JPH05303205A - Planographic printing plate - Google Patents

Abstract

PURPOSE:To improve an ink desorption rate by incorporating an amphoteric surfactant having amino acid skeleton into a physical development nucleus layer or its adjacent layer. CONSTITUTION:This planographic printing plate is formed by successively applying a primer coat layer, silver halide emulsion layer and physical development nucleus layer on a base. This printing plate contains the amphoteric surfactant having the amino acid skeleton in the physical development nucleus layer or its adjacent layer. Surfactants are used as a lubricant to improve wetting in general at the time of forming a hydrophilic high-polymer binder layer on a band-shaped base body, but the surfactants exclusive of the amino acid surfactant cannot increase the ink desorption rate. The amino acid surfactant is the N-amino acyl acid which is derived from various generally known amino acids and is introduced with a long-chain acyl group or its salt.

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, particularly a lithographic printing plate to which a silver complex salt diffusion transfer method is applied, and is characterized by imparting fast ink releasing property to a non-image area of a plate surface. Relating to planographic printing plate materials.

[0002]

2. Description of the Related Art A lithographic printing plate comprises an oleophilic image-forming portion that receives ink and a hydrophilic non-image-forming portion that does not receive ink, and the non-image-forming portion generally receives water. Therefore, in normal lithographic printing, both ink and water are supplied to the plate screen, and the image area selectively receives colored ink and the non-image area receives water to transfer the ink on the image to the paper. It is done by letting.

Therefore, in order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity between the surface of the image area and the non-image area is sufficiently large, and when the water-ink in the emulsified state comes, It is necessary that the line parts fully accept ink and the non-imprinted parts fully accept water. The lithographic printing plate relating to the invention is also printed on the basis of the same principle.

One of the lithographic printing plates relating to the present invention is a lithographic printing plate to which the silver complex salt diffusion transfer method is applied. This printing plate material has silver precipitation nuclei in or on the surface of the hydrophilic polymer binder layer, and the silver halide crystals in the emulsion layer undergo chemical development by silver complex salt diffusion transfer processing to become black silver and become hydrophilic. Form a non-image area. On the other hand, unexposed silver halide crystals become a silver salt complex by the silver salt complexing agent in the developing solution and diffuse to the physical development nucleus layer on the surface. An image area mainly composed of developed silver is formed. Here, the silver image is made ink-receptive, and the surface of the hydrophilic binder in the non-image area is made ink-repellent for printing. The surface of the hydrophilic binder is hydrophilic but poor in water retention, and the repulsion of the printing ink is extremely poor. Therefore, ink stains on the non-image area due to printing are remarkable, and it is not practical at all. As a method for improving the ink resilience on the surface of this kind of binder, it is known to roughen the surface by means such as dispersing fine particle powder such as silica or starch in the binder layer to impart water retention property. There is. However, the ink resilience obtained by these methods is still insufficient, and when printing is performed by supplying ink and water, ink stains are generated in the non-image area of the printed matter. These phenomena become remarkable as the number of printed sheets increases.

On the surface of the printing plate, the responsiveness to adsorption / desorption with the ink-water emulsion is important, and it is preferable that the responsiveness when changing the ink feed or water feed to set appropriate printing conditions is fast. Particularly in the field of offset rotary presses, in order to prevent paper breakage, etching with dampening water is often omitted at the start of printing, and ink adheres to non-image areas.
Therefore, the desorption speed of the ink is important at the time of rising, and the desorption speed of the ink is required. As a prior art for improving the ink resilience of the non-image area of the plate surface, Japanese Patent Publication No. 61-
Anion and betaine type surfactants described in 45227 are added to a plate. However, it is difficult to improve the ink desorption rate with these surfactants and the like, and the effect is slight.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate material having a hydrophilic binder layer surface as a non-image area to improve the ink desorption rate of the lithographic printing plate. .. The ink release speed here is the speed from the state of printing with the ink placed on the entire surface of the lithographic printing plate in the absence of dampening water until the time when the dampening water is fed and the ink is removed from the non-image area of the plate surface. Means

[0007]

[Means for Solving the Problems] The above-mentioned problems can be solved by using a lithographic printing plate to which a silver complex salt diffusion transfer method is applied.
It is achieved by containing at least one amphoteric surfactant having an amino acid skeleton in the physical development nucleus or in the layer adjacent thereto.

