JP3237951B2 - Lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image portion that receives oily ink and an oil-repellent non-image portion that does not receive ink. Generally, the non-image portion is a hydrophilic portion that receives water. It is composed of sex parts. In normal lithographic printing, both water and ink are supplied to the plate surface, the image portion selectively receives color ink, and the non-image portion selectively receives water, and the ink on the image line is, for example, paper or the like. Printing is performed by transferring to a printing medium.

[0003] Therefore, in order to obtain good printed matter, the difference between the lipophilicity and the hydrophilicity between the image area and the non-image area is sufficiently large, and when the water and the ink are supplied to the printing plate, the image area is not sufficient. It is necessary to accept the amount of ink and not to accept the ink at all in the non-image area.

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, for example, in 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, while unexposed silver halide crystals are converted into silver salt complexes by the silver salt complexing agent in the developer and diffuse to the physical development nucleus layer on the surface to form nuclei. Causes the physical development to form an image portion mainly composed of physically developed silver having ink receptivity.

[0005] As described above, the lithographic printing plate requires gelatin-
Since the silver image deposited on the physical development nucleus layer on the silver halide emulsion layer is used as an ink-accepting image area, the image area is higher than that of a general lithographic printing plate (for example, PS plate). The parts have insufficient resistance to mechanical abrasion, and have the drawback that the image area is missing or the ink receptivity of the image area is easily lost.

If the hardness of gelatin is increased or the amount of physical development nuclei is increased in order to overcome this drawback, background staining occurs and the printing durability of the lithographic printing plate is significantly reduced.
Further, since the lithographic printing plate is stored for a long period of time from production to plate making, there is a drawback that background contamination occurs and ink receptivity is deteriorated, and improvement is desired.

The effect of surface irregularities of a lithographic printing plate on printability is known in the field of PS plates, but is also an important factor in a lithographic printing plate using the silver complex salt diffusion transfer method of the present invention. It was revealed. In particular, in a lithographic printing plate using a silver complex salt diffusion transfer method, the non-image area is mainly made of a gelatin film, and although it is originally high in hydrophilicity, it is matted to improve the printing durability of the image area. In general, the matting property of the surface is designed to be large (the surface irregularities are large) by the agent. Japanese Patent Application Nos. 3-259655, 3-268766, 3-268765, 3-2
68767 and 3-285623, by selecting a matting agent in a coating layer on the side including the silver halide emulsion layer and specifying the center line average roughness Ra value of the lithographic printing plate. It has been proposed that print stains in non-image areas can be significantly reduced.

Ink / water responsiveness is important for printing,
It is preferable that the responsiveness when setting the appropriate printing conditions by changing the ink feed and the water feed be faster. Particularly, in the field of offset rotary presses, etching with dampening water is often omitted at the start of printing to prevent paper breakage,
Ink adheres to non-image areas. Therefore, at the time of rising, the speed of ink detachment is important, and the speed of ink detachment is required. Japanese Patent Application No. 3-259655, 3-285
No. 623 discloses that improvement can be achieved by setting the gelatin content of all coating layers on the side including the silver halide emulsion layer to 5 g / m ² or less.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method which is excellent in stain resistance and printing durability.

Another object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method which is excellent in ink / water responsiveness.

[0011]

Means for Solving the Problems A polyester film coated with an organic copolymer and subjected to a hydrophilic treatment is used as a support,
In a lithographic printing plate in which at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus are sequentially coated on the support , the styrene-butadiene-based latex is added to the undercoat layer.
Containing helix and hindered formalin type hardeners
Gelatin in all coating layers on the side including the silver halide emulsion layer
Lithographic printing, characterized in that the content is 5 g / m ² or less
The above purpose can be achieved by the plate .

The styrene / butadiene type used in the present invention
The latex may be an unmodified type, but is preferably a carboxyl-modified type synthetic rubber latex. Specific examples thereof include Polylac manufactured by Mitsui Toatsu Chemicals, Nippon Zeon NIPOLE, and Nippon Synthetic Rubber JSR. The layer containing the latex may be any layer on the emulsion side, but an undercoat layer is preferred. The addition amount of latex varies depending on various conditions, but is 0.1% per m ^2.
g to 10 g, and the ratio of gelatin to gelatin is 3 to 3
00%.

The hindered formalin type hardener used in the present invention has an N-methylol group,
It is a hardener that slightly dissociates formalin. Specific examples of the hindered formalin type hardener include an initial condensate of ethylene urea and formalin as described in JP-B-57-46771, a modified polyamide-formaldehyde resin described in JP-B-62-2307, and the like. Etc.

The amount of the hindered / formalin type hardener used in the present invention varies depending on various conditions such as the type of the hardener, the pH of the coating solution, and the like.
The range is 0 mg.

