JP2006078724A - Planographic original printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planographic original printing plate, having superior contamination resistance and plate wear and unlikely to cause contamination in a non-image part of a shadow portion, even when the supply amount of damping water is decreased during printing, in a process that uses a FM screen for dot matrix. <P>SOLUTION: The planographic original printing plate comprises an intermediate layer, containing a polymer having a structure expressed by general formula (I) as a side chain and an image recording layer successively layered on a planographic printing plate support body which is prepared by subjecting an aluminum plate to at least treatment with an alkali metal silicate and then to rinsing with water and has 5 to 15 mg/m<SP>2</SP>Si amount on the surface and ≥1 mg/m<SP>2</SP>amount for an alkaline earth metal element on the surface. In general Formula (I), Y represents a connecting group to the main chain skeleton of the polymer, R<SP>1</SP>represents a hydrogen atom or a monovalent hydrocarbon group, and R<SP>2</SP>represents a divalent hydrocarbon group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lithographic printing plate precursor.

In recent years, with the development of solid-state lasers and semiconductor lasers that have a light emitting region from the near infrared to the infrared, systems using these infrared lasers are attracting attention as systems for direct plate-making from computer digital data (direct plate-making). .
For example, Patent Document 1 describes an image recording material for an infrared laser positive lithographic printing plate used for direct plate making. This image recording material is an image recording material in which a substance that absorbs light and generates heat and a positive photosensitive compound such as quinonediazide compounds are added to an alkali-soluble resin. In this image recording material, in the image area, the positive photosensitive compound acts as a dissolution inhibitor that substantially lowers the solubility of the alkali-soluble resin, and in the non-image area, it is decomposed by heat and no longer exhibits dissolution inhibiting ability. Thus, it can be removed by development to form an image.

On the other hand, it is known that an onium salt or a compound capable of forming a hydrogen bond network with low alkali solubility has an alkali dissolution inhibiting action of an alkali-soluble polymer.
For example, Patent Document 2 describes a composition exhibiting a positive action using a cationic infrared absorbing dye as a dissolution inhibitor of an alkaline water-soluble polymer as an image recording material for infrared laser. The positive action in this image recording material is an action in which the infrared absorbing dye absorbs the laser light, and the effect of dissolving the polymer film in the irradiated portion is lost by the generated heat to form an image.

With respect to a support for a lithographic printing plate used for such a lithographic printing plate precursor, there has been extensive research on hydrophilicizing the surface of the support in order to prevent contamination of non-image areas.
For example, in the case of using a metal support such as an aluminum plate, an anodized aluminum support or an alkali metal silicate after anodizing to further improve the hydrophilicity. Various techniques such as an aluminum support subjected to a treatment (silicate treatment) have been proposed.

Specifically, for example, in Patent Document 3, an anodized aluminum plate is an aqueous solution of an alkali metal silicate containing a hydroxide, and the pH at 25 ° C. is 12.4 to 13.0. And a process for producing a lithographic printing plate support, characterized by treatment with an aqueous solution having a specific gravity of 1.02 to 1.17 and an electrical conductivity at 70 ° C. of 35 to 180 [ms / cm]. Are listed. The object of this method is to provide a lithographic printing plate that is less likely to cause contamination of non-image areas and has a large printing durability.
However, various treatments for improving hydrophilicity, including the method described in Patent Document 3, are not necessarily excellent in affinity with the image recording layer. And the image recording layer formed thereon deteriorate, and the image recording layer may peel off under severe printing conditions. That is, there is a problem that sufficient printing durability cannot be obtained.

On the other hand, in order to improve the adhesion between the hydrophilic support surface and the image recording layer, a method of providing various intermediate layers between the support and the image recording layer has been proposed. In such a method, the resin material constituting the image recording layer and the material having a functional group excellent in affinity with the support surface are used as an intermediate layer, whereby the adhesion in the image area is improved and sufficient. Printing durability is obtained.
However, in the non-image area, the image recording layer is not quickly removed at the time of development, and remains as a residual film on the surface of the support, causing ink to adhere to the non-image area and causing stains. There was a problem. For this reason, a support having excellent surface hydrophilicity and satisfying both the adhesion to the recording layer in the image area and the removability of the image recording layer in the non-image area has been desired.

Therefore, a lithographic printing plate provided with an intermediate layer containing a polymer compound containing a specific structural unit such as p-vinylbenzoic acid for the purpose of making both the stain resistance and the printing durability excellent. It has been proposed (see Patent Document 4).
A lithographic printing plate precursor provided with an intermediate layer containing a polymer (random polymer) having a monomer having an acid group and a monomer having an onium group has also been proposed (see Patent Document 5).
Although these lithographic printing plate precursors have a certain improvement effect, they are intended to improve adhesion with both the support and the image recording layer, further improve printing durability, and in non-image areas. However, the present situation is that further improvement that effectively suppresses the generation of dirt is desired.

JP-A-7-285275 International Publication No. 97/39894 Pamphlet Japanese Patent Laid-Open No. 2-185493 JP-A-10-69092 JP 2000-108538 A

  As a result of earnest research on the lithographic printing plate precursor described in Patent Document 5, the present inventor found that when using an FM screen for halftone dots and reducing the amount of dampening water supplied during printing, The present inventors have found that non-image areas are easily stained.

  Therefore, the present invention is excellent in stain resistance and printing durability, and when an FM screen is used as a halftone dot, even if the supply amount of dampening water is reduced during printing, the non-image portion of the shadow portion is reduced. An object of the present invention is to provide a lithographic printing plate precursor which is less susceptible to smudges.

  As a result of further diligent research to achieve the above object, the present inventor has increased the amount of Si on the surface resulting from the alkali metal silicate treatment as compared with the case of Patent Document 5, and the alkaline earth metal element on the surface. When the amount is more than a specific amount, and a polymer having a specific structure in the side chain is used for the intermediate layer, the stain resistance and the printing durability are excellent, and an FM screen is used for the halftone dots. The inventors have found that even if the amount of dampening water supplied during printing is reduced, the non-image area of the shadow area is less likely to be stained, and the present invention has been completed.

  That is, the present invention provides the following (1) to (5).

(1) The surface Si amount obtained by subjecting an aluminum plate to at least alkali metal silicate treatment and subsequent water washing treatment is 5 to 15 mg / m ² , and the surface alkaline earth metal element amount is 1 mg. / Lithographic printing in which an intermediate layer containing a polymer having a structure represented by the following general formula (I) in the side chain and an image recording layer are sequentially provided on a lithographic printing plate support having a size of at least ² m ² Version original edition.

(In the formula, Y represents a linking group to the main chain skeleton of the polymer. R ¹ represents a hydrogen atom or a monovalent hydrocarbon group. R ² represents a divalent hydrocarbon group.)

  (2) The lithographic printing plate precursor as described in (1) above, wherein the washing treatment is performed using an alkaline earth metal element-containing liquid.

  (3) The lithographic printing plate precursor as described in (1) or (2) above, wherein the alkaline earth metal element is calcium.

  (4) The lithographic printing plate precursor as described in any one of (1) to (3) above, wherein the alkali metal silicate treatment is performed using an aqueous alkali metal silicate solution having a pH of 11.5 to 13.5. .

  (5) The lithographic printing plate precursor as described in any one of (1) to (4) above, wherein the image recording layer is an image recording layer containing an alkali-soluble polymer compound and a photothermal conversion substance.

  The planographic printing plate precursor of the present invention is excellent in stain resistance and printing durability, and in the case where an FM screen is used for halftone dots, even if the supply amount of dampening water is reduced during printing, the shadow portion is not Dirt on the image area hardly occurs.

Hereinafter, the present invention will be described in detail.
[Support for lithographic printing plate]
<Aluminum plate (rolled aluminum)>
In order to obtain the lithographic printing plate precursor according to the present invention, a known aluminum plate can be used. The aluminum plate used in the present invention is a metal mainly composed of dimensionally stable aluminum, and is made of aluminum or an aluminum alloy. In addition to a pure aluminum plate, an alloy plate containing aluminum as a main component and a trace amount of foreign elements can also be used.

  In the present specification, various substrates made of the above-described aluminum or aluminum alloy are generically used as an aluminum plate. The foreign elements that may be contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, titanium, and the content of the foreign elements in the alloy is 10% by mass or less. It is.

  Thus, the composition of the aluminum plate used in the present invention is not specified. For example, a conventionally known material described in the fourth edition of the Aluminum Handbook (1990, published by the Light Metal Association), for example, JIS Al-Mn aluminum plates such as A1050, JIS A1100, JIS A1070, JIS A3004 containing Mn, and internationally registered alloy 3103A can be appropriately used. For the purpose of increasing the tensile strength, an Al—Mg alloy or an Al—Mn—Mg alloy (JIS A3005) in which 0.1% by mass or more of magnesium is added to these aluminum alloys can also be used. Furthermore, an Al—Zr alloy or an Al—Si alloy containing Zr or Si can also be used. Furthermore, an Al—Mg—Si based alloy can also be used.

  Regarding the JIS 1050 material, the techniques proposed by the applicant of the present application are disclosed in Japanese Patent Application Laid-Open Nos. 59-153861, 61-51395, 62-146694, 60-215725, and 60-215725. JP 60-215726, JP 60-215727, JP 60-216728, JP 61-272367, JP 58-11759, JP 58-42493, JP 58- 221254, JP-A-62-148295, JP-A-4-254545, JP-A-4-165541, JP-B-3-68939, JP-A-3-234594, JP-B-1-47545, and JP-A-62. It is described in each publication of -140894. In addition, techniques described in Japanese Patent Publication No. 1-35910 and Japanese Patent Publication No. 55-28874 are also known.

  Regarding the JIS1070 material, the techniques proposed by the applicant of the present application are disclosed in JP-A-7-81264, JP-A-7-305133, JP-A-8-49034, JP-A-8-73974, JP-A-8-108659 and It is described in JP-A-8-92679.

  Regarding Al-Mg alloys, the techniques proposed by the applicant of the present application are disclosed in Japanese Patent Publication Nos. Sho 62-5080, Sho 63-60823, Shoko 3-61753, JP Sho 60-20396, JP-A-60-203497, JP-B-3-11635, JP-A-61-274993, JP-A-62-23794, JP-A-63-47347, JP-A-63-47348, JP-A-63-47349. JP-A 64-1293, JP-A 63-135294, JP-A 63-87288, JP-B 4-73392, JP-B 7-100844, JP-A 62-149856, JP-B JP-A-4-73394, JP-A-62-181191, JP-B-5-76530, JP-A-63-30294, and JP-B-6-37116. Also described in JP-A-2-215599, JP-A-61-201747, and the like.

  With regard to Al—Mn alloys, techniques proposed by the applicant of the present application are described in Japanese Patent Application Laid-Open Nos. 60-230951, 1-306288, and 2-293189. In addition, JP-B-54-42284, JP-B-4-19290, JP-B-4-19291, JP-B-4-19292, JP-A-61-35995, JP-A-64-51992, JP-A-4-19592, No. 226394, US Pat. No. 5,009,722, US Pat. No. 5,028,276 and the like.

  With regard to the Al—Mn—Mg alloy, techniques proposed by the applicant of the present application are described in Japanese Patent Application Laid-Open Nos. 62-86143 and 3-2222796. JP-B 63-60824, JP-A 60-63346, JP-A 60-63347, JP-A-1-293350, European Patent No. 223,737, US Pat. No. 4,818, No. 300, British Patent No. 1,222,777, etc.

  Regarding the Al—Zr alloy, the technique proposed by the applicant of the present application is described in Japanese Patent Publication No. 63-15978 and Japanese Patent Application Laid-Open No. 61-51395. Also described in JP-A-63-143234 and JP-A-63-143235.

  The Al—Mg—Si alloy is described in British Patent 1,421,710.

  In order to use an aluminum alloy as a plate material, for example, the following method can be employed. First, a molten aluminum alloy adjusted to a predetermined alloy component content is subjected to a cleaning process and cast according to a conventional method. In the cleaning process, in order to remove unnecessary gas such as hydrogen in the molten metal, flux treatment, degassing process using argon gas, chlorine gas, etc., so-called rigid media filter such as ceramic tube filter, ceramic foam filter, A filtering process using a filter that uses alumina flakes, alumina balls or the like as a filter medium, a glass cloth filter, or a combination of a degassing process and a filtering process is performed.

  These cleaning treatments are preferably performed in order to prevent defects caused by foreign matters such as non-metallic inclusions and oxides in the molten metal and defects caused by gas dissolved in the molten metal. Regarding filtering of the molten metal, JP-A-6-57432, JP-A-3-162530, JP-A-5-140659, JP-A-4-231425, JP-A-4-276031, JP-A-5-311261, JP-A-5-311261 6-136466 and the like. Further, the degassing of the molten metal is described in JP-A-5-51659, Japanese Utility Model Laid-Open No. 5-49148, and the like. The applicant of the present application has also proposed a technique relating to degassing of molten metal in Japanese Patent Application Laid-Open No. 7-40017.

Next, casting is performed using the molten metal that has been subjected to the cleaning treatment as described above. Regarding the casting method, there are a method using a solid mold typified by a DC casting method and a method using a driving mold typified by a continuous casting method.
In DC casting, solidification occurs at a cooling rate of 0.5 to 30 ° C./second. When the temperature is less than 1 ° C., many coarse intermetallic compounds may be formed. When DC casting is performed, an ingot having a thickness of 300 to 800 mm can be manufactured. The ingot is chamfered as necessary according to a conventional method, and usually 1 to 30 mm, preferably 1 to 10 mm, of the surface layer is cut. Before and after that, soaking treatment is performed as necessary. When performing the soaking process, heat treatment is performed at 450 to 620 ° C. for 1 to 48 hours so that the intermetallic compound does not become coarse. If the heat treatment is shorter than 1 hour, the effect of soaking may be insufficient.

  Then, hot rolling and cold rolling are performed to obtain a rolled aluminum plate. An appropriate starting temperature for hot rolling is 350 to 500 ° C. An intermediate annealing treatment may be performed before or after hot rolling or in the middle thereof. The conditions for the intermediate annealing treatment are heating at 280 to 600 ° C. for 2 to 20 hours, preferably 350 to 500 ° C. for 2 to 10 hours using a batch annealing furnace, or 400 to 600 ° C. using a continuous annealing furnace. Heating is performed for 6 minutes or less, preferably 450 to 550 ° C. for 2 minutes or less. The crystal structure can be made finer by heating at a heating rate of 10 to 200 ° C./second using a continuous annealing furnace.

