JP2001281870A - Planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planographic printing plate having satisfactory printing durability and stain resistance. SOLUTION: The planographic printing plate has at least one silver halide emulsion layer on a surface-roughened and anodically oxidized aluminum substrate and contains a compound having a pKa of 10-12.5 or an amphoteric metal salt between the silver halide emulsion layer and the aluminum substrate.

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 using an aluminum plate as a support, and more particularly to a lithographic printing plate using a silver complex salt diffusion transfer method.

[0002]

2. Description of the Related Art A planographic printing plate using a silver complex salt diffusion transfer method (DTR method) is disclosed in "Focal Press, London New York (1972)," by Andrelot and Edith Weide, "Photographic Silver Halide. 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. For a two-sheet type lithographic printing plate, see JP-A-57-158.
It is described in detail in Japanese Patent Publication No. 844. The mono-sheet type is described in detail in JP-B-48-30562, JP-B-51-15765, JP-A-51-111103, and JP-A-52-150105.

[0004] A lithographic printing plate using paper as a support is difficult to print with high quality including printing durability due to plate elongation during printing and penetration of moisture. A film support is used for the purpose of improving these problems and improving printing performance. For example, a cellulose acetate film, a polyvinyl acetal film, a polystyrene film, a polypropylene film, a polyethylene terephthalate film, or a composite film obtained by coating a polyester, polypropylene, or polystyrene film with a polyethylene film can be used as the support.

[0005] However, lithographic printing plates using a film as a support are improved in terms of plate elongation and moisture penetration, as compared with paper-based printing plates, but they have improved printing durability, water retention and printing. The problem remains in terms of the ability to hang the plate on the machine.

In order to solve the above-mentioned various problems of the lithographic printing plate using a paper or a film as a support, a lithographic printing plate of a silver salt type using a metal, particularly an aluminum plate as a support has been known. JP-A-57-118244, JP-A-57-158844
And JP-A-62-260491, JP-A-3-116151, and JP-A-4-82295.

In each of these publications, it is described that a strong alkali is used as a developing solution. However, aluminum is an amphoteric metal and is very easily dissolved in alkali, so that the developing time is long or the developing temperature is high. DT if
There was a problem that the silver image precipitated by R was dissolved together with the base, that is, the development stability was lacking.
Also, Japanese Patent Application Laid-Open No. 7-199471 describes that a silicate having low aluminum solubility is used, but in this case, the adhesion between the image silver and the base is extremely poor, and sufficient printing durability can be obtained. could not.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate having good development stability.

[0009]

SUMMARY OF THE INVENTION At least one silver halide emulsion layer is provided on a roughened and anodized aluminum support with a pKa between the silver halide emulsion layer and the aluminum support. Was achieved by using a lithographic printing plate characterized in that it contained a compound of from 10 to 12.5 or a salt of an amphoteric metal.

[0010]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, any compound having a pKa of 10 to 12.5 or a salt of an amphoteric metal can be contained in any layer between the silver halide emulsion layer and the aluminum support. However, a physical development nucleus layer is most preferred.

In the present invention, a compound having a pKa of 10 to 12.5 can be used as an organic compound or an inorganic compound, but a compound having an adverse effect on photographic properties is not preferred. Inorganic compounds include sodium carbonate and phosphoric acid. Organic compounds include m-cresol, resorcinol, sulfosalicylic acid, and the like. These are preferably 0.1 mmol / m ²
As described above, it is more preferable to apply 0.5 to 5 mmol / m ² . Further, the pH of the coating solution for applying these is preferably adjusted to 4.0 to 8.0 which has little influence on the aluminum support.

In the present invention, the amphoteric metal refers to an oxide whose oxide acts as a base for an acid and acts as an acid for a base. For example, zinc, cadmium, boron, aluminum, gallium, indium, There are silicon, germanium, tin, lead, arsenic, antimony, bismuth and the like. In order to apply these amphoteric metals, they are used in the form of sulfate, nitrate, phosphate, chloride, bromide, etc. after being made water-soluble. These are 0.1 mmol / m ² or more, preferably 0.5 to
5 mmol / m ^2, more preferably be applied 1~5mmol / m ^2. Further, the pH of the coating liquid for applying these is preferably adjusted to a weak acidity and 4.0 to 6.0 so as not to cause precipitation.

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 (1
972) Published by Andre Lott and Edith Weide,
See "Photographic Silver Halide Diffusion Processes".

The aluminum support used in the present invention has an aluminum purity of 93% by weight or more, preferably 99% by weight or more. As the aluminum impurities, elements commonly used as aluminum alloys such as iron, silicon, copper, manganese, magnesium, chromium, zinc, titanium, bismuth, lead, zirconium, and nickel can be used. Particularly preferred aluminum alloys include 1050, 1100, and 3003.

