JP2007052371A - Method for setting exposure condition for planographic printing original plate, platemaking method and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for setting exposure conditions that facilitate appropriate exposure adjustment on an on-press development type planographic printing original plate. <P>SOLUTION: The method for setting exposure conditions for a planographic printing plate having an image recording layer on a supporting body and facilitating on-press development by supplying a print ink and/or dampening water, is characterized in that the exposure conditions are set by evaluating an image on a planographic printing plate obtained by exposure and on-press development of the planographic printing original plate. It is preferable to evaluate reproducibility of an image of thin lines and/or dots and to carry out on-press development at least 10 minutes after the exposure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exposure condition setting method for a lithographic printing plate precursor that can be developed on-press, and a plate making method and a printing method using the same. In particular, the present invention relates to an exposure condition setting method based on evaluation of a printed image, and a plate making method and a printing method using the exposure condition setting method.

In lithographic printing, dampening water and oil-based ink are alternately applied to a lithographic printing plate surface having a surface composed of an oleophilic image portion and a hydrophilic non-image portion, and the property that water and oil repel each other is utilized. A method in which a hydrophilic non-image portion is used as a dampening water receiving portion (ink non-receiving portion), ink is received only in the oleophilic image portion, and then the ink is transferred to a printing medium such as paper. It is.
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 other unnecessary image recording layers are made of an alkaline aqueous solution, an organic solvent, etc. A lithographic printing plate is obtained by making a plate by a method of forming a non-image portion by exposing the surface of the hydrophilic support by dissolving and removing with a developer.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing an unnecessary image recording layer with a developer or the like is necessary after exposure. However, such additional wet processing is 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.

As one of the simple plate making methods corresponding to this, an image recording layer that can remove the image recording layer of the lithographic printing plate precursor in a normal printing process is used. A method called on-press development has been proposed in which the 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 a step of removing an unnecessary 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 Or a dampening solution) to remove unnecessary image recording layers of the lithographic printing plate precursor and to expose the hydrophilic support surface.

  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. Accordingly, 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 describes a lithographic printing plate precursor in which an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is provided on a hydrophilic support. Yes. In this Patent Document 1, the above lithographic printing plate precursor is exposed by an infrared laser, and the hydrophobic thermoplastic polymer particles are coalesced by heat to form an image, which is then mounted on a cylinder of a printing press and moistened. It is described that it is possible to perform on-press development with water and / or ink.
However, it has been found that the above-described method for forming an image by merging the fine particles by simple thermal fusion exhibits good on-press developability but has low image strength and insufficient printing durability.

  For this reason, it has been proposed to improve printing durability using a polymerization reaction. For example, Patent Document 2 and Patent Document 3 describe a lithographic printing plate precursor having an image recording layer (heat-sensitive layer) containing microcapsules encapsulating a polymerizable compound on a hydrophilic support. Furthermore, Patent Document 4 describes a lithographic printing plate precursor in which an image recording layer (photosensitive layer) containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on a support.

  Also, work procedures from image exposure to printing on a lithographic printing plate precursor in a plate making method including on-press development, for example, when performing image exposure on a lithographic printing plate precursor before mounting on a printing press, When performing later, various proposals, such as the order of supply of dampening water and ink and the use of rollers of a printing press, have been made (see, for example, Patent Documents 2 and 5).

  When performing actual plate making operations, the state of the equipment and materials used (exposure light source, lithographic printing plate precursor, developer, etc.) affects the performance of the resulting lithographic printing plate. I am working on setting exposure conditions. For example, in a conventional PS plate that is UV-exposed using a lith film, a step guide generally called a gray scale is used to adjust an exposure amount (exposure count number) at which an appropriate image forming reaction is performed. That is, the step guide is test-baked and developed under standard conditions to inspect whether or not an image having the target step guide level is obtained. The result is fed back to determine an appropriate exposure amount for the main exposure. Even in the photopolymer type CTP plate for laser exposure in the visible light to UV light region, by setting the step guide on the plate and performing laser exposure, exposure condition setting by trial baking similar to the conventional PS plate ( Adjustment of laser output and scanning speed).

On the other hand, in the thermal type CTP plate using IR laser, exposure adjustment using a step guide is generally not performed, and the following adjustment method is performed. In other words, whether or not the desired image (thin line reproducibility, halftone dot reproducibility) has been obtained on a lithographic printing plate after exposure to fine lines and halftone dots under standard exposure conditions and standard alkali development. Judgment of exposure can be made. Although the exposure parameters to be set differ depending on the plate setter to be used, the exposure conditions are basically set by the method described above. This method may be used for the above-mentioned photopolymer type CTP plate.
Japanese Patent No. 2938397 JP 2001-277740 A JP 2001-277742 A JP 2002-287334 A JP 2000-52634 A

As described above, in the actual plate making operation, an exposure condition is set using any method before the main operation. However, in the on-press development type CTP plate, the above-described method cannot be used because there is no development step before the printing press is attached.
Accordingly, an object of the present invention is to provide an exposure condition setting method that enables appropriate exposure adjustment of an on-press development type lithographic printing plate precursor.

1. An exposure condition setting method for a lithographic printing plate precursor having an image recording layer on a support and capable of being developed on-press by supplying printing ink and / or dampening water, the lithographic printing plate precursor being exposed An exposure condition setting method comprising setting an exposure condition by evaluating an image on a lithographic printing plate obtained by on-machine development.
2. 2. The exposure condition setting method according to 1 above, wherein the exposure amount is set by evaluating reproducibility of fine lines and / or halftone dots on the lithographic printing plate after on-press development.
3. 2. The exposure condition setting method according to 1 above, wherein calibration is set when creating a halftone image of an image original by evaluating tone reproducibility on a lithographic printing plate after on-machine development.
4). 4. The exposure condition setting method according to any one of items 1 to 3, wherein the image recording layer is a layer on which an image is formed by polymerization.
5. Any one of the above 1 to 4, wherein exposure conditions are set by evaluating an image on a lithographic printing plate obtained by on-press development after at least 10 minutes have elapsed after exposure of the lithographic printing plate precursor 2. The exposure condition setting method according to item 1.
6). The exposure conditions are set by evaluating the image on the planographic printing plate obtained by exposing the planographic printing plate precursor to the plate cylinder of the printing press and developing it on the press. The exposure condition setting method according to any one of the above.
7). Any one of said 1-6 characterized by attaching printing ink to the image part of the lithographic printing plate after on-press development so that (DELTA) E with respect to a non-image part may be 20 or more, and evaluating an image. The exposure condition setting method as described in 2.
8). A lithographic printing plate making method comprising exposing a lithographic printing plate precursor under the exposure conditions set by the exposure condition setting method described in any one of 1 to 7 above and developing it on-machine.
9. A printing method for a lithographic printing plate, wherein the lithographic printing plate precursor is exposed under the exposure conditions set by the exposure condition setting method described in any one of 1 to 7 above, developed on the machine, and printed.

