JPS60190392A - Aluminum support for lithographic plate and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the titled support which has high printing performance with a specified average roughness of center line by applying an alternating waveform voltage to an Al plate in an electrolytic liquid containing nitric acid to form the second pit after the formation of the primary pit by applying the alternating waveform voltage therto in the electrolytic liquid containing hydrochloric acid. CONSTITUTION:An alternating waveform voltage is applied to an aluminum plate in an electrolytic liquid containing hydrochloric acid as main component to form the primary pit 1-30mum in the diameter and 0.1-10mum in the depth and then, an alternating waveform voltage is applied thereto in an electrolytic liquid containing nitric acid as main component to form the secondary pit 1- 30mum in the diameter and 1mum or less in the depth. Thus, the desired support is obtained with the average roughness of center line (Ra) of 0.4-1.0mum. It should be noted that a dismatting is preferably applied before the process of forming the secondary pit following the primary pit formation process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aluminum support for lithographic printing and a method for producing the same. The present invention relates to a method for producing an aluminum support for lithographic printing having excellent printing performance, by performing electrolytic surface roughening treatment in a nitric acid-based electrolytic solution.

[Prior art]

Conventionally, there are a variety of methods for producing supports for lithographic printing plates by roughening aluminum or plate-shaped bodies made of nine alloys mainly composed of aluminum (hereinafter referred to as aluminum plates). - Mechanical surface roughening methods such as graining, wire graining, and brush graining, electrochemical methods such as electrolytic graining, or a combination of both methods. After being made into a shape, it is etched with an aqueous solution such as acid or alkali, and then subjected to anodization treatment and, if desired, hydrophilic treatment to obtain a support for one plate of lithographic printing. A photosensitive layer is provided on this support to form a lithographic printing plate (so-called PS plate). This 28
The plate is usually subjected to processes such as exposure, development, correction, and gumming to form a printing plate, which is then mounted on a printing machine and printed.

By the way, in roughening the surface of an aluminum plate, the mechanical roughening described above generally results in sand 1 having a simple structure, and the grain surface is smooth. On the other hand, electrochemical roughening method
Until the electrolytic surface roughening cools down, grains similar to those in mechanical roughening are formed, but when electrolytic surface roughening is continued further, finer secondary pits are formed within these pits. ,
It becomes a pit with a single layer structure, and the center line average roughness is o, lIL.
Although the pits are larger than .mu., the lithographic printing plate using an Al 1=U plate as a support having such double structure bits has a drawback in that it consumes a large amount of power in its manufacture. Moreover, the single-layer structure bit formed in this way has grains with an excessively complicated shape, and the photosensitive layer in the non-image area may remain during development, and the non-image area may become smeared during printing. It also has the disadvantage that it is relatively easy to occur. For this reason, methods have also been developed in which the seventh pit is formed by mechanical graining, and the negative pit is formed by electrolytic surface roughening (for example, in Japanese Patent Laid-Open No. 33
-/4', see Publication No. 215). In this method, it is important to form many small-diameter hemispherical pits in the co-order roughening process by electrolysis. However, when the seventh pit is mechanically formed, the cross-sectional shape becomes wavy in the vertical direction with respect to the center line, so the overall water retention is poor and the non-image area is easily smudged.

Generally, electrolytic surface roughening treatment can be carried out using alternating current in an electrolytic solution containing mainly hydrochloric acid or nitric acid.

The grains formed by electrolytic graining are developed pitting holes caused by aluminum dissolution, and have a crater-like or honeycomb-like structure, and the pores are straight compared to mechanical graining. It is also characterized by its openness. Furthermore, compared to mechanical graining, the depth of the holes can be controlled more precisely, and a substrate can be produced with a surface roughness greater than that obtained by mechanical graining.

The grain shape and surface roughness can be adjusted depending on the type of electrolyte and electrolytic conditions.
E), 2.4!0.762, the following is disclosed.

