JPS62105150A - Lithographic printing plate - Google Patents

Abstract

PURPOSE:To obtain a lithographic printing plate which has the high sensitivity to permit the use of low-output semiconductor laser light, has high resolving power and high print resisting power and utilizes a silver complex salt diffusion transfer method and a photoengraving method without ground staining by incorporating specific sensitizing dyes into the silver halide mulsion layer of the lithographic printing plate. CONSTITUTION:The lithographic printing plate having at least the silver halide emulsion layer and surface physical development nucleus layer on a base contains at least one sensitizing dye expressed by the formula in the emulsion layer. In the formula, R1 denotes an alkyl group, alkenyl group, R3 denotes a hydrogen group, alkyl group, aryl group, X denotes an acid anion. The sensitizing dye is added to the silver halide emulsion at an optional timing until the emulsion is coated and the amt. of said dye to be added is in 1X10<-5>-1X10<-2>mol range for each 1mol silver halide. The lithographic printing plate has the extremely high sensitivity to light of the wavelength longer than 700mmu, more particularly semiconductor laser light of >=750mmu and has high print resisting power and excellent shelf stability.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Field of Application The present invention relates to a lithographic printing plate using a silver complex diffusion transfer method suitable for using laser light, particularly semiconductor laser light as a light source, and a plate-making method thereof. (B) Prior art and its problems @ Planographic printing plates in which the transferred silver image obtained by the complex salt diffusion transfer method can be used immediately as ink receptivity have already been published in Japanese Patent Publications No. 48-30562 and No. 53-2160.
2, 1972-103104, 1977-9750, etc., and are well known.

41 suitable for the surface plate method of such lithographic printing plates! According to a typical implementation method of the complex salt diffusion transfer method, a photosensitive material consisting of a support, an undercoat layer for preventing halation on the support, a silver halide emulsion layer, and physical development nuclei Ifj is imagewise exposed and developed. When the image processing is carried out, the silver halide on which the latent image has been formed becomes blackened silver in the emulsion r@. At the same time, silver halide on which no latent image has been formed is dissolved by the action of a silver halide complexing agent contained in the processing solution and diffused 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.

After development and, if necessary, a sensitization treatment to enhance the ink receptivity of the resulting silver image, it is placed in an offset printing press and the ink image is transferred to a printed product.

In the conventional method, the silver halide emulsion layer is spectrally sensitized using merocyanine dyes, cyanine dyes, etc. so that it has a sensitivity maximum in the green region around 550 nm, and then the silver halide emulsion layer is spectrally sensitized using a merocyanine dye, cyanine dye, etc. so that it has a maximum sensitivity in the green region around 550 nm. Exposures of ~tens of seconds were given. However, the above conventional method has limitations even though the lithographic printing plate originally has excellent sharpness and resolution.

Moreover, if one tries to obtain color printed matter from a color original, there are still problems in that not only the resolution is insufficient, but also the production of printing plates and plate-making operations are complicated.

Today, as one method for solving the above-mentioned problems, plate making using laser light has been proposed.

For example, U.S. Patent No. 4,501,811, JP-A-59
-71055, 1986-75838, 1986-10
No. 0148 and the like disclose a lithographic printing plate for use in helium-neon lasers or light-emitting diodes.

As described in these patent specifications, in these 11th lithographic printing plates using the silver complex diffusion transfer method, surface physical development nuclei have a large effect on spectral sensitization, and as a result, the target laser beam As a result of the formation of a soft transferred deposited silver image due to silver complex salt diffusion transfer development, the sharpness and
In order to obtain the desired high-quality lithographic printing plate, the resolution is reduced, and furthermore, background stains occur, and the silver image appears during printing, making it impossible to obtain sufficient printing durability. It is difficult to do so. Therefore, a sensitizing dye that meets these requirements must not only have sufficiently high sensitivity at the wavelength of laser light, but also have good storage stability and the ability to form a high-contrast transferred deposited silver image. It must be free of negative effects such as scumming, and must be completely free of scales, forming a strong transfer deposit that cannot be removed during printing even with minute amounts of silver.

