WO2007094187A1

WO2007094187A1 - Printing plate material and method for image formation

Info

Publication number: WO2007094187A1
Application number: PCT/JP2007/051924
Authority: WO
Inventors: Takahiro Mori
Original assignee: Konica Minolta Medical & Graphic, Inc.
Priority date: 2006-02-17
Filing date: 2007-02-05
Publication date: 2007-08-23

Abstract

This invention provides a printing plate material, which has exposure visualizing properties high enough to provide excellent visibility and, at the same time, has excellent printing durability and press developing properties, and a method for image formation. The printing plate material has a press developable image forming layer provided on a support and is characterized in that the image forming layer contains the following components (A) to (D) and has been formed using a coating liquid (pH 6.5 to 12) for an image forming layer. (A) A microcapsule encapsulating thermoplastic lipophilic resin particles or a lipophilic material (B) An infrared absorbing cyanine coloring matter (C) A water soluble resin having a mass average molecular weight of not less than 200000 (D) A water soluble basic compound

Description

Specification

Printing plate material and image forming method

Technical field

[0001] The present invention relates to a printing plate material and an image forming method, and more particularly to a printing plate material used in a computer 'to' plate (hereinafter referred to as CTP) system.

Background art

[0002] Currently, in the field of printing, with the digital input of print image data, the power that is being printed by the CTP method is cheap and easy to handle. Therefore, there is a need for a printing plate material for the CTP system that has the same printability as the conventional so-called PS plate.

[0003] In particular, in recent years, it has direct imaging (hereinafter referred to as DI) performance that does not require development processing with a special drug, and can be applied to a printing press equipped with this function, and has the same usability as the PS version. What is needed is a general-purpose processless plate.

[0004] On the other hand, in general, the image layer of a PS plate or a 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, It has a good development visible image property with a high contrast with the grain of aluminum support. In other words, plate inspection after development (visually or using a dedicated device) is possible.

[0005] In the CTP method, it is expected that the work of plate inspection will not be performed in the future! However, it is necessary for the current workflow.

[0006] In addition, when punching (mounting holes for mounting) necessary for mounting on a printing press is performed after development, the registration mark image is read with a dedicated device, and accurate position adjustment is performed, so that it can be read with the device. The contrast between the image portion and the non-image portion is required.

[0007] Therefore, in a thermal processless plate that does not require development, one of the important performances is visible image quality after image recording, V, and so-called exposure visible image quality.

[0008] As a processless plate for DI, for example, ThermoLite (registered trademark) manufactured by Agfa Inc. is mentioned, but the plate inspection property after exposure is not particularly taken into consideration, so that exposure visibility is high. Has very little.

[0009] 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 broadly divided into an ablation type, a thermal fusion image layer development type, and a phase change type, which will be described later.

[0010] Examples of the abrasion type are described in JP-A-8-507727, JP-A-6-186750, JP-A-6-199064, JP-A-7-314934, JP-A-10-58636, JP-A-10-244773. Being! /, There are things.

[0011] These are, for example, obtained by laminating a hydrophilic layer and a lipophilic layer 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, removing the hydrophilic layer and removing it like an image to expose the lipophilic layer. However, contamination of the inside of the exposure apparatus due to the ablated surface scattered matter becomes a problem. Therefore, a water-soluble protective layer is further provided on the hydrophilic layer to prevent the ablated surface layer from scattering, and the protective layer on the printing press. A method for removing the ablated surface layer has also been proposed.

[0012] In the case of the abrasion type, the force that can provide exposure visibility by making the hues of the surface layer and the layer below the surface different from each other. For this purpose, the surface layer is completely abraded. Need to be removed. This can be achieved, for example, by installing a cleaner that sucks and removes the scattered particles in the exposure apparatus, but there is a problem that the cost of the apparatus increases significantly.

[0013] In the type provided with the protective layer as described above, the scattered scattered matter remains. Therefore, even if the hues of the surface layer and the layer below it are different, good exposure visibility is good. I can't get it.

[0014] As a means for solving the above problem, a method is disclosed in which a hydrophilic overcoat layer removable on a printing press contains 20% by mass or more of a cyanine-based infrared absorbing dye capable of changing an optical density by exposure. Being! Speak (see Patent Document 1).

[0015] According to this method, a force that can surely provide a good exposure visible image property is contained. A large amount of a dye is contained in a layer to be removed on a printing press, and the dye is faded or faded by exposure. Of course, either the exposed or unexposed area is a layer with a high color density. Printer contamination due to top development is inevitable.

[0016] On the other hand, as a method for imparting exposure visibility, a method using a heat-sensitive element composed of a colorless basic dye (dye precursor) and a developer is known (see Patent Document 1). When such a dye precursor and developer are dispersed and mixed, there is a concern that pressure-sensitive color development may occur in addition to heat-sensitive color development, which requires care in handling and insufficient storage stability. It was a thing.

[0017] Further, as a method for imparting exposure visible image quality to a printing plate material having a thermal image forming layer, a printing plate material having a layer containing a microcapsule containing a dye precursor and a developer. Is known (see Patent Document 2), but there are cases where background smudging may occur at the time of printing, the printing durability is insufficient, t, and there are other problems!

[0018] Furthermore, a printing plate material (see Patent Document 3) having an image forming layer containing a dye precursor coated with a solid resin is known, but requires a relatively large amount of the dye precursor, There have been problems such as insufficient coloring efficiency.

[0019] In addition, in the method of adding a visible image imparting material for the purpose of only the exposure color development function to the image forming layer as described above, a decrease in printing durability due to a decrease in image intensity in an exposed area, and a sensitivity increase. There was a basic problem that a decrease, deterioration of on-press development property, or deterioration of scratch resistance was unavoidable.

[0020] As a method different from the above, there is known a method of changing the color of a specific IR (infrared absorption) single dye by exposure in an unprocessed (not on-press development type) printing plate material. (See Patent Document 4).

[0021] An image-forming layer colored in dark blue with IR-dye is laser-exposed to fade the exposed area, and a white image is formed on a dark blue background to obtain a visible image. It is disclosed that it can be obtained.

However, the density of such an image portion is low, and the negative image is often insufficient for visibility. When this method is applied to an on-press development type printing plate, it is necessary to increase the density of the background, that is, the unexposed area, in order to improve the visible image quality. There was a problem of contamination of the printing press!

Patent Document 1: Japanese Patent Publication No. 2-56231 Patent Document 2: Japanese Patent Laid-Open No. 2000-225780

Patent Document 3: Japanese Patent Laid-Open No. 2005-88403

Patent Document 4: Japanese Patent Laid-Open No. 11-240270

Disclosure of the invention

Problems to be solved by the invention

[0023] An object of the present invention is to provide a printing plate material and an image forming method having exposure visibility with excellent visibility, excellent printing durability, on-press development property, and excellent scratch resistance. is there. Means for solving the problem

The above object of the present invention is achieved by the following configurations.

