JP3019366B2 - Lithographic printing plate - Google Patents

Description

The present invention relates to a lithographic printing plate having a hydrophilic resin layer.
More specifically, it relates to a lithographic printing plate used as a PS plate.

[Prior Art] A lithographic printing plate generally comprises a hydrophilic non-image portion and a lipophilic image portion. Among them, the PS plate, known as a PS plate, polishes or anodizes the surface of a support metal plate (aluminum plate or zinc plate) to impart hydrophilicity, and makes this a hydrophilic non-image portion. It is manufactured by exposing and developing a photosensitive resin to form an lipophilic image area. In addition, as a printing plate for trial printing or a small number of printing plates for office use, a hydrophilic resin layer (hydrophilic non-image) is provided on water-resistant paper, synthetic paper, plastic film or metal foil as a support. Part), which is provided with an oleophilic image part (for example, a toner image by an electrophotographic method, a drawn image by a ballpoint pen or oil-based ink, a printed image by a typewriter, a printed image by thermal recording, etc.), and provided for printing. ing. A lithographic printing plate having such a conventional hydrophilic resin layer has insufficient hydrophilicity and water resistance, has poor coating strength, and has good adhesion to a support (particularly under high humidity). But it was weak. In Japanese Patent Publication No. 2-11440, PVM / MA is used as a hydrophilic resin in an organic solvent.
After once forming a water-insoluble aggregate of the copolymer (copolymer of lower alkyl vinyl ether and maleic anhydride),
There has been proposed a method of imparting hydrophilicity by treating with an aqueous alkali solution. Although this method improves the printing durability, it involves two steps of production, so that the number of steps is increased, and furthermore, it is necessary to treat with an alkaline aqueous solution, which is disadvantageous in that it is complicated.

[Problems to be Solved by the Invention] Accordingly, an object of the present invention is to eliminate these conventional disadvantages, to provide excellent hydrophilicity, water resistance, excellent coating film strength, excellent adhesion to a support, and manufacturing. Is to provide an easy lithographic printing plate.

[Means for Solving the Problems] As a result of intensive studies, the present inventors have found that the above-mentioned drawbacks can be solved by providing a specific hydrophilic resin layer on the hydrophilic resin layer, and have completed the present invention.

That is, the present invention provides a lithographic printing plate in which a hydrophilic resin layer and a lipophilic image portion are laminated in this order on a support,
The present invention provides a lithographic printing plate characterized in that the hydrophilic resin layer is a porous layer having a center line average roughness of 0.5 μm or less and an undulation index of 0.035 to 0.3 μm.

The present invention is a laminate in which a hydrophilic resin layer composed of a porous layer and a lipophilic image portion are laminated on a support in this order.

The porous layer referred to in the present invention has a layer structure having a large number of voids inside and on the surface of the layer. It is particularly preferable that the void is a so-called through-hole which leads to the outside in the porous layer from the viewpoint of hydrophilicity.

In the present invention, the peak pore size in the pore size distribution curve of the pores of the porous layer is 0.06 to 2.0 μm, preferably 0.08 to 1.0 μm.
m, more preferably 0.1 to 0.5 μm. When the peak pore size of the pore size distribution curve is less than 0.06 μm, the hydrophilicity is insufficient, and the peak pore size in the pore size distribution curve is 2.0 μm.
If it exceeds m, the surface smoothness will be reduced, and there will be a drawback that uneven coating of the lipophilic image area will occur.

Further, the pore area ratio is preferably in the range of 20 to 85%, preferably 30 to 75%, more preferably 35 to 65%. When the pore area ratio is less than 20%, the hydrophilicity tends to decrease. When it exceeds 85%, it is easy to take a form in which holes are partially connected, and bleeding and sharpness tend to decrease.

The pores, when observed from the surface of the porous layer, are independent of each other, and have a roundness r (= b / a, a: major axis diameter of the hole, b: minor axis diameter of the hole) of 1 to 1. A value of 5 is particularly preferred because of good hydrophilicity. This roundness is an average value of 1000 or more measurement points and is usually determined by an image analyzer.

Further, it is desirable that the expansion of the pore size distribution in the pore size distribution curve is small, that is, it is desirable to have a sharp pore size distribution. It is desirable to be within.

Next, the center line average roughness of the porous layer surface in the present invention is
It is 0.5 μm or less. It is preferably 0.3 μm or less, more preferably 0.1 μm or less, since hydrophilicity is good and pinhole-shaped coating of the lipophilic image layer is reduced.

