JP2005088403A - Printing plate material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing plate material which is free from scumming during printing and shows high resistance to plate wear and exposure image visibility with excellent color developing properties. <P>SOLUTION: In the printing plate material with constituent layers, some of which are a hydrophilic layer and a thermosensitive imaging layer formed on a base material, one of the constituent layers is formed of a solid resin fine particle containing a coloring matter precursor and further, includes a developer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printing plate material, and more particularly to a printing plate material used in a computer-to-plate (hereinafter referred to as CTP) system.

  At present, in the field of printing, printing by the CTP method has been performed with the digitization of print image data. However, this printing is inexpensive and easy to handle and is equivalent to a conventional so-called PS plate. Therefore, there is a demand for a printing plate material for a CTP system having the following printability.

  In particular, it has a direct imaging (hereinafter referred to as DI) performance that does not require development processing with a special agent in recent years, and can be applied to a printing machine having this function, and has the same usability as the PS plate. There is a need for a general-purpose processless plate.

  On the other hand, generally, the image layer of the PS plate or the printing plate material for CTP that requires development after exposure is colored, and the substrate surface of the image portion and the non-image portion exposed after development (for example, an aluminum support) And a good development visible image property. That is, a plate inspection (visually or using a dedicated device) after development is possible.

  In the CTP method, it is expected that the work of plate inspection will not be performed in the future, but it is necessary in the current workflow.

  In addition, when punching (drilling for mounting) necessary for mounting on a printing press is performed after development, the registration mark image is read with a dedicated device for accurate position adjustment. Contrast with the image portion is required.

  For this reason, in a thermal processless plate that does not require development, visible image quality after image recording, so-called exposure visible image quality, is one of the important performances.

  As a processless plate for DI, for example, ThermoLite (R) manufactured by Agfa Co., Ltd. can be mentioned, but since the plate inspection after exposure is not particularly taken into consideration, it has little exposure visibility.

  A thermal laser recording system having a wavelength of near infrared to infrared is mainly used for image formation of a processless plate. Thermal processless plates that can form images by this method are roughly classified into an ablation type, a thermal fusion image layer on-machine development type, and a phase change type, which will be described later.

  Examples of the ablation type include those described in JP-A-8-507727, JP-A-6-186750, JP-A-6-199064, JP-A-7-314934, JP-A-10-58636, and JP-A-10-244773. Can be mentioned.

  In these, for example, a hydrophilic layer and a lipophilic layer are laminated on a base material with either layer as a surface layer. If the surface layer is a hydrophilic layer, it is possible to form an image portion by exposing it like an image, ablating the hydrophilic layer and removing it like an image to expose the lipophilic layer. However, since contamination inside the exposure apparatus due to the scattered material on the ablated surface layer becomes a problem, a water-soluble protective layer is further provided on the hydrophilic layer to prevent the ablated surface layer from scattering and together with the protective layer on the printing press. A method for removing the ablated surface layer has also been proposed.

  In the case of the ablation type, it is possible to impart exposure visibility by setting the hues of the surface layer and the layer below it to be different, but for this purpose, it is necessary to completely ablate and remove the surface layer. . This can be achieved, for example, by installing a cleaner that sucks and removes the ablation scattered matter in the exposure apparatus, but there is a problem that the apparatus cost increases significantly.

  In the type provided with the protective layer as described above, since the ablation scattered matter remains, even if the hues of the surface layer and the layer below the surface layer are different from each other, good exposure visibility is not obtained.

  As a means for solving the above, a method of “containing 20% by mass or more of a cyanine-based infrared-absorbing dye whose optical density can be changed by exposure in a hydrophilic overcoat layer removable on a printing press” is disclosed. (See Patent Document 1). Although this method surely provides good exposure visibility, it contains a large amount of dye in the layer to be removed on the printing press, and it is exposed whether the dye is further developed or faded by exposure. Since either the unexposed portion or the unexposed portion is a layer having a high color density, contamination of the printing press due to on-press development is inevitable.

  On the other hand, as the development type on the heat fusion image layer machine, as disclosed in Japanese Patent No. 2938397 and Japanese Patent No. 2938397, the hydrophilic layer or the aluminum fine grain and the thermoplastic fine particles and the water-soluble bond are formed on the image forming layer. And those using the agent. The above-mentioned ThermoLite manufactured by Agfa is a processless plate of this type.

  In order to provide exposure visible image quality with this type, there is one that utilizes the exposure fading of an infrared absorbing dye, but when such a dye is added to the image forming layer, the color difference between the unexposed area and the exposed area. Increasing the exposure visibility to improve the exposure visibility, that is, increasing the color density of the unexposed area, causing a problem of printer contamination during on-press development of the unexposed area (see Patent Document 2). .

  In addition, as a phase change type, as described in the above-mentioned Patent Document 2, a hydrophilic layer that is not removed during printing contains hydrophobized precursor particles, and the exposed portion is changed from hydrophilic to lipophilic. It is possible to change the phase.

  In order to provide the exposure visible image property with this type, one using the exposure fading of the infrared absorbing dye as described above may be used. However, in order to maintain the hydrophilicity of the hydrophilic layer, it is preferable to use an infrared-absorbing dye that is also hydrophilic, that is, a water-soluble dye. In this case, the dye is moistened during printing and eluted in water. There is a concern that contamination of the printing press will be a problem. On the other hand, when a water-insoluble dye is used so that the dye does not elute, the hydrophilicity of the hydrophilic layer is lowered, causing problems such as soiling.

  Another method of imparting visible exposure to a phase change type is to use a heat-sensitive element comprising a colorless basic dye (dye precursor) and a developer (see Patent Document 3). When such a dye precursor and developer are used in a dispersed mixture, pressure-sensitive color development may occur in addition to heat-sensitive color development, which requires careful handling and storage stability is insufficient. It is.

In addition, printing plate materials having a thermal image forming layer have been known as a method for imparting exposure visible imageability to a printing plate material having a microcapsule containing a dye precursor and a layer containing a developer (patent). (Refer to Document 4.), there are problems that background staining may occur during printing, and printing durability is insufficient.
JP 2002-205466 A JP-A-11-140270 Japanese Examined Patent Publication No. 2-56231 JP 2000-225780 A

  An object of the present invention is to provide a printing plate material which is free from background stains during printing, has excellent printing durability, and has excellent exposure and visible image properties.

The object of the present invention is achieved by the following constitution.
(Claim 1)
In a printing plate material having a constituent layer including a hydrophilic layer and a heat-sensitive image forming layer on a substrate, one of the constituent layers includes solid resin fine particles containing a dye precursor, and one of the constituent layers. A printing plate material characterized in that one contains a developer.
(Claim 2)
The printing plate material according to claim 1, wherein the dye precursor is coated with a solid resin.
(Claim 3)
3. The printing plate material according to claim 1, wherein an average particle diameter of the solid resin fine particles of the constituent layer containing the solid resin fine particles is 0.1 μm or more and 1 μm or less.
(Claim 4)
4. The printing plate material according to claim 1, wherein one of the constituent layers contains a photothermal conversion material.
(Claim 5)
5. The hydrophilic layer or a constituent layer on the surface side adjacent to the hydrophilic layer contains the solid resin fine particles, and the thermal image forming layer is a layer that can be developed on-press. Printing plate material.
(Claim 6)
6. The printing plate material according to claim 1, wherein the hydrophilic layer contains the solid resin fine particles and a hydrophilic material that is substantially insoluble in water.
(Claim 7)
The printing plate material according to claim 1, wherein the constituent layer containing the solid resin fine particles and the constituent layer containing the developer are different layers.
(Claim 8)
The printing plate material according to claim 7, wherein the constituent layer containing the solid resin fine particles and the constituent layer containing the developer are adjacent to each other.
(Claim 9)
9. The printing plate material according to claim 1, further comprising a constituent layer not containing the solid resin fine particles on a surface layer side of the constituent layer containing the solid resin fine particles.
(Claim 10)
9. The printing plate material according to claim 7, wherein the constituent layer containing the developer is on the surface layer side of the constituent layer containing the solid resin fine particles.
(Claim 11)
The printing plate material according to claim 1, wherein the developer is contained in the form of particles.

  According to the present invention, it is possible to provide a printing plate material which is free from background stains during printing, has excellent printing durability, and has excellent exposure and visible image properties.

  Hereinafter, the present invention will be described in detail.

  The present invention relates to a printing plate material having a hydrophilic layer and a heat-sensitive image forming layer on a substrate, wherein one of the constituent layers includes solid resin fine particles containing a dye precursor, and one of the constituent layers is revealed. A printing plate material containing a colorant.

  In the present invention, by including the dye precursor as a solid particle together with the resin in the constituent layer, it is possible to obtain a printing plate material free of background stains, excellent in printing durability, and having good exposure visibility. .

  The solid resin particles in the present invention are resin particles that do not contain a solvent or the like in a liquid state and have a particle size of 10 μm or less. The form of the fine particles is not particularly limited as long as the solid resin is continuous, and may be a porous body or a hollow body.

  Here, the particle diameter means a diameter of a circle having the largest area among circles having the same area as the projected area of the particles.

  The solid resin fine particles may contain the dye precursor mixed at the molecular level, may contain the dye precursor in a solid state, or may contain the dye precursor in a mixed state.

  Among these, a form in which the dye precursor is coated with a solid resin is particularly preferably used.

  In this case, “covered” means that 70% or more of the surface area of the resin fine particles is covered with a solid resin, more preferably 90% or more, particularly 99% or more. preferable.

  The case where the average particle diameter of the solid resin fine particles contained in the constituent layer of the present invention is 0.1 μm or more and 1 μm or less is particularly preferably used in terms of sensitivity and printing durability.

