JPS62144171A - Method for processing image for lithographic printing plate - Google Patents

Abstract

PURPOSE:To improve the print resisting power of a printing plate and particularly the number of print resisting sheets for 5% dot images and >=50mum fine line by subjecting the printing plate to image exposing and developing process then processing the same with a processing liquid contg. a specific hardening agent. CONSTITUTION:A material having at least a silver halide emulsion layer and physical development nuclei layer on a base is subjected to image exposing and developing process and is then processed with the processing liquid contg. the hardening agent is the stage of manufacturing said material by a processing method in order to form the lithographic printing plate by a silver complex salt diffusion transfer method. A soln. contg. any one among aldehydes having pH=(5-8), N-methyrol compd., chlortriazines, epoxy compds., aziridines, coarbodiimides, acrylic acid deriv., vinylsulfonyl compd., and chrome alum or the mixture ecomposed thereof is prepd. as the aq. soln. The printing plate after photoengraving is immersed into such soln. and is squeezed and is further dried, by which the print resistance of the printing plate is remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (A>Field of Industrial Use) The present invention relates to a processing method for improving the printability and printing durability of a lithographic printing plate using a silver ♀11 salt diffusion transfer method.

(B) Prior art and its problems A typical implementation method of the silver salt diffusion transfer method suitable for the plate making method of lithographic printing plates includes a support and an undercoat layer thereon which also serves as antihalation. When a photosensitive material consisting of a silver halide emulsion layer and a physical development nucleus layer is imagewise exposed and developed, the silver halide forming a latent image becomes blackened silver in the emulsion layer.

At the same time, silver halide on which no latent image has been formed is dissolved by the action of the silver halide marking agent contained in the processing solution.
It diffuses onto the surface of the photosensitive material.

The silver complex salt that has been dissolved and diffused is deposited as a silver image on the physical development nuclei in the surface layer by the reducing action of the developing agent. In order to avoid enhancing the ink receptivity of the resulting silver image, the silver image is developed and, if necessary, subjected to an oil sensitization treatment, and then transferred to an offset printing press to transfer the ink image to a printed matter.

A printing plate in which a silver image obtained by the silver-111 salt diffusion transfer method, which is one of such photographic reproduction methods, can be used as an offset printing plate has already been published in Japanese Patent Publication No. 46-43132 or ,! Ire' [Publication 1972-
It is listed in 30562@.

The printing plate developed by the diffusion transfer method has high sensitivity,
Printing that has the characteristics of high WI image power and high image reproducibility, or is inferior in terms of printing durability compared to other commercially available printing plates (e.g. PS plates), and has improved printing durability. Version requested.

After that, in order to improve the printing durability, we take into consideration factors such as the current image quality, the production conditions of transferred silver particles in the processing process, such as the diffusion rate, stability, or reduction rate of silver complex salts. (1
Japanese Patent Publication No. 56-1057 has been reported as a processing liquid for printing plates in which the addition of curing agents and additives has been investigated, but it has not achieved sufficiently satisfactory printing durability.

The poor print image reproducibility as well as the printing durability of such printing plates is strongly dependent on the process of photo-processing and plate-making, and especially on the development process. Conditions and the form of the binder in each layer (for example, pyratine in the emulsion layer) from a microscopic point of view after development processing are major factors that affect printing characteristics and image reproducibility. Furthermore, the structural properties and compressive strength of each binder due to strong alkali treatment are important factors.

Regarding the practical printing durability of this printing plate, the practical printing durability limit of 5% halftone image of 200 (line 7 inch) or more is 500 sheets in terms of image and crease reproducibility when printing is performed. This is inevitable, and if the manuscript's crease line is less than 50 ml, the reproduced crease line on the printing plate becomes thinner due to light scattering, which is the fate of the printing process, so the silver on the plate flies off during printing, making it impossible to reproduce the thin line. It becomes impossible. However, by the postdural treatment used in the present invention, the 5
% halftone image and fine line reproducibility.

