Information reading method, reading system, and attachment for reading device

Abstract

This invention provides an information reading method capable of accurately reading printing plate identification information added to an on-press development type lithographic printing plate master configured to enhance the visibility of the exposed portion, as well as a reading system and a reading device attachment that can be used therefor. [Solution] An information reading method comprising: a first step of preparing an on-press development type lithographic printing plate master having an exposure area including a colorant having an absorption maximum in the visible range, and an unexposed area, wherein the ΔL between the exposure area and the unexposed area is 10 or more, and printing plate identification information formed on the surface on the image forming layer side with water-soluble ink; a second step of imaging the on-press development type lithographic printing plate master with an image sensor while a filter is provided between the on-press development type lithographic printing plate master and an image sensor that cuts out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range; and a third step of acquiring the printing plate identification information based on the image data obtained by imaging in the second step.

Description

[Technical Field]

[0001] The technology disclosed herein relates to an information reading method, a reading system, and an attachment for a reading device. [Background technology]

[0002] Patent Document 1 describes a method in which a data identification area consisting of one row and multiple digits is partitioned at a desired position on the printing plate, data marks are applied to the partitioned data identification areas using ink of a different color from the color of the image area or non-image area, and when these data marks are imaged by a matching imaging means, a filter provided on the matching imaging means absorbs or transmits the color components of the image area of ​​the printing plate.

[0003] Patent Document 2 describes a system comprising: an exposure unit for image exposure of a lithographic printing plate; a printing unit for printing plate information on the lithographic printing plate; and a coating unit having a coating means for applying a treatment solution containing a hydrophilizing agent to an area within 1 cm from at least one edge of the lithographic printing plate, wherein the plate information is printed using water-based ink. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-105263 [Patent Document 2] Japanese Patent Publication No. 2019-22983 [Overview of the project] [Problems that the invention aims to solve]

[0005] The technology disclosed herein aims to enable high-precision reading of printing plate identification information added to an on-press development type lithographic printing plate master configured to enhance the visibility of the exposed portion. [Means for solving the problem]

[0006] An information reading method according to one embodiment of the technology of this disclosure comprises: a first step of preparing an on-press development type lithographic printing plate master having an exposure area including a chromogen having an absorption maximum in the visible range, and an unexposed area, wherein the ΔL between the exposure area and the unexposed area is 10 or more, and printing plate identification information formed on the surface on the image forming layer side with water-soluble ink; a second step of imaging the on-press development type lithographic printing plate master with an image sensor while a filter is provided between the on-press development type lithographic printing plate master and an image sensor that cuts out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range; and a third step of acquiring the printing plate identification information based on the image data obtained by imaging in the second step.

[0007] A reading system according to one embodiment of the technology of the present disclosure comprises: an image sensor; an on-press development type lithographic printing plate having an exposure portion and an unexposed portion including a chromogen having an absorption maximum in the visible range, wherein the ΔL between the exposure portion and the unexposed portion is 10 or more; and a printing plate identification information formed on the surface on the image forming layer side with water-soluble ink; a filter provided between the image sensor and the original image sensor to cut out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range; and a processor that acquires the printing plate identification information based on image data obtained by imaging the on-press development type lithographic printing plate through the filter with the image sensor.

[0008] An attachment to a reading device according to one embodiment of the technology of the present disclosure is an attachment to a reading device capable of reading printing plate identification information from an on-press development type lithographic printing plate master plate having an exposed portion and an unexposed portion including a chromogen having an absorption maximum in the visible range, an image forming layer having a ΔL of 10 or more between the exposed portion and the unexposed portion, and printing plate identification information formed on the surface on the image forming layer side with water-soluble ink, and comprising a filter that cuts out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range, and a support portion that supports the filter, wherein the support portion is configured to be detachable from the reading device so that the on-press development type lithographic printing plate master plate can be imaged by the image sensor of the reading device through the filter.

[0009] An attachment to a reading device according to one embodiment of the technology of the present disclosure is an attachment to a reading device capable of reading printing plate identification information from an on-press development type lithographic printing plate master plate having an exposure section including a chromogen having an absorption maximum in the visible range, and a non-exposure section, wherein the ΔL between the exposure section and the non-exposure section is 10 or more, and printing plate identification information is formed on the surface on the image-forming layer side with water-soluble ink, and the attachment comprises a filter that cuts out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range, and an adhesive sheet attached to the filter, which has an adhesive applied to a substrate that does not absorb in the visible range, wherein the filter is configured to be attached by the adhesive sheet in a position that covers the imaging window of the reading device. [Effects of the Invention]

[0010] According to the technology disclosed herein, it is possible to read with high accuracy the printing plate identification information attached to an on-press development type lithographic printing plate original that is configured to enhance the visibility of the exposed portion. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of a reading system 60, which is one embodiment of the technology of this disclosure. [Figure 2]Figure 2 shows an example of the absorbance of the exposed area 13, the unexposed area 14, and the water-soluble ink 15. [Figure 3] Figure 3 is a schematic diagram showing an example of the external configuration of the reading device 100. [Figure 4] Figure 4 is a schematic diagram showing a modified example of the reading device 100. [Figure 5] Figure 5 shows an example of the optical characteristics of filter 50. [Figure 6] Figure 6 is a schematic diagram showing the general configuration of reading system 60A, which is a modified version of reading system 60. [Figure 7] Figure 7 is a schematic diagram showing the configuration of the attachment 52A of the reading device 100 in the reading system 60A. [Figure 8] Figure 8 shows the AC power supply waveform. [Figure 9] Figure 9 is a side view showing an example of a radial cell used in electrochemical surface roughening treatment using alternating current. [Modes for carrying out the invention]

[0012] Figure 1 is a schematic diagram showing the general configuration of a reading system 60, which is one embodiment of the technology of this disclosure. The reading system 60 is capable of optically reading printing plate identification information formed on a lithographic printing plate.

[0013] A lithographic printing plate is formed by mechanically, chemically, and electrochemically treating the surface of a thin metal support, such as aluminum, which is formed in the shape of a rectangular plate, to create a surface treatment layer, on which an image-forming layer (photosensitive or thermal layer) is formed. This image-forming layer undergoes plate-making processes such as exposure, development (developing and washing), and gumming. After plate-making, ink is applied to the lithographic printing plate, and characters or images are printed on the paper. In recent years, gumming has been omitted, and development and ink application are now performed simultaneously.

[0014] The reading system 60 is particularly effective when reading plate identification information formed on an on-press development type lithographic printing plate master that is developed while set in the printing press. Figure 1 shows an example of an on-press development type lithographic printing plate master, plate 10, after exposure treatment.

[0015] The original plate 10 comprises a support 11, an image forming layer 12 formed on one side of the support 11 in the thickness direction, and a water-soluble ink 15 formed by printing or the like on the side of the image forming layer 12 opposite to the support 11.

[0016] The image forming layer 12 includes an exposed portion 13 and an unexposed portion 14, which are arranged in a two-dimensional manner. The unexposed portion 14 is removed by a developing process performed by a printing press.

[0017] Image exposure of an on-press type lithographic printing plate can be performed in accordance with the image exposure operation of a normal lithographic printing plate. Image exposure is performed by laser exposure through a transparent original image having line images, halftone images, etc., or by laser light scanning using digital data. The wavelength of the light source is preferably 700 to 1400 nm. Suitable light sources for 700 to 1400 nm include solid-state lasers and semiconductor lasers that emit infrared rays. For infrared lasers, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy is preferably 10 to 300 mJ / cm2. It is preferable to use a multi-beam laser device to shorten the exposure time.

[0018] The exposure mechanism may be an internal drum type, an external drum type, a flatbed type, or any other. Image exposure can be performed by conventional methods using a platesetter or the like. Examples of commercially available platesetters include the AMZISetter-SX manufactured by NEC Corporation, the GX-9600 manufactured by Panasonic Connect Corporation, and the TRENDSETTER NEWS manufactured by Kodak.

[0019] On-press development and printing of lithographic printing plates can be carried out by conventional methods. Specifically, when dampening water and printing ink are supplied to an image-exposed lithographic printing plate on the printing press, the image-forming layer, hardened by exposure, forms an ink-receiving area with a lipophilic surface in the exposed areas of the image-forming layer. On the other hand, in the unexposed areas, the unhardened image-forming layer is dissolved or dispersed and removed by the supplied dampening water and / or printing ink, exposing a hydrophilic surface in those areas. As a result, the dampening water adheres to the exposed hydrophilic surface, and the printing ink adheres to the image-forming layer in the exposed areas, initiating printing. Here, what is initially supplied to the surface of the lithographic printing plate may be either dampening water or printing ink, but it is preferable to supply dampening water first in order to allow the dampening water to penetrate and promote on-press development.

[0020] The water-soluble ink 15 is formed by printing plate identification information, such as code information (e.g., two-dimensional codes), character information, or symbol information, onto the surface of the image-forming layer 12 using inkjet printing or the like. The water-soluble ink 15 is removed by a water washing process during the development process performed by the printing press. Therefore, there are no restrictions on the position in the image-forming layer 12 where the water-soluble ink 15 is formed. For example, as shown in Figure 1, the water-soluble ink 15 can also be formed in a position that overlaps with the exposed area 13, which is not removed by the development process, when viewed in the thickness direction of the original plate 10.

[0021] The printing plate identification information specifically refers to information for properly positioning the plate cylinder, and includes information such as the publication date, brand name, plate type, number of pages, color, folding machine name, and tracking information. The printing plate identification information can be printed using water-soluble ink, for example, by an inkjet coating device. Specifically, the methods described in Japanese Patent Publication No. 10-52906 and Japanese Patent Publication No. 10-166552 can be applied. Examples of commercially available inkjet coating devices include the Miyall newspaper printing plate printing system manufactured by Systemac Co., Ltd., and the Graphica 5000 industrial inkjet printer manufactured by Yamazaki Sangyo Co., Ltd. The following describes preferred examples of water-soluble inks, but is not limited to these.

[0022] [Water-based ink] In this embodiment, the water-soluble ink used when printing plate identification information is a solution obtained by dissolving a water-soluble dye in an aqueous medium.

[0023] {Water-soluble dye} Examples of water-soluble dyes include anionic dyes or cationic dyes that have excellent solubility in water. The content of water-soluble dyes in water-soluble inks is preferably in the range of 0.1 to 10% by mass. Examples of water-soluble dyes include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, and diphenylmethane dyes.

[0024] Considering that the image portion of the lithographic printing plate after exposure is often blue, the color of the water-soluble dye is preferably red or black, from the viewpoint of making the printed plate identification information clearer.

[0025] As water-soluble dyes, anionic dyes are preferred. Anionic dyes are preferably those having hydrophilic groups such as -SO3X (where X is Li, Na, or K) or -COOX (where X is Li, Na, or K).

[0026] {aqueous medium} The aqueous medium consists of water and an aqueous solvent. Deionized water, distilled water, etc., are preferably used as the water. The aqueous solvent is used as appropriate to adjust the drying of the water-soluble ink on the press-developable lithographic printing plate, and is preferably contained in the water-soluble ink in an amount of 0.1 to 50% by mass. One or more aqueous solvents such as methanol, ethanol, isopropyl alcohol, t-butanol, glycerin, propylene glycol, ethylene glycol, and polyethylene glycol can be used.

[0027] {Water-soluble fixing agent} Water-soluble inks preferably contain a water-soluble fixative. The water-soluble fixative is preferably included in the water-soluble ink in an amount of 0.1 to 20% by mass, and more preferably in an amount of 0.2 to 10% by mass, in order to form appropriate dots on the original plate of a press-developable lithographic printing plate, and to provide the water-soluble ink with appropriate drying properties and appropriate fixation, such as fixation that does not easily come off even when touched during work. One or more water-soluble polymers and sugars are used as the water-soluble fixative.

[0028] {Other ingredients} Water-soluble inks may also contain antifungal agents to prevent mold growth, antiprecipitation agents to suppress the formation of insoluble substances over time, pH adjusters to improve ink stability, defoamers to prevent foam formation during ink manufacturing, and surfactants to improve the solubility of water-soluble dyes.

[0029] In order to mount a lithographic printing plate to the printing press cylinder, it is preferable to create positioning holes on the edge of the gripping portion or both the gripping portion and the toe portion of the lithographic printing plate, and / or to bend the edge of the gripping portion or both the gripping portion and the toe portion into a predetermined shape to form a locking piece for mounting. Here, "positioning holes" refer to holes formed in the lithographic printing plate corresponding to positioning pins on the printing press cylinder for mounting the lithographic printing plate to the printing press cylinder, and are also called punch holes. The process of forming these punch holes is also called a punching process. "Locking piece" refers to a locking portion formed by bending the edge of the lithographic printing plate into a predetermined shape for mounting the lithographic printing plate to the printing press cylinder, and the process of forming this locking portion is also called a bending process. The method for creating the positioning holes and locking piece is not particularly limited, and known methods can be used. For example, the method described in Japanese Patent Application Publication No. 2010-89384 can be cited.

[0030] In multi-color printing, performing registration quickly after printing has started offers cost advantages in terms of reducing waste paper and work time. Therefore, it is preferable to read the registration marks (registration marks) on the lithographic printing plate, which serve as registration guides, with a camera and perform the punching and / or bending processes accordingly.

[0031] Suitable commercially available equipment used in the punching and / or bending processes include, for example, the Vision Punch Bender SIBM-V40 manufactured by Shimizu Seisakusho Co., Ltd. and the View Control Punch & Bender VC24 manufactured by Nishiken Graphics Co., Ltd.

[0032] The operator can mount the original plate 10 in the correct position on the printing press plate cylinder while confirming the plate identification information attached to the original plate 10, which has been created through the image exposure process, the plate identification information printing process, the punching process, and the bending process. The plate identification information attached to the original plate 10 that the operator confirms may include information drawn outside the margin of the lithographic printing plate original during the exposure process, or information printed on the surface of the lithographic printing plate original with water-soluble ink during the printing process. However, from the viewpoint of character size and visibility, it is preferable to confirm the information printed with water-soluble ink. Specifically, the methods described in Japanese Patent Publication No. 10-52906 and Japanese Patent Publication No. 10-166552 can be applied.

[0033] The image-forming layer 12 is configured such that the absorbance of the exposed area 13 and the absorbance of the unexposed area 14 in the visible range are adjusted to enhance the visibility of images, characters, etc., represented by the exposed area 13. In this specification, the difference between the brightness (L* value) of the exposed area 13 and the brightness (L* value) of the unexposed area 14 is defined as ΔL, and this ΔL is defined as an indicator of visibility. In this embodiment, the ΔL of the image-forming layer 12 is 10 or more. In this specification, the visible range is defined as the wavelength range from 400 nm to 700 nm.

[0034] Figure 2 shows an example of the absorbance of the exposed area 13, the unexposed area 14, and the water-soluble ink 15. As shown in Figure 2, the absorbance of the unexposed area 14 is low over a wide range of the visible spectrum. On the other hand, over a wide range of the visible spectrum, the absorbance of the exposed area 13 is higher than that of the unexposed area 14.

[0035] The absolute value of the difference in absorbance between the exposed area 13 and the unexposed area 14 is denoted as the absorbance difference ΔX. At a given wavelength, the larger the absorbance difference ΔX, the greater the difference between the intensity of light of that wavelength reflected from the unexposed area 14 and the intensity of light of that wavelength reflected from the exposed area 13. In other words, for light of wavelengths where the absorbance of the exposed area 13 is greater than that of the unexposed area 14, the unexposed area 14 will appear brighter (fainter), while the exposed area 13 will appear darker (darker). This difference in brightness (darkness) can improve the visibility of images and characters represented by the exposed area 13. In particular, as shown in Figure 2, by increasing the absorbance difference ΔX in the vicinity of the green wavelength range, which correlates with the brightness of the image, visibility can be easily improved compared to increasing the absorbance difference ΔX across the entire visible range.

[0036] The image forming layer 12 contains a chromogenic material that has an absorption maximum at a specific wavelength when exposed to light (infrared light). In the example in Figure 2, the image forming layer 12 contains a chromogenic material that has an absorption maximum in the visible range at a wavelength λm around 570 nm when exposed to light. The exposed portion 13 of the image forming layer 12 is the part that has been exposed to this light. Therefore, the exposed portion 13 has a higher absorbance than the unexposed portion 14 in the range before and after the wavelength λm.

[0037] As described above, the larger the absorbance difference ΔX, the higher the visibility of the exposed area 13. For example, by setting the absorbance difference ΔX to be greater than or equal to the threshold TH1, it is possible to sufficiently improve the visibility of the exposed area 13. The threshold TH1 can be arbitrarily determined according to the required visibility, but as an example, it is 0.1, preferably 0.15. In the following explanation, we will assume that the threshold TH1 is 0.15.

[0038] Figure 2 shows the second range R2, which is the wavelength range in which the absorbance difference ΔX is greater than or equal to the threshold TH1. The second range R2 includes the wavelength λm of the absorption maximum in the visible region of the exposure area 13 and is narrower than the visible region. Figure 2 also shows the range of the visible region other than the second range R2 as the third range R3. The third range R3 is shown as a range with shorter wavelengths than the second range R2 and a range with longer wavelengths than the second range R2.

[0039] The absorbance difference ΔX at wavelength λm is greater than the absorbance difference ΔX in the third range R3. Furthermore, the absorbance difference ΔX at wavelength λm is greater than the absorbance difference ΔX at other wavelengths in the visible region. In other words, the absorbance difference ΔX at wavelength λm is the largest among all absorbance differences ΔX in the visible region.

[0040] In this configuration, where the absorbance difference ΔX in the second range R2 is greater than or equal to the threshold TH1, and the absorbance difference ΔX in the third range R3 is less than the threshold TH1, it should be noted that, for example, when observing only the light in the third range R3 reflected from the original plate 10, the difference in brightness (density difference) between the exposed area 13 and the unexposed area 14 becomes small, and the visibility of the exposed area 13 decreases.

[0041] To enhance visibility, it is preferable that the absorbance difference ΔY, which is the absolute value of the difference in absorbance between the unexposed area 14 and the water-soluble ink 15, is equal to or greater than the threshold TH1 in at least part or all of the third range R3 of the visible range. Black ink can be used as the water-soluble ink 15 that satisfies these conditions.

[0042] The absorbance of the water-soluble ink 15 shown in Figure 2 is that of the case where black ink is used. As shown in Figure 2, the absorbance of the water-soluble ink 15 is higher than the absorbance of the unexposed area 14 by a threshold TH1 or more in the range from approximately 400 nm to 660 nm.

[0043] In the second range R2, both the absorbance difference ΔX and the absorbance difference ΔY are greater than or equal to the threshold TH1. Therefore, when the original plate 10 is observed in a visible light environment, the visibility of both the image or characters represented by the exposed area 13 and the printing plate identification information represented by the water-soluble ink 15 is increased. As a result, as shown in Figure 1, when the exposed area 13 and the water-soluble ink 15 overlap in the thickness direction of the original plate 10, it should be noted that the image or characters and the printing plate identification information overlap, making it difficult to distinguish between the two.

[0044] As shown in Figure 1, the reading system 60 comprises a reading device 100 and a filter 50. The reading device 100 includes an imaging unit 20 that images the original plate 10 to be read, a light irradiation unit 40 that irradiates the original plate 10 with light, and a control unit 30 that performs various processing and provides overall control. The reading device 100 is configured such that the image sensor 21 of the imaging unit 20 can image the original plate 10 through the filter 50, and the filter 50 is detachable. The filter 50 may be built into the reading device 100.

[0045] The imaging unit 20 includes an image sensor 21 such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

[0046] The light irradiation unit 40 has a light source 41 including a light-emitting element such as an LED (light-emitting diode) or an LD (laser diode). The light source 41 is configured to generate light in the visible range. The light irradiation unit 40 does not have to be built into the reading device 100, and may be provided separately from the reading device 100.

[0047] Figure 3 is a schematic diagram showing an example of the external configuration of the reading device 100. The reading device 100 comprises a housing 101 that houses an imaging unit 20, a control unit 30, and a light irradiation unit 40. The housing 101 is provided with an imaging window 102 and an illumination window 103.

[0048] Light emitted from the light source 41 of the light irradiation unit 40 is projected outside the housing 101 through the illumination window 103.

[0049] Light entering the imaging window 102 from the outside passes through the imaging optical system included in the imaging unit 20 and enters the image sensor 21. An attachment 52 is detachably attached to the housing 101 near the imaging window 102.

[0050] The attachment 52 comprises a filter 50 and a support portion 51 that detachably supports the filter 50. The support portion 51 is configured to be attachable to the housing 101 so that the image sensor 21 can capture an image of the subject (original plate 10) through the filter 50. In the example shown in Figure 3, the support portion 51 is configured to be attached in a position where the filter 50 covers the imaging window 102. The support portion 51 may be fixed to or integrated with the housing 101. The support portion 51 is configured to detachably support the filter 50, but is not limited to this configuration, and the filter 50 may be fixed to the support portion 51.

[0051] When the support portion 51 of the attachment 52 is mounted on the housing 101, as shown in Figure 1, a filter 50 is provided between the original plate 10 to be read and the image sensor 21. In the state shown in Figure 1, the original plate 10 is imaged by the image sensor 21 through the filter 50. The control unit 30 then acquires printing plate identification information formed by the water-soluble ink 15 based on the image data obtained from this imaging.

[0052] The filter 50 has optical properties that cut out light in a first range R1 within the visible range, which includes wavelength λm and is narrower than the visible range. Cutting out light in a predetermined range means that the transmittance of light in that predetermined range is 50% or less, preferably 60-30% or less, and more preferably 70-10% or less. The filter 50 also has optical properties that transmit at least a portion of light in the range of the visible range excluding the first range R1. Transmitting light in a predetermined range means that the transmittance of light in that predetermined range is greater than 50%, preferably greater than 60%, and more preferably greater than 70%.

[0053] For filter 50, commercially available options include ROSCO's E-Color 068 Sky Blue, 075 Evening Blue, and 052 Light Lavender.

[0054] Figure 4 shows a modified version of the reading device 100 shown in Figure 3. The reading device 100 shown in Figure 4 has the same configuration as the reading device 100 shown in Figure 3, except that attachment 52 has been changed to attachment 52B.

[0055] Attachment 52B comprises a filter 50 and an adhesive sheet 53 having an adhesive that does not absorb in the visible range applied to both sides of a substrate that does not absorb in the visible range. One side of the substrate of the adhesive sheet 53 is attached to one side of the filter 50 by adhesive. The other side of the substrate of the adhesive sheet 53 is attached to the housing 101 by adhesive, covering the imaging window 102. Attachment 52B can be made thinner than attachment 52. It can also be manufactured at a lower cost than attachment 52. By using attachment 52B, other objects are less likely to get caught on attachment 52B, and work using the reading device 100 can be performed more efficiently.

[0056] When the attachment 52B is mounted on the housing 101, as shown in Figure 1, a filter 50 is placed between the original plate 10 to be read and the image sensor 21. In the state shown in Figure 1, the original plate 10 is imaged by the image sensor 21 through the filter 50. The control unit 30 then acquires printing plate identification information formed by the water-soluble ink 15 based on the image data obtained from this imaging.

[0057] Figure 5 shows an example of the optical characteristics of filter 50. In the example shown in Figure 5, filter 50 cuts out light in the visible range from approximately 490 nm to approximately 700 nm and transmits light in the range from approximately 410 nm to less than approximately 490 nm. The range from approximately 490 nm to approximately 700 nm constitutes the first range R1. The first range R1 shown in Figure 5 includes the second range R2 shown in Figure 2. Thus, in the example in Figure 5, filter 50 cuts out light in the first range R1 (a range that combines a part of the third range R3 on the short wavelength side, the second range R2, and the third range R3 on the long wavelength side), which is wider than the second range R2, and transmits the remainder of the light in the third range R3 on the short wavelength side.

