JPH09160251A - Method for making planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing plate which has excellent image quality (the image quality on planographic printing plates and printing quality) and flaw resistance and is formed by using a silver complex salt diffusion transfer method. SOLUTION: This plate making method comprises successively applying at least one undercoating layers, silver halide emulsion layers and physical development nucleus layers on a base. The center line average height Ra value thereof is specified to <=0.6. The planographic printing plate is made by subjecting the plate to diffusion transfer development processing in the presence of the following thion compd.: The compd. has thion groups which are not enolized. The compd. has substd. nitrogen atoms expressed by >N-R adjacent to these thion groups and the balance consist of the atom groups necessary for forming a 5-or 6-membered ring selected from (substd.) carbon, nitrogen, oxygen and sulfur atoms expressed by the R described above. This ring does not have an arom. condensed ring. Further, the R has 1 to 4 pieces of carbon atoms or a substituent having no carbon atoms.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a silver complex salt diffusion transfer method (D
The present invention relates to a lithographic printing plate and a plate making method to which the TR method) is applied.

[0002]

2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image-forming portion that accepts oil-based ink and an oil-repellent non-image-forming portion that does not receive ink. It is composed of sex parts. In ordinary lithographic printing, both water and ink are supplied to the plate surface, the image area selectively receives the coloring ink, and the non-image area selectively receives water, and the ink on the image area, such as paper Printing is performed by transferring it to a printing medium. Therefore, in order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity between the image area and the non-image area is sufficiently large, and when water and ink are supplied to the plate surface,
It is necessary that the image area receives a sufficient amount of ink and the non-image area does not receive ink at all.

A lithographic printing plate using a silver complex salt diffusion transfer method (DTR method), particularly a lithographic printing plate having a physical development nucleus layer on a silver halide emulsion layer is disclosed in, for example, US Pat.
No. 8,114, No. 4,134,769, No. 4-1
No. 60,670, No. 4,336,321, No. 4,
Nos. 501,811, 4,510,228, and 4,621,041, and the like. The exposed silver halide crystal undergoes chemical development by DTR development to produce a black color. It becomes silver and forms a hydrophilic non-image area.On the other hand, unexposed silver halide crystals are converted into a silver salt complex by a silver salt complexing agent in a developing solution and diffused to the physical development nucleus layer on the surface to form nuclei. Causes physical development to form an image portion mainly composed of physically developed silver having ink receptivity.

The influence of the surface irregularities of the lithographic printing plate on the printability is well known in the field of PS plates, but it is also an important factor in the lithographic printing plate using the silver complex salt diffusion transfer method of the present invention. Are known. In particular, in a lithographic printing plate using the silver complex salt diffusion transfer method, the non-image area is mainly composed of a gelatin film, and although it is originally highly hydrophilic, it is used to improve the printing durability of the image area. It was general that the agent is designed to have a large matte surface (large unevenness on the surface). In US Pat. No. 5,281,509, it is disclosed that there is a correlation between the matteness of the surface and the print stain, and by smoothing the surface, the print stain in the non-image area can be greatly reduced. It was disclosed.

However, although smoothing the surface was effective in improving print stains, scratches were likely to occur on the plate surface during development processing during plate making, especially by processing with an automatic developing machine. This phenomenon tends to occur particularly when a polyester film is used as a support, and the scratches appear on the image portion in an overlapping manner, which is a serious defect in practical use.

Further, recently, due to the diversification of automatic developing machines and the like, they are more severely handled than ever, and scratches are more likely to occur. Further, in recent years, while demands for high image quality and high definition printing have increased more than ever, the same demands have been made for lithographic printing plates using the silver complex salt diffusion transfer method. Particularly, in order to improve the image quality of the planographic printing plate (the image quality on the planographic printing plate and the printing image quality), it is important to reduce the surface roughness, and therefore smoothing has become an essential condition. Therefore, there is a demand for a lithographic printing plate using a silver complex salt diffusion transfer method that has scratch resistance that can withstand such practically necessary processing conditions and that has excellent image quality.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lithographic printing plate making method using a silver complex salt diffusion transfer method, which is excellent in image quality (image quality on lithographic printing plate and printing image quality). Is.

Still another object of the present invention is to provide a method for making a lithographic printing plate using a silver complex salt diffusion transfer method which is excellent in scratch resistance.

Further objects and advantages of the present invention will be understood from the description in the following specification.