  ADVANTAGE OF THE INVENTION According to this invention, the exposure condition setting method which makes it possible to perform appropriate exposure adjustment of an on-press development type lithographic printing plate precursor can be provided.

[Exposure condition setting method]
The exposure condition setting method for the planographic printing plate of the present invention will be described in detail.
In the exposure condition setting method of the present invention, it is essential to perform on-press development for confirming the exposure conditions once before the main printing. The evaluation image used here is an image that can be detected in a sensitive manner when the exposure parameters (exposure amount, scanning speed, focus, etc.) to be adjusted fluctuate. As the image, fine lines and / or halftone dots are preferable, and in general, the detection sensitivity is higher when a high-resolution image is used. Therefore, fine lines of about several μm to 10 μm and / or halftone dots of about 10 μm to several tens of μm per dot. Is preferably used. Furthermore, in general, the FM screen is more preferable than the AM screen because the perimeter of the image becomes longer or the detection sensitivity becomes higher.
Also, with regard to halftone dot density calibration at the time of RIP development, the dot gain amount of a normal printed matter is measured, the halftone density of the original image is adjusted to match this with the target dot gain amount, and the RIP image is again displayed. Do that. Further, in order to separate the dot gain at the time of plate making and the dot gain at the time of printing, the dot gain amount on the printing plate after plate making is managed, and the calibration curve is corrected when this amount deviates from the target. In the exposure condition setting method of the present invention, the dot gain amount on the plate of the on-press development type printing plate can be adjusted. This calibration curve is prepared for each color and for each color.

These images suitable for confirming the exposure conditions are exposed under standard exposure conditions, and evaluation is performed on images on the printing plate obtained by developing the images on a printing press. At this time, the time interval from exposure to on-press development is preferably 10 minutes or more. The reason for this is not clear, but especially in image formation using a polymerization reaction, the radical species at the time of exposure exist for a while after that, and the time change of the image forming area immediately after exposure is large. Estimated. That is, if the image is evaluated by developing it on the machine just after exposure, the variation in fine line reproducibility and halftone dot reproducibility becomes large. A more preferable time interval is 30 minutes or more.
The press settings for on-press development (such as the number of times the ink is applied and the number of ink deposits at the start of on-press development, the amount of water supplied, the amount of ink supplied, the rotation speed of the press, etc.) can be used as long as they can be properly developed on-press. There is no limitation, and it is more preferable if it is within the standard use conditions of the printing press to be used. Regarding the state of the plate after on-press development that is evaluated for setting exposure conditions, the printed material when printed in that state is a normal printed material that is free of ink stains in the non-image area and has no half-body color. Is essential. The larger the amount of ink adhering to the solid part on the plate, the easier it is to evaluate the image. In general, it is sufficient that the ink density of the solid part of the printed material is a standard density when printed, but the ink is preferably adhered so that the color difference ΔE from the non-image part is 20 or more, more preferably ΔE is 30 or more. preferable.

In the present invention, the color difference ΔE includes the color space coordinates (L * ₁ , a * ₁ , b * ₁ ) of the image part to which the ink is applied, and the color space coordinates (L * ₂ , a * ₂ ) of the non-image part. , B * ₂ ) is obtained from the following equation.
_{ΔE = {(L * 1 -L} * 2) 2 + (a * 1 -a * 2) 2 + (b * 1 -b * 2) 2} 1/2
The color space coordinates can be measured using a general color difference meter such as a color difference meter CR-221 (manufactured by Minolta Co., Ltd.).

Therefore, in the method of the present invention, printing may or may not be performed following on-press development. However, in order to determine whether the on-plate state after on-press development is the proper state described above, printing is performed. It is better to go. The ink type used for the image evaluation on the plate needs to be a color having sufficient contrast with the non-image portion so that an appropriate image evaluation can be performed. That is, generally, black, cyan, or magenta is selected, and black is preferable.
The fine line reproducibility and halftone dot reproducibility on the lithographic printing plate after on-press development thus obtained are evaluated, and the exposure conditions are set so as to correct the deviation from the desired image reproducibility. If necessary, repeat this operation twice or more to set appropriate exposure conditions.

The exposure light source used in the present invention is preferably a laser. Although the laser used for this invention is not specifically limited, The solid laser and semiconductor laser which irradiate infrared rays with a wavelength of 760-1200 nm, the semiconductor laser which irradiates light with 250-420 nm, etc. are mentioned suitably.
Regarding the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is preferably 10 to 300 mJ / cm ² . In a semiconductor laser that emits light of 250 to 420 nm, the output is preferably 0.1 mW or more. In any laser, it is preferable to use a multi-beam laser device in order to shorten the exposure time.

  The exposed lithographic printing plate precursor is mounted on a plate cylinder of a printing press. In the case of a printing press equipped with a laser exposure device, imagewise exposure is performed after a lithographic printing plate precursor is mounted on the plate cylinder of the printing press.

After exposing the lithographic printing plate precursor imagewise with a laser and supplying printing with dampening water and printing ink without going through a development process such as a wet development process, in the exposed part of the image recording layer, The image recording layer cured by exposure forms a printing ink receiving portion having an oleophilic surface. On the other hand, in the unexposed portion, the uncured image recording layer is dissolved or dispersed and removed by the supplied fountain solution and / or printing ink, and the hydrophilic surface is exposed in the portion, and the machine is on-machine. Development is complete. As a result, the fountain solution adheres to the exposed hydrophilic surface, and the printing ink is deposited on the image recording layer in the exposed area. The fountain solution and printing ink used in the present invention may be ordinary ones that are commercially available for lithographic printing.
In actual printing work, exposure conditions are determined by the exposure condition setting method of the present invention, and a lithographic printing plate precursor for main printing is exposed under those conditions, developed on the machine, and a large number of sheets are printed as they are.

[Lithographic printing plate precursor]
Hereinafter, components and components of the lithographic printing plate precursor used in the present invention will be described.

(Image recording layer)
The image recording layer of the present invention can be removed with fountain solution and / or printing ink. A preferably usable element is an imaging element utilizing polymerization. As an image forming element utilizing this polymerization, (A) an infrared absorber, (B) a polymerization initiator, and (C) a polymerizable compound, which can be recorded with an infrared laser, or (B) It contains a polymerization initiator and (C) a polymerizable compound, and is preferably photosensitive in the range of 250 nm to 420 nm.
Hereinafter, these components will be described.

<(A) Infrared absorber>
When forming an image of the lithographic printing plate precursor according to the present invention with a laser that emits infrared rays of 760 to 1200 nm using a light source, it is usually essential to use an infrared absorber. The infrared absorber has a function of converting the absorbed infrared ray into heat and a function of being excited by the infrared ray and transferring electrons / energy to a polymerization initiator (radical generator) described later. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

  As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

  Examples of preferable dyes include cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, Methine dyes described in JP-A Nos. 58-181690 and 58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc., squarylium dyes described in JP-A-58-112792, etc., British Patent No. And cyanine dyes described in the specification of 434,875.

