JP2001138652A - Lithographic printing original plate and printing method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithographic printing original plate, in which no developing treatment is necessary, the highly sensitive and high resolution image formation is possible, without developing abrasion and which is excellent in scratch resistance, scumming properties in non-image part, especially scumming restoring properties and scumming properties in blanket, plate wear and post-exposure visibility of picture, and a printing method using thereof and, in addition, the lithographic printing original plate, which is excellent in the dispersion stability of a coating liquid and in which no crack develops in a coated film. SOLUTION: (1) This lithographic printing original plate is produced by including inorganic particles such as fine necklace-like colloidal silica, anatase- type titanium oxide particles or the like, a photothermal conversion material and a thermally meltable stock on a base material. (2) Further, crystalline cellulose is included in (1) the above original plate. (3) Furthermore, the lithographic printing original plate is produced by laminating a photothermal coversion material-containing layer, a layer including the thermally meltable stock and a layer including 60% in mass or more of the inorganic particles in the order named.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel lithographic printing original plate which does not require development after image exposure, and a printing method using the lithographic printing original plate.

[0002]

2. Description of the Related Art In recent years, with the development of digital image processing technology using a semiconductor laser and a computer, a PS plate is directly scanned and exposed with a semiconductor laser from digital image data formed by a computer to produce a lithographic printing plate ( (CTP) is attracting attention. With the digitization of such print data, there is a need for a lithographic printing original plate for CTP which is inexpensive, easy to handle, and has the same printability as the PS plate. Particularly in recent years, various types of CTP using infrared laser recording have been proposed. So-called dry CTP that does not require special development processing
(Including development on a printing press) has received attention. Such techniques include, for example, the following.

[0003] Japanese Patent Application Laid-Open No. 8-507727 discloses a heat-sensitive material having a recording layer containing a photothermal conversion material and a hardened hydrophilic surface layer containing a photothermal conversion material on a support having an ink-receiving surface. A material and a method for forming an image by using a mode recording material to remove an upper layer above the recording layer by laser with a laser are disclosed.

Japanese Patent Application Laid-Open No. 6-186750 discloses a first type having a different affinity for ink or an ink adhesion preventing liquid.
A method and apparatus for forming an image by scanning a plate having a layer and a second layer with an infrared laser and removing one or more of these layers by ablation is disclosed.

Japanese Patent Application Laid-Open No. 6-199064 discloses that an upper layer first layer which is an infrared absorbing layer and a second layer which is a lower layer are provided on a substrate or an upper first layer and an infrared layer which is a lower layer. A lithographic printing plate material for laser recording, comprising a second layer which is an absorbing layer, wherein the one layer and the two layers exhibit different affinities for ink or an ink adhesion preventing liquid and form an image by ablation. Have been.

Japanese Patent Application Laid-Open No. Hei 7-314934 discloses an upper layer that is not ablated, a thin metal layer of titanium or a titanium alloy to be ablated, and a substrate, wherein the upper layer and the substrate are resistant to ink or an ink-insoluble fluid. And a method for forming an image by ablation with a printing member for laser recording having different affinities.

JP-A-10-58636 discloses that a laser-sensitive hydrophilic swelling layer (preferably containing a color pigment or a black dye) is provided on a substrate, and the hydrophilic swelling layer is ablated by laser irradiation. Discloses a lithographic printing plate precursor that forms an ink-coated image by removing the lithographic printing plate precursor.

JP-A-10-244773 discloses a photosensitive lithographic printing plate which does not require a laser direct dampening solution and has a photosensitive layer containing a near-infrared absorber and a silicone rubber layer in this order on a substrate. Discloses a technique for producing a lithographic printing plate by ablation by laser exposure of a photosensitive lithographic printing plate in which titanium black as a near-infrared absorber is dispersed in a photosensitive layer with a specific particle size.

All of these are printing plate materials (original plates) of a type in which an image portion or a non-image portion is formed by ablating the surface layer, and have problems such as low resolution and poor dot quality. In addition, there is a concern that the ablated surface layer may contaminate the inside of the exposure apparatus, and it is necessary to remove ablated residues remaining on the printing plate surface by some means (wiping, rinsing with a dedicated device, or the like). There still remain problems such as not being a dry treatment.

To compensate for these drawbacks, Japanese Patent Publication No. 8-27
JP-A No. 01-307787 discloses a lithographic printing plate precursor in which a heat-sensitive recording layer mainly containing an inorganic pigment, an oil-soluble thermoplastic resin and a heat-fusible substance is provided on a water-resistant support. Is characterized in that in a lithographic printing plate provided with a thermosensitive recording layer mainly composed of an inorganic pigment, a thermoplastic resin and a heat-fusible substance on a hydrophilic support, the HLB value of the heat-fusible substance is 4 or less. By using a heat-sensitive lithographic printing plate precursor, printing can be performed by causing a difference in ink adhesion / hydrophilicity or ink adhesion / ink repulsion between a laser-exposed portion and an unexposed portion without causing ablation. Enable,
So-called switchable lithographic printing plate materials have been proposed.

Further, Japanese Patent Application Laid-Open No. H11-105234,
Japanese Patent Application Laid-Open No. H11-109610 proposes a lithographic printing plate precursor that utilizes the photocatalysis of anatase-type titanium oxide, is photoexcited by irradiation with ultraviolet light, and utilizes the fact that the surface changes to hydrophilic. . That is, JP-A-11-
No. 105234 describes a technique in which a printing master having a thin layer mainly composed of titanium oxide or zinc oxide on its surface is irradiated with active light to make the entire surface hydrophilic, and drawing is performed on this surface in a heat mode. A printing method of performing printing by forming a printing surface in which an image area accepts ink, and a printing method of repeatedly removing and printing ink used on a printing plate from a used printing plate as a printing original plate. The technique described in JP-A-11-109610 has a layer containing at least anatase-type titanium oxide fine particles and a binder resin on a water-resistant support, and uses electromagnetic radiation in the ultraviolet region on the surface of the layer. By performing imagewise exposure, the exposed portion of the surface of the layer becomes a non-image portion that retains dampening water during printing and repels ink, and the unexposed portion becomes an image portion that receives ink. A printing plate precursor.

Generally, it is difficult for such a switchable printing plate to improve the ink density difference between the image portion and the non-image portion, that is, to improve the S / N.
Improving the ink coverage of the image area results in stains on the non-image area, and when focusing on reducing the stain on the non-image area, it is difficult to obtain ink coverage on the image area. There is a problem that scratches and stains may occur if scratched for any reason.In addition, compared to the conventional PS plate, if the non-image part is stained for some reason, the printing condition is adjusted and normal Satisfactory performance (P), such as a problem of poor suitability for dirt recovery and a problem of poor blanket dirt (also called blanket piling) in which ink is deposited on non-image areas on the blanket.
Printability equivalent to that of the S-plate). In addition, when the plate is touched, sweat, sebum and the like adhere to the plate, and the printed portion is stained, and the touched portion is stained like a fingerprint, which is called a "fingerprint stain".

The lithographic printing plate precursor as described above includes:
When a method of applying a dispersion of an inorganic pigment (inorganic particles) on a substrate is employed in the production method, phase separation or consolidation occurs if the dispersion stability of the inorganic pigment (inorganic particles) in a coating solution is poor. However, when a lithographic printing plate is used, there are also problems such as deterioration in image reproducibility and generation of stains.

[0014]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a high-sensitivity, high-resolution, high-sensitivity, high-resolution image forming apparatus which does not require a special developing process and does not cause ablation. It is possible to form a lithographic printing plate with excellent scratch stains and other scratches, excellent non-image stains, especially excellent stain recovery, fingerprint stains and blanket stains, and excellent printing durability. Another object of the present invention is to provide a lithographic printing original plate having excellent visibility after exposure and a printing method using the lithographic printing original plate. Another object of the present invention is to provide the lithographic printing plate precursor having excellent dispersion stability of a coating solution and having no cracks in a coating film.

[0015]

The constitution of the present invention for solving the above-mentioned problems is as follows.

(1) A lithographic printing plate precursor comprising a base material containing inorganic particles, a material having a light-to-heat conversion function, and a material which is melted by heat.

(2) The lithographic printing plate precursor as described in (1) above, wherein necklace-shaped colloidal silica is contained as inorganic particles.

(3) Necklace-shaped colloidal silica is
50 to 50 nm spherical colloidal silica
The lithographic printing plate precursor as described in (2) above, wherein the lithographic printing plate precursor is colloidal silica bonded to a length of 400 nm.

