JPS585424B2 - Method for manufacturing lithographic printing plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a lithographic printing plate that uses a silver image to make it receptive to ink, and particularly relates to a method for manufacturing a lithographic printing plate that is free from scumming and has dramatically improved printing durability. .

Printing plates having high sensitivity and spectrally sensitized using L-crystalline silver halide emulsions have already been put into practical use in several forms.

Among these, offset printing plates that utilize silver images to make them ink receptive include U.S. Patent No. 3,721,559;
U.S. Patent No. 3,490,905, U.S. Patent Publication No. 48-30562, U.S. Patent No. 3,385,701, U.S. Patent No. 3,814,
No. 603, JP 44-27242, JP 53-2
1602, U.S. Patent No. 3,454,398, U.S. Patent No. 3
．． No. 764,323, No. 3,099,209, and Japanese Unexamined Patent Publication No. 53-9603.

Although these printing plate manufacturing methods are roughly divided into several types, they have in common that they make silver receptive to ink.

A lithographic printing plate consists of a oleophilic printing area that accepts oil-based ink and a hydrophilic non-printing area that does not accept ink, and the non-printing area generally consists of a hydrophilic area that receives water. be done.

Therefore, in normal lithographic printing, both water and ink are supplied to the print, and the image area selectively receives colored ink and the non-image area receives water, and the ink on the image line is, for example, This is done by transferring it to a substrate such as paper.

In order to obtain good prints, the difference in lipophilicity and hydrophilicity between the surface of the image area and the background non-image area must be sufficiently large so that when water and ink are applied, the image area receives a sufficient amount of ink. It is necessary that the non-image areas receive no ink at all, and desirably, it is necessary that this effect lasts for as many printed materials as possible.

The method for manufacturing printing plates using silver halide emulsions described above is simple, reliable, rapid, can be automated, and has the characteristics of high sensitivity, high resolution, and high image reproducibility. For example, compared to the printing plates (PS plates) that have been realized which are essentially made of dichromate-sensitized hydrophilic colloids and diazo-sensitized organic colloids, it is difficult to print a larger number of sheets, which is the so-called durability. There is something lacking in terms of printing power.

The purpose of the present invention is to have good ink adhesion, no scumming,
The present invention provides a method for producing a lithographic printing plate in which a silver image with dramatically improved printing durability is used as ink receptivity.

In the method for producing a lithographic printing plate according to the present invention, the silver or/silver halide image formed to receive ink has at least one mercapto group or thione group and at least one hydrophilic group in the molecule. It basically consists of bringing the compound and the oxidizing agent into contact with each other.

Examples of organic compounds having a mercapto group or a thione group and a hydrophilic group in the molecule include 2-mercaptoethanol,
Hydroxymercaptans such as α-thioglycerin, thioglycolic acid, α-mercaptopropionic acid, β-mercaptopropionic acid, α-mercaptobutyric acid, β-mercaptobutyric acid, γ-mercaptobutyric acid, bis(mercaptomethyl)acetic acid, α-mercapto mercaptoalkyl carboxylic acids and their derivatives, such as caproic acid and cysteine;
Mercaptoalkylsulfonic acids such as 2-mercaptoethylsulfonic acid, mercaptopropylsulfonic acid, mercaptobutylsulfonic acid, 2,3-dimercaptopropanesulfonic acid, P-mercaptobenzoic acid, P-mercaptobenzenesulfonic acid, m-mercaptobenzene Sulfonic acid, 2-mercaptobenzimidazole-5-sulfonic acid, ■-methylbenzothiazole-5-sulfonic acid-2
Compounds containing aromatic rings or heterocyclic rings such as -thione, 2-mercaptobenzimidazole-5-sulfonic acid, 1-methylbenzothiazole-5-sulfonic acid-2-thione, and mercaptobenzenecarboxylic acid; 51
-62723, the following compounds having a mercapto group and an ethylene oxide unit, H8CH2CH2C00(CH2CH20)nCOCH
2CH2SHH8CH2COO(CH2CH20)nC
OCH2SHCI2H25S(CH2CH20)ncO
cCH2CH2SHH8CH2CH20 (CH2CH20
)nCH2CH2SHC12H250(CH2CH20
)nCH2CH2SH Furthermore, the above polymer includes a group capable of forming a mercapto group, such as disulfide, and the following compounds in which the introduced mercapto group is protected, for example.