In the present invention, in order to further enhance the hydrophilicity, those having a surface undulation are preferable. For this purpose, the porous layer preferably satisfies the following conditions. That is, the surface of the porous layer is at least 0.2 μm in height, preferably 0.3 μm.
m, more preferably 0.4 μm or more swell 5/40
μm or more, preferably 7/40 μm or more, more preferably 10/40 μm or more. 0.2μ height
If the number of undulations of m or more is less than 5/40 μm or more, the water absorption speed is low, the printing speed is low, and the workability is reduced.

In the present invention, the waviness index of the porous layer surface is 0.
035 to 0.3 μm, preferably 0.045 to 0.2 μm, more preferably 0.055 to 0.13 μm. If the waviness index is less than 0.035 μm, the hydrophilicity is poor, which is not preferable. On the other hand, when the undulation index exceeds 0.3 μm, undesired pinhole-shaped coating in the hydrophilic image area is undesirably increased.

The porous layer of the present invention is obtained by mixing a water-dispersible polymer and a specific colloidal silica in a specific range, and applying the mixture.
It is obtained by drying. Here, the water-dispersible polymer may be an aqueous dispersion of various polymers, and specific examples include an acrylic polymer,
Aqueous dispersions such as ester-based polymers, urethane-based polymers, olefin-based polymers, vinylidene chloride-based polymers, epoxy-based polymers, amide-based polymers, and modified products and copolymers thereof can be used. Use of an acrylic polymer or urethane polymer is preferred because the pore size distribution is sharp and the pore area is large, and an acrylic polymer is particularly preferred in view of the mechanical stability of the coating film and the strength of the coating film.

The polymer used in the present invention is preferably dispersed in water and has a particle shape. When it does not have a particle shape, that is, a polymer dissolved in a water-soluble polymer, an organic solvent, or the like, cannot be made porous. The particles are preferably dispersed in primary particles, but need not necessarily be dispersed in primary particles, and may include secondary particles.

The acrylic polymer suitable as the porous forming polymer of the present invention is at least 40 mol% or more of an acrylic monomer and / or a methacrylic monomer and an ester forming monomer thereof, and an acrylic monomer having various functional groups such as acrylic acid and methacrylic acid. , Alkyl acrylate, alkyl methacrylate (the alkyl group is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group,
Ethylhexyl, lauryl, stearyl, cyclohexyl, phenyl, benzyl, etc.), and 2-
Hydroxy-containing monomers such as hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N- Amide group-containing monomers such as methylol methacrylamide, N, N-dimethylolacrylamide, N-methoxymethyl methacrylamide, N-phenylacrylamide, N, N-
Amino group-containing monomers such as diethylaminoethyl methacrylate and N, N-diethylaminoethyl acrylate; epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; salts of acrylic acid and methacrylic acid (sodium salt, potassium salt, ammonium salt, etc.) These can be used in combination with other monomers. Other types of monomers include, for example, epoxy group-containing monomers such as acrylic glycidyl ether, and sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (sodium salt, potassium salt, ammonium salt, etc.) include the salts thereof. Monomers, crotonic acid, itaconic acid, maleic acid, fumaric acid,
And monomers containing a carboxyl group or a salt thereof such as salts thereof, monomers containing an acid anhydride such as maleic anhydride, itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether And vinyltrisalkoxysilane, alkylmaleic acid monoester, alkylfumaric acid monoester, acrylonitrile, methacrylonitrile, alkylitaconic acid monoester, vinyl chloride, vinyl acetate, and vinylidene chloride.

The above-mentioned monomers are copolymerized using one kind or two or more kinds.

In order to cause undulation in the porous layer of the present invention in the colloidal silica mixed with 20 to 90 parts by weight of the water dispersion of the water-dispersible polymer, the following silica is suitable. For example, a porous membrane having a long chain structure in which spherical colloidal silica is connected in a bead shape and a product in which the linked silica is branched can be used to obtain a porous film having a waviness structure on the surface. The above-mentioned colloidal silica is obtained by connecting primary particles of spherical silica with a metal ion having a valence of 2 or more and binding between particles, and at least 3 or more, preferably 5 or more, and more preferably 7 or more are connected. And also includes those in which beads connected in a bead shape are branched.

