JPH0798433B2 - Method for producing support for lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a support for a photosensitive lithographic printing plate, and in particular, an anodized film is modified so that the non-image portion of the support is less likely to be scratched. Now, it is intended to improve wear resistance.

[Conventional technology]

Conventionally, a lithographic printing plate has a so-called PS plate in which a photosensitive plastic material is coated in a thin layer on an aluminum plate, but the above-mentioned aluminum plate is usually a mechanical method such as a brush grain method or a ball grain method or It is subjected to a roughening treatment such as a galvanic electrochemical method such as an electrolytic grain method or a combination of both methods, and after the surface is made satin-finished, it is etched with an aqueous solution of acid or alkali, and further anodized. After that, a hydrophilic treatment is applied if desired to obtain a support for a lithographic printing plate, and a photosensitive layer is provided on the support.
PS plate (photosensitive lithographic printing plate). This PS plate is usually subjected to image exposure, development, correction and gumming steps to obtain a lithographic printing plate, which is attached to a printing machine for printing.

However, there has been a problem that scratches are generated in the non-image area at the stage of these plate making and printing steps, and the ink is attached to the scratched area to easily cause print stains.

Therefore, increasing the amount of anodized film has been considered as a method for improving the scratch resistance and wear resistance of the surface of the support. However, this method has drawbacks such as print stains on non-image areas, dye in the pores of the anodized film, dyeing due to the deposition of a photosensitive material, and blackening of the surface of the support, resulting in deterioration of plate inspection property.

To improve these drawbacks, JP-A-58-153698,
JP-A-59-193298 and JP-A-60-56093 disclose two-stage electrolysis by combining H ₂ SO ₄ and H ₃ PO ₄ baths having different porosities. However, these processes
Since phosphoric acid is used, there is a problem of pollution of waste liquid treatment, which is not practical.

Increasing the weight of the anodic oxide coating leads to an increase in cost due to the electricity cost required for electrolysis in addition to the above-mentioned deterioration in quality, so scratch resistance is improved without increasing the weight of the anodic oxide coating. A method was desired.

The surface hardness of the porous oxide film is reduced because there are many voids on the surface, but as a method of closing the pore voids, water or steam obtained by adding ammonia, triethanolamine, etc., or heating is used. There are sealing in a bath, post-treatment of an anodic oxide film in a heating bath containing a metal salt as disclosed in JP-A-62-216796, etc., but almost no abrasion resistance is the object of the present invention. No effect was seen.

As a method for electrochemically obtaining an anodized film having no pores, JP-A-53-1203 discloses a method of subjecting an aluminum support surface to a barrier type anodizing treatment, and JP-A-58-2. Japanese Patent No. 153699 describes a method of performing reanodizing treatment with an oxoanion-containing electrolytic solution such as boric acid after the porous anodizing treatment.

When the pores are completely filled by these methods, the scratch resistance is improved, and for example, when the anodized film amount of 1.4 g / m ² is sealed, it becomes a level equivalent to the scratch resistance of AD amount of 2.8 g / m ^2. Become. However, such a method requires a high voltage of several hundreds V and is a disadvantageous method from the viewpoint of practicality and economy. or,
In terms of quality, the level of achievement of scratch resistance is still insufficient, and further improvement is desired.

As another method for improving scratch resistance and other abrasion resistance, it is conceivable to fill the pores with a hard material that is hard to be scratched in order to increase the hardness of the surface. For example, JP-A-62-260096 describes a method in which pores are filled with glass composition particles by an electrophoretic method and heated and melted.
In this method, there is a problem that pure aluminum, which is generally used as a printing plate, is softened at the heating dissolution temperature (350 to 450 ° C.), and the strength of the printing plate is extremely deteriorated. In addition, no significant improvement in scratch resistance was observed by filling pores by an electrophoresis method using 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 anodized film a lubricating surface. For example, in JP-A-53-134744, MoS _{2 is} contained in the anodic oxide film pores.
Although a method of lowering the dynamic friction coefficient by this is described, the precipitation of MoS ₂ is a result of a complicated chemical reaction, and it is difficult to precipitate under stable constant conditions.
There is a problem of high voltage processing. In addition, as other methods, there are surface lubrication methods such as a method of impregnating Teflon resin in the pores (tuffram processing) and a method of generating metallic soap in the pores (JP-A-60-112894). However, in all cases, there is a problem in that the surface is modified to be water-repellent, the non-image area causes printing stains, and is not suitable as the surface of the printing plate support.

