JP3345556B2 - Plate making method of lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for making a lithographic printing plate utilizing a silver complex salt diffusion transfer method using an aluminum plate as a support.

[0002]

2. Description of the Related Art A planographic printing plate using a silver complex salt diffusion transfer method (DTR method) is described in "Photographic Silver Halide," published by Focal Press, London New York (1972), by Andrelot and Edith Weide. Some examples are described in "Diffusion Processes", pp. 101-130.

As described therein, a lithographic printing plate using the DTR method includes a two-sheet type in which a transfer material and an image receiving material are separated, or a monolithic type in which they are provided on a single support. Two types of sheet type are known.
A two-sheet type lithographic printing plate is disclosed in
This is described in detail in JP-A-158844. For the mono-sheet type, see JP-B-48-30562.
No. 51-15765, JP-A-51-111103
And JP-A Nos. 52-150105.

A lithographic printing plate of the monosheet type utilizing a silver complex salt diffusion transfer method using an aluminum plate as a support (hereinafter referred to as an aluminum lithographic printing plate), which is an object of the present invention, is disclosed in JP-A-57-118244. No. 57-158
Nos. 844 and 63-260491, JP-A-3-116
No. 151, 4-282295, U.S. Pat.
Nos. 7,131, 5,427,889 and the like.

[0005] The aluminum lithographic printing plate has a structure in which a physical development nucleus is supported on a roughened and anodized aluminum support, and a silver halide emulsion layer is further provided thereon. The general method of making a lithographic printing plate is
After exposure, development, washing (removal of the silver halide emulsion layer), and finishing are performed.

More specifically, a metal silver image portion is formed on a physical development nucleus by a development process, and a silver halide emulsion layer is removed by a subsequent washing process to form a metal silver image portion (hereinafter referred to as silver) on an aluminum support. Image portion) is exposed. At the same time, the anodized aluminum surface itself is exposed as a non-image area.

The exposed silver image area and the non-image area are coated with a finishing solution containing a protective colloid such as gum arabic, dextrin, carboxymethylcellulose, polystyrene sulfonic acid and the like for protection. A so-called gumming process is performed. This finishing solution is also called a fixing solution or a finishing solution, and generally contains a compound that makes the silver image area lipophilic (hereinafter, referred to as a lipophilic agent).

One of the serious problems in the method of making an aluminum lithographic printing plate is a problem of removing gelatin from a silver halide emulsion layer during a water washing process. In the aluminum lithographic printing plate, the removal of the silver halide emulsion layer by water washing is a very important step for completely exposing the silver image portion and the non-image portion constituted by the aluminum surface itself. In particular, the silver image portion receiving the ink needs to have strong lipophilicity, and it is necessary to completely remove substances that inhibit lipophilicity such as gelatin.

The above-mentioned water-washing treatment is carried out by spraying a water-washing liquid at 25 to 35 ° C. by a jet method to peel and remove the emulsion layer.
Alternatively, a method of peeling the emulsion layer with a scrub roller while spraying a washing liquid is generally adopted. However, it is difficult to completely remove the emulsion layer by such a physical peeling and removing method, and there is a problem that water retention and ink acceptability are reduced.

On the other hand, the washing liquid is circulated through a filtration filter to collect the components of the emulsion layer eluted or dispersed in the washing liquid, for example, gelatin and silver ions, and to reuse the washing liquid. ing. Therefore, it is preferable to efficiently filter the components of the emulsion layer eluted or dispersed in the washing solution for the reuse of the washing solution, but at present it is not possible to sufficiently collect by filtration. there were. In particular, gelatin dissolved in the washing solution easily rots and deteriorates the working environment. Further, if the amount of gelatin dissolved in the washing liquid increases due to the running treatment, the gelatin in the washing liquid is re-adhered to the aluminum surface and the silver image area, and the ink receptivity and water retention were reduced.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a method of making an aluminum lithographic printing plate having excellent ink acceptability and water retention. Another object of the present invention is to provide a plate making method capable of efficiently filtering an emulsion layer component eluted or dispersed in a washing solution. Still another object is to maintain the performance of the washing liquid in the running process, and to maintain ink acceptability and water retention.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lithographic printing plate having a physical development nucleus between an aluminum support and a silver halide emulsion layer. Wherein the developer and / or water washing solution contains an anionic organic gelatin flocculant (hereinafter, referred to as a flocculant). Was.