CH3CO8CH2COO(CH2CH20)nCOC
H2SCOCH3C12H25S(CH2CH20)n
cOcH2SCONHC2H6 In the formula, n and n1tn2 are determined by the average degree of polymerization of the raw material polyethylene glycol, and represent an integer of 4 to 120 or more.

Examples of other polymers having a mercapto group and a hydrophilic group include polyvinyl alcohol described in "Poval (Kobunshi Kagaku Kankai, written by Kiyoshi Hirabayashi, 1952)", pages 75 to 77, and the above-mentioned mercapto group. Also effective are ester compounds with compounds having carboxylic acid or sulfonic acid, and polymers obtained by esterifying a copolymer of methyl vinyl ether and maleic anhydride with Thiog IK roll.

In short, any organic compound containing at least one mercapto group or thione group and at least one hydrophilic group (carboxyl group, sulfo group, hydroxyl group, ethylene oxide group, etc.) in the molecule can be a low-molecular compound or a high-molecular compound. do not have.

Among the above-mentioned compounds, a polymer having ethylene oxide units is disclosed in JP-A-51-62723 along with its synthesis method.

In addition, the above-mentioned compounds were developed by the applicant in Japanese Patent Publication No. 51-15
No. 761 and Japanese Patent Application No. 118766/1989,
It was proposed as a so-called image correcting agent that makes unnecessary parts of the silver image area of lithographic printing presses, which are used to make recorded images ink receptive, ink repellent (hydrophilic).

These compounds are thought to have a mercapto group bonded to the silver image formed on the printing plate, and one hydrophilic group imparts ink repellency, and the ink repellency, or correction effect, is remarkable. It is.

The present invention provides a lithographic plate having significantly improved ink receptivity in the silver image area and dramatic printing durability by using a compound and an oxidizing agent that originally make the silver image area ink repellent as described above. We discovered the unexpected and surprising fact that a printed version can be obtained.

It has not yet been clearly elucidated why the effects of the present invention are obtained.

However, as far as we can infer from the compounds described below,
It has been found that compounds that interact with either the silver image or a compound having a mercapto group and a hydrophilic group, that is, a compound that has an oxidizing effect, are preferable.

Therefore, the term oxidizing agent is used in the claims.

Oxidizing agents are generally well known substances.

In the present invention, the following substances have been found to be particularly preferable oxidizing agents.

(1) Second metal ion: First metal ion, that is, excluding the metal ion with the highest valence, for example, Cu+2
．． AI+3. Tt+3. Cr+3. C4+61Mn+4
゜Mn+7. Ce"4.Rh+3.Pb', Pd+2.
Pd+4°co+3. ■γ+3. Fe+3. Ni+3.
sn+4. ■+4°Bi+3. Mo+3. Mo+5. P
t+4. Ru+4. Te +”.

W+4, and these metal ions are halogen salts,
It can be used as water-soluble nitrates and sulfates, but in the case of water-insoluble or poorly soluble organic solvents such as alcohols such as methanol, ethanol, and ingropanol, dimethylformamide, dioxane, Acetone or the like may also be used, and in some cases, an organic solvent immiscible with water may also be used.

(2) Halogens: chlorine, bromine, iodine (3) Halogen acids: hypohalous acids, such as potassium hypochlorite, hypoiodium slag, hypobromite slag, etc., halogen acids , such as sodium chlorate, potassium iodate, sodium bromate, perhalogenesic acids, such as orthoperiodic acid (u, 106), sodium metaperiodate (NaIO3), N-halocarboxylic acid amides,
For example, N-bromoacetamide, N-bromosuccinimide, N-halosulfonamide, such as N-chloro-P-toluenesulfonamide (chloramine T), N-
Chlorobenzenesulfonamide (chloramine B), etc.
Hypohalous acid esters, such as t-butyl hypochlorite, can be used in an aqueous solution, in an organic solvent miscible with water, or in some cases, in a solvent immiscible with water.

