass relative to the total mass of the image recording layer, more preferably 0.5% to 30% by mass, and particularly preferably 0.8% to 20% by mass.

[0285] -Electron-donating polymerization initiators-

[0286] From the viewpoint of improving the chemical resistance and printing durability of offset printing plates, the polymerization initiator preferably includes an electron-donating polymerization initiator, and more preferably includes both an electron-donating polymerization initiator and the aforementioned electron-accepting polymerization initiator.

[0287] Five examples of electron-donating polymerization initiators can be cited.

[0288] (i) Alkyl or arylate complexes: These are thought to involve the oxidative cleavage of carbon-heterobonds, generating active free radicals. Examples include borates.

[0289] (ii) Glycine compounds: It is assumed that an active free radical is generated by the cleavage of the CX bond on the carbon adjacent to nitrogen due to oxidation. Preferably, X is a hydrogen atom, a carboxyl group, a trimethylsilyl group, or a benzyl group. Specifically, examples include N-phenylglycine derivatives (which may have substituents in the phenyl group), N-phenyliminodiacetic acid (which may have substituents in the phenyl group), etc.

[0290] (iii) Sulfur-containing compounds: Compounds formed by replacing the nitrogen atom of the above-mentioned aminoacetic acid compounds with a sulfur atom can generate active free radicals through the same action. Specifically, examples include phenylthioacetic acid (which may have substituents in the phenyl group), etc.

[0291] (iv) Tin-containing compounds: Compounds obtained by replacing the nitrogen atoms of the above-mentioned aminoacetic acid compounds with tin atoms can generate active free radicals through the same action.

[0292] (v) Sulfites: These can generate reactive free radicals through oxidation. Examples include sodium arylsulfite.

[0293] Among these electron-donating polymerization initiators, the image recording layer preferably contains a borate compound. As a borate compound, a tetraarylborate compound or a monoalkyltriarylborate compound is preferred, and from the viewpoint of compound stability, a tetraarylborate compound is more preferred, and a tetraphenylborate compound is particularly preferred.

[0294] There are no particular limitations on the counter cations present in borate compounds, but alkali metal ions or tetraalkylammonium ions are preferred, and sodium ions, potassium ions or tetrabutylammonium ions are more preferred.

[0295] As a borate compound, sodium tetraphenylborate is particularly preferred.

[0296] Furthermore, from the viewpoint of chemical resistance and printability, the highest occupied orbital (HOMO) of the electron-donating polymerization initiator used in this invention is preferably -6.00 eV or more, more preferably -5.95 eV or more, even more preferably -5.93 eV or more, and particularly preferably greater than -5.90 eV.

[0297] Furthermore, as an upper limit, it is preferably below -5.00 eV, and more preferably below -5.40 eV.

[0298] Hereinafter, as a preferred example of an electron-donating polymerization initiator, the polymerization initiator described in International Publication No. 2020 / 262692 is preferably cited.

[0299] Furthermore, from the viewpoints of visual recognizability, print durability, and stability over time, the image recording layer preferably includes at least one compound selected from the onium salt compound used as the electron-accepting polymerization initiator and the borate compound used as the electron-donating polymerization initiator, and more preferably includes the onium salt compound used as the electron-accepting polymerization initiator and the borate compound used as the electron-donating polymerization initiator.

[0300] Furthermore, the image recording layer preferably contains a borate compound as the electron-donating polymerization initiator, more preferably contains a borate compound as the electron-donating polymerization initiator, and the HOMO value of the infrared absorber minus the HOMO value of the borate compound is 0.70 eV or less.

[0301] One type of electron-donating polymerization initiator can be added, or two or more can be added together.

[0302] The content of the electron-donating polymerization initiator relative to the total mass of the image recording layer is preferably 0.01% to 30% by mass, more preferably 0.05% to 25% by mass, and even more preferably 0.1% to 20% by mass.

[0303] Furthermore, one of the preferred embodiments of the present invention is that the above-mentioned electron-accepting polymerization initiator and the above-mentioned electron-donating polymerization initiator form a salt.

[0304] Specifically, for example, the aforementioned ononium salt compound may be a salt of an ononium ion and an anion (e.g., tetraphenylborate anion) in the aforementioned electron-donating polymerization initiator. More preferably, an iodonium borate compound may be an iodonium cation (e.g., di-p-tolyliodonium cation) in the aforementioned iodonium salt compound may be a salt of an iodonium borate anion in the aforementioned electron-donating polymerization initiator.

[0305] As a specific example of the formation of a salt between the aforementioned electron-accepting polymerization initiator and the aforementioned electron-donating polymerization initiator, the method described in International Publication No. 2020 / 262692 is preferably cited.

[0306] In this invention, when the image recording layer contains onium ions and the anions in the electron-donating polymerization initiator described above, the image recording layer contains both an electron-accepting polymerization initiator and the electron-donating polymerization initiator described above.

[0307] [The relationship between electron-donating polymerization initiators, electron-accepting polymerization initiators, and infrared absorbers]

[0308] The image recording layer of the present invention comprises the above-mentioned electron-donating polymerization initiator, the above-mentioned electron-accepting polymerization initiator and the above-mentioned infrared absorber. Preferably, the HOMO of the electron-donating polymerization initiator is -6.0 eV or more, and the LUMO of the electron-accepting polymerization initiator is -3.0 eV or less.

[0309] The preferred embodiments of the HOMO of the electron-donating polymerization initiator and the LUMO of the electron-accepting polymerization initiator are as described above.

[0310] It is presumed that, in the image recording layer of the present invention, at least one of the electron-donating polymerization initiator, the infrared absorber, and the electron-accepting polymerization initiator transfer energy, for example, as described in the following chemical formula.

[0311] Therefore, it is believed that if the HOMO of the above-mentioned electron-donating polymerization initiator is above -6.0 eV and the LUMO of the above-mentioned electron-accepting polymerization initiator is below -3.0 eV, the free radical generation efficiency is improved, thus making it easier to achieve better chemical resistance and printing durability.

[0312] [Chemical Formula 11]

[0313]

[0314] From the viewpoint of printability and chemical resistance, the HOMO value of the infrared absorber minus the HOMO value of the electron-donating polymerization initiator is preferably 1.0 eV or less, more preferably 0.70 eV or less, and particularly preferably 0.60 eV or less. Furthermore, from the same viewpoint, the HOMO value of the infrared absorber minus the HOMO value of the electron-donating polymerization initiator is preferably -0.200 eV or more, more preferably -0.100 eV or more. Additionally, a negative value indicates that the HOMO of the electron-donating polymerization initiator is higher than the HOMO of the infrared absorber.

[0315] Furthermore, from the viewpoint of printability and chemical resistance, the LUMO value of the aforementioned electron-accepted polymerization initiator minus the LUMO value of the aforementioned infrared absorber is preferably 1.00 eV or less, more preferably 0.700 eV or less. Also, from the same viewpoint, the LUMO value of the aforementioned electron-accepted polymerization initiator minus the LUMO value of the aforementioned infrared absorber is preferably -0.200 eV or more, more preferably -0.100 eV or more.

[0316] Furthermore, from the same perspective, the LUMO of the aforementioned electron-accepting polymerization initiator minus the LUMO of the aforementioned infrared absorber is preferably 1.00 eV to -0.200 eV, more preferably 0.700 eV to -0.100 eV. Additionally, a negative value indicates that the LUMO of the aforementioned infrared absorber is higher than the LUMO of the aforementioned electron-accepting polymerization initiator.

[0317] 〔particle〕

[0318] From the viewpoint of print durability, the aforementioned image recording layer preferably contains particles.

[0319] The particles can be organic or inorganic, but from the viewpoint of print durability, it is preferable to include organic particles, and more preferably polymer particles.

[0320] 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.

[0321] The polymer particles are preferably selected from thermoplastic resin particles, thermally reactive resin particles, polymer particles with polymerizable groups, microcapsules containing hydrophobic compounds, and microgels (crosslinked polymer particles). Among these, polymer particles or microgels with polymerizable groups are preferred. In a particularly preferred embodiment, the polymer particles contain at least one olefinically unsaturated group. The presence of such polymer particles improves the printing durability of the exposed portion and the on-machine developability of the unexposed portion.

[0322] Furthermore, from the viewpoint of printability and machine developability, the polymer particles are preferably thermoplastic resin particles.

[0323] Thermoplastic resin particles are preferably those described in Research Disclosure No. 33303 (January 1992), Japanese Patent Application Publication No. 9-123387, Japanese Patent Application Publication No. 9-131850, Japanese Patent Application Publication No. 9-171249, Japanese Patent Application Publication No. 9-171250, and European Patent No. 931647.

[0324] Specific examples of polymers constituting thermoplastic resin particles include homopolymers or copolymers or mixtures thereof of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, acrylates or methacrylates having a polyalkylene structure, etc. Copolymers comprising polystyrene, styrene, and acrylonitrile, or polymethyl methacrylate, are preferably included. The average particle size of the thermoplastic resin particles is preferably 0.01 μm to 3.0 μm.

[0325] Examples of thermoreactive resin particles include polymer particles with thermoreactive groups. Thermoreactive polymer particles form hydrophobic regions through crosslinking based on thermal reactions and changes in functional groups during crosslinking.

[0326] The thermally reactive groups in polymer particles can be functional groups that can form chemical bonds and undergo any reaction, but polymerizable groups are preferred. Examples of such groups include olefinic unsaturated groups (e.g., acryloyl, methacryl, vinyl, allyl, etc.) that undergo free radical polymerization, cationic polymerizable groups (e.g., vinyl, ethyleneoxy, epoxy, oxetyl, etc.), isocyanate groups or their blocks, epoxy groups, ethyleneoxy groups, and functional groups having active hydrogen atoms as the target of these reactions (e.g., amino, hydroxyl, carboxyl, etc.) that undergo addition reactions, carboxyl groups and hydroxyl or amino groups as the target of the reaction that undergo condensation reactions, and acid anhydrides and amino or hydroxyl groups as the target of the reaction that undergo ring-opening addition reactions.

[0327] As a microcapsule, for example, as described in Japanese Patent Application Publications Nos. 2001-277740 and 2001-277742, a microcapsule containing at least a portion of the components of an image recording layer within itself. The components of the image recording layer may also be contained outside the microcapsule. A preferred embodiment of the image recording layer containing the microcapsule is a structure in which a hydrophobic component is contained within the microcapsule, and a hydrophilic component is contained outside the microcapsule.

[0328] Microgels (crosslinked polymer particles) may contain at least a portion of the components of an image recording layer on their surface or within. In particular, from the viewpoint of the sensitivity of the obtained lithographic printing plate and the printing durability of the obtained lithographic printing plate, reactive microgels having free radical polymerizable groups on their surface are preferred.

[0329] To microencapsulate or microgel the components of this image recording layer, known methods can be applied.

[0330] Furthermore, from the viewpoint of the printing durability, stain resistance and storage stability of the obtained lithographic printing plate, polymer particles obtained by reacting a polyisocyanate compound having two or more hydroxyl groups in the molecule with an adduct of isophorone diisocyanate and a compound having active hydrogen are preferred.

[0331] As the aforementioned polyphenolic compounds, compounds having multiple benzene rings with phenolic hydroxyl groups are preferred.

[0332] As a compound having the aforementioned active hydrogen, a polyol compound or a polyamine compound is preferred, a polyol compound is more preferred, and at least one compound selected from propylene glycol, glycerol and trimethylolpropane is even more preferred.

[0333] As for the resin particles obtained by reacting a polyisocyanate compound, which is an adduct of a polyphenol compound having two or more hydroxyl groups in the molecule and an isophorone diisocyanate, the polymer particles described in paragraphs 0032 to 0095 of Japanese Patent Application Publication No. 2012-206495 are preferred examples.

[0334] Furthermore, from the viewpoint of the printability and solvent resistance of the obtained lithographic printing plate, it is preferable that the polymer particles have a hydrophobic backbone and include both i) a constituent unit having a side cyano group directly bonded to the hydrophobic backbone and ii) a constituent unit having a side group containing a hydrophilic polyoxyalkylene segment.

[0335] An acrylic resin chain is preferably used as the hydrophobic backbone mentioned above.

[0336] Examples of the aforementioned side cyano groups are preferably -[CH2CH(C≡N)]- or -[CH2C(CH3)(C≡N)]-.

[0337] Furthermore, the constituent units having the aforementioned side cyano groups can be readily derived from olefinic unsaturated monomers, such as acrylonitrile or methacrylonitrile or combinations thereof.

[0338] Furthermore, the epoxide in the hydrophilic polyepoxide segment is preferably ethylene oxide or propylene oxide, more preferably ethylene oxide.

[0339] The number of repeating epoxide structures in the above-mentioned hydrophilic polyepoxide segments is preferably 10 to 100, more preferably 25 to 75, and even more preferably 40 to 50.

[0340] As for the particles of a resin having a hydrophobic main chain and comprising i) a constituent unit having a side cyano group directly bonded to the hydrophobic main chain and ii) a constituent unit having a side group containing a hydrophilic polyoxyalkylene segment, the particles described in paragraphs 0039 to 0068 of Japanese Patent Application Publication No. 2008-503365 are preferably examples.

[0341] Furthermore, from the viewpoint of printability and machine developability, the polymer particles mentioned above preferably have hydrophilic groups.

[0342] As for the aforementioned hydrophilic groups, there are no particular restrictions as long as the structure is hydrophilic, but examples include acid groups such as carboxyl groups, hydroxyl groups, amino groups, cyano groups, and polyepoxide structures.

[0343] From the viewpoint of machine developability and printing durability, polyepoxide structure is preferred, and polyethylene oxide structure, polypropylene oxide structure or polyethylene / propylene oxide structure is more preferred.