  The average particle diameter is a value measured as follows.

  The average particle diameter is a value measured by a known laser diffraction / scattering particle distribution measuring apparatus (for example, LA-300 manufactured by HORIBA), and the peak value of the particle distribution curve is defined as the average particle diameter.

  In the present invention, the present invention can be particularly advantageously applied when one of the constituent layers is a layer containing a photothermal conversion material, that is, in the case of a photosensitive printing plate material that forms an image by image exposure with a laser beam or the like.

  Further, the hydrophilic layer or the constituent layer adjacent to the hydrophilic layer on the surface side (the side opposite to the substrate side) contains solid resin fine particles, and the thermal image forming layer is a layer that can be developed on-machine. In particular, the effect is great.

  Furthermore, it is also preferable that the hydrophilic layer contains solid fine particles and a hydrophilic material that is substantially insoluble in water.

  Here, the on-machine developable layer refers to a non-image area at the time of printing by using dampening water and printing ink at the time of being subjected to the printing process without passing through the development process after image exposure. This is a layer in which the image forming layer in the portion to be removed is removed and a printable image can be formed.

  In the present invention, the case where the constituent layer containing the solid resin fine particles and the constituent layer containing the developer are different is particularly preferable.

  In that case, it is particularly preferable that the respective constituent coarses are adjacent to each other. Further, the constituent layer containing the developer is on the surface layer side with respect to the base material than the constituent layer containing the solid resin fine particles (what is the base material? Preferably on the opposite side.

  Moreover, it is preferable to provide a structure that does not contain solid resin fine particles on the surface layer side with respect to the base material than the layer containing solid resin fine particles.

  The dye precursor of the present invention is a compound capable of forming a dye by reacting with the developer of the present invention, and an electron donating dye precursor is particularly preferably used. As the electron donating dye precursor, known materials used for heat-sensitive recording paper can be used.

  For example, various compounds such as diphenylmethane such as triallylmethane and leucooramine represented by crystal violet lactone, spiropyran, fluoran, rhodamine lactam, and caribazolylmethane are listed.

  Further, compounds represented by the general formula (I) described in JP-A-6-210947 can also be used.

Specific examples of the dye precursor used in the present invention will be given below.
(1) Triarylmethane compounds 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- ( p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- ( p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3- Bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5 -Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl)- 6-dimethylaminophthalide and the like.
(2) Diphenylmethane compounds 4,4′-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-halophenyl leucooramine, 2,4,5-trichlorophenyl leucooramine and the like.
(3) Xanthene compounds Rhodamine B anilinolactam, rhodamine Bp-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7 -Phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino- 7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane, 3- Piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-to Ryl) amino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-methyl- N-propyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N- (Cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluorane, and the like.
(4) Thiazine compounds benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, and the like.
(5) Spiro compounds 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3′-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho (3-methoxybenzo) ) Spiropyran, 3-propyl spirobenzopyran and the like.

  These can be used alone or in admixture of two or more.

  The developer of the present invention is a compound that can react with the dye precursor to form a dye.

  As the developer that can be used in the present invention, a known inorganic or organic developer can be used, and an organic electron-accepting developer is particularly preferable.

  As the organic electron-accepting developer, known materials such as those described in JP-A-6-99663, JP-A-7-52551, and JP-A-8-258420 used for thermal recording paper are preferably used. be able to.

  For example, acidic substances such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and their metal salts, and oxyesters can be preferably used.

  Specifically, 2,2-bis (4′-hydroxyphenyl) propane (generic name bisphenol A), 2,2-bis (4′-hydroxyphenyl) pentane, 2,2-bis (4′-hydroxy-) 3 ′, 5′-dichlorophenyl) propane, 1,1-bis (4′-hydroxyphenyl) cyclohexane, 2,2-bis (4′-hydroxyphenyl) hexane, 1,1-bis (4′-hydroxyphenyl) Propane, 1,1-bis (4′-hydroxyphenyl) butane, 1,1-bis (4′-hydroxyphenyl) pentane, 1,1-bis (4′-hydroxyphenyl) hexane, 1,1-bis ( 4′-hydroxyphenyl) heptane, 1,1-bis (4′-hydroxyphenyl) octane, 1,1-bis (4′-hydroxyphenyl) -2-methyl Pentane, 1,1-bis (4′-hydroxyphenyl) -2-ethyl-hexane, 1,1-bis (4′-hydroxyphenyl) dodecane, 1,4-bis (p-hydroxyphenylcumyl) benzene, Bisphenols such as 1,3-bis (p-hydroxyphenylcumyl) benzene, bis (p-hydroxyphenyl) sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, bis (p-hydroxyphenyl) acetic acid benzyl ester , 3,5-di-α-methylbenzylsalicylic acid, 3,5-di-tertiarybutylsalicylic acid, 3-α-α-dimethylbenzylsalicylic acid, 4- (β-p-methoxyphenoxyethoxy) salicylic acid, etc. Derivatives or their polyvalent metal salts (especially zinc and aluminum are preferred), p-hydroxy Oxybenzoates such as benzyl ertel benzoate, p-hydroxybenzoic acid-2-ethylhexyl ester, β-resorcinic acid- (2-phenoxyethyl) ester, p-phenylphenol, 3,5-diphenylphenol, Examples of the phenol include milphenol, 4-hydroxy-4′-isopropoxy-diphenylsulfone, and 4-hydroxy-4′-phenoxy-diphenylsulfone, but are not limited thereto.

  The resin in the present invention is a resin that can form particles in a solid state together with the dye precursor. As the resin used for the solid resin fine particles containing the dye precursor of the present invention, a capsule walling agent resin used for a known microcapsule can be used, but a polyurea obtained by polymerizing the following polymerization components, Polyurea-polyurethane is preferably used.

  Examples of the polymerization component include hexamethylene diisocyanate, hexamethylene diisocyanate trimethylolpropane adduct, hexamethylene diisocyanate biuret, hexamethylene diisocyanate isocyanurate, dicyclohexylmethane-4,4'-diisocyanate, 5-isocyanato-1. And polyisocyanate compounds such as-(isocyanatomethyl) -1,3,3-trimethylcyclohexane.

  Examples of the resin that can be used in the present invention include thermoplastic resins such as polyethylene, polystyrene, polyamide, polyvinyl alcohol, and polysulfone.

  To produce solid resin fine particles containing a dye precursor, a method of applying a coating liquid containing a resin to the dye precursor particles and drying, a method of mixing and heating the dye precursor particles and the resin particles The following method using a resin polymerization step is preferably used.

  For example, as a method of incorporating a dye precursor into a resin, for example, a method of complexing with a polyurea or polyurea-polyurethane resin as described in JP-A-9-262457 can be mentioned.

  Specifically, an electron donating dye precursor and a polyvalent isocyanate compound are dissolved in an organic solvent having a boiling point of less than 100 ° C., and this solution is dissolved in an aqueous solution in which a water-soluble polymer compound having a protective colloid action is dissolved. Emulsified and dispersed, and this dispersion is heated to volatilize and remove the organic solvent, or after volatilization and removal, the polymerization component in the fine particle phase containing the electron-donating dye precursor that has been emulsified and dispersed is polymerized. By doing so, fine particles in which the electron-donating dye precursor and the polyurea or polyurea-polyurethane resin are combined can be obtained.

  By appropriately adjusting the organic solvent volatilization removing step and the polymerization step, it is also possible to obtain fine particles in a state in which a core mainly containing an electron donating dye precursor is coated with a resin.

  Since the substance to be included does not substantially contain a solvent, there is no problem in sensitivity and printing durability even if the resin film to be coated is porous. It is preferable that it is porous in terms of exposure visibility.

  This can be produced, for example, by performing the polymerization step without completely evaporating the solvent in the solvent volatilization step, and controlling the solvent to volatilize to form pores while forming the polymer film.

  In the present invention, the effect of the present invention can be remarkably exhibited by coating the dye precursor with a resin.

  When coated with a resin, it is possible to increase the content ratio of the dye precursor to the solid particles, prevent scumming during printing, improve printing durability, and at the same time provide excellent exposure visibility. The printing plate material which has is obtained.

  The content of the dye precursor with respect to the solid resin fine particles is preferably 10 to 90% by mass, more preferably 20 to 70% by mass from the viewpoint of storage stability.

  Further, the solid resin fine particles containing the dye precursor of the present invention form fine oil phase droplets by emulsifying and dispersing the oil phase component in the water phase component, and volatilize the organic solvent from the oil phase droplets. When a method such as removal is used, resin fine particles having a particle diameter smaller than that of general microcapsules can be produced.

  In a preferred embodiment of the present invention, the average particle diameter of the resin fine particles is 0.1 μm or more and 1 μm or less, particularly in the range of 0.3 μm to 0.8 μm, from the viewpoints of printing durability and storage stability.

  Examples of the photothermal conversion material include the following dyes and pigments.

  Examples of the dye include organic compounds such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, which are general infrared absorbing dyes, phthalocyanines , Naphthalocyanine-based, azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes. Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-1-280750, JP-A-1-293342, JP-A-2-2074, Kaihei 3-26593, JP-A-3-30991, JP-A-3-34891, JP-A-3-36093, JP-A-3-36094, JP-A-3-36095, JP-A-3-42281, JP-A-3-42281 Examples thereof include compounds described in JP-A-3-97589, JP-A-3-103476, and the like. These can be used alone or in combination of two or more.

  JP-A-11-240270, JP-A-11-265062, JP-A-2000-309174, JP-A-2002-49147, JP-A-2001-162965, JP-A-2002-144750, JP-A-2001-219667. The compounds described in (1) can also be preferably used.