[0058] In the reading device 100, with the support portion 51 of the attachment 52 mounted on the housing 101, or with the adhesive sheet 53 of the attachment 52B attached to the housing 101, light is irradiated from the light irradiation unit 40 onto the image forming layer 12, and the image forming layer 12 is captured by passing it through the filter 50. At this time, the light incident on the image sensor 21 is strongly attenuated in the first range R1 (a range that combines the second range R2 and the third range R3 on the longer wavelength side).

[0059] Therefore, in the image data obtained by imaging with the image sensor 21, the difference in brightness (density difference) between the exposed area imaging region where the exposed area 13 is imaged and the unexposed area imaging region where the unexposed area 14 is imaged becomes small. On the other hand, the ink imaging region where the water-soluble ink 15 is imaged becomes sufficiently darker than these exposed area imaging region and unexposed area imaging region. For this reason, even when the exposed area 13 and the water-soluble ink 15 overlap in the thickness direction of the original plate 10, only the printing plate identification information expressed by the water-soluble ink 15 can be extracted from the image data with high accuracy. The control unit 30 extracts the ink imaging region from this image data to obtain the printing plate identification information and performs processing such as comparing it with predetermined information. Through these processes, the original plate 10 can be identified with high accuracy.

[0060] The process for using the reading system 60 is as follows: First, the original plate 10 shown in Figure 1 is prepared (Step 1). Next, the original plate 10 is imaged using the reading device 100 equipped with attachment 52 or attachment 52B (Step 2). Based on the image data obtained by this imaging, the control unit 30 acquires the printing plate identification information assigned to the original plate 10 (Step 3), and performs processing such as matching the original plate 10 based on the printing plate identification information (Step 4).

[0061] As described above, the reading system 60 allows the image sensor 21 to image the original plate 10 while cutting off the light from the first range R1, which includes the second range R2, where the visibility of the exposure area 13 is enhanced. Therefore, the brightness (density) of the image and characters expressed by the exposure area 13 can be made to differ significantly from the brightness (density) of the printing plate identification information expressed by the water-soluble ink 15. As a result, it becomes possible to read the printing plate identification information with high accuracy, and the identification accuracy of the original plate 10 can be improved.

[0062] Furthermore, in the reading system 60, the filter 50 is configured to be detachable from the reading device 100. Therefore, for example, the system can be built using an existing reading device 100, thereby reducing system construction costs. An example of an existing reading device is the Panasonic Connect tablet computer FZ-N1, which is used as an information terminal for the Systemac Co., Ltd. printing plate mounting check system Scope.

[0063] Furthermore, the attachment 52 is configured so that the filter 50 can be attached and detached. Therefore, the filter 50 can be replaced with one that has different optical properties. The optical properties required of the filter 50 may change depending on the absorbance of the image forming layer 12 of the original plate 10 and the absorbance of the water-soluble ink 15. Because the filter 50 is replaceable, the original plate 10 can be imaged through the appropriate filter 50 depending on the original plate 10 and the water-soluble ink 15. Therefore, it is possible to identify various original plates 10 with high accuracy. With attachment 52B, by preparing multiple types of filters 50 with different properties, the filter 50 with appropriate properties depending on the original plate 10 and the water-soluble ink 15 can be attached to the reading device 100 and used, making it possible to identify various original plates 10 with high accuracy.

[0064] In the example shown in Figure 5, filter 50 transmits a portion of the third range R3 on the short wavelength side and blocks the third range R3 on the long wavelength side, but it is not limited to this configuration. For example, a similar effect can be obtained even if the filter further transmits at least a portion of the third range R3 on the long wavelength side. Alternatively, filter 50 may block the third range R3 and second range R2 on the short wavelength side and transmit at least a portion of the third range R3 on the long wavelength side. In the water-soluble ink 15 shown in Figure 2, the absorbance of the third range R3 on the short wavelength side is higher than that of the third range R3 on the long wavelength side (in other words, the absorbance difference ΔY is larger). Therefore, as shown in Figure 5, by using filter 50 that transmits the third range R3 on the short wavelength side, the printing plate identification information can be read with higher accuracy. Alternatively, filter 50 may block the second range R2 and transmit part or all of the third range R3. That is, the first range R1 may coincide with the second range R2.

[0065] Figure 6 is a schematic diagram showing the general configuration of reading system 60A, which is a modified version of reading system 60. The overall configuration of reading system 60A is the same as that of reading system 60, except that the position of the filter 50 has been changed.

[0066] In the reading system 60A, the filter 50 is provided on an attachment to the reading device 100, similar to the reading system 60.

[0067] Figure 7 is a schematic diagram showing the configuration of attachment 52A of the reading device 100 in the reading system 60A. Attachment 52A is similar to attachment 52 in that it comprises a filter 50 and a support portion 51 that supports it.

[0068] The support portion 51 of attachment 52A is configured to be attachable to the housing 101 so that light from the light source 41 can be irradiated onto the subject (original plate 10) through the filter 50. In the example shown in Figure 7, the support portion 51 is configured to be attached in a position where the filter 50 covers the illumination window 103. The support portion 51 of attachment 52A may be fixed to or integrated with the housing 101. The support portion 51 of attachment 52A is configured to support the filter 50 in a detachable manner, but is not limited to this, and the filter 50 may be fixed to the support portion 51.

[0069] When the support portion 51 of attachment 52A is mounted on the housing 101, visible light generated by the light source 41 is irradiated through the filter 50. In other words, the light in the first range R1 of the visible light is attenuated, and the intensity of the light irradiated from the light irradiation unit 40 onto the original plate 10 is such that the intensity of the first range R1 is lower than the intensity of the ranges other than the first range R1 in the visible range.

[0070] As a result, when the original plate 10 is imaged by the image sensor 21 while light is irradiated from the light irradiation unit 40, the light incident on the image sensor 21 becomes equivalent to the light incident on the image sensor 21 in the reading system 60. That is, the light incident on the image sensor 21 is strongly attenuated in the first range R1 (the range that combines the second range R2 and the third range R3 on the longer wavelength side). Therefore, the same effect as the reading system 60 can be obtained. In addition, in the reading system 60A, it is possible to replace attachment 52A with attachment 52B shown in Figure 4.

[0071] The usage flow for the reading system 60A is as follows: First, the original plate 10 shown in Figure 1 is prepared (Step 1). Next, the original plate 10 is irradiated with light by the reading device 100 fitted with attachment 52A (Step 2). The original plate 10, which has been irradiated with light in Step 2, is imaged by the image sensor 21 of the reading device 100 (Step 3). Based on the image data obtained from this imaging, the control unit 30 acquires the printing plate identification information assigned to the original plate 10 (Step 4), and performs processing such as matching the original plate 10 based on the printing plate identification information (Step 5).

[0072] In this specification, each process performed by the control unit 30 is executed on any computer. Furthermore, any computer may perform these processes using a processor, a program, or a combination thereof. Any computer may be a general-purpose computer, a computer designed for a specific purpose, a workstation, or any other hardware element capable of executing a program.

[0073] A processor may consist of one or more hardware components, and the type of hardware is not limited. For example, a processor may consist of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a programmable logic device such as an FPGA (Field Programmable Gate Array), a dedicated circuit for executing specific processing such as an ASIC (Application Specific Integrated Circuit), a GPU (Graphic Processing Unit), or an NPU (Neural Processing Unit). Furthermore, the processor has various units or means that execute the various processes described in this embodiment. The type of hardware may also be a combination of different types of hardware. When multiple hardware components are configured to execute one or more processes of a processor, the multiple hardware components may reside in physically separate devices or in the same device. Also, in any embodiment, the order of the processes performed by the processor is not limited to the order described above and may be changed as appropriate. The hardware is composed of electrical circuits (circuitry) combining circuit elements such as semiconductor elements.

[0074] Furthermore, this embodiment may be implemented by hardware, software, firmware, microcode, or a combination thereof. The software, firmware, and microcode are composed of a program. The program may also be, for example, a group of program modules, each of which may be implemented by a processor configured to perform its respective function. The program may be program code or multiple code segments stored on one or more non-temporary computer-readable media (e.g., storage media or other storage). The program may be divided and stored on multiple non-temporary computer-readable media located on devices that are physically separated from each other. The program code or code segment may represent any combination of procedures, functions, subprograms, routines, subroutines, modules, software packages, classes, or instructions, data structures, or program statements. The program code or code segment may be connected to other code segments or hardware circuits by sending and receiving information, data, arguments, parameters, or memory contents.

[0075] Next, we will describe the details of the printing plates to which the technology of this disclosure is preferably applied.

[0076] (Support) As the support, an aluminum support is preferred. The aluminum plate used for such an aluminum support is made of a dimensionally stable metal mainly composed of aluminum, i.e., aluminum or an aluminum alloy. It is preferable to select from pure aluminum plates and alloys mainly composed of aluminum and containing trace amounts of other elements.

[0077] The foreign elements contained in aluminum alloys include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is 10% by mass or less. Pure aluminum sheets are preferred, but since it is difficult to manufacture completely pure aluminum due to smelting technology, alloys containing small amounts of foreign elements are also acceptable. The composition of the aluminum sheet used for the aluminum support is not specified, and conventionally known aluminum sheets, such as JIS A 1050, JIS A 1100, JIS A 3103, and JIS A 3005, can be used as appropriate. The thickness of the support (preferably an aluminum plate) is preferably about 0.1 to 0.6 mm.

[0078] (Anodized coating) The above-mentioned support preferably has an anodic oxide coating. The term "anodic oxide film" refers to an anodic oxide film (preferably an anodized aluminum film) having extremely fine pores (also called micropores) formed on the surface of a support (preferably an aluminum plate) by an anodizing treatment. The micropores extend from the surface of the anodic oxide film opposite the support along the thickness direction (support side, depth direction). The average diameter (average aperture diameter) on the surface of the anodic oxide film of the micropore is preferably 7 nm to 150 nm, more preferably 10 nm to 100 nm, even more preferably 10 nm to 60 nm, particularly preferably 15 nm to 60 nm, and most preferably 18 nm to 40 nm, from the viewpoint of tone reproducibility, print resistance, and blanket stain resistance. The depth of the micropore is preferably 10 nm to 3,000 nm, more preferably 10 nm to 2,000 nm, and even more preferably 10 nm to 1,000 nm.

[0079] The shape of a micropore is usually that of a nearly straight tube (or nearly cylindrical) with a diameter that remains almost constant in the depth direction (thickness direction), but it may also be conical in shape, where the diameter decreases continuously in the depth direction (thickness direction). Alternatively, it may be a shape in which the diameter decreases discontinuously in the depth direction (thickness direction). Examples of micropores with a shape in which the diameter becomes discontinuously smaller in the depth direction (thickness direction) include micropores composed of a large-diameter pore portion extending in the depth direction from the surface of the anodic oxide film and a small-diameter pore portion communicating with the bottom of the large-diameter pore portion and extending in the depth direction from the communication point.

[0080] Specifically, a micropore is preferred that consists of a large-diameter pore extending 10 nm to 1,000 nm in depth from the surface of the anodic oxide film, and a small-diameter pore communicating with the bottom of the large-diameter pore and extending a further 20 to 2,000 nm in depth from the communication point. The large-diameter and small-diameter hole sections are described in detail below.

[0081] -Large diameter hole- The average diameter (average aperture diameter) of the anodic oxide film surface in the large-diameter pores is preferably 7 nm to 150 nm, more preferably 10 nm to 100 nm, even more preferably 15 nm to 100 nm, particularly preferably 15 nm to 60 nm, and most preferably 18 nm to 40 nm, from the viewpoint of tone reproducibility, print resistance, and blanket stain resistance. The average diameter of the large-diameter pores is calculated by observing the surface of the anodic oxide film with a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000x (N=4 images), arbitrarily selecting 50 micropores (large-diameter pores) located in the 400nm × 600nm range from the four images obtained, measuring their diameters, and calculating the arithmetic mean. If the shape of the large-diameter opening is not circular, the equivalent diameter of the circle is used. The "equivalent diameter of the circle" is the diameter of the circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0082] The bottom of the large-diameter pore is preferably located at a depth of 70 nm to 1,000 nm (hereinafter also referred to as depth A) from the surface of the anodic oxide film. In other words, the large-diameter pore is preferably a pore that extends 70 nm to 1,000 nm in the depth direction (thickness direction) from the surface of the anodic oxide film. Among these, in terms of the superior effect of the manufacturing method of the lithographic printing plate, depth A is more preferably 90 nm to 850 nm, even more preferably 90 nm to 800 nm, and particularly preferably 90 nm to 600 nm. The above depth is calculated by taking a cross-sectional photograph (150,000x magnification) of the anodic oxide film, measuring the depth of 25 or more large-diameter pores, and taking the arithmetic mean.

[0083] The shape of the large-diameter hole is not particularly limited; for example, it can be approximately straight (approximately cylindrical) or conical, with the diameter decreasing towards the depth (thickness) direction, and an approximately straight shape is preferred. Furthermore, the shape of the bottom of the large-diameter hole is not particularly limited and may be curved (convex) or flat. The inner diameter of the large-diameter hole is not particularly limited, but it is preferable that it be about the same size as the diameter of the opening, or smaller than the diameter of the opening. The inner diameter of the large-diameter hole may differ from the diameter of the opening by about 1 nm to 10 nm.

[0084] -Small diameter hole- A small-diameter hole is a hole that communicates with the bottom of a large-diameter hole and extends further in the depth direction (thickness direction) beyond the point of communication. Usually, one small-diameter hole communicates with one large-diameter hole, but two or more small-diameter holes may communicate with the bottom of one large-diameter hole. The average diameter at the communication point of the small-diameter holes is preferably 15 nm or less, more preferably 13 nm or less, even more preferably 11 nm or less, and particularly preferably 10 nm or less. There is no particular lower limit, but 5 nm is preferred.

[0085] The average diameter of the small-diameter pores is calculated by observing the surface of the anodized film with a FE-SEM at a magnification of 150,000x (N=4 images), selecting 50 micropores (small-diameter pores) located in a 400nm × 600nm range from the four images obtained, measuring their diameters, and calculating the arithmetic mean. If the depth of the large-diameter pores is deep, the upper part of the anodized film (the area containing the large-diameter pores) may be cut (for example, by cutting with argon gas), and then the surface of the anodized film may be observed with the FE-SEM described above to determine the average diameter of the small-diameter pores. If the shape of the small-diameter hole is not circular, the equivalent diameter is used. The "equivalent diameter" is the diameter of the circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0086] The bottom of the small-diameter hole is preferably located 20 nm to 2,000 nm further in the depth direction from the communication position with the large-diameter hole (corresponding to depth A as described above). In other words, the small-diameter hole is a hole that extends further in the depth direction (thickness direction) from the communication position with the large-diameter hole, and the depth of the small-diameter hole is preferably 20 nm to 2,000 nm, more preferably 100 nm to 1,500 nm, and particularly preferably 200 nm to 1,000 nm. The above depth is calculated by taking a cross-sectional photograph (150,000x magnification) of the anodic oxide film, measuring the depth of 25 or more small-diameter pores, and taking the arithmetic mean.

[0087] The shape of the small-diameter hole is not particularly limited; for example, it can be approximately straight (approximately cylindrical) or conical, with the diameter decreasing towards the depth. A nearly straight shape is preferred. The shape of the bottom of the small-diameter hole is also not particularly limited; it may be curved (convex) or flat. The inner diameter of the small-diameter hole is not particularly limited, but it may be about the same size as the diameter at the communication position, or it may be smaller or larger than the above diameter. In general, the inner diameter of the small-diameter hole may differ from the diameter of the opening by about 1 nm to 10 nm.

[0088] The ratio of the average diameter on the anodic oxide film surface of the large-diameter pores to the average diameter at the communication point of the small-diameter pores, (average diameter on the anodic oxide film surface of the large-diameter pores) / (average diameter at the communication point of the small-diameter pores), is preferably 1.1 to 13, and more preferably 2.5 to 6.5. Furthermore, the ratio of the depth of the large-diameter hole to the depth of the small-diameter hole, (depth of large-diameter hole) / (depth of small-diameter hole), is preferably 0.005 to 50, and more preferably 0.025 to 40.

[0089] Furthermore, the shape of the micropore is generally a nearly straight tube (approximately cylindrical) shape where the diameter of the micropore remains almost constant in the depth direction (thickness direction), but it may also be a conical shape where the diameter increases continuously in the depth direction (thickness direction). Alternatively, it may be a shape where the diameter increases discontinuously in the depth direction (thickness direction). Examples of micropores with a shape in which the diameter increases discontinuously in the depth direction (thickness direction) include micropores composed of a small-diameter pore extending in the depth direction from the surface of the anodic oxide film and a large-diameter pore communicating with the bottom of the small-diameter pore and extending in the depth direction from the point of communication.

[0090] Specifically, a micropore is preferred that consists of a small-diameter pore extending 10 nm to 1,000 nm in depth from the surface of the anodic oxide film, and a large-diameter pore communicating with the bottom of the small-diameter pore and extending a further 20 to 2,000 nm in depth from the communication point.

[0091] -Small diameter hole- The average diameter (average aperture diameter) of the small-diameter pores on the anodic oxide film surface is not particularly limited, but is preferably 35 nm or less, more preferably 25 nm or less, and particularly preferably 20 nm or less. The lower limit is not particularly limited, but 15 nm is preferred. The average diameter of the small-diameter pores is calculated by observing the surface of the anodic oxide film with a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000x (N=4 images), arbitrarily selecting 50 micropores (small-diameter pores) located in the 400nm × 600nm range from the four images obtained, measuring their diameters, and calculating the arithmetic mean. If the shape of the small-diameter hole is not circular, the equivalent diameter is used. The "equivalent diameter" is the diameter of the circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0092] The bottom of the small-diameter pore is preferably located at a depth of 70 nm to 1,000 nm (hereinafter also referred to as depth A') from the surface of the anodic oxide film. In other words, the small-diameter pore is preferably a pore that extends 70 nm to 1,000 nm in the depth direction (thickness direction) from the surface of the anodic oxide film. The above depth is calculated by taking a cross-sectional photograph (150,000x magnification) of the anodic oxide film, measuring the depth of 25 or more large-diameter pores, and taking the arithmetic mean.

[0093] The shape of the small-diameter hole is not particularly limited; for example, it can be approximately straight (approximately cylindrical) or conical, with the diameter increasing in the depth direction (thickness direction), and an approximately straight shape is preferred. Furthermore, the shape of the bottom of the small-diameter hole is not particularly limited and may be curved (convex) or flat. The inner diameter of the small-diameter hole is not particularly limited, but it is preferable that it be about the same size as the diameter of the opening, or smaller than the diameter of the opening. The inner diameter of the small-diameter hole may differ from the diameter of the opening by about 1 nm to 10 nm.

[0094] -Large diameter hole- The large-diameter hole is a hole that communicates with the bottom of the small-diameter hole and extends further in the depth direction (thickness direction) beyond the point of communication. Typically, one large-diameter hole may have two or more small-diameter holes communicating with the bottom of one large-diameter hole. The average diameter at the communication position of the large-diameter hole is preferably 20 nm to 400 nm, more preferably 40 nm to 300 nm, even more preferably 50 nm to 200 nm, and particularly preferably 50 nm to 100 nm.

[0095] The average diameter of the large-diameter pores is calculated by observing the surface of the anodized film with a FE-SEM at a magnification of 150,000x (N=4 images), arbitrarily selecting 50 micropores (large-diameter pores) located in the 400nm × 600nm range from the four obtained images, measuring their diameters, and calculating the arithmetic mean. If the depth of the small-diameter pores is deep, the upper part of the anodized film (the area containing the small-diameter pores) may be cut (for example, by cutting with argon gas), and then the surface of the anodized film may be observed with the FE-SEM described above to determine the average diameter of the large-diameter pores. If the shape of the large-diameter opening is not circular, the equivalent diameter of the circle is used. The "equivalent diameter of the circle" is the diameter of the circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0096] The bottom of the large-diameter hole is preferably located 20 nm to 2,000 nm further in the depth direction from the communication point with the small-diameter hole (corresponding to depth A' described above). In other words, the large-diameter hole is a hole that extends further in the depth direction (thickness direction) from the communication point with the small-diameter hole, and the depth of the large-diameter hole is preferably 20 nm to 2,000 nm, more preferably 100 nm to 1,500 nm, and particularly preferably 200 nm to 1,000 nm. The above depth is calculated by taking a cross-sectional photograph (150,000x magnification) of the anodic oxide film, measuring the depth of 25 or more large-diameter pores, and taking the arithmetic mean.

[0097] The shape of the large-diameter hole is not particularly limited; for example, it can be approximately straight (approximately cylindrical) or conical, with the diameter decreasing towards the depth. A nearly straight shape is preferred. The shape of the bottom of the large-diameter hole is also not particularly limited; it may be curved (convex) or flat. The inner diameter of the large-diameter hole is not particularly limited, but it may be about the same size as the diameter at the communication position, or it may be smaller or larger than the above diameter. In general, the inner diameter of the large-diameter hole may differ from the diameter of the opening by about 1 nm to 10 nm.

[0098] The above support has an anodic oxide film, The above anodic oxide film is applied sequentially from the surface of the anodic oxide film toward the depth, The upper layer has a thickness of 30-500 nm and has micropores with an average diameter of 20-100 nm. An intermediate layer with a thickness of 100 to 300 nm having micropores whose average diameter is 1 / 2 to 5 times the average diameter of the micropores in the above-mentioned upper micropore layer, and A sublayer with a thickness of 300-2000 nm, having micropores with an average diameter of 15 nm or less. It is preferable that it has

[0099] In press-developed lithographic printing plates, high brightness on the surface of the anodic oxide coating of the support (the surface on which the image recording layer is formed) is useful from the viewpoint of improving image visibility. In the printing process of lithographic printing plates, a proofreading process is usually performed before the printing plate is mounted on the printing press to confirm that the desired image has been recorded. In the case of press-developed lithographic printing plates, it is necessary to check the image at the exposure stage, so a method is applied to create a so-called printout image in the exposed area. One method for quantitatively evaluating the visibility of the image portion of an exposed lithographic printing plate is to measure the brightness of the exposed and unexposed areas and determine the difference between the two. Here, the brightness value L* in the CIEL*a*b* color system can be used, and the measurement can be performed using a colorimeter (SpectroEye, manufactured by X-Rite Corporation). The larger the difference between the brightness of the exposed and unexposed areas obtained from the measurement, the easier the image portion is to see. It has been found that a large value of lightness L* in the CIEL*a*b* color system of the anodic oxide film surface is effective in increasing the difference in lightness between the exposed and unexposed areas of the image. Specifically, a value of lightness L* of 60 to 100 is preferable.

[0100] A support having an anodized film may optionally have a back coat layer on the side opposite to the side where a constituent layer containing a hydroxy acid compound having two or more hydroxyl groups is formed, which contains an organic polymer compound described in Japanese Patent Publication No. 5-45885 or a silicon alkoxy compound described in Japanese Patent Publication No. 6-35174.

[0101] (Manufacturing of aluminum supports with anodized coating) As an example of a support, a method for manufacturing an aluminum support having an anodic oxide coating is described. Aluminum supports having an anodized coating can be manufactured using known methods. The method for manufacturing aluminum supports having an anodized coating is not particularly limited. A preferred embodiment of the method for manufacturing aluminum supports having an anodized coating includes a step of roughening an aluminum plate (roughening step), an anodizing step of anodic oxidizing the roughened aluminum plate (anodic oxidation step), and a step of contacting the aluminum plate having the anodized coating obtained in the anodizing step with an acidic aqueous solution or an alkaline aqueous solution to enlarge the diameter of micropores in the anodized coating (pore widening step).

[0102] The following describes each step in detail.

[0103] <Surface roughening process> The surface roughening process involves applying a surface roughening treatment, including electrochemical surface roughening, to the surface of the aluminum plate. While it is preferable to perform the surface roughening process before the anodic oxidation process described later, it may be omitted if the aluminum plate already has a desirable surface shape.