[0344] Furthermore, from the viewpoint of machine developability and the ability to suppress developing residues during machine development, the aforementioned polyoxyethylene structure is preferably a polyoxypropylene structure, and more preferably a polyoxyethylene structure and a polyoxypropylene structure.

[0345] Furthermore, from the viewpoint of print durability, ink adhesion and machine developability, the hydrophilic group preferably contains a constituent unit having a cyano group or a group represented by the following formula Z, more preferably contains a constituent unit represented by the following formula (AN) or a group represented by the following formula Z, and especially preferably contains a group represented by the following formula Z.

[0346] *-QWY style Z

[0347] In formula Z, Q represents a divalent linking group, W represents a divalent group with a hydrophilic structure or a divalent group with a hydrophobic structure, Y represents a monovalent group with a hydrophilic structure or a monovalent group with a hydrophobic structure, either W or Y has a hydrophilic structure, and * represents the bonding site with other structures.

[0348] [Chemical Formula 12]

[0349]

[0350] In formula (AN), R AN It represents a hydrogen atom or a methyl group.

[0351] From the viewpoint of print durability, the polymer contained in the above-mentioned polymer particles preferably contains constituent units formed of compounds having cyano groups.

[0352] The cyano group is typically introduced into the resin using a compound (monomer) containing a cyano group as the cyano-containing building block. Examples of compounds containing a cyano group include acrylonitrile compounds, with (meth)acrylonitrile being a preferred example.

[0353] As a constituent unit having a cyano group, it is preferably a constituent unit formed from an acrylonitrile compound, more preferably a constituent unit formed from (meth)acrylonitrile, that is, a constituent unit represented by the above formula (AN).

[0354] In the case where the above-mentioned polymer includes a polymer having a cyano group, from the viewpoint of print durability, the content of the cyano group in the polymer having the cyano group, preferably the group represented by the above formula (AN), is preferably 5% to 90% by mass, more preferably 20% to 80% by mass, and especially preferably 30% to 60% by mass, relative to the total mass of the polymer having the cyano group.

[0355] Furthermore, from the viewpoints of printability, ink adhesion, and machine developability, the polymer particles preferably include polymer particles having groups represented by the above formula Z.

[0356] In the above formula Z, Q is preferably a divalent linking group with 1 to 20 carbon atoms, and more preferably a divalent linking group with 1 to 10 carbon atoms.

[0357] Furthermore, Q in the above formula Z is preferably an alkylene group, an aryl group, an ester bond, an amide bond, or a combination of two or more of them, and more preferably a phenylene group, an ester bond, or an amide bond.

[0358] The divalent group with a hydrophilic structure in W of formula Z above is preferably polyalkoxide or has -CH2CH2NR bonded to one end of the polyalkoxide. W - groups. Additionally, R W It represents a hydrogen atom or an alkyl group.

[0359] The divalent group with a hydrophobic structure in W of formula Z above is preferably -R. WA -、-OR WA -O-、-R W NR WA -NR W -、-OC(=O)-R WA -O-or-OC(=O)-R WA -O-. Also, R WAEach of these can be independently represented as a straight-chain, branched, or cyclic alkylene group with 6 to 120 carbon atoms, a haloalkylene group with 6 to 120 carbon atoms, an aryl group with 6 to 120 carbon atoms, an alkarylene group (a divalent group obtained by removing one hydrogen atom from an alkylaryl group), or an aryl group with 6 to 120 carbon atoms.

[0360] The monovalent group with a hydrophilic structure in Y of formula Z is preferably -OH, -C(=O)OH, a polyalkoxide group with a hydrogen atom or alkyl group at the end, or a polyalkoxide group with a hydrogen atom or alkyl group at the end bonded to another end with -CH2CH2NR. W - group.

[0361] The monovalent group with a hydrophobic structure in Y of formula Z above is preferably a straight-chain, branched, or cyclic alkyl group with 6 to 120 carbon atoms, a haloalkyl group with 6 to 120 carbon atoms, an aryl group with 6 to 120 carbon atoms, an alkylaryl group (alkylaryl group) with 7 to 120 carbon atoms, an aralkyl group with 7 to 120 carbon atoms, or an -OR group. WB -C(=O)OR WB or -OC(=O)R WB R WB This indicates an alkyl group having 6 to 20 carbon atoms.

[0362] In polymer particles having groups represented by the above formula Z, from the viewpoint of printability, ink adhesion and machine developability, it is more preferable that W is a divalent group with a hydrophilic structure, more preferably that Q is a phenylene, ester bond or amide bond, W is a polyalkoxide group, and Y is a polyalkoxide group with a hydrogen atom or alkyl end.

[0363] Furthermore, from the viewpoint of printability and machine developability, the polymer particles preferably include polymer particles having polymeric groups, and more preferably include polymer particles having polymeric groups on the particle surface.

[0364] Furthermore, from the viewpoint of print durability, the polymer particles mentioned above preferably include polymer particles having both hydrophilic and polymeric groups.

[0365] The aforementioned polymerizable groups can be cationic polymerizable groups or free radical polymerizable groups, but from a reactivity point of view, free radical polymerizable groups are preferred.

[0366] As for the polymerizable group mentioned above, there are no particular restrictions as long as it is a polymerizable group, but from the viewpoint of reactivity, olefinic unsaturated groups are preferred, vinylphenyl (styrene), (meth)acryloyloxy or (meth)acrylamido groups are more preferred, and (meth)acryloyloxy is especially preferred.

[0367] Furthermore, the polymer in the polymer particles having polymeric groups preferably has constituent units having polymeric groups.

[0368] Furthermore, polymeric groups can be introduced onto the surface of polymer particles through polymer reactions.

[0369] Furthermore, from the viewpoint of printability and machine developability, the image recording layer preferably comprises addition polymeric resin particles having dispersible groups as the polymer particles, and more preferably the dispersible groups comprise groups represented by the above formula Z.

[0370] Furthermore, from the viewpoints of print durability, ink adhesion, machine developability, and inhibition of developing residue during machine development, the aforementioned polymer particles preferably contain a resin having urea bonds.

[0371] As a resin having the aforementioned urea bonds, the resin described in International Publication No. 2020 / 262692 is preferably cited.

[0372] Furthermore, from the viewpoint of printability and machine developability, the aforementioned image recording layer preferably contains thermoplastic resin particles.

[0373] There are no particular limitations on the thermoplastic resin contained in the thermoplastic resin particles. Examples include polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, poly(methyl methacrylate), poly(ethyl methacrylate), poly(butyl methacrylate), polyacrylonitrile, polyvinyl acetate, and copolymers thereof. The thermoplastic resin may be in latex form.

[0374] The thermoplastic resin involved in this invention is preferably a resin that is melted or softened by heat generated in the exposure process described later, thereby forming part or all of the hydrophobic film forming the recording layer.

[0375] From the viewpoint of ink adhesion and printing durability, the aforementioned thermoplastic resin is preferably a resin comprising a constituent unit formed of an aromatic vinyl compound and a constituent unit having a cyano group.

[0376] As a resin having constituent units formed of aromatic vinyl compounds and constituent units having cyano groups, the resin described in International Publication No. 2020 / 262692 is preferably cited.

[0377] From the viewpoint of printability and machine developability, the thermoplastic resin contained in the above-mentioned thermoplastic resin particles preferably has hydrophilic groups.

[0378] As a hydrophilic group, there are no particular restrictions on the structure that is hydrophilic, but examples include acid groups such as carboxyl groups, hydroxyl groups, amino groups, cyano groups, and polyoxyalkylene structures.

[0379] From the viewpoint of printability and machine developability, the hydrophilic group is preferably a group having a polyepoxide structure, a group having a polyester structure, or a sulfonic acid group, more preferably a group having a polyepoxide structure or a sulfonic acid group, and even more preferably a group having a polyepoxide structure.

[0380] From the viewpoint of machine-developable properties, the poly(ethylene oxide), poly(propylene oxide), or poly(ethylene oxide / propylene oxide) structures are preferred as the aforementioned poly(ethylene oxide / propylene oxide) structures.

[0381] Furthermore, from the viewpoint of machine developability, among the aforementioned hydrophilic groups, as a polyepoxide structure, it is preferable to have a polyepoxide propylene structure, and more preferably a polyepoxide ethylene structure and a polyepoxide propylene structure.

[0382] From the viewpoint of machine developability, the number of epoxy structures in the above-mentioned polyepoxide structure is preferably 2 or more, more preferably 5 or more, even more preferably 5 to 200, and particularly preferably 8 to 150.

[0383] Furthermore, from the viewpoint of machine developability, the hydrophilic group described above is preferably a group represented by the formula Z.

[0384] From the viewpoint of printability and ink adhesion, the glass transition temperature (Tg) of the thermoplastic resin is preferably 60°C to 150°C, more preferably 80°C to 140°C, and even more preferably 90°C to 130°C.

[0385] When the thermoplastic resin particles contain two thermoplastic resins, the value obtained by the FOX formula described later is called the glass transition temperature of the thermoplastic resin.

[0386] In this invention, the glass transition temperature of the resin can be determined using differential scanning calorimetry (DSC).

[0387] The specific determination method shall be in accordance with the method described in JIS K 7121 (1987) or JIS K 6240 (2011). The glass transition temperature in this specification uses the extrapolated glass transition onset temperature (hereinafter, sometimes referred to as Tig).

[0388] The method for determining the glass transition temperature is explained in more detail.

[0389] Once the glass transition temperature is determined, maintain the temperature at approximately 50°C lower than the predicted Tg of the resin until the apparatus stabilizes. Then, heat the resin at a rate of 20°C / min to a temperature approximately 30°C higher than the end temperature of the glass transition, and plot a differential thermal analysis (DTA) curve or a DSC curve.

[0390] The extrapolated glass transition onset temperature (Tig), also known as the glass transition temperature Tg in this specification, is determined by the temperature at the intersection of the straight line drawn from the DTA curve or DSC curve that extends the baseline from the low-temperature side to the high-temperature side, and the tangent line drawn at the point where the gradient of the curve in the stepwise change portion of the glass transition is the largest.

[0391] When the thermoplastic resin particles contain two thermoplastic resins, the Tg of the thermoplastic resin particles is determined as follows.

[0392] When the Tg of the first thermoplastic resin is set as Tg1(K), the mass fraction of the first thermoplastic resin in the thermoplastic resin particles relative to the total mass of the thermoplastic resin components is set as W1, the Tg of the second thermoplastic resin is set as Tg2(K), and the mass fraction of the second resin in the thermoplastic resin particles relative to the total mass of the thermoplastic resin components is set as W2, the Tg0(K) of the thermoplastic resin particles can be deduced according to the following FOX formula.

[0393] FOX equation: 1 / Tg0 = (W1 / Tg1) + (W2 / Tg2)

[0394] Furthermore, when the thermoplastic resin particles contain three or more types of resin, or when the pretreatment liquid contains three or more types of thermoplastic resin particles with different types of thermoplastic resin, the Tg0(K) of the thermoplastic resin particles can be deduced in the same manner as described above, by setting the Tg of the nth resin as Tgn(K) and the mass fraction of the nth resin in the thermoplastic resin particles relative to the total mass of the resin components as Wn.

[0395] FOX formula: 1 / Tg0=(W1 / Tg1)+(W2 / Tg2)+(W3 / Tg3)……+(Wn / Tgn)

[0396] As a differential scanning calorimeter (DSC), for example, the Seiko Instruments Inc. EXSTAR6220 can be used.

[0397] From the viewpoint of printability durability, the arithmetic mean particle size of the thermoplastic resin particles is preferably 1 nm or more and 200 nm or less, more preferably 3 nm or more and less than 80 nm, and even more preferably 10 nm or more and 49 nm or less.

[0398] Unless otherwise specified, the arithmetic mean particle size of the thermoplastic resin particles in this invention refers to the value determined by dynamic light scattering (DLS). The determination of the arithmetic mean particle size of the thermoplastic resin particles based on DLS was performed using a Brookhaven BI-90 (manufactured by Brookhaven Instrument Company) according to the aforementioned equipment manual.

[0399] The weight-average molecular weight of the thermoplastic resin contained in the thermoplastic resin particles is preferably 3,000 to 300,000, more preferably 5,000 to 100,000.

[0400] There are no particular limitations on the manufacturing method of the thermoplastic resin contained in the thermoplastic resin particles; they can be manufactured by known methods.

[0401] For example, it can be obtained by polymerizing styrene compounds, acrylonitrile compounds, and, as needed, at least one compound selected from the above-mentioned N-vinyl heterocyclic compounds, compounds used in the formation of the above-mentioned constituent units having olefinic unsaturated groups, compounds used in the formation of the above-mentioned constituent units having acidic groups, compounds used in the formation of the above-mentioned constituent units having hydrophobic groups, and compounds used in the formation of the above-mentioned other constituent units using known methods.

[0402] As a specific example of the thermoplastic resin contained in the thermoplastic resin particles, the thermoplastic resin described in International Publication No. 2020 / 262692 is preferably cited.

[0403] The average particle size of the aforementioned particles is preferably 0.01 μm to 3.0 μm, more preferably 0.03 μm to 2.0 μm, and even more preferably 0.10 μm to 1.0 μm. Good resolution and long-term stability can be obtained within this range.

[0404] The average primary particle size of the particles described above in this invention is determined by light scattering or by taking electron micrographs of the particles. The particle size of a total of 5,000 particles is measured on the micrographs, and the average value is calculated. Furthermore, for non-spherical particles, the particle size of spherical particles having the same particle area as the particle area in the micrograph is taken as the particle size.

[0405] Furthermore, unless otherwise specified, the average particle size in this invention refers to the volume average particle size.