Surfactants are generally used as wetting agents for improving wetting when forming a hydrophilic polymer binder layer on a suitable strip-shaped substrate. However, surfactants other than amino acid type surfactants are not used. However, the effect of the present invention is slight, and it is not possible to accelerate the ink release rate or prevent ink stains on the non-image area. Surfactants are broadly classified into anions, cations, nonions, and amphoteric types other than betaine. The present invention has found that, among these surfactants, an amphoteric surfactant having an amino acid skeleton effectively achieves the object of the present invention.

[0009] The amino acid-based surfactants are those which are derivatized from various generally known amino acids (eg, glycine, glutamic acid, histidine, etc.), and N-aminoacyl acid having a long-chain acyl group introduced and That salt. These synthetic methods are described in Yoshinosuke Yoshida: “Organic Synthetic Chemistry” 33, 672 (1975) and the like.
For example, fatty acid residues such as coconut oil fatty acid, stearic acid, lauric acid, and palmitic acid are used in the long-chain acyl group portion.

The general formula of the amphoteric surfactant having an amino acid skeleton, which is preferably used in the present invention, is shown below.

[0011]

[Chemical 1] R is a long-chain alkyl group having 22 or more carbon atoms.

These surfactants are known and are commercially available. For example, from Ajinomoto Co., Inc., Amisoft CS-11, LS-11, GS-11, HS-11,
MS-11, DL-12, CT-12, LT-12, H
S-21, GS-21 and CS-21 are commercially available as a series. Two or more kinds of these surfactants may be used in combination.

The amino acid-based surfactant used in the present invention is a physical development nucleus of a lithographic printing plate obtained by sequentially coating at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer on a support. In a layer or in an adjacent layer,
It is desirable to contain 0.01 to 1% by weight, preferably 0.03 to 0.3% by weight.

In the present invention, the addition of the matting agent to the undercoat layer is known to roughen the plate surface and impart high water retention to the non-image area. The matting agent preferably used in the present invention is a solid powder having an average particle size of 1 to 10 microns, and examples thereof include silica particles and aluminosilicate. In the present invention, the average particle size is 1 to 5
Micron silica particles are preferred. In particular, silica particles surface-treated with hydrogen fluoride are preferable because they have excellent dispersion stability. Specific examples of silica particles include Syloid manufactured by Fuji Divison Chemical Co., Ltd. and Shilton AM manufactured by Mizusawa Chemical Co., Ltd.

In the present invention, the matting agent is preferably contained in the undercoat layer between the support and the silver halide emulsion layer, but may be contained in the emulsion layer. The amount of the matting agent added varies depending on various conditions and types, but is in the range of 0.1 g to 4.0 g per 1 m ² , preferably 1 m ^2.
It is in the range of 0.1 g to 2.0 g per unit.

Further, in the present invention, when titanium oxide is further added as a matting agent, the matting property of the plate surface becomes finer and finer irregularities are formed, so that higher water retention can be imparted. is there. The titanium oxide used in the present invention can be contained in the undercoat layer. The titanium oxide that can be used here may be any one such as an anase type and a rutile type, and may be surface-treated for the purpose of dispersion stability and the like. Titanium oxide is usually dispersed in water,
It is added at the time of makeup before application, but is not necessarily limited thereto. The amount of titanium oxide added varies depending on various conditions, but is in the range of 1 to ²⁰ g per 1 m ² .

The gelatin film has a swelling property in water and tends to slow the adsorption / desorption response of the film to the ink-water emulsion during printing. This is because the gelatin film absorbs the dampening water supplied to the plate surface before the saturated swelling of the gelatin film is reached.
Further, it is a phenomenon that it takes time for the dampening water to effectively act on the plate surface. Therefore, as the amount of gelatin is increased, the swelling action of the film is increased, the time required to reach an appropriate ink-water emulsion state is increased, and the adsorption / desorption response with the emulsion is further delayed.