The gelatin used in the silver halide emulsion layer is water-soluble, but it is difficult to completely remove the gelatin adhering to the aluminum surface having microscopic irregularities by washing with water. there were. Then, the present inventor focused on aggregation of gelatin as a result of earnest research. As described above, the washing and removal of the emulsion layer was generally carried out by a physical method.However, it was an unexpected finding that it was easy to separate gelatin from the aluminum surface and the silver image area by coagulating gelatin. there were.

It is considered that when the flocculant is contained in the developer, the flocculant is adsorbed on the emulsion layer, and the pH is lowered by the next washing solution, whereby the gelatin is flocculated and easily removed. Also, when a coagulant is contained in the washing liquid, it is considered that the separated gelatin is easily aggregated by a scrub roller or the like to facilitate removal. Therefore, the coagulant is contained in the developing solution or the washing solution to facilitate the removal of gelatin, and the coagulant is contained in both the developing solution and the washing solution to obtain a further effect.

Including a flocculant in the developing solution or the washing solution improves the efficiency of filtration and recovery of gelatin dissolved in the washing solution, and prevents the decomposition of gelatin due to running processing. Further, when the amount of gelatin eluted in the washing liquid is reduced, re-adhesion to the aluminum surface and the silver image area does not occur, and therefore, a decrease in ink receptivity and water retention (stain resistance) in the running process can be prevented. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Anionic organic gelatin flocculant used in the present invention,
A gelatin flocculant used in a desalting water washing step after physical ripening of the silver halide emulsion can be used.

Examples of the coagulant used in the present invention include phenol aldehyde resins having a sulfonic acid group described in JP-B-35-16765, and JP-B-46-434.
No. 29, a copolymer containing a maleic hydrazide derivative in the main chain, a copolymer of paravinylbenzene sulfonate and another vinyl compound described in JP-B-49-24283, JP-A-51-61823. 2-acrylamido-2-methylpropanesulfonic acid polymer described above and a copolymer with another vinyl compound; poly-β-naphthomethylenesulfonic acid described in JP-A-54-7321;
No. 3031, non-polymeric sulfonic acid or sulfuric acid such as naphthalenedisulfonic acid and derivatives; long-chain alkylsulfonic acid and sulfuric acid such as various anionic wetting agents; flocculants described in JP-A-51-61823;
No. 24, the coagulant described in JP-A-55-45066, U.S. Pat. No. 2,772,165 and British Patent No. 6
No. 48472, and the like.

Generally, a polymer having a relatively small molecular weight (average molecular weight of several thousands to tens of thousands) is used as a flocculant used in the desalting and washing step after physical ripening, but the flocculant used in the present invention has a limited molecular weight. Not used in a wide range.
The amount of addition may be adjusted according to the molecular weight. Therefore, those having an average molecular weight of about several thousands to one million are used.
Coagulants having different molecular weights may be used in combination. Among the above flocculants, polystyrene sulfonic acid or a copolymer of polystyrene sulfonic acid and maleic anhydride is preferably used.

In the present invention, the amount of the coagulant added to the developing solution and / or the washing solution is preferably 1 to 100 g / l, more preferably 5 to 50 g / l. If the amount of the coagulant is less than 1 g / liter, the removal of gelatin will be insufficient, and if it is more than 100 g / liter, poor development and sludge will tend to occur due to thickening of the gelatin in the developer.