In addition, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also suitable. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, and 58-2
Pyryllium compounds described in 2014, No. 59-41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, JP-A-59-216146 The cyanine dyes described herein, the pentamethine thiopyrylium salts described in US Pat. No. 4,283,475, and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are also preferably used. It is done. Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).
Other preferable examples of the infrared absorbing dye of the present invention include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferred, and one particularly preferred example is a cyanine dye represented by the following general formula (I).

In general formula (I), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group shown below.

Here, Ph is a phenyl group, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, a hetero atom And a hydrocarbon group having 1 to 12 carbon atoms. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. Xa ^- the Za described later ^- is defined as for, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom.

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring or It is particularly preferable that a 6-membered ring is formed.
Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (I) has an anionic substituent in its structure and neutralization of charge is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a hexagonal salt, in view of the storage stability of the recording layer coating solution. Fluorophosphate ions and aryl sulfonate ions.

Specific examples of the cyanine dye represented by formula (I) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. be able to.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, 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 In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Application of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle diameter of the pigment is preferably in the range of 0.01 to 10 μm, more preferably in the range of 0.05 to 1 μm, and particularly preferably in the range of 0.1 to 1 μm. Within this range, good stability of the pigment dispersion in the image recording layer coating solution and good uniformity of the image recording layer can be obtained.

  As a method for dispersing the pigment, a known dispersion technique used for ink production, toner production or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

These infrared absorbers may be added to the same layer as other components, may be added to the discoloration layer, or may be added to another layer. Moreover, it can also be included in a microcapsule and added.
As the addition amount, when a negative lithographic printing plate precursor is prepared, the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm of the image recording layer is in the range of 0.3 to 1.2 by the reflection measurement method. It is preferable to add such that it is in a range of 0.4 to 1.1. Within this range, a uniform polymerization reaction proceeds in the depth direction of the image recording layer, and good film strength of the image area and adhesion to the support can be obtained.
The absorbance of the image recording layer can be adjusted by the amount of infrared absorber added to the image recording layer and the thickness of the image recording layer. Absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, an image recording layer having a thickness appropriately determined in a range in which the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is set to the optical density. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.

<(B) Polymerization initiator>
The polymerization initiator used in the present invention is a compound that generates radicals by light, heat, or both, and initiates and accelerates polymerization of a compound having a polymerizable unsaturated group. As the polymerization generator that can be used in the present invention, a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, or the like can be used, and a radical that is suitably used in the present invention is generated. The compound to be used refers to a compound that initiates and accelerates the polymerization of a compound having a polymerizable unsaturated group by generating a radical by thermal energy. As the thermal radical generator according to the present invention, a known polymerization initiator, a compound having a bond with a small bond dissociation energy, or the like can be appropriately selected and used. Moreover, the compound which generate | occur | produces a radical can be used individually or in combination of 2 or more types.
Examples of the compound that generates radicals include organic halogenated compounds, carbonyl compounds, organic peroxide compounds, azo polymerization initiators, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boric acid compounds, disulfonic acid compounds, Examples include oxime 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. The compound as described in Hutt, "Journal of Heterocyclic Chemistry" 1 (No. 3) (1970) is mentioned. Among these, an oxazole compound S-triazine compound substituted with a trihalomethyl group is preferable.

More preferably, an oxadiazole derivative in which at least one mono-, di-, or trihalogen-substituted methyl group is bonded to the s-triazine derivative oxadiazole ring bonded to the s-triazine ring. 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) Examples include -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, Kunz, Martin “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”. Organoboron salts, organoboron sulfonium complexes or organoboron oxosulfonium complexes described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, JP-A-6-175554 JP-A-6-175553 Organoboron iodonium complexes described in JP-A-9-188710, organoboron phosphonium complexes described in JP-A-9-348710, JP-A-7-128785, JP-A-7-140589, JP-A-7- Examples thereof include organoboron transition metal coordination complexes such as 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 compound include JCS Perkin II (1979) 1653-1660), JCSPerkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, and JP-A 2000-66385. Compounds, compounds described in JP-A No. 2000-80068, specifically, compounds represented by the following structural formulas may be mentioned.

  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 particular, from the viewpoint of reactivity and stability, the above oxime ester compounds, diazonium salts, iodonium salts, and sulfonium salts are exemplified. In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
The onium salt suitably used in the present invention is an onium salt 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. Of these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, and sulfonate ion sulfinate ion are preferable from the viewpoint of stability.

In the formula (RI-II), Ar ₂₁ Ar ₂₂ each independently represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents are 1 to 12 carbon atoms. Alkyl group, alkenyl group having 1 to 12 carbon atoms, alkynyl group having 1 to 12 carbon atoms, aryl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, 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 number A 1-12 thioalkyl group and a C1-C12 thioaryl group are mentioned. 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 and R ₃₂ R ₃₃ are each independently an aryl group, alkyl group, alkenyl group, or alkynyl group having 20 or less carbon atoms, which may have 1 to 6 substituents. Represents. 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, Aryloxy group having 1 to 12 carbon atoms, 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, a 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. Of 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.

  Specific examples of the polymerization initiator that can be applied to the present invention are listed below, but are not limited thereto.

  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.

  Radical generation by using a sensitizer in combination with a polymerization initiator selected from the above in the image recording layer of a lithographic printing plate precursor that performs imagewise exposure using a light source that emits light of 250 to 420 nm Efficiency can also be increased.

  Specific examples of the sensitizer 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) phenyl styryl ketone, p- (dimethylamino) phenyl p-methylstyryl ketone, benzophenone, p- (dimethylamino) ) Benzophenone (or Michlerketo) ), P- (diethylamino) benzophenone, and the like benzanthrone.

  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 (α-naphthothiazole, β-naphthothiazole, etc.), benzoselenazoles (benzoselenazole, 5-chlorobenzoselenazole, 6-methoxybenzoselenazole, etc.), naphthoselenazoles (α-naphthoselenazole) , 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 and R ¹⁴ 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.

  Moreover, as the sensitizer used in the present invention, compounds described as sensitizing dyes in JP-A Nos. 2001-100412 and 2003-221517 are also suitable.

  These polymerization initiators and sensitizers are each preferably from 0.1 to 50% by weight, more preferably from 0.5 to 30% by weight, particularly preferably 0.8%, based on the total solid content constituting the image recording layer. It can be added at a ratio of ˜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.

<(C) 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, that is, dimers, trimer oligomers, or mixtures thereof, and copolymers thereof. Examples of such monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof. Preferably, 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. Also, addition reaction product, monofunctional or polyfunctional of unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as hydroxyl group, amino group, mercapto group and monofunctional or polyfunctional isocyanates or epoxy A dehydration condensation reaction product with 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 -, and the like [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. And those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613. 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 (A) to a polyisocyanate compound having two or more isocyanate groups. Compound etc. are mentioned.

_{CH 2 = C (R 4)} COOCH 2 CH (R 5) OH (A)
(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. Furthermore, 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, JP-A-1-105238, It is possible to obtain a photopolymerizable composition excellent in the 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. In addition, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid-based compounds described in JP-A-2-25493 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 monomer oligomers, can also be used.

