JP2003094849A - Original plate for lithography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an original plate for lithography which enables making of a lithographic plate having a printing durability, by on-machine development. SOLUTION: In the original plate for lithography having a constitution wherein an image forming layer containing particulates of a hydrophobic polymer, and a hydrophilic polymer, is provided on a hydrophilic substrate, the particulates of the hydrophobic polymer each having a surface of an indented shape are used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lithographic printing original plate. In particular, the present invention relates to a lithographic printing original plate capable of recording an image by scanning exposure of laser light based on a digital signal.

[0002]

2. Description of the Related Art Generally, a lithographic printing plate comprises an oleophilic image portion that receives ink during the printing process and a hydrophilic non-image portion that receives fountain solution. A conventional lithographic printing plate is prepared by mask-exposing a PS plate having a lipophilic photosensitive resin layer on a hydrophilic support through a lith film, and then dissolving and removing the non-image area with a developing solution. It was normal to do. In recent years, image information is electronically processed as digital information using a computer, accumulated, and output. Therefore, in the image forming process according to the digital image information, the image formation is directly performed on the lithographic printing plate precursor without the intermediary of the lith film by the scanning exposure using the highly directional actinic radiation such as the laser beam. Is desirable. In this way, the technology of making a printing plate from digital image information without using a lith film is a computer-to-computer method.
It is called a plate (CTP). When the conventional plate-making method for a printing plate using a PS plate is attempted to be carried out by computer-to-plate (CTP) technology, there is a problem that the wavelength region of laser light and the photosensitive wavelength region of the photosensitive resin do not match.

In addition, in the conventional PS plate, a step (developing process) of dissolving and removing the non-image portion after exposure is indispensable.
Further, a post-treatment step of washing the developed printing plate with water, treating with a rinse solution containing a surfactant, or treating with a desensitizing solution containing gum arabic or a starch derivative was also required. The fact that these additional wet treatments are indispensable has been a major study subject of conventional PS plates. Even if the first half (image forming process) of the plate making process is simplified by the digital process, the effect by the simplification is insufficient in the wet process in which the latter half (developing process) is complicated. Particularly in recent years, consideration of the global environment has become a major concern of the entire industry. In consideration of the environment, it is desirable that the wet post-treatment be simplified, changed to the dry treatment, or even eliminated.

As one of the methods for eliminating the processing step, an exposed printing plate precursor is mounted on a cylinder of a printing machine, and dampening water and ink are supplied while the cylinder is rotated to supply the printing plate precursor. There is a method called on-press development that removes non-image areas. That is, after exposing the printing plate precursor,
This is a method in which it is installed in the printing machine as it is and the processing is completed during the normal printing process. Such a lithographic printing plate precursor suitable for on-press development has a photosensitive layer soluble in dampening water or an ink solvent, and is suitable for development on a printing machine placed in a bright room. It is necessary to have good light room handling.
In the conventional PS version, satisfying such requirements is
It was virtually impossible.

Japanese Patent No. 2938397 discloses a lithographic printing original plate having a hydrophilic support on which a photosensitive layer, in which fine particles of a thermoplastic hydrophobic polymer are dispersed in a hydrophilic binder polymer, is provided. According to the description of the publication, in plate-making, infrared laser exposure is carried out to form an image by coalescing (fusing) the thermoplastic hydrophobic polymer fine particles by heat, and then the plate is mounted on the plate cylinder of the printing machine and wetted. On-press development is possible by supplying water and / or ink. This lithographic printing plate precursor has a light-sensitive region in the infrared region, and thus has handleability in a bright room. However, in the image forming method in which the polymer particles as described above are fused and united by the heat generated by exposure, if the on-press development is facilitated, it is difficult to obtain the printing durability, and if the printing durability is increased, the on-press development is performed. However, there is a problem that it is difficult to achieve both of them, such as the deterioration of the printability and the difficulty of smearing during printing. For example, when the particle size of the polymer particles is increased, on-press development can be easily performed because the contact between particles is reduced, but the coating formed by heat fusion deteriorates and the printing durability decreases. On the other hand, when the particle size is reduced, the contact between particles increases, so that a film having printing durability can be formed by heat fusion, but on-press development becomes difficult.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate precursor capable of making a lithographic printing plate having printing durability by on-press development.