Particularly preferred are CL+2 (cupric chloride, copper nitrate, etc.), Au+3 (chlorometal, etc.), T7+3 (thallium nitrate, etc.), Cr+6 (potassium dichromate, etc.), Mn+7 (potassium permanganate, etc.) , Fe+3
(ferric chloride, ferric sulfate, ferric salt of ethylenediaminetetraacetic acid, etc.), Cσ+3 (such as cobalt (■) complexes as described in JP-A-48-9729), Pb+2 (
palladium chloride, etc.) and Ni+3. Ce+4. Ir
+3, etc., and halogens, halogen acids, hypohalous acids, and the like.

In the present invention, it is applied to the production of the known planographic printing plates mentioned above.

Lithographic printing plates that use a silver image as ink receptive include those that use the silver diffusion transfer method described in Japanese Patent Publication No. 48-30562, and those that use silver halide as ink receptivity include , for example, in Japanese Patent Application Laid-Open No. 53-9603.

After imagewise exposure, these lithographic printing plates are developed with a conventional developer, such as D-72 developer or silver diffusion transfer developer, to form a /SO-generated silver image or a metallic silver image for receiving ink. formed and, if necessary, enhances ink receptivity.

In the present invention, it is necessary that the three compounds mentioned above be present in contact with the silver image formed to receive the ink.

Therefore, the above-mentioned three compounds, especially the compounds having a mercapto group and a hydrophilic group, are used in the production process of light-sensitive materials for planographic printing plates, such as silver halide emulsions, undercoat layers, physical development nucleus-containing layers, etc. It can also be contained in the constituent layers.

In addition, the three compounds can be included in photolithographic processing solutions such as developing solution, stop solution, and fixing solution, or in various processing solutions used in printing process steps such as desensitizing solution and dampening solution. Special treatment solutions can also be created for application of the three-way compound.

The three compounds can be brought into contact with the formed silver image in the manner described above, and preferably the three compounds are allowed to act separately.

More preferably, the compound having a mercapto group and a hydrophilic group is reacted first.

The amount of the compound having a mercapto group and a hydrophilic group contained in the constituent layers of the printing plate is about 0.001 g/m'' to about 5
! /m2, and the concentration range of about 0.1% to about 20% is practically appropriate for the amount contained in various processing solutions.

It is practically preferable that the amount of the oxidizing agent contained in the various processing solutions is from about 1% to the saturation concentration of the oxidizing agent, preferably about 3% or more.

In the method of the present invention, it is preferred to use a silver halide emulsion to form an ink-receptive silver image, although silver images can also be formed by other methods.

For example, a method known as the RS process,
In this method, a printing original plate having a coating containing a photoactivatable vine semiconductor such as titanium dioxide is prepared, and after image exposure, it is immersed in a redox type developer such as silver nitrate and metol to form a metallic silver image.

The silver halide emulsion may be present in the printing plate itself or on a separate negative sheet as a source of silver for a printing plate sheet having an image-receiving layer by a silver diffusion transfer method.

The silver halide emulsion may be silver bromide, silver bromide, silver chlorobromide, or any of these containing iodide, and the binder thereof is preferably gelatin, but some or all of the gelatin may be substituted with other colloidal substances. , for example, casein, albumin, polyvinyl alcohol, polyvinyl alcohol-maleic anhydride, cellulose derivatives, acrylamide-vinylimidazole copolymers, and the like.

Silver halide is 0.5 to 7 g/m21 in terms of silver nitrate
The binder can normally be used in a range of 0.5 to 10 g/m2.

