JP2000089470A - Photosensitive planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve plate inspectability and to make dust traces and film edge traces in particular easily visible and to make register marks easily visible as well by making the average dye content per unit area of the layer nearest a substrate among the layers which are made soluble in a developer by exposure higher than the average dye contents of the other layers. SOLUTION: The surface of the aluminum substrate subjected to an anodic oxidation treatment is provided with >=2 layers of the layers which are made soluble in the developer by exposure. The photosensitive planographic printing plate of which the average dye content per unit area of the layer nearest the substrate among the respective layers is higher than the average dye contents of the other layers is used. The surface of the substrate is provided, with >=2 layers of the layers which are made soluble in the developer by exposure, i.e., the photosensitive layers and the average dye content per unit area of the layer nearest the substrate among the photosensitive layers is made higher than that of the other photosensitive layers. When the plural photosensitive layers are coterminous with each other and appear as one layer at a glance, the photosensitive layers of two-layer constitution is assumed and are divided into the upper layer and the lower layer at the point of 50% of the thickness of the photosensitive layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive photosensitive lithographic printing plate, and more particularly to a positive photosensitive lithographic printing plate having a photosensitive layer containing a positive photosensitive composition on an aluminum plate having an anodic oxide film. It concerns printing plates.

[0002]

2. Description of the Related Art Conventionally, a lithographic printing plate is obtained by developing a photosensitive lithographic printing plate obtained by coating a photosensitive composition in a thin layer on an aluminum plate after image exposure. The above aluminum plate is usually subjected to a 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,
After the surface is pear-skinned, it is etched with an aqueous solution of an acid or alkali, and further subjected to an anodizing treatment, and if desired, subjected to a hydrophilic treatment to form a support for a lithographic printing plate. A photosensitive lithographic printing plate (so-called PS plate) is provided with a photosensitive layer. This PS plate is usually subjected to image exposure, development, plate inspection, correction, and gumming steps to form a lithographic printing plate, which is mounted on a printing press for printing. Of these, plate inspections consist of 1) unnecessary images, 2) "dust marks" due to fine dust on the original film and the photosensitive lithographic printing plate at the time of image exposure, and 3) the original film as a base film with cellophane tape. This is an important work to check for "film edge marks" due to the edges of the film when using a film pasted with a film (so-called pasted film). In order to facilitate the plate inspection, the photosensitive layer of the photosensitive lithographic printing plate is conventionally colored blue or green with a dye.
Generally, when the density of the image portion is increased and the contrast (ΔD) between the image portion and the non-image portion is increased, plate inspection becomes easier. On the other hand, the register mark written on the photosensitive lithographic printing plate with a blue ballpoint pen to align the original film and the photosensitive lithographic printing plate becomes very difficult to see if the PS plate is dark, and it is difficult to inspect the plate. Balancing was difficult. Further, in the plate inspection work, the above-mentioned "dust mark" and "film edge mark" are exposed to some extent at the time of image exposure, so that a considerable portion of the photosensitive layer is eluted and is difficult to see and easily overlooked. . That is, the visibility of the "dust mark" and "film edge mark" in plate inspection is an extremely important part.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photosensitive lithographic printing plate having good plate inspection properties, in particular, dust marks and film edge marks are easy to see, and register marks are easy to see.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have accomplished the present invention. The present invention is as follows. (1) On an anodized aluminum support,
A photosensitive lithographic printing plate provided with at least two layers that become soluble in a developer by exposure, wherein among the layers, the average dye content per unit volume of the layer closest to the support is the average of the other layers. A photosensitive lithographic printing plate characterized by having a higher dye content.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below step by step. The photosensitive lithographic printing plate of the present invention is a layer provided with two or more photosensitive layers on a support, the layer being soluble in a developer by exposure, among these photosensitive layers,
The average dye content per unit volume of the photosensitive layer closest to the support is higher than that of the other photosensitive layers.

In the case where a plurality of photosensitive layers are fused with each other and seemingly appear as one layer, it is assumed that the photosensitive layer has a two-layer structure, and the upper and lower layers are located at 50% of the thickness of the photosensitive layer. Shall be divided.

Hitherto, it has been considered that a photosensitive lithographic printing plate having excellent plate inspection properties has difficulty in register marks and it is extremely difficult to satisfy them simultaneously. Only lowering the density (whitening) of the non-image portion is intended to increase the compatibility of both, but there was naturally a limit due to the fact that the eyes tended to shine and glow during plate inspection.

