JP2000075504A - Photosensitive planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive planographic printing plate sufficiently improved in the erasability of a photosensitive layer in a correcting process. SOLUTION: The photosensitive planographic printing plate is formed by providing the photosensitive layer on a supporting body having an anodic oxidation coating film formed on an aluminum or its alloy plate. The photosensitive layer entering into a micropore of the anodic oxidation coating film is limited in a range of 300 nm starting from the boundary between the anodic oxidation coating film and the photosensitive layer in the supporting body direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a photosensitive lithographic printing plate. More specifically, the present invention relates to a photosensitive lithographic printing plate capable of reducing an erasing time when erasing a photosensitive layer using a positive erasing liquid.

[0002]

2. Description of the Related Art A lithographic printing plate is a photosensitive lithographic printing plate obtained by coating a photosensitive composition in a thin layer on an aluminum plate or an aluminum alloy plate (hereinafter collectively referred to as "aluminum plate"). It is obtained by post-development. The aluminum plate is usually subjected to a surface roughening treatment such as a mechanical method such as a brush grain method or a ball grain method, an electrochemical method such as an electrolytic grain method, or a method combining the both, and the surface thereof has a satin finish. After that, the substrate is etched with an aqueous solution of an acid or an alkali, and further subjected to an anodic oxidation treatment, and if desired, subjected to a hydrophilic treatment to form a support for a lithographic printing plate. And a photosensitive lithographic printing plate (so-called PS plate). As the photosensitive composition, those comprising an o-quinonediazide compound are widely used, and such a photosensitive substance is used alone or mixed with an alkali-soluble resin such as a novolak-type phenol resin or a cresol resin, an acrylic resin, a polyurethane resin, or the like. It is painted on a special holiday. When a support having a hydrophilic surface is used, the exposed portion is easily removed with an alkali developing solution because the o-quinonediazide compound is decomposed and changes to alkali-soluble,
The hydrophilic surface of the support is exposed, this area receiving water and repelling the ink. On the other hand, unexposed portions remaining as images are lipophilic and accept ink. This PS version is usually
The lithographic printing plate is subjected to image exposure, development, correction, and gumming steps, and is mounted on a printing press for printing.

In the process of making a photosensitive lithographic printing plate, generally, a step of providing a photosensitive layer on an anodized aluminum plate, a step of exposing the photosensitive layer through a transparent original film, and a step of developing an exposed portion of the photosensitive layer are performed. The developing step of dissolving and removing with a liquid, after the developing step, remains on the anodized aluminum plate as a support due to insufficient exposure due to the edge portion of the original film or dust attached thereto, There is a correction step of erasing the photosensitive layer that should be removed with an erasing liquid. In this correction process, the length of time required for the photosensitive layer to be erased to be dissolved and erased with the erasing liquid is called erasability. If erased in a short time, the erasability is excellent, and it takes a long time to erase. Is described as poor erasability. If the erasability can be improved, the repair work can be completed in a short time, leading to an increase in work efficiency. In general, as a method for improving the erasability in the above-mentioned repairing step, conventionally, treatment of an anodic oxide film on a support with nitrite (JP-A-4-10989)
JP-A-8-1061), treatment with an inclusion compound
No. 57), a method of treating with a metal salt of an aliphatic monocarboxylic acid (Japanese Patent Publication No. 7-90669) and the like.

However, in these methods,
The level of improvement of the erasability is not sufficient, and the erasability is greatly affected by subtle variations in the processing conditions of the support.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photosensitive lithographic printing plate in which the erasability of the photosensitive layer in the repair step is sufficiently improved.

[0006]

Means for Solving the Problems The present inventors have observed the state of adhesion of the photosensitive composition near the interface between the anodic oxide film and the photosensitive layer, and examined the correlation with the erasability of the photosensitive layer. It has been found that when the photosensitive composition is present only in the specific region of the interface, extremely good erasability is obtained, and the present invention has been completed. That is, the object of the present invention is to provide a photosensitive lithographic printing plate in which a photosensitive layer is provided on a support in which an anodic oxide film is formed on an aluminum or alloy plate of the present invention. The photosensitive lithographic printing plate is characterized in that the photosensitive layer is limited to a range of 300 nm from the interface between the anodized film and the photosensitive layer in the direction of the support. Here, the interface means the boundary between the uppermost portion of the anodic oxide film and the photosensitive layer, and the wall inside the micropore is not included in the interface. Further, a similar object is to provide a photosensitive lithographic printing plate of the present invention in which a photosensitive layer is provided on a support having an anodic oxide film formed on an aluminum or alloy plate thereof, by using Auger electron spectroscopy. The element ratio _{C / Al} of the carbon element and the aluminum element due to the photosensitive layer, which is obtained by the point analysis by the analyzer and calculated from the following formula (I), is closer to the support side from the interface between the anodic oxide film and the photosensitive layer. It is also achieved by a photosensitive lithographic printing plate characterized by being at most 0.3 at a distance of more than 300 nm. Element ratio _{C / Al = (I c /} S c) / (I Al / S Al) ··· (I) I c: carbon (KLL) Auger electron differential peak-to-peak intensity I _Al: Aluminum (KLL Auger electron differential peak-to
-Peak intensity S _c : Relative sensitivity coefficient of carbon (KLL) Auger electrons S _Al : Relative sensitivity coefficient of aluminum (KLL) Auger electrons