(4) The lithographic printing plate precursor as described in (1) above, further comprising anatase type titanium oxide fine particles as inorganic particles.

(5) The lithographic printing plate precursor as described in any one of (1) to (4) above, further comprising crystalline cellulose.

(6) [A] a layer containing a material having a light-to-heat conversion function, [B] a layer containing a material that melts by heat, and [C] a layer containing 60% by mass or more of inorganic particles. A lithographic printing original plate characterized by the following.

(7) The lithographic printing plate precursor as described in (6) above, wherein at least one of the layer [A], the layer [B] and the layer [C] contains necklace-shaped colloidal silica.

(8) Necklace-shaped colloidal silica is 50 to 4 spherical colloidal silica having a particle diameter of 10 to 50 nm.
The lithographic printing plate precursor as described in (7) above, wherein the lithographic printing plate precursor is colloidal silica bonded to a length of 00 nm.

(9) The above (6), (7) or (8), wherein at least one of the layer [A], the layer [B] and the layer [C] contains fine particles of anatase type titanium oxide. The lithographic printing original plate described in.

(10) The method according to any one of the above (6) to (9), wherein at least one of the layer [A], the layer [B] and the layer [C] contains crystalline cellulose. Lithographic printing plate.

(11) The lithographic printing original plate as described in any one of (1) to (10) above, wherein the photothermal conversion material is a conductive metal oxide.

(12) Any one of the above (6) to (11), wherein the layer (A) is a layer containing a material having a photothermal conversion function on the surface of the core material particles and particles coated with inorganic particles. Or the lithographic printing original plate according to item 1.

(13) The core material particles contained in the [A] layer are:
The lithographic printing plate precursor as described in (12) above, wherein the lithographic printing plate has an average particle diameter of 0.1 to 10 μm, and contains hydrophilic particles having an average particle diameter larger than the core material particles and 20 μm or less.

(14) The material which is melted by heat has a melting point of 4.
Any one of the above (1) to (13), wherein the viscosity is in the range of 0 to 150 ° C. and at 140 ° C. is 1 × 10 ^{−3 to} 100 × 10 ⁻³ Pa · s. The lithographic printing original plate described in.

(15) The above (6) to (B), wherein the layer [B] contains porous inorganic particles having a diameter larger than the average particle diameter of the material to be melted by heat and having a diameter of 3 μm or less.
(14) The lithographic printing original plate as described in any one of the above (14).

(16) The above (1) to (1), wherein at least one of the inorganic particles is a porous inorganic particle.
5) The lithographic printing original plate as described in any one of 5) above.

(17) The porous inorganic particles are porous silica,
The lithographic printing plate precursor as described in (15) or (16) above, which is a porous aluminosilicate or zeolite.

(18) The above (6) to (1), wherein the [C] layer contains a material having a light-to-heat conversion function.
7) The lithographic printing original plate according to any one of the above items.

(19) The coating amount of the [C] layer is 0.1-8.
(6) to (g), wherein the content is in the range of 0 g / m ^2.
(18) The lithographic printing original plate as described in any one of the above (18).

(20) The lithographic printing plate described above, wherein the average surface roughness Ra is in the range of 200 to 800 nm, and the ten-point average roughness Rz is in the range of 2000 to 7000 nm. The lithographic printing original plate according to any one of 1) to (19).

(21) A lithographic printing original plate comprising a lithographic printing original plate according to any one of the above (1) to (20), on which a protective layer containing a water-soluble resin is provided. .

(22) The water-soluble resin is at least one selected from starches, gelatins, polyvinyl alcohol, modified polyvinyl alcohol and cellulose derivatives.
The lithographic printing original plate as described in (21) above, which is a seed.

(23) After imagewise exposing the lithographic printing plate precursor according to any one of the above (1) to (22), the imagewise exposed portion receives the ink and is not exposed, without performing development processing. A printing method, wherein printing is performed by a part receiving a dampening solution.

(24) A lithographic printing plate precursor containing the fine particles of anatase type titanium oxide according to any one of the above (9) to (23) is exposed to ultraviolet light without image development after exposure and image development. A printing method wherein an image-exposed portion receives ink and an unexposed portion receives fountain solution to perform printing.

In the lithographic printing plate precursor of the present invention, a material having a light-to-heat conversion function generates heat in a portion exposed by a laser or the like,
A material that is melted by heat is melted to form an ink-inkable image portion. Therefore, it is possible to print completely without processing after exposure.

Further, by utilizing the change of anatase type titanium oxide to hydrophilicity due to photoexcitation, dirtiness, especially background dirt, is improved. In addition, the dispersion stability of the coating solution can be obtained by containing crystalline cellulose. Also, by containing necklace-shaped colloidal silica, a difference in density occurs between the exposed portion of the laser and the unexposed portion, whereby visible image quality is obtained and plate inspection is excellent. In addition, the necklace-shaped colloidal silica also improves cracks (cracks) in the coating film.

The lithographic printing plate precursor according to the present invention is the above [A],
In the case of the three-layer configuration of [B] and [C], the laser exposure section causes the [A] layer to generate heat, thereby melting the hot-melt material in the [B] layer, and the hot-melt material becomes [ C] so as to form an ink-inkable image portion. Therefore, it is not necessary to ablate the layer [C], and it is possible to print without exposure after exposure.

The layer [A] contains a material having a light-to-heat conversion function and particles coated with inorganic particles on the surface of the core material, and the layer [B] has a smaller average particle diameter than the average particle diameter of the heat-fusible substance. By containing large hydrophilic particles, high strength and excellent fog due to scratches and the like are obtained.

Further, when the layer [C] contains 60% by mass or more of inorganic particles, soiling property, in particular, background soiling and blanket soiling can be suppressed.

Further, the surface roughness of the lithographic printing original plate is adjusted so that the average surface roughness Ra is in the range of 200 to 800 nm and the 10-point average roughness Rz is in the range of 2000 to 7000 nm. The balance between the ink and the fountain solution can be easily obtained, and the printability such as recovery from soiling is excellent. Further, by providing a protective layer containing a water-soluble resin on the lithographic printing plate, it is excellent in fingerprint stains, and also excellent in stain recovery properties and scratch resistance.

Hereinafter, the present invention will be described in detail. As the inorganic particles used in the present invention, general metal oxide particles such as silica, alumina, aluminosilicate, zeolite, titania, and zirconia can be used.

The amount of the inorganic particles contained in the layer [C] is 6
It is preferably at least 0% by mass, more preferably at least 80% by mass. If it is less than 60% by mass, the hydrophilicity is reduced, and stains occur during printing, which is a problem. The content in the layer containing the inorganic particles, the material having a light-to-heat conversion function (hereinafter, referred to as “light-to-heat conversion material”) and the material that is melted by heat (hereinafter, referred to as “hot-melt material”) is preferably 30 to 90% by mass, -80 mass% is more preferable.

The inorganic particles are preferred to be porous particles (preferably having an apparent specific gravity of 1.5 or less) because of the problem of sedimentation when added and dispersed in the paint. If the degree of the porosity is too high, the strength of the particles decreases, and the wear resistance deteriorates. Therefore, the oil absorption of the particles is 40 to 100 m.
It is preferably in the range of 1/100 g. The shape is preferably close to a sphere.

Among the inorganic particles, anatase type titanium oxide, porous aluminosilicate (for example, zeolite particles) and porous silica (preferably necklace-shaped colloidal silica) are preferable.

In order to effectively utilize the effects of the fine particles, at least 10 to 80% by mass, more preferably 10 to 50% by mass of anatase type titanium oxide fine particles are contained as a layer component, so that the surface of the particles has the desired hydrophilicity. Sex can be obtained. These particles are commercially available as a powder or a titania sol dispersion. Examples include Ishihara Sangyo Co., Ltd., Titanium Industry Co., Ltd., Sakai Chemical Co., Ltd., Nippon Aerosil Co., Ltd., Nissan Chemical Industry Co., Ltd.
Further, the anatase type titanium oxide particles provided in the present invention,
Other metal elements or oxides thereof may be contained. The inclusion includes coating, supporting, or doping on the surface and / or inside of the particles.

