JP2831789B2 - Lithographic printing plate for scanning exposure - Google Patents

Description

The present invention relates to a lithographic printing plate utilizing a silver complex salt diffusion transfer method suitable for using a scanning exposure light source such as a laser light source as a light source.

(B) Prior art and its problems Lithographic printing plates in which a transferred silver image obtained by a silver complex salt diffusion transfer method can be used immediately as ink acceptability have already been disclosed in JP-B-48-30562, JP-A-53-21602, 54-
103104 and 56-9750, etc., and are well known.

According to a typical practice of the silver salt diffusion transfer method suitable for the method of making a lithographic printing plate, a support and an undercoat layer on which a halation is prevented, a silver halide emulsion layer, a physical development nucleus layer are provided. When the photosensitive material is exposed to light and developed, the silver halide on which the latent image is formed becomes blackened silver in the emulsion layer. At the same time, the silver halide having no latent image formed thereon is dissolved by the action of the silver halide complexing agent contained in the developing solution and diffuses to the surface of the photosensitive material. The dissolved and diffused silver complex salt is deposited as a silver image on the physical development nuclei of the surface layer by the reducing action of the developing agent. After the development process, if necessary, a sensitization process is performed after the development process to enhance the ink acceptability of the obtained silver image, and the silver image is set in an offset printing machine, and the ink image is transferred to a printed material.

According to the above-mentioned conventional method, the silver halide emulsion layer is spectrally sensitized with a merocyanine dye, a cyanine dye, or the like so as to have a photosensitive maximum in a green region around 550 nm, and is sensitized with a plate making camera using a normal light source such as a tungsten light source. Seconds ~
Exposure for several tens of seconds was given. However, in the above-mentioned conventional method, there is a limit even though the lithographic printing plate is originally excellent in sharpness and resolution. In addition, if a color print is to be obtained from a color original, not only the resolution is insufficient, but also the production of the printing plate and the plate making operation are complicated.

Today, as a method for solving the above-described problem, a method of performing direct plate making using a laser beam has been considered. For example, U.S. Pat.No. 4,501,811, JP-A-59-710
55, sho 59-71056, sho 60-61752, sho 60-75838,
JP-A-60-100148, JP-A-61-114235 and JP-A-63-47756 disclose lithographic printing plates used for helium / neon lasers, argon ion lasers, semiconductor lasers, light emitting diodes and the like.

On the other hand, as a light source used for the scanning plate-making, a helium-cadmium laser, an argon laser, a helium-neon laser, a semiconductor laser, a light emitting diode, and the like are used.

An image produced by using a scanning type output device using these light sources is characterized by having better sharpness and resolution than an image produced by a plate making camera.

Among the performance requirements for a scanning lithographic printing plate are image reproducibility and exposure latitude. In order to improve image reproducibility and exposure latitude, various methods have been used in the prior art, such as providing a black anti-halation layer and adding an anti-irradiation dye to the emulsion. Was. The present inventors have proposed such anti-halation,
By studying the emulsion factors of silver halide emulsions in addition to the anti-irradiation technique, a new emulsion grain system having better exposure latitude than the conventionally used emulsions was discovered.

(C) Object of the Invention It is an object of the present invention to provide a scanning lithographic printing plate which uses a silver complex salt diffusion transfer method and has excellent exposure latitude using a scanning exposure light source as a light source.

(D) Constitution of the invention The object of the present invention is to provide a silver halide emulsion comprising 95 mol% or more of silver chloride grains mainly composed of silver chloride, wherein 90 wt% or more of the silver halide grains have an average grain size of ± 40% or less, the average grain size is 0.3 μm or more and 1.0 μm or less, and the grain surface is 0.1 to 0.1 mol per mol of silver halide.
Achieved by using one that was replaced with 3.0% iodide.

The mechanism by which the exposure latitude is improved is not clearly understood, but is presumed as follows as a factor. That is, when exposed with a scanning exposure light source, the photographic material undergoes weak pre-exposure, strong exposure and weak post-exposure. Because of such intermittent exposure, it is considered that those having less influence of these sub-exposures are preferable. However, those having little influence of the sub-exposure were not clarified technically. The effect of the above-mentioned silver halide emulsion this time has been clarified as a result of the experiment.

The silver halide emulsion used in the present invention is a silver halide grain mainly containing 95 mol% or more of silver chloride, and the surface of the silver halide grain is substituted with 0.1 to 3.0 mol% of iodide per mol of silver halide. Silver chloroiodide or silver chloroiodobromide emulsion. If the silver chloride content is less than 95 mol%, sufficient image reproducibility cannot be obtained. If the iodide content on the surface of the silver halide grains is less than 0.1 mol% or more than 3.0 mol%, the exposure latitude is reduced.