However, in the photosensitive lithographic printing plate according to the present invention, as described above, the photosensitive layer has a multilayer structure, and the dye concentration of the layer on the support side is the highest as compared with the other layers. In addition to having the performance of excellent plate inspection, it also has excellent properties that have not been obtained conventionally, such that register marks are easy to see. On the other hand, if the photosensitive layer has a one-layer structure having a uniform dye concentration, it will be difficult to achieve both excellent plate inspection properties and legibility of the register mark, and if the concentration is relatively high, the register mark will be difficult to see. If the concentration is relatively low, the plate inspection becomes poor.

In general, it is preferable to reduce the amount of dye applied per unit area if the main purpose is to make the register mark easy to see. It is preferable to increase the coating amount per unit and to provide a high-concentration dye layer in a region closest to the support. That is, considering the legibility of the register mark, the amount of the dye in the entire photosensitive layer is preferably small, and the amount of the dye in the photosensitive layer remaining without being dissolved after development is preferably large in terms of plate inspection. . However, in order to maintain the function of the lithographic printing plate as a light-sensitive material and to secure developability, it is preferable to provide a high-concentration layer of a dye in a relatively narrow area of the closest area of the support. The present invention has been made from such a viewpoint.

Therefore, the average dye content per unit volume of the photosensitive layer closest to the support is preferably at least 1.5 times the photosensitive layer having the second average dye content after the other layers. Although it depends on the amount of dye in the entire photosensitive layer, the thickness of the photosensitive layer closest to the support, and the like, it is generally preferred that the amount be twice or more.

The dye content in this case can be appropriately selected according to the dye used. The average dye content of each photosensitive layer is calculated from the composition of the coating solution with the specific gravity of each photosensitive layer being 1, when the photosensitive layer closest to the support is not dissolved in the coating solvent of the photosensitive layer to be subsequently applied. You can ask. Otherwise, the photosensitive layer far from the support is scraped off with a cutter knife or the like, and the remaining photosensitive layer (determined by the gravimetric method) is dissolved in a certain amount of an organic solvent. The average dye content of the photosensitive layer is determined. The shaved photosensitive layer can be determined by subtracting the dye in the remaining photosensitive layer from the total amount of dye.

A photosensitive lithographic printing plate having a photosensitive layer having a multilayer structure having such a dye concentration distribution can be prepared by sequentially applying coating solutions having different dye concentrations. In particular, the photosensitive layer (particularly, a binder described later) used for the coating on the side closer to the support (first coating) has a solvent for the coating used on the layer farther from the support (second coating). It is preferable to use a material that is difficult to dissolve. This makes it possible to prevent the dye from diffusing from the high-concentration dye layer to the low-concentration dye layer, thereby preventing the dye concentration from becoming uniform.

As described above, the photosensitive layer of the photosensitive lithographic printing plate of the present invention is generally formed by coating. Therefore, from the viewpoint of production, the high-concentration dye layer and the low-concentration dye layer are formed from the support side. It is preferable to form a two-layer structure of a combination of the density dye layers and to make the dye density in each layer uniform. However, under the restrictions of the present invention, a multilayer structure of three or more layers may be used,
Further, a concentration gradient of the dye may be provided in each of the high concentration dye layer and the low concentration dye layer.

The preferred 2 in the present invention
In the layer structure, the high-concentration dye layer is preferably applied as a layer having a thickness of 3 to 50% from the support side, and more preferably 10 to 10 depending on the total amount of dye and the amount of dye in the layer.
It is preferably applied as a layer having a thickness of 35%.

In the case of a photosensitive layer having a two-layer structure, the ratio of the dye in the high-concentration dye layer to the dye in the entire photosensitive layer is not particularly limited because the average dye content per unit volume is important. Generally, it is preferably 40 to 100% by weight, and more preferably 60 to 100% by weight. This value can also be determined from the same measurement as the aforementioned average dye content.

In the present invention, the coating amount of the dye per 1 m ^{2 of the} entire photosensitive layer varies depending on the dye.
1 to 0.1 g, preferably 0.02 g
It is preferably from 0.1 to 0.1 g.

