JP2002099092A - Original plate for planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original plate for planographic printing plate which is free from a staining caused by a local residual film of a non-image part and easily carries out fine adjustment of the amount of water during printing. SOLUTION: The original plate for planographic printing plate which is characterized by providing a recording layer which contains an infrared absorbent and a high molecular compound insoluble in water but soluble in alkaline solution and improves the solubility to an alkaline developing solution by exposure with infrared laser beams, on supporting body which is an aluminum substrate subjected to a surface roughening in which a recess having width of >=8 μm or a recess having the maximum depth of >=1.7 μm in the direction perpendicular to the width is ten or less within 1 mm, which supporting body possesses 30<= of 85 degree of grossiness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate, and more particularly to a lithographic printing plate precursor provided with a heat mode recording layer that can be written by exposure to an infrared laser.

[0002]

2. Description of the Related Art In recent years, with the development of image forming technology, a laser beam having a narrow beam is scanned on a plate surface, and a character document, an image document, and the like are formed directly on the plate surface. It is becoming possible to make plates. However, in a so-called thermal type lithographic printing plate in which a positive image is formed by increasing the alkali solubility by causing photothermal conversion in the photosensitive layer, heat is generated by a photothermal conversion material in the photosensitive layer by laser light irradiation, and the heat is generated. Causes an image forming reaction, but if there is a deep dent due to the surface roughening treatment on the roughened aluminum support on which the anodic oxide film is formed, the photosensitive layer in that part becomes thicker, so the bottom of the dent is formed. In this case, the image forming reaction becomes insufficient, and a local residual film (hereinafter, referred to as a local film)
This causes a problem that a non-image portion is generated during printing. Also,
In the printing operation, fine adjustment of the water scale is made based on the glossiness of the water on the plate surface, so if the surface roughness after the surface roughening process is shallow, the glossiness of the non-image area increases, There is a problem that it is difficult to finely adjust the amount of water. An attempt was made to improve the above problem by making the shape of the support surface specific. For example, Japanese Patent Application Laid-Open No. 9-86068 discloses a "pit diameter" for a pit diameter of 1.5 μm or less.
Prevents non-image areas from being stained during printing by forming a rough surface with a pit shape where the gradient of the straight line is 0.300 or less by temporary regression analysis of "maximum depth in the direction perpendicular to the diameter" Although it has been proposed to obtain excellent suitability for ballpoint pens, the method disclosed in this publication achieves suppression of the pot-like residual film, but improves the ease of fine adjustment of the water amount during printing. There is room for

Japanese Patent Application Laid-Open No. 11-184074 discloses that a large pit has a double structure, a large pit has an average opening diameter of 3 μm or more and 6 μm or less, has uniformity, and has an average small pit average. The aperture diameter is 0.2 μm or more and 0.8 μm or less, and the ratio of the depth of small pits to the opening diameter is 0.2 or less, thereby improving dot gain with high definition, improving blanket dirt, and squeezing water. Improvement of dirt resistance and improvement of Yupo paper printing at the time of printing have been proposed. According to the method disclosed in the official gazette, it is easy to finely adjust the amount of water at the time of printing, but suppression of pot-like residual film is achieved. Is still desired to be improved. Also, Japanese Patent Application Laid-Open No. 6-135175 discloses at least 2
It has been proposed to prevent background contamination and clogging of shadow portions by including a brush graining step of roughening the surface with a brush of the type described above. Although it is easy to perform, it is difficult to completely remove the recording layer near the bottom of the pit in the brush grain process, and there is room for improvement in suppressing the remaining film.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thermal type lithographic printing plate precursor which has no local residual film in the non-image area and which can easily finely adjust the amount of water during printing. And

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have limited the size and number of recesses formed in an aluminum support before coating a photosensitive layer, and have set the glossiness of the surface to a predetermined value. The inventors have found that the above objects can be achieved by setting the range, and have completed the present invention. That is, the lithographic printing plate precursor of the present invention is a roughened aluminum substrate and has a recess having a width of 8 μm or more, or a recess having a maximum depth of 1.7 μm or more perpendicular to the width of 1 mm. An infrared absorber, a water-insoluble and aqueous alkali-soluble polymer compound is contained on a support having a glossiness of 85 degrees or less within 10 places between them, and is soluble in an alkali developing solution by infrared laser exposure. Characterized in that a recording layer for improving the The concave portion of the aluminum substrate can be measured by observing the cross-sectional shape of the substrate with a scanning electron microscope. When a cross-section at an arbitrary position is measured, the concave portion may have a width of 8 μm or more, or may be perpendicular to the width. With a maximum depth of 1.7 μm or more,
Within 10 mm, the glossiness of the obtained aluminum support is set to 30 or less at 85 degree glossiness specified in JIS Z8741-1997.

In the present invention, the possibility that the photosensitive layer existing in the deep portion remains may be controlled by controlling the recesses of the roughened aluminum substrate exceeding a predetermined width and depth within a predetermined range. It is estimated that it can be kept low. However, if the surface is excessively smoothed by suppressing the presence of a wide or deep concave portion, the adhesion to the photosensitive layer is reduced, or the glossiness at the time of printing increases, and fine adjustment of the water amount becomes difficult. In the present invention, the 85 degree glossiness of the aluminum support is controlled to 30 or less to suppress the occurrence of residual film, the adhesion to the photosensitive layer, and the ease of fine adjustment of the amount of water during printing. It is now possible to satisfy all genders.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The support used for the lithographic printing plate precursor according to the present invention is a roughened aluminum substrate having, in its cross-sectional shape, a concave portion having a width of 8 μm or more or a maximum depth in the direction perpendicular to the width of 1 μm. A recess of 7 μm or more is
And preferably no more than 7 such recesses, and most preferably no such recesses. Further, it is necessary that the 85-degree glossiness measured according to the method specified in JIS Z8741-1997 is 30 or less, and the glossiness is preferably in the range of 10 to 30.

