JPS58108195A - Manufacture of supporter for lithographic plate - Google Patents

Abstract

PURPOSE:To obtain a supporter for lithographic plate, having excellent resistances to wearing and alkalies and free of staining to film, by subjecting a roughened aluminum plate to an anodic oxidation treatment in which a current having a positive electricity quantity/negative electricity quantity ratio =1 or less under a specific condition. CONSTITUTION:The surface of an aluminum plate is roughened in order to raise the adhesion between a humectant layer and the overlying photosensitive material layer, and then subjected to an anodic oxidation treatment under the condition that anodic oxidation is made with a current density of 5A/dm<2> or more in an electrolyte of 80g/1 or less of sulfuric acid in such a way that the ratio of the negative electricity quantity to the positive electricity quantity is 1 or less. The photo-sensitive lithographic plate is exposed to light source containing active light, e.g., carbon arc lamp, xenon lamp, etc., for development to obtain a lithographic plate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aluminium support for a lithographic printing plate.

A lithographic printing plate is a printing method that takes advantage of the fact that water and oil do not mix due to physical properties, and forms a print on one plane consisting of a water-receptive non-mg1 area and an ink-receptive 1&image area. If water is supplied to the printing plate to retain pressure water in the non-image area, and ink is further supplied to the printing plate, the ink will be retained only in the #J part, so the ink formed in this way This is a printing method in which the image is transferred to a plunket and then printed on paper.

Conventionally, “28 plates” were used as a photosensitive material for creating lithographic printing plates.
There is something called
= A photosensitive composition is coated on a plate, and when it is used, the photosensitive plate surface of the 28 plate is exposed to light in the desired image, and in the case of the positive type 28 plate, the exposed area is treated with water or an organic solvent. Alternatively, it can be dissolved with a mixture of these to form a non-image area, and the non-image area can maintain its property of not being dissolved in the above solution, and can be used as an umbrella area in the image. is dissolved in the above S solution to make non-aiii*
The exposed portion maintains its property of not being dissolved in the solution, and forms the printing plate surface as an image portion.

As mentioned above, the non-image area of the printing plate surface is the area from which the photosensitive composition layer has been removed, and is thus the fluoronium surface itself of the support. Therefore, when the surface of the aluminum support constitutes a non-image area, it is necessary to have the property of retaining water, so the property (water retaining property) is generally improved by roughening the surface. Additionally, aluminum is a relatively soft material with poor abrasion and corrosion resistance, so when used as a support for lithographic printing plates, it is usually roughened as described above and then anodized to form a harder film. It is being done to

When the photosensitive film of the 28th plate, which has been anodized and provided with a photosensitive layer, is exposed and developed, the substances contained in the photosensitive film irreversibly adsorb to the non-linear areas of the printing plate, resulting in non-linear It had the disadvantage of contaminating the area. This contamination becomes obvious when unnecessary line portions are corrected and erased. If this contamination becomes severe, the printing plate will become stained.

As a method to improve such shortcomings,
Ko1#jJ publication and JP-A-Sho! A method disclosed in Publication No. j-λtUOO has been proposed. however,
These methods reduce the aluminum ion concentration from lO to cozf
/l or anodized in a mixed electrolyte of sulfuric acid and phosphoric acid, so if aluminum sulfate with a high fa degree is used, scale is likely to occur, workability is poor, and the liquid Sludge (Al(OH) when processing
3) increases, and the waste liquid treatment load increases. In addition, in the case of a mixed electrolyte of sulfuric acid and phosphoric acid, it is very difficult to control the l1ij of both, resulting in poor manufacturing suitability. Furthermore, when anodized at a high current density, the film tends to become burnt.

Therefore, an object of the present invention is to provide a method for producing a support for a lithographic printing plate that has excellent abrasion resistance and alkali resistance and does not cause contamination of the anodic oxide film.

Another object of the present invention is to provide a method for producing a support for a lithographic printing plate that does not cause "burn" of aluminum oxide even when anodized at a high current density.

