JP2003295450A - Method for producing planographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planographic printing plate and a method for producing the same by which warming-free one-pass coating is enabled without lowering printing performance to enhance production efficiency. <P>SOLUTION: In the method for producing a planographic printing plate in which the top of a support is coated with at least an undercoat layer and a silver halide emulsion layer, and after drying, continuous coating with a physical developing nucleus layer is carried out without winding, an inorganic sulfate is contained in the undercoat layer and/or the silver halide emulsion layer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lithographic printing plate using a silver complex salt diffusion transfer method, and more particularly to a lithographic printing plate having improved ink acceptability and printing durability and improved production efficiency. The present invention relates to a method for manufacturing a plate.

[0002]

2. Description of the Related Art A printing plate using a silver halide emulsion having high sensitivity and capable of spectral sensitization has already been put into practical use in several forms. Among them, offset printing plates that utilize a silver image as an ink-receptive material include U.S. Pat. Nos. 3,721,559, 3,490,905, and JP-B-4.
No. 8-30562, U.S. Pat. 5
3-9603, etc.

Although these are roughly classified into several types as a method for producing a printing plate, they are common in that the image silver is made ink-receptive. The lithographic printing plate is composed of an image-forming portion that receives lipophilic ink and a non-image-forming portion that is hydrophilic and receives water. Therefore, in the ordinary lithographic printing, both water and ink are supplied to the plate surface, the image area selectively receives the coloring ink, and the non-image area selectively receives the water, and the ink on the image area is transferred to, for example, paper. It is done by transferring to a substrate.

In order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity between the surface of the imaged part and the non-imaged part is sufficiently large, and the respective parts are physically and firmly joined together. This is very important.

In the art, a general method for producing the above-mentioned lithographic printing plate is as follows. An undercoat layer also serving as an antihalation layer and a silver halide emulsion layer are coated on a support, dried and then once formed into a long roll. After winding, the gelatin coating of the undercoat layer and the silver halide emulsion layer is subjected to a heating treatment (hardening treatment) to obtain a sufficient film strength to withstand printing (hardening treatment), and then a physical development nucleus layer is applied and dried. Is the standard method.

Conventionally, a printing plate coated with a subbing layer and a silver halide emulsion layer and provided with physical development nuclei without heating once without being wound into a long roll shape is not exposed to an image portion after development processing. Only a plate-making product having a low contrast with the image area was obtained, and ink-carrying and printing durability were poor. Although the cause is not always clear, it is presumed that the migration of nuclei to a layer in contact with physical development nuclei, for example, an emulsion layer, or the migration of an emulsion layer binder, for example, an emulsion layer gelatin to a nuclear layer, is involved. . The heating treatment has the effect of preventing the migration of physical development nuclei by promoting the hardening of the undercoat layer, the emulsion layer and the surface of the surface of the hardener, which is obviously compounded, and also preventing the migration of the binder. it can. As a result, a printing plate having metallic luster (achieving good contrast), good ink coverage, and good printing durability is possible.

Formaldehyde is known as a good hardener in the design of the printing plate. The constituent layer containing formaldehyde is usually heated at 40 ° C. for 5 to 10 days or more, and on the emulsion film which is sufficiently hardened, migration of the nucleus and / or binder gelatin as described above is caused. Can be practically prevented. As a result, it is possible to easily maintain and secure image contrast, ink transfer, printing durability, etc., which are basic characteristics in terms of quality of the printing plate.

Although this heating treatment is effective for ensuring a certain quality required for the printing plate, it not only complicates the production line and raises the production cost, but also stabilizes the sensitivity and other factors. It has also been a cause of quality fluctuations (for example, due to fluctuations in temperature and humidity during the heating period). Therefore, if consistent and efficient production including core coating is possible, not only will production cost be greatly reduced, but quality control will be easy and a stable printing plate with little quality fluctuation can be realized. Therefore, as a method for producing the printing plate, there is a strong demand for a heating-free method in a wound state, and a coating production method for a silver halide emulsion layer and a physical development nucleus layer in one pass.

In JP-A-8-194315, the temperature of a coating solution (receptor coating solution) containing physical development nuclei is 0 ° C. or higher and 2
A method for producing a diffusion transfer printing plate by a tandem coating method, which is applied at 0 ° C or lower, more preferably in the range of 0.1 to 10 ° C, is disclosed. In JP-A-11-184092 and JP-A-11-231543, the grain size of physical development nuclei is 10 nm or more, further 30 nm in simultaneous multilayer coating or tandem coating of a silver halide emulsion layer and physical development nuclei layer.
The above materials and the manufacturing method thereof are disclosed.
Although there are some attempts, the current situation is that the results have not always been good.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for producing a lithographic printing plate which enables one-pass coating and improves production efficiency without lowering printing performance.