Hereinafter, a method for producing a support having the above preferable surface characteristics will be described in the order of steps. [Aluminum support] (Support substrate) The aluminum support used in the present invention is a dimensionally stable metal containing aluminum as a main component.
That is, the support is made of aluminum or an aluminum alloy. In addition to a pure aluminum plate, it is selected from an alloy plate containing aluminum as a main component and containing a trace amount of a different element, or a plastic film or paper on which aluminum (alloy) is laminated or evaporated. In addition,
A composite sheet in which an aluminum sheet is bonded on a polyethylene terephthalate film as described in JP-A-18327 may be used. In the following description, the above-mentioned substrate made of aluminum or an aluminum alloy or a substrate having a layer made of aluminum or an aluminum alloy is collectively used as an aluminum substrate. The foreign elements contained in the aluminum base metal include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, titanium and the like, and the content of the foreign elements in the alloy is 10% by weight or less. . In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to produce due to refining technology, and therefore may contain a slightly different element. As described above, the composition of the aluminum plate applied to the present invention is not specified, but is a conventionally known and used material such as JI.
S A1050, JIS A1100, JIS A31
03, JIS A3005, etc. can be used as appropriate. The thickness of the aluminum substrate used in the present invention is about 0.1 mm to 0.6 mm. This thickness can be appropriately changed according to the size of the printing press, the size of the printing plate, and the user's request.

Such an aluminum substrate is subjected to various surface treatments described below to obtain an aluminum support. (Graining treatment) The aluminum plate is grained to a more preferable shape. The graining treatment method is disclosed in
Mechanical graining, chemical etching, electrolytic grains, etc., as disclosed in US Pat. Furthermore, an electrochemical graining method in which the aluminum surface is electrochemically grained in a hydrochloric acid or nitric acid electrolyte, a wire brush graining method in which the aluminum surface is scratched with a metal wire, and a ball graining method in which the aluminum surface is grained with a polishing ball and an abrasive. Alternatively, a mechanical graining method such as a brush grain method for graining the surface with a nylon brush and an abrasive can be used, and the above graining methods can be used alone or in combination.

Among them, the method of forming a grain surface usefully used in the present invention is an electrochemical graining method in which the grain is electrochemically grained in a hydrochloric acid or nitric acid electrolyte. the amount of electricity 50C / dm ² ~400C /
dm ² . More specifically, 0.1 to 50
% Hydrochloric acid or nitric acid in an electrolytic solution at a temperature of 20 to 100%.
° C, time 1 second to 30 minutes, current density 100 C / dm ² -4
This is performed using a direct current or an alternating current under the condition of 00 C / dm ² . Electrochemical roughening is inevitable in improving the adhesion between the photosensitive layer and the substrate because it is easy to provide fine irregularities on the surface. By this surface roughening, craters or honeycomb-shaped pits having an average diameter of about 0.5 to 20 μm can be formed on the aluminum surface at an area ratio of 30 to 100%. The pits provided here have the effect of making the non-image portion of the printing plate less liable to stain and improving the printing durability. In the electrochemical treatment, the quantity of electricity necessary to provide sufficient pits on the surface, that is, the product of the current and the time during which the current is passed is an important condition in electrochemical surface roughening. It is desirable from the viewpoint of energy saving that sufficient pits can be formed with a smaller amount of electricity. As the surface roughness after the surface roughening treatment, it is preferable that the center line average roughness (Ra) is 0.2 to 0.6 μm and the maximum height is (Rmax) = 2.5 to 6.0 μm. Further, at least width 2 to 2 by the roughening treatment
30 μm, preferably 5 to 10 μm, the maximum depth in the vertical direction to the width 0.1 to 5 μm, preferably 0.5 to 2 μm, and the ratio of the maximum depth in the width / width in the vertical direction is 2 or more, Preferably, five or more recesses are formed, and more preferably, the recesses having a width of 8 μm or more or a maximum depth of 1.7 μm or more perpendicular to the width are within 10 places within 1 mm. .

(Etching process after graining) The grained aluminum substrate is chemically etched with an acid or an alkali, if necessary. When an acid is used as an etching agent, it takes time to destroy a fine structure, which is disadvantageous in industrially applying the present invention. However, it can be improved by using an alkali as an etching agent. Alkali agents suitably used in the present invention include caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, and the like. The preferred ranges of concentration and temperature are 1 to 50, respectively. %, 20 to 100 ° C,
It is preferable that the amount of Al dissolved is 0.01 to 10 g / m ² , more preferably 0.1 to 5 g / m ^2.
And the range. After etching, pickling is performed to remove dirt (smut) remaining on the surface. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borofluoric acid are used. In particular, as a method for removing the smut after the electrochemical surface-roughening treatment, it is preferable to use a method described in JP-A-53-12739.
A method of contacting with sulfuric acid of 15 to 65% by weight at a temperature of ９０90 ° C. and a method of alkali etching described in JP-B-48-28123 are exemplified.

(Anodic Oxidation Treatment) The aluminum substrate treated as described above is further subjected to an anodic oxidation treatment. The anodizing treatment can be performed by a method conventionally performed in this field. Specifically, when a direct current or an alternating current is applied to aluminum in an aqueous solution or a non-aqueous solution by using sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid or the like alone or in combination of two or more thereof, aluminum is supported. An anodized film can be formed on the body surface. At this time, at least A
Components normally contained in 1 alloy plates, electrodes, tap water, groundwater and the like may of course be included. Further, the second and third components may be added. Here, the second and third components include, for example, Na, K, Mg, Li, Ca, Ti, Al,
Ions of metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Zn and the like, cations such as ammonium ion, nitrate ion, carbonate ion, hydrochloric acid ion, phosphate ion, fluorine ion, sulfite ion, titanate Examples include anions such as ions, silicate ions, and borate ions, and the concentration may be about 0 to 10000 ppm.

The conditions of the anodic oxidation treatment vary depending on the electrolytic solution to be used, and thus cannot be unconditionally determined. However, in general, the concentration of the electrolytic solution is 1 to 80%, and the solution temperature is -5 to 70%.
° C, current density 0.5-60 A / dm ² , voltage 1-100
V, the electrolysis time is suitably in the range of 10 to 200 seconds. Among these anodizing treatments, in particular, British Patent No. 1,41
The method of anodizing at a high current density in a sulfuric acid electrolytic solution described in US Pat. No. 2,768 is preferable. In the present invention, the anodized film formed is preferably in the range of 1 to 10 g / m ^2, forming amount of the coating film tends to enter scratches on the plate is less than 1 g / m ^2, a 10 g / m ² If it exceeds, a large amount of power is required for production, which is economically disadvantageous. Preferably, it is 1.5 to 7 g / m ² , more preferably ² to 5 g / m ² .