As the dye used in the present invention, various known dyes are all used as a colorant for an image. As a printing-out agent for obtaining a visible image immediately after exposure, a photosensitive agent which releases an acid upon exposure is used. Organic dyes capable of forming a salt used in combination with an acidic compound can be mentioned as typical examples. Specifically, JP-A-50-36209, JP-A-53-8
No. 128, a combination of o-naphthoquinonediazide-4-sulfonic acid halide and a salt-forming organic dye or JP-A-53-36223, JP-A-54-74728, JP-A-60-3626,
Combinations of trihalomethyl compounds and salt-forming organic dyes described in JP-A-61-143748, JP-A-61-151644 and JP-A-63-58440 can be exemplified. Other dyes besides the above-mentioned salt-forming organic dyes can be used as image coloring agents. Suitable dyes, including salt-forming organic dyes, include oil-soluble dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 130,
Oil pink # 312, oil green BG, oil blue B
OS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (all manufactured by Orient Chemical Industries, Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Rhodamine B ( CI45170B), mykite green (CI42000), methylene blue (CI52015), curcumin and the like. Also, Japanese Patent Application Laid-Open
The dyes described in 293247 are particularly preferred.

The proportion of the above dye in the total photosensitive layer is 0.01%.
-10% by weight is suitable, preferably 0.05-5% by weight.

The composition of the photosensitive layer in the present invention includes:
Any material can be used as long as its solubility or swelling property in a developer changes before and after exposure. Hereinafter, typical ones will be described.

Examples of the photosensitive compound of the positive photosensitive composition include an o-quinonediazide compound, and a representative example thereof is an o-naphthoquinonediazide compound.

The o-naphthoquinonediazide compound is an ester of 1,2-naphthoquinone (2) diazide-5-sulfonic acid chloride and pyrogallol-acetone resin described in JP-B-43-28403. preferable. Other suitable o-quinonediazide compounds include 1,2-naphthoquinone (2) diazide-5- (or-4-) sulfonic chloride described in U.S. Pat. Nos. 3,046,120 and 3,188,210. And phenol-formaldehyde resins. Other useful o-naphthoquinonediazide compounds include those reported and known in numerous patents. For example, JP-A-47-5303 and JP-A-48-63802
No. 48-63803, No. 48-96575, No. 49-3870
No. 1, No. 48-13354, No. 51-139402, No. 58-15
No. 0948, No. 58-203434, No. 59-165053, No. 60
No. 121445, No. 60-134235, No. 60-163043, No. 61-118744, No. 62-10645, No. 62-10646,
No. 62-153950, No. 62-178562, No. 64-76047
No., Japanese Patent Publication No. 37-18015, No. 41-11222, No. 45-96
No. 10, No. 49-17481, U.S. Pat.No. 2,797,213,
No. 3,454,400, No. 3,544,323, No. 3,573,917
No. 3,674,495, No. 3,785,825, No. 3,102,80
No. 9, No. 3,126,281, No. 3,130,047, No. 3,148,9
No. 83, No. 3,184,310, No. 3,188,210, No. 4,639,
No. 406, UK Patent No. 1,227,602, No. 1,251,345, No. 1,267,005, No. 1,329,888, No. 1,330,932,
Examples described in German Patent No. 854,890 and the like can be given.

In synthesizing these o-naphthoquinonediazide compounds, 1,2-naphthoquinone (2) diazide-5 is added to the hydroxyl group of the polyhydroxy compound.
It is preferable to react 0.2 to 1.2 equivalents of (or -4-) sulfonic acid chloride, more preferably 0.3 to 1.0 equivalent.

As the photosensitive compound which acts positively without using an o-naphthoquinonediazide compound, for example, a polymer compound having an orthonitrocarbinol ester group described in JP-B-56-2696 is also included in the present invention. Can be used.

A compound that generates an acid by photolysis,
A combination system with a compound having a —CO—C group or a —CO—Si group dissociated by an acid can also be used in the present invention.

For example, a combination of a compound capable of generating an acid by photolysis with an acetal or an O, N-acetal compound (JP-A-48-89003) or a combination with an orthoester or amide acetal compound (JP-A-51-120714) issue),
Combination with a polymer having an acetal or ketal group in the main chain (JP-A-53-133429), combination with an enol ether compound (JP-A-55-12995), combination with an N-acylimino carbon compound (JP-A-55-12995) 55-126236), a combination with a polymer having an orthoester group in the main chain (JP-A-56-17345), a combination with a silyl ester compound (JP-A-60-10247), and a combination with a silyl ether compound. Combination (JP-A-60-37549, JP-A-60-121446)
And the like.