Zeolite is a crystalline aluminosilicate, and is a porous material having pores of a regular three-dimensional network structure having a pore diameter of 0.3 to 1 nm. The general formula combining natural and synthetic zeolites is as follows:

(MI, MII _1/2 ) _m (Al _m Si _n O _{2 (m + n)} ). XH ₂ O where MI and MII are exchangeable cations, and
Are Li ⁺ , Na ⁺ , K ⁺ , Tl ⁺ , Me ₄ N ⁺ (TMA), E
t ₄ N ⁺ (TEA), Pr ₄ N ⁺ (TPA), C ₇ H
₁₅ N ₂ ⁺ , C ₈ H ₁₆ N ⁺ , and MII is Ca ²⁺ , Mg ²⁺ ,
Ba ²⁺ , Sr ²⁺ , C ₈ H ₁₈ N ₂ ^{2+ and the} like. Also, n ≧ m
And the value of m / n, that is, the Al / Si ratio is 1 or less. The higher the Al / Si ratio, the greater the amount of exchangeable cations included, and hence the higher the polarity, and therefore the higher the hydrophilicity. A preferred Al / Si ratio is 0.4 to 1.0,
More preferably, it is 0.8 to 1.0.

The zeolite particles used in the present invention are preferably synthetic zeolites having a stable Al / Si ratio and a relatively sharp particle size distribution. For example, zeolite A: Na ₁₂ (Al ₁₂ Si _{12) O48} ) 27
H ₂ O; Al / Si ratio 1.0, zeolite X: Na ₈₆
(Al ₈₆ Si ₁₀₆ O ₃₈₄ ) · 264H ₂ O; Al / Si ratio 0.811, zeolite Y: Na ₅₆ (Al ₅₆ Si ₁₃₆₎
O ₃₈₄ ) · 250H ₂ O; Al / Si ratio of 0.412.

By containing highly hydrophilic porous particles having an Al / Si ratio of 0.4 to 1.0, the hydrophilicity of the [B] layer itself is greatly improved, and it is hardly stained at the time of printing, and the water volume latitude is also reduced. Become wider. In addition, stains on fingerprint traces are greatly reduced. When the Al / Si ratio is less than 0.4, the hydrophilicity is insufficient, and the effect of improving the performance is reduced. The particle size in the state of being contained in the layer [B] (including the case of passing through the dispersion crushing step) is preferably substantially 1 μm or less, more preferably 0.5 μm or less. When coarse particles are present, porous and steep protrusions are formed on the surface of the layer, and ink is likely to remain around the protrusions, thus deteriorating non-image area stains. Porous particles are 30% of the entire coating layer.
To 95% by mass, preferably 40 to 80% by mass.
Is more preferable.

The above-mentioned porous inorganic particles can be used by being dispersed and crushed in advance, or crushed in the process of being dispersed simultaneously with other materials of the coating layer. Similarly, the layered mineral particles can be used after being crushed / peeled in advance or crushed / peeled in the process of being dispersed simultaneously with other materials of the coating layer.

The dispersion and crushing or delamination of particles can be broadly classified into a dry type and a wet type. Dry dispersion crushing does not require a drying step, so the process is relatively simple.
For delamination up to a layer thickness of less than nm, the wet method is usually more advantageous.

Examples of the dry dispersing and crushing apparatus include a high-speed rotary impact shearing mill (for example, an annular type innomizer), an air-flow crusher (jet mill), a roll mill,
A dry medium stirring mill (for example, a ball mill), a compression shearing type pulverizer (for example, an ang mill) and the like can be used. As a wet dispersion and crushing apparatus, a wet medium stirring mill (for example, a ball mill or an aquamizer), a high-speed rotating shear friction type mill (for example, a colloid mill), or the like can be used.

The particle size of the porous particles after dispersion and crushing is preferably substantially 1 μm or less, more preferably 0.5 μm or less. When coarse particles remain, they may be removed by classification or filtration.

The layered mineral particles after dispersion and crushing have a mean particle size (maximum particle length) of 20 μm or less and an average aspect ratio (maximum particle length / particle thickness) of 20 or more. The average particle diameter is preferably 10 μm or less, and the average aspect ratio is more preferably 50 or more. Further, a swelling step described later may be performed before the dispersion crushing of the layered mineral particles.

Particularly when wet dispersion is performed, it is preferable to prepare a coating solution without drying both the porous particles and the layered mineral particles. This is because re-aggregation may occur when the particles subjected to dispersion crushing or dispersion separation are dried. Concentration or dilution may be performed to adjust the solid concentration of the coating solution.

Further, in the above-mentioned dispersion crushing or dispersion layer peeling step, a surface treatment can be performed on the particles by adding a surface treatment agent. Further, in the dispersion crushing or dispersion layer peeling step, other components to be added to the coating solution may be added and dispersed simultaneously, or after the dispersion crushing or dispersion layer peeling step, other components may be added to the coating solution. May be added and dispersed again. In the dispersion crushing or dispersion layer peeling step, it is considered that a mechanochemical reaction is occurring simultaneously, and when dispersed simultaneously with other components added to the coating solution, an effect of improving strength when a coating film is obtained is obtained. There are cases.

The colloidal silica is a general term for an aqueous dispersion of very small spherical silica particles, and the necklace-shaped colloidal silica used in the present invention has a particle diameter of 10%.
50 to 400 nm spherical colloidal silica
Means "pearl necklace-shaped" colloidal silica bonded to the length of The pearl necklace shape (that is, pearl necklace shape) is said to be because the image of a state in which colloidal silica silica particles are connected and connected has a shape like a pearl necklace, as shown in FIG. While the conventional colloidal silica 1 is a dispersion system of spherical silica particles 2, as shown in FIG. 1, the necklace-shaped colloidal silica 3 is a dispersion system in which spherical silica particles 4 are dispersed in a continuous state. . The bonding between the silica particles constituting the necklace-shaped colloidal silica is caused by the dehydration bonding of -SiOH groups present on the surface of the silica particles -Si-
It is estimated to be O-Si-. Specific examples of the necklace-shaped colloidal silica include the “Snowtex-PS” series manufactured by Nissan Chemical Industries, Ltd.

The necklace-shaped colloidal silica has voids inside the coating film due to the structure. Accordingly, the "material which is melted by heat" can be melted and flow during image exposure, and can be easily leached to the surface, thereby improving the sensitivity. Although the reason is not so small, the visibility after exposure is also good. Probably, it is presumed that the “material that melts due to heat” oozes out on the surface, and the internal voids become higher, resulting in a density difference, which can be recognized as the visual image quality of the image. In addition, necklace-shaped colloidal silica can be added for the purpose of preventing cracks in the coating layer.

The content of the necklace-shaped colloidal silica is preferably from 10 to 80% by mass, more preferably from 30 to 60% by mass. If the amount is less than 10% by mass, the above-mentioned voids cannot be sufficiently obtained, and the sensitivity decreases. If the amount is more than 80% by mass, the number of voids increases, but the strength of the coating film is insufficient, and printing durability and stains due to scratches become problems.

In addition to the above, examples of the inorganic particles include the following. a. Metal oxide fine particles having an average particle diameter of 100 nm or less As metal oxide fine particles having an average particle diameter of 100 nm or less,
Examples include colloidal silica, alumina sol, titania sol, and sols of other metal oxides. The form of the metal oxide fine particles may be spherical, needle-like, feather-like, or any other form. The average particle diameter is preferably from 3 to 100 nm, and several kinds of metal oxide fine particles having different average particle diameters can be used in combination. Further, a surface treatment may be performed on the particle surface.

The metal oxide fine particles can be used as a binder by utilizing the film forming property. Compared to the use of an organic binder, the decrease in hydrophilicity is less, and thus it is suitable for use in the [B] layer. Of these, colloidal silica is particularly preferred because of its high film-forming properties even under relatively low-temperature drying conditions. In the case of colloidal silica, the smaller the particle size, the stronger the bonding force. When the particle diameter is larger than 100 nm, the bonding force is greatly reduced, and when used as a binder, the strength is insufficient.

When these metal oxide fine particles are used together with the porous silica particles, it is preferable to use them in a state where the fine particles themselves have a positive charge. For example, it is preferable to use alumina sol or acidic colloidal silica. . When these metal oxide fine particles are used together with porous aluminosilicate particles and / or zeolite particles, it is preferable to use them in a state where the fine particles themselves have a negative charge.For example, it is preferable to use alkali colloidal silica. preferable. When used together with the porous silica particles and the porous aluminosilicate particles and / or zeolite particles, it is preferable to use, for example, colloidal silica whose surface is treated with aluminum to provide stability in a wide pH range.

B. Inorganic particles with a new Mohs hardness of 5 or more Non-porous metal oxide particles with high hardness (new Mohs hardness of 5 or more) (silica, alumina, titania, zirconia, iron oxide, chromium oxide, etc.) to improve wear resistance ), Metal carbide particles (such as silicon carbide), boron nitride particles, and diamond particles.