(Hydrophilic treatment method) For the purpose of enhancing the hydrophilicity of the metal or metal compound layer, it is desirable to carry out the following hydrophilic treatment. US Patent No. 27140
Nos. 66 and 3181461 or alkali metal silicates disclosed in JP-B-36-22063 and potassium fluorozirconate and polyvinylphosphonic acid as disclosed in U.S. Pat. No. 4,153,461. There is a method of processing. Alternatively, a method of treating with an aqueous solution containing a phosphate and an inorganic fluorine compound disclosed in JP-A-9-244227 can be used. Further, a method of treating with an aqueous solution containing titanium and fluorine disclosed in JP-A Nos. 10-252078 and 10-263411 can be used. Among them, treatment with an alkali metal silicate or polyvinyl phosphonic acid is preferred.

The alkali metal silicate used in the hydrophilization treatment of the present invention includes sodium silicate, potassium silicate,
Lithium silicate or the like is used. In this hydrophilization treatment, the content of the alkali metal silicate is 0.01 to 30% by weight, preferably 0.01 to 10% by weight, particularly preferably 0.05 to 3% by weight. Anodized aluminum support is placed in an aqueous solution of an alkali metal silicate having a pH of 10 to 13 at 25 ° C. at 4 to 80 ° C. for 0.5 to 120 seconds, preferably 2 to 80 ° C.
The immersion method for up to 30 seconds can be preferably performed by appropriately selecting the processing conditions such as the concentration of the alkali metal silicate, the processing temperature, and the processing time so that the attached amount of Si atoms becomes the above specific amount. In performing this hydrophilization treatment, if the pH of the alkali metal silicate aqueous solution is lower than 10, the solution gels, and if the pH is higher than 13.0, the anodic oxide film is dissolved.

In the hydrophilization treatment of the present invention, if necessary, a hydroxide can be blended to adjust the pH of the aqueous solution of the alkali metal silicate to a high value. Examples of the hydroxide include sodium hydroxide and water. Examples include potassium oxide and lithium hydroxide. If necessary, an alkaline earth metal salt or a Group IVB metal salt may be added to the aqueous alkali metal silicate solution. Examples of the alkaline earth metal salts include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate, and sulfates, hydrochlorides, phosphates, acetates, oxalates, and borates of these alkaline earth metals. And water-soluble salts such as salts. IV
Examples of the group B metal salt include titanium tetrachloride, titanium trichloride, potassium titanium fluoride, titanium potassium oxalate, titanium sulfate, titanium tetraiodide, zirconium chloride, zirconium dioxide, zirconium oxychloride, and zirconium tetrachloride. Can be. Alkaline earth metal salts or Group IVB metal salts can be used alone or in combination of two or more. The preferred use amount range of these metal salts is 0.01 to 10% by weight, and the more preferred range is 0.05 to 5.0% by weight. The concentration of the aqueous solution used for the polyvinyl phosphonic acid treatment is 0.01
10 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.2 to 2.5% by weight, at a temperature of 10 ° C to 70 ° C and preferably 30 ° C to 60 ° C. .5
It is appropriate to perform the processing for from 10 seconds to 10 minutes, more preferably from 1 second to 30 seconds.

(Observation of cross-sectional shape) Observation of the cross-sectional shape is performed as follows. In order to obtain a cross-sectional shape, first, a method is used in which a support piece is embedded in a resin, and the support piece is polished or cut with a microtome in a direction perpendicular to the surface of the support. Although any polishing method may be used, it goes without saying that so-called mirror polishing is suitable for cross-sectional observation at high magnification. The observation is performed by taking a photograph with a normal electron microscope from the front of the section. The photographing magnification at this time is about 3000 to about 10000 times, and is arbitrarily selected according to the size of the recess so that the width and depth of the recess can be easily recognized. Photographing is performed while moving the sample in accordance with the range to be photographed, so that the observation range is at least 1 mm or more. In order to confirm the state of the concave portion of the support according to the present invention, a portion near the center except for the edge portion of about 100 mm with respect to the width of the support is randomly observed at five or more places, and the width is 8 μm or more. It is preferable to use a method of counting the number of concave portions having a maximum depth of 1.7 μm or more in a direction perpendicular to the width and averaging the number.

The definition of the "width of the concave portion" and the "depth of the concave portion" measured by the method of the present invention can be made by direct measurement of an electron micrograph, and the "width of the concave portion" is merely the edge of the concave portion of the cross-sectional photograph. If the recess is not open perpendicularly to the plane of the aluminum fabric, this straight line will not be parallel to the plane of the aluminum fabric. The “maximum depth of the recess in the direction perpendicular to the width” is the position where the depth in the direction perpendicular to the straight line of the “width of the recess” is maximum. The width of the line is not the position of the perpendicular bisector of the straight line. In addition, regarding the concave portion having the shape in which the pits overlap, the overlapping pit is regarded as one concave portion,
The "maximum depth of the concave portion in the direction perpendicular to the width" with respect to the "width of the concave portion" is to be measured. The number and depth of the pits per unit length can be controlled by a conventional method by adjusting the processing conditions such as the above-described surface roughening and etching.

(Measurement of Glossiness) The glossiness of the aluminum support of the present invention can be determined in accordance with the method for measuring 85-degree glossiness in specular glossiness specified in JIS Z8741-1997. For actual measurement, a known variable-angle gloss meter, for example, a digital variable-angle gloss meter UGV-4K manufactured by Suga Test Instruments Co., Ltd. may be used. The glossiness of the untreated aluminum substrate is about 90 to 140, but after the surface treatment described above, it is substantially 10 to 3
It is about 0, which is within the preferred range of the present invention, but if it exceeds 30 due to surface treatment conditions, it can be easily reduced to 30 or less by adjusting the treatment conditions of the electrochemical graining treatment. When the 85 degree glossiness is 30 or less, fine unevenness on the surface contributes to the water retention of the dampening water, so that the synergistic effect with the function of the surface hydrophilic treatment facilitates the fine adjustment of the water amount at the time of printing. It can be carried out, but if the value exceeds 30, it is not preferable because this property cannot be sufficiently exhibited.

