JP2008089916A - Lithographic printing plate precursor, and lithographic printing plate precursor laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate precursor and its laminate that suppress adhesion and rub scratches between the surface of the lithographic printing plate precursor and the backside of a support in an adjacent lithographic printing plate precursor when the plates are stacked without using inserting paper, that suppress polymerization inhibition in a polymerizable negative photosensitive layer, and that prevent fracture of the photosensitive layer. <P>SOLUTION: The lithographic printing plate precursor has a polymerizable negative photosensitive layer and an oxygen blocking layer containing mica sequentially in this order on a support, and further has a protective layer containing fine particles containing an organic resin as the uppermost layer, wherein the hardness H<SB>1</SB>of the fine particles containing the organic resin and the hardness H<SB>2</SB>of the oxygen blocking layer containing mica satisfy the relation of H<SB>1</SB>≤H<SB>2</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a negative lithographic printing plate precursor capable of direct drawing with infrared laser light and capable of high-speed plate making, and a laminate thereof.

  Conventionally, PS plates having a structure in which an oleophilic photosensitive resin layer is provided on a hydrophilic support are widely used as lithographic printing plate precursors. As a plate making method, mask exposure (typically through a lithographic film) After the surface exposure), the desired printing plate was obtained by dissolving and removing the non-image area. In recent years, digitization techniques that electronically process, store, and output image information using a computer have become widespread. Various new image output methods corresponding to such digitization techniques have come into practical use. As a result, computer-to-plate (CTP) technology that scans highly directional light such as laser light according to digitized image information and directly produces a printing plate without going through a lithographic film is eagerly desired. Obtaining a lithographic printing plate precursor adapted to this is an important technical issue.

As such a lithographic printing plate precursor capable of scanning exposure, an oleophilic photosensitive resin layer containing a photosensitive compound capable of generating active species such as radicals and Bronsted acid by laser exposure on a hydrophilic support (hereinafter referred to as “lithographic printing plate precursor”) , Which is also referred to as a photosensitive layer) has been proposed and is already on the market. This lithographic printing plate precursor is laser-scanned based on digital information to generate active species, which causes physical or chemical changes in the photosensitive layer to insolubilize it, followed by development processing, thereby developing a negative lithographic printing plate Can be obtained.
In particular, on a hydrophilic support, a photopolymerization type photosensitive layer containing a photopolymerization initiator excellent in photosensitive speed, an ethylenically unsaturated compound capable of addition polymerization, and a binder polymer soluble in an alkali developer, and necessary According to the planographic printing plate precursor (for example, see Patent Document 1) provided with an oxygen-blocking protective layer is excellent in productivity, simple development processing, and good resolution and inking properties, It has desirable printing performance.

In addition, in order to improve productivity, that is, to improve plate making speed, photopolymerizability comprising a cyanine dye having a specific structure, an iodonium salt and an addition polymerizable compound having an ethylenically unsaturated double bond. A recording material that uses the composition for the photosensitive layer and does not require heat treatment after imagewise exposure has been proposed (see, for example, Patent Document 2). This recording material is produced by oxygen in the air during the polymerization reaction. There was a problem that the polymerization was inhibited, the sensitivity was lowered, and the strength of the formed image area was insufficient.
To solve this problem, a method of providing a protective layer containing a water-soluble polymer on the photosensitive layer or a method of providing a protective layer containing an inorganic layered compound and a water-soluble polymer (for example, see Patent Document 3) is known. It has been. The presence of these protective layers prevents polymerization inhibition, promotes the curing reaction of the photosensitive layer, and improves the strength of the image area.

  On the other hand, shortening the time required for the exposure process is important as the productivity in the plate making operation of a photopolymerization type lithographic printing plate precursor that is easy to develop. In the exposure process, a laminate in which an interleaving paper having an anti-adhesion function between originals and an anti-scratching function caused by rubbing the surface of a relatively soft protective layer with an aluminum support is usually inserted between the originals. Supplied as Therefore, the slip sheet removal time in the exposure process has been a cause of inefficiency. In order to improve the efficiency in this exposure process, it is sufficient to omit the process of removing the slip sheet by using a laminate that does not insert the slip sheet between the master plates. There has been a desire for improvements in adhesion and scratches caused by rubbing the surface of the protective layer with the aluminum support. For improving the adhesion resistance between lithographic printing plate precursors, the above-mentioned method of providing a protective layer containing an inorganic layered compound and a water-soluble polymer is effective, but when the protective layer surface is rubbed with an aluminum support Rather, it becomes easy to be scratched. Further, the outermost layer of the protective layer to which the inorganic layered compound is added has a small coefficient of friction and is easy to slide, and when it is made into a laminate, it has a fatal defect that the laminate tends to collapse due to stress from the side.

From the above, polymerization inhibition of the polymerizable negative photosensitive layer can be suppressed, and even if a laminate is formed without inserting a slip sheet between the original plates, the adhesion resistance between the lithographic printing plate precursors is improved. Further, there is a demand for a lithographic printing plate precursor capable of suppressing scratches caused by rubbing the surface of the protective layer with an aluminum support and improving productivity in plate making operations.
For example, Patent Document 4 describes a method of providing a mat layer containing fine particles made of an organic resin as a technique capable of improving the above-described scratches.
Japanese Patent Laid-Open No. 10-228109 Japanese Examined Patent Publication No. 7-103171 JP 11-38633 A Japanese Patent No. 2739395

  However, in the case where the mat layer as described above is provided on the lithographic printing plate precursor, the fine particles constituting the mat layer sink into the photosensitive layer when pressure is applied from the outside on the mat layer side during lamination. The photosensitive layer may be physically destroyed. In particular, the polymerizable negative photosensitive layer has a low physical strength of the film and is easily broken in order to increase the polymerization efficiency and achieve high sensitivity. When the photosensitive layer is destroyed, when the portion is an image portion, an image defect occurs, and a problem that print quality is remarkably deteriorated occurs.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to achieve the following object.
That is, the object of the present invention is to cause adhesion between the surface of the lithographic printing plate precursor and the back surface of the adjacent lithographic printing plate precursor, and generation of scratches between them when laminated without interposing the interleaving paper. It is intended to provide a lithographic printing plate precursor capable of suppressing the polymerization inhibition of the polymerizable negative photosensitive layer and further preventing the photosensitive layer from being destroyed.
Another object of the present invention is to provide a laminate of a lithographic printing plate precursor that uses the lithographic printing plate precursor and can improve productivity in plate making operations.

As a result of intensive studies focusing on the hardness of the organic resin fine particles, the inventor has a hardness higher than that of the organic resin fine particles between the polymerizable negative photosensitive layer and the protective layer containing the organic resin fine particles. It has been found that the above object can be achieved by adopting a configuration in which an oxygenated fault is provided, and the present invention has been achieved.
That is, the lithographic printing plate precursor of the present invention has a polymerizable negative photosensitive layer and an oxygen barrier layer containing mica in this order on a support, and further contains fine particles containing an organic resin in the uppermost layer. A hardness H _{1 of the} fine particles containing the organic resin and a hardness H ₂ of the oxygen barrier layer containing the mica satisfies a relationship of H ₁ ≦ H ₂ .
In the present invention, the fine particles containing the organic resin preferably contain a silica component, more preferably organic resin fine particles whose surface is coated with silica.

  The laminate of the lithographic printing plate precursor according to the invention is characterized in that a plurality of the lithographic printing plate precursors of the invention are laminated with the protective layer and the back surface of the support in direct contact.

According to the present invention, when laminating without interposing the interleaving paper, the adhesion between the surface of the lithographic printing plate precursor and the back surface of the adjacent lithographic printing plate precursor support, and the generation of scratches between them are suppressed. In addition, it is possible to provide a lithographic printing plate precursor capable of suppressing the polymerization inhibition of the polymerizable negative photosensitive layer and further preventing the photosensitive layer from being destroyed. Therefore, since it is not necessary to use a slip sheet when laminating, industrial waste can be reduced, and productivity in the plate making operation can be improved.
Moreover, since the laminated body of the lithographic printing plate precursor according to the present invention is formed by laminating the lithographic printing plate precursor according to the present invention without interposing the interleaf, productivity in the plate making operation can be improved.

<Lithographic printing plate precursor and laminates thereof>
The lithographic printing plate precursor according to the invention has a polymerizable negative photosensitive layer and an oxygen barrier layer containing mica in this order on a support, and further contains fine particles containing an organic resin in the uppermost layer. It has a protective layer and the hardness H _{1 of the} fine particles containing the organic resin and the hardness H ₂ of the oxygen barrier layer containing the mica satisfy the relationship of H ₁ ≦ H ₂ .
That is, the hardness of the fine particles containing the organic resin in the present invention (hereinafter sometimes referred to as “organic resin fine particles” as appropriate) is the same as or smaller than the hardness of the oxygen barrier layer containing mica. . By satisfying this relationship, the fine particles in the protective layer cannot penetrate the oxygen blocking layer even when pressure is applied from the outside to the planographic printing plate precursor of the present invention, and as a result, a polymerizable negative photosensitive layer is obtained. It is possible to prevent the fine particles from sinking.

In addition, since the protective layer containing fine particles containing an organic resin as the uppermost layer has a relatively soft convex portion, adhesion between the surface of the lithographic printing plate precursor and the back surface of the adjacent lithographic printing plate precursor support , And the generation of scratches between them can be suppressed. As a result, since it is not necessary to use a slip sheet when laminating, industrial waste can be reduced, and productivity in plate making operations can be improved.
In addition, the presence of the oxygen barrier layer containing mica suppresses polymerization inhibition of the polymerizable negative photosensitive layer, thereby enabling good image formation.

  The laminate of the lithographic printing plate precursor according to the invention is obtained by laminating the lithographic printing plate precursor according to the invention with the protective layer and the back surface of the support in direct contact. In other words, the sheets are stacked without interposing the interleaving paper, and the process of removing the interleaving paper is not required in the plate making operation, so that productivity can be improved.

The relationship between the hardness H ₁ of the organic resin fine particles and the hardness H ₂ of the oxygen barrier layer containing mica will be described below.
In the present invention, it is essential to satisfy the relationship of the hardness H ₁ of the organic resin fine particles ≦ the hardness H ₂ of the oxygen blocking layer, but the hardness H ₁ of the organic resin fine particles is the hardness H _{2 of} the oxygen blocking layer containing mica. Is preferably smaller.
More preferably, the difference between the hardness H ₁ and the hardness H ₂ is more preferably 0.01 GPa or more, and further preferably 0.03 GPa or more.

Here, a method for measuring hardness in the present invention will be described.
The hardness H ₁ of the organic resin fine particles and the hardness H ₂ of the oxygen barrier layer containing mica are all Brinell hardness meter, Rockwell hardness meter, Vickers hardness meter, micro hardness meter, Knoop hardness meter, superficial hardness It can be measured by a general method such as a meter, a thin film hardness meter (triboscope), etc. Among them, a triboscope is a measurement method with excellent quantitativeness, and is preferable.
The method for measuring the hardness of the organic resin fine particles or the oxygen barrier layer according to the present invention is to push the indenter into an object formed on the surface of the substrate, and determine the hardness of the organic resin fine particles or the oxygen barrier layer from the depth of the indentation. taking measurement. At this time, the indentation depth of the indenter is preferably in the range of 2 to 50% with respect to the film thickness of the thin film. The indenter is preferably a diamond indenter, and the shape thereof is preferably a Vickers-type indenter or a Belkovic-type indenter.
In addition, what is necessary is just to measure the target object formed by spraying microparticles | fine-particles on the surface of a base material, when measuring the hardness of organic resin microparticles | fine-particles.

  Moreover, as a measuring apparatus used by the method of this invention, in addition to Elionix super micro hardness tester ENT-1100a, Shimadzu Corporation dynamic hardness meter "DUH-200" "DUH-W210" etc. are mentioned. . It is also possible to use a Fischer microhardness measuring device equivalent to them; a Fischer scope H100V or a Vigo Multimode AFM connected to a Hystron Triboscope. In this case, a Vickers indenter or a Belkovic indenter is used. Similarly, the hardness can be obtained in the same manner. In any apparatus, it is desirable that the resolution is μN and the resolution of the indentation depth is nm.

The hardnesses H ₁ and H ₂ were calculated by H = P / A from the load (P) when the indentation depth was 10% of the film thickness and the action area of the indenter at that time. About the method of calculating | requiring P and A, the method of literature "Oliver and Pharr, Journal of Materials Research, 7 (6), 1564 (1992)" was followed.

Incidentally, the lithographic printing plate precursor which is produced, the hardness H ₁ of the organic resin fine particles contained therein, and the hardness of H ₂ oxygen blocking layer, when measuring is, FT-IR, X-ray fluorescence measurements , ¹ H-NMR, gravimetric analysis spectrum, and GPC can be used to identify the type of organic resin fine particles used and the composition of the oxygen barrier layer, and to apply the measurement to the measurement method described above.

  Hereinafter, each component of the protective layer, the oxygen blocking layer, the polymerizable negative photosensitive layer, and the support constituting the lithographic printing plate precursor according to the invention will be described.

[Protective layer]
The protective layer according to the present invention is a layer containing fine particles containing organic resin (organic resin fine particles). Due to the presence of the fine particles, a protective layer having a relatively soft convex portion can be obtained. Since this protective layer is the uppermost layer, and also because the protective layer is provided with matting properties, when the planographic printing plate precursor of the present invention is laminated without sandwiching the interleaf, It becomes possible to suppress adhesion between the adjacent lithographic printing plate precursor and the back surface of the support, and scratches generated between the protective layer surface and the back surface of the support.
First, the organic resin fine particles in the present invention will be described.

(Organic resin fine particles)
The organic resin fine particles in the present invention suppress adhesion between the protective layer surface of the lithographic printing plate precursor and the back surface of the adjacent lithographic printing plate precursor, and scratches generated between the protective layer surface and the back surface of the support. To be added.
The basic characteristics desired for such organic resin fine particles that act as a matting agent are that the transmission of light used for exposure is not substantially inhibited, and it softens or becomes sticky depending on the moisture and temperature in the air. It is preferable that the surface of the protective layer is appropriately roughened to reduce the adhesion surface area.
Moreover, from the viewpoint of suppressing scratching, it is preferable that the organic resin fine particles can relieve stress generated when rubbing with a hard support back surface (aluminum).
Furthermore, the organic resin fine particles in the present invention preferably have a high affinity with the binder (for example, polyvinyl alcohol) of the protective layer, are well kneaded in the protective layer, and do not leave the protective layer surface.

  Examples of the organic resin fine particles having the above-described characteristics include poly (meth) acrylates, polystyrene and derivatives thereof, polyamides, polyimides, low-density polyethylene, high-density polyethylene, polypropylene, and other polyolefins, and Examples thereof include copolymers of these and poval, synthetic resin particles such as polyurethane, polyurea and polyester, and natural polymer fine particles such as chitin, chitosan, cellulose, crosslinked starch and crosslinked cellulose. Among these, synthetic resin fine particles have advantages such as easy particle size control and easy control of desired surface properties by surface modification.

  Such organic resin fine particle production methods can be pulverized by crushing, but the method of synthesizing particles by emulsion / suspension polymerization is currently the mainstream due to the ease and accuracy of particle size control. It has been adopted. More specifically, the method for producing these fine particle powders is described in “Ultrafine Particles and Materials”, edited by the Japan Society for Materials Science, published in 1993, “Manufacturing and Application of Fine Particles / Powder”, supervised by Haruma Kawaguchi, It is described in detail in MC Publishing 2005.

