JP2005274860A - Image forming method and image exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method by which an image can be formed without passing through a liquid development step after image exposure and a lithographic printing plate excellent in printing durability can be obtained, and to provide an image exposure apparatus suitable for the method. <P>SOLUTION: In the image exposure apparatus, a planographic printing plate precursor 12 attached to an outer drum 20 is subjected to scanning exposure with infrared laser L to form an image corresponding to image information in a recording layer of the planographic printing plate precursor 12. At this time, in synchronism with the exposure of an arbitrary exposure area A<SB>IR</SB>with the infrared laser L, ultraviolet radiation emitted from a UV light source portion 40 is combined with the infrared laser L, whereby an irradiation area A<SB>UV</SB>including the exposure area A<SB>IR</SB>with the infrared laser L is irradiated with ultraviolet radiation. The recording layer of the planographic printing plate precursor 12 contains a photothermal conversion agent and a material capable of forming an area whose surface is hydrophobic under heat, wherein an acid generator and microcapsules housing a cation polymerizable compound are used as the material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and an image exposure apparatus. The present invention relates to an exposure apparatus.

  The development of laser technology in recent years has been remarkable, and in particular, solid-state lasers and semiconductor lasers (hereinafter referred to as “infrared lasers” where appropriate) that emit infrared rays with a wavelength of 760 nm to 1200 nm can be easily obtained with high output and small size. Became. In particular, in the field of lithographic printing, these infrared lasers are very useful as a recording light source for a CTP (Computer to Plate) system that directly makes a printing plate from digital data such as a computer.

  Accordingly, many studies have been made on the lithographic printing plate for the CTP system. Among them, as an aim to further streamline the process and solve the waste liquid treatment problem, development-free lithographic printing plate precursors that can be printed on a printing press without being developed after exposure have been studied, and various methods have been studied. Has been proposed.

  One method of eliminating the development process is to mount the exposed lithographic printing plate precursor on the cylinder of the printing press, and supply dampening water and ink while rotating the cylinder, so that the non-image area of the lithographic printing plate precursor There is a method called on-press development that removes the toner. That is, the lithographic printing plate precursor is exposed and mounted on a printing machine as it is, and the processing is completed in a normal printing process. This eliminates the need for a conventional liquid developing process using developing chemicals, thereby making it possible to rationalize the printing preparation process, eliminate the need for developing waste liquid processing, and the like.

  As such a lithographic printing plate precursor, a lithographic printing plate precursor having a cross-linked hydrophilic layer on a substrate and containing a microcapsulated hot-melt material has been proposed (for example, Patent Document 1). reference.). In this printing plate, the microcapsule is collapsed by the action of heat generated in the laser exposure area, the lipophilic substance in the capsule is dissolved, and the hydrophilic layer surface is hydrophobized.

  Other examples using microcapsules that also disintegrate by heat include microcapsules encapsulating a photopolymerizable monomer and a photosensitive resin, and lipophilic components that form an interaction with a three-dimensionally crosslinked hydrophilic layer. A lithographic printing plate precursor using a microcapsule enclosing a liquid crystal has also been proposed (see, for example, Patent Documents 2 and 3).

Although these lithographic printing plate precursors do not require development processing, when a metal plate material such as aluminum having high thermal conductivity is used as a support, heat to be used for image formation diffuses to the support, and the image In the vicinity of the interface of the recording layer with the support, curing did not proceed sufficiently, and there was a problem that the strength of the image area was insufficient and the printing durability was poor.
International Publication No. 94/23954 Pamphlet Japanese Patent Laid-Open No. 62-250454 Japanese Patent No. 3206297

  An object of the present invention, which has been made to solve the above-mentioned conventional problems, is to enable image formation without passing through a special liquid development processing step by scanning exposure using an infrared beam, and has excellent printing durability. Another object is to provide an image forming method capable of obtaining a lithographic printing plate and an image exposure apparatus suitable for the image forming method.

  As a result of intensive investigations, the inventors of the present invention simultaneously exposed the image recording layer to ultraviolet rays simultaneously with scanning exposure with an infrared beam to the image recording layer of the planographic printing plate precursor provided with the recording layer containing the specific microcapsule. The inventors have found that the above object can be achieved and have solved the present invention.

  That is, the image forming method of the present invention is applied to a lithographic printing plate precursor provided with an image recording layer containing a microcapsule encapsulating a polymerizable compound, a polymerization initiator, and a photothermal conversion agent on a support. An image forming method for forming an image by scanning and exposing a lithographic printing plate precursor with an infrared beam to form an image on an image recording layer of the lithographic printing plate precursor, and image recording of the lithographic printing plate precursor An ultraviolet irradiation step of locally irradiating ultraviolet rays during irradiation of an infrared beam with respect to an exposure region included in the ultraviolet irradiation region on an ultraviolet irradiation region including an arbitrary exposure region irradiated with the infrared beam on the layer; It is characterized by including.

  Here, in the ultraviolet irradiation step, the image recording layer of the lithographic printing plate precursor is irradiated with ultraviolet rays having a wavelength selected from a wavelength range of 200 nm to 400 nm in order to efficiently generate a reaction initiator from the polymerization initiator. It is preferable to do.

  The image exposure apparatus of the present invention is an image exposure apparatus used in the image forming method according to claim 1 or 2, wherein the lithographic printing plate precursor can be mounted, and the holding of the mounted lithographic printing plate precursor is held. A member, an exposure unit that scans and exposes the lithographic printing plate precursor held by the holding member with an infrared beam to form an image on an image recording layer of the lithographic printing plate precursor, and an infrared beam is irradiated by the exposure unit. An ultraviolet irradiation area including an arbitrary exposure area in the lithographic printing plate precursor, and an ultraviolet irradiation means for locally irradiating ultraviolet rays during irradiation of an infrared beam with respect to the exposure area included in the ultraviolet irradiation area. And

  The lithographic printing plate precursor according to the invention is characterized in that the recording layer contains microcapsules encapsulating a polymerizable compound, a polymerization initiator, and a photothermal conversion agent. The image forming mechanism of such a lithographic printing plate precursor is as follows. Infrared light energy in image exposure is converted into thermal energy by the photothermal conversion agent, and the heat causes the microcapsule wall to collapse or become permeable, releasing the encapsulated polymerizable compound outside the capsule. (Exudation). Similarly, the reaction initiator generated from the polymerization initiator by the image exposure energy serves as a polymerization initiator for the polymerizable compound released (exuded) out of the capsule, and initiates or advances the polymerization reaction. This is a mechanism in which a hydrophobic region, that is, an image portion is formed.

  However, with only the thermal energy used for image exposure, a sufficient amount (concentration) of an initiator is required to make the capsule wall permeable and further activate the polymerization initiator to advance the curing reaction of the polymerizable compound. It is difficult to generate in the image recording layer, and as described above, in the vicinity of the interface between the recording layer and the support, thermal diffusion (heat absorption) from the recording layer to the support occurs, and the polymerization reaction starts. Since sufficient reaction starting materials necessary for the progress were not sufficiently supplied, the recording layer was not sufficiently cured, and a strong and excellent printing durability could not be formed.

  Here, in the image forming method of the present invention, the lithographic printing plate precursor is scanned and exposed with an infrared beam to form an image (latent image) on the image recording layer of the lithographic printing plate precursor, and the image of the lithographic printing plate precursor The ultraviolet ray irradiation region including the exposure region irradiated with the infrared beam on the recording layer is irradiated with the ultraviolet ray during the irradiation of the infrared beam with respect to the exposure region included in the ultraviolet ray irradiation region, and the polymerization included in the ultraviolet ray irradiation region is performed. The initiator is activated to generate an initiator.

  At this time, the exposure area in the lithographic printing plate precursor is irradiated with an infrared beam, the capsule in the image recording layer is broken by the thermal energy of the infrared beam, and the polymerization initiator is activated to start the reaction with the polymerizable compound. The polymerization reaction with the substance can be started, but the activation of the polymerization initiator existing near the interface of the image recording layer with the support is insufficient due to thermal diffusion to the support only by irradiation with the infrared beam. Therefore, there is a possibility that a sufficient amount of the reaction initiator is not supplied to the polymerizable compound in the vicinity of the interface. Even in such a case, by irradiating the ultraviolet ray irradiation region including the exposure region by the infrared beam simultaneously with the irradiation of the infrared beam, the non-existence that exists near the interface with the support of the image recording layer by the light energy of the ultraviolet ray. By effectively activating the polymerization initiator for the reaction and supplying a sufficient amount of the initiator to the polymerizable compound existing in the vicinity of the interface with the support of the image recording layer, the polymerization reaction between the two is reliably and highly efficient. You can start and progress.