[Image forming layer] The following image forming layer is formed on the support of the present invention prepared as described above, if necessary. The image forming layer used in the present invention is not particularly limited as long as it can be written by irradiation with an infrared laser and improves the solubility of the recording layer. It is possible to record directly by such infrared laser exposure,
The photosensitive layer in which the solubility of the exposed portion in an alkali developing solution is increased is hereinafter referred to as a thermal positive type photosensitive layer.
As the photosensitive layer for the laser positive writing type lithographic printing plate of the thermal positive type, known ones can be applied. For example, JP-A-9-222737 and JP-A-9-90610 can be used.
JP-A-9-87245, JP-A-9-43845
, Japanese Patent Application Laid-Open No. 7-306528, Japanese Patent Application No. 10-229099, Japanese Patent Application No.
The photosensitive layer, the recording layer and the like described in each specification of No. 240601 can be used.

Such a thermal positive type photosensitive layer is
It contains an infrared absorber, a water-insoluble and aqueous alkali-soluble polymer compound and other optional components. Because it is a positive recording layer, its image forming mechanism is based on the acid and heat energy itself generated by light irradiation and heating.
The polymer compound forming the layer becomes soluble in water or alkaline water by a function such as release of the bond, and is removed by development to form a non-image portion.

In the present invention, the water-insoluble and alkali-water-soluble polymer is simply referred to as "alkali-water-soluble polymer" as appropriate. As such a polymer compound, it is preferable to use a homopolymer containing an acidic group in a main chain and / or a side chain in the polymer, a copolymer thereof, or a mixture thereof. Above all, (1)
Those having an acidic group described in (6) in the main chain and / or side chain of the polymer are preferable in terms of solubility in an alkaline developer and development of dissolution inhibiting ability.

(1) Phenol group (—Ar—OH) (2) Sulfonamide group (—SO ₂ NH—R) (3) Substituted sulfonamide acid group (hereinafter referred to as “active imide group”) SO ₂ NHCOR, -SO ₂ NHSO ₂ R, -CO
NHSO ₂ R] (4) Carboxylic acid group (—CO ₂ H) (5) Sulfonic acid group (—SO ₃ H) (6) Phosphate group (—OPO ₃ H ₂ )

In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrocarbon group which may have a substituent. .

Among the alkaline water-soluble polymers having an acidic group selected from the above (1) to (6), among the alkaline water-soluble polymers having (1) a phenol group, (2) a sulfonamide group and (3) an active imide group, A polymer is preferable, and an alkali water-soluble polymer having (1) a phenol group or (2) a sulfonamide group is most preferable in terms of sufficiently securing solubility in an alkaline developer, development latitude, and film strength. These alkaline water-soluble polymers can be arbitrarily selected from known ones and applied.
Specifically, for example, Japanese Patent Application No. 11-3 filed by the present applicant
No. 57048, paragraph numbers [0051] to [006]
8] can be suitably applied.

These alkaline water-soluble polymer compounds include:
One type or a combination of two or more types may be used, and 30 to 99% by weight, preferably 40 to 95% by weight, and particularly preferably 50% by weight, based on the total solid content of the photosensitive composition.
It is used in an amount of up to 90% by weight.

The infrared absorbing agent contained in the recording layer according to the present invention has a function of converting the absorbed infrared rays into heat, causing a photochemical reaction or the like by laser scanning, and dissolving the recording layer in a developing solution. Greatly increase. The infrared absorbent used in the present invention has a wavelength of 760 nm to 12 nm.
It is a dye or pigment that effectively absorbs 00 nm infrared rays. Preferably, the dye or the pigment has an absorption maximum at a wavelength of 760 nm to 1200 nm. Any of these infrared absorbers can be used as long as they have a photothermal conversion function with respect to the exposure wavelength. Specifically, for example, paragraph No. [0] of JP-A-11-985 by the present applicant.
038] to [0050] can be suitably applied. The addition amount of these dyes or pigments is preferably about 0.01 to 30% by weight based on the total solid content of the recording layer coating solution.

In the recording layer according to the present invention, if necessary, various known additives can be used in combination. The lithographic printing plate precursor of the present invention can be obtained by dissolving these compounds in a suitable solvent to prepare a photosensitive layer coating solution, and coating the solution on an aluminum support having the specific surface area described above. . The coating amount (solid content) of the recording layer according to the present invention varies depending on the application, but is 0.01 to 3.
It is adjusted to the range of 0 g / m ² . As a method of applying, various methods can be used, for example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating,
Roll coating and the like can be mentioned. As the coating amount decreases, the apparent sensitivity increases, but the film characteristics of the recording layer deteriorate.

[0029]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. (Example 1) [Production of support] JIS A105 having a plate thickness of 0.24 mm
0 aluminum plate is subjected to an etching treatment at a temperature of 70 ° C. with a 26 wt% sodium hydroxide aqueous solution (containing 6.5 wt% aluminum ions), and 6 g of the aluminum plate
/ M ² , washed with water, neutralized with a 25% by weight aqueous solution of sulfuric acid, washed with water, and then used as an electrolytic solution with a 0.8% by weight aqueous solution of hydrochloric acid (containing 0.5% by weight of aluminum ions) at a temperature of 35 ° C. Using a 60 Hz rectangular wave alternating current, electrolytic surface roughening treatment was performed so that the current density was 25 A / dm ² and the total amount of electricity at the time of the anode of the aluminum plate was 200 C / dm ² . Next, an etching treatment is performed at a temperature of 35 ° C. with a 5 wt% aqueous solution of sodium hydroxide (including 1.5 wt% of aluminum ions), and the main component is aluminum hydroxide generated when the preceding electrolytic surface roughening is performed. Removal of the smut component, dissolution of the edge portion of the generated pit, and smoothing of the edge portion were performed, followed by washing with water. The amount of aluminum dissolved excluding the amount of smut generated by the electrolytic surface roughening treatment was 0.3 g / m ² .