[0010]

A planographic printing plate in which at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer are sequentially coated on a support and a center line average roughness Ra value is 0.6 or less. In the plate-making method, a thione group that does not enolize is present, a substituted nitrogen atom represented by> N-R is provided next to the thione group, and the rest are the substituents represented by R. Consisting of a group of atoms necessary for forming a 5- or 6-membered ring selected from carbon, nitrogen, oxygen, and sulfur atoms, which may have, wherein the ring does not have an aromatic condensed ring, Furthermore, said R has 1 to 4 carbon atoms,
Alternatively, it was achieved by a diffusion transfer development treatment in the presence of a thione compound which is a substituent having no carbon atom.

That is, the surface of the lithographic printing plate is made smooth (center line average roughness of 0.6 or less) so as not to adversely affect image reproducibility, and further development processing is performed in the presence of the thione compound. Dense silver complex salt diffusion transfer silver (DTR
It is realized by transferring (silver).

The image quality of the lithographic printing plate is largely influenced by the constituent factors (surface property) of the lithographic printing plate, but other than that, even if silver is transferred to the printing plate with high image quality, the image on the printed matter is Does not appear, which depends on the size and shape of the transferred silver particles, which change depending on the production conditions of the transferred silver particles (diffusion rate, stability, reduction rate of silver complex salt, etc.).

The improvement of the image quality, which depends on the size and shape of the transferred silver particles, is improved by the conventional surface lithographic printing plate.
Since the surface roughness (central average roughness) is large and a factor for that is strong, it was not effective as a means for improving the image quality. However, in order to cope with high image quality, high definition printing and color printing in recent years, a lithographic printing plate having a smooth surface for the purpose of improving image quality is effective as a useful means for further improving the image quality. Is.

Center line average roughness (Ra value) of the present invention is 0.6.
The following lithographic printing plate may be achieved by simply reducing the amount of the matting agent on the side containing the silver halide emulsion layer or not adding it, but preferably a small matting agent (average particle size) is used. 3 micron or less) in a state of being dispersed in the form of single particles to achieve a smooth printing plate surface having an Ra value of 0.6 or less.

In the present invention, the center line average roughness Ra value of the lithographic printing plate can be measured by using a surface roughness profile measuring instrument, for example, Surfcom 500B manufactured by Tokyo Seimitsu Co., Ltd. A portion having a measurement length 1 is extracted from the roughness curve in the direction of the center line, the center line of the extracted portion is set as the X axis, the direction of the vertical magnification is set as the Y axis, and the roughness curve is expressed as y = f (x). Then, the center line average roughness Ra value is expressed in units of micrometers, and can be calculated by the equation (1).

[0016]

[Equation 1]

The provision of a lithographic printing plate excellent in scratch resistance, which is the other object, can also be achieved by the transfer of dense DTR silver according to the present invention.

The compound used in the present invention has a thione group which is not enolized, and next to the thione group,>
It has a substituted nitrogen atom represented by NR and the rest are
It is composed of an atomic group necessary for forming a 5- or 6-membered heterocyclic ring selected from carbon, nitrogen, oxygen, and sulfur atoms which may have a substituent represented by R, and the ring is an aromatic condensed ring. R is a thione compound which has no ring and is a substituent having 1 to 4 carbon atoms or having no carbon atoms.

The characteristics of the compound used in the present invention are:
(1) having at least one non-enolizable thione group, (2) being a heterocyclic compound having no aromatic condensed ring, (3) next to the thione group, a nitrogen atom having a substituent is present. It is present, and (4) none of the substituents should have a group having 5 or more carbon atoms, for example, an alkyl group or an aryl group.

The compound used in the present invention can be represented by the following general formula (1).

[0021]

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Z is an atomic group necessary for forming a 5- or 6-membered ring selected from C, N, O and S atoms, R may be different from each other, and the substituent n defined above is 0. ~
Represents an integer of 4.

Typical examples used in the present invention are shown below. Of course, it is not limited to this.

[0024]

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[0025]

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[0026]

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[0027]

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[0028]

[Chemical 6]

[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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The amount of the thione compound used in the present invention can be used in the range of 0.1 to 5.0 g / l in the case of the diffusion transfer developer. In this case, the developing solution is preferably an alkali activating solution, but may be an alkaline developing solution containing a main developing agent. For printing materials, optional constituent layers (silver halide emulsion layer, undercoat layer, physical development nucleus layer)
Can be used in at least one layer of 0.005 to 1 g / m ² . Further, two or more kinds of thione compounds can be used in combination. Of course, other organic compounds having a mercapto group or a thione group can also be used.

