JP2005271338A - Image forming method and lithographic printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method for a lithographic printing master which exhibits sensitivity, printing resistance and white light safety, and a lithographic printing method using the same. <P>SOLUTION: The image forming method includes a process for exposing a lithographic printing master which has, on a support, an image recording layer containing a polymerization initiator, a polymerizable compound and a binder polymer with a light source radiating a light of a wavelength of 250 nm to 420 nm, and also includes a process for heating the master over the glass transition temperature of the binder polymer. In the lithographic printing method, the lithographic printing master with an image formed using this method is supplied with a printing ink and a dampening water to remove a non-imaging part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming method for a lithographic printing plate precursor and a lithographic printing method using the same. More specifically, the present invention relates to an image forming method for a lithographic printing plate precursor using a light source that emits light within a wavelength range of 250 nm to 420 nm, and a lithographic printing method using the same.

In general, a lithographic printing plate has a surface composed of an oleophilic image portion and a hydrophilic non-image portion. In lithographic printing, dampening water and oil-based ink are alternately applied to the plate surface, and the hydrophilic non-image area is dampened with a dampening water receiving area (ink non-receiving area) by utilizing the property that water and oil repel each other. ), After the ink is received only in the oleophilic image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Usually, after exposing the lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer to be an image portion is left, and the other unnecessary image recording layer is removed with an alkaline developer or an organic solvent. The lithographic printing plate is obtained by carrying out plate making by a method in which the surface of the hydrophilic support is exposed by dissolving and removing to form a non-image portion.

  In the conventional plate making process of a lithographic printing plate precursor, after exposure, a step of dissolving and removing unnecessary image recording layers with a developer or the like is necessary, but such additional wet processing is made unnecessary or Simplification is cited as one of the issues. In particular, in recent years, disposal of waste liquids discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and therefore, the demand for solving the above-mentioned problems has become stronger.

On the other hand, as one of simple plate making methods, an image recording layer that can be removed in a normal printing process is used in a lithographic printing plate precursor, and is unnecessary on a printing machine after exposure. A method called on-press development has been proposed in which the image recording layer is removed to obtain a lithographic printing plate.
As a specific method of on-press development, for example, a method of using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in dampening water, an ink solvent, or an emulsion of dampening water and ink , Method of mechanically removing the image recording layer by contact with rollers or blankets of a printing press, cohesion of the image recording layer or adhesion between the image recording layer and the support by penetration of dampening water, ink solvent, etc. There is a method in which after the force is weakened, the image recording layer is mechanically removed by contact with rollers or a blanket.
In the present invention, unless otherwise specified, the “development process step” refers to using a device other than a printing press (usually an automatic developing machine) and bringing a liquid (usually an alkaline developer) into contact therewith. Refers to the step of removing the image recording layer of the lithographic printing plate precursor and exposing the surface of the hydrophilic support, and “on-press development” refers to a liquid (usually printing ink and / or wet) using a printing press. This refers to a method and process for removing the image recording layer of the lithographic printing plate precursor and exposing the surface of the hydrophilic support by contacting with water.

  On the other hand, in recent years, digitization technology that electronically processes, stores, and outputs image information using a computer has become widespread, and various new image output methods corresponding to such digitization technology have been put into practical use. It has come to be. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate technology for manufacturing is attracting attention. Therefore, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.

  As described above, in recent years, the simplification, drying, and no processing of plate making operations have become more desirable than ever in terms of consideration for the global environment and adaptation to digitalization. It is coming.

  On the other hand, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 47-8657) discloses a photosensitive composition containing polyvinylpyrrolidone, a polymer polycarboxylic acid, an olefinically unsaturated monomer, a photoinitiator, and the like. Although it is described that a printing plate can be obtained that can be immediately mounted on a printing press and processed without post-exposure processing, the photoinitiator used here is problematic in terms of sensitivity and fog after exposure. was there.

  Patent Document 2 (Japanese Patent Publication No. 6-502931) describes a photosensitive lithographic printing plate having a photosensitive hydrophilic layer and a photosensitive layer having a two-layer structure comprising a photosensitive hydrophobic layer thereon. ing. This photosensitive lithographic printing plate can be immediately attached to a printing press for printing without post-exposure processing. However, since the adhesion between the upper layer and the lower layer is insufficient, the printing durability is still insufficient.

  Furthermore, Patent Document 3 (International Publication No. WO96 / 34316 pamphlet) describes a photosensitive lithographic printing plate having a one-layer structure comprising a photocurable group and a polymer having an acidic group or a salt thereof and a photoinitiator. . This photosensitive lithographic printing plate can also be immediately attached to a printing press without being subjected to post-exposure processing. However, the printing durability is insufficient, particularly when the pH of the fountain solution during printing becomes alkaline. The printability is extremely deteriorated.

When the conventional image recording method using light in the ultraviolet to visible region is used for simplifying plate making operations such as on-press development, the image recording layer does not fix after exposure, so it is sensitive to room light. For this reason, after the lithographic printing plate precursor is taken out of the package, it must be completely shielded from light or handled in a safe light environment until on-press development is completed. That is, the light source used for image recording is image-like exposure with light in the range of 300 to 500 nm, such as a metal halide lamp. Therefore, the lithographic printing plate precursor has photosensitivity in that range and emits light mainly in the visible region. There is a large overlap with room light with a band, and the light irradiation intensity is low to medium illuminance, and exposure is performed with the same light intensity as room light. Formation was a problem.
On the other hand, by shifting the absorption maximum of the photosensitive wavelength to the short wavelength side, the overlap with the emission spectrum of the white fluorescent lamp used for room light is reduced, and even when the image forming sensitivity of the recording material is sufficiently high, the white It was revealed that no image was formed by irradiation with a fluorescent lamp. That is, by setting the wavelength region to 420 nm to 250 nm, it is possible to minimize the overlap with room light, and unnecessary image formation can be suppressed by irradiation with room light.
In addition, it is possible to give a large amount of light energy in a short time by exposing short wavelength light with large energy per photon with a particularly high illuminance laser. Occurs in a very short time, is less susceptible to polymerization inhibition by oxygen, and is excellent in image formability. On the other hand, in a low-efficiency reaction such as room light with low illuminance and long exposure, if energy equivalent to that in high illuminance exposure is applied, it becomes more susceptible to polymerization inhibition by oxygen, thus suppressing unnecessary image formation. It is possible. When the photosensitive wavelength is shorter than 250 nm, an undesirable photochemical reaction such as decomposition of the image recording material is caused, and therefore a region having a shorter wavelength is not preferable.
JP-A-47-8657 JP-T 6-502931 International Publication No. WO96 / 34316 Pamphlet

  An object of the present invention is to provide a lithographic printing plate precursor image forming method excellent in sensitivity, printing durability and white light safety, and a lithographic printing method using the same.

As a result of extensive research, the present inventor has heated the lithographic printing plate precursor to a glass transition temperature (Tg) or higher of the binder polymer used in the image recording layer, so that the image recording layer becomes flexible and the polymerization reaction is not caused. It has been found that a good image can be formed with improved sensitivity and printing durability. In addition, by using a polymer whose binder polymer has a glass transition temperature higher than room temperature, the mobility of the polymer decreases at room temperature, and the polymerization reaction is suppressed, so it is unnecessary under normal white light at room temperature. As a result, the present inventors have found that the image formation and the white light safety are compatible, and the present invention has been completed.
That is, the present invention is as follows.
1. A lithographic printing plate precursor in which an image recording layer containing a polymerization initiator, a polymerizable compound, and a binder polymer is provided on a support is exposed using a light source that emits light within a wavelength range of 250 nm to 420 nm. And an image forming method comprising: a step of heating to a glass transition temperature or higher of the binder polymer.

2. 2. The image forming method according to claim 1, wherein the heating step is performed before the exposure step, after the exposure step, or at the same time as the exposure step.
3. 3. The image forming method as described in 1 or 2 above, wherein the polymerization initiator is a compound having an onium ion.
4). 4. The image forming method according to any one of 1 to 3, wherein the light source is a laser.
5). A lithographic printing method comprising printing a lithographic printing plate precursor on which an image has been formed by the method according to any one of 1 to 4 above, supplying printing ink and fountain solution to remove non-image areas.

  According to the present invention, by including the step of heating to a glass transition temperature (Tg) or higher of the binder polymer contained in the image recording layer of the lithographic printing plate precursor, the image recording layer becomes flexible, and a polymerization initiator or a polymerizable property is obtained. Since the mobility of the compound is improved and it is easy to move, it is possible to provide a lithographic printing plate precursor image forming method and a lithographic printing method in which a polymerization reaction is promoted and sensitivity, printing durability, and white light safety are improved.