Thereafter, a 1 wt% aqueous solution of nitric acid (0.5 wt% aluminum ion, 0.007 ammonium ion)
(% by weight) as an electrolytic solution, using a rectangular wave alternating current at a temperature of 50 ° C. and a frequency of 60 Hz, so that the current density is 30 A / dm ² and the total amount of electricity at the time of the anode of the aluminum plate is 210 C / dm ^2. Surface treatment and washing with water were performed to obtain an aluminum support. Next, a 5 wt% aqueous solution of sodium hydroxide (containing 1.5 wt% of aluminum ions) is subjected to an etching treatment at a temperature of 35 ° C., and a smut component mainly composed of aluminum hydroxide generated when performing electrolytic surface roughening in the preceding stage. And a process of dissolving the edge portion of the generated pit and smoothing the edge portion was performed, followed by washing with water. The amount of aluminum dissolved except for the amount of smut generated by the electrolytic surface roughening treatment was 0.2 g / m ² . Subsequently, after neutralizing with a 25 wt% sulfuric acid aqueous solution (containing 0.5 wt% aluminum ions) at a temperature of 60 ° C. and washing with water, in a 170 g / L sulfuric acid electrolyte at a temperature of 50 ° C. and a current density of 5 A / Anodizing treatment was performed at dm ² with a direct current for 50 seconds. After that, 3% at a concentration of 1% by weight and a temperature of 30 ° C
No. 10 sodium silicate aqueous solution for 10 seconds, washed with water and dried to prepare a lithographic printing plate support (A-1).

[Formation of Recording Layer] An undercoat layer was formed on the support (A-1) thus obtained as described below, and then a recording layer coating solution was applied and dried to form a recording layer. (Formation of undercoat layer)
The substrate was dried at 15 ° C. for 15 seconds. The coating amount of the coating film after drying was 15 mg / m ² .

(Undercoat liquid) The following compound 0.3 g methanol 100 g water 1 g

[0033]

Embedded image

Next, the following recording layer coating solution was prepared, and the recording layer coating solution was applied to an undercoated substrate so that the coating amount after drying was 1.0 g / m ² to form a recording layer. A lithographic printing plate precursor (B-1) was obtained.

(Recording Layer Coating Solution) Capric acid 0.03 g Specific copolymer 1 0.75 g m, p-cresol novolak (m, p ratio = 6/4, 0.25 g Weight average molecular weight 3500, Unreacted cresol 0.5% by weight) p-toluenesulfonic acid 0.003 g tetrahydrophthalic anhydride 0.03 g cyanine dye A (the following structure) 0.017 g victoria pure blue BOH counter ion 0.015 g 1-naphthalene Sulfonate anion dye Megafac F-177 0.05 g (produced by Dainippon Ink and Chemicals, Inc., fluorine-based surfactant) γ-butyl lactone 10 g methyl ethyl ketone 10 g 1-methoxy-2-propanol 1 g

[0036]

Embedded image

[Synthesis of Specific Copolymer 1] In a 500 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel, 31.0 g (0.36 mol) of methacrylic acid and 39.1 g (0.36 mol) of ethyl chloroformate were added. Mol) and 200 ml of acetonitrile, and the mixture was stirred while being cooled in an ice-water bath. 36.4 g of triethylamine (0.
(36 mol) was dropped by a dropping funnel over about 1 hour. After the addition, the ice-water bath was removed, and the mixture was stirred at room temperature for 30 minutes.

51.7 g (0.30 mol) of p-aminobenzenesulfonamide was added to the reaction mixture, and the mixture was stirred for 1 hour while being heated to 70 ° C. in an oil bath. After the completion of the reaction, this mixture was added to 1 liter of water while stirring the water, and the resulting mixture was stirred for 30 minutes. The mixture was filtered to remove the precipitate, which was then washed with 500 m of water.
Then, the slurry was filtered and the obtained solid was dried to obtain a white solid of N- (p-aminosulfonylphenyl) methacrylamide (yield 46.9 g).

Next, 4.61 g of N- (p-aminosulfonylphenyl) methacrylamide was placed in a 20 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel.
92 mol), and 2.94 g (0.02 g) of ethyl methacrylate.
Acrylonitrile, 0.80 g (0.015 g)
Mol) and 20 g of N, N-dimethylacetamide, and the mixture was stirred while being heated to 65 ° C. in a hot water bath. This mixture was mixed with “V-65” (manufactured by Wako Pure Chemical Industries, Ltd.).
0.15 g was added, and the mixture was stirred for 2 hours under a nitrogen stream while maintaining at 65 ° C. N- (p-
Aminosulfonylphenyl) methacrylamide 4.61
g, 2.94 g of ethyl methacrylate, 0.80 g of acrylonitrile, N, N-dimethylacetamide and "V-
65 "and a mixture of 0.15 g was added dropwise with a dropping funnel over 2 hours. After the completion of the dropwise addition, the obtained mixture was further stirred at 65 ° C. for 2 hours. After completion of the reaction, 40 g of methanol was added to the mixture, and the mixture was cooled. The obtained mixture was poured into 2 liters of water while stirring the mixture. After stirring the mixture for 30 minutes, the precipitate was taken out by filtration and dried. Gave 15 g of a white solid. The weight average molecular weight (polystyrene standard) of this specific copolymer 1 was measured by gel permeation chromatography and found to be 53.00.
It was 0.

(Example 2) [Production of support] JIS A105 having a thickness of 0.24 mm
0 aluminum plate is subjected to an etching treatment at a temperature of 70 ° C. with a 26 wt% sodium hydroxide aqueous solution (containing 6.5 wt% aluminum ions), and 6 g of the aluminum plate
/ M ² , washed with water, neutralized with a 25% by weight aqueous sulfuric acid solution, washed with water, and then used as an electrolyte with a 1% by weight aqueous nitric acid solution (containing 0.5% by weight of aluminum ion and 0.007% by weight of ammonium ion). , Temperature 50
℃, 0.3Hz rectangular wave alternating current, current density 25A
/ Dm ² , the total amount of electricity when the aluminum plate is the anode is 2
The electrolytic surface roughening treatment was performed so as to be 00 C / dm ² .
Next, a 26 wt% sodium hydroxide aqueous solution (6.5 w
Etching at a temperature of 70 ° C. to remove the smut component mainly composed of aluminum hydroxide generated when performing the electrolytic surface roughening in the preceding stage, and remove the edge portion of the generated pit. Dissolution was performed to smooth the edges. The amount of aluminum dissolved is 3 g excluding the amount of smut generated by electrolytic surface roughening.
/ M ² .

