JP2012214878A - Method for producing lithographic printing plate original plate and method for roughening surface of aluminum support body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a lithographic printing plate original plate and a method for roughening a surface of an aluminum support body, in which pits whose average pit diameter is small and the size is uniform are dispersedly-formed on the surface of the aluminum support body in high density.SOLUTION: The method for producing the lithographic printing plate original plate includes an electrolytic surface-roughening treatment step of the aluminum support body. In the electrolytic surface-roughening treatment step, an electrolysis treatment is performed in an acidic solution having a dissolved oxygen concentration of 6.0 mg/l or less.

Description

  The present invention relates to a method for producing a lithographic printing plate precursor and a method for roughening the surface of an aluminum support, and in particular, uniform pit diameters formed when electrolytically roughening an aluminum support used in a lithographic printing plate. The present invention relates to a method for producing a lithographic printing plate precursor and a method for roughening the surface of an aluminum support.

  Conventionally, a photosensitive composition for coloring, dyeing, painting, or lithographic printing plate is provided on pure aluminum or an alloy thereof (hereinafter sometimes referred to as “aluminum”) and anodized aluminum. At this time, as a method for increasing the adhesion to the aluminum support, it is common practice to roughen the surface of the aluminum support.

  The roughening of the surface of the aluminum support is performed by subjecting the aluminum support to electrolytic treatment, and is called electrolytic roughening treatment.

  The electrolytic surface roughening treatment is performed by applying an alternating waveform current such as a sine wave current, a rectangular wave current, or a trapezoidal wave current, or a direct current to an aluminum support in an acidic electrolytic solution.

  The acidic electrolytic solution used for the electrolytic surface roughening treatment is usually nitric acid, sulfuric acid, phosphoric acid, or a mixture of these at a certain ratio.

  In the electrolytic surface roughening treatment by alternating current, pits are generated by the anode reaction, but at the same time, an oxide film is also generated, so that the surface resistance increases and the dispersibility of the pits decreases. When the dispersibility of the pits is lowered, pits having non-uniform sizes are likely to occur. For this reason, the surface area of the aluminum support is not so large, which causes poor adhesion to the upper layer.

  Electrolytic surface roughening by direct current produces an anodized film on the aluminum support, but the concentration of oxygen dissolved in the acidic electrolyte (hereinafter referred to as dissolved oxygen) is not constant. Variation occurs.

  As a means for dispersing pits, there is, for example, Patent Document 1. In Patent Document 1, a method of performing a roughening treatment after providing an organic film or an inorganic film having electrical resistance is considered good.

Japanese Patent No. 2614744

  However, in the above-mentioned Patent Document 1, it is difficult to control the film thickness of the organic film or the inorganic film, and the electrolyte solution is contaminated.

  The present invention has been made in view of such circumstances, and when the aluminum support is roughened by AC electrolysis in an acidic solution, the formation of an oxide film is suppressed, the pits are dispersed, and the pits are formed. It aims at providing the method of raising adhesiveness with an upper layer by making uniform. Another object of the present invention is to provide a method for producing a anodic oxide film having a certain thickness and properties during surface roughening by an anode reaction of direct current electrolysis to suppress variation in quality between products.

  The above problems can be solved by the following invention. That is, the method for producing a lithographic printing plate according to the present invention is a method for producing a lithographic printing plate having an electrolytic surface roughening treatment step for performing an electrolytic surface roughening treatment on an aluminum support, wherein the electrolytic surface roughening treatment step comprises: The main feature is that the electrolytic treatment is performed in an acidic solution having a dissolved oxygen concentration of 6.0 mg / l or less.

  Further, the roughening method of the surface of the aluminum support of the present invention is characterized mainly by electrolytic treatment of the aluminum support in an acidic solution having a dissolved oxygen concentration of 6.0 mg / l or less.

  This suppresses the formation of an oxide film in the anode reaction of AC electrolytic treatment, reduces the surface resistance, and applies a uniform current, so that pits with a small average pit diameter and a uniform size can be formed with high density. Can do. Pit evaluation was judged by analyzing SEM photographs. In addition, the thickness and properties of the anodized film in the anodic reaction of direct current electrolytic treatment are less affected by dissolved oxygen and are determined only by oxygen ions due to dissociation of water, so that the quality can be made constant.

  In the present invention, the dissolved oxygen concentration in the acidic solution is 6 mg / l or less, preferably 3 mg / l or less, more preferably 1 mg / l or less. A dissolved oxygen meter (manufactured by Central Science Co., Ltd.) was used for concentration measurement.

  The method for removing dissolved oxygen is any one of membrane degassing, nitrogen purging, and decompression. Either method is a method in which a solution having a dissolved oxygen concentration below a certain level is circulated by connecting to a drain pipe portion between the electrolytic bath and the electrolyte tank.

  Depressurization is a method of reducing the dissolved oxygen concentration in the liquid by exposing the acidic electrolytic solution to a reduced pressure atmosphere.

  Nitrogen purge is a method of reducing the dissolved oxygen concentration by replacing the dissolved oxygen in the liquid by passing nitrogen gas through the acidic electrolytic solution.

  Membrane degassing can be performed by using a deoxygenating resin in which reducing copper is held in a weakly basic anion exchange resin, or by using a degassing membrane having the property of allowing gas such as oxygen to pass but not allowing liquid to permeate. This is a method using an attached membrane deaerator.

  According to the present invention, pits having a small average pit diameter and a uniform size can be formed at a high density in a roughening treatment using electrolysis.

It is sectional drawing which shows an example of the electrolytic surface-roughening processing apparatus provided with the radial type | mold AC electrolytic cell in embodiment of this invention. It is explanatory drawing which shows an example of the apparatus system used for the electrolytic surface roughening method which concerns on this invention. It is a SEM photograph of the aluminum support body surface after a roughening process. It is a SEM photograph of the aluminum support body surface after a roughening process.

  Hereinafter, preferred embodiments of the present invention will be described.

[Electrolytic treatment method]
Examples of the acidic solution used in the present invention include a nitric acid solution, a hydrochloric acid solution, a phosphoric acid solution, and a mixed solution thereof, and a nitric acid solution is preferable. The concentration of the nitric acid solution is preferably 1 to 20 g / l, and more preferably 5 to 15 g / l. The liquid temperature during the electrolytic treatment is preferably 20 to 60 ° C, more preferably 30 to 50 ° C. AC electrolytic current density is preferably ^{10~60A / dm 2, 25~55A / dm} 2 is more preferable. The total quantity of electricity is preferably ^{10~400C / dm 2, 60~300C / dm} 2 is more preferable. The distance between the aluminum and the carbon electrode is preferably 5 to 50 mm, more preferably 10 to 20.

[Preparation of lithographic printing plate support and lithographic printing plate precursor]
In the present embodiment, an example in which the present invention is applied to an AC surface roughening treatment using a nitric acid solution in the manufacturing process of an aluminum support for a lithographic printing plate will be described below.

  FIG. 1: shows the cross-sectional schematic diagram of an example of the electrolytic surface-roughening processing apparatus provided with the radial type | mold alternating current electrolysis tank suitably used for this invention.

  As shown in FIG. 1, an electrolytic surface-roughening treatment apparatus 10 includes an electrolytic cell main body 12 in which an electrolytic cell 12A in which an acidic electrolytic solution is stored is provided, and an axis extending in the horizontal direction inside the electrolytic cell 12A. And a feed roller 14 that feeds the aluminum web W, which is a thin plate continuous in a strip shape, in the direction of arrow a, that is, from the right to the left in FIG.

