JP2921528B2 - Lithographic printing plate material - 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 material. In particular, the present invention relates to a lithographic printing plate material, in which a nonionic surfactant having an HLB of 6 to 14 is added to a lithographic printing plate material to provide high water retention to a non-image portion of the lithographic printing plate. It relates to a lithographic printing plate material characterized by being provided.

[0002]

2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image portion that receives ink and a hydrophilic non-image portion that does not receive ink. Generally, the non-image portion receives water. Therefore, in normal lithographic printing, ink and water are both supplied to the plate screen, the image area selectively receives ink, and the non-image area selectively receives water, and the ink on the image is transferred to paper. Done. Therefore, in order to obtain good printed matter, the difference between the lipophilicity and hydrophilicity of the surface of the image area and the non-image area is sufficiently large, and when the emulsified water-ink comes, the image area is It is necessary to receive ink sufficiently and the non-image area to receive water sufficiently. The planographic printing plate relating to the present invention is also printed based on the same principle.

One of the lithographic printing materials according to the present invention is a lithographic printing plate to which a silver complex salt diffusion transfer method is applied. This printing plate material has a silver precipitate nucleus in or on the surface of the hydrophilic polymer binder layer, a silver image is formed on the silver precipitate nucleus by silver complex salt diffusion transfer treatment, and the silver image is made ink receptive, The surface of the hydrophilic binder in the non-image area is subjected to printing as ink repellency. Since the surface of the hydrophilic binder itself is hydrophilic, but poor in water retention and the resilience of the printing ink is extremely poor, the ink stains on the non-image area due to printing are remarkable and are not practically practical. As a method of improving the ink repellency of the surface of this type of binder, it is known that the surface is roughened by means such as dispersing fine particle powder such as silica and starch in the binder layer to impart water retention. I have. However, the ink repellency obtained by these methods is still insufficient, and when printing is performed by supplying ink and water, ink stains occur on the non-image portion of the printed matter. This phenomenon becomes remarkable as the number of prints increases.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lithographic printing plate in which the surface of a hydrophilic binder layer is made ink-removable, the speed of ink removal of a lithographic printing plate is improved, and the ink stain on a non-image area is improved. To provide a printing plate material. The ink desorption speed referred to here is the speed from when ink is applied to the entire surface of a lithographic printing plate in the absence of dampening water and when printing starts when dampening water is fed and ink is removed from the non-image area of the plate surface. Means This is because paper waste can be suppressed by improving the ink-water responsiveness of the printing plate, such as when the ink is applied at the initial printing stage or when the non-image area is accidentally stained. is important.

[0005]

Means for Solving the Problems In a lithographic printing plate material for making the surface of a hydrophilic binder layer ink-releasable, HLB is used.
= 6 to 14 inclusive of a nonionic surfactant. Further, the present invention can provide not only the improvement of the stain resistance of the non-image portion of the printed matter, but also the effect of improving the water retention and improving the ink desorption speed.
The present invention is suitable for a lithographic printing plate which makes a silver image ink-receptive, particularly a lithographic printing plate material which makes a silver image formed on a silver precipitation nucleus by silver complex salt diffusion transfer method ink-receptive.

The surfactant is generally used as a wetting agent for improving the wetting when the hydrophilic polymer binder layer is formed on a suitable belt-like substrate, but HLB = 6 to 14
Surfactants outside the range do not have the effect of the present invention and cannot prevent ink staining of the non-image area due to printing.
Surfactants are roughly divided into anions, cations, nonions,
And amphoteric types other than betaine, but in the present invention, a nonionic surfactant is basically preferred.

Next, specific examples of the surfactant used in the present invention will be described. However, the present invention is not limited to these, and two or more of these surfactants may be used in combination. The next surfactant among the surfactants is HLB = 6-1.
4 range. (1) Sorbitan monopalmitate
[HLB = 6.7] (2) Sorbitan monolaurate [HLB = 8.6] (3) Combination of polyoxyethylene and sorbitan monooleate [HLB = 9.6] (4) Combination of polyoxyethylene and sorbitol tetraoleate [HLB = 11.8] (5) Combined use of polyethylene glycol and monolaurate
[HLB = 13.7]

As a comparison of the activators used in the present invention,
The following activators are mentioned. (1) Sorbitan trioleate [HLB = 1.8] (2) Sorbitan sesquiolate [HLB = 3.7] (3) Sorbitan monostearate [HLB = 4.7] (4) Combined use of polyoxyethylene and sorbitan monostearate [HLB = 14.9] (5) Combination of polyoxyethylene and sorbitan monooleate [HLB = 15.0] (6) Combination of polyoxyethylene and sorbitan monolaurate [HLB = 16.7] (7) Combination of polyethylene glycol and monostearate [HLB = 19.1] These surfactants are known and can be obtained as commercial products.