1. In a printing plate material having an on-press developable image forming layer on a support, the image forming layer contains the following (A) to (D), and the image forming layer has a pH of 6.5 to A printing plate material characterized by being formed using 12 image forming layer coating solutions.

(A) Microcapsules enclosing thermoplastic lipophilic rosin particles or lipophilic materials

(B) Infrared absorbing cyanine dye

(C) A water-soluble resin having a mass average molecular weight of 200,000 or more

(D) Water-soluble basic compound

2. The printing plate material according to 1, wherein the content of the (B) infrared absorbing cyanine dye is 10% by mass to 20% by mass with respect to the image forming layer.

3. An image forming method for image-exposing a printing plate material having an on-press developable image forming layer on a support, the image forming layer containing the following (A) and (B), and The image forming layer is formed using a coating liquid for an image forming layer having a pH of 6.5 to 12, and a color difference between an exposed portion and an unexposed portion by the image exposure (Δ Δ in the LW measurement color space) Is a difference between the a * value of the exposed area and the a * value of the unexposed area (A a *), the b * value of the exposed area, and the b * value of the unexposed area. (Δb *) and the ratio (Δb * ZΔa *) to the image forming method is 0.3 or more.

(B) Infrared absorbing cyanine dye The invention's effect

[0025] With the above-described configuration of the present invention, a printing plate having excellent visibility and exposure visibility, excellent printing durability, on-press development property, and excellent scratch resistance without causing scratch marks. Materials and imaging methods can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] Hereinafter, the present invention will be described in detail.

[0027] The present invention relates to a printing plate material having an image-forming layer that can be developed on-press on a support, wherein the image-forming layer includes (A) a thermoplastic lipophilic resin particle or a lipophilic material. Capsule, (B) infrared-absorbing cyanine dye, (C) a water-soluble resin having a mass average molecular weight of 200,000 or more, and (D) a water-soluble basic compound), and the image-forming layer has a pH of 6.5 to It is characterized by being formed using 12 image forming layer coating solutions.

In the present invention, in particular, the image forming layer is a layer formed using an image forming layer coating solution containing the above (A) to (D) and having a pH of 6.5 to 12. Therefore, it is possible to provide a printing plate material having excellent visibility and exposure visibility, and excellent printing durability, on-press development property, and scratch resistance.

[0029] (Image forming layer capable of on-machine development)

The on-press developable image forming layer according to the present invention refers to a dampening solution or a dampening solution and a printing ink at the time of being subjected to a printing process after image exposure, particularly without undergoing a development process. Thus, the image forming layer that can form a printable image by removing a portion of the image forming layer that becomes a non-image portion at the time of printing.

The image forming layer according to the present invention is a layer capable of forming an image by image exposure, and is a heat-sensitive image forming layer capable of forming an image by heat generation of a layer containing a photothermal conversion agent that converts image exposure light into heat. .

[0031] The layer containing the photothermal conversion agent is preferably the image forming layer according to the present invention, but may be a separate layer adjacent to the image forming layer such as a hydrophilic layer or a protective layer.

[0032] Generally, when an infrared absorbing cyanine dye is contained in such a heat-sensitive image forming layer in an amount of about 0.1 to 20% by mass, the image forming layer is colored green. When this image-forming layer is exposed with an infrared laser, the exposed area fades as described above and the density decreases. It is known that the visible image obtained thereby has low visibility.

[0033] However, in the present invention, the pH of the image forming layer containing the above (A) to (D) is adjusted to 6.5 to 12 in the image forming layer coating solution. As a result, it has been found that the exposed portion is substantially orange-colored without a decrease in density, and that good visibility can be obtained, leading to the present invention.

[0034] The pH of the coating solution for the image forming layer needs to be adjusted in the range of 6.5 to 12 in terms of visibility, dispersion stability, resolution, press life, and printability.

[0035] The drying amount of the image forming layer is 0.1 from the viewpoints of visible image quality, printing durability, and on-press development property.

To 3. Og / m ² force S women preferred, 0. 2 to 1. 5 g / m ² force Ri women preferred, from 0.3 to 0. Preferred 8 g / m ² force S further.

[0036] (A) Thermoplastic lipophilic rosin particles or microcapsules encapsulating a lipophilic material Examples of the thermoplastic oleophilic resin particles according to the present invention include heat-meltable particles and heat-fusible particles. it can.

[0037] The heat-meltable particles are particles formed of a material generally classified as a wax having a low viscosity when melted, among thermoplastic materials. Regarding the physical properties, it is preferable that the softening point is 40 ° C or higher and 120 ° C or lower, the melting point is 60 ° C or higher and 150 ° C or lower, and the soft melting point is 40 ° C or higher and 100 ° C or lower, and the melting point is 60 ° C or higher. More preferably, it is 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, the ink deposition sensitivity decreases.

[0038] Usable materials include paraffin, polyolefin, polyethylene wax, microcrystalline wax, fatty acid wax and the like. These have a molecular weight of about 800 to 1000. In order to facilitate emulsification, these waxes can be acidified to introduce polar groups such as hydroxyl groups, ester groups, carboxyl groups, aldehyde groups, and peroxide groups. Furthermore, in order to lower the softness point and improve the workability, these tastes were mixed with stearoamide, linolenamide, laurylamide, myristamide, hardened bovine fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide. It is also possible to add coconut fatty acid amides or methylolated products of these fatty acid amides, methylene bissteraroamide, ethylene bissteraroamide, and the like. Coumarone-indene rosin, rosin-modified phenol It is also possible to use a resin resin, a terpene-modified phenol resin, a xylene resin, a ketone resin, an acrylic resin, an ionomer, and a copolymer of these resins.

[0039] Among these, it is preferable to contain any one 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.

[0040] 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 and the like is improved.

[0041] The heat-meltable particles are preferably dispersible in water, and the average particle diameter is preferably 0.01 to 10 µm, more preferably 0.1 to 3 µm. It is.

[0042] In addition, the composition of the heat-meltable particles may vary continuously between the inside and the surface layer, or may be coated with a different material.

[0043] As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.

[0044] The content of the heat-meltable particles in the layer is preferably 1 to 90% by mass, more preferably 5 to 80% by mass, based on the entire layer.

[0045] Examples of the heat-fusible particles include thermoplastic hydrophobic polymer particles, and there is no specific upper limit to the softening temperature of the polymer particles. It is preferable that the temperature is lower than the decomposition temperature. The weight average molecular weight (Mw) of the high molecular weight polymer is preferably in the range of 10,000 to 1,000,000! /.