  The inner wall surface of the electrolytic cell 12A is formed in a substantially cylindrical shape so as to surround the feed roller 14, and semicylindrical electrodes 16A and 16B are provided on the inner wall surface of the electrolytic cell 12A with the feed roller 14 interposed therebetween. Yes. The electrodes 16A and 16B are each divided into a plurality of small electrodes 18A and 18B along the circumferential direction, and insulating layers 20A and 20B are interposed between the small electrodes 18A and 18B, respectively. The small electrodes 18A and 18B can be formed using, for example, graphite or metal, and the insulating layers 20A and 20B can be formed using, for example, a vinyl chloride resin. The thickness of the insulating layers 20A and 20B is preferably 1 to 10 mm. Although omitted in FIG. 1, in both the electrodes 16A and 16B, the small electrodes 18A and 18B are connected to the power source AC, respectively. The small electrodes 18A and 18B and the insulating layers 20A and 20B are all held by an insulating electrode holder 20C to form the electrodes 16A and 16B.

  The power supply AC has a function of supplying an alternating waveform current to the electrodes 16A and 16B. The power source AC is a sine wave generating circuit that generates a sine wave by adjusting the current / voltage of commercial alternating current using an induction voltage regulator and a transformer, and a trapezoidal wave from direct current obtained by means such as rectifying the commercial alternating current. Examples include a thyristor circuit that generates a current or a rectangular wave current.

  An opening 12B through which an aluminum web W, which is an example of a metal plate of the present embodiment and is a continuous strip-like aluminum plate, is introduced and led out at the top of the electrolytic cell 12A. ing. In the vicinity of the downstream end of the electrode 16B in the opening 12B, an acidic electrolyte replenishment flow path 22 for replenishing the electrolytic bath 12A with the acidic electrolyte is provided. As such an acidic electrolytic solution, a nitric acid solution, a hydrochloric acid solution, or the like can be used.

  In the vicinity of the opening 12B above the electrolytic cell 12A, a group of upstream guide rollers 24A that guide the aluminum web W into the electrolytic cell 12A and the aluminum web W that has been subjected to electrolytic surface roughening in the electrolytic cell 12A are electrolyzed. A downstream guide roller 24B for guiding outside the tank 12A is provided.

  An overflow tank 12C is provided on the upstream side of the electrolytic cell 12A in the electrolytic cell main body 12. The overflow tank 12C temporarily stores the acidic electrolyte overflowed from the electrolytic tank 12A and has a function of keeping the liquid level of the electrolytic tank 12A constant.

  In the electrolyte near the inlet for guiding the aluminum web W into the electrolytic cell 12A, a direct current portion for applying a negative DC voltage to the aluminum web W at a position of 5 to 15 mm with respect to the surface of the aluminum web W 26 is provided. The direct current unit 26 has a function of constantly applying a negative direct current voltage to the aluminum web W and flowing a direct current through the aluminum web W at the entrance inside the electrolytic cell 12A.

  An auxiliary electrolytic cell 28 is provided downstream of the electrolytic cell 12 </ b> A in the electrolytic cell main body 12. The auxiliary electrolytic cell 28 is shallower than the electrolytic cell 12A, and the bottom surface 28A is formed in a planar shape. A plurality of columnar auxiliary electrodes 29 are provided on the bottom surface 28A.

  The auxiliary electrode 29 is preferably formed of a highly corrosion-resistant metal such as platinum, ferrite, or the like, and may be plate-shaped.

  The auxiliary electrode 29 is connected in parallel to the electrode 16A on the side to which the electrode 16A in the AC power source AC is connected, and in the middle, the thyristor Th1 is connected to the electrode 16A in the AC power source AC at the time of firing. They are connected so that current flows in the direction from the side toward the auxiliary electrode 29.

  Further, the side of the AC power supply AC to which the electrode 16B is connected is also connected to the auxiliary electrode 29 via the thyristor Th2. The thyristor Th2 is connected so that a current flows in a direction from the side connected to the electrode 16B in the AC power supply AC to the auxiliary electrode 29 at the time of ignition.

  An anode current flows through the auxiliary electrode 29 when any of the thyristors Th1 and Th2 is ignited. Therefore, by controlling the phase of the thyristors Th1 and Th2, the current value of the anode current flowing through the auxiliary electrode 29 can be controlled, and the ratio Qc between the amount of electricity Qc flowing when the aluminum web W is the cathode and the amount of electricity Qa flowing when the aluminum web W is the anode. / Qa can also be controlled.

  The auxiliary electrode 29 and the direct current unit 26 are connected via a direct current power source.

  The AC frequency is not particularly limited, but is preferably 40 to 120 Hz, more preferably 40 to 80 Hz, and still more preferably 50 to 60 Hz.

  The ratio Qc / Qa of the amount of electricity Qa flowing during the anode reaction and the amount of electricity Qc flowing during the cathode reaction is preferably 0.9 to 1 with respect to the aluminum web W. More preferred is 99. Thereby, uniform honeycomb pits can be formed on the surface of the aluminum web W.

  The duty of the alternating current is not particularly limited, but is preferably 0.33 to 0.66 from the viewpoint of uniformly roughening the surface of the aluminum web W and manufacturing the power supply device. It is more preferably 4 to 0.6, and most preferably 0.5. In this embodiment, “duty” refers to ta / T, where T is the period of alternating current and ta is the time during which the aluminum alloy plate undergoes an anodic reaction (anode reaction time).

  The time TP until the current value in alternating current reaches a positive or negative peak from zero is preferably 0.5 to 6 msec, more preferably 0.6 to 5 msec in the case of a trapezoidal wave current. preferable. Thereby, a more uniform crater-like recess (pit) can be formed on the surface of the aluminum web W.

The amount of electricity from the start to the end of the electrolytic surface-roughening treatment is preferably 10 to 1000 C / dm ² , and preferably 10 to 800 C / dm ² in terms of the total when the aluminum web W is the anode. More preferably, it is 40-500 C / dm < ² >.

Current Iap at the peak on the anode cycle side in an alternating current, and the current Icp at the peak on the cathode cycle side is preferably from 10 to 100 A / dm ² respectively, more preferably from 20~80A / dm ^2, even more preferably a 30~60A / dm ^2. Icp / Iap is preferably 0.9 to 1.5, more preferably 0.9 to 1.0.

  In the electrolytic surface roughening treatment, in one or two or more electrolytic cells, when the rest period during which alternating current does not flow in the aluminum web W is provided once or more, and the length of the rest period is 0.001 to 0.6 seconds, The honeycomb pits are preferable because they are uniformly formed on the entire surface of the aluminum web W.

  Hereinafter, as an example to which the present invention is applied, a method for producing a lithographic printing plate precursor will be described. Here, the lithographic printing plate precursor is the one before producing a lithographic printing plate, and a lithographic printing plate is produced by exposing and developing the image.

<Aluminum web (rolled aluminum)>
The aluminum plate used as the aluminum web W in the present embodiment is a metal mainly composed of dimensionally stable aluminum. As described above, the aluminum plate also includes an aluminum alloy plate. Hereinafter, these are collectively referred to as an aluminum plate.

  As the aluminum plate, a plastic film or paper on which an aluminum alloy is laminated or vapor-deposited can also be used. Furthermore, a composite sheet in which an aluminum sheet is bonded to a polyethylene terephthalate film as described in Japanese Patent Publication No. 48-18327 can also be used. The aluminum plate can contain elements such as Bi and Ni and inevitable impurities.