When the photosensitive material satisfies the above conditions, the photosensitive lithographic printing plate shows excellent erasability regardless of the processing conditions of the support.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. [Aluminum support] The aluminum support used in the present invention is a dimensionally stable metal containing aluminum as a main component, and is made of aluminum or an aluminum alloy. In addition to a pure aluminum plate, it is selected from an alloy plate containing aluminum as a main component and containing a trace amount of a different element, or a plastic film or paper on which aluminum (alloy) is laminated or evaporated. Furthermore, Japanese Patent Publication No. 48-18
A composite sheet in which an aluminum sheet is bonded to a polyethylene terephthalate film as described in Japanese Patent No. 327 may be used.

In the following description, the above-mentioned substrates made of aluminum or aluminum alloy are collectively used as aluminum substrates. The foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel and titanium, and the content of the foreign elements in the alloy is 10% by weight or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to produce due to refining technology, and therefore may contain a slightly different element. Thus, the aluminum plate applied to the present invention, the composition is not specified, conventionally known and used materials, such as JIS A 1050, JIS A 1100, JISA 3103, JIS A
3005 can be used as appropriate. The thickness of the aluminum substrate used in the present invention is about 0.1
mm to about 0.6 mm. This thickness can be appropriately changed according to the size of the printing press, the size of the printing plate, and the user's request. The aluminum substrate is appropriately subjected to a substrate surface treatment described below.

[Graining] The graining method includes mechanical graining, chemical etching and electrolytic graining as disclosed in JP-A-56-28893. Further, an electrochemical graining method for electrochemically graining in a hydrochloric acid or nitric acid electrolyte, a wire brush graining method for scratching the aluminum surface with a metal wire, and graining the aluminum surface with a polishing ball and an abrasive. A mechanical graining method such as a ball graining method or a brush graining method for graining the surface with a nylon brush and an abrasive can be used, and the above graining methods can be used alone or in combination. Among them, a method for producing a surface roughness usefully used in the present invention is an electrochemical method of chemically graining in a hydrochloric acid or nitric acid electrolyte, and a suitable current density is 50 C / dm ^{2 to} 400 C /.
dm ² . More specifically, 0.1 to 50
% Hydrochloric acid or nitric acid at a temperature of 20 to 90%
° C, time 1 second to 30 minutes, current density 100 C / dm ² -40
The electrolysis is preferably performed under the condition of 0 C / dm ² . By such a treatment, a rough surface with Ra = 0.3 to 0.8 μm is obtained.

The grained aluminum substrate is chemically etched with an acid or an alkali. When an acid is used as an etching agent, it takes time to destroy a fine structure, which is disadvantageous in industrially applying the present invention. However, it can be improved by using an alkali as an etching agent. Alkali agents suitably used in the present invention are caustic soda, sodium carbonate,
Sodium aluminate, sodium metasilicate, sodium phosphate,
Preferred ranges of concentration and temperature are 1 to 50% and 20 to 100 ° C., respectively, using potassium hydroxide, lithium hydroxide or the like.
It is preferable that the conditions are such that the amount of aluminum dissolved is 5 to 20 g / m ² .

After the etching, pickling is performed to remove dirt (smut) remaining on the surface. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borofluoric acid and the like are used. In particular, as a method for removing the smut after the electrochemical surface-roughening treatment, it is preferable to use a method of removing 50 to 50 as described in JP-A-53-12739.
A method of contacting with sulfuric acid of 15 to 65% by weight at a temperature of 90 ° C. and a method of alkali etching described in Japanese Patent Publication No. 48-28123 are exemplified.

[Anodizing treatment] The aluminum substrate treated as described above is further subjected to anodizing treatment. The anodizing treatment can be performed by a method conventionally performed in this field. Specifically, sulfuric acid, phosphoric acid,
Chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc. or a combination of two or more of these can be used to form an anodized film on the aluminum substrate surface by passing a direct or alternating current through the aluminum substrate in an aqueous or non-aqueous solution. it can. Since the conditions of the anodizing treatment vary depending on the electrolytic solution to be used, they cannot be unconditionally determined.
Suitable ranges are 70 ° C., current density of 0.5 to 60 amps / dm ² , voltage of 1 to 100 V, and electrolysis time of 10 to 100 seconds. In the present invention, the anodic oxide film has a thickness of 1 to 10 g /
Preferably, it is m ² , and if it is 1 g / m ² or less, the plate is easily damaged, and if it exceeds 10 g / m ² , a large amount of power is required for production, which is economically disadvantageous. Preferably, it is 1.5 to 7 g / m ² . More preferably, 2
５5 g / m ² .