About these addition polymerizable compounds, the details of the method of use such as the structure, single use or combination, addition amount, etc. 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 area, that is, the cured film, those having three or more functionalities are preferable. Further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
Further, the selection and use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components (for example, binder polymer, initiator, colorant, etc.) in the image recording layer. In some cases, the compatibility can be improved by using a low-purity compound or by 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 used in an amount of preferably 5 to 80% by mass, more preferably 25 to 75% by mass, based on 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 polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.

In the present invention, several modes can be used as a method of incorporating the above-mentioned image recording layer constituent components (A) to (C) and other constituent components described later 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, for example, JP-A-2002-287334. In another embodiment, for example, as described in 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 microcapsule type image recording layer. Further, in the microcapsule type image recording layer, the constituent component can 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. As another embodiment, an embodiment in which the image recording layer contains crosslinked resin particles, that is, microgel, can be mentioned. The microgel can contain a part of the components (A) to (C) in and / or on the surface thereof. In particular, an embodiment in which (C) a reactive microgel is formed by having a polymerizable compound on the surface thereof is particularly preferable from the viewpoint of image forming sensitivity and printing durability.
In order to obtain better on-press developability, the image recording layer is preferably a microcapsule type or microgel type image recording layer.

  As a method for microencapsulating or microgelling the components of the image recording layer, known methods can be applied.

  For example, as a method for producing microcapsules, a method using coacervation found in US Pat. Nos. 2,800,547 and 2,800,498, each specification of US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, 42-446 by the interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304 by precipitation of polymer, US Pat. No. 3,796,669, isocyanate polyol A method using a wall material, a method using an isocyanate wall material found in US Pat. No. 3,914,511, and a urea-formaldehyde system found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802. Or urea formaldehyde-resorcino A method using a wall 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 Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method using monomer polymerization, spray drying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling method seen in British Patent Nos. 952807 and 967074, etc. However, 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 the below-mentioned binder polymer.

On the other hand, as a method for preparing the microgel, granulation by interfacial polymerization described in JP-B-38-19574 and JP-A-42-446, as described in JP-A-5-61214, etc. It is possible to utilize granulation by non-aqueous dispersion polymerization. However, it is not limited to these methods.
As the method using the interfacial polymerization, the known microcapsule production method described above can be applied.

  Preferred microgels used in the present invention are those granulated by interfacial polymerization and having three-dimensional crosslinking. From such a viewpoint, the material to be used is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and polyurea and polyurethane are particularly preferable.

  The average particle size of the microcapsules or microgel 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.

<Other image recording layer components>
The image recording layer of the present invention can further contain various additives as required. These will be described below.

<Binder polymer>
In the image recording layer of the present invention, a binder polymer can be used in order to improve the film strength of the image recording layer. As the binder polymer, any conventionally known polymer can be used without limitation, and a polymer having a 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 may have crosslinkability in order to improve the film strength of the image area. In order to give the binder polymer crosslinkability, 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 (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group, or an alkoxy group) Alternatively, it represents an aryloxy group, and R ¹ and R ² or R ³ may be bonded to each other to form a ring, n represents an integer of 1 to 10. X represents a dicyclopentadienyl residue. Can be included).
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 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.

  In the present invention, in addition to the above binder polymer, the following hydrophilic binder polymers can also be used. The hydrophilic binder polymer is effective for improving the on-press developability by increasing the permeability of the fountain solution into the image recording layer and for stabilizing the dispersion of the microcapsules and microgels.

  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, ammonium groups. And those having a hydrophilic group such as an amide group, a carboxymethyl group, a sulfonic acid group, and a phosphoric acid group.

  Specific examples include gum arabic, casein, gelatin, starch derivatives, sodium salt of carboxymethyl cellulose, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acid salts thereof, polymethacrylic acid Acids salts thereof, homopolymer copolymer of hydroxyethyl methacrylate, homopolymer copolymer of hydroxyethyl acrylate, homopolymer copolymer of hydroxypropyl methacrylate, homopolymer copolymer of hydroxypropyl acrylate, homopolymer copolymer of hydroxybutyl methacrylate, hydroxybutyl acrylate Homopolymer copolymers, polyethylene glycols, hydroxypropylene polymers Polyvinyl alcohols, hydrolyzed polyvinyl acetate having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more, polyvinyl formal, polyvinyl butyral, polyvinylpyrrolidone, acrylamide homopolymer copolymer, methacrylamide homopolymer polymer, N-methylolacrylamide homopolymer copolymer, polyvinylpyrrolidone, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, and the like.

The binder polymer preferably has a mass average molecular weight of 5,000 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 (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The binder polymer may be a random polymer, a block polymer, a graft polymer, or the like, but is preferably a random polymer or a graft 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 5 to 90% by mass, more preferably 5 to 80% by mass, and further preferably 10 to 70% by mass with respect to the total solid content of the image recording layer. preferable. 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.

<Surfactant>
In the present invention, it is preferable to use a surfactant in the image recording layer in order to improve the on-surface development property in order to promote on-press developability at the start of printing. 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; Cationic type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group hydrophilic group, oligomer containing perfluoroalkyl group lipophilic group, perfluoroalkyl group, Nonionic types such as an oligomer containing a hydrophilic group / lipophilic group and a urethane containing a perfluoroalkyl group / lipophilic group can be mentioned. Moreover, the fluorine-type surfactant described in Unexamined-Japanese-Patent No. 62-170950, 62-226143, 60-168144 is also mentioned suitably.

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) 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 JP-A-62-2 And dyes described in No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can 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 relative 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, 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.

  The preferred amount of the dye that changes color by acid or radical is preferably 0.01 to 10% by mass relative to the solid content of the image recording layer.

<Polymerization inhibitor>
In order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during the production or storage of the image recording layer, a small amount of a thermal polymerization inhibitor is preferably added 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.

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

<Formation of image recording layer>
The image recording layer of the present invention is coated 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 be formed by preparing a plurality of coating liquids 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-like material. 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 these, 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 (surface roughening treatment for dissolving the surface electrochemically), 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 of anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, 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. If necessary, it contains micropore enlargement treatment, micropore sealing treatment, and hydrophilic compound described in JP-A Nos. 2001-253181 and 2001-322365. A surface hydrophilization treatment immersed in an aqueous solution can be appropriately selected and performed. Of course, the enlargement process and the sealing process are not limited to those described above, and any conventionally known method can be performed.
For example, as the sealing treatment, in addition to the vapor sealing, a single treatment with fluorinated zirconic acid, a treatment with sodium fluoride, or a vapor sealing with addition of lithium chloride is possible.

  The sealing treatment used in the present invention is not particularly limited, and a conventionally known method can be used. Among them, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and sealing with hot water are particularly preferable. Hole treatment is preferred. Each will be described below.