  These organic resin fine particles can be used as commercial products. As commercial products suitable as the organic resin fine particles in the present invention, cross-linked acrylic resins MX-300, MX-500, MX-1000, MX-1500H, MR-2HG, MR-7HG, MR-10HG manufactured by Soken Chemical Co., Ltd. MR-3GSN, MR-5GSN, MR-7G, MR-10G, MR-5C, MR-7GC, styryl resin-based SX-350H, SX-500H, Sekisui Plastics Co., Ltd. acrylic resin, MBX-5, MBX -8, MBX-12MBX-15, MBX-20, MB20X-5, MB30X-5, MB30X-8, MB30X-20, SBX-6, SBX-8, SBX-12, SBX-17 polyolefin resin manufactured by Mitsui Chemicals, Chemipearl W100, W200, W300, W308, W310, W400, W401, W405, W410, 500, WF640, W700, W800, W900, W950, WP100, and the like.

The organic resin fine particles in the present invention preferably contain a silica component, and particularly preferably silica-coated fine particles in which a part of the surface of the organic resin fine particles is coated with a silica layer. Due to the presence of silica on at least a part of the surface of the organic resin fine particles, the affinity between the organic resin fine particles and the binder (polyvinyl alcohol) is improved, and the organic resin fine particles are applied even when external stress is applied to the protective layer. Is suppressed, and excellent scratch resistance and adhesion resistance can be maintained.
Therefore, the “silica coating” in the present invention includes such a state that silica is present on at least a part of the surface of the organic resin fine particles.

As the organic resin constituting the organic resin fine particles serving as the core of the silica-coated fine particles according to the present invention, any organic resin having physical properties required for the organic resin fine particles as described above can be used without limitation. Specifically, for example, polyacrylic acid resins, polyurethane resins, polystyrene resins, polyester resins, epoxy resins, phenol resins, melamine resins, silicone resins and the like can be mentioned.
Of these, polyacrylic acid resins, polyurethane resins, melamine resins, and the like are preferable from the viewpoint of affinity with polyvinyl alcohol, which is a preferred binder for the protective layer.

In addition, as a material for forming the silica layer covering the surface of the organic resin fine particles, compounds having an alkoxysilyl group such as a condensate of an alkoxysiloxane compound, particularly a siloxane material used in a sol-gel method, silica sol Preferred are silica fine particles such as colloidal silica and silica nanoparticles.
Regarding the constitution of the silica-coated fine particles, even if the silica fine particles adhere to the surface of the organic resin fine particles as a solid component, a condensation reaction of the alkoxysiloxane compound was performed to form a siloxane compound layer on the surface of the organic resin fine particles. It may be a thing.

Silica does not necessarily need to coat the entire surface of the organic resin fine particles, and the above-described effects can be obtained if the surface is coated at an amount of 0.5% by mass or more with respect to at least the organic resin fine particles.
The surface coating state of silica can be confirmed by morphological observation with a scanning electron microscope (TEM) or the like, and the silica coating amount is detected by detecting Si atoms by elemental analysis such as fluorescent X-ray analysis. This can be confirmed by calculating the amount of silica present.

  The production method of the silica-coated fine particles in the present invention is not particularly limited, and the silica surface coating layer is formed simultaneously with the formation of the organic resin fine particles by coexisting the silica fine particles or the silica precursor compound with the monomer component as the raw material of the resin fine particles. Alternatively, a method may be employed in which after forming the organic resin fine particles, the silica fine particles are physically attached to the surface and then fixed.

  As an example of the method for producing silica-coated fine particles, first, a suspension stabilizer appropriately selected from water-soluble polymers such as polyvinyl alcohol, methylcellulose, and polyacrylic acid, and inorganic suspensions such as calcium phosphate and calcium carbonate. In water containing, silica and a raw resin (more specifically, a monomer capable of suspension polymerization, a prepolymer capable of suspension cross-linking, or a raw resin such as a resin liquid constituting the organic resin described above) Is added, stirred, and mixed to prepare a suspension in which silica and the hydrophobic raw material resin are dispersed, in which case the type of suspension stabilizer, its concentration, and the number of rotations of stirring are adjusted. Then, an emulsion (suspension) having a desired particle size can be formed, and the suspension is heated to start the reaction, and the resin raw material is subjected to suspension polymerization or suspension crosslinking. At this time, the coexisting silica is fixed to the resin particles that are cured by polymerization or cross-linking reaction, particularly in the vicinity of the surface of the resin particles due to their physical properties. The suspension stabilizer adhering to the particles is removed by liquid separation and washed, and dried to obtain substantially spherical organic resin particles having a desired particle size on which silica is immobilized.

  In this way, it is possible to obtain a resin of a desired size by controlling the conditions during suspension polymerization or suspension crosslinking. However, silica-adhered organic resin fine particles can be produced without strict control. Then, silica-coated fine particles having a desired size can be obtained by a mesh filtration method.

  When the total amount of the raw material resin and silica is 100 parts by weight, the addition amount of the raw material in the mixture when the silica-coated fine particles are produced by the above method is first stable in suspension in 200 to 800 parts by weight of water as a dispersion medium. 0.1 to 20 parts by weight of the agent is added and sufficiently dissolved or dispersed, and the mixture of 100 parts by weight of the raw material resin and silica is added to the liquid so that the dispersed particles have a predetermined particle size. After adjusting the particle size, the liquid temperature is raised to 30 to 90 ° C. and reacted for 1 to 8 hours.

  As for the method for producing silica-coated fine particles, the above-described method is an example, and for example, JP 2002-327036 A, JP 2002-173410 A, JP 2004-307837 A, JP 2006-38246 A, and the like. The method described in detail in can also be applied. Further, any silica-coated fine particles obtained by the method described herein can be suitably used in the present invention.

  The silica-coated fine particles that can be used in the present invention are also available as commercial products. As specific examples, silica / melamine composite fine particles include Nissan Chemical Industries Co., Ltd. Opt Bead 2000M, Opt Bead 3500M, Examples thereof include opt beads 6500M, opt beads 10500M, opt beads 3500S, and opt beads 6500S. As silica / acrylic composite fine particles, Negami Industrial Co., Ltd. Art Pearl G-200 transparent, Art Pearl G-400 transparent, Art Pearl G-800 transparent, Art Pearl GR-400 transparent, Art Pearl GR-600 transparent, Art Pearl GR-800 transparent, Art Pearl J-7P. As the silica / urethane composite fine particles, Negami Industrial Co., Ltd. Art Pearl C-400 Transparent, C-800 Transparent, P-800T, U-600T, U-800T, CF-600T, CF800T, Dainichi Seika Co., Ltd. Dynamic Examples thereof include beads CN5070D and dampula coat THU.

In the protective layer in the present invention, only one organic resin fine particle may be used, or two or more organic resin fine particles may be used in combination. For example, organic resin fine particles and silica-coated fine particles may be used in combination.
Hereinafter, preferred physical properties of the organic resin fine particles of the present invention will be described.

The hardness (H ₁ ) of the organic resin fine particles (silica-coated fine particles) according to the present invention is not particularly limited as long as it is the same as or lower than the hardness (H ₂ ) of an oxygen barrier layer described later. When measured with a device having a Triscope made by Hystron, it is 0.0005 to 0.20 GPa, more preferably 0.001 to 0.15 Gpa, and the most preferable hardness is 0.003 to 0.010 Gpa. It is.
This hardness can be appropriately adjusted according to the material of the organic resin fine particles, the coating amount of the silica layer, and the like.

The shape of the organic resin fine particles (silica-coated fine particles) according to the present invention is preferably a true spherical shape, but may be a flat plate shape or an elliptical shape.
The preferable average particle diameter of the organic resin fine particles (silica-coated fine particles) according to the present invention is 1 to 30 μmφ, more preferably 1.5 to 20 μmφ, and most preferably 2 to 15 μmφ. In this range, a sufficient spacer function and mat performance can be expressed, the immobilization on the surface of the protective layer is easy, and the holding function is excellent against contact stress from the outside.
In particular, the true specific gravity of the organic resin fine particles (silica-coated fine particles) is in the range of 0.90 to 1.30, and the average particle diameter is preferably 2.0 to 15 μm. It is in the range of 90 to 1.20, and more preferably 3.0 to 12 μm.

The preferable addition amount of the organic resin fine particles (silica coated fine particles) to the protective layer according to the present invention is 5 to 1000 mg / m ² , more preferably 10 to 500 mg / m ² , and most preferably 20 to 200 mg. / M ² .
More specifically, the content of the organic resin fine particles (silica coated fine particles) in the protective layer solid content is preferably 1.0% by mass to 20% by mass, and more preferably 2.0% by mass to 10% by mass. If the addition amount is too small, the surface mat effect will not be exhibited, the adhesion prevention effect and scratch resistance effect will be insufficient, and if the addition amount is too large, the sensitivity will decrease and the particles will be detached from the protective layer surface, It may cause failure.

(binder)
The binder for forming the protective layer is not particularly limited as long as it can form a uniform film, but is preferably a water-soluble polymer from the viewpoint of detailed description below. However, the present invention is not limited to this, and a water-insoluble polymer can be appropriately selected and used in combination as long as the effects of the present invention are not impaired.
Specific examples of various polymers that can be used as the binder for the protective layer include, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, polyvinyl acetate partially saponified product, ethylene- Vinyl alcohol copolymers, water-soluble cellulose derivatives, gelatin, starch derivatives, water-soluble polymers such as gum arabic, polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, cellophane And the like. These may be used in combination of two or more as required.

Among them, the binder polymer used for forming the protective layer has excellent adhesion to the recording layer, its surface (outermost surface) has low adhesion to other materials, and is easy in the development process after exposure. Polymers that can be removed easily are preferred.
From such a viewpoint, a water-soluble polymer is preferable as the binder component of the protective layer, and it is particularly preferable to use polyvinyl alcohol as a main component. Polyvinyl alcohol has an excellent film-forming property and a relatively low adhesion surface.

Polyvinyl alcohol (PVA) used as a preferred water-soluble polymer in the present invention is preferably a compound having a saponification degree of 85 to 99, preferably 91.0 to 99. If the degree of saponification is within this range, it may have any structure as long as it contains an unsubstituted vinyl alcohol unit for having a necessary oxygen barrier property and a low adhesion surface. That is, a part of the polyvinyl alcohol may be substituted with an ester, an ether and an acetal, or a part of the polyvinyl alcohol may be modified, and further may contain other copolymer components. Good.
Generally, the higher the degree of saponification of the PVA used, in other words, the higher the content of unsubstituted vinyl alcohol units, the higher the oxygen barrier property. For this reason, it is preferable that the protective layer which concerns on this invention has polyvinyl alcohol whose saponification degree is 91 mol% or more as a main component, for example.

  Polyvinyl alcohol having a polymerization degree in the range of 200 to 2400 is preferable. Such a polymer is also available as a commercial product, specifically, PVA-102, PVA-103, PVA-104, PVA-105, PVA-110, PVA-117, PVA manufactured by Kuraray Co., Ltd. -120, PVA-124, PVA-117H, PVA-135H, PVA-HC, PVA-617, PVA-624, PVA-706, PVA-613, PVA-CS, PVA-CST, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Of Gohsenol NL-05, NM-11, NM-14, AL-06, P-610, C-500, A-300, AH-17, JF-04, JF manufactured by Nihon Ventures & Poval Co., Ltd. -05, JF-10, JF-17, JF-17L, JM-05, JM-10, JM-17, JM-17L, JT-05, JT-13, JT- 5, and the like.

Furthermore, preferable water-soluble polymers used in the present invention include, for example, itaconic acid and maleic acid-modified carboxy-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol and the like, and these acid-modified polyvinyl alcohols are also more preferable. It can be preferably used.
Examples of the acid-modified polyvinyl alcohol that can be suitably used for forming the protective layer according to the present invention include, for example, KL-118, KM-618, KM-118, SK-5102, MP-102, and R- manufactured by Kuraray Co., Ltd. 2105, GOHSENAL CKS-50, T-HS-1, T-215, T-350, T-330, T-330H, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., AF- 17, AT-17, and the like.

The water-soluble polymer (preferably polyvinyl alcohol) is preferably contained in the range of 45 to 95% by mass, and in the range of 50 to 90% by mass with respect to the total solid content in the protective layer. Is more preferable. In the range of this content, excellent film-forming properties, high sensitivity and low adhesiveness resulting therefrom are achieved, and the effect of suppressing adhesion between laminated lithographic printing plate precursors is exhibited.
Only 1 type may be used for the water-soluble polymer which forms a protective layer, and multiple types may be used together according to the objective. For example, oxygen permeability can be controlled by using polyvinylpyrrolidone in combination with PVA. Even when a plurality of types of water-soluble polymers are used, the total content thereof is preferably in the above mass range.

In the protective layer of the present invention, various additives can be added to the protective layer according to the purpose in addition to the components described above within a range not impairing the effects of the present invention.
For example, a colorant (water-soluble dye) that is excellent in the transparency of light used for exposing the recording layer (infrared light in the present invention) and can efficiently absorb light having a wavelength that is not related to exposure. It may be added. Thereby, safelight aptitude can be improved without reducing sensitivity.

(Formation of protective layer)
-Preparation of coating solution for protective layer-
In forming the protective layer according to the present invention, organic resin fine particles (silica-coated fine particles), which are supplied in powder form, are directly added to a binder aqueous solution such as polyvinyl alcohol which is the main component of the protective layer. What is necessary is just to disperse. As a dispersion method, for example, a dispersion method using a known simple disperser such as a homogenizer, a homomixer, a ball mill, or a paint shaker may be employed.

At this time, a surfactant can be added as desired for the purpose of improving dispersion stability. As the surfactant used for improving the dispersion stability, any of a nonionic surfactant, an anionic surfactant, and a cationic surfactant can be used.
Examples of nonionic surfactants include polyethylene glycol alkyl ethers, alkenyl ethers, polyethylene glycol alkyl esters, polyethylene glycol aryl ethers, and the like. Anionic surfactants include alkyl or aryl sulfonate type, alkyl or aryl sulfate ester type, alkyl or aryl phosphate ester type, alkyl or aryl carboxylate type surfactants. Examples of the cationic surfactant include alkylamine salt type, alkylpyridinium salt type, and alkylammonium salt type surfactants.
More specifically, more specific examples of these surfactants are described in “Latest Surfactant Functional Creation / Material Development / Applied Technology” Teruo Horiuchi, edited by Toshiyuki Suzuki Can be mentioned.

  In addition, when using Mitsui Chemicals Chemie Pal series fine particles as silica-coated fine particles, these fine particles are supplied in a state of being dispersed in water. Therefore, these dispersions are directly added and stirred in the binder aqueous solution of the protective layer. A protective layer coating solution can be prepared.

-Formation of protective layer-
The protective layer in the present invention is obtained by applying a coating liquid for protective layer, which is obtained by blending the organic resin fine particles (silica-coated fine particles) prepared as described above and a binder, onto an oxygen barrier layer described later. Formed with.

Known additives such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film can be added to the coating solution for the protective layer.
Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, a known additive for improving the adhesion to the oxygen barrier layer and the temporal stability of the coating solution may be added to the coating solution.

  The method for coating the protective layer according to the present invention is not particularly limited, and a method described in US Pat. No. 3,458,311 or JP-A-55-49729 can be applied.

The coating amount of the protective layer according to the present invention ^is preferably ^{0.1g / m 2 ~3.0g / m 2} , further preferably ^{0.5g / m 2 ~2.0g / m 2} . In the range of this coating amount, the film strength of the protective layer is maintained well and the scratch resistance is excellent. Further, the transparency of light incident on the protective layer by exposure is also maintained.