[0007]

The present invention provides a lithographic printing original plate as described in (1) and (2) below. (1) A lithographic printing original plate in which an image forming layer containing a fine particle of a hydrophobic polymer and a hydrophilic polymer is provided on a hydrophilic support, and the fine particle of the hydrophobic polymer has an uneven surface. A lithographic printing original plate comprising: (2) Fine particles of hydrophobic polymer are 0.05 to 2 μm
The lithographic printing original plate as described in (1), having an average particle size of

[0008]

INDUSTRIAL APPLICABILITY In the present invention, fine particles of a hydrophobic polymer having a surface with irregularities are used. Microparticles of hydrophobic polymers, including conventional techniques, are generally produced by emulsion polymerization methods. In the emulsion in the emulsion polymerization, the smaller the area of the interface, the more stable the state becomes, and therefore the particles tend to be spherical with the smallest surface area. When fine particles having a surface with irregularities are used instead of fine particles having a smooth surface such as spheres, the irregularities on the surface of the fine particles come into contact with each other and the fine particles are entangled with each other. Therefore, since the contact between the fine particles is increased, a film having printing durability can be formed by heat fusion. In addition, the irregularities on the surface of the fine particles cause fine voids between the fine particles. Due to the capillary phenomenon with respect to the voids, dampening water or ink easily penetrates between the fine particles. Therefore, in the on-press development, the fine particles in the unexposed area can be easily removed from the printing original plate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION [Shape of Fine Particles] In the present invention, the fine particles of the hydrophobic polymer have a shape having irregularities on the surface. The shape of the fine particles can be easily determined by observation with a microscope (usually an electron microscope). That is, fine particles of ordinary hydrophobic polymer are generally spherical surface smooth, fine particles having a different surface irregularities,
It can be easily identified. The average particle diameter of the hydrophobic polymer fine particles is preferably 0.05 to 2 μm, more preferably 0.08 to 0.8 μm. The average particle diameter (d) of the particles means the average diameter when the particles are approximate to a sphere.

The fine particles having irregularities on the surface can be produced by forming seed fine particles and causing a partial polymerization reaction on the surface of the seed fine particles. The seed particles can be synthesized by a polymerization reaction of a monomer (generally an ethylenically unsaturated monomer) corresponding to the hydrophobic polymer. A radical polymerization reaction, a cationic polymerization reaction, or an anionic polymerization reaction can be adopted as a specific polymerization reaction. The polymerization is preferably an emulsion polymerization reaction. With the emulsion polymerization reaction, fine particles can be formed at the same time as the synthesis of the hydrophobic polymer. For the emulsion polymerization reaction, reaction conditions generally used for producing latex may be adopted.

It is preferable to use a surfactant in the emulsion polymerization reaction in order to form homogeneous seed fine particles. Any of a cationic surfactant, an anionic surfactant, a nonionic surfactant and an amphoteric surfactant can be used. The amount of the surfactant used is preferably 0.01 to 10% by mass of the total amount of the monomers. Further, it is possible to form fine particles having irregularities on the surface by utilizing hetero aggregation.
Heteroaggregation is a phenomenon in which when two types of particles having different particle sizes and surface charges are mixed, one particle is electrostatically adsorbed on the surface of the other particle. As a result, the surface of the large particle can be covered with the small particle to form irregularities on the surface of the large particle. As a specific production method, there can be adopted a method in which spherical polymer particles are dispersed in an aqueous dispersion of coating material particles having a particle size smaller than the particle, and the dispersion is aggregated on the polymer particles. Composite fine particles obtained by aggregating a wax emulsion on the surface are used as electrophotographic toners.

A polymerization initiator (chain transfer agent) is preferably used in the polymerization reaction for forming fine particles. The amount of the polymerization initiator used is preferably 0.05 to 10% by mass of the total amount of the monomers. The polymer that constitutes the seed particles and the polymer that forms the surface irregularities are usually of different types. The “hydrophobic polymer fine particles” of the present invention satisfy the definition of the present invention even if the polymer forming the seed fine particles is hydrophilic as long as the polymer forming the surface irregularities is hydrophobic. However, it is preferable that both the polymer forming the seed particles and the polymer forming the surface irregularities are hydrophobic polymers. For details of confetti-like polymer particles having irregularities on the surface and a method for synthesizing them, see Matsumoto et al., Polymers, 33, 575 (197).
There is a description in 6). Two or more kinds of hydrophobic polymer particles may be mixed and used.

The main chain of the hydrophobic polymer is preferably selected from hydrocarbon (polyolefin), polyester, polyamide, polyimide, polyurea, polyurethane, polyether and combinations thereof. A hydrocarbon backbone is especially preferred.

Examples of repeating units of the hydrophobic polymer are shown below.