In order to solve the above-mentioned problems, the inventors of the present invention conducted intensive studies and found that by making a roughened aluminum plate have a value of jA/dnn'' or more in a sulfuric acid electrolyte of less than 0fi/l, It has been found that the conventional drawbacks can be solved.

The present invention will be explained in detail below.

The aluminum ζ plate used in the present invention includes pure aluminum and aluminum alloy plates. Various types of aluminum pentalloys can be used, such as aluminum alloys with metals such as silicon, iron, copper, manganese, magnesium, chromium, zinc, bismuth, and nickel. The aluminum plate may be in the form of a sheet or a strip, and may also be made of paper, plastic, or other metal as a lining, where fi is aluminum and lining is made of paper, plastic, or other metal. . The aluminum plate must not change in size when it is attached to a printing press as a printing plate.
For example, in the case of a plate made of aluminum alone, generally o
, lo, zm/m thickness is used.

Prior to the roughening treatment, the surface of the aluminum plate may be subjected to a degreasing treatment to remove rolling oil from the surface, if necessary.

The surface of the aluminum plate is roughened to improve water retention and adhesion to the layer of photosensitive material superimposed thereon. As the surface roughening method, a commonly used mechanical surface roughening method, chemical surface roughening method, electrochemical surface roughening method, or a combination thereof can be used.

Mechanical surface roughening methods include wire brush graining method, brush graining method, sand sillast method, and mail graining method. Electrochemical surface graining methods include nitric acid, t4t1k and its salts. A method of roughening the surface using direct current or alternating current in a dilute aqueous solution of is used. As a particularly preferred surface roughening method, a mechanical surface roughening method is advantageous from the viewpoint of mass production stability. Furthermore, a combination method of both methods disclosed in Japanese Patent Application Laid-Open No. WSJ-4J-01 can also be used.

The aluminum plate thus roughened is subjected to alkali etching treatment and neutralization treatment as necessary. When electrochemically roughened methods are used, phosphoric acid, sulfuric acid,
If necessary, it is hardened by a process of desmatting using chromic acid or the like.

The aluminum surface treated in this way is anodized. When anodic oxidation is performed with sulfuric acid 111IFI1 higher than 10171, components in the photosensitive layer tend to remain on the anodic oxide film, and therefore contamination of non-linear areas tends to occur after exposure and development. Furthermore, alkali resistance and abrasion resistance are also reduced. However, when anodizing is carried out in sulfur #ItIIIf with a concentration of got/l or more, such drawbacks disappear. Electrolyte S[
In order to reduce contamination of the anodic saponification film, lower temperatures are preferable, but because the lI[ of electrolytic silver sulfuric acid is low, no contamination of the film occurs even if anodic oxidation is performed at a higher temperature. The preferred temperature ranges from JO to 70°C, more preferably ri3
The range is from 0 to '''C.The lower the current density, the more "burning" of the aluminum oxide will occur, but considering commercial electrolytic conditions, a very high current density is required. In order to effectively utilize the features of the present invention, the current density is preferably from j people/dm'' to QOA/dm''. Most preferably lOA/dm ~30A/
A current density of d m' is chosen. Further, the electrolysis time is 1 to 720 seconds, preferably 10-. It is 10 seconds. The aluminum oxide obtained in this way is 1.2~
J, 197m.

Direct current electrolysis and alternating current electrolysis are known methods for performing anodic oxidation under such electrolytic conditions, but when the known electrolysis methods are used, "scorching" of the oxide film occurs. Therefore, the inventors of the present invention passed a positive current until just before the film started to "burn," and then passed a negative current at the next moment to eliminate the positive charge in the film (increasing the negative current would destroy the film. )
We succeeded in forming an anodic fermentation film that does not cause "scorching". The current waveform used is preferably a rectangular wave (a) and a trapezoidal wave (b) as shown in FIG. 7, but a sine wave may also be used. The ratio of the positive 1 quantity Q+ and the negative quantity Q- is Q, -/Q+=
A range of 0, ./-0,2 is preferable. More preferably, Q'/Q+≦t/J. The ratio of positive current time Ta and negative current time Tb (1) is Tb/Ta=o, oi ~O0j
The range of 'l' b /Ta is preferable, and more preferably 'l' b /Ta
=0.04A to 0.3. The frequency of this waveform is 0.
/, /koOHz is preferable, but more preferably! ~40
1 (z). If the frequency is too low, the time for positive and negative conversion will be too long, making it easy to cause burns. If the frequency is too high, power consumption will increase, which is unfavorable in terms of production.