(Oxygen barrier layer)
The oxygen barrier layer in the lithographic printing plate precursor according to the invention contains mica.
The oxygen barrier layer in the present invention is a layer mainly for preventing polymerization inhibition by oxygen in the polymerizable negative photosensitive layer, and has an oxygen barrier property. More specifically, the oxygen barrier layer in the present invention preferably has an oxygen permeability at 25 ° C.-60% RH 1 atm of 0.5 ml / m ² · day to 100 ml / m ² · day, A composition that achieves oxygen permeability is selected.

(mica)
Mica is used for the oxygen barrier layer in the present invention from the viewpoint of improving oxygen barrier properties.
The mica used in the present invention is, for example, a general formula: A (B, C) ₂ -5D ₄ O ₁₀ (OH, F, O) ₂ [where A is any of K, Na, Ca, B And C is any one of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. And mica groups such as natural mica and synthetic mica.

Examples of the mica that can be used in the present invention include muscovite, soda mica, phlogopite, biotite and sericite. As the synthetic mica, non-swelling mica such as fluor-phlogopite mica KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 (Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _{2 .5} (Si ₄ O ₁₀ ) F ₂ , Na or Li Teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , Montmorillonite Na or Li Hectorite (Na, Li) _1/8 Mg ₂ Swellable mica such as _{/ 5} Li _1/8 (Si ₄ O ₁₀ ) F ₂ . In addition, synthetic smectites are also useful.

In the present invention, among the mica, fluorine-based swellable mica is particularly useful. That is, this swellable synthetic mica has a laminated structure composed of unit crystal lattice layers with a thickness of about 100 to 150 nm (10 to 15 cm), and the substitution of metal atoms in the lattice is significantly larger than other viscosity minerals. As a result, the lattice layer is deficient in positive charge, and cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers to compensate for this. The cations present between these layers are called exchangeable cations and exchange with various cations. In particular, when the cation between the layers is Li ⁺ or Na ⁺ , the bond between the layered crystal lattices is weak because the ionic radius is small, and the layer swells greatly with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Swellable synthetic mica has a strong tendency and is useful in the present invention. In particular, swellable synthetic mica is preferably used.

  As the shape of mica used in the present invention, it has a plate-like particle shape. From the viewpoint of adsorption to organic resin fine particles, the thinner the better, the planar size of the coated surface. As long as the smoothness and actinic light transmittance are not impaired, the larger the better. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured from, for example, a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

  In the present invention, the particle diameter of the mica used for the oxygen barrier layer is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm in average major axis. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. Specifically, for example, the swellable synthetic mica that is a representative compound has a thickness of 1 to 50 nm and a surface size (major axis) of about 1 to 20 μm.

  The amount contained in the oxygen barrier layer of mica is preferably added in a ratio of 5 to 50 parts by mass with respect to 100 parts by mass of the binder.

(binder)
The binder constituting the oxygen barrier layer in the present invention is not particularly limited as long as it can form an oxygen barrier property and a uniform film, and the same binder as that constituting the protective layer can be used. . Here, as the binder constituting the oxygen barrier layer, it is preferable to use polyvinyl alcohol from the viewpoints of oxygen barrier property, development removability, heat resistant adhesive property, physical strength resistance, and the like. This polyvinyl alcohol is the same as the polyvinyl alcohol constituting the protective layer described above.

The binder (preferably, polyvinyl alcohol) is preferably contained in the range of 45 to 95% by mass and contained in the range of 50 to 90% by mass with respect to the total solid content in the oxygen barrier layer. More preferred. Within this content range, excellent film-forming properties and oxygen barrier properties can be obtained.
Only 1 type may be used for the water-soluble polymer which forms an oxygen interruption | blocking layer, and multiple types may be used together according to the objective. For example, oxygen permeability can be controlled by using polyvinylpyrrolidone in combination with PVA.

  In addition to the components described above, various additives can be added to the oxygen barrier layer in the present invention in accordance with the purpose within a range not impairing the effects of the present invention.

(Formation of oxygen barrier layer)
The protective layer in the present invention comprises a coating solution for oxygen barrier layer formed by blending a dispersion in which mica is dispersed and a binder (an aqueous solution in which a binder such as polyvinyl alcohol is dissolved) on the polymerizable negative photosensitive layer. It is formed by coating.

  An example of a general dispersion method of mica used for the oxygen barrier layer will be described. First, 5 to 10 parts by mass of the swellable mica mentioned above as a preferable mica is added to 100 parts by mass of water, and the mixture is thoroughly blended with water and swollen, and then dispersed by a disperser. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion of 2 to 15% by mass of mica dispersed by the above method is highly viscous or gelled, and has very good storage stability.

  Known additives such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film can be added to the coating solution for the oxygen barrier layer. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, a known additive for improving the adhesion to the polymerizable negative photosensitive layer and the temporal stability of the coating solution may be added to the coating solution.

  The method for coating the oxygen barrier layer according to the present invention is not particularly limited, and a method described in US Pat. No. 3,458,311 or JP-A-55-49729 can be applied.

The coating amount of the oxygen blocking layer according to the present invention ^is preferably ^{0.1g / m 2 ~2.0g / m 2} , further preferably 0.2g / ^{m 2} ~1.0g / m 2 . Within this coating amount range, the oxygen barrier layer has good oxygen barrier properties, and the transmittance of light incident on the protective layer by exposure is also maintained.

The hardness (H ₂ ) of the oxygen barrier layer according to the present invention is not particularly limited as long as it is the same as or higher than the hardness (H ₁ ) of the organic resin fine particles described above. When measured with a device connected to, it is 0.05 to 0.50 GPa, more preferably 0.10 to 0.40 Gpa, and the most preferable hardness is 0.15 to 0.30 Gpa.
In addition, this hardness can be suitably adjusted with the material of the material which comprises an oxygen interruption | blocking layer, a compounding quantity, etc.

(Polymerizable negative photosensitive layer)
The polymerizable negative photosensitive layer according to the present invention (hereinafter sometimes simply referred to as “photosensitive layer”) contains a sensitizing dye, a polymerization initiator, a polymerizable compound, and a binder polymer, and further if necessary. It is preferable that a colorant and other optional components are included.

Since the polymerizable negative photosensitive layer in the present invention is sensitive to a laser corresponding to a sensitizing dye, it can be exposed to various lasers useful for CTP. For example, in the case of using an infrared absorber as a sensitizing dye, the infrared absorber contained in the polymerizable negative photosensitive layer is highly sensitive to the irradiation (exposure) of an infrared laser and is in an electronically excited state. Electron transfer, energy transfer, heat generation (photothermal conversion function), etc. related to the electronically excited state act on the polymerization initiator coexisting in the photosensitive layer, causing a chemical change in the polymerization initiator to generate radicals.
In this case, the radical generation mechanism is as follows: 1. Heat generated by the photothermal conversion function of the infrared absorber thermally decomposes a polymerization initiator (for example, sulfonium salt) described later to generate radicals. 2. Excited electrons generated by the infrared absorber move to a polymerization initiator (for example, an active halogen compound) to cause radicals. For example, radicals are generated by electron transfer from a polymerization initiator (for example, a borate compound) to an excited infrared absorber. Then, the polymerizable compound causes a polymerization reaction by the generated radical, and the exposed portion is cured to become an image portion.

The lithographic printing plate precursor of the above embodiment is particularly suitable for plate making directly drawn with an infrared laser beam having a wavelength of 750 nm to 1400 nm because the polymerizable negative photosensitive layer contains an infrared absorber as a sensitizing dye. In addition, it can exhibit high image-forming properties as compared with conventional lithographic printing plate precursors.
Below, each component which comprises the polymeric negative photosensitive layer concerning this invention is demonstrated.

(Sensitizing dye)
The photosensitive layer according to the present invention contains a sensitizing dye that absorbs light of a predetermined wavelength that matches the exposure wavelength in laser exposure from the viewpoint of sensitivity.
The exposure of the wavelength that can be absorbed by the sensitizing dye accelerates the radical generation reaction of the polymerization initiator described later and the polymerization reaction of the polymerizable compound thereby. Examples of such a sensitizing dye include a known spectral sensitizing dye or dye, or a dye or pigment that absorbs light and interacts with a photopolymerization initiator. This sensitizing dye becomes a highly sensitive electronically excited state by laser exposure with a wavelength suitable for the sensitizing dye, and electron transfer, energy transfer, and the like related to the electronically excited state act on the polymerization initiator described later, and the polymerization initiator has a high level. It is useful for generating radicals by causing chemical changes with sensitivity.

  Depending on the wavelength of light absorbed by the sensitizing dye, the photosensitive layer in the present invention can be sensitive to various wavelengths from ultraviolet rays to visible rays and infrared rays. For example, when an infrared absorber is used as the sensitizing dye, it is sensitive to infrared light having a wavelength of 760 nm to 1200 nm. Further, by using a dye having a maximum absorption wavelength from 350 nm to 450 nm, it is sensitive to blue to purple visible light.

  Spectral sensitizing dyes or dyes preferred as sensitizing dyes used in the present invention are polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal). ), Cyanines (eg thiacarbocyanine, oxacarbocyanine), merocyanines (eg merocyanine, carbomerocyanine), thiazines (eg thionine, methylene blue, toluidine blue), acridines (eg acridine orange, chloroflavin) , Acriflavine), phthalocyanines (eg, phthalocyanine, metal phthalocyanine), porphyrins (eg, tetraphenylporphyrin, central metal-substituted porphyrin), chlorophylls (eg, chlorophyll) Chlorophyllin, central metal-substituted chlorophyll), metal complexes, anthraquinones (for example, anthraquinone), squalium (for example, squalium), and the like. For example, paragraph numbers [0188] to [ [0258] can be selected as appropriate and used as a sensitizing dye in the present invention.

Among these, the photosensitive layer in the present invention preferably contains an infrared absorber described in detail below as a sensitizing dye.
Infrared absorbers are in an electronically excited state with high sensitivity to infrared laser irradiation (exposure), and heat energy is generated by the photothermal conversion function in addition to the electron transfer and energy transfer related to the previous electron excited state. It is useful for causing a chemical change with high sensitivity by a polymerization initiator.
As an infrared absorber which is a particularly preferable sensitizing dye used in the present invention, a dye or pigment having an absorption maximum at a wavelength of 750 nm to 1400 nm is preferably exemplified.

As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.
Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, 58-181690, JP-A-58-194595, etc., methine dyes, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59- No. 73996, JP-A-60-52940, JP-A-60-63744 and the like, Naphthoquinone dyes described in JP-A-58-112792, etc., British Patent 434,875 And cyanine dyes.

Also, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is preferably used, and a substituted arylbenzo (thio) pyrylium salt described in US Pat. No. 3,881,924, Trimethine thiapyrylium salts described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363, 59-84248 Nos. 59-84249, 59-146063, 59-146061, pyranlium compounds, cyanine dyes described in JP-A-59-216146, U.S. Pat. No. 4,283,475 The pentamethine thiopyrylium salts described above and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are also preferably used. . Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).
Other preferable examples of the infrared absorbing dye in the invention include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferred, and particularly preferred examples include cyanine dyes represented by the following general formula (a).

In general formula (a), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom including a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.
In the group shown below, X _a ^- is Z _a which will be described below ^- has the same definition as, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom Represents.

R ¹ and R ² each independently represent a hydrocarbon group having 1 to 12 carbon atoms. In view of storage stability of the coating solution for the photosensitive layer, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring. Alternatively, it is particularly preferable that a 6-membered ring is formed.

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z _a ⁻ represents a counter anion. However, when the cyanine dye represented by formula (a) has an anionic substituent in the structure thereof, Z _a is does not require charge neutralization ^- is not necessary. Preferred Z _a ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of the storage stability of the coating solution for the photosensitive layer. , Hexafluorophosphate ions, and aryl sulfonate ions.

Specific examples of the cyanine dye represented by formula (a) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. Can do.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.
However, a counter ion that does not contain a halogen ion is particularly preferable.

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. Within this preferred particle size range, excellent dispersion stability of the pigment in the photosensitive layer can be obtained, and a uniform photosensitive layer can be obtained.

  As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

  When these infrared absorbers are used in the photosensitive layer according to the present invention, they may be added to the same layer as other components, or another layer may be provided and added thereto.

  The addition amount of these sensitizing dyes, preferably infrared absorbers, is 0.01 to 50% by mass with respect to the total solid content constituting the photosensitive layer from the viewpoint of uniformity in the photosensitive layer and durability of the photosensitive layer. It is preferably in the range of 0.1 to 10% by mass, particularly preferably 0.5 to 10% by mass when a dye is used as a sensitizing dye, and particularly when a pigment is used. Preferably it can add in the ratio of 0.1-10 mass%.

(Polymerization initiator)
The polymerization initiator used in the present invention has a function of initiating and advancing the curing reaction of a polymerizable compound described later, and is a thermal decomposition type radical generator that decomposes by heat to generate radicals, and excitation of an infrared absorber. An electron transfer type radical generator that accepts electrons to generate radicals, or an electron transfer type radical generator that generates electrons by transferring electrons to an excited infrared absorber. Any compound may be used as long as it is generated. For example, onium salts, active halogen compounds, oxime ester compounds, borate compounds and the like can be mentioned. These may be used in combination. In the present invention, an onium salt is preferable, and a sulfonium salt is particularly preferable.
Examples of the sulfonium salt polymerization initiator suitably used in the present invention include onium salts represented by the following general formula (I).

In general formula (I), R ¹¹ , R ¹² and R ¹³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. (Z ¹¹ ) ⁻ represents a counter ion selected from the group consisting of halogen ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, carboxylate ion, and sulfonate ion, preferably perchloric acid Ions, hexafluorophosphate ions, carboxylate ions, and aryl sulfonate ions.

  Specific examples ([OS-1] to [OS-12]) of the onium salt represented by the general formula (I) are shown below, but are not limited thereto.

  In addition to the above, specific aromatic sulfonium salts described in JP-A Nos. 2002-148790, 2002-148790, 2002-350207, and 2002-6482 are also preferably used.

  In the present invention, in addition to the sulfonium salt polymerization initiator, other polymerization initiators (other radical generators) can be used. Other radical generators include onium salts other than sulfonium salts, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, quinonediazides, active halogen compounds, oxime ester compounds, triaryls. Examples thereof include monoalkyl borate compounds. Among them, onium salts are preferable because of their high sensitivity. Moreover, these polymerization initiators (radical generators) can be used in combination with the sulfonium salt polymerization initiator as an essential component.

Other onium salts that can be suitably used in the present invention include iodonium salts and diazonium salts. In the present invention, these onium salts function not as acid generators but as radical polymerization initiators.
Other onium salts in the present invention include onium salts represented by the following general formulas (II) and (III).

In the general formula (II), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a carbon atom having 12 or less carbon atoms. An aryloxy group is mentioned. (Z ²¹ ) ⁻ represents a counter ion having the same meaning as (Z ¹¹ ) ⁻ .

In the general formula (III), Ar ³¹ represents an aryl group having 20 or less carbon atoms which may have a substituent. Preferred examples of the substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, an aryloxy group having 12 or less carbon atoms, and 12 or less carbon atoms. Examples thereof include an alkylamino group, a dialkylamino group having 12 or less carbon atoms, an arylamino group having 12 or less carbon atoms, or a diarylamino group having 12 or less carbon atoms. (Z ³¹ ) ⁻ represents a counter ion having the same meaning as (Z ¹¹ ) ⁻ .

  In the present invention, onium salts represented by general formula (II) ([OI-1] to [OI-10]) and onium salts represented by general formula (III) ([ Specific examples of ON-1] to [ON-5] are given below, but are not limited thereto.