[Step of heating above the glass transition temperature (Tg) of the binder polymer]
In the image forming method of the present invention, the step of heating to the glass transition temperature (Tg) or higher of the binder polymer used for the image recording layer is performed before the exposure step, after the exposure step, or at least simultaneously with the exposure step. It is characterized by having.
The reason why the image forming method of the present invention improves the sensitivity, printing durability and white light safety is not clear, but heating the image recording layer to Tg or higher of the binder polymer in the image recording layer makes the image recording layer flexible. Thus, the mobility of the initiator and the polymerizable compound is improved, and it is easy to move, so that the polymerization reaction is promoted, and as a result, the sensitivity, printing durability, and white light safety are considered to be improved.

In the present invention, the heating step is performed before the exposure step, after the exposure step, or at least simultaneously with the exposure step. Heating before exposure (preheating) is performed as preliminary heating, and there is a merit that exposure can be performed immediately by preparing for exposure. Further, heating after exposure (post-heating) is effective for further promoting the polymerization reaction.
Next, the heating process that can be employed in the present invention will be described in detail with reference to the drawings.

  Regarding the pre-exposure heating, the pre-heating timing is such that the pre-heating temperature, that is, heating up to the glass transition temperature of the binder polymer used in the image recording layer, starts irradiation 1 minute before the start of irradiation of the laser beam used for image exposure. It is preferable to complete within the period until the time, and further within the period from 30 seconds before the start of irradiation to the start of irradiation. This is because the exposure apparatus used, the heating apparatus, the active ingredient of the lithographic printing plate precursor, It can be appropriately selected depending on the sensitivity. The preheating timing can be controlled by adjusting the drum circumference of the exposure apparatus, the main scanning speed, the interval between the exposure head and the preheating head, and the like.

  As shown in FIGS. 3 and 4, the preheating device 38 of the image exposure apparatus 10 preheats the preheating region of the lithographic printing plate precursor by blowing hot air directly onto the surface of the lithographic printing plate precursor 12. However, the preheating device is not limited to the one using hot air. For example, a heating element such as a halogen heater or a ceramic heater is mounted on the carrier 68, and the lithographic printing plate precursor is irradiated with laser light from the heating element. Even if the preheating area is heated, a magnetron is mounted on the carrier 68, and an electromagnetic wave having a predetermined wavelength generated by the magnetron is irradiated to the image recording layer of the lithographic printing plate precursor 12, so that the Even if a substance such as water is resonated and heated (electromagnetic wave heating), an electric coil is mounted on the carrier 68 and a high frequency magnetic field from the electromagnetic coil is flattened. Is applied to the metal of the support in the printing plate precursor 12 may be inductively heating the support.

  When performing the electromagnetic wave heating, for the purpose of effectively absorbing the electromagnetic wave and converting it to heat energy, it is preferable to include a component that can resonate with the electromagnetic wave and generate heat in the recording layer component. For example, when using a generally used 240 Hz electromagnetic wave, water corresponds to that component, and therefore, by containing a compound that retains water such as a hydrophilic resin or a water-soluble compound in the recording layer component, Water retention in the recording layer can be improved and efficient heat generation can be generated. Examples of the hydrophilic resin used herein include those described in the section of the hydrophilic resin described later in this specification. Among them, polysaccharides such as arabic rubber, soya rubber, hydroxypropyl cellulose, hydroxymethyl cellulose, polyacrylic acid, High molecular compounds having a hydroxyl group in the molecule such as sodium polyacrylate, hydroxypropyl acrylate and polyvinyl alcohol, and low molecular weight compounds such as sorbitol and glycerin are preferred from the viewpoint of improving the water retention of the recording layer.

  The preheating device 38 of the image exposure apparatus 10 according to the present invention preferably heats the heating member 146 to a high temperature state by magnetic induction, and heats the lithographic printing plate precursor 12 by heat transfer from the heating member 146 (indirect heating). However, the high frequency magnetic field from the coil unit 148 is applied to the support (aluminum plate) in the lithographic printing plate precursor without passing through the heating member 146, so that the support is induction heated (direct heating). May be.

  As shown in FIGS. 2, 5, and 6, in the image exposure apparatus 10 used when a heating process is performed after exposure or simultaneously with exposure, for example, a heating device 38 is disposed in a casing 14. It is preferable. The heating device 38 locally heats (spots) the lithographic printing plate precursor 12 with hot air. As shown in FIG. 5, the heating fan unit 140 is connected to the heating fan unit 140 through a flexible duct 142. And a tubular hot air nozzle 144. The heating fan unit 140 is fixed to the casing 14, and the hot air nozzle 144 is mounted on the carrier 68 together with the exposure head 26. The flexible duct 142 has a distal end portion inserted through the cable bear together with a bundle of optical fibers.

Here, the hot air nozzle 144 on the carrier 68 is disposed adjacent to the exposure head 26 along the sub-scanning direction. The hot air nozzle 144 is supported so that the base end side thereof extends in parallel with the traveling direction of the laser light L, and the tip of the hot air nozzle 144 is located on the planographic printing plate precursor 12 from the base end side toward the front end surface. A bend portion 45 bent so as to face the exposure area A _IR is formed. A rectangular air outlet is opened at the distal end surface of the bend portion 45.

The heating fan unit 140 includes a heating unit 48 made of a halogen heater, a ceramic heater, or the like that heats the air sucked from the outside of the casing 14, and an air supply unit that sends the heated air into the flexible duct 142 in a pressurized state. 50 is provided. The high-temperature air sent into the flexible duct 142 is supplied to the hot air nozzle 144, and is blown as hot air from the outlet 46 of the hot air nozzle 144 to the planographic printing plate precursor 12 mounted on the outer drum 20. At this time, since the bend portion 45 of the hot air nozzle 144 is directed to the exposure area A _IR on the planographic printing plate precursor 12, the hot air blown from the outlet 46 is exposed to the exposure area A _IR in the planographic printing plate precursor 12. (This is appropriately referred to as “heating area A _HT ”), and the recording layer in the heating area A _HT is heated to a predetermined heating temperature.

Here, the heating region A _HT is the center have substantially coincides with the center of the exposure area A _IR, there is a sufficiently large size than the sub-scanning direction and the exposure area A _IR along the main scanning direction. Thus, the heating region A _HT of the lithographic printing plate precursor 12 on becomes a region that includes an exposure region A _IR, hot air blown out from the blowout opening 46, any of the exposure laser beam L of the lithographic printing plate precursor 12 simultaneously irradiated to the region a _IR, blown to the heating region a _HT including the exposure region a _IR, heating region a while the exposure to the exposure area a _IR is completed exposed from the start the exposure by the laser beam L _HT is heated to a predetermined heating temperature.
However, the exposure time from the start of exposure of an arbitrary exposure area A _IR by the laser beam L to the completion of the exposure is substantially the same as the modulation period of the laser beam L according to the sub-scanning speed. It is a short time of about 05 seconds. In such a short time, in order to heat the lithographic printing plate precursor to a desired heating temperature with hot air, for example, the temperature of the hot air needs to be extremely high, which is not practical. Therefore, 50 to 100 times longer than Satoshi of the heating region A _HT exposure region A _IR along the sub-scanning direction, a hot air heating for an arbitrary exposure region A _IR included in the heating region A _HT modulation period 10 It is preferable to be able to continue over ⁶ to 10 ⁷ times or more. As a result, the heating time for an arbitrary exposure area A _IR can be sufficiently extended, so that the exposure area A _IR can be stably heated to a predetermined heating temperature without significantly increasing the hot air temperature.

Further, the image exposure apparatus 10 is provided with a heating control unit for controlling the heating device 38, and the heating control unit controls the temperature and the air volume of hot air supplied from the heating fan unit 140 to the hot air nozzle 144, respectively. Control. The measurement signal equipped with a temperature sensor such as an infrared radiation thermometer on the carrier 68, the temperature (surface temperature) of the heating region A _HT by the temperature sensor is measured, corresponding to the surface temperature of the heating region A _HT center May be output to the heating control unit. As a result, the heating control unit can feedback control the temperature of the heating area A _HT based on the measurement signal, so that the temperature of the central area of the heating area A _HT is accurately and stably maintained at the heating temperature. become able to.

  As shown in FIG. 1, the image exposure apparatus 10 is provided with a carry-out mechanism 84 for carrying the lithographic printing plate precursor 12 detached from the outer drum 20 to the discharge tray 18 in the casing 14. The unloading mechanism 84 includes a plurality of conveying rollers 86 and a plate-shaped guide member 88 arranged along the unloading path of the planographic printing plate precursor 12.