Although the mechanism of action of the present invention is not clear, the presence of styrene / butadiene / latex makes gelatin having improved film properties into a favorable cross-linked state by a hindered / formalin type hardener, which shows a printing performance. I think it is improving.

In the present invention, the gelatin content of all coating layers on the side including the silver halide emulsion layer is preferably 5 g / m ² or less.

The gelatin film has a swelling property in water, and tends to slow down the ink / water responsiveness. This is a phenomenon that occurs because the gelatin film sucks in the dampening solution supplied to the plate surface until the gelatin film reaches saturated swelling, and the dampening solution does not work effectively on the plate surface. In addition, the exchange of dampening water between the plate surface and the gelatin film occurs at the same time. Therefore, if the amount of gelatin is increased, the responsiveness of the ink / water is reduced. A non-swellable latex such as styrene / butadiene latex, which hardly swells with fountain solution, hardly delays the ink / water responsiveness. Thus, it has been found that it is effective to reduce the amount of gelatin and use a styrene / butadiene-based latex instead of gelatin in order to increase the ink / water responsiveness.

The lithographic printing plate as the object of the present invention contains gelatin, and the layer containing the lithographic printing plate can be an undercoat layer, an emulsion layer, or a physical development nucleus layer. These gelatin-containing layers can also be hardened with other gelatin hardeners. Examples of gelatin hardeners other than the hindered formalin type hardener include inorganic compounds such as chrome alum, aldehydes such as formalin and glyoxal, mucochloric acid, 2,3-dihydroxy-1,4-dioxane. Dialdehydes such as 2,4-
Dichloro-6-hydroxy-S-triazine salt, 2,
Compounds having an active halogen, such as 4-dihydroxy-6-chloro-S-triazine salt, divinyl sulfone,
Divinyl ketone, N, N, N-triacroylhexahydrotriazine, compounds having two or more active three-membered ethyleneimino groups or epoxy groups in the molecule, dialdehyde starch as a polymer hardener And the like, or one or more of various compounds.

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.

A part of the gelatin in the gelatin-containing layer of the present invention is water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethylcellulose, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylamide, styrene. It can be substituted with one or more hydrophilic polymers such as maleic anhydride copolymer and polyvinyl methyl ether-maleic anhydride copolymer.

The polymer binder of the undercoat layer is generally 0.5
-5 g / m ^2, more preferably 1-4 g / m ² . Further, a photographic additive such as a developing agent can be included. The undercoat layer is disclosed in JP-A-48-5503 and JP-A-48-1002.
03, pp. 49-16507.

In the present invention, the matting agent has an average particle size of 1
Solid powder of 10 to 10 microns, for example, silica particles. In the present invention, silica particles having an average particle diameter of 1 to 5 microns are preferred. In particular, silica particles surface-treated with hydrogen fluoride are preferable because of their excellent dispersion stability. Specific examples of the silica particles include Siloid manufactured by Fuji Divison Chemical Co., Ltd.

In the present invention, the matting agent may be contained in any coating layer on the side including the silver halide emulsion layer. It can be contained in a coating layer and / or a silver halide emulsion layer. The addition amount of the matting agent varies depending on various conditions, in the range of 1 m ² per 0.1G～2.0G.

In the present invention, the lithographic printing plate preferably has a center line average roughness Ra value of 1.2 or less. The center line average roughness Ra value 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 l is extracted from the roughness curve in the direction of the center line, and the center line of the extracted portion is denoted by X.
Axis, the direction of the vertical magnification is the Y axis, and the roughness curve is y = f (x)
When represented by, the center line average roughness Ra value is expressed in units of micrometers, and can be calculated by the equation (1). The center line average roughness Ra value referred to in the present invention is a measured value when the stroke length is 2.5 mm.

[0025]

(Equation 1)

In the present invention, the undercoat layer may contain a pigment such as carbon black, a dye or the like for the purpose of preventing halation.

The silver halide emulsion layer may be, 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 the silver halide is not particularly limited, and may be cubic to tetradecahedral grains, or core-shell 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 containing 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 above 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. The physical development nucleus may or may not contain a hydrophilic binder, but gelatin, starch, dialdehyde starch, carboxymethylcellulose, gum arabic, sodium alginate, hydroxyethylcellulose, polystyrenesulfonic 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 / m2.
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 coating layer such as an undercoat layer, a silver halide emulsion layer and a physical development nucleus layer may contain some of anionic, cationic or neutral surfactants as coating aids. , An antifoggant, a thickener, an antistatic agent and the like.

