JPH0225399A - Manufacture of support for planographic plate - Google Patents

Abstract

PURPOSE:To reduce the possibility of contamination in non-image areas and enhance scratch resistance and wear resistance of the non-image areas by electrochemically treating pores of an oxide film on a specified metallic plate with an oxide of a specified metal or the like. CONSTITUTION:Pores of a porous anodic oxide film on an aluminum plate or aluminum alloy plate are electrochemically treated with an oxide and/or hydroxide of a bivalent or higher valent metal by use of an AC or AC-DC superimposed current. The aluminum plate to be used is a plate-shaped body of pure aluminum, an aluminum alloy containing traces of foreign atoms, or the like comprising aluminum as a main constituent. An electrolyte used for porous anodic oxidation of the aluminum plate may be, generally, sulfuric acid, phosphoric acid, oxalic acid, chromic acid or a mixed acid thereof, sodium hydroxide, potassium hydroxide or a mixed liquid thereof, or the like. A metallic salt to be used for an electrolytic sealing treatment is a water-soluble salt of a bivalent or higher valent metal. The bivalent or higher valent metal may be, for example, calcium, magnesium, zinc, nickel, iron or copper, among which magnesium is particularly preferred.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a support for a photosensitive lithographic printing plate, and in particular to a method for producing a support for a photosensitive lithographic printing plate, and in particular a method for improving the anodic oxide film to make the non-image area of the support less likely to be scratched. The aim is to improve wear resistance.

[Conventional technology]

Conventionally, lithographic printing plates include so-called PS plates in which a photosensitive composition is coated in a thin layer on an aluminum plate. The surface is roughened by an electrochemical method such as the electrolytic grain method, or a combination of both methods, and the surface is made into a matte finish.Then, the surface is etched with an aqueous solution of acid or alkali, and then anodized. After that, it is subjected to a hydrophilic treatment if desired to obtain a support for a lithographic printing plate, and a photosensitive layer is provided on this support to form a P or S plate (photosensitive lithographic printing plate). This PS
The plate is usually subjected to imagewise exposure, development, correction, and gumming steps to form a lithographic printing plate, which is then mounted on a printing press and printed.

However, there is a problem in that scratches occur in non-image areas during these plate-making and printing steps, and ink tends to adhere to the scratches, resulting in printing stains.

For this reason, increasing the amount of anodized film has been considered as a method of improving the scratch resistance and abrasion resistance of the support surface. However, this method has drawbacks such as printing stains in non-image areas, dyeing in the pores of the anodized film, staining due to deposition of photosensitive material, and worsening of plate inspection properties due to blackening of the surface of the support.

In order to improve these drawbacks, Japanese Patent Application Laid-Open Nos. 58153698, 1981-193298, and 60-
In Publication No. 56093, ■2S0 with different porosity
4, H3P0. A two-stage electrolysis with a combination of baths is disclosed. However, since these treatments use phosphoric acid, there is a problem of pollution caused by waste liquid treatment, and these treatments are not practical.

Increasing the weight of the anodic oxide film not only causes the quality deterioration mentioned above, but also increases the cost of electricity required for electrolysis, so it is important to improve scratch resistance without increasing the weight of the anodic oxide film. A method was desired.

A porous oxide film has many pores on its surface, resulting in a decrease in surface hardness, but the method of closing the pores is to use water, steam with ammonia, triethanolamine, etc. added to it, or heating. There are sealing baths, or post-treatment of anodic oxide films in heating baths containing metal salts as seen in JP-A No. 62-216796, but these methods hardly achieve the abrasion resistance that is the objective of the present invention. No effect was seen.

As a method for electrochemically obtaining an anodic oxide film without pores, JP-A No. 53-2103 discloses a method of performing barrier-type anodization treatment on the surface of an aluminum support; Publication No. 153699 describes a method of carrying out re-anodizing treatment with an electrolytic solution containing an oxo anion such as boric acid after porous anodizing treatment.