[Problems to be Solved by the Invention]

Therefore, an object of the present invention is to provide a lithographic printing plate support in which the non-image area is less likely to be contaminated, and the non-image area is excellent in scratch resistance and abrasion resistance, and can be inexpensively processed. To provide.

[Means for Solving the Problems]

The present inventors have completed the present invention as a result of intensive studies to achieve the above object. That is, the present invention uses a porous anodized film of an aluminum plate or an aluminum alloy plate to electrochemically electrochemically convert the pores of a metal oxide and / or hydroxide of divalent or higher valence into alternating current or alternating direct current. A method for producing a support for a lithographic printing plate, which comprises filling.

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

(Aluminum Plate) The aluminum plate used in the present invention is a plate-shaped body such as pure aluminum containing aluminum as a main component or an aluminum alloy containing a slight 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 which is suitable for the support of the present invention is pure aluminum, but completely pure aluminum is difficult to produce due to the kneading technology, and therefore it is preferable that it contains as few foreign atoms as possible. As described above, the aluminum plate applied to the present invention is not specified in its composition, and conventionally known and publicly available aluminum plates can be appropriately used. A suitable thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.5 mm.

(Roughening treatment) Prior to anodizing the aluminum plate, a degreasing treatment with a surfactant or an alkaline aqueous solution and a graining treatment for removing rolling oil on the surface are optionally carried out.

The graining treatment method includes a method of mechanically roughening the surface, a method of electrochemically melting the surface, and a method of chemically selectively melting the surface. As a method for mechanically roughening the surface, a known method called a ball polishing method, a brush polishing method, a blast polishing method, a buff polishing method or the like can be used.

Further, as an electrochemical graining method, there is a method of performing alternating current or direct current in an electrolytic solution such as hydrochloric acid or nitric acid. Further, as disclosed in Japanese Patent Laid-Open No. 54-63902, a method in which both are combined can be used. Furthermore, a method using a rectangular wave alternating waveform described in JP-A-52-77702 can be mentioned.

The surface of the aluminum plate thus roughened can be washed in a solution of sulfuric acid or the like, and if necessary, an alkali etching treatment and a neutralization treatment are carried out.

(Porous Anodizing Treatment) As the electrolyte used for the porous anodizing treatment of the aluminum plate, any electrolyte can be used as long as it forms a porous oxide film, and is generally sulfuric acid, phosphoric acid, oxalic acid, chromium. An acid, a mixed acid thereof, sodium hydroxide, potassium hydroxide, a mixed solution thereof, an ammonium fluoride addition bath, or the like is used, and the electrolyte and the concentration thereof are appropriately determined depending on the kind of the electrolyte.
The treatment conditions of the porous anodic oxidation cannot be unconditionally specified because it varies depending on the electrolyte used, but generally the concentration of the electrolyte is 1 to 80 wt% solution, the liquid temperature is 5 to 80 ° C, and the current density is 1
Appropriate ranges are -80 A / dm ² , voltage 1-100 V, and electrolysis time 5 seconds-10 minutes.

The amount of the porous anodic oxide film is preferably 0.1 to 10 g / m ^2, but more preferably 1 to 6 g / m ² . The larger the thickness of the oxide film, the more the effects of the present invention can be exhibited.

Further, the porosity, the pore size cannot be specified because it changes variously depending on the electrolyte used, the treatment conditions, etc., but when anodizing treatment is performed using sulfuric acid, for example, about 10 ³ to 10 ¹¹ pieces / cm ²
And has a pore size of about 100 to 200Å in diameter.

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

The metal salt used is a water-soluble divalent or higher valent metal salt, and examples of the divalent or higher valent metal include calcium, magnesium, barium, zinc, nickel, cobalt, iron and copper. preferable. In addition, examples of the salt of the electrolyte constituting the present invention include salts of inorganic acids or organic carboxylic acids, and examples thereof include sulfates, nitrates, phosphoric acid, hydrochlorides, acetates, oxalates and the like.
However, when a monovalent so-called alkali metal salt such as Na, K or Li was used, the result was examined using a wear tester of a Suga abrasion tester, and as a result, it was found that the effect on improving the wear resistance of the surface was observed. I couldn't do it.

As a similar method, Japanese Patent Publication No. 54-11248 discloses a method of improving corrosion resistance by forming a cemented surface film by electrolytic treatment of calcium or magnesium salt. However, this method is different from the method of filling the pores with metal oxide or the like in the present invention, in which the cement coating layer of Ca salt or Mg salt is formed on the oxide film.