  The flatness of the aluminum plate finished to a predetermined thickness, for example, 0.1 to 0.5 mm by the above steps may be further improved by a correction device such as a roller leveler or a tension leveler. The flatness may be improved after the aluminum plate is cut into a sheet shape, but in order to improve productivity, it is preferably performed in a continuous coil state. Further, a slitter line may be used for processing into a predetermined plate width. Moreover, in order to prevent generation | occurrence | production of the damage | wound by friction between aluminum plates, you may provide a thin oil film on the surface of an aluminum plate. As the oil film, a volatile or non-volatile film is appropriately used as necessary.

  On the other hand, as the continuous casting method, a twin roll method (hunter method), a method using a cooling roll typified by the 3C method, a double belt method (Hazley method), a cooling belt or a cooling block typified by Al-Swiss Caster II type The method using is industrially performed. When the continuous casting method is used, it solidifies at a cooling rate of 100 to 1000 ° C./second. Since the continuous casting method generally has a higher cooling rate than the DC casting method, it has a feature that the solid solubility of the alloy component in the aluminum matrix can be increased. Regarding the continuous casting method, the techniques proposed by the applicant of the present application are disclosed in JP-A-3-79798, JP-A-5-201166, JP-A-5-156414, JP-A-6-262203, and JP-A-6-122949. JP-A-6-210406 and JP-A-6-26308.

  When continuous casting is performed, for example, if a method using a cooling roll such as a Hunter method is used, a cast plate having a thickness of 1 to 10 mm can be directly cast continuously, and the hot rolling step is omitted. The advantage of being able to In addition, when a method using a cooling belt such as the Husley method is used, a cast plate having a thickness of 10 to 50 mm can be cast. Generally, a hot rolling roll is arranged immediately after casting and continuously rolled. Thus, a continuous cast and rolled plate having a thickness of 1 to 10 mm is obtained.

  These continuous cast and rolled plates are subjected to processes such as cold rolling, intermediate annealing, improvement of flatness, slits, and the like in the same manner as described for DC casting. Finished to a thickness of 5 mm. Regarding the intermediate annealing condition and the cold rolling condition when using the continuous casting method, the techniques proposed by the applicant of the present application are disclosed in JP-A-6-220593, JP-A-6-210308, JP-A-7-54111, It is described in JP-A-8-92709.

Various characteristics described below are desired for the aluminum plate thus manufactured.
As for the strength of the aluminum plate, it is preferable that the 0.2% proof stress is 140 MPa or more in order to obtain the stiffness required for a lithographic printing plate support. Further, in order to obtain a certain level of waist strength even when performing a burning treatment, the 0.2% yield strength after heat treatment at 270 ° C. for 3 to 10 minutes is preferably 80 MPa or more, and 100 MPa or more. It is more preferable that In particular, when the waist strength is required for an aluminum plate, an aluminum material added with Mg or Mn can be used, but if the waist is strengthened, the ease of fitting to the plate cylinder of a printing press becomes inferior. Depending on the application, the material and the amount of trace components added are appropriately selected. With regard to these, techniques proposed by the applicant of the present application are described in Japanese Patent Application Laid-Open Nos. 7-126820 and 62-140894.

  The crystal structure of the aluminum plate may cause poor surface quality when the surface of the aluminum plate is subjected to chemical or electrochemical surface roughening. It is preferably not too coarse. The crystal structure on the surface of the aluminum plate preferably has a width of 200 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, and the length of the crystal structure is 5000 μm or less. Is preferably 1000 μm or less, and more preferably 500 μm or less. With regard to these, techniques proposed by the applicant of the present application are described in Japanese Patent Laid-Open Nos. 6-218495, 7-39906, and 7-124609.

  The alloy component distribution of the aluminum plate, when chemical surface roughening treatment or electrochemical surface roughening treatment is performed, poor surface quality occurs due to non-uniform distribution of the alloy component on the surface of the aluminum plate. Therefore, it is preferable that the surface is not very uneven. With regard to these, the techniques proposed by the applicant of the present application are described in Japanese Patent Laid-Open Nos. 6-48058, 5-301478, and 7-132689.

  In the intermetallic compound of the aluminum plate, the size and density of the intermetallic compound may affect the chemical roughening treatment or the electrochemical roughening treatment. With regard to these, techniques proposed by the applicant of the present application are described in Japanese Patent Laid-Open Nos. 7-138687 and 4-254545.

  In the present invention, an aluminum plate as shown above can be used with unevenness by lamination rolling, transfer or the like in the final rolling step.

The aluminum plate used in the present invention is a continuous belt-like sheet material or plate material. That is, it may be an aluminum web, or a sheet-like sheet cut to a size corresponding to a planographic printing plate precursor shipped as a product.
Since scratches on the surface of the aluminum plate may become defects when processed into a lithographic printing plate support, it is possible to generate scratches at the stage prior to the surface treatment process for making a lithographic printing plate support It is necessary to suppress as much as possible. For that purpose, it is preferable that the package has a stable form and is hardly damaged during transportation.
In the case of an aluminum web, for example, the packaging of aluminum is, for example, laying a hardboard and felt on an iron pallet, applying cardboard donut plates to both ends of the product, wrapping the whole with a polytube, and inserting a wooden donut into the inner diameter of the coil Then, a felt is applied to the outer periphery of the coil, the band iron is used to squeeze it, and the display is performed on the outer periphery. Moreover, a polyethylene film can be used as the packaging material, and needle felt and hard board can be used as the cushioning material. There are various other forms, but the present invention is not limited to this method as long as it is stable and can be transported without being damaged.

  The thickness of the aluminum plate used in the present invention is about 0.1 to 0.6 mm, preferably 0.15 to 0.4 mm, and more preferably 0.2 to 0.3 mm. This thickness can be appropriately changed according to the size of the printing press, the size of the printing plate, the user's desires, and the like.

<Surface treatment>
The support for a lithographic printing plate used in the lithographic printing plate precursor according to the present invention is not particularly limited as long as it is subjected to an alkali metal silicate treatment. However, the aluminum plate is roughened, anodized, and It is preferably obtained by applying an alkali metal silicate treatment.

In the following, as a representative method for forming a suitable surface grain shape,
A method of sequentially performing mechanical surface roughening treatment, alkali etching treatment, desmutting treatment with an acid and electrochemical surface roughening treatment using an electrolytic solution on an aluminum plate,
A method of performing mechanical surface roughening treatment, alkaline etching treatment, desmutting treatment with acid and electrochemical surface roughening treatment using different electrolytes a plurality of times on an aluminum plate,
A method of sequentially performing an alkali etching treatment, an acid desmutting treatment on an aluminum plate, and an electrochemical surface roughening treatment using an electrolytic solution,
Examples include a method of subjecting an aluminum plate to alkali etching treatment, desmutting treatment with an acid, and electrochemical surface roughening treatment using different electrolytic solutions a plurality of times, but the present invention is not limited thereto. In these methods, after the electrochemical roughening treatment, an alkali etching treatment and an acid desmutting treatment may be further performed.
Hereinafter, each step of the surface treatment will be described in detail.

<Mechanical roughening>
The mechanical roughening treatment is effective as a roughening treatment means because it can form an uneven surface with an average wavelength of 5 to 100 μm at a lower cost than the electrochemical roughening treatment. is there.
Examples of the mechanical surface roughening treatment include, for example, a wire brush grain method in which the aluminum surface is scratched with a metal wire, a ball grain method in which the aluminum surface is grained with a polishing ball and an abrasive, JP-A-6-135175, and Japanese Patent Publication A brush grain method in which the surface is grained with a nylon brush and an abrasive described in Japanese Patent No. 50-40047 can be used.
A transfer method in which the uneven surface is pressed against the aluminum plate can also be used. That is, in addition to the methods described in JP-A-55-74898, JP-A-60-36195, and JP-A-60-20396, transfer is performed several times. The method described in JP-A-6-24168 and JP-A-6-24168 characterized in that the surface is elastic is also applicable.

In addition, by using electric discharge machining, shot blasting, laser, plasma etching, etc., a method of repeatedly transferring using a transfer roll etched with fine irregularities, and an uneven surface coated with fine particles on an aluminum plate It is also possible to use a method in which an uneven pattern corresponding to the average diameter of the fine particles is repeatedly transferred to the aluminum plate a plurality of times by contacting the surface and applying a pressure a plurality of times from above. As a method for imparting fine irregularities to the transfer roll, known methods described in JP-A-3-8635, JP-A-3-66404, JP-A-63-65017, etc. may be used. it can. Further, a fine groove may be cut in two directions using a die, a cutting tool, a laser, or the like on the roll surface, and a square unevenness may be formed on the surface. The roll surface may be subjected to a known etching process or the like so that the formed square irregularities are rounded.
Further, in order to increase the surface hardness, quenching, hard chrome plating, or the like may be performed.
In addition, as the mechanical surface roughening treatment, methods described in JP-A Nos. 61-162351 and 63-104889 can be used.
In the present invention, the above-described methods can be used in combination in consideration of productivity and the like. These mechanical surface roughening treatments are preferably performed before the electrochemical surface roughening treatment.

Hereinafter, the brush grain method used suitably as a mechanical roughening process is demonstrated.
The brush grain method generally uses a roller-shaped brush in which a large number of brush hairs such as synthetic resin hair made of synthetic resin such as nylon (trade name), propylene, and vinyl chloride resin are implanted on the surface of a cylindrical body. This is carried out by rubbing one or both of the surfaces of the aluminum plate while spraying a slurry liquid containing an abrasive on a rotating roller brush. Instead of the roller brush and the slurry liquid, a polishing roller which is a roller having a polishing layer on the surface can be used.
When a roller brush is used, the flexural modulus is preferably 10,000 to 40,000 kg / cm ² , more preferably 15,000 to 35,000 kg / cm ² , and the bristle strength is preferably Brush hair of 500 gf or less, more preferably 400 gf or less is used. The diameter of the brush bristles is generally 0.2 to 0.9 mm. The length of the brush bristles can be appropriately determined according to the outer diameter of the roller brush and the diameter of the body, but is generally 10 to 100 mm.

A well-known thing can be used for an abrasive | polishing agent. For example, abrasives such as pumicestone, silica sand, aluminum hydroxide, alumina powder, silicon carbide, silicon nitride, volcanic ash, carborundum, and gold sand; a mixture thereof can be used. Of these, pumiston and silica sand are preferable. In particular, silica sand is preferable in terms of excellent surface roughening efficiency because it is harder and less likely to break than Pamiston.
The average particle diameter of the abrasive is preferably 3 to 50 μm, and more preferably 6 to 45 μm in terms of excellent surface roughening efficiency and a narrow graining pitch.
For example, the abrasive is suspended in water and used as a slurry. In addition to the abrasive, the slurry liquid may contain a thickener, a dispersant (for example, a surfactant), a preservative, and the like. The specific gravity of the slurry liquid is preferably 0.5-2.

  As an apparatus suitable for the mechanical surface roughening treatment, for example, an apparatus described in Japanese Patent Publication No. 50-40047 can be given.

<Electrochemical roughening treatment>
In the electrochemical surface roughening treatment, an electrolytic solution used for the electrochemical surface roughening treatment using a normal alternating current can be used. Among them, the concavo-convex structure characteristic of the present invention can be formed on the surface by using an electrolytic solution mainly composed of hydrochloric acid or nitric acid.
As the electrolytic surface roughening treatment in the present invention, it is preferable to perform the first and second electrolytic treatments with an alternating waveform current in an acidic solution before and after the cathodic electrolytic treatment. By cathodic electrolysis, hydrogen gas is generated on the surface of the aluminum plate and smut is generated to make the surface state uniform, and it is possible to obtain a uniform electrolytic surface during the subsequent electrolysis with an alternating waveform current. .
This electrolytic surface roughening treatment can be performed according to, for example, an electrochemical grain method (electrolytic grain method) described in Japanese Patent Publication No. 48-28123 and British Patent No. 896,563. This electrolytic grain method uses a sinusoidal alternating current, but it may be performed using a special waveform as described in JP-A-52-58602. Further, the waveform described in JP-A-3-79799 can also be used. JP-A-55-158298, JP-A-56-28898, JP-A-52-58602, JP-A-52-152302, JP-A-54-85802, JP-A-60-190392, JP-A-58-120531, JP-A-63-176187, JP-A-1-5889, JP-A-1-280590, JP-A-1-118489, JP-A-1-148592, and JP-A-1-17896. JP-A-1-188315, JP-A-1-1549797, JP-A-2-235794, JP-A-3-260100, JP-A-3-253600, JP-A-4-72079, JP-A-4-72098, The methods described in JP-A-3-267400 and JP-A-1-141094 can also be applied. In addition to the above, it is also possible to perform electrolysis using an alternating current having a special frequency that has been proposed as a method of manufacturing an electrolytic capacitor. For example, it is described in US Pat. Nos. 4,276,129 and 4,676,879.

Various electrolyzers and power sources have been proposed. U.S. Pat. No. 4,023,637, JP-A-56-123400, JP-A-57-59770, JP-A-53-12738, JP-A-53. -32821, JP-A 53-32822, JP-A 53-32823, JP-A 55-122896, JP-A 55-13284, JP-A 62-127500, JP-A-1-52100 JP-A-1-52098, JP-A-60-67700, JP-A-1-230800, JP-A-3-257199 and the like can be used.
Also, JP-A-52-58602, JP-A-52-152302, JP-A-53-12738, JP-A-53-12739, JP-A-53-32821, JP-A-53-32822, JP 53-32833, JP 53-32824, JP 53-32825, JP 54-85802, JP 55-122896, JP 55-13284, JP 48-28123, JP-B-51-7081, JP-A-52-13338, JP-A-52-133840, JP-A-52-133844, JP-A-52-133845, JP-A-53- Nos. 149135 and 54-146234 can be used.

  As an acidic solution which is an electrolytic solution, in addition to nitric acid and hydrochloric acid, U.S. Pat. Nos. 4,671,859, 4,661,219, 4,618,405, 4,600, 482, 4,566,960, 4,566,958, 4,566,959, 4,416,972, 4,374,710, The electrolyte solution described in each specification of 4,336,113 and 4,184,932 can also be used.

  The concentration of the acidic solution is preferably 0.5 to 2.5% by mass, but it is particularly preferably 0.7 to 2.0% by mass in consideration of use in the smut removal treatment. Moreover, it is preferable that liquid temperature is 20-80 degreeC, and it is more preferable that it is 30-60 degreeC.