[0406] The aforementioned image recording layer may contain only one type of particle, particularly polymer particles, or it may contain two or more types.

[0407] Furthermore, from the viewpoint of machine developability and printing durability, the content of particles, especially polymer particles, in the image recording layer is preferably 5% to 90% by mass, more preferably 10% to 90% by mass, even more preferably 20% to 90% by mass, and particularly preferably 50% to 90% by mass, relative to the total mass of the image recording layer.

[0408] Furthermore, from the viewpoint of machine developability and printing durability, the content of polymer particles in the image recording layer is preferably 20% to 100% by mass, more preferably 35% to 100% by mass, even more preferably 50% to 100% by mass, and particularly preferably 80% to 100% by mass, relative to the total mass of the components with a molecular weight of 3,000 or more in the image recording layer.

[0409] [Adhesive polymers]

[0410] The image recording layer may contain an adhesive polymer.

[0411] The aforementioned polymer particles are not part of the aforementioned adhesive polymer. That is, the adhesive polymer is a polymer that is not in particle shape.

[0412] As the adhesive polymer, (meth)acrylic resin, polyvinyl acetal resin or polyurethane resin are preferred.

[0413] The adhesive polymer can preferably be a known adhesive polymer used in the image recording layer of a lithographic printing plate master. As an example, a detailed description will be given of the adhesive polymer used in an in-machine developing type lithographic printing plate master (hereinafter also referred to as an in-machine developing adhesive polymer).

[0414] As an adhesive polymer for in-machine development, an adhesive polymer having an epoxy chain is preferred. The adhesive polymer having an epoxy chain may have poly(epoxy) sites in the main chain or in the side chains. Furthermore, it may be a graft polymer having poly(epoxy) in the side chains, or a block copolymer consisting of blocks composed of repeating units containing poly(epoxy) and blocks composed of repeating units not containing (epoxy).

[0415] When the main chain has a poly(epoxy) site, polyurethane resin is preferred. Examples of polymers with poly(epoxy) sites in the side chains include (meth)acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, phenolic varnish-type phenolic resin, polyester resin, synthetic rubber, and natural rubber, with (meth)acrylic resin being particularly preferred.

[0416] Furthermore, as another preferred example of an adhesive polymer, a polymeric compound having a core of a polyfunctional thiol with 6 or more functions and less than 10 functions, and having a polymer chain bonded to the core via a thioether bond, and wherein the polymer chain has polymerizable groups (hereinafter also referred to as a star polymeric compound).

[0417] From the viewpoint of curability, compounds with polymeric groups such as olefinic unsaturated groups in the main chain or side chain, and more preferably in the side chain, are preferred examples of star-shaped polymeric compounds.

[0418] Examples of star-shaped polymers include those described in Japanese Patent Application Publication No. 2012-148555 or International Publication No. 2020 / 262692.

[0419] Regarding the molecular weight of the adhesive polymer, as a polystyrene conversion value based on the GPC method, the weight-average molecular weight (Mw) is preferably 2,000 or more, more preferably 5,000 or more, and even more preferably 10,000 to 300,000.

[0420] As needed, hydrophilic polymers such as polyacrylic acid and polyvinyl alcohol as described in Japanese Patent Application Publication No. 2008-195018 can be used. Furthermore, oleophilic (hydrophobic) polymers and hydrophilic polymers can also be used together.

[0421] Furthermore, from the viewpoint of print durability and machine developability, the aforementioned image recording layer preferably comprises a polymer having constituent units formed of aromatic vinyl compounds, more preferably a polymer having constituent units formed of aromatic vinyl compounds, and also comprises an infrared absorber that decomposes upon infrared exposure.

[0422] Furthermore, regarding the adhesive polymer used in this invention, for example, from the viewpoint of suppressing the decrease in machine developability over time, the glass transition temperature (Tg) is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and especially preferably 90°C or higher.

[0423] Furthermore, from the viewpoint that water can easily penetrate the image recording layer, the upper limit of the glass transition temperature of the adhesive polymer is preferably 200°C, and more preferably below 120°C.

[0424] From the viewpoint of further suppressing the decrease in machine developability over time, polyvinyl acetal is preferred as an adhesive polymer having the aforementioned glass transition temperature.

[0425] Polyvinyl alcohol acetal is a resin obtained by acetalizing the hydroxyl groups of polyvinyl alcohol with aldehydes.

[0426] In particular, polyvinyl butyral obtained by acetalizing the hydroxyl groups of polyvinyl alcohol with butyraldehyde (i.e., butyraldehyde) is preferred.

[0427] Furthermore, from the viewpoint of improving print durability, polyvinyl acetal preferably has olefin unsaturated groups.

[0428] Polyvinyl acetal is preferably represented by the polymer described in International Publication No. 2020 / 262692.

[0429] The image recording layer in this invention preferably contains a resin having fluorine atoms, and more preferably a copolymer containing fluorinated aliphatic groups.

[0430] By using resins containing fluorine atoms, especially copolymers containing fluorinated aliphatic groups, it is possible to suppress surface quality abnormalities caused by bubbling during the formation of the image recording layer, improve the coating surface, and enhance the ink adhesion of the formed image recording layer.

[0431] Furthermore, the image recording layer containing copolymers with fluorinated aliphatic groups has a higher gray level, for example, it has high sensitivity to laser beams, and can obtain lithographic printing plates with good gray fog properties caused by scattered light, reflected light, etc. and excellent printing durability.

[0432] As the copolymer containing fluorinated aliphatic groups, the copolymer described in International Publication No. 2020 / 262692 is preferred.

[0433] In the image recording layer used in this invention, one adhesive polymer may be used alone, or two or more may be used together.

[0434] The adhesive polymer can be included in the image recording layer in any amount, but the content of the adhesive polymer is preferably 1% to 90% by mass, more preferably 5% to 80% by mass, relative to the total mass of the image recording layer.

[0435] [Chain transfer agent]

[0436] The image recording layer used in this invention may contain a chain transfer agent. Chain transfer agents help improve print durability in lithographic printing plates.

[0437] As a chain transfer agent, thiols are preferred, and from the viewpoint of boiling point (low volatility), thiols with 7 or more carbon atoms are more preferred, and compounds having a thiol group on the aromatic ring (aromatic thiols) are even more preferred. The aforementioned thiols are preferably monofunctional thiols.

[0438] As a specific example of a chain transfer agent, the chain transfer agent described in International Publication No. 2020 / 262692 is preferably cited.

[0439] Chain transfer agents can be added in one form or in combination with two or more.

[0440] The content of the chain transfer agent relative to the total mass of the image recording layer is preferably 0.01% to 50% by mass, more preferably 0.05% to 40% by mass, and even more preferably 0.1% to 30% by mass.

[0441] [Sensitizer]

[0442] The image recording layer preferably also contains a sensitizer to improve the ink's ink adhesion.

[0443] The SP value of the sensitizer is preferably less than 18.0, more preferably less than 14 to 18, even more preferably 15 to 17, and especially preferably 16 to 16.9.

[0444] Furthermore, the sensitizer can be a compound with a molecular weight (weight-average molecular weight when having a molecular weight distribution) of 2,000 or more, or a compound with a molecular weight of less than 2,000.

[0445] The SP value (solubility parameter, unit: (MPa)) in this invention 1 / 2 Use Hansen solubility parameters.

[0446] Regarding the Hansen solubility parameters, the solubility parameters imported by Hildebrand are divided into three components: dispersion term δd, polarity term δp, and hydrogen bonding term δh, and are shown in three-dimensional space. However, in this invention, δ (unit: (MPa)) is used instead. 1 / 2 ) represents the SP value, and is calculated using the following formula.

[0447] δ(MPa) 1 / 2 =(δd 2 +δp 2 +δh 2 ) 1 / 2

[0448] In addition, Hansen or his research successors derived a large number of dispersion terms δd, polarity terms δp, and hydrogen bonding terms δh, which are detailed in the Polymer Handbook (fourth edition), VII-698-711.

[0449] Furthermore, in this invention, the SP value of the polymer is calculated based on the polymer's molecular structure using the Hoy method described in the fourth edition of the Polymer Handbook.

[0450] Examples of such sensitizers include, for example, onium salt compounds, nitrogen-containing low molecular weight compounds, ammonium compounds such as ammonium-containing polymers.

[0451] In particular, when the outermost layer contains inorganic layered compounds, these compounds act as surface covering agents for the inorganic layered compounds, suppressing the decrease in ink adhesion during printing due to the inorganic layered compounds.

[0452] Furthermore, from the viewpoint of ink adhesion, the sensitizer is preferably an onium salt compound.

[0453] Examples of onium salt compounds include phosphonium compounds, ammonium compounds, and sulfonium compounds. From the above perspective, at least one of phosphonium compounds and ammonium compounds is preferred as an onium salt compound.

[0454] Furthermore, the onium salt compounds in the developer accelerators or electron-accepting polymerization initiators described later are compounds with an SP value greater than 18 and are not included in the sensitizers.

[0455] Examples of phosphonium compounds include those described in Japanese Patent Application Publication Nos. 2006-297907 and 2007-50660. Specific examples include 1,4-bis(triphenylphosphine)butane = di(hexafluorophosphate), 1,7-bis(triphenylphosphine)heptane = sulfate, and 1,9-bis(triphenylphosphine)nonane = naphthalene-2,7-disulfonate.

[0456] Examples of ammonium compounds include nitrogen-containing low-molecular-weight compounds and ammonium-containing polymers.

[0457] Examples of nitrogen-containing low-molecular-weight compounds include amine salts and quaternary ammonium salts. Additionally, examples include imidazoline ium salts, benzimidazolinium salts, pyridinium salts, and quinolinium salts.

[0458] Among them, quaternary ammonium salts and pyridinium salts are preferred.

[0459] Specific examples include tetramethylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate, dodecyltrimethylammonium p-toluenesulfonate, benzyltriethylammonium hexafluorophosphate, benzyldimethyloctylammonium hexafluorophosphate, benzyldimethyldodecylammonium hexafluorophosphate, compounds described in paragraphs 0021 to 0037 of Japanese Patent Application Publication No. 2008-284858, and compounds described in paragraphs 0030 to 0057 of Japanese Patent Application Publication No. 2009-90645.

[0460] As an ammonium-containing polymer, it is acceptable as long as it contains an ammonium group in its structure. Preferred polymers are those containing 5 mol% to 80 mol% of ammonium-containing (meth)acrylates as copolymerizing components in their side chains. As a specific example, the polymer described in paragraphs 0089 to 0105 of Japanese Patent Application Publication No. 2009-208458 can be cited.

[0461] Regarding ammonium-containing polymers, the specific viscosity (unit: ml / g) determined by the 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 specific viscosity is converted to 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.

[0462] The following are specific examples of ammonium-containing polymers.

[0463] (1) 2-(trimethylammonium) ethyl methacrylate = p-toluenesulfonate / 3,6-dioxamethacrylate heptyl copolymer (molar ratio 10 / 90, Mw 45,000)

[0464] (2) Ethyl 2-(trimethylammonium)methacrylate = hexafluorophosphate / 3,6-dioxamethacrylate heptyl copolymer (molar ratio 20 / 80, Mw 60,000)

[0465] (3) 2-(Ethyl dimethylammonium) ethyl methacrylate = p-toluenesulfonate / hexyl methacrylate copolymer (molar ratio 30 / 70, Mw 45,000)

[0466] (4) 2-(trimethylammonium) ethyl methacrylate = hexafluorophosphate / 2-ethylhexyl methacrylate copolymer (molar ratio 20 / 80, Mw 60,000)

[0467] (5) 2-(trimethylammonium) ethyl methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40 / 60, Mw 70,000)

[0468] (6) 2-(Butyldimethylammonium)ethyl methacrylate = hexafluorophosphate / 3,6-dioxamethacrylate heptyl copolymer (molar ratio 25 / 75, Mw 65,000)

[0469] (7) Ethyl 2-(Butyldimethylammonium)acrylate = Hexafluorophosphate / Heptyl 3,6-dioxamethacrylate copolymer (molar ratio 20 / 80, Mw 65,000)

[0470] (8) 2-(Butyldimethylammonium)ethyl methacrylate = 13-ethyl-5,8,11-trioxa-1-heptadecanesulfonate / 3,6-dioxamethacrylate heptyl copolymer (molar ratio 20 / 80, Mw 75,000)

[0471] The sensitizer content is preferably 1% to 40.0% by mass relative to the total mass of the image recording layer, more preferably 2% to 25.0% by mass, and even more preferably 3% to 20.0% by mass.

[0472] The image recording layer may contain only one sensitizer or two or more sensitizers in combination.

[0473] One preferred method for the image recording layer used in this invention is to contain two or more compounds as sensitizers.

[0474] Specifically, in the image recording layer used in this invention, from the viewpoint of balancing on-machine developability and ink adhesion, phosphonium compounds, nitrogen-containing low molecular weight compounds and ammonium-containing polymers are preferably used as sensitizers, and more preferably phosphonium compounds, quaternary ammonium salts and ammonium-containing polymers are used in combination.

[0475] [Development Accelerator]

[0476] The image recording layer used in this invention preferably further comprises a development promoter.

[0477] Regarding the developer, the polarity value of the SP value is preferably 6.0 to 26.0, more preferably 6.2 to 24.0, even more preferably 6.3 to 23.5, and particularly preferably 6.4 to 22.0.

[0478] SP value (solubility parameter, unit: (cal / cm³)) in this invention 3 ) 1 / 2 The value of the polarity term is the value of the polarity term 6p in the Hansen solubility parameter. Regarding the Hansen solubility parameter, the solubility parameter imported by Hildebrand is divided into three components: dispersion term δd, polarity term δp, and hydrogen bonding term δh, and is shown in three-dimensional space. However, the polarity term δp mentioned above is used in this invention.