[0046] Specific examples of the polymer constituting the polymer particles include, for example, gen (co) polymers such as polypropylene, polybutadiene, polyisoprene and ethylene butadiene copolymer, styrene butadiene copolymer. Synthetic rubbers such as polymers, methyl methacrylate-butadiene copolymers, acrylonitrile-butadiene copolymers, polymethyl methacrylate, methyl methacrylate (2-ethylhexyl acrylate) copolymers, methyl methacrylate Acid copolymers, methyl acrylate (N-methylol acrylamide) copolymers, (meth) acrylic acid esters such as polyacrylonitrile, (meth) acrylic acid (co) polymers, poly (acetic acid) butyl, bi-loopropion acetate Bures such as acid bur copolymer and vinyl acetate butylene copolymer Ter (co) polymer, vinyl acetate- (2-ethylhexyl acrylate) copolymer, polyvinyl chloride, polysalt vinylidene, polystyrene, etc. These copolymers are mentioned. Of these, (meth) acrylic acid esters, (meth) acrylate (co) polymers, vinyl ester (co) polymers, polystyrene, and synthetic rubbers are preferably used.

[0047] Further, it is preferable that the heat-fusible particles are dispersible in water. The average particle size is preferably on-machine developability, surface strength such as sensitivity, etc. is 0.01 to: LO / zm. More preferably, it is 0.1 to 3 μm.

[0048] Further, the composition of the heat-fusible particles may vary continuously between the inside and the surface layer, or may be coated with a different material.

[0049] As a coating method, a known microcapsule forming method, a sol-gel method, or the like can be used.

The content of the thermoplastic fine particles in the layer is preferably 1 to 90% by mass of the entire layer.

0% by mass is more preferable.

[0050] Examples of the microcapsules enclosing the lipophilic material according to the present invention include, for example, JP-A-200.

As described in JP-A-2002-19317, there can be mentioned microcapsules containing a lipophilic material. As the lipophilic material, the above-mentioned thermoplastic lipophilic resin particles are preferably used.

[0051] The average size of the microcapsules is preferably 0.1 to 10 μm, more preferably 0.3 to 5 μm, and further preferably 0.5 to 3 m. preferable.

[0052] The content of (A) in the image forming layer is preferably 40 to 95% by mass, more preferably 50 to

80% by mass.

[0053] (B) Infrared absorbing cyanine dye

The infrared-absorbing cyanine dye according to the present invention can form an image by absorbing image exposure light, and examples thereof include the following dyes.

[0054] [Chemical 1] [z ^ [eeoo]

l7Z6lS0 / .00Zdf / X3d 6 mu 8 60 / 00Z OAV

[0056] [Chemical 3]

Tsuyoshi [zeoo]

Ζ61ζΟ / ίΟΟΖάΐ / 13ά mu 8 60 / 00Z OAV [S ^] [8S00]

* 0I0

(61-«1)

Ζ61ζΟ / ίΟΟΖάΐ / 13ά ZY mu 8 60 / 00Z OAV Set (¾005

> ¾25I [0900]

PZ6lS0 / L00Zd £ / 13d Mu 8 60 / 00Z OAV

[8 ^] [Ϊ900]

Ζ61ζΟ / ίΟΟΖάΐ / 13ά 9V mu 8 60 / 00Z OAV

[0062] The content of the dye in the image forming layer is preferably 3 to 30% by mass from the viewpoint of exposure visible image property, printing press contamination during on-press development, on-press developability, and printing durability. Preferably, it is 6-20 mass%, More preferably, it is 10-20 mass%.

[0063] When the cyanine dye is not water-soluble, it can also be used by being present on the surface of the resin particles or microcapsules by the method described in JP-A-2005-121949, for example. Further, it may be combined with the resin particles, or may be encapsulated in the microcapsule or exist in the capsule wall.

Examples of the water-soluble rosin having a mass average molecular weight of 200,000 or more according to the present invention include polysaccharides (CMC (carboxymethylcellulose), starch, alginate, pullulan, etc.), polyvinyl alcohol, polybulucetal, polyacrylic acid, polyacrylic. A water-soluble resin such as acid, polyacrylate, polyacrylamide and the like having a mass average molecular weight of 200,000 or more.

In the present invention, the molecular weight needs to be 200,000 or more from the viewpoint of suppressing on-press developability and pressure-sensitive image formability. [0065] The content of (C) in the image forming layer is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and still more preferably 5 to 15% by mass.

[0066] (D) Water-soluble basic compound

The water-soluble basic compound is an inorganic or organic compound that exhibits basicity when dissolved in water, and preferably has an on-press developability with a molecular weight of 1000 or less.

[0067] Examples of inorganic compounds include Na hydroxide, K, Li, and Na phosphate.

[0068] Examples of the organic compound include ammine compounds (such as triethanolamine), guanidine compounds, and imidazo compounds.

[0069] The content of (D) in the image forming layer is preferably in the range of 0.1 to 40% by mass, and the amount capable of adjusting the pH of the image forming layer coating solution to 6.5 to 12 is preferable. ! /.

In the present invention, the cyanine dye functions as a photothermal conversion agent.

[0071] The image forming layer may have a photothermal conversion agent other than the cyanine dye according to the present invention.

[0072] Examples of the photothermal conversion agent that can be used in combination include dyes or pigments other than cyanine dyes.

[0073] Examples of the dye include organic compounds such as croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, naphthalocyanine dyes, and azo dyes. , Thioamide, dithiol and indoor-phosphorus organometallic complexes.

[0074] Examples of the pigment include carbon, graphite, metal, metal oxide and the like.

[0075] As carbon, it is particularly preferable to use furnace black or acetylene black. The particle size (d50) is preferably lOOnm or less, more preferably 50 nm or less.

[0076] The graphite has a particle size of 0.5 μm or less, preferably 10 nm or less, more preferably

Fine particles of 50 nm or less can be used.

[0077] As the metal, any metal can be used as long as it has a particle size of 0.5 µm or less, preferably lOOnm or less, more preferably 50nm or less. The shape may be any shape such as a sphere, a piece, or a needle. Colloidal metal fine particles (Ag, Au, etc.) are particularly preferred. [0078] As the metal oxide, it is possible to use a material that exhibits a black color in a visible light castle !, a material that is electrically conductive, or that is a semiconductor. Materials that are black in the visible light castle include black iron oxide (Fe 2 O 3) and the two or more metals mentioned above

3 4

A black composite metal oxide is exemplified. Specifically, it 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 can be produced by the methods disclosed in JP-A-8-27393, JP-A-9-25126, JP-A-9-237570, JP-A-9-241529, and JP-A-10-231441. The composite metal oxide that can be used in the present invention is particularly preferably a Cu—Cr—Mn or Cu—Fe—Mn composite metal oxide. In the case of a Cu—Cr Mn system, it is preferable to perform the V treatment disclosed in JP-A-8-27393 in order to reduce elution of hexavalent chromium. These composite metal oxides have good coloration with respect to the amount added, that is, good photothermal conversion efficiency. These composite metal oxides preferably have an average primary particle diameter of 1 m or less, and preferably have an average primary particle diameter in the range of 0.01 to 0.5 m. When the average primary particle size is: L m or less, the photothermal conversion ability with respect to the added amount becomes better, and when the average primary particle size is in the range of 0.01-0. Photothermal conversion ability becomes better. However, the photothermal conversion ability with respect to the amount added is greatly affected by the degree of dispersion of the particles, and the better the dispersion, the better. Therefore, before adding these composite metal oxide particles to the coating solution for the layer, it is preferable to disperse them by a known method to prepare a dispersion liquid (paste). An average primary particle size of less than 0.01 is not preferable because dispersion becomes difficult. A dispersing agent can be appropriately used for the dispersion. The addition amount of the dispersant is preferably 0.01 to 5% by mass, more preferably 0.1 to 2% by mass with respect to the composite metal oxide particles. The type of dispersant is not particularly limited, but it is preferable to use a Si-based surfactant containing Si element.