The roughened surface obtained when nitric acid or an electrolyte mainly composed of nitric acid is used has a single-layer structure of pores in which extremely fine pores are present on the surface of the pores produced by electrochemical corrosion. shape, but the depth of the pores is generally shallow (pore diameter/~3
μ, pore depth/μ or less). Therefore, water retention is weak and hydrophilicity is also insufficient. On the other hand, when using hydrochloric acid or an electrolyte mainly composed of hydrochloric acid, the depth of the pores is generally large, but the pore surface is relatively smooth, compared to when using a nitric acid-based electrolyte. It will not result in a complicated uneven surface like that (
Pore diameter/~3θμ, hole depth O1l~)θμ) Therefore,
The holding power of the photosensitive layer is weak and the printing durability is insufficient.

Although aluminum plates subjected to electrochemical graining have a large surface roughness, they have the drawbacks of insufficient hydrophilicity in non-image areas and insufficient printing durability. ◎ [Object of the Invention] Therefore, the object of the present invention is to provide a support for a lithographic printing plate having high printing durability. In other words, it is a lithographic printing plate that has excellent adhesion to the constituent materials of the image area that receives ink, and also exhibits stable hydrophilicity in the non-image area during printing operations to produce prints of good quality. The purpose is to provide support.

Another object of the present invention is to provide a method for producing a lithographic printing plate support having non-directional grain.

Another object of the present invention is to provide a support for a lithographic printing plate that has a large average roughness and has excellent hydrophilicity and water retention.

[Structure of the invention]

As a result of repeated research, the inventors of the present invention found that the depth of the holes is large, and by superimposing fine and complicated holes on a rough surface to form a smooth grain, the present inventors The inventors have discovered that the object of the invention can be achieved, and have completed the present invention.

That is, the present invention provides an aluminum surface with a pore diameter/μ~3
A primary bit with a diameter of 0μ and a depth of 0.7μ to /θμ and a hole diameter of /μ to 3μ and a depth of /μ provided superimposed on the core/secondary bit.
An aluminum support for a lithographic printing plate is characterized in that it has the following secondary bits and has a center line average roughness (Ra) of θ, g~/, θμ.

An alternating waveform voltage is applied to the aluminum plate in a solution to form a seventh-order pit with a hole diameter of /μ to 30μ and a depth of θ of /μ to 10μ. Applying an alternating waveform voltage to the aluminum plate, the hole diameter / μ ~ 3
μ, and is obtained by forming secondary pits with a depth of lμ or less. The centerline average roughness (Ra) of the surface of the aluminum support thus obtained is o, 4t~/, θμ.

In the method of the present invention, a comparatively thick smut film is produced in the seventh bit formation step, that is, the electrolytic surface roughening treatment step in an electrolytic solution containing hydrochloric acid, so a desmut treatment is performed to dissolve and remove the smut, and then the primary pit formation treatment is performed. It is desirable to apply

The aluminum plate used in the present invention includes pure aluminum and aluminum alloy plate. Various aluminum alloys can be used; for example, alloys of aluminum and metals such as silicon, iron, copper, manganese, magnesium, chromium, zinc, lead, bismuth, and nickel are used.

Before the aluminum plate is subjected to electrolytic surface roughening treatment, it is optionally subjected to degreasing treatment or etching treatment in order to remove rolling oil from the surface and to expose a clean aluminum surface. The degreasing treatment is performed by cleaning the surface using a solvent such as trichloride, a surfactant, etc., and the secondary etching treatment is performed using an alkaline etching agent such as sodium hydroxide or potassium hydroxide.

In the etching process, the alkaline etching agent θ, O3-
Using an aqueous solution of θ wt %, at a liquid temperature of θ°C to 100°C! It is common to process for f~300 seconds. In the case of alkaline etching, smut is generally generated on the surface of aluminum, so phosphoric acid, nitric acid,
Desmut treatment is preferably performed using sulfuric acid, chromic acid, or a mixed acid containing one or more of these acids.

