JPH09234969A - Manufacture of lithographic printing plate support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the surface roughening method of an aluminum plate for manufacturing a lithographic printing plate, in which fill-in and scumming are hard to develop and which is excellent in plate wear by a method wherein surface roughening is carried out by means of composite surface roughening of mechanical surface roughening and electrochemical surface roughening and then a photosensitive layer is provided on the roughened surface. SOLUTION: This support is constituted under the condition that the center line mean roughness Ra of an aluminum supporting plate after being electrochemically roughened and etched is 0.9-1.5 times as much as the center line mean roughness Ra of the aluminum supporting plate after being mechanically roughened and etched, the area average pit diameter after electrochemically roughened and etched is 0.3-10μm, the pits having the diameter of 0.3-6μm occupies 80% or more of the total pits and its un-etching percentage is below 60%. Preferably, the center line mean roughness Ra of the aluminum plate after being electrochemically roughened and etched is set within the range of 0.3-1.0μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lithographic printing plate support, and more particularly, to a surface roughening treatment which combines mechanical surface roughening and electrochemical surface roughening of an aluminum plate. The present invention relates to a method for producing a support for a lithographic printing plate which is resistant to stains, is less likely to be entangled, and has excellent printing durability.

[0002]

2. Description of the Related Art The lithographic printing method is a printing method utilizing the fact that water and oil are essentially immiscible. A non-image area that repels ink and an image area that repels water and receives oil-based ink are formed. Aluminum support used for the lithographic printing plate, the surface is used so as to bear the non-image portion, hydrophilicity, excellent water retention,
Further, various contradictory performances such as excellent adhesion to the photosensitive layer provided thereon are required. When the support has a low hydrophilicity, ink adheres to the non-image area during printing, causing so-called background stain. When the water retention property of the support is low, entanglement (stain on the non-image area in the halftone dots) occurs unless the dampening water is increased during printing. Therefore,
If the support has poor hydrophilicity or water retention, the so-called water width becomes narrow. Further, if the adhesion between the support and the photosensitive layer is poor, excellent printing durability cannot be obtained.

In order to obtain an aluminum support having good performance, it is customary to grain the surface of an aluminum plate to give fine irregularities. This graining includes mechanical graining methods such as ball graining, brush graining, wire graining, blast graining, and electrolytic graining for electrolytically etching an aluminum plate in an electrolytic solution containing hydrochloric acid and / or nitric acid. Known are a roughening method and a composite roughening method in which a mechanical roughening method and an electrolytic roughening method are combined. In the roughening of the aluminum plate, in order to improve the hydrophilicity to a desirable degree, it is necessary to make the irregularities of the rough surface shallow to some extent, but this will reduce the water retention capacity of the support and adhere to the photosensitive layer. Also gets worse. On the contrary, if the unevenness of the rough surface is deepened, the water retention property, that is, the water width is widened, and the adhesiveness with the photosensitive layer is improved, but scumming occurs.

As a composite surface roughening method in which the mechanical surface roughening method and the electrolytic surface roughening method are combined, there is disclosed in Japanese Patent Laid-Open No. 55-1.
In JP-A-28494, after mechanically roughening the surface of an aluminum plate, it is electrochemically roughened to form a grain having holes on the surface of the aluminum plate, and the diameter of the holes is determined. The open diameters corresponding to 5% and 95% of the cumulative frequency curve are 3 μm or less and 7 μm or less, respectively, and preferably the center line average roughness Ra of the sand is in the range of 0.6 to 1.0 μm. It describes a technique for obtaining a support for a lithographic printing plate which is less likely to become dirty and is excellent in printing durability by roughening and preferably anodizing at the end. Also,
In JP-A-6-24166, after mechanically roughening the surface of an aluminum plate, it is chemically etched in a range of 0.5 to 30 g / m ² to preferably erase only sharp irregularities. Moreover, the current density at the anode is 10 to 60 A / d.
m ² , the amount of electricity at the anode is 200 to 600 coulombs / dm ²
AC surface roughening is performed in an acidic aqueous solution to form pits over the entire surface of the plate, and then alkaline etching is performed.
Finally, it describes a technique for obtaining a support for a lithographic printing plate that is anodized and is resistant to stains and has excellent printing durability.