[0079] Examples of materials that have conductivity or are semiconductors include, for example, SnO doped with Sb (ATO), In O with added Sn (ITO), TiO, and TiO. TiO (acid

2 2 3 2 2

For example, titanium oxynitride, generally titanium black). Also, those coated with a core material (BaSO, TiO, 9A1 O · 2Β 0, K O'nTiO, etc.) with these metal oxides are used.

4 2 2 3 2 2 2

can do. Their particle size is 0. or less, preferably lOOnm or less, more preferably Or less than 50nm.

[0080] The image forming layer may contain a surfactant. Although surfactants such as Si-based or F-based can be used, 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 from 0.01 to 3% by mass, more preferably from 0.03 to 1% by mass, based on the entire hydrophilic layer (solid content as the coating solution).

[0081] The coating solution for an image forming layer according to the present invention is obtained by dispersing and dissolving the components contained in the image forming layer in a coating solvent. Examples of the coating solvent include water, alcohol (methanol, ethanol, IPA (isopropyl alcohol)), and other organic solvents compatible with water.

[0082] The pH of the image forming layer coating solution can be adjusted to 6.5 to 12 by adjusting the content of the water-soluble basic compound in the coating solution.

The formation of the image forming layer using the image forming layer coating solution is performed by applying the image forming layer coating solution on the support and drying it.

[0084] As a coating method, any known coating method can be used as long as it can be uniformly applied in the above-mentioned application range. For example, wire bar coating, curtain coating, and extrusion coater coating method. Is mentioned.

[0085] The temperature for drying to form a coating film is in the range of 30 ° C to 300 ° C, and the time is from 0.1 second to

I prefer to do it in 10 minutes!

[0086] Further, the drying step may be one in which the temperature is changed stepwise or steplessly.

[0087] The solid concentration of the image forming layer coating solution is preferably 1% by mass to 30% by mass, depending on the coating method! /.

[0088] (Support)

As the support according to the present invention, a substrate having a hydrophilic surface is used. A base material having a hydrophilic surface is a base material having a surface where a portion from which an image forming layer has been removed at the time of printing is water-receptive and can become a non-image part. A substrate having a hydrophilic surface layer or a substrate provided with a hydrophilic layer containing a hydrophilic substance can be used. [0089] The base material is a plate-like body or a film body that can carry a constituent layer including a hydrophilic layer and an image forming layer, and a known material used as a base material for a printing plate can be used. .

[0090] For example, a metal plate, a plastic film, a paper treated with polyolefin, a composite base material obtained by appropriately bonding the above materials, and the like can be given.

[0091] The thickness of the substrate is not particularly limited as long as it can be attached to a printing press! /

1S 50-500 μm is generally handled! /, Easy! /.

[0092] Examples of the metal plate used as the base material include iron, stainless steel, aluminum and the like. Aluminum is also particularly preferable in terms of the relational force between specific gravity and rigidity.

[0093] A preferred embodiment in the case of providing a hydrophilic layer by hydrophilizing the surface of the substrate is the case of using an aluminum substrate. Since the hydrophilic layer is provided on the aluminum substrate, the surface is roughened and used. It is done.

[0094] Prior to roughening (graining treatment), it is preferable to perform a degreasing treatment to remove 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. An alkaline aqueous solution such as caustic soda can also be used for the degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, it is possible to remove dirt and acid film that cannot be removed only by the above degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for degreasing, smut is generated on the surface of the support. In this case, acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof is used. It is preferable to immerse and apply a desmut treatment. Examples of the roughening method include a mechanical method and a method of etching by electrolysis.

[0095] The mechanical roughening method used is not particularly limited, but a brush polishing method and a Houng polishing method are preferred.

[0096] The electrochemical surface roughening method is not particularly limited, but a method of electrochemical surface roughening in an acidic electrolyte is preferred.

[0097] 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. Um, potassium hydroxide, etc. are used. Among these, it is preferable to use an alkaline aqueous solution. The amount of aluminum dissolved on the surface is preferably 0.5 to 5 g / m ² . Alkali ’s

It is preferable to carry out a neutralization treatment after immersion in an aqueous solution and then immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

[0098] The mechanical surface roughening method and the electrochemical surface roughening method may each be used alone to roughen the surface, or the mechanical surface roughening method followed by the electrochemical surface roughening method. To roughen the surface.

[0099] Following the roughening treatment, an anodizing treatment can be performed. In the present invention, a known method with no particular limitation can be used for the anodizing treatment method that can be used. By performing the anodizing treatment, an oxide film is formed on the support.

[0100] The anodized support may be subjected to a sealing treatment if necessary. These sealing treatments can be carried out using known methods such as hot water treatment, boiling water treatment, steam treatment, sodium silicate treatment, dichromate aqueous solution treatment, nitrite treatment, and acetic acid ammonium treatment.

[0101] Further, after these treatments, water-soluble rosin, such as polyvinylphosphonic acid, polymers and copolymers having sulfonic acid groups in the side chain, polyacrylic acid, water-soluble metal salts (for example, boron Zinc acid) or undercoat with yellow dye, amine salt, etc. are also suitable

. Furthermore, a sol-gel-treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A-5-304358 is covalently used.

[0102] Examples of the plastic film used for the substrate include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters.

[0103] As the substrate that can be used in the present invention, polyethylene terephthalate and polyethylene naphthalate are particularly preferable.

[0104] In order to improve the adhesion of the plastic film to the coating layer, it is preferable to perform easy adhesion treatment or undercoat layer coating on the coated surface. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment. Also as an undercoat layer Examples include a layer containing gelatin or latex. The undercoat layer may contain an organic or inorganic known conductive material.

[0105] The hydrophilic layer is a layer that can be a non-image area where printing ink does not deposit during printing, and is a layer formed on a substrate or a surface when the substrate surface is hydrophilized. Is a layer. The hydrophilic layer contains a hydrophilic material.

[0106] The hydrophilic layer may be a single layer, or a plurality of layer forces may be formed.

[0107] As the amount of the hydrophilic layer, 0.1 to: LOgZm ² is preferable, and 0.2 to ⁵ gZm ² is more preferable.