Japanese Examined Patent Publication (Kokoku) No. 61-52466 discloses that high printing durability can be obtained by performing development processing by the DTR method in the presence of a thione compound, but the effect of the thione compound in the present invention is This can be achieved only by smoothing the surface of the planographic printing plate, and the conventional planographic printing plate having a rough surface cannot obtain the effect on the image quality.

The lithographic printing plate which is the object of the present invention contains gelatin, and the layer containing the gelatin may be an undercoat layer, an emulsion layer or a physical development nucleus layer. These gelatin-containing layers can be hardened with a gelatin hardener.
Examples of the gelatin hardener include inorganic compounds such as chromium alum, aldehydes such as formalin, glyoxal, malealdehyde and glutaraldehyde, N-methylol compounds such as urea and ethyleneurea, mucochloric acid, 2,3. Aldehydes such as dihydroxy-1,4-dioxane, 2,4-dichloro-6-hydroxy-
Compounds having an active halogen such as S-triazine salts and 2,4-dihydroxy-6-chloro-S-triazine salts, divinyl sulfone, divinyl ketone and N, N, N
-Triacroylhexahydrotriazine, compounds having two or more active three-membered ethyleneimino groups or epoxy groups in the molecule, one of various compounds such as dialdehyde starch as a polymer hardener, or Two or more kinds can be used.

The hardener can be added to all layers or to some or only one layer.
Of course, in the case of two-layer simultaneous application, the diffusible hardener can be added to only one of the layers. The addition method can be added at the time of emulsion production or in-line at the time of coating.

The undercoat layer may contain pigments such as carbon black and dyes for the purpose of preventing halation. Further, photographic additives such as developing agents can be included. Further, the undercoat layer is disclosed in JP-A-48-5503 and JP-A-48-10020.
3, such as those described in JP-A-49-16507.

The silver halide emulsion layer includes, for example, silver chloride,
It consists of silver bromide, silver chlorobromide, and those containing silver iodide. The silver halide crystal may contain a heavy metal salt such as a rhodium salt, an iridium salt, a palladium salt, a ruthenium salt, a nickel salt, a platinum salt, and the like, in an amount of 10 ^-8 to 10 ^-3 per mol of silver halide. Is a mole. The crystal form of silver halide is not particularly limited, and may be cubic or tetradecahedral grains, or core-shell type or tabular grains. The silver halide crystal may be a monodisperse or polydisperse crystal,
Its average particle size is in the range of 0.2-0.8 μm. One preferred example is a monodispersed or polydispersed crystal containing 80 mol% or more of silver chloride, which contains a rhodium salt or an iridium salt.

The silver halide emulsion can be sensitized in various ways as it is manufactured or coated. It is preferred to chemically sensitize by methods well known in the art such as, for example, with sodium thiosulfate, alkyl thioureas, or with gold compounds such as rhodium gold, gold chloride, or a combination of both. Silver halide emulsions can also be sensitized or desensitized positively or negatively by dyes such as cyanine, merocyanine and the like. There is no particular limitation on the wavelength range in which the sensitization or desensitization can be performed. Therefore, orthosensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization, and semiconductor laser sensitization can be performed, and UV sensitization and visible light reduction for a bright room can be performed. You can feel it.

The surface layer present on top of the emulsion layer contains physical development nuclei. As physical development nuclei, silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold, platinum and other metal colloid fine particles, and sulfides, polysulfides, selenides of these metals, or those It may be a mixture or a mixed crystal. Physical development nuclei may or may not contain a hydrophilic binder, but gelatin, starch, dialdehyde starch, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, polystyrene sulfonic acid, sodium polyacrylate, vinyl It may contain a copolymer of imidazole and acrylamide, a copolymer of acrylic acid and acrylamide, a hydrophilic polymer such as polyvinyl alcohol or an oligomer thereof, and the content thereof is 0.5 g / m.
It is preferably ² or less. Further, the physical development nucleus layer may contain a developing agent such as hydroquinone, methylhydroquinone, or catechol, or a known hardener such as formalin or dichloro-s-triazine.

Each of the coating layers such as the undercoat layer, the silver halide emulsion layer and the physical development nucleus layer may contain some of anionic, cationic or neutral surfactants as coating aids. , Antifoggants, matting agents, thickeners, antistatic agents and the like.

As the support used in the lithographic printing plate of the present invention, resin-coated paper having both surfaces or one surface coated with a polyolefin resin, a polyester film, a polyester film having a hydrophilic surface, a surface-treated aluminum plate, etc. There is. These supports may contain pigments for preventing halation and solid fine particles for improving the surface properties. Further, the support may be light-transmissive so that backside exposure is possible. Among these, a polyester film is particularly preferably used.