In recent years, in the lithographic printing industry, speeding up and automation are rapidly advancing, and in the present situation that skilled workers are insufficient, it is easy to print even for unskilled workers and stable with higher quality than ever. A lithographic printing plate is desired, and therefore, an aluminum support having a particularly wide water width and being resistant to stain is desired as an aluminum support for the lithographic printing plate.
Therefore, an object of the present invention is to provide a lithographic printing plate with higher quality and stability than in the conventional composite surface-roughening technique, and since the water retention is high, the shadow portion does not collapse even if the fountain solution is reduced, Tangles are less likely to occur, stains are less likely to occur, and the adhesion to the photosensitive layer is improved to improve printing durability.

[0006]

The above object of the present invention can be achieved by the following method for producing a lithographic printing plate support of the present invention. That is, (1) the surface of the aluminum plate is mechanically roughened, chemically etched, desmutted, and then electrochemically roughened in an acidic electrolytic solution containing nitric acid or hydrochloric acid to perform chemical etching. In the method for producing a support for a lithographic printing plate, which is subjected to a treatment, a desmutting treatment, and an anodizing treatment, an electrochemical treatment is performed with respect to the center line average roughness Ra after mechanical roughening, chemical etching treatment, and desmutting treatment. The center line average roughness Ra after roughening, chemical etching treatment, desmutting is 0.9 to 1.5 times, and area average pits after electrochemical roughening, chemical etching treatment, desmutting treatment The diameter is 0.3-10 μm,
A method for producing a support for a lithographic printing plate, wherein pits of 0.3 to 6 μm occupy 80% or more of the whole and the unetched rate is less than 60%. Preferably, (2) the electrochemical graining, the chemical etching treatment,
The range of the centerline average roughness Ra after desmutting is 0.3.
To 1.0 μm. The method for producing a lithographic printing plate support as described in (1) above.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an aluminum support for a lithographic printing plate of the present invention will be described in detail below. That is, the inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, (a) mechanically roughen the aluminum plate surface in order, and (b) centerline average roughness Ra (1 ) Is 0.5
To 0.8 μm in the range, (c) 15 A / dm ² current density, 350-600 coulomb / dm ² electricity amount in an acidic aqueous solution for AC or DC electrolytic surface roughening, (d) Center line average roughness Ra of the grain
(2) is in the range of 0.9 to 1.5 times Ra (1), the area average pit diameter is 0.3 to 10 μm, and
It is chemically etched so that pits of 3 to 6 μm occupy 80% or more of the whole, and then desmutted.
At this time, the unetched rate is less than 60%. Then, (f)
Anodizing treatment is performed to form an anodized film.

Preferably, the surface of the aluminum plate is
(a) Mechanically roughened surface, (b) Center line average roughness Ra of grain
(1) is chemically etched so as to be in the range of 0.5 to 0.8 μm, and (c) a current density of 15 A / dm ² ,
AC or DC electrolytic surface roughening in an acidic aqueous solution with an electric quantity of 0 to 600 coulombs / dm ² , and (d) the center line average roughness Ra (2) of the grain is 0.9 to 1 of the Ra (1). .2
The value of Ra (2) is in the range of 0.3 to 1.0
It is a method for producing an aluminum support in which a film is chemically etched to have a thickness of μm, followed by desmutting, and (f) anodizing to form an anodized film.

In the present invention, the electrochemical roughening is carried out electrochemically in an acidic aqueous solution containing nitric acid or hydrochloric acid. The electrochemical surface roughening may be performed using alternating current or direct current. Usually, it is often the case that electrochemical roughening is performed using alternating current.