  An aqueous solution mainly composed of hydrochloric acid or nitric acid is an aqueous solution of hydrochloric acid or nitric acid having a concentration of 1 to 100 g / L, such as nitric acid compounds having nitrate ions such as aluminum nitrate, sodium nitrate, ammonium nitrate, or aluminum chloride, sodium chloride, ammonium chloride, etc. At least one of the hydrochloric acid compounds having hydrochloric acid ions can be used by adding in a range from 1 g / L to saturation. Moreover, the metal contained in aluminum alloys, such as iron, copper, manganese, nickel, titanium, magnesium, a silica, may melt | dissolve in the aqueous solution which has hydrochloric acid or nitric acid as a main component. Preferably, a solution obtained by adding aluminum chloride, aluminum nitrate or the like to an aqueous solution of hydrochloric acid or nitric acid having a concentration of 0.5 to 2% by mass so that aluminum ions are 3 to 50 g / L is preferably used.

Further, by adding and using a compound capable of forming a complex with Cu, uniform graining is possible even for an aluminum plate containing a large amount of Cu. Examples of the compound capable of forming a complex with Cu include ammonia; hydrogen atom of ammonia such as methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, cyclohexylamine, triethanolamine, triisopropanolamine, EDTA (ethylenediaminetetraacetic acid), etc. And amines obtained by substituting with a hydrocarbon group (aliphatic, aromatic, etc.); metal carbonates such as sodium carbonate, potassium carbonate, potassium hydrogen carbonate and the like. In addition, ammonium salts such as ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate, and ammonium carbonate are also included.
The temperature is preferably 10-60 ° C, more preferably 20-50 ° C.

  The AC power supply wave used for the electrochemical surface roughening treatment is not particularly limited, and a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave or the like is used, but a rectangular wave or a trapezoidal wave is preferable, and a trapezoidal wave is particularly preferable. A trapezoidal wave means what was shown in FIG. In this trapezoidal wave, the time (TP) until the current reaches a peak from zero is preferably 1 to 3 msec. If it is less than 1 msec, processing irregularities such as chatter marks that occur perpendicular to the traveling direction of the aluminum plate are likely to occur. When TP exceeds 3 msec, especially when a nitric acid electrolyte is used, it is easily affected by trace components in the electrolyte typified by ammonium ions and the like that spontaneously increase by electrolytic treatment, and uniform graining is performed. It becomes hard to be broken. As a result, the stain resistance tends to decrease when a lithographic printing plate is obtained.

A trapezoidal wave alternating current duty ratio of 1: 2 to 2: 1 can be used. However, as described in Japanese Patent Laid-Open No. 5-195300, in an indirect power feeding method in which no conductor roll is used for aluminum. A duty ratio of 1: 1 is preferable.
A trapezoidal AC frequency of 0.1 to 120 Hz can be used, but 50 to 70 Hz is preferable in terms of equipment. If it is lower than 50 Hz, the carbon electrode of the main electrode is likely to be dissolved, and if it is higher than 70 Hz, it is likely to be affected by the inductance component on the power supply circuit and the power supply cost is increased.

  One or more AC power supplies can be connected to the electrolytic cell. As shown in FIG. 3, the current ratio between the AC anode and cathode applied to the aluminum plate facing the main electrode is controlled to achieve uniform graining and to dissolve the carbon of the main electrode. In addition, it is preferable to install an auxiliary anode and divert part of the alternating current. In FIG. 3, 11 is an aluminum plate, 12 is a radial drum roller, 13a and 13b are main poles, 14 is an electrolytic treatment liquid, 15 is an electrolytic solution supply port, and 16 is a slit. , 17 is an electrolyte passage, 18 is an auxiliary anode, 19a and 19b are thyristors, 20 is an AC power source, 40 is a main electrolytic cell, and 50 is an auxiliary anode cell. An anodic reaction that acts on the aluminum plate facing the main electrode by diverting a part of the current value as a direct current to an auxiliary anode provided in a tank separate from the two main electrodes via a rectifier or switching element It is possible to control the ratio between the current value for the current and the current value for the cathode reaction. On the aluminum plate facing the main electrode, the ratio of the amount of electricity involved in the anodic reaction and the cathodic reaction (the amount of electricity at the time of cathode / the amount of electricity at the time of anode) is preferably 0.3 to 0.95.

  As the electrolytic cell, electrolytic cells used for known surface treatments such as a vertical type, a flat type, and a radial type can be used, but a radial type electrolytic cell as described in JP-A-5-195300 is particularly preferable. . The electrolytic solution passing through the electrolytic cell may be parallel to the traveling direction of the aluminum web or may be a counter.

(Nitric acid electrolysis)
Pits having an average opening diameter of 0.5 to 5 μm can be formed by electrochemical surface roughening using an electrolytic solution mainly composed of nitric acid. However, when the amount of electricity is relatively large, the electrolytic reaction is concentrated, and honeycomb pits exceeding 5 μm are also generated.
To obtain such a grain, the total amount of electricity furnished to anode reaction on the aluminum plate up until the electrolysis reaction is completed is preferably from ^{1~1000C / dm 2, 50~300C / dm} 2 It is more preferable that The current density at this time is preferably ²⁰ to 100 A / dm ² .
Further, when a high concentration or high temperature nitric acid electrolytic solution is used, a small wave structure having an average opening diameter of 0.2 μm or less can be formed.

(Hydrochloric acid electrolysis)
Since hydrochloric acid itself has a strong ability to dissolve aluminum, it is possible to form fine irregularities on the surface with only slight electrolysis. These fine irregularities have an average opening diameter of 0.01 to 0.2 μm and are uniformly generated on the entire surface of the aluminum plate. Such grained total amount of electricity furnished to anode reaction on the aluminum plate up until the electrolysis reaction is completed in order to obtain the, is preferably from 1~100C / dm ^2, in 20~70C / dm ² More preferably. The current density at this time is preferably ²⁰ to 50 A / dm ² .

In such an electrochemical surface roughening treatment with an electrolyte mainly composed of hydrochloric acid, a large crater-like swell is simultaneously formed by increasing the total amount of electricity involved in the anode reaction to 400 to 1000 C / dm ^2. In this case, fine irregularities having an average opening diameter of 0.01 to 0.4 μm are formed on the entire surface by being superimposed on a crater-like wave having an average opening diameter of 10 to 30 μm.

  In the present invention, as the first electrolytic surface roughening treatment, the above-described electrolytic surface roughening treatment (nitric acid electrolysis) using the electrolytic solution mainly composed of nitric acid is performed, and the second electrolytic surface roughening treatment is performed as described above. It is preferable to perform an electrolytic surface roughening treatment (hydrochloric acid electrolysis) using an electrolytic solution mainly composed of hydrochloric acid. That is, the present invention also provides a method for producing a lithographic printing plate support, in which at least an aluminum plate is subjected to nitric acid electrolysis and hydrochloric acid electrolysis sequentially as a roughening treatment, and further subjected to an anodic oxidation treatment to obtain a lithographic printing plate support. provide.

The aluminum plate is preferably subjected to cathodic electrolysis treatment during the first and second electrolytic surface-roughening treatments performed in the electrolytic solution such as nitric acid and hydrochloric acid. By this cathodic electrolysis treatment, smut is generated on the surface of the aluminum plate, and hydrogen gas is generated to enable more uniform electrolytic surface roughening treatment. This cathodic electrolysis treatment is carried out in an acidic solution at a cathode electric quantity of preferably 3 to 80 C / dm ² , more preferably 5 to 30 C / dm ² . Further, the electrolytic solution may be the same as or different from the solution used in the first and second electrolytic surface roughening processes.

<Alkaline etching treatment>
The alkali etching treatment is a treatment for dissolving the surface layer by bringing the aluminum plate into contact with an alkali solution.

  Alkaline etching performed before the electrolytic surface roughening treatment removes rolling oil, dirt, natural oxide film, etc. on the surface of the aluminum plate (rolled aluminum) if mechanical surface roughening treatment is not performed. If the surface of the unevenness generated by the mechanical surface roughening treatment is dissolved, the surface with sharp undulations is smoothed. It is done for the purpose of changing.

If you do not mechanical surface-roughening treatment before the alkali etching treatment, the etching amount is preferably from 0.1 to 10 g / m ^2, and more preferably 1 to 5 g / m ^2. If the etching amount is less than 0.1 g / m ² , rolling oil, dirt, natural oxide film, etc. may remain on the surface, so that uneven pits cannot be generated in the subsequent electrolytic surface roughening treatment. May occur. On the other hand, when the etching amount is 1 to 10 g / m ² , the surface rolling oil, dirt, natural oxide film and the like are sufficiently removed. An etching amount exceeding the above range is economically disadvantageous.

When performing mechanical surface-roughening treatment before the alkali etching treatment, the etching amount is preferably from 3 to 20 g / m ^2, and more preferably 5 to 15 g / m ^2. If the etching amount is less than 3 g / m ² , the unevenness formed by mechanical surface roughening may not be smoothed, and uniform pit formation may not be possible in subsequent electrolytic treatment. In addition, the stain may deteriorate during printing. On the other hand, when the etching amount exceeds 20 g / m ² , the concavo-convex structure may disappear.

The alkali etching treatment performed immediately after the electrolytic surface roughening treatment is performed for the purpose of dissolving the smut generated in the acidic electrolytic solution and dissolving the edge portion of the pit formed by the electrolytic surface roughening treatment. .
Since the pits formed by the electrolytic surface roughening treatment are different depending on the type of the electrolytic solution, the optimum etching amount is different, but the etching amount of the alkali etching treatment performed after the electrolytic surface roughening treatment is 0.1 to 5 g / m. ² is preferred. When a nitric acid electrolyte is used, the etching amount needs to be set larger than when a hydrochloric acid electrolyte is used.
When the electrolytic surface roughening treatment is performed a plurality of times, an alkali etching treatment can be performed as necessary after each treatment.

  Examples of the alkali used in the alkaline solution include caustic alkali and alkali metal salts. Specifically, examples of caustic alkali include caustic soda and caustic potash. Examples of the alkali metal salt include alkali metal silicates such as sodium metasilicate, sodium silicate, potassium metasilicate, and potassium silicate; alkali metal carbonates such as sodium carbonate and potassium carbonate; sodium aluminate and alumina. Alkali metal aluminates such as potassium acid; alkali metal aldones such as sodium gluconate and potassium gluconate; dibasic sodium phosphate, dibasic potassium phosphate, tribasic sodium phosphate, tertiary potassium phosphate, etc. An alkali metal hydrogen phosphate is mentioned. Among these, a caustic alkali solution and a solution containing both a caustic alkali and an alkali metal aluminate are preferable from the viewpoint of high etching rate and low cost. In particular, an aqueous solution of caustic soda is preferable.

  Although the density | concentration of an alkaline solution can be determined according to the etching amount, it is preferable that it is 1-50 mass%, and it is more preferable that it is 10-35 mass%. When aluminum ions are dissolved in the alkaline solution, the concentration of aluminum ions is preferably 0.01 to 10% by mass, and more preferably 3 to 8% by mass. The temperature of the alkaline solution is preferably 20 to 90 ° C. The treatment time is preferably 1 to 120 seconds.

  Examples of the method of bringing the aluminum plate into contact with the alkaline solution include, for example, a method in which the aluminum plate is passed through a tank containing the alkaline solution, a method in which the aluminum plate is immersed in a tank containing the alkaline solution, The method of spraying on the surface of a board is mentioned.

<Desmut treatment>
After the electrolytic surface roughening treatment or the alkali etching treatment, pickling (desmut treatment) is performed to remove dirt (smut) remaining on the surface. Examples of the acid used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid.
The desmutting treatment is performed, for example, by bringing the aluminum plate into contact with an acidic solution having a concentration of 0.5 to 30% by mass (containing 0.01 to 5% by mass of aluminum ions) such as hydrochloric acid, nitric acid, and sulfuric acid. . Examples of the method of bringing the aluminum plate into contact with the acidic solution include a method in which the aluminum plate is passed through a tank containing the acidic solution, a method in which the aluminum plate is immersed in a tank containing the acidic solution, and the acidic solution being aluminum. The method of spraying on the surface of a board is mentioned.
In the desmutting treatment, the acidic solution is mainly composed of an aqueous solution mainly composed of nitric acid or an aqueous solution mainly composed of hydrochloric acid discharged in the above-described electrolytic surface-roughening treatment, or sulfuric acid discharged in an anodic oxidation process described later. It is possible to use a waste solution of an aqueous solution.
It is preferable that the liquid temperature of a desmut process is 25-90 degreeC. Moreover, it is preferable that processing time is 1-180 second. Aluminum and aluminum alloy components may be dissolved in the acidic solution used for the desmut treatment.

<Anodizing treatment>
The aluminum plate treated as described above is further subjected to anodizing treatment. The anodizing treatment can be performed by a method conventionally used in this field. In this case, for example, in a solution having a sulfuric acid concentration of 50 to 300 g / L and an aluminum concentration of 5% by mass or less, an aluminum plate can be energized as an anode to form an anodized film. As a solution used for the anodizing treatment, sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, amidosulfonic acid and the like can be used alone or in combination of two or more.

  Under the present circumstances, the component normally contained at least in an aluminum plate, an electrode, tap water, groundwater, etc. may be contained in electrolyte solution. Furthermore, the 2nd, 3rd component may be added. Examples of the second and third components herein include metal ions such as Na, K, Mg, Li, Ca, Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn; Cation such as ammonium ion; anion such as nitrate ion, carbonate ion, chloride ion, phosphate ion, fluoride ion, sulfite ion, titanate ion, silicate ion, borate ion, etc., 0 to 10,000 ppm It may be contained at a concentration of about.

The conditions for anodizing treatment vary depending on the electrolyte used, and thus cannot be determined unconditionally. In general, however, the electrolyte concentration is 1 to 80% by mass, the solution temperature is 5 to 70 ° C., and the current density is 0.5. ˜60 A / dm ² , voltage 1 to 100 V, and electrolysis time 15 seconds to 50 minutes are appropriate and adjusted so as to obtain a desired anodic oxide film amount.

  Further, JP-A-54-81133, JP-A-57-47894, JP-A-57-51289, JP-A-57-51290, JP-A-57-54300, JP-A-57-136596, JP-A-58-107498, JP-A-60-200366, JP-A-62-136696, JP-A-63-176494, JP-A-4-17697, JP-A-4-280997, JP-A-6-280997 The methods described in JP-A-207299, JP-A-5-24377, JP-A-5-32083, JP-A-5-125597, JP-A-5-195291 and the like can also be used.