[0479] δp[cal / cm 3 [V is the Hansen solubility parameter dipole term, V[cal / cm]] 3 [] represents the molar volume, and μ[D] represents the dipole moment. δp is typically represented by the following simplified form from Hansen and Beerbower.

[0480] [Formula 1]

[0481]

[0482] As a developer promoter, a hydrophilic polymer or a hydrophilic low molecular weight compound is preferred.

[0483] In this invention, hydrophilicity refers to a polar value of SP ranging from 6.0 to 26.0. Hydrophilic macromolecules are compounds with a molecular weight (weight-average molecular weight in the case of molecular weight distribution) of 3,000 or more, and hydrophilic low molecular weight compounds are compounds with a molecular weight (weight-average molecular weight in the case of molecular weight distribution) of less than 3,000.

[0484] Examples of hydrophilic polymers include cellulose compounds, with cellulose compounds being the preferred choice.

[0485] As a cellulose compound, examples include compounds in which cellulose or at least a portion of cellulose is modified (modified cellulose compounds), with modified cellulose compounds being preferred.

[0486] As a modified cellulose compound, preferably is a compound obtained by replacing at least a portion of the hydroxyl groups of cellulose with at least one group selected from alkyl and hydroxyalkyl groups.

[0487] The degree of substitution of compounds obtained by replacing at least a portion of the hydroxyl groups of the cellulose with at least one group selected from alkyl and hydroxyalkyl groups is preferably 0.J to 6.0, more preferably 1 to 4.

[0488] As the modified cellulose compound, alkyl cellulose compounds or hydroxyalkyl cellulose compounds are preferred, and hydroxyalkyl cellulose compounds are more preferred.

[0489] Methylcellulose is a preferred example of an alkylcellulose compound.

[0490] Hydroxypropyl cellulose is a preferred example of a hydroxyalkyl cellulose compound.

[0491] The molecular weight (weight-average molecular weight in the case of a molecular weight distribution) of the hydrophilic polymer is preferably 3,000 to 5,000,000, more preferably 5,000 to 200,000.

[0492] Examples of hydrophilic low-molecular-weight compounds include diols, polyols, organic amines, organic sulfonic acids, organic aminosulfonyl compounds, organic sulfuric acid compounds, organic phosphonic acid compounds, organic carboxylic acid compounds, and betaine compounds, with polyols, organic sulfonic acids, or betaine compounds being preferred.

[0493] Examples of diol compounds include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and other diols, as well as their ether or ester derivatives.

[0494] Examples of polyol compounds include glycerol, pentaerythritol, and tris(2-hydroxyethyl) isocyanurate.

[0495] Examples of organic amine compounds include triethanolamine, diethanolamine, monoethanolamine, and their salts.

[0496] Examples of organic sulfonic acid compounds include alkyl sulfonic acids, toluene sulfonic acids, benzene sulfonic acids, and their salts, with alkyl sulfonic acids having 1 to 10 carbon atoms being preferred.

[0497] Examples of organic aminosulfonyl compounds include alkyl aminosulfonic acids and their salts.

[0498] Examples of organic sulfuric acid compounds include alkyl sulfuric acid, alkyl ether sulfuric acid, and their salts.

[0499] Examples of organophosphonic acid compounds include phenylphosphonic acid and its salts.

[0500] Examples of organic carboxylic acid compounds include tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, and their salts.

[0501] Examples of betaine compounds include phosphate betaine compounds, sulfobetaine compounds, and carboxybetaine compounds, with trimethylglycine being a preferred example.

[0502] The molecular weight (weight-average molecular weight in the case of a molecular weight distribution) of the hydrophilic low molecular weight compound is preferably 100 or more and less than 3,000, more preferably 300 to 2,500.

[0503] The developer is preferably a compound with a cyclic structure.

[0504] There are no particular limitations on the cyclic structure, but examples of cyclic structures in which at least a portion of the hydroxyl group can be substituted include glucose rings, isocyanuride rings, aromatic rings that may have heteroatoms, and aliphatic rings that may have heteroatoms. Glucose rings or isocyanuride rings are preferred examples.

[0505] The aforementioned cellulose compounds are examples of compounds containing a glucose ring.

[0506] Examples of compounds containing an isocyanurate ring include the aforementioned tri(2-hydroxyethyl) isocyanurate.

[0507] Examples of compounds containing aromatic rings include toluenesulfonic acid and benzenesulfonic acid.

[0508] Examples of compounds having aliphatic rings include the aforementioned alkyl sulfuric acid compounds in which the alkyl group has a cyclic structure.

[0509] Furthermore, the compounds with the cyclic structure described above preferably have hydroxyl groups.

[0510] As compounds having hydroxyl groups and cyclic structures, the above-mentioned cellulose compound and the above-mentioned tri(2-hydroxyethyl) isocyanurate are preferred examples.

[0511] Furthermore, onium salt compounds are preferred as development promoters.

[0512] Examples of onium salt compounds include ammonium compounds and sulfonium compounds, with ammonium compounds being preferred.

[0513] Examples of onium salt compounds, i.e., developer promoters, include trimethylglycine.

[0514] Furthermore, the onium salt compounds in the aforementioned electron-accepting polymerization initiators are compounds whose SP value polarity term is not 6.0 to 26.0 and are not included in the developer accelerators.

[0515] The image recording layer may contain only one development accelerator or two or more in combination.

[0516] One of the preferred methods for the image recording layer used in this invention is to contain two or more compounds as development promoters.

[0517] Specifically, from the viewpoint of on-machine developability and ink adhesion, the image recording layer used in this invention preferably contains the above-mentioned polyol compound and the above-mentioned betaine compound, the above-mentioned betaine compound and the above-mentioned organic sulfonic acid compound, or the above-mentioned polyol compound and the above-mentioned organic sulfonic acid compound as a developing promoter.

[0518] The content of the developer relative to the total mass of the image recording layer is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less.

[0519] [Other ingredients]

[0520] The image recording layer may contain surfactants, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic layered compounds, etc., as other components. Specifically, please refer to paragraphs 0114 to 0159 of Japanese Patent Application Publication No. 2008-284817.

[0521] [Formation of image recording layer]

[0522] The image recording layer in the lithographic printing plate original involved in this invention can be formed, for example, by dispersing or dissolving the necessary above-mentioned components in a known solvent to prepare a coating liquid as described in paragraphs 0142 to 0143 of Japanese Patent Application Publication No. 2008-195018, applying the coating liquid onto a support by a known method such as bar coating, and then drying it.

[0523] As a solvent, known solvents can be used. Specifically, examples include 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 monoethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy-1-propanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, ethyl lactate, etc. The solvent can be used alone or in combination with two or more solvents. The concentration of solid components in the coating solution is preferably 1% to 50% by mass.

[0524] The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer, 0.3 g / m² is preferred. 2 ~3.0g / m 2 .

[0525] Furthermore, the thickness of the image recording layer is preferably 0.1 μm to 3.0 μm, more preferably 0.3 μm to 2.0 μm.

[0526] In this invention, the layer thickness of each layer in the lithographic printing plate original is confirmed by making a slice cut along a direction perpendicular to the surface of the lithographic printing plate original and observing the cross-section of the slice using a scanning electron microscope (SEM).

[0527] <Support Body>

[0528] The original lithographic printing plate involved in this invention has a support.

[0529] As a support, it can be appropriately selected from known supports for lithographic printing plates.

[0530] As a support, a support having a hydrophilic surface is preferred (hereinafter also referred to as "hydrophilic support").

[0531] As the support in this invention, an aluminum plate that has been roughened by a known method and then anodized is preferred. That is, the support in this invention preferably has an aluminum plate and an anodized aluminum film disposed on the aluminum plate.

[0532] Furthermore, the support preferably has an aluminum plate and an aluminum anodic oxide film disposed on the aluminum plate, the anodic oxide film being located closer to the image recording layer side than the aluminum plate, the anodic oxide film having micropores extending from the surface of the image recording layer side along the depth direction, the average diameter of the micropores at the surface of the anodic oxide film being more than 10 nm and less than 100 nm.

[0533] Preferably, the 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 depth of 10 nm to 1,000 nm. The small-diameter pore portion is connected to the bottom of the large-diameter pore portion and extends from the connection position to a depth of 20 nm to 2,000 nm. 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 connection position is 13 nm or less.

[0534] Figure 1 This is a schematic cross-sectional view of one embodiment of the aluminum support 12a.

[0535] The aluminum support 12a has a laminated structure consisting of an aluminum plate 18 and an anodized aluminum film 20a (hereinafter also simply referred to as "anodized film 20a") stacked sequentially. Furthermore, the anodized film 20a in the aluminum support 12a is located closer to the image recording layer side than the aluminum plate 18. That is, the lithographic printing plate original according to the present invention preferably has at least an anodized film, an image recording layer, and a water-soluble resin layer sequentially on the aluminum plate.

[0536] -Anodized film-

[0537] The preferred embodiment of the anodic oxide film 20a will be described below.

[0538] The anodized film 20a is a film formed on the surface of the aluminum plate 18 by anodizing, and the film has ultrafine micropores 22a that are approximately perpendicular to the film surface and uniformly distributed. The micropores 22a extend 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) along the thickness direction (aluminum plate 18 side).

[0539] 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.

[0540] 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.

[0541] The average diameter of the micropore 22a is as follows: the surface of the anodic oxide film 20a was observed using a field emission scanning electron microscope (FE-SEM) with a magnification of 150,000x in N=4 images. The diameter of 50 micropores existing in the range of 400nm×600nm was measured in the four images obtained and then averaged.

[0542] 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.

[0543] 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.

[0544] In the support, 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 communicates with the bottom of the large-diameter pore portion and extends from the communication position to a certain depth.

[0545] 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.

[0546] 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 26 is connected to the bottom of the large-diameter hole 24 at the position of the hole, and extends further from the connection position to a depth of 20 nm to 2,000 nm. Specifically, for example, the method described in paragraphs 0107 to 0114 of Japanese Patent Application Publication No. 2019-162855 can be used.

[0547] -Manufacturing method of support body-

[0548] As a method for manufacturing the support used in this invention, for example, a manufacturing method that sequentially performs the following steps is preferred.

[0549] • Roughening process: The process of roughening the aluminum plate.

[0550] • Anodizing process: The process of anodizing roughened aluminum plates.

[0551] • Hole enlargement process: This process involves contacting the aluminum plate with anodized film obtained in the anodizing process with an acidic or alkaline aqueous solution to enlarge the diameter of the micropores in the anodized film.

[0552] The steps for each process are described in detail below.

[0553] Roughening Process

[0554] The roughening process is a process of performing a roughening treatment on the surface of an aluminum plate, including an electrochemical roughening treatment. This process is preferably performed before the anodizing process described later; however, if the surface of the aluminum plate already has a preferred surface shape, this process is not necessary. It can be performed using the method described in paragraphs 0086 to 0101 of Japanese Patent Application Publication No. 2019-162855.

[0555] Anodizing Process

[0556] There are no particular restrictions on the steps of the anodizing process, as long as the aforementioned micropores can be obtained, and well-known methods can be cited.

[0557] In the anodizing process, aqueous solutions of sulfuric acid, phosphoric acid, and oxalic acid can be used as electrolytic cells. For example, the concentration of sulfuric acid can range from 100 g / L to 300 g / L.

[0558] The conditions for anodizing can be appropriately set according to the electrolyte used, but examples include a electrolyte temperature of 5°C to 70°C (preferably 10°C to 60°C) and a current density of 0.5 A / dm³. 2 ~60A / dm 2 (preferably 1A / dm) 2 ~60A / dm 2The voltage is 1V to 100V (preferably 5V to 50V), the electrolysis time is 1 second to 100 seconds (preferably 5 seconds to 60 seconds), and the film weight is 0.1g / m³. 2 ~5g / m 2 (Preferred size: 0.2g / m) 2 ~3g / m 2 ).

[0559] Hole Enlargement Treatment

[0560] The pore enlargement process is a process that increases the diameter (pore size) of the micropores existing in the anodic oxide film formed by the above-mentioned anodic oxidation process (pore size enlargement process).

[0561] The hole-enlarging process can be performed by contacting the aluminum plate obtained through the above-described anodizing process with an acidic or alkaline aqueous solution. There are no particular limitations on the contact method; for example, immersion and spraying methods can be used.

[0562] The support may have a back coating on the side opposite to the image recording layer, as needed, containing an organic polymer compound as described in Japanese Patent Application Publication No. 5-45885 or a silicon alkoxy compound as described in Japanese Patent Application Publication No. 6-35174.

[0563] <Undercoat>

[0564] The lithographic printing plate master according to the present invention preferably has a base coating (sometimes also called an intermediate layer) between the image recording layer and the support. The base coating enhances the adhesion between the support and the image recording layer in the exposed areas and facilitates the peeling of the image recording layer from the support in the unexposed areas. Therefore, the base coating helps to improve developability while suppressing a decrease in print durability. Furthermore, in the case of infrared laser exposure, the base coating functions as a heat insulation layer, thereby preventing a decrease in sensitivity due to heat diffusion generated by exposure to the support.

[0565] Examples of compounds used in the primer coating include polymers having adsorbent and hydrophilic groups that can be adsorbed onto the surface of the support. To improve adhesion to the image recording layer, polymers having adsorbent and hydrophilic groups, as well as crosslinking groups, are preferred. The compounds used in the primer coating can be low-molecular-weight compounds or polymers. Two or more compounds may be mixed as needed.

[0566] When the compound used in the primer is a polymer, copolymers of monomers having adsorption groups, monomers having hydrophilic groups, and monomers having crosslinking groups are preferred.