Furthermore, as a method of realizing image reinforcement as in the present invention, it is considered to increase the amount of hardening agent during printing plate production to increase the printing durability. I was unable to raise the issue and hire the company.

(C) Purpose of the Invention The present invention provides a method for extremely improving the printing durability of such printing plates, particularly the number of printings of 5% halftone images and fine lines of 501 I/n or less.

(D> Structure of the Invention The present invention provides a method for preparing a lithographic printing plate using a silver salt diffusion transfer method using a material having at least a silver halide emulsion layer and a physical development nucleus layer on a support. exposure,
This is a lithographic printing plate making method characterized by processing with a processing solution containing a hardening agent after development.

As an aqueous solution, pl-1 = (5-8) aldehyde'M,
A solution containing one or a mixture of N-methylol compounds, chlor-1-riazines, ebogish compounds, aziridines, carbodiimides, acrylic derivatives, vinylsulfonyl compounds, and chromium alum is prepared, and printing after plate making is carried out. By immersing the plate in this solution, squeezing it, and then drying it, the printing durability of the printing plate is significantly improved.

A feature of the present invention is that the strong alkali treatment of the printing plate causes disturbance in the relatin dura structure of the emulsion layer, resulting in a decrease in film quality and a slightly alkaline tinge. Therefore, the objective is to lower the I)l-f of the emulsion layer, uniformly reproduce the hardening structure, and improve the crushing strength of silver on the surface of the printing plate.

Examples of preferable compounds that can be used in carrying out the present invention include the following, but the compounds are not limited thereto.

1. Formalin (aldehyde) 2. Crotonaldehyde (″) 3. Glyoxal (〃) 4. Glytaraldehyde (〈″) 5. υ-Cucinaldegyde (″) 6. Mucochloric acid (″) Ctl□OH 8,2 ,4-dichloro-6-hydroxy-s-triazine sodium (chlor1-riazine)9.2-chloro-
4,6-cyhydroxy-S-triazine ``Kum (
Chlor 1~Ryazine) 10゜(epoxy) (aziridine) 12, dicyclohexylcarbodiimide (carbodiimide) COCl=CH2(acrylic acid) 1 4, CH2= CIISO2ell□QC)
I2302CIl=CI+2 (vinylsulfonyl) 1 5 , M"Cr(SO2)z ・12HzO (chromium alum) However, Mt is a monovalent metal ion (including ammonium ion). Also, the amount of this hardening agent used is 1ρ Hit 10-
3 to 10-''M is preferred.

Lithographic stamp used in carrying out the present invention'. The silver halide emulsion for the i version can be silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, etc., and preferably silver chloride or 50
Cover with more than mol% of silver halide.

These silver halide emulsions may contain conventional emulsion additives such as spectral sensitizers, ceratin hardeners, coating aids, antifoggants, plasticizers, developers, and the like.

Binders for the silver halide emulsions can be natural and/or synthetic binders commonly used for this purpose, such as gelatin, colloidal albumin, cellulose derivatives, and the like.

Below the silver halide emulsion layer (support side), a subbing layer for improving adhesion and/or an undercoating layer for the purpose of preventing halation may be provided, and this layer may also contain a developer.

The support coated with a silver halide emulsion can be paper, various films, Plus Deck, paper coated with a resin-like substance,
Gold layer etc. can be used.

Physical development nuclei used in the physical development nucleus layer are well-known examples of this type of chemicals, including gold layers and their sulfides such as antimony, bismuth cadmium, cobalt, palladium, nickel, silver, lead, and zinc. or can be used.

This physical development nucleus layer may also contain a developer or a hydrophilic binder.