  As the aluminum plate, conventionally known materials such as JIS A1050, JIS A1100, JIS A3003, JIS A3004, JIS A3005, and internationally registered alloy 3103A can be appropriately used.

  Further, the aluminum plate may be produced by either a continuous casting method or a DC casting method, and an aluminum plate in which DC casting method intermediate annealing or soaking treatment is omitted can also be used. In the final rolling, it is possible to use an aluminum plate provided with unevenness by lamination rolling or transfer. The aluminum plate may be an aluminum web, which is a continuous strip-shaped sheet material or plate material, and is a sheet-like sheet cut to a size corresponding to a planographic printing plate precursor shipped as a product. Also good.

  Moreover, the thickness of an aluminum plate is about 0.05-1 mm normally, and it is preferable that it is 0.1 mm-0.5 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 desire.

  In the method for producing a lithographic printing plate precursor according to this embodiment, the aluminum plate is subjected to various surface treatments including an electrolytic surface roughening treatment in an acidic aqueous solution to obtain a lithographic printing plate precursor. Further, various types of processing may be included.

  Before the electrolytic surface roughening treatment, an alkali etching treatment or a desmut treatment is preferably performed, and an alkali etching treatment and a desmut treatment are also preferably performed in this order. Moreover, it is preferable to perform an alkali etching process or a desmut process after an electrolytic surface roughening process, and it is also preferable to perform an alkali etching process and a desmut process in this order. Further, the alkali etching treatment after the electrolytic surface roughening treatment can be omitted. In the present invention, it is also preferable to perform a mechanical surface roughening treatment before these treatments. Moreover, you may perform an electrolytic surface roughening process twice or more. Moreover, it is also preferable to perform an anodizing process, a sealing process, a hydrophilization process, etc. after these.

  Hereinafter, mechanical roughening treatment, first alkali etching treatment, first desmutting treatment, electrolytic surface roughening treatment, second alkali etching treatment, second desmutting treatment, anodizing treatment, sealing treatment, and hydrophilic treatment, respectively. Will be described in detail. In the present embodiment, the process performed before the electrolytic surface roughening process is called with an ordinal number “first”, and the process performed after the electrolytic surface roughening process is called with an ordinal number “second”. There is a case.

<Mechanical roughening>
The mechanical surface roughening treatment is preferably performed before the electrolytic surface roughening treatment. In general, the mechanical surface roughening treatment is a roller brush in which a large number of brush hairs such as synthetic resin hair made of synthetic resin such as nylon (registered trademark), propylene, and vinyl chloride resin are implanted on the surface of a cylindrical body. Is used by rubbing one or both of the surfaces of the aluminum web while spraying a slurry liquid containing an abrasive on a rotating roller brush. Instead of the roller brush and the slurry liquid, a polishing roller which is a roller having a polishing layer on the surface can be used. The length of the bristle in the roller brush can be appropriately determined according to the outer diameter of the roller brush and the diameter of the body, but is generally 10 to 100 mm.

  A well-known thing can be used for an abrasive | polishing agent. For example, abrasives such as pumiston, silica sand, aluminum hydroxide, alumina powder, volcanic ash, carborundum, and gold sand can be used, or a mixture thereof. Among them, pumiston and silica sand are preferable, but silica sand is particularly preferable in terms of excellent roughening efficiency because it is harder and less likely to break than pamiston. The average particle diameter of the abrasive is preferably 3 to 50 μm, and more preferably 6 to 45 μm in terms of excellent surface roughening efficiency and a narrow graining pitch. When using pumiston as an abrasive, the average particle size is particularly preferably 40 to 45 μm, and when using silica sand as the abrasive, the average particle size is particularly preferably 20 to 25 μm. For example, the abrasive is suspended in water and used as a polishing slurry. In addition to the abrasive, the polishing slurry liquid can contain a thickener, a dispersant (for example, a surfactant), an antiseptic, and the like. The average particle diameter is the particle diameter at which the cumulative ratio is 50% when the cumulative distribution of the ratio of the abrasive particles of each particle diameter is taken with respect to the volume of the total abrasive contained in the polishing slurry liquid. Say.

  Further, in the mechanical surface roughening treatment, first, prior to performing brush graining, if necessary, a degreasing treatment for removing rolling oil on the surface of the aluminum web, for example, a surfactant, an organic solvent, an alkaline aqueous solution. The degreasing process by etc. may be performed.

<First alkali etching treatment>
In the first alkaline etching treatment, etching is performed by bringing the aluminum web into contact with an alkaline solution. The first alkali etching treatment is performed for the purpose of removing rolling oil, dirt, and natural oxide film on the surface of the aluminum web (rolled aluminum) when mechanical roughening treatment is not performed. When the roughening treatment is performed, it is performed for the purpose of obtaining a surface having smooth undulations by dissolving the uneven edge portions generated by the mechanical roughening treatment. As a method of bringing the aluminum web into contact with the alkaline solution, for example, a method of passing the aluminum web through a bath containing the alkaline solution,
Examples include a method of immersing an aluminum web in a tank containing an alkaline solution, a method of spraying an alkaline solution onto the surface of the aluminum web, and the like.

The etching amount is preferably ¹ to 15 g / m ² for the surface subjected to the electrolytic surface roughening treatment in the next step, and 0.1 to 5 g / m for the surface not subjected to the electrolytic surface roughening treatment. ² (about 10 to 40% of the surface to be subjected to electrolytic surface roughening treatment) is preferable.

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

Although the density | concentration of an alkaline solution can be determined according to the etching amount, it is preferable that it is 1-50 mass%, and it is more preferable that it is 10-35 mass%. When aluminum ions are dissolved in the alkaline solution, the concentration of aluminum ions is preferably 0.01 to 10% by mass, and more preferably 3 to 8% by mass. The temperature of the alkaline solution is preferably 20 to 90 ° C. The treatment time is preferably 1 to 120 seconds. The amount of the etching treatment is preferably for 1 to 15 g / m ² dissolution, it is more preferable to 3~12g / m ² dissolution. The first alkali etching treatment can be performed using an etching tank usually used for the etching treatment of the aluminum web. As the etching tank, either a batch type or a continuous type can be used. Moreover, when spraying an alkali solution on the surface of an aluminum web and performing a 1st alkali etching process, a spray apparatus can be used.

<First desmut treatment>
In the first desmutting treatment, for example, the aluminum web is brought into contact with an acidic solution (containing 0.01 to 5% by mass of aluminum ions) having a concentration of 0.5 to 30% by mass such as hydrochloric acid, nitric acid, and sulfuric acid. Do. Examples of the method of bringing the aluminum web into contact with the acidic solution include, for example, a method in which the aluminum web is passed through a tank containing the acidic solution, a method in which the aluminum web is immersed in a tank containing the acidic solution, and the acidic solution is made of aluminum. The method of spraying on the surface of a web is mentioned. In the first desmutting treatment, as an acidic solution, an aqueous solution mainly containing nitric acid or an aqueous solution mainly containing hydrochloric acid discharged in an electrolytic surface-roughening treatment described later, or sulfuric acid discharged in an anodic oxidation treatment described later It is preferable to use a waste liquid of an aqueous solution mainly composed of. The liquid temperature of the first desmut treatment is preferably 25 to 90 ° C. Moreover, it is preferable that the processing time of a 1st desmut process is 1-180 second.