In the silver halide emulsion used in the present invention, 90% by weight or more of the silver halide grains have an average grain size of ± 40%.
% And the average particle size is 0.3 μm or more and 1.0 μm or less. Average particle size less than 0.3μ or 1.0
If the particle size exceeds μ or the particle size exceeds 40% of the average particle size exceeds 10% by weight, the exposure latitude decreases.

The binder used in the silver halide emulsion of the lithographic printing plate of the present invention is usually gelatin. It can be replaced with one or more hydrophilic polymer binders such as carboxymethylcellulose, polyacrylamide, styrene-maleic anhydride copolymer, and polyvinylmethylether-maleic anhydride copolymer. Further, a vinyl polymer aqueous dispersion (latex) may be used.

Silver halide emulsions can be sensitized in various ways as they are prepared or coated. Preferably, it is chemically sensitized by methods well known in the art, such as by sodium thiosulfate, alkyl thioureas, or by gold compounds, such as rhodium gold, gold chloride, or a combination of both. Also, by using a compound of a metal belonging to Group VIII of the periodic table at any time of producing a silver halide emulsion, for example, a salt of cobalt, nickel, rhodium, palladium, iridium, platinum or the like, particularly high sensitivity. Thus, preferable characteristics for a printing plate for direct plate making having high sharpness and high resolution can be obtained. The amount of addition is in the range of 10 ^-8 to 10 ^-3 mol per mol of silver halide. The silver halide emulsion layer may contain other additives such as coating additives, antifoggants, matting agents (water retention agents), and developing agents, for example.

The sensitizing dye used in the silver halide emulsion layer of the scanning lithographic printing plate of the present invention is a dye having an absorption region at an emission wavelength of a scanning exposure light source, for example, U.S. Pat.
No., JP-A-59-71055, JP-A-59-71056, JP-A-60-6175
2, 60-75838, 60-100148, 61-114235,
For example, helium / neon laser,
A sensitizing dye used for an argon ion laser, a semiconductor laser, a light emitting diode, and the like is disclosed. In particular, a sensitizing dye represented by the following general formula (I) is preferable.

(Wherein, Z ₁ and Z ₂ each represent a nonmetallic atom group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic nucleus, and at least one of R ₁ and R ₂ represents a sulfoalkyl group, a carboxy group, Represents an alkyl group, the remainder is an alkyl group, a substituted alkyl group,
Alkenyl group, an aralkyl group, an aryl group, R ₃
Represents an alkyl group or a hydrogen atom, and M represents an alkali metal atom or an ammonium group. n, m, p, and q are 0,
Or 1 is represented. The following is a typical example.

Also, sensitizing dyes, for example, U.S. Pat.No. 2,095,854,
No. 2,095,856, No. 2,955,939, No. 3,482,978
No. 3,552,974, No. 3,573,921, No. 3,582,34
No. 4, No. 3,623,881 and the like are preferable.

Preferably, for example, dyes represented by the following general formulas (II) to (V) are used.

In the general formulas (II) to (V), Z ₁ and Z ₂ may be the same or different and each represents an atom group necessary to form a 5- or 6-membered nitrogen-containing heterocyclic ring. . R ₁ and
R ₂ may be the same or different and each represents an alkyl group or an alkenyl group. R ₃ represents an alkyl group, an alkenyl group, or an aryl group. R _{4 to} R ₁₀ may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkoxy group. However, R ₆ and R ₇ or R ₈ and R ₉ can be linked to each other to form a 5- or 6-membered ring. R ₁₁ and R ₁₂ may be the same or different, and each is an alkyl group,
Represents an aryl group, and R ₁₁ and R ₁₂ may be linked to each other to form a 5- or 6-membered ring. Y is a sulfur atom, an oxygen atom, N-R ₁₃ (R ₁₃ is an alkyl group). X represents an acid anion. l, m, n, p and q each represent 1 or 2.