  Here, the activation of the polymerization initiator by the irradiation of ultraviolet rays is uniformly performed up to the deep part of the image recording layer, unlike the case of irradiation by infrared beams. Therefore, the polymerization reaction proceeds efficiently not only in the vicinity of the surface of the image recording layer but also in the vicinity of the interface between the image recording layer and the support due to the effect of heat absorption from the image recording layer to the support. An image having excellent properties can be formed. Further, since the exposure area is scanned and exposed by the infrared beam, and simultaneously, the ultraviolet irradiation area including the exposure area is irradiated with ultraviolet light, the ultraviolet light is applied to the lithographic printing plate before or after the infrared beam exposure. Compared with the case of irradiation, the polymerization initiator is activated more efficiently by the energy of ultraviolet rays.

  Further, in the image exposure apparatus of the present invention, the ultraviolet irradiation means applies the infrared beam to the exposure area included in the ultraviolet irradiation area in the ultraviolet irradiation area including the exposure area in the lithographic printing plate precursor irradiated with the infrared beam by the exposure means. Irradiate ultraviolet rays during irradiation.

  As a result, even if the polymerization reaction between the polymerizable compound and the reaction initiator present in the vicinity of the interface with the recording layer support is not sufficiently advanced by only the thermal energy by the infrared beam, the infrared beam is simultaneously exposed. By irradiating the ultraviolet irradiation area including the exposure area with ultraviolet rays, the release of the polymerizable compound from the capsule and the effect of the unreacted polymerization initiator existing near the interface with the image recording layer support by the ultraviolet rays are also effective. The polymerization reaction between the polymerizable compound present in the vicinity of the interface of the recording layer with the support and the reaction initiating substance can be started and proceeded efficiently and reliably.

  According to the present invention, an image forming method of a lithographic printing plate precursor capable of scanning exposure of an image based on a digital signal and on-press development and having excellent printing durability, and an image exposure apparatus used therefor Can be obtained.

[Configuration of image exposure apparatus]
First, an image exposure apparatus in which an image forming method according to the present invention is preferably implemented will be described with reference to the drawings.

(First embodiment)
1 to 3 show an image exposure apparatus according to a first embodiment of the present invention. The image exposure apparatus 10 scans and exposes a lithographic printing plate precursor 12 with an infrared laser (hereinafter referred to as “IR laser L”) modulated based on digital image information, and the lithographic printing plate precursor 12 has digital image information. An image (latent image) corresponding to is formed. Here, the lithographic printing plate precursor 12 is a so-called non-processed printing plate that does not require special development processing, and is formed on a support made of aluminum or an aluminum alloy and on this support. An image recording layer is provided, and this image recording layer (hereinafter simply referred to as “recording layer”) contains, for example, microcapsules enclosing a cationically polymerizable compound, an acid generator, and a photothermal conversion agent. .

  The acid generator and the photothermal conversion agent may be added to at least one of the inside of the microcapsule and the outside of the microcapsule, that is, in the recording layer matrix, respectively, from the viewpoint of storage stability. The acid generator is preferably added to the recording layer matrix. Moreover, it is preferable from a viewpoint of a sensitivity that a photothermal conversion agent is added in a microcapsule.

  As shown in FIG. 1, the image exposure apparatus 10 is provided with a casing 14 as an outer shell portion of the apparatus. The casing 14 has a side plate portion on one side along the width direction of the apparatus (direction of arrow W). A plate feeding table 16 for mounting a bundle of lithographic printing plate precursors 12 is attached to the platen plate, and a discharge tray 18 for discharging the exposed lithographic printing plate precursor 12 is provided above the plate feeding table 16. ing. In the casing 14, a cylindrical outer drum 20 on which one lithographic printing plate precursor 12 can be attached and detached is rotatably arranged. On the outer peripheral side of the outer drum 20, a chuck mechanism 22 for chucking the front end portion and the rear end portion of the planographic printing plate precursor 12 on the outer drum 20 is provided, and the planographic printing plate precursor 12 is attached to the outer drum 20. A guide roller 24 for winding on the outer peripheral surface is installed.

  An exposure head 26 facing the outer drum 20 and a feed mechanism 28 that supports the exposure head 26 so as to be movable along the sub-scanning direction are disposed in the casing 14. The exposure head 26 and the feed mechanism 28 scan and expose the lithographic printing plate precursor 12 mounted on the outer drum 20 by the IR laser L modulated based on the digital image information, and digitally record the lithographic printing plate precursor 12 on the recording layer. This is for forming an image corresponding to the image information. In the casing 14, a light source box 30 is disposed below the outer drum 20, and an LD light source section 32 (see FIG. 2) for supplying the IR laser L to the exposure head 26 is disposed in the light source box 30. ) Is stored.

  As shown in FIG. 1, the image exposure apparatus 10 is provided with a feeding mechanism 34 for transporting the lithographic printing plate precursor 12 loaded on the plate feeding table 16 in the casing 14 to the outer drum 20. Yes. The feeding mechanism 34 includes a plurality of conveying rollers 35 and a plate-shaped guide member 36 arranged along the feeding path of the planographic printing plate precursor 12. Further, the feeding mechanism 34 separates one lithographic printing plate precursor 12 from a bundle of lithographic printing plate precursors 12 stacked on the plate feeding table 16 at the end on the plate feeding table 16 side. A separation mechanism (not shown) for supplying the planographic printing plate precursor 12 to the feeding path is provided.

  In the image exposure apparatus 10, when the planographic printing plate precursor 12 is conveyed to the vicinity of the upper end of the outer drum 20 by the feeding mechanism 34, the tip of the planographic printing plate precursor 12 is chucked on the outer drum 20 by the chuck mechanism 22. At the same time, the outer drum 20 starts to rotate in a predetermined forward rotation direction (the direction of arrow R1 in FIG. 1). As a result, the planographic printing plate precursor 12 whose tip is constrained on the outer drum 20 is wound while being pressed onto the outer peripheral surface of the outer drum 20 by the guide roller 24.

  In the image exposure apparatus 10, when the planographic printing plate precursor 12 is wound around the outer drum 20 to the rear end portion, the rear end portion of the planographic printing plate precursor 12 is chucked onto the outer drum 20 by the chuck mechanism 22. Thereby, the entire planographic printing plate precursor 12 is brought into close contact with the outer peripheral surface of the outer drum 20, and the mounting of the planographic printing plate precursor 12 to the outer drum 20 is completed. In the image exposure apparatus 10, the IR laser L emitted from the exposure head 26 while moving the exposure head 26 in the sub-scanning direction by the feed mechanism 28 with the lithographic printing plate precursor 12 mounted on the outer drum 20. Is irradiated onto the lithographic printing plate precursor 12 to perform sub-scanning exposure on the lithographic printing plate precursor 12. Further, the image exposure apparatus 10 can perform main scanning on the lithographic printing plate precursor 12 by rotating the outer drum 20 by a rotation amount corresponding to the main scanning pitch in the forward rotation direction in synchronization with the completion of one sub-scan. Become.

As shown in FIG. 3, the exposure head 26 is provided with an optical unit 90 comprising a plurality of lenses or the like and constituting an imaging optical system, and an LD bar array 60 to which the distal ends of two cables 70 are connected. It has been. The other ends of the two cables 70 are connected to the LD driver 72, respectively. The exposure head 26 is mounted on a carrier 68 (see FIG. 2), and moves along the sub-scanning direction (arrow S direction in FIG. 2) together with the carrier 68. Here, the IR laser L emitted from the LD bar array 60 enters the optical unit 90 and forms an image on the lithographic printing plate precursor 12 mounted on the outer drum 20 by the optical unit 90, and has a predetermined shape and size. A beam spot having the same is formed. That is, the exposure head 26 projects the beam spot of the IR laser L onto a predetermined area (referred to as “exposure area A _IR ”) on the planographic printing plate precursor 12, and this exposure area A _IR is projected in the sub-scanning direction and the main scanning direction. By moving in the scanning direction, an image (latent image) having a two-dimensional extent is formed on the planographic printing plate precursor 12.