As the support of the present invention, a polyester film coated with an organic copolymer and subjected to a hydrophilic treatment is used. This is one in which a subbing layer of an organic copolymer composition is provided on a polyester film after performing a surface treatment in order to increase the adhesiveness with a hydrophilic photographic layer. These are the following two. (1) A method of applying a composition comprising an organic solvent and an organic copolymer to serve as a swelling agent or a solubilizing agent for a polyester film (hereinafter referred to as a solvent subtraction method). For example, US Pat. No. 2,830,
No. 030, British Patent Nos. 772,600 and 776,1
Nos. 57 and 785,789, and JP-A-50-1718.
And No. 50-8259. (2) A method in which the composition is applied in a state of an aqueous composition of an organic copolymer (so-called latex) containing substantially no organic solvent (hereinafter referred to as an aqueous subbing method). For example, Japanese Patent Publication Nos. 44-13278 and 45
-10988, JP-A-49-11118 and 51-118
No. 27918, No. 52-114670, No. 54-11
Nos. 177, 55-67745, 58-16914
No. 5, and No. 59-77439.

The solvent undercoating method of (1) involves deterioration of the physical properties of the polyester film during the undercoating step or problems of safety and hygiene and pollution of the organic solvent due to the above-mentioned problems. It is shifting to the law.

The developing solution used in the present invention includes an alkaline substance such as sodium hydroxide, 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, a compound described in JP-A-47-26201, a developing agent such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone, a developing modifier,
For example, it can contain a polyoxyalkylene compound, an onium compound, and the like. 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 to ink receptivity or enhanced in receptivity with any known surface treating agent. Examples of such a processing solution include JP-B-48-29723 and U.S. Pat.
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. Hereinafter, the present invention will be described with reference to Examples, but it should be understood that the present invention is not limited thereto.

[0035]

【Example】

Example 1 For the purpose of hydrophilicity, an undercoat layer was formed as follows on a polyester film support which had been subjected to aqueous undercoating with an undercoat composition containing an epoxy compound disclosed in JP-A-60-213942. Apply.

<Undercoating liquid> Gelatin 2.5 g Water 20.0 g Fujiloid Davidson's syloid (grade 978, average particle size 2.5 μ) 0.6 g Carbon black dispersion (solid content 32%) 0.8 g As described in the specification of Japanese Patent No. 57-46771, an initial condensate of ethylene urea and formalin (hardening agent A) 0.5 g Grigiozar (30% aqueous solution) 0.5 g Polyrac 752A manufactured by Mitsui Toatsu Chemicals Co., Ltd. (styrene-butadiene system) Latex (solid content 47.5%) 5.0 g Surfactant 0.6 ml Add water to make the total amount 50.0 g.

The coating amount was 50 g / m ² in terms of a moisture coating amount. An ortho-sensitized high-contrast silver chloride emulsion was coated thereon at 1.5 g / m ² in terms of silver nitrate. After drying, the mixture was heated at 50 ° C. for 2 days, and then coated with a nucleus coating solution described in Example 2 of JP-A-58-21602 (polymer containing No. 3 copolymer of acrylamide and imidazole and hydroquinone as a developing agent) In a ratio of 0.8 g / m ² ) to sodium polyacrylate (average molecular weight 26000).
0) was added and adjusted in a similar manner to 0.04 g / m ^2, and applied. (Sample 1)

As a comparison, an undercoating liquid was prepared in the same manner except that Polylac 752A manufactured by Mitsui Toatsu Chemicals was not included, and was applied in the same manner. (Comparison a). An undercoating liquid was prepared in the same manner except that formalin was used in place of the above-mentioned initial condensate of ethylene urea and formalin (hereinafter referred to as hardener A), and applied in the same manner.
(Comparison b). Further, an undercoating liquid was prepared in the same manner except that polylac 752A was not contained, and formalin was used instead of the hardener A, and the coating was performed in the same manner. (Comparison c).

Each of the planographic printing plates was subjected to image exposure using an automatic plate-making machine CP-414S manufactured by Mitsubishi Paper Mills and developed. The development is performed using the following diffusion transfer developer for 3 each.
Development was performed at 0 ° C. for 15 minutes. For stabilization, each was treated with a stabilizing solution having the following composition at 25 ° C. for 10 minutes and dried.

<Diffusion Transfer Developer> Water 700 g sodium hydroxide 18 g potassium hydroxide 7 g anhydrous sodium sulfite 50 g 2-mercaptobenzoic acid 1 g uracil 10 g 2-methylaminoethanol 30 g 5-phenyl-2-mercapto-1,3,4 -Oxadiazole 0.1 g Potassium bromide 1 g Add water to make the total volume 1,000 ml.