[0108] The hydrophilic material used for the hydrophilic layer is preferably a metal oxide, particularly preferably a hydrophilic material that is substantially insoluble in water.

[0109] The metal oxide preferably contains metal oxide fine particles. Examples thereof include colloidal silica, alumina sol, titer 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. As the average particle size, it is also possible to use several kinds of metal oxide fine particles having different average particle sizes, preferably 3 to: LOOnm. Further, the surface of the particles may be subjected to surface treatment.

[0110] The metal oxide fine particles can be used as a binder by utilizing the film-forming property. It is suitable for use in a hydrophilic layer where the decrease in hydrophilicity is less than when an organic binder is used.

[0111] 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 it has good strength even in such layers as it contains 91% by mass or more of materials that do not contain carbon atoms. Obtainable.

[0112] The colloidal silica preferably includes necklace-like colloidal silica and fine particle colloidal silica having an average particle size of 20 nm or less. Further, the colloidal silica preferably exhibits alkalinity as a colloidal solution.

[0113] The necklace-like colloidal silica used in the present invention is a general term for an aqueous dispersion of spherical silica having a primary particle diameter of the order of nm. Necklace-shaped colloid used in the present invention Silica 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 an image in which the silica particles of colloidal silica are joined together is shaped 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 the Si OH 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.

[0114] 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 (average particle size in the connected state is about 170 nm) ”, and acid products corresponding to these are“ SNOWTEX PS—S—0 ”and“ SNOWTEX—PS—M—0 ”. ”And“ Snowtex PS—L-0 ”.

[0115] By adding the 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.

[0116] Among these, alkaline "Snowtex PS-S", "Snowtex PS-M" and "Snowtex PS-L" improve the strength of the hydrophilic layer, and the number of printed sheets Especially, even if the occurrence of soiling is suppressed, especially preferred.

[0117] Further, it is known that the colloidal silica has a stronger binding force as the particle size is smaller. In the present invention, it is preferable to use colloidal silica having an average particle size of 20 nm or less, 3 to 15 nm. More preferably. Moreover, among the colloidal silicas, as described above, alkali-based ones are highly effective in suppressing the occurrence of scumming, so it is particularly preferable to use an alkaline colloidal silica force.

[0118] Average particle size force Alkaline colloidal silica in this range includes "Snowtex 1-20 (particle size 10-20nm)" and "Snowtex 1 30 (particle size 10-20ηm)" manufactured by Nissan Chemical Co., Ltd. , "Snowtex 1 40 (particle size 10-20nm)", "Snowtex 1 N (particle size 10-20nm)", "Snowtex 1 S (particle size 8: L lnm)", "Snowtex 1 XS (Particle diameter 4 to 6 nm). [0119] Colloidal silica having an average particle diameter of 20 nm or less is particularly preferable because it can be further improved in strength while maintaining the porosity of the layer by using in combination with the above-mentioned necklace-like colloidal silica force. .

[0120] Colloidal silica with an average particle size of 20 nm or less Z-necklace-shaped colloidal silica is preferably 95Z5-5Z95 (mass ratio) 70Z30-20Z80 is more preferred 60/4 0-30 / 70 force Even better!

[0121] 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.

[0122] 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 the gel obtained by neutralizing the aqueous silicate solution, or by pulverizing the precipitate deposited after neutralization. In the dry method, it is obtained by burning silica with hydrogen and oxygen and precipitating silica. The porosity and particle size of these particles can be controlled by adjusting the production conditions.

[0123] The porous silica particles are particularly preferably those obtained by a wet gel force.

[0124] 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. It is possible to synthesize the ratio of alumina and silica force in the particles in the range of 1: 4 to 4: 1. In addition, particles produced by adding other metal alkoxides at the time of production as composite particles of three or more components can also be used in the present invention. The porosity and particle size of these composite particles can also be controlled by adjusting the production conditions.

[0125] The porosity of the particles is preferably 1. OmlZg or more in terms of the pore volume before dispersion 1. More preferably 2 mlZg or more 1. 8 to 2.5 mlZg or less Is more preferable.

[0126] It is preferable that the particle size is substantially 1 _μm or less in a state in which it is contained in the hydrophilic layer (for example, when crushed during dispersion). More preferably, it is as follows. [0127] The particle diameter of the porous inorganic particles is preferably substantially 1 μm or less, more preferably 0.5 m or less, when contained in the hydrophilic layer.

[0128] Further, 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, rhosite, talc, smectite (montmorillonite, piderite, hectorite, sabonite, etc.), vermiculite, my strength (mica), chlorite, and the like. Examples include talcite and layered polykeyate (force nemite, macatite, eyelite, magadiite, kenyaite, etc.). Among them, 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 fluorine mica is preferable because it can be obtained with stable quality such as particle size. Further, among the synthetic fluorinated mica, those that are free swelling that are swellable are more preferred.

[0129] In addition, intercalation compounds of the above-mentioned layered minerals (such as billard crystals), those subjected to ion exchange treatment, surface treatment (silane coupling treatment, compounding treatment with organic noinda) Etc.) can also be used.

[0130] Regarding the size of the layered mineral particles, the average particle size (maximum particle length) is 20 / in the state of being contained in the layer (including the case where the swelling process and dispersion peeling process have been performed). It is preferably a thin layer with an average aspect ratio (maximum particle length Z particle thickness) of 20 or more, an average particle diameter of 5 m or less, and an average aspect ratio of 50 or less. More preferably, the average particle size is: L m 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 possible to form a tough coating film in a dry state that is hard to crack. In addition, in a coating solution containing a large amount of particulate matter, sedimentation of the particulate matter can be suppressed by the thickening effect of the layered clay mineral.

[0131] The content of the layered mineral particles is preferably 0.1 to 30% by mass, more preferably 1 to 10% by mass, based on the entire layer. In particular, swellable synthetic fluoromica is smectite. The addition of a small amount is preferable because an effect is seen. The layered mineral particles may be added to the coating liquid as a powder! /, 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) It is preferable to prepare a gel obtained by swelling layered mineral particles alone in water and then adding the gel to the coating solution.

[0132] In the hydrophilic layer according to the present invention, a silicate aqueous solution can also be used as another additive material. Alkaline metal silicates such as Na, Ca, and Li are preferred, and the SiO / M0 ratio of the coating solution should not exceed 13 when the silicate is added.

twenty two

V, choosing to be in the range is preferred to prevent inorganic particles from dissolving.

[0133] Further, an inorganic polymer or an organic-inorganic hybrid polymer by a so-called sol-gel method using a metal alkoxide can be used. Regarding the formation of inorganic polymers or organic-inorganic hybrid polymers by the sol-gel method, for example, the force described in “Application of the sol-gel method” (published by Sakuo Sakuo, published by Z. The known methods described in the literature can be used.

[0134] The hydrophilic layer may contain a hydrophilic organic resin!ヽ.