[0567] As adsorbent groups that can be adsorbed onto the surface of the support, phenolic hydroxyl groups, carboxyl groups, -PO3H2, -OPO3H2, -CONHSO2-, -SO2NHSO2-, and -COCH2COCH3 are preferred. As hydrophilic groups, sulfonyl groups or their salts, and carboxyl salts are preferred. As crosslinking groups, acryloyl groups, methacryloyl groups, acrylamide groups, methacrylamide groups, and allyl groups are preferred.

[0568] The polymer may have crosslinking groups introduced by the formation of salts of compounds containing polar substituents of the polymer and substituents having charges opposite to those of the aforementioned polar substituents and olefinic unsaturated bonds, and may be further copolymerized with monomers other than those described above, preferably hydrophilic monomers.

[0569] Specifically, preferred examples include silane coupling agents having olefinic double-bond reactive groups capable of addition polymerization as described in Japanese Patent Application Publication No. 10-282679, and phosphorus compounds having olefinic double-bond reactive groups as described in Japanese Patent Application Publication No. 2-304441. Low-molecular-weight or high-molecular-weight compounds having crosslinking groups (preferably olefinic unsaturated groups), functional groups interacting with the support surface, and hydrophilic groups as described in Japanese Patent Application Publication Nos. 2005-238816, 2005-125749, 2006-239867, and 2006-215263 are also preferred.

[0570] As a more preferred polymer, examples include the polymers described in Japanese Patent Application Publication Nos. 2005-125749 and 2006-188038 that have adsorbent groups, hydrophilic groups and crosslinking groups that can be adsorbed onto the surface of a support.

[0571] The content of olefinic unsaturated groups in the polymer used in the primer coating is preferably 0.1 mmol to 10.0 mmol per 1g of polymer, more preferably 0.2 mmol to 5.5 mmol.

[0572] The weight-average molecular weight (Mw) of the polymer used in the base coating is preferably 5,000 or more, and more preferably 10,000 to 300,000.

[0573] In addition to the compounds used in the base coating, the base coating may also contain chelating agents, secondary or tertiary amines, polymerization inhibitors, amino groups or functional groups with polymerization inhibitory effects, and groups that interact with the surface of the aluminum support (e.g., 1,4-diazabicyclo[2.2.2]octane (DABCO), 2,3,5,6-tetrahydroxy-p-benzoquinone, chloroquinone, sulfophthalic acid, hydroxyethyl ethylenediamine triacetic acid, dihydroxyethyl ethylenediamine diacetic acid, hydroxyethyl iminodiacetic acid, etc.) to prevent contamination over time.

[0574] The primer layer can be applied using known methods. The preferred coating weight (solid content) is 0.1 mg / m³. 2 ~100mg / m 2 More preferably 1 mg / m 2 ~30mg / m 2 .

[0575] <Outermost layer>

[0576] The lithographic printing plate of this invention may have an outermost layer (sometimes also called a "protective layer" or "outer coating") on the side of the image recording layer opposite to the support side.

[0577] Furthermore, the original lithographic printing plate involved in this invention preferably has a support, an image recording layer and an outermost layer in sequence.

[0578] The thickness of the outermost layer is preferably thicker than the thickness of the image recording layer.

[0579] In addition to inhibiting the image formation reaction by blocking oxygen, the outermost layer can also prevent scratches in the image recording layer and prevent ablation during high-intensity laser exposure.

[0580] Regarding this characteristic of the outermost layer, it is described, for example, in U.S. Patent No. 3,458,311 and Japanese Patent Publication No. 55-49729. As the low-oxygen permeability polymer used in the outermost layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected, and two or more types can be mixed as needed. However, from the viewpoint of machine developability, it is preferable to include a water-soluble polymer.

[0581] In this invention, a water-soluble polymer refers to a polymer that dissolves more than 1g in 100g of pure water at 70°C, and does not precipitate even when the solution obtained by dissolving 1g of the polymer in 100g of pure water at 70°C is cooled to 25°C.

[0582] Examples of water-soluble polymers used in the outermost layer include polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose derivatives, polyethylene glycol, and poly(meth)acrylonitrile.

[0583] As a modified polyvinyl alcohol, acid-modified polyvinyl alcohol having carboxyl or sulfonyl groups is preferred. Specifically, the modified polyvinyl alcohols described in Japanese Patent Application Publication Nos. 2005-250216 and 2006-259137 can be cited as examples.

[0584] The water-soluble polymers mentioned above preferably include polyvinyl alcohol, and more preferably include polyvinyl alcohol with a saponification degree of 50% or more.

[0585] The aforementioned degree of saponification is preferably 60% or higher, more preferably 70% or higher, and even more preferably 85% or higher. There is no particular upper limit to the degree of saponification; it can be below 100%.

[0586] The above degree of saponification was determined according to the method described in JIS K 6726:1994.

[0587] Furthermore, as the outermost layer, a preferred method is one that includes polyvinyl alcohol and polyethylene glycol.

[0588] When the outermost layer of the present invention comprises a water-soluble polymer, the content of the water-soluble polymer relative to the total mass of the outermost layer is preferably 1% to 99% by mass, more preferably 3% to 97% by mass, and even more preferably 5% to 95% by mass.

[0589] The outermost layer preferably contains a hydrophobic polymer.

[0590] Hydrophobic polymers are polymers that can dissolve less than 5g or are insoluble in 100g of pure water at 125°C.

[0591] Examples of hydrophobic polymers include, for example, polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, alkyl poly(meth)acrylates (e.g., poly(meth)acrylate, poly(ethyl)acrylate, poly(butyl)acrylate, etc.), and copolymers formed by combining the raw material monomers of these resins.

[0592] Furthermore, as a hydrophobic polymer, polyvinylidene chloride resin is preferred.

[0593] Furthermore, as a hydrophobic polymer, it is preferable to include a styrene-propylene copolymer (also known as styrene-acrylic resin).

[0594] Furthermore, from the viewpoint of machine developability, hydrophobic polymers are preferably hydrophobic polymer particles.

[0595] Hydrophobic polymers can be used alone or in combination of two or more.

[0596] When the outermost layer contains a hydrophobic polymer, the content of the hydrophobic polymer relative to the total mass of the outermost layer is preferably 1% to 70% by mass, more preferably 5% to 50% by mass, and even more preferably 10% to 40% by mass.

[0597] In this invention, the area percentage of the hydrophobic polymer on the outermost surface is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more.

[0598] As an upper limit for the area ratio occupied by hydrophobic polymers on the outermost surface, for example, 90% area can be cited.

[0599] The area fraction of hydrophobic polymers on the outermost surface can be determined in the following manner.

[0600] Using a PHI nano TOFII time-of-flight secondary ion mass spectrometer (TOF-SIMS) manufactured by ULVAC-PHI, INCORPORATED., a Bi ion beam (primary ions) was irradiated onto the outermost surface at an accelerating voltage of 30 kV. The peaks of ions (secondary ions) released from the surface corresponding to the hydrophobic region (i.e., the region based on the hydrophobic polymer) were measured, thereby mapping the hydrophobic region and determining the hydrophobic region per 100 μm. 2 The area occupied is used to calculate the area ratio of the hydrophobic part, which is taken as the "area ratio of the hydrophobic polymer in the outermost surface".

[0601] For example, when the hydrophobic polymer is an acrylic resin, it is obtained by using C6H... 13 O - The peak was measured. Furthermore, in the case where the hydrophobic polymer was polyvinylidene chloride, the peak was determined by C2H2Cl. + The peak was measured.

[0602] The aforementioned area ratio can be adjusted based on factors such as the amount of hydrophobic polymer added.

[0603] From the viewpoint of visual recognition and storage stability, the outermost layer preferably contains an infrared absorber, and more preferably contains a decomposable infrared absorber.

[0604] As infrared absorbers, the infrared absorbers described in the image recording layer are preferred examples.

[0605] The infrared absorber in the outermost layer can be a single ingredient or a combination of two or more ingredients.

[0606] From the viewpoint of visual recognizability over time and preservation stability, the content of infrared absorber in the outermost layer is preferably 0.10% to 50% by mass, more preferably 0.50% to 30% by mass, and even more preferably 1.0% to 20% by mass, relative to the total mass of the outermost layer.

[0607] From the perspective of improving the visual recognition of the exposed area, the outermost layer preferably contains a colorant.

[0608] As a chromogenic agent, the chromogenic precursor described in the image recording layer is preferably cited.

[0609] The colorant in the outermost layer can be used alone or in combination with two or more ingredients.

[0610] From the viewpoint of color development, the content of colorant in the outermost layer is preferably 0.10% to 50% by mass, more preferably 0.50% to 30% by mass, and even more preferably 1.0% to 20% by mass, relative to the total mass of the outermost layer.

[0611] To improve oxygen barrier properties, the outermost layer may contain inorganic layered compounds. Inorganic layered compounds are particles with thin, flat, plate-like shapes, such as natural mica, synthetic mica, talc (represented by the formula 3MgO·4SiO·H2O), monzocarp, montmorillonite, saponite, lithium montmorillonite, zirconium phosphate, etc.

[0612] The preferred inorganic layered compound is a mica compound. Examples of mica compounds include those with the formula: A(B, C). 2-5 D4O 10 (OH, F, O)₂ [where A is any one of K, Na, Ca, B and C are any one of Fe(II), Fe(III), Mn, Al, Mg, V, and D is Si or Al] represents the mica group including natural mica and synthetic mica.

[0613] Within the mica group, natural mica includes muscovite, sodium mica, phlogopite, biotite, and phosphorite. Synthetic mica includes fluorophlogopite (KMg3(AlSi3O4)). 10 F2, potassium tetrasilica KMg 2.5 (Si4O 10 Non-swellable mica such as F2 and Na tetrafluorosilica NaMg 2.5 (Si4O 10 F2, Na or Li with mica (Na, Li)Mg2Li(Si4O) 10 F2, montmorillonite series Na or Li lithium montmorillonite (Na, Li) 1 / 8 Mg 2 / 5 Li 1 / 8 (Si4O 10 F2 and other swelling mica, etc. Furthermore, it is also used in the synthesis of green soil.

[0614] Among the aforementioned mica compounds, fluorine-based swelling mica is particularly useful. That is, swelling synthetic mica has a thickness of... The crystal structure consists of stacked unit lattice layers, with significant metal atom substitution within the lattice compared to other clay minerals. As a result, the lattice layers exhibit a lack of positive charge, prompting the adsorption of Li atoms between the layers to compensate. + Na + Ca 2+ Mg 2+ Oxygen ions. These interlayer oxygen ions are called exchangeable oxygen ions, and they can exchange with various oxygen ions. In particular, the interlayer oxygen ions are Li. + Na + In this state, the ionic radius is small, resulting in weak bonding between the layered lattice layers, leading to significant swelling upon contact with water. If shear force is applied in this state, it easily breaks down, forming a stable sol in water. This tendency is strong in synthetic mica with swelling properties, making it particularly preferred.

[0615] From the perspective of controlling diffusion, the thinner the mica compound, the better; however, the larger the planar dimension, the better, as long as it does not inhibit the smoothness of the coating surface or the transmissibility of activated light. Therefore, the aspect ratio is preferably 20 or more, more preferably 100 or more, and especially preferably 200 or more. The aspect ratio is the ratio of the major axis to the thickness of the particle, and can be measured, for example, from the projection of a particle-based microscopic photograph. The larger the aspect ratio, the greater the effect obtained.

[0616] Regarding the particle size of the mica compound, its average major diameter is preferably 0.3 μm to 20 μm, more preferably 0.5 μm to 10 μm, and particularly preferably 1 μm to 5 μm. The average thickness of the particles is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.01 μm or less. Specifically, for example, in the case of swollen synthetic mica as a representative compound, as a preferred method, the thickness is 1 nm to 50 nm, and the planar dimension (major diameter) is about 1 μm to 20 μm.

[0617] The content of inorganic layered compounds relative to the total mass of the outermost layer is preferably 1% to 60% by mass, more preferably 3% to 50% by mass. Even when multiple inorganic layered compounds are used together, the total amount of inorganic layered compounds is preferably at the above-mentioned content. Within the above range, oxygen barrier properties are improved, and good sensitivity can be obtained. Furthermore, it is possible to prevent a decrease in ink adhesion.

[0618] The outermost layer may contain known additives such as plasticizers for imparting flexibility, surfactants for improving coatability, and inorganic particles for controlling surface slippage. Furthermore, the outermost layer may contain additives described in the image recording layer.

[0619] The outermost layer is coated using a known method. The coating weight (solid content) of the outermost layer is preferably 0.01 g / m². 2~10g / m 2 More preferably 0.02 g / m 2 ~3g / m 2 0.02g / m 2 ~1g / m 2 .

[0620] The thickness of the outermost film in the lithographic printing plate original involved in this invention is preferably 0.1μm to 5.0μm, more preferably 0.3μm to 4.0μm.

[0621] Relative to the film thickness of the aforementioned image recording layer, the film thickness of the outermost layer in the lithographic printing plate original involved in this invention is preferably 1.1 times to 5.0 times, more preferably 1.5 times to 3.0 times.

[0622] The original lithographic printing plate involved in this invention may have other layers besides those described above.

[0623] There are no particular restrictions on the other layers; any known layer can be used. For example, if necessary, a back coating layer can be provided on the side of the support opposite to the image recording layer side.

[0624] (Methods for making offset printing plates and offset printing methods)

[0625] A lithographic printing plate can be produced by exposing an image to the original lithographic printing plate involved in this invention and performing a developing process.