As an indicator of non-porosity, the specific surface area is preferably 50 m ² / g or less, more preferably 10 m ² / g or less in terms of BET value. The average particle size is preferably 0.1 to 5 μm, and 0.2 to 3 μm.
μm is more preferred.

The content of the inorganic particles having a new Mohs hardness of 5 or more is preferably 1 to 50% by mass, more preferably 3 to 30% by mass of the whole coating layer.

C. Layered mineral particles Layered mineral particles can also be used for the purpose of preventing cracks in the coating layer. Layered mineral particles include kaolinite, halloysite, chrysotile, talc, smectite (montmorillonite, beidellite, hectorite,
Savonite, etc.), vermiculite, mica (mica),
Examples include clay minerals such as chlorite, hydrotalcite, and layered polysilicates (such as kanemite, macatite, aialite, magadiite, and kenyaite).

In particular, it is considered that the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The preferred charge density is 0.25 or more, more preferably 0.6 or more. As a layered mineral having such a charge density, smectite (charge density of 0.25
~ 0.6; negative charge), vermiculite (charge density 0.
6-0.9; negative charge), mica (~ 1; negative charge), hydrotalcite (~ 2; positive charge), magadiite (~
1; negative charge).

In particular, synthetic fluorine mica is preferable because it can be obtained in a stable quality such as a particle size. In addition, among synthetic fluorine mica, those which are swellable are preferable, and those which are free swell are more preferable.

Further, the above layered mineral intercalation compound (pillar crystal, etc.), one subjected to ion exchange treatment, surface treatment (silane coupling agent, etc.)
Can be used.

The size of the layered mineral particles is such that the average particle size (maximum length of the particles) is 20 μm or less in the state of being contained in the [B] layer (including the case where the particles have undergone the swelling step and the dispersion peeling step). In addition, it is preferable to be a thin layer having an average aspect ratio (maximum particle length / particle thickness) of 20 or more, an average particle diameter of 10 μm or less, and an average aspect ratio of 50 or less.
More preferably, it is the above. When the particle size is in the above range, continuity and flexibility in the planar direction, which are characteristics of the thin layered particles, are imparted to the coating film, and a tough coating film that is less likely to crack can be obtained. If the particle diameter is out of the above range, undesired increase in surface roughness may cause deterioration of non-image areas and blanket stains. When the aspect ratio is less than the above range, the flexibility becomes insufficient, and the effect of suppressing cracks in the coating film is reduced. The content of the layered mineral particles is preferably 1 to 50% by mass of the entire coating layer, and more preferably 3 to 30% by mass.

Swellable synthetic fluorine mica which is free swelling swells sufficiently only by mixing and stirring with water, and has an average thickness of 1%.
The dispersion liquid is divided into thin layers of 0 nm or less to obtain a stable dispersion.

The Mg-vermiculite becomes swellable by performing, for example, the following ion exchange treatment.

Mg-vermiculite + lithium citrate aq. → Li-vermiculite + magnesium citrate aq. .

Further, by mechanically dispersing and delaminating the Li-vermiculite which has been limitedly swollen by the osmotic pressure, it is possible to divide it into a thin layer having an average thickness of 10 nm or less.

As the light-to-heat conversion material, a material capable of converting infrared light into heat, that is, a material having absorption in the infrared region can be used. One of them is a general infrared absorbing dye (cyanine, phthalocyanine). However,
When a water-soluble dye is added to a porous layer (a layer containing porous inorganic particles), the water resistance and durability of the layer decrease. When a water-insoluble dye is added, it is difficult to uniformly disperse the solid dye in the aqueous dispersion liquid in the form of ultrafine particles, and the dye-to-aggregate dye has poor photothermal conversion efficiency. Also, it causes stains during printing.

Of the photothermal conversion materials having absorption in the infrared region, it is preferable that the material itself is a material having conductivity. It may be a semiconductor. For unknown reasons,
When a light-to-heat conversion material having conductivity was added to the layer, the adhesion of the ink to the non-image area was remarkably improved, especially in printing using dampening water, and the soil recovery was greatly improved. . Examples of such a material include metal, conductive carbon, graphite, and conductive metal oxide. Of these, conductive metal oxides are particularly preferred.

As the metal, any metal can be used as long as the particle size is preferably 0.5 μm or less, more preferably 100 nm or less, and still more preferably 50 nm or less. The shape may be any of a spherical shape, a flake shape, and a needle shape. In particular, colloidal metal fine particles (Ag, Au, etc.) are preferable.

It is particularly preferable to use furnace black or acetylene black as the conductive carbon. The particle size (d ₅₀ ) is preferably 100 nm or less.
It is more preferable that the diameter be equal to or less than nm. The conductivity index represented by the following formula is preferably 30 or more, and 5
More preferably, it is 0 or more.

Conductivity index = ｛specific surface area (m ² / g) × D
BP oil absorption (ml / 100 g)｝ ^1/2 / (1 + volatile content) As graphite, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.

Examples of the conductive (or semiconductor) metal oxide include ZnO, Al-doped ZnO, SnO ₂ , S
b-doped SnO ₂ (ATO), Sn-doped I
n ₂ O ₃ (ITO), TiO ₂ , TiO ₂ reduced TiO
(Titanium oxynitride, generally titanium black). In addition, the core material (BaS) is made of these metal oxides.
O ₄ , TiO ₂ , 9Al ₂ O ₃ .2B ₂ O, K ₂ O.nTiO
₂ ) can also be used. Their particle size is 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less.

Among the above conductive metal oxides, titanium black, ATO and ITO are preferred. In particular, ATO and ITO which do not substantially color (present colorless or white) when dispersed in a coating film and are used as a transparent conductive film are preferable. Colorless or white heartwood is made of ATO or ITO
A material coated with a can also be preferably used. This is because the color turbidity of the ink does not occur even when the coating film wears little by little on the printing press.

It is important that these light-to-heat conversion materials are uniformly dispersed in the coating film, and it is preferable to form a coating solution by itself or mechanically dispersing simultaneously with any of the other coating composition components. . At that time, a dispersant may be used.

The content of the photothermal conversion material is 2 to 40
% By mass, more preferably 5 to 30% by mass.
When the content is less than 2% by mass, the sensitivity becomes low, and when the content is 40% by mass or more, ablation tends to occur with exposure energy in a practical region.

The lithographic printing plate precursor according to the present invention comprises the layer [A],
When the layer [B] and the layer [C] are provided, it is preferable that the layer [A] contains particles coated on the core material surface with a photothermal conversion material and inorganic particles from the viewpoint of soil recovery and blanket soiling.

The content of the particles in which the core material surface is coated with the photothermal conversion material and the inorganic particles is preferably in the range of 20 to 90% by mass as the ratio of the whole layer of the particles including the core material and the coating material.
More preferably, it is in the range of 40 to 80% by mass. The coating amount of the core material particles (including the light-to-heat conversion material, the inorganic particles and other binders and additives when used) is preferably 5 to 100% by mass based on the total mass of the coated particles,
More preferably, it is 10 to 60% by mass.

In the particle coating by the dry method described later, the ratio of the area of the photothermal conversion material particles fixed to the core material particle surface and the surface area calculated by considering the core material as a sphere is defined as the coating ratio. The ratio is preferably 50% or more on average, and more preferably 80% or more.

As the core material particles, any of the following organic particles and inorganic particles can be used.
These particles can be used as they are,
It can also be used after surface treatment with a sol of a coupling agent or metal oxide.

The average particle size of the primary particles is preferably 0.1 to 10 μm, more preferably 0.5 to 10 μm.
６6 μm. Two or more types of particles having different average particle sizes can be used in combination.

As the organic particles, nylon, PMMA,
General crosslinked resin particles such as silicone, Teflon, polyethylene, and polystyrene can be used. Also, Ca alginate particles can be used. Alternatively, particles coated with a core material may be generated by using a so-called microcapsule forming method. As the particles made of an inorganic material, general metal oxide particles such as silica, alumina, aluminosilicate, titania, and zirconia can be used. However, since sedimentation when added and dispersed in the paint becomes a problem, it is preferable that the porous particles have an apparent specific gravity of 1.5 or less. If the degree of porosity is too high, the strength of the particles decreases and the wear resistance deteriorates. Therefore, the oil absorption of the particles is preferably in the range of 40 to 100 ml / 100 g. The shape is preferably close to a sphere.

As the light-to-heat conversion material for coating, the above-mentioned function of converting infrared rays into heat, that is, a material having absorption in the infrared part can be used.

