JP3296899B2 - Lithographic printing plate processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a lithographic printing plate by a silver complex salt diffusion transfer method.

[0002]

2. Description of the Related Art An offset printing plate using a silver image obtained by a silver complex salt diffusion transfer method (DTR) has already been disclosed in Japanese Patent Publication No. 46-43232 or Japanese Patent Publication No. 48-3.
No. 0562, and a positive-type printing original plate is disclosed in JP-A-49-55402.
For a negative-type printing original plate, see Japanese Unexamined Patent Publication No.
No. 106902, JP-A-52-112402 and the like.

[0003] These direct printing plates are composed of a support, an undercoat layer for preventing halation thereon, a silver halide emulsion layer, and a physical development nucleus layer. When the photosensitive material is imagewise exposed and then processed with a developer containing a developing agent and a silver halide solvent, a latent image is formed.The silver halide is blackened in the emulsion layer. Is not formed by the action of the silver halide complexing agent and diffuses to the surface of the light-sensitive material. The silver complex salt is deposited as a silver image on the physical development nuclei of the surface layer by the reducing action of the developing agent. This process results in a direct printing plate.

After development, in order to enhance the ink receptivity of the silver image, if necessary, the silver image is subjected to a sensitization treatment, and the ink image is transferred to a printed material on an offset printing machine. This direct printing plate has advantages such as good operability and low cost, but on the other hand, diffusion transfer is completed within the processing time due to the nature of forming a silver image for printing by photographic development processing However, excessive silver ions remained, and this contributed to a decrease in storage stability or printing durability.

[0005] Various methods are used to remedy these drawbacks. One is the use of oxidants. JP-A-55-98753 describes the use of a sulfur-containing organic compound in combination with an oxidizing agent.
Nos. 952 and 61-223740 describe a method for improving printing durability using iodine ions and an oxidizing agent. The removal of excess silver ions by using a chelate resin was also effective in increasing the printing durability. However, a disadvantage of these methods was that the silver image was buried in the gelatin layer and the chelating resin often adhered to the silver image, thereby reducing the ink receptivity of the silver image.

There is also a method in which various suitable compounds are used as a silver halide complexing agent. JP-A-56-1057
And JP-A-56-9750 describe a method of adding thiosalicylic acid and a substituted derivative thereof to a processing solution or a constituent layer of a printing plate. Id 56-623
Nos. 7 and 56-8145 describe a method in which thiosalicylic acid and a substituted derivative thereof are used in combination with an alkanolamine or a cyclic imide compound. With such a method, it is possible to improve the printing durability and the ink receiving ability of the silver image. However, these methods only slightly improve the printing durability and are not practically sufficient.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a silver image having good printing durability and high ink receiving ability in the development of a direct lithographic printing plate utilizing a silver complex salt diffusion transfer method. Is to provide a processing method.

[0008]

As a result of intensive studies, the present inventors have found that the object of the present invention can be achieved by adding the compound represented by the formula (1).

That is, the present invention is a method for treating a lithographic printing plate with a developer containing a compound represented by the following formula (2).

[0010]

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(Where Y is a divalent linking group having a double bond , forms a 5- to 6-membered ring, and may have a substituent.
Represents N, O, S, NR. Here, R represents a hydrogen atom or an alkyl group. )

Specific examples of the compound of formula 2 used in the present invention are shown below.

[0013]

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[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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In the present invention, the compound of formula 2 may be added with a suitable silver halide complexing agent (thiosulfate, thiocyanate, thioether, cyclic imide, thiosalicylic acid, alkanolamine, etc.). These silver halide complexing agents may be added either in the developer or in the layers of the direct printing plate.

The amount of the compound of the formula (2) of the present invention added to the developer is in the range of 10 ^-4 to 10 ^-2 mol / l, preferably 1 to 10 ^-2 mol / l.
0 ^-4 to 10 ^-3 mol / l is preferred. Also, two or more compounds can be used in combination. Although the compound of the present invention is most effectively added to a developer, it may be added to a silver halide emulsion layer or an overcoat layer of a direct printing plate. In that case, the addition amount is 10 ^{-4 to 1} mmol / m ² , preferably 10 ^{-2 to 1} mmol / m ² . Also, two or more compounds can be used in combination.