[0011]

The above objects of the present invention are as follows.
A method for producing a lithographic printing plate comprising applying at least an undercoat layer and a silver halide emulsion layer on a support, drying the same, and continuously applying a physical development nucleus layer without winding, comprising the undercoat layer and / or It has been achieved by a method for producing a lithographic printing plate characterized by containing an inorganic sulfate in a halogenated emulsion layer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The purpose of the manufacturing method of the present invention is to improve the production efficiency and to enable a one-pass coating method. Therefore, one embodiment of the production method of the present invention is that a coating solution of at least an undercoat layer and a silver halide emulsion layer is simultaneously coated on a support by a slide hopper coating technique, dried, and once wound into a long roll. It is a method for producing a printing plate by a one-pass coating method (tandem method) in which a physical development nucleus layer is applied without being heated and dried.

After coating and drying the undercoat layer and the silver halide emulsion layer in the one-pass manufacturing process of the present invention,
Before coating the physical development nucleus layer, the surface coated with the silver halide emulsion layer may be heat-treated for an extremely short time (for example, within 1 minute), preferably within 20 seconds.

The inorganic sulfate used in the present invention preferably has a dehydrating ability by forming a hydrated salt with water molecules, and sodium sulfate, magnesium sulfate and calcium sulfate are typical, and sodium sulfate is more preferable. preferable.

The effect of this inorganic sulfate in the one-pass coating system (Tandem system) is that the coating solution of at least the undercoat layer and the silver halide emulsion layer is simultaneously coated on the support by the slide hopper coating technique and dried. In the step of adding, when an inorganic sulfate is added to the undercoat layer and / or the halogenated emulsion layer, the dehydration action of the inorganic sulfate increases the speed of drying water in the coating solution, thereby drying the laminate, It is possible to sufficiently suppress the swelling of gelatin, which is the hydrophilic binder in the laminate, in the short time until the physical development nucleus layer is applied, and only a plate-making product having a low contrast between the image area and the non-image area after the development processing is performed. Migration of nuclei to a layer that comes into contact with physical development nuclei, for example, an emulsion layer, which is considered to be the main cause of not being obtained, or Pass coating methods emulsion layer binder, such as migration to the nucleus layer of the emulsion layer gelatin by having a sufficient effect of inhibiting (tandem (Tande
The present inventors have found that it is possible to implement m) method).

The swelling suppressing action will be described in detail. Usually, a lithographic printing material having at least an undercoat layer, a silver halide emulsion layer and a physical development nucleus layer on a support of a lithographic printing plate in a developing solution, Immersion development was performed, and the swelling ratio was expressed by the ratio of how much liquid was absorbed per 1 g of gelatin.
When the immersion development is performed for 10 seconds, the swelling rate is 400% or more,
When the immersion development is performed at 30 ° C. for 10 seconds, the swelling rate is 450.
%, The swelling ratio is set to 300 in order to realize the one-pass coating method (Tandem method) by adding the inorganic sulfate of the present invention.
It has been found that it is preferable to control the content to be not more than%. The addition amount of the inorganic sulfate of the present invention is such that the swelling ratio is 300%.
The addition amount that can be suppressed below is preferable.

This inorganic sulfate is added to the undercoat layer and / or the halogenated emulsion layer, and the addition amount is 1 g of gelatin.
The amount is preferably 0.01 to 1.0 g, and more preferably 0.1 to 0.5 g.

The support for the lithographic printing plate of the present invention includes:
Paper or a synthetic or semi-synthetic polymer film, a metal plate such as aluminum or iron, and the like can be used as long as they can withstand lithographic printing. The surface of the support may be coated on one side or both sides with one or more polymer films or metal thin films. The surface of these supports can be surface-treated in order to improve the adhesion with the coating layer. Particularly preferably used supports are paper having both surfaces or one surface coated with a polyolefin polymer, a polyester film, a polyester film having a hydrophilic surface, a surface-treated aluminum plate, and the like. These supports may contain pigments for preventing halation and solid fine particles for improving surface properties. The support may also be light transmissive so that backside exposure is possible.