[0135] Examples of hydrophilic organic resins include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl alcohol, styrene butadiene copolymer, and methyl metatalylate butadiene copolymer conjugate. Examples thereof include resins such as gen-based polymer latex, acrylic polymer latex, vinyl-based polymer latex, polyarylamide, and polybutylpyrrolidone.

[0136] In addition, cationic resins that may contain cationic resins include polyalkylene polyamines such as polyethyleneamine and polypropylene polyamine or derivatives thereof, tertiary amino groups and quaternary compounds. Examples thereof include acrylic resin having an ammonium group and diacrylamine. Cationic rosin may be added in the form of fine particles. Examples thereof include cationic microgels described in JP-A-6-161101.

[0137] In a more preferred embodiment of the present invention, the hydrophilic organic resin contained in the hydrophilic layer is water-soluble, and at least a part thereof is water-soluble and can be eluted in water. It exists in a state.

[0138] As the water-soluble material contained in the hydrophilic layer, saccharides are preferred. [0139] As the saccharide, an oligosaccharide, which will be described in detail later, can be used, but it is particularly preferable to use a polysaccharide.

[0140] As polysaccharides, starches, celluloses, polyuronic acids, pullulans, and the like can be used. Cellulose derivatives such as methylcellulose salts, carboxymethylcellulose salts, hydroxyethylcellulose salts and the like are preferred. Sodium salt and ammonium salt are preferred.

[0141] This is because inclusion of a polysaccharide in the hydrophilic layer favors the surface shape of the hydrophilic layer V, and the effect of forming a state is obtained.

[0142] The surface of the hydrophilic layer preferably has a concavo-convex structure with a pitch of 0.1 to 50 / zm like the aluminum grain of the PS plate. This concavo-convex improves water retention and image area retention. To do.

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

[0144] The shape of the concavo-convex structure (pitch, surface roughness, etc.) depends on the type and amount of alkaline colloidal silica, the type and amount of water-soluble polysaccharides, the type and amount of other additives, and the solidity of the coating liquid. It is possible to appropriately control the concentration, wet film thickness, drying conditions, and the like.

[0145] 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 with a smaller pitch is formed on the concavo-convex structure with a large pitch may be formed.

[0146] The surface roughness is preferably 100 to 1000 nm for Ra, more preferably 150 to 600 nm force S.

[0147] The thickness of the hydrophilic layer is 0.01 to 50 µm, preferably 0.2 to 10 µm, and more preferably 0.5 to 3 / ζ πι.

[0148] The hydrophilic layer coating solution for forming the hydrophilic layer may contain a water-soluble surfactant for the purpose of improving the coating property. S-type or F-type surfactants can be used, but in particular, the use of surfactants containing Si elements may cause printing stains. Is preferable.

[0149] The content of the surfactant is 0.01 to 3 mass of the entire hydrophilic layer (solid content as the coating solution).

% Is preferable 0.03 to 1% by mass is more preferable.

[0150] (Protective layer)

A protective layer may be provided on the image forming layer according to the present invention.

[0151] As the material used for the protective layer, the above-mentioned water-soluble and water-dispersible resin can be preferably used.

[0152] Also, hydrophilic overcoat layers described in JP-A-2002-19318 and JP-A-2002-86948 can be preferably used.

[0153] The amount per the protective layer, 0. 01: A LOG / m ^2, is Ri preferably 0. l~3g / m ² der, more preferably 0. 2~2gZm ^2.

[0154] (Image forming method)

The image forming method of the present invention is an image forming method in which a printing plate material having an image forming layer that can be developed on-press on a support is subjected to image exposure, and the image forming layer comprises: And the image forming layer is formed using a coating solution for an image forming layer having a pH of 6.5 to 12, and a color difference (LW measurement color) between an exposed portion and an unexposed portion by the image exposure. Δ Δ) in space is 5 or more, and the difference (Δ a *) between the a * of the exposed area and the a * value of the unexposed area by the image exposure, the b * value of the exposed area and b of the unexposed area * The ratio (Δb * / Δa *) to the difference (Δb *) from the value is 0.3 or more.

(B) Infrared absorbing cyanine dye

The color difference ΔΕ indicates the distance between the position of the exposed area in the LW measurement color space and the position of the unexposed area in the LW measurement color space.

[0155] The difference (Δ a *) between the a * value of the exposed area and the a * value of the unexposed area by image exposure is the value of (a * value of the exposed area minus 1 a * value of the unexposed area). Yes, the difference between the b * value of the exposed area and the b * value of the unexposed area (Δ b *) is the value of (b * value of exposed area minus b * value of unexposed area).

In general, if Δ Δ is large, the visibility of the exposed visible image is good. However, since the visual visibility is also affected by the direction of hue change, the Δ In spite of not being large, there is a direction of hue change in which visibility is good.

[0157] In a printing plate material having a photosensitive layer containing an infrared-absorbing cyanine dye, the present inventors have conducted intensive studies. As a result, ΔΕ is 5 or more and Ab * Z Aa * is 0.3 or more. Thus, it has been found that good visibility can be obtained, and the present invention has been achieved.

[0158] In other words, in the hue change due to exposure fading of a simple cyanine dye, the change in the b * value is poor with respect to the change in the a * value. Become.

[0159] By changing the b * value as well as the a * value by exposure, 厶 7 厶 becomes 0.3 or more and is visible

'The sex will also be good.

[0160] Δ Ε is preferably 8 or more, more preferably 10 or more.

[0161] Further, 厶 7 厶 & * is preferably 0.4 or more, more preferably 0.46 or more.

[0162] (Image exposure)

Image exposure according to the present invention is performed by irradiation with actinic rays according to image data.

In particular, image exposure with laser light is a preferred embodiment.

[0163] Image exposure more specifically emits in the infrared and Z or near infrared regions, ie 700

Scanning exposure using a laser that emits light in the wavelength range of ~ 1500nm is preferred.

[0164] Although a gas laser may be used as the laser, it is particularly preferable to perform scanning exposure using a semiconductor laser that emits light in the near infrared region.

[0165] As an apparatus suitable for scanning exposure, any apparatus may be used as long as it can form an image on the surface of a printing plate material in accordance with an image signal from a computer using a semiconductor laser. .

[0166] Generally, (1) a method of exposing the entire surface of the printing plate material by performing two-dimensional scanning on the printing plate material held by the flat plate holding mechanism using one or more laser beams.

(2) The printing plate material held along the cylindrical surface inside the fixed cylindrical holding mechanism is used in the circumferential direction of the cylinder (mainly using one or more laser beams from the inside of the cylinder). (Scanning direction) while moving in the direction perpendicular to the circumferential direction (sub-scanning direction) while scanning in the scanning direction) (3) Cylindrical drum surface rotating around the axis as a rotating body The plate material held in the cylinder is scanned in the circumferential direction (main scanning direction) by rotating the drum using one or more laser beams from the outside of the cylinder, and perpendicular to the circumferential direction. There is a method in which the entire surface of the printing plate material is exposed by moving in the direction (sub-scanning direction).