[0015]

[Chemical 1]

[0016]

[Chemical 2]

[0017]

[Chemical 3]

[0018]

[Chemical 4]

[0019]

[Chemical 5]

[0020]

[Chemical 6]

[0021]

[Chemical 7]

[0022]

[Chemical 8]

[0023]

[Chemical 9]

[0024]

[Chemical 10]

[0025]

[Chemical 11]

[0026]

[Chemical 12]

[0027]

[Chemical 13]

[0028]

[Chemical 14]

[0029]

[Chemical 15]

[0030]

[Chemical 16]

[0031]

[Chemical 17]

[0032]

[Chemical 18]

[0033]

[Chemical 19]

[0034]

[Chemical 20]

[0035]

[Chemical 21]

[0036]

[Chemical formula 22]

[0037]

[Chemical formula 23]

[0038]

[Chemical formula 24]

[0039]

[Chemical 25]

[0040]

[Chemical formula 26]

[0041]

[Chemical 27]

[0042]

[Chemical 28]

[0043]

[Chemical 29]

[0044]

[Chemical 30]

A copolymer having two or more kinds of repeating units may be used. You may use together two or more types of hydrophobic polymers. The weight average molecular weight of the hydrophobic polymer is preferably from 500 to 1,000,000, and from 1,000 to 5
It is more preferably 0,000, and most preferably 2,000 to 200,000. The hydrophobic polymer is preferably contained in the image forming layer in an amount of 5 to 90% by mass, more preferably 30 to 80% by mass.

[Hydrophilic Polymer] The hydrophilic polymer can function as a binder for fine particles in the image forming layer. The hydrophilic group of the hydrophilic polymer is preferably a hydroxyl, carboxyl, sulfo, amino or amide bond. Carboxyl and sulfo may be in a salt state. As the hydrophilic polymer, various natural or semi-synthetic polymers or synthetic polymers can be used.
Natural or semi-synthetic polymers include polysaccharides (eg gum arabic, starch derivatives, carboxymethylcellulose,
Its sodium salt, cellulose acetate, sodium alginate) or protein (eg casein, gelatin) can be used.

Examples of synthetic polymers having hydroxyl as a hydrophilic group include polyhydroxyethyl methacrylate, polyhydroxyethyl acrylate, polyhydroxypropyl methacrylate, polyhydroxypropyl acrylate, polyhydroxybutyl methacrylate, polyhydroxybutyl acrylate, polyallyl alcohol. , Polyvinyl alcohol and poly-N-methylol acrylamide. Examples of synthetic polymers having a carboxyl as a hydrophilic group include polymaleic acid, polyacrylic acid, polymethacrylic acid and salts thereof. Examples of synthetic polymers having other hydrophilic groups (eg, amino, multiple ether bonds, hydrophilic heterocyclic groups, amide bonds, sulfo) include polyethylene glycol, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide, methacryl. Amides and 2-acrylamido-2-methylpropanesulfonic acid and salts thereof are included.

A copolymer having two or more kinds of repeating units of the hydrophilic synthetic polymer may be used. A copolymer containing a repeating unit of a hydrophilic synthetic polymer and a repeating unit of a hydrophobic synthetic polymer (eg, polyvinyl acetate, polystyrene) may be used. Examples of copolymers include vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers and vinyl alcohol-vinyl acetate copolymers (partially saponified polymers of polyvinyl acetate). When a vinyl alcohol-vinyl acetate copolymer is synthesized by partial saponification of polyvinyl acetate, the saponification degree is preferably 60% by mass or more, and 80% by mass.
It is more preferable that the above is satisfied. You may use together two or more types of hydrophilic polymers. The hydrophilic polymer is preferably contained in the image forming layer in an amount of 2 to 40% by mass.
It is more preferable that the content is from 30 to 30 mass%.

[Photothermal Conversion Agent] The image forming layer preferably contains a photothermal conversion agent. The photothermal conversion agent is a substance having a function of absorbing light, converting light energy into heat energy, and generating heat. The photothermal conversion agent can be present inside the hydrophobic polymer particles. The photothermal conversion agent may be added outside the fine particles (in the hydrophilic binder). The wavelength of light absorbed by the photothermal conversion agent (maximum absorption wavelength) is 70
It is particularly preferably 0 nm or more (infrared light). Pigments, dyes or fine metal particles capable of absorbing infrared light can be preferably used as the photothermal conversion agent.

For infrared absorbing pigments, the Color Index (CI) Handbook, "Latest Pigment Handbook" (edited by Japan Pigment Technology Association, published in 1977), "Latest Pigment Application Technology" (C
MC Publishing, 1986, "Printing Ink Technology" (CM
C Publishing, published in 1984). A particularly preferred infrared absorbing pigment is carbon black. When the infrared absorbing pigment is added to the hydrophobic polymer or inside the fine particles of the hydrophobic polymer, the pigment can be subjected to a hydrophobizing (lipophilicizing) treatment. As the hydrophobic treatment, there is a method of coating the surface of the pigment with a lipophilic resin. When the infrared absorbing pigment is dispersed in the hydrophilic polymer, the pigment can be subjected to a hydrophilic treatment. As the hydrophilic treatment, a method of coating the surface of the pigment with a hydrophilic resin, a method of attaching a surfactant to the surface of the pigment, or a reactive substance (eg, silica sol,
A method of binding an alumina sol, a silane coupling agent, an epoxy compound, an isocyanate compound) to the pigment surface can be adopted. The particle size of the pigment is preferably 0.01 to 1 μm, more preferably 0.01 to 0.5 μm. When the pigment is dispersed in the hydrophilic polymer, a known dispersion technique used in ink production or toner production can be applied.