In the present invention, the undercoat layer preferably contains gelatin as a binder. The amount of gelatin is generally 0.5 to 5 g / m ² , more preferably 1 to 4 g.
/ M ² . The preferred gelatin is inert deionized gelatin. Gelatin, if necessary,
Water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethyl cellulose, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, polyacrylamide, styrene-maleic anhydride copolymer, polyvinylmethyl ether-maleic anhydride copolymer It is also possible to substitute one or more hydrophilic polymers such as Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer.

In the present invention, the undercoat layer usually contains a pigment such as carbon black or a dye for the purpose of preventing halation. Further, in order to improve printing durability, solid powder (for example, silica particles) having an average particle diameter of 2 to 10 microns may be included. Further, photographic additives such as developing agents can be included. The undercoat layer is disclosed in JP-A-48-5503 and 48-1002.
03, and 49-16507.

The silver halide emulsion layer is, for example, silver chloride,
It comprises 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 and a platinum salt, and the addition amount is 10 ^-8 to 10 ^-3 per mol of silver halide. It is a mole. The crystal form of silver halide is not particularly limited, and may be cubic or tetradecahedral grains, or core-shell type or tabular grains. The silver halide crystal may be a monodisperse or polydisperse crystal,
The average particle size is in the range of 0.2 to 0.8 μm. One preferable example is a monodisperse or polydisperse crystal containing rhodium salt or iridium salt and having a silver chloride content of 80 mol% or more.

The silver halide emulsion can be sensitized in various ways as it is manufactured or coated. It is preferable to chemically sensitize by methods well known in the art, for example, with sodium thiosulfate, alkyl thiourea, or with a gold compound such as gold rhodanide, gold chloride, or a combination of both. The silver halide emulsions can also be sensitized or desensitized positively or negatively with dyes such as cyanines, merocyanines. There is no particular limitation on the wavelength range that can be sensitized or desensitized. Therefore, ortho sensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization, semiconductor laser sensitization can be performed, and UV sensitization and visible light desensitization for bright rooms. I can feel it. Although the binder of the silver halide emulsion layer is mainly composed of gelatin, a part thereof can be replaced with the hydrophilic colloid described in the above-mentioned undercoat layer structure. The amount of gelatin in the silver halide emulsion layer is appropriately about 0.3 to ² g / m ² , and preferably 0.5 to 1.5 g / m ² .

Examples of the hardener used in the present invention include inorganic compounds such as chromium alum, N-methylol compounds such as urea and ethylene urea, formaldehyde, glutaraldehyde, mucochloric acid, and 2,3-dihydroxy-1. , 4-dioxane-like aldehydes, 2,4
-Dichloro-6-hydroxy-s-triazine salt,
A compound having an active halogen such as 2,4-dihydroxy-6-chloro-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 It is possible to use one kind or two or more kinds of various compounds such as

These hardeners can be added to all layers or to some or only one layer. Of course, the diffusible hardener can be added to only one layer in the case of simultaneous multi-layer coating. As an addition method, it may be added at the time of producing the coating solution or may be added in-line at the time of coating.

The outer surface of the silver halide emulsion layer is coated with a physical development nucleus layer for constituting an image receiving layer in the silver complex salt diffusion transfer method. Physical development nuclei include fine particles of metal colloid such as silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold and platinum, and sulfides, polysulfides, selenides of these metals, or those. It may be a mixture or a mixed crystal. Further, the physical development nucleus layer preferably contains a hydrophilic binder in an amount of about 0.5 to 50 mg / m ² . The binder is starch,
Dialdehyde starch, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, polystyrene sulfonic acid, JP-A-53-21
Examples thereof include a copolymer of vinyl imidazole and acrylamide described in 602, and a copolymer of acrylamide and methyl sulfone substituted with guanyl thioureas described in the above-mentioned Hei 8-212614. Further, a developing agent such as hydroquinone, methylhydroquinone, catechol and the like, and the hardeners mentioned above may be contained. The pH of the coating solution is set to a weakly acidic to acidic range. Specifically, the pH is 1.6 to 4.
A range of 0 is reasonable. It is preferably in the range of 1.6 to 3.5.

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

The undercoat layer and the silver halide emulsion layer may be sequentially laminated, but most commonly, they can be simultaneously coated in a multilayer manner by a slide hopper coating technique. The applied web (support) is first guided and set in the chill zone. Subsequently, it is dried in a blast drying zone in which the temperature and humidity are controlled, but in the first half to the second half of the drying process (until the solid content concentration reaches 70 to 75%: constant-rate drying area), the web surface temperature during drying It is preferable to dry at (surface temperature of the surface coated with the silver halide emulsion layer) 15 ° C. or lower, more preferably 13.5 ° C. or lower.