  Specific examples of onium salts that can be suitably used as a polymerization initiator (radical generator) in the present invention include those described in JP-A No. 2001-133696.

  The polymerization initiator (radical generator) used in the present invention preferably has a maximum absorption wavelength of 400 nm or less, and more preferably 360 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the lithographic printing plate precursor can be handled under white light.

  In the present invention, the total content of the polymerization initiator is from 0.1 to 50% by mass, preferably from 0. It is 5-30 mass%, Most preferably, it is 1-20 mass%.

As a polymerization initiator in this invention, only 1 type may be used and 2 or more types may be used together. When two or more polymerization initiators are used in combination, for example, a plurality of suitably used sulfonium salt polymerization initiators may be used, or a sulfonium salt polymerization initiator and another polymerization initiator may be used in combination. Also good.
When the sulfonium salt polymerization initiator and another polymerization initiator are used in combination, the content ratio (mass ratio) is preferably 100/1 to 100/50, more preferably 100/5 to 100/25.
Moreover, a polymerization initiator may be added to the same layer as other components, or another layer may be provided and added thereto.

  When a highly sensitive sulfonium salt polymerization initiator, which is preferable as a polymerization initiator, is used for the photosensitive layer in the present invention, the radical polymerization reaction proceeds effectively, and the strength of the formed image portion becomes very high. Therefore, combined with the high oxygen blocking function of the protective layer described later, a lithographic printing plate having high image area strength can be produced, and as a result, printing durability is further improved. In addition, since the sulfonium salt polymerization initiator itself is excellent in stability over time, even when the produced lithographic printing plate precursor is stored, the occurrence of an undesirable polymerization reaction is effectively suppressed. Will also have.

(Polymerizable compound)
The polymerizable compound used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one ethylenically unsaturated bond, preferably two or more. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, that is, dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.
Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.
Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.
Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, JP-A-59-5241. Those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

  In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane compound containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula to a polyisocyanate compound having two or more isocyanate groups. Can be mentioned.

^{_{CH 2 = C (R a)}} COOCH 2 CH (R b) OH ··· formula (wherein, ^{R a} and ^{R b} represent H or CH _3.)

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765, JP-B-58-49860, JP-B-56-17654, Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable. Further, by using addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238, It is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-A-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337 and JP-B-1-40336, vinylphosphonic acid compounds described in JP-A-2-25493, and the like can also be mentioned. . In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combined use, and addition amount can be arbitrarily set according to the final performance design. For example, it is selected from the following viewpoints. From the viewpoint of photosensitive speed, a structure having a high unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image portion, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic ester, methacrylic ester, styrenic compound, A method of adjusting both photosensitivity and strength by using a vinyl ether compound) is also effective. A compound having a large molecular weight or a compound having high hydrophobicity is excellent in photosensitive speed and film strength, but is not preferable in terms of development speed and precipitation in a developer. In addition, the selection and use method of the addition polymerization compound is also an important factor for compatibility and dispersibility with other components in the photosensitive layer composition (for example, binder polymer, initiator, colorant, etc.). For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination.
In the lithographic printing plate precursor according to the invention, a specific structure may be selected for the purpose of improving adhesion to a support or a protective layer described later.

Regarding the content of the addition polymerizable compound in the photosensitive layer composition, the solid content in the photosensitive layer composition is considered from the viewpoints of sensitivity, occurrence of phase separation, adhesiveness of the photosensitive layer, and precipitation from the developer. The amount is preferably 5 to 80% by mass, more preferably 40 to 75% by mass.
These may be used alone or in combination of two or more. In addition, as for the method of using the addition polymerizable compound, an appropriate structure, blending, and addition amount can be arbitrarily selected from the viewpoints of polymerization inhibition with respect to oxygen, resolution, fogging property, refractive index change, surface tackiness, and the like. Furthermore, in the lithographic printing plate precursor according to the invention, layer constitution / coating methods such as undercoating and overcoating can be carried out.

(Binder polymer)
The binder polymer used in the present invention is contained from the viewpoint of improving the film property, and various types can be used as long as it has a function of improving the film property. Especially, as a binder polymer suitable in this invention, it is a binder polymer which has a repeating unit represented by the following general formula (i). Hereinafter, the binder polymer having the repeating unit represented by the general formula (i) is appropriately referred to as a specific binder polymer and will be described in detail.

(In the general formula (i), R ¹ represents a hydrogen atom or a methyl group, and R ² contains two or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. And represents a linking group having a total atom number of 2 to 82. A represents an oxygen atom or —NR ³ —, and R ³ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. N represents an integer of 1 to 5.)

First, R ¹ in the general formula (i) represents a hydrogen atom or a methyl group, and a methyl group is particularly preferable.

The linking group represented by R ² in the general formula (i) includes two or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. The number is 2 to 82, preferably 2 to 50, more preferably 2 to 30. The total number of atoms shown here refers to the number of atoms including the substituent when the linking group has a substituent. More specifically, the number of atoms constituting the main skeleton of the linking group represented by R ² is preferably 1-30, more preferably 3-25, and 4-20. More preferred is 5-10. The “main skeleton of the linking group” in the present invention refers to an atom or an atomic group used only for linking A and the terminal COOH in the general formula (i), and particularly when there are a plurality of linking paths. Refers to an atom or atomic group that constitutes a path with the smallest number of atoms used. Therefore, when a linking group has a ring structure, the number of atoms to be included differs depending on the linking site (for example, o-, m-, p-, etc.).

More specific examples include alkylene, substituted alkylene, arylene, substituted arylene, and the like, and a structure in which a plurality of these divalent groups are linked by an amide bond or an ester bond may be used.
Examples of the linking group having a chain structure include ethylene and propylene. A structure in which these alkylenes are linked through an ester bond can also be exemplified as a preferable example.

Among these, the linking group represented by R ² in the general formula (i) is preferably an (n + 1) -valent hydrocarbon group having an aliphatic cyclic structure having 3 to 30 carbon atoms. More specifically, a compound having an aliphatic cyclic structure such as cyclopropane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, dicyclohexyl, tercyclohexyl, norbornane and the like, which may be substituted one or more by any substituent. And (n + 1) valent hydrocarbon groups by removing (n + 1) hydrogen atoms on an arbitrary carbon atom constituting. R ² preferably has 3 to 30 carbon atoms including a substituent.

One or more arbitrary carbon atoms of the compound constituting the aliphatic cyclic structure may be replaced with a heteroatom selected from a nitrogen atom, an oxygen atom, or a sulfur atom. In terms of printing durability, R ² is a condensed polycyclic aliphatic hydrocarbon, a bridged cyclic aliphatic hydrocarbon, a spiro aliphatic hydrocarbon, an aliphatic hydrocarbon ring assembly (a plurality of rings are connected by a bond or a linking group). A (n + 1) -valent hydrocarbon group having an aliphatic cyclic structure which may have a substituent of 5 to 30 carbon atoms containing two or more rings. . Also in this case, the carbon number includes the carbon atom of the substituent.

As the linking group represented by R ² , those having 5 to 10 atoms constituting the main skeleton of the linking group are particularly preferable, and are structurally a chain structure, and an ester bond in the structure. And those having a cyclic structure as described above are preferred.

Examples of the substituent that can be introduced into the linking group represented by R ² include monovalent nonmetallic atomic groups other than hydrogen, such as halogen atoms (—F, —Br, —Cl, —I), hydroxyl groups. Group, alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N- Diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy Group, arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′- Arylureido group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N '-Alkyl-N-arylureido group, N', N'-dialkyl-N-alkylureido group, N ', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N '-Aryl-N-arylureido group, N', N'-diaryl-N-alkylureido group, N ', N'-diaryl-N-arylureido group, N'-a Kill-N′-aryl-N-alkylureido group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group and its conjugate base group, Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, Alkylsulfinyl , An arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group (-SO 3 _H) and its conjugated base group, alkoxy sulfonyl group, aryloxy sulfonyl group, sulfinamoyl group, N- alkylsulfinamoyl group, N, N -Dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, N-acylsulfamoyl group and its conjugate base group , N- alkylsulfonylsulfamoyl group _(-SO 2 NHS ₂ (alkyl)) and its conjugated base group, N- aryl sulfonylsulfamoyl group _{(-SO 2 NHSO 2 (aryl)} ) and its conjugated base group, N- alkylsulfonylcarbamoyl group _(-CONHSO 2 _(alkyl)) and Its conjugated base group, N-arylsulfonylcarbamoyl group (—CONHSO ₂ (aryl)) and its conjugated base group, alkoxysilyl group (—Si (Oalkyl) ₃ ), aryloxysilyl group (—Si (Oaryl) ₃ ), Hydroxysilyl group (—Si (OH) ₃ ) and its conjugate base group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group, dialkylphosphono group (—PO ₃ (alkyl) ₂ ), diarylphosphono group (—PO ₃ (aryl) ₂ ), alkylarylphosphono group (—PO ₃ (a lkyl) (aryl)), monoalkylphosphono group (—PO ₃ H (alkyl)) and its conjugate base group, monoarylphosphono group (—PO ₃ H (aryl)) and its conjugate base group, phosphonooxy group ( -OPO ₃ H ₂₎ and its conjugated base group, a dialkyl phosphono group _{(-OPO 3 (alkyl) 2)} , diaryl phosphono group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphono group (- _{OPO 3 (alkyl) (aryl)} ), monoalkyl phosphono group _(-OPO 3 H _(alkyl)) and its conjugated base group, monoarylphosphono group _(-OPO 3 H _(aryl)) and its conjugate base group, a cyano group, a nitro group, a dialkyl boryl group (-B _{(alkyl) 2),} Jiariruboriru group (-B ( _RYL) 2), alkyl aryl boryl group (-B (alkyl) (aryl) ), dihydroxy boryl group (-B _{(OH) 2)} and its conjugated base group, an alkyl hydroxy boryl group (-B (alkyl) (OH) ) And conjugated base groups thereof, arylhydroxyboryl groups (-B (aryl) (OH)) and conjugated base groups thereof, aryl groups, alkenyl groups and alkynyl groups.

  In the lithographic printing plate precursor according to the invention, although depending on the design of the photosensitive layer, a substituent having a hydrogen atom capable of hydrogen bonding, particularly a substituent having an acid dissociation constant (pKa) smaller than that of a carboxylic acid is , Because it tends to lower the printing durability. On the other hand, hydrophobic substituents such as halogen atoms, hydrocarbon groups (alkyl groups, aryl groups, alkenyl groups, alkynyl groups), alkoxy groups, aryloxy groups and the like are more preferable because they tend to improve printing durability. When the cyclic structure is a monocyclic aliphatic hydrocarbon having 6 or less members such as cyclopentane or cyclohexane, it preferably has such a hydrophobic substituent. If possible, these substituents may be bonded to each other or with a substituted hydrocarbon group to form a ring, and the substituent may be further substituted.

When A in the general formula (i) is NR ³ —, R ³ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ³ include an alkyl group, an aryl group, an alkenyl group, and an alkynyl group.
Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isopropyl, isobutyl, sec-butyl, 1 carbon number such as tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-norbornyl group Up to 10 linear, branched or cyclic alkyl groups.
Specific examples of the aryl group include carbon having one heteroatom selected from the group consisting of an aryl group having 1 to 10 carbon atoms such as a phenyl group, a naphthyl group, and an indenyl group, a nitrogen atom, an oxygen atom, and a sulfur atom. Examples include heteroaryl groups of 1 to 10, such as furyl, thienyl, pyrrolyl, pyridyl, and quinolyl groups.
Specific examples of the alkenyl group include those having 1 to 10 carbon atoms such as vinyl group, 1-propenyl group, 1-butenyl group, 1-methyl-1-propenyl group, 1-cyclopentenyl group, 1-cyclohexenyl group and the like. A linear, branched, or cyclic alkenyl group is mentioned.
Specific examples of the alkynyl group include alkynyl groups having 1 to 10 carbon atoms such as ethynyl group, 1-propynyl group, 1-butynyl group, and 1-octynyl group. The substituent that R ³ may have is the same as those exemplified as the substituent that R ² can introduce. The number of carbon atoms of ^{R 3} is 1 to 10 including the carbon number of the substituent.

  A in the general formula (i) is preferably an oxygen atom or —NH— because synthesis is easy.

  N in the general formula (i) represents an integer of 1 to 5, and is preferably 1 in terms of printing durability.

  Although the preferable specific example of the repeating unit represented by general formula (i) below is shown, this invention is not limited to these.

  One type of repeating unit represented by the general formula (i) may be contained in the binder polymer, or two or more types may be contained. The specific binder polymer in the present invention may be a polymer composed only of the repeating unit represented by the general formula (i), but is usually used as a copolymer in combination with other copolymerization components. The total content of the repeating unit represented by the general formula (i) in the copolymer is appropriately determined depending on its structure, the design of the photosensitive layer composition, etc., but preferably 1 to 99 with respect to the total molar amount of the polymer component. It is contained in the range of mol%, more preferably 5 to 40 mol%, still more preferably 5 to 20 mol%.

  As a copolymerization component in the case of using as a copolymer, a conventionally well-known thing can be used without a restriction | limiting, if it is a monomer which can be radically polymerized. Specific examples include monomers described in “Polymer Data Handbook—Basic Edition” (Edition of Polymer Society, Bafukan, 1986). One type of such copolymerization component may be used, or two or more types may be used in combination.

  The molecular weight of the specific binder polymer in the present invention is appropriately determined from the viewpoint of image formability and printing durability. The molecular weight is preferably in the range of 2,000 to 1,000,000, more preferably 5,000 to 500,000, and still more preferably 10,000 to 200,000.

  The binder polymer used in the present invention may be a specific binder polymer alone, or may be used as a mixture by combining one or more other binder polymers. The binder polymer used in combination is used in the range of 1 to 60% by mass, preferably 1 to 40% by mass, and more preferably 1 to 20% by mass with respect to the total mass of the binder polymer component. As the binder polymer that can be used in combination, a conventionally known binder polymer can be used without limitation, and specifically, an acrylic main chain binder, a urethane binder, or the like often used in the industry is preferably used.

The total amount of the specific binder polymer in the photosensitive layer composition and the binder polymer that may be used in combination can be appropriately determined, but is usually 10 to 90 with respect to the total mass of the nonvolatile components in the photosensitive layer composition. It is mass%, Preferably it is 20-80 mass%, More preferably, it is the range of 30-70 mass%.
Moreover, as an acid value (meg / g) of such a binder polymer, it is preferable that it is the range of 2.00-3.60.

-Other binder polymers that can be used together-
The other binder polymer that can be used in combination with the specific binder polymer is preferably a binder polymer having a radical polymerizable group.
The radical polymerizable group is not particularly limited as long as it can be polymerized by radicals, but α-substituted methylacrylic group [—OC (═O) —C (—CH ₂ Z) ═CH ₂ , Z = A hydrocarbon group starting from a hetero atom], an acryl group, a methacryl group, an allyl group, and a styryl group. Among these, an acryl group and a methacryl group are preferable.
The content of the radical polymerizable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 1 g per binder polymer from the viewpoint of sensitivity and storage stability. It is 10.0 mmol, More preferably, it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol.

  Further, the other binder polymer that can be used in combination is preferably one having an alkali-soluble group. The content of alkali-soluble groups in the binder polymer (acid value by neutralization titration) is preferably from 0.1 to 3.0 mmol, more preferably from 1 to 3.0 g of binder polymer, from the viewpoints of precipitation of developing residue and printing durability. Is 0.2 to 2.0 mmol, most preferably 0.45 to 1.0 mmol.