When the pores are completely filled using these methods, the scratch resistance improves; for example, when sealing with an anodized film amount of 1.4 g/m', the scratch resistance is equivalent to an AD amount of 2.8 g/m'. reach the level of However, such a method requires a high voltage of several hundreds of volts, and is disadvantageous in terms of practicality and economy. Furthermore, from a quality standpoint, the level of scratch resistance achieved is still insufficient, and further improvement is desired.

Another method to improve scratch resistance and wear resistance is to fill the pores with a hard substance that is hard to scratch in order to increase the hardness of the surface. For example, JP-A-62-260
Publication No. 096 describes a method in which fine particles of a glass composition are filled into pores by electrophoresis and melted by heating.
), the pure aluminum commonly used as printing plates softens, causing a problem in which the strength of the printing plate is extremely deteriorated. Furthermore, no significant improvement in scratch resistance was observed in pore filling using electrophoresis with alumina, silica sol, or the like.

Next, as another method for improving scratch resistance and wear resistance, it is possible to fill the pores with a lubricating substance to make the surface of the anodic oxide film a lubricating surface. For example, JP-A-53-134744 describes a method of precipitating MoS2 in the pores of an anodic oxide film to thereby lower the coefficient of dynamic friction, but the precipitation of MoS2 is produced as a result of a complex chemical reaction. However, there are problems in that it is difficult to perform stable deposition under constant conditions, and it requires high voltage treatment.

Other methods include surface lubrication methods such as impregnating Teflon resin into the pores (Taflam processing) and producing metal soap in the pores (Japanese Unexamined Patent Publication No. 60112894). In either case, the surface is modified to be water-repellent, and the non-image area becomes a cause of printing stains, making it unsuitable as a printing plate support surface.

[Problem to be solved by the invention]

Therefore, an object of the present invention is to prevent contamination from occurring in non-image areas.
Another object of the present invention is to provide a lithographic printing plate support in which the non-image area has excellent scratch resistance and abrasion resistance, and also to provide a processing method that can be carried out at low cost.

[Means to solve the problem]

The present inventors have completed the present invention as a result of intensive studies to achieve the above object. That is, the present invention electrochemically fills the pores of a porous anodic oxide film on an aluminum plate or an aluminum alloy plate with an oxide and/or hydroxide of a divalent metal or more using alternating current or AC/DC superimposed current. This is a method for producing a lithographic printing plate support, characterized by filling the support.

Hereinafter, the present invention will be explained in detail step by step.

(Aluminum Plate) The aluminum plate used in the present invention is a plate-shaped body made of pure aluminum whose main component is aluminum or an aluminum alloy containing a trace amount of foreign atoms. Such foreign atoms include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of these foreign atoms is generally 10% by weight or less. Aluminum suitable for the support of the present invention is pure aluminum, but since it is difficult to produce completely pure aluminum due to smelting technology, it is preferable to use aluminum that contains as few foreign atoms as possible. As described above, the composition of the aluminum plate applied to the present invention is not specified; conventionally known and publicly used materials can be used as appropriate. The thickness of the aluminum plate used in the present invention is approximately 0.1 mm ~
Approximately 0.5 mm is appropriate.

(Surface Roughening Treatment) Prior to anodizing the aluminum plate, degreasing treatment and graining treatment are performed, for example, using a surfactant or an alkaline aqueous solution, in order to remove rolling oil from the surface, if desired.

Graining treatment methods include a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of selectively dissolving the surface chemically. As a method for mechanically roughening the surface, known methods such as ball polishing, brush polishing, blast polishing, puff polishing, etc. can be used.

Further, as an electrochemical surface roughening method, there is a method in which alternating current or direct current is used in an electrolytic solution such as hydrochloric acid or nitric acid. Furthermore, a method that combines both methods can also be used, as disclosed in Japanese Patent Application Laid-Open No. 54-63902. Furthermore, a method using a rectangular alternating waveform described in Japanese Patent Application Laid-Open No. 5277702 can also be mentioned.

The aluminum plate thus roughened can be surface-cleaned in a solution such as sulfuric acid, and is further subjected to alkali etching treatment and neutralization treatment if necessary.