The aluminum support thus obtained may be subjected to a surface treatment, if necessary, after the anodizing treatment and before the treatment for forming the positive photosensitive layer.
For example, a compound having a sulfonic acid group, a compound containing fluorine and titanium, a compound containing fluorine and zirconium,
Using compounds containing phosphorus and fluorine, metal acetates such as cobalt and nickel, metal fluorides, inorganic carbonates, alkali metal silicates, inorganic sulfates, amines, sugars, amino acid compounds, polyvinylphosphonic acid, etc. , Immersion, hot water sealing, water vapor sealing and the like.

Another example is a process of providing an organic undercoat layer on the surface of an aluminum support. Examples of the organic compound used in the organic undercoat layer include carboxymethyl cellulose, dextrin, gum arabic, phosphonic acids having an amino group such as 2-aminoethylphosphonic acid, phenylphosphonic acid which may have a substituent, and naphthyl. Organic phosphonic acids such as phosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid, and organic acids such as phenylphosphoric acid, naphthylphosphoric acid, alkylphosphoric acid and glycerophosphoric acid which may have a substituent. Phosphoric acid, phenylphosphinic acid which may have a substituent, naphthylphosphinic acid, organic phosphinic acids such as alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine,
And a hydrochloride of an amine having a hydroxyl group such as a hydrochloride of triethanolamine, and a sulfonic acid such as tamol, and a mixture of two or more thereof.

This organic undercoat layer can be provided by the following method. That is, a method in which a solution obtained by dissolving the above organic compound in water or an organic solvent such as methanol, ethanol, or methyl ethyl ketone or a mixed solvent thereof is applied to an aluminum plate and provided by drying, water or methanol, ethanol, methyl ethyl ketone, or the like. In an organic solvent or a mixed solvent thereof, a solution obtained by dissolving the above organic compound, by immersing an aluminum plate to adsorb the organic compound, and then washing with water or the like,
This is a method of drying to provide an organic undercoat layer. In the former method, a solution of the above organic compound having a concentration of 0.005 to 10% by weight can be applied by various methods. For example, any method such as bar coater coating, spin coating, spray coating, and curtain coating may be used. In the latter method, the concentration of the solution is 0.01 to 20% by weight, preferably 0.05% by weight.
-5% by weight, the immersion temperature is 20-90 ° C., preferably 25-50 ° C., and the immersion time is 0.1 second-20 minutes,
Preferably it is 2 seconds to 1 minute. The pH of the solution used for this can be adjusted with a basic substance such as ammonia, triethylamine, potassium hydroxide or the like, or an acidic substance such as hydrochloric acid or phosphoric acid.
Further, a yellow dye may be added for improving the tone reproducibility of the photosensitive lithographic printing plate. The coating amount of the organic undercoat layer after drying is suitably from ² to 200 mg / m ² , and preferably from 5 to 100 mg / m ² .

A photosensitive lithographic printing plate is obtained by providing a photosensitive layer on the support treated as described above. This photosensitive layer can be formed by a conventionally known method of dissolving the photosensitive composition in a solvent and coating the solution on a support. Hereinafter, preferred embodiments of the photosensitive layer will be described.

The phenol / p-cresol-formaldehyde resin having a weight average molecular weight of 7000 or more is preferable as the binder used in the positive photosensitive layer of the positive photosensitive lithographic printing plate to be used in the present invention. The method of synthesizing this resin is as follows. That is, in order to synthesize the present resin, the total of phenol and p-cresol is 1
It is preferred to use 0.7 to 0.9 moles of aldehydes per mole. When the amount of the aldehyde is 0.7 mol or less, a sufficient molecular weight cannot be obtained. When the amount of the aldehyde exceeds 0.9 mol, a gel is easily formed, which is not preferable. The molar ratio of phenol / p-cresol is preferably in the range of 8/2 to 4/6, and most preferably 5/5. If the amount of phenol is more than 8/2, the photosensitive layer tends to have a lower development tolerance. If the amount is less than 4/6, the sensitivity of the photosensitive layer tends to be lower. As the acidic catalyst used for the condensation reaction, the above various acids can be used, and among them, oxalic acid is preferable. A phenol / p-cresol-formaldehyde resin having a weight average molecular weight of 7000 or more is 1
It is preferable that the compound has three or more aromatic groups in the molecule.