  Examples of the pigment include carbon, graphite, metal, metal oxide and the like.

  As carbon, furnace black or acetylene black is particularly preferable. The particle size (d50) is preferably 100 nm or less, and more preferably 50 nm or less.

  As the graphite, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.

  As the metal, any metal can be used as long as the particle diameter is 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less. The shape may be any shape such as a spherical shape, a piece shape, or a needle shape. Colloidal metal fine particles (Ag, Au, etc.) are particularly preferable.

  As the metal oxide, a material that is black in the visible light region, or a material that has conductivity or is a semiconductor can be used.

  Examples of the former include black iron oxide and black composite metal oxides containing two or more metals.

Examples of the latter include SnO ₂ doped with Sb (ATO), In ₂ O ₃ doped with Sn (ITO), TiO ₂ , TiO ₂ with reduced TiO ₂ (titanium oxynitride, generally titanium black), etc. Is mentioned. Further, it can also be used those obtained by coating the core material _{(BaSO 4, TiO 2, 9Al} 2 O 3 · 2B 2 O, K 2 O · nTiO 2 , etc.) in these metal oxides. These particle sizes are 0.5 μm or less, preferably 100 nm or less, and more preferably 50 nm or less.

  Among these photothermal conversion materials, black iron oxide and black composite metal oxides containing two or more metals are more preferable materials.

The black iron oxide (Fe ₃ O ₄ ) is preferably particles having an average particle diameter of 0.01 to 1 μm and an acicular ratio (major axis diameter / minor axis diameter) of 1 to 1.5. It is preferably substantially spherical (acicular ratio 1) or has an octahedral shape (acicular ratio about 1.4).

  Examples of such black iron oxide particles include TAROX series manufactured by Titanium Industry Co., Ltd. As the spherical particles, BL-100 (particle diameter 0.2 to 0.6 μm), BL-500 (particle diameter 0.3 to 1.0 μm), or the like can be preferably used. Further, as octahedral shaped particles, ABL-203 (particle size 0.4 to 0.5 μm), ABL-204 (particle size 0.3 to 0.4 μm), ABL-205 (particle size 0.2 to 0) .3 μm), ABL-207 (particle size: 0.2 μm) and the like can be preferably used.

Furthermore, particles whose surface is coated with an inorganic substance such as SiO ₂ can also be preferably used. As such particles, spherical particles coated with SiO ₂ : BL-200 (particle size 0.2 to 0) .3 μm), octahedral shaped particles: ABL-207A (particle size 0.2 μm).

  Specifically, the black composite metal oxide is a composite metal oxide composed of two or more metals selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb, and Ba. . These are disclosed by methods disclosed in JP-A-8-27393, JP-A-9-25126, JP-A-9-237570, JP-A-9-241529, JP-A-10-231441, and the like. Can be manufactured.

  The composite metal oxide used in the present invention is particularly preferably a Cu-Cr-Mn-based or Cu-Fe-Mn-based composite metal oxide. In the case of a Cu—Cr—Mn system, it is preferable to perform the treatment disclosed in JP-A-8-27393 in order to reduce the elution of hexavalent chromium. These composite metal oxides are colored with respect to the amount added, that is, they have good photothermal conversion efficiency.

  These composite metal oxides preferably have an average primary particle size of 1 μm or less, and more preferably have an average primary particle size in the range of 0.01 to 0.5 μm. When the average primary particle diameter is 1 μm or less, the photothermal conversion ability with respect to the addition amount becomes better, and when the average primary particle diameter is within the range of 0.01 to 0.5 μm, the photothermal conversion ability with respect to the addition amount is obtained. Better.

  However, the photothermal conversion ability with respect to the addition amount is greatly affected by the degree of dispersion of the particles, and the better the dispersion, the better. Therefore, it is preferable to disperse these composite metal oxide particles by a known method separately before adding them to the layer coating solution to prepare a dispersion (paste).

  A dispersing agent can be appropriately used for the dispersion. The addition amount of the dispersant is preferably 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass with respect to the composite metal oxide particles.

  Among these, in the present invention, it is preferable to use a dye, and it is more preferable to use a dye that is less colored with visible light.

  As one of the preferred embodiments of the printing plate material of the present invention, as described above, the constituent layer containing the solid resin fine particles containing the dye precursor is a hydrophilic layer or a constituent layer on the surface side adjacent to the hydrophilic layer. And a printing plate material in which the heat-sensitive image forming layer is a layer having on-press developability.

  In this case, the developer is preferably contained in a layer containing solid resin fine particles containing a dye precursor or in an upper layer (surface side) thereof.

  Specifically, for example, a hydrophobized precursor particle described later on a substrate having a hydrophilic layer described later (for example, aluminum having an aluminum grain or a plastic film or metal having a hydrophilic layer formed on the surface). And a printing plate material provided with an on-press developable image forming layer containing heat fusible fine particles and heat fusible fine particles.

  In this embodiment, the photothermal conversion material is preferably contained in the heat-sensitive image forming layer or the hydrophilic layer.

  By the infrared laser exposure, the exposed portion develops color and becomes an image portion that is not removed on the printing press by heating. The image layer in the unexposed area developed on the machine does not develop color, so it is not contaminated with the printing machine, and is removed mainly by the ink roller and finally moves to the printing paper.

  The on-press developability of the image forming layer on a printing press is related to the particle size of the contained fine particles, and tends to be difficult to develop as the particle size decreases. In the present invention, by allowing the dye precursor to be present as solid fine particles together with the resin, it is possible to improve background stains and printing durability while maintaining good on-machine developability even when fine particles of 1 μm or less are formed. Became possible.

  The inorganic material (mainly silica and alumina) used for the material of the grain surface and hydrophilic layer itself is a solid acid that functions as a color developer for the dye precursor, and is easy to react with the dye precursor. It is considered to be a material with high affinity, and when a dye precursor single particle size reduced to 1 μm or less is used, it is difficult to be removed from the grained surface or hydrophilic layer surface and developed on-machine. It is thought that the nature deteriorates greatly and causes soiling.

  On the other hand, in the case of solid resin fine particles containing the dye precursor of the present invention, preferably fine particles in which the periphery of the dye precursor is coated with resin, the affinity with the grained surface or the hydrophilic layer surface decreases. For this reason, it is considered that good on-press developability is obtained even if the particle size is reduced to 1 μm or less, and that no background staining occurs.

  As one of preferred embodiments of the printing plate material of the present invention, the constituent layer containing solid resin fine particles containing a dye precursor is a hydrophilic layer containing a hydrophilic material that is substantially insoluble in water. Examples include plate materials.

  This means that the constituent layer containing the solid resin fine particles is a hydrophilic layer that is not substantially removed on the printing press during printing. In this embodiment, since the dye precursor solid particles developed by exposure are also held and fixed in the hydrophilic material matrix, there is a low possibility that the colored material is detached and causes printing press contamination.

  Since the dye precursor itself is usually not a hydrophilic material, the hydrophilicity of the hydrophilic layer tends to deteriorate when fine particles of the dye precursor alone are contained in the hydrophilic layer. In addition, since the dye precursor itself is not a material that forms a strong coating film by combining with a component that functions as a binder in the hydrophilic layer, the strength of the hydrophilic layer tends to deteriorate when it is contained. is there. The above-mentioned tendency is conspicuous because the specific surface area of the fine particles increases as the particle size of the fine particles of the dye precursor alone decreases. This is generally considered to lead to background stains and printing durability during printing.

  One preferred embodiment of the printing plate material of the present invention includes a printing plate material in which the constituent layer containing solid resin fine particles containing a dye precursor is different from the constituent layer containing a developer. .

  By containing the dye precursor and the developer in separate layers, the preservability is further improved.

  Further, as described above, another preferable embodiment of the printing plate material of the present invention includes a printing plate material having a constituent layer not containing solid resin fine particles on the surface layer side of the constituent layer containing solid resin fine particles. Can be mentioned.

  For example, a configuration in which the constituent layer containing the dye precursor solid particles is a hydrophilic layer described later, and a thermal image forming layer described later is provided thereon. In the case of this embodiment, the developer can be contained as fine particles in the hydrophilic layer, or can be contained in the image forming layer to further improve the storage stability.

  The constituent layer containing solid resin fine particles containing a dye precursor is a phase-changeable hydrophilic layer further containing hydrophobized precursor fine particles, and a protective layer (water-soluble, water-swellable) is formed thereon. Is preferable). Also in this embodiment, the developer can be contained in the hydrophilic layer capable of phase change as fine particles, or can be contained in the protective layer to improve the storage stability.

  In this embodiment, since the color-developing layer is not the outermost layer of the printing plate material, for example, the dye precursor and the developer are heated to a temperature that greatly exceeds the melting point due to rapid heat generation by infrared laser exposure. Even in this case, there is no concern that the colored dye is sublimated and scattered from the surface of the printing plate material, and the printing plate material can be free of contamination of the exposure apparatus under a wide range of exposure conditions.

  As a preferable image forming method using the printing plate material of the present invention, an infrared laser such as an image forming by an infrared laser ablation method, an image forming by an infrared laser heat melting / heat fusing method (on-press development, phase change), etc. The various image forming methods used can be mentioned.

  As a particularly preferred embodiment, a hydrophilic layer described later is provided on a base material, and a heat-meltable material described later is further provided with a heat-sensitive image forming layer containing a heat-fusible material. Examples include an on-press development type printing plate material of a heat fusion type.

  The developer used in the printing plate material of the present invention is more preferably contained in the form of fine particles.