(Porous anodizing treatment) Any electrolyte that forms a porous oxide film can be used as the electrolyte for porous anodizing treatment of aluminum plates, and generally, sulfuric acid, phosphoric acid, oxalic acid, Chromic acid or mixed acid or hydroxide)
IJ aluminum, potassium hydroxide, a mixture thereof, a bath containing ammonium fluoride, etc. are used, and the electrolyte and its concentration are determined as appropriate depending on the type of electrolyte. The processing conditions for porous anodic oxidation vary depending on the electrolyte used, so they cannot be definitively specified, but generally the electrolyte concentration is 1 to 80% by weight solution, the liquid temperature is 5 to 80°C, and the current density is 1 to 80A. /dm2, voltage 1-100V, electrolysis time 5
A range of seconds to 10 minutes is appropriate.

The amount of the porous anodic oxide film is preferably in the range of 0.1 to 10 g/m', more preferably in the range of 1 to 6 g/m'. The greater the thickness of the oxide film, the more the effects of the present invention can be exhibited.

In addition, the porosity and pore size cannot be specified because they vary depending on the electrolyte used, processing conditions, etc., but for example, when anodized using sulfuric acid, it is approximately 109 to 1011
The porosity is approximately 100-200 pores/cd in diameter.

(Electrolytic pore sealing treatment) Electrolytic pore sealing treatment is an electrolytic treatment using a metal salt, that is, a method of electrochemically filling the inside of the pore with metal oxide and/or metal hydroxide. This method is different from the so-called pore filling method in which pores are filled with alumina by electrolysis of a neutral salt containing oxo anions such as boric acid.

The metal salt to be used is a water-soluble metal salt with a valence of more than 2. Examples of the metal with a valence of 2 or more include calcium, magnesium, barium, zinc, nickel, cobalt, iron, copper, etc., but magnesium is particularly preferred. preferable. In addition, examples of the electrolyte salt constituting the present invention include salts of inorganic acids or organic carboxylic acids, such as sulfates, nitrates, phosphates, hydrochlorides, acetates, oxalates, and the like.

However, when monovalent so-called alkali metal salts such as Na5K and Li are used, as a result of examination using a wear tester of Suga Abrasion Tester, no effect on improving surface abrasion properties was found. Ta.

As a similar method, Japanese Patent Publication No. 54-11248 describes a method of increasing corrosion resistance by forming a cemented surface film through electrolytic treatment of calcium or magnesium salts. However, this method forms a cement film layer of Ca salt or Mg salt on the oxide film,
This is different from the present invention in which the inside of the pore is filled with a metal oxide or the like.

The purpose of the method according to the present invention is to improve the scratch resistance and abrasion resistance of the lithographic printing support, and its special feature is that a porous anodic oxide film is used, and the interior of the pores is divalent or higher. oxide and/or hydroxide of a metal, preferably magnesium.

For this purpose, additives can be added to the electrolyte, preferably the lactating agents EDTA (disodium ethylenediaminetetraacetic acid), citric acid, or ammonium hydroxide. It is preferable to add these additives because they stabilize the metal ions in the electrolytic solution and stabilize the metal hydroxide filled in the micropores of the oxide film, thereby increasing the filling effect.

Although the reason for the improved wear resistance is still unclear, the outermost surface of the substrate manufactured by the method according to the present invention has a porous oxide film and pores filled in the voids of the film. It is thought that the coexistence of magnesium oxide, etc., the hardness of the porous film, and the lubricating effect of magnesium hydroxide, etc., have an effect on wear resistance.

This electrolytic sealing treatment requires - For boat fishing, 1 to 10 of the above metal salts are used.
% solution, voltage 10-40V, current 0.1-0.
6 A/d112, temperature 3-15 at 20-35℃
This is done by processing for minutes. Under conditions more severe than this, hydroxides and the like will also precipitate on the surface of the support, and if these conditions are not met, the filling will be incomplete.

Therefore, by selecting such conditions, the pores can be selectively filled with metal oxide or metal hydroxide, and a lithographic printing plate support with excellent scratch resistance and abrasion resistance can be produced. .