Specific examples of Z ₁ and Z ₂ include thiazole, benzothiazole, naphtho [1,2-d] thiazole, naphtho [2,1-
d) thiazole, naphtho [2,3-d] thiazole, selenazole, benzoselenazole, naphtho [2,1-d] selenazole, naphtho [1,2-d] selenazole, oxazole, benzoxazole, naphtho [1,2 -D) oxazole, naphtho [2,1-d] oxazole, naphtho [2,3-d] oxazole, 2-quinoline, 4-quinoline, 3,3-dialkylindolenin, imidazole, benzimidazole, naphtho [1, 2-d) imidazole,
Examples include a nitrogen-containing heterocyclic ring such as pyridine. These heterocycles are alkyl groups (eg, methyl, ethyl,
Butyl, trifluoromethyl, etc.), an aryl group (eg, phenyl, tolyl, etc.), a hydroxy group, an alkoxy group (eg, methoxy, ethoxy, butoxy, etc.), a carboxy group, an alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, etc.) ), A halogen atom (eg, fluorine, chlorine, bromine, iodine), an aralkyl group (eg, benzyl, phenethyl, etc.), a cyano group, an alkenyl group (eg, allyl, etc.) with 1 or 2
It may have the above.

In R ₁ and R ₂ , the alkyl group is methyl, ethyl,
Propyl, lower alkyl groups such as butyl, β-hydroxyethyl, hydroxyalkyl groups such as γ-hydroxypropyl, β-methoxyethyl, alkoxyalkyl groups such as γ-methoxypropyl, β-acetoxyethyl, γ-acetoxypropyl, β Acyloxyalkyl groups such as -benzoyloxyethyl, carboxymethyl groups such as carboxymethyl and β-carboxyethyl, alkoxycarbonylalkyl groups such as methoxycarbonylmethyl, ethoxycarbonylmethyl and β-ethoxycarbonylethyl, β-sulfoethyl, γ-sulfoethyl Sulfoalkyl groups such as propyl and -sulfobutyl; aralkyl groups such as benzyl, phenethyl and sulfobenzyl; and alkenyl groups include allyl.

As R ₃ , an alkyl group as described above for R ₁ and R ₂ ,
Examples include alkenyl groups and aryl groups such as phenyl, tolyl, methoxyphenyl, chlorophenyl, and naphthyl.

R _{4 to} R ₁₀ represent a hydrogen atom, a halogen atom (eg, chlorine,
Bromine, iodine, fluorine), alkyl groups as described in R _1, R _2, an aryl group, or R _1, an alkoxy group having alkyl as mentioned in R ₂ (i.e. group OR _1), and R ₆ R ₇
Alternatively, the 5- or 6-membered ring formed by R ₈ and R ₉ may be substituted with a lower alkyl group or the like. R ₁₁ and R
₁₂ represents an alkyl group or an aryl group as described for R ₁ and R ₂ , and R ₁₁ and R ₁₂ may be mutually linked to form a 5- or 6-membered ring. R ₁₃ is an alkyl group as described for R ₁ and R ₂ .

Examples of the acid anion of X include alkyl sulfate ions such as methyl sulfate and ethyl sulfate, thiocyanate ions, toluene sulfonate ions, halogen ions such as chlorine, bromine and iodine, and perchlorate ions. It does not exist when taking.

Specific examples of the sensitizing dye used in the present invention are shown below.

The sensitizing dye used in the present invention can be synthesized by a method known to those skilled in the art. The time of addition to the silver halide emulsion can be any time before coating of the emulsion. The amount added can vary over a wide range,
Good results range from 1 × 10 ^-6 to 1 × per mole of silver halide.
It is in the range of 10 ^-2 mol. The optimum addition amount varies depending on the conditions of the silver halide emulsion, for example, the halogen composition, the average grain size of silver halide grains, crystal habit, and the like.

Under the silver halide emulsion layer (support side), a subbing layer for improving adhesion and / or an undercoat layer for the purpose of preventing halation may be provided. This layer may contain a developer or a matting agent. You can also.

The support is, for example, paper, a film, for example, a cellulose acetate film, a polyvinyl acetal film, a polystyrene film, a polypropylene film, a polyethylene terephthalate film, or a composite film in which a polyester, polypropylene, or polystyrene film is coated with a polyethylene film, metal, metallized paper. Alternatively, it can be a metal / paper laminate support. A paper support coated on one or both sides with an α-olefin polymer, such as polyethylene, is also effective.

The scanning planographic printing plate of the invention has an image receiving layer containing physical development nuclei.

Known physical development nuclei such as metals such as antimony, bismuth, cadmium, cobalt, palladium, nickel, silver, lead and zinc and sulfides thereof can be used. The image receiving layer may not contain a hydrophilic colloid, gelatin, carboxymethylcellulose, gum arabic, sodium alginate, hydroxyethyl starch, dextrin, hydroxyethylcellulose, polystyrenesulfonic acid, a copolymer of vinylimidazole and acrylamide, A hydrophilic colloid such as polyvinyl alcohol can be contained in an amount of preferably 0.1 g or less per square meter.