The developing solution used in the present invention contains an alkaline substance such as sodium hydroxide or potassium hydroxide,
Lithium hydroxide, tribasic sodium phosphate, etc., sulfites as preservatives, silver halide solvents such as thiosulfate,
Thiocyanates, cyclic imides, 2-mercaptobenzoic acid, amines and the like, thickeners such as hydroxyethylcellulose, carboxymethylcellulose and the like, antifoggants,
For example, potassium bromide, the compounds described in JP-A-47-26201, developers, such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone, development modifiers,
For example, a polyoxyalkylene compound and an onium compound can be included. Further, as the developing solution, a compound or the like described in U.S. Pat. No. 3,776,728 which improves the ink running of the surface silver layer can be used.

The surface silver layer after development of the lithographic printing plate of the present invention can be converted into ink receptivity or the receptivity can be enhanced by any known surface treatment agent. Examples of such treatment liquid include Japanese Patent Publication No. 48-29723 and U.S. Pat. No. 3,7.
21, 559 and the like. The printing method, the desensitizing solution, the humidifying solution, and the like to be used can be a commonly known method.

[0050]

EXAMPLES The present invention will be described below with reference to examples, but of course the present invention is not limited thereto.

Example 1 An undercoat layer was coated as follows on a polyester film support which had been subjected to an aqueous undercoating treatment with an undercoating composition containing an epoxy compound disclosed in JP-A-60-213942 for the purpose of hydrophilization. To do.

<Undercoat Layer Coating Liquid> Gelatin 15 g Water 200 g Silica particles: (Shinogi Pharmaceutical Co., Ltd. FPS-101 average particle size 1.1 μm, Fuji Silysia Chemical Ltd. SY-445 average particle size 3.5 μm) Xg Water 160 g Carbon black dispersion (solid content 32%) 8 g Formaldehyde (30% aqueous solution) 2 g Gliogisar (30% aqueous solution) 4 g Surfactant 6 ml Water is added to bring the total amount to 600 g.

By changing the particle size of silica and the amount of silica added,
Each undercoat layer coating solution was prepared. The coating amount was 60 g / m ^{2 in} terms of moisture coating amount. The ortho-sensitized high-contrast silver chloride emulsion on the above-mentioned undercoat layer is converted into silver nitrate to 1.5.
g / m ^2, it was coated with a gelatin amount 0.8 g / m ^2. After drying, the mixture was heated at 50 ° C. for 2 days, and the core coating solution described in Example 2 of JP-A-58-21602 (containing a copolymer of acrylamide and imidazole of No. 3 as a polymer and hydroquinone as a developing agent) was used. Is included at a rate of 0.8 g / m ² )
A solution obtained by adding sodium polyacrylate (average molecular weight 260,000) to 0.04 g / m ² was similarly prepared and applied.

The center line average roughness Ra value of the finished planographic printing plate is as shown in Table 2.

Each of the above lithographic printing plates was image-exposed using a plate-making camera processor CP-610S manufactured by Mitsubishi Paper Mills Co., Ltd., and developed with the following diffusion transfer developing solution at 30 ° C. for 20 minutes. Stabilization was carried out by treating with a stabilizing solution having the following composition at 25 ° C. for 20 seconds and drying. The following tests were performed on each of the obtained lithographic printing plates. Tables 2 and 3 show the results.

<Diffusion Transfer Developer> Water 700 g Sodium hydroxide 18 g Potassium hydroxide 7 g Anhydrous sodium sulfite 50 g 2-Mercaptobenzoic acid 1 g 2-Methylaminoethanol 30 g Organic compound 1 g Water is added to bring the total volume to 1,000 ml.

The above-mentioned organic compounds represent the thione compounds used in the present invention and comparative compounds, and the treatment liquids a to j were prepared by changing them. The results are shown in Table 1 below.

[0058]

[Table 1]

[0059]

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[0060]

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[0061]

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[0062]

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<Stabilizing Solution> Water 600 g Citric acid 10 g Sodium citrate 35 g Colloidal silica (20%) 5 g Ethylene glycol 5 g Water is added to bring the total volume to 1,000 ml.

[0064]

[Table 2]

The image quality on the planographic printing plate was judged by the following evaluation criteria by taking an enlarged photograph of the surface of the planographic printing plate and observing the shape of the net with 150 lines and 50%. (A) Reproduce a halftone dot with a clear contour. (B) The contour is a half-blurred halftone dot. (C) The outline becomes a blurred halftone dot. (D) Each halftone dot has an indeterminate shape.

