JP3101431B2 - 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, which has improved processing temperature dependency.

[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 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.

[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). Resistance to mechanical abrasion of the part is insufficient, the image part is missing or the ink receptivity of the image part is easily lost,
It has the disadvantage of low printing durability.

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, 3-268765, 3-268765, 3-2
68767, same Hei 3-268766, same Hei 3-2856
No. 23 discloses that there is a correlation between the matte property of the surface and the print stain, and that the smoothing of the surface can significantly reduce the print stain in the non-image area.

A lithographic printing plate using a silver complex salt diffusion transfer method is
Processing is performed by a camera processor or an automatic processor, but printing performance changes depending on the processing temperature. Although this performance depends on the structure of the developing machine, the composition of the processing solution, etc., in general,
It has a large temperature dependency, and it changes depending on the temperature of diffusion transfer development. In recent years, with the introduction of a liquid-saving type camera processor to the market, it has become more susceptible to a change in development temperature, and the print quality has been more likely to fluctuate. Thus, a planographic printing plate having little dependence on the processing temperature has been demanded.

[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 processing temperature dependency.

[0010]

The object of the present invention is to provide at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus sequentially coated on a support. 0.1 to 2.0 g / m in the coating layer on the side including
^A lithographic printing plate containing the matting agent of formula (2) and having a center line average roughness Ra value of 1.2 or less, and a mercapto compound represented by the general formula (1) This was achieved by incorporating a benzotriazole compound of the general formula represented by

In the chemical formula 1, R1 and R2 each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, an amino group, an acylamide group or a sulfonamide group, and the sum of the carbon atoms of R1 and R2 is 3 That is all.

In Chemical Formula 2, M ⁺ represents a hydrogen ion, an alkali metal ion or an ammonium ion. Where R3, R
4, R5 and R6 each represent a hydrogen atom, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, a halogen atom, an alkoxy group, a hydroxy group, an amino group, a carboxy group, a sulfone group, an alkoxycarbonyl group, an acylamide group, a sulfone Indicates an amide group. R3, R4, R
5 and R6 may be linked to form a ring.

Specific examples of the mercapto compound represented by the general formula (1) used in the present invention include:
However, the present invention is of course not limited to these.

[0014]

Embedded image

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

[0020]

Embedded image

[0021]

Embedded image

[0022]

Embedded image

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

The addition amount of the mercapto compound of the general formula represented by the formula (1) used in the present invention depends on the compound and the layer constitution, but is from 8 × 10 ⁻³ mmol / m ^{2 to} 1.6 mmol / m ^{2. 2} , preferably in the range of 2.4 × 10 ⁻² mmol / m ^{2 to} 0.4 mmol / m ² .

As a specific example of the benzotriazole compound of the general formula represented by Chemical formula 2 used in the present invention, Chemical formula 1
Examples 7 to 30 are shown, but the present invention is of course not limited to these.

[0030]

Embedded image

[0031]

Embedded image

[0032]

Embedded image

[0033]

Embedded image

[0034]

Embedded image

[0035]

Embedded image

[0036]

Embedded image

[0037]

Embedded image

[0038]

Embedded image

[0039]

Embedded image

[0040]

Embedded image

[0041]

Embedded image

[0042]

Embedded image

[0043]

Embedded image

The addition amount of the benzotriazole compound of the general formula represented by Chemical formula 2 used in the present invention depends on the compound and the layer structure, but is 8 × 10 ⁻³ mmol / m ² to
1.6 mmol / m ² , preferably 2.4 × 1
0 in the range ^-2 mmol / m ² to 0.4 mmol / m ^2.

The matting agent used in the present invention has an average particle size of 1 to 1.
10 micron solid powder, for example, silica particles,
Etc. 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 of the coating layers on the side including the silver halide emulsion layer, but it is preferable that the matting agent be provided between the support and 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 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 l is extracted from the roughness curve in the direction of the center line, and the center line of the extracted portion is defined as the X axis,
When the direction of the vertical magnification is the Y axis and the roughness curve is represented by y = f (x), the center line average roughness Ra value is expressed in units of micrometers, and can be calculated by the equation (1).

[0048]

(Equation 1)

In the present invention, it is necessary that the lithographic printing plate has a center line average roughness Ra value of 1.2 or less. When the center line average roughness Ra value of the lithographic printing plate is larger than 1.2, printing stains are likely to occur.

The mechanism of action of the present invention is estimated as follows. By smoothing the surface of the lithographic printing plate for the purpose of improving the stain resistance, the shape of the physically developed silver generated by DTR development is changed, or the state of filling of the physically developed silver is changed. It seems that the adhesive strength with the coating film is reduced. In particular, under a high temperature condition such as treatment at 40 ° C., the amount of silver deposited tends to increase, but the adhesive strength of physically developed silver tends to decrease, and the printing durability tends to decrease significantly. Thus, the smoothing of the surface of the lithographic printing plate increases the processing temperature dependency. The present invention 1
The mercapto compound represented by the general formula and the benzotriazole compound represented by the general formula represented by Formula 2 act on DTR development, thereby changing the shape and filling state of physically developed silver, thereby allowing a wide range of It has been found that printing durability can be ensured at a temperature, but a more detailed mechanism of action has not been elucidated.

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, 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. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer.

The polymer binder in the undercoat layer is generally 0.5
More preferably to 10 g / m ² is 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
8-5503, 48-100203, and 49-1
6507.

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 crystals 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, and the addition amount is 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. 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 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. 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. Hereinafter, the present invention will be described with reference to Examples, but it should be understood that the present invention is not limited thereto.