A hygroscopic substance, for example, a humectant such as sorbitol or glycerol may be present in the image receiving layer. further,
The image receiving layer may also contain pigments for preventing scumming, such as barium sulfate, titanium dioxide, china clay and silver, developing agents such as hydroquinone, and curing agents such as formaldehyde.

The DTR treatment liquid used in the present invention includes an alkaline substance,
For example, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium tertiary phosphate, etc., sulfites as preservatives, silver halide solvents such as thiosulfate, thiocyanate, cyclic imide, thiosalicylic acid, amines, etc. Thickeners such as hydroxyethylcellulose, carboxymethylcellulose, antifoggants such as potassium bromide,
1-phenyl-5-mercaptotetrazole, JP-A-47
-26201, a developer, for example, hydroquinone, 1-phenyl-3-pyrazolidone, a development modifier, for example, a polyoxyalkylene compound, an onium compound and the like.

In carrying out the silver complex salt diffusion transfer method, for example, British Patent No. 1,000,115, No. 1,012,476, No. 1,017,273,
As described in the specification of Japanese Patent No. 1,042,477 and the like, a developer is mixed in a silver halide emulsion layer and / or an image receiving layer or another water-permeable layer adjacent thereto. Therefore, in such a material, a so-called “alkaline activating liquid” containing no developer can be used as a processing liquid used in the developing step.

The lithographic printing plate manufactured according to the present invention is described in, for example,
Compounds such as those described in U.S. Pat. No. 3,721,539, can be used to convert or enhance ink acceptance.

The printing method, the desensitizing solution, the humidifying solution, and the like to be used can be a commonly known method.

(E) Examples The present invention will be described below with reference to examples, but it is needless to say that the present invention is not limited thereto.

Example 1 A matte layer containing silica particles having an average particle size of 5 μm was provided on one side of a support having both sides coated with a polyethylene resin, and the opposite side contained carbon black and phenidone. Average particle size of 7% by weight
m-silica powder, adjusted to pH 4.1, and chemically sensitized with a gold compound and hypo, and then 2-mercaptobenzoic acid, and a silica powder having an average particle diameter of 7 μm were added to photographic gelatin. And a silver halide emulsion layer (adjusted to pH 4.5) containing 5% by weight. The silver halide emulsion was added a sensitizing dye (6) 1.82mg / gAgNO ₃ as a solution. During physical ripening, 5 × 10
^-6 mol of iridium added, average particle size 0.
A substantially cubic silver chloride crystal having a size of 33 microns and 90% by weight or more of the total number of grains in a range of ± 30% of the average grain size. A KI solution corresponding to mol% was added, and a silver halide grain surface was replaced with iodide.

The gelatin of the undercoat layer is 3.6 g / m ² , and the gelatin of the emulsion layer is 1.2
g / m ² , and 1.5 g / m ² of silver halide in terms of silver nitrate. The undercoat layer and the emulsion layer contain formalin as a hardening agent in an amount of 28 mg / g gelatin relative to gelatin.

After coating and drying, the mixture was heated at 40 ° C. for 7 days. On this emulsion layer, a nucleus coating solution for plate No. 11 in Example 1 of JP-A-54-103104 was used. A physical development nucleus solution was prepared and coated as follows.

Solution A and Solution B are mixed while stirring, and after 30 minutes, ion exchange resins (IR-120B, IRA-400) made for pure water production
Through the column containing No. 2, and further, No. 2 polyfunctional polymer described in Example 1 of JP-A-54-103104, sodium polyacrylate (average molecular weight 500,000), and an interface. Solution C containing an activator was added, and then solution D was added to obtain a physical development nucleus solution.

The coating solution was applied by a Dip method at a speed of 8 m / min to prepare a plate. (Sample 1) For comparison, the same except that the average grain size of the silver halide grains was 0.27 μm and the amount of the sensitizing dye (6) was 2.06 mg / gAgNO ₃ to obtain the same sensitivity as Sample 1. To make a plate. (Sample a) Each sample was exposed to a thin line image having a thickness of 50 μm using a helium-neon laser typesetter Linotronic300 (manufactured by Linotype) while changing the exposure intensity.

Each of the exposed printing plates is separately treated with the following diffusion transfer developer.
Development was performed at 25 ° C. for 30 seconds. After the development processing, the original plate is passed between two squeezing rollers to remove the excess developing solution, and immediately treated with a neutralizing solution having the following composition at 25 ° C. for 20 seconds. And dried at room temperature.