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

The print evaluation was made by AB Dick 350
CD (trademark of offset printing machine manufactured by AB Dick)
It was used. Regarding the printing durability, after each lithographic printing plate was treated with the following desensitizing solution, using the following humidifying solution, printing was performed using Dainippon Ink Co., Ltd. New Champion Boku N, and the silver image portion was printed. The number of prints when image skipping occurred due to lack of the prints and the prints could not be used was determined according to the following evaluation criteria. (A) 20,000 or more (B) 10,000 to 20,000 (C) 5,000 to 10,000 (D) 2,000 to 5,000 (E) Less than 2,000 Table 1 shows the results.

<Desensitizing Solution> Water 600 g Isopropyl alcohol 400 g Ethylene glycol 50 g 3-mercapto-4-acetamido-5-n-heptyl-1,2,4-triazole 1 g

<Humidifying solution> O-phosphoric acid 10 g Nickel nitrate 5 g Sodium nitrite 5 g Ethylene glycol 100 g Colloidal silica (20% solution) 28 g Water is added to make 2,000 ml.

On the other hand, in order to check the water retention (dirt) of the non-image area, cycloson 23 manufactured by Fanson was used as ink.
29, and humidifier OD5 manufactured by Mitsubishi Paper Mills as the humidifier
A 2% aqueous solution of 0 was used to determine the number of printed sheets when the background was stained with AB Dick 350CD and could not be used for printing. (A) 3000 sheets or more (B) 1000-3000 sheets (C) 500-1000 sheets (D) 100-500 sheets (E) Less than 100 sheets The printing results are shown in Table 1.

Next, in order to examine the ink / water responsiveness, each of the lithographic printing plates was not treated with a desensitizing solution, and the following humidifying solution was used. And printing was performed, and evaluation was made based on the number of sheets from which dirt could be removed at the time of startup. (A) 20 sheets or less (B) 20 to 50 sheets (C) 50 to 100 sheets (D) 100 to 500 sheets (E) 500 sheets or more The printing results are shown in Table 1.

[0048]

[Table 1]

As is apparent from Table 1, Polylac 752, which is the styrene / butadiene latex of the present invention,
A and Sample 1 containing a precondensate of ethylene urea and formalin, which are hindered and formalin-type hardeners, were clearly more durable and / or durable than Comparative a, Comparative b and Comparative c.
Or it turned out to be excellent in stain resistance.

Example 2 An undercoat layer is applied on a polyester film support which has been subjected to aqueous undercoating in the same manner as in Example 1 as follows.

<Undercoat Coating Solution> Gelatin Xg Water 20.0 g Syloid (grade 978, average particle size 2.5 μ) manufactured by Fuji Divison Co., Ltd. 0.6 g Carbon black dispersion (solid content 32%) 0.8 g Tokiko Sho 62- EPINOXP-9007Y 1.5 g Grigiogizar (30% aqueous solution) 0.5 g Polylac 752A (Styrene-butadiene-based latex solid) manufactured by Dick Hercules Co., Ltd. 5.0 g Surfactant 0.6 ml Water is added to bring the total amount to 50.0 g.

The amount of coating was 50 g / m ² in terms of the amount of moisture applied. The amount of gelatin added is shown in Table 2. An ortho-sensitized high-contrast silver chloride emulsion was coated thereon at 1.5 g / m ² in terms of silver nitrate. At this time, the applied amount of gelatin was 1.0 g / m ² in solid content. After drying,
The mixture was heated at 50 ° C. for 2 days, and coated with a nucleus coating solution described in Example 2 of JP-A-58-21602 (a polymer containing a copolymer of acrylamide and imidazole of No. 3 and hydroquinone as a developing agent in an amount of 0.1%). 8 g / m ² ) and sodium polyacrylate (average molecular weight 260,000) in 0.1 g.
The added solution was adjusted in the same manner so as to have a concentration of 04 g / m ² and applied. (Samples 2, 3, 4, 5)

Thereafter, a sample was prepared in the same manner as in Example 1, and printing evaluation was performed. The results are shown in Table 2.

[0054]

[Table 2]

As is clear from Table 2, the ink / water responsiveness depends on the amount of gelatin on the emulsion side and is 5.0 g / m 2.
² The following Sample 2, Sample 3, and the sample 4 showed good ink / water responsiveness. Sample 5 of 5.0 g / m ² or more
Poor ink / water responsiveness.

[0056]

According to the present invention, a lithographic printing plate excellent in stain resistance and printing durability can be provided.
Further, a lithographic printing plate having excellent ink / water responsiveness can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 7/07 G03F 7/00 503

Claims (1)

(57) [Claims] 1. A polyester film coated with an organic copolymer and subjected to a hydrophilic treatment is used as a support, and at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus are sequentially coated on the support. at a lithographic printing plate formed by the bottom
Styrene, butadiene, latex and solder
Silver formalin type hardener and silver halide
The gelatin content of all coating layers on the side including the emulsion layer is 5 g / m
A lithographic printing plate characterized by being ² or less .