As the inorganic fluorine compound used for the sealing treatment with an aqueous solution containing an inorganic fluorine compound, a metal fluoride is preferably exemplified.
Specifically, for example, sodium fluoride, potassium fluoride, calcium fluoride, magnesium fluoride, sodium fluoride zirconate, potassium fluoride zirconate, sodium fluoride titanate, potassium fluoride titanate, zircon fluoride Ammonium acid, ammonium fluoride titanate, potassium fluoride titanate, fluorinated zirconate, fluorinated titanate, hexafluorosilicic acid, nickel fluoride, iron fluoride, phosphor fluoride, ammonium fluoride phosphate It is done. Among these, sodium fluorinated zirconate, sodium fluorinated titanate, fluorinated zirconic acid, and fluorinated titanic acid are preferable.

  The concentration of the inorganic fluorine compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, from the viewpoint of sufficiently sealing the micropores of the anodized film. Further, in terms of stain resistance, it is preferably 1% by mass or less, and more preferably 0.5% by mass or less.

  It is preferable that the aqueous solution containing an inorganic fluorine compound further contains a phosphate compound. When the phosphate compound is contained, the hydrophilicity of the surface of the anodized film is improved, so that on-machine developability and stain resistance can be improved.

Suitable examples of the phosphate compound include phosphates of metals such as alkali metals and alkaline earth metals.
Specifically, for example, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, dihydrogen phosphate Potassium, dipotassium hydrogen phosphate, calcium phosphate, sodium ammonium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, hydrogen phosphate Disodium, lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid, ammonium phosphotungstate, sodium phosphotungstate, ammonium phosphomolybdate, sodium phosphomolybdate, sodium phosphite , Tripolyphosphate Potassium, and sodium pyrophosphate. Among these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.
The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. Is preferred.

  The concentration of the phosphate compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, from the viewpoint of improving on-press developability and stain resistance. Further, in terms of solubility, it is preferably 20% by mass or less, and more preferably 5% by mass or less.

The ratio of each compound in the aqueous solution is not particularly limited, but the mass ratio of the inorganic fluorine compound and the phosphate compound is preferably 1/200 to 10/1, and preferably 1/30 to 2/1. Is more preferable.
The temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower.
The aqueous solution preferably has a pH of 1 or more, more preferably has a pH of 2 or more, preferably has a pH of 11 or less, and more preferably has a pH of 5 or less.
The method for sealing with an aqueous solution containing an inorganic fluorine compound is not particularly limited, and examples thereof include an immersion method and a spray method. These may be used alone or in combination, or may be used in combination of two or more.
Of these, the dipping method is preferred. When the treatment is performed using the dipping method, the treatment time is preferably 1 second or longer, more preferably 3 seconds or longer, and preferably 100 seconds or shorter, and 20 seconds or shorter. More preferred.

Examples of the sealing treatment with water vapor include a method in which pressurized or normal pressure water vapor is brought into contact with the anodized film continuously or discontinuously.
The temperature of the water vapor is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 105 ° C. or lower.
The water vapor pressure is preferably in the range (1.008 × 10 ^{5 to} 1.043 × 10 ⁵ Pa) from (atmospheric pressure−50 mmAq) to (atmospheric pressure + 300 mmAq).
Further, the time for which the water vapor is contacted is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, more preferably 20 seconds or shorter.

Examples of the sealing treatment with hot water include a method of immersing an aluminum plate on which an anodized film is formed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and even more preferably 20 seconds or shorter.

  The hydrophilization treatment is described in 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 each 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. In this range,
Good adhesion to the image recording layer, good printing durability and good stain resistance are 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 lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the image recording layer and the support, if necessary. Since the undercoat layer tends to cause the image recording layer to peel off from the support in the unexposed area, the on-press developability is improved. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, so that heat generated by exposure does not diffuse to the support and can be used efficiently, so that high sensitivity can be achieved. There are advantages.
As the undercoat layer, specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, JP-A-2-304441. Preferred examples include phosphorus compounds having an ethylenic double bond reactive group described in the publication.
The most preferable undercoat layer includes a polymer resin obtained by copolymerization of a monomer having an adsorbing group / a monomer having a hydrophilic group / a monomer having a crosslinkable group.

An essential component of the polymer undercoat is an adsorptive group on the surface of the hydrophilic support. The presence or absence of adsorptivity to the hydrophilic support surface can be determined by the following method, for example.
A coating night is prepared by dissolving the test compound in a readily soluble solvent, and the coating night is coated and dried on the support so that the coating amount after drying is 30 mg / m ² . Next, the support coated with the test compound is sufficiently washed with a readily soluble solvent, and then the residual amount of the test compound that has not been removed by washing is measured to calculate the adsorbed amount of the support. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, liquid chromatography measurement and the like. A compound having a support adsorptivity is a compound that remains in an amount of 0.5 mg / m ² or more even after the washing treatment as described above.

The adsorptive group on the hydrophilic support surface is a substance (eg, metal, metal oxide) or functional group (eg, hydroxyl group) present on the hydrophilic support surface and a chemical bond (eg, ionic bond, hydrogen bond). , Coordination bond, bond by intermolecular force). The adsorptive group is preferably an acid group or a cationic group.
The acid group preferably has an acid dissociation constant (pKa) of 7 or less. Examples of acid groups include phenolic hydroxyl groups, carboxyl groups, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ —, and —COCH ₂ COCH ₃ . A phosphoric acid group (—OPO ₃ H ₂ , —PO ₃ H ₂ ) is particularly preferred. These acid groups may be metal salts.
The cationic group is preferably an onium group. Examples of the onium group include an ammonium group, a phosphonium group, an arsonium group, a stibonium group, an oxonium group, a sulfonium group, a selenonium group, a stannonium group, and an iodonium group. An ammonium group, a phosphonium group and a sulfonium group are preferred, an ammonium group and a phosphonium group are more preferred, and an ammonium group is most preferred.

  Particularly preferred examples of the monomer having an adsorptive group include compounds represented by the following formula (IV) or (V).

In the formula (IV), R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms. R ¹ , R ² and R ³ are preferably each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferred is a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom.
In the formula (IV), X is an oxygen atom (—O—) or imino (—NH—). X is more preferably an oxygen atom. In the formula (IV), L is a divalent linking group. L is a divalent aliphatic group (alkylene group, substituted alkylene group, alkenylene group, substituted alkenylene group, alkynylene group, substituted alkynylene group), divalent aromatic group (arylene group, substituted arylene group) or divalent Or an oxygen atom (—O—), a sulfur atom (—S—), an imino (—NH—), a substituted imino (—NR—, where R is an aliphatic group, an aromatic group. Or a combination with a heterocyclic group) or carbonyl (—CO—).

  The aliphatic group may have a cyclic structure or a branched structure. The number of carbon atoms in the aliphatic group is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10. The aliphatic group is preferably a saturated aliphatic group rather than an unsaturated aliphatic group. The aliphatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aromatic group, and a heterocyclic group.