  Of these, as described in JP-A-54-12853 and JP-A-48-45303, it is preferable to use a sulfuric acid solution as the electrolytic solution. The sulfuric acid concentration in the electrolytic solution is preferably 10 to 300 g / L (1 to 30% by mass), and the aluminum ion concentration is 1 to 25 g / L (0.1 to 2.5% by mass). It is preferable that it is 2 to 10 g / L (0.2 to 1% by mass). Such an electrolytic solution can be prepared, for example, by adding aluminum sulfate or the like to dilute sulfuric acid having a sulfuric acid concentration of 50 to 200 g / L.

When anodizing is performed in an electrolytic solution containing sulfuric acid, direct current may be applied between the aluminum plate and the counter electrode, or alternating current may be applied.
When a direct current is applied to the aluminum plate, the current density is preferably from 1 to 60 A / dm ^2, and more preferably 5 to 40 A / dm ^2.
In the case where continuous anodizing treatment is performed, a low current of 5 to 10 A / m ² is initially introduced so that current is concentrated on a part of the aluminum plate and so-called “burning” does not occur. It is preferable to increase the current density to 30 to 50 A / dm ² or more as the current is passed at the density and the anodization process proceeds.
When the anodizing process is continuously performed, it is preferable to perform the liquid feeding method in which the aluminum plate is fed with an electrolyte.
By performing anodizing treatment under such conditions, a porous film having many pores called micropores can be obtained. Usually, the average pore diameter is about 5 to 50 nm, and the average pore density is 300. ˜800 / μm ² or so.

The amount of the anodized film is preferably 1 to 5 g / m ² . If it is less than 1 g / m ² , the plate is likely to be scratched. On the other hand, if it exceeds 5 g / m ² , a large amount of electric power is required for production, which is economically disadvantageous. The amount of the anodized film is more preferably 1.5 to 4 g / m ² . Moreover, it is preferable to carry out so that the difference in the amount of the anodized film between the center portion of the aluminum plate and the vicinity of the edge portion is 1 g / m ² or less.

As the electrolysis apparatus used for the anodizing treatment, those described in JP-A-48-26638, JP-A-47-18739, JP-B-58-24517, and the like can be used.
Among these, the apparatus shown in FIG. 4 is preferably used. FIG. 4 is a schematic view showing an example of an apparatus for anodizing the surface of an aluminum plate. In the anodizing apparatus 410, the aluminum plate 416 is transported as indicated by arrows in FIG. In the power supply tank 412 in which the electrolytic solution 418 is stored, the aluminum plate 416 is charged to (+) by the power supply electrode 420. The aluminum plate 416 is transported upward by the roller 422 in the power supply tank 412, and the direction is changed downward by the nip roller 424, and then transported toward the electrolytic treatment tank 414 in which the electrolytic solution 426 is stored. The direction is changed horizontally. Next, the aluminum plate 416 is charged to (−) by the electrolytic electrode 430 to form an anodized film on the surface thereof, and the aluminum plate 416 exiting the electrolytic treatment tank 414 is conveyed to a subsequent process. In the anodizing apparatus 410, the roller 422, the nip roller 424, and the roller 428 constitute a direction changing means, and the aluminum plate 416 is disposed between the power supply tank 412 and the electrolytic treatment tank 414 in the inter-tank section. By 428, it is conveyed into a mountain shape and an inverted U shape. The feeding electrode 420 and the electrolytic electrode 430 are connected to a DC power source 434.

  A feature of the anodizing apparatus 410 in FIG. 4 is that the feeding tank 412 and the electrolytic treatment tank 414 are partitioned by a single tank wall 432, and the aluminum plate 416 is conveyed in a mountain shape and an inverted U shape between the tanks. It is in. As a result, the length of the aluminum plate 416 in the inter-tank portion can be minimized. Therefore, the overall length of the anodizing apparatus 410 can be shortened, so that the equipment cost can be reduced. In addition, by conveying the aluminum plate 416 in a mountain shape and an inverted U shape, it is not necessary to form an opening for allowing the aluminum plate 416 to pass through the tank walls of the tanks 412 and 414. Therefore, since the liquid feeding amount required to maintain the liquid level height in each tank 412 and 414 at a required level can be suppressed, the operating cost can be reduced.

<Sealing treatment>
In this invention, you may perform the sealing process which seals the micropore which exists in an anodic oxide film as needed. The sealing treatment can be performed according to a known method such as boiling water treatment, hot water treatment, steam treatment, sodium silicate treatment, nitrite treatment, ammonium acetate treatment and the like. For example, even if the sealing treatment is carried out by the apparatus and method described in JP-B-56-12518, JP-A-4-4194, JP-A-5-20296, JP-A-5-179482, etc. Good.

<Alkali metal silicate treatment>
In the present invention, as described above, the aluminum plate is subjected to a treatment such as roughening treatment or anodizing treatment as necessary, and then subjected to a hydrophilization treatment with an alkali metal silicate aqueous solution (alkali metal silicate). Salt treatment).
The alkali metal silicate treatment can be performed according to the methods and procedures described in US Pat. No. 2,714,066 and US Pat. No. 3,181,461, but in the present invention The amount of Si on the surface of the lithographic printing plate support is 5 to 15 mg / m ² , preferably 9 to 15 mg / m ² . Within the above range, when an FM screen is used for the halftone dots, the non-image portion of the shadow portion is hardly stained even if the amount of dampening water supplied is reduced during printing. That is, the entanglement stain resistance is excellent.

Hereinafter, the entanglement stain will be described.
In the shadow portion of the printed matter, the area ratio of the halftone dots is high (about 70 to 90%), and in the portion corresponding to that of the planographic printing plate, the area of the image portion (image recording layer) is large, and the non-image portion (support) The exposed area is relatively small. Therefore, the distance between the image portions is small.
In such a case, in printing, particularly when the amount of dampening water supplied is reduced, the inks placed on adjacent image portions come into contact with each other (that is, entangled), and the non-image portion between them comes into contact. A phenomenon that ink adheres and a non-image portion of a printed material is crushed (that is, soiled) easily occurs. Such a phenomenon is called “entangled dirt”.
In recent years, the demand for FM screen printing has been increasing for the purpose of high-definition printing, but FM screens that adjust the density by the density of halftone dots are compared with AM screens that adjust the density by the size of the halftone dots. Since the distance between adjacent halftone dots in the shadow portion is small, the above-described entanglement contamination is likely to occur.

According to the research of the present inventor, the lithographic printing plate support was subjected to silicate treatment under the conditions described in Examples of Patent Document 5, and further, a monomer having an acid group and a monomer having an onium group It has been found that when an intermediate layer containing a polymer having the above is provided, entanglement stains are likely to occur in the FM screen.
Therefore, the present inventor increases the Si amount on the surface of the lithographic printing plate support to the above range and improves the hydrophilicity while providing an intermediate layer to be described later to ensure better printing durability. Thus, even when an FM screen is used, it has been found for the first time that the occurrence of entanglement stains can be suppressed. Further, as will be described later, the amount of the alkaline earth metal element on the surface of the lithographic printing plate support is more than a specific amount. As a result, it was found that the printing durability is extremely excellent, and the present invention has been completed.

In the present invention, the amount of Si on the surface of the support for a lithographic printing plate is determined as a Si atom adhesion amount (Simg / m ² ) by a calibration curve method using an X-ray Fluorescence Spectrometer (XRF). Use the measured value. As a standard sample for preparing a calibration curve, a sodium silicate aqueous solution containing a known amount of Si atoms is uniformly dropped into an area of 30 mmφ on an aluminum plate and then dried. The model of the X-ray fluorescence analyzer and other conditions are not particularly limited. An example of conditions for X-ray fluorescence analysis of Si is shown below.

  X-ray fluorescence analyzer: RIX3000 manufactured by Rigaku Corporation, X-ray tube: Rh, measurement spectrum: Si-Kα, tube voltage: 50 kV, tube current: 50 mA, slit: COARSE, spectral crystal: RX4, detector: F -PC, analysis area: 30 mmφ, peak position (2θ): 144.75 deg. , Background (2θ): 140.70 deg. And 146.85 deg. Integration time: 80 seconds / sample

The alkali metal silicate used for the alkali metal silicate treatment is not particularly limited, and examples thereof include sodium silicate, potassium silicate, and lithium silicate. These may be used alone or in combination of two or more. The aqueous solution of alkali metal silicate may contain an appropriate amount of sodium hydroxide, potassium hydroxide, lithium hydroxide or the like.
Moreover, the alkali metal silicate aqueous solution may contain an alkaline earth metal salt or a Group 4 (Group IVA) metal salt. Examples of the alkaline earth metal salt include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate; sulfates; hydrochlorides; phosphates; acetates; oxalates; Examples of the Group 4 (Group IVA) metal salt include titanium tetrachloride, titanium trichloride, potassium fluoride titanium, potassium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride. And zirconium tetrachloride. These alkaline earth metal salts and Group 4 (Group IVA) metal salts are used alone or in combination of two or more.

  The alkali metal silicate treatment is performed by bringing an aluminum plate subjected to a treatment such as a roughening treatment or an anodizing treatment into contact with an alkali metal silicate aqueous solution. The method of bringing the aluminum plate into contact with the alkali metal silicate aqueous solution is not particularly limited. For example, the method of passing the aluminum plate through the tank containing the aqueous solution, and the aluminum plate in the tank containing the aqueous solution. Examples include a dipping method and a method of spraying the aqueous solution onto the surface of an aluminum plate.

  The conditions for the alkali metal silicate treatment are not particularly limited as long as the Si amount falls within the above range, but the liquid temperature is preferably 10 to 80 ° C, more preferably 15 to 50 ° C, The treatment time is preferably 1 to 100 seconds, and more preferably 5 to 20 seconds.

The alkali metal silicate treatment is preferably performed using an alkali metal silicate aqueous solution having a pH of 11.5 to 13.5. When the pH of the alkali metal silicate aqueous solution is within the above range, the entanglement stain resistance becomes more excellent.
The reason for this is not clear, but when the pH is in the above range, the amount of Si increases and the amount of silanol groups (SiOH) present on the surface of the aluminum plate increases, resulting in higher hydrophilicity. Conceivable.

  The method of adjusting the pH to the above range is not particularly limited. For example, a method of adding a strong alkali such as sodium hydroxide, potassium hydroxide, lithium hydroxide or the like to an aqueous alkali metal silicate solution, an alkali metal silicate, for example. A method of increasing the concentration of Among these, a method of adding sodium hydroxide is preferable.

  The concentration of the alkali metal silicate aqueous solution is preferably 0.1 to 10% by mass, and more preferably 1 to 6% by mass.

<Washing treatment>
It is preferable to perform water washing after the completion of the above-described processes. For washing, pure water, well water, tap water, or the like can be used. A nip device may be used to prevent the processing liquid from being brought into the next process.

Especially, it is preferable to perform the water washing process after an alkali metal silicate process using an alkaline-earth metal element containing liquid. This makes it easy to adjust the amount of the alkaline earth metal element on the surface of the lithographic printing plate support to the amount described later.
In the present invention, the alkaline earth metal element of the surface of the lithographic printing plate support 1 mg / m ² or more, preferably 2-6 mg / m ^2. Within the above range, the printing durability is extremely excellent.

  The alkaline earth metal element is not particularly limited, but calcium and magnesium are preferable, and calcium is more preferable.

In the present invention, the amount of alkaline earth metal element on the surface of the lithographic printing plate support is determined by the calibration curve method using an X-ray fluorescence spectrometer (XRF: X-ray Fluorescence Spectrometer). The value measured as (mg / m ² ) is used. As a standard sample for preparing a calibration curve, an aqueous solution containing a known amount of an alkaline earth metal element atom is uniformly dropped into an area of 30 mmφ on an aluminum plate and then dried. . The model of the X-ray fluorescence analyzer and other conditions are not particularly limited. An example of the conditions of the fluorescent X-ray analysis when the alkaline earth metal element is Ca is shown below.

  X-ray fluorescence analyzer: RIX3000 manufactured by Rigaku Corporation, X-ray tube: Rh, measurement spectrum: Ca-KA, tube voltage: 50 kV, tube current: 50 mA, slit: COARSE, spectral crystal: GE, detector: PC , Analysis area: 30 mmφ, peak position (2θ): 61.950 deg. , Background (2θ): 59.500 deg. And 64.500 deg. Integration time: 80 seconds / sample

The alkaline earth metal element-containing liquid is not particularly limited as long as it is a liquid containing an alkaline earth metal element in the form of ions or the like. For example, a liquid in which an alkaline earth metal element is dissolved or a liquid in which the alkaline earth metal element is dispersed can be given. Among these, a solution in which an alkaline earth metal element is dissolved is preferable. Specifically, a liquid in which calcium is dissolved is preferable. Examples of the liquid in which calcium is dissolved include well water; aqueous solutions of calcium salts such as calcium chloride, calcium hydrogen carbonate, and calcium nitrate.
The alkaline earth metal element-containing liquid may contain two or more alkaline earth metal elements.

The concentration of the alkaline earth metal element-containing liquid is preferably 20 to 2000 ppm, and more preferably 30 to 1000 ppm.
The temperature of the alkaline earth metal element-containing liquid is preferably 20 to 80 ° C, and more preferably 30 to 60 ° C.
Various conditions of the water washing treatment using the alkaline earth metal element-containing liquid are not particularly limited as long as the alkaline earth metal element amount falls within the above range.

<Back coat layer>
The support for a lithographic printing plate obtained as described above has a back surface (a surface on which the image recording layer is not provided) so that the image recording layer is not damaged even if it is overlaid when a lithographic printing plate precursor is used. ) May be provided with a coating layer made of an organic polymer compound (hereinafter also referred to as “backcoat layer”) as necessary.
As a main component of the back coat layer, at least one resin selected from the group consisting of a saturated copolymerized polyester resin, a phenoxy resin, a polyvinyl acetal resin, and a vinylidene chloride copolymer resin having a glass transition point of 20 ° C. or higher is used. Is preferred.

