JP3301854B2 - 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 comprises 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 the image 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.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 effect of surface irregularities of a lithographic printing plate on printability is known in the field of PS plates, but it 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, 3-268765, 3-268765, 3-2
68767, same Hei 3-268766, same Hei 3-2856
No. 23 discloses that there is a correlation between the matt property of the surface and the print smear, and that the smoothing of the surface can significantly reduce the print smear of the non-image area.

[0006] However, although the smoothing of the surface has been effective in improving the printing stain, in the development processing step at the time of plate making, scratches are more likely to occur on the plate surface particularly in the processing by an automatic developing machine. The abrasion appears on the image area and is a serious defect in practical use. In addition, due to recent expansion of processing methods and diversification of automatic developing machines, they have been subjected to more severe handling than has been conventionally performed, so that scratches are more likely to occur. Therefore, there is a demand for a lithographic printing plate using a silver complex salt diffusion transfer method having an excellent quality of scratch resistance enough to withstand such processing conditions required for practical use.

In order to overcome this drawback, for example, silica having a small average particle size is densely filled in the constituent layers and the reduction of the center line average roughness Ra value is reduced, so that the stain resistance performance is reduced. Although it has been clarified that it is effective in improving the scratch resistance without any problem, conventionally, such a solid powder is densely filled in the constituent layer, and a large amount of dispersion water is required in the process of dispersing the solid powder. In addition, silica, in particular, tends to aggregate when added to an aqueous gelatin solution due to its low dispersibility itself. As a result, the center line average roughness Ra value is increased, and the stain resistance is deteriorated. Did not. JP-A-64-
The technique for forming fine uneven patterns on the surface of a lithographic printing plate disclosed in No. 46760 is no longer sufficient, and a novel solid fine particle dispersion has been demanded.

[0008]

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 having excellent scratch resistance and water retention.

[0009]

In a lithographic printing plate comprising at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer sequentially coated on a support, fine particle powder is contained in the constituent layers. This was achieved by containing a compound of the general formula represented by Chemical Formula 1 as a solid fine particle dispersion.

In the general formula of the compound used in the present invention, L ₁ represents an alkyl oxide unit, examples of which include ethylene oxide and propylene oxide. M is an alkali metal or ammonium salt,
It may be a hydrogen atom. R ₂ represents a monovalent organic group, preferably an alkyl group. Specific examples of the compound used in the present invention include Chemical Formulas 2 to 17, but the present invention is of course not limited to these.

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[0026]

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The compound represented by the general formula (I) used in the present invention can be added to any layer such as a silver halide emulsion layer and an undercoat layer. A dispersion of the compound of the general formula represented by Formula 1 in advance is added to the undercoat layer. The addition amount depends on the compound and the layer constitution, but is 0.05 to 5 times the addition amount of the fine particle powder.
%, Preferably in the range of 0.1 to 2% by weight.

The fine particle powder used in the present invention has an average particle diameter of 10
It is a submicron solid powder, for example, silica particles, talc, clay, titanium oxide and the like. In the present invention, silica particles having an average particle size of 0.1 to 5 microns are preferred.
Specific examples of the silica particles include Siricia 310 (average particle size: 1.4 microns) manufactured by Fuji Silysia Chemical Ltd. The amount of the matting agent added varies depending on various conditions, but is in the range of 0.1 g to 10 g per m ² .

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. Measured length l from the roughness curve in the direction of its center line
When the roughness curve is represented by y = f (x), and the center line of the extracted portion is defined as the X axis and the direction of the vertical magnification is defined as Y axis, the center line average roughness Ra value is expressed by the micromeans. It is expressed in units of Torr, and can be calculated by the formula of Equation 1.

[0030]

(Equation 1)

In the present invention, when the center line average roughness Ra value of the lithographic printing plate is 1.2 or less, water retention is good, but when the Ra value is more than 1.2, printing stains are reduced. Easy to occur.

The action mechanism of the present invention is estimated as follows. The effects of the solid fine particle dispersion disclosed in the present invention have enabled solid fine particle dispersion at a level not realized conventionally. Therefore, it has become possible to fill the constituent layer with solid powder more densely than before. It is believed that this is effective in improving the scratch resistance, that is, the function of dispersing the force applied to the plate surface at the time of contact, which is the cause of the scratch, has been improved, in other words, it is a result that is excellent in stress relaxation characteristics. It is possible. Moreover, the center line average roughness R
Since it is effective in maintaining the reduction of the a value, it is also possible to prevent deterioration of the stain resistance performance.

The lithographic printing plate which is 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 be hardened with a gelatin hardener.
Gelatin hardeners include, for example, inorganic compounds such as chrome alum, aldehydes such as formalin, glyoxal, malealdehyde and glutaraldehyde, N-methylol compounds such as urea and ethylene urea, 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 salt, 2,4-dihydroxy-6-chloro-S-triazine salt, divinyl sulfone, divinyl ketone, N, N, N
-Tricloyl hexahydrotriazine, compounds having two or more ethyleneimino groups or epoxy groups as active three-membered rings in a molecule, one of various compounds such as dialdehyde starch as a polymer hardener or Two or more 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 gelatin in the gelatin-containing layer of the present invention is partially formed of water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethylcellulose, acacia, 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. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer.

The polymer binder of the undercoat layer is generally 0.5
10 to 10 g / m ^2, more preferably 1 to 6 g / m ² .
The undercoat layer may contain pigments such as carbon black, dyes and the like for the purpose of preventing halation. Further, a photographic additive such as a developing agent can be included. The undercoat layer is disclosed in JP-A-48-5503, JP-A-48-100203, and JP-A-49-50203.
16507.