Regarding infrared absorbing dyes, "Dye Handbook" edited by the Society of Synthetic Organic Chemistry, published in 1970, "Chemical Industry" 19
May 1986 issue P. 45-51 "near infrared absorbing dye",
"Development of 90's functional dyes and market trends" Chapter 2 2.3
See (1990) CMC. Preferred infrared absorbing dyes are azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, and naphthoquinone dyes (JP-A-58-1127).
No. 93, No. 58-224793, No. 59-48187.
No. 59-73996, No. 60-52940, No. 60-63744), anthraquinone dye, phthalocyanine dye (JP-A-11-235883), squarylium dye (JP-A-58-112).
792), pyrylium dye (US Pat. No. 388)
1924, 4283475, JP-A-57 / 1982
-142645, 58-181051, 58-
220143, 59-41363, 59-84
No. 248, No. 59-84249, No. 59-14606.
No. 3, No. 59-146061, No. 5-13514
No. 5,197,702), carbonium dyes, quinoneimine dyes and methine dyes (JP-A-58).
-173696, 58-181690, 58-
194595).

For infrared absorbing dyes, US Pat.
It is also described in each specification of 6993 and 5156938 and JP-A-10-268512. A commercially available infrared absorbing dye (for example, Epolite III-178, Epolite III-130, Epolite III-125, manufactured by Eporin) may be used. Methine dyes are more preferred, and cyanine dyes (UK Patent 434875, US Patent 497
No. 3572, JP-A-58-125246,
59-84356, 59-216146, 6
0-78787). The cyanine dye is defined by the following formula. Bo-Le = Bs In the above formula, Bs is a basic nucleus; Bo is an onium body of a basic nucleus; and Le is a methine chain composed of an odd number of methines. In the case of infrared absorbing dyes,
Le is preferably a methine chain composed of 7 methines.

When the infrared absorbing dye is added to the hydrophilic polymer of the image forming layer, it is preferable to use a hydrophilic dye. Examples of hydrophilic infrared absorbing dyes are shown below.

[0054]

[Chemical 31]

[0055]

[Chemical 32]

[0056]

[Chemical 33]

[0057]

[Chemical 34]

[0058]

[Chemical 35]

[0059]

[Chemical 36]

When the infrared absorbing dye is added to the hydrophobic polymer fine particles, it is preferable to use a relatively hydrophobic dye. Examples of hydrophobic infrared absorbing dyes are shown below.

[0061]

[Chemical 37]

[0062]

[Chemical 38]

[0063]

[Chemical Formula 39]

[0064]

[Chemical 40]

Metals generally have a self-heating property.
Therefore, metals with absorption in the infrared, visible or ultraviolet region,
In particular, a metal having absorption in the infrared region has a light-heat conversion function. The metal forming the metal fine particles is preferably heat-sealed by light irradiation. Specifically, the melting point is 100.
It is preferably 0 ° C. or lower. As the metal constituting the metal fine particles, Si, Al, Ti, V, Cr, Mn, F
e, Co, Ni, Cu, Zn, Y, Zr, Mo, Ag,
Au, Pt, Pd, Rh, In, Sn, W, Te, P
b, Ge, Re, Sb and alloys thereof are preferred,
Re, Sb, Te, Ag, Au, Cu, Ge, Pb and Sn are more preferable, and Ag, Au, Cu, Sb and Ge are more preferable.
And Pb are more preferred, and Ag, Au and Cu are most preferred.

In the case of an alloy, a low melting point metal (eg Re, S
b, Te, Au, Ag, Cu, Ge, Pb, Sn),
Metals with high self-heating properties (eg Ti, Cr, Fe, Co,
Ni, W, Ge) can also be combined. It is also possible to use fine particles of a metal (eg, Ag, Pt, Pd) having a large light absorption and fine particles of another metal in combination. The metal fine particles are preferably dispersed in the hydrophilic polymer by subjecting the surface to hydrophilic treatment.
As the surface hydrophilic treatment, means such as surface treatment with a hydrophilic substance (eg, surfactant), surface chemical reaction with the hydrophilic substance, or formation of a hydrophilic polymer film can be adopted. A method such as providing a protective colloid hydrophilic polymer film can be used. A surface chemical reaction with a hydrophilic substance is preferred, and a surface silicate treatment is most preferred.
In the surface silicate treatment of iron fine particles, the surface can be made sufficiently hydrophilic by a method of immersing the iron fine particles in an aqueous sodium silicate (3%) solution at 70 ° C. for 30 seconds. Other metal fine particles can be subjected to surface silicate treatment in the same manner. Metal oxide particles or metal sulfide particles may be used instead of the metal particles. The particle size of the fine particles is preferably 10 μm or less, and is 0.0
It is more preferably from 03 to 5 μm, and 0.01
Most preferably from 3 to 3 μm.