  In the image exposure apparatus 10, after the exposure (image formation) to the lithographic printing plate precursor 12 mounted on the outer drum 20 is completed, the outer drum 20 is rotated in the reverse direction (in the direction of arrow R <b> 2 in FIG. 1) and the chuck mechanism 22. The rear end and the front end of the planographic printing plate precursor 12 are sequentially released from the outer drum 20. In conjunction with this, the carry-out mechanism 84 rotates the transport roller 86 to start carrying out the lithographic printing plate precursor 12 sent from the outer drum 20 to the entrance of the discharge path to the discharge tray. The original plate 12 is discharged onto the discharge tray 18.

The heating device 38 of the image exposure apparatus 10 according to the present invention, directly into a lithographic printing plate precursor 12 surface and by blowing hot air is intended to heat the spot heating region A _HT of the lithographic printing plate precursor 12, such The heating device is not limited to those using hot air. For example, an infrared radiator such as a halogen heater or a ceramic heater is mounted on the carrier 68, and the lithographic printing plate precursor 12 is irradiated with infrared rays from the radiator. Even if the heating area _AHT is spot-heated, a magnetron is mounted on the carrier 68, and the recording layer of the lithographic printing plate precursor 12 is irradiated with an electromagnetic wave having a predetermined wavelength generated by the magnetron. Even if a substance such as water is resonated to perform spot heating (electromagnetic wave heating), an electromagnetic coil is mounted on the carrier 68, and Wave magnetic field is applied to the metallic support of the lithographic printing plate precursor 12, the support may be spot inductively heating.

  In the present invention, both the pre-exposure heating and post-heating from the heating step to the exposure step, or the interval from the exposure step to the heating step can be appropriately selected depending on the exposure apparatus used, the heating apparatus, the active ingredients of the lithographic printing plate precursor, In the case of preheating, preferably within 1 to 60 seconds after heating, more preferably within 1 to 30 seconds, and in the case of post heating, within 1 to 60 seconds after exposure, more preferably within 1 to 30 seconds. It is preferable to perform an exposure process or a heating process.

Next, a planographic printing plate precursor to which the image forming method of the present invention can be applied will be described. In the lithographic printing plate precursor that can be used in the image forming method of the present invention, an image recording layer containing a polymerization initiator, a polymerizable compound, and a binder polymer is provided on a support.
(Image recording layer)
The image recording layer of the present invention contains a polymerization initiator, a polymerizable compound, and a binder polymer, has photosensitivity in a wavelength range of 250 nm to 420 nm, and can be removed by printing ink and / or fountain solution. . Accordingly, in the lithographic printing plate precursor according to the present invention, the exposed portion of the image recording layer is cured by light irradiation within a wavelength range of 250 nm to 420 nm to form a hydrophobic (lipophilic) region, and at the start of printing, The exposed portion is quickly removed from the support by dampening water, ink, or an emulsion of dampening water and ink.
Hereinafter, each component of the image recording layer will be described.

<Polymerization initiator>
The polymerization initiator used in the present invention is a compound that initiates and accelerates the polymerization of a compound having a polymerizable unsaturated group by generating radicals with light energy having a wavelength of 250 nm to 420 nm. Examples of such a photo radical generator include a known polymerization initiator and a compound having a bond having a small bond dissociation energy (a compound having absorption within a wavelength range of 250 nm to 420 nm, or a wavelength range of 250 nm to 420 nm). A compound that generates a radical by energy transfer or electron transfer from a compound having absorption therein can be appropriately selected and used. In this way, the lithographic printing plate precursor according to the present invention can have photosensitivity in the wavelength range of 250 nm to 420 nm.

Examples of the compounds that generate radicals include organic halogen compounds, carbonyl compounds, organic peroxides, azo polymerization initiators, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boron compounds, disulfone compounds, and oximes. Examples thereof include ester compounds and onium salt compounds.

  Specific examples of the organic halogen compound include Wakabayashi et al., “Bull Chem. Soc Japan” 42, 2924 (1969), US Pat. No. 3,905,815, Japanese Patent Publication No. 46-4605, JP 48-36281, JP 53-133428, JP 55-3070, JP 60-239736, JP 61-169835, JP 61-169837, JP 62- 58241, JP-A 62-212401, JP-A 63-70243, JP-A 63-298339, P. Examples thereof include compounds described in Hutt "Journal of Heterocyclic Chemistry" 1 (No 3), (1970) ". Of these, oxazole compounds and S-triazine compounds substituted with a trihalomethyl group are preferred.

  More preferable examples include s-triazine derivatives in which at least one mono, di, or trihalogen-substituted methyl group is bonded to the s-triazine ring, and oxadiazole derivatives in which the oxadiazole ring is bonded. Specifically, for example, 2,4,6-tris (monochloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [1- (P-methoxyphenyl) -2,4-butadienyl] -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis (trichloromethyl) -s-triazine, 2- ( -Methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (pi-propyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p- Tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenylthio-4,6-bis ( Trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (dibromomethyl) -s-triazine, 2,4,6-tris ( Tribromomethyl) -s-triazine, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2-methoxy-4,6-bis (tribromomethyl) Etc. -s- triazine and the following compounds.

Examples of the carbonyl compound include benzophenone, Michler ketone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-chlorobenzophenone, 4-bromobenzophenone, 2-carboxybenzophenone and other benzophenone derivatives, 2,2-dimethoxy- 2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, α-hydroxy-2-methylphenylpropanone, 1-hydroxy-1-methylethyl- (p-isopropylphenyl) ketone, 1- Hydroxy-1- (p-dodecylphenyl) ketone, 2-methyl- (4 ′-(methylthio) phenyl) -2-morpholino-1-propanone, 1,1,1-trichloromethyl- (p-butylphenyl) Acetophenone derivatives such as ketones, thioxanthone derivatives such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, p- Examples thereof include benzoic acid ester derivatives such as ethyl dimethylaminobenzoate and ethyl p-diethylaminobenzoate.

  As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.

  Examples of the organic peroxide include trimethylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butyl). Peroxy) cyclohexane, 2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydro Peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2, -Oxanoyl peroxide, succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate , Dimethoxyisopropyl peroxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tert-butyl peroxyacetate, tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, tert- Butyl peroxyoctanoate, tert-butyl peroxylaurate, tersyl carbonate, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4 ′ − Tra- (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogen diphthalate), carbonyl And di (t-hexylperoxydihydrogen diphthalate).

Examples of the metallocene compound include JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, JP-A-2-4705, Various titanocene compounds described in JP-A-5-83588, such as di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, Di-cyclopentadienyl-Ti-bis-2,4-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl, di- -Cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,4,5,6-penta Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4,6-trifluoropheny -1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4 , 5,6-pentafluorophen-1-yl, iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109, and the like.

  Examples of the hexaarylbiimidazole compound include the specification of JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. And, specifically, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-bromophenyl) )) 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2 ′ -Bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5,5 '-Tetraphenylbiimidazole, 2, 2' Bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole and the like.

  Examples of the organoboron compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188585, JP-A-9-188686, JP-A-9-188710, JP-A 2000-. 131837, Japanese Patent Application Laid-Open No. 2002-107916, Japanese Patent No. 2764769, Japanese Patent Application Laid-Open No. 2002-116539, and Kunz, Martin “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”, etc. Organoborates described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, and organic boron oxosulfonium complexes, JP-A-6-175554 No. 1, JP-A-6-175553 The organoboron iodonium complex described in JP-A-9-188710, the organoboron phosphonium complex described in JP-A-9-188710, JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP-A-5-140589 Examples thereof include organoboron transition metal coordination complexes such as 7-306527 and JP-A-7-292014.

  Examples of the disulfone compound include compounds described in JP-A Nos. 61-166544 and 2003-328465.

Examples of the oxime ester compounds include JCS Perkin II (1979) 1653-1660), JCS
Perkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, compounds described in JP-A No. 2000-66385, compounds described in JP-A No. 2000-80068, specifically, And a compound represented by the structural formula:

  Examples of the onium salt compound include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055, 4,069,056, phosphonium salts described in European Patent Nos. 104,143, US Pat. Nos. 339,049, 410,201, JP -150848, JP-A-2-296514, iodonium salts, European Patent Nos. 370,693, 390,214, 233,567, 297,443, and 297 442, U.S. Pat. Nos. 4,933,377, 161,811, 410,201, 339,049, 4,760,013 No. 4,734,444, No. 2,833,827, German Patent No. 2,904,626, No. 3,604,580, No. 3,604,581 Or a sulfonium salt described in J. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), and onium salts such as arsonium salts.

In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
The onium salts suitably used in the present invention are onium salts represented by the following general formulas (RI-I) to (RI-III).