In the developer used in the present invention, in addition to the coagulant, a developing agent such as polyhydroxybenzenes, 3-pyrazolidinones, or an alkaline substance such as potassium hydroxide, sodium hydroxide, lithium hydroxide, Third
Sodium phosphate, or an amine compound, a preservative such as sodium sulfite, a thickener such as carboxymethyl cellulose, an antifoggant such as potassium bromide, a development modifier such as a polyoxyalkylene compound, a silver halide solvent such as Additives such as thiosulfate, thiocyanate, cyclic imide, thiosalicylic acid, mesoionic compounds and the like can be included. The pH of the developer is usually 10
To 14, preferably 12 to 14. Further, a lipophilic agent for making the silver image lipophilic can be contained. As the lipophilic agent, a compound having a mercapto group or a thione group described below is preferable.

The pH of the washing solution used in the present invention is 4-9.
The pH is preferably about 8 or less, particularly preferably about 7 or less. In addition to the flocculant, the pH of the washing solution is 4 to
7, preferably a buffer buffering in the range of 5 to 7, for example a phosphate buffer, a citrate buffer or a mixture thereof. Further, a preservative may be contained. Further, it is preferable to include a proteolytic enzyme in the washing solution, and in combination with a gelatin flocculant,
Gelatin is decomposed and removed more effectively, and ink receptivity is further improved.

The proteolytic enzyme used in the present invention is a known vegetable or animal enzyme capable of hydrolyzing proteins such as gelatin. For example, pepsin, rennin, trypsin, chymotrypsin, cathepsin, papain, ficin, thrombin, renin, collagenase, bromelain, bacterial proteinase (for example, bioprase manufactured by Nagase & Co., Ltd.) and the like can be mentioned. Among these, trypsin, papain, ficin, and bacterial proteinase are particularly preferred. The appropriate content of the enzyme in the washing solution is about 0.5 to 50 g / liter.

The washing liquid preferably further contains a compound having a mercapto group or a thione group. As the compound having a mercapto group or a thione group, those described in JP-B-48-29723 and JP-A-58-127728 are preferably used. In particular, a nitrogen-containing heterocyclic compound having a mercapto group or a thione group is preferable, and examples thereof include compounds having a general formula shown in the following Chemical Formula 1.

[0024]

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(Wherein R ₁ and R ₃ are an alkyl group, alkenyl group, aralkyl group or aryl group having 3 or more carbon atoms, preferably 3 to 12 carbon atoms, and R ₂ is a hydrogen, an alkyl group, an alkenyl group or an aralkyl group). Or an aryl group.
n represents an integer of 1 or more. When R ₂ is an alkyl group, alkenyl group, aralkyl group or aryl group having 3 or more carbon atoms, n may be 0. Z is N, C in the formula
And the remaining atomic groups of the bond necessary to form a 5- or 6-membered ring with the above. )

Specific examples of the 5- or 6-membered ring include imidazole, imidazoline, thiazole, thiazoline,
Oxazole, oxazoline, pyrazoline, triazole, thiadiazole, oxadiazole, tetrazole, pyridine, pyrimidine, pyridazine, pyrazine, triazine, etc., and these rings may be two or more condensed rings; And those condensed with a naphthalene ring. Further, it is preferable that the compound does not have a water-soluble group such as a carboxy group and a sulfo group.

Specific examples of such compounds include 2-mercapto-4-phenylimidazole and 2-mercapto-1
-Benzylimidazole, 2-mercapto-1-butyl-benzimidazole, 1,3-dibenzyl-imidazolidin-2-thione, 2-mercapto-4-phenylthiazole, 3-butyl-benzothiazoline-2-thione, 3- Dodecyl-benzothiazoline-2-thione, 2
-Mercapto-4,5-diphenyloxazole, 3-
Pentyl-benzoxazoline-2-thione, 1-phenyl-3-methylpyrazolin-5-thione, 3-mercapto-4-allyl-5-pentadecyl-1,2,4-triazole, 3-mercapto-5-nonyl-1 , 2,4
-Triazole, 3-mercapto-4-acetamide-5
-Heptyl-1,2,4-triazole, 3-mercapto-4-amino-5-heptadecyl-1,2,4-triazole, 2-mercapto-5-phenyl-1,3,4
-Thiadiazole, 2-mercapto-5-n-heptyl-oxathiazole, 2-mercapto-5-nheptyl-oxadiazole, 2-mercapto-5-phenyl-
1,3,4-oxadiazole, 2-heptadecyl-5
-Phenyl-1,3,4-oxadiazole, 5-mercapto-1-phenyl-tetrazole, 3-mercapto-4-methyl-6-phenyl-pyridazine, 2-mercapto-5,6-diphenyl-pyrazine, -Mercapto-4,6-diphenyl-1,3,5-triazine, 2-
Amino-4-mercapto-6-benzyl-1,3,5-
Examples include, but are not limited to, triazines.