On the other hand, if the amount of gelatin is too small, the water retentivity of the plate decreases, and as the number of printed sheets increases, the non-image area of the plate surface begins to become dirty. From the above, it is uncomfortable if the plate contains too much or too little gelatin. Therefore, in the present invention, the total amount of gelatin added in the undercoat layer, emulsion layer and physical development nucleus layer is 1 m.
The range of 1 g to 6 g per ² is preferable.

The hydrophilic binder forming the ink repellent emulsion layer used in the present invention is gelatin, acylated gelatin, graft gelatin, water-soluble gelatin, starch, dextrin, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylacrylamide. , Carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl methyl ether, methyl vinyl ether / maleic anhydride copolymer, styrene / maleic anhydride copolymer, isobutylene / maleic anhydride copolymer, polyvinyl alcohol and styrene maleic anhydride copolymer Condensate, condensate of polyvinyl alcohol and isobutylene / maleic anhydride copolymer, gum arabic, albumin, sodium alginate, cellulose sulfate, described in JP-A-53-21602. Tetrafunctional synthetic polymers such as various natural or synthetic polymers are used alone or in combination of two or more. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer. The lithographic printing plate which is the object of the present invention contains gelatin, and the containing layer may be an undercoat layer, an emulsion layer or a physical development nucleus layer.

The above emulsion layer has formalin, glyoxal, glutaraldehyde, tannic acid, urea, dimethylol urea, ethylene urea resin as a hardening agent for the gelatin contained in order to have sufficient mechanical strength as a printing plate. One or more N-methylol compounds, such as N-methylol compounds, organic compounds such as mucohalogen acids (mucochloric acid, mucobromic acid), and inorganic compounds such as chromium alum and potassium alum are used as necessary. The hardener can be added to all layers, or it is possible to add some or only one layer. Of course, the diffusible hardener can be added to only one layer in the case of simultaneous coating of two layers. As an addition method, it may be added at the time of emulsion production or in-line at the time of coating.

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, for example with sodium thiosulfate, alkyl thioureas, or with gold compounds such as gold rhodanide, gold chloride, or a combination of both. Further, the silver halide emulsion can be positively or negatively sensitized or desensitized with a dye such as cyanine or merocyanine. 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 do it.

On top of the emulsion layer is a physical development nucleus layer containing physical development nuclei. As the physical development nuclei, 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 mixed crystal. The physical development nucleus may or may not contain a hydrophilic binder, but gelatin, starch, dialdehyde starch, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, polystyrene sulfonic acid, vinyl imidazole and acrylamide It may contain a polymer, a hydrophilic polymer such as polyvinyl alcohol, or an oligomer thereof, and the content thereof is 0.5.
It is preferably g / m ² or less. Further, the physical development nucleus layer may contain a developing agent such as hydroquinone, methylhydroquinone and catechol, and a known hardener such as formalin and dichloro-s-triazine.

In particular, in a lithographic printing plate having a silver image to which the silver complex salt diffusion transfer method is applied as an ink-receptive material, a coating aid may be used in any of the antihalation layer, emulsion layer and physical development nucleus layer. As the cation, an anion or a neutral surfactant may be contained. The surfactant used here does not have the effect of improving the ink releasability unlike the above-mentioned amino acid-based surfactant, but has only the effect of improving the coatability. The proper amount of the surfactant used as the coating aid is preferably in the concentration range of 1% to 0.01% in terms of moisture in the layer forming coating liquid. Further, an antifoggant, a thickener, and an antistatic agent can be included.

The support of the lithographic printing plate material of the present invention includes polyethylene terephthalate, polycarbonate,
Synthetic resin film such as polypropylene and polystyrene,
Any material that can withstand lithographic printing, such as polyolefin-coated paper, polyolefin laminated film, or aluminum-reinforced composite support, can be used. Also,
The surface of these supports may be surface-treated in order to improve the adhesion with the coating layer.