In general, a novolak resin other than a phenol / p-cresol-aldehyde resin can be used as a binder component in the positive photosensitive layer, if necessary. In the positive photosensitive layer, a resin other than the phenol / p-cresol-aldehyde resin can be used as a binder component, if necessary. As resins other than this novolak resin, phenol-modified xylene resin,
Polyhydroxystyrene, polyhalogenated hydroxystyrene, an acrylic resin having a phenolic hydroxyl group as disclosed in JP-A-51-34711,
Examples thereof include alkali-soluble resins such as an acrylic resin having a sulfonamide group and a urethane resin as disclosed in JP-A-2-866. These resins are
Those having a weight average molecular weight of 500 to 100,000 are preferred. In the positive photosensitive layer of the positive photosensitive lithographic printing plate of the embodiment of the present invention, resins other than the above various novolak resins, alone or in combination of plural kinds, may be used in combination with the novolak resin. . In this case, the binder component ratio is at least phenol /
It is necessary that the resin other than the p-cresol aldehyde resin is less than 90% by weight of the binder component and the phenol / p-cresol aldehyde resin is 10% by weight or more of the binder component, and preferably phenol / p-cresol aldehyde resin. The resin other than the aldehyde resin is less than 50% by weight of the binder component, and the phenol / p-cresol aldehyde resin is 50% by weight or more of the binder component, and more preferably the resin other than the phenol / p-cresol aldehyde resin is 30% by weight of binder component
Less than 70% by weight of the binder component of the phenol / p-cresol aldehyde resin. In the positive photosensitive lithographic printing plate of the present invention, the content of the binder component resin is preferably not more than 80% by weight of all the components constituting the positive photosensitive layer. , Preferably 30-75% by weight, more preferably 5% by weight.
0 to 65% by weight. This range is preferable from the viewpoint of developability and marking resistance.

In general, the positive photosensitive layer of a positive photosensitive lithographic printing plate is composed of a photosensitive composition containing a positive working photosensitive compound, an alkali-soluble and water-insoluble resin as a binder, an image coloring agent and the like. You. In the photosensitive composition constituting the positive photosensitive layer of the positive photosensitive lithographic printing plate of the present invention, components other than the binder resin such as a photosensitive compound and an image coloring agent are conventionally known. Various photosensitive compounds, various image coloring agents, and the like can be appropriately selected and employed.

As the positive working type photosensitive compound, an o-naphthoquinonediazide compound or the like is generally used. JP-A-47-5303, JP-A-48-63802, and JP-A-48-63802.
No. 63803, No. 48-96575, No. 49-387
No. 01, No. 48-13354, Japanese Patent Publication No. 41-1122
2, No. 45-9610, No. 49-17481, U.S. Pat. Nos. 2,797,213 and 3,45.
No. 4,400, No. 3,544,323, No. 3,5
No. 73,917, No. 3,674,495, No. 3,
785,825, British Patent No. 1,227,602,
Nos. 1,251,345 and 1,267,005
No. 1,329,888, No. 1,330,93
No. 2, German Patent No. 854,890, etc., various o-naphthoquinonediazide compounds are described. The proportion of the photosensitive compound in the photosensitive composition constituting the positive photosensitive layer is suitably from 10 to 80% by weight, preferably from 15 to 50% by weight, more preferably 20% by weight.
~ 35% by weight.

As the image colorant, a blue dye or the like whose color tone is changed by an acid is generally used. Specific examples of the blue dye include a cation having a basic dye skeleton described in JP-A-5-313359 and a carbon number having 1 to 3 hydroxyl groups having a sulfonic acid group as a sole exchange group. Basic dyes comprising salts with 10 or more organic anions are exemplified. The amount of the blue dye added is suitably 0.2 to 5% by weight of the total photosensitive composition, preferably 0.2 to 5% by weight.
The content is 5 to 4% by weight, more preferably 0.3 to 3% by weight. If the addition amount is less than 0.2% by weight, the plate inspection after development is poor, and if it is more than 5% by weight, a bluish color remains in the non-image area after development.

As the image coloring agent, other dyes can be used in addition to the above-mentioned blue dyes. Suitable dyes, including salt-forming organic dyes, include oil-soluble dyes and basic dyes. Specifically, Oil Green BG, Oil Blue BOS, Oil Blue # 603 (or more, manufactured by Orient Chemical Industry Co., Ltd.), Victoria Pure Blue BOH, Victoria Pure Blue NAPS, Ethyl Violet 6HNAPS (above, Hodogaya Chemical Co., Ltd. )
), Rhodamine B (C145170B), malachite green (C142000), methylene blue (C15
2015).