  The saturated copolyester resin is composed of a dicarboxylic acid unit and a diol unit. Examples of the dicarboxylic acid unit include aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, tetrabromophthalic acid, and tetrachlorophthalic acid; adipic acid, azelaic acid, succinic acid, oxalic acid, suberic acid, and sebacic acid , Saturated aliphatic dicarboxylic acids such as malonic acid and 1,4-cyclohexanedicarboxylic acid.

  The backcoat layer further comprises a dye or pigment for coloring, a silane coupling agent for improving the adhesion to the support, a diazo resin comprising a diazonium salt, an organic phosphonic acid, an organic phosphoric acid, a cationic polymer, Wax, higher fatty acids, higher fatty acid amides, silicone compounds composed of dimethylsiloxane, modified dimethylsiloxane, polyethylene powder and the like that are usually used as slipping agents can be appropriately contained.

  The thickness of the backcoat layer may be basically such that even if no interleaf is present, the image recording layer to be described later is hardly damaged, and is preferably 0.01 to 8 μm. When the thickness is less than 0.01 μm, it is difficult to prevent the recording layer from being scratched when the planographic printing plate precursors are handled in layers. On the other hand, when the thickness exceeds 8 μm, the backcoat layer swells due to chemicals used around the lithographic printing plate during printing, the thickness varies, and the printing pressure may change to deteriorate the printing characteristics.

  Various methods can be used as a method of providing the back coat layer on the back surface of the support. For example, a method in which the above components for the back coat layer are dissolved in an appropriate solvent and applied as a solution, or an emulsified dispersion is applied and dried; a previously formed film is supported with an adhesive or heat. The method of bonding to a body; The method of forming a molten film with a melt extruder and bonding to a support body is mentioned. The most preferable method for securing a suitable thickness is a method in which the components for the backcoat layer are dissolved in a suitable solvent, applied as a solution, and dried. In this method, an organic solvent as described in JP-A-62-251739 can be used alone or in combination as a solvent.

  In the production of a lithographic printing plate precursor, any one of the back-coat layer on the back surface, the intermediate layer on the front surface, and the image recording layer may be provided on the support first, or both may be provided simultaneously.

[Middle layer]
Next, the intermediate layer will be described.
The intermediate layer used in the present invention contains a polymer having a structure represented by the following general formula (I) in the side chain (hereinafter also referred to as “specific polymer”).

  In general formula (I), Y represents a linking group to the main chain skeleton of the polymer. Examples of the linking group represented by Y include a substituted or unsubstituted divalent hydrocarbon group. This divalent hydrocarbon group may have one or more partial structures containing one or more heteroatoms selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom.

In general formula (I), R ¹ represents a hydrogen atom or a monovalent hydrocarbon group.
The monovalent hydrocarbon group represented by R ¹ is preferably a hydrocarbon group having 1 to 30 carbon atoms. Among these hydrocarbon groups, an alkyl group or an aryl group is more preferable.
The monovalent hydrocarbon group represented by R ¹ may further have a substituent described later. As the substituent, a group consisting of a carboxy group and a salt thereof is preferable.
As the hydrocarbon group represented by R ¹ , an alkyl group and an aryl group having a group consisting of a carboxy group or a salt thereof are more preferable.

The monovalent hydrocarbon group in R ¹ and the substituents that can be introduced into the monovalent hydrocarbon group will be described in detail.
Specific examples of the alkyl group represented by R ¹ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, Tridecyl group, hexadecyl group, octadecyl group, eicosyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methyl Examples thereof include straight-chain, branched or cyclic alkyl groups having 1 to 30 carbon atoms such as hexyl group, cyclopentyl group, cyclohexyl group and 1-adamantyl group.

The aryl group represented by R ¹ includes those in which 2 to 4 benzene rings form a condensed ring and those in which a benzene ring and an unsaturated five-membered ring form a condensed ring.
Specific examples of the aryl group represented by R ¹ include aryl groups having 6 to 30 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, a fluorenyl group, and a pyrenyl group. It is done.

The hydrocarbon group represented by R ¹ may be substituted at one or more locations with any substituent. Examples of the substituent that can be introduced into R ¹ include a monovalent nonmetallic atomic group excluding a hydrogen atom.

  Specific examples include halogen atoms (-F, -Br, -Cl, -I), hydroxyl groups, alkoxy groups, aryloxy groups, mercapto groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, amino groups, 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 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 An alkylureido group, an N ′, N′-diaryl-N-arylureido group,

N'-alkyl-N'-aryl-N-alkylureido group, N'-alkyl-N'-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxy Carbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxy group and salts thereof A group consisting of: 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, alkyl A sulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group (-SO ₃ H) and a group consisting of a salt thereof, 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 the like A group consisting of a salt, N-alkylsulfonylsulfamoy Group _{(-SO 2 NHSO 2 (alkyl)} ) and a group consisting of a salt thereof, N- aryl sulfonylsulfamoyl group _{(-SO 2 NHSO 2 (aryl)} ) and a group consisting of a salt thereof, N- alkylsulfonylcarbamoyl group ( -CONHSO ₂ (alkyl)) and its salts,

N-arylsulfonylcarbamoyl group (—CONHSO ₂ (aryl)) and a salt thereof, alkoxysilyl group (—Si (Oalkyl) ₃ ), aryloxysilyl group (—Si (Oaryl) ₃ ), hydroxysilyl group ( -Si (OH) ₃ ) and groups thereof, phosphono groups (-PO ₃ H ₂ ) and groups thereof, dialkylphosphono groups (-PO ₃ (alkyl) ₂ ), diarylphosphono groups (- PO ₃ (aryl) ₂ ), an alkylarylphosphono group (—PO ₃ (alkyl) (aryl)), a monoalkylphosphono group (—PO ₃ H (alkyl)) and a salt thereof, a monoarylphosphono group (-PO ₃ H (aryl)) and its a salt group, phosphonooxy group (-OPO ₃ H ₂₎ and a group consisting of a salt thereof Dialkylphosphono group _{(-OPO 3 (alkyl) 2)} , diaryl phosphono group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphono group _{(-OPO 3 (alkyl) (aryl} )), monoalkyl A group consisting of a phosphonooxy group (—OPO ₂ H (alkyl)) and a salt thereof, a group consisting of a monoarylphosphonooxy group (—OPO ₃ H (aryl)) and a salt thereof, a cyano group, a nitro group, an aryl group , An alkyl group, an alkenyl group, and an alkynyl group.

Among these, as a substituent that can be introduced into R ¹ , a group consisting of a carboxy group and a salt thereof, an alkoxycarbonyl group, and an aryloxycarbonyl group are more preferable, and a group consisting of a carboxy group and a salt thereof is more preferable.

In general formula (I), R ² represents a divalent hydrocarbon group and may further have a substituent. The divalent hydrocarbon group may contain one or more heteroatoms selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom.

Examples of the substituent that can be introduced into R ² include the same substituents as those described as the substituent that can be introduced into R ¹ . The same applies to preferable substituents.

More preferable examples of the divalent hydrocarbon group represented by R ² include an alkylene group and a phenylene group which may have a substituent. Specific examples include linear or branched alkylene groups such as methylene group, ethylene group, propylene group, butylene group, isopropylene group and isobutylene group, and phenylene group. Moreover, as a more preferable form, what substituted the carboxy group to the said alkylene group is mentioned.

  The carboxy group contained in the general formula (I) may form an alkali metal salt or an ammonium salt.

A more preferable structure of the general formula (I) is a case where R ¹ is a hydrocarbon group substituted with a carboxy group, and R ² is a linear alkylene group or an alkylene group substituted with a carboxy group. . Furthermore, the most preferable structure of the general formula (I) is a case where R ¹ is an alkyl group substituted with a carboxy group, and R ² is a linear alkylene group.

  As a method for introducing the structure represented by the general formula (I) as a side chain into the polymer, for example, a monomer having a structure represented by the general formula (I) is polymerized or copolymerized by a known method. Good. Other methods include a method of reacting poly-p-aminostyrene and chloroacetic acid, and a method of hydrolyzing after reacting polychloromethylstyrene and iminodiacetonitrile. From the viewpoint of more easily controlling the introduction rate of the structure represented by the general formula (I), a method of polymerizing or copolymerizing the monomer having the structure represented by the general formula (I) by a known method is preferable. .

When the specific polymer is a copolymer, it may be a random copolymer, a block copolymer, or a graft copolymer.
For the synthesis of the specific polymer, for example, a polymerization initiator such as peroxides such as di-t-butyl peroxide and benzoyl peroxide, persulfates such as ammonium persulfate, and azo compounds such as azobisisobutyronitrile was used. It can be performed by radical polymerization. The polymerization initiator is appropriately selected depending on the polymerization method to be applied. As the polymerization method, solution polymerization, emulsion polymerization, suspension polymerization and the like are applied.

  As polymerization solvents used in the synthesis, acetone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy -2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, ethyl acetate, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, toluene, water and the like can be mentioned, but are not limited thereto. Not.

<Monomer having structure represented by general formula (I)>
Specific examples of the monomer having the structure represented by the general formula (I) include the following compounds, but the present invention is not limited thereto.

  As a monomer which has a structure represented by general formula (I), what contains the following structures is more preferable.

  Moreover, the following structure is mentioned as a preferable structure of the coupling group with the principal chain skeleton of the polymer represented by Y.

  In the specific polymer, the content of the structure represented by the general formula (1) is preferably 5 mol% or more from the viewpoint of sufficiently exerting the effect of improving the printing durability due to the interaction with the aluminum support. 20 mol% or more is more preferable.

  As a weight average molecular weight of the specific polymer used for this invention, 500-1,000,000 are preferable and 1,000-500,000 are more preferable.

<Other monomer components>
The specific polymer used in the present invention may be a copolymer obtained by copolymerizing other monomer components for the purpose of further enhancing the interaction with the support or the interaction with the image recording layer. As the other monomer component, for example, from the viewpoint of improving the adhesion to the hydrophilic treatment substrate, "monomer having an onium group", from the viewpoint of improving the adhesion to the hydrophilic treatment substrate and improving the developer solubility. From the viewpoint of improving the adhesion to the image recording layer, “monomer having an acid group”, “monomer having a functional group capable of interacting with the image recording layer” and the like can be mentioned.

<Monomer having an onium group>
Examples of the monomer having an onium group include, but are not limited to, monomers represented by the following general formulas (A) to (C).

In general formulas (A) to (C), J represents a divalent linking group. K represents an aromatic group or a substituted aromatic group. M represents a divalent linking group. Y ¹ represents a group V atom in the periodic table. Y ² represents an atom belonging to Group VI of the periodic table. Z ⁻ represents a counter anion. R ² represents a hydrogen atom, an alkyl group or a halogen atom. R ³ , R ⁴ , R ⁵ and R ⁷ each independently represents a hydrogen atom, an alkyl group, an aromatic group or an aralkyl group, and these may further have a substituent. R ⁶ represents an alkylidine group or a substituted alkylidine group. R ³ and R ⁴ , R ⁶ and R ⁷ may be bonded to each other to form a ring. j, k, and m each independently represents 0 or 1. u represents an integer of 1 to 3.

Among the monomers having an onium group represented by the general formulas (A) to (C), more preferable are the following cases.
J represents -COO- or -CONH-, and K represents a phenylene group or a substituted phenylene group. The substituent introduced when K is a substituted phenylene group is preferably a hydroxy group, a halogen atom or an alkyl group.
M is an alkylene group and a divalent linking group having a molecular formula of C _n H _2n O, C _n H _2n S, or C _n H _{2n + 1n} . However, n represents the integer of 1-12 here.
Y ¹ represents a nitrogen atom or a phosphorus atom, and Y ² represents a sulfur atom.
Z ⁻ represents a halogen ion, PF ₆ ⁻ , BF ₄ ⁻ or R ⁸ SO ₃ ⁻ .
R ² represents a hydrogen atom or an alkyl group.
R ³ , R ⁴ , R ⁵ and R ⁷ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms or an aromatic group having 6 to 10 carbon atoms to which a substituent may be bonded. Represents a group or an aralkyl group having 7 to 10 carbon atoms. R ⁶ is preferably an alkylidine group having 1 to 10 carbon atoms or a substituted alkylidine. R ³ and R ⁴ , R ⁶ and R ⁷ may be bonded to each other to form a ring.
j, k and m each independently represent 0 or 1, but it is preferable that j and k are not 0 at the same time.
R ⁸ represents an alkyl group having 1 to 10 carbon atoms, an aromatic group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms, to which a substituent may be bonded.

Among the monomers having an onium group represented by the general formulas (A) to (C), particularly preferred are the following cases.
K represents a phenylene group or a substituted phenylene group, and when it is a substituted phenylene group, the substituent represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
M represents an alkylene group having 1 to 2 carbon atoms or an alkylene group having 1 to 2 carbon atoms linked by an oxygen atom.
Z ⁻ represents a chlorine ion or R ⁸ SO ₃ ^— .
R ² represents a hydrogen atom or a methyl group.
j is 0 and k is 1.
R ⁸ represents an alkyl group having 1 to 3 carbon atoms.

  Although the specific example of the monomer which has an onium group used suitably for a specific polymer below is given, this invention is not limited to these.

<Monomer having an acid group>
The monomer having an acid group that is suitably used for the specific polymer will be described. The acid group contained in the monomer having an acid group is particularly preferably a carboxy group, a sulfo group or a phosphonic acid group, but is not limited thereto.

<Monomer having carboxy group>
The monomer having a carboxy group is not particularly limited as long as it is a polymerizable compound having a carboxy group and a polymerizable double bond in its structure.
Preferable examples of the monomer having a carboxy group include compounds represented by the following general formula (1).

In General Formula (1), R ^{1 to} R ⁴ each independently represent a hydrogen atom, an alkyl group, or an organic group represented by the following General Formula (2), and at least one of R ^{1 to} R ⁴ is It is an organic group represented by Formula (2).
Here, from the viewpoint of copolymerizability and raw material availability when producing the specific polymer, R ^{1 to} R ⁴ may have 1 to 2 organic groups represented by the following general formula (2). It is particularly preferable to have one. From the viewpoint of the flexibility of the specific polymer obtained as a result of the polymerization, among R ^{1 to} R ⁴ , in addition to the organic group represented by the following general formula (2), an alkyl group or a hydrogen atom is preferable. Particularly preferred is a hydrogen atom.
For the same reason, when R ^{1 to} R ⁴ are alkyl groups, it is preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group.