In the formula (RI-I), Ar ₁₁ represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include an alkyl group having 1 to 12 carbon atoms and a carbon number. 1-12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1-C1 12 alkylamino groups, C1-C12 dialkylamino groups, C1-C12 alkylamide groups or arylamide groups, carbonyl groups, carboxyl groups, cyano groups, sulfonyl groups, C1-C12 thioalkyl groups And a thioaryl group having 1 to 12 carbon atoms. Z ₁₁ ^- represents a monovalent anion, specifically a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, a sulfate ion Can be mentioned. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion and sulfinate ion are preferable from the viewpoint of stability.

In formula (RI-II), Ar ₂₁ and Ar ₂₂ each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include 1 to 1 carbon atoms. 12 alkyl groups, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, Halogen atom, C1-C12 alkylamino group, C1-C12 dialkylamino group, C1-C12 alkylamide group or arylamide group, carbonyl group, carboxyl group, cyano group, sulfonyl group, carbon Examples thereof include a thioalkyl group having 1 to 12 carbon atoms and a thioaryl group having 1 to 12 carbon atoms. Z ₂₁ ^- represents a monovalent anion. Specific examples include halogen ions, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, thiosulfonate ions, and sulfate ions. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoint of stability and reactivity.

In the formula (RI-III), R ₃₁ , R ₃₂ and R ₃₃ are each independently an aryl group, alkyl group, alkenyl group or alkynyl having 20 or less carbon atoms, which may have 1 to 6 substituents. Represents a group. Among them, an aryl group is preferable from the viewpoint of reactivity and stability. Examples of the substituent include an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, 1 carbon
~ 12 aryloxy group, halogen atom, alkylamino group having 1 to 12 carbon atoms, dialkylamino group having 1 to 12 carbon atoms, alkylamide group or arylamide group having 1 to 12 carbon atoms, carbonyl group, carboxyl group, cyano Group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms. Z ₃₁ ^- represents a monovalent anion. Specific examples include halogen ions, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, thiosulfonate ions, and sulfate ions. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoints of stability and reactivity. More preferred are the carboxylate ions described in JP-A No. 2001-343742, and particularly preferred are the carboxylate ions described in JP-A No. 2002-148790.

  The polymerization initiator is not limited to the above, but a triazine-based initiator, an organic halogen compound, an oxime ester compound, a diazonium salt, an iodonium salt, and a sulfonium salt are more preferable from the viewpoints of reactivity and stability.

  Furthermore, these triazine-based initiators, organic halogen compounds, oxime ester compounds, diazonium salts, iodonium salts, and sulfonium salt-based polymerization initiators are preferably used in combination with a sensitizer. By using in combination with a sensitizer, the photopolymerization rate can be increased.

Specific examples of such sensitizers include benzoin, benzoin methyl ether, benzoin ethyl ether, 9-fluorenone, 2-chloro-9-fluorenone, 2-methyl-9-fluorenone, 9-anthrone, and 2-bromo-9. -Anthrone, 2-ethyl-9-anthrone, 9,10-anthraquinone, 2-ethyl-9, 10-anthraquinone, 2-t-
Butyl-9,10-anthraquinone, 2,6-dichloro-9,10-anthraquinone, xanthone, 2-methylxanthone, 2-methoxyxanthone, thioxanthone, benzyl, dibenzalacetone, p- (dimethylamino) phenylstyryl ketone , P- (dimethylamino) phenyl p-methylstyryl ketone, benzophenone, p- (dimethylamino) benzophenone (or Michler's ketone), p- (diethylamino) benzophenone, benzanthrone and the like.

  Furthermore, preferred sensitizers in the present invention include compounds represented by the general formula (II) described in Japanese Patent Publication No. 51-48516.

In the formula, R ¹⁴ is an alkyl group (for example, methyl group, ethyl group, propyl group, etc.) or a substituted alkyl group (for example, 2-hydroxyethyl group, 2-methoxyethyl group, carboxymethyl group, 2-carboxyethyl group) Etc.). R ¹⁵ represents an alkyl group (eg, methyl group, ethyl group, etc.) or an aryl group (eg, phenyl group, p-hydroxyphenyl group, naphthyl group, thienyl group, etc.).

Z ² is a group of nonmetallic atoms necessary for forming a heterocyclic nucleus containing nitrogen, which is usually used in cyanine dyes, such as benzothiazoles (benzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, etc.), naphtho Thiazoles (such as α-naphthothiazole, β-naphthothiazole), benzoselenazoles (such as benzoselenazole, 5-chlorobenzoselenazole, 6-methoxybenzoselenazole), naphthoselenazoles (α-naphthelenazole) , Β-naphthselenazole, etc.), benzoxazoles (benzoxazole, 5-methylbenzoxazole, 5-phenylbenzoxazole, etc.) and naphthoxazoles (α-naphthoxazole, β-naphthoxazole, etc.).

Specific examples of the compound represented by the general formula (II) are those having a chemical structure combining these Z ² , R ¹⁴ and R ¹⁵ , and many exist as known substances. Therefore, it can be used by appropriately selecting from these known ones. Furthermore, preferable sensitizers in the present invention include merocyanine dyes described in JP-B-5-47095 and ketocoumarin compounds represented by the following general formula (III).

Here, R ¹⁶ represents an alkyl group such as a methyl group or an ethyl group.

  As the sensitizer, merocyanine dyes described in JP-A No. 2000-147763 can also be used. Specifically, the following compounds can be mentioned.

  These polymerization initiators and sensitizers are each preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0. 0% by mass relative to the total solid content constituting the image recording layer. It can be added at a rate of 8 to 20% by mass. Within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained. These polymerization initiators may be used alone or in combination of two or more. Moreover, these polymerization initiators may be added to the same layer as other components, or another layer may be provided and added thereto.

<Polymerizable compound>
The polymerizable compound that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one ethylenically unsaturated bond, preferably two or more. It is. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer, isocyanuric acid There are EO-modified triacrylate and the like.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate. Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include, for example, aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, and JP-A-59-5241. Those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

  In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (IV) to a polyisocyanate compound having two or more isocyanate groups. Compounds and the like.

_{CH 2 = C (R 4)} COOCH 2 CH (R 5) OH (IV)
(However, R ₄ and R ₅ represent H or CH _3. )

  Further, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56-17654 Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable. Further, by using addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238. Can obtain a photopolymerizable composition having an excellent photosensitive speed.

  Other examples include reacting polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191 and JP-B-52-30490. And polyfunctional acrylates and methacrylates such as epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, and JP-B-1-40336, vinylphosphonic acid compounds described in JP-A-2-25493, and the like are also included. Can be mentioned. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

About these polymerizable compounds, the details of usage such as the structure, single use or combination, addition amount and the like can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image portion, that is, the cured film, those having three or more functionalities are preferable, and further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrene compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
In addition, the selection and use method of the polymerized compound is also an important factor for the compatibility and dispersibility with other components in the image recording layer (for example, binder polymer, initiator, colorant, etc.). The compatibility may be improved by using a low-purity compound or using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the substrate and the protective layer described later.

  The polymerizable compound is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass with respect to the total solid content constituting the image recording layer. These may be used alone or in combination of two or more. In addition, the use method of the addition polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging property, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.

<Binder polymer>
In the present invention, a binder polymer is used to improve the film strength and film property of the image recording layer and to improve the on-press developability. A conventionally well-known thing can be used as a binder polymer without a restriction | limiting, The linear organic polymer which has film property is preferable. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.
The binder polymer preferably has crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.
Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid where the ester or amide residue (R of -COOR or -CONHR) is Mention may be made of polymers having an ethylenically unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{bond, - (CH 2) n CR} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and — (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, Represents an alkoxy group or an aryloxy group, and R ¹ and R ² or R ³ may combine with each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadienyl. Represents a residue).
Specific examples of the ester _{residue, -CH 2 CH = CH 2,} ( described in JP Kokoku _{7-21633.) - CH 2 CH 2} O-CH 2 CH = CH 2, -CH 2 C _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 -NHCOO-CH 2 CH = CH 2 and - CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

  In the case of a binder polymer having crosslinkability, for example, free radicals (polymerization initiation radicals or growth radicals in the polymerization process of a polymerizable compound) are added to the crosslinkable functional group, and a polymerization chain of a polymerizable compound is formed directly between polymers. Through addition polymerization, a cross-link is formed between the polymer molecules and cured. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded to each other so that crosslinking between the polymer molecules occurs. Forms and cures.

  The content of the crosslinkable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0, per 1 g of the binder polymer. -7.0 mmol, most preferably 2.0-5.5 mmol. Within this range, good sensitivity and good storage stability can be obtained.

Further, from the viewpoint of on-press developability of the image recording layer unexposed portion, the binder polymer preferably has high solubility or dispersibility in ink and / or fountain solution.
In order to improve the solubility or dispersibility in ink, the binder polymer is preferably lipophilic, and in order to improve the solubility or dispersibility in dampening water, the binder polymer is hydrophilic. Is preferred. Therefore, in the present invention, it is also effective to use a lipophilic binder polymer and a hydrophilic binder polymer in combination.