Compounds which generate an acid which changes the color tone by interacting with the above-mentioned blue dyes,
No. 0-36209 (U.S. Pat. No. 3,969,118)
O-naphthoquinonediazide-4-sulfonic acid halogenide described in JP-A-53-36223 (U.S. Pat. No. 4,160,671).
-Pyrone or trihalomethyltricidin, JP-A-55-6
Various o-naphthoquinonediazide compounds described in JP-A-2444 (U.S. Pat. No. 2,038,801);
JP-A-5-77742 (U.S. Pat. No. 4,279,982)
2-trihalomethyl-5-aryl-1,
A 3,4-oxadiazole compound or the like can be added.

In the photosensitive composition constituting the positive photosensitive layer in the present invention, it is preferable to add cyclic acid anhydrides, phenols, and organic acids in order to increase the sensitivity. US Pat. No. 4,115,12 discloses cyclic acid anhydrides.
No. 8, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride as described in US Pat.
3,6-Endoxy-Δ ⁴ -tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like. As phenols, bisphenol A, p-nitrophenol,
p-ethoxyphenol, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 2,
4,4'-trihydroxybenzophenone, 4,4
4 "-trihydroxy-triphenylmethane, 4,
4 ', 3 ", 4"-tetrahydroxy-3,5,3',
5'-tetramethyltriphenylmethane and the like.

As the organic acids, JP-A-60-8894
2, sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, phosphinic acids, phosphoric esters, carboxylic acids, and the like described in JP-A No. 2-96755 and JP-A-2-96755. p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenylphosphonic acid,
Phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 1,4-cyclohexene-2,2- Examples thereof include dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, and ascorbic acid. The above cyclic acid anhydrides,
The proportion of phenols and organic acids in the photosensitive composition is preferably from 0.05 to 15% by weight, more preferably from 0.1 to 5% by weight.

In the photosensitive composition constituting the positive photosensitive layer in the present invention, JP-A-62-251740 and JP-A-6-251740 are used in order to widen the development latitude.
It is possible to add a nonionic surfactant as described in JP-A-68355 and an amphoteric surfactant as described in JP-A-59-121044 and JP-A-4-13149. it can. Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan triolate, stearic acid monoglyceride, polyoxyethylene sorbitan monooleate, polyoxyethylene nonyl phenyl ether, and the like. Specific examples of the activator include alkyl di (aminoethyl) glycine, alkyl polyaminoethyl glycine hydrochloride, Ammogen K (trade name, manufactured by Dai-ichi Kogyo Co., Ltd., N-tetradecyl-N, N-betaine type), 2- Alkyl-N-carboxyethyl-N
-Hydroxyethylimidazolinium betaine, Levon 15 (trade name, manufactured by Sanyo Chemical Co., Ltd., alkylimidazoline type) and the like. The nonionic surfactant,
The proportion of the amphoteric surfactant in the photosensitive composition is 0.0
It is preferably from 5 to 15% by weight, more preferably from 0.1 to 5% by weight.
% By weight.

As a solvent for dissolving the photosensitive composition, γ
-Butyrolactone, ethylene dichloride, cyclohexanone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, 1-methoxy-2
-Propanol, 1-methoxy-2-propyl acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate,
Examples include dimethyl sulfoxide, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, tetrahydrofurfuryl alcohol, acetone, diacetone alcohol, methanol, ethanol, isopropanol, and diethylene glycol dimethyl ether. These solvents are used alone or as a mixture. The concentration (solid content) of the solution in which the photosensitive composition is dissolved in the solvent is suitably 2 to 50% by weight. Further, the coating amount is 0.5 to 2.
5 g / m ² is preferred. If the amount is less than 0.5 g / m ² , printing durability deteriorates, and if it is more than 2.5 g / m ² , tone reproducibility deteriorates.

To the photosensitive composition, a surfactant for improving coating properties, for example, a fluorine-based surfactant as described in JP-A-62-170950 can be added. . The amount added is 0.01% of the total photosensitive composition.
To 1% by weight, more preferably 0.05 to
0.5% by weight.

The surface of the photosensitive layer provided as described above is preferably matted in order to shorten the time of evacuation during contact exposure using a vacuum firing frame and prevent blurring. Specifically, a method of providing a mat layer as described in JP-A-50-125805, JP-B-57-6582 and JP-B-61-28986 is described in JP-B-62-62337. And a method of thermally fusing such a solid powder.