<Electrolytic roughening treatment>
The acidic aqueous solution used in the electrolytic surface roughening treatment is not particularly limited, but an aqueous solution mainly containing nitric acid and an aqueous solution mainly containing hydrochloric acid are preferable. The aqueous solution mainly composed of nitric acid preferably has a nitric acid concentration of 3 to 20 g / L, more preferably 5 to 15 g / L, and preferably an aluminum ion concentration of 3 to 15 g / L. 3 to 7 g / L is more preferable. The concentration of aluminum ions in an aqueous solution mainly composed of nitric acid can be adjusted by adding aluminum nitrate to an aqueous nitric acid solution having a nitric acid concentration. The aqueous solution mainly composed of hydrochloric acid preferably has a hydrochloric acid concentration of 3 to 15 g / L, more preferably 5 to 10 g / L, and preferably an aluminum ion concentration of 3 to 15 g / L. 3 to 7 g / L is more preferable. The concentration of aluminum ions in the aqueous solution mainly containing hydrochloric acid can be adjusted by adding aluminum chloride to the aqueous hydrochloric acid solution having the above hydrochloric acid concentration.

<Second alkali etching treatment>
In the second alkali etching treatment, etching is performed by bringing the aluminum web into contact with an alkaline solution. Examples of the alkali type, the method of bringing the aluminum web into contact with the alkaline solution, and the apparatus used therefor are the same as in the case of the first alkaline etching treatment. The etching amount is preferably 0.001 to 5 g / m ² , more preferably 0.01 to 3 g / m ² , more preferably 0.05 to ² g for the surface subjected to the electrolytic surface roughening treatment. further preferably / m ^2.

  Examples of the alkali used in the alkaline solution include the same as in the case of the first alkali etching treatment. The concentration of the alkaline solution can be determined according to the etching amount, but is preferably 0.01 to 80% by mass. The temperature of the alkaline solution is preferably 20 to 90 ° C. The treatment time is preferably 1 to 60 seconds. In the second desmutting process to be described later, when an acidic solution containing 100 g / L or more of sulfuric acid and having a liquid temperature of 60 ° C. or higher is used, the second alkali etching process can be omitted.

<Second desmut treatment>
In the second desmut treatment, for example, the aluminum web is brought into contact with an acidic solution (containing aluminum ions 0.01 to 5% by mass) having a concentration of 0.5 to 30% by mass such as phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid. To do. The method for bringing the aluminum web into contact with the acidic solution may be the same as in the case of the first desmut treatment. In the second desmutting treatment, it is preferable to use a waste solution of a sulfuric acid solution discharged in an anodic oxidation treatment described later as the acidic solution. Further, instead of the waste liquid, a sulfuric acid solution having a sulfuric acid concentration of 100 to 600 g / L, an aluminum ion concentration of 1 to 10 g / L, and a liquid temperature of 60 to 90 ° C. can be used. The liquid temperature of the second desmut treatment is preferably 25 to 90 ° C. Moreover, it is preferable that the processing time of a 2nd desmut process is 1-180 second. Aluminum and aluminum alloy components may be dissolved in the acidic solution used for the second desmut treatment.

<Anodizing treatment>
It is preferable that the aluminum web treated as described above is further subjected to an anodizing treatment. The anodizing treatment can be performed by a conventional method in this field. Specifically, in an electrolytic solution that is an aqueous solution or a non-aqueous solution of sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, amidesulfonic acid, etc. When direct current, pulsating flow or alternating current is passed through the web, an anodized film can be formed on the surface of the aluminum web.

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

When anodizing is performed in an electrolytic solution containing sulfuric acid, direct current may be applied to the aluminum web, or alternating current may be applied. When a direct current is applied to the aluminum web, the current density is preferably 1 to 60 A / dm ^2, and more preferably 5 to 40 A / dm ^2. In the case of continuous anodizing treatment, a low current of 5 to 10 A / dm ² is initially introduced so that the so-called “burn” does not occur due to concentration of current on a part of the aluminum web. It is preferable to increase the current density to 30 to 50 A / dm ² or more as the current is passed at the density and the anodization process proceeds. In the case where the anodizing treatment is continuously performed, it is preferable to use a liquid feeding method in which the aluminum web is fed through an electrolytic solution.

  As an electrode for supplying power to the aluminum web, an electrode formed of lead, iridium oxide, platinum, ferrite, or the like can be used. Among these, an electrode formed mainly from iridium oxide and an electrode in which the surface of the substrate is coated with iridium oxide are preferable. As such a base material, it is preferable to use a so-called valve metal such as titanium, tantalum, niobium, zirconium, etc. Among the valve metals, titanium and niobium are preferable. Since the valve metal has a relatively large electric resistance, the valve metal may be clad on the surface of a core material made of copper to form a base material. When valve metal is clad on the surface of a copper core material, it is difficult to produce a base material with a complicated shape. Therefore, the valve metal is clad on the core material in which the base material is divided into parts. Then, the base material may be assembled by combining the components.

The conditions of the anodizing treatment cannot be determined unconditionally because they vary depending on the electrolytic solution used. In general, the electrolytic solution concentration is 1 to 80% by mass, the liquid temperature is 5 to 70 ° C., and the current density is 1 to 60 A. / Dm ² , voltage 1 to 100 V, and electrolysis time 10 to 300 seconds are appropriate. The anodizing treatment is preferably performed so that the amount of the anodized film becomes ¹ to 5 g / m ² from the viewpoint of printing durability of the lithographic printing plate. Further, it is preferable that the difference in the amount of the anodized film between the center portion of the aluminum web and the vicinity of the edge portion is 1 g / m ² or less.

<Sealing treatment>
It is preferable to perform a sealing treatment in which the aluminum alloy plate on which the anodized film is formed is brought into contact with boiling water, hot water or steam to seal small holes (micropores) formed by anodizing treatment.

<Hydrophilic treatment>
After anodizing treatment or sealing treatment, soaking in an aqueous solution of alkali metal silicate such as sodium silicate, potassium silicate, etc., applying hydrophilic vinyl polymer or hydrophilic compound to form hydrophilic undercoat layer It is preferable to perform a hydrophilization treatment by a forming method or the like. Examples of the hydrophilic vinyl polymer used in this method include polyvinyl sulfonic acid, a sulfonic acid group-containing vinyl polymerizable compound such as p-styrene sulfonic acid having a sulfonic acid group, and an ordinary (meth) acrylic acid alkyl ester. Examples thereof include a copolymer with a vinyl polymerizable compound. Examples of hydrophilic compounds that may be used in this method include, -NH ₂ group, compounds having at least one selected from the group consisting of -COOH group and sulfo group.

[Formation of intermediate layer and photosensitive layer]
<Intermediate layer>
A photosensitive layer can be provided directly on the lithographic printing plate support subjected to the above hydrophilic treatment or the lithographic printing plate support further treated with an acidic aqueous solution after the hydrophilic treatment. An intermediate layer may be provided on the body, and a photosensitive layer may be provided on the intermediate layer.

(Intermediate layer of polymer compound having acid group and onium group)
As the polymer compound used for forming the intermediate layer, a polymer compound having an acid group or having a component having an onium group together with a component having an acid group is more preferably used. As the acid group of the component of the polymer compound, an acid group having an acid dissociation index (pKa) of 7 or less is preferable, more preferably —COOH, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ , —SO ₂ NHSO ₂ — and particularly preferably —COOH. A preferred component having an acid group is a polymerizable compound represented by the following general formula (1) or general formula (2).