After the stage where the solid content is concentrated to 70 to 75% or more (reduction rate dry zone), the temperature can be raised to some extent. When the web surface temperature (the surface temperature of the surface coated with the silver halide emulsion layer) is set to 40 ° C. or higher, preferably 50 ° C. or higher at the time point from the latter half of the reduction rate drying with a solid content concentration of 80% or more to the substantial drying. Good results can be obtained (image contrast, ink coverage, printing durability). If the temperature is 50 ° C., sufficient effect can be obtained by heating for 10 seconds. 1 above 70 ℃
It is also effective for processing in the order of seconds or less. Methods such as local warm air treatment, heat roll contact treatment, infrared heat treatment, far infrared heat treatment, and microwave heat treatment can be adopted.

A coating solution for a physical development nucleus layer is applied to the dried and optionally heat-treated web. The coating amount of the moisture of the coating liquid is preferably 15 g / m ² or less. As a coating method, dip coating, slide coating, bar coating, air knife coating, roll coating, gravure coating, spray coating and the like may be continuously applied. The drying temperature is not particularly limited, and drying is performed with warm air of 20 to 50 ° C.

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

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

[0032]

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

Example 1 An undercoated polyethylene terephthalate film having a thickness of 175 μm was prepared as a support. On one surface of this support, a backing first layer containing conductive carbon black (SD10M, manufactured by Dainippon Ink) 2 g / m ² and gelatin 1.5 g / m ² , silica particles having an average particle size of 3.5 μm the 0.1 g / m ^2, provided with the backing second layer of gelatin 1 g / m ² containing matting layer. Next, the following undercoat layer, silver halide emulsion layer, and physical development nucleus layer were coated on the opposite surface of the support in a tandem system.

<Undercoat Layer Coating Liquid> Gelatin 20 kg Silica fine particles 8 kg (Fuji Silysia Chemical Ltd. SY445; average particle diameter 3.5 μm) Carbon black dispersion liquid (solid content 32% by mass) 8 kg Styrene-butadiene latex 5 kg (POL752A manufactured by Nippon A & L Co., Ltd.) Surfactant 4 kg Inorganic sulfate 4 kg Adjust pH to 5.0. Make up to 400 kg with water. The amount of moisture applied is 40 g / m ² . Immediately before coating on the support, formalin was added so as to be 1 mmol per 1 g of gelatin. For comparison, formalin was added to the undercoat layer containing no inorganic sulfate so as to be 1 mmol per 1 g of gelatin.

The silver halide emulsion was prepared by the control double jet method in which potassium hexachloroiridium (IV) having a mean particle size of 0.33 μm was doped in an amount of 0.006 mmol per mol of silver, and 0.2 mol% of KI was added. A solution-converted silver chloride emulsion was prepared. Then, the precipitate was washed, washed with water, dehydrated, and redissolved. Further, this emulsion was subjected to sulfur-gold sensitization by a conventional method, a stabilizer was added, and then 3 mg of a sensitizing dye was added per 1 g of silver for dye ripening for spectral sensitization.

(Preparation of Emulsion Coating Solution) A coating solution was prepared by sequentially adding a surfactant, thiosalicylic acid and ethylenediaminetetraacetic acid sodium salt to the emulsion solution. 3.0 g / m ² and gelatin amount was produced lithographic printing plate applied and dried such that the 1.5 g / m ² with silver nitrate amount per square meter of the emulsion layer coating solution. <Silver Halide Emulsion Layer Coating Solution> Ortho-sensitized high-sensitivity silver chloride emulsion (silver nitrate conversion) 14 kg (silver nitrate / gelatin mass ratio = 2/1) Ethylenediaminetetraacetic acid sodium salt 0.09 kg Surfactant 7 kg thiosalicylic acid 0.6 kg 1-phenyl-3-pyrazolidone 0.15 kg N-methylol ethylene urea 0.8 kg formalin 0.7 kg pH is adjusted to 5.0. The total amount is adjusted to 120 kg. The amount of moisture applied is 12 g / m ² .

[0037] Liquid A and liquid B were mixed with stirring, and after 30 minutes, they were passed through a column filled with an ion exchange resin to obtain a palladium sulfide sol.

<Physical Development Nucleation Layer Coating Solution> Palladium Sulfide Sol 10 kg Hydroquinone 6 kg 1-Phenyl-3-pyrazolidone 0.4 kg Polymer 0.05 kg (Acrylamido (97) and Vinyl Imidazole (3) Copolymer ; Average molecular weight 100,000) Surfactant 0.02 kg Formalin (37% by weight aqueous solution) 1 kg Adjust the total amount to 100 kg. The amount of moisture applied is 10 g / m ² .