[0104] The surface roughening treatment may consist solely of electrochemical roughening, or it may be a combination of electrochemical roughening, mechanical roughening, and at least one of chemical roughening. When combining mechanical surface roughening and electrochemical surface roughening, it is preferable to perform the electrochemical surface roughening after the mechanical surface roughening.

[0105] Electrochemical surface roughening treatment is preferably carried out in an aqueous solution of nitric acid or hydrochloric acid.

[0106] Mechanical surface roughening treatment is generally performed with the aim of achieving a surface roughness Ra: 0.35 to 1.0 μm on the surface of an aluminum plate. The conditions for the mechanical surface roughening treatment are not particularly limited, but can be carried out, for example, according to the method described in Japanese Patent Publication No. 50-40047. The mechanical surface roughening treatment can be carried out by brush grain treatment using a pumstone suspension or by a transfer method. Furthermore, the chemical surface roughening treatment is not particularly limited and can be carried out according to known methods.

[0107] Following the mechanical surface roughening treatment, it is preferable to perform the following chemical etching treatment. The chemical etching process, which follows the mechanical surface roughening treatment, is performed to smooth the edges of the uneven surface of the aluminum plate, prevent ink from sticking during printing, improve the stain resistance of the lithographic printing plate, and remove unwanted materials such as abrasive particles remaining on the surface. Chemical etching processes include etching with acids and etching with alkalis, but chemical etching using alkaline solutions (hereinafter also referred to as "alkaline etching") is particularly superior in terms of etching efficiency.

[0108] The alkaline agent used in the alkaline solution is not particularly limited, but examples of suitable alkaline agents include caustic soda, caustic potassium, sodium metasilicate, sodium carbonate, sodium aluminate, and sodium gluconate. The alkaline solution may contain aluminum ions. The concentration of the alkaline agent in the alkaline solution is preferably 0.01% by mass or more, more preferably 3% by mass or more, preferably 30% by mass or less, and more preferably 25% by mass or less. Furthermore, the temperature of the alkaline solution is preferably above room temperature, more preferably above 30°C, preferably below 80°C, and more preferably below 75°C.

[0109] The etching rate is 0.01 g / m². 2 The above is preferable, and 0.05 g / m 2 The above is more preferable, and also 30g / m 2 The following is preferable: 20 g / m 2 The following are preferable. The processing time is preferably 2 seconds to 5 minutes, depending on the etching amount, and more preferably 2 to 10 seconds from the viewpoint of improving productivity.

[0110] When alkaline etching is performed after mechanical surface roughening, it is preferable to perform chemical etching (hereinafter also referred to as "de-matt treatment") using a low-temperature acidic solution to remove the products generated by the alkaline etching. The acid used in the acidic solution is not particularly limited, but examples include sulfuric acid, nitric acid, and hydrochloric acid. The concentration of the acidic solution is preferably 1 to 50% by mass. The temperature of the acidic solution is preferably 20 to 80°C. When the concentration and temperature of the acidic solution are within this range, the resistance to spot-like stains in the lithographic printing plate using an aluminum support is further improved.

[0111] Preferred embodiments of the surface roughening process are illustrated below. -Pattern SA- An embodiment in which the processes shown in (1) to (8) are carried out in this order. (1) Chemical etching treatment using an alkaline aqueous solution (first alkaline etching treatment) (2) Chemical etching treatment using an acidic aqueous solution (first desmatt treatment) (3) Electrochemical roughening treatment using an aqueous solution mainly composed of nitric acid (first electrochemical roughening treatment) (4) Chemical etching treatment using an alkaline aqueous solution (second alkaline etching treatment) (5) Chemical etching treatment using an acidic aqueous solution (second desmatt treatment) (6) Electrochemical roughening treatment using an aqueous solution mainly composed of hydrochloric acid (second electrochemical roughening treatment) (7) Chemical etching treatment using an alkaline aqueous solution (third alkaline etching treatment) (8) Chemical etching treatment using an acidic aqueous solution (third desmatt treatment)

[0112] -Mode SB- An embodiment in which the processes shown in (11) to (15) are carried out in this order. (11) Chemical etching treatment using an alkaline aqueous solution (fourth alkaline etching treatment) (12) Chemical etching treatment using an acidic aqueous solution (fourth desmatt treatment) (13) Electrochemical roughening treatment using an aqueous solution mainly composed of hydrochloric acid (third electrochemical roughening treatment) (14) Chemical etching treatment using an alkaline aqueous solution (5th alkaline etching treatment) (15) Chemical etching treatment using an acidic aqueous solution (5th desmatt treatment)

[0113] Mechanical surface roughening treatment may be performed before the treatment described in (1) of embodiment SA, or before the treatment described in (11) of embodiment SB, if necessary.

[0114] The amount of aluminum plate dissolved in the first and fourth alkaline etching treatments is 0.5 g / m². 2 ~30g / m 2 Preferably, 1.0 g / m 2 ~20g / m 2 This is preferable.

[0115] Examples of aqueous solutions mainly composed of nitric acid used in the first electrochemical roughening treatment in embodiment SA include aqueous solutions used in electrochemical roughening treatment using direct current or alternating current. For example, aqueous solutions obtained by adding aluminum nitrate, sodium nitrate, or ammonium nitrate to an aqueous solution of 1 g / L to 100 g / L of nitric acid include aqueous solutions. The aqueous solution mainly composed of hydrochloric acid used in the second electrochemical roughening treatment in embodiment SA and the third electrochemical roughening treatment in embodiment SB includes aqueous solutions used for electrochemical roughening treatment using direct current or alternating current. For example, an aqueous solution obtained by adding 0 g / L to 30 g / L of sulfuric acid to an aqueous hydrochloric acid solution of 1 g / L to 100 g / L is included. In addition, nitrate ions such as aluminum nitrate, sodium nitrate, or ammonium nitrate; chloride ions such as aluminum chloride, sodium chloride, or ammonium chloride may be further added to this aqueous solution.

[0116] For the alternating current power supply waveform of the electrochemical roughening treatment, a sine wave, square wave, trapezoidal wave, triangular wave, etc. can be used. The frequency is preferably 0.1 Hz to 250 Hz. Figure 8 is a graph showing an example of an alternating waveform current waveform diagram used for the electrochemical roughening treatment. In Figure 8, ta is the anode reaction time, tc is the cathode reaction time, tp is the time for the current to reach the peak from 0, Ia is the current at the peak on the anode cycle side, and Ic is the current at the peak on the cathode cycle side. In the trapezoidal wave, the time tp for the current to reach the peak from 0 is preferably 1 msec to 10 msec. The conditions for one cycle of the alternating current used in the electrochemical roughening treatment are such that the ratio tc / ta of the anode reaction time ta and the cathode reaction time tc of the aluminum plate is 1 to 20, the ratio Qc / Qa of the electric quantity Qc at the cathode and the electric quantity Qa at the anode of the aluminum plate is 0.3 to 20, and the anode reaction time ta is preferably in the range of 5 msec to 1,000 msec. The current density is such that both the current Ia on the anode cycle side and the current Ic on the cathode cycle side at the peak value of the trapezoidal wave are 10 to 200 A / dm 2 is preferred. Ic / Ia is preferably 0.3 to 20. The total electric quantity involved in the anode reaction of the aluminum plate at the time when the electrochemical roughening treatment is completed is 25 C / dm 2 ~1,000 C / dm 2 is preferred.

[0117] For the electrochemical roughening treatment using alternating current, the apparatus shown in Figure 9 can be used. Figure 9 is a side view showing an example of a radial type cell in the electrochemical roughening treatment using alternating current. In Figure 9, 150 is the main electrolytic cell, 151 is the alternating current power supply, 152 is the radial drum roller, 153a and 153b are the main electrodes, 154 is the electrolyte supply port, 155 is the electrolyte, 156 is the slit, 157 is the electrolyte passage, 158 is the auxiliary anode, 160 is the auxiliary anode cell, and W is the aluminum plate. When two or more electrolytic cells are used, the electrolytic conditions may be the same or different. The aluminum plate W is wound around a radial drum roller 152 immersed and disposed in the main electrolytic cell 150, and is electrolytically processed by main electrodes 153a and 153b connected to an AC power supply 151 during the conveyance process. The electrolytic solution 155 is supplied from an electrolytic solution supply port 154 through a slit 156 to an electrolytic solution passage 157 between the radial drum roller 152 and the main electrodes 153a and 153b. The aluminum plate W processed in the main electrolytic cell 150 is then electrolytically processed in the auxiliary anode cell 160. In this auxiliary anode cell 160, an auxiliary anode 158 is disposed opposite to the aluminum plate W, and the electrolytic solution 155 is supplied so as to flow through the space between the auxiliary anode 158 and the aluminum plate W.

[0118] The dissolution amount of the aluminum plate in the second alkali etching treatment is 1.0 g / m 2 ~20 g / m 2 which is preferable, and 2.0 g / m 2 ~10 g / m 2 is more preferable.

[0119] [[ID=!5]] The dissolution amount of the aluminum plate in the third alkali etching treatment and the fifth alkali etching treatment is 0.01 g / m 2 ~0.8 g / m 2 which is preferable, and 0.05 g / m 2 ~0.3 g / m 2 is more preferable.

[0120] In the chemical etching treatment (first to fifth desmuttreatment) using an acidic aqueous solution, an acidic aqueous solution containing phosphoric acid, nitric acid, sulfuric acid, chromic acid, hydrochloric acid, or a mixed acid containing two or more of these acids is preferably used. The concentration of the acid in the acidic aqueous solution is preferably 0.5 mass% to 60 mass%.

[0121] <Anodic oxidation treatment step> The anodizing process involves applying an anodizing treatment to the aluminum plate that has undergone the surface roughening treatment described above, thereby forming an aluminum oxide film on the surface of the aluminum plate. The anodizing treatment forms an aluminum anodic oxide film having micropores on the surface of the aluminum plate. Anodizing can be carried out by setting appropriate manufacturing conditions, taking into consideration the desired micropore shape, etc., according to methods conventionally known in this field.

[0122] In the anodizing process, aqueous solutions of sulfuric acid, phosphoric acid, oxalic acid, etc., can be mainly used as the electrolyte. In some cases, aqueous solutions or non-aqueous solutions of chromic acid, sulfamic acid, benzenesulfonic acid, or combinations of two or more of these can also be used. When direct current or alternating current is passed through the aluminum plate in the electrolyte, an anodic oxide film can be formed on the surface of the aluminum plate. The electrolyte may contain aluminum ions. The content of aluminum ions is not particularly limited, but 1 to 10 g / L is preferred.

[0123] The conditions for anodizing are set appropriately depending on the electrolyte used, but generally, the electrolyte concentration is 1 to 80% by mass (preferably 5 to 20% by mass), the liquid temperature is 5 to 70°C (preferably 10 to 60°C), and the current density is 0.5 to 60 A / dm². 2 (preferably 5-50 A / dm 2 A suitable range is 1 to 100V (preferably 5 to 50V) for the voltage and 1 to 100 seconds (preferably 5 to 60 seconds) for the electrolysis time.

[0124] The method of anodic oxidation in sulfuric acid at a high current density, as described in British Patent No. 1,412,768, is a preferred example of an anodizing treatment.

[0125] Anodizing can be performed multiple times. One or more conditions, such as the type, concentration, temperature, current density, voltage, and electrolysis time of the electrolyte used in each anodizing process, can be changed. If the anodizing process is performed twice, the first process may be called the first anodizing process, and the second anodizing process may be called the second anodizing process. By performing both the first and second anodizing processes, it is possible to form anodized films with different shapes, making it possible to provide lithographic printing plates with superior printing performance. Furthermore, it is also possible to perform the pore-widening treatment described below following the anodizing treatment, and then perform the anodizing treatment again. In this case, the process will involve the first anodizing treatment, the pore-widening treatment, and the second anodizing treatment. By utilizing the method of performing the first anodic oxidation treatment, pore widening treatment, and second anodic oxidation treatment described above, it is possible to form micropores consisting of large-diameter pores extending in the depth direction from the surface of the aforementioned anodic oxidation film, and small-diameter pores communicating with the bottom of the large-diameter pores and extending in the depth direction from the communication point.

[0126] <Pore-wide processing process> The pore widening process is a process (pore diameter enlargement process) that enlarges the diameter of micropores (pore diameter) present in the anodic oxide film formed by the above anodic oxidation process. This pore widening process enlarges the diameter of the micropores, resulting in the formation of an anodic oxide film with micropores having a larger average diameter.

[0127] Pore ​​widening can be performed by contacting the aluminum plate obtained by the above anodic oxidation process with an acidic aqueous solution or an alkaline aqueous solution. The method of contact is not particularly limited and examples include immersion and spraying. Among these, the immersion method is preferred.

[0128] When using an alkaline aqueous solution in the pore-widening process, it is preferable to use at least one alkaline aqueous solution selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. It is appropriate to adjust the pH of the alkaline aqueous solution to 11 to 13 and contact the aluminum plate with the alkaline aqueous solution for 1 to 300 seconds (preferably 1 to 50 seconds) under conditions of 10 to 70°C (preferably 20 to 50°C). In this case, the alkaline treatment solution may also contain metal salts of polyvalent weak acids such as carbonates, borates, and phosphates.

[0129] When using an aqueous acid solution in the pore-widening process, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, or a mixture thereof. The concentration of the aqueous acid solution is preferably 1 to 80% by mass, and more preferably 5 to 50% by mass. It is appropriate to contact the aluminum plate with the aqueous acid solution for 1 to 300 seconds (preferably 1 to 150 seconds) under conditions where the temperature of the aqueous acid solution is 5 to 70°C (preferably 10 to 60°C). Alkaline aqueous solution or acidic aqueous solution may contain aluminum ions. The aluminum ion content is not particularly limited, but 1 to 10 g / L is preferred.

[0130] A method for producing an aluminum support having an anodic oxide film may include a hydrophilization treatment step in which a hydrophilization treatment is performed after the pore-widening treatment step described above. For the hydrophilization treatment, a known method described in paragraphs 0109 to 0114 of Japanese Patent Application Publication No. 2005-254638 can be used.

[0131] Hydrophilization treatment is preferably carried out by methods such as immersion in an aqueous solution of alkali metal silicates such as sodium silicate or potassium silicate, or by applying a hydrophilic vinyl polymer or hydrophilic compound to form a hydrophilic undercoat layer.

[0132] Hydrophilization treatment with aqueous solutions of alkali metal silicates such as sodium silicate and potassium silicate can be carried out by the methods and procedures described in U.S. Patent No. 2,714,066 and U.S. Patent No. 3,181,461.

[0133] [Image recording layer] The image recording layer described above includes a chromogenic compound having a group that cleaves upon infrared exposure, a polymerization initiator, a polymerizable compound, and any other compound.

[0134] [Chromogenic compounds containing groups that cleave under infrared exposure] The image recording layer in the lithographic printing plate according to the present invention contains a chromogenic compound (hereinafter also referred to as "chromogenic compound") having a group that cleaves upon infrared exposure. The chromogenic compound contained in the above-mentioned image recording layer is preferably an infrared absorber that has the function of absorbing and decomposing infrared rays upon infrared exposure to produce color. Decomposition refers to the cleavage of groups that are cleaved by infrared exposure. Here, "color development" means that before infrared exposure, there is almost no absorption in the visible light region (wavelength range from 400 nm to 700 nm), but infrared exposure causes absorption in the visible light region. This also includes the shift of absorption from lower wavelength regions to longer wavelengths in the visible light region. Hereafter, a chromogenic compound that is formed by absorbing infrared light and decomposing upon infrared exposure will also be called a "chromogenic compound." Furthermore, it is preferable that the color-developing compound has the function of absorbing infrared rays upon infrared exposure and converting the absorbed infrared rays into heat. The above-mentioned decomposable infrared absorber only needs to absorb and decompose at least a portion of the light in the infrared wavelength range (wavelengths from 700 nm to 1 mm), but it is preferable that the infrared absorber has maximum absorption in the wavelength range of 700 nm to 1,400 nm.

[0135] The color-forming compound is preferably an infrared absorber that decomposes by heat, electron transfer, or both caused by infrared exposure, and more preferably an infrared absorber that decomposes by electron transfer caused by infrared exposure. Here, "decomposes by electron transfer" means that electrons excited from the HOMO (highest occupied molecular orbital) to the LUMO (lowest unoccupied molecular orbital) of the decomposable infrared absorber by infrared exposure undergo intramolecular electron transfer to an electron-accepting group (a group with a potential close to that of the LUMO) within the molecule, and decomposition occurs accordingly.

[0136] As the color-forming compound, a cyanine dye that decomposes by infrared exposure is preferable from the viewpoints of color-forming property and UV printing resistance of the resulting lithographic printing plate. The color-forming compound is more preferably a cyanine dye represented by the following formula 1 from the viewpoints of color-forming property and UV printing resistance of the resulting lithographic printing plate.

[0137]

Chemical formula

[0138] In formula 1, R 1 represents a group in which the R 1 -L bond cleaves upon infrared exposure, and R 11 ~R 18 each independently represents a hydrogen atom, a halogen atom, -Ra, -ORb, -SRc, or -NRdRe, Ra~Re each independently represents a hydrocarbon group, A1, A2, and a plurality of R 11 ~R 18 may be linked to form a monocyclic or polycyclic ring, A1 and A2 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, n 11 and n 12 each independently represents an integer from 0 to 5, provided that the sum of n 11 and n 12 is 2 or more, n 13 and n 14 each independently represents 0 or 1, L represents an oxygen atom, a sulfur atom, or -NR 10 -, and R 10represents a hydrogen atom, alkyl group, or aryl group, and Za represents a counterion that neutralizes the charge.

[0139] The cyanine dye represented by Equation 1 reacts to infrared light when exposed to R 1 - The L bond is cleaved, and L becomes =O, =S, or =NR 10 As a result, a chromogenic compound is formed. 1 These molecules detach to form radicals or ionic forms. These contribute to the polymerization of polymerizable compounds contained in the image recording layer.

[0140] In Equation 1, R 11 ~R 18 Each of these is preferably a hydrogen atom, -Ra, -ORb, -SRc, or -NRdRe. The hydrocarbon group in Ra~Re is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and even more preferably a hydrocarbon group having 1 to 10 carbon atoms. The above hydrocarbon group may be linear, branched, or have a cyclic structure.

[0141] R in Equation 1 11 ~R 14 Each of these is independently preferably a hydrogen atom or a hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom. Furthermore, R bonded to the carbon atom that L is bonded to and the carbon atom that L is bonded to. 11 and R 13 The alkyl group is preferred, and it is more preferable that the two are linked to form a ring. The formed ring is preferably a 5-membered ring or a 6-membered ring, and a 5-membered ring is more preferable. R bonded to the carbon atom to which A1+ is attached. 12 and R bonded to the carbon atom to which A2 is bonded 14 These are, respectively, R 15 and R 17 It is preferable to connect them to form a ring.

[0142] R in Equation 1 15 A hydrocarbon group is preferred. Also, R 15And R bonded to the carbon atom to which A1+ is bonded. 12 It is preferable that these elements are linked to form a ring. The formed ring is preferably an indolium ring, a pyrylium ring, a thiopyrillium ring, a benzoxazoline ring, or a benzimidazoline ring, with an indolium ring being more preferable from the viewpoint of color development. R in Equation 1 17 A hydrocarbon group is preferred. Also, R 17 And R bonded to the carbon atom to which A2 is bonded. 14 It is preferable that these rings are linked to form a ring. The formed ring is preferably an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring, or a benzimidazole ring, with an indole ring being more preferable from the viewpoint of color development. R in Equation 1 15 and R 17 It is preferable that these are the same group, and if each forms a ring, it is preferable that they form the same ring.

[0143] R in Equation 1 16 and R 18 It is preferable that they are the same group. Furthermore, from the viewpoint of improving the water solubility of the compound represented by formula 1, R 16 and R 18 Each of these groups is preferably an alkyl group having a (poly)oxyalkylene group or an alkyl group having an anionic structure, more preferably an alkoxyalkyl group, an alkyl group having a carboxylate group or a sulfonate group, and even more preferably an alkyl group having a sulfonate group at the terminal end. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. The countercation of the above anionic structure is R in formula 1. 1 -L may contain cations or A1+, or it may contain alkali metal cations or alkaline earth metal cations. The countercation of the above sulfonate group is R in formula 1. 1 -L may contain cations or A1+, or it may contain alkali metal cations or alkaline earth metal cations. Furthermore, the maximum absorption wavelength of the compound represented by Equation 1 is increased to a longer wavelength, and from the viewpoint of color development and print durability in lithographic printing plates, R 16 and R 18 Each of these is independently preferably an alkyl group or an alkyl group having an aromatic ring. The alkyl group is preferably one with 1 to 10 carbon atoms, more preferably one with 1 to 4 carbon atoms, and even more preferably a methyl group or an ethyl group. The alkyl group having an aromatic ring is preferably one with an aromatic ring at the terminal end, and more preferably a 2-phenylethyl group, a 2-naphthalenylethyl group, or a 2-(9-anthracenyl)ethyl group.

[0144] n in Equation 1 11 and n 12 The integer is preferably the same from 0 to 5, more preferably from 1 to 3, even more preferably 1 or 2, and particularly preferably 2.

[0145] In Formula 1, A1 and A2 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, with nitrogen atoms being preferred. In Formula 1, it is preferable that A1 and A2 are the same atom.

[0146] In Formula 1, Za represents a counterion that neutralizes the charge. When representing an anionic species, examples include sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, p-toluenesulfonate ions, and perchlorate ions, with hexafluorophosphate ions or hexafluoroantimonate ions being preferred. When representing a cationic species, examples include alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, and sulfonium ions, with sodium ions, potassium ions, ammonium ions, pyridinium ions, or sulfonium ions being preferred, and sodium ions, potassium ions, or ammonium ions being more preferred. R 11 ~R 18 and R 1 -L may have an anionic structure or a cationic structure, R11 ~R 18 and R 1 If all of -L are electrically neutral groups, Za is a monovalent counter anion, for example, R 11 ~R 18 and R 1 When -L has two or more anion structures, Za can also be a counter cation. Also, if the cyanine dye represented by Formula 1 has an electrically neutral structure throughout the compound, Za does not exist.

[0147] In Formula 1, R 1 The group in which the R 1 -L bond is cleaved by infrared exposure will be described in detail later.

[0148] From the viewpoints of coloring property and UV printing resistance of the resulting lithographic printing plate, the cyanine dye represented by the following Formula 2 is more preferable as the cyanine dye that decomposes by infrared exposure.

[0149]

Chemical formula

[0150] In Formula 2, R 1 represents a group in which the R 1 -L bond is cleaved by infrared exposure, R 2 and R 3 each independently represents a hydrogen atom or an alkyl group, R 2 and R 3 [[ID=,49]] may be linked to each other to form a ring, Ar 1 and Ar 2 each independently represents a group forming a benzene ring or a naphthalene ring, Y 1 and Y 2 each independently represents an oxygen atom, a sulfur atom, -NR 0 -, or a dialkylmethylene group, R 0 represents a hydrogen atom, an alkyl group or an aryl group, R 4 and R 5Each independently represents an aliphatic hydrocarbon group, a -CO2M group or a -PO3M2 group, M represents a hydrogen atom, a Na atom, a K atom or an onium group, and R 6 ~R 9 Each independently represents a hydrogen atom or an alkyl group, L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion that neutralizes the charge.

[0151] R 4 、R 5 The aliphatic hydrocarbon groups of R In Formula 2, R 2 ~R 9 and R 0 The alkyl groups in are preferably alkyl groups having 1 to 30 carbon atoms, more preferably alkyl groups having 1 to 15 carbon atoms, and still more preferably alkyl groups having 1 to 10 carbon atoms. The above alkyl groups may be linear, branched or have a ring structure. Specifically, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, hexadecyl group, octadecyl group, eicosyl group, isopropyl group, isobutyl group, s-butyl group, tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group, cyclopentyl group, and 2-norbornyl group can be mentioned. Among the alkyl groups, a methyl group, an ethyl group, a propyl group or a butyl group is preferred.