  The mass average molecular weight of such a binder polymer is preferably from 2,000 to 1,000,000, more preferably from 10,000 to 300, from the viewpoints of film properties (press life) and solubility in a coating solvent. In the range of 20,000 to 200,000.

Further, the glass transition point (Tg) of such a binder polymer is preferably 70 to 300 ° C., more preferably 80 to 250 ° C., and most preferably 90 to 90 ° C. from the viewpoints of storage stability, printing durability, and sensitivity. It is in the range of 200 ° C.
As a means for increasing the glass transition point of the binder polymer, the molecule preferably contains an amide group or an imide group, and particularly preferably contains a methacrylamide or a methacrylamide derivative.

In the present invention, further, Japanese Patent Publication No. 7-12004, Japanese Patent Publication No. 7-120041, Japanese Patent Publication No. 7-120042, Japanese Patent Publication No. 8-12424, Japanese Patent Publication No. 63-287944, Japanese Patent Publication No. 63-287947, Urethane-based binder polymers containing acid groups described in JP-A-1-2717741, Japanese Patent Application No. 11-352691 and the like can also be used. Since the binder polymer is very excellent in strength, it is advantageous in terms of printing durability and suitability for low exposure.
A binder having an amide group described in JP-A No. 11-171907 is suitable because it has excellent developability and film strength.

Consider again!
In addition, polyvinyl pyrrolidone, polyethylene oxide, and the like are useful as the water-soluble linear organic polymer. In order to increase the strength of the cured film, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) propane and epichlorohydrin are also useful. These linear organic high molecular polymers can be mixed in an arbitrary amount in the entire composition. However, when it exceeds 90% by mass, a favorable result is not given in terms of the strength of the formed image. Preferably it is 30-85 mass%. In addition, the photopolymerizable compound having an ethylenically unsaturated double bond and the linear organic polymer are preferably in the range of 1/9 to 7/3 by mass ratio. In a preferred embodiment, a binder polymer that does not require water and is soluble in alkali is used. By doing so, an organic solvent which is not environmentally preferable is not used as a developing solution, or it can restrict | limit to the very small usage-amount. In such a method of use, the acid value of the binder polymer (the acid content per gram of the polymer expressed as a chemical equivalent number) and the molecular weight are appropriately selected from the viewpoint of image strength and developability. The preferred acid value is 0.4 to 3.0 meq / g, and the preferred molecular weight is in the range of 3000 to 500,000 in terms of mass average molecular weight, more preferably the acid value is 0.6 to 2.0 and the molecular weight is It is in the range of 10,000 to 300,000.

(Other ingredients)
In addition to the above basic components, the photosensitive layer according to the present invention may further contain other components suitable for its use and production method. Hereinafter, preferred additives will be exemplified.

-Colorant-
A dye or a pigment may be added to the photosensitive layer according to the present invention for the purpose of coloring. As a result, it is possible to improve the so-called plate inspection property such as the visibility of the image after plate making as a printing plate and the suitability of the image density measuring machine. Specific examples of the colorant include pigments such as phthalocyanine pigments, azo pigments, carbon black, and titanium oxide, and dyes such as ethyl violet, crystal violet, azo dyes, anthraquinone dyes, and cyanine dyes. Among them, a cationic dye is preferable.
The addition amount of the dye and pigment as the colorant is preferably about 0.5% by mass to about 5% by mass with respect to the non-volatile components in the total photosensitive layer composition.

-Polymerization inhibitor-
In the photosensitive layer according to the present invention, it is desirable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the polymerizable compound having an ethylenically unsaturated double bond, that is, the polymerizable compound. . Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxyamine primary cerium salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the nonvolatile component in the photosensitive layer composition. Further, if necessary, a higher fatty acid derivative such as behenic acid or behenic acid amide may be added in order to prevent polymerization inhibition by oxygen, and may be unevenly distributed on the surface of the layer in the course of drying after coating. The addition amount of the higher fatty acid derivative is preferably from about 0.5% by mass to about 10% by mass with respect to the non-volatile components in the photosensitive layer composition.

-Other additives-
Furthermore, the photosensitive layer according to the present invention may be added with known additives such as inorganic fillers for improving the physical properties of the cured film, other plasticizers, and oil-sensitizing agents that can improve the ink deposition on the surface of the photosensitive layer. An agent may be added. Examples of plasticizers include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerin, and addition polymerization with binder polymer. Generally, it can be added in a range of 10% by mass or less with respect to the total mass with the compound.
In addition, in the photosensitive layer according to the present invention, in order to enhance the effect of heating and exposure after development for the purpose of improving the film strength (printing durability) described later, a UV initiator, a thermal crosslinking agent, etc. are added. Can also be done.

[Support]
Examples of the support in the present invention include paper, a polyester film or an aluminum plate. Among them, a surface having good dimensional stability, relatively inexpensive, and having excellent hydrophilicity and strength by surface treatment as necessary. An aluminum plate that can be provided is more preferred. A composite sheet in which an aluminum sheet is bonded on a polyethylene terephthalate film as described in Japanese Patent Publication No. 48-18327 is also preferable.

  The aluminum plate as the most preferable support in the present invention is a metal plate mainly composed of dimensionally stable aluminum, and contains pure aluminum plate, aluminum as a main component, and a trace amount of foreign elements. An alloy plate or aluminum (alloy) is selected from a laminated or vapor-deposited plastic film or paper. In the following description, the above-mentioned support made of aluminum or an aluminum alloy is generically used as an aluminum support. Examples of the foreign element contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of the foreign element in the alloy is 10% by mass or less. In the present invention, a pure aluminum plate is suitable, but since completely pure aluminum is difficult to manufacture in the refining technique, it may contain a slightly different element. Thus, the composition of the aluminum plate applied to the present invention is not specified, and it is a conventionally known material such as JIS A 1050, JIS A 1100, JIS A 3103, JIS A 3005, etc. Can be used as appropriate.

Moreover, the thickness of the aluminum support body used for this invention is about 0.1 mm-about 0.6 mm. This thickness can be appropriately changed depending on the size of the printing press, the size of the printing plate, and the user's desire.
Such a support (aluminum support) is subjected to a surface treatment described later to be hydrophilized.

(Roughening treatment)
Examples of the roughening treatment method include mechanical roughening, chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. Furthermore, the electrochemical surface roughening method in which the surface is electrochemically roughened in hydrochloric acid or nitric acid electrolyte solution, the aluminum surface is scratched with a metal wire, the wire brush grain method, the surface of the aluminum is polished with a polishing ball and an abrasive. A mechanical graining method such as a pole grain method, a brush grain method in which the surface is roughened with a nylon brush and an abrasive, can be used, and the above roughening methods can be used alone or in combination. Among them, a method usefully used for roughening is an electrochemical method in which roughening is chemically performed in hydrochloric acid or nitric acid electrolyte, and a suitable amount of electricity during anode is 50 C / dm ^{2 to} 400 C / dm ² . It is a range. More specifically, in the electrolytic solution containing from 0.1 to 50% hydrochloric acid or nitric acid, the temperature 20 to 80 ° C., for 1 second to 30 minutes, alternating at a current density of 100C ^/ dm ² ~400C ^/ dm 2 It is preferable to perform direct current electrolysis.

  The roughened aluminum support may be chemically etched with acid or alkali. Etching agents suitably used are caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, and the like. Preferred ranges of concentration and temperature are 1 to 50% and 20%, respectively. ~ 100 ° C. Pickling is performed to remove dirt (smut) remaining on the surface after etching. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borohydrofluoric acid and the like are used. In particular, as a method for removing smut after the electrochemical surface roughening treatment, contact with 15 to 65 mass% sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739 is preferable. And the alkali etching method described in Japanese Patent Publication No. 48-28123. After the treatment as described above, the method and conditions are not particularly limited as long as the surface roughness Ra of the treated surface is about 0.2 to 0.5 μm.

(Anodizing treatment)
The aluminum support that has been treated as described above to form an oxide layer is then anodized.
In the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid, or an aqueous solution of boric acid / sodium borate is used as a main component of the electrolytic bath singly or in combination. In this case, the electrolyte solution may of course contain at least components normally contained in at least an Al alloy plate, an electrode, tap water, groundwater, and the like. Further, the second and third components may be added. Here, the second and third components are, for example, metal ions such as Na, K, Mg, Li, Ca, Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and ammonium ions. Examples include cations, nitrate ions, carbonate ions, chloride ions, phosphate ions, fluorine ions, sulfite ions, titanate ions, silicate ions, borate ions, and the like, and the concentration is 0 to 10,000 ppm. May be included. There are no particular limitations on the conditions of the anodizing treatment, but the treatment is preferably performed by direct current or alternating current electrolysis at a treatment liquid temperature of 10 to 70 ° C. and a current density of 0.1 to 40 A / m ² at 30 to 500 g / liter. . The thickness of the formed anodic oxide film is in the range of 0.5 to 1.5 μm. Preferably it is the range of 0.5-1.0 micrometer. The support produced by the above treatment is treated so that the pore diameter of the micropores existing in the anodized film is in the range of 5 to 10 nm and the pore density is in the range of 8 × 10 ¹⁵ to 2 × 10 ¹⁶ pieces / m ^2. It is preferred that the conditions are selected.

A widely known method can be applied as the hydrophilic treatment on the surface of the support. As a particularly preferable treatment, a hydrophilic treatment with silicate or polyvinylphosphonic acid is performed. A film | membrane is formed by 2-40 mg / m < ² > as Si or P element amount, More preferably, it is 4-30 mg / m < ² >. The coating amount can be measured by fluorescent X-ray analysis.

  The hydrophilization treatment is carried out by applying an anodized film to an aqueous solution containing 1 to 30% by mass, preferably 2 to 15% by mass of alkali metal silicate or polyvinylphosphonic acid, and having a pH of 10 to 13 at 25 ° C. This is carried out by immersing the aluminum support on which is formed, for example, at 15 to 80 ° C. for 0.5 to 120 seconds.

  As the alkali metal silicate used for the hydrophilization treatment, sodium silicate, potassium silicate, lithium silicate, or the like is used. Examples of the hydroxide used for increasing the pH of the aqueous alkali metal silicate solution include sodium hydroxide, potassium hydroxide, and lithium hydroxide. In addition, you may mix | blend alkaline-earth metal salt or Group IVB metal salt with said process liquid. Alkaline earth metal salts include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate, and water-soluble substances such as sulfate, hydrochloride, phosphate, acetate, oxalate, and borate. Salt. Group IVB metal salts include titanium tetrachloride, titanium trichloride, potassium fluoride titanium, potassium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride, zirconium tetrachloride, etc. Can be mentioned.

  Alkaline earth metal salts or Group IVB metal salts can be used alone or in combination of two or more. A preferable range of these metal salts is 0.01 to 10% by mass, and a more preferable range is 0.05 to 5.0% by mass. Silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective. Surface obtained by combining a support with electrolytic grains as disclosed in JP-B-46-27481, JP-A-52-58602, JP-A-52-30503, and the above anodizing treatment and hydrophilization treatment Processing is also useful.

(Backside treatment of support)
In the lithographic printing plate precursor according to the invention, the back surface of the support is preferably modified for the purpose of further improving scratch resistance. As a method for modifying the back surface of the support, for example, when an aluminum support is used, a method of uniformly forming an anodic oxide film on the entire back surface as in the case of the photosensitive layer side or a back coat layer is formed. The method of doing is mentioned. The film-forming amount in the case of taking a method of forming an anodic oxide film, is preferably 0.6 g / ^{m 2} or more, preferably in the range of 0.7~6g / ^{m 2.} Of these, a method of providing a backcoat layer is more effective and preferable. Hereinafter, these back surface processing methods will be described.

1. Method for Forming Back Anodic Oxide Film First, a method for uniformly forming an anodized film of 0.6 g / m ² or more on the entire back surface of the aluminum support in the same manner as the photosensitive layer side will be described. The formation of the anodized film is performed by the same means as described in the support surface treatment. The thickness of the anodized film provided on the back surface of the support is effective if it is 0.6 g / m ² or more, and the upper limit is not particularly limited from the viewpoint of performance. Considering energy, time required for formation, etc., it may be about 6 g / m ² , and a practical preferable film amount is 0.7 g to 6 g / m ² , and a more preferable range is 1.0 g to 3 g / m ^2. a m ^2.
The amount of the anodic oxide film can be converted by measuring the peak of Al ₂ O ₃ using fluorescent X-rays and using a calibration curve of the peak height and the film amount.

In the present invention, an anodic oxide film is provided on the entire surface of the aluminum support, and the amount thereof is 0.6 g / m ² or more. This means that the anode on the side opposite to the photosensitive layer of the aluminum support in the lithographic printing plate precursor The center part of the surface having the oxide film, and the end part 5 cm from both ends in the direction (Transverse Direction) passing through the center part and orthogonal to the processing direction (Machine Direction) are both 0.6 g of anodic oxide film amount. / M ² or more.

2. Next, a method for forming a backcoat layer on the back surface of the aluminum support will be described. As the back coat layer in the present invention, any composition may be used, and in particular, a metal oxide obtained by hydrolysis and polycondensation of an organometallic compound or an inorganic metal compound described in detail below. A back coat layer comprising a colloidal silica sol or a back coat layer comprising an organic resin film is preferred.

2-1. Back Coat Layer Containing Metal Oxide and Colloidal Silica Sol As a first preferred embodiment of the back coat layer in the present invention, there is a back coat layer containing a metal oxide and a colloidal silica sol.
More specifically, it is formed by a so-called sol-gel reaction solution in which an organometallic compound or an inorganic metal compound is hydrolyzed with a catalyst such as an acid or an alkali and a polycondensation reaction in water and an organic solvent. A backcoat layer is preferred.
Examples of the organic metal compound or inorganic metal compound used for forming the back coat layer include metal alkoxide, metal acetylacetonate, metal acetate, metal oxalate, metal nitrate, metal sulfate, metal carbonate, and metal oxychloride. , Metal chlorides, and condensates obtained by oligomerizing these by partial hydrolysis.
The metal alkoxide is represented by a general formula of M (OR) _n (M is a metal element, R is an alkyl group, and n is an oxidation number of the metal element). As specific examples, for example, Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ , Al (OCH ₃ ) ₃ , Al ( OC ₂ H ₅ ) ₃ , Al (OC ₃ H ₇ ) ₃ , Al (OC ₄ H ₉ ) ₃ , B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ , B (OC ₃ H ₇ ) ₃ , B (OC ₄ H ₉ ) ₃ , Ti (OCH ₃ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₃ H ₇ ) ₄ , Ti (OC ₄ H ₉ ) ₄ , Zr (OCH ₃ ) ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (OC ₃ H ₇ ) ₄ , Zr (OC ₄ H ₉ ) _{4 and the} like can be mentioned. In addition, for example, Ge, Li, Na, Fe, Ga, Mg, P , Alkoxides such as Sb, Sn, Ta, and V. In addition, mono-substituted silicon such as CH ₃ Si (OCH ₃ ) ₃ , C ₂ H ₅ Si (OCH ₃ ) ₃ , CH ₃ Si (OC ₂ H ₅ ) ₃ , C ₂ H ₅ Si (OC ₂ H ₅ ) ₃ Alkoxides are also used.

These organic metal compounds or inorganic metal compounds can be used alone or in combination of two or more. Among these organometallic compounds or inorganic metal compounds, metal alkoxides are preferable because they are highly reactive and easily form a polymer made of a metal-oxygen bond. Among them, silicon alkoxide compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , and Si (OC ₄ H ₉ ) ₄ are inexpensive and easily available. The coating layer of the metal oxide obtained therefrom is excellent and particularly preferred. Also preferred are oligomers obtained by condensing these silicon alkoxide compounds by partial hydrolysis. An example of this is an average pentameric ethylsilicate oligomer containing about 40% by weight of SiO ₂ .