  As shown in FIG. 2, the feed mechanism 28 includes a pair of guide rails 62 that support the carrier 68 so as to be slidable along the sub-scanning direction and a screw shaft 66 connected to the motor unit 64. A female screw member 69 having a screw hole formed along the sub-scanning direction is fixed to the lower surface portion of the carrier 68, and a screw shaft 66 is screwed into the female screw hole of the female screw member 69. As a result, when the screw shaft 66 is rotated by the motor unit 64, the exposure head 26 is integrated with the carrier 68 along the sub-scanning direction in a direction corresponding to the rotation direction of the screw shaft 66 (forward direction or reverse direction). It moves by a distance corresponding to the amount of rotation of the screw shaft 66. In the image exposure apparatus 10 of this embodiment, sub-scanning with respect to the planographic printing plate precursor 12 is performed only when the exposure head 26 moves forward, that is, when it moves in the sub-scanning direction (arrow S direction). Sometimes, sub-scanning (reciprocal scanning) may be performed.

  In the feed mechanism 28, a tube-shaped cable bear 78 and a hook-shaped bear guide 80 are arranged below the guide rail 62 so as to extend in the sub-scanning direction. The cable bear 78 has a structure in which a large number of link pieces 82 divided in the longitudinal direction are linked and connected in series, and can be bent in the vertical direction. A portion (front end side) of the cable 70 on the exposure head 26 side is inserted into the cable bear 78.

  As shown in FIG. 2, the image exposure apparatus 10 is provided with an ultraviolet irradiation device 38 for irradiating the lithographic printing plate precursor 12 with ultraviolet UV. As shown in FIG. 2, the ultraviolet irradiation device 38 includes a UV light source unit 40 mounted on a carrier 68 and a beam combiner 92 that combines the ultraviolet light UV emitted from the UV light source unit 40 with the IR laser L. I have. As shown in FIG. 3, the optical unit 90 includes a cylinder lens 44, a collimator lens 46, a λ / 2 plate 48, a liquid crystal shutter array 50, a λ / 2 plate 52, from the LD bar array 60 toward the outer drum 20 side. A deflecting beam splitter 54, a first imaging lens 56, and a second imaging lens 58 are arranged in this order. Further, between the two imaging lenses 56 and 58 in the optical unit 90, the beam combiner 92 of the ultraviolet irradiation device 38 is inserted on the optical axis.

  In the optical unit 90, when the IR laser L is emitted from the LD bar array 60, the IR laser L enters the cylinder lens 44, the divergence angle is adjusted by the cylinder lens 44, and the collimator lens 46 is incident. The collimating lens 46 emits each IR laser L to the λ / 2 plate 48 as parallel light to the optical axis L of the optical unit 90. At this time, the deflection direction of the IR laser L emitted from the semiconductor laser 72 in the on state is parallel to the active layer of the LD array, as shown in FIG. The λ / 2 plate 48 deflects and rotates the IR laser L emitted from the collimating lens 46 in the clockwise direction by 45 ° on the paper surface and emits it to the liquid crystal shutter array 50. At this time, the liquid crystal shutter array 50 allows the IR laser L corresponding to the off-state pixel to pass through without being deflected and rotated, and the IR laser L corresponding to the on-state pixel to be deflected and rotated 90 ° clockwise. And let it pass.

  The IR laser L that has passed through the liquid crystal shutter array 50 is rotated 45 ° clockwise by the λ / 2 plate 52 and emitted to the deflecting beam splitter 54. The deflecting beam splitter 54 allows the IR laser L corresponding to the off-state pixel to pass through without being deflected and rotated, and reflects (deflects) the IR laser L corresponding to the on-state pixel downward, and turns it on. The IR laser L corresponding to this pixel is allowed to pass through without being deflected. At this time, the off-state IR laser L deflected downward is incident on a laser absorber (not shown) mounted on the carrier 68 and absorbed, and the on-state IR laser L passed without being deflected. L is imaged on the planographic printing plate precursor 12 as a beam spot by the two imaging lenses 56 and 58.

  As shown in FIG. 3B, the UV light source section 40 of the ultraviolet irradiation device 38 is provided with a UV lamp 94 as a light source of ultraviolet UV, and a reflecting surface curved in a concave shape below the UV lamp 94. The hemispherical reflector 96 having the above is disposed, and the UV lamp 94 is located in the reflector 96. As a result, some of the ultraviolet rays UV emitted from the UV lamp 94 are directly incident on the beam combiner 92, and most of the remaining rays are reflected by the reflector 96 and enter the beam combiner 92.

  The ultraviolet irradiation device 38 includes a power supply unit 98 for supplying power to the UV lamp 94, and the power supply unit 98 is housed in the light source box 30 together with the LD light source unit 32 as shown in FIG. ing. The power supply unit 98 is connected to the UV lamp 94 via a power supply cable 100 inserted through the cable bear 78. The power supply unit 98 is controlled by a control unit (not shown) of the image exposure apparatus 10 to supply and stop supplying power to the UV lamp 94. In the image exposure apparatus 10, the power supply unit 98 controlled by the control unit emits the UV lamp 94 in synchronization with the start of exposure of the lithographic printing plate precursor 12 by the IR laser L, and turns off the UV lamp 94 in synchronization with the completion of exposure. To do.

The beam synthesizer 92 of the ultraviolet irradiation device 38 passes the IR laser L without reflection, but reflects the ultraviolet UV incident from the UV light source 40 at a right angle so as to be incident on the planographic printing plate precursor 12. To do. Thereby, as shown in FIG. 2, the ultraviolet ray UV irradiates a predetermined irradiation area A _UV on the lithographic printing plate precursor 12 mounted on the outer drum 20.

Here, the irradiation area A _UV has a size sufficiently larger than the exposure area A _IR along the sub-scanning direction and the main scanning direction, and the center of the irradiation area A _UV on the planographic printing plate precursor 12. It substantially coincides with the center of the exposure area A _IR . Thereby, the ultraviolet ray UV emitted from the UV light source unit 40 is irradiated to the irradiation area A _UV including the exposure area AIR during the exposure of the arbitrary exposure area A _IR by the IR laser L. Accordingly, the exposure area A _IR is exposed by the IR laser L, and at the same time, the irradiation area A _UV including the exposure area A _IR is locally irradiated with the ultraviolet rays UV. The polymerization initiator contained in the recording layer in the irradiation area A _UV can be activated by _{UV UV} .

In the ultraviolet irradiation device 38, an integrator illumination optical system is interposed between the UV light source unit 40 and the beam combiner 92, and the irradiation area A _UV on the planographic printing plate precursor 12 is Koehler illuminated by this integrator illumination optical system. By doing so, the light quantity distribution of the ultraviolet rays UV irradiated on the planographic printing plate precursor 12 may be made uniform.

  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 transporting the planographic printing plate precursor 12 sent from the outer drum 20 to the entrance of the discharge path to the discharge tray 18. The printing plate precursor 12 is discharged onto the discharge tray 18.

In the ultraviolet irradiation device 38 of the present embodiment, the UV lamp 94 is used as the ultraviolet light source (UV light source). Instead of such a UV lamp 94, a plurality of GaN emitting lasers in the ultraviolet region are used. A semiconductor laser may be used as the UV light source. In this case, a structure similar to that of the LD light source unit 32 can be applied, and a plurality of semiconductor lasers arranged on the heat sink are housed in the light source box 30 and a plurality of semiconductor lasers connected to these semiconductor lasers are accommodated. By holding the tip of the optical fiber with a fiber holder mounted on the carrier 68, the irradiation region A _UV in the planographic printing plate precursor can be irradiated with ultraviolet rays UV while the carrier 68 is moved.