The silver halide emulsion can be manufactured by a method known in the ordinary photographic industry, and the manufacturing method for use in printing plates is also disclosed in the above-mentioned known patent documents, so please refer to them. be able to.

The lithographic printing plate used in the present invention is generally treated with an alkaline developer after image exposure, followed by plate-making and printing processes such as a neutralizing liquid, a fixing liquid, a desensitizing liquid, an etching liquid, and a dampening liquid, if necessary. will be applied.

Any such developer may be used, such as a normal photographic alkaline developer containing a developing agent such as hydroquinone, a developer for silver diffusion transfer method containing hypo, etc., or a high alkaline developer containing these as an activator. I can do it.

Among the various developers used in the present invention, for example,
No. 1-486 and Japanese Patent Application No. 51-67409, organic compounds having a mercapto group or thione group and compounds having a heterocyclic group having a sulfur atom that improve the ink receiving ability of the image area are used. When it is contained, the difference in lipophilicity and hydrophilicity between the printed area and the non-printed area becomes significant.

The composition of the neutralization, fixing, desensitizing, etching, or dampening liquid used in the present invention depends on the purpose and type of plate material, but in general, these processing liquids It is preferable to modify the treatment activity by incorporating conventionally known substances such as the above-mentioned mercapto organic compounds, desensitization promoters, buffers, preservatives, and wetting agents.

For example, gum arabic, carboxymethyl cellulose,
Sodium alginate, vinyl pyrrolidone, vinyl imidazole, copolymer of methyl vinyl ether g maleic anhydride, carboxymethyl starch, ammonium alginate, oquindide cellulose alginate, methyl cellulose, sulfate (sodium sulfate, ammonium sulfate, etc.), phosphoric acid, nitric acid , nitrous acid, tannic acid and their salts, polyol compounds having at least two hydroxyl groups (polyethylene glycol, glopylene glycol, pentaerythriol, glycerol, diethylene glycol, hexylene glycol, etc.), organic weak acids (citric acid, succinic acid, tartaric acid, adipic acid, ascorbic acid, propionic acid, etc.) inorganic fine particles (colloidal silica, alumina, etc.), polyacrylic acid, ammonium dichromate, chromium alum, alkynoic acid propylene glycol ester, amine polycarboxylate By adding one or more of surfactants (such as ethylenediaminetetraacetic acid sodium salt), a plate-making and printing processing liquid that more completely satisfies the objectives of the present invention can be obtained.

In addition, a small amount of a water-miscible organic solvent such as methanol, dimethylformamide, or dioxane, or a coloring agent such as phthalocyanine dye, malachite green, or ultramarine may be added in consideration of the distinctive appearance of the liquid.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited only to these Examples.

Example 1 A matting layer containing silica particles with an average particle size of 5 μm was provided on one side of a 135 g/m2 double-sided polyethylene coated paper, and an antihalation layer containing carbon black was provided on the other side after corona discharge machining. , an ortho-sensitized high-contrast silver chlorobromide emulsion containing silica particles with an average grain size of 5 microns thereon with a silver nitrate concentration of 1.09/
m'' was applied.

The antihalation layer and emulsion layer contain formaldehyde as a hardening agent.

After drying and heating at 40C for 3 days, a sulfurized palladium sulfide sol prepared by the method described below was applied onto this emulsion layer at a speed of 5 m/min.

Preparation of palladium sulfide sol Mix solutions A and B with stirring, and after 30 minutes pass through a column containing an ion exchange resin made for pure water production for purification. Add solution C to make the coating solution. And so.

Copolymer of methyl vinyl ether and maleic anhydride (1.25%) 100nlCM
10% saponin solution 200. l water
18.000R1 The lithographic printing plate original plate thus obtained was subjected to image exposure using a letterpress camera having an image reversal mechanism, and developed for 60 seconds at 30° C. using the following silver complex salt diffusion transfer developer.

After the transfer developer development process, the original plate is passed between two squeezing rollers to remove excess developer, and immediately treated with a neutralizing solution having the following composition at 25°C for 20 seconds, and the excess liquid is removed using a squeezing roller. was removed and dried at room temperature and humidity.