[0152] The above alkyl groups may have substituents. Examples of the substituents include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and a group combining these.

[0153] R 0 The aryl group in is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The above aryl group may have substituents. Examples of substituents include alkyl groups, alkoxy groups, aryloxy groups, amino groups, alkylthio groups, arylthio groups, halogen atoms, carboxyl groups, carboxylate groups, sulfo groups, sulfonate groups, alkyloxycarbonyl groups, aryloxycarbonyl groups, and groups that combine these. Specifically, examples include phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, p-fluorophenyl group, p-methoxyphenyl group, p-dimethylaminophenyl group, p-methylthiophenyl group, and p-phenylthiophenyl group. Among the aryl groups, phenyl, p-methoxyphenyl, p-dimethylaminophenyl, or naphthyl groups are preferred.

[0154] R 2 and R 3 It is preferable that they are connected to form a ring. R 2 and R 3 When the elements are linked to form a ring, a 5-membered ring or a 6-membered ring is preferred, and a 5-membered ring is particularly preferred.

[0155] Y 1 and Y 2 These are, independently, an oxygen atom, a sulfur atom, and -NR. 0 - or represents a dialkylmethylene group, -NR 0 -A dialkylmethylene group is preferred, and a dialkylmethylene group is more preferred. R 0 represents a hydrogen atom, an alkyl group, or an aryl group, with alkyl groups being preferred.

[0156] R 4 or R 5 The alkyl group represented by R may be a substituted alkyl group. 4 or R 5Examples of substituted alkyl groups represented by the following formulas (a1) to (a5) include groups represented by any of the following formulas.

[0157] [ka]

[0158] -R W6 -R W7 (a5)

[0159] In formulas (a1) to (a4), R W0 represents an alkylene group with 2 to 6 carbon atoms, W represents a single bond or oxygen atom, and n W1 represents integers from 1 to 45, and R W1 C1-C12 alkyl group or -C(=O)-R W5 Represents R W5 R represents an alkyl group with 1 to 12 carbon atoms. W2 ~R W4 , R W6 Each of these independently represents a single bond or an alkylene group with 1 to 12 carbon atoms, and M represents a hydrogen atom, a sodium atom, a potassium atom, or an onium group. R W7 This represents an aryl group. Examples of aryl groups include R 0 The aryl group is similar to that of the aryl group, and the preferred range is also similar.

[0160] In equation (a1), R W0 Specific examples of alkylene groups represented by include ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, n-pentylene group, isopentylene group, n-hexyl group, isohexyl group, etc., with ethylene group, n-propylene group, isopropylene group, and n-butylene group being preferred, and n-propylene group being particularly preferred. n W1 A value of 1 to 10 is preferred, 1 to 5 is more preferred, and 1 to 3 is particularly preferred. R W1Specific examples of alkyl groups represented by include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, n-octyl group, n-dodecyl group, etc. Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, and tert-butyl group are preferred, methyl group and ethyl group are more preferred, and methyl group is particularly preferred. R W5 The alkyl group represented by R W1 Similar to alkyl groups represented by R, a preferred embodiment is also R W1 This is similar to a preferred embodiment of the alkyl group represented by .

[0161] Specific examples of the group represented by formula (a1) are shown below, but the present invention is not limited to these. In the following structural formulas, Me represents a methyl group, Et represents an ethyl group, and * represents a bonding site.

[0162] [ka]

[0163] In equations (a2) to (a5), R W2 ~R W4 , R W6 Specific examples of alkylene groups represented by include methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, n-pentylene group, isopentylene group, n-hexyl group, isohexyl group, n-octylene group, n-dodecylene group, etc., with ethylene group, n-propylene group, isopropylene group, and n-butylene group being preferred, and ethylene group and n-propylene group being particularly preferred. In equation (a3), the two M's may be the same or different.

[0164] In formulas (a2) to (a4), the onium group represented by M can be an ammonium group, an iodonium group, a phosphonium group, a sulfonium group, or the like.

[0165] Among the groups represented by formulas (a1) to (a5), the group represented by formula (a1) or formula (a4) is preferred.

[0166] In Equation 2, R 4 and R 5 Each of these is preferably an unsubstituted alkyl group. 4 and R 5 It is preferable that they are the same group.

[0167] R 6 ~R 9 Each of these independently represents either a hydrogen atom or an alkyl group, with hydrogen atoms being preferred. Ar 1 and Ar 2 Each of these independently represents a group that forms a benzene ring or a naphthalene ring. The benzene ring and naphthalene ring may have substituents. Examples of substituents include alkyl groups, alkoxy groups, aryloxy groups, amino groups, alkylthio groups, arylthio groups, halogen atoms, carboxyl groups, carboxylate groups, sulfo groups, sulfonate groups, alkyloxycarbonyl groups, aryloxycarbonyl groups, acyloxy groups, phosphonic acid groups, and groups that combine these. Alkyl groups are preferred as substituents. Furthermore, from the viewpoint of extending the maximum absorption wavelength of the compound represented by Equation 2, and improving color development and print durability of lithographic printing plates, Ar 1 and Ar 2 Each of these groups is preferably independently a group that forms a naphthalene ring or a benzene ring having an alkyl or alkoxy group as a substituent, more preferably a group that forms a naphthalene ring or a benzene ring having an alkoxy group as a substituent, and particularly preferably a group that forms a naphthalene ring or a benzene ring having a methoxy group as a substituent.

[0168] In equation 2, Ar 1 Or Ar 2 However, it is preferable that the group forms a group represented by the following formula (b1).

[0169] [ka]

[0170] In formula (b1), R 19 * represents an alkyl group with 1 to 12 carbon atoms. n3 represents an integer from 1 to 4. * represents a bonding site.

[0171] Za represents a counterion for neutralizing the charge. However, Za is not necessary if the compound represented by formula 2 has a corresponding ionic substituent in its structure and charge neutralization is not required. When Za represents an anionic species, examples include sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, p-toluenesulfonate ions, perchlorate ions, etc., with hexafluorophosphate ions or hexafluoroantimonate ions being preferred. When Za represents a cationic species, examples include alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, or sulfonium ions, with sodium ions, potassium ions, ammonium ions, pyridinium ions, or sulfonium ions being preferred, and sodium ions, potassium ions, or ammonium ions being more preferred. R 1 ~R 9 , R 0 Ar 1 Ar 2 , Y 1 and Y 2 It may have an anionic structure or a cationic structure, R 1 ~R 9 , R 0 Ar 1 Ar 2 , Y 1 and Y 2 If all of them are charge-neutral groups, then Za is a monovalent counter anion, but for example, R 1 ~R 9 , R 0 Ar 1 Ar 2 , Y 1 and Y 2 If it has two or more anionic structures, Za can also act as a countercation.

[0172] In equations 1 and 2 above, R 1 Infrared exposure, represented by R 1 The groups that cleave the -L bond are explained below. In formula 1 or formula 2, if L is an oxygen atom, then R 1 From the viewpoint of color development, a group represented by any of the following formulas (1-1) to (1-7) is preferred, and a group represented by any of the following formulas (1-1) to (1-3) is more preferred.

[0173] [ka]

[0174] In formulas (1-1) to (1-7), ● represents the bonding site with the oxygen atom represented by L in formula 1 or formula 2, and R 20 Each of these independently consists of a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, and an -OR group. 24 , -NR 25 R 26 or -SR 27 Represents R 21 Each of these independently represents a hydrogen atom, an alkyl group, or an aryl group, and R 22 is an aryl group, -OR 24 , -NR 25 R 26 , -SR 27 -C(=O)R 28 -OC(=O)R 28 Or it represents a halogen atom, R 23 R represents an aryl group, alkenyl group, alkoxy group, or onium group. 24 ~R 27 Each of these independently represents a hydrogen atom, an alkyl group, or an aryl group, and R 28 is an alkyl group, aryl group, -OR 24 , -NR 25 R 26 or -SR 27 Represents Z 1 This represents a counterion that neutralizes the charge.

[0175] R 20, R 21 and R 24 ~R 28 A preferred embodiment when is an alkyl group is R 2 ~R 9 and R 0 This is similar to the preferred embodiment of the alkyl group in the above. R 20 and R 23 The number of carbon atoms in the alkenyl group is preferably 1 to 30, more preferably 1 to 15, and even more preferably 1 to 10. R 20 ~R 28 A preferred embodiment when is an aryl group is R 0 This is similar to the preferred embodiment of the aryl group in [the relevant context].

[0176] From the standpoint of color development, R in formula (1-1) 20 These are alkyl groups, alkenyl groups, aryl groups, and -OR groups. 24 , -NR 25 R 26 or -SR 27 Preferably, alkyl groups, -OR 24 , -NR 25 R 26 or -SR 27 More preferably, alkyl groups or -OR 24 More preferably, -OR 24 That is particularly preferable. Also, R in equation (1-1) 20 If the alkyl group is an alkyl group, the alkyl group may be an alkyl group having an arylthio group, an alkyloxycarbonyl group, or an arylsulfonyl group at the α-position, and an alkyl group having an arylthio group or an alkyloxycarbonyl group at the α-position is preferred. R in equation (1-1) 20 ga-OR 24 If R 24 The alkyl group is preferred, an alkyl group having 1 to 8 carbon atoms is more preferred, an isopropyl group or a tert-butyl group is even more preferred, and a t-butyl group is particularly preferred. R in equation (1-1) 20If the above is an alkenyl group, the alkenyl group may be an aryl group or an alkenyl group having a hydroxyaryl group.

[0177] From the standpoint of color development, R in formula (1-2) 21 A hydrogen atom is preferred. Furthermore, from the standpoint of color development, R in formula (1-2) 22 is -C(=O)OR 24 , -OC(=O)OR 24 Alternatively, a halogen atom is preferred, -C(=O)OR 24 Or -OC (=O) OR 24 This is more preferable. R in equation (1-2) 22 -C(=O)OR 24 Or -OC (=O) OR 24 If R 24 Alkyl alkyl groups are preferred.

[0178] From the standpoint of color development, R in formula (1-3) 21 Each of these is preferably a hydrogen atom or an alkyl group, and at least one R in formula (1-3) 21 Alkyl alkyl groups are more preferred. Also, R 21 The alkyl group in is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 3 to 10 carbon atoms. Furthermore, R 21 The alkyl group in is preferably a branched or cyclic alkyl group, and more preferably an isopropyl group, a cyclopentyl group, a cyclohexyl group, or a tert-butyl group. Also, R 21 The alkyl group in this is preferably a secondary or tertiary alkyl group. Furthermore, from the standpoint of color development, R in formula (1-3) 23 The group is preferably an aryl group, an alkoxy group, or an onium group, more preferably a p-dimethylaminophenyl group or a pyridinium group, and even more preferably a pyridinium group. R 23Examples of onium groups in this compound include pyridinium groups, ammonium groups, sulfonium groups, etc. The onium group may have substituents. Examples of substituents include alkyl groups, aryl groups, alkoxy groups, aryloxy groups, amino groups, alkylthio groups, arylthio groups, halogen atoms, carboxyl groups, sulfo groups, alkyloxycarbonyl groups, aryloxycarbonyl groups, and groups combining these, but alkyl groups, aryl groups, and groups combining these are preferred. Among these, pyridinium groups are preferred, including N-alkyl-3-pyridinium group, N-benzyl-3-pyridinium group, N-(alkoxypolyalkyleneoxyalkyl)-3-pyridinium group, N-alkoxycarbonylmethyl-3-pyridinium group, N-alkyl-4-pyridinium group, N-benzyl-4-pyridinium group, N-(alkoxypolyalkyleneoxyalkyl)-4-pyridinium group, and N-alkoxycarbonylmethyl-4-pyridinium A mu group or an N-alkyl-3,5-dimethyl-4-pyridinium group is more preferred, an N-alkyl-3-pyridinium group or an N-alkyl-4-pyridinium group is even more preferred, an N-methyl-3-pyridinium group, an N-octyl-3-pyridinium group, an N-methyl-4-pyridinium group or an N-octyl-4-pyridinium group is particularly preferred, and an N-octyl-3-pyridinium group or an N-octyl-4-pyridinium group is most preferred. Also, R 23 When the group is a pyridinium group, examples of counteranions include sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, p-toluenesulfonate ions, and perchlorate ions, with p-toluenesulfonate ions, hexafluorophosphate ions, or hexafluoroantimonate ions being preferred.

[0179] From the standpoint of color development, R in formula (1-4) 20 The alkyl group is preferably an alkyl group or an aryl group, and two R 20 Of these, one is more preferably an alkyl group and the other is more preferably an aryl group.20 They may be connected to form a ring. From the standpoint of color development, R in formula (1-5) 20 The group is preferably an alkyl group or an aryl group, more preferably an aryl group, and even more preferably a p-methylphenyl group. From the standpoint of color development, R in formula (1-6) 20 Each of these groups is independently preferably an alkyl group or an aryl group, and more preferably a methyl group or a phenyl group. From the perspective of color development, Z in formula (1-7) 1 This can be any counterion that neutralizes the charge, and the compound as a whole may be included in the above Za. Z 1 The preferred ions are sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, p-toluenesulfonate ions, or perchlorate ions, with p-toluenesulfonate ions, hexafluorophosphate ions, or hexafluoroantimonate ions being more preferred.

[0180] In formula 1 or formula 2, if L is an oxygen atom, more preferably, R 1 This is a group represented by the following formula (5).

[0181] [ka]

[0182] In formula (5), R 15 and R 16 Each of the following independently represents a hydrogen atom, an alkyl group, or an aryl group; E represents an onium group; and * represents a bonding site with the oxygen atom represented by L in formula 1 or formula 2.

[0183] R 15 or R 16 The alkyl group represented by R 2 ~R 9 and R 0Similar to alkyl groups in R, a preferred embodiment is also R 2 ~R 9 and R 0 This is similar to the preferred embodiment of the alkyl group in the above. R 15 or R 16 The aryl group represented by R 0 Similar to the aryl group in R, a preferred embodiment is also R 0 This is similar to the preferred embodiment of the aryl group in [the relevant context]. The onium group represented by E is R 23 Similar to the onium group in R, a preferred embodiment is also R 23 This is similar to the preferred embodiment of the onium group in [the relevant context]. In one preferred embodiment, R 15 represents a hydrogen atom, R 16 It is preferable to represent an alkyl group.

[0184] In formula (5), the onium group represented by E is preferably a pyridinium group represented by the following formula (6).

[0185] [ka]

[0186] In formula (6), R 17 R represents a halogen atom, alkyl group, aryl group, hydroxyl group, or alkoxy group. 17 If multiple R 17 The same or different Rs may be used, or multiple Rs may be used. 17 These elements may be linked together to form a ring. n² represents an integer from 0 to 4. 18 Z represents an alkyl group, aryl group, or aralkyl group. b This represents a counterion that neutralizes the charge.

[0187] R 17 or R 18 The alkyl or aryl group represented by R 2 ~R 9 and R 0 Alkyl or R in0 Similar to the aryl group in R, a preferred embodiment is also R 2 ~R 9 and R 0 Alkyl or R in 0 This is similar to the preferred embodiment of the aryl group in [the relevant context]. R 17 The alkoxy group represented by is preferably an alkoxy group having 1 to 10 carbon atoms, and examples include a methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, tert-butoxy group, etc. R 18 The aralkyl group in is preferably an aralkyl group having 7 to 31 carbon atoms, more preferably an aralkyl group having 7 to 21 carbon atoms, and even more preferably an aralkyl group having 7 to 13 carbon atoms. Specific examples of aralkyl groups include the benzyl group. The above aralkyl group may have substituents. Examples of substituents include alkyl groups, alkoxy groups, and groups that combine these. R 18 Preferably, represents an alkyl group or an aralkyl group. n2 is preferably 0. Z b The counterion for neutralizing the charge represented by is Z in equation (1-7). 1 Similarly, the preferred embodiment is Z in equation (1-7) 1 This is similar to the preferred embodiment.

[0188] In the following, when L is an oxygen atom in formula 1 or formula 2, R 1 The following are specific examples of groups represented by TsO, but the present invention is not limited to these. - represents a tosylate anion, and ● represents the bonding site with the oxygen atom represented by L in formula 1 or formula 2. Me represents methyl.

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[0199] If L is an oxygen atom, then R 1 If it is an aryl group or a linear alkyl group, then R by infrared exposure 1 -O bond cleavage does not occur.

[0200] In formula 1 or formula 2, if L is a sulfur atom, then R 1 The group is preferably represented by the following formula (2-1).

[0201] [ka]

[0202] In formula (2-1), ● represents the bonding site with the sulfur atom represented by L in formula 1 or formula 2, and R 21 Each of these independently represents a hydrogen atom, an alkyl group, or an aryl group, and R 22 The symbol represents an aryl group, alkenyl group, alkoxy group, or onium group.

[0203] In equation 1 or equation 2, L is -NR 10 -If this is the case, join R to N 1 The group is preferably represented by the following formula (3-1).

[0204] [ka]

[0205] In formula (3-1), ● represents the bonding site with the nitrogen atom contained in L in formula 1 or formula 2, and X 1 and X 2 Each of these independently represents either an oxygen atom or a sulfur atom, and Y represents the group represented by the above formula (2-1).

[0206] In the above equation (2-1), R 21 and R 22 For alkyl groups, aryl groups, alkenyl groups, alkoxy groups, and onium groups represented by the above formulas (1-1) to (1-7), the descriptions of alkyl groups, aryl groups, alkenyl groups, alkoxy groups, and onium groups described in the above formulas (1-1) to (1-7) can be applied.

[0207] In formula 1 or formula 2, L is a sulfur atom or -NR 10 - represents R 10From the viewpoint of improving print durability, it is preferable that the group represents a hydrogen atom, an alkyl group, or an aryl group.

[0208] Specific examples of compounds represented by Formula 1 or Formula 2 are shown below, but the present invention is not limited to these. In the following structural formulas, Ph represents phenyl.

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[0224] Furthermore, as chromogenic compounds, those described in Japanese Patent Publication No. 2008-544322 or International Publication No. 2016 / 027886 can be suitably used.

[0225] Compounds represented by formula 1 or formula 2 can be synthesized by applying known methods. For example, compounds represented by formula 1 or formula 2 can be synthesized by the methods described in

[0109] to

[0113] of Japanese Patent Application Publication No. 2020-69789.

[0226] The color-developing compounds may be used individually or in combination of two or more. The content of the color-developing compound in the image recording layer is preferably 0.1% to 95% by mass, more preferably 0.5% to 40% by mass, and even more preferably 1% to 20% by mass, based on the total solid content of the image recording layer.

[0227] Since chromogenic compounds themselves possess excellent infrared absorption properties, they function well as infrared absorbers. Therefore, when chromogenic compounds are used in the image recording layer of a lithographic printing plate, it is practically unnecessary to use other infrared absorbers besides the chromogenic compound; however, the image recording layer may contain other infrared absorbers.

[0228] [Polymerization initiator] Polymerization initiators are compounds that generate polymerization initiating species such as radicals or cations in response to light, heat, or both of these energies. They can be appropriately selected and used from known thermal polymerization initiators, compounds with bonds having low bond dissociation energy, photopolymerization initiators, and the like. Infrared photosensitive polymerization initiators are preferred as polymerization initiators. Radical polymerization initiators are also preferred as polymerization initiators. Two or more radical polymerization initiators may be used in combination.

[0229] The radical polymerization initiator may be either an electron-accepting polymerization initiator or an electron-donating polymerization initiator.

[0230] <Electron-accepting polymerization initiator> Examples of electron-accepting polymerization initiators include organic halides, carbonyl compounds, azo compounds, organic peroxides, metallocene compounds, azide compounds, hexaarylbiimidazole compounds, disulfone compounds, oxime ester compounds, and onium salt compounds.

[0231] As for organic halides, for example, the compounds described in paragraphs 0022 to 0023 of Japanese Patent Publication No. 2008-195018 are preferred. As a carbonyl compound, for example, the compound described in paragraph 0024 of Japanese Patent Publication No. 2008-195018 is preferred. Examples of azo compounds include the azo compounds described in Japanese Patent Publication No. 8-108621. As an organic peroxide, for example, the compound described in paragraph 0025 of Japanese Patent Publication No. 2008-195018 is preferred. As a metallocene compound, for example, the compound described in paragraph 0026 of Japanese Patent Publication No. 2008-195018 is preferred. Examples of azide compounds include 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone. As a hexaarylbiimidazole compound, for example, the compound described in paragraph 0027 of Japanese Patent Publication No. 2008-195018 is preferred. Examples of disulfone compounds include those described in Japanese Patent Publication No. 61-166544 and Japanese Patent Publication No. 2002-328465. As oxime ester compounds, for example, the compounds described in paragraphs 0028 to 0030 of Japanese Patent Publication No. 2008-195018 are preferred.

[0232] Among electron-accepting polymerization initiators, onium salt compounds such as iodonium salts, sulfonium salts, and azinium salts are more preferred. Iodonium salts and sulfonium salts are particularly preferred. Specific examples of iodonium salts and sulfonium salts are shown below, but the present invention is not limited to these.

[0233] Electron-accepting polymerization initiators may be used alone or in combination of two or more. From the viewpoint of color development during exposure, fade resistance during white light exposure, print resistance, and coating stability, the content of the electron-accepting polymerization initiator is preferably 0.1 to 30% by mass, more preferably 0.1 to 20% by mass, and even more preferably 0.5 to 15% by mass, of the total solid content of the image recording layer.

[0234] <Electron-donating polymerization initiator> Electron-donating polymerization initiators contribute to improving the print resistance of lithographic printing plates produced from lithographic printing plates. Examples of electron-donating polymerization initiators include the following five types: (i) Alkyl or arylate complexes: These are thought to oxidatively break the carbon-heterobond and generate active radicals. Specifically, borate compounds are examples of such complexes. (ii) Aminoacetic acid compounds: It is thought that oxidation causes the CX bond on the carbon adjacent to the nitrogen to break, generating an active radical. X is preferably a hydrogen atom, a carboxyl group, a trimethylsilyl group, or a benzyl group. Specifically, examples include N-phenylglycines (which may have substituents on the phenyl group) and N-phenyliminodiacetic acid (which may have substituents on the phenyl group). (iii) Sulfur-containing compounds: Compounds obtained by replacing the nitrogen atom of the above-mentioned aminoacetic acid compounds with a sulfur atom can generate active radicals through a similar mechanism. Specifically, examples include phenylthioacetic acid (which may have substituents on the phenyl group). (iv) Tin-containing compounds: Compounds obtained by replacing the nitrogen atom of the above-mentioned aminoacetic acid compound with a tin atom can generate active radicals through a similar mechanism. (v) Sulfinates: These can generate active radicals upon oxidation. Examples include sodium arylsulfinates.

[0235] Among electron-donating polymerization initiators, borate compounds are preferred. Tetraarylborate compounds or monoalkyltriarylborate compounds are preferred as borate compounds, and tetraarylborate compounds are more preferred from the viewpoint of compound stability. The countercations of the borate compound are preferably alkali metal ions or tetraalkylammonium ions, and more preferably sodium ions, potassium ions, or tetrabutylammonium ions. The polymerization initiator preferably contains oyster shell and a compound as an electron-donating polymerization initiator.

[0236] Specific examples of borate compounds include the following compounds. Here, X c + represents a monovalent cation, preferably an alkali metal ion or a tetraalkylammonium ion, and more preferably an alkali metal ion or a tetrabutylammonium ion. Also, Bu represents an n-butyl group.

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[0241] Electron-donating polymerization initiators may be used alone or in combination of two or more. From the viewpoint of color development during exposure, print resistance, and coating solution stability, the content of the electron-donating polymerization initiator is preferably 0.1 to 20% by mass, more preferably 0.3 to 15% by mass, and even more preferably 0.5 to 10% by mass, of the total solid content of the image recording layer.