The aluminum support used in the present invention is rolled by a known method. That is, a slab is cast by dissolving and holding an aluminum ingot, and a surface cutting step of cutting an impurity structure portion of the slab surface by a facer at a rate of 3 to 10 mm is performed.
0 ° C., performing a soaking process of holding for 6 to 12 hours, and then hot rolling to a thickness of 5 to 40 mm,
Cold rolling is performed at room temperature to a predetermined thickness. In addition, after annealing and homogenizing the rolled structure etc. afterwards for the uniformity of the structure,
Cold rolling is performed to a specified thickness, and straightening is performed to obtain a plate with good flatness. The thickness of the support usually ranges from about 0.13 to 0.50 mm.

The support used in the present invention is subjected to a degreasing treatment, a roughening treatment, an anodizing treatment, etc., which are generally used in this technical field. At least the roughening treatment and the anodizing treatment are performed. A support made in this order is used.

The aluminum plate used in the present invention is subjected to a degreasing treatment to remove fatty substances from the surface. Examples of the degreasing treatment include solvent degreasing such as trichlene and thinner, emulsion degreasing mixed with a surfactant, kerosene, triethanolamine, and sodium hydroxide, acid degreasing, and alkali degreasing.

The aluminum plate used in the present invention is subjected to a surface roughening treatment in order to improve the adhesion to the photosensitive layer and to improve the water retention. There are mechanical treatment, chemical treatment, and electrochemical treatment as a method of surface roughening treatment. These treatments are performed alone or in combination, but in particular, in order to control the color tone of the base, chemical treatment, electrochemical treatment, Processing is essential. The shape of the surface is generally represented by a roughness meter, and the size of the surface is center line average roughness;
1.0 μm is appropriate.

As the mechanical surface roughening treatment, a ball grain method, a nylon brush method, a buff polishing method, a blast polishing method, or the like can be used. Chloride,
There is a method of chemically dissolving aluminum with fluoride or the like.

Since the electrochemical graining treatment method can finely control the grain shape and surface roughness depending on the composition of the electrolytic solution and the electrolytic conditions as compared with other methods, it is preferable to use this method. preferable. The electrochemical graining treatment can be performed by direct current, alternating current, or a combination of both. As the AC wave, a single-phase or three-phase commercial AC or a sine wave in the range of 10 to 300 Hz including these, a square wave,
There are typhoons and the like.

The electric power supplied to the aluminum plate varies depending on the composition of the electrolytic solution, the temperature, the distance between the electrodes, and the like.
It is used in the range of 50-4000C in A / dm ² and electric quantity. The distance between the electrode and the aluminum plate is preferably in the range of 1 to 10 cm.

As the electrolytic solution, an aqueous solution of nitric acid or a salt thereof, hydrochloric acid or a salt thereof, or one or a mixture of two or more thereof can be used. If necessary, sulfuric acid,
Phosphoric acid, chromic acid, boric acid, organic acids, or salts thereof, ammonium salts, amines, surfactants, other corrosion inhibitors, corrosion accelerators, and stabilizers can also be used.

As the concentration of the electrolyte, the concentration of the above-mentioned acids is as follows.
It is preferably 0.1 to 10%, and the concentration of aluminum ions in the electrolyte is maintained in the range of 0 to 10 g / L. The temperature of the electrolyte is preferably from 0 to 60 ° C.

In the present invention, desmut refers to a chemical etching step performed between surface roughening and anodic oxidation. Desmutting can be performed using an acid or alkali, but acid treatment is preferred. As the acid, nitric acid, phosphoric acid, chromic acid, sulfuric acid, hydrochloric acid, hydrofluoric acid and the like can be used alone or as a mixture of several kinds. For the alkali desmut, sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, potassium tertiary phosphate, sodium aluminate, sodium silicate, or the like can be used alone or in combination. Further, the concentration of the desmut solution and the processing time must be such that the smut can be completely removed. Since the amount of smut generation depends on the roughening treatment method at the preceding stage, the required degree of desmutting depends on the roughening method. However, since the degree of smut removal can be easily observed with a scanning microscope, the degree of desmut from which smut is completely removed can be easily determined by observing the surface of the aluminum treated with the scanning microscope.
Actually, there is also a relationship with the treatment of the waste liquid. The total amount of the acid or alkali is about 5 to 40%, and the treatment time is preferably 30 seconds to 2 minutes. The processing temperature is preferably from 40 to 60 ° C.