The amount of these positive-acting photosensitive compounds (including the above combinations) in the photosensitive composition of the present invention is suitably from 10 to 50% by weight, more preferably from 15 to 50% by weight. 40% by weight.

Although the o-quinonediazide compound alone forms the photosensitive layer, it is preferable to use a resin soluble in alkaline water as a binder together with this kind of resin. Such resins soluble in alkaline water include novolak resins having this property, such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m / p-mixed cresol formaldehyde resin, and phenol / cresol. (It may be m-, p- or m- / p-mixed) Cresol formaldehyde resin such as mixed formaldehyde resin, phenol-modified xylene resin, polyhydroxystyrene, polyhalogenated hydroxystyrene, JP-A-51-34711 Acrylic resin containing a phenolic hydroxyl group as disclosed in JP-A-8-339082, acrylic resin having a urea bond according to claim 2 of JP-A-8-339082, and JP-A-2-866 An acrylic resin having a sulfonamide group or And various alkali-soluble polymer compounds such as urethane resins and the like. These alkali-soluble polymer compounds preferably have a weight average molecular weight of 500 to 200,000 and a number average molecular weight of 200 to 60,000. Further, it is preferable to use an acrylic resin or a urethane resin for the photosensitive layer (first layer) close to the support side, partly or entirely (5 to 100% by weight of the total binder amount of the first layer).

Such an alkali-soluble polymer compound is generally used in an amount of not more than 70% by weight of the total photosensitive composition.

Further, as described in US Pat. No. 4,123,279, phenol having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and t-octylphenol formaldehyde resin, is used. It is preferable to use a condensate with formaldehyde in combination in order to improve the oil sensitivity of the image.

In the photosensitive composition of the present invention, a cyclic acid anhydride for enhancing the sensitivity, a printing-out agent for obtaining a visible image immediately after exposure, and other fillers can be added. U.S. Pat.No. 4,115,128 as a cyclic acid anhydride
Phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6
-Endoxy-Δ ⁴ -tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like. By containing these cyclic acid anhydrides in an amount of 1 to 15% by weight based on the total weight of the composition, the sensitivity can be increased up to about three times.

The photosensitive composition according to the present invention is dissolved in a solvent that dissolves the above-mentioned components and applied on a support to form a photosensitive lithographic printing plate. Examples of the solvent used herein include ethylene dichloride, cyclohexanone, methyl ethyl ketone, γ-butyrolactone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, 2-methoxyethyl acetate, 1-methoxy-2-propanol, -Methoxy-2-propyl acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, water, N-methylpyrrolidone, tetrahydrofurfuryl alcohol, acetone, diacetone alcohol, methanol, ethanol, There are isopropanol, diethylene glycol dimethyl ether and the like, and these solvents are used alone or in combination.

In the photosensitive composition of the present invention, a surfactant for improving coating properties, for example, JP-A-62-1709.
A fluorine-based surfactant as described in JP-B-50 can be added. The preferable addition amount is 0.01 to 1% by weight, more preferably 0.05 to 0.5% by weight of the whole photosensitive composition.

The solid content in the photosensitive composition is 2 to 50% by weight. As the coating method used when the photosensitive layer is provided on the support surface in the present invention, conventionally known methods, for example, spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, curtain coating and spraying Coating or the like is possible.
Among them, a spray coating method using an electrostatic system as disclosed in Japanese Patent Application No. 2-41135 is particularly preferable. The amount of coating varies depending on the application, but is generally 0.5 to 3.0 g / solid as a solid content in an amount per 1 m ^{2 of} the support.
m ² is preferred. The photosensitivity increases as the coating amount decreases, but the film properties of the photosensitive layer decrease.

In general, when a film original is closely printed on a photosensitive lithographic printing plate, the printing frame is evacuated to a vacuum. A method for improving the vacuum adhesion is described in the plate making of the photosensitive lithographic printing plate of the present invention. Can be applied to

Methods for improving the vacuum adhesion include a method of mechanically embossing the surface of the photosensitive layer, a method of spraying a solid powder on the surface of the photosensitive layer, and JP-A-50-125805 and JP-A-51-111102.
Nos. 52-29302 and 57-34558, in which a mat layer is provided on the surface of a photosensitive layer, and a method described in JP-A-55-12974. A method of thermally fusing a solid powder to the surface of the layer may be used.