[0626] The method for manufacturing the lithographic printing plate according to the present invention preferably includes the following steps: a step of exposing the on-machine developing type lithographic printing plate master of the present invention into an image (hereinafter also referred to as the "exposure step"); and a step of supplying at least one of printing ink and dampening solution to a printing press to remove the image recording layer of non-image areas (hereinafter also referred to as the "on-machine developing step").

[0627] The offset printing method of the present invention preferably includes the following steps: an exposure step of exposing the on-machine developing type offset printing plate of the present invention into an image shape (exposure step); an on-machine developing step of producing an offset printing plate by supplying at least one of printing ink and dampening solution to remove the image recording layer of the non-image portion in a printing press; and a printing step of using the obtained offset printing plate (printing step).

[0628] Furthermore, the method for manufacturing the lithographic printing plate or the lithographic printing method of the present invention preferably further includes a step (identification step) of using a sensor to determine the exposed lithographic printing plate original.

[0629] The preferred embodiments of each step in the following description are provided regarding the method for manufacturing the lithographic printing plate and the lithographic printing method involved in this invention. Furthermore, the original lithographic printing plate involved in this invention can also be developed using a developing solution.

[0630] The following describes the exposure, on-machine development, and identification processes in the method for making a lithographic printing plate. However, the exposure process in the method for making a lithographic printing plate of this invention is the same as the exposure process in the lithographic printing method of this invention. The on-machine development process in the method for making a lithographic printing plate of this invention is the same as the on-machine development process in the lithographic printing method of this invention. The identification process in the method for making a lithographic printing plate of this invention is the same as the identification process in the lithographic printing method of this invention.

[0631] <Exposure Process>

[0632] The method for manufacturing the lithographic printing plate according to the present invention preferably includes an exposure step of exposing the original lithographic printing plate according to the present invention into an image shape and forming an exposed portion and an unexposed portion. The original lithographic printing plate according to the present invention is preferably exposed to an image shape by laser exposure using a transparent original image having line images, halftone images, etc., or by laser beam scanning based on digital data.

[0633] A light source with a wavelength of 750 nm to 1,400 nm is preferably used. As a light source with a wavelength of 750 nm to 1,400 nm, solid-state lasers and semiconductor lasers that radiate infrared radiation are preferred. Regarding the infrared laser, the output power is preferably 100 mW or higher, the exposure time per pixel is preferably less than 20 microseconds, and the irradiation energy is preferably 10 mJ / cm². 2 ~300mJ / cm 2 Furthermore, to shorten the exposure time, a multi-beam laser device is preferred. The exposure mechanism can be any of the following: internal drum type, external drum type, or flat plate type.

[0634] Regarding image exposure, it can be performed using conventional methods such as plate-making machines. In the case of in-press development, image exposure can be performed on the printing press after the original lithographic printing plate is mounted on the press.

[0635] Furthermore, various parameters such as SD (depth of focus), Slope (linear slope of the laser), and Curve (arrangement curvature of the laser) can be set separately during exposure. In setting these parameters, development can be performed using the ink and dampening solution described later, or image-like exposure can be performed, or development can be performed using liquids other than ink and dampening solution.

[0636] As for the liquid other than the ink and dampening solution mentioned above, any liquid that can be developed on the machine is acceptable, but water-based liquids are preferred. Examples include water-based developer, water-based finisher liquid, and water-based finisher gum liquid.

[0637] Furthermore, when developing with a liquid other than ink and dampening solution, the plate can be cleaned with water or the like after development. In order to further improve the visual recognition of the image area, an acidic aqueous solution can also be brought into contact with the plate.

[0638] There are no particular limitations on the acids contained in the acidic aqueous solution, but carboxylic acids such as acetic acid, hydroxycarboxylic acids such as citric acid, and their salts are preferred.

[0639] Furthermore, there are no particular limitations on the aforementioned methods of development, cleaning, and contact with acidic aqueous solutions, and these methods can be carried out using known methods. For example, methods such as applying the solution to the printing plate using a sponge or cloth are preferred.

[0640] <On-machine developing process>

[0641] The method for manufacturing the lithographic printing plate according to the present invention preferably includes an on-machine developing step of supplying at least one of printing ink and dampening solution to remove the image recording layer of the non-image area on a printing press.

[0642] The following is an explanation of the on-machine development method.

[0643] [In-machine development method]

[0644] In the on-machine development method, the original lithographic printing plate exposed by the image is preferably made by supplying oil-based ink and water-based components on the printing press and removing the image recording layer of the non-image area to create the lithographic printing plate.

[0645] That is, if the lithographic printing plate is directly mounted on the printing press after image exposure without any development treatment, or if the lithographic printing plate is mounted on the printing press and then image exposure is performed on the printing press, followed by the supply of oil-based ink and water-based components for printing, then in the initial stage of printing, in the non-image section, the uncured image recording layer, due to the supply of either or both of the oil-based ink and water-based components, is dissolved or dispersed and removed, thereby exposing the hydrophilic surface to that portion. On the other hand, in the exposure section, the image recording layer cured by exposure forms an oil-based ink receiving portion with an oleophilic surface. Initially, either oil-based ink or water-based components can be supplied to the plate, but from the perspective of preventing contamination of the image recording layer due to the removal of water-based components, it is preferable to initially supply oil-based ink. In this way, the lithographic printing plate is developed on the printing press and directly used in multi-sheet printing. As for oil-based inks and water-based components, conventional offset printing inks and dampening solutions are preferred.

[0646] <Identification Process>

[0647] The method for manufacturing a lithographic printing plate according to the present invention preferably further includes a step (identification step) of using a sensor to determine the exposed lithographic printing plate original.

[0648] As a sensor, a mechanism is preferred for detecting light with a wavelength range of at least 580 nm and below 750 nm, and a mechanism is more preferably for reading barcodes in an exposed lithographic printing plate original with a wavelength range of at least 580 nm and below 750 nm.

[0649] Furthermore, there are no particular restrictions on the aforementioned sensors, but known sensors can be used. Among them, a known barcode reader is preferred.

[0650] Furthermore, in the above-mentioned exposure process, it is preferable to expose at least a portion of the original offset printing plate into a barcode shape.

[0651] Furthermore, the method for manufacturing the lithographic printing plate or the lithographic printing method involved in this invention preferably further includes a process of bending the exposed lithographic printing plate original (bending process).

[0652] In the above bending process, a known bending device can be used.

[0653] Moreover, the aforementioned identification process is preferably performed before or after the bending process, or during the bending process.

[0654] <Printing Process>

[0655] The lithographic printing method involved in this invention includes a printing process of supplying printing ink to a lithographic printing plate and printing a recording medium.

[0656] There are no particular restrictions on the type of printing ink, and various known inks can be used as needed. Furthermore, oil-based inks or ultraviolet-curing inks (UV inks) are preferred as printing inks.

[0657] Furthermore, dampening solution can be supplied as needed during the aforementioned printing process.

[0658] Furthermore, the aforementioned printing process can be carried out immediately after the aforementioned on-machine developing process without stopping the printing press.

[0659] As a recording medium, there are no particular restrictions, and any known recording medium can be used as needed.

[0660] In the method for manufacturing a lithographic printing plate derived from the lithographic printing plate master of the present invention and the lithographic printing method of the present invention, the entire surface of the lithographic printing plate master can be heated as needed before exposure, during exposure, and during the exposure-to-development period. This heating promotes the image formation reaction in the image recording layer, resulting in advantages such as improved sensitivity and print durability, and stabilized sensitivity. Regarding heating before development, it is preferable to perform the heating under mild conditions below 150°C. This prevents problems such as curing of non-image areas. For heating after development, it is preferable to use very strong conditions, preferably within the range of 100°C to 500°C. Within this range, sufficient image enhancement can be obtained, and problems such as deterioration of the support and pyrolysis of the image area can be suppressed.

[0661] Example

[0662] The present invention will now be described in detail through examples, but the invention is not limited thereto. In these examples, unless otherwise specified, "%" and "parts" refer to "mass %" and "parts by mass," respectively. Furthermore, in polymer compounds, except for specifically defined polymer compounds, the molecular weight is the weight-average molecular weight (Mw), and the ratio of repeating structural units is the molar percentage. The weight-average molecular weight (Mw) is a value determined as a polystyrene conversion value based on gel permeation chromatography (GPC).

[0663] (Examples 1 to 15 and Comparative Examples 1 to 16)

[0664] <Fabrication of the Support Body>

[0665] Surface Treatment A

[0666] (Aa) Mechanical roughening treatment (brush texture method)

[0667] While using, such Figure 5 The apparatus shown contains a pumice suspension (specific gravity 1.1 g / cm³). 3 The material is supplied as a polishing slurry to the surface of the aluminum plate, where it undergoes mechanical roughening by a rotating stiff-bristled brush. Figure 5 In the diagram, 1 is an aluminum plate, 2 and 4 are roller brushes (in this embodiment, they are stiff bristle brushes), 3 is grinding slurry, and 5, 6, 7 and 8 are support rollers.

[0668] In the mechanical roughening process, the median particle size (μm) of the abrasive material was set to 30μm, the number of brushes was set to 4, and the brush rotation speed (rpm) was set to 250rpm. The stiff bristle brush was made of 6.10 nylon, with bristle diameter of 0.3mm and bristle length of 50mm. The brush was constructed by drilling holes and densely packing bristles into a φ300mm stainless steel sleeve. The distance between the two support rollers (φ200mm) at the bottom of the stiff bristle brush was 300mm. The load on the drive motor that pressed the stiff bristle brush until it rotated was increased by 10kW compared to the load before pressing the brush against the aluminum plate. The rotation direction of the brush was the same as the movement direction of the aluminum plate.

[0669] (Ab) Alkali etching treatment

[0670] The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda (26% by mass) and aluminum ion concentration (6.5% by mass) through a nozzle at a temperature of 70°C. Then, a water wash was performed using the sprayer. The aluminum dissolution rate was 10 g / m³. 2 .

[0671] (Ac) Decontamination treatment in acidic aqueous solution

[0672] Next, a decontamination treatment was performed in a nitric acid aqueous solution. The nitric acid aqueous solution used for the decontamination treatment was waste liquid of nitric acid used in the electrochemical roughening process in the next step. The liquid temperature was 35°C. The decontamination treatment was performed for 3 seconds by spraying the decontamination solution with a sprayer.

[0673] (Ad) Electrochemical roughening treatment

[0674] Electrochemical roughening treatment was performed continuously using nitric acid electrolysis at an AC voltage of 60 Hz. The electrolyte used was an aqueous solution of 10.4 g / L nitric acid at 35°C, with aluminum nitrate added to adjust the aluminum ion concentration to 4.5 g / L. The AC power supply waveform was as follows. Figure 3 The waveform shown, using a trapezoidal rectangular alternating current with a current value reaching its peak value in 0.8 msec (tp), a duty cycle of 1:1, and a carbon electrode as the counter electrode, underwent electrochemical roughening treatment. Ferrite was used as the auxiliary anode. Regarding the electrolytic cell, [the following is a description of the process:] ... Figure 4The electrolytic cell shown. The current density, expressed as peak current, is 30 A / dm³. 2 This causes 5% of the current flowing from the power source to be diverted to the auxiliary anode. (Electricity (C / dm³)) 2 The total charge during the reaction with the aluminum plate as the cathode is 185 C / dm. 2 Then, a spray-based water wash was performed.

[0675] (Ae) alkaline etching treatment

[0676] The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda (5% by mass) and aluminum ions (0.5% by mass) through a nozzle at 50°C. Then, a water wash was performed using the sprayer. The aluminum dissolution rate was 0.5 g / m³. 2 .

[0677] (Af) Decontamination treatment in acidic aqueous solution

[0678] Next, a decontamination treatment was performed in a sulfuric acid aqueous solution. The sulfuric acid aqueous solution used for the decontamination treatment had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The solution temperature was 30°C. The decontamination treatment was performed for 3 seconds by spraying the decontamination solution using a sprayer.

[0679] (Ag) Electrochemical roughening treatment

[0680] Electrochemical roughening treatment was performed continuously using hydrochloric acid electrolysis at an AC voltage of 60 Hz. The electrolyte was an aqueous solution of 6.2 g / L hydrochloric acid at 35°C, with aluminum chloride added to adjust the aluminum ion concentration to 4.5 g / L. The AC power supply waveform was as follows: Figure 3 The waveform shown, using a trapezoidal rectangular alternating current with a current value reaching its peak value in 0.8 msec (tp), a duty cycle of 1:1, and a carbon electrode as the counter electrode, underwent electrochemical roughening treatment. Ferrite was used as the auxiliary anode. Regarding the electrolytic cell, [the following is a description of the process:] ... Figure 4 The electrolytic cell shown.

[0681] The current density, measured in peak current, is 25 A / dm. 2 The amount of electricity generated during hydrochloric acid electrolysis (C / dm³) 2 The total charge during the reaction with the aluminum plate as the cathode is 63 C / dm. 2 Then, a spray-based water wash was performed.

[0682] (Ah) Alkali etching treatment

[0683] The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda (5% by mass) and aluminum ions (0.5% by mass) through a nozzle at 50°C. Then, a water wash was performed using the sprayer. The aluminum dissolution rate was 0.1 g / m³. 2 .

[0684] (Ai) Decontamination treatment in acidic aqueous solution

[0685] Next, a decontamination treatment was performed in an aqueous sulfuric acid solution. Specifically, the waste liquid generated during the anodizing process (containing 5 g / L of dissolved aluminum ions in a 170 g / L aqueous sulfuric acid solution) was used for a 4-second decontamination treatment at a liquid temperature of 35°C. A 3-second decontamination treatment was then performed by spraying the decontamination solution using a sprayer.