Subsequently, a first stage electrolytic surface roughening treatment is performed in an electrolytic solution containing hydrochloric acid. The hydrochloric acid concentration of the electrolytic solution is suitably selected from a range of about 0.3 to 3% by weight. Corrosion inhibitors (or stabilizers) such as chlorides, monoamines, cyamines, aldehydes, phosphoric acid, chromic acid, and boric acid can be added to this electrolytic solution, if necessary. Further, the temperature of the electrolytic bath is preferably about 10 to 60oC, /, 1--! 0°
c is particularly preferred. When performing the first stage electrolytic surface roughening treatment in a hydrochloric acid electrolyte, Japanese Patent Publication No. Sho+r-Iza 723, Japanese Patent Application Laid-Open No. 17311, Japanese Patent Application Laid-open No. 5.2-
303-03, JP-A-Sho S-/RI-JtVq, JP-A-Sho-JS-17310, JP-A-Sho Sλ-tag gt
It is possible to use sine wave alternating current, special sine wave alternating current, and special alternating waveforms disclosed in Japanese Patent Application Laid-Open No. 5-3-47307, etc. A special alternating waveform is more preferable because it can reduce power consumption.

The alternating waveform voltage used in the electrolytic surface roughening method of the present invention is a waveform voltage obtained by alternately exchanging positive and negative polarities, and includes a sinusoidal single-phase alternating current, a sinusoidal three-phase alternating current, This includes any alternating waveform voltages such as square waves and trapezoidal waves.

In a preferred embodiment of the present invention, an aluminum plate in an acidic electrolyte has an anode current of 1 t (QA) and a cathode specific electricity (QA).
An alternating waveform current is passed so that the current becomes larger than QC). A particularly preferable QC/QA ratio is Ol, ? ~ o, qs
It is. In this case, U.S. Patent No. I, (X7,3'l
For use in companies where the anode voltage is higher than the cathode dark voltage, as described in the specification of No. Preferably, a waveform voltage is applied. FIG. 1 shows the waveform of the alternating waveform voltage.

FIG. 7(a) shows an alternating waveform voltage using a sine wave, FIG. 7(b) a rectangular wave, and FIG. 7(C) a trapezoidal wave; any of the waveforms can be used in the present invention.

The voltage applied to the aluminum plate is about /~Sθ delt, more preferably 1.2-30g delt, the current density is about 70~/00 A/dm2, and the electric bone is about IO
θ~30θoo coulombs/dm2, more preferably 10
It is selected from the range of 0 to 3θoo coulombs/dm.

When such conditions are adopted, primary pits with a hole diameter of /μ to 30μ and a depth of o, /μ to /θμ are formed by the electrolytic surface roughening treatment in the first stage, and in the second stage, vi By the Mm surface processing, a secondary bit with a hole diameter of /μ to 3μ and a depth of less than lμ is formed, and the center line average roughness (Ra) of the surface of this aluminum plate is 0.41-/, θμ. By using the thus treated aluminum plate as a support for a lithographic printing plate, a printing plate with excellent printing durability can be obtained.

When the current density is lower than about 10 A/dm2, the diameter and depth of the pits formed become small, making it difficult to obtain a lithographic printing plate support with large roughness, which is the object of the present invention.

Furthermore, if a nitric acid-based electrolyte is used as the electrolytic solution in the first stage electrolytic surface roughening treatment, it is possible to obtain pits with the same pore diameter and depth as those obtained when a hydrochloric acid-based electrolyte is used. This is not preferable because it requires a higher current density than when a hydrochloric acid electrolyte is used, which increases the power cost.

Subsequently, it is preferable to perform a desmut treatment in order to remove the smut formed in the first stage electrolytic treatment.

This is because smut adhering to the aluminum surface caused by the first-stage electrolytic roughening treatment may make it impossible to uniformly form pores on the surface. be. This desmatting process was developed in Japanese Patent Application Publication No. 5
,? This can be carried out by the high-temperature sulfuric acid solution immersion method disclosed in Japanese Patent Publication No. 12739 or the sodium hydroxide solution immersion method disclosed in Japanese Patent Publication No. 4TG-Kognoko No. 3.

In addition, aqueous solutions of phosphoric acid, chromic acid, nitric acid, hydrofluoric acid, etc. can also be used. Further, when the aluminum surface is treated with an alkaline aqueous solution, smut is formed on the aluminum surface, so it is desirable to further perform a desmut treatment with the above-mentioned acidic solution.

Thereafter, a second electrolytic surface roughening treatment is performed in a nitric acid electrolyte. As the nitric acid electrolyte used, conventionally known ones can be used. It is appropriate that the nitric acid concentration be selected from a range of about 0.5% to 3% by weight.This electrolyte may contain nitrates, monoamines, cyamines, aldehydes, phosphorus, etc. as necessary. Corrosion inhibitors (or stabilizers) such as acids, chromic acid, boric acid, etc. can be added.