(E) Example A matting layer containing silica particles having an average particle size of 5IJIn was provided on one side of a subbed-treated polyester film support, and a matting layer containing carbon black on the other side was applied to the photographic ceratin. An antihalation undercoat layer (pl-14) containing 20% by weight of wrinkle strength powder with an average particle size of 71M1
．． 0) and a spectrally sensitized high-sensitivity silver iodochloride emulsion containing silica powder with an average grain size of 7/jm at a strain ratio of 5% to photographic ceratin after being chemically sensitized with a gold compound. layer (r] adjusted to -44.0) was provided.

The gelatin of the undercoat layer is 3. Ot3/Td, the gelatin in the emulsion layer was coated at a ratio of 1.0 s/6 moxibusted silver halide (1.0 a/m2). This undercoat layer and emulsion layer were Formalin as an agent for gelatin
．． Contains in an amount of 0m3/Utiradin. 40 after drying
After heating at C for 14 days, a core coating solution (the polymer is a copolymer of NO3 acrylamide and imidazole, The silver halide used to produce a lithographic printing plate was a silver iodochloride emulsion containing 2 mol% of silver iodide (this silver halide contained an average grain With a diameter of 0.3IJIn, ±30 of the average particle size
After chemical ripening using ordinary gold sensitization method and M[yellow sensitization method], Divide the emulsion.

Furthermore, using a sensitizing dye, the color is sensitized panchromatically,
A lithographic printing plate was produced by the method described above. Next, in order to examine the printing characteristics, a camera processor was placed on the plate using CP-404-I.
(manufactured by Inu Nippon Screen) was closely exposed to light and developed.

Development treatment after exposure was performed using the following diffusion transfer developer.

<Transfer developer> Water 700 ml After the image processing, the original plate was passed between two squeezing rollers,
The excess developer was removed, and immediately treated with a neutralizing solution having the following composition at 25° C. for 20 seconds, the excess solution was removed with a squeezing roller, and the product was dried at the lowest temperature.

<Neutralizing liquid> Dilute a predetermined amount of the embedding agent used in the present invention with water as shown in Table 1 to give a concentration of 1ρ, and after adjusting it to pl-(6,0), fill a fixing processor with a fast wave. This was used to redistribute the printed printing plate.

Table 1 shows the results of the ink receptivity, printing durability (reproducibility of 5% halftone images and crease lines of 701I111 or less), and stain evaluation of each printing plate using the various processing agents of the present invention.

b) The number of prints until the paper is fed at the same time as the inked roller comes into contact with the ink-receptive plate surface and a print is obtained with a good image temperature.

(1) Printing durability a) Image reproduction printing durability 11 times for printing up to 3000 sheets, gray contact 1 to screen 100.133.150.175 and 200 lines/inch, fine halftone dots ( 5% dot) could be reproduced clearly and clearly. Rating 1 (100 lines/inch) to 5 (20
0/inch).

b>c gland reproduction printing durability 70.60.50.40, and 3oIIIt
Up to 3,000 sheets were printed using a reflection-printed manuscript, and the thickness of the horizontal lines was clearly reproduced, resulting in a rating of 1.
1IIi1 (70II/n) ~ Rating 5 (30IIIn>
It was expressed in five stages.

c) Evaluation of stain resistance and water retention) 3QOO sheets were printed and evaluated on the following three scales based on the degree of stain on the printed matter.

1) Full-scale overflow stains occur.

2) Partial or light stains occur.

3) No dirt is generated at all.

As can be understood from Table 1 above, the processing method according to the present invention has improved printing durability (
It can be seen that the number of printing sheets that could have been improved is maintained.

Table 1

Claims (1)

[Claims] (1) When producing a material having at least a silver halide emulsion layer and a physical development nucleus layer on a support into a lithographic printing plate using a silver complex salt diffusion transfer method, after image exposure and development processing, the following [I] A lithographic printing plate making method characterized by processing with a processing liquid containing at least one hardening agent described in . [I] Aldehydes, chlortriazines, epoxy compounds, aziridines, carbodiimides, acrylic acid derivatives, vinylsulfonyl compounds, and chromium alum.