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, 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 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 can 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 is 0.5 g /
m 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 matting agent, a thickener, an antistatic agent and the like.

As the support of the lithographic printing plate of the present invention,
Paper, a synthetic or semi-synthetic polymer film, a metal plate of aluminum, iron, or the like can be used as long as it can withstand lithographic printing. One or both surfaces of the support may be coated with one or more polymer films or metal thin films. The surface of these supports can be subjected to a surface treatment in order to improve the adhesion to the coating layer.

Particularly preferably used supports are paper coated on both sides or one side with a polyolefin polymer, a polyester film, a polyester film having a hydrophilized surface, an aluminum plate having been subjected to a surface treatment, and the like.
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.

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.

[0045]

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

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

<Undercoating solution> Gelatin 25 g Water 200 g Fuji Silysia Chemical Ltd. Sylysia 310 Xg Water 160 g Compound 2 Yg Carbon black dispersion (solid content 32%) 8 g Formaldehyde (30% aqueous solution) 2 g Grigiozal (30% (Aqueous solution) 4 g Surfactant 6 ml Add water to make the total amount 600 g.

The coating amount was 60 g / m ² in terms of a moisture coating amount. The 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.
After drying, the mixture was heated at 50 ° C. for 2 days.
Of sodium acrylate (containing a No. 3 copolymer of acrylamide and imidazole as a polymer and hydroquinone as a developing agent at a ratio of 0.8 g / m ² ) described in Example 2 of Average molecular weight 26000
0) was added and adjusted in a similar manner to 0.04 g / m ^2, and applied. (Samples 1-3)

For comparison, comparative samples were prepared in the same manner except that no compound 2 was added to the undercoating solution (Comparative a,
b, c).

Each lithographic printing plate was subjected to image exposure using a plate making camera processor CP-550II manufactured by Mitsubishi Paper Mills and developed. The development was carried out at 30 ° C. for 20 minutes using the following diffusion transfer developer. For stabilization, each was treated with a stabilizing solution having the following composition at 25 ° C. for 20 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 Water is added to bring the total volume to 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 Water is added to bring the total volume to 1,000 ml.

The printing evaluation was performed by AB Dick 350
CD (trademark of offset printing machine manufactured by AB Dick)
It was used. To check the stain resistance of the non-image area, F Gloss Purple 68S manufactured by Dainippon Ink was used as the ink, and a 2.5% aqueous solution of KPS # 500 manufactured by Lawoss Co., Ltd. was used as the humidifying liquid. The number of printed sheets when stains occurred and could not be used for printing was determined according to the following evaluation criteria. (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.

The scratch resistance was evaluated by performing a development process using a processor and then evaluating the level of scratches generated on the plate surface. (A) There is no scratch on the plate. (B) There is no problem in practical use although the scratch is very thin. (C) Although inferior to the level of (B), there is no practical problem. (D) Inferior to the level of (C), scars appear thin during printing, and there is a problem in practice. (E) Scratches occur, and there is a practical problem. Table 1 shows the scratch resistance results.

[0055]

[Table 1]

As is clear from Table 1, it was found that the sample of the present invention was superior in the scratch resistance and the stain resistance as compared with the comparisons a, b and c. In particular, the improvement in the dispersibility of silica by using the compound of the present invention reduced the Ra value of samples 1 to 3 of Example 1, and made it possible to maintain stain resistance performance and improve scratch resistance performance. In Comparative a, which has a tendency to agglomerate and has a large Ra value, it has excellent scratch resistance but very poor stain resistance. In the case of the comparative b, the stain resistance is better than that of the comparative a because the Ra value is reduced, but the scratch resistance is reduced. In Comparative c, although the Ra value was low, the stain resistance was good, but the scratch resistance was poor.

Example 2 A sample was prepared in the same manner as in Example 1 except that silica, the compound of the present invention and the amount of use were used in the undercoating liquid of Example 1 as shown in Tables 2 and 3, and a print evaluation was performed. Was done. The results are shown in Table 2.

For comparison, a comparative sample was prepared in the same manner except that the compound of the present invention was not added to the undercoat liquid. (Comparison a)

[0059]

[Table 2]

[0060]

[Table 3]

As is clear from Tables 2 and 3, the sample of the present invention has a significantly improved dispersibility of silica powder, so that the surface roughness maintains the smoothness with respect to the added amount of silica. Excellent in scratch resistance and stain resistance. Regarding Comparative a, the silica has a tendency to agglomerate and the surface roughness has a large Ra value, so the scratch resistance is excellent, but the stain resistance is inferior.

[0062]

According to the present invention, a lithographic printing plate excellent in stain resistance and scratch resistance can be provided.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-13249 (JP, A) JP-A-62-113140 (JP, A) JP-A-1-229245 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03F 7/07 G03C 1/76 G03C 1/04

Claims (1)

(57) [Claims] 1. A lithographic printing plate comprising a support, on which at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer are successively coated, wherein the fine particles are converted into fine particles in the constituent layers. A lithographic printing plate comprising a solid fine particle dispersion containing a compound of the general formula: Embedded image L ₁ represents an alkyl oxide unit. n = an integer from 1 to 20. R ₁ represents hydrogen or an alkyl group, and M represents a cation. R ₂ represents a monovalent organic group, 1 and m represent mol%, 1 represents 50 to 100 mol%, and m represents 50 to 0 mol%.