The hydrophilic binder forming the ink-repellent surface layer used in the present invention includes gelatin, acylated gelatin, grafted gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acrylamide, carboxymethyl cellulose, hydroxymethyl cellulose, and polyvinyl. Methyl ether, methyl vinyl ether-Maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-Maleic anhydride copolymer, condensate of polyvinyl alcohol and styrene maleic anhydride copolymer, polyvinyl alcohol and isobutylene A maleic anhydride copolymer condensate, gum arabic, albumin, sodium alginate, cellulose sulfate, JP-A-53-2160
Various natural or synthetic polymers such as the polyfunctional synthetic polymer described in JP-A No. 2 (1993) -207 are used alone or in combination of two or more. This ink-repellent surface layer, together with a hydrophilic binder, silver chloride emulsions such as silver chloride, silver bromide, silver chlorobromide, silver iodobromide, silver chloroiodobromide, gold, silver, copper, platinum, Silver precipitation nuclei such as heavy metals such as palladium and zinc or sulfide colloids thereof, hydroquinone, 1-phenyl-3
-It may contain a developing agent such as pyrazolidone. The composition for forming the layer adjacent to the surface layer in the present invention is the same as that of the surface layer, and the description thereof is omitted. However, in practice, they may be the same or different. In the present invention, an adjacent layer to the surface layer may not necessarily be present. In order to impart sufficient mechanical strength as a printing plate to the surface layer and the surface layer, as a hardening agent for a hydrophilic binder contained, formalin, glyoxal, glutaraldehyde, tannic acid, dimethylol urea, ethylene Organic compounds such as urea resin, mucohalic acid (mucochloric acid, mucobromic acid), and inorganic compounds such as chromium alum and potassium alum are used as necessary.

As described above, the present invention, when applied to a lithographic printing plate material having a roughened hydrophilic binder surface,
The most preferable result is obtained, but as a method of forming a roughened surface, a method of using a support having a roughened surface, a method of molding the surface of a hydrophilic binder layer using a roughened roll or the like, There are a method of including fine particle powder on the surface of the binder layer and a method of combining these. These appropriate combinations will produce more favorable results in the present invention. For example, an embodiment in which a hydrophilic binder layer containing fine particle powder is provided on a support having a roughened hydrophobic resin surface is a typical embodiment of the present invention. Roughening of a support having a hydrophobic surface is carried out by a solvent processing method,
It can be obtained by a foaming method, a crimping method using a rough body, or the like. It is preferable that these rough surfaces have a depth of 2 to 20 μm and a size of about 10 to 100 μm. Here, "depth" refers to the distance from the uneven valley on the surface to the top of the mountain, and "size" refers to the distance from the mountain to the mountain. Examples of the fine particle powder include silica, talc, clay, titanium oxide, barium sulfate, zinc oxide,
Rice starch and the like, and having an average particle size of about 0.8 to 15
μ is preferred.

As the support of the lithographic printing plate material of the present invention, polyethylene terephthalate, polycarbonate,
Synthetic resin films such as polypropylene and polystyrene,
Various materials such as a polyolefin-coated paper, a polyolefin laminated film or a composite support reinforced with aluminum can be used.

The printing plate obtained by using the lithographic printing plate material of the present invention is repelled by an ink repellent treatment liquid for desensitization performed as required during printing, and a dampening solution supplied during printing. Colloidal particles such as silica and alumina, and polyol compounds such as ethylene glycol, diethylene glycol, α-propylene glycol, and glycerin can be contained for the purpose of assisting the water retention of the functional surface.

The lithographic printing plate according to the present invention includes a direct-drawing lithographic printing plate, a lithographic printing plate in which a silver image obtained by applying a silver complex salt diffusion transfer method is ink-receptive, and an image exposure of a material coated with a silver halide emulsion. -A type in which the surface of a layer containing a hydrophilic binder is subjected to printing with ink repellency, such as a lithographic printing plate in which the silver halide image portion after development processing is made lipophilic and the ink is receptive. However, the present invention is not limited to these, but particularly, a lithographic printing plate having a silver image applied by a silver complex salt diffusion transfer method and having ink acceptability is most suitable.

Further, the surfactant used in the present invention comprises:
It can be used anywhere in the lithographic printing plate. In particular, in a lithographic printing plate having a silver image obtained by applying a silver complex salt diffusion transfer method and having ink acceptability, it can be used in any of an antihalation layer, an emulsion layer and a physical development nucleus layer.

The appropriate amount of the surfactant used in the present invention is such that the layer forming coating liquid has a concentration in the range of 1% to 0.01% in terms of moisture to improve the ink desorption rate and to reduce the background stain. The effect of prevention is shown.

Next, typical examples of the present invention will be described, but the present invention is not limited to these examples.