The content of the compound having a mercapto group or a thione group in the washing solution is suitably about 0.01 to 10 g / liter.

In the present invention, when the compound having a mercapto group or a thione group is contained in the washing solution, the silver ions eluted in the washing solution can be recovered by filtration, and the washing solution can be prevented from being clouded by silver ions. I do. On the other hand, as described above, the incorporation of a flocculant in the processing solution (developing solution and / or washing solution) is effective for efficiently removing the emulsion layer on the aluminum support. There is an advantage that the gelatin eluted at the time of the treatment is easily collected from the washing liquid with a filter. Therefore, by using a coagulant and a compound having a mercapto group or a thione group together, it is possible to remove emulsion layer components such as gelatin and silver ions from the washing solution, and to reuse a clean washing solution without contamination.

Including a compound having a mercapto group or a thione group in the washing solution is effective in removing gelatin by a gelatin flocculant or a protease thereof and a protease, and as a result, the compound having a mercapto group or a thione group is not removed. Adsorption to a silver image is promoted, and further, ink receptivity and printing durability are improved.

The washing solution is used to completely remove the silver halide emulsion layer on the aluminum support, and is usually sprayed with a washing solution at 25 to 35 ° C. by a jet method, or scrubbed while spraying the washing solution. A method of peeling the emulsion layer with a roller is employed.

The silver image portion and the non-image portion exposed by the washing process are subjected to a treatment with a finishing liquid in order to increase their lipophilicity and hydrophilicity and to protect the plate surface.
In the present invention, in addition to the lipophilic agent in the finishing solution, for protecting the anodized layer of the non-image area and improving the hydrophilicity, arabic gum, dextrin, sodium alginate, propylene glycol ester of alginic acid, hydroxyethyl starch, It is preferable to contain a protective colloid such as carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polystyrenesulfonic acid, and polyvinyl alcohol.

The lithographic printing plate of the present invention has a physical development nucleus and a silver halide emulsion layer on an aluminum support. The silver halide emulsion is selected from commonly used silver chloride, silver bromide, silver iodide, silver chlorobromide, silver chloroiodobromide, silver iodobromide, etc., but mainly contains silver chloride (50 mol of silver chloride). %). The emulsion type may be either a negative type or a positive type. These silver halide emulsions can be chemically or spectrally sensitized as necessary.

As the gelatin used for the silver halide emulsion layer, various gelatins are used, and alkali-treated gelatin is preferable. Further, hydrophilic polymer compounds such as polyvinylpyrrolidone, various starches, albumin, polyvinyl alcohol, gum arabic, and hydroxyethyl cellulose can be contained. As the hydrophilic colloid to be used, it is desirable to use a hydrophilic colloid layer substantially free of a hardener in order to facilitate the peelability after development. Gelatin content of the silver halide emulsion layer 1 to 5 g / m ^2, preferably from 2 to 4 g / m ² approximately.

The aluminum support used in the present invention is a roughened and anodized aluminum plate, preferably the one described in US Pat. No. 5,427,889.

The physical development nucleus of the physical development nucleus layer used in the present invention may be a physical development nucleus used in a known silver complex salt diffusion transfer method, for example, a colloid such as gold or silver, or a water-soluble salt such as palladium or zinc. Metal sulfide mixed with sulfide can be used. Various hydrophilic colloids can be used as the protective colloid. For details and manufacturing method,
For example, Focal Press, London New York (1972), Andre Lott and Edith
See Weide, "Photographic Silver Halide Diffusion Processes".