In the present invention, the desmutting step can be divided into two or more times. In this case, it is possible to combine acid desmut and alkali desmut, but it is preferable to use alkali desmut first.

After performing such a roughening treatment and a desmutting treatment, an anodic oxidation treatment is performed. Sulfuric acid, phosphoric acid, oxalic acid, chromic acid or an organic acid (eg, sulfamic acid, benzenesulfonic acid, etc.) or a mixture thereof is preferable for the anodizing electrolyte, and an acid having low solubility of the formed oxide film is particularly preferable. .

Since the anodic oxide film is formed only on the anode, a direct current is usually used as the current. The conditions of anodic oxidation are as follows: liquid concentration 1 to 40%, current density 0.1 to 10 A / dm ² , voltage 10 to 100
Used in the V range. The thickness of the anodic oxide film is changed depending on the current density and time, and is appropriately adjusted depending on the printing durability of the printing plate, but 3 g / m ² or less, preferably 2.8 to 1 g /
m ² , more preferably 2.3 to 1 g / m ² . The temperature affects the hardness of the anodic oxide film, and the hardness increases at a low temperature, but the processing is usually performed at a temperature near normal temperature because of poor flexibility. The amount of anodic oxide film created is JIS
It can be measured based on H86807 “Coating Mass Method”.

After the anodic oxidation treatment, a post-treatment can be performed if necessary. As the post-treatment, methods known to those skilled in the art, for example, post-treatment with inorganic salts such as silicate treatment, fluorozirconic acid treatment, organic polymer treatment such as gum arabic, polyvinyl phosphonic acid, polyvinyl sulfonic acid, hydration There is a sealing treatment and the like.

Various hydrophilic colloids can be used as protective colloids in the photosensitive silver halide emulsion layer of the printing plate of the present invention. That is, various gelatins such as acid-treated gelatin, alkali-treated gelatin, gelatin derivatives, and grafted gelatin can be used, and hydrophilic polymer compounds such as polyvinylpyrrolidone, various starches, albumin, polyvinyl alcohol, gum arabic, and hydroxyethyl cellulose. Can be contained. Examples of the hydrophilic colloid used include gelatin, a gelatin derivative, polyvinyl alcohol, and polyvinylpyrrolidone. Preferably, a substantially hardener is used to facilitate release of the hydrophilic colloid layer after physical development. It is desirable to use a hydrophilic colloid layer containing no.

The types of photosensitive silver halide emulsions used in the present invention include commonly used silver chloride, silver bromide, and silver halide.
It is selected from silver iodide, silver chlorobromide, silver chloroiodobromide, silver iodobromide and the like. 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.

In the present invention, the silver halide emulsion layer may contain benzotriazole or a derivative thereof, or a nitrogen-containing heterocyclic compound having a mercapto group or a thione group. The amount is 1 to 100 mg / m ² , preferably 5
3030 mg / m ² .

Examples of the benzotriazole derivative include 5-methylbenzotriazole, 5-chlorobenzotriazole and the like. Examples of the heterocycle of the nitrogen-containing heterocyclic compound having a mercapto group or a thione group include imidazole, imidazoline, thiazole, thiazoline, oxazole, oxazoline, pyrazolidone, trizole, thiadiazole, oxadiazole, tetrazole, pyridine, pyrimidine, pyridazine, pyrazine, There are triazine and the like, and among them, imidazole, triazole and tetrazole are preferable.

Specific examples of the nitrogen-containing heterocyclic compound having a mercapto group or a thione group are shown below. 2-mercapto-4-fenlimidazole, 2-mercapto-1
-Benzylimidazole, 2 mercapto-1-butyl-
Benzimidazole, 1 ethyl-2-mercapto-benzimidazole, 2 mercapto-benzimidazole,
1,3 diethyl-benzimidazoline-2-thione,
1,3 dibenzyl-imidazolidin-2-thione, 2,
2-dimercapto-1,1′-decamethylene-diimidazoline-2-thione, 2-mercapto-4-phenylthiazole, 2-mercapto-benzothiazole, 2-mercaptonaphthothiazole, 3-ethyl-benzothiazoline-2-thione, 3-dodecyl-benzothiazoline-2
-Thione, 2-mercapto-4,5-diphenyloxazole, 2-mercaptobenzoxazole, 3-pentyl-benzoxazoline-2-thione, 1-phenyl-3-methylpyrazolidone-5-thione, 3-mercapto- 4-allyl-5-pentadecyl-1,2,4-triazole, 3-mercapto-5-nonyl-1,2,4-
Triazole, 3-mercapto-5-nonyl-5-1,
2,4-triazole, 3-mercapto-4-allyl-
5-pentadecyl-1,2,4-triazole, 3-mercapto-4-amino-5-heptadecyl-1,2,4
-Triazole, 2-mercapto-5-phenyl-5-
Pentadecyl-1,3,4-thiadiazole, 2-mercapto-5-n-heptyl-oxathiazole, 2-mercapto-5-phenyl-1,3,4-oxadiazole, 5-mercapto-1-phenyl-tetrazole, 2
-Mercapto-5-nitropyridine, 1-methyl-quinoline-2 (1H) -thione, 3-mercapto-4-methyl-6-phenylpyridazine, 2-mercapto-5,6
-Diphenyl-pyrazin, 2-mercapto-4,6-
Diphenyl 1,3,5 triazine, 2-amino-4-mercapto-6-benzyl-1,3,5-triazine,
1,5-dimercapto-3,7-diphenyl-S-triazolino [1,2-a] -S-triazoline and the like.