Further, it may be a composite or mixed particle of colloidal silica and other inorganic particles, for example, alumina, ceria, titania, or the like, or may be a particle in which these are interposed. The metal ion to be interposed is preferably a divalent or higher metal ion. For example, Ca ²⁺ , Zn ²⁺ , Mg ²⁺ , Ba ²⁺ , Al ³⁺ , Ti
⁴⁺ and so on. In particular, when Ca ²⁺ is used, it is suitable for producing colloidal silica linked and branched in a bead shape. The primary particles of colloidal silica are 5-100 nm,
When the thickness is preferably 7 nm to 50 nm, more preferably 8 nm to 30 nm, it is preferable in terms of increasing the pore forming property and the pore area ratio.
Further, the undulation of the porous layer is manifested when the silica particles are connected and branched in a rosary, and the larger the number of primary particles of the connected silica is, the more preferable, but usually 3 or more.
It is desirable that the number be less than 100, preferably 5 or more and less than 50, and more preferably 7 or more and less than 30. If the number is two or less, undulation is insufficiently expressed, and if the number is 100 or more, beads linked and / or branched in a bead form tend to be thickened and water dispersibility tends to be poor. The content of rosary-linked and / or branched silica particles in the porous coating film is 3 to 80% by weight, preferably 10 to 70% by weight, and more preferably 20 to 60% by weight. 3% by weight content
If it is less than 4, there is no porosity formation and no undulation is exhibited, so that the hydrophilicity tends to decrease. When the content exceeds 80% by weight, the porous formability is reduced, the pore size is reduced, the pore area ratio is reduced, the hydrophilicity is reduced, and the strength of the coating film is poor. Disadvantages, such as easy generation of dust.

Porosity changes depending on the ratio of the average particle diameter of the water-dispersible polymer and the colloidal silica, and the average particle diameter of the colloidal silica needs to be smaller than the average particle diameter of the water-dispersible polymer. Can not do. In the case of the colloidal silica connected in a bead shape, the length of the connected particles observed in an electron microscope in the minor axis direction is defined as the particle diameter, and the average value of 100 measured lengths is defined as the average particle diameter.

The average particle diameter ratio of the water-dispersible polymer / colloidal silica is 2/1 to 1000/1, preferably 5/1 to 500/1, and more preferably 10/1 to 200/1. It is particularly preferable in view of the formability of the polymer.

In particular an average particle size ratio in relation to an average particle size of colloidal silica and (a ₁₎ and the average particle size of the water-dispersible polymer (a ₂₎ is in the above range, and complete one surface water-dispersible polymer particles when the minimum number particles of colloidal silica necessary for covering was _{α (α-2π (a 1} + a 2) 2/3 1/2 · a 1 2) , the per average particles of the water-dispersible polymer, 0.3 α
When the compounding ratio is in the range of from 10 to 10α, preferably in the range of from 0.5α to 6α, and more preferably in the range of from 0.7α to 3α, the effect of the present invention is more remarkably exhibited.

Known additives within a range that does not impair the effects of the present invention in the porous layer of the present invention, for example, inorganic or organic fine particles, plasticizer, lubricant, surfactant, antistatic agent, crosslinking agent, crosslinking catalyst, A heat resistance agent, a weather resistance agent, and the like may be added. In particular, the addition of an antistatic agent is preferable in terms of eliminating the effects of static electricity in the manufacturing process and preventing double feeding when producing a cut sheet-like material, and the addition of a crosslinking agent or a crosslinking catalyst is preferred for coating a porous layer. It is more preferable because toughness, water resistance, chemical resistance and heat resistance are improved.

The method of application is a known method, for example, gravure coat,
Any method such as reverse coating, bar coating, kiss coating, and die coating can be used.

Although the thickness of the porous layer is not particularly limited, it is usually 0.1 to 50 μm.
m, preferably 0.5-30 μm, more preferably 1-20 μm
m is good. If the thickness is too thin, the hydrophilicity is insufficient, and if it is too thick, the strength of the coating film tends to be insufficient.

Examples of the support of the present invention include paper, synthetic paper, plastic film, metal foil, a composite material of metal foil and paper or plastic film, various metal plates (iron plate, aluminum plate, zinc plate, etc.). Among these, a plastic film is preferable from the viewpoint of moldability, lightness, handleability, mechanical properties, price, and the like. As the plastic film in the present invention, a known plastic film can be used as appropriate. Typical examples are polyester film, polycarbonate film, triacetylloin film, cellophane film, polyamide film, polyimide film, polyphenylene sulfide film, polyetherimide film, polyethersulfone film, aromatic polyamide film, polysulfone film, polyolefin film, etc. Can be mentioned. However, it is preferable to use a polyester film, a polycarbonate film, and a polyphenylene sulfide film in view of mechanical properties, thermal properties, price, and the like, and a polyester film is particularly preferable.