Furthermore, it is also preferable to use a so-called silane coupling agent in which one or two alkoxy groups of the silicon tetraalkoxy compound are substituted with an alkyl group or a reactive group in combination with these metal alkoxides. As the silane coupling agent to be added to the backcoat layer in the present invention, one or two alkoxy groups in the silicon tetraalkoxy compound may be a hydrophobic group such as a long-chain alkyl group having 4 to 20 carbon atoms or a fluorine-substituted alkyl group. Examples include silane coupling agents substituted with a substituent, and silane coupling agents having a fluorine-substituted alkyl group are particularly preferable. Specific examples of such a silane coupling agent include CF ₃ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , CF ₃ CF ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , CF ₃ CH ₂ CH ₂ Si (OC). ₂ H ₅ ) _{3 and the} like, and commercially available products include LS-1090 manufactured by Shin-Etsu Chemical Co., Ltd. The silane coupling agent substituted with the fluorine-substituted alkyl group is included in the organic fluorine compound in the present invention. The preferable content of such a silane coupling agent is 5 to 90% by mass, more preferably 10 to 80% by mass, based on the total solid content of the backcoat layer.

  As a catalyst useful when forming a sol-gel coating solution for the backcoat layer, organic and inorganic acids and alkalis are used. Examples include hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, fluorine, phosphoric acid, phosphorous acid and other inorganic acids, formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, Fluoroacetic acid, bromoacetic acid, methoxyacetic acid, oxaloacetic acid, citric acid, oxalic acid, succinic acid, malic acid, tartaric acid, fumaric acid, maleic acid, malonic acid, ascorbic acid, benzoic acid, 3,4-dimethoxybenzoic acid Substituted benzoic acid, phenoxyacetic acid, phthalic acid, picric acid, nicotinic acid, picolinic acid, pyrazine, pyrazole, dipicolinic acid, adipic acid, p-toluic acid, terephthalic acid, 1,4-cyclohexene-2,2-dicarboxylic acid , Erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and other organic acids, alkali metals and alkaline earth gold Hydroxides, ammonia, ethanolamine, diethanolamine, and alkali such as triethanolamine.

  Other preferred catalysts include sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, and phosphate esters, such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl acid. Organic acids such as phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, and diphenyl phosphate can also be used.

  These catalysts can be used alone or in combination of two or more. The catalyst is preferably from 0.001 to 10% by mass, more preferably from 0.05 to 5% by mass, based on the starting metal compound. If the amount of the catalyst is less than this range, the start of the sol-gel reaction is delayed, and if it is more than this range, the reaction proceeds rapidly and non-uniform sol-gel particles are formed. Become.

  In order to initiate the sol-gel reaction, an appropriate amount of water is further required, and the preferred amount of addition is preferably 0.05 to 50 times the amount of water required to completely hydrolyze the starting metal compound. More preferably, it is 0.5 to 30 times mol. If the amount of water is less than this range, the hydrolysis is difficult to proceed, and if it is more than this range, the reaction is difficult to proceed because the raw material is diluted.

A solvent is further added to the sol-gel reaction solution. Any solvent may be used as long as it dissolves the starting metal compound and dissolves or disperses the sol-gel particles produced by the reaction. Ketones are used. In addition, mono- or dialkyl ethers and acetates of glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol can be used for the purpose of improving the coating surface quality of the backcoat layer. Of these solvents, lower alcohols that are miscible with water are preferred. The sol-gel reaction solution is prepared with a solvent at a concentration suitable for coating. However, if the total amount of the solvent is added to the reaction solution from the beginning, the raw material is diluted, making it difficult for the hydrolysis reaction to proceed. Therefore, it is preferable to add a part of the solvent to the sol-gel reaction solution and add the remaining solvent when the reaction proceeds.
The coating amount of the back coat layer containing the metal oxide thus formed and the colloidal silica sol is preferably 0.01 to 3.0 g / m ² and preferably 0.03 to 1.0 g / m 2. ² is more preferable.

2-2. Backcoat layer comprising an organic resin film Another preferred example of the backcoat layer in the present invention is a backcoat layer comprising an organic resin film formed on the back surface of the support.
Examples of preferable resins that can form the backcoat layer in this embodiment include thermosetting resins such as urea resins, epoxy resins, phenol resins, melamine resins, and diallyl phthalate resins. Among these, a phenol resin is preferable from the viewpoint that the physical strength of the formed layer is high. More specifically, for example, a phenol formaldehyde resin, an m-cresol formaldehyde resin, a p-cresol formaldehyde resin, m− / p−. Preferable examples include mixed cresol formaldehyde resins, novolak resins such as phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resins and pyrogallol acetone resins.

Further, as the phenol resin, as described in US Pat. No. 4,123,279, an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin is further used. Examples thereof include a condensation polymer of phenol and formaldehyde as a substituent.
The phenol resin preferably has a weight average molecular weight of 500 or more from the viewpoint of image forming properties, and more preferably 1,000 to 700,000. The number average molecular weight is preferably 500 or more, and more preferably 750 to 650,000. The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  Moreover, these phenol resins may be used alone or in combination of two or more. In the case of combination, it has 3 to 8 carbon atoms such as a condensation polymer of t-butylphenol and formaldehyde or a condensation polymer of octylphenol and formaldehyde as described in US Pat. No. 4,123,279. A polycondensation product of phenol and formaldehyde having an alkyl group as a substituent, an organic compound having a phenol structure having an electron-withdrawing group on an aromatic ring described in JP-A-2000-241972 previously filed by the present inventors You may use resin etc. together.

A surfactant can be added to the backcoat layer in the present invention for the purpose of improving the coating surface properties and controlling the surface properties. The surfactant used here is an anionic surfactant having any of carboxylic acid, sulfonic acid, sulfate ester and phosphate ester; a cationic surfactant such as aliphatic amine, quaternary ammonium salt. Agents: Betaine-type amphoteric surfactants; or nonionic surfactants such as fatty acid esters of polyoxy compounds, polyalkynelene oxide condensation type, polyethyleneimine condensation type, and fluorine surfactants. A fluorochemical surfactant is preferred.
The addition amount of the surfactant is appropriately selected according to the purpose, but in general, it can be added in the range of 0.1 to 10.0% by mass in the back coat layer.

As the fluorine-based surfactant, a fluorine-based surfactant containing a perfluoroalkyl group in the molecule is particularly preferable. Such a fluorochemical surfactant will be described in detail.
Fluorosurfactants that can be used particularly favorably in the backcoat layer include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates, and amphoteric such as perfluoroalkyl betaines. Type, perfluoroalkylamine oxide, perfluoroalkylamine oxide adduct, perfluoroalkyl group and hydrophilic group-containing oligomer, perfluoroalkyl group and lipophilic group-containing oligomer, perfluoro Nonionic types such as alkyl group, hydrophilic group and lipophilic group-containing oligomer, perfluoroalkyl group and lipophilic group-containing urethane are included. Among these, the fluoroaliphatic group is preferably a group represented by the following general formula (1).

(In the general formula (1), R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X is selected from a single bond, an alkylene group, an arylene group, or the like. Represents a divalent linking group, m represents an integer of 0 or more, and n represents an integer of 1 or more.)
Here, when X represents a divalent linking group, the linking group such as an alkylene group or an arylene group may have a substituent, and in the structure, an ether group, an ester group, an amide It may have a linking group selected from a group and the like. Examples of the substituent that can be introduced into the alkylene group or arylene group include a halogen atom, a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an alkyl group, and an aryl group, and these may further have a substituent. Good. Among these, X is preferably an alkylene group, an arylene group, or an alkylene group having a linking group selected from an ether group, an ester group, an amide group, and the like, an unsubstituted alkylene group, an unsubstituted arylene group, or An alkylene group having an ether group or an ester group inside is more preferable, and an unsubstituted alkylene group or an alkylene group having an ether group or an ester group inside is most preferable.
It is preferable to contain about 0.5 to 10% by mass of such a fluorosurfactant in the backcoat layer.

  Various methods can be applied to cover the back surface of the aluminum support with the backcoat layer made of an organic resin film. After adding fine particles such as silica gel to the backcoat layer component, specifically, each raw material mainly composed of an organic resin, if necessary, for example, it is dissolved in an appropriate solvent, or an emulsion dispersion is prepared. Then, it is applied to the back side of the support and dried, or an organic resin film previously formed into a film shape is bonded to the aluminum support via an adhesive or by heating, and a molten film is formed with a melt extruder. And a method of bonding to a support. Among these, the most preferable method from the viewpoint of easy control of the coating amount is a method of coating and drying in a solution. As the solvent used here, an organic solvent as described in JP-A-62-251739 is used alone or in combination.

  Examples of means for applying the coating liquid for the backcoat layer to the surface of the support include a known coater such as a bar coater, a roll coater, a gravure coater, a curtain coater, an extruder, and a slide hopper. A non-contact type quantitative coater such as a curtain coater, an extruder or a slide hopper is particularly preferred because it does not damage the back surface.

The thickness of the back coat layer of the present invention is such that the formed film thickness is 0.1 to 8 μm in both the back coat layer containing the metal oxide and the colloidal silica sol and the back coat layer made of an organic resin. Preferably there is. In this thickness range, the surface slipperiness of the back surface of the aluminum support is improved, and during printing, the thickness variation due to dissolution and swelling of the backcoat layer by chemicals used around the printing, and the printing pressure resulting therefrom Can suppress the deterioration of the printing characteristics due to the change.
In the back coat layer, the most preferable one is an organic resin back coat layer.

[Preparation of lithographic printing plate precursor]
The lithographic printing plate precursor according to the present invention comprises a support, a photosensitive layer, an oxygen blocking layer, and a protective layer provided in this order, and further an undercoat layer and the like as necessary. Such a lithographic printing plate precursor can be produced by dissolving the above-described coating liquids containing the various components in an appropriate solvent and sequentially coating them on a support.

When coating the photosensitive layer, the photosensitive layer components are dissolved in various organic solvents to form a photosensitive layer coating solution, which is applied onto the support or the undercoat layer.
Solvents used here include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 3-methoxypropanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, Ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, lactic acid There are ethyl and the like. These solvents can be used alone or in combination. The concentration of the solid content in the photosensitive layer coating solution is suitably 2 to 50% by mass.

The coating amount of the photosensitive layer mainly affects the sensitivity of the photosensitive layer, the developability, and the strength and printing durability of the exposed film, and is preferably selected as appropriate according to the application. If the coating amount is too small, the printing durability is not sufficient. On the other hand, when the amount is too large, the sensitivity is lowered, it takes time for exposure, and a longer time is required for development processing, which is not preferable. For the lithographic printing plate precursor for scanning exposure, the coating amount is suitably in the range of about 0.1 g / m ² to about 10 g / m ² in terms of the mass after drying. More preferably from 0.5 to 5 g / ^{m 2.}

[Intermediate layer (undercoat layer)]
In the lithographic printing plate precursor according to the invention, an intermediate layer (undercoat layer) may be provided for the purpose of improving the adhesion and soiling between the photosensitive layer and the support. Specific examples of such an intermediate layer include JP-B-50-7481, JP-A-54-72104, JP-A-59-101651, JP-A-60-149491, JP-A-60-232998, JP-A-3-56177, JP-A-4-282737, JP-A-5-16558, JP-A-5-246171, JP-A-7-159983, JP-A-7-314937, JP-A-8-202025, Special Kaihei 8-320551, JP 9-34104, JP 9-236911, JP 9-269593, JP 10-69092, JP 10-115931, JP 10-161317, JP 10-260536, JP-A-10-282682, JP-A-11-84684, JP-A-10-69092, JP-A-10-115931, Kaihei 11-38635, JP-A-11-38629, JP-A-10-282645, JP-A-10-301262, JP-A-11-24277, JP-A-11-109641, JP-A-10-319600, JP-A-10-319600 11-84684, JP-A-11-327152, JP-A-2000-10292, JP-A-2000-235254, JP-A-2000-352854, JP-A-2001-209170, Japanese Patent Application No. 11-284091, etc. Can be mentioned.

<Plate making method>
Hereinafter, a method for making a lithographic printing plate precursor according to the present invention will be described.
The plate-making method of the lithographic printing plate of the present invention comprises a laminate comprising a plurality of the above-described lithographic printing plate precursors of the present invention in contact with the protective layer and the back surface of the support (the planographic printing plate precursor of the present invention). The laminate is set in a plate setter, and the lithographic printing plate precursor is automatically conveyed one by one, and then exposed at a wavelength of 750 nm to 1400 nm, and then substantially without heat treatment, the conveyance speed Is developed under the condition of 1.25 m / min or more.
Even if the lithographic printing plate precursor of the present invention described above is laminated without sandwiching a slip sheet between the plates, the adhesion between the lithographic printing plate precursor and the generation of scratches on the protective layer are suppressed, It can be applied to the plate making method as described above.
According to the plate making method of the lithographic printing plate of the present invention, since the laminate (laminated body of the lithographic printing plate precursor of the present invention) obtained by laminating the lithographic printing plate precursor without sandwiching the slip sheet is used, the slip sheet can be removed. It becomes unnecessary and productivity in the plate making process is improved.

  Needless to say, this plate making method is also suitable for plate making of the above-described lithographic printing plate precursor according to the present invention, but contains at least an infrared absorber, a polymerization initiator, and a polymerizable compound, and is 750 nm to 1400 nm. The present invention can be suitably applied to any lithographic printing plate precursor provided with a polymerizable negative photosensitive layer whose solubility in an alkaline developer is reduced by exposure at a wavelength of. Specifically, it may be a photosensitive layer containing each component of “infrared absorber, polymerization initiator, and polymerizable compound” described in the column of each component constituting the photosensitive layer of the lithographic printing plate precursor according to the invention. What is necessary is just to include a well-known thing as a binder polymer, and does not need to contain it.

  The photosensitive layer to which the lithographic printing plate making method of the present invention is applied has a development rate of 80 nm / sec or more in an unexposed portion with respect to an alkaline developer having a pH of 10 to 13.5, and exposure of the alkaline developer. It is preferable that the penetration rate in the part has a physical property of 50 nF / sec or less. The method for measuring the developing speed of the unexposed portion of the photosensitive layer and the penetration speed of the alkali developer into the cured photosensitive layer is the same as the method described in Japanese Patent Application No. 2004-248535 previously filed by the present applicant. Can be used. Control of the developing speed of the unexposed part of the photosensitive layer and the penetration speed of the alkali developer into the cured photosensitive layer can be performed by a conventional method, but as a typical method, a method using the specific binder polymer In addition, the addition of a hydrophilic compound is useful for improving the developing speed of the unexposed area, and the means for adding a hydrophobic compound is useful for suppressing the penetration of the developer into the exposed area.

〔exposure〕
The light source used for the exposure treatment in the present invention may be any light source as long as it can be exposed at a wavelength of 750 nm to 1400 nm, and an infrared laser is preferable. Especially, in this invention, it is preferable to image-expose with the solid laser and semiconductor laser which radiate | emit infrared rays with a wavelength of 750 nm-1400 nm. The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec. The energy applied to the planographic printing plate precursor is preferably 10 to 300 mJ / cm ² . If the exposure energy is too low, the photosensitive layer is not sufficiently cured. If the exposure energy is too high, the photosensitive layer may be laser ablated and the image may be damaged.

  In the exposure processing in the present invention, exposure can be performed by overlapping light beams of light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the present invention, the overlap coefficient is preferably 0.1 or more.