In the developing solution of the present invention, alkaline substances (such as sodium hydroxide, potassium hydroxide and sodium tertiary phosphate) and sulfites (such as potassium sulfite and sodium sulfite) as preservatives are essential. Other compounds, for example, sulfates (such as sodium sulfate and ammonium sulfate), antifoggants (such as potassium bromide), developing agents (such as hydroquinone, 1-phenyl-3-pyrazolidone and methol), development modifiers (such as polyoxyalkylenes) Compounds, onium compounds, etc.).

Further, one or more surfactants (eg, propylene glycol alginate), aminopolycarboxylates (eg, sodium ethylenediaminetetraacetate) and the like may be contained. In addition, a solvent for the compound of the present invention, for example, a water-miscible organic solvent such as methanol, ethanol, propanol, isopropyl alcohol, n-butyl alcohol, DMF, and dioxane can be contained.

In carrying out the silver complex salt diffusion transfer method, for example, British Patent Nos. 1000115 and 1012476.
Incorporation of a developing agent into a silver halide emulsion and / or an image-receiving layer or another water-permeable layer adjacent to the image-receiving layer is carried out as described in JP-A Nos. 1017273 and 1042477. I have. Therefore, in such a photosensitive material, a so-called "alkaline activating solution" containing no developing agent can be used as a processing solution for development.
The processing liquid of the present invention is effective even with such a type of photosensitive material.

As the silver halide emulsion of the lithographic printing plate used in the practice of the present invention, silver chloride, silver bromide, silver chlorobromide, silver chloroiodide and silver chlorobromoiodide can be used. Is 50
Mol% or more of silver halide. These silver halide emulsions include spectral sensitizers (spectral sensitizing dyes according to the light source and application, for example, camera type, laser light type, panchromatic type for color separation, etc.), gelatin hardener, coating aid, antifoggant , A plasticizer, a developing agent, a matting agent, and the like.

The binder used for the silver halide emulsion of the lithographic printing plate of the present invention is usually gelatin, and gelatin is partially used for starch, albumin, sodium alginate, hydroxyethylcellulose (HEC), gum arabic, and polyvinyl alcohol. (PVA), polyvinylpyrrolidone (PVP), carboxymethylcellulose (CMC), polyacrylamide, styrene-maleic anhydride copolymer, and other hydrophilic polymer binders can be substituted with one or more. Further, an aqueous dispersion (latex) of a vinyl copolymer may be used.

Under the silver halide emulsion layer (on the side of the support), an undercoat layer may be included for the purpose of improving adhesion and / or preventing halation. This layer may contain a developing agent and a matting agent. I can do it.

The support on which the silver halide emulsion is coated is
Paper, various films, plastics, paper coated with a resin-like substance, metal plate, and the like can be used.

The physical development nucleus used for the physical development nucleus layer is
Well known chemicals such as antimony, cadmium, cobalt,
Metals such as palladium, nickel, silver, lead and zinc and their sulfides can be used. The physical development nucleus layer can also contain a developing agent, and may also contain a hydrophilic binder.

[0035]

The present invention will be described in more detail with reference to the following Examples, which, of course, are not intended to limit the scope of the present invention.

A matting layer containing silica particles having an average particle size of 5 μm is provided on one side of the undertreated polyester film support, and the other side is provided with an amount of 3% in reflectance of light having a wavelength of 633 nm. 20% by weight of silica powder containing carbon black and having an average particle diameter of 7μ based on photographic gelatin
And a silica powder having an average particle size of 7 μm after chemical sensitization was added at a ratio of 5% by weight to photographic gelatin, and a spectral enhancement was performed. And a sensitive silver chloride emulsion layer (adjusted to pH 4.0). The undercoat layer contains 3.5 g / m ^{2 of} gelatin,
The emulsion layer was coated with gelatin at a ratio of 0.8 g / m ² and silver halide (converted to silver nitrate) at a ratio of 1.0 g / m ² . The undercoat layer and the emulsion layer contain formalin as a hardening agent at a ratio of 5.0 mg / g to gelatin.