[0017]

【Example】

Examples 1 to 5 and Comparative Examples 1 to 7 The rough surface of a double-sided polyethylene-coated paper support having a roughened surface having an average depth of 7 μm and an average size of 50 μm is made hydrophilic by corona discharge. After the working, a solution having the following composition was applied so as to have a moisture content of 30 g / m ² . Gelatin 20g Silica (average particle size 7μ) 5g Formalin (12% aqueous solution) 3ml Carbon black dispersion (solid content 32%) 3ml Saponin (10% aqueous solution) 10ml Water is added to make the total amount 600g.

An ortho-sensitized high-sensitivity silver halide emulsion having the following composition was coated thereon by changing the type of surfactant as shown in Table 1 so as to obtain a moisture content of 30 g / m ^2. did. The silver halide emulsion (silver nitrate 25 g, silver chlorobromide was adjusted with gelatin 20g halide emulsion) 60 g silica (average particle size 7 microns) 1 g Formalin (12% aqueous solution) 3 ml surfactant (10% solution) ...... A Table 1) 10 ml of water is added to bring the total amount to 600 g.

Further, a palladium sulfide (silver precipitation nucleus) sol prepared by the following method was applied thereon at a speed of 5 m / min. Liquid A 5g Palladium chloride 5g Hydrochloric acid 40ml Water 1000ml Liquid B Sodium sulfide 8.6g Water 1000ml Liquid C Methyl vinyl ether / maleic anhydride copolymer (1.25% solution) 100ml Saponin (10% aqueous solution) 200ml Water 18000ml

The solution A and the solution B are mixed with stirring, and
After a minute, the solution was purified through a column containing an ion-exchange resin, to which solution C was added to obtain a coating solution.

The lithographic printing plate material thus obtained is subjected to image exposure with a camera having an image reversing mechanism, and is subjected to a development treatment at 30 ° C. for 30 seconds using a silver complex salt diffusion transfer developer having the following composition. Was. 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 development, the printing plate material is removed with a squeezing roller to remove the developing solution.
The mixture was treated at 20 ° C. for 20 seconds, the liquid was removed with a squeezing roller, and dried. Colloidal silica (20% solution) 1 g Citric acid 10 g Sodium citrate 35 g Water is added to bring the total volume to 1000 ml.

[0023]

[Table 1]

The lithographic printing plate produced by the above operation was mounted on an offset printing machine, and after the plate surface was treated with a desensitizing solution, printing was immediately performed. At that time, the following procedure was used. 1. Normal printing 2. Turn off the dampening solution so that the ink is applied to the entire surface of the plate. 3. Start feeding dampening water again. 4. After that, normal printing.

The number of printed sheets when the ink was detached from the plate surface was defined as the number of ink detached sheets, and the value was used to represent the difficulty of ink detachment and the degree of ink stain. The detachment of the ink from the plate surface was observed by measuring the density of the printed matter using a densitometer.

Example 6 The same roughened support surface as that used in Examples 1 to 5 was subjected to corona discharge machining, and then a coating solution having the following composition was applied at a moisture of 40 g / m ^2. It was applied so that Gelatin 20g Silica (average particle size 7μ) 5g Formalin (12% aqueous solution) 3ml Sorbitan monopalmitate (10% solution) 4ml Water is added to make the total amount 500g.

Next, a hydrosol composition solution of silver precipitation nuclei obtained by mixing the following solution A and solution B was applied to a moisture content of 15 g / m ² . Solution A Palladium chloride 1g Hydrochloric acid 20ml Water 250ml Solution B Sodium thiosulfate 4g Saponin (10% aqueous solution) 10ml Water 1000ml

The lithographic printing plate thus obtained was printed with the same photographic processing and printing processing as in the example, with the surfaces of the lithographic printing plate and the silver complex salt diffusion transfer negative material, which had been image-exposed beforehand, brought into close contact with each other. No ink stains occurred. Further, when a surfactant other than the range of HLB = 6 to 14 was used, a thin ink stain occurred on the entire printed matter.

[0029]

FIG. 1 shows the HLB of each surfactant used.
The relationship between the value and the number of ink detached from the hydrophilic binder film is shown. According to FIG. 1, those in the range of HLB = 6 to 14 are:
The ink hardly applied on the surface of the hydrophilic binder, and the ink detachment speed was high. The surface of the hydrophilic binder to which no surfactant was added did not release ink. In addition, in addition to the lithographic printing plate material which uses a silver complex salt diffusion transfer method to make a silver image ink-receptive, the non-image area is similarly obtained by using the nonionic surfactant having an HLB of 6 to 14 used herein. The result that the ink desorption speed was improved was obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the HLB value of each surfactant and the number of inks removed from a hydrophilic binder film.

Claims (1)

(57) [Claims] (1) In a lithographic printing material using a silver halide emulsion, HLB (Hydro-phile-lipophile balance) =
A lithographic printing material having a silver image as an ink-receptive material, wherein the material contains 6 to 14 nonionic surfactants.