The film anodized in this way is KOHj00f%Z
nOIog, and water! 7009 (D) The alkali resistance can be examined by immersing it in arc and measuring the time it takes for it to turn black.

The anodized aluminum plate is also US special FF1G
J, 7/44,044 and H,i, iti.

61, by a method such as immersion in a water bath solution of an alkali metal silicate, for example, sodium silicate; A subbing layer of hydrophilic cellulose (such as carboxymethylcellulose) containing a water-soluble metal salt (such as vinegar tIIi!lead) may also be provided, as described in the U-coro specification.

On the lithographic printing plate support obtained in this way,
28th edition (Pre-1iensitized plate
A photosensitive lithographic printing plate can be obtained by providing a conventionally known photosensitive layer as a photosensitive layer (abbreviation for ``(abbreviation)''), and the lithographic printing plate obtained by plate-making processing this plate has excellent performance. ing.

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.

■ As a positive-acting photosensitive diazo compound,
The ester of benzoquinone-1,λ-diazide sulfoyes chloride and polyhydroxyphenyl described in 1c3-Color Kou No. 03 or Hanaphthoquinone/, J
Most preferred are esters of -diazide sulfoydi chloride and pyrogallol-acetone resin. Other relatively suitable 01 chino/diazide compounds include:
US#! No. J, No. 0@4.720 and No. 1. l
I1. Jio 7-/J-diazide sulfonic acid chloride or naphthoquinone-1, cordiazide sulfonic acid chloride and phenol formaldehyde resin.

The O-quinonediazide compound alone constitutes the photosensitive layer, but a resin soluble in alkaline water is used as a binder together with this resin.

Examples of resins soluble in alkaline water include novolak resins having this property, such as phenol formaldehyde resin, Vsol formaldehyde resin, and G-sol formaldehyde resin.
"-butylphenol-formaldehyde resin, phenol-modified xylene resin, phenol-modified medium silane/mesitylene resin, etc.Other useful alkaline water-soluble resins include polyhydroxystyrene, polynorogenated hydrocystyrenated (meth)acrylic acid, and others. Mention may be made of copolymers with vinyl compounds.

■A photosensitive composition consisting of diazo #R resin and a binder.

As a negative-acting photosensitive diazo compound, US Pat.
Diphenylamine, which is a reaction product with an organic condensing agent containing a diazoniurbonyl group, disclosed in the specifications of No. D43.4J1 and No. A47゜≠lj.
A condensation product of p-diazonium salt and formaldehyde (photosensitive diazo resin) is preferably used. Other useful condensed diazo compounds are
No., Kota 4A! J Coco issue, same 2-μ! It is disclosed in various publications such as No. 3 Co. No. 3. These types of photosensitive diazo compounds are usually obtained in the form of water-soluble inorganic salts and can therefore be coated from aqueous solution. Furthermore, these water-soluble diazo compounds can be converted into aromatic or aliphatic compounds having seven or more phenolic hydroxyl groups, sulfonic acid groups, or both by the method disclosed in Japanese Patent Publication No. 7-//47. It is also possible to react and use a substantially water-insoluble photosensitive diazo resin which is the reaction product.

Also, British time vIf 1st. Also preferred are the diazo resins described in the specification of J/Co, Taco No. J.