The aluminum plate used as the support in the present invention is a plate-like body made of pure aluminum or an aluminum alloy containing aluminum as a main component and containing a trace amount of a different atom. This heteroatom includes silicon, iron, manganese,
Copper, magnesium, chromium, zinc, bismuth, nickel, titanium and the like. Heterogeneous content in alloys at most
10% by weight or less. The preferred aluminum for the present invention is pure aluminum, but completely pure aluminum is
Since production is difficult due to refining technology, it is preferable that the content of foreign atoms be as low as possible. Further, any aluminum alloy having the above-described content can be said to be a material applicable to the present invention. Thus, the composition of the aluminum plate applied to the present invention is not specified,
Conventionally known and publicly available materials can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.5 mm.

The aluminum plate of the present invention has been subjected to a surface roughening treatment and an anodic oxidation treatment. Such an aluminum plate has the advantage of being flexible and having excellent corrosion resistance and durability.

Prior to the surface roughening treatment of the aluminum plate, if necessary, a degreasing treatment with, for example, a surfactant or an alkaline aqueous solution is performed to remove rolling oil on the surface.

The photosensitive lithographic printing plate of the present invention may be one that can be used only on one side or one that can be used on both sides by the same processing. Since the same applies to both surfaces, the case of one surface will be described below.

The surface roughening method includes a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of chemically selectively dissolving 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 surface roughening method, there is a method of performing an alternating or direct current in a hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used.

The aluminum plate thus roughened is subjected to an alkali etching treatment and a neutralization treatment as required.

As the electrolyte used for the anodic oxidation treatment of the aluminum plate, any electrolyte that forms a porous oxide film can be used.
Phosphoric acid, oxalic acid, chromic acid or a mixed acid thereof is used, and the concentration of the electrolyte is appropriately determined depending on the type of the electrolyte.

The anodizing treatment conditions vary depending on the electrolyte to be used and cannot be specified unconditionally. However, in general, the concentration of the electrolyte is 1 to 80% by weight, the solution temperature is 5 to 70 ° C., and the current density is 5 to 70%. It is appropriate that the voltage is 60 A / dm ² , the voltage is 1 to 100 V, and the electrolysis time is 10 seconds to 50 minutes.

The aluminum plate which has been roughened and anodized as described above may be subjected to a hydrophilizing treatment, if necessary. Preferred examples thereof are disclosed in US Pat. Nos. 2,714,066 and 3,181,461. Aqueous solution of an alkali metal silicate (for example, sodium silicate), such as the aqueous solution of potassium fluorozirconate disclosed in JP-B-36-22063 (= US Pat. No. 2,946,683) or US Pat. No. 4,415,461. A method of treating with an aqueous solution of polyvinyl phosphonic acid as disclosed in the specification, a method of treating with hot water or steam as disclosed in JP-A-59-114100, and JP-A-3-235950. There is a method of treating with an aqueous solution of nitrous acid or a salt thereof as disclosed, or an aqueous solution of sulfonic acid or a salt thereof as disclosed.

The aluminum plate thus treated is:
Before coating the photosensitive layer, a method of undercoating hydrophilic cellulose containing a water-soluble metal salt for the purpose of reducing residual color, or sodium aryl sulfonate as described in British Patent No. 2098627 Undercoat, polyacrylamide disclosed in U.S. Pat.No. 3,151,661, polyvinyl phosphonic acid disclosed in JP-B-46-35685, JP-A-60-149491
And amino acids and salts thereof (Na
Salts, alkali metal salts such as K salts, ammonium salts, hydrochlorides, oxalates, acetates, phosphates, etc.), JP-A-60-232998
Amines having a hydroxyl group and salts thereof (hydrochlorides, oxalates, phosphates, etc.) disclosed in Japanese Patent Application Laid-Open No. 63-1
No. 65183 and a method for undercoating a compound having an amino group and a phosphonic acid group or a salt thereof disclosed in JP-A-3-261542, and undercoating a phosphonic acid shown in Japanese Patent Application No. 3-10604. It is preferable to apply a method and a method of combining these undercoats.