The aluminum plate used in the present invention is selected from a pure aluminum plate, an alloy plate containing aluminum as a main component and a trace amount of a foreign element, or a plastic film laminated or vapor-deposited with aluminum.
The different elements contained in the aluminum alloy include silicon,
There are iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel and titanium. The content of the foreign element in the alloy is 10% by weight or less. The aluminum suitable for the present invention is pure aluminum, but completely pure aluminum is difficult to produce due to refining technology, and thus may contain slightly different elements. As described above, the aluminum plate applied to the present invention is not one whose composition is specified, and is made of a conventionally publicly known material such as JIS.
A 1050, JIS A 1100, JIS A 3
103, JIS A 3005 and the like can be used as appropriate. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm.

Here, the center line average roughness Ra of the sand is
As shown in JIS B601 1970, a portion of the measurement length L is extracted from the roughness curve in the direction of the center line, and the center line of the extracted portion is taken as the X axis and the vertical direction is taken as the Y axis. When the height curve is represented by Y = f (X), the Ra value given by the following mathematical formula (I) is represented in units of microns.

[0012]

[Equation 1]

In the present invention, the center line average roughness Ra of the grain is measured after mechanical roughening, chemical etching, desmutting, and electrochemical roughening, chemical roughening, chemical etching, and desmutting. Ra measured the former two times
(1), the latter is Ra (2), and Ra (2) / Ra
The ratio of (1) is 0.9 to 1.5 times, preferably 0.95 to
Manage to be 1.2 times.

Further, in the present invention, as one of the conditions for performing the electrochemical surface roughening, as described above, the opening diameter (pit size) of the sand obtained after the chemical etching treatment and the desmut treatment is performed. Diameter) area average pit diameter is 0.3 ~
Pits having a size of 10 μm and having a size of 0.3 to 6 μm occupy 80% or more of the whole, and preferably the area average pit diameter is 1.3
It is 5.0 μm. At this time, the unetched rate is 60
Less than%. Here, the area average open pore diameter (pit diameter) of the sand is 100 to 100 mm by using a scanning microscope for the surface of one piece of the aluminum plate after electrochemical graining, chemical etching, and desmutting. It can be obtained by taking a photograph at a magnification of 5000 times, measuring the aperture diameter and the number thereof in the unit area from this photograph, and averaging the areas.

In the present invention, mechanical surface roughening is carried out by degreasing treatment for removing rolling oil on the surface, if desired, prior to brush graining the aluminum plate, for example, a surfactant, an organic solvent or an alkaline aqueous solution. Degreasing treatment is performed by, for example, Subsequently, brush graining is performed using one type or at least two types of brushes having different bristles, while supplying the polishing slurry liquid to the surface of the aluminum plate. The brush used first in the brush graining is called a first brush, and the brush used finally is called a second brush. At the time of graining, as shown in FIG. 1, roller-shaped brushes 2 and 4 and two supporting rollers 5, 6, 7 and 8, respectively, are arranged with an aluminum web 1 interposed therebetween. Two support rollers 5, 6 and 7, 8
Are arranged such that the shortest distance between their outer surfaces is smaller than the outer diameters of the roller brushes 2 and 4, respectively, and the aluminum web 1 is pressed by the roller brushes 2 and 4, and the two support rollers 5, 6 and It is preferable to polish the surface by transporting the aluminum plate at a constant speed in a state of being pushed between 7 and 8 and supplying the polishing slurry liquid 3 onto the aluminum plate to rotate the roller brush.