In the formula, A represents a divalent linking group. B represents an aromatic group or a substituted aromatic group. D and E each independently represent a divalent linking group. G represents a trivalent linking group. X and X ′ each independently represents an acid group having a pKa of 7 or less, or an alkali metal salt or ammonium salt thereof. R1 represents a hydrogen atom, an alkyl group or a halogen atom. a, b, d and e each independently represents 0 or 1; t is an integer of 1 to 3. More preferably, A represents —COO— or CONH—, B represents a phenylene group or a substituted phenylene group, and the substituent is a hydroxyl group, a halogen atom, or an alkyl group. D and E each independently represent an alkylene group or a divalent linking group having a molecular formula of CnH ₂ nO, CnH ₂ nS or CnH 2n + 1N. G represents a trivalent linking group having a molecular formula of CnH ₂ n-1, CnH ₂ n-1O, CnH ₂ n-1S or CnH ₂ nN. However, n represents the integer of 1-12 here. X and X ′ each independently represent carboxylic acid, sulfonic acid, phosphonic acid, sulfuric acid monoester or phosphoric acid monoester. R1 represents a hydrogen atom or an alkyl group. a, b, d and e each independently represent 0 or 1, but a and b are not 0 at the same time. Among the constituents having an acid group, a compound represented by the general formula (1) is particularly preferable. B represents a phenylene group or a substituted phenylene group, and the substituent is a hydroxyl group or an alkyl group having 1 to 3 carbon atoms. . D and E each independently represent an alkylene group having 1 to 2 carbon atoms or an alkylene group having 1 to 2 carbon atoms linked by an oxygen atom. R1 represents a hydrogen atom or a methyl group. X represents a carboxylic acid group. a is 0 and b is 1.

  Although the specific example of the structural component which has an acid group is shown below, it is not limited to these. Acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, itaconic acid, maleic acid, maleic anhydride and the like are listed, and the following are further listed.

  You may combine the structural component which has the above acid groups 1 type, or 2 or more types.

(Intermediate layer of polymer compound having onium group)
Moreover, what is preferable as an onium group as a constituent component of the polymer compound used for forming the intermediate layer is an onium group composed of a group V or group VI atom in the periodic table, more preferably a nitrogen atom or a phosphorus atom. Alternatively, it is an onium group composed of a sulfur atom, and particularly preferably an onium group composed of a nitrogen atom. The polymer compound is preferably a polymer whose main chain structure is vinyl polymer such as acrylic resin, methacrylic resin or polystyrene, urethane resin, polyester or polyamide. Of these, vinyl polymers such as acrylic resin, methacrylic resin, and polystyrene are more preferable for the main chain structure. A particularly preferable polymer compound is a polymer in which a constituent component having an onium group is a polymerizable compound represented by the following general formula (3), general formula (4), or general formula (5).

In the formula, J represents a divalent linking group. K represents an aromatic group or a substituted aromatic group. M independently represents a divalent linking group. Y1 represents a group V atom in the periodic table, and Y2 represents a group VI atom in the periodic table. Z @-represents a counter anion. R2 represents a hydrogen atom, an alkyl group or a halogen atom. R3, R4, R5 and R7 each independently represents a hydrogen atom or an alkyl group, an aromatic group or an aralkyl group to which a substituent may be bonded, and R6 represents an alkylidine group or a substituted alkylidine, And R4 or R6 and R7 may combine with each other to form a ring. j, k, and m each independently represents 0 or 1. u represents an integer of 1 to 3. More preferably, among the components having an onium group, J represents —COO— or CONH—, K represents a phenylene group or a substituted phenylene group, and the substituent is a hydroxyl group, a halogen atom or an alkyl group. M represents an alkylene group or a divalent linking group having a molecular formula of CnH ₂ nO, CnH ₂ nS, or Cn H 2n + 1N. However, n represents the integer of 1-12 here. Y1 represents a nitrogen atom or a phosphorus atom, and Y2 represents a sulfur atom. Z − represents a halogen ion, PF ₆ −, BF ₄ − or R ₈ SO ₃ −. R2 represents a hydrogen atom or an alkyl group. R3, R4, R5 and R7 each independently represent a hydrogen atom or an optionally substituted alkyl group, aromatic group or aralkyl group to which a substituent may be bonded; 10 alkylidyne groups or substituted alkylidines are represented, and R3 and R4 or R6 and R7 may be bonded to each other to form a ring. j, k, and m each independently represent 0 or 1, but j and k are not 0 at the same time. Particularly preferably among the components having an onium group, K represents a phenylene group or a substituted phenylene group, and the substituent is a hydroxyl group or an alkyl group having 1 to 3 carbon atoms. M represents an alkylene group having 1 to 2 carbon atoms or an alkylene group having 1 to 2 carbon atoms linked by an oxygen atom. Z- represents a chlorine ion or R ₈ SO _3- . R2 represents a hydrogen atom or a methyl group. j is 0 and k is 1.

<Photosensitive layer>
A lithographic printing plate precursor can be obtained by providing a photosensitive layer on the lithographic printing plate support before the intermediate layer is formed or on the lithographic printing plate support on which the intermediate layer is formed.

  Although a photosensitive layer is not specifically limited, For example, the visible light exposure type platemaking layer exposed with normal visible light, The laser exposure type platemaking layer exposed with laser beams, such as an infrared laser beam, are mentioned. Hereinafter, the visible light exposure type plate making layer and the laser exposure type plate making layer will be described.

(1) Visible light exposure type plate making layer The visible light exposure type plate making layer can be formed of a composition containing a photosensitive resin and, if necessary, a colorant. Examples of the photosensitive resin include a positive photosensitive resin that dissolves in the developer when exposed to light, and a negative photosensitive resin that does not dissolve in the developer when exposed to light. Examples of the positive photosensitive resin include a combination of a diazide compound such as a quinone diazide compound or a naphthoquinone diazide compound and a phenol resin such as a phenol novolac resin or a cresol-novolak resin. Examples of the negative photosensitive resin include diazo compounds such as diazo resins (for example, condensation products of aromatic diazonium salts and aldehydes such as formaldehyde), inorganic acid salts of the diazo resins, and organic acid salts of the diazo resins. And combinations with binders such as (meth) acrylate resins, polyamide resins, polyurethane resins, vinyl polymers such as (meth) acrylate resins and polystyrene resins, and vinyl polymerizable compounds such as (meth) acrylate esters and styrene , A combination with a photopolymerization initiator such as a benzoin derivative, a benzophenone derivative, or a thioxanthone derivative.

  As the colorant, in addition to ordinary dyes, an exposure coloring dye that develops color by exposure, an exposure decoloring dye that becomes almost or completely colorless by exposure, and the like can be used. Examples of the exposure coloring dye include a leuco dye. Examples of exposure decolorizing dyes include triphenylmethane dyes, diphenylmethane dyes, oxazine dyes, xanthene dyes, iminonaphthoquinone dyes, azomethine dyes, and anthraquinone dyes.

  The visible light exposure type plate-making layer can be formed, for example, by applying a photosensitive resin solution in which the photosensitive resin and the colorant are blended in a solvent, and then drying. Examples of the solvent used in the photosensitive resin solution include a solvent that can dissolve the photosensitive resin and has a certain degree of volatility at room temperature. Specific examples include alcohol solvents, ketone solvents, ester solvents, ether solvents, glycol ether solvents, amide solvents, and carbonate esters. Examples of the alcohol solvent include ethanol, propanol, and butanol. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, and diethyl ketone. Examples of the ester solvent include ethyl acetate, propyl acetate, methyl formate, and ethyl formate. Examples of the ether solvent include tetrahydrofuran and dioxane. Examples of the glycol ether solvent include ethyl cellosolve, methyl cellosolve, and butyl cellosolve. Examples of the amide solvent include dimethylformamide and dimethylacetamide. Examples of the carbonate ester solvent include ethylene carbonate, propylene carbonate, diethyl carbonate, and dibutyl carbonate.