  In the case of an oleophilic binder polymer, an alkali-soluble group such as a carboxyl group, which is essential for a binder polymer used in a lithographic printing plate precursor that requires a development step with a conventional alkaline developer, is unnecessary, and it can be developed on-machine. From the viewpoint, it is preferable not to include a functional group having such polarity that easily interacts with the substrate. On the other hand, a hydrophilic binder polymer may have such a polar substituent because it has good solubility or dispersibility in a highly polar dampening solution.

  Examples of hydrophilic binder polymers include hydroxy groups, carboxyl groups, carboxylate groups, hydroxyethyl groups, polyoxyethyl groups, hydroxypropyl groups, polyoxypropyl groups, amino groups, aminoethyl groups, aminopropyl groups, and ammonium. Preferred are those having a hydrophilic group such as a group, an amide group, a carboxymethyl group, a sulfonic acid group, and a phosphoric acid group.

  Specific examples include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, Polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropyl methacrylate, homopolymers and copolymers of hydroxypropyl acrylate, homopolymers of hydroxybutyl methacrylate Polymers and copolymers, homopolymers and copolymers of hydroxybutyl acrylate Polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide homopolymers and copolymers having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more , Homopolymers and polymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide, polyvinylpyrrolidone, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, etc. Is mentioned.

The binder polymer preferably has a weight average molecular weight of 5000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 250,000. More preferred. The polydispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The binder polymer may be any of a random polymer, a block polymer, a graft polymer, and the like, but is preferably a random polymer.

The binder polymer can be synthesized by a conventionally known method. Solvents used in the synthesis include, for example, tetrahydrofuran, ethylene dichloride, cyclohexanone, methyl ethyl ketone, acetone, methanol, ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy. Examples include 2-propanol, 1-methoxy-2-propyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, toluene, ethyl acetate, methyl lactate, ethyl lactate, dimethyl sulfoxide, and water. These may be used alone or in combination of two or more.
As the radical polymerization initiator used for synthesizing the binder polymer, known compounds such as an azo initiator and a peroxide initiator can be used.

A binder polymer may be used independently or may be used in mixture of 2 or more types.
The content of the binder polymer is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and still more preferably 30 to 70% by mass with respect to the total solid content of the image recording layer. Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use a polymeric compound and a binder polymer in the quantity used as 1 / 9-7 / 3 by mass ratio.

  In general, the mobility of a polymer does not depend on the type of polymer, and changes greatly with the glass transition temperature as a boundary. The mobility is low below the glass transition temperature, and the mobility is high above the glass transition temperature. In order to suppress fogging under white light and to promote image formation, it is necessary to control so that the polymer mobility is low at room temperature under white light and the polymer mobility is high in the heating process. is there. From such a viewpoint, the glass transition temperature of the binder polymer is preferably room temperature or higher. More preferably, it is the range of 25 degreeC-250 degreeC, and the most preferable glass transition temperature range is 30 degreeC-200 degreeC. When the glass transition temperature is within the above range, a large amount of energy is not required for heating, and an effective image formation promoting effect can be obtained efficiently.

<Other image recording layer components>
In the image recording layer of the present invention, additives such as a surfactant, a colorant, a print-out agent, a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic fine particles, and a low molecular weight hydrophilic compound are added as necessary. Can be contained. These will be described below.

<Surfactant>
In the present invention, it is preferable to use a surfactant in the image recording layer in order to promote on-press developability at the start of printing and to improve the coated surface state. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.

The nonionic surfactant used for this invention is not specifically limited, A conventionally well-known thing can be used. For example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol Fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N N- bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid ester, trialkylamine oxide, polyethylene glycol, copolymers of polyethylene glycol and polypropylene glycol.

  The anionic surfactant used in the present invention is not particularly limited, and conventionally known anionic surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinate esters, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy poly Oxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef oil, fatty acid alkyl esters Sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, polyoxyethylene alcohol Ruphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, styrene / maleic anhydride Examples thereof include partial saponification products of polymers, partial saponification products of olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.

The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.

  Of the above surfactants, the term “polyoxyethylene” can be read as “polyoxyalkylene” such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc. These surfactants can also be used.

  More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Also preferred are the fluorosurfactants described in JP-A-62-170950, JP-A-62-226143 and JP-A-60-168144.

Surfactant can be used individually or in combination of 2 or more types.
The content of the surfactant is preferably 0.001 to 10% by mass and more preferably 0.01 to 7% by mass with respect to the total solid content of the image recording layer.

<Colorant>
In the present invention, various compounds other than these may be added as necessary. For example, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Manufactured by Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc. And dyes described in Japanese Patent No. 293247. In addition, pigments such as phthalocyanine pigments, azo pigments, carbon black, and titanium oxide can also be suitably used.

  These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The amount added is preferably 0.01 to 10% by mass with respect to the total solid content of the image recording material.

<Bakeout agent>
In the image recording layer of the present invention, a compound that changes color by an acid or a radical can be added to produce a printout image. As such a compound, for example, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

  Specific examples include brilliant green, ethyl violet, methyl green, crystal violet, basic fuchsin, methyl violet 2B, quinaldine red, rose bengal, methanyl yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, Congo Fred, Benzopurpurin 4B, α-Naphthyl Red, Nile Blue 2B, Nile Blue A, Methyl Violet, Malachide Green, Parafuchsin, Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Kogyo Co., Ltd.], Oil Pink # 312 [Orient Chemical Co., Ltd.], Oil Red 5B [Orient Chemical Co., Ltd.], Oil Scarlet # 308 [Orient Gaku Kogyo Co., Ltd.], Oil Red OG [Orient Chemical Co., Ltd.], Oil Red RR [Orient Chemical Co., Ltd.], Oil Green # 502 [Orient Chemical Co., Ltd.], Spiron Red BEH Special [made by Hodogaya Chemical Co., Ltd.], m-cresol purple, cresol red, rhodamine B, rhodamine 6G, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p- Diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4-pN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4- - dyes and p of diethylamino phenyl imino-5-pyrazolone, p ', p "- hexamethyl triamnotriphenylmethane (leuco crystal violet), and a leuco dye such as Pergascript Blue SRB (manufactured by Ciba-Geigy).

In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoylleucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.

  A suitable addition amount of the dye that changes color by acid or radical is 0.01 to 15% by mass relative to the solid content of the image recording layer.

<Polymerization inhibitor>
In order to prevent unnecessary thermal polymerization of the (C) radical polymerizable compound during production or storage of the image recording layer, it is preferable to add a small amount of a thermal polymerization inhibitor to the image recording layer of the present invention.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t- (Butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the image recording layer.

<Higher fatty acid derivatives, etc.>
In order to prevent polymerization inhibition by oxygen, a higher fatty acid derivative such as behenic acid or behenic acid amide is added to the image recording layer of the present invention, and the surface of the image recording layer is dried during the coating process. It may be unevenly distributed. The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass with respect to the total solid content of the image recording layer.

<Plasticizer>
The image recording layer of the present invention may contain a plasticizer in order to improve the on-press developability.
Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in.
The plasticizer content is preferably about 30% by mass or less based on the total solid content of the image recording layer.

<Inorganic fine particles>
The image recording layer of the present invention may contain inorganic fine particles for the purpose of improving the strength of the cured film in the image area and improving the on-press developability of the non-image area.
As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate or a mixture thereof can be preferably mentioned. Even if they are not photothermally convertible, they can be used for strengthening the film, enhancing interfacial adhesion by surface roughening, and the like.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 to 3 μm. Within the above range, it is possible to form a non-image portion excellent in hydrophilicity that is stably dispersed in the image recording layer, sufficiently retains the film strength of the image recording layer, and hardly causes stains during printing. .
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total solid content of the image recording layer.

<Low molecular hydrophilic compound>
The image recording layer of the present invention may contain a hydrophilic low molecular weight compound for improving on-press developability. Examples of the hydrophilic low-molecular compound include water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Examples thereof include organic carboxylic acids such as salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid and amino acids, and salts thereof.

<Formation of image recording layer>
In the present invention, several modes can be used as a method of incorporating the above-described polymerization initiator, polymerizable compound, binder and other components into the image recording layer. One is a molecular dispersion type image recording layer in which the constituent components are dissolved and applied in an appropriate solvent as described in JP-A-2002-287334, for example. In another embodiment, as described in, for example, JP-A-2001-277740 and JP-A-2001-277742, all or part of the constituent components are encapsulated in microcapsules and contained in the image recording layer. It is a capsule type image recording layer. further. In the microcapsule type image recording layer, the constituent component may be contained outside the microcapsule. Here, it is preferable that the microcapsule-type image recording layer includes a hydrophobic constituent component in the microcapsule and a hydrophilic constituent component outside the microcapsule. In order to obtain better on-press developability, the image recording layer is preferably a microcapsule type image recording layer.