The number of carbon atoms in the aromatic group is preferably 6 to 20, more preferably 6 to 15, and most preferably 6 to 10. The aromatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aliphatic group, an aromatic group, and a heterocyclic group.
The heterocyclic group preferably has a 5-membered or 6-membered ring as the heterocycle. The heterocycle may be condensed with another heterocycle, aliphatic ring or aromatic ring. The heterocyclic group may have a substituent. Examples of substituents are halogen atoms, hydroxyl groups, oxo groups (═O), thioxo groups (═S), imino groups (═NH), substituted imino groups (═N—R, R is an aliphatic group, aromatic Group or heterocyclic group), aliphatic group, aromatic group and heterocyclic group.
L is preferably a divalent linking group containing a plurality of polyoxyalkylene structures. The polyoxyalkylene structure is more preferably a polyoxyethylene structure. In other words, L preferably contains — (OCH ₂ CH ₂ ) _n — (n is an integer of 2 or more).

In the formula (IV), Z is a functional group adsorbed on the surface of the hydrophilic support. Y is a carbon atom or a nitrogen atom. When Y is a nitrogen atom and L is connected to Y to form a quaternary pyridinium group, Z is not essential because it exhibits adsorptivity itself.
In the formula (V), R ¹ , L and Z have the same meanings as in the formula (IV).
The adsorptive functional group is as described above.
Examples of typical compounds represented by formula (IV) or (V) are shown below.

Examples of the hydrophilic group of the undercoat polymer resin that can be used in the present invention include a hydroxy group, a carboxyl group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, a hydroxypropyl group, a polyoxypropyl group, and an amino group. Preferred examples include a group, an aminoethyl group, an aminopropyl group, an ammonium group, an amide group, a carboxymethyl group, a sulfonic acid group, and a phosphoric acid group. Among them, a monomer having a sulfonic acid group exhibiting high hydrophilicity is preferable. Specific examples of the monomer having a sulfonic acid group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, allylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, acrylamide- Examples thereof include t-butylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, (3-acryloyloxypropyl) butylsulfonic acid sodium salt and amine salt. Among them, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferable from the viewpoint of hydrophilic performance and synthetic handling.

  The water-soluble polymer resin for the undercoat layer of the present invention preferably has a crosslinkable group. The crosslinkable group can improve the adhesion with the image area. In order to impart crosslinkability to the polymer resin for the undercoat layer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the side chain of the polymer, or paired with the polar substituent of the polymer resin It can be introduced by forming a salt structure with a compound having a charged substituent and an ethylenically unsaturated bond.

  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, or 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 dicyclopentadi An enyl 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 O—Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ OCO—CH═CH _2. Is mentioned.
As the monomer having a crosslinkable group of the polymer resin for undercoat layer, an ester or amide of acrylic acid or methacrylic acid having the crosslinkable group is suitable.

  The content of the crosslinkable group in the polymer resin for the undercoat layer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol per 1 g of the polymer resin. More preferably, it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol. Within this range, both good sensitivity and dirtiness and good storage stability can be obtained.

The polymer resin for the undercoat layer preferably has a mass average molecular weight of 5000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1000 or more is preferable. More preferably, it is 250,000. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The polymer resin for the undercoat layer may be any of a random polymer, a block polymer, a graft polymer, and the like, but is preferably a random polymer.

  As the undercoat polymer resin of the present invention, a known resin having a hydrophilic group can also be used. Specific examples of such resins include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and Salts thereof, 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, hydroxybutyl Homopolymers and copolymers of methacrylates, homopolymers of hydroxybutyl acrylate Copolymers, polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide homopolymers having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more. Polymers and copolymers, homopolymers and polymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide, polyvinylpyrrolidone, alcohol-soluble nylon, 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin A polyether etc. are mentioned.

The undercoat polymer resin may be used alone or in combination of two or more.
The coating amount (solid content) of the undercoat layer is preferably from 0.1-100 mg / m ^2, and more preferably 1 to 30 mg / m ^2.

(Protective layer)
The lithographic printing plate precursor of the present invention is protected on the image recording layer as necessary to impart oxygen barrier properties, prevent scratches in the image recording layer, prevent ablation that occurs during high-illuminance laser exposure, etc. A layer can be provided.
Usually, the exposure processing of a lithographic printing plate is carried out in the atmosphere. The image forming reaction in the image recording layer caused by the exposure process can be inhibited by low molecular compounds such as oxygen and basic substances present in the atmosphere. The protective layer prevents low molecular compounds such as oxygen and basic substances from entering the image recording layer, and as a result, suppresses image formation inhibition reaction in the air. Therefore, the properties desired for the protective layer are to reduce the permeability of low-molecular compounds such as oxygen, and furthermore, the transparency of light used for exposure is good, and the adhesiveness with the image recording layer is excellent. And it can be easily removed in an on-press development process after exposure. The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and JP-B-55-49729.

  As a material used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used. Specifically, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, partially saponified product of polyvinyl acetate, ethylene-vinyl alcohol copolymer, water-soluble cellulose derivative, gelatin, starch Examples thereof include water-soluble polymers such as derivatives and gum arabic, and polymers such as polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, and cellophane. These may be used in combination of two or more as required.

Examples of relatively useful materials among the above materials include water-soluble polymer compounds having excellent crystallinity. Specifically, water-soluble acrylic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid, gelatin, gum arabic, and the like are suitable. Among these, water can be applied as a solvent, and at the time of printing Polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl imidazole are preferable from the viewpoint that they are easily removed by the fountain solution. Among them, polyvinyl alcohol (PVA) gives the best results for basic properties such as oxygen barrier properties and development removability. The polyvinyl alcohol that can be used in the protective layer may be partially substituted with esters, ethers, and acetals as long as they contain a substantial amount of unsubstituted vinyl alcohol units having the required water solubility. Similarly, a part may contain other copolymerization components. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxyl groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester modification of vinyl alcohol and various organic acids. Polyvinyl alcohol having various degrees of polymerization having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, etc. at the polymer chain end is also preferably used.

  Suitable examples of the modified polyvinyl alcohol include compounds having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, 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, L-8 and the like. Examples of the modified polyvinyl alcohol include KL-318, KL-118, KM-618, KM-118, SK-5102 having an anion-modified site, C-318, C-118 and CM-318 having a cation-modified site. M-205 and M-115 having terminal thiol modification sites, MP-103, MP-203, MP-102 and MP-202 having terminal sulfide modification sites, and ester modification sites with higher fatty acids HL-12E, HL-1203, and other reactive silane-modified R-1130, R-2105, R-2130, and the like.

The protective layer preferably contains a layered compound. The layered compound is a particle having a thin flat plate shape. For example, the following general formula A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂
[However, A is any of Li, K, Na, Ca, Mg, organic cation, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, V, and D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.
Examples of the natural mica include muscovite, soda mica, phlogopite, biotite and sericite. Further, as the synthetic mica, non-swelling mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 ( Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite-based Na or Li hectorite (Na, Li) _1/8 Mg _2/5 Li Examples thereof include swelling mica such as _1/8 (Si ₄ O ₁₀ ) F ₂ . Synthetic smectite is also useful.