When a semiconductor laser is used as the UV light source as described above, the output of ultraviolet UV irradiated to the lithographic printing plate precursor 12 can be easily increased or decreased by increasing or decreasing the number of semiconductor lasers installed. Compared with the ultraviolet irradiation device 38 using the UV lamp 94 as a UV light source, it is possible to irradiate the lithographic printing plate precursor 12 with higher output ultraviolet UV. Therefore, when an ultraviolet irradiation apparatus using a semiconductor laser as a UV light source is applied to the image exposure apparatus 10, the speed of the carrier 68 (sub-scanning speed) is greatly increased in order to improve the exposure processing capability of the image exposure apparatus 10. Even when the lithographic printing plate precursor 12 is raised, it is possible to easily increase the output of the ultraviolet rays UV in accordance with the increase in the sub-scanning speed and reliably irradiate the planographic printing plate precursor 12 with the required amount of ultraviolet rays UV.
(Configuration of lithographic printing plate precursor)
Next, the configuration of a lithographic printing plate precursor that can be suitably applied to the method of the present invention and that can form an image without requiring a liquid development processing step will be described in detail.

The lithographic printing plate precursor according to the invention comprises an image recording layer containing a microcapsule encapsulating a polymerizable compound on a support, a polymerization initiator, and a photothermal conversion agent.
(Image recording layer)
(Microcapsules encapsulating polymerizable compounds)
Examples of the polymerizable compound used in the present invention include a cationic polymerizable compound and a radical polymerizable compound.
<Cationically polymerizable compound>
The cationically polymerizable compound used in the present invention is not particularly limited as long as it is a compound having a cationically polymerizable group in the molecule. Among them, a compound having a vinyloxy group or an epoxy group is preferably used.

  Examples of the cationically polymerizable compound having a vinyloxy group suitable for the present invention include compounds described in JP-A-2002-29162.

  Specifically, tetramethylene glycol divinyl ether, trimethylolpropane trivinyl ether, tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, 1,4-bis {2- (vinyloxy) ethyloxy } Benzene, 1,2-bis {2- (vinyloxy) ethyloxy} benzene, 1,3-bis {2- (vinyloxy) ethyloxy} benzene, 1,3,5-tris {2- (vinyloxy) ethyloxy} benzene, 4,4′-bis {2- (vinyloxy) ethyloxy} biphenyl, 4,4′-bis {2- (vinyloxy) ethyloxy} diphenyl ether, 4,4′-bis {2- (vinyloxy) ester Ruoxy} diphenylmethane, 1,4-bis {2- (vinyloxy) ethyloxy} naphthalene, 2,5-bis {2- (vinyloxy) ethyloxy} furan, 2,5-bis {2- (vinyloxy) ethyloxy} thiophene, , 5-bis {2- (vinyloxy) ethyloxy} imidazole, 2,2-bis [4- {2- (vinyloxy) ethyloxy} phenyl] propane {bis (vinyloxyethyl) ether of bisphenol A}, 2,2- Bis {4- (vinyloxymethyloxy) phenyl} propane, 2,2-bis {4- (vinyloxy) phenyl} propane, and the like, among others, 2,2-bis [4- [2- (vinyloxy) ethyloxy] ] Phenyl] propane, bis (vinyloxyethyl) ether of bisphenol A, 2,2 Bis [4- (vinyloxymethyl) phenyl] propane, 2,2-bis [4- (vinyloxy) phenyl] propane is particularly preferred. The present invention is not limited to these.

  As the cationically polymerizable compound having an epoxy group suitable for the present invention, a compound having two or more epoxy groups is preferable, and a glycidyl ether compound obtained by a reaction of a polyhydric alcohol or a polyhydric phenol with epichlorohydrin or the like. Examples thereof include a prepolymer, and a polymer or copolymer of glycidyl acrylate or glycidyl methacrylate.

  Specific examples include propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl ether of hydrogenated bisphenol A, hydroquinone di- Glycidyl ether, resorcinol diglycidyl ether, diglycidyl ether or epichlorohydrin polyadduct of bisphenol A, diglycidyl ether or epichlorohydrin polyadduct of bisphenol F, diglycidyl ether of halogenated bisphenol A or epichloro Hydrine polyadduct, diglycidyl ether of biphenyl type bisphenol or epichlorohydrin polyadduct, novolac resin Examples include glycidyl etherified compounds, methyl methacrylate / glycidyl methacrylate copolymer, ethyl methacrylate / glycidyl methacrylate methacrylate, and the like. Among them, diglycidyl ether or epichlorohydrin polyadduct of bisphenol A, A diglycidyl ether of biphenyl type bisphenol or an epichlorohydrin heavy compound is particularly preferred. The present invention is not limited to these.

Commercially available products of the above compounds include, for example, Epicoat 1001 (molecular weight: about 900, epoxy equivalent: 450 to 500), Epicoat 1002 (molecular weight: about 1600, epoxy equivalent: 600 to 700), Epicoat 1004 (about) manufactured by Japan Epoxy Resin Co., Ltd. 1060, epoxy equivalent 875-975), Epicoat 1007 (molecular weight about 2900, epoxy equivalent 2000), Epicoat 1009 (molecular weight about 3750, epoxy equivalent 3000), Epicoat 1010 (molecular weight about 5500, epoxy equivalent 4000), Epicoat 1100L (epoxy equivalent) 4000), Epikote YX31575 (epoxy equivalent 1200), Sumitomo Chemical Co., Ltd. Sumiepoxy ESCN-195XHN, ESCN-195XL, ESCN-195XF, and the like.
<Radically polymerizable compound>
The radically polymerizable compound used in the present invention is not particularly limited as long as it has an ethylenically unsaturated bond in the molecule.

  Examples of the functional group containing an ethylenically unsaturated bond include an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group. A compound having at least one, preferably two or more of these is preferably used. Such a group of compounds is widely known as a monomer or a crosslinking agent for a radically polymerizable compound in the industrial field, and in the present invention, these can be used without any particular limitation. The chemical form is a monomer, a prepolymer, that is, a dimer, a trimer, an oligomer, a polymer or a copolymer, or a mixture thereof.

  Examples of the radical polymerizable compound suitable for the present invention include compounds having an ethylenically unsaturated group described in JP-A No. 2001-277740.

  Typical examples are trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol. Examples include di (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, adducts of trimethylolpropane diacrylate and xylylene diisocyanate.

Examples of the polymer or copolymer in the form of a compound having an ethylenically unsaturated group include allyl methacrylate copolymer, allyl methacrylate / methacrylic acid copolymer, allyl methacrylate / ethyl methacrylate copolymer, and allyl methacrylate. / Butyl methacrylate copolymer. Among them, a copolymer of acrylic methacrylate is particularly preferable. The present invention is not limited to these.
<Other polymerizable compounds>
Furthermore, the inclusion of the microcapsule according to the present invention may contain a thermopolymerizable compound having the following heat-reactive group, in addition to the polymerizable compound.

Examples of the thermally polymerizable group include an isocyanate group that performs an addition reaction, a block thereof, and a functional group having an active hydrogen atom that is a reaction partner with the cationic polymerizable group or the ethylenically unsaturated group (for example, Amino group, hydroxy group, carboxy group, etc.),
A carboxy group that performs a condensation reaction, and a hydroxy group and an amino group that are reaction partners thereof,
Examples thereof include an acid anhydride that undergoes a ring-opening addition reaction, and an amino group and a hydroxy group that are reaction partners thereof.

  Suitable compounds having an isocyanate group for the present invention include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, xylylene diisocyanate, naphthalene diisocyanate, cyclohexanephenylene diisocyanate, isophorone diester. Examples thereof include isocyanate, hexamethylene diisocyanate, cyclohexyl diisocyanate, and compounds obtained by blocking these with alcohol or amine.

  Examples of the compound having an amino group suitable for the present invention include ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, propylenediamine, and polyethyleneimine.

  Examples of the compound having a hydroxy group suitable for the present invention include compounds having a terminal methylol group, polyhydric alcohols such as pentaerythritol, and bisphenol / polyphenols.

  Examples of the compound having a carboxy group suitable for the present invention include aromatic polyvalent carboxylic acids such as pyromellitic acid, trimellitic acid, and phthalic acid, and aliphatic polyvalent carboxylic acids such as adipic acid.

  Suitable acid anhydrides for the present invention include pyromellitic acid anhydride and benzophenone tetracarboxylic acid anhydride.

  Further, in the image recording layer according to the present invention, it is necessary to add a photothermal conversion agent and a polymerization initiator to at least one of the microcapsule and the recording layer matrix. These components are added to the microcapsule. At this time, the resultant is dissolved or dispersed in the same solvent as that of the inclusion, and is included. Further, usable photothermal conversion agents and polymerization initiators will be described later.