The brush used in the present invention has nylon, polypropylene, animal hair, or
A brush material such as a steel wire implanted with a uniform bristle length and a flocked distribution, a brush bristle bundle implanted with a small hole in the base portion, or a channel roller type is preferably used. Among them, nylon is a preferable material, and the preferable hair length after flocking is 10 to 200 mm.
It is. In addition, the planting density when planting on the brush roller is 1
The number is preferably 30 to 1000, and more preferably 50 to 300, per cm ² . The preferred bristle diameter of the brush is 0.24 mm to 0.83 mm, more preferably 0.295 mm to 0.6 mm. The cross-sectional shape of the bristles is preferably circular. If the bristle diameter is smaller than 0.24 mm, the stain performance on the shadow portion is deteriorated, and if it is larger than 0.83 mm, the stain performance on the blanket is deteriorated. Nylon is preferred as the material for the bristles, and nylon 6 and nylon 6
6, nylon 6, etc. are used, but nylon 6,10 is most preferable in terms of tensile strength, wear resistance, dimensional stability due to water absorption, bending strength, heat resistance, recovery and the like.

The number of brushes is preferably 1 or more and 10
The number is less than or equal to this number, and more preferably 1 or more and less than or equal to 6. The brush roller may be a combination of brush rollers having different bristles as described in JP-A-6-135175. Then the rotation of the brush roller is preferably 100 rp
It is arbitrarily selected from m to 500 rpm. A supporting roller having a rubber or metal surface and having a good straightness is used. As shown in FIG. 1, it is preferable that the brush roller is rotated in the forward direction of the aluminum plate conveyance direction. However, if the number of brush rollers is large, some of the brush rollers may be rotated in the reverse direction.

The polishing slurry liquid used in the present invention is made of silica sand, aluminum hydroxide, alumina powder, volcanic ash, carborundum, hard sand, etc., having an average particle size of 5 to 150 μm, in an amount of 5 to 40 wt% and a specific gravity of 1.05. It can be used in the range of 1.3. It is important that the abrasive has corners for roughening, and it is difficult for the abrasive particles having no corners such as glass beads to carry out roughening by a combination of a slurry liquid and a brush. As for the pushing force of the brush, the power consumption of the rotary drive motor is 0.5 to 15k.
w, and further preferably 3 to 10 kw. Particularly preferred abrasives are silica sand and aluminum hydroxide. When an abrasive having rounded corners such as aluminum hydroxide is used, a good printing plate can be obtained even if the etching amount after mechanical surface roughening is lower than that when silica sand is used as the abrasive.

Next, in the present invention, electrification using alternating current
Fig. 2 shows an example of the equipment used for the surface roughening treatment.
explain. As a roughening treatment device using alternating current, carbon
The problem that the counter electrode made of metal, metal, etc., is very susceptible to deterioration
was there. Therefore, the auxiliary pair should be connected to the circuit connected to the main pole.
Circuits for the poles are connected in parallel and the anode current is
A diode for controlling the flow in the main counter electrode of
A diode-like mechanism is added to the circuit for the auxiliary counter electrode.
The provided electrolytic treatment apparatus is preferably used. The present invention
As an example of an apparatus used for electrochemical roughening treatment using a flow
For example, as shown in FIG.
The web 11 is supported by the circumference of the drum roller 12 so as to face each other.
From the electrolyte supply port 15 between the main counter electrodes 13a and 13b
Electrolysis solution 14 containing metal ions is replenished and the electrolyte is discharged
By discharging from the mouth 22, the main counter electrode 13a, 1
An alternating current is supplied to the 3b from the AC power supply 17 to electrify it.
An electrolytic treatment apparatus for performing a biological treatment, comprising a metal web 11
The counter electrode of the main counter 13a, 13b and the auxiliary counter 18
And formed in the circuit connected to the main counter electrodes 13a and 13b.
The circuit for the auxiliary counter electrode 18 is connected in parallel, and the anode current is
The circuits of the main counter electrodes of
A diode 19 for controlling the flow at the main counter
Electrolytic treatment provided in the circuit for the auxiliary counter electrode 18 to flow current
Device. At this time, the main counter electrodes 13a and 13b are opposed to each other.
Wires with opposite polarities are connected to the power supply 17 on opposite sides.
In addition, the main counter electrodes 13a and 13b each have a large number of
(For example, n = 10 to 14) small electrodes (13a₁, 13
a_Two , 13a_Three... 13a _n) (13b₁, 13
b_Two, 13b_Three... 13b_n) Are insulators 20
It is constructed with the
You are a husband.