[0686] (Aj) Stage 1 Anodizing Treatment

[0687] Using based Figure 6 The DC electrolytic anodizing apparatus shown in the diagram performed the first stage of anodizing. Anodizing was carried out under the conditions shown in Table 1, and an anodized film of a specified thickness was formed. Furthermore, in the anodizing apparatus 610, the aluminum plate 616, as... Figure 6 The aluminum plate 616 is conveyed as indicated by the middle arrow. In the power supply tank 612 containing electrolyte 618, the aluminum plate 616 is charged (+) by the power supply electrode 620. Furthermore, the aluminum plate 616 is conveyed upwards in the power supply tank 612 by roller 622, then downwards by clamping roller 624, and finally conveyed to the electrolytic treatment tank 614 containing electrolyte 626, and then horizontally by roller 628. Next, the aluminum plate 616 is charged (-) by the electrolytic electrode 630, thereby forming an anodized film on its surface. The aluminum plate 616, leaving the electrolytic treatment tank 614, is conveyed to the subsequent process. In the anodizing apparatus 610, a direction-changing mechanism is formed by rollers 622, 624, and 628. In the inter-tank section between the power supply tank 612 and the electrolytic treatment tank 614, the aluminum plate 616 is conveyed in a mountain-shaped and inverted U-shaped configuration via the rollers 622, 624, and 628. The power supply electrode 620 and the electrolytic electrode 630 are connected to a DC power supply 634.

[0688] (Ak) Hole Enlargement Treatment

[0689] Under the conditions shown in Table 1, the aluminum plate that had undergone the above anodizing treatment was immersed in an aqueous solution of caustic soda at a temperature of 35°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. Then, a spray-based water washing was performed.

[0690] (Al) Stage 2 Anodizing Treatment

[0691] Using based Figure 6 The DC electrolytic anodizing apparatus with the structure shown underwent the second stage of anodizing. Anodizing was performed under the conditions shown in Table 1, resulting in an anodized film of a specified thickness.

[0692] (Am) Stage 3 Anodizing Treatment

[0693] Using based Figure 6 The DC electrolytic anodizing apparatus with the structure shown underwent the third stage of anodizing. Anodizing was performed under the conditions shown in Table 1, resulting in an anodized film of a specified thickness.

[0694] The support body A described in Tables 1 and 2 was obtained by the above surface treatment A.

[0695] The average diameter (nm) of the large-diameter pores at the surface of the anodic oxide film after the second anodizing process, the average diameter (nm) of the small-diameter pores at the connecting positions, the depth (nm) of the large-diameter and small-diameter pores, and the indentation density (micropore density, unit: pores / μm) are calculated. 2 The thickness (nm) of the anodized film from the bottom of the small diameter hole to the surface of the aluminum plate is summarized in Table 2.

[0696] Furthermore, the average diameter of the micropores (average diameter of the large-diameter and small-diameter pore portions) is as follows: N=4 images of the large-diameter and small-diameter pore surfaces were observed using FE-SEM at 150,000x magnification. The diameters of the micropores (large-diameter and small-diameter pore portions) existing in the 400nm×600nm range were measured in the four images, and the average value was obtained. Additionally, in cases where the large-diameter pores are deep and it is difficult to measure the diameter of the small-diameter pores, and in cases where the diameter of enlarged pores within the small-diameter pores is measured, the upper part of the anodic oxide film is cut, and then various diameters are determined.

[0697] The depth of the micropores (the depth of the large-diameter pores and the small-diameter pores) is as follows: the cross-section of the support (anodic oxide film) is observed using FE-SEM (large-diameter pore depth observation: 150,000x, small-diameter pore depth observation: 50,000x), and the depth of any 25 micropores in the obtained image is measured and averaged.

[0698] In addition, in Table 1, the film amount (AD) in the first and second anodizing treatment columns indicates the film amount obtained in each treatment. Furthermore, the electrolyte used is an aqueous solution containing the components listed in Table 1.

[0699] [Table 1]

[0700]

[0701] [Table 2]

[0702]

[0703] Using support A, a base layer, an image recording layer, and a protective layer as needed are formed according to any one of the formulations 1 to 3 recorded in Table 3.

[0704] Prescriptions 1 through 3 are shown below.

[0705] ~Prescription 1~

[0706] <Formation of the base coating>

[0707] The obtained support A was coated with a dry coating at a rate of 0.1 g / m². 2 The primer coating liquid with the following composition is applied in a manner that forms a primer coating layer.

[0708] - Primer coating liquid -

[0709] • Compound for primer coating (U-1 below, 11% aqueous solution): 0.10502 parts

[0710] • Sodium gluconate: 0.0700 parts

[0711] Surfactant (EMALEX (registered trademark) 710, manufactured by NIHON EMULSION Co., Ltd.): 0.00159 parts

[0712] • Preservative (Biohope L, K·I Chemical Industry Co., LTD.): 0.00149 parts

[0713] Water: 2,8719 portions

[0714] [Chemical Formula 13]

[0715]

[0716] <Formation of Image Recording Layer>

[0717] One rod of the following image recording layer coating solution was applied to the primer layer and dried at 50°C for 60 seconds to form a dry coating weight of 0.9 g / m². 2 The image recording layer was used to create the original lithographic printing plate.

[0718] -Image recording layer coating solution 1-

[0719] Polymer dispersion: 0.675 parts

[0720] Hydroxypropyl methylcellulose: 0.400 parts

[0721] Monomer 1: 0.036 parts

[0722] Monomer 2: 0.115 parts

[0723] Monomer 3: 0.087 parts

[0724] Infrared absorber 1:0.028 parts

[0725] Surfactant 1: 0.045 parts

[0726] Iodized salt 1:0.073 parts

[0727] Iodized salt 2:0.053 parts

[0728] Chromoplast precursor 1: Add the compounds and amounts listed in Table 3.

[0729] Chromoplast precursor 2: Add the compounds and amounts listed in Table 3.

[0730] Phenothiazine: 0.005 parts

[0731] 1-Propanol: 2.6 parts

[0732] 2-Butanone: 3.5 parts

[0733] 1-Methoxy-2-propanol: 0.92 parts

[0734] δ-Butyrolactone: 0.10 parts

[0735] Water: 1.16 parts

[0736] Polymer dispersion: The polymer dispersion was prepared according to Example 10 of European Patent Application Publication No. 1,765,593 and was used as a 23.5% by mass dispersion of n-propanol / water in a mass ratio of 80:20.

[0737] Hydroxypropyl methylcellulose: 5% aqueous solution. 30% is methoxylated and 10% is hydroxypropoxylated. The viscosity of a 2% by mass aqueous solution at 20°C is 5 mPa·s.

[0738] Monomer 1: The following compounds

[0739] [Chemical Formula 14]

[0740]

[0741] Monomer 2: The following compounds

[0742] [Chemical Formula 15]

[0743]

[0744] Monomer 3: The following compounds

[0745] [Chemical Formula 16]

[0746]

[0747] Infrared absorber 1: The following compounds

[0748] [Chemical Formula 17]

[0749]

[0750] Surfactant 1: BYK302 manufactured by Byk Chemie was used as a 25% by mass solution of 1-methoxy-2-propanol.

[0751] Iodonium salt 1: The following compounds

[0752] [Chemical Formula 18]

[0753]

[0754] Iodonium salt 2: The following compounds

[0755] [Chemical Formula 19]

[0756]

[0757] Phenothiazine: the following compounds

[0758] [Chemical Formula 20]

[0759]

[0760] ~Prescription 2~

[0761] <Formation of the base coating>

[0762] The obtained support A was coated with a dry coating at a rate of 0.1 g / m². 2 The above-mentioned primer coating liquid is applied in a manner that forms the primer coating.

[0763] <Formation of Image Recording Layer>

[0764] The following image recording layer coating solution was applied to the primer layer using two rods and dried at 120°C for 40 seconds to form a dry coating with a coating weight of 1.0 g / m². 2 The image recording layer was used to create the original lithographic printing plate.

[0765] -Image recording layer coating solution 2-

[0766] Infrared absorber (IR-2): 0.0400 parts

[0767] Chromoplast precursor 1: Add the compounds and amounts listed in Table 3.

[0768] Chromoplast precursor 2: Add the compounds and amounts listed in Table 3.

[0769] Electron-accepting polymerization initiator (Int-1): 0.1090 parts

[0770] Electron-donating polymerization initiator (TPB): 0.0250 parts

[0771] Polymerizable compound (M-4 below): 0.4714 parts

[0772] Anionic surfactant (A-1): 0.0400 parts

[0773] Fluorinated surfactant (W-1): 0.0042 parts

[0774] 2-Butanone: 4.3551 parts

[0775] 1-Methoxy-2-propanol: 3.9260 parts

[0776] Methanol: 2.6947 parts

[0777] Polymer particle R: 2.3256 parts

[0778] IR-2: The following compounds

[0779] [Chemical Formula 21]

[0780] IR-2

[0781]

[0782] Int-1: For the following compounds, the HOMO level is -6.70 eV and the LUMO level is -3.08 eV.

[0783] [Chemical Formula 22]

[0784]

[0785] TPB: The following compounds

[0786] [Chemical Formula 23]

[0787]

[0788] A-1: The following compounds

[0789] [Chemical Formula 24]

[0790] A-1

[0791]

[0792] W-1: The following compounds

[0793] [Chemical Formula 25]

[0794] W-1

[0795]

[0796] <Synthetic methods of polymeric compound (M-4)>

[0797] A mixed solution of Takenate D-160N (polyisocyanate-trimethylolpropane adduct, manufactured by Mitsui Chemicals, Inc., 4.7 parts), ARONIX M-403 (manufactured by TOAGOSEI CO., LTI, with the NCO value of Takenate D-160N and the hydroxyl value of ARONIX M-403 in a 1:1 ratio), tert-butylbenzoquinone (0.02 parts), and methyl ethyl ketone (11.5 parts) was heated to 65°C. NEOSTANN U-600 (bismuth-based polycondensation catalyst, manufactured by NITTO KASEICO., LTD., 0.11 parts) was added to the reaction solution, and the mixture was heated at 65°C for 4 hours. The reaction solution was cooled to room temperature (25°C), and methyl ethyl ketone was added, thereby synthesizing a 50% by weight solution of urethane acrylate (M-4).

[0798] <Production of Polymer Particles R>

[0799] -Preparation of oil phase components-

[0800] The oil phase composition was obtained by mixing WANNATE (registered trademark) PM-200 (a polyfunctional isocyanate compound manufactured by Wanhua Chemical Co., Ltd.): 6.66 g; Takenate (registered trademark) D-116N (a 50% by mass ethyl acetate solution of the adduct of trimethylolpropane (TMP), m-phenylenedimethyl diisocyanate (XDI) and polyethylene glycol monomethyl ether (E090) (the structure below): manufactured by Mitsui Chemicals, Inc.): 5.46 g; SR399 (dipentaerythritol pentaacrylate: manufactured by Sartomer Company, Inc.): 11.24 g; ethyl acetate: 14.47 g; and PIONIN (registered trademark) A-41-C (manufactured by Takemoto Oil & Fat Co., Ltd.): 0.45 g, and stirring at room temperature (25°C) for 15 minutes.

[0801] [Chemical Formula 26]

[0802]

[0803] -Preparation of Aqueous Phase Components-

[0804] 47.2g of distilled water was prepared as the aqueous phase component.

[0805] -Microcapsule formation process-

[0806] An emulsion was obtained by adding an aqueous component to the oil phase and mixing the mixture, then emulsifying the resulting mixture at 12,000 rpm for 16 minutes using a homogenizer.

[0807] 16.8 g of distilled water was added to the obtained emulsion, and the resulting liquid was stirred at room temperature for 180 minutes.

[0808] Next, the stirred liquid was heated to 45°C and stirred for 5 hours while maintaining the temperature at 45°C, thereby removing ethyl acetate by distillation. The concentration of the solid component was adjusted to 20% by mass with distilled water, thus obtaining an aqueous dispersion of polymer particles R. The volume average particle size of R was measured using a laser diffraction / scattering particle size distribution measuring device LA-920 (manufactured by HORIBA, Ltd.), and was found to be 165 nm.

[0809] <Formation of the protective layer>

[0810] One rod of the following protective coating solution was applied to the image recording layer and dried at 120°C for 60 seconds to form a dry coating weight of 0.05 g / m². 2 The protective layer was used to create the original lithographic printing plate.

[0811] -Protective coating liquid 1-

[0812] Inorganic layered compound dispersion (1) (below): 0.5625 parts

[0813] • Hydrophilic polymer (1) (20% aqueous solution of the following compound): 0.0825 parts

[0814] • METOLOSE SM04 (methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., degree of methoxy substitution = 1.8): 0.0125 parts

[0815] • RAPISOL A-80 (anionic surfactant, manufactured by NOF CORPORATION, 80% aqueous solution): 0.007 parts

[0816] • Ion-exchanged water: 4.3355 parts

[0817] [Chemical Formula 27]

[0818]

[0819] The following shows the preparation method of the inorganic layered compound dispersion (1) used in the above protective coating liquid.

[0820] Preparation of Inorganic Layered Compound Dispersion (1) -

[0821] 6.4 parts of synthetic mica (SOMASIF ME-100, manufactured by Co-op Chemical Co., Ltd.) were added to 193.6 parts of ion-exchanged water and dispersed using a homogenizer until the volume average particle size (laser scattering method) was 3 μm. The aspect ratio of the obtained dispersed particles was greater than 100.

[0822] ~Prescription 3~

[0823] <Formation of the base coating>

[0824] The obtained support A was coated with a dry coating at a rate of 0.1 g / m². 2 The above-mentioned primer coating liquid is applied in a manner that forms the primer coating.