Further, the temperature of the electrolytic bath is preferably about 10oC to 6o'C,
/1 season to Sθ°C is more preferable. When performing the first stage electrolytic surface roughening treatment, Japanese Patent Publication No. 2g1.23, British Patent No. A,! Publication No. t&3, Unexamined Japanese Patent Publication No. JT3-
The method described in Japanese Patent No. 67!507 can be used. Among these methods, Japanese Patent Application Laid-Open No. 53-67J
The method of electrolytic surface roughening treatment using a special alternating waveform described in Japanese Patent No. 07 is most preferable because the power consumption can be reduced and any grain shape can be obtained. The electrolytic surface roughening method using a special alternating waveform can be carried out in the same manner as the first stage electrolytic treatment.

After completing the first stage electrolytic surface roughening treatment, the formed saletas mat is removed again. This desmutting treatment can be performed by the same method as the desmutting treatment after the first stage electrolytic treatment.

The aluminum plate thus treated is then anodized.

The anodic oxidation treatment can be performed by a method conventionally practiced in this field. Specifically, sulfuric acid, phosphoric acid,
When a direct or alternating current is passed through aluminum in an aqueous or non-aqueous solution containing chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc. or a combination of two or more of these, an anodized film is formed on the surface of the aluminum support. I can do it.

The treatment conditions for anodic oxidation cannot be generally determined because they vary depending on the electrolyte used.

In general, the concentration of the electrolyte is 7 to 30%, the liquid temperature is s to ri, and the current density is OJ to A.
Suitable ranges are a dm2 voltage of 7 to /θOV and an electrolysis time of 10 seconds to so minutes.

Among these anodizing treatments, especially the British Patent No. 8 Da/
A method of anodizing at high current density in sulfuric acid is described in U.S. Pat. No. 76g and US Pat. ! F//
Preferred is the method of anodizing using phosphoric acid as an electrolytic bath, as described in the specification of No. 44/.

Anodized Alonium plates are further described in U.S. Patent No. 2. R/G, No. 066 and No. 3. Alkali, metal silicates,
For example, it may be treated by a method such as immersion in an aqueous solution of sodium silicate, or as described in US Patent No. 3. F2O,! As described in I2A, an undercoat υ layer of hydrophilic cellulose (such as carboxymethylcellulose) containing a water-soluble metal salt (such as zinc acetate) may also be provided.

A conventionally known photosensitive layer is provided as a photosensitive layer of a PS plate on the support for a planographic printing plate obtained in this way, and a photosensitive planographic printing plate can be obtained, which is subjected to plate-making processing. The resulting lithographic printing plate has excellent performance.

As the composition for the above-mentioned photosensitive layer, any one can be used as long as its solubility or swelling property in a developer changes before and after exposure to light. The typical ones will be explained below.

■? Di-acting photosensitive diazo compound.

For example, the ester of benzoquinone-7,-1diazide sulfonic acid chloride and polyhydroxyphenyl, or the naphthoquinone-/, codeiazide sulfonic acid chloride and pyrogallol-acetone resin described in Japanese Patent Publication No. 113-22-4tOJ Esters with are most preferred. Other relatively suitable 0-quinonediazide compounds include U.S. Pat. /zag, No. 219, benzoquinone-/, cordiazide sulfonic acid chloride or s7toquinone-1. ．． There are esters of 2-diazide sulfonic acid chloride and phenol formaldehyde resin.

Although the 0-quinonediazide compound alone constitutes the photosensitive layer, it is common to use a resin soluble in alkaline water as a binder together with this type of resin. As a resin soluble in this alkaline water, does it have this property? Lac resin resin, such as phenol formaldehyde resin, cresol formaldehyde resin, p-t
-butylphenol-formaldehyde resin, phenol-modified xylene resin, phenol-modified xylene/mesitylene resin, etc. Other useful alkaline water-soluble resins include polyhydroxystyrene, copolymers of polyhalogenated hydroxystyrenated (meth)acrylic acid and other vinyl compounds.

■Negative-acting photosensitive diazo compound.