[0242] [Polymerizable compound] The polymerizable compound may be, for example, a radical polymerizable compound or a cationic polymerizable compound, but it is preferably an addition polymerizable compound (ethylenically unsaturated compound) having at least one ethylenically unsaturated bond. As the ethylenically unsaturated compound, a compound having at least one terminal ethylenically unsaturated bond is preferred, and a compound having two or more terminal ethylenically unsaturated bonds is more preferred. The polymerizable compound can have chemical forms such as monomers, prepolymers, i.e., dimers, trimers, or oligomers, or mixtures thereof.

[0243] From the viewpoint of print resistance, polymerizable compounds are preferably 5-functional or more, more preferably 7-functional or more, and even more preferably 11-functional or more. "Functionality" refers to groups that contribute to polymerization (functional groups), and ethylenically unsaturated bonds are preferred. For example, "4-functional or more" indicates that the number of groups that contribute to polymerization is 4 or more. Polymerizable compounds are not particularly limited, but typically have 20 or fewer functionalities. From the viewpoint of print resistance, the polymerizable compound is preferably an ethylenically unsaturated compound with 5 or more functions, more preferably an ethylenically unsaturated compound with 7 or more functions, and even more preferably an ethylenically unsaturated compound with 11 or more functions.

[0244] The molecular weight of the polymerizable compound (or weight-average molecular weight if it has a molecular weight distribution) is not particularly limited, but from the viewpoint of on-press developmentability, a smaller molecular weight is preferable, and from the viewpoint of print durability, a larger molecular weight is preferable. The molecular weight is preferably less than 15,000. Furthermore, a molecular weight of 100 or more is preferable. From the viewpoint of achieving both on-press developability and print durability, the molecular weight is preferably 100 or more and less than 15,000, more preferably 500 or more and less than 13,000, and even more preferably 1,000 or more and less than 10,000. In one preferred embodiment, the image recording layer preferably contains a polymerizable compound that has 7 or more functional properties and a molecular weight of less than 15,000. In one preferred embodiment, the image recording layer preferably contains a polymerizable compound having 11 or more functions and a molecular weight of less than 15,000.

[0245] Examples of monomers include unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid), their esters, and amides. Preferably, esters of unsaturated carboxylic acids and polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and polyhydric amine compounds are used. Addition reaction products of unsaturated carboxylic acid esters or amides having nucleophilic substituents such as hydroxyl groups, amino groups, and mercapto groups with monofunctional or polyfunctional isocyanates or epoxys, and dehydration condensation reaction products with monofunctional or polyfunctional carboxylic acids are also suitably used. Addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituents such as isocyanate groups and epoxy groups with monofunctional or polyfunctional alcohols, amines, and thiols, and substitution reaction products of unsaturated carboxylic acid esters or amides having leaving substituents such as halogen atoms and tosyloxy groups with monofunctional or polyfunctional alcohols, amines, and thiols are also suitable. As another example, compounds can also be used in which the above-mentioned unsaturated carboxylic acids are replaced with unsaturated phosphonic acids, styrene, vinyl ethers, etc. These compounds are described in Japanese Patent Publication No. 2006-508380, Japanese Patent Publication No. 2002-287344, Japanese Patent Publication No. 2008-256850, Japanese Patent Publication No. 2001-342222, Japanese Patent Publication No. 9-179296, Japanese Patent Publication No. 9-179297, Japanese Patent Publication No. 9-179298, Japanese Patent Publication No. 2004-294935, Japanese Patent Publication No. 2006-243493, Japanese Patent Publication No. 2002-275129, Japanese Patent Publication No. 2003-64130, Japanese Patent Publication No. 2003-280187, Japanese Patent Publication No. 10-333321, and others.

[0246] Specific examples of monomers that are esters of polyhydric alcohol compounds and unsaturated carboxylic acids include, as acrylic acid esters, ethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, isocyanurate ethylene oxide (EO) modified triacrylate, and polyester acrylate oligomers. Examples of methacrylic acid esters include tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis[p-(3-methacrylateoxy-2-hydroxypropoxy)phenyl]dimethylmethane, and bis[p-(methacrylateoxyethoxy)phenyl]dimethylmethane. Furthermore, specific examples of monomers of amides formed from polyhydric amine compounds and unsaturated carboxylic acids include methylenebisacrylamide, methylenebismethacrylamide, 1,6-hexamethylenebisacrylamide, 1,6-hexamethylenebismethacrylamide, diethylenetriaminetrisacrylamide, xylylenebisacrylamide, and xylylenebismethacrylamide.

[0247] Furthermore, urethane-based addition polymerizable compounds produced by the addition reaction of isocyanates and hydroxyl groups are also suitable. Specific examples include, for instance, a vinyl urethane compound containing two or more polymerizable vinyl groups per molecule, obtained by adding a vinyl monomer containing a hydroxyl group represented by the following formula (M) to a polyisocyanate compound having two or more isocyanate groups per molecule, as described in Japanese Patent Publication No. 48-41708. CH2=C(R M4 )COOCH2CH(R M5 )OH (M) In formula (M), R M4 and R M5Each of these independently represents either a hydrogen atom or a methyl group.

[0248] Furthermore, urethane acrylates described in Japanese Patent Publication No. 51-37193, Japanese Patent Publication No. 2-32293, Japanese Patent Publication No. 2-16765, Japanese Patent Publication No. 2003-344997, Japanese Patent Publication No. 2006-65210, Japanese Patent Publication No. 58-49860, Japanese Patent Publication No. 56-17654, Japanese Patent Publication No. 62-39417, Japanese Patent Publication No. 62-39418 Urethane compounds having an ethylene oxide-based skeleton as described in Japanese Patent Publication No. 2000-250211 and Japanese Patent Publication No. 2007-94138, as well as urethane compounds having hydrophilic groups as described in U.S. Patent No. 7,153,632, Japanese Patent Publication No. Hei 8-505958, Japanese Patent Publication No. 2007-293221 and Japanese Patent Publication No. 2007-293223, are also suitable.

[0249] The structure of polymerizable compounds, whether they are used alone or in combination, and the amount added, as well as other details of their usage, can be arbitrarily determined, taking into consideration the final use of the lithographic printing plates. The polymerizable compound content is preferably 1 to 90% by mass, more preferably 5 to 70% by mass, and even more preferably 10 to 50% by mass, of the total solid content of the image recording layer.

[0250] Other optional compounds include the hydrogen-donating compounds described below. [Hydrogen-donating compounds] Hydrogen-donating compounds are compounds distinct from polymerization initiators, polymerizable compounds, chromogenic compounds, and acid-cleaving compounds. They have at least one group selected from the group consisting of -OH, -NH-, -SO2-NH-, -SO2-OH, -CO-NH-, and -CO-OH in their molecule, and have a molecular weight of less than 3,000.

[0251] Groups selected from the group consisting of -OH, -NH-, -SO2-NH-, -SO2-OH, -CO-NH-, and -CO-OH (hereinafter also simply referred to as "hydrogen-donating groups") are groups that can donate hydrogen atoms. "-OH" represents a hydroxyl group, which is different from "-CO-OH" (carboxyl group), and it is a group that does not bond with "-SO2-". The "-NH-" group does not bond with "-SO2-" or "-CO-".

[0252] "Compounds different from polymerization initiators, polymerizable compounds, chromogenic compounds, and acid-cleaving compounds" means that even if a compound has the hydrogen-donating group described above and has a molecular weight of less than 3,000, if it functions as a polymerization initiator, polymerizable compound, chromogenic compound, or acid-cleaving compound, it is not included in the category of hydrogen-donating compounds. The polymerization initiator, polymerizable compound, and chromogenic compound are as described above.

[0253] Acid-cleaved compounds are compounds that are cleaved by the action of an acid, specifically indicating that an intramolecular ring is cleaved (ring-opening) by the action of an acid. So-called acid-developing agents, which develop color by cleaving in response to the action of an acid, are included in the category of acid-cleaved compounds. Hydrogen-donating compounds are compounds that are different from acid-developing agents.

[0254] Hydrogen-donating compounds are preferably compounds that have at least one substructure represented by the following formula (I) within their molecule.

[0255] [ka]

[0256] In formula (I), X is a group selected from the group consisting of -OH, -NH-, -SO2-NH-, -SO2-OH, -CO-NH-, and -CO-OH. R 1A ~R 3A Each of these groups independently has at least one atom selected from the group consisting of hydrogen atoms, carbon atoms, halogen atoms, and heteroatoms. R 1A ~R 3A At least two of these may be linked together to form a ring. If X is a monovalent base, R 1A ~R 3A One or more hydrogen atoms are removed to form a bonding bond. If X is a divalent group, R 1A ~R 3A One or more hydrogen atoms contained in it may be further removed to form a bonding bond.

[0257] As for the hydrogen-donating group of X, -OH, -NH-, -SO2-NH-, or -CO-NH- are preferred from the viewpoint of suppressing fading when exposed to white light and being easily absorbed into the image recording layer, and -OH or -SO2-NH- are more preferred.

[0258] R 1A ~R 3A The group having at least one atom selected from the group consisting of hydrogen atoms, carbon atoms, halogen atoms, and heteroatoms (hereinafter also referred to as "substituent A") is not particularly limited, but it is preferably a group having 0 to 30 carbon atoms. While not particularly limited, examples of halogen atoms include fluorine, chlorine, bromine, or iodine atoms. The heteroatoms are not particularly limited, but examples include nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, and so on. The substituent A is not particularly limited, but for example, a hydrogen atom or a hydrocarbon group is preferred. The hydrocarbon group may also have a heteroatom or a halogen atom.

[0259] R 1A ~R 3A At least two of these may be linked to form a ring. The formed ring may be a monocyclic or polycyclic ring. Examples of the formed ring include aromatic rings and aliphatic hydrocarbon rings, and the number of ring member atoms in the formed ring is preferably 6 to 14. If X is a monovalent group (specifically, a group selected from the group consisting of -OH, -SO2-OH, and -CO-OH), then R 1A ~R 3A One or more hydrogen atoms are removed to form a bonding bond. When X is a divalent group (specifically, a group selected from the group consisting of -NH-, -SO2-NH-, and -CO-NH-), it can form a substructure in formula (I), but R 1A ~R 3A It is also possible that one or more hydrogen atoms contained in it have been further removed to form a bonding bond.

[0260] The hydrogen-donating compound is preferably a compound having at least one substructure represented by formula (I) in its molecule, and may also be a compound having at least two or more substructures represented by formula (I) in its molecule. The number of substructures represented by formula (I) within the molecule is not particularly limited, but it is preferably 1 to 10, and more preferably 1 to 5.

[0261] The hydrogen-donating compound is preferably a compound having at least one substructure represented by the following formula (II) within its molecule.

[0262] [ka]

[0263] In formula (II), Ar represents an aromatic ring group. X is a group selected from the group consisting of -OH, -NH-, -SO2-NH-, -SO2-OH, -CO-NH-, and -CO-OH. R 4A This is a group having at least one selected from the group consisting of hydrogen atoms, carbon atoms, halogen atoms, and heteroatoms. m represents an integer from 1 to 5. If m represents an integer greater than or equal to 2, the multiple X values ​​may be the same or different. n represents an integer from 0 to 5. If n represents an integer greater than or equal to 2, multiple R 4A They may be the same or different. If n is 2 or more, multiple R 4A They may be linked together to form a ring. If all X are monovalent bases, then R4A One or more hydrogen atoms are removed to form a bonding bond. If at least one X is a divalent group, R 4A It is also possible that one or more hydrogen atoms contained in it have been further removed to form a bonding bond.

[0264] X is synonymous with X in equation (I), and the preferred range is also the same. Examples of aromatic rings in the aromatic ring group of Ar include aromatic hydrocarbon rings or aromatic heterocycles. The aromatic hydrocarbon ring may be monocyclic or polycyclic. The number of ring member atoms is preferably 6 to 15, and more preferably 6 to 10. Examples of aromatic hydrocarbon rings include benzene rings, naphthalene rings, and anthracene rings. Among these, benzene rings or naphthalene rings are preferred, and benzene rings are more preferred.

[0265] The aromatic heterocycle may be monocyclic or polycyclic. The number of ring member atoms is preferably 5 to 15. Examples of heterocycles that possess aromaticity include furan rings, thiophene rings, benzofuran rings, benzothiophene rings, dibenzofuran rings, dibenzothiophene rings, pyridine rings, indole rings, benzodiazole rings, and carbazole rings.

[0266] R 4A The group having at least one atom selected from the group consisting of hydrogen atoms, carbon atoms, halogen atoms, and heteroatoms (hereinafter also referred to as "substituent A1") is not particularly limited, but it is preferably a group having 0 to 24 carbon atoms. While not particularly limited, examples of halogen atoms include fluorine, chlorine, bromine, or iodine atoms. The heteroatoms are not particularly limited, but examples include nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, and so on. The substituent A1 is not particularly limited, but a hydrogen atom or a hydrocarbon group is preferred, for example. The hydrocarbon group may have a heteroatom or a halogen atom.

[0267] m represents an integer between 1 and 5. Preferably, m represents an integer between 1 and 3, and more preferably, an integer between 1 and 2. n represents an integer between 0 and 5. Preferably, n represents an integer between 0 and 2, and more preferably, an integer between 0 and 1.

[0268] If n is 2 or greater, multiple R 4A They may be linked together to form a ring. Multiple R 4A However, the ring formed by linking may be a monocyclic or polycyclic ring. Examples of the formed rings include aromatic rings and aliphatic hydrocarbon rings, and the number of ring member atoms in the formed ring is preferably 6 to 10.

[0269] If X is a monovalent group (specifically, a group selected from the group consisting of -OH, -SO2-OH, and -CO-OH), then R 4A One or more hydrogen atoms are removed to form a bonding bond. When X is a divalent group (specifically, a group selected from the group consisting of -NH-, -SO2-NH-, and -CO-NH-), it can form a substructure in formula (I), but R 4A It is also possible that one or more hydrogen atoms contained in it have been further removed to form a bonding bond.

[0270] The hydrogen-donating compound is preferably a compound having at least one substructure represented by formula (II) in its molecule, but it may also be a compound having at least two or more substructures represented by formula (II) in its molecule. The number of substructures represented by formula (I) within the molecule is not particularly limited, but it is preferably 1 to 5, and more preferably 1 to 3.

[0271] Hydrogen-donating compounds are preferably compounds that have at least one substructure represented by the following formula (III) within their molecule.

[0272] [ka]

[0273] In formula (III), X is a group selected from the group consisting of -OH, -NH-, -SO2-NH-, -SO2-OH, -CO-NH-, and -CO-OH. R 5A This is a group having at least one selected from the group consisting of hydrogen atoms, carbon atoms, halogen atoms, and heteroatoms. p represents an integer between 1 and 5. If p represents an integer greater than or equal to 2, the multiple X values ​​may be the same or different. q represents an integer from 0 to 5. If q represents an integer of 2 or more, multiple R5s may be the same or different. If q is 2 or more, multiple R 5A They may be linked together to form a ring. p+q is less than or equal to 6. If all X are monovalent bases, then R 5A One or more hydrogen atoms are removed to form a bonding bond. If at least one X is a divalent group, R 5A It is also possible that one or more hydrogen atoms contained in it have been further removed to form a bonding bond.

[0274] X is synonymous with X in equation (I), and the preferred range is also the same. R 5A The substituent A2, which has at least one atom selected from the group consisting of hydrogen atoms, carbon atoms, halogen atoms, and heteroatoms, is not particularly limited, but it is preferably a group having 0 to 24 carbon atoms. While not particularly limited, examples of halogen atoms include fluorine, chlorine, bromine, or iodine atoms. The heteroatoms are not particularly limited, but examples include nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, and so on. The substituent A2 is not particularly limited, but a hydrogen atom or a hydrocarbon group is preferred, for example. The hydrocarbon group may have a heteroatom or a halogen atom.

[0275] p represents an integer between 1 and 5. Preferably, p represents an integer between 1 and 3, and more preferably, an integer between 1 and 2. q represents an integer between 0 and 5. Preferably, q represents an integer between 0 and 2, and more preferably, an integer between 0 and 1.

[0276] If q is 2 or greater, multiple R 5A They may be linked together to form a ring. Multiple R 5A However, the ring formed by linking may be a monocyclic or polycyclic ring. Examples of the formed rings include aromatic rings and aliphatic hydrocarbon rings, and the number of ring member atoms in the formed ring is preferably 6 to 10.

[0277] In hydrogen-donating compounds, the hydrogen-donating group is preferably selected from the group consisting of -OH, -NH-, -SO2-NH-, and -CO-NH-, and more preferably selected from the group consisting of -OH and -SO2-NH-, from the viewpoint of suppressing discoloration when exposed to white light and being easily compatible with the image recording layer. From the viewpoint of suppressing discoloration when exposed to white light, the hydrogen-donating compound preferably contains at least one of the above-mentioned hydrogen-donating groups, more preferably at least two, and even more preferably at least three. The number of hydrogen-donating groups in the hydrogen-donating compound is not particularly limited, but is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less.

[0278] In one preferred embodiment, the hydrogen-donating compound is preferably a compound having at least two groups selected from the group consisting of -OH, -NH-, -SO2-NH-, -SO2-OH, -CO-NH-, and -CO-OH in its molecule. In one preferred embodiment, the hydrogen-donating compound preferably has at least one group selected from the group consisting of -OH and -SO2-NH-. In one preferred embodiment, the hydrogen-donating compound preferably has at least two groups selected from the group consisting of -OH and -SO2-NH-.

[0279] The hydrogen-donating compound preferably has at least one phenolic hydroxyl group. A phenolic hydroxyl group refers to a hydroxyl group (-OH) directly attached to an aromatic ring (specifically, a benzene ring). Hydrogen-donating compounds preferably have two or more phenolic hydroxyl groups. The hydrogen-donating compound preferably has two to six phenolic hydroxyl groups, and more preferably two to four phenolic hydroxyl groups. "Having two or more phenolic hydroxyl groups" means that an aromatic ring bonded to one phenolic hydroxyl group may have one or more additional phenolic hydroxyl groups bonded to it, and an aromatic ring different from the one bonded to one phenolic hydroxyl group may have one or more additional phenolic hydroxyl groups bonded to it.

[0280] The hydrogen-donating compound is preferably a compound represented by the following formula (IV) or a compound represented by the following formula (V).

[0281] [ka]

[0282] In equation (IV), X A This represents -OH. R 6A This represents an organic group or a halogen atom. r represents an integer between 1 and 5. s represents an integer from 0 to 5. If s represents an integer greater than or equal to 2, multiple R 6A They may be the same or different. If s is 2 or more, there may be multiple R 6AThey may be linked together to form a ring. In equation (V), L represents a single bond or a divalent linking group. X B This represents -OH. R 7A This represents an organic group or a halogen atom. X c This represents -OH. R 8A This represents an organic group or a halogen atom. t represents an integer between 1 and 5. u represents an integer from 0 to 5. If u represents an integer greater than or equal to 2, multiple Rs are used. 7A They may be the same or different. If u is 2 or more, multiple R 7A They may be linked together to form a ring. v represents an integer between 1 and 5. w represents an integer from 0 to 5. If w represents an integer greater than or equal to 2, multiple Rs are used. 8A They may be the same or different. If w is 2 or more, there may be multiple R 8A They may be linked together to form a ring.

[0283] R 6A , R 7A , R 8A The organic group is not particularly limited, but examples include alkyl groups and aryl groups. The alkyl group may be linear or branched, and examples include alkyl groups having 1 to 10 carbon atoms. The aryl group may be monocyclic or polycyclic, and examples include aryl groups having 6 to 20 carbon atoms. R 6A , R 7A , R 8A The halogen atom is not particularly limited, but examples include a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0284] r represents an integer between 1 and 5. Preferably, r represents an integer between 1 and 3, and more preferably, r represents 1 or 2. s represents an integer between 0 and 5. Preferably, s represents an integer between 0 and 3, and more preferably, s represents 0 or 1. It is preferable that r+s is 6 or less. Multiple R 6A However, the ring formed by linking may be a monocyclic or polycyclic ring. Examples of the ring that can be formed include an aliphatic hydrocarbon ring, and the number of ring member atoms in the formed ring is preferably 6 to 10.

[0285] The divalent linking group of L is not particularly limited, but examples include alkylene groups, -CO-, -SO2-, -O-, or combinations thereof. Examples of alkylene groups include linear or branched alkylene groups having 1 to 5 carbon atoms. The alkylene group may have further substituents. The substituents are not particularly limited, but examples include aryl groups (preferably with 6 to 10 carbon atoms). The aryl group may have further substituents, and examples of further substituents include hydroxyl groups.

[0286] t represents an integer between 1 and 5. Preferably, t represents an integer between 1 and 3, and more preferably, t represents 1 or 2. u represents an integer between 0 and 5. Preferably, u represents an integer between 0 and 3, and more preferably 0 or 1. It is preferable that t+u is 6 or less. Multiple R 7A However, the ring formed by linking may be a monocyclic or polycyclic ring. Examples of the ring that can be formed include an aliphatic hydrocarbon ring, and the number of ring member atoms in the formed ring is preferably 6 to 10.

[0287] v represents an integer between 1 and 5. Preferably, v represents an integer between 1 and 3, and more preferably, 1 or 2. w represents an integer between 0 and 5. Preferably, w represents an integer between 0 and 3, and more preferably, 0 or 1. It is preferable that v+w is 6 or less. Multiple R 8A However, the ring formed by linking may be a monocyclic or polycyclic ring. Examples of the ring that can be formed include an aliphatic hydrocarbon ring, and the number of ring member atoms in the formed ring is preferably 6 to 10.

[0288] The hydrogen-donating compound is a low-molecular-weight compound with a molecular weight of less than 3,000, preferably 1,500 or less, and more preferably 1,000 or less. Here, the low molecular weight compound in the present invention is not a polymer or oligomer obtained by cleaving the unsaturated bonds of a compound having unsaturated bonds (a so-called polymerizable monomer) using an initiator and growing the bonds in a chain reaction, but rather a compound having a constant molecular weight of 3000 or less (more preferably 2000 or less, and even more preferably 1000 or less) (a compound that substantially does not have a molecular weight distribution).

[0289] The molecular weight of the hydrogen-donating compound is not particularly limited, but is preferably 50 or more, preferably 100 or more, and more preferably 200 or more. In one preferred embodiment, from the viewpoint of on-press developability and print durability, the molecular weight is preferably 50 to 3000, more preferably 100 to 1500, and even more preferably 200 to 1000.

[0290] Specific examples of hydrogen-donating compounds are shown below, but the present invention is not limited to these.

[0291] [ka]

[0292] [ka]

[0293] [ka]

[0294] Hydrogen-donating compounds may be used individually or in combination of two or more. The hydrogen-donating compound content is preferably 0.5 to 30% by mass, more preferably 1 to 20% by mass, and even more preferably 1 to 10% by mass, of the total solid content of the image recording layer.

[0295] In an on-press type lithographic printing plate, the image recording layer may contain other infrared absorbers, acid colorants, polymer compounds, chain transfer agents, low molecular weight hydrophilic compounds, oil-sensitive agents, and other components in addition to the above-mentioned color-developing compounds.

[0296] [Other infrared absorbers] The image recording layer described above may also contain infrared absorbers other than chromogenic compounds. Other infrared absorbers include pigments and dyes. Other dyes that can be used as infrared absorbers include commercially available dyes and known dyes listed in literature such as the "Dye Handbook" (edited by the Society of Synthetic Organic Chemistry, published in 1970). Specifically, examples include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methine dyes, cyanine dyes, squarylium dyes, pyryllium salts, and metal thiolate complexes. Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyryllium salts, nickel thiolate complexes, and indorenine-cyanine dyes. Furthermore, cyanine dyes and indorenine-cyanine dyes are also preferred. Of these, cyanine dyes are particularly preferred.