There are many powerful types of lasers, but methods that use helium-neon, argon, or other laser light sources as scanner-type light sources can provide high output, but the equipment is large and has a high power consumption. , has drawbacks such as low Se power consumption efficiency. On the other hand, semiconductor lasers have advantages such as being small, inexpensive, easy to modulate, and have a long life. Semiconductor laser has Q a / A a / P i
G a / A no / A a i Ga / A s
Semiconductors of systems such as iIn/PiIn/As are used, and the wavelength of this laser light is generally 7
There are many wavelengths longer than 00 mμ, especially wavelengths longer than 750 mμ.

Such long wavelength semiconductor laser light is li! ili[
A photosensitive lithographic printing plate used as a light source for exposure is described, for example, in % Dosho 60-61752.

This patent specification describes, as a particularly preferred embodiment, a non-silver photosensitive layer (such as O
- A photosensitive lithographic printing plate having a photosensitive layer consisting of a naphthoquinonediazide compound and a photosensitive silver halide emulsion is disclosed, and sensitization with extremely thick spectral sensitivity in a wavelength region longer than 700 mμ used in such an emulsion layer is disclosed. The pigment has the general formula [
I] to (IV). Also, among these, certain cyanine dyes are used as silver halide photographic materials for semiconductor lasers in Japanese Patent Application Laid-Open No. 59-19103.
2, a specific example is disclosed in 1982-192242.

However, the present inventors have discovered that many infrared sensitizing dyes, including the sensitizing dyes specifically shown in these patent specifications, have a physical development nucleus layer as the outermost surface layer described above. When incorporated into the silver halide emulsion layer of a lithographic printing plate, it was found that the sensitivity was insufficient for plate making using a semiconductor laser source.
In many cases, only lithographic printing plates with poor resolution and printing durability were obtained.

(C) Purpose of the Invention The purpose of the present invention is to use a silver complex diffusion transfer method that has high sensitivity that can use a low-output semi-4-body laser beam, has high resolution, 1-quadrant power, high printing durability, and is free from scumming. An object of the present invention is to provide a lithographic printing plate and a plate-making method using the same.

(D) Constitution of the Invention The above object of the present torch was achieved by incorporating a sensitizing dye described later into the silver halide emulsion layer of the lithographic printing plate. That is, the present invention provides a lithographic printing plate having at least a silver halide emulsion layer and a surface physical development nucleus layer on a support, in which at least one sensitizing dye represented by the following general formula (r) is added to the emulsion layer. This is a lithographic printing plate characterized by containing:

General formula CI) Summer FL! Yes, X is a sulfur atom, selenium atom, oxygen atom, N-R
, (R represents an alkyl group), and FL4 and R5 represent a hydrogen atom, an alkyl group, or an aryl group; however, R4 and a cannot be hydrogen atoms at the same time)
, ■ represents an alkyl group, an alkoxy group, an aryl group, an alkoxycarbonyl group, an alkenyl group, a carboxyl group, a hydroxy group, or a halogen atom, and n 0 or 1 to 4
and when n is 0, a naphthoazole ring is formed.R and 几represent an alkyl group or an alkenyl group. R8 is a hydrogen atom, an alkyl group,
Represents an aryl group. X represents a silicate anion, and t is 1
or 2. ] Specific examples of penta-membered compounds of A include thiazole, benzothiazole, naphtho[1,2-α]thiazole, natuto[2,1-α]thiazole, natuto[2
゜3-α] Thiazole, selenazole, benzoselenazole, naphthoC2,1-α]selenazole, naphthoC1
,2-α]selenazole, oxazole, benzoxazole, nut[1,2-α]oxazole, naph)C
Examples include 2,1-α]oxazole, naph)[:2,3-α]oxazole, and benzimidazole.

几, and at least one of R and R1 is an alkyl group (for example, methyl, ethyl, butyl, etc.) or an aryl group (for example, phenyl, tolyl, etc.), and in both cases, they may be different.

The substituent represented by (2) is an alkyl group (for example,
methyl, ethyl, butyl, trifluoromethyl, hydroxymethyl, methoxyethyl, benzyl, etc.), alkoxy groups (e.g., methoxy, ethoxy, butoxy, etc.), aryl groups (e.g., phenyl, tolyl, etc.), alkoxycarbonyl groups (e.g., methoxycarbonyl, ethoxycarbonyl, etc.), alkenyl groups (e.g. allyl, etc.),
Carboxy groups, hydroxy groups, halogen atoms (e.g.
(chlorine, bromine, iodine, fluorine), and n is preferably 1 or 2, and when it is 0, a naphthoazole ring is formed.