The purpose of the method according to the present invention is to improve the scratch resistance and abrasion resistance of the lithographic printing plate support. Particularly, the feature is that a porous anodic oxide film is used and the inside of this pore is
An oxide of a metal having a valency or higher, preferably magnesium, and / or
Or filling with hydroxide.

For this purpose, it is possible to add additives to the electrolyte, preferably the chelating agent EDTA (ethylenediaminetetraacetic acid disodium), citric acid, ammonium hydroxide, or the like. These additives are preferably added because they stabilize the metal ions in the electrolytic solution and stabilize the metal hydroxide filled in the oxide film fine pores to increase the filling effect.

Although the reason why the wear resistance is improved is not yet clear, the re-surface of the substrate manufactured by the method according to the present invention has a porous oxide film and magnesium oxide filled in pores which are voids of the film. It is considered that the coexistence of substances and the like has an effect on the wear resistance due to the hardness of the porous film and the lubricating action due to the action of magnesium hydroxide and the like.

This electrolytic sealing treatment is generally 1 to 10% of the above metal salt.
Using the solution, voltage 10-40V, current 0.1-0.6A / dm ² , temperature
It is carried out by treating at 20 to 35 ° C. for 3 to 15 minutes.
Under more severe conditions, hydroxides and the like will be deposited on the surface of the support, and if the conditions are not satisfied, the filling will be incomplete.

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

(Hydrophilic layer) On the support according to the present invention, JP-A-60-149491,
A hydrophilic layer as described in JP-A-60-232998 and JP-A-62-19494 can be provided.

It may also be treated with an aqueous solution of an alkali metal silicate (eg sodium silicate) as described in US Pat. No. 3,181,461 before or after providing this hydrophilic layer on the support according to the invention.

(Photosensitive layer) By providing a conventionally known photosensitive layer on the thus obtained support for lithographic printing plate, a photosensitive lithographic printing plate can be obtained. The lithographic printing plate thus obtained has excellent performance.

As the composition of the photosensitive layer, any composition can be used as long as the solubility or lubricity in a developer changes before and after exposure. The representative ones will be described below.

As (A) positive-working photosensitive diazo compound,
Benzoquinone-1,2-
Most preferred are the esters of diazidosulfonic acid chloride with polyhydroxyphenyl or the esters of naphthoquinone-1,2-diazidosulfonic acid chloride with pyrogallol-acetone resin. Other relatively suitable −
Examples of o-quinonediazide compounds include U.S. Pat. No. 3,046,12
There are esters of benzoquinone-1,2-diazide sulfonic acid chloride or naphthoquinone-1,2-diazide sulfonic acid chloride with phenol formaldehyde resins as described in US Pat. Nos. 0 and 3,188,210.

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

Further details of the photosensitive layer comprising the o-quinonediazide compound and its developer are described in US Pat. No. 4,259,434.

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

As the negative-working photosensitive diazo compound, US Pat.
No. 063,631 and No. 2,667,415, a diphenylamine-p-diazonium salt and a formaldehyde which are reaction products of a diazonium salt and an organic condensing agent containing a reactive carbonyl group such as aldol and acetal. Condensation product with (so-called photosensitive diazo resin)
Is preferably used. Other useful fused diazo compounds are U.S. Patent No. 3,679,419, British Patent No. 1,312,925, U.S. Pat.
It is disclosed in each specification of No. 1,312,926. These types of photosensitive diazo compounds are usually obtained in the form of water-soluble inorganic salts and can therefore be coated from aqueous solutions. Also, these water-soluble diazo compounds are reacted with an aromatic or aliphatic compound having one or more phenolic hydroxyl groups, sulfonic acid groups or both by the method disclosed in British Patent No. 1,280,885, The reaction product, a substantially water-insoluble photosensitive diazo resin, can also be used.

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

In addition, the diazo resin described in US Pat. No. 1,312,925 is also preferable.