In the present invention, in the above-described photosensitive lithographic printing plate, (1) the photosensitive layer penetrating into the micropores of the anodic oxide film has a range from the interface between the anodic oxide film and the photosensitive layer to 300 nm in the direction of the support. Or (2) point analysis of the fractured surface of the anodic oxide film with an Auger electron spectrometer, which is caused by the photosensitive layer calculated from the following formula (I). That the element ratio _{C / Al} between the carbon element and the aluminum element is 0.3 or less, preferably 0.2 or less, at a position more than 300 nm away from the interface between the anodic oxide film and the photosensitive layer toward the support from the interface. To be satisfied. Element ratio _{C / Al = (I c /} S c) / (I Al / S Al) ··· (I) I c: carbon (KLL) Auger electron differential peak-to-peak intensity I _Al: Aluminum (KLL Auger electron differential peak-to
-Peak intensity S _c : Relative sensitivity coefficient of carbon (KLL) Auger electrons S _Al : Relative sensitivity coefficient of aluminum (KLL) Auger electrons

The conditions (1) and (2) define the allowable amount of the photosensitive composition that can be present at the interface in order to develop good erasability. Therefore, as long as these requirements are satisfied, the photosensitive lithographic printing plate shows excellent erasability regardless of the processing method of the support. In the above (1), with respect to an arbitrary cross section of the photosensitive lithographic printing plate, a range from the interface between the anodized film and the photosensitive layer to, for example, 400 nm on the support side is observed using an electron microscope. Check the area that is inside. On the other hand, in the above (2), the aluminum support on which the anodic oxide film was formed was bent at almost 180 ° to form a fractured surface, which was mounted on an Auger electron spectrometer, and an electron beam was applied to the fractured surface. Then, the differential peak intensity of the carbon element and the differential peak intensity of the aluminum element caused by the photosensitive layer are measured, the respective values are normalized by a relative sensitivity coefficient, and the element ratio _{C / Al} is determined from the ratio. This operation is performed by sequentially changing the position from the interface between the anodized film and the photosensitive layer toward the support, and the element ratio _{C / Al} is determined for each measurement position. For Auger electron spectroscopy, see HANDB0
0K OF AUGER ELECTRON SPECTROSCOPY ”(Perkin-Elme
r Corporation Physical Electronics Division)
Can be referred to.

According to the present invention, the photosensitive lithographic printing plate having a positive photosensitive layer prepared as described above can be subjected to image exposure and development by a conventionally known method to make a plate. Hereinafter, preferred embodiments of the developing step will be described.
Light sources used for image exposure include a carbon arc lamp, a mercury lamp, a xenon lamp, a tungsten lamp, a metal halide lamp, and the like. The developer is preferably an alkaline aqueous solution containing substantially no organic solvent, specifically, sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium tertiary phosphate, dibasic phosphate. Aqueous solutions such as sodium, tribasic ammonium phosphate, dibasic ammonium phosphate, sodium metasilicate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, aqueous ammonia, etc., are suitable, and their concentrations are 0. It is added in an amount of 1 to 10% by weight, preferably 0.5 to 5% by weight. Among these, a developer containing an alkali silicate such as potassium silicate, lithium silicate, and sodium silicate is preferable because stains during printing hardly occur, and the composition of the alkali silicate is [SiO ₂ ] / molar ratio. [M] = 0.5-2.5 (here [SiO _2], [M], respectively, show the molar concentration and the molar concentration of the total alkali metal SiO _2.) it is, and the SiO ₂ 0. A developer containing 8 to 8% by weight is preferably used. In addition, water-soluble sulfites such as sodium sulfite, potassium sulfite and magnesium sulfite, resorcin, methylresorcin, hydroquinone and thiosalicylic acid can be added to the developer. The preferred content of these compounds in the developer is 0.002 to 4% by weight, preferably 0.01 to 1% by weight.

Further, in the above developer, JP-A-50-51
Nos. 324 and 59-84241, anionic surfactants and amphoteric surfactants, and JP-A-59-75255 and JP-A-60-1112.
No. 46, JP-A-60-213943 and the like, by incorporating at least one of nonionic surfactants described in JP-A-55-95 and JP-A-55-95.
As described in JP-A-946-946 and JP-A-56-142528, the incorporation of a polymer electrolyte enhances wettability to the photosensitive composition and enhances development stability (development latitude). be able to. The addition amount of such a surfactant and the like is preferably 0.001 to 2% by weight, and particularly preferably 0.003 to 0.5% by weight. Further, as an alkali metal of alkali silicate in the developer,
It is preferable that potassium is contained in an amount of 20 mol% or more in the total alkali metal, because less insoluble matter is generated in the developer, more preferably 90 mol% or more, and most preferably potassium is 1 mol or more.
It is the case of 00 mol%. In the developing solution, some organic solvents such as alcohols and chelating agents described in JP-A-58-190952,
An antifoaming agent such as a metal salt or an organic silane compound as described in JP-A No. 2-2,086 can be added.