After heating at 40 ° C. for 14 days after drying, a nucleus solution described in Plate No. 31 used in Example 2 of JP-A-54-103104 was applied onto the emulsion layer and dried. To produce lithographic printing plates. The silver halide emulsion was obtained by adding 4.times.10.sup. ^-6 mol of rhodium chloride per mol of silver halide at the time of physical ripening, and had an average grain size of 0.40 .mu.m. The thus obtained lithographic printing plate precursor is image-exposed with a plate-making camera having an image reversing mechanism, developed with the following developer (used solution) at 30 ° C. for 30 seconds, and subsequently with the following neutralizing solution. Processed.

Developer A Sodium hydroxide 24 g Potassium hydroxide 8 g Anhydrous sodium sulfite 50 g 2-methyl-amino-1-propanol 30 g Uracil 0.2 g Add water to make 1 liter.

Neutralizing solution Ethylene glycol 5 g Colloidal silica (20% aqueous solution) 1 g Citric acid 10 g Sodium citrate 35 g Water is added to make 1 liter.

On the other hand, in addition to the developer A, the compound 3,5,7,10,14 of the present invention was added at a ratio of 2 × 10 ^-4 mol per liter of the developer. F was prepared. Further, Comparative Compounds 15 and 16 were added at a ratio of 2 × 10 ⁻⁴ mol per 1 liter of the developing solution to prepare developing solutions G and H.

[0041]

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[0042]

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Further, instead of 2-methyl-amino-1-propanol of the developer A, 3,6-dithia-
30 g of 1,8-octanediol was added to prepare a developer I. With respect to the developing solution I, the exemplified compounds of the present invention 3,5,7,
10, 14 was added at a rate of 2 × 10 ⁻⁴ mol per liter of developer to prepare a developer JN. For comparison, developing solutions O and P were prepared by adding a comparative compound at a rate of 2 × 10 ⁻⁴ mol per liter of the developing solution.

The development was performed in exactly the same manner as the above-mentioned developer A, and a plate making process was performed. Then, the printing plate was set on an offset printing machine, the plate surface was sufficiently wetted with an etching solution having the following composition, and printing was performed using a moisturizing solution having the following composition.

Etch liquid Water 600 ml Isopropanol 400 ml Ethylene glycol 50 g

Humidification liquid Water 8 l Succinic acid 6 g Sodium sulfate 25 g Ethylene glycol 100 g Colloidal silica (20% aqueous solution) 28 g

Table 1 shows the printing results of the examples determined according to the following criteria. The printing durability of printing was determined by the following method. Printing of 1,000 to 50,000 sheets was continued, and the evaluation was made on the following four levels according to the number of printed sheets when the ink jumped out of the silver image area. A 50,000 sheets or more B 25,000 C 10,000 D 5,000

[0048]

[Table 1]

As is clear from Table 1, the lithographic printing plate obtained by adding the compound of formula 2 has a remarkably excellent silver image with excellent printing durability, and reproduces fine lines of the original well. In addition, the printing was able to withstand long printing without mechanical abrasion due to printing of the fine line portion.

[0050]

According to the lithographic printing plate prepared by the processing method of the present invention, the loss of the transferred silver image is improved, the printing durability is remarkably improved, and the ink receiving capacity is not reduced.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 7/07 G03F 7/32

Claims (1)

(57) [Claims] 1. A lithographic printing plate utilizing a silver complex salt diffusion transfer method, wherein at least one kind of a compound represented by the following formula 1 is used.
A method of processing with a contained developer . Embedded image (Wherein Y is a divalent linking group having a double bond to form a 5- to 6-membered ring, and may have a substituent. Z is N, O,
Represents S and NR. Here, R represents a hydrogen atom or an alkyl group. )