  In general formula (2), X represents a single bond, an alkylene group, an arylene group which may have a substituent, or any one of the following structural formulas (i) to (iii). From the viewpoints of polymerizability, availability, etc., a single bond, an arylene group represented by a phenylene group or one represented by the following structural formula (i) is preferred, and an arylene group or one represented by the following structural formula (i) Are more preferable, and those represented by the following structural formula (i) are particularly preferable.

In structural formulas (i) to (iii), Y represents a divalent linking group, and Ar represents an arylene group which may have a substituent. Y is preferably an alkylene group having 1 to 16 carbon atoms or a single bond. In the alkylene group, methylene (—CH ₂ —) represents an ether bond (—O—), a thioether bond (—S—), an ester bond (—COO—), an amide bond (—CONR—, R represents a hydrogen atom or an alkyl group). A bond that may be substituted with a methylene group, an ether bond or an ester bond is particularly preferable.
Among such divalent linking groups, particularly preferred specific examples are listed below.

  Particularly preferred examples of the monomer having a carboxy group represented by the general formula (1) are shown below, but the present invention is not limited thereto.

<Monomer having a sulfo group>
The monomer having a sulfo group is not particularly limited as long as it is a polymerizable compound having a sulfo group and a polymerizable double bond in its structure.
Preferable specific examples of the monomer having a sulfo group include 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, and 4-styrenesulfonic acid.

<Monomer having a phosphonic acid group>
The monomer having a phosphonic acid group is not particularly limited as long as it is a polymerizable compound having a phosphonic acid group and a polymerizable double bond in its structure.
Preferable specific examples of the monomer having a phosphonic acid group include acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, and acid phosphoxypolyoxyethylene glycol monomethacrylate.

<Other monomers>
Specific examples of other monomers are given below, but the present invention is not limited thereto.

  (1) N- (4-hydroxyphenyl) acrylamide or N- (4-hydroxyphenyl) methacrylamide, o-, m- or p-hydroxystyrene, o- or m-bromo-p-hydroxysterene, o- or Acrylamides, methacrylamides, acrylates, methacrylates and hydroxystyrenes having an aromatic hydroxy group such as m-chloro-p-hydroquinstyrene, o-, m- or p-hydroxyphenyl acrylate or methacrylate Kind;

  (2) N- (o-aminosulfonylphenyl) acrylamide, N- (m-aminosulfonylphenyl) acrylamide, N- (p-aminosulfonylphenyl) acrylamide, N- [1- (3-aminosulfonyl) naphthyl] acrylamide Acrylamides such as N- (2-aminosulfonylethyl) acrylamide, N- (o-aminosulfonylphenyl) methacrylamide, N- (m-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) methacryl Amides, methacrylamides such as N- [1- (3-aminosulfonyl) naphthyl] methacrylamide, N- (2-aminosulfonylethyl) methacrylamide, o-aminosulfonylphenyl acrylate, m-aminosulfonylphenyl Unsaturated sulfonamides such as acrylic acid esters such as acrylate, p-aminosulfonylphenyl acrylate, 1- (3-aminosulfonylphenylnaphthyl) acrylate, o-aminosulfonylphenyl methacrylate, m-aminosulfonylphenyl methacrylate, p-amino Unsaturated sulphonamides such as methacrylic acid esters such as sulfonylphenyl metatalylate and 1- (3-aminosulfonylphenylnaphthyl) methacrylate;

(3) phenylsulfonyl acrylamide, which may have a substituent such as tosyl acrylamide, and phenylsulfonyl methacrylamide, which may have a substituent such as tosyl methacrylamide;
(4) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxy group, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate;

  (5) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, phenyl acrylate, benzyl acrylate, acrylic acid-2 -(Substituted) acrylic esters such as chloroethyl, 4-hydroxybutyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate;

  (6) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, methacrylic acid-2 -(Substituted) methacrylate esters such as chloroethyl, 4-hydroxybutyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate;

  (7) Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-ethyl methacrylamide, N-hexyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N- Cyclohexylmethacrylamide, N-hydroxyethylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-phenylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N-nitrophenylacrylamide, N-nitrophenylmethacrylamide N-ethyl-N-phenylacrylamide and N-ethyl-N-phenylmethacrylamide, etc. :

  (8) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, phenyl vinyl ether;

(9) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate;
(10) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene;
(11) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone;
(12) Olefin such as ethylene, propylene, isobutylene, butadiene, isoprene;

(13) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile, etc .;
(14) Lactone group-containing monomers such as pantoyl lactone (meth) acrylate, α- (meth) acryloyl-γ-butyrolactone, β- (meth) acryloyl-γ-butyrolactone;
(15) Ethylene oxide group-containing monomers such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and methoxypolyethylene glycol mono (meth) acrylate.

In the specific polymer, the content of other monomers described above is preferably 95 mol% or less, and more preferably 80 mol% or less.
Among the other monomers, it is more preferable to copolymerize (4) acrylic acid esters and methacrylic acid esters having an aliphatic hydroxy group, (5) acrylic acid esters, and (6) methacrylic acid esters.

  Hereinafter, although the specific example (P-1 to P-21) of the specific polymer used suitably for this invention is given, this invention is not limited to these. Moreover, the polymer B used in the Example is also used suitably.

  As for content of the specific polymer in an intermediate | middle layer, 50-100 mass% is preferable with respect to the total solid which comprises an intermediate | middle layer, and 80-100 mass% is more preferable.

<Formation of intermediate layer>
The intermediate layer used in the present invention is provided by applying the coating solution (intermediate layer forming coating solution) in which each component of the above-described intermediate layer is dissolved on the above-described lithographic printing plate support by various methods. be able to. Although there is no restriction | limiting in particular in the method of apply | coating an intermediate | middle layer, The following method is mentioned as a typical thing. That is, (1) A solution in which the specific polymer in the present invention is dissolved in an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof, or a mixed solvent of these organic solvent and water is applied onto a support. A coating method provided by drying. Alternatively, (2) the support is immersed in a solution in which the specific polymer in the present invention is dissolved in an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof, or a mixed solvent of these organic solvents and water. Thereafter, a coating method in which the intermediate layer is formed by washing and drying with water or air or the like can be mentioned.

  In the application method (1), a solution having a concentration of 0.005 to 10% by mass in total may be applied by various methods. As the coating means, any means such as bar coater coating, spin coating, spray coating, curtain coating, etc. may be used. In the coating method (2), the concentration of the solution is 0.005 to 20% by mass, preferably 0.01 to 10% by mass, and the immersion temperature is 0 to 70 ° C., preferably 5 to 60 ° C. The soaking time is 0.1 to 5 minutes, preferably 0.5 to 120 seconds.

  The above intermediate layer forming coating solution includes basic substances such as ammonia, triethylamine and potassium hydroxide, inorganic acids such as hydrochloric acid, phosphoric acid, sulfuric acid and nitric acid, organic sulfonic acids such as nitrobenzenesulfonic acid and naphthalenesulfonic acid, PH is adjusted with organic phosphonic acids such as phenylphosphonic acid, organic acidic substances such as organic carboxylic acids such as benzoic acid, coumaric acid and malic acid, naphthalenesulfonyl chloride, organic chlorides such as benzenesulfonyl chloride, etc., pH 0-12, More preferably, it can also be used in the range of pH 0-6. In addition, a substance that absorbs ultraviolet light, visible light, infrared light, or the like can be added to the coating solution for forming an intermediate layer in order to improve the tone reproducibility of the lithographic printing plate.

The total coating amount of the intermediate layer in the present invention after drying is appropriately 1 to 100 mg / m ² , and preferably ² to 70 mg / m ² .

Although the operation of the intermediate layer used in the present invention is not clear, it is considered as follows.
That is, since the specific polymer contained in the intermediate layer used in the present invention has the structure represented by the general formula (I), the specific polymer can strongly interact with the surface of the support. It is considered that the adhesion with the recording layer is improved. For this reason, even if the surface of the support for a lithographic printing plate has extremely high hydrophilicity by the alkali metal silicate treatment described above, it is considered that excellent printing durability is realized.
In general, an image recording layer (thermal positive type image recording layer) containing an alkali-soluble polymer compound and a photothermal conversion substance, which will be described later, is near the support surface due to thermal diffusion to the support during exposure. The reaction does not proceed until the removal of the image recording layer in the non-image area may be incomplete, but in the present invention, the removability of the specific polymer used in the intermediate layer is good, In the case where a thermal positive type image recording layer is provided, it is considered that the occurrence of contamination in the non-image area is effectively suppressed.

[Image recording layer]
As described above, after providing an intermediate layer on a lithographic printing plate support, an image recording layer is further provided to obtain the lithographic printing plate precursor of the present invention. The lithographic printing plate precursor according to the invention is provided with the above-described intermediate layer and an image recording layer described later on the above-described lithographic printing plate support in this order, but depending on the purpose, other layers ( For example, the above-described back coat layer and an overcoat layer described later) can be provided.

A photosensitive composition is used for the image recording layer. The photosensitive composition suitably used in the present invention is not particularly limited. For example, a thermal positive photosensitive composition containing an alkali-soluble polymer compound and a photothermal conversion substance (hereinafter referred to as this composition and the composition). The image recording layer was referred to as “thermal positive type”), a thermal negative photosensitive composition containing a curable compound and a photothermal conversion substance (hereinafter also referred to as “thermal negative type”), and photopolymerization type photosensitive. Composition (hereinafter also referred to as “photopolymer type”), negative photosensitive composition containing diazo resin or photocrosslinking resin (hereinafter also referred to as “conventional negative type”), positive containing quinonediazide compound Type photosensitive composition (hereinafter also referred to as "conventional positive type"), photosensitive composition that does not require a special development step (Referred to below as "non-treatment type".) And the like.
Also, as a thermal positive type, a thermal negative type, etc., the digitized image information is carried on a high-convergence radiation such as a laser beam, and the lithographic printing plate precursor is scanned and exposed with the light, via a lith film. Without any problem, it is preferably used in computer-to-plate (CTP) technology for directly producing a lithographic printing plate. Therefore, an image recording layer that can be written by infrared laser exposure and used for such applications is preferable.
Hereinafter, these suitable photosensitive compositions will be described.

<Thermal positive type>
<Photosensitive layer>
The thermal positive type photosensitive composition contains an alkali-soluble polymer compound and a photothermal conversion substance. In the thermal positive type image recording layer, the photothermal conversion substance converts the energy of light such as infrared lasers into heat, which effectively eliminates the interaction that reduces the alkali solubility of alkali-soluble polymer compounds. To do.

Examples of the alkali-soluble polymer compound include a resin containing an acidic group in the molecule and a mixture of two or more thereof. In particular, a phenolic hydroxy group, sulfonamide group (in -SO ₂ NH-R (wherein, R represents a hydrocarbon group.)), Active imino group _{(-SO 2 NHCOR, -SO 2 NHSO} 2 R, -CONHSO A resin having an acidic group such as ₂ R (wherein R has the same meaning as described above) is preferable in terms of solubility in an alkali developer.
In particular, a resin having a phenolic hydroxy group is preferable in that it has excellent image-forming properties when exposed to light such as an infrared laser, and examples thereof include phenol-formaldehyde resins, m-cresol-formaldehyde resins, p-cresol-formaldehyde resins, m- / p-mixed cresol-formaldehyde resin, phenol / cresol (any of m-, p- and m- / p-mixed) mixed-formaldehyde resin (phenol-cresol-formaldehyde co-condensation resin) and other novolak resins Are preferable.
Furthermore, a polymer compound described in JP-A No. 2001-305722 (particularly [0023] to [0042]), and a repetition represented by the general formula (1) described in JP-A No. 2001-215893 Preferred examples also include polymer compounds containing units and polymer compounds described in JP-A No. 2002-311570 (particularly [0107]).

  Preferable examples of the photothermal conversion substance include pigments or dyes having a light absorption region in the infrared region having a wavelength of 700 to 1200 nm from the viewpoint of recording sensitivity. Examples of the dye include 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 (for example, , Nickel thiolate complex). Among these, cyanine dyes are preferable, and cyanine dyes represented by the general formula (I) described in JP 2001-305722 A are particularly preferable.

The thermal positive type photosensitive composition can contain a dissolution inhibitor. As the dissolution inhibitor, for example, a dissolution inhibitor as described in JP-A-2001-305722, [0053] to [0055] is preferably exemplified.
In addition, in the thermal positive type photosensitive composition, as a additive, a sensitivity modifier, a printing agent for obtaining a visible image immediately after heating by exposure, a compound such as a dye as an image colorant, a coating property In addition, it is preferable to include a surfactant for improving the processing stability. For these, compounds as described in [0056] to [0060] of JP-A No. 2001-305722 are preferable.
The photosensitive composition described in detail by Unexamined-Japanese-Patent No. 2001-305722 is preferably used also in respects other than the above.

Further, the thermal positive type image recording layer is not limited to a single layer but may have a two-layer structure.
As an image recording layer having a two-layer structure (multilayer image recording layer), a lower layer (hereinafter referred to as “A layer”) having excellent printing durability and solvent resistance is provided on the side close to the support, and a positive layer is provided thereon. A type provided with a layer having excellent image formability (hereinafter referred to as “B layer”) is preferable. This type has high sensitivity and can realize a wide development latitude. The B layer generally contains a photothermal conversion substance. Preferred examples of the photothermal conversion substance include the dyes described above.
As the resin used for the A layer, a polymer having a monomer having a sulfonamide group, an active imino group, a phenolic hydroxy group or the like as a copolymerization component is preferably used because it has excellent printing durability and solvent resistance. . As the resin used for the B layer, an alkaline aqueous solution-soluble resin having a phenolic hydroxy group is preferably exemplified.
In addition to the resin, the composition used for the A layer and the B layer can contain various additives as necessary. Specifically, various additives as described in [0062] to [0085] of JP-A-2002-3233769 are preferably used. Further, the additives described in [0053] to [0060] of JP-A-2001-305722 described above are also preferably used.
About each component which comprises A layer and B layer, and its content, it is preferable to make it describe in Unexamined-Japanese-Patent No. 11-218914.

<Others>
As a method for producing a thermal positive type image recording layer and a plate making method, methods described in detail in JP-A No. 2001-305722 can be used.

<Thermal negative type>
The thermal negative photosensitive composition contains a curable compound and a photothermal conversion substance. The thermal negative type image recording layer is a negative photosensitive layer in which a portion irradiated with light such as an infrared laser is cured to form an image portion.
<Polymerized layer>
As one of the thermal negative type image recording layers, a polymerization type image recording layer (polymerization layer) is preferably exemplified. The polymerization layer contains a photothermal conversion substance, a radical generator, a radical polymerizable compound that is a curable compound, and a binder polymer. In the polymerization layer, infrared light absorbed by the photothermal conversion substance is converted into heat, the radical generator is decomposed by this heat to generate radicals, and the radical polymerizable compound is polymerized in a chain by the generated radicals and cured. .