The current flowing to the auxiliary anode is controlled by the diode 19 so as to have an arbitrary current value from the power supply, and is shunted. By distributing the current to the auxiliary anode, it is possible to suppress the dissolution of the carbon electrode of the main electrode and control the roughened shape in the electrochemical roughening step. The ratio of the current flowing through the carbon electrode and the current flowing through the auxiliary anode was 0.
It is preferably 95: 0.05 to 0.7: 0.3. The liquid flow may be parallel to the progress of the aluminum web or may be a counter, but the counter causes less uneven processing. The electrolytic treatment solution 14 enters the electrolytic solution supply port 15, passes through the distributor, enters the cavity so as to be uniformly distributed in the entire width direction of the radial drum roller 12, and is ejected from the slit 16 into the electrolytic solution passage 21. It

Next, in the present invention, an example of an apparatus used for electrochemical graining treatment using direct current will be described with reference to the drawings. The roughening treatment apparatus using a DC voltage shown in FIG. 3 is composed of a first electrolytic cell 32 for first performing a cathodic electrolysis treatment of the aluminum web 11 and a second electrolytic cell for secondly performing an electrolytic electrolysis treatment of the aluminum web 11. 33 is provided. In the first electrolytic cell 32, the aluminum web 11
Is supported by the pass roller 31 and the opposing anode 30 is replenished with an electrolytic treatment solution containing metal ions from the electrolytic solution supply port 15 and discharged from the electrolytic solution discharge port to fill the anode 30 with a DC power source 29. It is an electrolytic treatment apparatus that supplies more current to perform an electrochemical treatment. In the second electrolytic tank 33, the aluminum web 11 is supported by the circumference of the drum roller 12 and the opposite cathode 28, and the electrolytic treatment solution is supplied from the electrolytic solution supply port 15 and discharged from the electrolytic solution discharge port. For the cathode 28, the DC power source 2 is supplied from the AC power source 17.
9 is an electrolytic treatment apparatus for supplying an electric current from 9 to perform an electrochemical treatment. At the start of the anode reaction of the aluminum web 11 in the second electrolytic cell 33, a bit shape can be controlled by providing a zone for low current density electrolysis and arbitrarily controlling the current distribution between the aluminum electrodes.

The aluminum web 11 is combined in an acidic electrolyte with at least one pair of anode and cathode, and three or more electrolytic cells having the same and / or different soft start zones at the inlet portion of the metal web. It is best to adjust the power source used for the main electrolysis of each electrolytic cell or each pair of anode and cathode independently, and adjust the average current density for each electrolytic cell or pair of anode and cathode. It is preferable because a different surface shape can be obtained. The current density in the soft start zone may be gradually increased from 0, or may be increased in two or more steps. The soft start zone is provided in the portion of the first electrolytic cell 32 where the aluminum web 11 on the inlet side of the aluminum web 11 undergoes an anodic reaction by controlling the surface condition such as an oxide film on the surface of the aluminum web 11 in the soft start zone. The purpose is to control the generation state of honeycomb pits generated in the subsequent high current density electrolysis zone.

When an aluminum plate after pretreatment in an acid or alkaline aqueous solution is subjected to electrochemical surface roughening using direct current, if the anodic reaction of the aluminum plate is carried out first, the running speed of the aluminum plate will increase. 20m / mi
When electrochemical roughening is performed using direct current at n or more, continuous groove-like pits having a width of about 5 to 10 μm and a length of about 20 μm or more are easily generated. If these groove-shaped pits are generated, the performance as a printing plate will not be satisfied. Therefore, if the aluminum plate after pretreatment in an acid or alkali aqueous solution is started from the cathode reaction treatment, continuous groove-shaped pits will not be generated.