The printing evaluation is AB Dick 350.
CD (trademark of AB Dick offset printing machine)
It was used. In order to check the stain resistance of the non-image area, F gloss purple 68S made by Dainippon Ink is used as the ink, 2.5% KPS # 500 aqueous solution of Rossos Co. is used as the moisturizing liquid, and AB Dick350CD stains the background. The number of printed sheets when they were generated and could not be used for printing was judged according to the following evaluation criteria. (A) 3000 sheets or more (B) 1000 to 3000 sheets (C) 500 to 1000 sheets (D) 100 to 500 sheets (E) Less than 100 sheets

The scratch resistance was evaluated based on the level of scratches generated on the plate surface after the development processing was carried out by the processor. (A) The plate surface is not scratched at all. (B) There are very thin scratches on the plate. (C) A slight scar is seen during printing. (D) The scars are clearly visible during printing.

The print image quality was evaluated by taking a magnified photograph of the surface of the printed matter, observing the shape of the net with 150 lines and 50%, and judging by the following evaluation criteria. (A) Reproduce a halftone dot with a clear contour. (B) The contour is a half-blurred halftone dot. (C) The outline becomes a blurred halftone dot. (D) Each halftone dot has an indeterminate shape.

[0069]

[Table 3]

From the above results, excellent image quality can be obtained while maintaining high scratch resistance and stain resistance by developing the surface of the lithographic printing plate smooth and developing it with the processing solution containing the thione compound of the present invention. I understand.

Example 2 An undercoat layer was coated as follows on a polyester film support which had been subjected to an aqueous undercoating treatment with an undercoating composition containing an epoxy compound disclosed in JP-A-60-213942 for the purpose of hydrophilization. To do.

<Undercoat layer coating liquid> Gelatin 15 g Water 200 g Silica particles: (Shionogi Pharmaceutical Co., Ltd. FPS-101) 25 g Water 160 g Carbon black dispersion (solid content 32%) 8 g Formaldehyde (30% aqueous solution) 2 g Gliogizar (30% aqueous solution) 4 g Surfactant 6 ml Water is added to bring the total amount to 600 g.

The coating amount is 60 g / m ² in terms of moisture coating amount. An ortho-sensitized high-contrast silver chloride emulsion was coated on the undercoat layer in an amount of 1.5 g / m ² in terms of silver nitrate and a gelatin amount of 0.8 g / m ² . After drying, the mixture was heated at 50 ° C. for 2 days, and the core coating solution described in Example 2 of JP-A-58-21602 (containing a copolymer of acrylamide and imidazole of No. 3 as a polymer and hydroquinone as a developing agent) was used. In an amount of 0.8 g / m ² ) and 0.04 g / m ^{2 of} sodium polyacrylate (average molecular weight 260000)
The thione compound of the present invention and the comparative compound were added in an amount of 0.15 g / m ² to the solution. Table 4 shows the added thione compounds.

[0074]

[Table 4]

Each of the planographic printing plates was image-exposed using a plate-making camera processor CP-610S manufactured by Mitsubishi Paper Mills Co., Ltd. The development processing was carried out by using the diffusion transfer developing solution of a in Table 1 of Example 1 at 30 ° C. for 20 minutes. Stabilization was performed in the same manner as in Example 1, dried, and each lithographic printing plate obtained was subjected to the same test as in Example 1. Table 5 shows the results.

[0076]

[Table 5]

From the above results, even when the thione compound of the present invention is added to the lithographic printing material, the effect is exhibited. Of course, the surface properties of the lithographic printing plate must be smooth.

[0078]

By using the present invention, it is possible to provide a lithographic printing plate using the silver complex salt diffusion transfer method which is excellent in image quality (image quality on the lithographic printing plate and printing image quality) and scratch resistance.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Miyazaki 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills, Ltd.

Claims (1)

[Claims] 1. At least one subbing layer on a support,
In a plate making method of a lithographic printing plate in which a silver halide emulsion layer and a physical development nucleus layer are sequentially coated and a center line average roughness Ra value is 0.6 or less, a thione group which does not enolize is contained. Next to, has a substituted nitrogen atom represented by> N-R, and the rest is selected from carbon, nitrogen, oxygen and sulfur atoms which may have the substituent represented by R. It consists of a group of atoms necessary to form a 5- or 6-membered ring, said ring does not have an aromatic condensed ring, and said R has 1 to 4 carbon atoms, or a carbon atom. A plate-making method for a lithographic printing plate, which comprises performing a diffusion transfer development treatment in the presence of a thione compound which is a substituent having no.