[0063]

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 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 (A)> Gelatin 35 g Water 200 g Fujiloid Davidson's syloid (grade 308) 3 g Carbon black dispersion (solid content 32%) 8 g Formaldehyde (30% aqueous solution) 2 g Grigiozar (30% aqueous solution) 4 g Mercapto compound of formula 6 0.05 g Benzotriazole compound of formula 19 0.1 g Surfactant 6 ml Add water to make the total amount 500 g.

The amount of application was 50 g / m ² in terms of the amount of moisture applied. (Sample 1). The average particle size of Fuji Dividson's thyroid (grade 308) was 3.5 μm as measured by the Coulter counter method. For comparison, the undercoat liquid (A) does not contain the mercapto compound of Chemical Formula 6 and the benzotriazole compound of Chemical Formula 19, contains no mercapto compound of Chemical Formula 6, and contains the benzotriazole compound of Chemical Formula 19 None was prepared and applied similarly. (Compare a, b, c). 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 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. (Sample 1, comparison a, b, c). The center line average roughness of each sample was 0.6.

Each of the lithographic printing plates 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 20 ° C., 30 ° C. and 40 ° C., respectively, using the following diffusion transfer developer for 20 minutes. The stabilization was performed with a stabilizing solution having the following composition for 25
The mixture was treated at 20 ° C. for 20 mats 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 Add water to make the total volume 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. Regarding the printing durability, after treating each lithographic printing plate with the following desensitizing solution, using the following humidifying solution, printing was performed using New Champion Ink N manufactured by Dainippon Ink Co., Ltd. Used as ink, Dainippon Ink F
Gloss black was used, and the number of prints when image skipping due to lack of a silver image portion occurred and printing could not be performed 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 liquid> 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 liquid> 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 (stain on the background) of the non-image area, Dai-Nippon Ink F Gloss Purple 68S was used as the ink.
Using a 2.5% aqueous solution of KPS # 500 manufactured by Lawoss Co., Ltd. as a humidifying liquid, the number of printed sheets when the AB Dick 350CD was soiled 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.

[0074]

[Table 1]

As is clear from Table 1, the comparisons a, b, c
Although there is a difference in the level of printing durability, the printing durability is reduced at 40 ° C., but the sample 1 of the present invention does not show the processing temperature dependence of printing durability, and has excellent printing durability over a wide temperature range. It has been found. It should be noted that the stain did not show any dependency on the processing temperature.

Example 2 <Undercoating solution (B)> Gelatin 35 g Water 200 g Titanium oxide (TR-1 manufactured by Sakai Chemical Co., Ltd.) 50 g Siloid (grade 978) manufactured by Fuji Divison Co. Xg Carbon black dispersion (solid content 32%) 8 g Formaldehyde (30% aqueous solution) 2 g Gliogizar (30% aqueous solution) 4 g Mercapto compound of Chemical formula 0.04 g Benzotriazole compound of Chemical formula 0.15 g Surfactant 6 ml Add water to make the total amount 500 g.

The coating amount was 50 g / m ² in terms of the amount of moisture applied. Fuji Dividson syroid (grade 97
The average particle size of 8) was measured by the Coulter counter method, and was 2.5 μm. According to Table 2, the amount of thyroid added was changed. (Samples 2, 3, 4, Comparative d). For comparison, an undercoating solution prepared by adding 0.05 g of 1-phenyl-5-mercaptotetrazole to the above undercoating solution instead of adding the mercapto compound of formula 6 and the benzotriazole compound of formula 19 was applied in the same manner.
(Compare e, f, g, h). Hereinafter, a sample was prepared in the same manner as in Example 1, and printing evaluation was performed. The results are shown in Table 2.

As is clear from Table 2, Sample 2 of the present invention,
Samples Nos. 3 and 4 have a center line average roughness Ra value of 1.2 or less, are less dependent on processing temperature, and are excellent in stain resistance, whereas Comparative d has a center line average roughness Ra value of 1. 2, which is less dependent on the processing temperature, but is inferior in stain resistance.
On the other hand, in all of the comparisons e, f, g, and h, a decrease in printing durability was observed on the high temperature side, and the processing temperature dependence was large. It should be noted that the stain did not show any dependency on the processing temperature.

[0079]

[Table 2]

[0080]

According to the present invention, it is possible to provide a lithographic printing plate which is excellent in stain resistance and processing temperature dependency.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-261643 (JP, A) JP-A-63-249852 (JP, A) JP-A-63-226658 (JP, A) JP-A-58-1983 196548 (JP, A) JP-A-62-239161 (JP, A) JP-A-56-110927 (JP, A) JP-A-63-198064 (JP, A) JP-A-1-237552 (JP, A) JP-A-59-67094 (JP, A) JP-A-3-280053 (JP, A) JP-A-62-179953 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 7/07 G03F 7/00 503 G03F 7/004 501

Claims (1)

(57) [Claims] An at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer are sequentially coated on a support. Containing a matting agent of 1 to 2.0 g / m ² , and
A lithographic printing plate having a lithographic printing plate having a center line average roughness Ra value of 1.2 or less, containing a mercapto compound represented by the general formula 1 and a benzotriazole compound represented by the general formula 2 A lithographic printing plate characterized by the following. Embedded image (Wherein, R1 and R2 represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, an amino group, an acylamide group, and a sulfonamide group, respectively.
And the sum of the carbon numbers of R2 is 3 or more. ) (In the formula, M ⁺ represents a hydrogen ion, an alkali metal ion, or an ammonium ion. In the formula, R3, R4, R5, and R6 each represent a hydrogen atom, an alkyl group, an alkenyl group,
It represents an aralkyl group, an aryl group, a halogen atom, an alkoxy group, a hydroxy group, an amino group, a carboxy group, a sulfone group, an alkoxycarbonyl group, an acylamide group, and a sulfonamide group. R3, R4, R5 and R6 may be linked to form a ring. )