In R8 and R1, the alkyl group includes lower alkyl groups such as methyl, ethyl, propyl, butyl, hydroxyalkyl groups such as β-hydroxyethyl and r-hydroxypropyl, β-methoxyethyl, r-methoxyethyl, etc. alkoxyalkyl group, β-acetoxyethyl, r
- Acyloxyalkyl groups such as acetoxypropyl and β-benzoyloxyethyl, carboxyalkyl groups such as carboxymethyl and β-carboxyethyl, alkoxycarbonylalkyl groups such as methoxycarbonylmethyl, ethoxycarbonylmethyl and β-ethoxycarbonylethyl, β-sulfoethyl Examples of alkenyl groups include nosulfoalkyl groups such as , r-sulfopropyl and δ-sulfobutyl, aralkyl groups such as benzyl, phenethyl and sulfobenzyl, and allyl.

As 几, mention may be made of a hydrogen atom, an alkyl group as mentioned above for R, and R, and an aryl group such as phenyl, tolyl, methoxyphenyl, chlorophenyl, and naphthyl.

Examples of the acid anion of 0, which does not exist in the case of 0. Representative examples of the sensitizing dyes used in the present invention are shown below.

(!-t) tH5 knee Cl-2) S.O.

(I-4) 80° Cl-5] [4-6] S.O.

[x-7] ■− (t-8) ("l-9) knee C knee 1o) S.O.

(I-12) (3H.

The sensitizing dye used in the present invention can be synthesized by methods known to those skilled in the art. The time of addition to the silver halide emulsion can be during the incubation period before the emulsion is coated. The amount added can vary within a wide range, but good results have been obtained from 1 x 10 to
It is in the range of 1×10 mol. The optimum amount to be added varies depending on the conditions of the silver halide emulsion, such as the halogen composition, the average grain size of the silver halide grains, and the crystal habit.

The silver halide emulsion of the lithographic printing plate of the present invention can be silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, etc., and preferably silver chloride is a halogen containing 50 mol% or more. It is chemical silver. The average particle size of these silver halide grains is preferably in the range of 0.2 to 0.8 microns, but ranges other than this can also be used. Furthermore, for silver halide, more than 90% of the total grain number is ±30% of the average grain size.
A monodispersed emulsion having a particle size within the range of 100 to 100% is preferable. Although silver halide grains are preferably substantially cubic or tetradecahedral, silver halide having other crystal habits may also be used.

The binder used in the silver halide emulsion of the lithographic printing plate of the present invention is usually gelatin. , carboxymethyl cellulose, polyacrylamide, styrene-maleic anhydride copolymer, polyvinyl methyl ether-maleic anhydride copolymer, and the like can be substituted with one or more hydrophilic polymer binders. Furthermore, an aqueous vinyl polymer dispersion (latex) can also be used.

Silver halide emulsions can be sensitized in a variety of ways when they are manufactured or coated. For example, by sodium thiosulfate, alkylthiourea,
Alternatively, it is preferable to chemically sensitize by a method well known in the art, such as with a gold compound such as gold rhodan, gold chloride, or a combination of both.

Also, at any time during the production of silver halide emulsions, compounds of metals belonging to Group 1 of the periodic table, such as cobalt,
By using salts such as nickel, rhodium, palladium, iridium, platinum, etc., it is possible to obtain properties particularly favorable for printing plates for direct plate making, such as high sensitivity, high sharpness, and high resolution. The amount of addition is in the range of 10-8 to 10-s mol per mol of silver halide.

The silver halide emulsion layer contains other additives such as coating aids, hardeners, antifoggants, matting agents (water retention agents),
It may contain conventional additives such as developing agents.

On the underside of the silver halide emulsion layer (support 11411), a subbing layer or subcoating that may contain a carbon black colorant or a compound that absorbs light of 700 μm or more to improve adhesion) x can also be provided, and this layer can also contain a developing agent, a matting agent, and the like.