For example, diazonium salts containing reactive carbonyl groups such as aldols and acetals are disclosed in U.S. Pat. A condensation product (so-called photosensitive diazo resin) of diphenylamine-p-diazonium salt, which is a reaction product with an organic condensing agent, and formaldehyde is preferably used. Other useful condensed diazo compounds are Special Publication Showa 4I? -111f00/issue, same Dadegu! F3 Co., 1I9-Hiro! It is disclosed in various publications such as No. 3.23. These types of photosensitive diazo compounds are usually obtained in the form of water-soluble inorganic salts and can therefore be coated from an aqueous solution. Father, these water-soluble diazo compounds were developed by
A substantially water-insoluble reaction product obtained by reacting with an aromatic or aliphatic compound having seven or more phenolic hydroxyl groups, sulfonic acid groups, or both by the method disclosed in Publication No. 7-1147. It is also possible to use photosensitive diazo resins.

Also, Tokukai Akira! It can also be used as a reaction product with hexafluorophosphate or tetrafluoroborate, as described in Publication No. 1-4-/Co1oai. Is that TL, British Patent No. 7,31? Also preferred are the diazo resins described in No. 2s specification.

■ A composition containing a compound that causes beading upon irradiation with actinic rays.

For example, polyvinyl cinnamate, polyvinyl cinnamoyl ethyl ether, polyethyl cinnamate acrylate,
and copolymers thereof, polyethyl cinnamate methacrylate and copolymers thereof, vinyl phenyl cinnamate and copolymers thereof, polyvinylbenzalacetophenone and derivatives thereof, polyvinylcinnamylidene acetate and derivatives thereof, acrylic acid Allyl prepolymers and derivatives thereof, derivatives of polyester resins consisting of paraphenylene diacrylic acid and polyhydric alcohol, such as those described in US Pat. No. 3,030.30g.

■ So-called photopolymerizable compositions that cause a polymerization reaction when irradiated with active light.

For example, U.S. Patent No. 740. gls3 and gls3
．． No. 040,023 discloses a composition comprising an addition monounsaturated compound having one or more terminal ethylene groups and a photopolymerization initiator.

The compound that undergoes a monomerization and the compound that undergoes a polymerization reaction upon irradiation with actinic rays may further contain a resin as a binder, a sensitizer, a thermal polymerization inhibitor, a dye, a plasticizer, and the like.

The photosensitive composition as described above is usually applied as a solution of water, an organic solvent, or a mixture thereof onto the support according to the present invention, and dried to prepare a photosensitive lithographic printing plate.

The coating amount of the photosensitive composition is generally about 0.1 to about ! r
, 09/m2 is suitable, about 0.5 to about 3.0
g/m2 is more preferred.

The photosensitive lithographic printing plate thus obtained is imagewise exposed to a light source containing actinic rays such as a Carden arc lamp, a xenon lamp, a mercury lamp, a tungsten lamp, a metal halide lamp, etc., and developed to obtain a lithographic printing plate.

〔Effect of the invention〕

The aluminum support for lithographic printing plates of the present invention has a large average roughness and is excellent in hydrophilicity and water retention. Therefore, this aluminum support can be used to produce high-quality printed matter with long printing durability. A feedable lithographic printing plate is obtained.

〔Example〕

Hereinafter, the present invention will be explained in more detail using examples.

In addition, "chi" in the examples means "ji" unless otherwise specified.
This indicates "chi".

Example / (a) An aluminum plate with a thickness of O, body%, was immersed in a 70% sodium hydroxide aqueous solution for 0 seconds at 60°C to extrude clean aluminum, and then soaked in a 30% sodium nitric acid aqueous solution. Desmat treated.

(b) This aluminum plate was exposed to hydrochloric acid in g g/13
In the electrolytic solution contained therein, an alternating rectangular waveform voltage shown in FIG. 1(b) was applied to carry out electrolytic surface roughening treatment. The electrolytic conditions are: frequency 40 Hz Vi, - = = Col = 0, Vo =
/ lI volt, anode electricity m' QA= 300
It was subjected to electrolytic surface roughening treatment for 6 seconds so that coulomb/dm and Qc/QA" 0.90, and then washed with water.