The undercoat layer coating solution and the silver halide emulsion layer coating solution described above were simultaneously multilayer coated by a slide hopper coating method and dried. Drying is divided into 5 zones,
The temperature and humidity can be adjusted respectively. The first zone was set at 0 ° C. and used for cooling and setting. 2nd, 3rd
The zone was used as a constant-rate drying section, and the web was dried at a maximum temperature of 14 ° C. (surface temperature of emulsion layer) at that section. The temperature of the web was raised to 30 ° C in the fourth zone and 40 ° C in the fifth zone. Fifth
The web residence time in the zone was 10 seconds. Subsequently, the physical development nuclei solution was applied by the dip / wire-squeeze method and dried with hot air at 30 ° C.

As a reference example, a lithographic printing plate was prepared by a conventional general manufacturing method. That is, an undercoat layer excluding inorganic sulfate and a silver halide emulsion layer were coated in multiple layers, wound up before coating the physical development nucleus layer, and heated at 40 ° C. for 7 days, and then the physical development nucleus layer was formed. A sample was prepared by coating.

The sample prepared as described above was exposed and developed with a plate-making camera to prepare a printing plate. The development treatment was carried out by the following silver complex salt diffusion transfer developer at 30 ° C. for 15 seconds.

<Developer> 700 ml of water 20 g of potassium hydroxide Anhydrous sodium sulfite 50 g 2-mercaptobenzoic acid 1.5 g 2-methylaminoethanol 15 g Add water to make 1 liter.

After the above-mentioned development processing, it was immersed in a stabilizing solution (neutralizing solution) shown below at 25 ° C. for 10 seconds and dried. <Stabilizer> Phosphoric acid 1.2 g Sodium monophosphate 25 g Ethylene glycol 5 g Monoethanolamine 5 g Water to make 1 liter. (Adjusted to pH 6)

Printing was performed on the printing plate prepared as described above. Ryobi 320 is used as a printing machine for printing.
0CD (trademark of Ryobi KK offset printing machine), ABdick3-1012 (trademark) as ink, and the following desensitizing solution (applied to the plate surface immediately before printing)
And using a dampening liquid.

<Desensitizing liquid> 600 ml of water Isopropyl alcohol 400 ml Ethylene glycol 50 g 3-mercapto-4-acetamido-5 -N-heptyl-1,2,4-triazole 1 g

<Moisturizing liquid> O-phosphoric acid 10 g Nickel nitrate 5 g Sodium nitrite 5 g Ethylene glycol 100 g Colloidal silica 28 g Add water to make 2L.

About this lithographic printing quality
Optical reflection density (D _min), Ink acceptance
And the printing durability were evaluated, and the results are shown in Table 1. D_min : Diffusion transfer physical development Macbeth is the reflection density of silver site
It was measured with a densitometer. The lower the reflection density, the clearer the image can be seen.
Well, the concentration is preferably 0.7 or less, and 0.65 or less.
Is more preferable. Ink acceptance: Marking of good printing ink density from the start of printing
The smaller the number of prints until the printed material is obtained, the better. Printing durability: After printing 100 sheets of normal print,
Turn off the ink / water supply roller and print 100 blank sheets.
To do. Turn on the ink / water supply roller again to 100
Perform normal printing of one sheet. Repeat this operation 10 times
The deterioration state of the printed image is compared with the initial printed matter. Print image
Reflection density step wedge (ΔD = 0.
03) Change of ink receiving point is the number of steps of step wedge
Displayed in. The smaller the change, the better the printing durability.
If the evaluation score is 3 or less, it is possible to print 10,000 sheets of normal print
It is a level.

[0048]

[Table 1]

From the above results, it can be seen that the present invention enables one-pass coating (tandem coating) without degrading printing performance.

[0050]

As is clear from the above results, according to the present invention, tandem coating can be performed without deteriorating the printing performance, and the production efficiency is greatly improved.

Claims (2)

[Claims] 1. A method for producing a lithographic printing plate, which comprises coating at least an undercoat layer and a silver halide emulsion layer on a support, drying the coated layer, and continuously coating the physical development nucleus layer without winding. A method for producing a lithographic printing plate, which comprises containing an inorganic sulfate in the undercoat layer and / or the halogenated emulsion layer. 2. The method for producing a lithographic printing plate as claimed in claim 1, wherein the inorganic sulfate is sodium sulfate, magnesium sulfate or calcium sulfate.