[Other Optional Components of Image Forming Layer] A colorant may be added to the image forming layer for the purpose of distinguishing the image area and the non-image area after image formation. As the colorant, a dye or pigment having a large absorption in the visible region is used. Examples of colorants are Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 60.
3, Oil Black BY, Oil Black BS, Oil Black T-505 (above Orient Chemical Industry Co., Ltd.)
Made), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42)
535), ethyl violet, rhodamine B (CI1
45170B), Malachite Green (CI4200
0) and methylene blue (CI52015). Regarding the dyes used as the colorant, see JP-A-6-61.
It is described in JP-A-2-293247. Inorganic pigments such as titanium oxide can also be used as colorants. The addition amount of the colorant is preferably 0.01 to 10% by mass of the image forming layer.

The image forming layer contains a nonionic surfactant (Japanese Patent Laid-Open No. 62-25174) in order to enhance the stability of on-press development.
No. 0, JP-A-3-208514) or an amphoteric surfactant (JP-A-59-121044, JP-A-4-13149). Examples of nonionic surfactants include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride and polyoxyethylene nonyl phenyl ether. Examples of amphoteric surfactants include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-
Alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-
An N, N-betaine type surfactant (Amogen K, manufactured by Dai-ichi Kogyo Co., Ltd.) is included. The nonionic surfactant and amphoteric surfactant are contained in the image forming layer in an amount of 0.05 to 15% by mass.
It is preferably contained, and more preferably 0.1 to 5% by mass.

A plasticizer may be added to impart flexibility to the image forming layer. Examples of plasticizers include polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate and tetrahydrofurfuryl oleate. .

[Formation of image-forming layer] The image-forming layer is prepared by dissolving, dispersing or emulsifying each component in a suitable liquid medium to prepare a coating solution, coating the solution on a hydrophilic support, and drying it. It can be formed by removing the liquid medium.
Examples of the liquid medium used for the coating liquid include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2.
-Propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N,
N-dimethylformamide, tetramethylurea, N-
Includes methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyl lactone, toluene and water. Two or more kinds of liquids may be mixed and used. The total solid content concentration of the coating liquid is preferably 1 to 50% by mass.

A surfactant for improving the coating property can be added to the coating liquid. Fluorine-based surfactants (described in JP-A-62-170950) are particularly preferable. The addition amount of the surfactant is preferably 0.01 to 1% by mass with respect to the solid content of the coating liquid, and is 0.05
To 0.5 mass% is more preferable. The dry coating amount of the image forming layer is preferably 0.5 to 5.0 g / m ² .

[Hydrophilic support] As the hydrophilic support,
A metal plate, a plastic film or paper can be used. Specifically, a surface-treated aluminum plate,
Hydrophilic treated plastic film or water treated paper is preferred. More specifically, an anodized aluminum plate, a polyethylene terephthalate film provided with a hydrophilic layer, or a polyethylene-laminated paper is preferable.

Anodized aluminum plates are particularly preferred. The aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of a foreign element. Examples of foreign elements contained in aluminum alloys are:
Includes silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel and titanium. The ratio of the foreign element is preferably 10% by mass or less. You may use the aluminum plate for commercial printing plates. The thickness of the aluminum plate is preferably 0.05 to 0.6 mm, more preferably 0.1 to 0.4 mm, and most preferably 0.15 to 0.3 mm.

The surface of the aluminum plate is preferably roughened. The roughening treatment can be performed by a mechanical method, an electrochemical method or a chemical method. As the mechanical method, a ball polishing method, a brush polishing method, a blast polishing method or a buff polishing method can be adopted. As the electrochemical method, a method of performing alternating current or direct current in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid can be adopted. An electrolytic surface-roughening method using a mixed acid (described in JP-A-54-63902) can also be used. As a chemical method, a method of immersing an aluminum plate in a saturated aqueous solution of an aluminum salt of mineral acid (described in JP-A-54-31187) is suitable. The roughening treatment is preferably performed so that the center line average roughness (Ra) of the surface of the aluminum plate is 0.2 to 1.0 μm. The roughened aluminum plate is subjected to alkali etching treatment if necessary. An aqueous solution of potassium hydroxide or sodium hydroxide is generally used as the alkaline treatment liquid. After the alkali etching treatment, it is preferable to further perform a neutralization treatment.