(Parent wood layer) On the support according to the present invention, there are
A hydrophilic layer as described in US Pat. No. 2-19494 can be provided.

It is also possible, before or after providing this hydrophilic layer on the support according to the invention, to treat it with an aqueous solution of an alkali metal silicate (e.g. sodium silicate) as described in U.S. Pat. No. 3.18L 461. .

(Photosensitive layer) A conventionally known photosensitive layer can be provided on the lithographic printing plate support obtained in this way to obtain a photosensitive lithographic printing plate, which is then subjected to plate-making processing. The obtained lithographic printing plate has excellent performance.

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

(A) As the positive-acting photosensitive diazo compound, an ester of benzoquinone-1,2-diazide sulfonic acid chloride and polyhydroxyphenyl chloride or naphthoquinone-1,2- Most preferred are esters of diazide sulfonic acid chloride and pyrogallol-acetone resin. Other relatively suitable 0-quinonediazide compounds include benzoquinone 12-diazide sulfonic acid chloride or naphthoquinone described in U.S. Pat. Nos. 3.046.120 and 3.188.210 There is an ester of -1,2-diazide sulfonic acid chloride and phenol formaldehyde N fat.

The 0-quinonediazide compound alone constitutes the photosensitive layer, but a resin soluble in alkaline water may be used in combination as a binder. Examples of resins soluble in alkaline water include novolac resins, such as phenol formaldehyde resin, cresol formaldehyde resin,
Examples include pt-butylphenol formaldehyde resin, phenol-modified xylene resin, and phenol-modified xylene/mesitylene resin. Other useful alkaline water-soluble resins include polyhydroxystyrene, copolymers of polyhalogenated hydroxystyrenated (meth)acrylic acid and other vinyl compounds.

Further details of photosensitive layers consisting of 0-quinonediazide compounds and their developers are described in U.S. Pat. No. 4,259,434.

(B) A photosensitive composition comprising a diazo resin and a binder.

As a negative-acting photosensitive diazo compound, US Pat.
．． Diphenylamine, which is a reaction product of the diazonium salt disclosed in No. 063.631 and No. 2.667 and No. 415, and an organic condensing agent containing a reactive carbonyl group such as aldol or acecool. A condensation product of p-diazonium salt and formaldehyde (so-called photosensitive diazo resin) is preferably used. Other useful fused diazo compounds are U.S. Pat. No. 3.679.419, British Pat.
It is disclosed in each specification of No. 26. These types of photosensitive diazo compounds are usually obtained in the form of water-soluble inorganic salts,
Therefore, it can be applied from an aqueous solution.

In addition, these water-soluble diazo compounds are disclosed in British Patent Nos. 1 and 28.
0.885 with an aromatic or aliphatic compound having one or more phenolic hydroxyl groups, sulfonic acid groups, or both, and the reaction product is substantially water. It is also possible to use insoluble photosensitive diazo resins.

It can also be used as a reaction product with hexafluorophosphate or tetrafluoroboric acid as described in JP-A-56-121031.

In addition, the diazo resins described in US Pat. No. L 312,925 are also preferred.

Such diazo resins are used together with binders. Preferred binders are organic polymers having an acid value of 10 to 200, and specific examples include copolymers containing acrylic acid, methacrylic acid, crotonic acid, or maleic acid as an essential polymerization component, such as U.S. Pat. .123
．． 2-Hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, acrylonitrile or methacrylonitrile, acrylic acid or methacrylic acid and optionally further copolymerized polymers as described in No. 276. Original or quaternary copolymers, acrylic acid or methacrylic acid, acrylic acid which has a hydroxyl group at the end and is esterified with a group containing a dicarboxylic acid ester residue as described in JP-A-53120903. Alternatively, a copolymer of methacrylic acid and, if necessary, other copolymerizable monomers, a monomer having an aromatic hydroxyl group at the end (for example, N (4-hydroxyphenyl) methacrylamide, etc.), acrylic acid or methacrylic acid, and if necessary, a copolymer with at least one other copolymerizable monomer, JP-A-56
Copolymers of alkyl acrylate or methacrylate, acrylonitrile or methacrylonitrile, and unsaturated carboxylic acids as described in Japanese Patent No. 4144 are included.