[0297] Specific examples of cyanine dyes include the compounds described in paragraphs 0017 to 0019 of Japanese Patent Publication No. 2001-133969, the compounds described in paragraphs 0016 to 0021 of Japanese Patent Publication No. 2002-023360, the compounds described in paragraphs 0012 to 0037 of Japanese Patent Publication No. 2002-040638, preferably the compounds described in paragraphs 0034 to 0041 of Japanese Patent Publication No. 2002-278057, the compounds described in paragraphs 0080 to 0086 of Japanese Patent Publication No. 2008-195018, particularly preferably the compounds described in paragraphs 0035 to 0043 of Japanese Patent Publication No. 2007-90850, and the compounds described in paragraphs 0105 to 0113 of Japanese Patent Publication No. 2012-206495. Furthermore, the compounds described in paragraphs 0008 to 0009 of Japanese Patent Publication No. 5-5005 and paragraphs 0022 to 0025 of Japanese Patent Publication No. 2001-222101 can also be preferably used. As pigments, compounds described in paragraphs 0072 to 0076 of Japanese Patent Publication No. 2008-195018 are preferred.

[0298] Other infrared absorbers may be used individually or in combination of two or more. Furthermore, pigments and dyes may be used in combination as other infrared absorbers. The content of other infrared absorbers in the image recording layer is preferably less than the content of the color-developing compound, from the viewpoint of color development and UV resistance of the resulting lithographic printing plate, and it is more preferable that the image recording layer does not contain any other infrared absorbers.

[0299] The image recording layer preferably contains an acid colorant in addition to the color-developing compound having a group that cleaves upon infrared exposure.

[0300] [Acid coloring agent] In this invention, "acid colorant" refers to a compound that changes the color of an image recording layer by developing or decolorizing when heated while accepting an electron-accepting compound (e.g., a proton such as an acid). As an acid colorant, a colorless compound having a partial skeleton such as a lactone, lactam, salton, spiropyran, ester, or amide is particularly preferred, in which these partial skeletons rapidly open or cleave when in contact with an electron-accepting compound.

[0301] Specific examples of acid colorants include those described in International Publication No. 2020 / 158138.

[0302] In particular, the acid colorant used in the present invention is preferably at least one compound selected from the group consisting of spiropyran compounds, spirooxazine compounds, spirolactone compounds, and spirolactam compounds, from the viewpoint of color development. From the viewpoint of visibility, the hue of the pigment after color development is preferably green, blue, or black.

[0303] Furthermore, the above-mentioned acid colorant preferably contains a leuco dye from the viewpoint of color development and visibility. The above-mentioned leuco dye is not particularly limited as long as it has a leuco structure, but it is preferable that it has a spiro structure, and more preferably that it has a spirolactone ring structure. Furthermore, from the viewpoint of color development and visibility of the exposed area, the leuco dye is preferably a leuco dye having a phthalide structure or a fluorane structure. Furthermore, the leuco dye having the phthalide structure or fluorane structure described above is preferably a compound represented by any of the following formulas (Le-1) to (Le-3), and more preferably a compound represented by the following formula (Le-2), from the viewpoint of color development and visibility of the exposed area.

[0304] [ka]

[0305] In formulas (Le-1) to (Le-3), ERG each independently represents an electron-donating group, X1 to X4 each independently represents a hydrogen atom, a halogen atom, or a dialkylanilino group, and X5 to X 10 Each of the following independently represents a hydrogen atom, a halogen atom, or a monovalent organic group; Y1 and Y2 independently represent C or N; if Y1 is N, X1 is absent; if Y2 is N, X4 is absent; Ra1 represents a hydrogen atom, an alkyl group, or an alkoxy group; and Rb1 to Rb4 independently represent a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0306] In the ERG of formulas (Le-1) to (Le-3), the electron-donating group is preferably an amino group, alkylamino group, arylamino group, heteroarylamino group, dialkylamino group, monoalkylmonoarylamino group, monoalkylmonoheteroarylamino group, diarylamino group, diheteroarylamino group, monoarylmonoheteroarylamino group, alkoxy group, allyloxy group, heteroaryloxy group, or alkyl group, more preferably an amino group, alkylamino group, arylamino group, heteroarylamino group, dialkylamino group, monoalkylmonoarylamino group, monoalkylmonoheteroarylamino group, diarylamino group, diheteroarylamino group, monoarylmonoheteroarylamino group, alkoxy group, or allyloxy group, even more preferably a monoalkylmonoarylamino group, diarylamino group, diheteroarylamino group, or monoarylmonoheteroarylamino group, and particularly preferably a monoalkylmonoarylamino group. Furthermore, as the electron-donating group in the above ERG, from the viewpoint of color development and visibility of the exposed area, it is preferable that the disubstituted amino group has an aryl group having a substituent at least one ortho position or a heteroaryl group having a substituent at least one ortho position, more preferably that the disubstituted amino group has a substituent at least one ortho position and a phenyl group having an electron-donating group at the para position, even more preferably that the amino group has a substituent at least one ortho position and a phenyl group having an electron-donating group at the para position and an aryl group or heteroaryl group, and particularly preferably that the amino group has a substituent at least one ortho position and a phenyl group having an electron-donating group at the para position and an aryl group having an electron-donating group or a heteroaryl group having an electron-donating group. In this invention, the ortho position in an aryl group or heteroaryl group other than a phenyl group refers to the bond position adjacent to position 1 (for example, position 2) when the bond position to another structure of the aryl group or heteroaryl group is defined as position 1. Furthermore, from the viewpoint of color development and visibility of the exposed area, the electron-donating group of the aryl group or heteroaryl group is preferably an amino group, alkylamino group, arylamino group, heteroarylamino group, dialkylamino group, monoalkylmonoarylamino group, monoalkylmonoheteroarylamino group, diarylamino group, diheteroarylamino group, monoarylmonoheteroarylamino group, alkoxy group, allyloxy group, heteroaryloxy group, or alkyl group, more preferably an alkoxy group, allyloxy group, heteroaryloxy group, or alkyl group, and particularly preferably an alkoxy group.

[0307] In formulas (Le-1) to (Le-3), X1 to X4 are each independently preferably hydrogen atoms or chlorine atoms, and more preferably hydrogen atoms, from the viewpoint of color development and visibility of the exposed area. X5~X in equation (Le-2) or equation (Le-3) 10Each of these groups is preferably, from the viewpoint of color development and visibility of the exposed area, a hydrogen atom, halogen atom, alkyl group, aryl group, amino group, alkylamino group, arylamino group, heteroarylamino group, dialkylamino group, monoalkylmonoarylamino group, monoalkylmonoheteroarylamino group, diarylamino group, diheteroarylamino group, monoarylmonoheteroarylamino group, hydroxyl group, alkoxy group, allyloxy group, heteroallyloxy group, acyl group, alkoxycarbonyl group, allyloxycarbonyl group, heteroallyloxycarbonyl group, or cyano group; more preferably a hydrogen atom, halogen atom, alkyl group, aryl group, alkoxy group, or allyloxy group; even more preferably a hydrogen atom, halogen atom, alkyl group, or aryl group; and particularly preferably a hydrogen atom. In formulas (Le-1) to (Le-3), at least one of Y1 and Y2 is preferably C, and more preferably both Y1 and Y2 are C, from the viewpoint of color development and visibility of the exposed area. In formulas (Le-1) to (Le-3), Ra1 is preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group, from the viewpoint of color development and visibility of the exposed area. In formulas (Le-1) to (Le-3), Rb1 to Rb4 are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group, from the viewpoint of color development and visibility of the exposed area.

[0308] Furthermore, the leuco dye having the phthalide structure or fluorane structure described above is more preferably a compound represented by any of the following formulas (Le-4) to (Le-6), and even more preferably a compound represented by the following formula (Le-5), from the viewpoint of color development and visibility of the exposed area.

[0309] [ka]

[0310] In formulas (Le-4) to (Le-6), ERG independently represents an electron-donating group, X1 to X4 independently represent a hydrogen atom, a halogen atom, or a dialkylanilino group, Y1 and Y2 independently represent C or N, if Y1 is N, then X1 is absent, if Y2 is N, then X4 is absent, Ra1 represents a hydrogen atom, an alkyl group, or an alkoxy group, and Rb1 to Rb4 independently represent a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0311] In equations (Le-4) to (Le-6), ERG, X1 to X4, Y1, Y2, Ra1, and Rb1 to Rb4 are equivalent to ERG, X1 to X4, Y1, Y2, Ra1, and Rb1 to Rb4 in equations (Le-1) to (Le-3), and the same applies to the preferred embodiment.

[0312] Furthermore, the leuco dye having the phthalide structure or fluorane structure described above is more preferably a compound represented by any of the following formulas (Le-7) to (Le-9), and is particularly preferably a compound represented by the following formula (Le-8), from the viewpoint of color development and visibility of the exposed area.

[0313] [ka]

[0314] In formulas (Le-7) to (Le-9), X1 to X4 each independently represent a hydrogen atom, a halogen atom, or a dialkylanilino group; Y1 and Y2 each independently represent C or N; if Y1 is N, X1 is absent; if Y2 is N, X4 is absent; Ra1 to Ra4 each independently represent a hydrogen atom, an alkyl group, or an alkoxy group; Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group; and Rc1 and Rc2 each independently represent an aryl group or a heteroaryl group.

[0315] In equations (Le-7) to (Le-9), X1 to X4, Y1 and Y2 are equivalent to X1 to X4, Y1 and Y2 in equations (Le-1) to (Le-3), and the preferred embodiment is also equivalent. In formula (Le-7) or formula (Le-9), Ra1 to Ra4 are each independently preferably alkyl groups or alkoxy groups, more preferably alkoxy groups, and particularly preferably methoxy groups, from the viewpoint of color development and visibility of the exposed area. In formulas (Le-7) to (Le-9), Rb1 to Rb4 are each independently preferably substituted with a hydrogen atom, an alkyl group, or an alkoxy group, more preferably an alkyl group, and particularly preferably a methyl group, from the viewpoint of color development and visibility of the exposed area. In formula (Le-8), Rc1 and Rc2 are each preferably a phenyl group or an alkylphenyl group, and more preferably a phenyl group, from the viewpoint of color development and visibility of the exposed area. Furthermore, Rc1 and Rc2 in formula (Le-8) are each preferably, from the viewpoint of color development and visibility of the exposed area, an aryl group having a substituent at least one ortho position, or a heteroaryl group having a substituent at least one ortho position, more preferably an aryl group having a substituent at least one ortho position, even more preferably a phenyl group having a substituent at least one ortho position, and particularly preferably a phenyl group having a substituent at least one ortho position and an electron-donating group at the para position. Examples of substituents in Rc1 and Rc2 are those described later. Furthermore, in formula (Le-8), from the viewpoint of color development and visibility of the exposed area, it is preferable that X1 to X4 are hydrogen atoms and Y1 and Y2 are carbon. Furthermore, in formula (Le-8), from the viewpoint of color development and visibility of the exposed area, it is preferable that Rb1 and Rb2 are each independently substituted with an alkyl group or an alkoxy group aryl group. Furthermore, in formula (Le-8), from the viewpoint of color development and visibility of the exposed area, it is preferable that Rb1 and Rb2 are each independently an aryl group or a heteroaryl group, more preferably an aryl group, even more preferably an aryl group having an electron-donating group, and particularly preferably a phenyl group having an electron-donating group at the para position. Furthermore, the electron-donating groups in Rb1, Rb2, Rc1, and Rc2 are preferably amino groups, alkylamino groups, arylamino groups, heteroarylamino groups, dialkylamino groups, monoalkylmonoarylamino groups, monoalkylmonoheteroarylamino groups, diarylamino groups, diheteroarylamino groups, monoarylmonoheteroarylamino groups, alkoxy groups, allyloxy groups, heteroaryloxy groups, or alkyl groups, more preferably alkoxy groups, allyloxy groups, heteroaryloxy groups, or alkyl groups, and particularly preferably alkoxy groups.

[0316] Furthermore, as an acid colorant, it is preferable to include a compound represented by the following formula (Le-10) from the viewpoint of color development and visibility of the exposed area.

[0317] [ka]

[0318] In formula (Le-10), each Ar1 independently represents an aryl group or a heteroaryl group, and each Ar2 independently represents an aryl group having a substituent at least one ortho position, or a heteroaryl group having a substituent at least one ortho position.

[0319] In equation (Le-10), Ar1 is equivalent to Rb1 and Rb2 in equations (Le-7) to (Le-9), and the same applies to the preferred embodiment. In equation (Le-10), Ar2 is synonymous with Rc1 and Rc2 in equations (Le-7) to (Le-9), and the preferred embodiment is similar.

[0320] Furthermore, as an acid colorant, it is preferable to include a compound represented by the following formula (Le-A) from the viewpoint of color development and visibility of the exposed area.

[0321] [ka]

[0322] In formula (Le-A), ERG each independently represents an electron-donating group, n11 represents an integer from 1 to 5, n12 represents an integer from 0 to 2, X1 to X4 each independently represent a hydrogen atom, a halogen atom, or a dialkylanilino group, Y1 and Y2 each independently represent C or N, if Y1 is N, then X1 is absent, if Y2 is N, then X4 is absent, and Rb4 each independently represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0323] In formula (Le-A), ERG, X1-X4, Y1, Y2, and Rb4 are equivalent to ERG, X1-X4, Y1, Y2, and Rb4 in formulas (Le-1) to (Le-3), respectively, and the same applies to the preferred embodiment. In equation (Le-A), n11 is preferably an integer between 1 and 3, and more preferably 1 or 2. In formula (Le-A), n12 is preferably 0 or 1, and more preferably 0.

[0324] Furthermore, as an acid colorant, it is preferable to include a compound represented by the following formula (Le-11) from the viewpoint of color development and visibility of the exposed area.

[0325] [ka]

[0326] In formula (Le-11), ERG each independently represents an electron-donating group, n11 represents an integer from 1 to 5, X1 to X4 each independently represents a hydrogen atom, a halogen atom, or a dialkylanilino group, Y1 and Y2 each independently represent C or N, if Y1 is N, then X1 is absent, if Y2 is N, then X4 is absent, and Rb2 and Rb4 each independently represent a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0327] In formula (Le-11), ERG, X1-X4, Y1, Y2, Rb2, and Rb4 are equivalent to ERG, X1-X4, Y1, Y2, Rb2, and Rb4 in formulas (Le-1) to (Le-3), respectively, and the same applies to the preferred embodiment. In equation (Le-11), n11 is preferably an integer between 1 and 3, and more preferably 1 or 2.

[0328] The alkyl groups in formulas (Le-1) to (Le-9), formula (Le-A), or formula (Le-11) may be linear, branched, or have a ring structure. Furthermore, the number of carbon atoms in the alkyl group in formulas (Le-1) to (Le-9), formula (Le-A), or formula (Le-11) is preferably 1 to 20, more preferably 1 to 8, even more preferably 1 to 4, and particularly preferably 1 or 2. In formulas (Le-1) to (Le-11) and (Le-A), the number of carbon atoms in the aryl group is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8. Specific examples of aryl groups in formulas (Le-1) to (Le-11) and (Le-A) include phenyl, naphthyl, anthracenyl, and phenantrenyl groups, which may have substituents. Specific examples of heteroaryl groups in formulas (Le-1) to (Le-11) and (Le-A) include furyl, pyridyl, pyrimidyl, pyrazoyl, and thiophenyl groups, which may have substituents.

[0329] Furthermore, each of the monovalent organic groups, alkyl groups, aryl groups, heteroaryl groups, dialkylanilino groups, alkylamino groups, alkoxy groups, etc. in formulas (Le-1) to (Le-11) and formula (Le-A) may have substituents. Examples of substituents include alkyl groups, aryl groups, heteroaryl groups, halogen atoms, amino groups, alkylamino groups, arylamino groups, heteroarylamino groups, dialkylamino groups, monoalkylmonoarylamino groups, monoalkylmonoheteroarylamino groups, diarylamino groups, diheteroarylamino groups, monoarylmonoheteroarylamino groups, hydroxyl groups, alkoxy groups, allyloxy groups, heteroallyloxy groups, acyl groups, alkoxycarbonyl groups, allyloxycarbonyl groups, heteroallyloxycarbonyl groups, cyano groups, etc. Moreover, these substituents may be further substituted with other substituents.

[0330] Furthermore, from the viewpoint of color development and visibility of the exposed area, the acid colorant preferably contains a compound represented by either of the following formulas 3a or 3b. In one preferred embodiment, the acid colorant is preferably a compound represented by either of the following formulas 3a or 3b.

[0331] [ka]

[0332] In formula (3a), Ar1 and Ar2 each independently represent an aryl group or a heteroaryl group. R 10 , R 11 These independently represent a hydrogen atom, an alkyl group, an aryl group, and a heteroaryl group, respectively. In formula (3b), ERG each independently represents an electron-donating group, n represents an integer from 1 to 5, X1 to X4 each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group, Y1 and Y2 each independently represent C or N, if Y1 is N, then X1 does not exist, if Y2 is N, then X4 does not exist, and R12 and R 13 Each of these independently represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0333] The alkyl groups in formulas (3a) to (3b) may be linear, branched, or have a ring structure. Furthermore, the number of carbon atoms in the alkyl group in formulas (3a) to (3b) is preferably 1 to 20, more preferably 1 to 8, even more preferably 1 to 4, and particularly preferably 1 or 2. The number of carbon atoms in the aryl group in formulas (3a) to (3b) is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8. Specific examples of aryl groups in formulas (3a) to (3b) include phenyl groups, naphthyl groups, anthracenyl groups, and phenantrenyl groups, which may have substituents. Specific examples of heteroaryl groups in formulas (3a) to (3b) include furyl groups, pyridyl groups, pyrimidyl groups, pyrazoyl groups, and thiophenyl groups, which may have substituents. In equation (3b), ERG is synonymous with ERG in equations (Le-1) to (Le-3), and the preferred embodiment is also the same. In equation (3b), n is preferably an integer between 1 and 3, and more preferably 1 or 2. The monovalent organic group in equation (3b) is X5~X in equations (Le-2)~(Le-3). 10 This is synonymous with a monovalent organic group, and the preferred embodiment is similar.

[0334] Furthermore, each of the monovalent organic groups, alkyl groups, aryl groups, heteroaryl groups, etc. in formulas (3a) to (3b) may have substituents. Examples of substituents include alkyl groups, aryl groups, heteroaryl groups, halogen atoms, amino groups, alkylamino groups, arylamino groups, heteroarylamino groups, dialkylamino groups, monoalkylmonoarylamino groups, monoalkylmonoheteroarylamino groups, diarylamino groups, diheteroarylamino groups, monoarylmonoheteroarylamino groups, hydroxyl groups, alkoxy groups, allyloxy groups, heteroaryloxy groups, acyl groups, alkoxycarbonyl groups, allyloxycarbonyl groups, heteroaryloxycarbonyl groups, cyano groups, and the like. Moreover, these substituents may be further substituted with other substituents.

[0335] The leuco dyes having the phthalide structure or fluorane structure described above are not particularly limited, but examples include the compounds described in paragraphs

[0141] to

[0150] of Japanese Patent Application Publication No. 2023-98447.

[0336] Furthermore, compounds described in paragraphs

[0151] to

[0188] of Japanese Patent Publication No. 2023-98447 can also be used as acid colorants.

[0337] These acid colorants may be used individually or in combination of two or more components. The content of the acid colorant is preferably 0.5% to 10% by mass, and more preferably 1% to 5% by mass, relative to the total solid content of the image recording layer.

[0338] (polymer compound) The polymer compound may function as a binder polymer in the image recording layer, or it may exist in the image recording layer as particulate polymer compounds (polymer particles).

[0339] <Binder Polymer> As the binder polymer, a polymer with film-forming properties is preferred, and examples of preferred materials include (meth)acrylic resin, polyvinyl acetal resin, and polyurethane resin.

[0340] As the binder polymer used in the image recording layer, a binder polymer having alkylene oxide chains is preferred. The binder polymer having alkylene oxide chains may have poly(alkylene oxide) moieties in the main chain or in the side chains. Alternatively, it may be a graft polymer having poly(alkylene oxide) moieties in the side chains, or a block copolymer consisting of a block composed of repeating units containing poly(alkylene oxide) moieties and a block composed of repeating units without (alkylene oxide) moieties. When the main chain contains a poly(alkylene oxide) moiety, polyurethane resin is preferred. When the side chain contains a poly(alkylene oxide) moiety, examples of main chain polymers include (meth)acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, novolac-type phenolic resin, polyester resin, synthetic rubber, and natural rubber, with (meth)acrylic resin being particularly preferred.

[0341] As the alkylene oxide, an alkylene oxide having 2 to 6 carbon atoms is preferred, and ethylene oxide or propylene oxide is particularly preferred. The number of alkylene oxide repeats in the poly(alkylene oxide) moiety is preferably 2 to 120, more preferably 2 to 70, and even more preferably 2 to 50. If the number of alkylene oxide repetitions is 120 or less, the decrease in print durability due to abrasion and the decrease in print durability due to deterioration of ink acceptance are suppressed, which is preferable.

[0342] The poly(alkylene oxide) moiety is preferably included as a side chain of the binder polymer in a structure represented by the following formula (AO), and more preferably as a side chain of the (meth)acrylic resin in a structure represented by the following formula (AO).

[0343] [ka]

[0344] In formula (AO), y represents a range from 2 to 120, R1 represents a hydrogen atom or an alkyl group, and R2 represents a hydrogen atom or a monovalent organic group. As monovalent organic groups, alkyl groups having 1 to 6 carbon atoms are preferred. Specifically, examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, cyclopentyl group, and cyclohexyl group. In formula (AO), y is preferably 2 to 70, and more preferably 2 to 50. R1 is preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom. R2 is particularly preferably a hydrogen atom or a methyl group.

[0345] The binder polymer may have crosslinking properties to improve the film strength of the image area. To give the polymer crosslinking properties, crosslinking functional groups such as ethylenically unsaturated bonds can be introduced into the main chain or side chains of the polymer. The crosslinking functional groups may be introduced by copolymerization or by polymer reaction. Examples of polymers having ethylenically unsaturated bonds in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene. Examples of polymers having ethylenically unsaturated bonds in the side chains of molecules include polymers of acrylic acid or methacrylic acid esters or amides in which the ester or amide residue (-COOR or -CONHR's R) has an ethylenically unsaturated bond.

[0346] An example of a residue containing an ethylenically unsaturated bond (R above) is -(CH2) n CR 1A =CR 2A R3A -(CH2O) n CH2CR 1A =CR 2A R 3A -(CH2CH2O) n CH2CR 1A =CR 2A R 3A ,-(CH2) n NH-CO-O-CH2CR 1A =CR 2A R 3A ,-(CH2) n -O-CO-CR 1A =CR 2A R 3A and -(CH2CH2O)2-X A (In the formula, R A1 ~R A3 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an alkoxy group, or an aryloxy group, and R A1 and R A2 or R A3 These elements may be joined together to form a ring. n represents an integer from 1 to 10. X A represents a dicyclopentadienyl residue. ) can be given as an example.

[0347] Specific examples of ester residues include -CH2CH=CH2, -CH2CH2O-CH2CH=CH2, -CH2C(CH3)=CH2, -CH2CH=CH-C6H5, -CH2CH2OCOCH=CH-C6H5, -CH2CH2-NHCOO-CH2CH=CH2, and -CH2CH2O-X (where X represents a dicyclopentadienyl residue). Specific examples of amide residues include -CH2CH=CH2, -CH2CH2-Y (where Y represents a cyclohexene residue), and -CH2CH2-OCO-CH=CH2.