Such a diazo resin is used together with a binder. A preferred binder is an organic polymer having an acid value of 10 to 200, and specific examples thereof include a copolymer containing acrylic acid, methacrylic acid, crotonic acid or maleic acid as an essential polymerization component, for example, U.S. Pat. Tertiary or quaternary with 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, acrylonitrile or methacrylonitrile, acrylic acid or methacrylic acid and optionally other copolymerizable monomers as described in US Pat. Original copolymer, JP-A-53-12
No. 0903, the terminal is a hydroxy group, and acrylic acid or methacrylic acid esterified with a group containing a dicarboxylic acid ester residue, acrylic acid or methacrylic acid, and optionally other Copolymer with a monomer capable of copolymerization, a monomer having an aromatic hydroxyl group at the terminal as described in JP-A-54-98614 (for example, N- (4-hydroxyphenyl) methacrylamide) Etc.), acrylic acid or methacrylic acid, and optionally a copolymer with at least one other copolymerizable monomer, an alkyl acrylate as described in JP-A-56-4144, or Included are copolymers of methacrylate, acrylonitrile or methacrylonitrile, and unsaturated carboxylic acids. Further, acidic polyvinyl alcohol derivatives and acidic cellulose derivatives are also useful.

(C) A composition containing a compound that causes dimerization upon irradiation with actinic rays. For example, polyvinyl cinnamate, polyvinylcinnamoylethyl ether, polycinnamoyloxyethyl acrylate, and copolymers thereof, polycinnamoyloxyethyl methacrylate and copolymers thereof, polyparavinylphenylcinnamate and copolymers thereof, Polyvinyl benzal acetophenone and its derivatives, polyvinyl cinnamylidene acetate and its derivatives, allyl acrylate prepolymer and its derivatives, derivatives of polyester resin consisting of paraphenylenediacrylic acid and polyhydric alcohol, for example, U.S. Pat. 20
And compounds such as those described in No. 8.

(D) A so-called copolymer composition which undergoes a polymerization reaction upon irradiation with actinic rays. For example, there is a composition comprising an addition-polymerizable unsaturated compound having two or more terminal ethylene groups described in US Pat. Nos. 2,760,863 and 3,060,023 and a photopolymerization initiator.

A resin, a sensitizer, a thermal polymerization inhibitor, a dye, a plasticizer and the like can be further added to the compound that dimerizes and the compound that undergoes a polymerization reaction upon irradiation with actinic rays as binders.

(E) Electrophotographic photosensitive layer.

The electrophotographic photosensitive layer is mainly composed of a photoconductive compound and a binder, but for the purpose of improving sensitivity, obtaining a desired photosensitive wavelength range, etc., known pigments, dyes, chemical sensitizers may be added as necessary. , Other additives, etc. can be used.
The photosensitive layer can be composed of a single layer or a plurality of layers having separate functions of charge generation and charge transport. The lithographic printing plate can be obtained by forming a toner image on the photosensitive layer by a known electrophotographic process and using this as a resist layer to decoat the non-image area. For example, JP-B-37-17162, JP-B-38-6961 and JP-A-56-107.
No. 246, No. 60-254142, No. 59-36259, No. 59-25
217, JP-A-56-146145, 62-194257, 57-1.
It is described in a large number of publications including 47656, 58-100862 and 57-161863, all of which can be preferably used.

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

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

In the case of (A) to (D), the coating amount of the photosensitive composition is generally about 0.1 to about 5.0 g / m ² , and is about 0.5.
˜3.0 g / m ² is more preferred.

The photosensitive lithographic printing plate thus obtained is subjected to imagewise exposure with a light source containing an actinic ray such as a carbon arc lamp, a xenon lamp, a mercury lamp, a Tung-ten lamp, a metal halide lamp and the like to develop 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 coating of aluminum with a metal salt oxide having a valence of 2 or more. The lithographic printing plate obtained by exposing and developing the photosensitive lithographic printing plate using is neither negative type nor positive type, and there is no contamination of the non-image area, and the image area and the non-image area are identified in the correction process. Is easy. In addition, there are no correction marks, therefore the printed matter does not stain and the scratches on the non-image area are less likely to occur and the abrasion resistance is excellent. Furthermore, the whiteness of the substrate is improved and plate inspection is excellent. Further, it is characterized in that the re-adhesion of the dissolved photosensitive composition during development is unlikely to occur and coloring of the non-image area due to a dye or the like is unlikely to occur.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples. In addition, "%" in the examples means "% by weight" unless otherwise specified.