The image-receiving layer is provided above the silver halide emulsion layer, that is, as the outermost surface layer.

The image-receiving layer is provided above the silver halide emulsion layer, that is, as the outermost surface layer.

As the physical development nucleus, known metals such as antimony, bismuth, cadmium, cobalt, palladium, nickel, silver, lead, zinc, and their sulfides can be used. The image-receiving layer contains hydrophilic colloids such as gelatin, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl starch, dialdehyde starch, dextrin, hydroxyethyl cellulose, polystyrene sulfonic acid, a copolymer of vinylimidazole and acrylamide, and polyvinyl alcohol. It may contain one or more types of Keyaki.

The hydrophilic colloid contained in the image receiving layer is 0.1 g/m''
It is preferable that it is below.

Hygroscopic substances such as wetting agents such as vinyl, glycerol, etc. may be present in the image-receiving layer. Furthermore, the image-receiving layer may also contain pigments for preventing scumming such as barium sulfate, titanium dioxide, china clay, and silver, developing agents such as hydroquinone, and hardening agents such as formaldehyde and dichloro-S-triazine.

The support may be, for example, paper, a film such as a cellulose acetate film, a polyvinyl acetal film, a polystyrene film, a polypropylene film, a polyethylene terephthalate film, or a composite film coated with a polyethylene film such as a polyester, polypropylene or polystyrene film, gold scrap, metal. It can be a support of synthetic paper or metal/paper laminate. Paper supports coated on one or both sides with an alpha-olefin polymer, such as polyethylene, are also useful. These supports include
A compound having an ability to prevent haleyshiron may be mixed.

The developing solution used in the present invention includes alkaline substances such as sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, etc., sulfite groups as preservatives, silver halide bath agents, etc. Thiosulfate, thiocyanine [
4. Cyclic imide, thiosalicylic acid, amine, etc., thickening agent,
For example, hydroxyethyl cellulose, carboxymethyl cellulose, antifoggants such as potassium bromide, 1-
Phenyl-5-mercaptotetrazole, JP-A-47-
26201, developers such as hydroquinone, 1-phenyl-3-pyrazolidone, development modifiers such as polyoxyalkylene compounds, onium compounds, and the like.

In implementing the silver complex diffusion transfer method, for example, British Patent Nos. 1,000,1.15, 1,012°476, 1,017,273, 1,042,477, etc. As described in the specification of 1999, it has been practiced to incorporate the entire developer into the silver halide emulsion layer and/or the image receiving layer or other water permeable layer adjacent thereto. Therefore,
For such materials, the processing solution used in the development step may be a so-called "alkaline activation α" which does not contain a developer. The ink receptivity can be converted or enhanced by compounds such as those described in Japanese Patent Publication No. 48-29723, US Pat. No. 3,721,539, and the like.

The desensitizing liquid, dampening liquid, etc. used in the printing method can be prepared by commonly known methods.

(E) Examples The present invention will be explained below using examples, but it is of course not limited thereto.

Example 1 A matting layer containing silica particles with an average particle size of 5 μm was provided on one side of a subbed polyester film support, and a carbon blank was provided on the opposite side, containing 20% by weight of photographic gelatin. An undercoat layer containing silica powder with an average particle size of 7IIm (adjusted to pH 4.0) and silica powder with an average particle size of 7am after being chemically sensitized with a gold compound at a ratio of 51% to photographic gelatin. A spectrally sensitized highly sensitive summer silver iodobromide emulsion layer containing (5 mol% Br, I O
, 4 mol%, adjusted to pH 4.0 with 0A94.6 mol%)
and has been established.

Gelatin for the undercoat layer is 3. OJl/rn', gelatin in the emulsion layer is 1. OJI/m", silver halide converted to silver nitrate 1.0 g/m". This undercoat 1 and emulsion layer were prepared using formalin as a hardening agent and gelatin as a hardening agent.
Contains an amount of 0'F/g gelatin. After drying 4
After heating at 0° C. for 14 days, a core coating solution (polymer is a combination of acrylamide and imidazole in T's, 3) described in Example 2 of JP-A-53-21602 was applied on top of this emulsion layer. Polymer (containing hydroquinone at a ratio of 0.811/rn'') was coated and dried to produce a lithographic printing plate.