[0348] A binder polymer with crosslinkability can harden when, for example, a free radical (polymerization initiation radical or growth radical during the polymerization process of a polymerizable compound) is added to its crosslinkable functional group, and crosslinks are formed between polymer molecules through addition polymerization, either directly between polymers or via the polymerization chain of a polymerizable compound. Alternatively, an atom in the polymer (for example, a hydrogen atom on a carbon atom adjacent to a functional crosslinking group) can be abstracted by a free radical to generate polymer radicals, which then bond to each other, forming crosslinks between polymer molecules and causing hardening.

[0349] The content of crosslinkable groups in the binder polymer (content of unsaturated double bonds capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0 to 7.0 mmol, and even more preferably 2.0 to 5.5 mmol per gram of binder polymer, from the viewpoint of good sensitivity and good storage stability.

[0350] Specific examples of binder polymers 1 to 11 are shown below, but the present invention is not limited to these. In the example compounds below, the numerical value accompanying each repeating unit (the numerical value accompanying the main chain repeating unit) represents the mole percentage of the repeating unit. The numerical value accompanying the side chain repeating unit indicates the number of repeats in the repeating site. Also, Me represents a methyl group, Et represents an ethyl group, and Ph represents a phenyl group.

[0351] [ka]

[0352] [ka]

[0353] The molecular weight of the binder polymer, as calculated by the GPC method using a weight-average molecular weight (Mw) of polystyrene equivalent, is 2,000 or more, preferably 5,000 or more, and more preferably 10,000 to 300,000.

[0354] If necessary, hydrophilic polymers such as polyacrylic acid and polyvinyl alcohol described in Japanese Patent Publication No. 2008-195018 can be used in combination. Furthermore, lipophilic polymers and hydrophilic polymers can also be used in combination.

[0355] The binder polymer may be used alone or in combination of two or more types. The binder polymer content is preferably 1 to 90% by mass, and more preferably 5 to 80% by mass, of the total solid content of the image recording layer.

[0356] <Polymer compounds in particulate form (polymer particles)> The image recording layer preferably contains polymer particles. The polymer particles contribute to improved on-pressure developmentability. The polymer particles are preferably polymer particles that can convert the image recording layer to hydrophobic when heat is applied. The polymer particles are preferably at least one selected from hydrophobic thermoplastic polymer particles, heat-reactive polymer particles, polymerizable groups, microcapsules containing hydrophobic compounds, and microgels (crosslinked polymer particles).

[0357] Suitable hydrophobic thermoplastic polymer particles include those described in Research Disclosure No. 33303 of January 1992, Japanese Patent Publication No. 9-123387, 9-131850, 9-171249, 9-171250, and European Patent No. 931647. Specific examples of polymers constituting hydrophobic thermoplastic polymer particles include homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and acrylates or methacrylates having a polyalkylene structure, or mixtures thereof. Preferably, copolymers containing polystyrene, styrene and acrylonitrile, and polymethyl methacrylate are used. The average particle size of the hydrophobic thermoplastic polymer particles is preferably 0.01 to 2.0 μm.

[0358] Examples of heat-reactive polymer particles include polymer particles having heat-reactive groups. Polymer particles having heat-reactive groups form hydrophobic regions through crosslinking due to thermal reactions and functional group changes during that process.

[0359] In polymer particles having a heat-reactive group, any functional group that undergoes any reaction as long as a chemical bond is formed can be used as the heat-reactive group, but polymerizable groups are preferred. Suitable examples include ethylenically unsaturated groups that undergo radical polymerization (e.g., acryloyl group, methacryloyl group, vinyl group, allyl group, etc.), cationic polymerizable groups (e.g., vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.), isocyanate groups or their blocks, epoxy groups, vinyloxy groups and functional groups having active hydrogen atoms that react with these groups (e.g., amino group, hydroxyl group, carboxyl group, etc.) that undergo addition reactions, carboxyl groups and their hydroxyl or amino groups that undergo condensation reactions, and acid anhydrides and their amino or hydroxyl groups that undergo ring-opening addition reactions.

[0360] Examples of microcapsules include those described in Japanese Patent Publication No. 2001-277740 and Japanese Patent Publication No. 2001-277742, in which all or part of the constituent components of the image recording layer are encapsulated within the microcapsules. The constituent components of the image recording layer can also be contained outside the microcapsules. In the image recording layer containing microcapsules, it is preferable that hydrophobic components are encapsulated within the microcapsules and hydrophilic components are contained outside the microcapsules.

[0361] Microgels (crosslinked polymer particles) can contain at least one of the components of the image recording layer in their interior and / or on their surface. In particular, a reactive microgel having radical polymerizable groups on its surface is preferred from the viewpoint of image formation sensitivity and print resistance.

[0362] Known methods can be used to microencapsulate or microgel the components of the image recording layer. The average particle size of microcapsules and microgels is preferably 0.01 to 3.0 μm, more preferably 0.05 to 2.0 μm, and particularly preferably 0.10 to 1.0 μm. Good resolution and stability over time can be obtained within this range.

[0363] Polymer particles may be used individually or in combination of two or more types. The polymer particle content is preferably 5 to 90% by mass, more preferably 5 to 80% by mass, and even more preferably 10 to 75% by mass, of the total solid content of the image recording layer.

[0364] In a preferred embodiment, the polymer particles have a hydrophobic main chain, i) A constituent unit having a pendant cyano group directly bonded to the hydrophobic main chain, and ii) Preferably, the constituent unit includes both a hydrophilic poly(alkylene oxide) segment and a pendant group. As the hydrophobic main chain mentioned above, an acrylic resin chain is preferred. Preferred examples of the pendant cyano group mentioned above include -[CH2CH(C≡N)-] or -[CH2C(CH3)(C≡N)-]. Furthermore, the constituent units having the pendant cyano group can be easily derived from ethylene-based unsaturated monomers, such as acrylonitrile or methacrylonitrile, or combinations thereof. Furthermore, as the alkylene oxide in the hydrophilic poly(alkylene oxide) segment described above, ethylene oxide or propylene oxide is preferred, and ethylene oxide is more preferred. The number of repeating alkylene oxide structures in the hydrophilic poly(alkylene oxide) segment described above is preferably 10 to 100, more preferably 25 to 75, and even more preferably 40 to 50. Particles of a resin having a hydrophobic main chain and comprising both i) a constituent unit having a pendant cyano group directly bonded to the hydrophobic main chain, and ii) a constituent unit having a pendant group containing a hydrophilic poly(alkylene oxide) segment, are preferably those described in paragraphs 0039 to 0068 of Japanese Patent Publication No. 2008-503365.

[0365] In one preferred embodiment, the polymer particles are preferably obtained by the reaction of a polyhydric isocyanate compound, which is an adduct of a polyhydric phenol compound having two or more hydroxyl groups in its molecule with an isophorone diisocyanate, and a compound having active hydrogen.

[0366] The average particle size of the polymer particles is preferably 0.01 to 3.0 μm, more preferably 0.05 to 2.0 μm, and particularly preferably 0.10 to 1.0 μm. Good resolution and stability over time can be obtained within this range.

[0367] Polymer particles may be used individually or in combination of two or more types. The polymer particle content is preferably 5 to 90% by mass, more preferably 5 to 80% by mass, and even more preferably 10 to 75% by mass, of the total solid content of the image recording layer.

[0368] As the polymer compound contained in the image recording layer, polymer compounds containing constituent units derived from styrene compounds and / or acrylonitrile compounds are also preferred. From the viewpoint of contributing to on-machine developability, this polymer compound can be suitably used as a binder polymer or polymer particles.

[0369] Examples of styrene compounds include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene, with styrene being preferred.

[0370] Examples of acrylonitrile compounds include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred.

[0371] In polymer compounds containing styrene compounds and acrylonitrile compounds as constituent units, it is preferable that the composition ratio of constituent units derived from styrene compounds to constituent units derived from acrylonitrile compounds is 4:1 to 1:4.

[0372] (Chain transfer agent) Chain transfer agents contribute to improving the print durability of lithographic printing plates produced from lithographic printing plates. As the chain transfer agent, thiol compounds are preferred, thiols with 7 or more carbon atoms are more preferred from the viewpoint of boiling point (low volatility), and compounds having a mercapto group on the aromatic ring (aromatic thiol compounds) are even more preferred. The thiol compound is preferably a monofunctional thiol compound.

[0373] The chain transfer agent may be used alone or in combination of two or more types. The content of the chain transfer agent 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, of the total solid content of the image recording layer.

[0374] (Lipidifying agent) Oil-sensing agents contribute to improving the ink adhesion (hereinafter also simply referred to as "ink adhesion") of lithographic printing plates made from lithographic printing plates. Examples of oil-sensing agents include phosphonium compounds, nitrogen-containing low molecular weight compounds, and ammonium group-containing polymers. In particular, when the lithographic printing plate has a protective layer containing an inorganic layered compound, these compounds function as surface coating agents for the inorganic layered compound and have the function of suppressing the decrease in ink adhesion during printing caused by the inorganic layered compound. As a lipid-sensing agent, it is preferable to use a combination of a phosphonium compound, a nitrogen-containing low molecular weight compound, and an ammonium group-containing polymer, and more preferably a combination of a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer. Regarding the lipid-reducing agent, those described in sections

[0151] to

[0155] of International Publication No. 2020 / 137919 may be used.

[0375] The amount of the lipid-sensitive agent is preferably 0.01 to 30% by mass, more preferably 0.1 to 15% by mass, and even more preferably 1 to 10% by mass, based on the total solid content of the image recording layer.

[0376] (Other ingredients) The image recording layer may contain, as other components, surfactants, calcining agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic particles, inorganic layered compounds, and the like. Specifically, the above components described in paragraphs 0114 to 0159 of Japanese Patent Application Publication No. 2008-284817 can be used.

[0377] The content of non-particulate polymer compounds with a weight-average molecular weight exceeding 15,000 is preferably 5% by mass or less, and more preferably 4% by mass or less, of the total solid content of the image recording layer.

[0378] (Formation of the image recording layer) The image recording layer can be formed, for example, by dispersing or dissolving the necessary components in a known solvent to prepare a coating solution, applying the coating solution by a known method such as bar coating, and drying it, as described in paragraphs 0142 to 0143 of Japanese Patent Publication No. 2008-195018. The amount of the image recording layer coated (solid content) after coating and drying varies depending on the application, but from the viewpoint of obtaining good sensitivity and good film characteristics of the image recording layer, it is 0.3 to 3.0 g / m². 2 A certain degree is desirable.

[0379] From the viewpoint of providing on-pressure developability, the image recording layer is preferably water-soluble or water-dispersible. Here, "water-soluble" means dissolving 0.1 g or more in 100 g of water at 20°C, and "water-dispersible" means uniformly dispersing in water at 20°C.

[0380] The on-press type lithographic printing plate master according to the present invention may have an undercoat layer (sometimes called an intermediate layer) between the image recording layer and the support.

[0381] [Undercoat layer] The undercoat layer strengthens the adhesion between the support and the image recording layer in the exposed areas, and makes it easier for the image recording layer to peel off from the support in the unexposed areas, thereby contributing to improved developability without compromising print durability. Furthermore, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, preventing the heat generated by exposure from diffusing to the support and reducing sensitivity.

[0382] Examples of compounds used in the undercoat layer include polymers having adsorbent groups and hydrophilic groups that can be adsorbed onto the support surface. Polymers having adsorbent groups and hydrophilic groups, and further having crosslinkable groups, are preferred to improve adhesion with the image recording layer. The compounds used in the undercoat layer may be low-molecular-weight compounds or polymers. Two or more compounds may be mixed and used as needed.

[0383] When the compound used in the undercoat layer is a polymer, copolymers of monomers having adsorbent groups, monomers having hydrophilic groups, and monomers having crosslinkable groups are preferred. Preferred adsorbent groups that can be adsorbed onto the support surface are phenolic hydroxyl groups, carboxyl groups, -PO3H2, -OPO3H2, -CONHSO2-, -SO2NHSO2-, and -COCH2COCH3. Preferred hydrophilic groups are sulfo groups or their salts, and carboxyl groups. Preferred crosslinking groups are acrylic groups, methacrylic groups, acrylamide groups, methacrylamide groups, and allyl groups. The polymer may have crosslinkable groups introduced by salt formation between the polar substituent of the polymer and a compound having a substituent oppositely charged to the polar substituent and an ethylenically unsaturated bond, or it may be further copolymerized with other monomers, preferably hydrophilic monomers.

[0384] Specifically, suitable examples include silane coupling agents having an ethylenically double bond reactive group that can be added and polymerized as described in Japanese Patent Publication No. 10-282679, and phosphorus compounds having an ethylenically double bond reactive group as described in Japanese Patent Publication No. 2-304441. Low molecular weight or high molecular weight compounds having a crosslinkable group (preferably an ethylenically unsaturated bond group), a functional group that interacts with the support surface, and a hydrophilic group as described in Japanese Patent Publication Nos. 2005-238816, 2005-125749, 2006-239867, and 2006-215263 are also preferably used. More preferable examples include polymers having adsorbent groups, hydrophilic groups, and crosslinkable groups that can be adsorbed onto the surface of a support, as described in Japanese Patent Publication No. 2005-125749 and Japanese Patent Publication No. 2006-188038.

[0385] The content of ethylenically unsaturated bonding groups in the polymer used for the undercoat layer is preferably 0.1 to 10.0 mmol, more preferably 0.2 to 5.5 mmol per gram of polymer. The weight-average molecular weight (Mw) of the polymer used in the undercoat layer is preferably 5,000 or more, and more preferably between 10,000 and 300,000.

[0386] In addition to the above-mentioned undercoat compound, the undercoat layer may also contain, to prevent soiling over time, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, or a compound having an amino group or a functional group having polymerization-inhibiting ability that interacts with the support surface (for example, 1,4-diazabicyclo[2.2.2]octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, etc.).

[0387] The undercoat layer can be formed by applying it using a known method and allowing it to dry. The amount of undercoat layer applied (solid content) after drying is 0.1 to 100 mg / m². 2 Preferably, 1 to 30 mg / m² 2 This is preferable.

[0388] The on-press type lithographic printing plate master according to the present invention may or may not have a protective layer on the image recording layer.

[0389] [Protective layer] The protective layer has the function of suppressing image formation inhibition reactions by blocking oxygen, as well as preventing scratches in the image recording layer and preventing ablation during high-intensity laser exposure.

[0390] Protective layers with such properties are described, for example, in U.S. Patent No. 3,458,311 and Japanese Patent Publication No. 55-49729. As the oxygen-low permeable polymer used in the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used, and two or more types can be mixed and used as needed. Specifically, examples include polyvinyl alcohol resin (including polyvinyl alcohol and modified polyvinyl alcohol), polyvinylpyrrolidone, water-soluble cellulose derivatives, and poly(meth)acrylonitrile. As the polyvinyl alcohol, polyvinyl alcohol with a degree of saponification of 50% or more is preferred. The degree of saponification of the polyvinyl alcohol is preferably 60% or more, more preferably 70% or more, and even more preferably 85% or more. There is no particular upper limit to the degree of saponification; it is sufficient if the degree of saponification is 100% or less. The degree of saponification can be measured according to the method described in JIS K 6726:1994. As the modified polyvinyl alcohol, acid-modified polyvinyl alcohol having a carboxyl group or a sulfo group is preferably used. Specifically, examples include the modified polyvinyl alcohols described in Japanese Patent Publication No. 2005-250216 and Japanese Patent Publication No. 2006-259137. Among water-soluble polymers, polyvinyl alcohol resin is preferred.

[0391] The protective layer preferably contains an inorganic layered compound to enhance oxygen barrier properties. The inorganic layered compound is a thin, flat particle and includes, for example, mica group such as natural mica and synthetic mica, talc represented by the formula: 3MgO·4SiO·H2O, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate, and the like. The inorganic layered compound that is preferably used is a mica compound. For example, a mica compound of formula A(B,C) 2-5 D4O 10 Examples of mica groups include natural mica and synthetic mica, represented by (OH,F,O)2 [where A is one of K, Na, or Ca; B and C are one of Fe(II), Fe(III), Mn, Al, Mg, or V; and D is Si or Al].

[0392] In the mica group, natural micas include muscovite, soda mica, phlogopite, biotite, and scallop mica. Synthetic micas include fluorinated phlogopite (KMg3(AlSi3O)). 10 ) F2, Potassium tetrasilicon mica KMg 2.5 Si4O 10 ) Non-swelling mica such as F2, and Na tetrasilicic mica NaMg 2.5 (Si4O 10 )F2, Na or Li teniolite (Na,Li)Mg2Li(Si4O 10 )F2, montmorillonite-based Na or Li hectorite (Na,Li) 1 / 8 Mg 2 / 5 Li 1 / 8 (Si4O 10 Examples include swelling mica such as F2. Synthetic smectite is also useful.

[0393] Among mica compounds, fluorine-based swelling mica is particularly useful. Specifically, swelling synthetic mica has a layered structure consisting of unit crystal lattice layers with a thickness of about 10-15 Å, and the intralattice metal atom substitution is significantly greater than in other clay minerals. As a result, the lattice layers suffer from a deficiency of positive charge, and Li is present between the layers to compensate for this. + kaNa + Ca 2+ Mg 2+It adsorbs cations such as Li. The cations interposed between these layers are called exchangeable cations and can exchange with various cations. In particular, the cations between the layers are Li + kaNa + In this case, the small ionic radius results in weak bonds between the layered crystal lattices, causing significant swelling in water. When sheared in this state, it easily cleaves and forms a stable sol in water. Swellable synthetic mica exhibits this tendency strongly and is therefore particularly preferred for use.

[0394] From the viewpoint of diffusion control, the shape of the mica compound is such that the thinner the particle, the better, and the larger the plane size, as long as it does not hinder the smoothness of the coated surface or the transmittance of active light. Therefore, the aspect ratio is preferably 20 or more, more preferably 100 or more, and particularly 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 a projection image of a microscopic photograph of the particle. The larger the aspect ratio, the greater the effect obtained.

[0395] The particle size of the mica compound is preferably 0.3 to 20 μm, more preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm in average major axis. 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 swelling synthetic mica, which is a representative compound, a preferred embodiment is a thickness of about 1 to 50 nm and a surface size (major axis) of about 1 to 20 μm.

[0396] The content of the inorganic layered compound is preferably 0 to 60% by mass, and more preferably 3 to 50% by mass, relative to the total solid content of the protective layer. Even when multiple types of inorganic layered compounds are used in combination, it is preferable that the total amount of inorganic layered compounds is within the above content range. Within this range, oxygen barrier properties are improved and good sensitivity is obtained. In addition, a decrease in paint adhesion can be prevented. The inorganic layered compound content is 0.01 to 100 mg / m². 2 Preferably, 5-80 mg / m² 2 More preferably, 5-50 mg / m² 2 That is particularly preferable.

[0397] The protective layer may contain known additives such as plasticizers for imparting flexibility, surfactants for improving applicability, and inorganic fine particles for controlling surface slipperiness. Furthermore, the protective layer may contain the oil-sensitive agents described for the image recording layer.

[0398] The protective layer can be formed by applying it using a known method and then drying it. The amount of protective layer applied (solid content) after drying is 0.01 to 10 g / m². 2 Preferably, 0.02-3 g / m 2 More preferably, 0.02~1g / m 2 That is particularly preferable.

[0399] The on-press type lithographic printing plate master according to the present invention may have a back coat layer on the non-printing surface side opposite the image recording layer, with the support in between. The back coat layer can be, for example, one like the one described in Japanese Patent Application Publication No. 2024-027054.

[0400] In the on-press type lithographic printing plate master according to the present invention, the arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer is preferably 0.3 to 20 μm. Here, the side opposite to the side having the image recording layer means the side opposite to the side having the image recording layer with respect to the support. In the on-press type lithographic printing plate master according to the present invention, the arithmetic mean height Sa of the outermost layer surface on the side having the image recording layer is preferably 0.3 to 20 μm. Here, the side having the image recording layer means the side having the image recording layer with respect to the support. By providing an outermost surface with such characteristics, the on-press development type lithographic printing plate master according to the present invention is superior in performance such as the ability to prevent multiple plate feeding in the process of removing the master from the stack, the ability to prevent scratches caused by protrusions on the outermost surface of the master, and the ability to prevent development delays caused by protrusions on the outermost surface of the master, even when stacked in a form without interleaving paper between the masters (also called interleaving paper-less).

[0401] The following describes examples of how to create printed plates to which the technology of this disclosure can be preferably applied.

[0402] <Preparation of support> A support was manufactured by subjecting a 0.3mm thick aluminum plate (aluminum alloy plate) made of material 1050 to the following treatments (Ja) to (Jm). Water washing was performed between all treatment steps, and after water washing, the liquid was removed using a nip roller.

[0403] (Ja) Mechanical surface roughening treatment (brush grain method) A pumice suspension (specific gravity 1.1 g / cm³) was supplied to the surface of an aluminum plate as a polishing slurry, while mechanical surface roughening was performed using a rotating bundled brush. In the mechanical surface roughening treatment, the median diameter (μm) of the abrasive material was set to 30 μm, the number of brushes to 4, and the brush rotation speed (rpm) to 250 rpm. The material of the bundled brush was 6-10 nylon, with a bristle diameter of 0.3 mm and a bristle length of 50 mm. The brushes were densely planted in a φ300 mm stainless steel cylinder with holes drilled in it. The distance between the two support rollers (φ200 mm) at the bottom of the bundled brush was 300 mm. The bundled brush was pressed against the aluminum plate until the load on the drive motor that rotated the brush was 10 kW more than the load before the bundled brush was pressed against the aluminum plate. The direction of brush rotation was the same as the direction of movement of the aluminum plate.

[0404] (Jb) Alkaline etching treatment An aluminum plate was etched by spraying it with an aqueous solution of caustic soda containing 26% by mass of caustic soda and 6.5% by mass of aluminum ions at a temperature of 70°C. The amount of aluminum dissolved in the surface to be subsequently subjected to electrochemical roughening treatment was 10 g / m2.

[0405] (Jc) Desmatt treatment using acidic aqueous solution As an acidic aqueous solution, waste nitric acid used in the subsequent electrochemical surface roughening treatment was sprayed onto an aluminum plate for 3 seconds at a liquid temperature of 35°C to perform the desmatt treatment.

[0406] (Jd) Electrochemical roughening treatment using aqueous nitric acid solution A continuous electrochemical surface roughening treatment was performed using a 60 Hz AC voltage. The electrolyte used was an aqueous solution of 10.4 g / L nitric acid to which aluminum nitrate was added to adjust the aluminum ion concentration to 4.5 g / L, at a liquid temperature of 35°C. The AC power waveform is shown in Figure 8, with a current value tp of 0.8 msec from zero to peak, a duty cycle of 1:1, and a trapezoidal rectangular wave AC. Electrochemical surface roughening was performed using a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The current density was 35 A / dm2 at the peak current value, and 5% of the current flowing from the power supply was diverted to the auxiliary anode. The total electric charge (C / dm2) when the aluminum plate was the anode was 185 C / dm2.

[0407] (Je) Alkali etching treatment An aluminum plate was etched by spraying it with an aqueous solution of caustic soda containing 27% by mass of caustic soda and 2.5% by mass of aluminum ions at a temperature of 50°C. The amount of aluminum dissolved was 2.0 g / m2.

[0408] (Jf) Desmatt treatment using acidic aqueous solution As an acidic aqueous solution, a solution with a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L at a liquid temperature of 30°C was sprayed onto an aluminum plate for 3 seconds to perform the desmatt treatment.

[0409] (Jg) Electrochemical roughening treatment using hydrochloric acid aqueous solution A continuous electrochemical surface roughening treatment was performed using a 60 Hz AC voltage. The electrolyte used was an aqueous solution of hydrochloric acid containing 6.2 g / L with aluminum chloride added to adjust the aluminum ion concentration to 4.5 g / L, at a liquid temperature of 35°C. The AC power waveform is shown in Figure 8, with a current value tp of 0.8 msec from zero to peak, a duty cycle of 1:1, and a trapezoidal rectangular wave AC. Electrochemical surface roughening was performed using a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The current density was 35 A / dm2 at the peak current value, and the amount of electricity (C / dm2) during hydrochloric acid electrolysis was 63 C / dm2, which is the sum of the amounts of electricity when the aluminum plate was the anode.