As the developer for the photosensitive composition of the present invention, sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium phosphate tribasic, sodium phosphate dibasic, Aqueous solutions of inorganic alkali agents such as ammonium phosphate, diammonium phosphate, sodium metasilicate, sodium bicarbonate, aqueous ammonia, etc., whose concentration is 0.1
-10% by weight, preferably 0.5-5% by weight.

Further, such an alkaline aqueous solution may be added, if necessary, to a surfactant such as those described in JP-A-50-51324 and JP-A-59-84241, and JP-A-58-190952. Chelating agents as described in
An organic solvent such as a water-soluble metal salt described in Japanese Patent Publication No. 9 or alcohol or the like can also be added.

Light sources used for exposure include a carbon arc lamp, a mercury lamp, a xenon lamp, a tungsten lamp, a metal halide lamp, and the like.

[0049]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, "%" indicates "% by weight" unless otherwise specified.

Example 1 (Preparation of Aluminum Substrate) An aluminum plate having a thickness of 0.30 mm was grained using a nylon brush and 400 mesh pumice tones using an aqueous suspension, and washed thoroughly with water. After etching by dipping in 10% sodium hydroxide at 70 ° C. for 60 seconds, the substrate was washed with running water, then neutralized and washed with 20% HNO ₃ , and washed with water. This was subjected to electrolytic surface roughening treatment in a 1% aqueous nitric acid solution at an anode electricity of 160 coulomb / dm ² using a sinusoidal alternating waveform current under the condition of V _A = 12.7 V. When the surface roughness was measured, it was 0.6 μm (Ra indication according to JIS B 0601). Then immersed in a 30% H ₂ SO ₄ aqueous solution at 55 ° C
And then anodized in a 20% H ₂ SO ₄ aqueous solution at a current density of 2 A / dm ^{2 to} a thickness of 2.7 g / m ² to prepare a substrate.

An undercoat solution (A) having the following composition was applied to the surface of the substrate thus treated, and dried at 80 ° C. for 30 seconds. The coating amount after drying was 30 mg / m ² .

Undercoat solution (A) Aminoethylphosphonic acid 0.10 g Phenylphosphonic acid 0.15 g β-alanine 0.10 g Methanol 40 g Pure water 60 g Thus, the substrate (I) was prepared.

[Preparation of Sample of the Present Invention] (Preparation of photosensitive lithographic printing plate (1)) Next, this substrate (I)
The photosensitive composition coating solution (1) having the following composition was applied on a wire bar at a solid content of 0.9 g per m ² using a wire bar, and dried at 120 ° C. for 1 minute (first layer formation).

Further, 0.9 g of a photosensitive composition coating solution (2) having the following composition was similarly applied at a solid content per 1 m ² , and then applied.
After drying at 120 ° C. for 1 minute (second layer formation), a positive photosensitive lithographic printing plate (1) having a two-layered photosensitive layer was obtained.

Coating solution for photosensitive composition (1) Esterified product of naphthoquinone-1,2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin (described in Example 1 of US Pat. No. 3,635,709) [A] 0.45 g tetrahydrophthalic anhydride 0.01 g benzoic acid 0.02 g copolymer of N- (p-aminosulfonylphenyl) methacrylamide / ethyl methacrylate / acrylonitrile (molar ratio 32:43: 25) [Compound of Synthesis Example 2 of JP-A-2-866] 0.9 g-Cresol-formaldehyde novolak 0.2 g (meta-para ratio: 6 to 4, weight-average molecular weight: 5000, number-average molecular weight: 1600, unreacted) Cresole 0.7%) ・ 4- [pN- (p-hydroxybenzoyl) aminophenyl] -2,6-bis (trichloromethyl) -S-triazine 0.02g ・ Victoria Pure Blue BOH [Hodogaya Chemicals Co., Ltd.] 1-naphthalenesulfonic acid converted to a counter anion 0.08 g ・ Curcumin 0.02 g ・ MegaFac F-176 (Fluorine-based surfactant manufactured by Dainippon Ink and Chemicals, Inc.) 0.02 g・ Γ-butyrolactone 5g ・ Methyl ethyl ketone 15g