Of the above layered compounds, fluorine-based swellable mica, which is a synthetic layered compound, is particularly useful. That is, swellable clay minerals such as mica, montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, and metal atom substitution in the lattice is other than Significantly greater than viscous minerals. As a result, the lattice layer is deficient in positive charge, and in order to compensate for this, the layers such as Li ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts and sulfonium salts are used. Adsorbs organic cation cations. These layered compounds swell with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have this tendency.

  As the shape of the layered compound, from the viewpoint of diffusion control, the thinner the better, the better the planar size as long as the smoothness of the coated surface and the transmittance of actinic rays are not impaired. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

The average particle diameter of the layered compound is 1 to 20 μm, preferably 1 to 10 μm, particularly preferably 2 to 5 μm. When the particle diameter is smaller than 1 μm, the suppression of permeation of oxygen and moisture is insufficient and the effect cannot be exhibited sufficiently. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.
When the inorganic layered compound particles having such a large aspect ratio are contained in the protective layer, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor does not deteriorate due to changes in humidity, and the storage stability is excellent.

  It is preferable that content of the inorganic stratiform compound in a protective layer is 5/1-1/100 by mass ratio with respect to the quantity of the binder used for a protective layer. Even when a plurality of types of inorganic layered compounds are used in combination, the total amount of these inorganic layered compounds is preferably the above-described mass ratio.

  Next, an example of a general dispersion method of the layered compound used for the protective layer will be described. First, 5 to 10 parts by mass of the swellable laminar compound mentioned above as a preferred laminar compound is added to 100 parts by mass of water, and the mixture is thoroughly swelled and swollen. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion of 5 to 10% by mass of the inorganic stratiform compound dispersed by the above method is highly viscous or gelled and has very good storage stability. When preparing a protective layer coating solution using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a binder solution.

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 can be added. These activators can be added in an amount of 0.1 to 100% by mass relative to the (co) polymer.
In order to improve the adhesion with the image area, for example, JP-A-49-70702 discloses an acrylic emulsion 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 of a water-insoluble vinylpyrrolidone-vinyl acetate copolymer and laminating on an image recording layer. British Patent Application No. 1303578 describes that the dispersion of polyfluoroethylene resin particles in a protective layer can prevent adhesion between a film and a lithographic printing plate precursor during exposure using a vacuum baking frame. ing. 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 infrared rays used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved.

  This protective layer coating solution includes known anionic surfactants, nonionic surfactants, cationic surfactants, fluorosurfactants and water-soluble plasticizers for improving the physical properties of the coating. Additives can be added. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, a known additive for improving the adhesion with the image recording layer and the temporal stability of the coating solution may be added to the coating solution.

  The protective layer coating solution thus prepared is applied onto the image recording layer provided on the support and dried to form the protective layer. The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water. The method for applying the protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. . Specific examples of the protective layer include blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and bar coating.

The coating amount of the protective layer, the coating amount after drying is preferably in the range of 0.01 to 10 g / ^{m 2,} more preferably in the range of 0.02 to 3 g / ^{m 2,} and most preferably 0. in the range of 02~1g / ^{m 2.}

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

1. Preparation of planographic printing plate precursor (1) (1) Preparation of support In order to remove rolling oil on the surface of a 0.3 mm thick aluminum plate (material 1050), a 10 mass% sodium aluminate aqueous solution is used at 50 ° C. After degreasing for 30 seconds, the aluminum surface was grained using ^three bundled nylon brushes with a bristle diameter of 0.3 mm and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) with a median diameter of 25 μm. And washed well with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% 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, nitric acid electrolysis was performed with an aqueous solution of 0.5% by mass hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was the anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying. After a direct current anodized film of 2.5 g / m ² of the plate 15 wt% sulfuric acid (containing 0.5 mass% of aluminum ion) at a current density of 15A / dm ² as the electrolytic solution, washed with water and dried.
Then, in order to ensure the hydrophilic property of a non-image part, the silicate process was performed for 15 second at 70 degreeC using the 1.5 mass% No. 3 sodium silicate aqueous solution. The adhesion amount of Si was 10 mg / m ² . Then, it washed with water and the support body was obtained. 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.

Furthermore, the following undercoat liquid (1) was applied so that the dry coating amount was 10 mg / m ² to prepare a support used in the following experiments.

Undercoat liquid (1)
・ Undercoat compound (1) below 0.017g
・ Methanol 9.00 g
・ Distilled water 1.00g

(2) Formation of image recording layer After the image recording layer coating liquid (1) having the following composition was bar-coated on the above support, it was oven-dried at 100 ° C for 60 seconds to obtain a dry coating amount of 1.0 g / m ² . An image recording layer was formed.
The image recording layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and microgel solution (1) immediately before coating.

Photosensitive solution (1)
・ The following binder polymer (1) 0.162 g
・ The following polymerization initiator (1) 0.100 g
・ The following infrared absorber (1) 0.020 g
・ Polymerizable compound (Aronix M215, manufactured by Toagosei Co., Ltd.) 0.385 g
-0.044 g of the following fluorosurfactant (1)
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g

Microgel solution (1)
-Microgel (1) synthesized as follows: 2.640 g
・ Distilled water 2.425g

(Synthesis of microgel (1))
As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g, And 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. 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 12,000 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 50 ° C. for 3 hours. The solid content concentration of the microgel solution thus obtained was diluted with distilled water so as to be 15% by mass. The average particle size was 0.2 μm.

(3) Formation of Protective Layer After the protective layer coating solution (1) having the following composition was further bar-coated on the image recording layer, it was oven-dried at 120 ° C. for 60 seconds, and the dry coating amount was 0.15 g / m ^2. A lithographic printing plate precursor (1) was obtained.

Protective layer coating solution (1)
-1.5 g of inorganic particle dispersion (1) prepared as follows
・ Polyvinyl alcohol (Poval PVA105) 0.06g
(Kuraray Co., Ltd., saponification degree 98-99 mol%, polymerization degree 500)
・ Polyvinylpyrrolidone (K30) 0.01g
(Wako Pure Chemical Industries, Ltd., mass average molecular weight 400,000)
-Copolymer of vinylpyrrolidone and vinyl acetate LUVITEC VA64W 0.01g
(ICP, copolymerization ratio = 6/4)
・ Nonionic surfactant 0.01g
(Product name: EMALEX 710, manufactured by Nippon Emulsion Co., Ltd.)
・ Ion-exchanged water 6.0g

(Preparation of inorganic particle dispersion (1))
6.4 g of synthetic mica Somasif ME-100 (manufactured by Co-op Chemical) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed inorganic particles was 100 or more.

2. Preparation of lithographic printing plate precursor (2) A lithographic printing plate precursor except that the image recording layer coating solution (1) described in the preparation of the lithographic printing plate precursor (1) is changed to the image recording layer coating solution (2) shown below. A lithographic printing plate precursor (2) was obtained in the same manner as in (1).