  The developer melts and flows with heat and develops color when it comes into contact with the dye precursor of solid resin fine particles containing the dye precursor. Therefore, the larger the specific surface area of the developer, the easier it is to melt, that is, the color develops. It becomes easy. The average particle size is preferably 0.1 to 1 μm.

  The fine particles of the developer can be obtained as an aqueous dispersion by wet dispersion by a known method such as a sand grinder together with the dispersant.

  As the dispersant, a known surfactant (nonionic or anionic) and / or a water-soluble polymer can be used. Among water-soluble polymers, methyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, polyethylene glycol, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether sulfate, and 2-ethylhexyl sulfosuccinate soda can be preferably used.

Further, as described in JP-A-5-229252, an organic solvent in which a developer is dissolved is dispersed and emulsified in water, and then the organic solvent is volatilized and removed to obtain a fine particle dispersion of the developer. The method can also be preferably used.
[Base material]
The base material of the present invention is a plate-like body or a film body that can carry a constituent layer including a hydrophilic layer and a heat-sensitive image forming layer, and a known material used as a base material for a printing plate can be used. .

  For example, a metal plate, a plastic film, paper treated with a polyolefin, a composite base material obtained by appropriately bonding the above materials, and the like can be given.

  The thickness of the base material is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.

  Examples of the metal plate used as the substrate include iron, stainless steel, and aluminum. Aluminum is particularly preferable from the relationship between specific gravity and rigidity. The aluminum plate is usually used after degreasing with an alkali, an acid, a solvent or the like in order to remove oil used during rolling and winding existing on the surface.

  As the degreasing treatment, degreasing with an alkaline aqueous solution is particularly preferable. Moreover, in order to improve adhesiveness with a coating layer, it is preferable to perform an easily bonding process and undercoat layer application | coating to an application surface. For example, a method of dipping in a liquid containing a coupling agent such as a silicate or a silane coupling agent, or applying a liquid and then sufficiently drying may be mentioned. Anodizing treatment is also considered as a kind of easy adhesion treatment and can be used. A combination of the anodizing treatment and the dipping or coating treatment can also be used.

  In addition, an aluminum base material roughened by a known method, that is, an aluminum base material having a hydrophilic layer obtained by subjecting so-called aluminum sand to a hydrophilic treatment, may be used as a base material having a hydrophilic layer. it can.

  Examples of the plastic film include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters.

  As the substrate used in the present invention, polyethylene terephthalate and polyethylene naphthalate are particularly preferable. These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve the adhesion to the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment. Examples of the undercoat layer include a layer containing gelatin or latex. The undercoat layer may contain an organic or inorganic known conductive material.

In addition, for the purpose of controlling the slipperiness of the back surface (for example, reducing the friction coefficient with the plate cylinder surface), a substrate provided with a back surface coating layer can also be preferably used.
[Hydrophilic layer]
The hydrophilic layer of the present invention is a layer that can be a non-image area where printing ink is not attached during printing, and is a layer formed on a substrate, or a surface layer when a substrate surface is made hydrophilic It is. The hydrophilic layer contains a hydrophilic material.

  One aspect of the printing plate material used in the present invention is an aspect having a hydrophilic layer on a substrate. The hydrophilic layer may be a single layer or may be formed from a plurality of layers.

The amount with the hydrophilic layer is preferably ^{0.1~10g / m 2, 0.2~5g / m} 2 is more preferable.

  One embodiment of the present invention includes an embodiment in which solid resin fine particles containing a dye precursor are contained in the hydrophilic layer. As content of the solid resin fine particle containing the pigment precursor in a hydrophilic layer, 5-70 mass% is preferable with respect to a hydrophilic layer, and 10-50 mass% is more preferable.

  As the hydrophilic material used for the hydrophilic layer, a hydrophilic material that is substantially insoluble in water is preferable, and a metal oxide is particularly preferable.

  The metal oxide preferably contains metal oxide fine particles. Examples thereof include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The form of the metal oxide fine particles may be spherical, needle-like, feather-like, or any other form. The average particle diameter is preferably 3 to 100 nm, and several kinds of metal oxide fine particles having different average particle diameters can be used in combination. The surface of the particles may be surface treated.

  The metal oxide fine particles can be used as a binder by utilizing the film forming property. The decrease in hydrophilicity is less than when an organic binder is used, and it is suitable for use in a hydrophilic layer.

  Among the above, colloidal silica can be preferably used in the present invention. Colloidal silica has the advantage of high film-forming properties even under relatively low temperature drying conditions, and good strength can be obtained even in a layer in which the material containing no carbon atom is 91% by mass or more.

  The colloidal silica preferably includes necklace-like colloidal silica and fine particle colloidal silica having an average particle size of 20 nm or less, and the colloidal silica preferably exhibits alkalinity as a colloidal solution.

  The necklace-like colloidal silica used in the present invention is a general term for an aqueous dispersion of spherical silica whose primary particle diameter is on the order of nm. The necklace-like colloidal silica used in the present invention means “pearl necklace-like” colloidal silica in which spherical colloidal silica having a primary particle diameter of 10 to 50 nm is bonded to a length of 50 to 400 nm. The pearl necklace shape (that is, the pearl necklace shape) means that the image in a state in which the silica particles of colloidal silica are connected and connected has a shape like a pearl necklace. The bond between the silica particles constituting the necklace-shaped colloidal silica is presumed to be —Si—O—Si— in which —SiOH groups present on the surface of the silica particles are dehydrated. Specific examples of the colloidal silica in the form of necklace include “Snowtex-PS” series manufactured by Nissan Chemical Industries, Ltd.

  Product names include “Snowtex-PS-S (average particle size in the connected state is about 110 nm)”, “Snowtex-PS-M (average particle size in the connected state is about 120 nm)” and “Snowtex- PS-L (the average particle size in the connected state is about 170 nm) ", and acidic products corresponding to these are" Snowtex-PS-SO "," Snowtex-PS-MO "and “Snowtex-PS-LO”.

  By adding necklace-like colloidal silica, it becomes possible to maintain the strength while ensuring the porosity of the layer, and it can be preferably used as a porous material for the layer.

  Among these, when “Snowtex PS-S”, “Snowtex PS-M”, and “Snowtex PS-L”, which are alkaline, are used, the strength of the hydrophilic layer is improved and the number of printed sheets is large. However, it is particularly preferable because the occurrence of soiling is suppressed.

  Further, it is known that the colloidal silica has a stronger binding force as the particle diameter is smaller, and it is preferable to use colloidal silica having an average particle diameter of 20 nm or less in the present invention, and more preferably 3 to 15 nm. preferable. In addition, as described above, alkaline colloidal silica is particularly preferable because alkaline colloidal silica has a high effect of suppressing the occurrence of soiling.

  Alkaline colloidal silica having an average particle size within this range includes “Snowtex-20 (particle size 10-20 nm)”, “Snowtex-30 (particle size 10-20 nm)”, “Snowtex” manufactured by Nissan Chemical Co., Ltd. -40 (particle diameter 10-20 nm) "," Snowtex-N (particle diameter 10-20 nm) "," Snowtex-S (particle diameter 8-11 nm) "," Snowtex-XS (particle diameter 4-6 nm) ) ".

  Colloidal silica having an average particle size of 20 nm or less is particularly preferable because it can be further improved in strength while maintaining the porous property of the layer when used in combination with the aforementioned necklace-like colloidal silica.

  The ratio of colloidal silica / necklace-shaped colloidal silica having an average particle diameter of 20 nm or less is preferably 95/5 to 5/95 (mass ratio), more preferably 70/30 to 20/80, and 60/40 to 30/70. Is more preferable.

  The hydrophilic layer of the printing plate material of the present invention preferably contains porous metal oxide particles as a metal oxide. As the porous metal oxide particles, porous silica, porous aluminosilicate particles, or zeolite particles can be preferably used.

  The porous silica particles are generally produced by a wet method or a dry method. In the wet method, it can be obtained by drying and pulverizing a gel obtained by neutralizing an aqueous silicate solution, or by pulverizing a precipitate deposited after neutralization. In the dry method, silicon tetrachloride is burned together with hydrogen and oxygen to obtain silica. These particles can be controlled in porosity and particle size by adjusting production conditions.

  As the porous silica particles, those obtained from a wet gel are particularly preferable.

  The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764. That is, amorphous composite particles synthesized by hydrolysis using aluminum alkoxide and silicon alkoxide as main components. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. In addition, those produced as composite particles of three or more components by adding an alkoxide of another metal during production can also be used in the present invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.

  The porosity of the particles is preferably 1.0 ml / g or more in terms of pore volume before dispersion, more preferably 1.2 ml / g or more, and 1.8 to 2.5 ml / g. More preferably, it is as follows.

  The particle size is preferably substantially 1 μm or less, and more preferably 0.5 μm or less, in a state where it is contained in the hydrophilic layer (including when crushed during dispersion, for example).

  The particle diameter of the porous inorganic particles is preferably substantially 1 μm or less, and more preferably 0.5 μm or less, when contained in the hydrophilic layer.

  In addition, the hydrophilic layer of the printing plate material of the present invention may contain layered clay mineral particles as a metal oxide. The layered mineral particles include kaolinite, halloysite, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), clay minerals such as vermiculite, mica (mica), chlorite, hydrotalcite, layered polysilicate ( Kanemite, macatite, ialite, magadiite, kenyaite, etc.). Among them, it is considered that the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of the layered mineral having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge) and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size. Among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.

  Also used are intercalation compounds of the above-mentioned layered minerals (pillar crystals, etc.), those subjected to ion exchange treatment, and those subjected to surface treatment (silane coupling treatment, compounding treatment with organic binder, etc.) can do.