The polyester film is a generic name of a polymer film having an ester bond as a main bonding chain. Particularly preferred polyesters are polyethylene terephthalate, polyethylene 2,6-naphthalate, and polyethylene α, β-bis (2-chlorophenoxy). ) Ethane 4,4'-
Examples thereof include dicarboxylate and polybutylene terephthalate, and among these, polyethylene terephthalate is most preferable in consideration of quality, economy, and the like. Therefore, hereinafter, polyethylene terephthalate will be described as a representative of polyester.

In the present invention, polyethylene terephthalate (hereinafter referred to as PET)
The term "abbreviated as") means that 80 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more has ethylene terephthalate as a repeating unit, but within this limited range, an acid component and / or a glycol component. May be replaced by a third component as described below.

-Acid component- Isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-
Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, p-β-hydroxyethoxybenzoic acid,
Adipic acid, adelineic acid, sebacic acid, hexahydroterephthalic acid, hexanehydroisophthalic acid, ε-oxycaproic acid, trimellitic acid, trimesic acid, pyromellitic acid, α, β-bisphenoxyethane-4,4′-dicarboxylic acid Acid, α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid, 5-sodium sulfoisophthalic acid and the like.

-Glycol component- Propylene glycol, butylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2-bis (4
-Β-hydroxyethoxyphenyl) propane, bis (4-β-hydroxyethoxyphenyl) sulfone, diethylene glycol, triethylene glycol, pentaerythritol, trimethylolpropane, polyethylene glycol and the like.

In addition, known additives in the PET, such as heat stabilizers, oxidation stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, and release agents. Molding agents, antistatic agents, nucleating agents and the like may be blended.
The ultimate concentration of PET as described above (measured in orthochlorophenol at 25 ° C) is between 0.40 and 1.20, preferably between 0.
Those in the range of 50 to 0.80, more preferably 0.55 to 0.75 dl / g are suitable for the present invention.

The PET film can be used in any of unoriented, uniaxial, and biaxial orientations, but biaxially oriented PET film is preferable because of its excellent mechanical strength. The biaxially oriented PET film is formed by stretching a non-stretched PET sheet or film about 2.5 to 5 times each in the so-called biaxial directions of the longitudinal direction and the width direction. Indicates a pattern.

If the PET film has been subjected to surface treatment by a known method, that is, a film subjected to corona discharge treatment (in air, in nitrogen, in carbon dioxide gas, etc.) or easy adhesion treatment, adhesion to the porous layer, water resistance It can be more preferably used because the solvent resistance and the like are improved. A variety of well-known methods can be used for the easy-adhesion treatment.Acrylic-based, urethane-based, polyester-based or the like or a blend of these in the film manufacturing process, or those coated with various easy-adhesives such as those grafted, Alternatively, a film obtained by applying the above-mentioned various adhesives to a film after uniaxial or biaxial stretching can be suitably used.

The base film may be a transparent film or a colored film, but a film having a whiteness of 80% or more by adding inorganic particles such as TiO ₂ and CaCO ₃ is particularly preferable in terms of beautifulness as a printing plate. .

The thickness of this film is not particularly limited, but is usually 1 μm.
It is desirably at least 1 mm, preferably at least 10 μm and at most 900 μm, more preferably at least 30 μm and at most 800 μm. The center line average roughness of this film is 0.001-0.3μ
m, preferably 0.005 to 0.2 μm, more preferably 0.01 to
Preferably, it is 0.1 μm.

By imparting an antistatic property to at least one surface of a laminate obtained by laminating a hydrophilic resin layer composed of a porous layer on the support of the present invention, or eliminating the influence of static electricity in the production process, or a cut sheet-like material Double feed during production can be prevented. The antistatic treatment may be performed on either the porous layer or the other surface of the film provided with the porous layer. The antistatic treatment preferably has a surface resistivity of 10 ⁸ to 10 ¹² Ω / □, and these may be mixed with a known antistatic agent in the porous layer within a range that does not impair the effects of the present invention. Can be obtained by coating on a surface on which a porous layer is not provided. In particular, when the treated layer containing 5 to 40% by weight of sulfonated polystyrene is used as the undercoat layer, the adhesion to the porous layer is also excellent, which is more preferable.