  As a method for microencapsulating each of the above components, known methods can be applied. For example, as a method for producing microcapsules, a method using coacervation as shown in U.S. Pat. Nos. 2,800,547 and 2,800,498, British Patent No. 990443, U.S. Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, No. 42-446. No. 42-711, interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304, method of polymer precipitation, US Pat. No. 3,796,669, method using isocyanate polyol wall material, US Pat. US Pat. No. 3,914,511 shows a method using an isocyanate wall material, US Pat. Nos. 4001140, 4087376, and 4089802 use a urea-formaldehyde-based or urea-formaldehyde-resorcinol-based wall forming material, A method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as shown in U.S. Pat. No. 4,025,445, an in situ method by monomer polymerization as shown in JP-B Nos. 36-9163 and 51-9079, British Patent No. 930422, US Pat. No. 3,111,407 And the like, but are not limited thereto, such as the spray drying method found in British Patent Nos. 952807 and 967074.

  A preferable microcapsule wall material used in the present invention has properties that it can swell in a coating solvent and can form a three-dimensional crosslink. 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. Further, a compound having a thermally reactive group may be introduced into the microcapsule wall.

  The average particle diameter of the obtained microcapsules is preferably 0.01 to 3.0 μm, more preferably 0.05 to 2.0 μm, and particularly preferably 0.10 to 1.0 μm. Within this range, good resolution and stability over time can be obtained.

  In addition, such microcapsules may be combined with each other by heat, or may not be combined. In short, the inclusion in the microcapsule oozes out of the capsule surface or outside the microcapsule by image exposure using an infrared beam and causes a chemical reaction with the reaction initiator generated from the polymerization initiator described later, or the reaction starts. Any material can be used as long as it has a structure capable of entering a microcapsule wall and causing a chemical reaction to be cured. Further, such a polymerizable compound may react with a later-described hydrophilic resin or low molecular compound added to the recording layer as an optional component. In addition, the microcapsules may be reacted with each other by providing the microcapsules with different functional groups that are thermally reacted with each other. Therefore, it is preferable for image formation that the microcapsules are melted and united by heat, but it is not essential.

  The amount of such microcapsules added to the recording layer is preferably 50% by mass or more, and more preferably 70 to 98% by mass in terms of solid content in terms of solid content. Within this range, a good image can be formed and good printing durability can be obtained.

  In the recording layer containing microcapsules, a solvent capable of dissolving the inclusions of the microcapsules and swelling the wall material can be added to the microcapsule dispersion medium. By adding such a solvent, the diffusion of the microcapsule inclusions outside the capsule is promoted during image exposure.

  Such a solvent depends on the microcapsule dispersion medium, the material of the microcapsule wall, the wall thickness, and the inclusion, but can be easily selected from many commercially available solvents. For example, in the case of a water-dispersible microcapsule comprising a crosslinked polyurea or polyurethane wall, alcohols, ethers, acetals, esters, ketones, polyhydric alcohols, amides, amines, fatty acids and the like are preferable.

  Specific compounds include methanol, ethanol, tertiary butanol, n-propanol, tetrahydrofuran, methyl lactate, ethyl lactate, methyl ethyl ketone, propylene glycol monomethyl ether, ethylene glycol diethyl ether, ethylene glycol monomethyl ether, γ-butyl lactone, N, Examples include N-dimethylformamide and N, N-dimethylacetamide, but the present invention is not limited thereto. Two or more of these solvents may be used in combination. A solvent that does not dissolve alone in the microcapsule dispersion medium but dissolves by mixing the above-mentioned solvents can also be used.

The amount of such a solvent added depends on the combination of materials, but usually 5 to 95% by mass of the recording layer coating solution is effective, and a preferable range is 10 to 90% by mass, and a more preferable range is 15 It is -85 mass%.
(Photothermal conversion agent)
In the recording layer according to the present invention, it is necessary to add a photothermal conversion agent having a function of absorbing light energy and converting it into heat. In this case, a photothermal conversion agent may be added to at least one of the microcapsule and the recording layer matrix. In the present invention, from the viewpoint that infrared energy can contribute to image forming efficiency, It is preferable to add.

  As a photothermal conversion agent, what is necessary is just a substance which absorbs infrared rays, especially near infrared rays (wavelength 700-2000 nm), and various well-known pigments, dyes or pigment | dyes, and metal microparticles | fine-particles can be used.

  For example, the pigments, dyes or dyes described in JP 2001-301350 A, JP 2002-137562 A, Journal of the Japan Printing Society, Vol. 38, pages 35 to 40 (2001) “New imaging materials, 2. Near-infrared absorbing dyes”, etc. Dyes and fine metal particles are preferably used. As these pigments and metal fine particles, those subjected to a known surface treatment can be used as necessary.

  More specifically, as dyes or pigments, U.S. Pat. Nos. 4,756,993 and 4,973,572, JP-A-10-268512, JP-A-11-235883, JP-B-5-13514, JP-A-5-19702, and JP-A-2001-2001. Examples thereof include cyanine dyes, polymethine dyes, azomethine dyes, squarylium dyes, pyrylium and thiopyrylium salt dyes, dithiol metal complexes, and phthalocyanine dyes described in No. 347765. Particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and phthalocyanine dyes.

  Examples of the pigment include insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments, Kinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Of these, carbon black is preferred.

  As the metal fine particles, fine particles of Ag, Au, Cu, Sb, Ge and Pb are preferable, and fine particles of Ag, Au and Cu are more preferable.

  Specific examples of particularly suitable photothermal conversion agents are shown below, but the present invention is not limited thereto. Note that (IR-1) to (IR-11) are hydrophilic photothermal conversion agents suitable for addition to the image recording layer matrix, and (IR-21) to (IR-29) are A lipophilic photothermal conversion agent suitable for inclusion in capsules.

When added to the microcapsule, the addition amount of the photothermal conversion agent is preferably 1 to 50% by mass, more preferably 3 to 25% by mass based on the total content of the microcapsules. On the other hand, when the photothermal conversion agent is added to the image recording layer matrix, 1 to 50% by mass of the solid content of the recording layer is preferable, and 3 to 25% by mass is more preferable. In this range, good sensitivity can be obtained without impairing the film strength of the recording layer.
(Polymerization initiator)
In the recording layer according to the present invention, it is necessary to add a polymerization initiator that generates a reaction initiating substance by heat and starts and accelerates the reaction of the polymerizable compound in the image recording layer matrix. In this case, a polymerization initiator may be added to at least one of the inside of the microcapsule and the image recording layer matrix. From the viewpoint of stability, the recording layer matrix is present so as to be separated from the polymerizable compound and the microcapsule wall. It is preferable to add in.

  Examples of the polymerization initiator used in the present invention include known acid generators or radical generators. The former is used when a cationic polymerizable compound is used as the polymerizable compound in the microcapsule. The latter is also used when a radical polymerizable compound is used as the polymerizable compound.

  It is also possible to form a printing system in combination with a dye that changes color due to the generated acid or radical.

Hereinafter, these polymerization initiators will be described.
<Acid generator>
In the present invention, the acid generator used in combination with the cationic polymerizable compound is not particularly limited as long as it generates heat by absorbing heat or ultraviolet rays. As such an acid generator, known acid precursors and acid generators are preferably used, and examples thereof include acid generators for print-out image formation, acid generators used in microresists, and the like. It is done.

  More specifically, organic halogen compounds typified by trihalomethyl-substituted heterocyclic compounds described in JP-A-2002-29162, JP-A-2002-46361, JP-A-2002-137562, etc., iminosulfonates, etc. And compounds capable of generating a sulfonic acid by photolysis represented by (2), disulfone compounds, onium salts (for example, iodonium salts, diazonium salts, sulfonium salts, etc.). Moreover, the compound which introduce | transduced the group or compound which generate | occur | produces these acids into the principal chain or side chain of a polymer can also be used.

  Hereinafter, although the specific example of the acid generator which can be used conveniently for this invention is given, this invention is not limited to these.

  Two or more of the above acid generators can be used in combination.