[0167] (On-press development method)

The image forming layer according to the present invention is a layer that can be developed on the machine, and the non-image part is removed on the printing machine using dampening water and / or ink.

[0168] Removal of the non-image area (unexposed area) of the image forming layer on the printing machine can be performed by contacting a watering roller or an ink roller while rotating the plate cylinder. This can be done by various sequences as shown in the examples or otherwise. In that case, the water volume adjustment that can be adjusted to increase or decrease the amount of dampening water required for printing is divided into multiple stages, or there is no need. You may change the stage.

(1) As a sequence for starting printing, contact the water roller to rotate the plate cylinder 1 to tens of rotations, then contact the ink roller to rotate the plate cylinder 1 to tens of rotations, and then Start printing.

(2) As a sequence for starting printing, contact the ink roller to rotate the plate cylinder 1 to tens of rotations, then contact the watering roller to rotate the plate cylinder 1 to tens of rotations, then Start printing.

(3) As a sequence for starting printing, the water roller and the ink roller are brought into contact with each other substantially simultaneously to rotate the plate cylinder one to several tens of turns, and then printing is started. Example

[0169] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. In the examples, “parts” represents “parts by mass” unless otherwise specified.

[0170] Fabrication of support

A support was prepared as follows.

[0171] [Support]

An aluminum plate (material 1050, tempered H16) with a thickness of 0.24 mm is immersed in a 1% by weight sodium hydroxide aqueous solution at 50 ° C and dissolved so that the dissolution amount is 2 g / m ^2. After washing with water, it was immersed in a 5 mass% nitric acid aqueous solution at 25 ° C for 30 seconds, neutralized, and then washed with water. [0172] Next, this aluminum plate was electrolytically roughened with an electrolytic solution containing hydrochloric acid 1 lgZL, acetic acid 10 gZL, and aluminum 8 gZL using a sinusoidal alternating current at a peak current density of 80 AZdm ^2. Processed.

[0173] The distance between the electrode and the sample surface at this time was 10 mm. The electrolytic surface roughening treatment is performed in 8 steps, and the amount of electricity processed (at the time of anode) is 40CZdm ² , the total amount of electricity processed (at the time of anode).

) It was used as a 320CZdm ^2. In addition, there was a 3 second pause between each treatment.

[0174] After electrolytic roughening, the amount of dissolution including the smut of the roughened surface is 0.65 g / m ² by dipping in a 10 mass% phosphoric acid aqueous solution maintained at 50 ° C. Etched and washed with water.

[0175] Then, in a 20% aqueous solution of sulfuric acid, the amount with a current density of 5AZdm ² 2. 5gZm anodizing a line under the condition for forming the ^second anode oxidation coatingヽwas further washed with water.

[0176] Next, after squeezing the surface water after washing with water, it was immersed for 15 seconds in a 1% by weight No. 3 sodium hydroxide aqueous solution maintained at 30 ° C, washed with water, and then dried at 80 ° C for 5 minutes. Thus, a support was obtained.

[0177] The surface shape parameter Ra value of the support was determined by the following method. The Ra value was 0.38 μm.

[0178] After depositing platinum rhodium with a thickness of 1.5nm on the sample surface, using WYKO's non-contact three-dimensional roughness measuring device: RST plus, the condition of 40 times (111.2 m X 149 After measuring with a measuring range of 7 m, measuring point 236 X 368, resolution of about 0.5 m), processing the measurement data by applying tilt correction and Median Smoothing filter to remove noise Ra value was determined. The measurement was performed 5 times at different measurement points, and the average was calculated.

[0179] Example 1

[Preparation of coating solution for image forming layer]

Each material in the table below was sufficiently mixed and stirred and filtered to prepare a coating solution for each image forming layer having a solid content concentration of 5% by mass. As the order of addition of the raw materials, pure water was added to the dispersion of thermoplastic resin particles or microcapsules, and then an aqueous solution or IPA solution of cyanine dye was added dropwise and mixed while stirring. Next, an aqueous solution prepared by mixing a water-soluble aqueous solution of rosin and a basic compound or trehalose in advance is added dropwise and mixed. It was.

[0180] A dispersion of microcapsules was prepared as follows.

[0181] [Preparation of microcapsule dispersion]

Isocyanate compound: Takenate D-204 (Mitsui Takeda Chemical Co., Ltd., butyl acetate solution having a solid content of 50% by mass) 1. 90 g of glycidyl metatalylate was uniformly dissolved in 8. Og to prepare an oily component. Next, propylene glycol alginate (Duckroid LF, manufactured by Kibun Food Chemifa Co., Ltd., number average molecular weight: 2 X 105) 3 g, polyethylene glycol (PEG 400, manufactured by Sanyo Chemical Co., Ltd.) 1 An aqueous phase mixed with Og was prepared. Subsequently, the oil component and the aqueous phase were mixed and emulsified at room temperature with lOOOOrpm using a homogenizer, and reacted at 60 ° C for 3 hours to obtain microcapsules having an average particle size of 0.4 m.

[0182] Coating solution composition for image forming layer (numerical values in the table represent parts by mass)

[0183] [Table 1]

Image formation / S coating solution No.

Material

(1) (2) (3) (4) (5) (6) (7) Thermoplastic styrene-acrylic particle dispersion 7.50 7.50 7.50 6.8 & 7.50 7.50 Resin particles Average particle size ΙΟΟΠΒΚ TgJOO,

40% solid content, pH 8,

Solvent composition: water / IPA = 90/10

Micro Prepared microcapsules 33,75 capsules Dispersion

A solution of cyanine dye cyanine dye [〗] 50.00 50,00 50.00 50.00 50,00 50.00 Solid content 1 ¾%

Cyanine dye [2] in 12.50 IPA solution solid?

Water-soluble resin Polyacrylic acid aqueous solution 3.33 2.50

Mw 250,000, solid? ^ Min 15 mass

Polyacrylic acid aqueous solution 3,75 3-50 3.75 Mw 2.5 million, solid content 10 ¾%

Polyacrylamide aqueous solution 12.50 12.50 Hw 3 million, solid content 2% by mass

Polyacrylic acid Na aqueous solution

10,000, solid content 30% by mass

Hydroxic acid aqueous solution 10.00 7.50 Solid content 10% by mass

Water-soluble tribasic phosphate * 12 aqueous solution 11.25 12.50 11-25 Compound base solid content 10¾%

Z-methylimidazole aqueous solution 28.00

Solid content 5% by mass

Guanidine carbonate aqueous solution 25.00 Solid content 5% by mass

Water-soluble compounds

Solid content 5% by mass

Pure water 29.17 27.50 17.50 11.62 5,00 65.00 6.25 Coating solution pH 8 7.5 9.5 7 9 7.5 8 2]