The structure of the electrolytic cell, the electrode structure and the liquid supply method are as follows.
Known materials used for surface treatment of printing plates or aluminum plates for electrolytic capacitors and general surface treatment of metal webs such as steel and stainless steel can be used. One or more liquid supply ports and waste liquid ports may be provided in the middle of the electrolytic cell. As the electrolytic cell, a vertical type, a horizontal type, a radial type, a V type and the like are generally used, but the vertical type is preferable from the viewpoint of space saving and ease of securing a soft start zone. The radial type electrolytic cell is superior in handling stability of the web-shaped aluminum plate. In the case of a vertical electrolytic cell, it is desirable to provide at least one liquid supply port and / or a waste liquid port on both sides in order to suppress vibration due to the liquid flow of the aluminum plate. In the case of the radial type electrolytic cell, a known method is applied to the liquid supply.

The power source used for the main electrolysis of each electrolytic cell may be a single power source for each electrolytic cell, or an independent power source may be provided for each electrolytic cell. An independent and separate power source may be provided (each located in a separate electrolytic cell). When an independent electrode is provided for each electrolysis cell or for each pair of anode and cathode, the current density can be controlled for each electrolysis cell or for each pair of anode and cathode. It is possible to control an arbitrary roughened shape for each of the anode and the cathode. Note that when power is supplied to multiple electrodes with one power source, the load impedance of the aluminum plate changes depending on the thickness and width of the aluminum plate, the composition of the electrolytic solution, the liquid temperature, etc. Be careful because it may change and it may be difficult to manufacture under certain conditions. Regarding the arrangement of the anode and the cathode, the anode may be arranged at the head or the cathode may be arranged at the head in the traveling direction of the aluminum plate. It is preferred to start the process with the cathode first and the anodic reaction of the aluminum plate.

[0026]

【Example】

(Example-1) JIS A 105 having a thickness of 0.24 mm
0 aluminum plate, nylon brush and average particle size about 21
Brush graining was performed using a suspension of μ pumicetone and water. The bristle diameters of the brushes used are 0.35 mm and 0.45 mm. The material of the nylon brush is nylon 6/10. Rotation of brush roller is 300 rpm
And 400 rpm was chosen. As shown in FIG. 1, the brush roller was rotated in the forward direction of the aluminum plate conveyance direction. In Table 1 below, the condition A for mechanical surface roughening is that the nylon brush has a bristle diameter of 0.3
5 mm, the bristle diameter of the second brush is 0.40 mm, the rotation of the brush is 300 rpm, and the condition B is that the bristle diameter of the nylon brush is 0.45 mm and the bristle diameter of the second brush is 0. The rotation of the brush was 50 mm and the rotation of the brush was 400 rpm. After brush graining, followed by thorough washing with water, then dipping in 26% by weight sodium hydroxide at 60 ° C for 35 seconds (condition A) and 40 seconds (condition B) for etching, and further washing with running water followed by 30% sulfuric acid. It was neutralized and washed with water. These are shown in Table 1.

[0027]

[Table 1]

The subsequent electrochemical surface roughening conditions are as follows: Mechanical roughening condition A: (A-1) condition: 1.5% by weight of nitric acid aqueous solution at 40 ° C. AC electrolytic surface-roughening treatment was carried out by using the apparatus used for the electrochemical surface-roughening treatment with an electric quantity of 350 C / dm ² at the time of anode. (A-2) Conditions: 1.5% by weight of nitric acid aqueous solution at 40 ° C., and direct current electrolytic surface roughening treatment at an electric quantity of 450 C / dm ² by the apparatus used for the electrochemical roughening treatment using direct current. I went. (A-3) Conditions: 1.5% by weight, an aqueous solution of nitric acid at 40 ° C., and an AC electrolytic surface roughening at an anode electricity of 600 C / dm ² by the apparatus used for the electrochemical surface roughening treatment using the alternating current. The chemical treatment was performed. In addition, following the condition B for mechanical surface roughening, (B) condition: 1.5 wt% nitric acid aqueous solution at 40 ° C. is used, and an anode is formed by an apparatus used for the electrochemical surface roughening treatment using the alternating current. An AC electrolytic surface roughening treatment was performed at an electric quantity of 600 C / dm ² . Further, after the electrolytic surface-roughening treatment, it is washed with water, subsequently immersed in 26 wt% sodium hydroxide at 40 ° C. for 18 seconds for etching, further washed with running water, desmutted with 30% sulfuric acid, and then washed with water. Two
1. In a 0% aqueous solution of sulfuric acid at a current density of 2 A / dm ² .
A substrate was prepared by anodizing with direct current so that the weight of the oxide film was 6 g / dm ² .