[0410] (Jh) Alkali etching treatment An aluminum plate was etched by spraying it with an aqueous solution of caustic soda containing 5% by mass of caustic soda and 0.5% by mass of aluminum ions at a temperature of 60°C. The amount of aluminum dissolved was 0.2 g / m2.

[0411] (Ji) Desmatt treatment using acidic aqueous solution As an acidic aqueous solution, a solution of waste liquid (sulfuric acid concentration 170 g / L and aluminum ion concentration 5 g / L) generated in an anodizing process at a liquid temperature of 35°C was sprayed onto an aluminum plate for 4 seconds to perform the desmatt treatment.

[0412] (Jj) First stage anodizing treatment The first stage of anodic oxidation treatment was performed using a DC electrolytic anodic oxidation apparatus. An 170 g / L sulfuric acid aqueous solution was used as the electrolyte, and the anodic oxidation treatment was carried out under conditions of a liquid temperature of 50°C and a current density of 30 A / dm2, forming an anodic oxidation film with a film thickness of 0.3 g / m2.

[0413] (Jk) Pore-wide processing An anodized aluminum plate was immersed in a caustic soda aqueous solution with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass for 5 seconds at 40°C to perform a pore widening treatment.

[0414] (Jl) Second stage anodizing treatment The second stage of anodic oxidation was performed using a DC electrolytic anodic oxidation apparatus. An 170 g / L sulfuric acid aqueous solution was used as the electrolyte, and the anodic oxidation treatment was carried out under conditions of a solution temperature of 50°C and a current density of 13 A / dm2, forming an anodic oxidation film with a film thickness of 2.3 g / m2.

[0415] (Jm) Silicate treatment To ensure hydrophilicity in the non-image areas, the aluminum plate was silicate-treated by immersing it in a 2.5% by mass sodium silicate aqueous solution at 58°C for 7 seconds.

[0416] <Formation of the undercoat layer> A primer layer was formed on the support by applying a primer coating liquid (1) with the following composition to a dry coating amount of 26 mg / m2.

[0417] (Primer coating liquid (1)) • Undercoat compound (2) (structure shown below) 0.013 parts Hydroxyethyliminodiacetic acid 0.005 parts • Ethylenediaminetetraacetate tetrasodium 0.005 parts • Polyoxyethylene lauryl ether 0.003 parts ·Wednesday 3.15 parts

[0418] [ka]

[0419] <Formation of the image recording layer> An image recording layer coating solution with the following composition was applied in a bar onto the undercoat layer, and the mixture was oven-dried at 100°C for 60 seconds to form an image recording layer with a thickness of 1.0 μm.

[0420] -Image recording layer coating liquid- 2-Butanone: 5,600 copies • 1-Methoxy-2-propanol (MFG): 3,300 parts Methanol: 1,300 parts • Borate compound (sodium tetraphenylborate): 0.0300 parts • Polymerization initiator (I-1): 0.0130 parts • Infrared absorber (Dye-5): 0.038 parts · 2,2',4,4'-Tetrahydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.): 0.048 parts • Anionic surfactant (A-1): 0.0750 parts • Fluorine-based surfactant (W-1): 0.0042 parts • Binder polymer 1:0.5400 parts (23% MFG solution) ·Polymerizable compound (1): 0.6800 parts • Polymer particles R-1 (microgel liquid): 2.3256 parts

[0421] [ka]

[0422] [ka]

[0423] [ka]

[0424] [ka]

[0425] <Preparation of Binder Polymer 1> 69.18 g of 1-methoxy-2-propanol was weighed into a 500 mL three-necked flask and heated to 70°C under a nitrogen stream. A mixed solution consisting of 52.90 g of Bremmer PME-100 (methoxydiethylene glycol monomethacrylate, manufactured by Nippon Oil & Fats Co., Ltd.), 35.17 g of methyl methacrylate, 6.05 g of methacrylic acid, 0.917 g of hexakis(3-mercaptopropionic acid) dipentaerythritol, 0.809 g of V-601 (2,2'-azobis(isobutyrate)dimethyl, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 70.10 g of 1-methoxy-2-propanol was added dropwise over 2 hours and 30 minutes. After the addition was complete, the reaction was continued for another 2 hours. After 2 hours, a mixed solution consisting of V-601:0.081 g and 1-methoxy-2-propanol:3.32 g was added, and the temperature was raised to 90°C and the reaction was continued for 2.5 hours. After the reaction was complete, the reaction solution was cooled to room temperature. To the above reaction solution, 97.73 g of 1-methoxy-2-propanol, 0.23 g of 4-hydroxytetramethylpiperidine N-oxide, 6.49 g of glycidyl methacrylate, and 0.90 g of betaine were added and the mixture was thoroughly stirred. The mixture was then heated at 92°C for 24 hours. After 24 hours, the reaction solution was cooled to room temperature and then diluted with 78.84 g of 1-methoxy-2-propanol. The resulting binder polymer 1 had a solid content concentration of 23% by mass and a polystyrene-equivalent weight-average molecular weight of 65,000 as measured by GPC.

[0426] <Synthesis of polymerizable compound (1)> A mixed solution of Takenate D-160N (polyisocyanate trimethylolpropane adduct, manufactured by Mitsui Chemicals, Inc., 4.7 parts), Arronix M-403 (manufactured by Toagosei Co., Ltd., in an amount that results in a 1:1 ratio between the NCO value of Takenate D-160N and the hydroxyl value of Arronix M-403), t-butylbenzoquinone (0.02 parts), and methyl ethyl ketone (11.5 parts) was heated to 65°C. Neostan U-600 (bismuth-based polycondensation catalyst, manufactured by Nitto Kasei Co., Ltd., 0.11 parts) was added to the reaction solution and heated at 65°C for 4 hours. The reaction solution was cooled to room temperature (25°C), and methyl ethyl ketone was added to synthesize a urethane acrylate solution with a solid content of 50% by mass. Molecular weight fractionation of a urethane acrylate (M-5) solution was performed using a recycled GPC (instrument: LC908-C60, columns: JAIGEL-1H-40 and 2H-40 (manufactured by Nippon Analytical Industry Co., Ltd.)) with tetrahydrofuran (THF) as the eluent. The weight-average molecular weight was 20,000.

[0427] <Preparation of polymer particles R-1> ·Microgel (1) (solid content 21.8% by mass) 1.8349 parts 1-Methoxy-2-propanol 0.4907 parts

[0428] (Preparation of microgel (1)) The method for preparing the microgel (1) used in the polymer particle R-1 solution described above is shown below.

[0429] <Preparation of polyhydric isocyanate compound (1)> To a suspension of 17.78 parts (80 molar equivalents) of isophorone diisocyanate and 7.35 parts (20 molar equivalents) of the following polyhydric phenol compound (1) in ethyl acetate (25.31 parts), 0.043 parts of bismastris (2-ethylhexanoate) (Neostan U-600, manufactured by Nitto Kasei Co., Ltd.) was added and the mixture was stirred. Once the exothermic reaction subsided, the reaction temperature was set to 50°C and the mixture was stirred for 3 hours to obtain an ethyl acetate solution (50% by mass) of polyhydric isocyanate compound (1).

[0430] [ka]

[0431] <Preparation of microgel (1)> The oil phase and aqueous phase components listed below were mixed and emulsified using a homogenizer at 12,000 rpm for 10 minutes. The resulting emulsion was stirred at 45°C for 4 hours, then 5.20 parts of a 10% by mass aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-en-octylate (U-CAT SA102, manufactured by Sunapro Co., Ltd.) were added, stirred at room temperature for 30 minutes, and allowed to stand at 45°C for 24 hours. The solid content concentration was adjusted to 21.8% by mass with distilled water to obtain an aqueous dispersion of microgel (1). The volume-average particle size was measured by light scattering using a dynamic light scattering particle size distribution analyzer LB-500 (manufactured by Horiba, Ltd.), and was found to be 0.28 μm.

[0432] (Oil phase components) (Component 1) Ethyl acetate 12.0 parts (Component 2) 3.76 parts of an adduct (50% by mass ethyl acetate solution, manufactured by Mitsui Chemicals, Inc.) obtained by adding trimethylolpropane (6 mol) and xylene diisocyanate (18 mol), and then adding methyl-terminated polyoxyethylene (1 mol, number of oxyethylene units repeated: 90) to it. (Component 3) Polyhydric isocyanate compound (1) (as a 50% by mass ethyl acetate solution) 15.0 copies (Component 4) 11.54 parts of a 65% by mass ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer) (Component 5) 4.42 parts of a 10% ethyl acetate solution of a sulfonate-type surfactant (Pionin A-41-C, manufactured by Takemoto Oil Co., Ltd.)

[0433] (Aqueous phase component) Distilled water 46.87 parts

[0434] <Formation of the overcoat layer> An overcoat coating solution with the following composition was applied to the image recording layer using a bar coating method, and then oven-dried at 120°C for 60 seconds to form a protective layer with a thickness of 0.20 μm.

[0435] -Overcoat layer coating liquid- • Inorganic layered compound dispersion (1): 1.6590 parts • Polyvinyl alcohol (Goselan L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., sulfonic acid modified, saponification degree 85 mol%): 0.065 parts • Surfactant (Pionin A-32-B (structure shown below), manufactured by Takemoto Oil Co., Ltd.) 40% by mass aqueous solution): 0.014 parts • Surfactant (Surfinol 465 (structure below), manufactured by Nisshin Chemical Co., Ltd.): 0.006 parts • Phosphoric acid (85% by mass aqueous solution): 0.0269 parts Trisodium phosphate dodecahydrate (manufactured by Nippon Chemical Industrial Co., Ltd.): 0.0719 parts ·Pure water: 5.600 parts

[0436] --Preparation of inorganic layered compound dispersion (1)-- 193.6 parts of deionized water were mixed with 6.4 parts of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co., Ltd.), and the mixture was dispersed using a homogenizer until the volume-average particle size (laser scattering method) reached 3 μm. The aspect ratio of the resulting dispersed particles was 100 or greater.

[0437] [ka]

[0438] <Visibility evaluation: Immediately after exposure> The obtained lithographic printing plate was exposed to light using an AMZISetter manufactured by NEC Corporation, equipped with an infrared semiconductor laser with a wavelength of 830 nm, at an exposure dose of 110 mJ / cm². The exposure image included both fully exposed and unexposed areas. Exposure was performed under conditions of 25°C and 50% RH. The color development of lithographic printing plates was measured immediately after exposure. A compact spectrophotometer, the eXact Advanced, manufactured by X-Rite, was used for the measurements. Visibility was evaluated using the L* value (lightness) of the L*a*b* color system, specifically the difference ΔL between the L* value of the exposed area and the L* value of the unexposed area. A larger ΔL value indicates better visibility.

[0439] <Visibility evaluation: After storage in the dark> The obtained lithographic printing plate was exposed to light using an AMZISetter manufactured by NEC Corporation, equipped with an infrared semiconductor laser with a wavelength of 830 nm, at an exposure dose of 110 mJ / cm². The exposure image included both fully exposed and unexposed areas. Exposure was performed under conditions of 25°C and 50% RH. The original lithographic printing plates were stored for 72 hours at 25°C, 50% RH, and in the dark immediately after exposure, and then their color development was measured. During storage, another lithographic printing plate was placed on top of the original plate to prevent the exposed surface from being exposed to air. The measurements were performed using an X-Rite eXact Advanced compact spectrophotometer. Visibility was evaluated using the L* value (lightness) of the L*a*b* color system, and the difference ΔL between the L* value of the exposed area and the L* value of the unexposed area was used. A larger ΔL value indicates better visibility. If ΔL is 10 or greater, it is considered within the acceptable range.

[0440] The ΔL of the press-developable lithographic printing plate master created in this manner was 10 or greater, and the printing plate identification information could be read with high accuracy using the technology disclosed herein.

[0441] In the above-described example of creating an on-press type lithographic printing plate, a more preferable example of an on-press type lithographic printing plate used in the information reading method of this disclosure is to replace the image recording layer with the following composition, apply an overcoat layer coating solution of the following composition onto the image recording layer, and oven dry it at 120°C for 60 seconds to form a protective layer with a thickness of 0.22 μm, and further apply a backcoat layer coating solution (1) of the following composition to the backcoat layer side (non-printing side) of the support, and dry it at 100°C for 120 seconds to form a backcoat layer with a thickness of 1.2 μm.

[0442] -Image recording layer coating liquid- 2-Butanone: 5,600 copies • 1-Methoxy-2-propanol (MFG): 2,900 parts Methanol: 1,300 parts • Borate compound (sodium tetraphenylborate): 0.0375 parts • Infrared absorber (Dye-5): 0.032 parts · 2,2',4,4'-Tetrahydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.): 0.048 parts • Anionic surfactant (A-1): 0.0750 parts DOWSIL (registered trademark) FZ-2123 (manufactured by Dow Toray Industries, Inc.): 0.0020 units • Binder polymer 1:1.5185 parts (23% MFG solution) ·Polymerizable compound (1): 0.5121 part • Polymer particles R-1 (microgel liquid): 1.2224 parts

[0443] -Overcoat layer coating liquid- • Inorganic layered compound dispersion (1): 2.2120 parts • Polyvinyl alcohol (Goselan L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., sulfonic acid modified, saponification degree 85 mol%): 0.0860 parts • Surfactant (Pionin A-32-B (structure shown below), manufactured by Takemoto Oil Co., Ltd.) 40% by mass aqueous solution): 0.0140 parts • Surfactant (Surfinol 465 (structure shown below), manufactured by Nisshin Chemical Co., Ltd.): 0.006 parts • Phosphoric acid (85% by mass aqueous solution): 0.0230 parts • Diammonium hydrogen phosphate: 0.0320 parts ·Pure water: 5.3400 parts

[0444] -Back coat layer coating solution (1)- • Mitsubishi Chemical BR-605 (acrylic resin) 11.072g • Smecton-SEN (flat particle) 0.500g, manufactured by Kunimine Industries Co., Ltd. • Negami Kogyo Co., Ltd., Acrylic Particles Art Pearl J-6PF 0.975g • Kao Corporation, Leodol TW-S106V (Polyoxyethylene (6) Sorbitan Monostearate) 0.250g 2-Butanone 74.123g 1-Methoxy-2-propanol 8.720g • Methanol 4.360g

[0445] As described above, this specification includes at least the following: Components corresponding to the embodiments described above are shown in parentheses below, but are not limited thereto.

[0446] (1) A first step of preparing an on-press development type lithographic printing plate master plate (master plate 10) having an exposure area (exposure area 13) containing a colorant having an absorption maximum in the visible range, an unexposed area (unexposed area 14), an image forming layer (image forming layer 12) having a ΔL of 10 or more between the exposure area and the unexposed area, and plate identification information formed on the surface of the image forming layer side with water-soluble ink (water-soluble ink 15), A second step involves imaging the on-pressure-developable lithographic printing plate with the image sensor (image sensor 21) while a filter (filter 50) is provided between the on-pressure-developable lithographic printing plate and the image sensor (image sensor 21) that cuts out light in a first range (first range R1) that includes the wavelength of the absorption maximum and is narrower than the visible range. An information reading method comprising: a third step of acquiring the printing plate identification information based on the image data obtained by imaging in the second step described above.

[0447] (2) (1) The method for reading information described above, An information reading method wherein the difference in absorbance between the exposed area and the unexposed area at the wavelength of the absorption maximum (absorbance difference ΔX) is greater than the difference in absorbance between the exposed area and the unexposed area at wavelengths other than the first range within the visible region.

[0448] (3) (1) or (2) is an information reading method, An information reading method wherein the difference in absorbance between the exposed area and the unexposed area at the wavelength of the absorption maximum (absorbance difference ΔX) is greater than the difference in absorbance between the exposed area and the unexposed area at wavelengths other than that wavelength in the visible range.

[0449] (4) A method for reading information described in any one of (1) to (3), The above-mentioned first range includes a second range (second range R2) in which the difference in absorbance between the exposed area and the unexposed area (absorbance difference ΔX) is greater than or equal to a threshold (threshold TH1). An information reading method wherein the difference in absorbance between the exposed area and the unexposed area in the visible range other than the first range is less than the threshold.

[0450] (5) (4) The method for reading information described above, An information reading method wherein the difference in absorbance (absorbance difference ΔY) between the unexposed area and the surface of the image-forming layer in the visible range other than the first range is greater than or equal to the threshold.

[0451] (6) A method for reading information described in any one of (1) to (5), The above first range includes an information reading method that includes the range of 500 nm to 650 nm.

[0452] (7) A method for reading information described in any one of (1) to (6), The above-mentioned water-soluble ink is black; this is the method for reading information.

[0453] (8) A method for reading information described in any one of (1) to (7), The second step of the above-described information reading method involves attaching the filter to the imaging window of a reading device having the image sensor and the imaging window facing the image sensor using an adhesive sheet made of a substrate that does not absorb in the visible range and to which an adhesive has been applied, and then using the image sensor to image the original plate of an on-machine-developable lithographic printing plate through the filter and the imaging window.

[0454] (9) Image sensor (image sensor 21), An on-pressure developing type lithographic printing plate (plate 10) having an exposure area (exposure area 13) containing a chromogen having an absorption maximum in the visible range, and an unexposed area (unexposed area 14), wherein the ΔL between the exposure area and the unexposed area is 10 or more, and plate identification information formed on the surface facing the image forming layer with water-soluble ink (water-soluble ink 15), and a filter (filter 50) provided between it and the image sensor, which cuts out light in a first range (first range R1) that includes the wavelength of the absorption maximum and is narrower than the visible range, A reading system (reading system 60) comprising a processor (control unit 30) that acquires printing plate identification information based on image data obtained by imaging the on-pressure developed lithographic printing plate original plate with the image sensor through the above filter.

[0455] (10) An attachment (attachment 52) ​​for a reading device (reading device 100) capable of reading the printing plate identification information from an on-press development type lithographic printing plate master plate (master plate 10), which has an exposed area (exposed area 13) containing a colorant having an absorption maximum in the visible range, and an unexposed area (unexposed area 14), wherein the ΔL between the exposed area and the unexposed area is 10 or more, and printing plate identification information formed on the surface facing the image forming layer with water-soluble ink (water-soluble ink 15), A filter (filter 50) that cuts out light in a first range (first range R1) that includes the wavelength of the absorption maximum mentioned above and is narrower than the visible range, The device comprises a support portion (support portion 51) that supports the above-mentioned filter, The support portion is an attachment for a reading device, configured to allow the image sensor (image sensor 21) of the reading device to image the original plate for on-press development type lithographic printing through the filter, and to be detachable from the reading device.

[0456] (11) (10) The attachment described above, The above-mentioned support part is an attachment configured to allow the above-mentioned filter to be replaced.

[0457] (12) An attachment for a reading device that can read printing plate identification information from an on-press type lithographic printing plate master plate, which has an exposure area containing a colorant having an absorption maximum in the visible range, and an unexposed area, wherein the ΔL between the exposure area and the unexposed area is 10 or more, and printing plate identification information formed on the surface of the image forming layer with water-soluble ink, A filter that cuts out light in a first range that includes the wavelength of the absorption maximum mentioned above and is narrower than the visible range, The above filter is attached to an adhesive sheet, which has an adhesive applied to a substrate that does not absorb in the visible range, and the sheet comprises: The above filter is an attachment for a reading device, configured to be attached by the above adhesive sheet to a position that covers the imaging window of the reading device. [Explanation of Symbols]

[0458] 10 Original version 11 Support 12 Image-forming layer 13 Exposure area 14 Unexposed areas 15 Water-soluble ink 20 Imaging Department 21 Image sensor 30 Control Unit 40 Light-irradiating section 41 Light source 50 filters 51 Support part 53 Adhesive Sheets 52, 52A, 52B Attachments 60,60A reading system 100 Reading device 101 cabinets 102 Imaging window 103 Lighting window R1 First Range R2 Second Range R3 Third Range

Claims

1. A first step of preparing an on-press development type lithographic printing plate master having an image-forming layer having an exposure area containing a colorant having an absorption maximum in the visible range, an unexposed area, and a ΔL of 10 or more between the exposure area and the unexposed area, and a printing plate identification information formed on the surface of the image-forming layer with water-soluble ink, A second step involves imaging the on-pressure-developable lithographic printing plate with the image sensor, with a filter provided between the on-pressure-developable lithographic printing plate and the image sensor that cuts out light in a first range that includes the wavelength of absorption maximum and is narrower than the visible range. An information reading method comprising: a third step of acquiring the printing plate identification information based on the image data obtained by imaging in the second step.

2. The information reading method according to claim 1, An information reading method wherein the difference in absorbance between the exposed area and the unexposed area at the wavelength of absorption maximum is greater than the difference in absorbance between the exposed area and the unexposed area at wavelengths other than the first range within the visible region.

3. The information reading method according to claim 2, The first range includes a second range in which the difference in absorbance between the exposed area and the unexposed area is greater than or equal to a threshold. An information reading method wherein the difference in absorbance between the exposed portion and the unexposed portion in a range other than the first range within the visible range is less than the threshold.

4. The information reading method according to claim 3, An information reading method wherein the difference in absorbance between the unexposed portion and the surface of the image-forming layer in a range other than the first range within the visible range is greater than or equal to the threshold.

5. The information reading method according to claim 4, The first range includes a range of 500 nm to 650 nm, and is an information reading method.

6. The information reading method according to claim 5, The aforementioned water-soluble ink is black, and this is an information reading method.

7. An information reading method according to any one of claims 1 to 6, The second step is an information reading method in which, after attaching the filter to the imaging window of a reading device having an image sensor and an imaging window facing the image sensor using an adhesive sheet having an adhesive applied to a substrate that does not absorb in the visible range, the image sensor captures the original plate of an on-machine-developable lithographic printing plate through the filter and the imaging window.

8. Image sensor and An on-pressure developing type lithographic printing plate master having an exposure area containing a colorant having an absorption maximum in the visible range, and an unexposed area, wherein the ΔL between the exposure area and the unexposed area is 10 or more, and printing plate identification information formed on the surface facing the image forming layer with water-soluble ink, and a filter provided between the image sensor and the image sensor, which cuts out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range, A reading system comprising: a processor that acquires printing plate identification information based on image data obtained by imaging the on-press development type lithographic printing plate original plate with the image sensor through the filter; and the image system that acquires printing plate identification information.

9. An attachment for a reading device capable of reading printing plate identification information from an on-press development type lithographic printing plate master plate, which has an exposure area containing a colorant having an absorption maximum in the visible range, and an unexposed area, wherein the ΔL between the exposure area and the unexposed area is 10 or more, and printing plate identification information formed on the surface on the image forming layer side with water-soluble ink, A filter that cuts out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range, The filter is supported by a support portion, The support portion is an attachment to the reading device, configured to enable the image sensor of the reading device to image the on-machine-developable lithographic printing plate through the filter, and to be detachable from the reading device.

10. The attachment according to claim 9, The support portion is an attachment configured to allow the filter to be replaced.

11. An attachment for a reading device capable of reading printing plate identification information from an on-press development type lithographic printing plate master plate, which has an exposure area containing a colorant having an absorption maximum in the visible range, and an unexposed area, wherein the ΔL between the exposure area and the unexposed area is 10 or more, and printing plate identification information formed on the surface on the image forming layer side with water-soluble ink, A filter that cuts out light in a first range that includes the wavelength of the absorption maximum and is narrower than the visible range, The filter is attached to an adhesive sheet, which has an adhesive applied to a substrate that does not absorb in the visible range. The filter is an attachment for a reading device, configured to be attached by the adhesive sheet to a position that covers the imaging window of the reading device.

Images