  As a method of microencapsulating the above-mentioned image recording layer constituent components, known methods can be applied. For example, as a method for producing microcapsules, a method using coacervation as described in the specifications of U.S. Pat. Nos. 2,800,047 and 2,800,498, U.S. Pat. -46 method by interfacial polymerization, US Pat. No. 3,418,250, US Pat. No. 3,660,304, by polymer precipitation method, US Pat. No. 3,796,669, isocyanate polyol wall A method using a material, a method using an isocyanate wall material found in US Pat. No. 3,914,511, a urea-formaldehyde system or a urea found in US Pat. Nos. 4001140, 4087376, and 4089802 Formaldehyde-resorcinol system A method using a forming material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as shown in US Pat. No. 4,025,445, and a monomer polymerization as shown in Japanese Patent Publication Nos. 36-9163 and 51-9079 In situ method, British Patent No. 930422, US Pat. No. 3,111,407 spray drying method, British Patent No. 952807, US Pat. No. 967074 specification, etc. It is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Moreover, you may introduce | transduce into the microcapsule wall the compound which has crosslinkable functional groups, such as an ethylenically unsaturated bond which can be introduce | transduced into said binder polymer.

  The average particle size of the microcapsules is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is further more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

The image recording layer of the present invention is applied by preparing a coating solution by dispersing or dissolving the necessary components described above in a solvent. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like. However, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.
The image recording layer of the present invention can also be formed by preparing a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents, and repeatedly applying and drying a plurality of times.

Further, the coating amount (solid content) of the image recording layer on the support obtained after coating and drying varies depending on the use, but generally 0.3 to 3.0 g / m ² is preferable. Within this range, good sensitivity and good film properties of the image recording layer can be obtained.
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

[Support]
The support used for the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. Preferable supports include a polyester film and an aluminum plate. Among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of different elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.

  The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm, and even more preferably from 0.2 to 0.3 mm.

  Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (electrochemical surface roughening treatment that dissolves the surface), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

  The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. However, in general, an electrolyte concentration of 1 to 80% by mass solution, a liquid temperature of 5 to 70 ° C., a current density of 5 to 60 A / d m ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is, but for further improvement in adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation and the like. If necessary, it contains a micropore enlargement treatment, a micropore sealing treatment, and a hydrophilic compound described in Japanese Patent Application Laid-Open Nos. 2001-253181 and 2001-322365. A surface hydrophilization treatment immersed in an aqueous solution can be selected as appropriate.

  The hydrophilization treatment is described in the specifications of US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There are such alkali metal silicate methods. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in the specification of No. 272.

  When using a support with insufficient surface hydrophilicity such as a polyester film as the support of the present invention, it is desirable to apply a hydrophilic layer to make the surface hydrophilic. As the hydrophilic layer, at least one element selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and a transition metal described in JP-A-2001-199175 A hydrophilic layer formed by coating a coating solution containing a colloid of oxide or hydroxide, or organic hydrophilicity obtained by crosslinking or pseudo-crosslinking an organic hydrophilic polymer described in JP-A-2002-79772 A hydrophilic layer having a hydrophilic matrix, a hydrophilic layer having an inorganic hydrophilic matrix obtained by sol-gel conversion comprising hydrolysis, condensation reaction of polyalkoxysilane, titanate, zirconate or aluminate, or a metal oxide A hydrophilic layer made of an inorganic thin film having a surface is preferred. Arbitrariness. Among these, a hydrophilic layer formed by applying a coating solution containing a silicon oxide or a hydroxide colloid is preferable.

  Moreover, when using a polyester film etc. as a support body of this invention, it is preferable to provide an antistatic layer in the hydrophilic layer side of a support body, the opposite side, or both sides. In the case where the antistatic layer is provided between the support and the hydrophilic layer, it also contributes to improving the adhesion with the hydrophilic layer. As the antistatic layer, a polymer layer in which metal oxide fine particles or a matting agent are dispersed as described in JP-A-2002-79772 can be used.

The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion with the image recording layer, good printing durability and good stain resistance can be obtained.
The color density of the support is preferably 0.15 to 0.65 as the reflection density value. Within this range, good image formability by preventing halation during image exposure and good plate inspection after development can be obtained.

[Back coat layer]
After the surface treatment is performed on the support or after the undercoat layer is formed, a back coat can be provided on the back surface of the support, if necessary.
Examples of the back coat include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organometallic compounds or inorganic metal compounds described in JP-A-6-35174. A coating layer made of a metal oxide obtained in this manner is preferred. Among them, it is inexpensive to use a silicon alkoxy compound such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4. It is preferable in terms of easy availability.

(Undercoat layer)
In the planographic printing plate precursor used in the image forming method of the present invention, an undercoat layer can be provided between the image recording layer and the support, if necessary. Since the undercoat layer functions as a heat insulating layer, heat generated by laser exposure is not diffused to the support and can be used efficiently, so that there is an advantage that high sensitivity can be achieved. In addition, in the unexposed area, the image recording layer is easily peeled off from the support, so that the on-press developability is improved.
As the undercoat layer, specifically, a silane coupling agent having an ethylenic double bond reactive group capable of addition polymerization described in JP-A-10-282679, an ethylenic double bond reactive group Preferable examples include phosphorus compounds and the like.
The coating amount (solid content) of the undercoat layer is preferably from 0.1-100 mg / m ^2, and more preferably 3 to 30 mg / m ^2.

[Protective layer]
In the lithographic printing plate precursor of the present invention used in the lithographic printing method of the present invention, image recording is performed as necessary to prevent the occurrence of scratches in the image recording layer, to block oxygen, and to prevent ablation during high-illuminance laser exposure. A protective layer can be provided on the layer.
In the present invention, the exposure is usually performed in the atmosphere, but the protective layer is an image of low molecular weight compounds such as oxygen and basic substances present in the atmosphere that inhibit the image forming reaction caused by exposure in the image recording layer. This prevents the recording layer from being mixed, and prevents the image formation reaction from being hindered by exposure in the air. Therefore, the properties desired for the protective layer are low permeability of low-molecular compounds such as oxygen, furthermore, good transparency of light used for exposure, excellent adhesion to the image recording layer, and It is preferable that it can be easily removed in an on-press development process after exposure. Various studies have been made on protective layers having such characteristics, and are described in detail, for example, in US Pat. No. 3,458,311 and JP-A-55-49729.

Examples of the material used for the protective layer include water-soluble polymer compounds that are relatively excellent in crystallinity. Specific examples include water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, and polyacrylic acid. Among these, when polyvinyl alcohol (PVA) is used as a main component, the best results are obtained for basic characteristics such as oxygen barrier properties and development removability. The polyvinyl alcohol may be partially substituted with an ester, ether or acetal as long as it contains an unsubstituted vinyl alcohol unit for providing the oxygen barrier property and water solubility necessary for the protective layer, and a part of the other You may have a copolymerization component.
Specific examples of the polyvinyl alcohol include those having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, for example, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA- HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420, PVA-613, and L-8 are mentioned.

The components of the protective layer (selection of PVA, use of additives, etc.), coating amount, etc. are appropriately selected in consideration of fogging properties, adhesion, scratch resistance, etc. in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of PVA (that is, the higher the content of unsubstituted vinyl alcohol units in the protective layer), the higher the film thickness, the higher the oxygen barrier property, which is preferable in terms of sensitivity. . Further, in order to prevent unnecessary polymerization reaction during production and storage and unnecessary fogging during image exposure, image line weighting, and the like, it is preferable that the oxygen permeability is not excessively high. Accordingly, the oxygen permeability A at 25 ° C. and 1 atm is preferably 0.2 ≦ A ≦ 20 (cc / m ² · day).

  As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers to the (co) polymer Mass% can be added.

  In addition, adhesion of the protective layer to the image area, scratch resistance, and the like are extremely important in handling the lithographic printing plate precursor. That is, when a protective layer that is hydrophilic because it contains a water-soluble polymer compound is laminated on an image recording layer that is oleophilic, the protective layer is easily peeled off due to insufficient adhesion, and polymerization is inhibited by oxygen at the peeled portion. It may cause defects such as poor film hardening due to.

  On the other hand, various proposals have been made to improve the adhesion between the image recording layer and the protective layer. For example, JP-A-49-70702 and British Patent Application No. 1303578 disclose an acrylic emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer, etc. in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesiveness can be obtained by mixing 20 to 60% by mass and laminating on an image recording layer. Any of these known techniques can be used in the present invention.

  Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (for example, a water-soluble dye) that is excellent in the transparency of light used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved.

The thickness of the protective layer is suitably from 0.1 to 5 μm, particularly preferably from 0.2 to 2 μm.
The method for applying the protective layer is described in detail, for example, in US Pat. No. 3,458,311 and JP-B-55-49729.

[Lithographic printing method]
In the present invention, the image recording layer coated and formed on the support is exposed to the original image by exposing it through a transparent original image having a line image, a halftone dot image, etc. or imagewise exposure with a laser or the like by digital data. Give a relief image of the negative. Examples of light sources suitable for exposure include carbon arc lamps, mercury lamps, xeno lamps, metal hydrado lamps, strobes, ultraviolet rays, and laser beams.

As a method for exposing a scanning exposure lithographic printing plate according to the present invention, a known method can be used without limitation. Desirably, the wavelength of the light source is 250 nm to 420 nm. Specifically, as a gas laser, an Ar ion laser (364 nm, 351 nm, 10 mW to 1 W), a Kr ion laser (356 nm, 351 nm, 10 mW to 1 W), He—Cd Laser (325 nm, 1 mW to 100 mW), solid laser, 1064 nm oscillation mode-locked solid laser such as YAG, YVO _4, etc. (266 nm, 20 to 100 mW), combination of waveguide type wavelength conversion element and AlGaAs, InGaAs semiconductor (380 nm to 400 nm, 5 mW to 100 mW), a combination of a waveguide type wavelength conversion element and AlGaInP, an AlGaAs semiconductor (300 nm to 350 nm, 5 mW to 100 mW), AlGaInN (350 nm to 470 nm, 5 mW to 10 mW) mW), other, N2 laser (337nm as a pulse laser, pulse 0.1~10mJ), XeF (351nm, pulse 10 to 250
mJ), a third harmonic of a 1064 nm oscillation mode-locked solid-state laser such as YAG, YVO ₄ (355 nm, 1 to 4 W), and the like.
In particular, the preferred laser among these is the AlGaInN semiconductor laser (commercially available InGaN-based semiconductor laser 375 nm or 405 nm, 5 to 100 mW) in terms of cost, the high output 355 nm laser in terms of productivity, and the most suitable in terms of wavelength. This is a 266 nm laser that has a small emission spectrum overlap of a white fluorescent lamp and can be highly sensitive.

Moreover, as a lithographic printing plate exposure apparatus of the scanning exposure method, there are an inner drum method, an outer drum method, and a flat bed method as an exposure mechanism, and an inner drum method and a flat bed method are preferable from the viewpoint of quality and cost, and productivity is improved. From the surface, the outer drum system is preferable.
As the inner drum type modulation element, an acoustic spatial modulation element, an electro-optic modulation element, or the like is used to scan laser light. The external drum system is a spatial modulation element such as a one-dimensional shutter array such as a ferroelectric liquid crystal, electro-optic modulation element, GLV (grating light valve), or a two-dimensional array such as DMD (digital micromirror device). Both conventionally known transmissive and reflective spatial modulation elements can be used. In the flat bed method, a method of performing x, y scanning using polarized light by a polygon mirror or the spatial modulation element can be used. The modulation rate is preferably in the range of 1 nanosecond to 100 nanoseconds.
The one-pixel drawing time is preferably as short as possible in order to minimize the competitive reaction with oxygen, but is preferably 1 millisecond or less, more preferably 500 μsec or less, and most preferably 100 μsec or less. If it is 1 millisecond or more, the polymerization inhibition due to oxygen increases, and image formation deteriorates.

In the lithographic printing method of the present invention, as described above, after exposing the lithographic printing plate precursor of the present invention imagewise with a laser, the oil-based ink and the aqueous component are supplied without any development processing steps. Print.
Specifically, after a lithographic printing plate precursor is exposed with a laser, it is mounted on a printing machine without passing through a development process, and after printing the lithographic printing plate precursor on a printing machine, a laser is used on the printing machine. And a method of printing without passing through a development processing step.

After the lithographic printing plate precursor is imagewise exposed with a laser, printing is performed by supplying an aqueous component and an oil-based ink without passing through a development processing step such as a wet development processing step. The image recording layer cured by the above process forms an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed area, the uncured image recording layer is dissolved or dispersed and removed by the supplied aqueous component and / or oil-based ink, and a hydrophilic surface is exposed in that area.
As a result, the aqueous component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the image recording layer in the exposed area, and printing is started. Here, the water-based component or the oil-based ink may be supplied to the printing plate first, but the oil-based ink is first used to prevent the water-based component from being contaminated by the image recording layer in the unexposed area. It is preferable to supply. As the aqueous component and oil-based ink, a dampening water and printing ink for ordinary lithographic printing are used.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

[Example 1]
1. Preparation of planographic printing plate precursor (1) Preparation of support Al: 99.5% by mass or more, Fe: 0.30% by mass, Si: 0.10% by mass, Ti: 0
. It contained 02% by mass, Cu: 0.013% by mass, and the balance was cast by subjecting the molten JIS A1050 aluminum alloy, which is an inevitable impurity, to cleaning. As the cleaning treatment, degassing treatment was performed to remove unnecessary gas such as hydrogen in the molten metal, and ceramic tube filter treatment was further performed. The casting method was a DC casting method. The surface of the solidified ingot with a thickness of 500 mm was chamfered by 10 mm, and homogenized at 550 ° C. for 10 hours so that the intermetallic compound was not coarsened. Subsequently, it was hot-rolled at 400 ° C., subjected to intermediate annealing at 500 ° C. for 60 seconds in a continuous annealing furnace, and then cold-rolled to obtain an aluminum rolled plate having a thickness of 0.30 mm. By controlling the roughness of the rolling roll, to control the center line average roughness R _a after cold rolling to 0.2 [mu] m. Then, it applied to the tension leveler in order to improve planarity. The obtained aluminum plate was subjected to the following surface treatment.
In order to remove the rolling oil on the surface of the aluminum plate, after degreasing at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, three bundled nylon brushes having a bristle diameter of 0.3 mm and the median The aluminum surface was grained using a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a diameter of 25 μm and thoroughly washed with water. This plate was etched by being immersed in a 25% aqueous sodium hydroxide solution at 45 ° C. for 9 seconds, washed with water, further immersed in 20% nitric acid at 60 ° C. for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .

Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Next, a 0.5% by mass hydrochloric acid aqueous solution (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. and nitric acid electrolysis under the condition of an electric quantity of 50 C / dm ² when the aluminum plate is an anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying. This plate was provided with a direct current anodic oxide coating of 2.5 g / m ² at a current density of 15 A / dm ² using 15% sulfuric acid (containing 0.5 mass% of aluminum ions) as an electrolyte, then washed with water, dried, Then, it was treated with a 2.5 mass% aqueous solution of sodium silicate at 30 ° C for 10 seconds. The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

(2) Preparation of lithographic printing plate precursor On the support, an undercoat layer coating solution (1) having the following composition was applied using a bar having a liquid volume of 7.5 ml / m ^2, and then 80 ° C, 10 seconds. And oven dried. Next, the image recording layer coating solution (1) having the following composition was coated with a bar and then oven-dried at 70 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. A protective layer coating solution (1) having the following composition was applied so that the dry coating mass was 0.5 g / m ² and dried at 120 ° C. for 1 minute to obtain a lithographic printing plate precursor (1).

<Undercoat layer coating solution (1)>
・ 300 g of water
・ Methanol 2700g
-The following compound C-1 1.45g

<Image recording layer coating solution (1)>
・ The following polymerization initiator (1) 0.05 g
-The following binder polymer (1) (average molecular weight 30,000) 6.0 g
・ Polymerizable compound 12.4g
Isocyanuric acid EO-modified triacrylate (manufactured by Toa Gosei Co., Ltd., M-315)
・ Royco Crystal Violet 3.0g
・ Thermal polymerization inhibitor 0.1g
N-nitrosophenylhydroxylamine aluminum salt 0.1 g of the following fluorosurfactant (1)
・ Methyl ethyl ketone 70.0g

<Protective layer coating solution (1)>
Polyvinyl alcohol (saponification degree 95 mol%, polymerization degree 800) 40 g
Polyvinylpyrrolidone (molecular weight 50,000) 5g
Poly (vinyl pyrrolidone / vinyl acetate (1/1)) molecular weight of 75 g
950g of water

(Examples 2 to 5)
In Example 1, lithographic printing plate precursors (2) to (5) were obtained in the same manner as in Example 1, except that the binder polymer shown in Table 1 was used instead of the binder polymer (1).

(Examples 6 to 10)
In Example 1, lithographic printing plate precursors (6) to (10) were obtained in the same manner as in Example 1, except that the compounds shown in Table 2 were used instead of the polymerization initiator (1).