The anodizing treatment of the aluminum plate is carried out in order to enhance the abrasion resistance of the support. As the electrolyte used for the anodizing treatment, various electrolytes forming a porous oxide film can be used. Generally, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used as the electrolyte. The anodizing treatment conditions are generally such that the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5.
To 60 A / dm ² , voltage of 1 to 100 V, and
The electrolysis time is in the range of 10 seconds to 5 minutes. The amount of oxide film formed by anodizing treatment is 1.0 to 5.0 g /
It is preferably m ² and is 1.5 to 4.0 g / m ^2.
Is more preferable.

[Water-soluble overcoat layer] A water-soluble overcoat layer may be provided on the image-forming layer to prevent the surface of the image-forming layer from being contaminated by a lipophilic substance. The water-soluble overcoat layer is composed of a material that can be easily removed during printing. For that purpose, it is preferable to form the water-soluble overcoat layer from a water-soluble organic polymer. Examples of water-soluble organic polymers include polyvinyl alcohol, polyvinyl acetate, polyacrylic acid, alkali metal salts or amine salts thereof, polymethacrylic acid, alkali metal salts or amine salts thereof, polyacrylamide, polyhydroxyethyl acrylate, polyvinyl. Pyrrolidone, polyvinyl methyl ether, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, its alkali metal salts or amine salts, gum arabic, cellulose ether (eg, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose), dextrin and Included are derivatives thereof (eg, white dextrin, enzyme-degraded etherified dextrin pullulan).
A copolymer having two or more kinds of repeating units of water-soluble organic polymer may be used. Examples of copolymers include vinyl alcohol-vinyl acetate copolymers (partially saponified polymers of polyvinyl acetate) and vinyl methyl ether-maleic anhydride copolymers. When a vinyl alcohol-vinyl acetate copolymer is synthesized by partial saponification of polyvinyl acetate, the saponification degree is preferably 65% by mass or more. You may use together two or more types of water-soluble organic polymers.

The above photothermal conversion agent may be added to the overcoat layer. The photothermal conversion agent added to the overcoat layer is preferably water-soluble. A nonionic surfactant (eg, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecyl ether) can be added to the coating solution for the overcoat layer. The coating amount of the overcoat layer is preferably 0.1 to 2.0 g / m ² .

[Imagewise heating step] The lithographic printing plate precursor is heated in an imagewise manner to form an image. Directly, the lithographic printing plate precursor can be imagewise heated by the thermal recording head.
In that case, the photothermal conversion agent is unnecessary. However, since the thermal recording head generally has a low image resolution, it is desirable to use a photothermal conversion agent to convert light energy by image exposure into heat energy. Generally, the exposure device used for image exposure has higher resolution than the thermal recording head. The exposure method includes exposure through an original (original) which is analog data and scanning exposure corresponding to original data (usually digital data). For exposure through the original, a xenon discharge lamp or an infrared lamp is used as a light source. If a high-power light source such as a xenon discharge lamp is used, short-time flash exposure is possible. Scanning exposure generally uses a laser, particularly an infrared laser. The wavelength of infrared rays is preferably 700 to 1200 nm. Infrared is a solid-state high-power infrared laser (for example, semiconductor laser, YA
G laser) is preferred.

When the image forming layer containing the photothermal conversion agent is scanned and exposed with a laser, the light energy of the laser is converted into thermal energy by the photothermal conversion agent. Then, in the heated portion (image portion) of the lithographic printing original plate, the hydrophobic polymer fine particles are fused to form a hydrophobic region attached to the hydrophilic support. On the other hand, there is no change in the hydrophobic polymer in the non-heated portion (non-image portion) of the lithographic printing original plate.

[Plate making and printing process] The planographic printing plate precursor image-wise heated can be developed to develop the planographic printing plate. Specifically, the hydrophobic polymer particles in the non-heated portion (non-image portion) can be removed with water or an aqueous solvent. However, even if the process of removing fine particles (development process) is not carried out, the planographic printing plate precursor that has been imagewise heated can be immediately mounted in the printing machine and printed in the usual procedure using ink and fountain solution. The plate making and printing can be continuously performed. That is, when the planographic printing original plate is mounted on a printing machine and the printing machine is operated, the image forming layer in the non-heated portion (non-image portion) can be removed by dampening water, ink, or rubbing. When a printing machine having a laser exposure device (described in Japanese Patent No. 2938398) is used, after the lithographic printing plate precursor is mounted on the printing machine cylinder, it is exposed by a laser mounted on the printing machine, and then dampening water or It is also possible to apply ink and perform on-press development (exposure to printing are continuously processed).