As the inorganic particles for coating, general metal oxide particles such as silica, alumina, aluminosilicate, titania and zirconia can be used.
The inorganic particles used are smaller than the core particles. For example, porous inorganic particles or the like may be crushed in advance to use particles having a smaller particle diameter than the core material. In particular,
1.0 μm or less, preferably 0.1 μm or less, more preferably 0.05 μm or less.

The coating can be performed by using a general method for forming microcapsules. For example, various methods described in Tamotsu Kondo and Masazumi Koishi in "Microcapsules-Methods for Production, Properties, and Applications" (1985, Sankyo Publishing Co., Ltd.) or described in cited documents can be used. However, it is not limited to this. Among them, the following methods are suitable.

Spray drying method A dispersion of the photothermal conversion material to be used is prepared. The binder and the solvent are appropriately selected. In the dispersion step, a usual kneading and dispersion method can be used. High efficiency due to the dispersion of the coating only,
In addition, there is an advantage that a material different from a binder and a solvent required as a layer exhibiting a desired function can be used. For example, there is a method in which coated particles to be added to a solvent-based coating layer are prepared from an aqueous dispersion. The core material particles are uniformly suspended in the dispersion and spray-dried to obtain coated particles. This step can be performed using, for example, a commonly used spray dry granulation apparatus. The concentration of the light-to-heat conversion material dispersion is preferably 0.1 to 10% by mass, and the suspension concentration of the core material particles is preferably 10 to 50% by mass.

Dry Method This is a method in which the core material particles collide with the coating material and the coating material is fixed to the surface of the core material by electrostatic force or physical penetration. In this method, it is preferable that the core material particles themselves are not crushed by a physical impact, and in particular, nylon, PMMA,
It is suitable when organic particles such as silicone and Teflon are used as a core material. The coating can be performed using a dispersing machine such as a sand grinder or a ball mill. In addition, it is preferable to use a device such as a hybridizer manufactured by Nara Machinery Co., Ltd., which is a high-speed air impact method that does not use dispersed beads, because the coated particles can be easily collected. In the case of using dispersed beads (glass, ceramic, or the like), coating is performed, for example, at a rotation speed of 300 to 2000 rpm for a processing time of 5 to 60 minutes. When a hybridizer is used, coating is performed at a peripheral speed of 50 to 150 m / sec for a processing time of 1 to 20 minutes.

The average particle size is larger than the core material particles, and
As the hydrophilic particles having a particle size of 0 μm or less, the same inorganic particles and organic particles as those of the core material particles, or those obtained by subjecting the particle surfaces to hydrophilic treatment are preferably used. Among them, inorganic particles are preferred. In addition, since sedimentation when added and dispersed in the coating material for forming a layer poses a problem, porous particles having an apparent specific gravity of 1.5 or less are preferable. If the degree of porosity is too high, the strength of the particles is reduced and the abrasion resistance is deteriorated. Therefore, the oil absorption of the particles is preferably in the range of 40 to 100 ml / 100 g. The shape is preferably close to a sphere. The average particle size of the particles is larger than the core material particles and preferably 20 μm or less, more preferably twice or less the core material particles. When the particle size is smaller than the core material particles, the strength of the coating film surface is reduced, and the problem of stains due to scratches and the like and the printing durability are reduced. 20μ
If it is larger than m, particles will easily fall off at the time of scratching, and the stain resistance will also deteriorate.

The hot melt used in the present invention is preferably water repellent. Further, the melting point is preferably from 40 ° C to 150 ° C, and more preferably from 60 ° C to 100 ° C. When the melting point is less than 40 ° C., stability with time becomes a problem, and stains are easily generated. Also,
When the melting point is higher than 150 ° C., the sensitivity decreases. Further, the viscosity at 140 ° C. is preferably 1 to 100 cps, more preferably 1 to 30 cps. When the viscosity at 140 ° C. is 1 cps or less, there is a problem of storage stability as in the case of the melting point, and 100 cps.
If it is higher than this, the sensitivity decreases.

Preferred heat-melting materials include paraffin, polyolefin, microwax, fatty acid wax,
Oxidized polyethylene wax and the like. These have a molecular weight of about 800 to 10,000, and are usually obtained as low-density and high-density polyethylene by high-pressure and low-pressure polymerization, and by thermal decomposition of a high-molecular-weight polyolefin. Further, these waxes may be oxidized to facilitate emulsification, and polar groups such as a hydroxyl group, an ester group, a carboxyl group, an aldehyde group and a peroxide group may be introduced. In addition, these waxes can be used in combination in order to lower the softening point or improve workability. The latter include stearoamide, linolenamide, laurylamide, myristeramide, hardened bovine fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide,
Examples thereof include coconut fatty acid amides, methylolated products of these fatty acid amides, methylene bissteraloamide, ethylene bissteraloamide, and the like, and combinations thereof are also possible. Further, a cumarone-indene resin, a rosin-modified phenol resin, a terpene-modified phenol resin, a xylene resin, a ketone resin, an acrylic resin, an ionomer, and a copolymer of these resins can also be used.

The shape of the hot-melt material has a particle size of 0.05.
The particle size is preferably from 10 to 10 μm, and the particle size is more preferably from 0.1 to 5 μm. When the thickness is less than 0.05 μm, the strength of the layer [A] decreases, and the printing durability as a printing plate decreases. When the thickness is more than 10 μm, the resolution decreases.

The content of the hot-melt material is preferably from 10 to 70% by mass, more preferably from 30 to 50% by mass of the layer containing the hot-melt material. If the amount is less than 10% by mass, the sensitivity is lowered and an image cannot be obtained. On the other hand, if it exceeds 70% by mass, the strength of the coating film becomes insufficient, and stains due to scratches and the like and the printing durability decrease.

The composition of the particulate hot-melt material may vary continuously between the inside and the surface layer, or may be covered with a different material. As a coating method, a known microcapsule forming method, a sol-gel method, an electrostatic adsorption method, or the like can be used.

In the present invention, crystalline cellulose is necessary for this purpose because it stabilizes a coating solution for coating a layer containing at least one of inorganic particles, a light-to-heat conversion material and a hot-melt material. It is contained in the coating solution. The content of crystalline cellulose is 0.01 to 10% by mass, more preferably 0.1 to 5% by mass of the coating solution. If the amount is less than 0.01% by mass, the effect as the dispersion stability of the coating liquid cannot be obtained. On the other hand, if it is more than 10% by mass, the viscosity of the coating solution increases and the handleability deteriorates, so that the stainability deteriorates and the coating film strength decreases.

Crystalline cellulose is obtained by depolymerizing a cellulosic material, followed by mechanical shearing with a mill such as a bead mill, or an emulsifier such as a high-pressure homogenizer, and wet-milling to obtain an aqueous suspension of fine cellulose. Obtained in liquid form. In the case of fine cellulose in an aqueous suspension, the colloid fraction, which is a practical property for measuring colloidal cellulose, is preferably 50% or more. Japanese Patent Application Nos. 5-244968, 5-244968, and 6-11793 disclose manufacturing examples thereof. Further, a water suspension of fine cellulose obtained by grinding and a water-soluble gum and / or a hydrophilic substance are mixed and dispersed to form a homogeneous dispersion, which is then dried to form a water-dispersible fine cellulose composite. It may be. The fine cellulose composite is dispersed in the fine cellulose again by stirring in water. The colloid fraction of the fine cellulose composite is improved by forming a composite of fine cellulose and a water-soluble gum or the like, and is preferably 65% or more. An example of the production method is disclosed in Japanese Patent Application No. 4-259396.
And Japanese Patent Application No. 5-318322.

The crystalline cellulose can be obtained as a commercial product as a powder or as an aqueous dispersion. For example, "Avicel" and "Theolus" of Asahi Kasei Gaku Kogyo KK are mentioned.

The lithographic printing plate precursor of the present invention comprises a light-to-heat conversion material,
These materials may be present as one or a plurality of layers on the base material so that the hot-melt material, the inorganic particles, and the like have the functions described above.

The lithographic printing plate precursor according to the present invention may comprise, as necessary, the following components: "organic binder or organic additive";"inorganic or organic-inorganic hybrid binder by sol-gel method". A layer is formed by applying a mixture of these components on a base material.

The above “organic binder or organic additive”
As the organic binder in the above, those having hydrophilicity are preferable. For example, caseins, soy proteins, proteins such as synthetic proteins, chitins, starches, gelatins,
Alginate, polyvinyl alcohol, silyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, methyl cellulose, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, polyethylene oxide, polypropylene oxide, polyethylene glycol, polyvinyl ether, styrene-butadiene copolymer, methyl methacrylate- Examples include a conjugated diene polymer latex of a butadiene copolymer, an acrylic polymer latex, a vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone.