  The scanning method of the light source of the exposure apparatus used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, or the like can be used. The channel of the light source may be a single channel or a multi-channel, but in the case of a cylindrical outer surface system, a multi-channel is preferably used.

  In the present invention, as described above, the exposed lithographic printing plate precursor is subjected to a development process without performing any special heat treatment and water washing treatment. By not performing this heat treatment, image non-uniformity due to the heat treatment can be suppressed. Further, by performing neither heat treatment nor water washing treatment, stable high-speed processing is possible in development processing.

〔developing〕
In the development processing in the present invention, a non-image portion of the photosensitive layer is removed using a developer.
In the present invention, as described above, the processing speed in the development process, that is, the transport speed (line speed) of the lithographic printing plate precursor in the development process needs to be 1.25 m / min or more. Preferably, it is 1.35 m / min or more. Moreover, there is no restriction | limiting in particular in the upper limit of a conveyance speed, However, From a viewpoint of stability of conveyance, it is preferable that it is 3 m / min or less.
Hereinafter, the developer used in the present invention will be described.

(Developer)
The developer used in the present invention is preferably an alkaline aqueous solution having a pH of 14 or less, and preferably contains an aromatic anionic surfactant.

(Aromatic anionic surfactant)
The aromatic anionic surfactant used in the developer in the present invention has a development accelerating effect and a dispersion stabilizing effect in the developer of the polymerizable negative photosensitive layer component and the protective layer component. preferable. Among these, the aromatic anionic surfactant used in the present invention is preferably a compound represented by the following general formula (A) or general formula (B).

In the above general formula (A) or general formula (B), R ¹ and R ³ each independently represents a linear or branched alkylene group having 1 to 5 carbon atoms, specifically, an ethylene group. , Propylene group, butylene group, pentylene group, and the like, among which ethylene group and propylene group are particularly preferable.
m and n each independently represent an integer selected from 1 to 100. Among them, 1 to 30 are preferable, and 2 to 20 are more preferable. When m is 2 or more, a plurality of R ¹ may be the same or different. Similarly, when n is 2 or more, a plurality of R ³ may be the same or different.
t and u each independently represents 0 or 1.

R ² and R ⁴ each independently represents a linear or branched alkyl group having 1 to 20 carbon atoms, specifically, methyl group, ethyl group, propyl group, butyl group, hexyl group, dodecyl group Among them, a methyl group, an ethyl group, an iso-propyl group, an n-propyl group, an n-butyl group, an iso-butyl group, and a tert-butyl group are particularly preferable.
p and q each represent an integer selected from 0 to 2; Y ¹ and Y ² each represent a single bond or an alkylene group having 1 to 10 carbon atoms. Specifically, a single bond, a methylene group or an ethylene group is preferable, and a single bond is particularly preferable.
(Z ¹ ) ^{r +} and (Z ² ) ^{s +} each independently represents an alkali metal ion, an alkaline earth metal ion, or an ammonium ion that is unsubstituted or substituted with an alkyl group. Sodium ion, potassium ion, magnesium ion, calcium ion, ammonium ion, secondary to quaternary ammonium ion substituted with an alkyl group, aryl group, or aralkyl group in the range of 1 to 20 carbon atoms, etc. In particular, sodium ion is preferable. r and s each represent 1 or 2.
Specific examples are shown below, but the present invention is not limited thereto.

  These aromatic anionic surfactants may be used alone or in appropriate combination of two or more. The amount of the aromatic anionic surfactant added is preferably such that the concentration of the aromatic anionic surfactant in the developer is in the range of 1.0 to 10% by mass, more preferably in the range of 2 to 10% by mass. It is effective to do. Here, if the content is 1.0% by mass or less, the developability and the solubility of the photosensitive layer components are lowered, and if the content is 10% by mass or more, the printing durability of the printing plate is reduced. .

In addition to the aromatic anionic surfactant, other surfactants may be used in combination with the developer according to the present invention. Examples of other surfactants include polyoxyethylene naphthyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene stearyl ether, Polyoxyethylene alkyl esters such as oxyethylene stearate, sorbitan monolaurate, sorbitan monostearate, sorbitan distearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, sorbitan alkyl esters, glycerol mono Nonionic surfactants such as monoglyceride alkyl esters such as stearate and glycerol monooleate.
The content of these other surfactants in the developer is preferably from 0.1 to 10% by mass in terms of active ingredients.

(Chelating agent for divalent metals)
The developer according to the present invention preferably contains a chelating agent for a divalent metal, for example, for the purpose of suppressing the influence of calcium ions contained in hard water. Examples of chelating agents for divalent metals include Na ₂ P ₂ O ₇ , Na ₅ P ₃ O ₃ , Na ₃ P ₃ O ₉ , Na ₂ O ₄ P (NaO ₃ P) PO ₃ Na ₂ , Calgon (polymetalin). Polyphosphates such as ethylenediaminetetraacetic acid, its potassium salt, its sodium salt, its amine salt; diethylenetriaminepentaacetic acid, its potassium salt, sodium salt; triethylenetetraminehexaacetic acid, its potassium salt, its sodium salt Hydroxyethylethylenediaminetriacetic acid, its potassium salt, its sodium salt; nitrilotriacetic acid, its potassium salt, its sodium salt; 1,2-diaminocyclohexanetetraacetic acid, its potassium salt, its sodium salt; 1,3-diamino-2 -Propanol tetraacetic acid 2-phosphonobutanetricarboxylic acid-1,2,4, potassium salt, sodium salt thereof; 2-phosphonobutanone tricarboxylic acid-2, in addition to aminopolycarboxylic acids such as potassium salt, sodium salt, etc. 3,4, its potassium salt, its sodium salt; 1-phosphonoethanetricarboxylic acid-1,2,2, its potassium salt, its sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, its potassium salt, Examples thereof include organic phosphonic acids such as aminotri (methylenephosphonic acid), potassium salt, sodium salt, and the like. Among them, ethylenediaminetetraacetic acid, potassium salt, sodium salt, amine salt; ethylenediamine; Tetra (methylenephosphonic acid), its ammonium salt, its potash Salt; hexamethylenediamine tetra (methylene phosphonic acid), an ammonium salt, its potassium salt is preferred.
The optimum amount of such a chelating agent varies depending on the hardness of the hard water used and the amount used, but is generally 0.01 to 5% by mass, more preferably 0% in the developing solution at the time of use. It is made to contain in the range of 0.01-0.5 mass%.

  Further, an alkali metal salt of an organic acid or an alkali metal salt of an inorganic acid may be added to the developer according to the present invention as a development regulator. For example, sodium carbonate, potassium, ammonium, sodium citrate, potassium, ammonium and the like may be used alone or in combination of two or more.

(Alkaline agent)
Examples of the alkaline agent used in the developer according to the present invention include tribasic sodium phosphate, potassium, ammonium, sodium borate, potassium, ammonium, sodium hydroxide, potassium, ammonium, and lithium. Inorganic alkali agents such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine And organic alkali agents such as diisotopanolamine, ethyleneimine, ethylenediamine, pyridine, and tetramethylammonium hydroxide. In the present invention, these may be used alone or in combination of two or more.

  Moreover, alkali silicate can be mentioned as alkali agents other than the above. Alkali silicates may be used in combination with a base. The alkali silicate to be used exhibits alkalinity when dissolved in water, and examples thereof include sodium silicate, potassium silicate, lithium silicate, and ammonium silicate. These alkali silicates may be used alone or in combination of two or more.

The developer used in the present invention is composed of silicon oxide SiO ₂ which is a silicate component as a hydrophilizing component of a support and alkali oxide M ₂ O as an alkali component (M represents an alkali metal or ammonium group). By adjusting the mixing ratio and concentration, it can be easily adjusted to the optimum range. The mixing ratio of the silicon oxide SiO ₂ and the alkali oxide M ₂ O (the molar ratio of SiO ₂ / M ₂ O) is the amount of unclean stains caused by excessive dissolution (etching) of the anodic oxide film of the support. From the viewpoint of suppressing the generation of insoluble gas resulting from complex formation between dissolved aluminum and silicate, the range is preferably 0.75 to 4.0, more preferably 0.75 to 3.5. Used in.

In addition, the alkali silicate concentration in the developer includes the effect of inhibiting dissolution (etching) of the anodic oxide film on the support, the developability, the effect of inhibiting precipitation and crystal formation, and the gelation during neutralization during waste From the viewpoint of the prevention effect and the like, the SiO ₂ amount is preferably 0.01 to 1 mol / L, more preferably 0.05 to 0.8 mol / L with respect to the mass of the developer.

  In addition to the above components, the following components can be used in combination in the developer used in the present invention, if necessary. For example, benzoic acid, phthalic acid, p-ethylbenzoic acid, pn-propylbenzoic acid, p-isopropylbenzoic acid, pn-butylbenzoic acid, pt-butylbenzoic acid, pt-butylbenzoic acid Acids, p-2-hydroxyethylbenzoic acid, decanoic acid, salicylic acid, organic carboxylic acids such as 3-hydroxy-2-naphthoic acid; organic solvents such as propylene glycol; other reducing agents, dyes, pigments, water softeners And preservatives.

  The developer used in the present invention preferably has a pH in the range of 10 to 12.5 at 25 ° C, and more preferably in the range of pH 11 to 12.5. Since the developer in the present invention contains the surfactant, even if such a low pH developer is used, excellent developability is exhibited in the non-image area. Thus, by setting the pH of the developing solution to a relatively low value, damage to the image area during development is reduced and the handling property of the developing solution is excellent.

The conductivity x of the developer is preferably 2 <x <30 mS / cm, more preferably 5 to 25 mS / cm.
Here, it is preferable to add an alkali metal salt of an organic acid, an alkali metal salt of an inorganic acid, or the like as a conductivity adjusting agent for adjusting the conductivity.

  The developer can be used as a developer and a development replenisher for the exposed lithographic printing plate precursor, and is preferably applied to an automatic processor. When developing using an automatic developing machine, the developing solution becomes fatigued according to the amount of processing, so that the processing capability may be restored by using a replenishing solution or a fresh developing solution. This replenishment method is also preferably applied to the plate making method of the present invention.

    Furthermore, in order to restore the processing capacity of the developer using an automatic developing machine, it is preferable to replenish by the method described in US Pat. No. 4,882,246. Developers described in JP-A-50-26601, 58-54341, JP-B-56-39464, 56-42860, and 57-7427 are also preferable.

  A more preferred development replenisher of the present invention contains an oxycarboxylic acid chelating agent having an ability to form a water-soluble chelate compound with aluminum ions, an alkali metal hydroxide, and a surfactant, and contains a silicate. A developing replenisher characterized by being an aqueous solution having a pH of 11 to 13.5. By using such a development replenisher, it has excellent developability and characteristics that do not impair the strength of the image area of the plate material, and is formed by elution of the aluminum support by the alkali of the developer. Precipitation of aluminum is effectively suppressed, adhesion of stains mainly composed of aluminum hydroxide to the surface of the developing bath roller of the automatic processor, and subsequent accumulation of aluminum hydroxide precipitates in the washing bath are reduced. It can be processed stably for a long time.

  The lithographic printing plate precursor thus developed is subjected to washing water, surface activity as described in JP-A Nos. 54-8002, 55-11545, 59-58431, and the like. It is post-treated with a desensitizing solution containing a rinse solution containing an agent and the like, gum arabic and starch derivatives. These treatments can be used in various combinations for the post-treatment of the lithographic printing plate precursor according to the invention. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing a large number of sheets.

In the lithographic printing plate making method of the present invention, for the purpose of improving the image strength and printing durability, the image after development can be subjected to whole surface post-heating or whole surface exposure.
Very strong conditions can be used for heating after development. Usually, the heating temperature is 200 to 500 ° C. If the heating temperature after development is low, sufficient image strengthening action cannot be obtained, and if it is too high, problems such as deterioration of the support and thermal decomposition of the image area may occur.

The planographic printing plate obtained by the above processing is loaded on an offset printing machine and used for printing a large number of sheets.
As plate cleaners used for removing stains on the plate during printing, conventionally known plate cleaners for PS plates are used, for example, multi cleaner, CL-1, CL-2, CP, CN-4. , CN, CG-1, PC-1, SR, IC (manufactured by Fuji Photo Film Co., Ltd.) and the like.

  Hereinafter, the present invention will be described by way of examples, but the present invention is not limited thereto.

[Example 1]
(Preparation of silica-coated fine particle aqueous dispersion)
[Optobead 6500M aqueous dispersion]
In 74 g of pure water, 3.0 g of Emalex 710 (Nonionic surfactant manufactured by Nippon Emulsifier Co., Ltd.) and 3.0 g of Serogen PR (Daiichi Kogyo Seiyaku Co., Ltd.) are added and dissolved. To this aqueous solution, 20.0 g of Opto beads 6500M (silica composite cross-linked melamine resin fine particles manufactured by Nissan Chemical Industries, Ltd.) was added, and dispersed with an ace homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.) at 10,000 rpm for 15 minutes. An optobead 6500M aqueous dispersion was obtained.
The true specific gravity of the silica-coated fine particles in this dispersion is 1.60, and the average particle size is 6.5 μm.

[Art Pearl J-7P Water Dispersion]
Opto beads 6500M In the above aqueous dispersion, Opto beads 6500M: Opto beads except that Art Pearl J-7P (silica composite crosslinked acrylic resin fine particles manufactured by Negami Kogyo Co., Ltd.) 20.0 g was used instead of 20.0 g. In the same manner as the 6500M aqueous dispersion, Art Pearl J-7 aqueous dispersion was obtained.
The true specific gravity of the silica-coated fine particles in this dispersion is 1.20, and the average particle size is 6.5 μm.

[Art Pearl MD-270 aqueous dispersion]
Opt beads except that Art Pearl MD-270 (silica composite crosslinked acrylic resin fine particles manufactured by Negami Kogyo Co., Ltd.) 20.0 g was used instead of Opt beads 6500M: 20.0 g of the above-mentioned Opt beads 6500M aqueous dispersion. Art Pearl MD-270 aqueous dispersion was obtained in the same manner as 6500M aqueous dispersion.
The true specific gravity of the silica-coated fine particles in this dispersion is 1.10, and the average particle size is 7.0 μm.

[Art Pearl U-800T aqueous dispersion]
Opt-Beads except that Art Pearl U-800T (silica composite cross-linked urethane resin fine particles manufactured by Negami Kogyo Co., Ltd.) 20.0 g was used instead of Opt-Bead 6500M: 20.0 g of the above-mentioned Opt-Bead 6500M aqueous dispersion. A U-800T aqueous dispersion was obtained in the same manner as the 6500M aqueous dispersion.
The true specific gravity of the silica-coated fine particles in this dispersion is 1.16, and the average particle size is 6.0 μm.

[Art Pearl C-800T aqueous dispersion]
Opt-Beads except that Art Pearl C-800T (silica composite crosslinked urethane resin fine particles manufactured by Negami Kogyo Co., Ltd.) 20.0 g was used instead of Opt-Bead 6500M: 20.0 g of the above-mentioned Opt-Bead 6500M aqueous dispersion. A U-800T aqueous dispersion was obtained in the same manner as the 6500M aqueous dispersion.
The true specific gravity of the silica-coated fine particles in this dispersion is 1.16, and the average particle size is 6.0 μm.

(Production of support)
The surface treatment shown below was performed using a JIS A 1050 aluminum plate having a thickness of 0.30 mm and a width of 1030 mm.

<Surface treatment>
In the surface treatment, the following various treatments (a) to (f) were continuously performed. In addition, after each process and water washing, the liquid was drained with the nip roller.