[0081]

EXAMPLES [Example 1] (Preparation of aluminum support) 99.5% or more of aluminum, Fe 0.30%, Si 0.10%, Ti
JIS A105 containing 0.02% and Cu 0.013%
The molten alloy No. 0 was subjected to a cleaning treatment and cast. For the cleaning treatment, degassing treatment was performed to remove unnecessary gas such as hydrogen in the molten metal, and ceramic tube filter treatment was performed. The casting method was a DC casting method. The solidified ingot having a plate thickness of 500 mm was chamfered by 10 mm from the surface, and homogenized at 550 ° C. for 10 hours so as not to coarsen the intermetallic compound. Then, hot rolling at 400 ° C,
After intermediate annealing at 500 ° C. for 60 seconds in a continuous annealing furnace, cold rolling was performed to obtain a rolled aluminum plate having a plate pressure of 0.30 mm. The center line average surface roughness Ra after cold rolling was controlled to 0.2 μm by controlling the roughness of the rolling roll. Then, a tension leveler was applied to improve the flatness.

Next, a surface treatment was carried out to obtain a lithographic printing plate support. First, in order to remove the rolling oil on the surface of the aluminum plate, degreasing treatment was performed with a 10 mass% sodium aluminate aqueous solution at 50 ° C. for 30 seconds, and then with a 30 mass% sulfuric acid aqueous solution.
Neutralization and smut removal treatment were carried out at 0 ° C. for 30 seconds.

Then, in order to improve the adhesion between the support and the image forming layer and to impart water retention to the non-image area, a so-called graining treatment was carried out to roughen the surface of the support. 1
An alternating solution with a current density of 20 A / dm ² and a duty ratio of 1: 1 by an indirect power supply cell while keeping an aqueous solution containing 45% by mass of nitric acid and 0.5% by mass of aluminum nitrate at 45 ° C. and flowing an aluminum web in the aqueous solution. Waveform on the anode side electricity quantity 24
Electrolytic graining was performed by applying 0 C / dm ² . Then, with a 10 mass% sodium aluminate aqueous solution at 50 ° C., 3
Etching treatment was performed for 0 seconds, neutralization with a 30 mass% sulfuric acid aqueous solution at 50 ° C. for 30 seconds, and smut removal treatment were performed.

Further, in order to improve abrasion resistance, chemical resistance and water retention, an oxide film was formed on the support by anodic oxidation. Anodized film of 2.5 g / m ² is obtained by using a 20% aqueous solution of sulfuric acid as an electrolyte at 35 ° C. and carrying out an electrolytic treatment with a direct current of 14 A / dm ² by an indirect power supply cell while carrying the aluminum web through the electrolyte. It was created. After that, a silicate treatment was performed in order to secure hydrophilicity as a non-image portion of the printing plate. The treatment was carried out by keeping a 1.5% by mass aqueous solution of No. 3 sodium silicate at 70 ° C. so that the contact time of the aluminum web was 15 seconds, and further washing with water. The amount of Si deposited is 10
It was mg / m ² . The center line surface roughness Ra of the support produced as described above was 0.25 μm.

(Formation of Undercoat Layer) Aluminum support surface
Apply the undercoat layer coating solution of the following composition on the surface,
It was dried for 30 seconds to form an undercoat layer. Undercoat dry
Dry coating amount is 10 g / m ²Met.

[0086] ────────────────────────────────────   Undercoat layer coating composition ────────────────────────────────────   β-alanine 0.10 g   40 g of methanol   Pure water 60g ────────────────────────────────────

(Synthesis of seed fine particle emulsion) 60 ml of ethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), distilled water 1
28 ml, potassium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.)
12 g of the mixture was placed in a 300 ml four-necked flask and stirred under a nitrogen stream at 70 ° C. for 10 minutes to synthesize an emulsion of seed particles.

(Synthesis of hydrophobic polymer fine particles) 200 m
50 ml of seed fine particle emulsion in a four-necked flask of l
1, styrene (manufactured by Tokyo Chemical Industry Co., Ltd.) 15 ml, distilled water 85 ml, and further potassium persulfate 0.075 g
Was added. The mixture was stirred at 70 ° C. for 6 hours under a nitrogen stream. The obtained emulsion was subjected to mesh filtration to synthesize hydrophobic polymer fine particles. When the particle shape was observed with a scanning electron microscope, it had a shape similar to that of Konpeito with protrusions on the surface. The average particle size of the fine particles was 0.4 μm.
The obtained emulsion was diluted with distilled water to adjust the solid content concentration to 10% by mass.

(Formation of image recording layer) An image recording layer coating liquid having the following composition was prepared.