In the present invention, a developing agent such as polyhydroxybenzenes, 3-pyrazolidinones, preservatives,
E.g. sodium sulfite, thickeners such as carboxymethylcellulose, antifoggants such as potassium bromide,
1-phenyl-5-mercaptotetrazole, development modifier,
For example, additives such as a polyoxyalkylene compound can be included. In addition to the silicate, an alkaline substance such as potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium tertiary phosphate, or an amine compound can be contained.

The pH of the developer in the present invention is usually about 10 to 1
4, preferably about 12-14, but pretreatment (e.g. anodizing) conditions of the aluminum support of the lithographic printing plate to be used,
It depends on the photographic element, the desired image, the type and amount of various compounds in the developer, the development conditions, and the like.

In the present invention, a washing-off process for removing the gelatin layer immediately after the development is performed. Wash off is performed at a temperature of about 20 to 40 ° C. The wash-off solution may contain an enzyme or a compound having a mercapto group or a thione group as described in JP-A-10-133381. Further, the wash-off process can be divided into multiple stages.

In silver salt printing plates, gumming is usually performed to protect the plate surface. The gum solution is arabic gum, dextrin, sodium alginate, hydroxyethyl starch,
It is preferable to have a protective colloid such as carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polystyrenesulfonic acid, and polyvinyl alcohol.

[0038]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition,% shows weight% unless there is a notice.

Example 1 A 1050 aluminum plate was degreased with a 4% aqueous solution of sodium hydroxide at 50 ° C. for 1 minute, washed with water, polished with a 400 mesh pumicestone suspension with a rotating nylon brush, and polished to a thickness of 2.5%. AC density 50A / dm at 20 ℃ in 20% hydrochloric acid aqueous solution
² was subjected to electrolytic surface roughening treatment for 60 seconds, followed by desmut treatment with 20% phosphoric acid at 50 ° C. for 1 minute. Then in a 25% sulfuric acid solution at a temperature of 20 ℃
Anodizing was performed at an electric density of 3 A / dm ² and a processing time of 45 seconds.

A palladium sulfide nucleus was prepared as a physical development nucleus solution, and pK was adjusted to the coating amount (addition amount) shown in Table 1.
Compound A in which a was 10-12.5 was included. P of this nuclear fluid
H was set to 4.5. This nucleus solution was applied on the prepared aluminum support so that the application amount was 3 mg / m ² as palladium sulfide. In addition, a silver chloride emulsion containing 0.5% iodine (average particle size 0.3%)
μm) was sensitized with gold-sulfur and further dye-sensitized to red to form a silver chloroiodide emulsion. Next, this emulsion was coated with silver nitrate at 2.0 g / m ² and dried on the prepared plate to prepare a photosensitive lithographic printing plate.

The lithographic printing plate obtained in this manner has an image setter SDP-α24 whose light source is a red semiconductor laser.
Image exposure and full screen exposure were performed at 2400 dpi and 175 lpi with 00 (manufactured by Mitsubishi Paper Mills). Next, development plate-making processing was performed using a plate-making processor (P-α880 manufactured by Mitsubishi Paper Mills). The plate making processor includes a developing process (22 ° C.), a rinsing process (washing off the emulsion layer with a scrub roller while spraying rinsing water at 35 ° C.), a finishing process (21 ° C., shower), and a drying process. It is composed of The washing process is a closed type that circulates 20L of washing water stored in the storage tank with a pump, sprays it onto a lithographic printing plate, then filters it with a filter, collects it in the storage tank, and reuses it. . The processing speed was represented by the time during which the plate was immersed in the developer, and the plate was made at different processing speeds.