An undercoat liquid having the following composition was applied to the surface of the substrate thus treated and dried at 80 ° C. for 30 seconds. The coating amount after drying was 30 mg / m ² . (Undercoating method) Aminoethylphosphonic acid 0.10 g Phenylphosphonic acid 0.15 g β-alanine 0.10 g Methanol 40 g Pure water 60 g A substrate was prepared in this manner.

Next, the following photosensitive solution was applied onto this substrate, and 1
A positive photosensitive lithographic printing plate was obtained by drying at 10 ° C. for 1 minute. The coating amount after drying was 1.7 g / m ² . (Photosensitive Solution) Esterified product of 1,2-diazonaphthoquinone-5-sulfonyl chloride and pyrogallol-acetone resin (described in US Pat. No. 3,635,709, Example 1). 45 g Cresol-formaldehyde nopolak resin (meta-para ratio; 6 to 4, weight average molecular weight 3,000, number average molecular weight 1,100, containing 0.7% of unreacted cresol) 1.1 g m-cresol -Formaldehyde nopolak resin (weight average molecular weight 1,700, number average molecular weight 600, containing 1% of unreacted cresol) 0.3 g poly (N- (p-aminosulfonylphenyl) acrylamide-connorbutyl acrylate-cordile Glycol glycol monomethyl ether methacrylate) Japanese Patent Application No. 3-311241 The molar ratio of each monomer is 40:40:20, the weight average molecular weight is 40,000, and the number average molecular weight is 20,000. 0.2 g p-Normal octylphenol-formaldehyde resin (US Pat. No. 123,279) 0.02 g Naphthoquinone-1,2-diazide-4-sulfonic acid chloride 0.01 g Tetrahydrophthalic anhydride 0.1 g Benzoic acid 0.02 g 4- (p- N, N-bis (ethoxycarbonylmethyl) aminophenyl) -2,6-bis (trichloromethyl) -S-triazine 0.01 g 4- (p-N- (p-hydroxybenzoyl) aminophenyl) -2,6 -Bis (trichloromethyl) -S-triazine 0.02 g 2-trichloromethyl-5- (4-hydroxystyril) ) -1,3,4-Oxadiazole 0.01 g Victoria Pureable-BOH counter anion is dye 1-naphthalene sulfonic acid 0.02 g MODIVER-F-200 (Nippon Yushi Co., Ltd. fluorine-based surfactant) Agent, 30 wt% methyl ethyl ketone and methyl isobutyl ketone mixed solvent solution) 0.06 g Megafac F177 (fluorine surfactant manufactured by Dainippon Ink and Chemicals, Inc., 20 wt% methyl isobutyl ketone solution) 0.02 g Methyl ethyl ketone 15 g 1-methoxy-2 propanol 10 g

On the photosensitive layer thus coated, according to the method described in Example 1 of JP-B-61-28986, (methyl methacrylate / ethyl acrylate / sodium acrylate = 68/20 / A mat layer was provided by electrostatically spraying the aqueous copolymer solution of 12).