(A) The aluminum plate was etched at a caustic soda concentration of 26 mass%, an aluminum ion concentration of 6.5 mass%, and a temperature of 70 ° C. to dissolve the aluminum plate by 5 g / m ² . Thereafter, it was washed with water.

(B) A desmut treatment by spraying was performed with a 1% by mass aqueous solution of nitric acid having a temperature of 30 ° C. (including 0.5% by mass of aluminum ions), and then washed with water.

(C) An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass aqueous nitric acid solution (including 0.5% by mass aluminum ions and 0.007% by mass ammonium ions) at a temperature of 30 ° C. The AC power source was subjected to an electrochemical surface roughening treatment using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current with a time TP of 2 msec until the current value reached a peak from zero and a duty ratio of 1: 1. Ferrite was used for the auxiliary anode. The current density was 25 A / dm ² at the current peak value, and the amount of electricity was 250 C / cm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Thereafter, it was washed with water.

(D) The aluminum plate was etched by spraying at 35 ° C. with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass, the aluminum plate was dissolved at 0.2 g / m ² , and electricity was obtained using the previous AC. The removal of the smut component mainly composed of aluminum hydroxide generated during chemical roughening and the edge portion of the generated pit were dissolved to smooth the edge portion. Thereafter, it was washed with water.

(E) A desmut treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid having a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

(F) Anodization was performed for 50 seconds at a sulfuric acid concentration of 170 g / liter (containing 0.5 mass% of aluminum ions), a temperature of 33 ° C., and a current density of 5 (A / dm ² ). Thereafter, it was washed with water. At this time, the weight of the anodized film was 2.7 g / m ² .
The surface roughness Ra of the aluminum support thus obtained was 0.27 (measuring instrument: Surfcom manufactured by Tokyo Seimitsu Co., Ltd., stylus tip diameter 2 micrometer).

<Undercoat layer>
Next, the following undercoat layer coating solution was applied to the aluminum support with a wire bar and dried at 90 ° C. for 30 seconds. The coating amount was 10 mg / m ² .

(Coating solution for undercoat layer)
-Polymer compound A having the following structure: 0.05 g
・ Methanol 27g
・ Ion exchange water 3g

(Photosensitive layer)
The following photosensitive layer coating solution [P-1] was prepared and applied on the undercoat layer formed on the aluminum support using a wire bar. Drying was performed at 115 ° C. for 34 seconds using a warm air dryer. The coating amount after drying was 1.4 g / m ² .

<Coating solution for photosensitive layer [P-1]>
・ Infrared absorber (IR-1) 0.074g
-Polymerization initiator (OS-12) 0.280g
・ Additive (PM-1) 0.151g
・ Polymerizable compound (AM-1) 1.00 g
・ Specific binder polymer (BT-1) 1.00g
・ Ethyl violet (C-1) 0.04g
・ Fluorine-based surfactant 0.015g
(Megafuck F-780-F Dainippon Ink and Chemicals,
Methyl isobutyl ketone (MIBK) 30% by mass solution)
・ Methyl ethyl ketone 10.4g
・ Methanol 4.83g
・ 10.4 g of 1-methoxy-2-propanol

  In addition, the polymerization initiator (OS-12) used for the said coating liquid for photosensitive layers points out what is mentioned as a compound example of the onium salt represented by the above-mentioned general formula (1). The structures of the infrared absorber (IR-1), additive (PM-1), polymerizable compound (AM-1), binder polymer (BT-1), and ethyl violet (C-1) are shown below. .

(Oxygen barrier layer)
On the formed photosensitive layer, an oxygen barrier layer coating solution 1 having the following composition was applied with a wire bar, and dried at 125 ° C. for 75 seconds with a hot air drying apparatus. The total coating amount of this oxygen barrier layer (the coating amount after drying) was 0.5 g / m ² .

<Coating solution 1 for oxygen barrier layer>
・ Synthetic mica 125g
(Somasif ME-100, 8% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.)
・ Polyvinyl alcohol 82g
(CKS-50: degree of saponification 99 mol%, degree of polymerization 300, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
・ Surfactant-1 (BASF, Pluronic P-84) 2.5 g
・ Surfactant-2 (Nippon Emulsion, Emalex 710) 5g
・ Pure water 1384g

(Protective layer)
The protective layer coating solution 1 having the following composition was coated on the formed oxygen barrier layer with a wire bar, and dried at 125 ° C. for 60 seconds using a hot air drying apparatus. The total coating amount of this protective layer (the coating amount after drying) was 1.2 g / m ² .
Thereby, the planographic printing plate precursor of Example 1 was obtained.

<Coating liquid 1 for protective layer>
・ Polyvinyl alcohol 58g
(CKS-50: degree of saponification 99 mol%, degree of polymerization 300, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
・ Daiichi Kogyo Seiyaku Serogen PR 24g
・ Surfactant-1 (Nippon Emulsion, Emalex 710) 5g
・ Art Pearl J-7P water dispersion 20g
・ Pure water 1384g

[Example 2 and Example 3]
A product using Art Pearl U-800T water dispersion instead of Art Pearl J-7P water dispersion of Example 1 is referred to as Example 2, and instead of Art Pearl J-7P water dispersion of Example 1. A product using Art Pearl C-800T aqueous dispersion was designated as Example 3.

Example 4
(Photosensitive layer)
The following photosensitive layer coating solution [P-2] was applied onto an aluminum support on which the same undercoat layer as in Example 1 was formed, using a wire bar. Drying was performed at 115 ° C. for 34 seconds using a warm air dryer. The coating amount after drying was 1.4 g / m ² .

<Coating solution for photosensitive layer [P-2]>
・ Infrared absorber (IR-1; the above structure) 0.074 g
-Polymerization initiator (OS-12) 0.280g
・ Additive (PM-1; said structure) 0.151 g
-Polymerizable compound (AM-1; said structure) 1.00g
-Specific binder polymer (BT-1; said structure) 0.75g
・ Binder polymer (BT-2; following structure) 0.25g
Ethyl violet (C-1; said structure) 0.04g
・ Fluorine-based surfactant 0.015g
(Megafuck F-780-F Dainippon Ink and Chemicals,
Methyl isobutyl ketone (MIBK) 30% by mass solution)
・ Methyl ethyl ketone 10.4g
・ Methanol 4.83g
・ 10.4 g of 1-methoxy-2-propanol

  The structure of the specific binder polymer (BT-2) used for the photosensitive layer coating solution is shown below.

(Oxygen barrier layer)
On the formed photosensitive layer, an oxygen blocking layer coating solution 2 having the following composition was applied with a wire bar, and dried at 125 ° C. for 75 seconds with a hot air drying apparatus. The total coating amount of this oxygen barrier layer (the coating amount after drying) was 0.5 g / m ² .

<Coating solution 2 for oxygen barrier layer>
・ Synthetic mica 250g
(Somasif ME-100, 8% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.)
・ Polyvinyl alcohol 82g
(CKS-50: degree of saponification 99 mol%, degree of polymerization 300, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
・ Surfactant-1 (BASF, Pluronic P-84) 2.5 g
・ Surfactant-2 (Nippon Emulsion, Emalex 710) 5g
・ Pure water 1259g

(Protective layer)
The protective layer coating solution 2 having the following composition was coated on the formed oxygen barrier layer with a wire bar, and dried at 125 ° C. for 60 seconds using a warm air dryer. The total coating amount of this protective layer (the coating amount after drying) was 1.2 g / m ² .
This obtained the planographic printing plate precursor of Example 4.

<Coating liquid 2 for protective layer>
・ Polyvinyl alcohol 58g
(CKS-50: degree of saponification 99 mol%, degree of polymerization 300, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
・ Daiichi Kogyo Seiyaku Serogen PR 24g
・ Surfactant-1 (Nippon Emulsion, Emalex 710) 5g
・ Art Pearl MD-270 aqueous dispersion 20g
・ Pure water 1384g

Example 5
A lithographic printing plate precursor of Example 5 was obtained in the same manner as in Example 1 except that the following back coat layer was formed on the back surface of the support of Example 1.

(Back coat layer)
On the back of the aluminum support (the surface opposite to the surface on which the undercoat layer is formed), a backcoat layer coating solution having the following composition is applied with a wire bar, and dried at 125 ° C. for 60 seconds with a hot air dryer. It was. The total coating amount of this back coat layer (the coating amount after drying) was 0.5 g / m ² .

<Backcoat layer coating solution>
・ PR55422 (Sumitomo Bakelite Co., Ltd. 0.5g
(Phenol / m-cresol / p-cresol = 5/3/2, average molecular weight 5300). Specific binder polymer (BT-1) 0.5 g
・ F780F (Dainippon Ink & Chemicals, Inc. fluorine-based surfactant) 0.005 g
・ Methyl ethyl ketone 25g

[Comparative Example 1]
A lithographic printing plate precursor of Comparative Example 1 was obtained in the same manner as in Example 1, except that the Art Pearl J-7P aqueous dispersion was removed from the protective layer coating solution 1 of Example 1.

[Comparative Example 2]
The lithographic printing plate precursor of Comparative Example 2 was prepared in the same manner as in Example 1 except that the Art Pearl J-7P aqueous dispersion in the coating solution 1 for the protective layer of Example 1 was replaced with the Optobead 6500M aqueous dispersion. Got.

[Comparative Example 3]
A lithographic printing plate precursor of Comparative Example 3 was obtained in the same manner as in Example 1, except that the synthetic mica was removed from the oxygen barrier layer coating solution 1 of Example 1.

[Evaluation]
(1) for the lithographic printing plate precursor obtained in the hardness measurement each of Examples and Comparative Examples, the hardness of H ₂ hardness H ₁ and the oxygen blocking layer of the organic resin fine particles was measured as follows.
For the hardness measurement, a device in which a Triboscope made by Hystron was connected to a Multimode AFM made by Vigo was used. As an indenter, a triangular pyramid Berkovich type (S / N TI-039) was used, and measurement was performed at an application rate of 20 μN / s, a maximum load of 200 μN, and a maximum load holding time of 10 seconds.
The hardness H ₁ of the organic resin fine particles is measured by spraying an aqueous dispersion of fine particles on a smooth SUS support to obtain an object to be measured, and then operating the triangular pyramid to apply pressure. Carried out.
Further still, the hardness of H ₂ oxygen barrier layer, in Examples and Comparative Examples were measured as in a state where the oxygen blocking layer is formed on the photosensitive layer as a measuring object. That is, the measurement was performed by applying pressure from above the oxygen barrier layer.
This measurement was repeated 5 times for the measurement object. Table 1 shows the average values of the measured values and the maximum and minimum values.

(2) Evaluation of pressure resistance A laminate was formed by laminating 500 sheets of the obtained lithographic printing plate precursor without sandwiching slip sheets. After the laminate is left in an environment where the humidity is adjusted to 30 ° C. and 70% for one month, the lowermost lithographic printing plate precursor is conveyed to a Trend setter 3244 manufactured by Creo, and an entire exposure image is output at a resolution of 2400 dpi, output 7 W, outer drum rotation The exposure was performed at several 150 rpm and a plate surface energy of 110 mJ / cm ² . After the exposure, neither heat treatment nor water washing treatment was performed, and development was performed at a conveyance speed (line speed) of 2 m / min and a development temperature of 30 ° C. using an automatic developing machine LP-1310HII manufactured by FUJIFILM Corporation. The developer used was a 1: 4 water diluted solution of DH-N, the developer replenisher was diluted 1: 1.4 water of FCT-421, and the finisher was 1: 1 of GN-2K manufactured by FUJIFILM Corporation. A water dilution was used.
The presence or absence of fine-grained white spots in the image of the obtained lithographic printing plate was evaluated using a 50 × magnifier. Evaluation was performed by sensory evaluation of 1 to 5, 3 being a practical lower limit level, and 2 or less being a practically impossible level. The results are shown in Table 1.

(3) Evaluation of scratch resistance A laminate was formed by stacking the obtained lithographic printing plate precursors with no interleaving paper interposed between the 20 lithographic printing plate precursors. This laminated body is placed on the planographic printing plate precursor of the present invention that has already been set in the cassette, and is shifted from the edge by 5 cm (the stacked 20 plate materials protrude from the edge of the plate material in the cassette to the outside by 5 cm). After that, the edges of the 20 protruding plate materials are pushed in horizontally, and the back surface of the bottom of the 20 stacked plates is rubbed against the surface of the protective layer of the uppermost plate material in the cassette. In this way, it was installed in the cassette. The plate material rubbed on the surface of the protective layer with the back surface of the aluminum support was used as a plate material for scratch resistance evaluation. It was conveyed from a setting part to a Trendsetter 3244 manufactured by Creo by an autoloader, and a 50% flat screen image was exposed at a resolution of 2400 dpi at an output of 7 W, an external drum rotational speed of 150 rpm, and a plate surface energy of 110 mJ / cm ² . After the exposure, development processing was performed in the same manner as in the evaluation of (2) pressure resistance.
The obtained lithographic printing plate was visually evaluated for the presence or absence of scratches in the flat screen image on the plate surface. Evaluation was performed by sensory evaluation of 1 to 5, 3 being a practical lower limit level, and 2 or less being a practically impossible level. The results are shown in Table 1.

(4) Evaluation of adhesion between lithographic printing plate precursors Three lithographic printing plate precursors (10 × 10 cm) obtained were conditioned for 2 hours in an environment of 25 ° C. and 75% RH, and the three original plates were in the same direction. Were laminated one after another without interleaving of the interleaving paper to obtain a laminate. This laminate was hermetically packaged with kraft paper having an aluminum laminate layer, and left under a 30 ° C. environment for 5 days under a load of 4 kg. About the laminated body after that, the adhesion state of the protective layer surface of the lithographic printing plate precursor and the support side surface of the adjacent lithographic printing plate precursor was evaluated.
Adhesion between the lithographic printing plate precursors was performed by sensory evaluation of 1 to 5, 3 being a practical lower limit level, and 2 or less being a practically impossible level. The results are shown in Table 1.

As is clear from Table 1, as in Examples 1 to 5, the lithographic printing plate precursor in which the hardness H _{1 of the} fine particles containing an organic resin is smaller than the hardness of the protective layer H ₂ containing mica is resistant even without interleaf. It can be seen that the lithographic printing plate precursors are not adhered to each other even after being excellent in scratching properties and placed under high humidity. Moreover, it turns out that it is excellent also in pressure resistance.
On the other hand, the lithographic printing plate precursor of Comparative Example 1 containing no organic resin fine particles shows adhesion between the lithographic printing plate precursors after being placed under high humidity, and the support back surface and the protective layer surface are rubbed. It was found that scratches occurred and the scratch resistance was extremely inferior.
Further, it can be seen that the lithographic printing plate precursors of Comparative Example 2 and Comparative Example 3 in which the hardness H _{1 of the} fine particles containing the organic resin is larger than the hardness of the protective layer H ₂ containing mica are significantly inferior in pressure resistance. .

Claims (3)

On the support, it has a polymerizable negative photosensitive layer and an oxygen blocking layer containing mica in this order, and further has a protective layer containing fine particles containing an organic resin in the uppermost layer,
A lithographic printing plate precursor, wherein the hardness H _{1 of the} fine particles containing the organic resin and the hardness H ₂ of the oxygen barrier layer containing mica satisfy a relationship of H ₁ ≦ H ₂ .   2. The lithographic printing plate precursor as claimed in claim 1, wherein the fine particles containing an organic resin contain a silica component.   A laminate of a lithographic printing plate precursor comprising a plurality of lithographic printing plate precursors according to claim 1 or 2, wherein the protective layer and the back surface of the support are directly brought into contact with each other.