Let's call it printing version A. Neutralizing solution Mount the lithographic printing plate A prepared by the above operations on an offset printing machine, apply the following desensitizing solution all over the plate surface,
Printing was performed using the following dampening liquid.

Desensitizing liquid dampening liquid (to use, dilute 10 times with water) The printing machine is NIP Dick 350CD (A-BD
Ink receptivity, ease of staining, and printing durability were determined using the following method.

1) Ink reception characteristics Using F-gloss ink as the ink, paper feeding begins at the same time as the inked roller contacts the plate surface, and the number of prints until a print with good image density is obtained.

2) Evaluation of stains Using F gloss composition ink, 1.
000 sheets were printed, and the following three levels were evaluated based on the degree of staining of the printed matter.

○ No stains occur at all.

Δ Partial or light stains × Full-scale light stains 3) Printing durability The following 3 types of printing durability are determined depending on the number of sheets printed when ink skips in the recorded image area or stains appear in the non-image area after printing more than i, ooo sheets. It was evaluated on two levels.

Δ 2,000 sheets or less 02,000 to 5,000 sheets ◎ 5,000 sheets or more On the other hand, a lithographic printing plate prepared in the same manner except that 5 ml of thioglycolic acid was added to the neutralizing solution was designated as B.

After further treatment with the neutralizing solution containing thioglycolic acid, the printing plate A
A lithographic printing plate manufactured in the same manner as B is designated as C-G.

The results obtained are shown in Table 1. Furthermore, the evaluation of the printing plate treated with a neutralizing solution containing no thioglycolic acid and then treated with second steel chloride was almost the same as that of printing plate A.

Example 2 Example 1 was repeated.

However, instead of thioglycolic acid, a neutralizing solution containing 10 g μ of β-mercaptopropionic acid and an oxidizing agent shown in Table 2 below were used.

Example 3 A gelatin basecoat containing silica particles (average size 5 microns) and carbon black was coated onto corona discharge machined polyethylene coated paper.

Further, formalin and dimethylol urea were added as colloid hardening agents.

The amount of gelatin and silica deposited was 1.2 grams and 10.7 grams per square meter, respectively.

The layer also exhibited a reflection density of 0.9. Subsequently, an ortho-sensitized, high-cost silver halide emulsion containing formalin and dimethylol urea as colloidal hardeners was coated on the undercoat layer.

After drying, it was heated at 40°C for 2 days.

The emulsion layer had the following structure.

Silver halide composition Chlorobromide (silver bromide 25 mol%) Average particle size of silver halide 0.33μ Silver halide coverage expressed in silver nitrate 1.2gβ Gelatin coverage 0.7g/m2 Silica (
Average size: 5 .mu.) Coverage rate: 0.1 g/m2 After imagewise exposure, the photographic material thus obtained was developed at 25 DEG C. for 30 seconds in a D-72 developer.

The excess developer was removed by squeezing, followed by immersion in 256C for 30 seconds in the following treatment solution (a), followed by immersion in treatment solution (b) for several seconds and squeezing.

Processing liquid (a) Processing liquid (b) Printing plates were prepared in the same manner using Compound A of processing liquid (a) and the oxidizing agent of processing liquid (b) shown in Table 3, and used in Example 1. It was printed using a printing press.

The results are shown in Table 3.

Note (1): H8CH2CH2C00 (CH2CH20)
45COCH2CH2SH Note (3) II 0.1 Normal concentration

Claims (1)

[Scope of Claims] 1. In a method for producing a lithographic printing plate in which a silver image is used as ink receptive, the silver image formed to accept ink has at least one mercapto group or thione group in its molecule. 1. A method for producing a lithographic printing plate, characterized in that a compound having at least one hydrophilic group and an oxidizing agent are brought into contact with each other. 2. The manufacturing method according to claim 1, wherein the oxidizing agent is selected from a second metal ion, a halogen, and a halogenic acid.