(Example 11)
An undercoat layer similar to that described in Example 1 was provided on the support used in Example 1, and then an image recording layer coating solution (2) having the following composition was applied with a bar, and then the oven was heated at 70 ° C. for 60 seconds. Then, an image recording layer having a dry coating amount of 1.0 g / m ² was formed, and a protective layer similar to that described in Example 1 was provided thereon to obtain a lithographic printing plate precursor (11).

<Image recording layer coating solution (2)>
・ The above polymerization initiator (1) 0.05 g
・ Binder polymer (1) (average molecular weight 30,000) 3.0 g
-Polymerizable compound 6.2g
Isocyanuric acid EO-modified triacrylate (manufactured by Toa Gosei Co., Ltd., M-315)
・ Royco Crystal Violet 3.0g
・ Thermal polymerization inhibitor 0.1g
N-nitrosophenylhydroxylamine aluminum salt 0.1 g of the above-mentioned fluorosurfactant (1)
・ The following microcapsule (1) (in terms of solid content) 10.0 g
・ Methyl ethyl ketone 35.0g
・ 3-methoxy-2-propanol 35.0 g
・ Water 10.0g

(Synthesis of microcapsule (1))
As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (manufactured by Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., SR444) 3.15 g, 1 g of 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane (ODB manufactured by Yamamoto Kasei) and 0.1 g of Pionine A-41C (manufactured by Takemoto Yushi Co., Ltd.) are dissolved in 17 g of ethyl acetate. did. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 3 hours. The microcapsule liquid (1) thus obtained was diluted with distilled water so that the solid content concentration became 20% by mass. The average particle size was 0.25 μm in all cases.

2. Exposure and Printing The lithographic printing plate precursor was exposed by the following method, and the exposed exposed original plate thus obtained was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without developing. Dampening solution (EU-3 (Etch solution manufactured by Fuji Photo Film Co., Ltd.) / Water / isopropyl alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (Dainippon Ink and Chemicals, Inc.) After supplying dampening water and ink, printing was performed at a printing speed of 6000 sheets per hour.

(Heating before exposure)
The obtained lithographic printing plate precursor was mounted on an image exposure apparatus, and after preheating the recording layer in the preheated area of the lithographic printing plate precursor to the temperature described in Table 3 by heat conduction from the heating member, 375 nm after 5 seconds. Exposure was performed with a semiconductor laser under the conditions of an output of 2 mW, an outer drum with a circumference of 900 mm, a drum rotation speed of 800 rpm, and a resolution of 2400 dpi.

(Heating during exposure)
The obtained lithographic printing plate precursor was mounted on an image exposure apparatus and exposed with a 375 nm semiconductor laser under the conditions of an output of 2 mW, an outer drum with a peripheral length of 900 mm, a drum rotation speed of 800 rpm, and a resolution of 2400 dpi. Hot hot air was blown from the tip of the nozzle from which hot air was blown onto the area overlapping the exposure area, and simultaneously with image exposure, the recording layer in the heating area including the exposure area in the lithographic printing plate precursor was heated to the temperature shown in Table 3.

(Post-exposure heating)
The obtained lithographic printing plate precursor was mounted on an image exposure apparatus and exposed with a 375 nm semiconductor laser under the conditions of an output of 2 mW, an outer drum with a peripheral length of 900 mm, a drum rotation speed of 800 rpm, and a resolution of 2400 dpi. 15 seconds after laser scanning exposure, hot hot air was blown from the tip of the nozzle, and the recording layer in the heating area including the exposure area was heated to the temperature shown in Table 3.

(Evaluation methods)
1. Printing durability Printing was continued until the removal of the unexposed portion of the image recording layer on the printing machine was completed and ink was not transferred to the printing paper. As the number of printed sheets increases, the image recording layer gradually wears out and the ink acceptability decreases, so the number of printed sheets when the ink density (reflection density) on the printing paper is reduced by 0.1 from the start of printing is durable. Assessed as sex. In the process of evaluating printing durability, no scumming occurred in any of the plates.
2. Sensitivity After printing 100 sheets, it was confirmed that a printed matter free from ink stains in the non-image area was obtained, and 500 sheets were subsequently printed. In the total 600th printed matter, the exposure amount with no unevenness in the ink density in the image area was measured as sensitivity.
3. White Light Safety An unexposed lithographic printing plate precursor was placed under a white fluorescent lamp and placed under a condition where the amount of light was 400 lux on the surface of the lithographic printing plate precursor, and was exposed to light. The lithographic printing plate precursor exposed to the white light is attached to the cylinder of the printing machine SOR-M manufactured by Heidelberg as described above, and after printing 100 sheets, the light is exposed under a white fluorescent light that does not cause ink stains. Time was measured. The longer this time, the better the white light safety.
The evaluation results are shown in Table 3.

(Examples 12 to 13)
Evaluation was performed in the same manner as in Example 1 except that the heating process and the heating temperature were changed as shown in Table 3 in Example 1. The results are shown in Table 3.

(Comparative Examples 1-2)
Evaluation was performed in the same manner as in Examples 1 and 11, except that the lithographic printing plate precursor (1) described in Example 1 and the lithographic printing plate precursor (11) described in Example 11 were each exposed without a heating step. . The results are shown in Table 3.
(Comparative Example 3)
In Example 1, the lithographic printing plate precursor (12) was used in the same manner as in Example 1 except that the following binder polymer (6) having a glass transition temperature lower than room temperature was used instead of the binder polymer (1). Was created and evaluated. The results are shown in Table 3.

  As is clear from Table 3, according to the planographic printing method of the present invention using the planographic printing plate precursor of the present invention (Examples 1 to 13), when the conventional planographic printing plate precursor was used (Comparative Examples 1 to Compared with 3), it can be seen that the sensitivity and printing durability are improved without impairing the safety of white light. Further, since there was no background stain in the printing process, it can be seen that the stain resistance is excellent.

It is a side view which shows the structure of an image exposure apparatus. It is a side view which shows the structure of the exposure apparatus of the post-exposure heating method (heating by a surface). It is a side view which shows the structure of the exposure apparatus of the heating method (heating by a surface) before exposure. It is a perspective view which shows the exposure head (local exposure before exposure) in the image exposure apparatus shown by FIG. 1, and its feeding mechanism. It is a perspective view which shows the exposure head (exposure simultaneous local heating) and its feeding mechanism in the image exposure apparatus shown by FIG. FIG. 2 is a perspective view showing an exposure head (post-exposure local heating) and its feed mechanism in the image exposure apparatus shown in FIG. 1. It is a perspective view which shows the structure of the heating apparatus in an image exposure apparatus. It is a side view of the heating apparatus shown by FIG. It is a perspective view which shows the structure of the coil unit in the heating apparatus shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image exposure apparatus 12 Planographic printing plate precursor 14 Casing 16 Feeding plate 18 Discharge tray 20 Outer drum 22 Chuck mechanism (holding member)
24 guide roller 26 exposure head (exposure means)
28 Feeding mechanism (exposure means)
30 Light source box 32 Light source device 34 Feed mechanism 35 Transport roller 36 Guide member 38 Heating device 40 Heat resistant film 42 Film guide 44 Pressure roller 45 Bend portion 46 Blowout port 48 Heating portion 50 Air supply portion 52 Elastic layer 54 Excitation coil 56 Temperature sensor 58 Lens unit 60 Fiber holder (exposure head)
62 Guide rail 64 Motor unit 66 Screw shaft 68 Carrier (carrier member)
69 Female thread member 70 Optical fiber 72 Laser 74 Heat sink 76 Connector array 78 Cable bear 80 Bare guide 82 Link piece 84 Unloading mechanism 86 Conveying roller 88 Guide member 140 Heating fan unit (heating means)
142 Flexible duct (heating means)
144 Hot air nozzle (heating means)
146 Heating member 148 Coil unit 150 Core metal L Laser light R1, R2 Drum rotation direction S Exposure head feed direction A _IR exposure area A _HT heating area

Claims (5)

  A lithographic printing plate precursor in which an image recording layer containing a polymerization initiator, a polymerizable compound, and a binder polymer is provided on a support is exposed using a light source that emits light within a wavelength range of 250 nm to 420 nm. And an image forming method comprising: a step of heating to a glass transition temperature or higher of the binder polymer.   The image forming method according to claim 1, wherein the heating step is performed at least one of before the exposure step, after the exposure step, or simultaneously with the exposure step.   The image forming method according to claim 1, wherein the polymerization initiator is a compound having an onium ion.   The image forming method according to claim 1, wherein the light source is a laser.   A lithographic printing plate precursor imaged by the method according to any one of claims 1 to 4, wherein printing ink and fountain solution are supplied to remove a non-image portion and printing is performed. Printing method.

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