As a photothermal conversion substance, the photothermal conversion substance used for the thermal positive type mentioned above is mentioned, for example. Specific examples of particularly preferred cyanine dyes include those described in JP-A-2001-133969, [0017] to [0019].
Preferable examples of the radical generator include onium salts. In particular, onium salts described in JP-A-2001-133969, [0030] to [0033] are preferable.
Examples of the radically polymerizable compound include compounds having at least one terminal ethylenically unsaturated bond, preferably two or more.
As the binder polymer, a linear organic polymer is preferably exemplified. Preferable examples include linear organic polymers that are soluble or swellable in water or weak alkaline water. Among them, a (meth) acrylic resin having an unsaturated group such as an allyl group or an acryloyl group or a benzyl group and a carboxy group in the side chain is preferable in that it has an excellent balance of film strength, sensitivity, and developability. .
As the radical polymerizable compound and the binder polymer, those described in detail in [0036] to [0060] of JP-A No. 2001-133969 can be used.

  The additive described in [0061] to [0068] of JP-A No. 2001-133969 is contained in the thermal negative photosensitive composition (for example, a surfactant for improving coatability). Is preferred.

  As a method for producing the polymerization layer and a plate making method, methods described in detail in JP-A No. 2001-133969 can be used.

<Acid cross-linked layer>
Further, as one of the thermal negative type image recording layers, an acid cross-linked image recording layer (acid cross-linked layer) is also preferably exemplified. The acid crosslinking layer comprises a photothermal conversion substance, a thermal acid generator, a compound that crosslinks with an acid that is a curable compound (crosslinking agent), and an alkali-soluble polymer compound that can react with the crosslinking agent in the presence of an acid. contains. In the acid cross-linking layer, infrared light absorbed by the light-to-heat conversion substance is converted into heat, and the thermal acid generator is decomposed by this heat to generate an acid, and the generated acid reacts with the cross-linking agent and the alkali-soluble polymer compound. And harden.

Examples of the photothermal conversion substance include the same substances as those used for the polymerization layer.
Examples of the thermal acid generator include thermal decomposition compounds such as photoinitiators for photopolymerization, photochromic agents for dyes, and acid generators used in microresists.
Examples of the crosslinking agent include an aromatic compound substituted with a hydroxymethyl group or an alkoxymethyl group; a compound having an N-hydroxymethyl group, an N-alkoxymethyl group or an N-acyloxymethyl group; and an epoxy compound.
Examples of the alkali-soluble polymer compound include a novolak resin and a polymer having a hydroxyaryl group in the side chain.

<Photopolymer type>
The photopolymerization type photosensitive composition contains an addition polymerizable compound, a photopolymerization initiator, and a polymer binder.
As the addition polymerizable compound, an ethylenically unsaturated bond-containing compound capable of addition polymerization is preferably exemplified. The ethylenically unsaturated bond-containing compound is a compound having a terminal ethylenically unsaturated bond. Specifically, for example, it has a chemical form such as a monomer, a prepolymer, and a mixture thereof. Examples of monomers include esters of unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, maleic acid) and aliphatic polyhydric alcohol compounds, amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds. Is mentioned.
Moreover, as an addition polymerizable compound, a urethane type addition polymerizable compound is also preferably exemplified.

As the photopolymerization initiator, various photopolymerization initiators or a combination system (photoinitiation system) of two or more photopolymerization initiators can be appropriately selected depending on the wavelength of the light source to be used. For example, the initiation system described in JP-A-2001-22079, [0021] to [0023] is preferable.
The polymer binder not only functions as a film forming agent for the photopolymerization type photosensitive composition, but is soluble or swellable in alkaline water because the image recording layer needs to be dissolved in an alkaline developer. An organic high molecular polymer is used. As such an organic polymer, those described in JP-A-2001-22079, [0036] to [0063] are preferably exemplified.

  In the photopolymer type photopolymerization type photosensitive composition, additives described in JP-A-2001-22079, [0079] to [0088] (for example, a surfactant for improving coatability) , Colorants, plasticizers, thermal polymerization inhibitors).

  Further, it is preferable to provide an oxygen-blocking protective layer on the photopolymer type image recording layer in order to prevent the action of inhibiting the polymerization of oxygen. Examples of the polymer contained in the oxygen barrier protective layer include polyvinyl alcohol and copolymers thereof.

<Conventional negative type>
The conventional negative photosensitive composition contains a diazo resin or a photocrosslinking resin. Among these, a photosensitive composition containing a diazo resin and an alkali-soluble or swellable polymer compound (binder) is preferable.
Examples of the diazo resin include condensates of aromatic diazonium salts and active carbonyl group-containing compounds such as formaldehyde; condensates of p-diazophenylamines and formaldehyde with hexafluorophosphate or tetrafluoroborate. An organic solvent-soluble diazo resin inorganic salt which is a reaction product of In particular, a high molecular weight diazo compound containing 20 mol% or more of a hexamer described in JP-A-59-78340 is preferable.
Examples of the binder include a copolymer containing acrylic acid, methacrylic acid, crotonic acid, or maleic acid as an essential component. Specifically, multi-component copolymers of monomers such as 2-hydroxyethyl (meth) acrylate, (meth) acrylonitrile, and (meth) acrylic acid as described in JP-A-50-118802, Examples thereof include multi-component copolymers composed of alkyl acrylate, (meth) acrylonitrile and unsaturated carboxylic acid as described in JP-A-56-4144.

  The conventional negative type photosensitive composition has, as an additive, a printing agent, dye, and flexibility and abrasion resistance described in JP-A-7-281425, [0014] to [0015]. It is preferable to contain a plasticizer for imparting, a compound such as a development accelerator, and a surfactant for improving coating properties.

<Conventional positive type>
The conventional positive-type photosensitive composition contains a quinonediazide compound. Among these, a photosensitive composition containing an o-quinonediazide compound and an alkali-soluble polymer compound is preferable.
Examples of the o-quinonediazide compound include esters of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride and phenol-formaldehyde resin or cresol-formaldehyde resin, described in US Pat. No. 3,635,709. And esters of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin.
Examples of the alkali-soluble polymer compound include phenol-formaldehyde resin, cresol-formaldehyde resin, phenol-cresol-formaldehyde co-condensation resin, polyhydroxystyrene, N- (4-hydroxyphenyl) methacrylamide copolymer, A carboxy group-containing polymer described in JP-A-7-36184, an acrylic resin containing a phenolic hydroxy group as described in JP-A-51-34711, and described in JP-A-2-866 Examples thereof include acrylic resins having a sulfonamide group and urethane resins.

  Conventional positive type photosensitive compositions include compounds such as sensitivity modifiers, printing agents, dyes and the like described in JP-A-7-92660, [0024] to [0027] as additives. It is preferable to contain a surfactant for improving the coating property as described in [0031] of Kaihei 7-92660.

<Non-treatment type>
Examples of the non-processing type photosensitive composition include a thermoplastic fine particle polymer type, a microcapsule type, and a sulfonic acid-generating polymer-containing type. These are all heat-sensitive types containing a photothermal conversion substance. The photothermal conversion substance is preferably the same dye as that used in the above-described thermal positive type.

The thermoplastic fine particle polymer type photosensitive composition is obtained by dispersing a hydrophobic and heat-meltable fine particle polymer in a hydrophilic polymer matrix. In the image recording layer of the thermoplastic fine particle polymer type, the hydrophobic fine particle polymer is melted by heat generated by exposure and is fused to form a hydrophobic region, that is, an image portion.
As the fine particle polymer, those in which fine particles melt and coalesce with heat are preferable, and those having a hydrophilic surface and capable of being dispersed in a hydrophilic component such as dampening water are more preferable. Specifically, ResearchDisclosureNo. 33303 (January 1992), JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, and JP-A-9-171250, and European Patent Application Publication No. 931,647. Preferred examples thereof include thermoplastic fine particle polymers. Of these, polystyrene and polymethyl methacrylate are preferred. Examples of the fine particle polymer having a hydrophilic surface include those in which the polymer itself is hydrophilic; those in which a hydrophilic compound such as polyvinyl alcohol and polyethylene glycol is adsorbed on the surface of the fine particle polymer to make the surface hydrophilic.
The fine particle polymer preferably has a reactive functional group.

  As a microcapsule type photosensitive composition, a compound having a heat-reactive functional group as described in JP-A No. 2000-118160 or JP-A No. 2001-277740 is included. A microcapsule type is preferable.

  Examples of the sulfonic acid generating polymer used in the sulfonic acid generating polymer-containing photosensitive composition include sulfonic acid ester groups, disulfone groups, and sec- or tert-sulfonamides described in JP-A No. 10-282672. Examples thereof include polymers having a group in the side chain.

  By incorporating a hydrophilic resin into the unprocessed photosensitive composition, not only on-press developability is improved, but also the film strength of the photosensitive layer itself is improved. Examples of the hydrophilic resin include those having a hydrophilic group such as hydroxy group, carboxy group, hydroxyethyl group, hydroxypropyl group, amino group, aminoethyl group, aminopropyl group, carboxymethyl group, and hydrophilic sol-gel conversion system. A binder resin is preferred.

  The unprocessed type image recording layer does not require a special development step and can be developed on a printing press. As a method for producing an unprocessed image recording layer and a plate-making printing method, methods described in detail in JP-A No. 2002-178655 can be used.

<Overcoat layer>
In the untreated type lithographic printing plate precursor, a water-soluble overcoat layer can be provided on the image recording layer in order to prevent contamination of the surface of the heat-sensitive layer with a lipophilic substance. The water-soluble overcoat layer used in the present invention is preferably one that can be easily removed during printing, and contains a resin selected from water-soluble organic polymer compounds.
As the water-soluble organic polymer compound, a film formed by coating and drying has film-forming ability. Specifically, for example, polyvinyl acetate (however, a hydrolysis rate of 65% or more), polyacrylic Acid and its alkali metal salt or amine salt, polyacrylic acid copolymer and its alkali metal salt or amine salt, polymethacrylic acid and its alkali metal salt or amine salt, polymethacrylic acid copolymer and its alkali metal salt or amine Salt, polyacrylamide and copolymer thereof, polyhydroxyethyl acrylate, polyvinylpyrrolidone and copolymer thereof, polyvinyl methyl ether, polyvinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamide-2-methyl-1- Propanesulfonic acid and its alkenyl Metal salt or amine salt, poly-2-acrylamido-2-methyl-1-propanesulfonic acid copolymer and alkali metal salt or amine salt thereof, gum arabic, fiber derivative (for example, carboxymethyl cellulose, carboxyethyl cellulose, Methyl cellulose, etc.) and modified products thereof, white dextrin, pullulan, enzymatically decomposed etherified dextrin and the like. In addition, two or more of these resins can be mixed and used depending on the purpose.

Moreover, you may add a water-soluble thing among the photothermal conversion agents mentioned above to an overcoat layer. Furthermore, for the purpose of ensuring the uniformity of coating, a nonionic surfactant such as polyoxyethylene nonylphenyl ether or polyoxyethylene dodecyl ether can be added to the overcoat layer in the case of aqueous solution coating. .
The dry coating amount of the overcoat layer is preferably 0.1 to 2.0 g / m ² . Within this range, the on-press developability is not impaired, and the surface of the heat-sensitive layer can be satisfactorily prevented from being contaminated with lipophilic substances such as fingerprints.

[Manufacture of lithographic printing plates]
The lithographic printing plate precursor using the lithographic printing plate support obtained by the present invention is made into a lithographic printing plate by various treatment methods according to the image recording layer.
Examples of the active light source used for image exposure include a mercury lamp, a metal halide lamp, a xenon lamp, and a chemical lamp. Examples of the laser beam include a helium-neon laser (He-Ne laser), an argon laser, a krypton laser, a helium-cadmium laser, a KrF excimer laser, a semiconductor laser, a YAG laser, and a YAG-SHG laser.

After the above exposure, if the image recording layer is one of a thermal positive type, a thermal negative type, a conventional negative type, a conventional positive type, and a photopolymer type, it is exposed and then developed using a developer to obtain a lithographic printing plate. It is preferable to obtain.
The developer is preferably an alkaline developer, and more preferably an alkaline aqueous solution substantially free of an organic solvent.
Moreover, the developing solution which does not contain alkali metal silicate substantially is also preferable. As a method of developing using a developer substantially not containing an alkali metal silicate, a method described in detail in JP-A No. 11-109637 can be used.
A developer containing an alkali metal silicate can also be used.

When the image recording layer is an unprocessed type, the lithographic printing plate precursor according to the present invention is mounted on a printing machine without further processing after image exposure and is usually used with ink and / or fountain solution. You can print with the procedure. Further, as described in Japanese Patent No. 2938398, after being mounted on a printing machine cylinder, it is exposed by a laser mounted on the printing machine, and then ink and / or dampening water is applied to perform on-machine development. It is also possible to do. In these cases, since the heat-sensitive layer is removed by ink and / or fountain solution on the printing press, there is no need for a separate development step, and there is no need to stop the printing press for printing after development. Printing can be continued as soon as development is completed.
Even in the case of having an untreated type heat-sensitive layer, it can be used for printing after developing with water or an appropriate aqueous solution as a developer.

1. Production of planographic printing plate precursors (Examples 1 to 6 and Comparative Examples 1 to 5)
<Aluminum plate>
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.005 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: Containing 0.03% by mass, the balance is prepared using Al and an inevitable impurity aluminum alloy, and after performing the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Created. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, the temperature was kept constant at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Furthermore, after performing heat processing using a continuous annealing machine at 500 degreeC, it finished by cold rolling to 0.24 mm in thickness, and obtained the aluminum plate of JIS1050 material. After making this aluminum plate width 1030mm, it used for the roughening process shown below.

<Roughening treatment>
As the roughening treatment, as shown in Table 1, any of the following roughening treatments A to D was performed.

<Roughening treatment A>
The roughening treatment A was performed by continuously performing the following various treatments (a) to (i). After each treatment and washing with water, the liquid was removed with a nip roller.