  The coating method of the photosensitive resin solution is not particularly limited, and conventionally known methods such as a spin coating method, a wire bar coating method, a dip coating method, an air knife coating method, a roll coating method, and a blade coating method can be used. .

(2) Laser exposure type plate making layer Examples of the laser exposure type plate making layer include a negative type laser plate making layer in which a portion irradiated with laser light remains, a positive type laser plate making layer in which a portion irradiated with laser light is removed, and a laser. A main example is a photopolymerization type laser plate making layer that undergoes photopolymerization when irradiated with light.

  The negative type laser plate-making layer comprises: (A) an acid precursor that decomposes with heat or light to generate an acid; (B) an acid crosslinkable compound that crosslinks with an acid generated by decomposition of the acid precursor (A); C) An alkali-soluble resin, (D) an infrared absorber, and (E) a phenolic hydroxyl group-containing compound can be formed using a negative type laser plate-making layer forming solution dissolved or suspended in an appropriate solvent. .

  As an acid precursor (A), the compound which decomposes | disassembles with an ultraviolet light, visible light, or a heat | fever like an iminophosphate compound, for example is mentioned. In addition, compounds generally used as a cationic photopolymerization initiator, a radical photopolymerization initiator, a photochromic agent, and the like can also be used as the acid precursor (A). Examples of the acid crosslinkable compound (B) include an aromatic compound having at least one of an alkoxymethyl group and a hydroxyl group, a compound having an N-hydroxymethyl group, an N-alkoxymethyl group, or an N-acyloxymethyl group, and an epoxy. Compounds. Examples of the alkali-soluble resin (C) include polymers having a hydroxyaryl group in the side chain, such as a novolak resin and poly (hydroxystyrene).

  As an infrared absorber (D), the dye and pigment which absorb the infrared rays with a wavelength of 760-1200 nm are mentioned, for example. Specific examples include black pigments, red pigments, metal powder pigments, phthalocyanine pigments; azo dyes, anthraquinone dyes, phthalocyanine dyes, and cyanine dyes that absorb infrared rays having the above wavelengths. Examples of the phenolic hydroxyl group-containing compound (E) include, for example, the general formula (R1-X) n-Ar- (OH) m (wherein R1 is an alkyl group or alkenyl group having 6 to 32 carbon atoms; Is a single bond, O, S, COO or CONH, Ar is an aromatic hydrocarbon group, an alicyclic hydrocarbon group or a heterocyclic group, and n and m are natural numbers of 1 to 8, respectively. .). Examples of such compounds include alkylphenols such as nonylphenol. In addition to the above components, a plasticizer or the like can also be blended in the negative type laser plate making layer forming liquid.

  The positive type laser plate making layer is a positive type laser plate making layer solution in which (F) an alkali-soluble polymer, (G) an alkali dissolution inhibitor, and (H) an infrared absorber are dissolved or suspended in an appropriate solvent. Can be used. Examples of the alkali-soluble polymer (F) include phenolic polymers having a phenolic hydroxyl group such as phenol resin, cresol resin, novolac resin, pyrogallol resin, poly (hydroxystyrene); and at least some of the monomer units are sulfonamide groups. Examples thereof include sulfonamide group-containing polymers that are polymers having active imide groups; active imide group-containing polymers obtained by homopolymerization or copolymerization of monomers having an active imide group such as N- (p-toluenesulfonyl) (meth) acrylamide group.

  Examples of the alkali dissolution inhibitor (G) include compounds that react with the alkali-soluble polymer (F) by heating or the like to reduce the alkali solubility of the alkali-soluble polymer (F). Specific examples include sulfone compounds, ammonium salts, sulfonium salts, and amide compounds. As a combination of the alkali-soluble polymer (F) and the alkali dissolution inhibitor (G), a combination of a novolak resin as the alkali-soluble polymer (F) and a cyanine dye which is a kind of sulfone compound as the alkali dissolution inhibitor (G). Preferably mentioned. Examples of the infrared absorber (H) include dyes having an absorption region in the infrared region with a wavelength of 750 to 1200 nm, such as squarylium dye, pyrylium dye, carbon black, insoluble azo dye, and anthraquinone dye, and having light / heat conversion ability. , Dyes and pigments.

  The photopolymerization type laser plate making layer can be formed using (I) a photopolymerization type laser plate making layer containing a vinyl polymerizable compound having an ethylenically unsaturated bond at the molecular end. In the photopolymerization type laser plate making layer forming liquid, (J) a photopolymerization initiator, (K) a sensitizer, and the like can be blended as necessary. Examples of the vinyl polymerizable compound (I) include an ethylenically unsaturated carboxylic acid polyvalent ester which is an ester of an ethylenically unsaturated carboxylic acid such as (meth) acrylic acid, itaconic acid and maleic acid and an aliphatic polyhydric alcohol. Examples include esters; ethylenically unsaturated carboxylic acid polyvalent amides such as methylene bis (meth) acrylamide; xylylene (meth) acrylamide composed of the ethylenically unsaturated carboxylic acid and polyvalent amine. Other examples of the vinyl polymerizable compound (I) include aromatic vinyl compounds such as styrene and α-methylstyrene; ethylenically unsaturated carboxylic acid monoesters such as methyl (meth) acrylate and ethyl (meth) acrylate. Can be mentioned. As a photoinitiator (J), the photoinitiator normally used for photopolymerization of a vinyl-type monomer can be used. Examples of the sensitizer (K) include titanocene compounds, triazine compounds, benzophenone compounds, benzimidazole compounds, cyanine dyes, merocyanine dyes, xanthene dyes, and coumarin dyes.

  Solvents used in the negative type laser plate making layer forming liquid, the positive type laser plate making layer forming solution and the photopolymerization type laser plate making layer forming liquid, and the negative type laser plate making layer forming solution, the positive type laser plate making layer forming solution, and For the coating method of the photopolymerization type laser plate making layer forming liquid, the solvents and coating methods mentioned for the photosensitive resin solution can be used. In the case of forming a photopolymerization laser plate making layer, using a silicone compound having a reactive functional group such as a partially decomposed silane compound obtained by partially decomposing a silane compound with water, alcohol or carboxylic acid, It is preferable to treat the roughened surface of the lithographic printing plate support in advance, since the adhesion between the support and the photopolymerization laser plate making layer is improved.

<Matte layer>
The surface of the photosensitive layer provided as described above may be provided with a matte layer in order to reduce the time for evacuation during close contact exposure using a vacuum printing frame and to prevent printing blur. Good. Specifically, a method for providing a mat layer as described in JP-A-50-125805, JP-B-57-6582, and JP-A-61-2986, and JP-B-62-62337. And a method of thermally depositing a solid powder as described above.

<Back coat layer>
In the planographic printing plate precursor obtained as described above, a coating layer (hereinafter referred to as an organic polymer compound) is formed on the back surface (the surface on which the photosensitive layer is not provided) so that the photosensitive layer is not damaged even if it is stacked. (Also referred to as “backcoat layer”) may be provided as necessary. As the main component of the backcoat layer, at least one resin selected from the group consisting of a saturated copolymerized polyester resin, a phenoxy resin, a polyvinyl acetal resin, and a vinylidene chloride copolymer resin having a glass transition point of 20 ° C. or higher is used. Is preferred.