  As the size of the layered mineral particles, the average particle diameter (maximum length of the particles) is 20 μm or less in the state of being contained in the layer (including the case where the swelling process and the dispersion peeling process are performed), and the average aspect The ratio (maximum particle length / particle thickness) is preferably a thin layer of 20 or more, the average particle size is 5 μm or less, the average aspect ratio is more preferably 50 or more, and the average particle size is More preferably, it is 1 μm or less and the average aspect ratio is 50 or more. When the particle size is in the above range, the continuity and flexibility in the planar direction, which are the characteristics of the thin layered particles, are imparted to the coating film, and it is difficult for cracks to occur, and a tough coating film can be obtained in a dry state. Moreover, in the coating liquid containing many particulate matters, sedimentation of particulate matter can be suppressed by the thickening effect of the layered clay mineral.

  The content of the layered mineral particles is preferably 0.1 to 30% by mass, and more preferably 1 to 10% by mass based on the entire layer. In particular, swellable synthetic fluorinated mica and smectite are preferable because they are effective even when added in a small amount. The layered mineral particles may be added as a powder to the coating solution, but in order to obtain a good degree of dispersion even with a simple preparation method (no need for a dispersion step such as media dispersion), the layered mineral particles are used alone. It is preferable that the gel swollen in water is prepared and then added to the coating solution.

A silicate aqueous solution can also be used as another additive material in the hydrophilic layer of the present invention. Alkali metal silicates such as silicate Na, silicate K, and silicate Li are preferred, and the SiO ₂ / M ₂ O ratio is in a range where the pH of the entire coating solution does not exceed 13 when silicate is added. It is preferable to select such that the inorganic particles are not dissolved.

  Further, an inorganic polymer or an organic-inorganic hybrid polymer using a metal alkoxide by a so-called sol-gel method can also be used. The formation of an inorganic polymer or an organic-inorganic hybrid polymer by the sol-gel method is described in, for example, “Application of the sol-gel method” (Sakuo Sakuo / Published by Agne Jofusha) or cited in this book. Known methods described in the published literature can be used.

  In the present invention, a hydrophilic organic resin may be contained in the hydrophilic layer.

  Examples of hydrophilic organic resins include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, and acrylic. Examples thereof include resins such as polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone.

  In addition, the resin may contain a cationic resin. Examples of the cationic resin include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine or derivatives thereof, and acrylic resins having a tertiary amino group or a quaternary ammonium group. , Diacrylamine and the like. The cationic resin may be added in the form of fine particles. Examples thereof include a cationic microgel described in JP-A-6-161101.

  As a more preferred embodiment of the present invention, the hydrophilic organic resin contained in the hydrophilic layer is water-soluble, and at least part of the hydrophilic organic resin remains in a water-soluble state and exists in a state that can be eluted in water. Can be mentioned.

  As the water-soluble material contained in the hydrophilic layer of the present invention, saccharides are preferable.

  As the saccharide, an oligosaccharide, which will be described in detail later, can be used, but it is particularly preferable to use a polysaccharide.

  As polysaccharides, starches, celluloses, polyuronic acids, pullulans and the like can be used, but cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, hydroxyethyl cellulose salts are particularly preferable, and sodium salts and ammonium salts of carboxymethyl cellulose are preferable. More preferred.

  This is because an effect of forming the surface shape of the hydrophilic layer in a preferable state can be obtained by including the polysaccharide in the hydrophilic layer.

  The surface of the hydrophilic layer preferably has a concavo-convex structure with a pitch of 0.1 to 50 μm like the aluminum grain of the PS plate, and this concavo-convex improves water retention and image area retention.

  Such a concavo-convex structure can be formed by containing an appropriate amount of a filler having an appropriate particle size in the hydrophilic layer, but the above-mentioned alkaline colloidal silica and the above-mentioned water-soluble substance are used in the hydrophilic layer coating solution. It is preferable that a structure having better printing performance can be obtained by containing a polysaccharide and forming a phase separation when the hydrophilic layer is applied and dried.

  The shape of the concavo-convex structure (such as pitch and surface roughness) is the type and amount of alkaline colloidal silica, the type and amount of water-soluble polysaccharides, the type and amount of other additives, the solid content concentration of the coating solution, and the wet film. The thickness and drying conditions can be appropriately controlled.

The pitch of the concavo-convex structure is more preferably 0.2 to 30 μm, and further preferably 0.5 to 20 μm. Further, a concavo-convex structure having a multiple structure in which a concavo-convex structure having a smaller pitch is formed on the concavo-convex structure having a large pitch may be formed.
As surface roughness, 100-1000 nm is preferable by Ra, and 150-600 nm is more preferable.

  Moreover, as a film thickness of a hydrophilic layer, it is 0.01-50 micrometers, Preferably it is 0.2-10 micrometers, More preferably, it is 0.5-3 micrometers.

  In addition, the hydrophilic layer coating solution for forming the hydrophilic layer of the present invention may contain a water-soluble surfactant for the purpose of improving the coating property. A surfactant such as Si-based or F-based can be used, but it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains.

  The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the entire hydrophilic layer (solid content as the coating solution).

  In addition, the hydrophilic layer of the present invention can contain a phosphate. In the present invention, since the hydrophilic layer coating solution is preferably alkaline, the phosphate is preferably added as trisodium phosphate or disodium hydrogen phosphate. By adding phosphate, the effect of improving the mesh opening at the time of printing can be obtained. The addition amount of phosphate is preferably 0.1 to 5% by mass, and more preferably 0.5 to 2% by mass as an effective amount excluding hydrate.

  A preferred embodiment in the case of providing a hydrophilic layer by hydrophilizing the surface of the substrate is a case where an aluminum substrate is used. Since the hydrophilic layer is provided on the aluminum substrate, the surface is roughened and used.

  Prior to roughening (graining treatment), it is preferable to perform a degreasing treatment in order to remove the rolling oil on the surface. As the degreasing treatment, a degreasing treatment using a solvent such as trichlene or thinner, an emulsion degreasing treatment using an emulsion such as kesilon or triethanol, or the like is used. In addition, an alkaline aqueous solution such as caustic soda can be used for the degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, dirt and oxide film that cannot be removed only by the degreasing treatment can be removed. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, smut is generated on the surface of the support. In this case, the substrate is immersed in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof and desmutted. It is preferable to perform the treatment. Examples of the roughening method include a mechanical method and a method of etching by electrolysis.

  The mechanical roughening method used is not particularly limited, but a brush polishing method and a honing polishing method are preferable.

  The electrochemical surface roughening method is not particularly limited, but a method of electrochemical surface roughening in an acidic electrolyte is preferable.

After the surface is roughened by the electrochemical surface roughening method, it is preferably immersed in an acid or alkali aqueous solution in order to remove aluminum scraps on the surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an alkaline aqueous solution. The dissolution amount of aluminum in the support surface, 0.5 to 5 g / m ² is preferred. In addition, it is preferable that after the immersion treatment with an alkaline aqueous solution, neutralization treatment is performed by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

  The mechanical surface roughening method and the electrochemical surface roughening method may each be used alone for roughing, or the mechanical surface roughening method followed by the electrochemical surface roughening method. You may roughen.

  Following the roughening treatment, an anodic oxidation treatment can be performed. There is no restriction | limiting in particular in the method of the anodizing process which can be used in this invention, A well-known method can be used. By performing the anodizing treatment, an oxide film is formed on the support.

  The anodized support may be sealed as necessary. These sealing treatments can be performed using known methods such as hot water treatment, boiling water treatment, water vapor treatment, sodium silicate treatment, dichromate aqueous solution treatment, nitrite treatment, and ammonium acetate treatment.

Furthermore, after performing these treatments, a water-soluble resin such as polyvinylphosphonic acid, a polymer or copolymer having a sulfonic acid group in the side chain, polyacrylic acid, a water-soluble metal salt (for example, zinc borate) or Also suitable are those coated with a yellow dye, amine salt or the like. Further, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A No. 5-304358 is covalently used.
[Thermal image forming layer]
The heat-sensitive image forming layer is a layer capable of forming an image by heating, and includes a heat-meltable material, a heat-fusible material, or a material (hydrophobized precursor) that changes from hydrophilic to hydrophobic by heating. The heating method includes a method using a heat source and a method using heat generated by light exposure such as a laser, but an image forming method using heat generated by light exposure such as laser is preferable.

  As one of the preferable embodiments of the image forming layer of the present invention, an embodiment in which the image forming layer contains a hydrophobizing precursor can be mentioned.

  As the hydrophobizing precursor, a polymer that changes from hydrophilicity (water-soluble or water-swellable) to hydrophobicity by heat can be used. Specific examples include polymers containing aryl diazosulfonate units disclosed in JP-A-2000-56449.

  The heat-meltable material or heat-fusible material used in the present invention is preferably used in the form of fine particles.

  The heat-meltable fine particles are fine particles formed of a material that has a low viscosity when melted, and is generally classified as a wax, among thermoplastic materials. The physical properties are preferably a softening point of 40 ° C. or higher and 120 ° C. or lower, a melting point of 60 ° C. or higher and 150 ° C. or lower, more preferably a softening point of 40 ° C. or higher and 100 ° C. or lower, and a melting point of 60 ° C. or higher and 120 ° C. or lower. When the melting point is less than 60 ° C., storage stability is a problem, and when the melting point is higher than 300 ° C., ink deposition sensitivity is lowered.