Further, a cationic resin may be contained.
Examples of the cationic resin include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine or derivatives thereof, acrylic resins having a tertiary amino group and a quaternary ammonium group, and diacrylamine.

The cationic resin may be added in the form of fine particles. This includes, for example, a cationic microgel described in JP-A-6-161101.

As the organic additive, a crosslinking agent can be used. Examples of the crosslinking agent include melamine resin, isocyanate compound, isoxazoles, aldehydes, N
-Methylol compounds, dioxane derivatives, active vinyl compounds, active halogen compounds and the like.

The organic components contained in the layer as described above include:
Even if a hydrophilic resin is crosslinked to improve durability, water resistance, etc., the hydrophilicity is greatly reduced,
This may cause stains during printing. For these reasons, it is preferable that the amount of the organic component added is small. Specifically, preferably, the amount of the organic component with respect to the entire layer is 0 to 40% by mass.
, More preferably 1 to 30%, and still more preferably 2 to 15%.

The formation of the “inorganic or organic-inorganic hybrid binder by the sol-gel method” is described, for example, in “Application of the sol-gel method” (written by Mio Sakubana / Agne Shofusha). Or known methods described in the literature cited herein.

As the base material of the lithographic printing plate precursor according to the present invention,
A known material used as a substrate of a printing plate can be used. For example, metal plate, plastic film,
Examples thereof include paper treated with polyolefin or the like, and a composite base material to which the above materials are appropriately bonded. The thickness of the substrate is not particularly limited as long as it can be attached to a printing machine, but a thickness of 50 to 500 μm is generally easy to handle.

Examples of the metal plate include iron, stainless steel, aluminum and the like, and aluminum is particularly preferable from the relation between specific gravity and rigidity. The aluminum plate is usually used after being degreased with an alkali, an acid, a solvent or the like in order to remove oil present on the surface and used in rolling and winding. As the degreasing treatment, degreasing with an aqueous alkali solution is particularly preferred. Further, in order to improve the adhesiveness with the coating layer, it is preferable to perform an easy adhesion treatment or an undercoating layer coating on the coating surface. For example, a method of immersing in a liquid containing a coupling agent such as a silicate or a silane coupling agent, or applying the liquid, followed by sufficient drying may be mentioned. Anodizing treatment is also considered as a kind of easy adhesion treatment and can be used. Further, the anodic oxidation treatment and the above immersion or coating treatment can be used in combination. For example, Japanese Patent Application Laid-Open No. 8-240
The organic-inorganic sol-gel film may be formed by the method described in JP-A-914. Also, an aluminum plate roughened by a known method can be used.

Examples of the plastic film include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, cellulose esters and the like. Particularly, polyethylene terephthalate and polyethylene naphthalate are preferred. In order to improve the adhesiveness between the plastic film and the coating layer, it is preferable to apply an easy adhesion treatment or an undercoating layer to the coating surface. Examples of the easy adhesion treatment include a corona discharge treatment, a flame treatment, and an ultraviolet irradiation treatment. Examples of the undercoat layer include layers containing gelatin and latex.

As the composite base material, the above-mentioned materials may be used by appropriately bonding them together, but may be bonded before forming the hydrophilic layer, or may be bonded after forming the hydrophilic layer. Alternatively, they may be laminated just before being attached to a printing machine.

The lithographic printing plate precursor according to the present invention can be produced by applying a coating solution containing the above components on a substrate and drying to form a layer. As a coating method, a general coating method can be used.

When the lithographic printing plate precursor of the present invention is a single layer containing inorganic particles, a light-to-heat conversion material and a hot-melt material,
The coating amount of the layer is preferably in the range of 1.0~20.0g / m ^2, the range of 2.0~10.0g / m ² is more preferable. In addition, there are three layers consisting of the [A] layer, the [B] layer and the [C] layer.
In the case of a layer, the coating amount of the [A] layer is 1.0 to 2
The range is preferably 0.0 g / m ² , and 2.0 to 10.0 g.
/ M ² is more preferable. [B] The coating amount of the layer
The range is preferably 0.1 to 8.0 g / m ² , and 0.2 to 8.0 g / m ^2.
A range of 4.0 g / m ² is more preferable. The coating amount of the layer [C] is preferably in the range of 0.1 to 8.0 g / m ² ,
The range is more preferably from ^{2 to} 4.0 g / m ² . When the coating amount of the layer [C] is less than 0.1 g / m ² , the strength of the coating film is insufficient, and stains due to scratches or the like and printing durability are reduced. If the amount is more than 8.0 g / m ² , the hot melt hardly oozes to the surface, and the sensitivity is lowered.

At the time of coating and drying the layer [B], and at the time of coating and drying other layers after the formation of the layer [B] on the substrate,
It is preferable to dry at a temperature equal to or lower than the melting point of the hot-melt material. Even when drying at a temperature equal to or higher than the melting point, it is preferable to dry in a short time of 1 minute or less. Further, an aging treatment can be appropriately performed after coating and drying. The aging treatment is preferably performed in a dry atmosphere at 40 to 70 ° C. for 6 to 200 hours.

The surface roughness of the lithographic printing plate precursor according to the present invention is R
a is 200 to 800 nm and Rz is 2000 to 70
The range of 00 nm is preferable, and Ra is 300 to 500 n.
m and Rz are more preferably in the range of 3500 to 4500 nm.

In the lithographic printing plate precursor according to the present invention, a layer group consisting of a layer containing inorganic particles, a light-to-heat conversion material and a heat-fusible material, and a layer containing at least one of inorganic particles, a light-to-heat conversion material and a heat-fusible material (Hereinafter, these may be referred to as "image forming layer"). A protective layer containing a water-soluble resin may be provided on the protective layer, and a protective film may be laminated. Further, a colored layer may be provided between the image forming layer and the substrate.

The water-soluble resin of the protective layer includes casein,
Soybean proteins, proteins such as synthetic proteins, chitins, starches, gelatins, polyvinyl alcohol, silyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose and hydroxyethyl cellulose, cellulose derivatives such as alginates, polyethylene oxide, Polypropylene oxide, polyethylene glycol, polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic polymer latex, vinyl polymer latex, polyacrylamide, polyvinylpyrrolidone, etc. No.

Preferably, starches, gelatins, polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives such as carboxymethylcellulose salts, hydroxyethylcellulose and alginates, among which carboxymethylcellulose and alginates are more preferable.

In addition to the water-soluble resin, the protective layer may contain the above-mentioned inorganic particles and crystalline cellulose.
In this case, the ratio of the water-soluble resin to the inorganic particles and the crystalline cellulose is preferably in the range of 95: 5 to 10:90. The coating amount of the protective layer is preferably from 0.1 to 20 g / m ² .

To perform printing using the lithographic printing original plate of the present invention, the lithographic printing original plate is image-exposed to form a lithographic printing plate surface. That is, the exposure changes the hydrophilic surface of the image forming layer of the lithographic printing plate precursor to ink receptivity. Therefore, printing can be performed as a printing plate without performing development processing after image exposure.

When the lithographic printing plate precursor contains fine particles of anatase type titanium oxide, development is not performed after image exposure.
By irradiating the ultraviolet light, the anatase type titanium oxide fine particles are excited by the ultraviolet light and change to hydrophilic, so that the hydrophilicity of the non-image area is increased and the stain property is improved.

[0131]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Examples 1 to 5 and Comparative Example 1 Preparation of Dispersions 1 to 6 The compositions shown in Tables 1 and 2 were mixed together with glass beads using a sand grinder at 1000 rpm.
After dispersion for 0 minutes, the glass beads were separated by filtration, and further dispersed with a high-speed homogenizer at 8000 rpm for 15 minutes to obtain dispersions 1 to 5. As a comparison, in a similar manner,
A dispersion liquid 6 containing no inorganic particles was prepared.

[0133]

[Table 1]

[0134]

[Table 2]

Next, carnauba wax emulsion A118 (manufactured by Gifu Shellac Co., Ltd., average particle size 0.3 μm, melting point 80 ° C., 140 ° C.) was added to each of the above dispersions as a heat-fusible material.
Melt viscosity of 8 cps, solid content 40 wt%)
%, Mixed, stirred and ultrasonically dispersed for 10 minutes, applied on the following substrate, and dried at 70 ° C. for 3 minutes. The coating thickness after drying was 4 g / m ² . Then the relative humidity 30
%, And aging was performed for 48 hours under the conditions of 55 ° C. to obtain lithographic printing original plate samples 1 to 6. In addition, each dispersion was
It was left to check the dispersion stability. Preparation of Crystalline Cellulose Dispersion Crystalline cellulose CL-611 (manufactured by Asahi Kasei Kogyo Co., Ltd.) shown in Table 1 was previously mixed with water, and then dispersed with a high-speed homogenizer at 15000 rpm for 60 minutes.
A wt% of the dispersion was prepared.