A photosensitive lithographic printing plate having a positive photosensitive layer prepared according to the present invention was prepared by the method described in JP-A-54-8002,
It goes without saying that the plate-making process may be performed by the methods described in JP-A-55-115045 and JP-A-59-58431. That is, after the development processing, it may be subjected to a desensitization treatment after washing with water, a desensitization treatment as it is, a treatment with an aqueous solution containing an acid, or a desensitization treatment after treating with an aqueous solution containing an acid. Furthermore, in the development process of this type of photosensitive lithographic printing plate, the alkali aqueous solution is consumed depending on the processing amount, and the alkali concentration is reduced, or the alkali concentration is reduced by air due to long-time operation of the automatic developing machine. Although the processing capacity is reduced, the processing capacity may be restored by using a replenisher as described in JP-A-54-62004. In this case, it is preferable to replenish by the method described in U.S. Pat. No. 4,882,246. The above-described plate making process is preferably performed by an automatic developing machine as described in JP-A-2-7054 and JP-A-2-32357.

Further, when the photosensitive lithographic printing plate prepared according to the present invention is subjected to image exposure, development, washing with water or rinsing, and then unnecessary image portions are to be erased, it is disclosed in Japanese Patent Publication No. 2-129393. It is preferable to use an erasing liquid as described in (1). In the case where a desensitized gum is applied as required in the final step of the plate making process, if the defatted gum is applied,
No. 16834, No. 62-25118, No. 63-526
No. 00, JP-A-62-7595 and JP-A-62-11693
And the desensitized gums described in JP-A-62-83194. Furthermore, if image exposure, development, washing or rinsing, erasing work as needed, and washing and then burning if desired, if necessary, before burning, JP-B Nos. 61-2518 and 55-2806.
No. 2, JP-A Nos. 62-31859 and 61-15965.
It is preferable to carry out treatment with a surface-regulating liquid as described in each publication of No. 5.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the examples. (Example) An aluminum plate having a thickness of 0.24 mm was grained with a nylon brush having a bristle diameter of 0.48 mm and an aqueous suspension of pumistone having a mesh size of 400 and then washed thoroughly with water. After etching by immersing in a 10% aqueous sodium hydroxide solution at 70 ° C. for 30 seconds, the substrate was washed with running water, neutralized with 20% HNO ₃ , and washed with water. This is V _A = 1
Under the condition of 2.7 V, 10
The electrolytic surface roughening treatment was performed in an aqueous solution of g / L nitric acid at an anode charge of 23 coulomb / dm ² . The surface roughness was measured to be 0.55 μm (Tokyo Seimitsu surfcom575, cu
toff 0.8, Ra display using a stylus of 2 μmR).
Subsequently, it was immersed in a 30% aqueous solution of H ₂ SO ₄ and 55
After desmutting for 2 minutes at 33 ° C, 33 ° C, 15% H ₂ SO
₄ Anodizing was performed in an aqueous solution at a current density of 5 A / dm ² for 45 seconds to prepare a substrate. Thereafter, the substrate was processed under the processing conditions shown in Table 1 below, washed with running water and air-dried, and then the samples of Example and Comparative Example 6 were coated with the following undercoating solution and photosensitive solution. . The undercoat liquid was applied so as to have an application amount of 10 mg / m ² as a solid content.
Dry at 0 ° C. for 20 seconds. The photosensitive solution was applied at 24 ml / m ² by rod coating and dried at 100 ° C. for 1 minute.
The coating amount after drying was about 1.25 g / m ² . In Comparative Examples other than Comparative Example 6, the photosensitive layer was not provided.

[Undercoat solution] ・ Pure water: 5 g ・ Methyl alcohol: 95 g ・ β-alanine: 1.6 g [Photosensitive solution] ・ 1,2-diazonaphthoquinone-5-sulfonyl chloride and pyrogallol-acetone Esterified product with resin (described in Example 1 of U.S. Pat. No. 3,635,709) 0.90 g phenol / p-cresol aldehyde resin having a weight average molecular weight of 8000 (phenol / p- Cresol-molar ratio: 5/5, containing 0.7% g of unreacted cresol) 1.90 gm-cresol-formaldehyde novolak resin (weight average molecular weight 1,700, number average molecular weight 600, unreacted cresol 0.3 g ・ p-n-octylphenol-formaldehyde resin (described in US Pat. No. 4,123,279)・ 0.02 g ・ Naphthoquinonediazide-1,2-diazide-4-sulfonic acid chloride ・ ・ ・ 0.01 g ・ Tetrahydrophthalic anhydride ・ ・ ・ 0.02 g ・ Victoria Pure Blue BOH Tsuchiya Chemical Co., Ltd.] Dye in which the counter anion is changed to 1-naphthalenesulfonic acid 0.05 g Megafac F-176 (a fluorosurfactant manufactured by Dainippon Ink and Chemicals, Inc.)・ ・ ・ 0.01g ・ Methyl ethyl ketone ・ ・ ・ 55g

Based on the method described in Example 1 of JP-B-61-28986, a plate of (methyl methacrylate / ethyl acrylate / sodium acrylate: 68/20/12) was placed on the plate thus coated. Copolymer aqueous solution 1
A mat layer was provided by dissolving 0.1 g of tartrazine in 00 g and electrostatically spraying.