[Examples 1 to 7] JIS A1050 aluminum sheet material was used as a polishing agent in a pumice-water suspension, and the surface was grained with a rotating nylon brush. At this time, the surface roughness (centerline average roughness) was 0.5 μ. After washing with water, a 10% aqueous sodium hydroxide solution was immersed in a solution warmed to 70 ° C., and etching was performed so that the amount of aluminum dissolved was 6 g / m ² . After washing with water, add 1 to 30% nitric acid solution
It was soaked for a minute for neutralization and washed thoroughly with water. Then 0.7%
Electrolytic surface roughening for 20 seconds in an aqueous nitric acid solution using a rectangular wave alternating waveform having a voltage at the anode of 13 V and a voltage at the cathode of 6 V (the power supply waveform described in the example of JP-A-52-77702). The surface was washed by immersing it in a solution of 20% sulfuric acid at 50 ° C. and then washing with water.

Then, using 20% sulfuric acid aqueous solution, anodization treatment was performed at 28 V and 1 A / dm ² at room temperature for 80 seconds so that the weight of the oxide film became 1.5 g / m ² . The pore size obtained at this time is 100Å,
The porosity was about 10 ¹⁰ cells / cm ² . Then, electrolytic sealing treatment was performed in a metal salt aqueous solution to prepare a support. The power supply waveform uses commercial AC, and the electrolysis voltage is 60 V or less, preferably 10 V.
The range of -40V is good, and was selected from within this range.

The support obtained in this manner measures the white density of the base plate, measures the abrasion resistance, and coats the photosensitive solution having the following composition so that the coating weight is 2.5 g / m ^2. did.

The photosensitive lithographic printing plate made in this way was passed through a transparent positive film in a vacuum baking frame at a distance of 1 m for 3K.
After exposure for 50 seconds with a W metal halide lamp, the SiO ₂ / Na ₂ O molar ratio of sodium silicate of 1.74
It was developed with a 5.26% aqueous solution (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 the anodizing treatment by the above-mentioned method and the electrolytic sealing treatment, the support was immersed in No. 3 sodium silicate 2.5% 10 ° C for 30 seconds, washed with water and dried. After coating and drying, a photosensitive layer was provided. The dry coating amount of the photosensitive layer is
It was 2.0 g / m ² .

The photosensitive lithographic printing plate made in this way is passed through a transparent negative film in a vacuum baking frame from a distance of 1 m for 3K.
After exposure for 50 seconds using a W metal halide lamp, development was performed with a developer having the following composition.

Developer The contamination of the non-image area was examined and shown in the table.

Comparative Example 1 A substrate that was not subjected to post-treatment after being subjected to anodizing treatment in the same manner as in Example (Comparative Example 1) and a substrate using a monovalent metal salt under the conditions of metal salt electrolytic sealing treatment ( Comparative Examples 2 and 3), substrates using DC for the power supply waveform (Comparative Example 4,
5), a substrate electrolyzed at high voltage (Comparative Example 6), a substrate subjected to hydration sealing by dipping in pure water at 100 ° C. for 2 minutes as a post-treatment method (Comparative Example 7), and ammonium borate 4 % Aqueous solution as an electrolytic solution, a substrate subjected to anodic electrolysis at 400 V (Comparative Example 8) is shown in the table as a comparative example.

The same photosensitive solution as in the example was used.

Note 1: The difference between the reflection optical density of the non-image area and the reflection optical density (ΔD) of the surface of the support immediately before coating the photosensitive layer is ○ …… 0.02 or less △ …… greater than 0.02 and 0.05 or less × …… greater than 0.05 Note 2: The wear degree of the non-image area after 350 reciprocating the non-image area with alumina abrasive paper using a wear tester made by Suga Test Machine (NUS-ISO-1 type) was ◎, ○, ○
The rank was divided into two stages of Δ, Δ, and ×.

◎ Not worn ○ Almost not worn ○ △ Slightly worn △ Slightly worn × Worn As you can see from the table, the metal salt electrolytic sealing is low voltage electrolysis,
That is, it can be manufactured at low cost, and the obtained quality has excellent features such as excellent wear resistance and resistance to contamination of non-image areas.

Regarding abrasion resistance, by using a magnesium salt in particular, it is significantly improved as compared with the comparative example, and by adding a chelating agent EDTA, or ammonium chloride, ammonium hydroxide, etc. as an additive, it is more remarkable. It was possible to obtain a great effect.

Claims (1)

[Claims] 1. A pore of a porous anodic oxide coating of an aluminum plate or an aluminum alloy plate is electrochemically formed by using an oxide and / or hydroxide of a metal having a valence of 2 or more by using an alternating current or an alternating direct current. A method for producing a support for a lithographic printing plate, which comprises filling.