For the lithographic printing original plate samples 1 to 6,
The surface roughness Ra, Rz, exposure energy for ablation, visible image quality, sensitivity and printability (density non-image area density, soil recovery, blanket stain) were measured and evaluated by the following methods.

Surface Roughness (Ra, Rz) The surface roughness of the lithographic printing original plate sample was measured using a non-contact three-dimensional surface roughness meter (RST Plus manufactured by WYKO). The measurement was performed in the VSI mode, and the measurement was performed at five locations per sample at a magnification of 40 times, and the average value was described for the roughness parameter. In the measurement, a vapor deposition treatment with platinum palladium was performed on the sample surface.
This was performed so as to have a thickness of 5 nm.

Ablation generation exposure energy A lithographic printing plate precursor was wound around a drum of a laser exposure machine with the image forming layer facing out, and a resolution of 4000 dpi (laser beam diameter 6 μm) was irradiated with an infrared laser of 830 nm.
In m), imagewise exposure was performed by changing the amount of exposure energy. The image area of the lithographic printing plate after exposure was observed by SEM, and the minimum exposure energy at which ablation began to occur was determined.

Visibility The difference between the densities of the exposed and unexposed areas was measured using a reflection densitometer Macbeth RD.
Measured at -918.

Sensitivity Printing machine: Using DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., coated paper, dampening solution (H-liquid SG-manufactured by Toyo Ink Co., Ltd.)
51 density 1.5%) and ink (Toyo King Hi-Echo M Red manufactured by Toyo Ink Co., Ltd.).

The minimum exposure energy at which a good printed image without blur was obtained by visual judgment was taken as the sensitivity.

Density of Non-Image Area of Smudge After printing 1,000 sheets, the density of the non-image area on the paper surface was measured, and the stain was evaluated.

Soil Recovery After printing 1,000 sheets, the printing machine is idled for 5 minutes to dry the dampening solution adhering to the printing plate surface. Next, an ink roller was attached to the plate surface, and after applying ink to the entire printing plate, dampening water was supplied again to restart printing. Soil recovery was evaluated at the number of printed sheets where the degree of smearing of the non-image area on the paper became equal to that at the time of printing 1,000 sheets (the larger the number, the poorer).

After printing 5,000 sheets of blanket, the stain on the corresponding portion of the non-image area on the blanket was measured with a reflection densitometer; Macbeth RD-918.

The results are shown in Table 3 below.

[0146]

[Table 3]

From Table 3, it can be seen that the inclusion of colloidal silica in the form of a necklace results in excellent exposure visibility, and the inclusion of titanium oxide photocatalyst provides excellent soil recovery and blanket soiling properties. It can be seen that the inclusion of the compound has excellent dispersion stability.

Examples 6 to 23, Comparative Examples 2 to 6 Preparation of Dispersions for Three-Layer Composition Preparation of Dispersions A-1 to A-5 for Layer A Compositions shown in Tables 4 to 6 were prepared by using glass. Using a sand grinder together with the beads, the mixture was dispersed at 1000 rpm for 180 minutes, the glass beads were filtered off, and further dispersed with a high-speed homogenizer at 8000 rpm for 15 minutes.
1 to A-4 were obtained. As a comparison, a dispersion A-5 containing no material having a light-to-heat conversion function was prepared.

The crystalline cellulose CL-611 shown in Table 3
(Asahi Kasei Kogyo Co., Ltd.) previously mixed with water and then dispersed with a high-speed homogenizer at 15000 rpm for 60 minutes to prepare a 3 wt% dispersion. Further, as a result of leaving the coating solution containing the crystalline cellulose for one week, no sedimentation of inorganic particles was observed.

[0150]

[Table 4]

[0151]

[Table 5]

[0152]

[Table 6]

Dispersion: The particles obtained by previously coating a core material particle surface with a material having a light-to-heat conversion function and inorganic particles are prepared by a dry method using a sand grinder and glass beads (Hibee 20). Coated with light-to-heat conversion material and other materials. The rotation speed of the disk was 800 rpm. Table 7 shows the core particles, coating materials, and processing times. After the treatment, the particles were sampled, and the degree of coating of the core material particles was evaluated by SEM observation. The results are also shown in Table 7.

[0154]

[Table 7]

The coated particles were mixed with pure water and stirred, and the glass beads were separated by filtration to collect a 10 wt% dispersion. Next, this dispersion was mixed with the components shown in Table 4,
Dispersion with a high-speed homogenizer at 8000 rpm for 15 minutes, and dispersions A-6 to A- containing "particles having core material particles coated with a material having a photothermal conversion function and inorganic particles"
8 was obtained. The dispersion A-8 contained aluminosilicate particles having an average particle size of 5.4 μm, with the core material particles as large particles.

[B] Preparation of Layer Dispersions B-1 to B-6 Dispersions B-1 to B-6 The compositions shown in Tables 8 and 9 were mixed and stirred, and subjected to ultrasonic dispersion for 10 minutes. And Dispersions B-1 to B-6. Also,
As the dispersion liquid of the porous inorganic particles shown in Tables 8 and 9, the dispersion liquid A-4 dispersion liquid in the above "Preparation of Layer A" was used.

[0157]

[Table 8]

[0158]

[Table 9]

[C] Preparation of Dispersions C-1 to C-6 for Layers The compositions shown in Tables 10 and 11 were mixed with glass beads using a sand grinder at 1000 rpm.
After the dispersion for 0 minutes, the glass beads were separated by filtration, and further dispersed with a high-speed homogenizer at 8000 rpm for 15 minutes.
Dispersions C-1 to C-6 were obtained. Table 6 shows the content of the inorganic components contained in the dispersion. Aluminosilicate and zeolite particles are dispersed and crushed, and the particle size is 1
It was confirmed by SEM observation that it was not more than μm.

[0160]

[Table 10]

[0161]

[Table 11]

Preparation of lithographic printing plate precursor A lithographic printing plate precursor having the structure shown in Table 12 was prepared on the following base material. Each layer was applied using a wire bar so as to have a specified amount. [A] layer was dried at 100 degreeC for 10 minutes. The layer [B] and the layer [C] were dried at 70 ° C. for 3 minutes. Thus, a lithographic printing plate was prepared by sequentially stacking the plates, and the obtained printing plate was aged for 48 hours under the conditions of a relative humidity of 30% and 55 ° C.

Formation of Base Material and Undercoat Layer Polyethylene terephthalate (PE) having a thickness of 0.18 mm
T) A two-layer undercoat layer was formed on the film by the following method.

First undercoat layer After applying a corona discharge treatment to the coating surface of the PET substrate, the coating solution having the following composition was dried with a wire bar in an atmosphere of 20 ° C. and a relative humidity of 55%. It was applied so as to be 0.4 μm. Thereafter, drying was performed at 140 ° C. for 2 minutes.

<Composition of First Undercoat Layer> Acrylic latex particles: n-butyl acrylate / t-butyl acrylate / styrene / hydroxyethyl methacrylate = 28/22/25/25 36.9 g Surfactant (A) 0.36 g Hardening agent (a) Distilled water was added to 0.98 g or more to make 1000 ml to prepare a coating solution.

Second undercoat layer After a corona discharge treatment was applied to the surface of the above film on which the first undercoat layer was formed, a coating solution having the following composition was applied by an air knife method in an atmosphere at 35 ° C. and a relative humidity of 22%. Coating was performed so that the film thickness after drying was 0.1 μm. Then 14
Drying was performed at 0 ° C. for 2 minutes.

<Composition of Second Undercoat Layer> Gelatin 9.6 g Surfactant (A) 0.4 g Hardener (b) 0.1 g Distilled water was added to the above to make 1000 ml, thereby preparing a coating solution.

[0168]

Embedded image

With respect to the lithographic printing plate precursor sample, the surface roughness, ablation generation exposure energy,
Visibility, sensitivity and printing suitability were measured and evaluated, and scratch flaw suitability was evaluated by the following method.

Evaluation Method for Suitability for Scratch Scratches Using a wear resistance tester (HEIDON-18), 0.1
With a sapphire stylus of mmφ, the load was changed from 0 to 200 g under continuous load, and the surface of the lithographic printing plate was slid, and a sliding scratch confirmed as dirt during printing was applied with a load of several g. Was evaluated.