[0825] <Formation of Image Recording Layer>

[0826] The following image recording layer coating solution was applied to the primer layer and dried at 120°C for 40 seconds, resulting in a dry coating weight of 1.0 g / m². 2 Image recording layer.

[0827] -Image recording layer coating solution 3-

[0828] Infrared absorber (IR-1): 0.0120 parts

[0829] Infrared absorber (IR-2 above): 0.0250 parts

[0830] Chromoplast precursor 1: Add the compounds and amounts listed in Table 3.

[0831] Chromoplast precursor 2: Add the compounds and amounts listed in Table 3.

[0832] Electron-accepting polymerization initiator (Int-1 above): 0.1090 parts

[0833] Electron-donating polymerization initiator (TPB above): 0.0250 parts

[0834] Polymerizable compound (M-4 above): 0.4714 parts

[0835] Anionic surfactant (A-1 above): 0.0400 parts

[0836] Fluorinated surfactant (W-1 above): 0.0042 parts

[0837] 2-Butanone: 4.3551 parts

[0838] 1-Methoxy-2-propanol: 3.6383 parts

[0839] Methanol: 2.6947 parts

[0840] The above polymer particles R: 2.6163 parts

[0841] IR-1: The following compounds

[0842] [Chemical Formula 28]

[0843] IR-1

[0844]

[0845] <Formation of the protective layer>

[0846] The following protective coating solution was applied to the image recording layer using two rods and dried at 120°C for 60 seconds, resulting in a dry coating weight of 0.05 g / m². 2 The protective layer was used to create the original lithographic printing plate.

[0847] -Protective coating liquid 2-

[0848] • Inorganic layered compound dispersion (1): 0.5625 parts

[0849] • Hydrophilic polymer (1) (20% aqueous solution of the above compound): 0.0825 parts

[0850] • METOLOSE SM04 (methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., degree of methoxy substitution = 1.8): 0.0250 parts

[0851] • RAPISOL A-80 (anionic surfactant, manufactured by NOF CORPORATION, 80% aqueous solution): 0.0007 parts

[0852] • Ion-exchanged water: 4,330 parts

[0853] <Evaluation of the original lithographed version>

[0854] [Ink Turbidity Inhibition]

[0855] Using the Magnus800 Quantum manufactured by Eastman Kodak Company, which is equipped with an infrared semiconductor laser, the original lithographic printing plate was exposed under the following conditions: output power of 27W, external drum speed of 450rpm, and resolution of 2,400dpi (dots per inch, 1 inch is 2.54cm). (Equivalent to irradiation energy of 110mJ / cm²) 2 The exposed image includes a solid image.

[0856] The exposed originals were not developed and were mounted on the cylinders of a Heidelberger Druckmaschinen AG printing press (636mm × 939mm). A 100L dampening solution circulation tank with a built-in nonwoven filter and temperature control was connected to the printing press. 80L of dampening solution S-Z1 (manufactured by Fujifilm Corporation) at 2.0% by mass was added to the circulation tank, and UV-curable ink (T&K solvent ink) was used as the printing ink. After supplying the dampening solution and ink using a standard automatic printing start-up method, 300 sheets were printed at a printing speed of 10,000 sheets per hour on Tokubishi Art (continuous yield: 76.5kg, manufactured by Mitsubishi Paper Mills Limited) paper. The ink turbidity suppression was evaluated based on the color difference ΔE between the ink color of the solid areas of the paper before printing and the ink color of the solid areas after 10 repeated printings. The smaller the value of ΔE, the less turbidity there is, and the better the ink turbidity suppression performance.

[0857] [Visual Recognition Evaluation]

[0858] The obtained lithographic printing plate was exposed under the same conditions as the ink turbidity suppression evaluation described above, with the image of the "Fuji" character as the exposed area, at a size of 3 to 14 dots. Under an 800 lux white light, the exposed lithographic printing plate was placed vertically relative to the ground, and testers stood 1 meter away from the plate after exposure, evaluating the number of dots of the smallest character that could be accurately read with both eyes. The evaluation was conducted within 30 minutes of exposing the lithographic printing plate. The average value of 10 testers was calculated, and visual recognition was evaluated according to the following criteria. A or B is preferred.

[0859] A: 3 points or more but less than 5 points

[0860] B: 5 points or more but less than 6 points

[0861] C: 6 points or higher but less than 7 points

[0862] D: 7 points or higher but less than 9 points

[0863] E: 9 o'clock or higher but less than 11 o'clock

[0864] F: Above 11 o'clock

[0865] <Sensor Readability>

[0866] The obtained lithographic printing plate original was exposed using a Trendsetter Q800 manufactured by Eastman Kodak Company, which is equipped with an infrared semiconductor laser, at an output power of 14W, an external drum speed of 360rpm, and a resolution of 2,400dpi (dots per inch, 1 inch is 2.54cm). The exposure energy was equivalent to 110mJ / cm². 2 The exposed image contains a data matrix code. This data matrix code is read using an SR-1000W sensor manufactured by KEYENCE CORPORATION. A read rate of 100% is considered acceptable; anything else is considered unacceptable.

[0867] [Table 3]

[0868]

[0869] In Table 3, λmax1 represents the maximum absorption wavelength of the chromophore generated from the chromophore precursor 1 in the range of wavelengths above 380 nm and below 580 nm, and λmax2 represents the maximum absorption wavelength of the chromophore generated from the chromophore precursor 1 or the chromophore precursor 2 in the range of wavelengths above 580 nm and below 750 nm.

[0870] Furthermore, the absorbance of the aforementioned chromophore precursor and the chromophore generated from the aforementioned chromophore precursor are determined by the aforementioned method.

[0871] The following shows the details of the abbreviations recorded in Table 3.

[0872] Chromosome precursor

[0873] CS-1~CS-4: The following compounds

[0874] CL-1~CL-7: The following compounds

[0875] [Chemical Formula 29]

[0876]

[0877] [Chemical Formula 30]

[0878]

[0879] [Chemical Formula 31]

[0880]

[0881] Furthermore, the maximum absorption wavelength (λmax) and ε of the chromophore precursors CS-1 to CS-4 and CL-1 to CL-7 were determined using the methods described above. The measurement results are shown in Table 4 below.

[0882] [Table 4]

[0883]

[0884] As can be seen from the results recorded in Table 3, the original offset printing plate involved in the embodiment has superior visual recognition and sensor readability compared with the original offset printing plate involved in the comparative example.

[0885] Furthermore, it is known that the original offset printing plate involved in the embodiments also has excellent ink turbidity suppression properties.

[0886] (Examples 16 to 30)

[0887] In the above evaluation of ink turbidity suppression, visual recognition, and sensor readability, exposure and development were performed under the following conditions with various parameters such as SD value, Slope value, and Curve value set. Otherwise, the original offset printing plate was made and evaluated in the same manner as in Examples 1 to 15.

[0888] The original lithographic printing plate is exposed to the specified image shape. It is then developed by gently rubbing it with a sponge (manufactured by 3M Company) soaked in PS finishing gum FN-6 (manufactured by Fujifilm Corporation). Next, the plate surface is cleaned with a cloth containing water. Then, a 10% aqueous solution of citric acid is soaked into the sponge (manufactured by 3M Company) and spread evenly on the plate surface to make the image area develop color.

[0889] The evaluation results of ink turbidity suppression, visual recognition and sensor readability in Examples 16 to 30 are the same as those in Examples 1 to 15.

[0890] The entire contents of the publications of Japanese Patent Application No. 2021-141516, filed on August 31, 2021, and Japanese Patent Application No. 2022-031973, filed on March 2, 2022, are incorporated herein by reference.

[0891] All documents, patent applications and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application and technical standard was specifically and individually set forth by reference.

[0892] Description of Symbols

[0893] 1-aluminum plate, 2 and 4-roller brushes, 3-grinding slurry, 5, 6, 7 and 8-support rolls, 12a, 12b-aluminum supports, 14-undercoat layer, 16-image recording layer, 18-aluminum plate, 20a, 20b-anodized films, 22a, 22b-micropores, 24-large-diameter pore portion, 26-small-diameter pore portion, D-depth of the large-diameter pore portion, 50-main electrolytic cell, 52-radial drum roll, 51-AC power supply, 53a and 53b-main electrodes, 55-electrolyte, 54-electrolyte supply port, 56-slit, 57-electrolyte channel, 60-auxiliary anode tank, 58-auxiliary anode, Ex-electrolyte discharge port, S-liquid supply, W-aluminum plate, 610-anodizing treatment apparatus, 612-power supply tank, 614-electrolytic treatment tank, 616-aluminum plate, 618, 626-electrolyte, 620-power supply electrode, 622, 628-rolls, 624-clamping roll, 630-electrolytic electrode, 632-tank wall, 634-DC power supply, ta-anode reaction time, tc-cathode reaction time, tp-time for current to reach peak value from 0, Ia-current at peak value on the anode circulation side, Ic-current at peak value on the cathode circulation side, AA-current for anode reaction of aluminum plate, CA-current for cathode reaction of aluminum plate.

Claims

1. An on-machine developing type lithographic printing plate master, comprising a support and an image recording layer on the support, The image recording layer comprises a polymerizable compound, a polymerization initiator, an infrared absorber, and a chromophore precursor. The chromophore generated from the chromophore precursor has: The maximum absorption wavelength is in the range of 380 nm or higher and less than 580 nm, and the absorbance difference between the wavelength and that of the chromophore precursor is 0.1 or higher; and The maximum absorption wavelength is in the range of 580 nm to 750 nm and has an absorbance difference of 0.07 or more from the chromophore precursor. The molar absorptivity ε of the chromophore at any of the maximum absorption wavelengths is greater than 35000.

2. An on-machine developing type lithographic printing plate master, comprising a support and an image recording layer on the support, The image recording layer comprises a polymerizable compound, a polymerization initiator, an infrared absorber, and a chromophore precursor. The chromophore generated from the chromophore precursor has: The maximum absorption wavelength is in the range of 380 nm or higher and less than 580 nm, and the absorbance difference between the wavelength and that of the chromophore precursor is 0.1 or higher; and The maximum absorption wavelength is in the range of 580 nm to 750 nm and has an absorbance difference of 0.07 or more from the chromophore precursor. In the chromophore, the maximum absorption wavelength in the range of 580 nm to 750 nm and with an absorbance difference of 0.07 or more from the chromophore precursor is the maximum absorption wavelength in the range of 580 nm to 660 nm and with an absorbance difference of 0.07 or more from the chromophore precursor.

3. An on-machine developing type lithographic printing plate master, comprising a support and an image recording layer on the support, The image recording layer comprises a polymerizable compound, a polymerization initiator, an infrared absorber, and a chromophore precursor. The chromophore generated from the chromophore precursor has: The maximum absorption wavelength is in the range of 380 nm or higher and less than 580 nm, and the absorbance difference between the wavelength and that of the chromophore precursor is 0.1 or higher; and The maximum absorption wavelength is in the range of 580 nm to 750 nm and has an absorbance difference of 0.07 or more from the chromophore precursor. The chromophore precursor contains two or more chromophore precursors.

4. The on-machine developing type lithographic printing plate original according to claim 2 or 3, wherein, The molar absorptivity ε of the chromophore at any of the maximum absorption wavelengths is greater than 35000.

5. The on-machine developing type lithographic printing plate original according to any one of claims 1 to 3, wherein, The chromophore precursor is a colorless pigment.

6. The on-machine developing type lithographic printing plate original according to any one of claims 1 to 3, wherein, The chromophore precursor is an acid chromophore.

7. The on-machine developing type lithographic printing plate original according to claim 1 or 2, wherein, The chromophore precursor contains two or more chromophore precursors.

8. The on-machine developing type lithographic printing plate original according to claim 7, wherein, The chromophore precursor comprises two types of chromophore precursors.

9. The on-machine developing type lithographic printing plate original according to any one of claims 1 to 3, wherein, In the chromophore, the maximum absorption wavelength in the range of 380 nm or more and less than 580 nm, and the maximum absorption wavelength with an absorbance difference of 0.1 or more from the chromophore precursor, is in the range of 500 nm or more and less than 580 nm, and the maximum absorption wavelength with an absorbance difference of 0.1 or more from the chromophore precursor.

10. The on-machine developing type lithographic printing plate original according to claim 1 or 3, wherein, In the chromophore, the maximum absorption wavelength in the range of 580 nm to 750 nm and with an absorbance difference of 0.07 or more from the chromophore precursor is the maximum absorption wavelength in the range of 580 nm to 660 nm and with an absorbance difference of 0.07 or more from the chromophore precursor.

11. The on-machine developable lithographic printing plate original according to any one of claims 1 to 3, wherein, The ring-opening percentage of the chromophore precursor, calculated by the following formula, is 40 mol% to 99 mol%. Ring-opening rate = molar absorptivity when 1 molar equivalent of acid is added to the chromophore precursor / molar absorptivity ε of the chromophore generated from the chromophore precursor × 100.

12. A method for manufacturing a lithographic printing plate, comprising the following steps: The machine-developable lithographic printing plate original as described in any one of claims 1 to 3 is exposed into an image; and The printing press supplies at least one of printing ink and dampening solution to remove the image recording layer from the non-image area.

13. The method for manufacturing a lithographic printing plate according to claim 12, further comprising the following steps: Sensors are used to identify the original lithographic printing plate after exposure.

14. A planographic printing method, comprising the following steps: The original lithographic printing plate of any one of claims 1 to 3 is exposed into an image shape; To produce a lithographic printing plate by supplying at least one of printing ink and dampening solution to remove the image recording layer (excluding the image portion) from a printing press; and Printing is carried out using the obtained lithographic printing plates.

15. The offset printing method according to claim 14, further comprising the following steps: Sensors are used to identify the original lithographic printing plate after exposure.

Images