Thereafter, a 1% by weight aqueous nitric acid solution (0.5% by weight of aluminum ion, 0.007% of ammonium ion)
(% by weight) as an electrolytic solution, using a rectangular wave alternating current at a temperature of 50 ° C. and a frequency of 60 Hz, so that the current density is 30 A / dm ² and the total amount of electricity at the time of the anode of the aluminum plate is 210 C / dm ^2. Surface treatment and washing with water were performed to obtain an aluminum support. Next, a 5 wt% aqueous solution of sodium hydroxide (containing 1.5 wt% of aluminum ions) is subjected to an etching treatment at a temperature of 35 ° C., and a smut component mainly composed of aluminum hydroxide generated when performing electrolytic surface roughening in the preceding stage. And a process of dissolving the edge portion of the generated pit and smoothing the edge portion was performed, followed by washing with water. The amount of aluminum dissolved except for the amount of smut generated by the electrolytic surface roughening treatment was 0.2 g / m ² . Subsequently, after neutralizing with a 25 wt% sulfuric acid aqueous solution (containing 0.5 wt% aluminum ions) at a temperature of 60 ° C. and washing with water, in a 170 g / L sulfuric acid electrolyte at a temperature of 50 ° C. and a current density of 5 A / Anodizing treatment was performed at dm ² with a direct current for 50 seconds. After that, 3% at a concentration of 1% by weight and a temperature of 30 ° C
No. 9 sodium silicate aqueous solution for 10 seconds, washed with water and dried to prepare a lithographic printing plate support (A-2). [Formation of Recording Layer] The thus obtained support (A-
In 2), an undercoat layer and a recording layer were formed in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-2).

Example 3 [Preparation of Support] JIS A105 having a thickness of 0.24 mm
0 aluminum plate is subjected to an etching treatment at a temperature of 70 ° C. with a 26 wt% sodium hydroxide aqueous solution (containing 6.5 wt% aluminum ions), and 6 g of the aluminum plate
/ M ² , washed with water, neutralized with a 25% by weight aqueous solution of sulfuric acid, washed with water, and then continuously subjected to electrochemical surface roughening using a DC voltage. At this time, the electrolytic solution was a 1 wt% aqueous solution of nitric acid (aluminum ion 0.5%).
wt%, ammonium ion 0.007wt%),
The liquid temperature was 50 ° C. Ferrite was used for the anode and titanium was used for the force sword. For the electrolysis, a DC voltage having a ripple rate of 20% or less was used. The current density was 80 A / dm ² , and the quantity of electricity was 200 C / dm ² . The cathode and anode were a pair. Thereafter, washing with water by spraying was performed. Next, a 26 wt% sodium hydroxide aqueous solution (6.5 wt%
The etching process is performed at a temperature of 70 ° C. to remove the smut component mainly composed of aluminum hydroxide generated when performing the electrolytic surface roughening in the preceding stage, and dissolve the edge portion of the generated pit. Then, a process for smoothing the edge portion was performed. The amount of aluminum dissolved except for the amount of smut generated in the electrolytic surface roughening treatment was 3 g /
m ² .

Thereafter, a 1% by weight aqueous nitric acid solution (0.5% by weight of aluminum ion, 0.007% of ammonium ion)
(% by weight) as an electrolytic solution, using a rectangular wave alternating current at a temperature of 50 ° C. and a frequency of 60 Hz, so that the current density is 30 A / dm ² and the total amount of electricity at the time of the anode of the aluminum plate is 210 C / dm ^2. Surface treatment and washing with water were performed to obtain an aluminum support. Next, a 5 wt% aqueous solution of sodium hydroxide (containing 1.5 wt% of aluminum ions) is subjected to an etching treatment at a temperature of 35 ° C., and a smut component mainly composed of aluminum hydroxide generated when performing electrolytic surface roughening in the preceding stage. And a process of dissolving the edge portion of the generated pit and smoothing the edge portion was performed, followed by washing with water. The amount of aluminum dissolved except for the amount of smut generated by the electrolytic surface roughening treatment was 0.2 g / m ² . Subsequently, after neutralizing with a 25 wt% sulfuric acid aqueous solution (containing 0.5 wt% aluminum ions) at a temperature of 60 ° C. and washing with water, in a 170 g / L sulfuric acid electrolyte at a temperature of 50 ° C. and a current density of 5 A / Anodizing treatment was performed at dm ² with a direct current for 50 seconds. After that, 3% at a concentration of 1% by weight and a temperature of 30 ° C
No. 10 sodium silicate solution, washed with water and dried to prepare a lithographic printing plate support (A-3). [Formation of Recording Layer] The thus obtained support (A-
An undercoat layer and a recording layer were formed on 3) in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-3).

(Comparative Example 1) [Preparation of Support] JIS A105 having a plate thickness of 0.24 mm
0 aluminum plate is subjected to an etching treatment at a temperature of 70 ° C. with a 26 wt% sodium hydroxide aqueous solution (containing 6.5 wt% aluminum ions), and 6 g of the aluminum plate
/ M ² , washed with water, neutralized with a 25% by weight aqueous sulfuric acid solution, washed with water, and then used as an electrolyte with a 1% by weight aqueous nitric acid solution (containing 0.5% by weight of aluminum ion and 0.007% by weight of ammonium ion). , Temperature 50
And a current density of 30 A /
dm ² , the total amount of electricity when the aluminum plate is the anode is 27
Electrolytic surface-roughening treatment was performed so as to be 0 C / dm ^2, and washing was performed with water to obtain an aluminum support.

Next, a 5 wt% aqueous solution of sodium hydroxide (containing 1.5 wt% of aluminum ions) was heated at a temperature of 35%.
Etching at ℃, removal of smut components mainly composed of aluminum hydroxide generated during the previous electrolytic surface roughening, dissolution of the edge of the generated pits, smoothing the edge And then washed with water. The amount of aluminum dissolved except for the amount of smut generated by the electrolytic surface roughening treatment was 0.2 g / m ² . Subsequently, after neutralizing and washing with a 25% by weight aqueous solution of sulfuric acid (containing 0.5% by weight of aluminum ions) at a temperature of 60 ° C., the solution was heated to a temperature of 50% in a 170 g / L electrolytic solution of sulfuric acid.
Anodizing was performed with a direct current at 50 ° C. and a current density of 5 A / dm ² for 50 seconds. Thereafter, the substrate was immersed in a No. 3 sodium silicate aqueous solution having a concentration of 1% by weight and a temperature of 30 ° C. for 10 seconds, washed with water and dried to prepare a lithographic printing plate support (A-4). [Formation of Recording Layer] The thus obtained support (A-
In 4), an undercoat layer and a recording layer were formed in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-4).