Also useful are acidic polyvinyl alcohol derivatives and acidic cellulose derivatives.

(C) A composition containing a compound that undergoes trimerization upon irradiation with actinic rays. For example, polyvinyl cinnamate, polyvinyl cinnamoyl ethyl ether, polycinnamoyloxyethyl acrylate and its copolymers, polycinnamoyloxyethyl methacrylate and its copolymers, polyparavinylphenyl cinnamate and its copolymers. , polyvinylbenzalacetophenone and its derivatives, polyvinyl cinnamylidene acetate and its derivatives, allyl acrylate prepolymer and its derivatives, derivatives of polyester resins consisting of paraphenylene diacrylic acid and polyhydric alcohol, such as those disclosed in US Pat. Examples include compounds such as those described in Specification No. 3.030.208.

(D) A so-called copolymer composition that undergoes a polymerization reaction upon irradiation with actinic rays. For example, U.S. Patent No. 2,760.863
There is a composition comprising an addition-polymerizable unsaturated compound having two or more terminal ethylene groups and a photopolymerization initiator, which is described in No. 3,060,023 of the same.

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

(B) Electrophotographic photosensitive layer.

The electrophotographic photosensitive layer mainly consists of a photoconductive compound and a binder, but if necessary, known pigments, dyes, and chemical sensitizers may be added for the purpose of improving sensitivity and obtaining a desired photosensitive wavelength range. , other additives, etc. can be used.

The photosensitive layer can be composed of a single layer or a plurality of layers in which charge generation and charge transport functions are separated. A lithographic printing plate can be obtained by forming a toner image on a photosensitive layer by a known electrophotographic process, and using this as a resist layer, decoding non-image areas. For example, JP-A No. 31-17162, JP-A No. 38-6961, JP-A-56-107246, JP-A-60-254142,
JP 59-36259, JP 59-25217, JP 56-146145, JP 62194257, JP 57-147656, JP 58-100862, JP 5
It is described in many publications including No. 7-161863, and any of these can be suitably used.

The thickness of the photosensitive layer is 0.1-30 μm, more preferably,
It can be used at 0.5-10 μm.

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.

In the case of (A) or D), the coating amount of the photosensitive composition is approximately 0.1 to approximately 5.0 g/m' for boat fishing, and approximately 0.5 to approximately 3.0 g/m'. g/m' is more preferred.

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

(Effect of the invention) A support obtained by carrying out the method according to the present invention, that is, a support obtained by filling the pores of a porous anodic oxide film of aluminum with a divalent or higher valent metal salt oxide, etc. The lithographic printing plate obtained by exposing and developing a photosensitive lithographic printing plate using the lithographic printing plate has no contamination in the non-image area in both negative and positive types, and the image area and non-image area can be distinguished in the correction process. is easy. In addition, there are no correction marks, so there is no staining of the printed matter due to correction marks, and non-image areas are hard to scratch and have excellent wear resistance.Furthermore, the whiteness of the substrate is improved, and plate inspection is excellent. Also, it has the characteristics that the photosensitive composition dissolved during development is less likely to re-deposit, and non-image areas are less likely to be colored by dye or the like.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "%" in the examples indicates "% by weight" unless otherwise specified.

[Examples 1 to 7] The surfaces of JIS A1050 aluminum sheet materials were grained with a rotating nylon brush using a pumice water suspension as an abrasive. Surface roughness at this time (center line average roughness)
was 0.5μ. After washing with water, it was immersed in a 10% aqueous solution of caustic soda heated to 70°C, and etched so that the amount of aluminum dissolved was 6 g/m'.

After washing with water, it was immersed in a 30% nitric acid aqueous solution for 1 minute to neutralize it, and then thoroughly washed with water.