(A) Mechanical surface roughening treatment Using an apparatus as shown in FIG. 1, a suspension of abrasive (pumice) having a specific gravity of 1.12 and water is supplied as a polishing slurry to the surface of the aluminum plate. However, a mechanical surface roughening treatment was performed with a rotating roller-like nylon brush. In FIG. 1, 1 is an aluminum plate, 2 and 4 are roller brushes, 3 is a polishing slurry, and 5, 6, 7 and 8 are support rollers. The average particle size of the abrasive was 40 μm, and the maximum particle size was 100 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkaline etching treatment The aluminum plate was subjected to an etching treatment by spraying using an aqueous solution having a caustic soda concentration of 2.6 mass%, an aluminum ion concentration of 6.5 mass%, and a temperature of 70 ° C., thereby dissolving 6 g / m ^{2 of the} aluminum plate. . Then, water washing by spraying was performed.

(C) Desmutting treatment Desmutting treatment was performed by spraying with a 1% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a step of performing an electrochemical surface roughening treatment using alternating current in a nitric acid aqueous solution.

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10.5 g / L aqueous solution of nitric acid (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions) at a liquid temperature of 50 ° C. The AC power supply waveform is the waveform shown in FIG. 2, the time TP until the current value reaches the peak from zero is 0.8 msec, the duty ratio is 1: 1, the trapezoidal rectangular wave AC is used, with the carbon electrode as the counter electrode An electrochemical roughening treatment was performed. Ferrite was used for the auxiliary anode. The electrolytic cell used was the one shown in FIG. The current density was 15 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm 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.
Then, water washing by spraying was performed.

(E) Alkaline etching treatment The aluminum plate was subjected to an etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass%, and the aluminum plate was dissolved at 0.25 g / m ² . Removes the smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening treatment was performed using alternating current in the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

(F) Desmut treatment Desmut treatment by spraying was performed with a 15% by weight aqueous solution of sulfuric acid at a temperature of 30 ° C. (containing 4.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a step of performing an electrochemical surface roughening treatment using alternating current in a nitric acid aqueous solution.

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 7.5 g / L aqueous solution (containing 5 g / L of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform is the waveform shown in FIG. 2. The time TP until the current value reaches a peak from zero is 0.8 msec, the duty ratio is 1: 1, a trapezoidal rectangular wave AC is used, with the carbon electrode as the counter electrode An electrochemical roughening treatment was performed. Ferrite was used for the auxiliary anode. The electrolytic cell used was the one shown in FIG. The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode.
Then, water washing by spraying was performed.

(H) Alkaline etching treatment An aluminum plate was subjected to an etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass%, and the aluminum plate was dissolved at 0.10 g / m ² . Removes the smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening treatment was performed using alternating current in the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

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

<Roughening treatment B>
In the roughening treatment B, (a) is not performed, (d), (e), and (f) are not performed, and in (g), the amount of electricity is the amount of electricity when the aluminum plate is an anode. Except for the sum total of 500 C / dm ² , the same method as roughening treatment A was used.

<Roughening treatment C>
In the roughening treatment C, the above (a) is not performed. In (d), the current density is set to 30 A / dm ² at the peak current value, and the above (g), (h), and (i) are performed. Except not performed, it was performed by the same method as the surface roughening treatment A.

<Roughening treatment D>
Roughening treatment D is a rough surface except that in (d) above, the current density was set to 30 A / dm ² at the peak current value, and (g), (h) and (i) were not performed. This was carried out in the same manner as in the conversion treatment A.

<Anodizing treatment>
After the surface roughening treatment, anodizing treatment was performed using an anodizing apparatus having a structure shown in FIG. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 170 g / L (containing 0.5 mass% of aluminum ions) and a temperature of 33 ° C. The current density was 27 A / dm ² for all. The anodizing treatment was performed for a total of 8 seconds. Then, water washing by spraying was performed. The final oxide film amount was 2.7 g / m ² .

<Alkali metal silicate treatment (silicate treatment)>
Furthermore, the alkali metal silicate treatment (silicate treatment) was performed by immersing the aluminum plate after the anodizing treatment in one of the following silicate treatment solutions 1 and 2 for 10 seconds.
In addition, pH 13 aqueous solution was prepared by adding 1.62 mass% sodium hydroxide to No. 3 sodium silicate aqueous solution.

<Silicate treatment solution>
1: 3 sodium silicate aqueous solution, concentration 1.0 mass%, temperature 20 ° C., pH 11.2
2: No. 3 sodium silicate and sodium hydroxide aqueous solution, No. 3 sodium silicate concentration 2.5 mass%, sodium hydroxide concentration 1.6 mass%, temperature 70 ° C., pH 13.0

<Washing treatment>
After the alkali metal silicate treatment, the substrate was washed with water to obtain a lithographic printing plate support. The washing treatment was performed by a spray method using any of the following washing waters I to IV.

<Washing water>
I: Pure water II: Well water (Ca ion concentration 25 ppm)
III: Calcium chloride aqueous solution with a concentration of 210 mg / L (Ca ion concentration 76 ppm)
IV: A calcium chloride aqueous solution having a concentration of 2100 mg / L (Ca ion concentration of 760 ppm)

<Formation of intermediate layer>
As shown in Table 1, either of the intermediate layers A and B was provided on the lithographic printing plate support obtained above.
<Intermediate layer A>
The intermediate layer A was bar-coated with a 0.3% by mass methanol solution of polymer A (weight average molecular weight 50,000) represented by the following formula so that the wet amount was 7.5 g / m ^2, and then 100 ° C. And dried for 8 seconds.

<Intermediate layer B>
The intermediate layer B was provided in the same manner as the intermediate layer A, except that the polymer B represented by the following formula was used instead of the polymer A (weight average molecular weight 50,000).

<Formation of image recording layer>
After providing an intermediate layer on the lithographic printing plate support, an image recording layer coating solution 1 having the following composition was applied so that the coating amount was 0.8 g / m ^2, and manufactured by TABAI, PERFECT OVEN PH-200. And Wind Control was set to 7 and dried at 140 ° C. for 50 seconds.
Thereafter, an image recording layer coating solution 2 having the following composition was applied so that the coating amount was 0.2 g / m ² and dried at 140 ° C. for 60 seconds to form a multilayer thermal positive type image recording layer. .

<Coating liquid 1 for image recording layer>
N- (4-aminosulfonylphenyl) methacrylamide / acrylonitrile / methyl methacrylate copolymer (molar ratio 36/34/30, weight average molecular weight 50,000, acid value 2.65) 2.133 g
-Cyanine dye A represented by the following formula: 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.030 g
・ The counter ion of ethyl violet is changed to an anion of 6-hydroxy-2-naphthalenesulfonic acid 0.100 g
-Fluorosurfactant (Megafac F-780-F, manufactured by Dainippon Ink and Chemicals, 30% by mass solution) 0.023 g
・ Methyl ethyl ketone 25.41g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-butyrolactone 13.2 g

<Image recording layer coating solution 2>
-M, p-cresol novolak resin (m / p ratio = 6/4, weight average molecular weight 4,500, containing 0.8% by mass of unreacted cresol) 0.3479 g
-Cyanine dye A represented by the above formula 0.0192 g
-Ethyl methacrylate / mono-2- (methacryloyloxy) -ethyl succinate copolymer (molar ratio 67/32) in 1-methoxy-2-propanol solution (concentration 30% by mass) 0.1403 g
・ Compound Y represented by the following formula: 0.0043 g
Fluorine-based surfactant (Megafac F-780-F, manufactured by Dainippon Ink & Chemicals, Inc., 30% by mass solution) 0.015 g
・ Fluorine-containing compound (Megafac F-781-F, manufactured by Dainippon Ink & Chemicals, Inc.) 0.0033 g
・ Methyl ethyl ketone 10.39g
・ 1-methoxy-2-propanol 20.78 g

2. The amount of Si on the surface of the lithographic printing plate support The amount of Si on the surface before providing the intermediate layer of the lithographic printing plate precursor obtained in Examples 1 to 6 and Comparative Examples 1 to 5 was measured using a fluorescent X-ray analyzer. The measurement was made by the calibration curve method. The results are shown in Table 1.
As a standard sample for preparing a calibration curve, an aqueous solution containing a known amount of silicon atoms was uniformly dropped into an area of 30 mmφ on an aluminum plate and then dried. The conditions for fluorescent X-ray analysis are shown below.

  X-ray fluorescence analyzer: RIX3000 manufactured by Rigaku Corporation, X-ray tube: Rh, measurement spectrum: Si-Kα, tube voltage: 50 kV, tube current: 50 mA, slit: COARSE, spectral crystal: RX4, detector: F -PC, analysis area: 30 mmφ, peak position (2θ): 144.75 deg. , Background (2θ): 140.70 deg. And 146.85 deg. Integration time: 80 seconds / sample

3. The amount of Ca on the surface of the lithographic printing plate support The amount of Ca on the surface before providing the intermediate layer of the lithographic printing plate precursor obtained in Examples 1 to 6 and Comparative Examples 1 to 5 was measured using a fluorescent X-ray analyzer. The measurement was made by the calibration curve method. The results are shown in Table 1.
As a standard sample for preparing a calibration curve, an aqueous solution containing a known amount of calcium atoms was uniformly dropped into an area of 30 mmφ on an aluminum plate and then dried. The conditions for fluorescent X-ray analysis are shown below.

  X-ray fluorescence analyzer: RIX3000 manufactured by Rigaku Corporation, X-ray tube: Rh, measurement spectrum: Ca-KA, tube voltage: 50 kV, tube current: 50 mA, slit: COARSE, spectral crystal: GE, detector: PC , Analysis area: 30 mmφ, peak position (2θ): 61.950 deg. , Background (2θ): 59.500 deg. And 64.500 deg. Integration time: 80 seconds / sample

4). Exposure and development of lithographic printing plate precursor The lithographic printing plate precursor obtained above is exposed using a Trend setter manufactured by Creo under the conditions of a beam intensity of 10 W and a drum rotation speed of 150 rpm, and an FM screen (Staccato 20, manufactured by Creo) The test pattern created in step 1 was drawn in an image.
Next, a 1: 8 water diluted solution (conductivity of about 43 mS / cm) of developer DT-2 manufactured by Fuji Photo Film Co., Ltd. was charged as the developer, and finisher FG-1 manufactured by Fuji Photo Film Co., Ltd. was used as the finisher. Using a PS processor LP940H manufactured by Fuji Photo Film Co., Ltd., which was charged with a 1: 1 water dilution solution, the lithographic printing plate precursor after exposure was maintained for 12 seconds while maintaining the developer and finisher liquid temperature at 30 ° C. Development was performed to obtain a lithographic printing plate.

5. Evaluation of lithographic printing plate precursor The entanglement stain resistance and printing durability of the lithographic printing plate obtained above were evaluated by the following methods. (1) Anti-entanglement stain resistance The lithographic printing plate obtained above is mounted on a printing machine SOR-M manufactured by Heidelberg, and printing is performed. %) Was visually evaluated for the degree of occurrence of entanglement stains.
The results are shown in Table 1. In the table, ◯ indicates that no entanglement stain occurred, and X indicates that the entanglement stain occurred and the halftone dot was almost completely crushed.

(2) Printing durability The printing durability was evaluated based on the number of printed sheets when it was visually recognized that the density of the solid image of the printed material began to decrease.
The results are shown in Table 1.

As is apparent from Table 1, the lithographic printing plate precursors (Examples 1 to 6) of the present invention are excellent in both entanglement stain resistance and printing durability.
On the other hand, when the amount of Si on the surface of the lithographic printing plate support is too small (Comparative Examples 1 and 2), the entanglement stain resistance is poor. Further, when the amount of Ca on the surface of the lithographic printing plate support is too small (Comparative Examples 3 and 5), the printing durability is poor. Further, even when the Si amount and the Ca amount on the surface of the lithographic printing plate support are within the scope of the present invention, the polymer contained in the intermediate layer is composed only of a monomer having an acid group and a monomer having an onium group. (Comparative Example 4) is inferior in printing durability.

It is a side view which shows the concept of the process of the brush graining used for the mechanical roughening process in preparation of the support body for lithographic printing plates used for the lithographic printing plate precursor of this invention. It is a graph which shows an example of the alternating waveform current waveform figure used for the electrochemical roughening process in preparation of the support body for lithographic printing plates used for the lithographic printing plate precursor of this invention. It is a side view which shows an example of the radial type cell in the electrochemical roughening process using alternating current in preparation of the support body for lithographic printing plates used for the lithographic printing plate precursor of this invention. It is the schematic of the anodizing apparatus used for the anodizing process in preparation of the support body for lithographic printing plates used for the lithographic printing plate precursor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum plate 2, 4 Roller-shaped brush 3 Polishing slurry liquid 5, 6, 7, 8 Support roller 11 Aluminum plate 12 Radial drum roller 13a, 13b Main electrode 14 Electrolytic process liquid 15 Electrolyte supply port 16 Slit 17 Electrolyte path 18 Auxiliary anodes 19a, 19b Thyristors 20 AC power supply 40 Main electrolytic tank 50 Auxiliary anode tank 410 Anodizing device 412 Power supply tank 414 Electrolytic treatment tank 416 Aluminum plate 418, 426 Electrolytic solution 420 Power supply electrode 422, 428 Roller 424 Nip roller 430 Electrolytic electrode 432 Tank wall 434 DC power supply

Claims (5)

Obtained by performing at least the alkali metal silicate treatment and subsequent washing treatment to the aluminum plate, Si of the surface is 5 to 15 mg / m ^2, and alkaline earth metal elements of the surface is 1 mg / m ² A lithographic printing plate precursor comprising an intermediate layer containing a polymer having a structure represented by the following general formula (I) in the side chain and an image recording layer on the lithographic printing plate support as described above.

(In the formula, Y represents a linking group to the main chain skeleton of the polymer. R ¹ represents a hydrogen atom or a monovalent hydrocarbon group. R ² represents a divalent hydrocarbon group.)   The lithographic printing plate precursor according to claim 1, wherein the washing treatment is performed using an alkaline earth metal element-containing liquid.   The lithographic printing plate precursor as claimed in claim 1 or 2, wherein the alkaline earth metal element is calcium.   The lithographic printing plate precursor according to any one of claims 1 to 3, wherein the alkali metal silicate treatment is performed using an aqueous alkali metal silicate solution having a pH of 11.5 to 13.5.   The lithographic printing plate precursor according to any one of claims 1 to 4, wherein the image recording layer is an image recording layer containing an alkali-soluble polymer compound and a photothermal conversion substance.

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