The above results are shown in Tables 12 and 13 below.

[0172]

[Table 12]

[0173]

[Table 13]

As is clear from Tables 12 and 13, the lithographic printing plate precursor according to the present invention has no ablation and high sensitivity. In addition, by containing necklace-shaped colloidal silica, exposure visibility is excellent, and by containing particles coated with a photothermal conversion material and inorganic particles on the core material particle surface, sensitivity is improved, and the core material particles are larger than the core material particles. And 20μ
m contains hydrophilic particles in the range of less than m, improves scratch suitability, and contains porous inorganic particles larger than the average particle size of the hot-melt material and 3 μm or less, improves scratch suitability. I do.

Examples 24 to 33 and Comparative Examples 7 to 16 Preparation of Coating Solution 1 for Protective Layer The following compositions were prepared at 8000 rpm using a high-speed homogenizer.
After stirring for 1 hour at, filtration was performed to prepare a protective layer coating solution 1.

Sodium carboxymethylcellulose 18 g (CMC Daicel 3043: manufactured by Daicel Chemical Industries, Ltd.) Hydroxypropyl cellulose (TC-5: manufactured by Shin-Etsu Chemical Co., Ltd.) 2 g Distilled water 980 g Preparation of protective layer coating solution 2 Protective layer coating In the same manner as in Liquid 1, a protective layer coating liquid 2 having the following composition was prepared.

Sodium carboxymethylcellulose 12 g (CMC Daicel 3043: manufactured by Daicel Chemical Industries, Ltd.) Crystalline cellulose (CL-611: manufactured by Asahi Kasei Corporation) 6 g distilled water 980 g Next, the lithographic printing plate precursor described in the above Examples Using a wire bar, the protective layer coating liquids 1 and 2 were combined in the combination shown in Table 14 below, and the dry weight of the protective layer was 0.5 g / m ^2.
And dried at 55 ° C. for 10 minutes.

The lithographic printing original plate thus obtained was imagewise exposed to light in the same manner as in the above Examples to obtain a lithographic printing plate. A finger was brought into contact with these lithographic printing plates for 20 seconds to allow sweat (sebum) to adhere thereto, then printing was started, and the printed matter after printing 100 sheets was evaluated. In addition, the soil recovery property and the suitability for scratching were evaluated by the above method. The results are shown in Table 14 below.

[0179]

[Table 14]

In Table 14, the meanings of the symbols in the column of the fingerprint stain evaluation result are as follows. ：: No fingerprint-like stains Δ: Slightly fingerprint-like stains occurred X: Fingerprint-like stains occurred As is apparent from Table 14, the protective layer containing a water-soluble resin was removed. By providing such a film, the fingerprint stain property is excellent, the stain recovery property and the scratch resistance are improved.

[0181]

According to the present invention, a lithographic printing plate precursor capable of forming a high-sensitivity, high-resolution image without requiring any special developing treatment and without causing ablation, and having scratch resistance due to scratching and the like. Provides a lithographic printing plate precursor which is excellent in stainability of a non-image area, particularly excellent in stain recovery property and blanket stain property, excellent in printing durability, and excellent in visibility after exposure, and a printing method using the same. Is done. Further, according to the present invention, there is provided a lithographic printing plate precursor having excellent dispersion stability of a coating solution and having no cracks in a coating film.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a dispersion structure of necklace-shaped colloidal silica used in the present invention.

FIG. 2 is a schematic diagram showing a dispersion structure of silica particles of a conventional colloidal silica.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conventional colloidal silica 2 Spherical silica particles 3 Necklace-shaped colloidal silica 4 Spherical silica particles

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H025 AA02 AA12 AA13 AB03 AC01 AD01 BH03 CC08 CC11 CC20 DA01 DA20 DA40 2H096 AA06 BA16 EA02 2H114 AA04 AA24 AA30 BA01 BA10 DA03 DA05 DA08 DA14 DA15 DA42 DA43 DA44 DA59 DA51 DA53 EA01 EA02 EA03 EA05 FA01 FA06 FA09

Claims (24)

[Claims] 1. A lithographic printing plate precursor comprising a base material containing inorganic particles, a material having a light-to-heat conversion function, and a material which is melted by heat. 2. The lithographic printing plate precursor according to claim 1, wherein necklace-shaped colloidal silica is contained as inorganic particles. 3. The necklace-shaped colloidal silica is composed of spherical colloidal silica having a particle diameter of 10 to 50 nm.
3. The lithographic printing plate precursor according to claim 2, wherein the lithographic printing plate precursor is colloidal silica bonded to a length of 0 nm. 4. The lithographic printing plate precursor according to claim 1, further comprising anatase-type titanium oxide fine particles as inorganic particles. 5. The lithographic printing plate precursor according to claim 1, further comprising crystalline cellulose. 6. A layer containing a material having a photothermal conversion function, [B] a layer containing a material which is melted by heat, and [C] a layer containing 60% by mass or more of inorganic particles are sequentially laminated. A lithographic printing plate precursor comprising: 7. The lithographic printing plate precursor according to claim 6, wherein at least one of the layer [A], the layer [B] and the layer [C] contains necklace-shaped colloidal silica. 8. A necklace-shaped colloidal silica having a particle diameter of 10 to 50 nm and a spherical colloidal silica having a particle diameter of 50 to 400.
The lithographic printing plate precursor according to claim 7, wherein the lithographic printing plate precursor is colloidal silica bonded to a length of nm. 9. The lithographic printing plate precursor according to claim 6, wherein at least one of the layer [A], the layer [B] and the layer [C] contains fine particles of anatase type titanium oxide. . 10. The lithographic printing method according to claim 6, wherein at least one of the layer [A], the layer [B] and the layer [C] contains crystalline cellulose. Original version. 11. The lithographic printing original plate according to claim 1, wherein the photothermal conversion material is a conductive metal oxide. 12. The method according to claim 6, wherein the layer (A) is a layer containing a material having a photothermal conversion function on the surface of the core material particles and particles coated with inorganic particles.
The lithographic printing original plate described in the section. 13. The core material particles contained in the layer [A] have an average particle size of 0.1 to 10 μm, and contain hydrophilic particles having an average particle size larger than the core material particles and 20 μm or less. The lithographic printing original plate according to claim 12, wherein: 14. The material which is melted by heat has a melting point of 40 to
The viscosity in the range of 150 ° C. and 140 ° C.
The lithographic printing plate precursor according to any one of claims 1 to 13, wherein the lithographic printing plate precursor has a pressure of 1 × 10 ^{−3 to} 100 × 10 ⁻³ Pa · s. 15. The method according to claim 6, wherein the layer (B) contains porous inorganic particles having a diameter larger than the average particle diameter of the material to be melted by heat and having a diameter of 3 μm or less. The lithographic printing original plate according to item 1. 16. The lithographic printing plate precursor according to claim 1, wherein at least one of the inorganic particles is a porous inorganic particle. 17. The lithographic printing plate precursor according to claim 15, wherein the porous inorganic particles are porous silica, porous aluminosilicate or zeolite. 18. The lithographic printing original plate according to claim 6, wherein the layer [C] contains a material having a light-to-heat conversion function. 19. The coating amount of the layer [C] is from 0.1 to 8.0 g.
/ Lithographic printing plate precursor as claimed in any one of claims 6-18, characterized in that m is in the range of ^2. 20. The surface roughness of a lithographic printing plate, wherein the average surface roughness Ra is in the range of 200 to 800 nm, and the ten-point average roughness Rz is in the range of 2000 to 7000 nm. 20. The lithographic printing original plate according to any one of Items 1 to 19 above. 21. A lithographic printing original plate comprising a lithographic printing original plate according to claim 1 and a protective layer containing a water-soluble resin provided thereon. 22. The water-soluble resin comprises starches, gelatins,
22. The lithographic printing plate precursor according to claim 21, wherein the lithographic printing plate precursor is at least one selected from polyvinyl alcohol, modified polyvinyl alcohol, and cellulose derivatives. 23. The lithographic printing plate precursor according to any one of claims 1 to 22, after image exposure, without performing a developing process, the image-exposed portion receives ink, and the unexposed portion is dampened. A printing method, wherein printing is performed by receiving water. 24. A lithographic printing plate precursor containing the anatase-type titanium oxide fine particles according to claim 9, after imagewise exposure, without developing, and after irradiating with ultraviolet light, the imagewise exposed portion. A printing method, wherein printing is performed by receiving ink and unexposed portions receiving fountain solution.