The addition amount of the acid generator is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass based on the total solid content of the recording layer. Within this range, good reaction initiation or acceleration effect can be obtained without impairing on-press developability.
<Radical generator>
In the present invention, the radical generator used in combination with the radical polymerizable compound is not particularly limited as long as it generates heat by absorbing heat or ultraviolet rays. As such a radical generator, a known thermal radical generator is preferably used, and examples thereof include a photoinitiator for photoradical polymerization.

  Specifically, compounds that generate sulfonic acid, disulfone compounds, onium salts (for example, iodonium salts, diazonium salts, sulfonium salts, etc.) mentioned as the acid generator may also be used as radical generators. it can.

  Specific examples include the compounds (AI-1) to (AI-17), (AN-1) to (AN-8) and (AS-1) to (AS-12) mentioned above. However, the present invention is not limited to these.

  Two or more of the above radical generators can be used in combination.

  The addition amount of the radical generator is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, based on the total solid content of the recording layer. Within this range, good reaction initiation or acceleration effect can be obtained without impairing on-press developability.

  In the method of the present invention, polymerization released from the capsule wall material into the system by initiating / promoting decomposition of the polymerization initiator (acid generator or radical generator) by irradiation with ultraviolet rays in the ultraviolet irradiation step. The effect of improving the efficiency of the curing reaction between the functional compound and the polymerization initiator can be obtained. For this reason, the wavelength of the ultraviolet light is preferably set to a wavelength that efficiently initiates and accelerates the decomposition of the polymerization initiator, and the wavelength of the ultraviolet light is selected from a wavelength range of 100 nm to 450 nm, and more preferably 200 nm to 400 nm. Selected.

  The recording layer according to the present invention can be added with a compound that changes color by an acid or a radical in order to generate a printout image. As such a compound, 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 a ratio of 0.01 to 10% by mass with respect to the solid content of the recording layer.
(Hydrophilic resin)
The recording layer matrix according to the present invention may contain a hydrophilic resin in order to improve the on-press developability and the film strength of the recording layer itself.

  As hydrophilic resin, what has hydrophilic groups, such as a hydroxyl group, an amino group, a carboxy group, a phosphoric acid group, a sulfonic acid group, an amide group, is preferable, for example.

  In addition, the hydrophilic resin reacts with a functional group such as an ethylenically unsaturated group, a cationic polymerizable group, or a thermally reactive group that the thermally polymerizable compound has in the polymerizable compound encapsulated in the microcapsule. Since crosslinking improves the image strength and further increases printing durability, it is preferable to select a resin having a group that reacts with these functional groups as the hydrophilic resin. For example, when the cationically polymerizable compound has a vinyloxy group or an epoxy group, the hydrophilic resin preferably has a hydroxy group, a carboxy group, a phosphoric acid group, a sulfonic acid group, or the like. Among these, a hydrophilic resin having a hydroxy group or a carboxy group is preferable.

  Specific examples of hydrophilic resins include gum arabic, casein, gelatin, starch derivatives, soya gum, hydroxypropylcellulose, methylcellulose, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-malein 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, hydroxypropyl acrylate Homopolymers and copolymers, hydroxybutyl methacrylate homopolymers and copolymers, Homopolymers and copolymers of butyl acrylate, polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate having a degree of hydrolysis of at least 60% by weight, preferably at least 80% by weight, polyvinyl formal, polyvinyl pyrrolidone, acrylamide Homopolymers and copolymers, methacrylamide homopolymers and copolymers, N-methylolacrylamide homopolymers and copolymers, 2-acrylamido-2-methyl-1-propanesulfonic acid homopolymers and copolymers, 2-methacryloyloxyethylphosphonic acid And homopolymers and copolymers thereof.

  The amount of the hydrophilic resin added is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the recording layer.

Further, the hydrophilic resin may be used after being cross-linked to such an extent that an unexposed portion can be developed on-press on a printing press. Examples of crosslinking agents used to crosslink hydrophilic resins include glyoxal, melamine formaldehyde resins, aldehydes such as urea formaldehyde resins, N-methylol urea, N-methylol melamine, methylol compounds such as methylolated polyamide resins, and divinyl. Active vinyl compounds such as sulfone and bis (β-hydroxyethylsulfonic acid), epoxy compounds such as epichlorohydrin, polyethylene glycol diglycidyl ether, polyamide, polyamine, epichlorohydrin adduct, polyamide epichlorohydrin resin, monochloroacetic acid Ester compounds such as esters and thioglycolic acid esters, polycarboxylic acids such as polyacrylic acid and methyl vinyl ether / maleic acid copolymer, boric acid, titanyl sulfate, C , Al, Sn, V, inorganic crosslinking agents such as Cr salts, and modified polyamide polyimide resin. In addition, a crosslinking catalyst such as ammonium chloride, a silane coupling agent, a titanate coupling agent can be used in combination.
(Other additives)
In addition to the above, various compounds may be added to the recording layer matrix according to the present invention as necessary.
<Multifunctional monomer>
In order to further improve the printing durability, a polyfunctional monomer can be added. As this polyfunctional monomer, those exemplified as the monomer put in the microcapsule can be used. Among them, preferable monomers include trimethylolpropane triacrylate, pentaerythritol triacrylate, and the like. The addition amount of the polyfunctional monomer is preferably 1 to 10% by mass and more preferably 0.5 to 5.0% by mass in the total solid content of the recording layer.
<Thermal polymerization inhibitor>
In the present invention, it is desirable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the ethylenically unsaturated compound during preparation or storage of the recording layer coating solution. Suitable thermal polymerization inhibitors 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-t-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt and the like. The addition amount of the thermal polymerization inhibitor is preferably 0.01 to 5% by mass in the total solid content of the recording layer.
<Higher fatty acids or their derivatives>
In the recording layer matrix according to the present invention, if necessary, a higher fatty acid such as behenic acid or behenic acid amide or a derivative thereof is added to prevent polymerization inhibition by oxygen, and drying after coating is performed. In this process, it may be unevenly distributed on the surface of the recording layer. The addition amount of the higher fatty acid or its derivative is preferably 0.1 to 10% by mass in the total solid content of the recording layer.
<Inorganic fine particles>
Inorganic fine particles may be added to the recording layer matrix according to the present invention, and suitable examples of inorganic fine particles include silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof. Even if they are not photothermally convertible, they can be used for strengthening the film and enhancing interfacial adhesion by surface roughening.

  The average particle size of the inorganic fine particles is preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm. Within this range, the microcapsules and the metal microparticles of the photothermal conversion agent are both stably dispersed in the hydrophilic resin, the film strength of the recording layer is sufficiently maintained, and the non-hydrophilic material has excellent hydrophilicity that does not easily cause printing stains. An image portion can be formed.

Such inorganic fine particles can be easily obtained as a commercial product such as a colloidal silica dispersion. The content of the inorganic fine particles in the recording layer is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the recording layer.
<Surfactant>
In the recording layer matrix according to the present invention, JP-A-2-195356, JP-A-59-121044, JP-A-4-12044 are used for improving the dispersion stability of the recording layer, plate making and printing performance, and coating properties. Nonionic, anionic, cationic, amphoteric or fluorine-based surfactants described in No. 13149 and Japanese Patent Application No. 2001-169731 can be added. A suitable addition amount of these surfactants is 0.005 to 1% by mass of the total solid content of the recording layer.
<Plasticizer>
In the recording layer matrix according to the present invention, a plasticizer can be added as needed to impart flexibility of the coating film. For example, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate and the like are used.
(Formation of image recording layer)
The recording layer according to the present invention is applied by preparing a coating solution by 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-butyrolactone, 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 recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the use, but is generally preferably 0.5 to 5.0 g / m ² . As the coating amount decreases, the apparent sensitivity increases, but the film properties of the recording layer that performs the image recording function decrease.

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.
[Overcoat layer]
The lithographic printing plate precursor according to the present invention is provided on the recording layer in order to protect the hydrophilic recording layer surface from contamination with lipophilic substances during storage and fingerprint trace contamination due to finger contact during handling. An overcoat layer containing a water-soluble resin described in JP-A-162961 and JP-A-2002-19318 can be provided.