[0090] ────────────────────────────────────   Composition of coating liquid for image recording layer ────────────────────────────────────   Emulsion of hydrophobic polymer particles 10g   Polyacrylic acid (mass average molecular weight: 250,000) 0.1 g   Photothermal conversion dye (S0306, manufactured by FEW Chemicals) 0.1 g   Fluorine-based surfactant (MegaFac F-171, Dainippon Ink and Chemicals, Inc.) Made) 0.05 g   Distilled water Add until the coating liquid concentration reaches 7% by mass ────────────────────────────────────

The coating solution for the image recording layer was applied onto the undercoat layer of the aluminum support using a rod bar, and the temperature was raised to 50 ° C.
And dried for 5 minutes to form an image recording layer. The mass of the image recording layer after drying was 0.9 g / m ² . In this way, a lithographic printing original plate was produced.

(Plate making, printing and evaluation) An image setter (Trendsetter 3244VFS, made by Creo) in which a water-cooled 40 W infrared semiconductor laser is mounted on the prepared planographic printing plate.
At 9V output, 210 rpm outer drum speed,
Plate energy of 500 mJ / m ² , and 2400 d
Image exposure was performed under the condition of pi resolution. Next, it was attached to a cylinder of a printing machine (Heidel SOR-M) without developing, and after supplying dampening water, ink was supplied.
Further, paper was supplied and printing was performed. As a result, a clear printed matter having no stain was obtained. Table 1 shows the number of prints required for the start of printing (on-press development) and the number of durable prints.

Comparative Example 1 (Synthesis of Hydrophobic Polymer Fine Particles) Sodium dodecyl sulfate (Wako Pure Chemical Industries, Ltd.) was placed in a 2-liter closed-neck flask.
3.12 g and 810 ml of distilled water were added, and the mixture was stirred at 50 ° C. for 10 minutes under a nitrogen stream. To the resulting solution was added a mixed solution of 0.462 g of potassium persulfate, 14 ml of distilled water and 3.5 ml of a 1N sodium hydrogen carbonate aqueous solution, and 104.15 g of styrene was added dropwise over 3 hours. After completion of dropping, 0.462 g of potassium persulfate, 14 ml of distilled water, 1
A mixed solution of 3.5 ml of an aqueous sodium hydrogencarbonate solution was added, and stirring was continued for 3 hours. The obtained reaction mixture was filtered with a glass filter to obtain a dispersion of hydrophobic polymer fine particles. When observing the particle shape with a scanning electron microscope,
The surface was a smooth spherical shape. The average particle diameter of the fine particles was 0.069 μm. The obtained emulsion was diluted with distilled water to adjust the solid content concentration to 10% by mass.

(Plate making, printing and evaluation) A lithographic printing original plate was prepared in the same manner as in Example 1 except that spherical spherical hydrophobic polymer particles were used. Using an image setter (Trendsetter3244VFS, made by Creo) equipped with a water-cooled 40W infrared semiconductor laser on the prepared lithographic printing plate.
9V output, 210 rpm outer drum speed, 500
Image exposure was performed under the conditions of a plate surface energy of mJ / m ² and a resolution of 2400 dpi. Next, without developing, it was attached to a cylinder of a printing machine (Heidel SOR-M), and after supplying dampening water, ink was supplied and then paper was further supplied to perform printing. As a result, scumming was found on the printed matter. Table 1 shows the number of prints required for the start of printing (on-press development) and the number of durable prints.

[0095]

[Table 1]                                 Table 1 ────────────────────────────────────   Lithographic printing original plate Polymer fine particles On-press development number of sheets Printable number of sheets ────────────────────────────────────     Example 1 There are irregularities on the surface 25 sheets 35,000 sheets     Comparative Example 1 No unevenness on the surface 85 sheets 25,000 sheets ────────────────────────────────────

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H025 AA12 AB03 AC08 AD01 AD03                       BH03 CB02 CB04 CB07 CB13                       CB14 CB15 CB41 CB43 CB47                       CC20 DA18 FA10                 2H096 AA07 AA08 BA16 BA20 CA20                       EA04 LA16                 2H114 AA04 AA24 BA02 BA10 DA41                       DA75 EA01 EA03 EA08 FA00                       GA01

Claims (2)

[Claims] 1. A lithographic printing plate precursor comprising an image forming layer containing a fine particle of a hydrophobic polymer and a hydrophilic polymer on a hydrophilic support, wherein the fine particle of the hydrophobic polymer has unevenness on the surface. A lithographic printing original plate having a certain shape. 2. The lithographic printing plate precursor as claimed in claim 1, wherein the fine particles of the hydrophobic polymer have an average particle diameter of 0.05 to 2 μm.