In the present invention, a water-swellable intermediate layer described in JP-A-3-116151 may be provided between the physical development nucleus layer and the silver halide emulsion layer.

[0038]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 The electrolytic surface roughening treatment and anodic oxidation of an aluminum support were carried out according to the method described in US Pat. No. 5,427,889 on a plateau having an average diameter of about 5 μm.
0.35 μm pits of about 5,60 per 100 μm ²
0 pits and the average diameter of these pits is 0.08μ
m of an aluminum plate having a thickness of 0.30 mm was obtained. This aluminum plate is anodized after roughening treatment.
The average roughness (Ra) was 0.5 to 0.6 μm.

The aluminum support was coated with a physical development nucleus solution composed of a silver sol prepared by the Curey Lea method, and then dried. The amount of silver contained in the physical development nucleus layer was 3 mg / m ² .

As a silver halide emulsion, alkali-treated gelatin was used as a protective colloid, and potassium hexachloroiridate (IV) having an average particle size of 0.2 μm was added in an amount of 0.006 m per mol of silver by a control double jet method.
A mol-doped silver chloroiodobromide emulsion (AgBr 20 mol%, AgI 0.4 mol%) was prepared. Further, this emulsion was subjected to sulfur gold sensitization, and the sensitizing dye of the formula (2) was added in an amount of 3 per gram of silver.
mg was used for spectral sensitization.

[0042]

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A surfactant was added to the silver halide emulsion thus prepared, and the silver amount was 2 g / m ² and the gelatin (alkali-treated gelatin) was 3 g / m ² on the aluminum support coated with the physical development nuclei. m ^2, and the coating was obtained a lithographic printing material was dried.

A 633 nm red LD was used for the lithographic printing material.
An image was output by an output machine using a laser as a light source, and then processed by a plate-making processor (SLT-N automatic developing machine manufactured by DuPont) to prepare a lithographic printing plate. The plate making processor includes a developing step (immersion at 21 ° C. for 30 seconds), a water washing step (peeling the emulsion layer with a scrub roller while spraying a washing liquid at 33 ° C. for 10 seconds), and a finishing step (21 ° C. 5 seconds shower) and a drying step. The rinsing process of the plate-making processor uses three rinsing liquids.
It consists of a tank that stores 0 liters, a unit that feeds the lithographic printing material from the tank to the lithographic printing material via a pump to remove the emulsion layer, and a unit that circulates the washing water from the tank through a filter installed outside the system. . As the filtration filter, a cylindrical 5 μm filter was used.

A 100 plate plate making process was performed using the following developing solution, washing solution and finishing solution. <Developer A> Sodium hydroxide 20 g Hydroquinone 20 g 1-Phenyl-3-pyrazolidinone 2 g Anhydrous sodium sulfite 80 g Monomethylethanolamine 6 g Anhydrous sodium thiosulfate 6 g Ethylene diamine tetraacetate sodium salt 5 g Polyethylene glycol (average molecular weight 400) 10 g To 1000 cc. pH is 1
It was adjusted to 3.0.

<Developer B> 10 g of polystyrene sulfonic acid having an average molecular weight of 500,000 as an aggregating agent was added to the above developer A.
added.

<Washing Solution A> 40 g of first potassium phosphate Water is added to adjust the total amount to 1000 cc. pH is 6.
Adjusted to zero.

<Washing solution B> A polystyrene sulfonic acid having an average molecular weight of 500,000 was added to the washing solution A as a coagulant.
g was added.

<Washing solution C> To the washing solution B was added 2 g of a proteolytic enzyme (bioprase AL-15).

<Finishing solution> Gum arabic 10 g Proteolytic enzyme 2 g 2-mercapto-5-nheptyl-oxadiazole 1 g Triethanolamine 26 g Sodium monophosphate 10 g Water is added to adjust the total amount to 1000 cc. pH 6.0
Was adjusted. Proteolytic enzyme is Bioprase AL
−15.