  Specific examples of water-soluble resins used in the overcoat layer include natural gums such as gum arabic, water-soluble soybean polysaccharide, fiber derivatives (eg, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), modified products thereof, For synthetic polymers such as white dextrin, pullulan, and enzymatically degraded etherified dextrin, polyvinyl alcohol (polyvinyl acetate having a hydrolysis rate of 65% or more), polyacrylic acid, its alkali metal salt or amine salt, and polyacrylic acid Polymer, alkali metal salt or amine salt thereof, polymethacrylic acid, alkali metal salt or amine salt thereof, vinyl alcohol / acrylic acid copolymer and alkali metal salt or amine salt thereof, polyacrylamide, copolymer thereof, polyhydroxy Ethyl acrylate, Polyvinyl Lupyrrolidone, its copolymer, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, its alkali metal salt or amine salt, poly-2 -Acrylamido-2-methyl-1-propanesulfonic acid copolymer, its alkali metal salt or amine salt. Depending on the purpose, two or more of these resins may be mixed and used. However, the present invention is not limited to these examples.

  The overcoat layer may contain a photothermal conversion agent in order to improve sensitivity. A preferable photothermal conversion agent includes a water-soluble infrared absorbing dye. For example, (IR-1) to (IR-11) shown in the description of the recording layer are preferably used.

  In addition, a nonionic surfactant can be mainly added to the overcoat layer in the case of aqueous solution coating for the purpose of ensuring the uniformity of coating. Specific examples of such nonionic surfactants include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecyl ether and the like. . The proportion of the nonionic surfactant in the overcoat layer in the total solid is preferably 0.05 to 5 mass%, more preferably 1 to 3 mass%.

  Furthermore, the overcoat layer can contain a compound having any one of fluorine atoms and silicon atoms described in JP-A No. 2001-341448 in order to prevent sticking between plates during stacking and storage.

The thickness of the overcoat layer according to the present invention is preferably 0.1 to 4.0 μm, and more preferably 0.1 to 1.0 μm. Within this range, it is possible to prevent the recording layer from being contaminated by an oleophilic substance without impairing the removability of the overcoat layer on the printing press.
[Support]
The support that can be used for the lithographic printing plate precursor according to the present invention is a dimensionally stable plate-like material, for example, paper, paper laminated with plastic (for example, 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.), paper or plastic film on which the above metal is laminated or vapor-deposited. A preferable support is an aluminum plate.

  The aluminum plate is a pure aluminum plate and an alloy plate containing aluminum as a main component and containing a trace amount of different elements. Further, a plastic is 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 at most 10% by mass. Further, it may be an aluminum plate from an aluminum ingot using a DC casting method or an aluminum plate from an ingot by a continuous casting method. However, as the aluminum plate applied to the present invention, conventionally known and publicly available aluminum plates can be used as appropriate.

  The thickness of the substrate used in the present invention is 0.05 mm to 0.6 mm, preferably 0.1 mm to 0.4 mm, and particularly preferably 0.15 mm to 0.3 mm.

  Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening the surface or anodizing. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion to the recording layer.

  The surface of the aluminum plate is roughened by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening the surface, and a method of selectively dissolving the surface chemically. By the method. As the mechanical method, 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. As a chemical method, a method of immersing in a saturated aqueous solution of an aluminum salt of a mineral acid as described in JP-A No. 54-31187 is suitable. In addition, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Further, as disclosed in JP-A-54-63902, an electrolytic surface roughening method using a mixed acid can also be used. The roughening by the method as described above is preferably performed in such a range that the center line average roughness (Ra) of the surface of the aluminum plate is 0.2 to 1.0 μm.

  The roughened aluminum plate is subjected to alkali etching treatment using an aqueous solution of potassium hydroxide or sodium hydroxide as necessary, and further neutralized, and then anodized to increase wear resistance as desired. Processing is performed.

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 treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. However, in general, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are suitable. The amount of the oxide film to be formed is preferably 1.0 to 5.0 g / m ² , particularly 1.5 to 4.0 g / m ² .

  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, an aqueous solution containing an anodized film micropore enlargement treatment, micropore sealing treatment, and a hydrophilic compound described in JP-A Nos. 2001-253181 and 2001-322365 The surface hydrophilization treatment to be immersed can be appropriately selected and performed.

  Suitable hydrophilic compounds for the hydrophilization treatment include polyvinylphosphonic acid, sulfonic acid group-containing compounds, saccharide compounds, citric acid, alkali metal silicates, potassium zirconium fluoride, phosphate / inorganic fluorine compounds, and the like. Can be mentioned.

  When using a support with insufficient surface hydrophilicity such as a polyester film as the support used in 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 transition metal described in JP-A-2001-199175 is used. A hydrophilic layer formed by applying a coating solution containing an oxide or hydroxide colloid is preferred. Among these, a hydrophilic layer formed by applying a coating solution containing a silicon oxide or hydroxide colloid is preferable.

  In the present invention, before applying the recording layer, an inorganic undercoat layer such as a water-soluble metal salt such as zinc borate described in JP-A-2001-322365, or An organic subbing layer containing carboxymethylcellulose, dextrin, polyacrylic acid or the like can be provided. The undercoat layer can contain the photothermal conversion agent.

  As described above, a lithographic printing plate precursor to which the method of the present invention can be applied can be obtained. This lithographic printing plate precursor is an on-press development type lithographic printing plate precursor that is image-formed by heat and is subjected to a printing process without undergoing development processing.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
[Production of support]
Cleaning treatment was applied to molten metal of JIS A1050 alloy containing 99.5 mass% or more of aluminum and Fe 0.30 mass%, Si 0.10 mass%, Ti 0.02 mass%, and Cu 0.013 mass%. And cast. In the cleaning process, a degassing process was performed to remove unnecessary gases such as hydrogen in the molten metal, and a ceramic tube filter process was performed. The casting method was a DC casting method. The solidified 500 mm thick ingot was chamfered 10 mm from the surface and homogenized at 550 ° C. for 10 hours so as not to coarsen the intermetallic compound.

  Next, after hot rolling at 400 ° C. and intermediate annealing at 500 ° C. for 60 seconds in a continuous annealing furnace, cold rolling was performed to obtain an aluminum rolled plate having a plate pressure of 0.30 mm. By controlling the roughness of the rolling roll, the centerline average surface roughness Ra after cold rolling was controlled to 0.2 μm. Then, it applied to the tension leveler in order to improve planarity.

Next, the surface treatment for making a lithographic printing plate support was performed. First, in order to remove the rolling oil on the surface of the aluminum plate, degreasing treatment was carried out with a 10% by mass sodium aluminate aqueous solution at 50 ° C. for 30 seconds, and neutralization and smut removal treatment were carried out with a 30% by mass sulfuric acid aqueous solution at 50 ° C. for 30 seconds. Next, in order to improve the adhesion between the support and the recording layer and to provide water retention to the non-image area, a so-called graining treatment was performed to roughen the surface of the support. An aqueous solution containing 1% by mass of nitric acid and 0.5% by mass of aluminum nitrate is kept at 45 ° C., and an aluminum web is allowed to flow in the aqueous solution, while an indirect power feeding cell has a current density of 20 A / dm ² and a duty ratio of 1: 1. Electrolytic graining was performed by applying an anode side electric quantity of 240 C / dm ² in an alternating waveform. Thereafter, an etching treatment was performed with a 10% by mass aqueous sodium aluminate solution at 50 ° C. for 30 seconds, and a 30% by mass sulfuric acid aqueous solution was subjected to neutralization and smut removal treatment at 50 ° C. for 30 seconds. Furthermore, in order to improve wear resistance, chemical resistance and water retention, an oxide film was formed on the support by anodic oxidation. An anodization of 2.5 g / m ² by using a 20% by weight sulfuric acid aqueous solution as an electrolyte at 35 ° C. and carrying out an aluminum web through the electrolyte and performing an electrolytic treatment at a direct current of 14 A / dm ² by an indirect power supply cell. A film was created.