The photosensitive lithographic printing plate thus prepared was passed through a transparent positive film in a vacuum baking frame and passed through a transparent positive film.
m from a distance of 3m by a metal halide lamp of 3kw
After exposure for 0 seconds, SiO ₂ / N was used as a developing solution.
5.26 of sodium silicate in which the molar ratio of a ₂ O is 1.74.
% Aqueous solution (pH = 12.7) was passed through an automatic developing stablon 900D manufactured by Fuji Photo Film Co., Ltd., which was charged with FR-3 (1: 7) manufactured by Fuji Photo Film Co., Ltd. as a rinse solution. After leaving this lithographic printing plate for 1 day, the printing was evaluated. The printing machine is Harris Aurelia A-125, and the dampening water is EU-3 (1:10 made by Fuji Photo Film Co., Ltd.).
0) and the ink used was Mark Five New Ink manufactured by Toyo Ink Co., Ltd.

On the printing machine, the dampening water was squeezed to visually observe how the ink in the non-image area was smeared, and the stain resistance (good) or bad (poor) was evaluated. When the dampening water was squeezed, it was judged whether 2% of the halftone dots were open or not, and the goodness (◯) or the difficulty (x) of the entanglement difficulty was evaluated. In addition, when 100,000 sheets were printed, good prints were evaluated as good (◯), and when the number of good prints did not reach 100,000, it was evaluated as poor (Δ). Table 2 summarizes these results.

[0034]

[Table 2]

As shown in Table 2, (A-1) of the present invention,
The lithographic printing plate using the support treated under the conditions (A-2) and B is less likely to cause scumming than the support treated under the condition (A-3), is less likely to cause entanglement, and has excellent printing durability. And showed excellent performance.

[0036]

The printing plate prepared from the PS plate using the aluminum support surface-roughened by the composite surface-roughening method combining the mechanical surface-roughening method and the electrolytic surface-roughening method of the present invention is printed. Since a background stain and entanglement are unlikely to occur on the machine, it is possible to provide a printing plate that is easy to print even for an unskilled person and has excellent printing durability.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of a brush grain used for mechanical roughening of the present invention.

FIG. 2 is a side view of an example of an apparatus used for the electrochemical graining treatment using alternating current of the present invention.

FIG. 3 is a side view of an example of an apparatus used in the electrochemical graining treatment using direct current of the present invention.

[Explanation of symbols]

1 aluminum web 2 brush roller 3 abrasive slurry liquid 4 brush roller 5, 6, 7, 8 supporting roller 11 aluminum web 12 radial drum roller 13a main electrode 13b main electrode 13a _1, 13a _2, 13a _n small electrodes 13b _1, 13b _2, 13b _n small electrodes 14 electrolytically treated liquid 15 electrolytic solution supply port 16 slit 17 AC power supply 18 auxiliary anode 19 diode 20 insulator 21 electrolyte passage 22 drain port 28 cathode 29 DC power supply 30 anode 31 pass roller 32 first electrolysis Bath 33 Second electrolysis bath

Claims (2)

[Claims] 1. A surface of an aluminum plate is mechanically roughened,
For lithographic printing plates that undergoes chemical etching, desmutting, electrochemical roughening in an acidic electrolyte containing nitric acid or hydrochloric acid, and then chemical etching, desmutting, and anodizing. In the method for manufacturing a support, the center line average roughness Ra after mechanical roughening, chemical etching treatment, and desmut treatment is compared with the center line average roughness after electrochemical roughening, chemical etching treatment, and desmut treatment. The roughness Ra becomes 0.9 to 1.5 times, and the area average pit diameter after electrochemical roughening, chemical etching treatment and desmut treatment is 0.3 to 10 μm,
A method for producing a support for a lithographic printing plate, wherein pits of 0.3 to 6 μm occupy 80% or more of the whole and the unetched rate is less than 60%. 2. The center line average roughness Ra after the electrochemical graining, chemical etching, and desmutting is in the range of 0.3 to 1.0 μm.
The method for producing the support for a lithographic printing plate as described in.