Photosensitive Composition Coating Solution (2) Esterified product of naphthoquinone-1,2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin (described in Example 1 of US Pat. No. 3,635,709). [A] 0.45 g ・ Cresol-formaldehyde novolak 1.18 g (meta; para ratio; 6: 4, weight average molecular weight: 5000, number average molecular weight: 1600, containing 0.7% of unreacted cresol) ・ 4- [ pN- (p-hydroxybenzoyl) aminophenyl] -2,6-bis (trichloromethyl) -S-triazine 0.01 g ・ pt-octylphenol-formaldehyde novolak 0.04 g ・ Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.] 0.02g ・ MegaFac F-176 (Fluorine-based surfactant manufactured by Dainippon Ink and Chemicals, Inc.) 0.02g ・ P Propylene glycol monomethyl ether 5 g · Methyl ethyl ketone 15g

(Preparation of photosensitive lithographic printing plates (2) and (3)) The coating amounts of the photosensitive composition coating solutions (1) and (2) in the preparation of the photosensitive lithographic printing plate (1) are shown in Table 1. A photosensitive layer was formed in the same manner as in the preparation of the sample of the photosensitive lithographic printing plate (1) except for changing as described above to obtain photosensitive lithographic printing plates (2) and (3).

[Preparation of Comparative Sample] (Preparation of photosensitive lithographic printing plates (4) to (6)) The same as the photosensitive layer of the photosensitive lithographic printing plate (1), except that the photosensitive layer was composed of one layer. A liquid was prepared by mixing the photosensitive composition coating liquids (1) and (2) so as to have a composition, and applied by a wire bar to a solid content of 1.8 g / m ² in the same manner as in the preparation of the sample. .
It dried at 120 degreeC for 1 minute, and produced the positive photosensitive lithographic printing plate (4).

Similarly, the photosensitive lithographic printing plates (5) and (6) were replaced with the photosensitive layers of the photosensitive lithographic printing plates (2) and (3), respectively, except that the photosensitive layer had a single-layer structure. Were made to be the same.

First, a register mark was written on the photosensitive lithographic printing plate (1) obtained as described above with a blue ballpoint pen manufactured by Pilot Co., Ltd., and the visibility was visually evaluated. The photosensitive lithographic printing plate (1) is passed through a manuscript in which three positive films are pasted on a transparent base with cellophane tape using a metal halide lamp as a light source.
Exposure for 2 seconds, then Developer D from Fuji Photo Film Co., Ltd.
Processing was carried out through an automatic developing machine charged with P-4 (diluted 8 times with water) and rinse solution FR-2 (diluted 8 times with water). On the obtained plate, traces of film edges and traces of dust were observed, and the visibility was visually evaluated. Next, a solution prepared by diluting gum GU-7 manufactured by Fuji Photo Film Co., Ltd. with water two-fold was applied to the plate surface, allowed to stand for one day, and then printed with a Heidel KOR-D machine.

Film edge marks and dust marks were also found on non-image areas on the printing plate.

Next, the exposure time of each of the photosensitive lithographic printing plates (2) to (6) was changed so that the film edge marks and dust marks on the printed matter became the same as those of the photosensitive lithographic printing plates (1). The same experiment as in the photosensitive lithographic printing plate (1) was performed. At that time, the visibility of the film edge traces and dust traces on the plate and the visibility of the register marks were visually evaluated. The results are shown in Table 1 together with the results of the photosensitive lithographic printing plate (1). "Printability" and "visibility of register marks" were evaluated and indicated on a scale of A to E, with A being "extremely visible" and E being "extremely invisible". In the table, the average dye content per unit volume and the like determined as described above are described.

[0063]

[Table 1]

As can be seen from Table 1, the photosensitive lithographic printing plates (1) to (3) of the present invention have better register mark visibility than the photosensitive lithographic printing plates (4) to (6) of the comparative examples. At the same level, film edge marks and dust marks are clearly visible, that is, they have excellent plate inspection properties. The photosensitive lithographic printing plate (3) is not so good in plate inspection, but it can be further improved by regulating the amount of the whole dye and the first dye layer. Thus, according to the present invention, a photosensitive lithographic printing plate having remarkably excellent performance can be obtained.