  Usable materials include paraffin, polyolefin, polyethylene wax, microcrystalline wax, fatty acid wax and the like. These have a molecular weight of about 800 to 10,000. In order to facilitate emulsification, these waxes can be oxidized to introduce polar groups such as hydroxyl groups, ester groups, carboxyl groups, aldehyde groups, and peroxide groups.

  Furthermore, in order to lower the softening point and improve the workability, these waxes are stearamide, linolenamide, laurylamide, myristamide, hardened beef fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide, coconut fatty acid amide. Alternatively, methylolated products of these fatty acid amides, methylene bisstellaramide, ethylene bisstellaramide, and the like can be added. Coumarone-indene resin, rosin-modified phenol resin, terpene-modified phenol resin, xylene resin, ketone resin, acrylic resin, ionomer, and copolymers of these resins can also be used.

  Among these, it is preferable to contain any of polyethylene, microcrystalline, fatty acid ester, and fatty acid. Since these materials have a relatively low melting point and a low melt viscosity, high-sensitivity image formation can be performed. In addition, since these materials have lubricity, damage when a shearing force is applied to the surface of the printing plate material is reduced, and resistance to printing stains due to scratches or the like is improved.

  The heat-meltable fine particles are preferably dispersible in water, and the average particle diameter is preferably 0.01 to 10 μm, more preferably 0.1 μm, from the viewpoint of on-press developability and resolution. ~ 3 μm.

  Further, the composition of the heat-meltable fine particles may vary continuously between the inside and the surface layer, or may be coated with a different material.

As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.
As content of the heat-meltable microparticles | fine-particles in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

  Examples of the heat-fusible fine particles used in the present invention include thermoplastic hydrophobic polymer fine particles, and there is no specific upper limit for the softening temperature of the polymer fine particles, but the temperature is the same as that of the polymer fine particles. It is preferable that the temperature is lower than the decomposition temperature. The weight average molecular weight (Mw) of the polymer is preferably in the range of 10,000 to 1,000,000.

  Specific examples of the polymer constituting the polymer particles include, for example, diene (co) polymers such as polypropylene, polybutadiene, polyisoprene and ethylene-butadiene copolymer, styrene-butadiene copolymer, Synthetic rubbers such as methyl methacrylate-butadiene copolymer, acrylonitrile-butadiene copolymer, polymethyl methacrylate, methyl methacrylate- (2-ethylhexyl acrylate) copolymer, methyl methacrylate-methacrylic acid copolymer, methyl acrylate- ( N-methylolacrylamide) copolymer, (meth) acrylic acid ester such as polyacrylonitrile, (meth) acrylic acid (co) polymer, polyvinyl acetate, vinyl acetate-vinyl propionate copolymer, vinyl acetate-ethylene copolymer Vinyl etc. of polymers Ester (co) polymer, vinyl acetate - (2-ethylhexyl acrylate) copolymers, polyvinyl chloride, polyvinylidene chloride, polystyrene and copolymers thereof. Of these, (meth) acrylic acid esters, (meth) acrylic acid (co) polymers, vinyl ester (co) polymers, polystyrene, and synthetic rubbers are preferably used.

  The polymer polymer fine particles may be composed of a polymer polymer polymerized by any known method such as emulsion polymerization, suspension polymerization, solution polymerization, and gas phase polymerization. As a method of microparticulating a polymer polymer polymerized by a solution polymerization method or a gas phase polymerization method, a method of spraying a solution in an organic solvent of the polymer polymer into an inert gas and drying to form particles, Examples thereof include a method in which a high molecular weight polymer is dissolved in a water-immiscible organic solvent, this solution is dispersed in water or an aqueous medium, and the organic solvent is distilled off to form fine particles. In any of the methods, a surfactant, such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyethylene glycol, or a water-soluble resin, such as polyvinyl alcohol, is used as a dispersant or stabilizer in polymerization or micronization as necessary. May be used.

  The heat-fusible fine particles are preferably dispersible in water, and the average particle size is preferably 0.01 to 10 μm, more preferably 0.1 to 10 m from the standpoint of on-press developability and resolution. ~ 3 μm.

  Further, the composition of the heat fusible particles may be continuously changed between the inside and the surface layer, or may be coated with a different material.

As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.
As content of the thermoplastic fine particle in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

  Examples of the microcapsules include microcapsules enclosing a hydrophobic material described in JP-A No. 2002-2135 and JP-A No. 2002-19317.

  The microcapsules preferably have an average diameter of 0.1 to 10 μm, more preferably 0.3 to 5 μm, and even more preferably 0.5 to 3 μm.

  The thickness of the wall of the microcapsule is preferably 1/100 to 1/5 of the diameter, and more preferably 1/50 to 1/10.

The content of the microcapsule is 5 to 100% by mass of the entire image forming layer, preferably 20 to 95% by mass, and more preferably 40 to 90% by mass.
Known materials and methods can be used as the material for the wall of the microcapsule and the method for producing the microcapsule. For example, known materials and methods described in “New Microcapsules, Production Methods, Properties, and Applications” (Takeshi Kondo, Masumi Koishi / Sankyo Publishing Co., Ltd.) or cited references are used. be able to.
[Other materials that can be contained in the image forming layer]
The image forming layer used in the present invention may further contain the following materials.

  The above-mentioned photothermal conversion material can be contained in the image forming layer. The image forming layer is preferably made of a material that is less colored with visible light.

  The image forming layer can contain a water-soluble resin or a water-dispersible resin. Examples of water-soluble resins and water-dispersible resins include oligosaccharides, polysaccharides, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymers, and methyl methacrylate-butadiene copolymers. Examples thereof include resins such as conjugated diene polymer latex, acrylic polymer latex, vinyl polymer latex, polyacrylic acid, polyacrylate, polyacrylamide, and polyvinylpyrrolidone.

Of these, oligosaccharides, polysaccharides, polyacrylic acid, polyacrylates (such as Na salts), and polyacrylamide are preferable.
Examples of the oligosaccharide include raffinose, trehalose, maltose, galactose, sucrose, and lactose, and trehalose is particularly preferable.
As polysaccharides, starches, celluloses, polyuronic acids, pullulans and the like can be used, but cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, hydroxyethyl cellulose salts are particularly preferable, and sodium salts and ammonium salts of carboxymethyl cellulose are preferable. More preferred.

  The polyacrylic acid, polyacrylic acid, polyacrylate (Na salt, etc.), and polyacrylamide preferably have a molecular weight of 3,000 to 5,000,000, and more preferably 5,000 to 1,000,000.

  The image forming layer can contain a water-soluble surfactant. A surfactant such as Si-based or F-based can be used, but it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains. The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the entire hydrophilic layer (solid content as the coating solution).

Further, it may contain an acid (phosphoric acid, acetic acid, etc.) or an alkali (sodium hydroxide, silicate, phosphate, etc.) for pH adjustment.
The amount per image forming layer, a 0.01 to 10 g / m ^2, preferably from 0.1 to 3 g / m ^2, more preferably from 0.2 to 2 g / m ^2.
[Protective layer]
A protective layer can also be provided on the image forming layer.

  As a material used for the protective layer, the above-mentioned water-soluble resin and water-dispersible resin can be preferably used.

  Further, hydrophilic overcoat layers described in JP-A Nos. 2002-19318 and 2002-86948 can also be preferably used.

The amount per the protective layer is 0.01 to 10 g / m ^2, preferably from 0.1 to 3 g / m ^2, more preferably from 0.2 to 2 g / m ^2.
[On-press development method]
A so-called on-press development method in which the non-image area is removed using dampening water and / or ink on a printing press, which is a preferred embodiment for developing the printing plate material of the present invention, is shown below.

The removal of the non-image part (unexposed part) of the image forming layer on the printing press can be performed by contacting a watering roller or an ink roller while rotating the plate cylinder. Alternatively, it can be performed by various other sequences. In that case, the water amount may be adjusted by increasing or decreasing the amount of dampening water required for printing, and the water amount adjustment may be divided into multiple stages or steplessly. You may change it to.
(1) As a sequence for starting printing, a watering roller is brought into contact with the plate cylinder to make one to several dozen rotations, then an ink roller is brought into contact with the plate cylinder to make one to several dozen rotations, and then Start printing.
(2) As a sequence for starting printing, an ink roller is contacted to rotate the plate cylinder from 1 to several tens of turns, then a watering roller is contacted to rotate the plate cylinder from 1 to tens of rotations, Start printing.
(3) As a sequence for starting printing, the watering roller and the ink roller are brought into contact with each other substantially simultaneously to rotate the plate cylinder 1 to several tens of times, and then printing is started.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” represents “parts by mass” unless otherwise specified.

Preparation of base material 1 An aluminum plate (material 1050, tempered H16) having a thickness of 0.24 mm is immersed in a 1 mass% sodium hydroxide aqueous solution at 50 ° C. and dissolved so that the dissolution amount becomes 2 g / m ^2. After performing the treatment and washing with water, it was immersed in a 0.1 mass% hydrochloric acid aqueous solution at 25 ° C. for 30 seconds, neutralized, and then washed with water.

Next, this aluminum plate was subjected to an electrolytic surface roughening treatment with an electrolytic solution containing hydrochloric acid 10 g / L and aluminum 0.5 g / L using a sine wave alternating current and a peak current density of 50 A / dm ^2. It was. The distance between the electrode and the sample surface at this time was 10 mm. Perform electrolytic graining treatment is divided into 12 times, and the quantity of electricity used in one treatment (at a positive polarity) as the 40C / dm ^2, treatment quantity of electricity 480C / dm ² in total (at a positive polarity). In addition, a rest period of 5 seconds was provided between each surface roughening treatment.