In the present invention, a hydrophilic resin layer composed of the porous layer is formed on the support, and thereafter, a lipophilic image area is formed by a usual method to obtain a target lithographic printing plate.

Examples of the method for forming the lipophilic image area include a method of forming a toner image by an electrophotographic method, a method of forming a drawn image with a ballpoint pen or oil-based ink and a print image by a typewriter, and a method of photoengraving using a photosensitive resin (process). : Coating, exposure, and development). In the case of the photoengraving method, both negative type and positive type photosensitive resins can be used as the photosensitive resin. Negative types include those obtained by mixing a diazo resin and an alkali-soluble hydrophobic resin, those using p-diazoquinone, and a photopolymerizable photopolymer type obtained by mixing a vinyl monomer and a photopolymerization initiator in an alkali-soluble hydrophobic resin. And a dimerized photopolymer having a photocrosslinkable side chain. A generally known outer type photosensitive resin can also be used. As the positive type photosensitive resin, a combination of orthonaphthoquinone azide and a phenol resin can be used.

In this way, a lithographic printing plate having a hydrophilic resin layer composed of the porous layer of the present invention can be obtained. In order to provide these for printing, a dampening solution is applied to the plate surface and printed on the lipophilic image area. Ink may be applied.

[Effects of the Invention] In the present invention, since a porous hydrophilic resin layer and a lipophilic image area are laminated in this order on a support, the support is excellent in hydrophilicity, water resistance, coating film strength, and the like. Excellent adhesion of
An easy-to-manufacture and inexpensive lithographic printing plate was obtained.

Therefore, the planographic printing plate of the present invention can be used not only as a normal PS plate, but also as a small number printing plate for office use, a printing plate for trial printing, and the like.

Next, a method for measuring characteristic values and a method for evaluating effects according to the present invention will be described.

(1) Pore size distribution curve Mark the pores on the electron microscope surface photograph taken at a magnification of 10,000 times, and perform image processing using a QUant: mat-720 type image analyzer (manufactured by Image Analyzing Computer Co., Ltd.). The area between the minimum pore diameter and the maximum pore diameter when converted to a perfect circle was divided in units of 10 μm, and the number of holes in each division was measured. From this measured value, a pore size distribution curve was drawn with the vertical axis being the number of pores per unit area and the horizontal axis being the pore size, and the pore size at the peak was determined.

(2) Pore area ratio The area occupied by pores per unit area was calculated from the above pore diameter distribution curve by the following equation.

ai: Average pore diameter in each division when the pore diameter in the measurement area is divided in 10 mμ units ni: Number of holes in each division when the pore diameter in the measurement area is divided in 10 mμ units A: Measurement area ( 3) Center line average roughness Measured at a cutoff of 0.25 mm according to JIS B 0601-1976.

(4) Height of undulation, number of undulations, and undulation index Using a scanning electron microscope ESM-3200 (manufactured by Elionix Inc.) equipped with a cross-section measuring device PMS-1, the surface irregularities observed at a magnification of 3000 times were measured. 0 above the surface roughness curve.
When the valleys adjacent to the peaks of 2 μm or more were connected by a straight line, the number of the peaks in the measurement length of 40 μm was measured, and the number of undulations having a undulation height of 0.2 μm or more was determined.

The center line average roughness (Ra ₁₀ ) at a cut-off of ₁₀ μm and the center line average roughness (Ra ₁ ) at a cut-off of 1 μm were obtained from the surface roughness curve, and the undulation index was calculated by the following equation.

The undulation index (μm) = Ra ₁₀ −Ra ₁ The number of undulations and the undulation index were average values of 50 measurement points.

(5) Hydrophilicity Printing was carried out using a fountain solution in a lithographic printing press, 1000 copies were printed, and judged according to the following criteria.

 ：: No abnormality in printed matter and printing plate.

 X: The printed matter has background stains.

(6) Clarity and bleeding of the printed surface The surface of the printed surface printed by the above method was visually observed, and the presence or absence of a transfer defect (a portion where ink was not transferred) was determined based on the following criteria. In addition, the blur of the ink was determined by observing the boundary between the printed portion and the non-printed portion with a 100-fold optical microscope, and the presence or absence of the blur at the boundary surface was determined based on the following criteria.