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

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

  The thickness of the backcoat layer may be basically a level that does not damage the photosensitive layer even without interleaf, and is preferably 0.01 to 8 μm. When the thickness is less than 0.01 μm, it is difficult to prevent the photosensitive layer from being scratched when the planographic printing plate precursors are handled in layers. On the other hand, when the thickness exceeds 8 μm, the backcoat layer swells due to chemicals used around the lithographic printing plate during printing, the thickness varies, and the printing pressure may change to deteriorate the printing characteristics.

  Various methods can be used for providing the backcoat layer on the back surface of the lithographic printing plate precursor. For example, a method in which the above components for the back coat layer are dissolved in an appropriate solvent and applied as a solution, or an emulsified dispersion is applied and dried; lithographic printing using a film-shaped material previously formed with an adhesive or heat A method of bonding to a plate precursor; a method of forming a melt film with a melt extruder and bonding to a lithographic printing plate precursor. The most preferable method for securing a suitable thickness is a method in which the components for the backcoat layer are dissolved in an appropriate solvent, applied as a solution, and dried.

  In the production of a lithographic printing plate precursor, either the back coat layer on the back surface or the photosensitive layer on the front surface may be provided on the support first, or both may be provided simultaneously.

  The lithographic printing plate precursor thus obtained is cut into an appropriate size, if necessary, exposed and developed to produce a lithographic printing plate. In the case of a lithographic printing plate precursor provided with a visible light exposure type plate-making layer (photosensitive plate-making layer), the transparent film on which the printed image is formed is overlaid and exposed by irradiating with normal visible light, and then developed. It is possible to make a plate by performing. In the case of a lithographic printing plate precursor provided with a laser exposure type plate making layer, exposure can be performed by directly writing a printed image by irradiating various types of laser light, and then developing can be carried out.

  As mentioned above, although the example which applies this invention to the manufacturing method of the support body for lithographic printing plates was demonstrated, this invention is applicable also to the other technical field provided with the process of carrying out the electrolytic roughening process on the surface of a metal plate. .

[Example]
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.

  This will be described with reference to FIG. FIG. 2 is an explanatory view showing an example of an apparatus system used in the electrolytic surface roughening method according to the present invention. In a container 200 having a size of 100 × 100 × 100 mm, an electrolytic surface roughening treatment was performed by alternating current using a nitric acid solution.

  In the apparatus system shown in FIG. 2, the concentration of the nitric acid solution 210 was set to 10 g / l, the liquid temperature was set to 35 ° C., and nitrogen gas 220 was injected into the nitric acid solution 210 to perform nitrogen purging. The dissolved oxygen concentration in the nitric acid solution 210 was adjusted by nitrogen purge. The dissolved oxygen concentration was measured with a dissolved oxygen meter (manufactured by Central Science Co., Ltd.).

  The aluminum support 230 and the carbon electrode 240 were arranged in the nitric acid solution 210 with their respective planes facing each other, and the aluminum support 230 and the carbon electrode 240 were connected to the AC power source 250, respectively. The distance between the aluminum support 230 and the carbon electrode 240 was 10 mm. The aluminum support 230 used A1050 as an aluminum material.

The aluminum support 230 was subjected to an electrolytic surface roughening treatment while the 1% nitric acid solution 210 was stationary. The AC electrolysis current density was 35 A / dm ² and the total electricity was 240 C / dm ² . At this time, the electrolytic surface roughening treatment was performed by changing the dissolved oxygen concentration in the nitric acid solution 210 as a parameter. The dissolved oxygen was changed by nitrogen purge as described above.

  SEM photography was performed on the surface of the roughened aluminum support 230, and the uniformity of the pits was evaluated by observing the surface. The evaluation results are shown in Table 1. SEM photographs taken at this time are shown in FIGS. FIG. 3 is an SEM photograph of the surface of an aluminum support that has been subjected to electrolytic surface roughening without removing dissolved oxygen in the nitric acid solution 210. FIG. 4 is an SEM photograph of the surface of an aluminum support from which dissolved oxygen in the nitric acid solution 210 was removed and electrolytic surface roughening was performed with a dissolved oxygen concentration of 3 mg / l.

The average pit diameter and pit density were calculated by analyzing a 174 × 254 μm SEM photograph. As the evaluation level of pit uniformity, the following four-level evaluation was made based on the comparative example.

○ ………… Excellent pit uniformity ○ ～ ○ △… Good pit uniformity ○ △ ～ △… Slightly good pit uniformity △ ………… Pit uniformity acceptable As shown in Table 1, dissolved oxygen concentration 6mg / It is preferable to perform the electrolytic surface treatment in a nitric acid solution of l or less. As a result, an aluminum support having a small pit average diameter, a large pit density, and good pit uniformity can be produced.

  Further, it is more preferable to perform the electrolytic surface treatment in a nitric acid solution having a dissolved oxygen concentration of 3 mg / l or less, and most preferably to perform the electrolytic surface treatment in a nitric acid solution having a dissolved oxygen concentration of 1 mg / l or less. preferable. Thereby, an aluminum support having a small pit average diameter, a larger pit density, and a better pit uniformity can be manufactured.

  Here, FIG. 3 and FIG. 4 are compared. FIG. 3 is an SEM photograph of the aluminum support surface manufactured under the conditions of the comparative example in Table 1, and FIG. 4 is an SEM photograph of the aluminum support surface manufactured under the conditions of Example 2 in Table 1.

  As apparent from FIGS. 3 and 4, the sample manufactured under the conditions of Example 2 has a smaller pit average diameter, a larger pit density, and is uniform than the sample manufactured under the conditions of the comparative example.

[Use as a support for lithographic printing plates]
(Desmutting treatment in acidic aqueous solution)
The obtained roughened aluminum plate was sprayed with an aqueous solution having a sulfuric acid concentration of 170 g / L, an aluminum ion concentration of 5 g / L, and a temperature of 50 ° C. from a spray tube to perform desmutting treatment for 5 seconds. As the sulfuric acid aqueous solution, the waste liquid of the anodizing process described later was used.

  Then, the liquid was drained with a nip roller. After draining, it was subjected to an anodizing treatment step without performing a water washing treatment.

(Anodizing treatment)
As the electrolytic solution, an electrolytic solution (temperature: 50 ° C.) in which aluminum sulfate was dissolved in a 170 g / L sulfuric acid aqueous solution to have an aluminum ion concentration of 5 g / L was used. The anodizing treatment was performed so that the average current density during the anodic reaction of the aluminum plate was 15 A / dm ² , and the final oxide film amount was 2.7 g / m ² .

  Thereafter, the liquid was drained with a nip roller, and further washed with water for 5 seconds using a spray tube having a spray tip in which spray water spread in a fan shape, and further drained with a nip roller.

(Hydrophilic treatment)
The aluminum plate was immersed in a 1% by weight aqueous solution of sodium silicate (temperature: 20 ° C.) for 10 seconds. The amount of Si on the surface of the aluminum plate measured with a fluorescent X-ray analyzer was 3.5 mg / m ² . Thereafter, the liquid was drained with a nip roller, and further washed with water for 5 seconds using a spray tube having a spray tip in which spray water spread in a fan shape, and further drained with a nip roller. Furthermore, 90 degreeC wind was sprayed for 10 seconds, it was made to dry, and the support body for lithographic printing plates was obtained.