(c) Next, the smut was completely dissolved in a 10% sodium hydroxide aqueous solution. Further, after washing with water, a desmutting treatment was performed with a nitric acid aqueous solution.

(b) Next, this aluminum plate was electrolytically roughened by applying a rectangular alternating waveform voltage shown in FIG. 1(b) in an electrolytic solution containing Y/e of nitric acid. Electrolysis conditions are frequency 6
0 Hz, VA=-2j volts, VC=/3? power, anode electricity 1tQA=/'7A coulomb/dm2=Q
Electrolytic surface roughening treatment was performed for 3 seconds so that C/QA = 0.7/.

(e) Place this aluminum plate in a 30% sulfuric acid aqueous solution! Ooc, after immersion for 30 seconds and desmutting,
Washed with water. Subsequently, the substrate was anodized in a 19% aqueous sulfuric acid solution so that the oxide film was approximately 0.1 μm, and then washed with water to prepare a support [A].

Next, a photosensitive solution with the following composition CI] was applied using a spin coating machine,
The coating weight after drying is ko! r,! il/m".

The photosensitive lithographic printing plate thus prepared was exposed in a vacuum printing frame through a transparent bozotable film from a distance of 7 m for 50 seconds using a 3 KW metal halide lamp, and the molar ratio of 5102/Na2O was 874'
Left, coro% aqueous solution of sodium silicate (pH=/2
．． Developed with ri).

The printing plate made in this way was printed according to the usual procedure. In addition, the pore diameter of the pit was determined using a scanning electron microscope.
The depth was measured by oblique observation, and the depth was measured by observing the cut cross section of the substrate with an ultramicrotome using an electron microscope.

The results are shown in Table 7.

Comparative Example 1 In Example 1, #1 which did not perform the desmutting treatment in step (c) and the de-roughening treatment in step (d) was as follows.
A support CB) was prepared in exactly the same manner as in Example 1, and a printing plate was prepared by exposure and development in the same manner, and printing was performed.

Comparative Example In Example 1, except that the seventh electrolytic surface roughening treatment in step (B) and the desmut treatment in step (C) were not performed,
A support (C'l) was prepared in exactly the same manner as in Example No.
A printing plate was prepared by exposure and development in the same manner, and printing was performed.

Table 1 shows the dimensions of the bits of the supports and the printing durability of the printing plates of Comparative Examples/Co.

The printing durability of the first table was printed on a Heidelberg KOR printing machine.
The evaluation was based on the number of prints that could be obtained with good image areas.

From the results shown in Table 1, it can be seen that the support of the present invention has a large center line average roughness, and at the same time has a large holding power for the photosensitive layer due to the micropores present, and therefore has excellent printing durability. I understand.

[Brief explanation of drawings]

FIG. 1 illustrates alternating voltage waveforms which are advantageously used in the method of the invention: (,) are sine waves, (b) are rectangular waves, and (c) are trapezoidal waves. (VA) is the anode dark voltage,
(Vc) is the cathode special voltage, (tA) is the anode time, (t
c) is the cathode time. 7 Figure 1 (a) (b) (c)

Claims (3)

[Claims] (1) Al 1 = 4 surface K, pore diameter lμ ~ 30μ, depth 0. /μ~10μ 7th order bit and nucleus/order pit overlappingly provided, hole diameter lμ~3μ, depth! It has secondary pits of μ or less, and has a center line average roughness (Ra) of 0. 'l
-/, Dμ Al 2 for lithographic printing plate
nium support. (2) Applying an alternating waveform voltage to the aluminum ζ plate in an electrolytic solution containing hydrochloric acid as a main component, the pore diameter/μ ~ 30μ, depth 0. A seventh-order pit of /μ to lθμ is formed, and then an alternating waveform voltage is applied to the aluminum plate in an electrolytic solution containing nitric acid as a main component to form a secondary pit with a hole diameter of /μ to 3μ and a depth of 7μ or less. The centerline average roughness Ra) is o,
A method for producing an aluminum support for a lithographic printing plate, the method comprising obtaining an aluminum plate having a diameter of 4t to 1, θμ. (3) The manufacturing method according to claim 1, characterized in that after the primary pit forming step, a desmutting treatment is performed in the secondary pit forming step.