Coating solution for image formation »Material

(8) (9) (10) (1!) (12) Thermoplastic styrene-acrylic particle dispersion 7.50 7.50 7.50 7.50 7.50 Resin particles Average particle size 100nra, Tg.i00 ° C,

40% solid content, pK8,

Solvent composition: water ΖΙΡΑ = 90/0

Micro Prepared microcapsules

Capsule dispersion

A solution of cyanine dye cyanine dye [色素] 50.00 50.00 50.00 50.00 50.00

1% solid content

A solution of cyanine dye [2]

Solid content 4% by mass

Water-soluble resin Polyacrylic acid aqueous solution

w250,000, solid content 15% by mass

Polyacrylic acid aqueous solution 3.75 5.00 Mw 2.5 million, solid content 10¾%

Polyacrylamide aqueous solution

Μ <ι 3 million, 2¾% solids

Polyacrylic acid Na aqueous solution ί .67 Mwl 70,000, solid content 30% by mass

Sodium hydroxide aqueous solution 10.00 Solid content 10 S amount%

Soluble basic triphosphate Na. ¹ 2 Water solution 11.25

Compound Solid content 10 «%

Z-methylimidazole aqueous solution

Solid content 5% by mass

Aqueous solution of guanidine carbonate 20.00 5% solids

Water-soluble compound trehalose aqueous solution Π .25 3.75 5.00 10.00

Solid content 5% by mass

Pure water 27.50 27.50 27.50 27.50 20.83 Coating solution pH 5! 2.5 13,5 6 9 9]

Cyanine dye [1]

[0186] [Preparation of printing plate material]

Each image forming layer coating solution was coated on the support using a wire knife so that the amount applied with drying was 0.7 gZm ^2, and dried at 55 ° C. for 3 minutes. Next, this was subjected to aging treatment at 40 ° C. for 24 hours to obtain printing plate materials shown in Table 3.

[0187] [Exposure with infrared laser]

Each printing plate material was brazed and fixed to an exposure drum. A laser beam with a wavelength of 830 nm and a spot diameter of about 18 / zm was used for exposure, and an image was formed with 175 lines at 2400 dpi (dpi represents 2.5 dots per 54 cm). The exposed image contains a solid image, a 1 to 99% halftone dot image, and a 10 point size character. The exposure energy was 300 mjZcm2.

[0188] [Exposure visibility evaluation]

The printing plate material after the exposure was visually observed, and the visibility of the exposed area and the readability of the characters were judged comprehensively, and the evaluation was performed according to the following criteria. The results are shown in Table 3.

[0189] 〇: Sufficient visibility and easy to read characters.

[0190] Δ: Power with a certain degree of visibility.

[0191] X: Characters with low visibility cannot be read. [0192] [Hue change evaluation]

The unexposed part and the solid exposed part of the printing plate material were measured using X-Rite520 (manufactured by X-Rite), and Δ Δ value and A b * Z A a * were measured. The results are shown in Table 3.

[0193] [Printing method]

Printing press: using manufactured by Mitsubishi Heavy Industries, Ltd. DAIYA1F-1, coated paper, dampening water: Asutoroma click 3 (Nikken I匕学Laboratory Ltd.) 2 mass ^_0/0, ink (Toyo Ink Co., Ltd. TK Haiyu - tee M red) was used for printing.

[0194] The printing plate material after exposure was directly attached to the plate cylinder, and 500 sheets were printed using the same printing conditions and printing sequence as the PS plate.

[0195] Next, the printing paper was changed to high-quality paper (manufactured by Nippon Paper Industries Co., Ltd., Shirai), and printing was performed up to 10,000 sheets.

[0196] [Scratch mark dirt evaluation]

The non-image area of the printing plate material after exposure was scratched with a nail. Printing was performed using a printing plate material with scratch marks, and scratch marks were evaluated using the 50th printed material after printing. The degree of stains on the printed material was visually evaluated, and “○” indicates that the stain is hardly confirmed, “△” indicates that the stain can be slightly confirmed, and “X” indicates that the stain can be clearly confirmed. The results are shown in Table 3.

[0197] [Evaluation of printing durability]

The printed matter was sampled every 1000 prints, and the degree of image deterioration in the 3% dot image area and solid image area was confirmed. When 3% halftone dot image area is confirmed to be missing a halftone dot, or when smudge is confirmed visually in the solid image area, the printing end point is determined, and the number of printed sheets is defined as the number of printed sheets. . Even after printing 10,000 sheets, more than 10,000 sheets were found to have been unable to confirm 3% halftone dot loss or solid image blurring. The results are shown in Table 3.

[0198] From Table 3, it can be seen that the printing plate material of the present invention has good exposure and visible image properties, and is excellent in printing durability if it is resistant to scratch marks.

[0199] [Table 3] Printing plate For image forming bottle Exposure Scratch Printing durability The present invention

Δ E Δ b '/ Δ a *

Material No. Coating solution No. Visible image trace Stain [sheet] Z comparison example

1 (1) ○ 9.0 0.45 ○ 10000 or more The present invention

2 (2) 0 8.5 0.45 0 10000 or more Present invention

3 (3) ○ 10.5 0.50 ○ 10000 or more The present invention

4 (4) 0 8,5 0.50 ○ 10000 or more The present invention

5 (5) o 10.0 0.45 0 10000 or more Present invention

6 (6) ○ 9.0 0.50 o 10000 or more The present invention

7 (7) o 9.5 0.45 ○ 10000 or more The present invention

8 (8) X 4.0 0.05 ○ 5000 Comparative example

9 (9) Δ6.0 0.25 X 7000 Comparative example

10 (10) Δ 5.5 0.20 X 6000 Comparative example

11 (11) X 4.0 0.05 O 4000 Comparative example

12 (12) 〇 7.0 0.40 X 10000 or more Comparative example

Claims

The scope of the claims

[1] A printing plate material having an on-press developable image forming layer on a support, the image forming layer contains the following (A) to (D), and the image forming layer: A printing plate material characterized by being formed using a coating solution for an image forming layer having a pH of 6.5 to 12.

(B) Infrared absorbing cyanine dye

(D) Water-soluble basic compound

[2] The printing plate material according to claim 1, wherein the content of the (B) infrared-absorbing cyanine dye is 10% by mass to 20% by mass with respect to the image forming layer.

[3] An image forming method for image-exposing a printing plate material having an on-press developable image forming layer on a support, the image forming layer containing the following (A) and (B), and The image forming layer is formed using a coating solution for an image forming layer having a pH of 6.5 to 12, and the color difference (L * a * b * measurement) between an exposed portion and an unexposed portion by the image exposure. Δ Ε) in color space is 5 or more, and the image

The difference between the a * value of the exposed area and the a * value of the unexposed area due to exposure (Δ a *), and the difference between the b * value of the exposed area and the b * value of the unexposed area (Δ b *) The image forming method, wherein the ratio (Δb * Z Δa *) of the image is 0.3 or more.

(B) Infrared absorbing cyanine dye