After electrolytic surface roughening, it is immersed in a 1% by weight sodium hydroxide aqueous solution kept at 50 ° C. and etched so that the amount of dissolution including the smut of the roughened surface becomes 1.2 g / m ^2. Then, it was washed with water, then immersed in a 10% aqueous sulfuric acid solution maintained at 25 ° C. for 10 seconds, neutralized, and then washed with water. Next, anodization was performed in a 20% sulfuric acid aqueous solution so that the amount of electricity was 150 C / dm ² under a constant voltage condition of 20 V, followed by washing with water.

  Next, after squeezing the surface water after washing with water, it was immersed in a 1% by mass aqueous solution of sodium dihydrogen phosphate kept at 70 ° C. for 30 seconds, washed with water, dried at 80 ° C. for 5 minutes, and hydrophilic on the surface. The base material 1 which has a property layer was obtained. Ra (center line roughness) of the substrate 1 was 460 nm (measured at 40 times using RST Plus manufactured by WYKO).

Production of Substrate 2 Both sides of a biaxially stretched polyester film film having a thickness of 175 μm were subjected to a corona discharge treatment of 8 W / m ² · min. The undercoat coating liquid b was applied to a dry film thickness of 0.1 μm while applying corona discharge treatment (8 W / m ² · min) after coating to 8 μm, and dried at 180 ° C. for 4 minutes, respectively. (Underdrawing surface A). Also, after coating the following undercoat coating solution c on the opposite side so as to have a dry film thickness of 0.8 μm, the undercoat coating solution d is dried film thickness 1 while performing corona discharge treatment (8 W / m ² · min). The coating was applied to a thickness of 0.0 μm and dried at 180 ° C. for 4 minutes (undercoating surface B). The surface electrical resistance at 108 ° C. and 25% relative humidity after coating was 108Ω. Thus, the base material 2 which formed the undercoat layer on both surfaces was obtained.

<< Undercoat coating liquid a >>
Styrene / glycidyl methacrylate / butyl acrylate = 60/39/1 (molar ratio) terpolymer copolymer latex (Tg = 75 ° C.) 6.3 parts Styrene / glycidyl methacrylate / butyl acrylate = 20/40/40 (molar ratio) ) Ternary copolymer latex 1.6 parts anionic surfactant S-1 0.1 part water 92.0 parts << undercoat coating solution b >>;
Gelatin 1 part Anionic surfactant S-1 0.05 part Hardener H-1 0.02 part Matting agent (silica, average particle size 3.5 μm) 0.02 part Antifungal agent F-1 0.01 Water 98.9 parts

<< Undercoat coating liquid c >>
Styrene / glycidyl methacrylate / butyl acrylate = 20/40/40 (molar ratio) terpolymer copolymer latex 0.4 part Styrene / glycidyl methacrylate / butyl acrylate / acetoacetoxyethyl methacrylate = 39/40/20/1 (mole) Ratio) quaternary copolymer latex
7.6 parts anionic surfactant S-1 0.1 part water 91.9 parts << undercoat coating solution d >>;
Conductive composition of component d-1 / component d-2 / component d-3 = 66/31/1 (mass ratio)
6.4 parts Hardener H-2 0.7 parts Anionic surfactant S-1 0.07 parts Matting agent (silica, average particle size 3.5 μm) 0.03 parts Water 92.8 parts Component d- 1;
An anionic polymer compound comprising a copolymer of sodium styrenesulfonate / maleic acid = 50/50 (molar ratio); component d-2;
Three-component copolymer latex composed of styrene / glycidyl methacrylate / butyl acrylate = 40/40/20 (molar ratio) component d-3;
Polymeric activator comprising styrene / sodium isoprenesulfonate = 80/20 (molar ratio)

Example 1
(Preparation of aqueous dispersion of solid resin fine particles containing dye precursor)
<< Solid resin fine particles A containing a dye precursor >>
As the electron-donating dye precursor, 2- (4-methylanilino) -3-methyl-6-ethylaminofluorane, which develops a black color, was used.

  25 g of the above electron-donating dye precursor was dissolved in 70 g of methylene chloride, and 45 g of isocyanate (Takenate D-170HN, manufactured by Mitsui Takeda Chemical Co., Ltd.) was added to and mixed with this solution to prepare an oil phase solution. Next, an oil phase solution was added little by little with stirring to 300 g of an aqueous 10% by weight polyvinyl alcohol (PVA-117, manufactured by Kuraray Co., Ltd.), and after adding the entire amount, the mixed solution was emulsified and dispersed at 10,000 rpm using a homogenizer. . Next, 130 g of pure water was added and the mixture was stirred and homogenized to adjust the solid content of the dispersion. The above steps were performed while adjusting the temperature so that the liquid temperature was in the range of 15 to 20 ° C.

  Next, a methylene chloride volatilization removal step was performed while stirring the obtained dispersion. The volatilization removal conditions were 40 ° C. and 6 hours.

  Next, the polymerization process was performed while stirring the dispersion. The polymerization conditions were set to 85 ° C. and 3 hours after heating from 40 ° C. to 85 ° C. over 30 minutes. After completion of the polymerization step, the dispersion was returned to room temperature to obtain a 20% by mass solid dispersion of solid resin fine particles A containing a dye precursor.

  The solid resin fine particles A containing the dye precursor were confirmed by SEM observation to be fine particles in which the surface layer having an average particle diameter of 0.5 μm was coated with the resin. Moreover, the conspicuous hole was not formed in the particle | grain surface.

<< Solid resin fine particles B containing dye precursor >>
Except for the volatilization removal step at 40 ° C. for 1 hour, an aqueous dispersion having a solid content of 20% by mass of the solid resin fine particles B containing the dye precursor is the same as the solid resin fine particles A containing the dye precursor. Obtained.

  The solid resin fine particles B containing the dye precursor were confirmed by SEM observation to be fine particles in which the surface layer having an average particle size of 0.7 μm was coated with the resin. In addition, a large number of holes were formed on the particle surface.

<< Preparation of aqueous dispersion of dye precursor fine particles >>
An electron-donating dye precursor 2- (4-methylanilino) -3-methyl-6-ethylaminofluorane: 18 g, carboxymethylcellulose: 50 g of a 4% by weight aqueous solution of CMC1220 (manufactured by Daicel Chemical Industries), and 32 g of pure water were mixed. And dispersed for 5 hours with a sand grinder. Zirconia beads were used for dispersion, and the number of rotations during dispersion was 2000 rpm.

  Subsequently, 100 g of pure water was added and mixed and diluted at 500 rpm for 10 minutes, and the beads were removed to obtain a 10% by mass dye precursor particle aqueous dispersion. The average particle diameter of the dye precursor particles was 0.8 μm.

<< Preparation of aqueous dispersion of electron-accepting developer fine particles >>
The dye precursor is changed to the developer: D-8 (4-hydroxy-4'-isopropoxydiphenylsulfone, manufactured by Nippon Soda Co., Ltd.), and the dispersion time is set to 2 hours. Thus, a developer particle aqueous dispersion was obtained. The average particle diameter of the developer particles was 1.5 μm.

(Preparation of printing plate material)
[Printing plate material 1]
A material having the following composition was sufficiently mixed and stirred and filtered to prepare a coating solution for the image forming layer (a) having a solid content of 10% by mass. On the base material 1, the coating liquid of the image forming layer (a) was applied using a wire bar so that the drying amount was 1.5 g / m ² and dried at 55 ° C. for 3 minutes. Subsequently, an aging treatment at 40 ° C. for 24 hours was performed to obtain a printing plate material 1.

[Printing plate material 2]
A material having the following composition was sufficiently mixed and stirred and filtered to prepare a coating solution for the image forming layer (b) having a solid content of 10% by mass. A printing plate material 2 was obtained in the same manner as in the printing plate 1 except that the coating solution for the image forming layer (a) was used as the coating solution for the image forming layer (b).

[Printing plate material 3 (comparison)]
A material having the following composition was sufficiently mixed and stirred and filtered to prepare a coating solution for the image forming layer (c) having a solid content of 10% by mass. A printing plate material 3 was obtained in the same manner as in the printing plate 1 except that the coating solution for the image forming layer (a) was used as the coating solution for the image forming layer (c).

[Printing plate material 4]
On the base material 1, the coating liquid of the image forming layer (a) was applied using a wire bar so that the drying amount was 1.5 g / m ² and dried at 55 ° C. for 3 minutes. Next, after thoroughly stirring and mixing the materials having the following composition, the mixture was filtered to prepare a coating solution for the protective layer (d) having a solid content of 2% by mass. This was applied onto the image forming layer (a) using a wire bar so that the dry weight was 0.2 g / m ² and dried at 55 ° C. for 3 minutes. Subsequently, an aging treatment at 40 ° C. for 24 hours was performed to obtain a printing plate material 4.

[Printing plate material 5]
A material having the following composition was sufficiently stirred and mixed, and then filtered to prepare a coating solution for an image forming layer (e) having a solid content of 10% by mass. On the base material 1, the coating liquid of the image forming layer (e) was applied using a wire bar so that the dry weight was 1.2 g / m ² and dried at 55 ° C. for 3 minutes. Next, after thoroughly stirring and mixing the materials having the following composition, the mixture was filtered to prepare a coating solution for the protective layer (f) having a solid content of 5% by mass. This was applied onto the image forming layer (e) using a wire bar so that the dry weight was 0.3 g / m ² and dried at 55 ° C. for 3 minutes. Subsequently, an aging treatment at 40 ° C. for 24 hours was performed to obtain a printing plate material 5.