■ A composition containing a compound that causes diminution upon irradiation with actinic rays. For example, polyvinyl cinnamate, polyvinyl cinnamoyl ethyl ether, polyethyl cinnamate acrylate and its copolymers, polyethyl cinnamate methacrylate and its copolymers, poly/(rabinylphenyl 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 described in US Pat. OJO,-
There are compounds with 〇 listed in the specification.

(2) A so-called photopolymerizable composition that causes a polymerization reaction when irradiated with active light. For example, U.S. Patent No. 2,71.0.143
No. 2 and No. J, D40.023 Specification Tatami.
There is a composition comprising an addition polymerizable unsaturated compound having one or more terminal ethylene groups and a photopolymerization initiator.

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

The photosensitive composition as described above is usually applied as a solution of water, a 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 1.
01/m" is appropriate, and about 0.j to about 3.097m"
is more preferable.

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

Hereinafter, the present invention will be explained in more detail based on examples. However, the present invention is not limited to these Examples. In addition, "excellent" in the examples indicates "-" by weight.

Example I The surface of a JI8toto aluminum sheet was roughened using a rotating nylon brush using a water suspension as a polishing agent. The surface roughness (average center roughness) is 0.4μ. After washing with water, immerse lOs caustic soda aqueous solution in CK solution at 70°C to determine the amount of dissolved aluminum on the surface of the book.
Alkaline etching was performed to obtain the desired results. After washing with water, it was immersed in 0.7 qIk nitric acid solution at room temperature for 1 minute, and using a square wave alternating waveform of anode voltage JJLtl & polar voltage lλ■ (Japanese Patent Laid-Open No. 7770λ) Electrolytic waveform shown in the example) / θ coulomb / d
Electrolytic surface roughening is performed with an anode electricity amount of m'', and JO%'
The surface was washed by immersing it in 1l of jO°C bath solution and then washing with water. In this way, the substrate CI) was prepared.

This substrate (1) was placed in a 7th layer of sulfuric acid bath solution.
Using the rectangular wave shown in Figure <a>, the anodic oxide film is
, 097 m to prepare a substrate [A]. The current waveform used at this time had a frequency of 1 OHZ and T
b/Ta=//4;h).

The substrate (1) was anodized using direct current under the same conditions to prepare a substrate CB) with a film thickness of 097 m''.Furthermore, the substrate CI) was anodized using cool/l sulfuric acid. Prepare the substrate [C] by converting it into a positive 1F!I!, #I using a direct current under warm conditions of 3j 0C/JA/dm in a melting frame to obtain a coating amount of J, 01/m''. did.

Next, apply the following composition (1) so that the coating weight after drying is 2゜tyim.
``Tonaru!'') IC was provided on the substrate (A) (BJ (C).

The photosensitive lithographic printing plate thus prepared was exposed for 30 seconds through a transparent positive film in a vacuum printing frame using a JKW Metalnoride lamp from a distance of 1 WIO, and then exposed to SiQ□/NaO. The molar ratio is /
, 7! of sodium silicate! , 4, and developed with a slow ice aqueous solution pH 1λ, 7).

The results are shown on the next page.The degree of contamination in the non-image area after development was visually classified into excellent, good, fair, and poor. 1ft-
KOHjoof, Zn0rOfl, water! A solution of oat was dropped onto the /31d film at room temperature, and the time for blackening was measured to examine alkali resistance. Furthermore, using these printing plates, the degree of staining was visually determined when printing was performed with an offset printing machine.

It is clearly seen that the method of the present invention is effective.

[Brief explanation of the drawing]

Figure 1 is a flow waveform diagram used in the present invention. (a) Square wave, (b) trapezoidal wave. Patent ratio - People Fuji Photo Film Co., Ltd. Figure 1

Claims (1)

[Claims] When carrying out positive conversion of a ram plate to roughened aluminum in a sulfuric acid electrolyte of tOf/l or less at a current density of j A / d m * or more, K, the ratio of negative to positive electricity. 1. A method for producing a support for a lithographic printing plate, characterized in that a current of less than 7 is applied.