Preparation of lithographic printing plate precursor A lithographic printing plate precursor was obtained by providing each lithographic printing plate support obtained above with a thermal positive type image recording layer as follows. Before providing the image recording layer, an undercoat layer was provided as described later.

An undercoat solution having the following composition was applied onto a lithographic printing plate support and dried at 80 ° C. for 15 seconds to form a coating film of an undercoat layer. The coating amount of the coating film after drying was 15 mg / m ² .

<Undercoat liquid composition>
・ The following polymer compound 0.3g
・ Methanol 100g
・ Water 1g

Furthermore, a heat-sensitive layer coating solution having the following composition was prepared, and the coating amount after drying the heat-sensitive layer coating solution (heat-sensitive layer coating amount) on a lithographic printing plate support provided with an undercoat layer was 1.8 g / m. ² was applied and dried to form a heat sensitive layer (thermal positive type image recording layer) to obtain a lithographic printing plate precursor.

<Thermosensitive layer coating solution composition>
Novolak resin (m-cresol / p-cresol = 60/40, weight average molecular weight 7,000, containing 0.5% by mass of unreacted cresol) 0.90 g
・ Ethyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (molar ratio 35/35/30) 0.10 g
-Cyanine dye A 0.1 g represented by the following structural formula
・ Tetrahydrophthalic anhydride 0.05g
・ 0.002 g of p-toluenesulfonic acid
-Ethyl violet counter ion with 6-hydroxy-β-naphthalenesulfonic acid 0.02 g
・ Fluorosurfactant (Megafac F-780F, manufactured by Dainippon Ink and Chemicals, solid content: 30% by mass) 0.0045 g (solid content conversion)
・ Fluorosurfactant (Megafac F-781F, manufactured by Dainippon Ink & Chemicals, Inc., solid content: 100% by mass) 0.035 g
・ Methyl ethyl ketone 12g

Evaluation of lithographic printing plate precursor The obtained lithographic printing plate precursor was evaluated for exposure / development sensitivity and adhesion to the upper layer.

(1) Sensitivity evaluation of exposure / development The obtained lithographic printing plate precursor was drawn in an image using a TrendSetter manufactured by Creo at a drum rotation speed of 150 rpm and a beam intensity of 10 W. Thereafter, using a PS processor 940H manufactured by Fuji Photo Film Co., Ltd., charged with an alkali developer having the following composition, the solution temperature was maintained at 30 ° C. and development was performed for 20 seconds to obtain a lithographic printing plate.

  As a result, the sensitivity of the lithographic printing plate precursor produced under any of the conditions of Examples 1 to 3 and Comparative Example in Table 1 was also good.

  The composition of the alkaline developer used for the sensitivity evaluation of the exposure / development is shown below.

<Alkali developer composition>
・ D-Sorbit 2.5% by mass
-Sodium hydroxide 0.85 mass%
・ Polyethylene glycol lauryl ether (weight average molecular weight 1,000) 0.5 mass%
・ Water 96.15% by mass
(2) Adhesion evaluation with upper layer (printing durability evaluation)
Next, adhesion evaluation with the upper layer was performed. Here, the adhesion evaluation with the upper layer is to evaluate the adhesion between the surface of the aluminum support on which pits are formed and the layer formed on the surface of the aluminum support. Here, the adhesion with the upper layer was judged by evaluating the printing durability. Evaluation of printing durability is performed by evaluating the number of printable sheets under each condition (Examples 1 to 3 in Table 1, comparative example), and is expressed as an index when the printable number of sheets in the comparative example is 100%. did.

[Conditions for printing durability test]
The resulting lithographic printing plate was printed on a Lithrone printing machine manufactured by Komori Corporation using DIC-GEOS (N) black ink manufactured by Dainippon Ink & Chemicals, Inc. Usually, printing durability was evaluated by the number of printed sheets at the time when it was visually recognized.

[Test results]
The test results are shown in Table 2 (the printing durability when the dissolved oxygen treatment is not performed is taken as index 100). In this table, Examples 1 to 3 and Comparative Examples are samples that were subjected to electrolytic surface formation treatment under the same conditions as Examples 1 to 3 and Comparative Examples in Table 1.

  As shown in Table 2, in Examples 1 to 3, the printing durability was improved as compared with the comparative example. It is considered that this is because the pit uniformity is improved by reducing the dissolved oxygen concentration in the nitric acid solution, and the printing durability is improved by improving the adhesion to the upper layer. This makes it possible to form pits of uniform size when the aluminum web W is continuously AC electrolyzed with an alternating waveform current while conveying the aluminum web W into the acidic electrolyte, thereby effectively improving the printing durability. It was proved that it can be improved.

In particular, as can be seen from the results of Examples 1 to 3, it can be seen that the dissolved oxygen concentration is most effective when the concentration is 1 mg / l or less. This shows that removal of dissolved oxygen in the nitric acid solution contributes to pit uniformity, that is, printing durability.

  On the other hand, it turned out that the comparative example which did not remove dissolved oxygen becomes poor in printing durability.

  DESCRIPTION OF SYMBOLS 10 ... Electrolytic surface roughening apparatus, 12 ... Electrolyzer main body, 12A ... Electrolyzer, 12B ... Opening part, 12C ... Overflow tank, 14 ... Roller, 16A ... Electrode, 18A ... Small electrode, 20A ... Insulating layer, 20C DESCRIPTION OF SYMBOLS ... Electrode holder, 22 ... Acid electrolyte replenishment flow path, 24A ... Upstream guide roller, 24B ... Downstream guide roller, 26 ... Direct current part, 28 ... Auxiliary electrolytic cell, 28A ... Bottom, 29 ... Auxiliary electrode, 29 ... Auxiliary electrode, 200 ... container, 210 ... nitric acid solution, 220 ... nitrogen gas, 230 ... aluminum support, 240 ... carbon electrode, 250 ... AC power supply

Claims (7)

A method for producing a lithographic printing plate precursor having an electrolytic surface roughening treatment step of performing an electrolytic surface roughening treatment on an aluminum support,
The electrolytic surface-roughening treatment step is a method for producing a lithographic printing plate precursor in which the electrolytic treatment is performed in an acidic solution having a dissolved oxygen concentration of 6.0 mg / l or less.   2. The method for producing a lithographic printing plate precursor according to claim 1, wherein the electrolytic treatment is alternating current electrolytic treatment or direct current electrolytic treatment by an anode reaction.   3. The lithographic plate according to claim 1, wherein the dissolved oxygen concentration is adjusted to 6.0 mg / l or less by removing oxygen contained in the acidic solution by any one of membrane degassing, nitrogen purging, and decompression. A method for producing a printing plate precursor.   A method for roughening a surface of an aluminum support, comprising subjecting the aluminum support to electrolytic treatment in an acidic solution having a dissolved oxygen concentration of 6.0 mg / l or less.   The method for roughening an aluminum support surface according to claim 4, wherein the electrolytic treatment is an alternating current electrolytic treatment or a direct current electrolytic treatment by an anode reaction.   The aluminum according to claim 4 or 5, wherein the dissolved oxygen concentration is adjusted to 6.0 mg / l or less by removing oxygen contained in the acidic solution by any one of membrane degassing, nitrogen purging, and decompression. A method for roughening the surface of a support.   The said aluminum support body is a support body for lithographic printing plates, The roughening method of the aluminum support body surface as described in any one of Claims 4-6 characterized by the above-mentioned.