[Printing plate material 6 (comparison)]
A material having the following composition was sufficiently stirred and mixed, followed by filtration to prepare a coating solution for an image forming layer (g) having a solid content of 10% by mass. On the base material 1, the coating liquid of the image forming layer (g) was applied using a wire bar so that the drying amount was 1.2 g / m ² and dried at 55 ° C. for 3 minutes. Next, the coating solution for the protective layer (f) was applied onto the image forming layer (g) using a wire bar so that the dry weight was 0.3 g / m ² and dried at 55 ° C. for 3 minutes. . Subsequently, an aging treatment at 40 ° C. for 24 hours was performed to obtain a printing plate material 6.

[Printing plate material 7]
A material having the following composition was sufficiently stirred and mixed using a homogenizer, followed by filtration to prepare a coating solution for a hydrophilic layer (h) having a solid content of 15% by mass. A coating solution for the hydrophilic layer (h) is applied onto the undercoating surface A of the substrate 2 using a wire bar so that the applied amount after drying is 2.0 g / m ^2, and at 100 ° C. for 3 minutes. Dried. Next, an aging treatment at 60 ° C. for 24 hours was performed.

  Next, the image forming layer (a) was applied onto the hydrophilic layer in the same manner as the printing plate material 1 and subjected to the same aging treatment to obtain a printing plate material 7.

[Printing plate material 8 (comparison)]
A material having the following composition was sufficiently stirred and mixed, and then filtered to prepare a coating solution for the image forming layer (i) having a solid content of 10% by mass. A printing plate material 8 was obtained in the same manner as the printing plate material 7 except that the image forming layer (a) was the image forming layer (i) and the amount applied after drying was 0.7 g / m ² .

(Image formation by infrared laser exposure)
The produced printing plate material was wound around an exposure drum and fixed. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm was used for exposure, and the exposure energy was 250 mJ / cm ² , and an image was formed with 2400 dpi (dpi represents the number of dots per 2.54 cm) and 175 lines. The exposed image includes a solid image and a 1 to 99% halftone dot image.

(Exposure visibility evaluation)
The reflection density between the non-image area (unexposed area) and the solid image area (solid exposure area) of the exposed printing plate material is measured in the K mode using Macbeth RD918, and Δd (density of the solid exposure area−unexposed) The density of the exposed area was determined, and the results are shown in Table 1. In the case of the printing plate material using the substrate 2, the measurement was performed by placing three coated paper sheets for printing under the printing plate material. In addition, the symbol in a table | surface has shown the following evaluation result.

◎: Δd is 0.8 or more ○: Δd is 0.4 or more and less than 0.8 Δ: 0.2 or more and less than 0.4 ×: Less than 0.2 (Printing method)
Printing machine: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., coated paper, dampening water: 2% by mass of Astro Mark 3 (manufactured by Nikken Chemical Laboratory), ink (TK High Unity Red, manufactured by Toyo Ink Co., Ltd.) Used to print. The printing plate material was attached to the plate cylinder as it was after exposure, and printed using the same printing sequence as the PS plate.

(Print evaluation)
[Earth dirt evaluation]
The 1000th printed material was sampled from the print, and the degree of background smudge in the non-image area was evaluated. The results are shown in Table 1. In addition, the symbol in a table | surface has shown the following evaluation result.

○: No soiling △: Slightly soiling ×: Grounding [Evaluation of printing durability]
The number of printed sheets at the time when the 3% halftone image started to be missing was used as an index of printing durability.

[On-press developability]
For each printing plate material, the number of sheets printed from the start of printing was determined for completion of on-press development. The on-machine development end index is that the non-image area is not smudged on the printed material, the density of the solid image area is 1.6 or more (measured in the M mode using Macbeth RD918), and 95 % Halftone image is open. The results are shown in Table 1.

[Preservation]
Each printing plate material was evaluated for color development after storage for 7 days in an environment of 55 ° C. and 20% humidity, and the results are shown in Table 1. In addition, the symbol in a table | surface has shown the following evaluation result.
○: No color development Δ: Slight color development ×: Color development As shown in Table 1, when the printing plate material of the present invention is used, there is no background stain, excellent printing durability, and good exposure visibility. You can see that Further, it can be seen that the on-press developability and storage stability are also excellent.

Example 2
Results Using the printing plate materials shown in Table 2, the following exposure apparatus contamination evaluation was performed. The results are shown in Table 2.

Infrared laser exposure conditions, exposure method:
A printing plate material was wound around and fixed to an exposure drum, and a transparent PET film having a thickness of 25 μm was adhered and fixed thereon to form a cover sheet. Wavelength 830nm The exposure, using a laser beam spot diameter 18 [mu] m, while changing the exposure energy from 150 mJ / cm ² at 50mJ increments until 450mJ / cm ^2, 2400dpi (dpi represents the number of dots per 2.54 cm), An image was formed at 175 lines. The exposed image includes a solid image.
(Exposure device contamination assessment)
The degree of coloring of the dirt attached to the portion corresponding to the solid exposure portion of the cover sheet after exposure was evaluated for each exposure energy, and the results are shown in Table 2. In addition, the symbol in a table | surface has shown the following evaluation result.

○: Not colored Δ: Slightly colored ×: Colored (exposure visible image property evaluation)
The visible image quality of the solid exposure portion of the printing plate material was measured in the same manner as in Example 1 for each exposure energy, and the results are shown in Table 2.

  From the result table 2, it can be seen that the printing plate material of the present invention has no concern about exposure apparatus contamination in the exposure energy region where good exposure visibility is obtained.

Example 3
(Preparation of printing plate material)
[Printing plate material 9]
A material having the following composition was sufficiently stirred and mixed using a homogenizer, followed by filtration to prepare a coating solution for a hydrophilic layer (j) having a solid content of 15% by mass. The coating liquid for the hydrophilic layer (j) is applied onto the undercoating surface A of the base material 2 using a wire bar so that the applied amount after drying is 2.0 g / m ^2, and at 80 ° C. for 3 minutes. Dried. Next, an aging treatment at 60 ° C. for 24 hours was performed.

Next, the material having the following composition of the image forming layer was sufficiently stirred and mixed, followed by filtration to obtain a coating solution for the image forming layer (k) having a solid content of 10% by mass. Next, the coating solution for the image forming layer (k) was applied on the hydrophilic layer using a wire bar so that the applied amount after drying was 1.0 g / m ² and dried at 55 ° C. for 3 minutes. . Next, an aging treatment at 40 ° C. for 24 hours was performed to obtain a printing plate material 9.

[Printing plate material 10]
In the same manner as in the above, except that the solid resin fine particle aqueous dispersion containing the dye precursor of the coating liquid of the hydrophilic layer (j) is changed to the solid resin fine particle B aqueous dispersion containing the dye precursor. A coating solution for layer (l) was prepared. A printing plate material 10 was obtained in the same manner except that the coating solution for the hydrophilic layer (j) was changed to the coating solution for the hydrophilic layer (l).

[Printing plate material 11 (comparison)]
A material having the following composition was sufficiently stirred and mixed using a homogenizer, followed by filtration to prepare a coating solution for a hydrophilic layer (m) having a solid content of 15% by mass. A printing plate material 11 was obtained in the same manner except that the coating solution for the hydrophilic layer (j) was changed to the coating solution for the hydrophilic layer (m).

Image formation by infrared laser exposure:
Exposure was performed in the same manner as in Example 1. All the printing plate materials had good exposure and visibility.
(Printing method)
Printing was performed in the same manner as in Example 1.

(Print evaluation)
[Earth dirt evaluation]
The printed material was sampled from the 100th sheet to the 2500th sheet after printing, and every 2000th sheet to the 20000th sheet to evaluate the degree of background smudge in the non-image area, and the results are shown in Table 3. In addition, the symbol in a table | surface has shown the following evaluation result.

○: No soiling △: Slightly soiling ×: Grounding [Evaluation of printing durability]
The number of prints at the time when the 3% halftone image started to be missing was used as an index of printing durability, and the results are shown in Table 3.

  As can be seen from the result table 3, the printing plate material of the present invention has good printing durability and good exposure visible image quality without causing soiling.

Claims (11)

In a printing plate material having a constituent layer including a hydrophilic layer and a heat-sensitive image forming layer on a substrate, one of the constituent layers includes solid resin fine particles containing a dye precursor, and one of the constituent layers. A printing plate material characterized in that one contains a developer. The printing plate material according to claim 1, wherein the dye precursor is coated with a solid resin. 3. The printing plate material according to claim 1, wherein an average particle diameter of the solid resin fine particles of the constituent layer containing the solid resin fine particles is 0.1 μm or more and 1 μm or less. 4. The printing plate material according to claim 1, wherein one of the constituent layers contains a photothermal conversion material. 5. The hydrophilic layer or a constituent layer on the surface side adjacent to the hydrophilic layer contains the solid resin fine particles, and the thermal image forming layer is a layer that can be developed on-press. Printing plate material. 6. The printing plate material according to claim 1, wherein the hydrophilic layer contains the solid resin fine particles and a hydrophilic material that is substantially insoluble in water. The printing plate material according to claim 1, wherein the constituent layer containing the solid resin fine particles and the constituent layer containing the developer are different layers. The printing plate material according to claim 7, wherein the constituent layer containing the solid resin fine particles and the constituent layer containing the developer are adjacent to each other. 9. The printing plate material according to claim 1, further comprising a constituent layer not containing the solid resin fine particles on a surface layer side of the constituent layer containing the solid resin fine particles. 9. The printing plate material according to claim 7, wherein the constituent layer containing the developer is on the surface layer side of the constituent layer containing the solid resin fine particles. The printing plate material according to claim 1, wherein the developer is contained in the form of particles.