The photosensitive lithographic printing plate thus obtained was used as a light source.
2kW metal halide lamp (Iwasaki Electric Co., Ltd.
(Dolphin) using Fuji Photo Film Co., Ltd.
Adjust the exposure time so that the top guide clears four steps.
Was. After the exposure, the planographic image quality of the printing plate was visually evaluated.
Later, as a developing solution, SiO_Two/ Na_TwoThe molar ratio of O is 1.7
5.26% aqueous solution of sodium silicate (pH = 12.
7) (e.g., Fuji Photo Film PS plate developer DP-4
1: 8 water dilution), and as a finisher
FP-2W (1: 1) manufactured by Photographic Film Co., Ltd.
Fuji Photo Film Co., Ltd. automatic developing machine Stublon 900
V. About the obtained sample,
Aluminum and carbon in the fracture surface of the oxide film
Differential peak intensity by JE spectroscopy and equation (I)
Element ratio by _{C / Al}Table 1 shows the evaluation results
did. The measurement positions in Table 1 refer to the anodic oxide film and the photosensitive position.
The distance from the interface with the layer to the support.

<Evaluation Method> Erasability: The image portion of the printing plate after development was dissolved with an erasing solution (Erasing Solution RP-2 manufactured by Fuji Photo Film Co., Ltd.), and the photosensitive layer appeared to be completely removed. (Time until the remaining photosensitive layer in the image area cannot be completely identified). Table 1
The average value is the average of two measurements. How to determine the elemental ratio _{C / Al} of aluminum and carbon in the fracture surface using an Auger electron spectrometer: Measurement device: FE-AES model 680 (manufactured by ULVAC-PHI, Inc.) Measurement conditions: irradiation current: about 10 nA, acceleration voltage: 10k
V, irradiation electron beam diameter: focused chamber pressure: about 1 × 10 ⁻¹⁰ Torr Detection range: 20 to 2020 eV, 1.0 eV / ste
p, 20 ms / step multiplier voltage: 225
0V Sample preparation method: Immediately before the measurement, the anodized aluminum support was bent almost 180 ° to form a fractured surface of the anodized film, fixed to a sample holder attached to the device, and introduced into the device. Calculation method: The element ratio _{C / Al} was determined according to the formula (I). still,
Carbon (KLL) Auger electron relative sensitivity coefficient S _c = 0.07
6, and aluminum (KLL) were calculated using Auger electron relative sensitivity coefficient S _Al = 0.105.

[0042]

[Table 1]

[0043]

[Table 2]

As is clear from Table 1, from the comparison between the example and the comparative example, the presence _/ absence of the photosensitive layer affects the elemental ratio _{C / Al} at the measurement position of 300 nm or less.
At the measurement position exceeding nm, the element ratio depending on the presence or absence of the photosensitive layer
It can be seen that there is no difference in _{C / Al} . In addition, the photosensitive lithographic printing plate of the embodiment in which the element ratio _{C / Al} by Auger electron spectroscopy is 0.3 or less at a position 300 nm away from the interface between the anodic oxide film and the photosensitive layer toward the support side has an erasability. It turns out that it is excellent.

[0045]

As described above, according to the present invention,
To provide a photosensitive lithographic printing plate exhibiting good erasability irrespective of the processing method of a support by defining the allowable amount of a photosensitive composition that may be present at an interface between an anodized film and a photosensitive layer. Can be.

Claims (2)

[Claims] 1. A photosensitive lithographic printing plate comprising a photosensitive layer provided on a support having an anodic oxide film formed on an aluminum or alloy plate thereof, wherein the photosensitive layer penetrating into the micropores of the anodic oxide film comprises: A photosensitive lithographic printing plate characterized by being limited to a range of 300 nm from the interface between the anodized film and the photosensitive layer in the direction of the support. 2. A photosensitive lithographic printing plate having a photosensitive layer provided on a support having an anodic oxide film formed on an aluminum or alloy plate thereof, wherein the fracture surface of the anodic oxide film is subjected to point analysis by an Auger electron spectrometer. Where the element ratio _{C / Al} between the carbon element and the aluminum element due to the photosensitive layer calculated from the following formula (I) is more than 300 nm away from the interface between the anodic oxide film and the photosensitive layer toward the support. Is a photosensitive lithographic printing plate characterized by being 0.3 or less. Element ratio _{C / Al = (I c /} S c) / (I Al / S Al) ··· (I) I c: carbon (KLL) Auger electron differential peak-to-peak intensity I _Al: Aluminum (KLL Auger electron differential peak-to
-Peak intensity S _c : Relative sensitivity coefficient of carbon (KLL) Auger electrons S _Al : Relative sensitivity coefficient of aluminum (KLL) Auger electrons