After that, in a 0.7% nitric acid aqueous solution, using a square wave alternating waveform with an anode special voltage of 13 volts and a cathode special voltage of 6 volts (
Power supply waveform described in the example of JP-A-52-77702) Electrolytic surface treatment was performed for 20 seconds, the surface was washed by immersion in a 20% sulfuric acid solution at 50°C, and then washed with water.

Next, using a 20% sulfuric acid aqueous solution, anodization was carried out at 28 V and IA/dm2 at room temperature for 80 seconds so that the weight of the oxide film was 1.5 g/m'. The pore size obtained at this time was 1008, and the porosity was approximately 1010/e.
It was nl. Thereafter, electrolytic sealing treatment was performed in an aqueous metal salt solution to produce a support. The power supply waveform used was a commercial alternating current, and the electrolytic voltage was preferably 60 V or less, preferably in the range of 10 to 40 V, and was selected from within this range.

The support obtained in this manner was tested for white density and abrasion resistance, and was coated with a photosensitive liquid having the following composition at a coating weight of 2.5 g/m'. Coated.

The photosensitive lithographic printing plate thus prepared was exposed in a vacuum printing frame through a transparent positive film from a distance of 1 m using a 3KW metal halide lamp for 50 seconds, and the molar ratio of 5102/Na2O was 1. .74
526% aqueous solution of IJium (pH = 12)
．． 7).

Then, it was thoroughly washed with water and the non-image area was examined for contamination.

The above results are shown in the table.

Next, after anodizing in the above-mentioned method, the support with the electrolytic sealing treatment name was immersed in No. 3 sodium silicate 2.5% at 10°C for 30 seconds, washed with water, dried, and then A photosensitive liquid was applied and dried to provide a photosensitive layer. The dry coating weight of the photosensitive layer was 2°Og/m'.

The photosensitive lithographic printing plate thus prepared was exposed in a vacuum printing frame through a transparent negative film from a distance of 1 meter using a 3KW metal halide lamp for 50 seconds, and then developed with a developer having the following composition. did.

developer Contamination in non-image areas was investigated and shown in the table.

Comparative Example 1 A substrate was subjected to anodization treatment in the same manner as in the example, and then no post-treatment was performed (Comparative Example 1); a substrate using a monovalent metal salt under the conditions of metal salt electrolytic sealing treatment (comparative example 1); Comparative example 2
．． 3), board using direct current as the power supply waveform (comparative example 4.5)
, a substrate electrolytically treated at high voltage (Comparative Example 6), a substrate subjected to hydration sealing by immersing it in pure water at 100°C for 2 minutes as a post-treatment method (Comparative Example 7), and a 4% ammonium borate aqueous solution. A substrate (Comparative Example 8) in which anodic electrolysis was performed at 400 V using the electrolyte as an electrolyte is shown in the table as a comparative example.

The photosensitive solution used was the same as in the examples.

Note 1: The difference (△D) between the reflective optical density of the non-image area and the surface of the support just before coating the photosensitive layer is ○...0.02 or less △...0. Thicker than 02 0.05 or less ×...
・Larger than 0.05 Note 2...Suga Test Instruments abrasion tester (NUSISO-
The degree of abrasion on the surface of the non-image area after 350 reciprocations with alumina abrasive paper using Type 1) was ranked by sensory evaluation into five levels: ◎, ○, △, △, and ×.

◎ Not worn ○ means hardly worn ○ △ Slightly worn △ Slightly worn in,
That is, it can be manufactured at low cost, and the resulting quality has excellent characteristics such as excellent abrasion resistance and resistance to staining of non-image areas.

In terms of wear resistance, the use of magnesium salt in particular significantly improves the wear resistance compared to the comparative example, and the addition of chelating agents such as EDTA, ammonium chloride, ammonium hydroxide, etc. as additives improves the wear resistance even more. I was able to get a great effect.

Claims (1)

[Claims] A method characterized by electrochemically filling the pores of a porous anodic oxide film on an aluminum plate or an aluminum alloy plate with an oxide and/or hydroxide of a divalent or higher valent metal using alternating current or AC/DC superimposed current. A method for producing a support for a lithographic printing plate.