The present invention is applicable to lithographic printing plate materials having a roughened hydrophilic binder surface. As a method for forming a roughened surface, a method using a support having a roughened surface, a method of molding the surface of the hydrophilic binder layer using a rough surface roll, etc., fine particles on the surface of the hydrophilic binder layer There are a method of incorporating powder and a method of combining these. The roughening of the support having a hydrophobic surface can be obtained by a solvent processing method, a foaming method, a pressure bonding method using a rough surface body, or the like. These suitable combinations give more favorable results in the present invention. The depth of these rough surfaces is preferably 2 to 20 μm and the size is about 10 to 100 μm. As used herein, "depth" means the distance from the uneven valley on the surface to the top of the mountain, and "size" means the distance from the mountain to the mountain.

The developing solution used in the present invention contains an alkaline substance such as sodium hydroxide or potassium hydroxide.
Lithium hydroxide, sodium triphosphate, sulfite as a preservative, silver halide solvent such as thiosulfate, thiocyanate, cyclic imide, 2-mercaptobenzoic acid, amine, etc., viscous agent such as hydroxyethyl cellulose,
Antifoggants such as carboxyethyl cellulose such as potassium bromide, compounds described in JP-A-47-26201, developers such as hydroquinones, catechol, 1
Development modifiers such as -phenyl-3-pyrazolidone and the like, such as polyoxyalkylene compounds and onium compounds, may be included. Further, in the developing solution, US Pat.
Compounds such as those described in Nos. 776 and 728, which improve ink transfer of the surface silver layer, can be used.

The printing plate obtained from the lithographic printing plate material of the present invention is ink repellent to a treatment liquid for desensitizing treatment which is carried out as necessary during printing, and further to dampening water supplied during printing. Colloidal particles such as silica and alumina, and a polyol compound such as ethylene glycol, diethylene glycol, α-propylene glycol and glycerin may be contained for the purpose of assisting the water retention of the surface.

[0028]

EXAMPLES Next, representative examples of the present invention will be explained, but the present invention is not limited to them.

Example 1, Comparative Example 1 A roughened surface of a double-sided polyethylene-coated paper support having a roughened surface with an average depth of 7 μ and an average size of 50 μ is hydrophilic by corona discharge. After processing, change the amount of gelatin to a liquid consisting of
It was applied so as to be c / m ² . Gelatin 3.5 g Silica (average particle size 7 μ) 10 g Titanium oxide 50 g Formalin (12% aqueous solution) 3 ml Carbon black dispersion (solid content 32%) 5 ml Saponin (10% aqueous solution) 10 ml Latex 50 g Add water to bring the total volume to 600 cc Do

Furthermore, an ortho-sensitized high-sensitivity silver halide emulsion having the following composition was added at a moisture content of 13 cc / m ²
Was applied so that Silver halide emulsion (silver chlorobromide emulsion prepared by using 15 g of silver nitrate and 12 g of gelatin) (gelatin, equivalent to 0.72 g / m ² ) 96 g Silica (average particle size 7 μ) 1 g Formalin (12% aqueous solution) 3 ml Interface Activator (10% solution) 10 ml Add water to bring the total volume to 130 cc

Further, a palladium sulfide (silver precipitation nucleus) sol prepared by the following method was added at a speed of 15 m / min.
And 80 mmHg of wind pressure. Liquid A Palladium chloride 2 g Water 20 ml B liquid Sodium sulfide 0.2 g Water 20 ml C liquid Methyl vinyl ether / maleic anhydride copolymer (1.25% solution) 20 ml Saponin (10% aqueous solution) (as coating aid) 20 ml Hydroquinone 50 g 1-Phenyl-3-pyrazolidone 5 g Formalin 30 ml Surfactant 12.5 ml (see Table 1) Water is added to bring the total volume to 1250 cc.