Thereafter, a silicate treatment was performed in order to ensure hydrophilicity as a non-image portion of the printing plate. The treatment was carried in such a way that a No. 3 sodium silicate 1.5 mass% aqueous solution was kept at 70 ° C. so that the contact time of the aluminum web was 15 seconds and further washed with water. The adhesion amount of Si was 10 mg / m ² . The center line surface roughness Ra of the support produced as described above was 0.25 μm.
[Synthesis of Microcapsule A Encapsulating Cationic Polymerizable Compound]
As an oil phase component, 4.5 g of bis (vinyloxyethyl) ether of bisphenol A, an adduct of trimethylolpropane and xylylene diisocyanate (Takenate D-110N, manufactured by Mitsui Takeda Chemical Co., Ltd., microcapsule wall material) 5 g Millionate MR-200 (Nippon Polyurethane Co., Ltd. aromatic isocyanate oligomer, microcapsule wall material) 3.75 g, Infrared absorbing dye (IR-27 described herein) 1.5 g, Pionine A41C (Takemoto Yushi Co., Ltd.) ) Surfactant) 0.1 g was dissolved in 18.4 g of ethyl acetate. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA205 (Kuraray polyvinyl alcohol) was prepared. The oil phase component and the aqueous phase component were emulsified at 12000 rpm for 10 minutes using a homogenizer. Thereafter, a solution obtained by dissolving 0.38 g of tetraethylenepentamine (pentafunctional amine, microcapsule wall cross-linking agent) in 26 g of water was added, followed by stirring at 65 ° C. for 3 minutes while cooling with water. The microcapsule A liquid thus obtained had a solid content concentration of 24% by mass and an average particle size of 0.3 μm.
[Synthesis Example of Microcapsule B Encapsulating Radical Polymerizable Compound]
As oil phase components, 4.5 g of dipentaerythritol tetraacrylate (KAYARAD DPHA manufactured by Nippon Kayaku), adduct of trimethylolpropane and xylylene diisocyanate (Takenate D-110N manufactured by Mitsui Takeda Chemical Co., Ltd.), microcapsule wall Material) 5 g, Millionate MR-200 (Nippon Polyurethane Co., Ltd. aromatic isocyanate oligomer, microcapsule wall material) 3.75 g, Infrared absorbing dye (IR-27 described in this specification) 1.5 g, Pionine A41C (Takemoto (Oil (surfactant) surfactant) 0.1 g was dissolved in ethyl acetate 18.4 g. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA205 (Kuraray polyvinyl alcohol) was prepared. The oil phase component and the aqueous phase component were emulsified at 12000 rpm for 10 minutes using a homogenizer. Thereafter, a solution obtained by dissolving 0.38 g of tetraethylenepentamine (pentafunctional amine, microcapsule wall cross-linking agent) in 26 g of water was added, followed by stirring at 65 ° C. for 3 minutes while cooling with water. The microcapsule solution thus obtained had a solid content concentration of 24% by mass and an average particle size of 0.3 μm.
[Example 1]
(Preparation of lithographic printing plate precursor A)
The following recording layer coating solution containing the microcapsules A of the synthesis example was bar-coated on the aluminum substrate obtained in the above production example, and then dried in an oven at 100 ° C. for 60 seconds. A lithographic printing plate precursor A having a thickness of 0.0 g / m ² was prepared.
<Recording layer coating solution>
・ 35.4g of water
-Microcapsule A liquid 9.0 g in the above synthesis example
Acid generator (AI-7 as described herein) 0.24 g
[Example 2]
(Preparation of lithographic printing plate precursor B)
The following recording layer coating solution containing the microcapsule B of the synthesis example was bar coated on the aluminum substrate obtained in the above production example, and then dried in an oven at 100 ° C. for 60 seconds. A lithographic printing plate precursor B having a thickness of 0.0 g / m ² was prepared.
<Recording layer coating solution>
・ 35.4g of water
-Microcapsule B liquid 9.0 g in the above synthesis example
Acid generator (AS-7 as described herein) 0.24 g
(Exposure / printing and evaluation)
The lithographic printing plate precursor obtained above is mounted on the image exposure apparatus 10 according to the present invention, and the lithographic printing plate precursor 12 is scanned and exposed by the IR laser L to form an image on the recording layer. During the scanning exposure, the irradiation area A _UV including the exposure area A _IR was irradiated with ultraviolet UV to activate the polymerization initiator contained in the recording layer. At this time, 365 nm was selected as the wavelength of the ultraviolet UV irradiated by the ultraviolet irradiation device 38. Moreover, the output of the ultraviolet UV emitted from the ultraviolet irradiation device 38 was set within the range of 30W to 100W.

  As a result, not only in the vicinity of the surface of the recording layer but also in the vicinity of the interface between the recording layer and the support, sufficient starting species are supplied by promoting the decomposition reaction of the acid generator. Polymerization and curing reaction of the released cationic polymerizable compound proceeded efficiently, and a strong and excellent printing durability could be formed.

  Each lithographic printing plate precursor of the example was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without developing after the image exposure. 4% by volume IF102 (manufactured by Fuji Photo Film Co., Ltd.) using dampening water and Barius ink ink (manufactured by Dainippon Ink & Chemicals, Inc.), supplying dampening water, supplying ink, and Paper was supplied for printing.

  At this time, the recording layer in the non-image area was removed in the initial stage of the printing process, and a high-quality printed matter without stains in the non-image area was obtained. After that, printing was continued, and the number of sheets was visually measured to determine whether the non-image area was free of smudges and the image area could be printed with a sufficient ink density, and used as an index of printing durability. The larger the number, the better the printing durability.

  As a result, the lithographic printing plate precursor A of Example 1 was 35,000 sheets, and the lithographic printing plate precursor B of Example 2 was 30,000 sheets. Thereby, it was confirmed that both the lithographic printing plate precursors of Examples 1 and 2 have excellent printing durability that can withstand practicality.

It is a side view which shows the structure of the image exposure apparatus of 1st Embodiment which concerns on this invention. It is a perspective view which shows the structure of the exposure head and its feed mechanism in the image exposure apparatus shown by FIG. It is the top view and side view which show the structure of the optical unit shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image exposure apparatus 12 Planographic printing plate precursor 20 Outer drum (holding member)
22 Chuck mechanism (chuck mechanism)
26 Exposure head (exposure means)
28 Feeding mechanism (exposure means)
32 LD light source (exposure means)
38 UV irradiation equipment (UV irradiation means)
40 UV light source (ultraviolet irradiation means)
68 Carrier (carrier member)
92 Beam combiner

Claims (4)

An image forming method for forming an image on a lithographic printing plate precursor comprising an image recording layer comprising a microcapsule encapsulating a polymerizable compound, a polymerization initiator, and a photothermal conversion agent on a support. ,
An image exposure step of scanning and exposing the lithographic printing plate precursor with an infrared beam to form an image on the image recording layer of the lithographic printing plate precursor;
Ultraviolet irradiation is locally applied to an ultraviolet irradiation region including an arbitrary exposure region irradiated with the infrared beam on the image recording layer of the lithographic printing plate precursor during irradiation of the infrared beam with respect to the exposure region included in the ultraviolet irradiation region. UV irradiation process to
An image forming method comprising:   2. The image forming method according to claim 1, wherein in the ultraviolet irradiation step, the ultraviolet irradiation region in the lithographic printing plate precursor is irradiated with ultraviolet rays having a wavelength selected from a wavelength range of 200 nm to 400 nm. An image exposure apparatus used in the image forming method according to claim 1 or 2,
A holding member for holding the lithographic printing plate precursor, the lithographic printing plate precursor being mountable;
Exposure means for scanning and exposing the lithographic printing plate precursor held by the holding member with an infrared beam to form an image on the image recording layer of the lithographic printing plate precursor;
An ultraviolet ray that irradiates ultraviolet rays locally to the ultraviolet irradiation region including an arbitrary exposure region in the lithographic printing plate precursor irradiated with the infrared beam by the exposure means during the irradiation of the infrared beam to the exposure region included in the ultraviolet irradiation region. Irradiation means;
An image exposure apparatus comprising: An exposure head that forms a beam spot of an infrared beam on the exposure area of the lithographic printing plate precursor mounted on the holding member on the exposure means, a carrier member on which the exposure head is mounted, and exposure to the lithographic printing plate precursor Sometimes provided with a feed mechanism for moving the carrier member in the sub-scanning direction,
The ultraviolet irradiating means is provided with an ultraviolet light source that emits ultraviolet rays, and a beam combiner that irradiates the ultraviolet irradiation region by combining the ultraviolet light emitted from the ultraviolet light source with the infrared beam emitted from the exposure head. ,
4. The image exposure apparatus according to claim 3, wherein each of the ultraviolet light source unit and the beam combiner is mounted on the carrier member.

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