 転 写 No transfer bleeding or bleeding was observed.

○ There is no transfer, but the surface gloss is slightly reduced.
Slight bleeding is observed.

Δ 1 to 5 transfer bleeds, which can be visually judged, are present in 10 cm ^2, and the boundaries are not clear.

× There are countless spots in the transfer, and bleeding is large.

(7) Coating strength The surface of the porous layer was subjected to a cross cut of 1 mm square, and a 90 ° peel test was carried out using a cellophane adhesive tape manufactured by Nichiban Co., Ltd., to determine the residual rate of the porous layer.

Residual rate 80% or more: [○] Residual rate less than 80%: [×] (8) Average particle size COULTER N4 submicron particle analyzer (Co., Ltd.)
The particle diameter was determined by a light scattering method using a laser, and the average value of 10 measurements was used. When measurement was not possible by this method, it was determined from a 200,000 magnification electron micrograph.

(9) Average number of particles The average number of particles contained in 1 ml of an aqueous dispersion of V wt% was determined from the following equation based on the average particle system a determined as described above and the specific gravity ρ of the particles determined by the density gradient method.

[Examples] Next, embodiments of the present invention will be described based on examples.

Example 1 Biaxially stretched PET having a center line average roughness of 0.03 μm and a thickness of 250 μm
The following coating material was applied to one side of the film so that the thickness after drying was 5 μm, and dried at 130 ° C. for 2 minutes to form a hydrophilic resin layer composed of a porous layer. The surface coated with the PET film was subjected to corona discharge treatment in air.

[Coating material composition] 70 parts by weight (solid content weight ratio) of an acrylic polymer emulsion (methyl methacrylate / ethyl acrylate / acrylic acid (60/35/5% by weight) copolymer) having an average particle diameter of 0.2 μm and a branched bead 30 parts by weight (solid content weight ratio) of colloidal silica (Snowtex UP (manufactured by Nissan Chemical Industries, Ltd., average particle size 0.015 μm)) was diluted with water to obtain a 30% by weight coating material.

Next, a positive photosensitive liquid was applied thereon and dried to obtain a positive PS plate. A positive image was applied to the PS plate, exposed and baked, and then developed to produce a lithographic printing plate. Using this lithographic printing plate, printing was performed using a fountain solution on a lithographic printing press.

Table 1 summarizes the characteristics of the lithographic printing plate. As is clear from Table 1, the hydrophilic resin layer composed of a porous layer has a peak pore diameter, a pore area ratio, and a center line average roughness in a pore diameter distribution curve within the range of the present invention. ,
Both sharpness and bleeding exhibited excellent characteristics, no abnormalities of the plate were observed, and good printed matter was obtained.

Examples 2 to 4 In the coating material of Example 1, the average particle diameter of the acrylic polymer emulsion and the branched beaded colloidal silica,
A lithographic printing plate having the properties shown in Table 1 was prepared in the same manner except that the solid content was changed as follows. All exhibited excellent characteristics.

Example 5 A lithographic printing plate was prepared in the same manner as in Example 1, except that a negative photosensitive solution was used instead of the positive photosensitive solution. Using this lithographic printing plate, printing was performed using a fountain solution on a lithographic printing press. Excellent characteristics were exhibited as in Example 1.

Example 6 A support having a hydrophilic resin layer comprising a porous layer obtained in Example 1 was set in an electrophotographic copying machine, a required original drawing was copied on the hydrophilic layer, heat-fixed, and A hydrophilic image was obtained. Even when offset printing was performed using this printing plate in the same manner, no abnormality was observed in the plate, and a good printed matter was obtained.

Continuation of the front page (56) References JP-A-3-173692 (JP, A) JP-A-2-225088 (JP, A) Japanese Utility Model Showa 50-85301 (JP, U) (58) Fields surveyed (Int .Cl. ⁷ , DB name) B41N 1/14

Claims (3)

(57) [Claims] 1. A lithographic printing plate comprising a support and a hydrophilic resin layer and a lipophilic image area laminated in this order, wherein the hydrophilic resin layer has a center line average roughness of 0.5 μm or less, and a swell index. Is a porous layer having a thickness of 0.035 to 0.3 μm. 2. The porous layer according to claim 1, wherein a peak pore size in a pore size distribution curve is 0.06 to 2.0 μm.
Lithographic printing plate described in. 3. The lithographic printing plate according to claim 1, wherein the pore area ratio of the porous layer is 20 to 85%.