(Comparative Example 2) [Preparation of Support] JIS A105 having a thickness of 0.24 mm
0 aluminum plate is subjected to an etching treatment at a temperature of 70 ° C. with a 26 wt% sodium hydroxide aqueous solution (containing 6.5 wt% aluminum ions), and 6 g of the aluminum plate
/ M ² was dissolved, washed with water, and neutralized with a sulfuric acid concentration of 25 wt% aqueous solution, washed with water, then, nitric acid 2 wt% aqueous solution (aluminum ion 0.5 wt%, including ammonium ions 0.007 wt%) as an electrolyte solution , Temperature 30
And a current density of 60 A /
dm ² , the total amount of electricity at the time of the anode is 40
Electrolytic surface-roughening treatment was performed so as to be 0 C / dm ^2, and washing was performed with water to obtain an aluminum support. Next, a 5 wt% aqueous solution of sodium hydroxide (containing 1.5 wt% of aluminum ions) is subjected to an etching treatment at a temperature of 35 ° C., and a smut component mainly composed of aluminum hydroxide generated when performing electrolytic surface roughening in the preceding stage. And a process of dissolving the edge portion of the generated pit and smoothing the edge portion was performed, followed by washing with water. Dissolution amount of aluminum excluding the amount of smut generated by electrolytic surface roughening treatment is 0.2 g / m
^{Was 2} .

Subsequently, the sulfuric acid concentration at a temperature of 60 ° C. was 25.
After neutralizing with an aqueous solution containing 0.5% by weight of aluminum (containing 0.5% by weight of aluminum ions) and washing with water, the anode was heated in a 170 g / L sulfuric acid electrolyte at a temperature of 50 ° C. and a current density of 5 A / dm ² for 50 seconds under a direct current. It was oxidized. Then, the concentration 1% by weight,
Immersed in a No. 3 sodium silicate aqueous solution at a temperature of 30 ° C. for 10 seconds,
After washing with water and drying, a lithographic printing plate support (A-5) was prepared. [Formation of Recording Layer] The thus obtained support (A-
In 5), an undercoat layer and a recording layer were formed in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-5).

(Comparative Example 3) [Preparation of Support] JIS A105 having a thickness of 0.24 mm
0 aluminum plate is subjected to an etching treatment at a temperature of 70 ° C. with a 26 wt% aqueous sodium hydroxide solution (containing 6.5 wt% of aluminum ions), and an aminium plate of 6 g /
After dissolving m ² , the product was washed with water, neutralized with a 25% by weight aqueous solution of sulfuric acid, washed with water, and then washed with 1% by weight of hydrochloric acid and 2w of acetic acid.
Using a mixed aqueous solution of t% as an electrolytic solution and a rectangular wave alternating current at a temperature of 60 ° C. and a current density of 50 A / dm ² , the quantity of electricity at one time is 8 in terms of the total quantity of electricity when the aluminum plate is an anode.
This was adjusted to 0 C / dm ^2, and this was repeated six times, and electrolytic surface roughening treatment was performed. Thereafter, washing was performed with water to obtain an aluminum support.

Next, a 5 wt% aqueous solution of sodium hydroxide (containing 1.5 wt% of aluminum ions) and a temperature of 35%
Etching at ℃, removal of smut components mainly composed of aluminum hydroxide generated during the previous electrolytic surface roughening, dissolution of the edge of the generated pits, smoothing the edge And then washed with water. The amount of aluminum dissolved except for the amount of smut generated by the electrolytic surface roughening treatment was 0.2 g / m ² . Subsequently, after neutralizing and washing with a 25% by weight aqueous solution of sulfuric acid (containing 0.5% by weight of aluminum ions) at a temperature of 60 ° C., the solution was heated to a temperature of 50% in a 170 g / L electrolytic solution of sulfuric acid.
Anodizing was performed with a direct current at 50 ° C. and a current density of 5 A / dm ² for 50 seconds. Thereafter, the resultant was immersed in a No. 3 sodium silicate aqueous solution having a concentration of 1% by weight at a temperature of 30 ° C. for 10 seconds, washed with water and dried to prepare a lithographic printing plate support (A-6). [Formation of Recording Layer] The thus obtained support (A-
In 6), an undercoat layer and a recording layer were formed in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-6).

(Comparative Example 4) [Preparation of Support] JIS A105 having a thickness of 0.24 mm
The aluminum plate was mechanically roughened with a rotating roller-shaped nylon brush while supplying a 400 mesh aqueous suspension of pumice to the aluminum surface. The nylon brush used was 6.10 nylon, and had a bristle length of 50 mm and a bristle diameter of 0.295 mm. The nylon brush was planted in a stainless steel cylinder having a diameter of 300 mm with a large size so as to be dense. 3 rotating brushes
Used this book. Two support rollers at the bottom of the brush (φ20
0 mm) was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus the load before pressing the brush roller against the aluminum plate. The direction of rotation of the brush was the same as the direction of movement of the aluminum plate.

After washing with water well after the mechanical surface roughening treatment, a 26 wt% sodium hydroxide aqueous solution (6.5 wt%
The aluminum plate is etched at a temperature of 70 ° C., the aluminum plate is dissolved at 6 g / m ² , washed with water, and neutralized with a 25 wt% aqueous solution of sulfuric acid.
After washing with water, a 1 wt% aqueous solution of nitric acid (aluminum ion 0.5 wt%, ammonium ion 0.007 wt%)
% Of comprising) as the electrolytic solution, temperature 50 ° C., using a rectangular wave AC of 60 Hz, the current density 30A / dm ^2, electrolytic rough surface, as the aluminum plate with the 230C / dm ² as the total quantity of electricity when the anode And washed with water to obtain an aluminum support. Next, a 5 wt% sodium hydroxide aqueous solution (containing 1.5 wt% aluminum ions) and a temperature of 35%
Etching at ℃, removal of smut components mainly composed of aluminum hydroxide generated during the previous electrolytic surface roughening, dissolution of the edge of the generated pits, smoothing the edge And then washed with water. The amount of aluminum dissolved except for the amount of smut generated by the electrolytic surface roughening treatment was 0.2 g / m ² .