Mix solution A and solution B with stirring,
After a minute, this was added to the liquid C to obtain a coating liquid.

[0033]

[Table 1]

The lithographic printing plate material thus obtained was subjected to image exposure for 20 seconds with a camera having an image reversal mechanism, and a silver complex salt diffusion transfer developer having the following composition was used.
Development processing was performed at 30 ° C. for 30 seconds. Sodium hydroxide 20 g Anhydrous sodium sulfite 100 g Hydroquinone 12 g 1-Phenyl-3-pyrazolidone 1 g Sodium thiosulfate 16 g Potassium bromide 3 g 1-Ethyl-2-mercaptobenzimidazole 0.05 g 3-Mercapto-4-acetamido-5-n- Heptyl-1,2,4-triazole 0.1 g Water is added to bring the total volume to 2000 ml.

After the developing treatment, the printing plate material was removed with a squeezing roller to remove the developing solution, and a neutralizing solution having the following composition was used to remove the developing solution.
The solution was treated at 20 ° C. for 20 seconds, removed by a squeezing roller, and dried. Colloidal silica (20% solution) 1 g Sodium sulfite 10 g Potassium phosphate 50 g Water is added to make 1000 ml.

The planographic printing plate prepared by the above operation was mounted on an offset printing machine, the plate surface was treated with a desensitizing solution, and printing was immediately performed. At that time, the procedure was as follows. 1. Normal printing 2. Stop feeding the dampening water so that the ink can be applied to the entire plate surface. 3. Pause and leave 4. Start feeding dampening water again. 5. Then print normally

The printing conditions at that time are as follows. Printer: RYOBI 3200 Ink: NEW-CHAMPION Purple (S) (manufactured by DIC) Moisturizing liquid: Eu-3 1% aqueous solution (manufactured by Fuji Photo Film Co., Ltd.) Printing speed: 4000 sheets / hour

The number of printed sheets when the ink was released from the plate surface was defined as the number of released inks, and the ink release rate was evaluated from the value. In addition, the degree of ink stain and the state of the ink detached from the plate surface were observed and evaluated by measuring the reflection density of the printed matter with a densitometer.

Table 2 shows the results of the kinds of surfactants added to the physical development nuclei layer and the number of printed sheets at the completion of ink removal in the non-image area of the plate surface.

From Table 2, it can be seen from the comparison between the case where the amino acid type surfactant is used (Example 1) and the case where the comparative surfactant is used (Comparative Example 1). It was confirmed that the desorption rate was increased. Also,
When printing 1000 sheets, the non-image area of the plate surface did not stain.

[0041]

[Table 2]

Example 2, Comparative Example 2 Next, an undercoat layer, an emulsion layer (similar to Example 1), and a physical development nucleus layer (no amino acid type surfactant was added) were applied in that order, and then the following was further applied. By providing an overlayer of the composition of
The ink desorption rate was evaluated under the same development processing and printing conditions as in Example 1. Surfactant 3 g Sodium hydroxide 0.1 g Water is added to bring the total volume to 1000 ml.

Table 3 shows the relationship between the kind of the surfactant added to the physical development nuclei layer and the number of printed sheets at the completion of deinking of the non-image area of the plate surface.

From Table 3, comparing the case of using the amino acid-based surfactant (Example) and the case of using the comparative surfactant (Comparative Example 2), ink removal using the amino-acid-based surfactant was performed. It was confirmed that the separation speed became faster. Further, among the comparative surfactants used, there were some that did not remove the ink from the plate surface even if printing was continued, and contaminated.

[0045]

[Table 3]

[0046]

According to the embodiment of the present invention, there is provided a lithographic printing plate which has a high stain resistance of the non-image area of the plate surface and a high ink desorption rate and a fast desorption response of the ink-water emulsion. be able to.

Claims (1)

[Claims] 1. A lithographic printing plate obtained by sequentially coating at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer on a support, wherein an amphoteric surfactant having an amino acid skeleton is physically added to the support. A lithographic printing plate which is contained in a development nucleus layer or in a layer adjacent thereto.