For the first and 100th lithographic printing plates prepared by the method described above, the printing press Heidelberg T
Printing was performed using OK (a trademark of an offset printing machine manufactured by Heidelberg), ink (New Champion Boku H, manufactured by Dainippon Ink and Chemicals Co., Ltd.), and a commercially available humidifying solution for PS plates. Ride) was evaluated. The water retention was performed by changing the ink to a low-viscosity ink (New Champion Purple S manufactured by Dainippon Ink and Chemicals, Inc.). Table 1 shows the results.

The ink acceptability was evaluated by the number of sheets after the start of printing until the image density did not change. For water retention, first add 15% isopropyl alcohol (IPA) to the humidifier.
%, And the dirt on the non-image area when the IPA was gradually reduced was observed and evaluated in four steps. 4 has no stain,
In No. 3, slightly dirt is confirmed. 2 is partially stained. 1 is stained on the entire surface.

[0053]

[Table 1]

As is evident from the above results, the present invention is superior in ink acceptability and water retention as compared with the comparative example. By including a flocculant in the developing solution and the washing solution, the effect is further enhanced, and by including a proteolytic enzyme in the washing solution, ink receptivity is improved. In particular, in the case where no flocculant is contained, the ink receptivity and water retention are reduced by the running process, but the present invention can maintain high printing performance without being reduced by the running process.

Example 2 A test was conducted in the same manner as in Example 1 except that the coagulant in Example 1 was replaced with a copolymer of polystyrene sulfonic acid and maleic anhydride having an average molecular weight of 3,000, and the same results as in Example 1 were obtained. was gotten. However, the addition amount was increased to 30 g.

Example 3 Using the developing solution A, the washing solution A and the washing solution D described below in Example 1,
The state of the stain of the washing liquid at the time of plate processing was observed.

<Washing solution D> 2-Mercapto-5-nheptyl-oxadiazole 0.5 g Triethanolamine 13 g Polystyrenesulfonic acid (average molecular weight 500,000) 10 g Potassium monophosphate 40 g Water was added to bring the total amount to 1000 cc. adjust. pH is 6.
Adjusted to zero.

As a result, the comparative washing solution A had considerable stains and cloudiness, and had a putrefactive smell of gelatin. However, the washing solution D of the present invention had no stain, cloudiness, and putrefaction smell, and did not accept ink. The properties have also been significantly improved.

[0059]

In the plate making process of an aluminum lithographic printing plate utilizing the silver complex salt diffusion transfer method, an ink having an anionic organic gelatin coagulant is added to a developing solution and / or a washing solution so that the ink acceptability at the start of printing can be improved. And water retention is greatly improved. Further, by including a proteolytic enzyme in the washing liquid, ink receptivity is further improved.
In addition, by including a coagulant in the treatment liquid, the efficiency of collecting the gelatin by filtration of the washing liquid is increased, the decay of the washing liquid during the running processing is prevented, and the ink receptivity and water retention during the running processing are further improved. The drop can be prevented.

Further, by containing a compound having a mercapto group or a thione group in the washing solution, silver ions eluted in the washing solution can be easily collected by filtration. It is possible to reuse the washing liquid which is not necessary, and the ink acceptability is further improved.

Continuation of the front page (56) References JP-A-4-14047 (JP, A) JP-A-7-331350 (JP, A) JP-A-5-19391 (JP, A) JP-A-1-92752 (JP) JP-A-7-77804 (JP, A) JP-A-7-234512 (JP, A) JP-A-1-100552 (JP, A) JP-A-52-35624 (JP, A) 55-45066 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F ⁷ /00-7/42 G03C 8/32

Claims (1)

(57) [Claims] 1. A method for making a lithographic printing plate, wherein a lithographic printing material having a physical development nucleus between an aluminum support and a silver halide emulsion layer is subjected to at least a developing solution and a rinsing solution after exposure. A plate making method for a lithographic printing plate, wherein the developer and / or the washing solution contains an anionic organic gelatin flocculant.