The structures of the developing solution, washing solution and finishing solution used are as follows. <Developer> 20 g of sodium hydroxide 20 g of hydroquinone 1 g of 1-phenyl-3-pyrazolidinone 2 g of anhydrous sodium sulfite 80 g 6 g of N-methylethanolamine 5 g of sodium sodium ethylenediaminetetraacetate 5 g of deionized water. pH (25 ° C) = 13.4

<Washing solution> 2-mercapto-5-n-heptyl-oxanediol 0.5 g triethanolamine 13 g sodium bisulfite 10 g potassium dihydrogen phosphate 40 g proteinase 1 g Water is added to adjust the total amount to 1000 cc. . pH 6.0
Was adjusted. Bioprolase as a proteolytic enzyme
AL-15 (bacterial proteinase, manufactured by Nagase & Co., Ltd.) was used.

<Finishing solution> Gum arabic 10 g Phosphoric acid 0.5 g Sodium nitrate 20 g Polyethylene glycol # 400 100 g 2-Mercapto-5-n-heptyloxane diol 0.5 g Make up to 1000 mL with deionized water. The pH was adjusted to 6.5 with sodium hydroxide.

The lithographic printing plate thus prepared was printed by a printing machine Sprint 226 (Komori Corporation).

Table 1 shows the printing results. The development latitude was changed to a plate made by changing the development time, and as a result of printing 10,000 sheets,
This indicates the development time (seconds) in which halftone dots and fine lines could not be applied. The wider the latitude, the better the printing plate stability.

[0047]

[Table 1] ─────────────────────────────────── No. Compound A pKa Dissociation stage Addition amount Development latitude ゛Remarks (mmol / m ² ) ─────────────────────────────────── 1 None 9-10 seconds Comparison 2 Sulfosalicylic acid 12.0 2 0.1 9 to 12 seconds The present invention 3 Sulfosalicylic acid 12.0 2 0.5 9 to 13 seconds The present invention 4 Sulfosalicylic acid 12.0 22.0 9 to 13 seconds The present invention 5 Resorucinol 11.3 22.0 9 to 13 seconds The present invention 6 Malonic acid 5.3 2 2.0 9-10 seconds comparison 7 o-nitrophenol 7.2 2.0 9-10 seconds comparison 8 p-phenolsulfonic acid 9.1 2 2.0 9-10 seconds comparison 9 phosphoric acid 12.4 22.0 9-12 seconds invention 10 sodium carbonate 10.3 2 2.0 9 to 12 seconds The present invention ───────────────────────────────────

From Table 1, it can be seen that the development latitude is expanded by including a compound having a pKa of 10 to 12.5 in the physical development nucleus layer.

Example 2 Example 1 was repeated except that a salt of an amphoteric metal was added to the physical development nucleus layer of Example 1 in place of the compound having a pKa of 10 to 12.5 as shown in Table 2.
As a result, the results shown in Table 2 were obtained.

[0050]

[Table 2] ────────────────────────────────── Addition amount of No. compound Developing latitude ゛ Remarks (mmol / m ² ) １ 1 None 9-10 seconds Comparison 11 Aluminum sulfate 0.1 9-12 Second invention 12 Same as above 0.5 9 to 12 seconds Invention 13 Same as above 2.0 9 to 13 seconds Invention 14 Zinc sulfate 0.59 to 12 seconds Invention 15 Zinc sulfate 2.0 9 to 13 seconds Invention 16 Tin (II) chloride 0.59 to 12 seconds invention 17 tin (IV) chloride 0.5 9-12 seconds invention ───────────────────────────────── ─

From Table 2, it can be seen that the development latitude is widened by containing a salt of an amphoteric metal in the physical development nucleus layer.

[0052]

The invention has at least one silver halide emulsion layer on a roughened and anodized aluminum support, and has a pKa between 10 and 12.5 between the silver halide emulsion layer and the aluminum support. Or a salt of an amphoteric metal, a lithographic printing plate having a wide development latitude can be obtained.

Claims (3)

[Claims] 1. A method according to claim 1, wherein the silver halide emulsion layer has at least one silver halide emulsion layer on a roughened and anodized aluminum support, and has a pKa of 10 to 12.5 between the silver halide emulsion layer and the aluminum support. A lithographic printing plate comprising the compound of formula (I). 2. The method according to claim 1, further comprising at least one silver halide emulsion layer on the roughened and anodized aluminum support, wherein an amphoteric metal salt is interposed between the silver halide emulsion layer and the aluminum support. A lithographic printing plate characterized by containing. 3. A physical development nucleus layer between the silver halide emulsion layer and the aluminum support, wherein the physical development nucleus layer contains a compound having a pKa of 10 to 12.5 or a salt of an amphoteric metal. 2. The lithographic printing plate according to 2.