Subsequently, the sulfuric acid concentration at a temperature of 60 ° C. was 25.
After neutralizing with an aqueous solution containing 0.5% by weight of aluminum (containing 0.5% by weight of aluminum ions) and washing with water, the anode was heated in a 170 g / L sulfuric acid electrolyte at a temperature of 50 ° C. and a current density of 5 A / dm ² for 50 seconds under a direct current. It was oxidized. Then, the concentration 1% by weight,
Immersed in a No. 3 sodium silicate aqueous solution at a temperature of 30 ° C. for 10 seconds,
After washing with water and drying, a lithographic printing plate support (A-7) was prepared. [Formation of Recording Layer] The thus obtained support (A-
An undercoat layer and a recording layer were formed on 7) in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-7).

(Comparative Example 5) [Preparation of support] A lithographic printing plate was prepared in the same manner as in Comparative Example 2, except that the diameter of the bristle of the nylon brush used for the mechanical surface roughening treatment was changed to 0.48 mm. Support (A-
8) was prepared. [Formation of Recording Layer] The thus obtained support (A-
8) An undercoat layer and a recording layer were formed in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-8).

(Comparative Example 6) [Preparation of Support] The number of nylon brushes used for mechanical surface roughening treatment was changed to two, and the first brush had a bristle diameter of 0.72 mm and the second brush had Hair diameter is 0.295mm
A lithographic printing plate support (A-9) was prepared in the same manner as in Comparative Example 2 except that the above materials were used in combination. [Formation of Recording Layer] The thus obtained support (A-
An undercoat layer and a recording layer were formed on 9) in the same manner as in Example 1 to obtain a lithographic printing plate precursor (B-9).

[Evaluation of Lithographic Printing Plate Precursor] (Measurement of Support Surface Properties) Examples 1 to 3 and Comparative Examples 1 to
The lithographic printing plate precursors (B-1) to (B-9) obtained in 6 were output at a power of 500 mW, a wavelength of 830 nm, and a beam diameter of 17 μm.
Main operation speed 5m using (1 / e ² ) semiconductor laser
After exposure, the film was developed for 30 seconds with a diluent of a developer for PS plate manufactured by Fuji Photo Film Co., Ltd. Non-image portions of each of the resulting lithographic printing plates were randomly sampled at five locations, and the cross-section was taken to about 1 m using a JEOL scanning electron microscope T-20.
The length of m was observed at a magnification of 5,000 and the number of recesses having a width of 8 μm or more or a depth of 1.7 μm or more was counted and averaged.
In addition, Suga Test Instruments Co., Ltd. digital variable gloss meter UGV
Using -4K, the 85-degree glossiness of the non-image portion of each printing plate was measured. The results are shown in Table 1.

(Stainability of planographic printing plates) Planographic printing plates (B-1) to (B-) obtained in Examples 1 to 3 and Comparative Examples 1 to 6
Printing was performed using 9). The printing machine used was a Harris chrysanthemum semi-monochrome machine (manufactured by Harris Corporation), and the ink was Geo
Ink (manufactured by Dainippon Ink and Chemicals, Inc.), dampening solution EU-3 (manufactured by Fuji Photo Film Co., Ltd.) diluted 1: 100 with water as a dampening solution, 90 vol% and isopropanol 10 vol% Using each of the mixtures described above, printing was performed on high-quality paper, and adhesion of the ink to the non-image area when printing 1,000 sheets from the start of printing was observed, and pot-like stains were evaluated. An excellent one and a good level having no practical problem were evaluated as ○, and a practically problematic level was evaluated as x. The results are shown in Table 1 below.

(Ease of Adjustment of Amount of Dampening Water on Plate) During printing, the surface of the plate was visually observed, and the amount of dampening water was adjusted based on the glossiness of the non-image area to evaluate the ease of fine adjustment of the amount of water. . Those that were excellent and easy to adjust, and those of a good level were rated as ○, and those that were difficult to finely adjust the amount of water and caused a problem in practice were rated as x. The results are shown in Table 1 below.

[0058]

[Table 1]

From the results in Table 1, it can be seen that the lithographic printing plate precursor of the present invention using the support in which the concave portions having the characteristic conditions were formed had no contamination on the non-image portion of the printing plate obtained after plate making and was excellent. An image of high quality was obtained, and fine adjustment of the amount of water was easy. On the other hand, in Comparative Examples 1 and 2 in which the surface glossiness of the support is high, it is difficult to finely adjust the amount of water, and the lithographic printing plates of Comparative Examples 3 to 6 using the support having a large number of concave portions having a specific size and depth. In the original plate, stains due to the remaining film of the recording layer occur in the non-image area,
Good prints were not obtained. Further, from these examples and comparative examples, the surface characteristics of the support suitable for the present invention are:
It can be seen that this can be achieved by adjusting the conditions of the surface treatment step of the aluminum substrate.

[0060]

According to the present invention, a thermal type lithographic printing plate precursor can be obtained in which a good printed matter free of stains due to a local residual film in a non-image area can be obtained, and fine adjustment of the amount of water during printing is easy. .

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H025 AA04 AB03 AC08 AD03 BG00 BH04 CB52 CC11 DA18 DA20 FA10 FA17 2H096 AA06 BA11 CA03 EA04 EA23 GA08 2H114 AA04 AA22 AA23 BA01 DA04 DA24 DA25 DA26 DA35 DA52 DA73 DA78 GA05 GA06 GA38

Claims (1)

[Claims] 1. An aluminum substrate having been subjected to a surface roughening treatment, wherein a concave portion having a width of 8 μm or more or a concave portion having a maximum depth of 1.7 μm or more in a direction perpendicular to the width is formed within 10 places within 1 mm. A recording layer containing an infrared absorbing agent, a water-insoluble and aqueous alkali-soluble polymer compound, and having improved solubility in an alkali developing solution by infrared laser exposure. A lithographic printing plate precursor characterized by being provided.