[Example 2] [Preparation of sample of the present invention] (Preparation of photosensitive lithographic printing plates (7) to (9)) In the photosensitive lithographic printing plates (1) to (3) of Example 1, The following photosensitive composition coating liquid (3) was used in place of the photosensitive composition coating liquid (1), and the following photosensitive composition coating liquid (4) was used instead of the photosensitive composition coating liquid (2). The photosensitive lithographic printing plate (4) was used in the same manner as the photosensitive lithographic printing plates (1) to (3) of Example 1 except that each coating was performed using a spray instead of a wire bar. To (6).

[Preparation of Comparative Samples] (Preparation of photosensitive lithographic printing plates (10) to (12)) In the photosensitive lithographic printing plates (4) to (6) of Example 1, the photosensitive composition coating solution The photosensitive lithographic printing plate of Example 1 was applied except that the photosensitive composition coating solutions (3) and (4) were used instead of (1) and (2), respectively, and the spraying was applied instead of the wire bar. In the same manner as in (4) to (6), photosensitive lithographic printing plates (7) to (9) were prepared.

Photosensitive Composition Coating Solution (3) Esterified product of naphthoquinone-1,2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin (described in Example 1 of US Pat. No. 3,635,709). [A] 0.45 g tetrahydrophthalic anhydride 0.01 g 1- [α-methyl-α- (4-hydroxy-3,5-dihydroxymethylphenyl) ethyl] -4- [α, α-bis ( 4-hydroxy-3,5-dihydroxymethylphenyl) ethyl] benzene (compound (X) of JP-A-6-282067) 0.04 g Cresol-formaldehyde novolak 1.1 g (meta / para ratio; 6 to 4, weight) Average molecular weight: 5000, number average molecular weight: 1600, containing 0.7% of unreacted cresol) ・ 4- [pN- (p-hydroxybenzoyl) aminophenyl] -2,6-bis (trichloromethyl) -S-triazine 0.02g ・ pt-octylphenol-formal Hydnovolak 0.02g ・ Dye in which the counter anion of Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.] is changed to 1-naphthalenesulfonic acid 0.08g ・ Curcumin 0.02g ・ MegaFac F-176 (Dainippon Ink & Chemicals, Inc.) 0.02 g ・ Propylene glycol monomethyl ether 3 g ・ Methyl ethyl ketone 15 g

Coating solution for photosensitive composition (4) Esterified product of naphthoquinone-1,2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin (described in Example 1 of US Pat. No. 3,635,709) [A] 0.45 g tetrahydrophthalic anhydride 0.01 g 1- [α-methyl-α- (4-hydroxy-3,5-dihydroxymethylphenyl) ethyl] -4- [α, α-bis ( 4-hydroxy-3,5-dihydroxymethylphenyl) ethyl] benzene (compound (X) of JP-A-6-282067) 0.04 g Cresol-formaldehyde novolak 1.1 g (meta / para ratio; 6 to 4, weight) Average molecular weight: 5,000, number average molecular weight: 1600, containing 0.7% of unreacted cresol) ・ 4- [pN- (p-hydroxybenzoyl) aminophenyl] -2,6-bis (trichloromethyl) -S-triazine 0.02g ・ pt-octylphenol-forma Dehydro novolak 0.02 g · Curcumin 0.02 g · MEGAFAC F-176 (Dainippon Ink and Chemicals fluorochemical surfactant) 0.02 g · Propylene glycol monomethyl ether 3 g · Methyl ethyl ketone 15g

These photosensitive lithographic printing plates (7) to (12)
Was evaluated in the same manner as in Example 1 for plate inspection and register mark visibility. Table 2 shows the results.

[0070]

[Table 2]

As can be seen from Table 2, according to the present invention,
It is possible to obtain a photosensitive lithographic printing plate which is excellent in terms of compatibility between plate inspection and visibility of register marks. In addition, the plate inspection property of the photosensitive lithographic printing plate (9) can be improved by regulating the amount of the whole dye and the amount of the dye in the first layer.

[0072]

The photosensitive lithographic printing plate obtained according to the present invention is remarkably excellent in that dust marks and film edge marks are easy to see and excellent in plate inspection, and that register marks are also easy to see as compared with conventional ones. It has excellent performance.

Claims (1)

[Claims] 1. A photosensitive lithographic printing plate comprising, on an anodized aluminum support, at least two layers which become soluble in a developing solution by exposure to light. A photosensitive lithographic printing plate characterized in that the average dye content per unit volume of the near layer is higher than the average dye content of the other layers.