Image recording layer coating solution (2)
・ The following infrared absorber (2) 0.05 g
・ 0.20g of the above polymerization initiator (1)
・ 0.50 g of the above binder polymer (1)
Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 1.00 g
・ 0.10 g of the above-mentioned fluorosurfactant (1)
・ Methyl ethyl ketone 18.0g

3. Preparation of lithographic printing plate precursor (3) The following image recording layer coating solution (3) was bar-coated on the above support having an undercoat layer, followed by oven drying at 70 ° C. for 60 seconds, and the dry coating amount. An image recording layer of 0.6 g / m ² was produced.

Image recording layer coating solution (3)
-Polymer fine particle aqueous dispersion prepared as follows: 33.0 g
・ The following infrared absorber (3) 1.0 g
・ Pentaerythritol tetraacrylate 0.5g
・ Methanol 16.0g

(Production of polymer fine particle aqueous dispersion)
A stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser is applied to a 1000 ml four-necked flask, and 350 mL of distilled water is added while deoxygenating by introducing nitrogen gas, and the internal temperature becomes 80 ° C. Until heated. Add 1.5 g of sodium dodecyl sulfate as a dispersant, 0.45 g of ammonium persulfide as an initiator, and then add a mixture of 45.0 g of glycidyl methacrylate and 45.0 g of styrene from the dropping funnel to about 1 It was added dropwise over time. After the completion of the dropwise addition, the reaction was continued as it was for 5 hours, and then the unreacted monomer was removed by steam distillation. Thereafter, the mixture was cooled and adjusted to pH 6 with ammonia water, and finally pure water was added so that the non-volatile content was 15% by mass to obtain an aqueous polymer polymer fine particle dispersion. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 60 nm.

  Here, the particle size distribution is obtained by taking an electron micrograph of polymer fine particles, measuring a total of 5000 fine particle sizes on the photograph, and a logarithmic scale between 0 and the maximum value of the obtained particle size measurement values. And the frequency of appearance of each particle size was plotted and obtained. For non-spherical particles, the particle size of spherical particles having the same particle area as that on the photograph was used as the particle size.

Further, the following protective layer coating solution (2) was bar coated thereon, followed by oven drying at 60 ° C. for 120 seconds to form a protective layer having a dry coating amount of 0.3 g / m ² to form a lithographic printing plate precursor (3 )

Protective layer coating solution (2)
・ Carboxymethylcellulose (mass average molecular weight 20,000) 5.0 g
・ Water 50.0g

[Examples 1 to 7, Comparative Examples 1 and 2]
The obtained lithographic printing plate precursors (1) to (3) were subjected to the following conditions in Table 1 under the conditions of an external drum rotating speed of 150 rpm and a resolution of 2400 dpi using Fuji Photo Film Co., Ltd.'s Luxel PLASETTERT-6000III equipped with an infrared semiconductor laser. It was exposed with a laser output having an exposure energy amount described in 1. The exposure image includes a thin line image in which thin lines having a width of 10 μm are arranged at intervals of 10 μm and a halftone dot chart of 50% of 1 pixel of 10 μm.
The obtained exposed master is not subjected to a development process, and a printing machine Speed manufactured by Heidelberg
It was attached to the master cylinder of Master52. Equality-2 (Fuji Photo Film Co., Ltd.) / Tap water = 2/98 (volume ratio) dampening water and Values-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) were used. After supplying on the machine with dampening water and ink by the standard automatic printing start method of Speed Master 52, printing was performed on Tohishi Art (76.5 kg) paper at a printing speed of 10,000 sheets per hour. .

Measure the ink density (reflection density) of the solid part of the printed matter with a Gretag densitometer, confirm that it is the standard density, and observe the fine line reproducibility and halftone dot reproducibility on the lithographic printing plate. It was evaluated with an indicator.
On the same lithographic printing plate, ΔE of the image area and the non-image area to which ink was adhered was measured using a color difference meter CR-221 (manufactured by Minolta Co., Ltd.).
Further, the dot area of the 50% halftone dot image in the evaluation chart is measured with a Gretag densitometer, and the dot gain amount of the 50% halftone dot is calculated from the difference between the actually measured halftone area and the original halftone dot percentage (= 50%). This was determined and used as a value representative of the tone reproducibility on the plate.
These results are shown in Table 1.

<Thin wire reproducibility evaluation index>
A: A fine line image is not formed at all, and all become non-image portions.
B: Although a fine line image is formed, there is a discontinuity (missing) in a part of thin lines with an average thickness of 6 to 8 μm.
C: Good reproduction with 10 μm fine lines and intervals.
D: Thin line image is thick and average thickness is 12 to 14 μm. Adjacent fine lines are partly continuous.
E: Non-image portions between thin lines are not formed at all, and all become solid portions.

<Stone dot reproducibility evaluation index>
A: A halftone image is not formed at all, and all are non-image portions.
B: A halftone image is formed, but a halftone dot is missing at an average of 6 to 8 μm.
C: The dot of 10 μm is reproduced well.
D: The halftone image is thick, and the average thickness is 12 to 14 μm. Adjacent halftone dots are partly continuous.
E: Non-image portions between halftone dots are not formed at all, and all become solid portions.

  As can be seen from Table 1, according to the exposure condition setting method of the present invention, it is possible to evaluate fine line reproducibility and halftone dot reproducibility for adjusting exposure conditions. Furthermore, it is possible to provide an accurate and easy exposure condition setting method by reducing variations in evaluation of fine line reproducibility and halftone dot reproducibility.

Claims (9)

  An exposure condition setting method for a lithographic printing plate precursor having an image recording layer on a support and capable of being developed on-press by supplying printing ink and / or dampening water, the lithographic printing plate precursor being exposed An exposure condition setting method comprising setting an exposure condition by evaluating an image on a lithographic printing plate obtained by on-machine development.   2. The exposure condition setting method according to claim 1, wherein the exposure amount is set by evaluating reproducibility of fine lines and / or halftone dots on the lithographic printing plate after on-press development.   2. The exposure condition setting method according to claim 1, wherein calibration is set when creating a halftone image of an image original by evaluating tone reproducibility on a lithographic printing plate after on-machine development.   4. The exposure condition setting method according to claim 1, wherein the image recording layer is a layer on which an image is formed by polymerization.   The exposure condition is set by evaluating an image on the lithographic printing plate obtained by on-press development after at least 10 minutes have elapsed after exposure of the lithographic printing plate precursor. The exposure condition setting method according to claim 1.   The exposure condition is set by evaluating an image on a lithographic printing plate obtained by exposing the lithographic printing plate precursor to a plate cylinder of a printing press and developing it on the press. 6. The exposure condition setting method according to any one of 5 above.   The printing ink is attached to the image portion of the lithographic printing plate after on-press development so that ΔE with respect to the non-image portion is 20 or more, and the image is evaluated. The exposure condition setting method according to the item.  A lithographic printing plate making method comprising exposing a lithographic printing plate precursor under the exposure conditions set by the exposure condition setting method according to any one of claims 1 to 7, and developing the lithographic printing plate on-machine.   A lithographic printing plate printing method comprising exposing a lithographic printing plate precursor under the exposure conditions set by the exposure condition setting method according to any one of claims 1 to 7, developing the image on the machine, and performing printing. .