The thickness of the fine line after the plate making process and after the printing was measured using Luzex 500 manufactured by Nippon Regulator.

For printing, each printing sample was attached to one sheet, this sheet was mounted on an offset printing machine, the following desensitizing solution was applied to the plate surface, and printing was performed using the following humidifying solution. Was.

The printing machine is AB Dick 350CD (AB Dic)
Offset printing machine manufactured by k Company) was used.

The ink used was F gloss ink B manufactured by Dainippon Ink.

The results obtained are shown in Table 1. Next, from Table 1,
Each sample reads the exposure dial that reproduces 45μ and 55μ fine line images, and calculates the exposure amount corresponding to this exposure dial.
And E _45, E _55, if the difference between the logarithmic value log E _45, log E ₅₅ and exposure latitude LREL, LREL give results as shown in Table 2.

As is evident from Table 2, Sample 1 of the present invention had a significantly higher exposure latitude than Sample a of Comparative Example a, and the effect of the embodiment of the present invention on the exposure latitude was clarified.

Example 2 This example illustrates the effect of iodide substituted on the particle surface.

At the end of physical ripening, samples 2, 3, and 4 and comparative samples b and c were prepared in the same manner as in Example 1 except that the KI solution was added in accordance with the amount of addition described in Table 3. Then, a thin line image was created and the exposure latitude was calculated. Table 3 shows the obtained results.

As is evident from Table 3, Samples 2, 3, and 4, which are embodiments of the present invention, are more excellent in exposure latitude than Sample b with KI addition 0 and Sample C with large KI addition. It has been confirmed that the embodiments of the present invention are effective.

Example 3 As a sensitizing dye, 0.28 mg / gAgNO ₃ of a dye (19) was used.
A cubic silver chlorobromide emulsion containing 2 mol% bromide, wherein the average grain size of the grains is 0.35μ and ±
90% by weight or more of all particles are distributed in the range of 30%, and
At the time of physical ripening, the same procedure as in Example 1 was carried out except that the surface of the silver halide grains was replaced with iodide by adding a KI solution corresponding to 1 mol% per mol of silver halide. , Sample 5 was prepared.

For comparison, a sample d was prepared in the same manner by using a powder having a wide particle size distribution in which the average particle size was 0.35 μm and 10% by weight or more of all particles exceeded ± 40%.

For each sample, a positive ruled line and a negative ruled line having a thickness of 63 μm were output by changing the exposure intensity using an Altre setter (manufactured by Ultre ^* ) which is a semiconductor laser image setter. Next, the same processing as in Example 1 was performed, and after plate making, the thickness of the thin line was measured using a view pack manufactured by Nippon Regulator. Thereafter, printing was performed in the same manner as in Example 1.

Assuming the thickness of the thin line after plate making and printing obtained in this way on the vertical axis, the exposure amount on the horizontal axis, and deq the line thickness at the intersection of the reproduction curves of the positive ruled line and the negative ruled line, 63
This indicates that the negative ruled line and the positive ruled line of μ are reproduced with the same thickness deq at the reference exposure amount. The deq is shown in Table 4.

Table 4 reveals that Sample 5, which is an embodiment of the present invention, is superior to Comparative Sample d in image reproducibility and that those having a narrow particle size distribution are preferable.

Example 4 Sample 5 of Example 3 except that bromide was 10 mol%
In the same manner as in the above, a comparative sample e was prepared. The same evaluation as in Example 3 was performed, and Table 5 was obtained.

From Table 5, it was found that Sample 5, which is an embodiment of the present invention, was superior to Comparative Sample e in image reproducibility, and that the sample containing more bromide was inferior in image quality.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-47756 (JP, A) JP-A-59-71056 (JP, A) JP-A-60-75838 (JP, A) JP-A-51- 111103 (JP, A) JP-A-59-71055 (JP, A) JP-A-60-100148 (JP, A) JP-A-60-123845 (JP, A) JP-A-60-220336 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03F 7/07, 7/00

Claims (1)

(57) [Claims] 1. A lithographic printing plate for scanning exposure having at least a silver halide emulsion layer and a physical development nucleus layer on a support, wherein the silver halide emulsion contains 95 mol% or more of silver halide grains mainly composed of silver chloride. Comprising the silver halide grains
90% by weight or more of grains are contained within ± 40% of the average grain size, the average grain size is 0.3 μm or more and 1.0 μm or less, and the grain surface has 0.1 to 3.0% iodine per mole of silver halide. A lithographic printing plate for scanning exposure characterized by being substituted by a compound.