The silver halide emulsion was prepared by adding 5 x 10 moles of salt 1 hhydrodium per mole of silver halide during physical ripening, and had an average grain size of 03 microns, ±3 of the average grain size.
It was a substantially cubic crystal with 90% or more of the total number of particles distributed in the 0% range.

As sensitizing dyes used in silver halide emulsions, the dyes shown in Table 1 below were added to a dark red filter (Fuji Photo Film Mso-70) that transmits light with a wavelength longer than about 700 mμ per mole of silver halide. , thin line surface Il! A film manuscript including the above-mentioned materials was given, and the prints were made to have approximately the same degree of printing, and this was used as a sample for a printing test.On the other hand, a dark red filter (So-70) was used as the light source.

After exposure, development was performed using the following diffusion transfer developer.

<Transfer developer> After the development process, the original plate was completely passed between two squeezing rollers to remove excess developer (148!), immediately treated with a neutralizing solution having the following composition at 25°C for 20 seconds, and then passed through the squeezing rollers. Excess liquid was removed and dried at room temperature.

Neutralizing Solution> The sensitivity and printing durability of each lithographic printing plate are shown in Table WJ1. Sensitivity is expressed as a relative value, with the sensitizing dye (I-1) taken as 1.0 by the exposure amount required to stop forming transferred deposited silver. This sheet 1f was attached to an offset printing machine, the following desensitized fL was applied all over the plate surface, and printing was carried out using the following dampening liquid.

The printing machine was a Niepee Dick 3500D (A-B-
Using DICk's offset printing machine, the printing durability was evaluated based on the number of sheets that could not be printed due to scumming or silver scattering, and was shown in the right column of Table 1. There is.

1.4,000 sheets or less 2.4. OOO ~ 6,000 pieces 3.6,000~s, ooo sheets 4.8,000~10,000 sheets 5. More than 10,000 sheets Non-greasy liquid> Humidifying liquid> Add water to obtain 2).

The following dyes were used for comparison.

(Al 1 (Fl) n04H @ 1 (D) so30,
H.

knee (K) O2H.

Table 1 Example 2 A plain printing plate was prepared in the same manner as in Example 1 except that a chloriodide emulsion containing 3 mol % of gO iodide was used. However, the sensitizing dyes listed in Table 2 below were used. Hereinafter, Example 1
The body plate was prepared and printed according to the following procedure to obtain the results shown in Table 2. The sensitivity is a relative value with the value of the sensitizing dye Cl-1) set as 1.0.

Table 2 Example 3 Each sample of Examples 1 and 2 was heated at 50°C and 80% RH.
After being stored for several days, a similar test was conducted and found that the comparison sample suffered from even more significant desensitization and no longer exhibited substantial sensitivity to light with an ifJ of 780 mμ, whereas the inventive sample had a desensitization rate of up to about 10%. It had good storage stability.

(k') Effects of the invention The lithographic printing plate of the invention can absorb light with a wavelength longer than 700 roμ.
In particular, it has extremely high sensitivity to semiconductor laser light of 750 mμ or more, has high printing durability, and has excellent storage stability.

Claims (1)

[Claims] (1) In a lithographic printing plate having at least a silver halide emulsion layer and a physical development nucleus layer as a surface layer on a support,
A lithographic printing plate characterized in that the emulsion layer contains at least one sensitizing dye represented by the following general formula [I]. General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, A is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and X is a sulfur atom , selenium atom, oxygen atom, >N-
R_6 (R_6 represents an alkyl group), R
_4 and R_5 represent a hydrogen atom, an alkyl group, an aryl group (however, R_4 and R_5 cannot be hydrogen atoms at the same time), V is an alkyl group, an alkoxy group, an aryl group, an alkoxycarbonyl group, an alkenyl group, It represents a carboxyl group, a hydroxyl group, or a halogen atom, and n represents 0 or an integer of 1 to 4, and when n is 0, a naphthoazole ring is formed. R_1 and R_2 are
Represents an alkyl group or an alkenyl group. R_3 represents a hydrogen atom, an alkyl group, or an aryl group. X represents an acid anion, and g represents 1 or 2. ]