JPH0764293A - Planographic printing plate - Google Patents

Abstract

PURPOSE:To improve inking and plate wear by specifying the ratio of the weight of an anodically oxidized film to the total weight of a hydrophilic binder expressed by weight. CONSTITUTION:This planographic printing plate has physical development nuclei between an aluminum base subjected to surface roughening and anodic oxidation and silver halide emulsion layers. The planographic printing plate is coated with the physical development nuclei without contg. gelatin as a protective colloid and the ratio of the hydrophilic binder on the planographic printing plate to the weight of the anodically oxidized aluminum film expressed by weight is >=2. Namely, the time when silver complex arrives at the anodically oxidized film is delayed by a degrease in the penetration speed of a developer and an increase in diffusion distance of the silver complex. On the other hand, the time when the silver complex arrives at the anodically oxidized film is easily presumed to be relatively fast when the coating amt. of the hydrophilic binder deceases.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lithographic printing plate having 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 For lithographic printing plates using the silver complex salt diffusion transfer method (DTR method), Focal Press, London, New York (1972), Andre Lot 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 is a two-sheet type in which a transfer material and an image receiving material are separately provided, or a monolith 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
It is described in detail in Japanese Patent Laid-Open No. 158844. For mono-sheet type, Japanese Patent Publication No. Sho 48-30562
No. 51-15765, JP-A-51-111103.
No. 52-150105 and the like.

A lithographic printing plate using paper as a support is difficult to perform high-quality printing including printing durability because of plate elongation during printing and water penetration. 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 film, a polypropylene film, a polystyrene film or the like with a polyethylene film can be used as a support.

However, the lithographic printing plate having a film as a support has improved printing elongation, water retention and printing, although it is improved in plate extensibility and water penetration as compared with a paper-based printing plate. There is a problem in terms of ease of printing on the machine.

Therefore, in order to solve various problems of the above-mentioned planographic printing plate using a paper or film as a support, a silver salt type planographic printing plate using a metal, particularly an aluminum plate as a support is known. The details are described in JP-A-57-118244, JP-A-57-158844, JP-A-63-260491, JP-A-3-116151, and JP-A-4-282295.

JP-A-63-260491, JP-A-3-
No. 116151, No. 4-282295, and the like, a roughened and anodized aluminum plate is used as a support, and physical development nuclei are carried thereon, and a photosensitive silver halide emulsion is further provided thereon. Mono sheet type with layers DT
A lithographic printing plate utilizing the R method is detailed. According to it, after the planographic printing plate is imagewise exposed and DTR developed,
The silver halide emulsion layer is washed with warm water and removed to prepare a printing plate. However, these patents are technologies aimed at preventing the corrosion of the aluminum plate caused by the contact between the silver halide emulsion and the aluminum plate, and in terms of ink acceptability and printing durability of the transferred silver image. It was not enough.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a lithographic printing plate having improved ink-carrying properties and improved printing durability.

[0009]

The above object of the present invention is to protect gelatin in a lithographic printing plate having a physical development nucleus between a roughened and anodized aluminum support and a silver halide emulsion layer. It was achieved by a lithographic printing plate characterized in that the physical development nuclei not contained in the lithographic printing plate were covered and the ratio of the amount of anodized aluminum film expressed by weight to the hydrophilic binder on the lithographic printing plate was 2 or more.

In the planographic printing plate targeted by the present invention, the inventors have found that the transferred developed silver that governs ink acceptability and printing durability is the coating amount of the anodic oxide film on the aluminum plate and As a result of diligent study based on the idea that it may be related to the coating amount of the hydrophilic binder including the photosensitive layer, the ratio of the weight of the anodized film to the total amount of the hydrophilic binder expressed by weight. When the ratio is 2 or more, an effective transferred silver can be formed on the anodized aluminum support, but when it is 2 or less, an effective transferred silver image is formed on the anodized aluminum support surface. As a result, it was found that sufficient ink acceptability and printing durability could not be obtained. That is, when the coating amount of the hydrophilic binder becomes large, the time required for the silver complex to reach the anodized film is delayed due to a decrease in the permeation rate of the developing solution and an increase in the diffusion distance of the silver complex. It is easily expected that the time required for the silver complex to reach the anodized film becomes relatively short as the binder coating amount becomes small.
In order to form a strong silver image on the anodized film, the silver complex needs to be effectively incorporated into minute pits generally present on the anodized film, as described in detail later. However, as described above, it is easily expected that the speed at which the silver complex reaches the minute pits on the anodized film is greatly influenced by the coating amount of the hydrophilic binder. In the lithographic printing plate as in the present invention, various photosensitive emulsions are used depending on the use and the required performance quality, and the optimum hydrophilic binder coating amount is present depending on the type of the hydrophilic emulsion. It was found that the transfer rate of the silver complex into the minute pits on the anodic oxide film as described above was changed depending on the coating amount of, and effective transfer silver might not be formed in some cases. The present inventors have set the ratio of the coating amount of the anodic oxide coating on the aluminum support to the coating amount of the hydrophilic binder to 2 or more, so that even if the coating amount of various hydrophilic binders is applied, fine pits on the anodic oxide coating can be obtained. It was found that an effective transfer silver was formed inside. By increasing the coating amount of the anodized film, by some mechanism, the rate of incorporation of the silver complex into the minute pits on the anodized film is improved. It is considered that effective transfer silver may be formed on the anodized film by setting the ratio of the coating amount of the binder to 2 or more.

Prior to the anodic oxidation treatment of the aluminum support of the present invention, the aluminum support generally used for a lithographic printing plate is used for improving the wettability (water retention) with dampening water at the time of printing, and also as a photosensitive layer. In order to improve the adhesion of the, the surface is roughened. This roughening treatment (so-called graining) is performed by mechanically roughening treatment such as ball graining, wire graining, brush graining, or by chemically dissolving aluminum with chloride, fluoride or the like. There are known a chemical roughening treatment, an electrolytic roughening treatment performed by electrochemically dissolving aluminum, and a roughening method using these methods in combination. For example, JP-A-48-28123,
53-123204, 54-146234, 55-25381, 55-132294, 56-.
55291, 56-150593, 56-28.
893, 58-167196, U.S. Pat.
44,510, 3,861,917, 4,
No. 301,229 and so on. Regarding the surface shape of the aluminum plate, U.S. Pat. No. 2,344,510 has a grain structure in which mechanical roughening and electrolytic roughening are combined to form a superposed composite, and U.S. Pat. No. 4,301,229 is a pit. Cumulative frequency distribution of diameter and centerline average roughness, U.S. Pat. No. 3,861,917 is rough surface depth, Canadian patent 955449 is rough mountain peak height and diameter, West German patent 1,813, No. 443 describes the height difference of rough surfaces.

After such a surface-roughening treatment, anodizing treatment is performed in an electrolytic solution such as sulfuric acid, phosphoric acid, nitric acid or a mixture thereof.

As described above, as the surface treatment of the aluminum plate for a printing plate, an extremely large number of roughened aluminum plates having different shapes and structures of a rough surface have been proposed depending on the type of the lithographic printing plate and the printing application. However, in the planographic printing plate targeted by the present invention, it is preferable that there are 500 or more fine pits having a diameter of 0.03 to 0.30 μm per 100 μm 2. That is, in the lithographic printing plate characterized in that the ratio of the amount of the anodized aluminum film described above to the hydrophilic binder on the lithographic printing plate is 2 or more, a large number of minute complexes in which the silver complex is present on the anodic oxide film. It is formed in the pit and has an anchoring effect, and because the transferred silver forms a continuous and dense lipophilic layer and adheres to the aluminum plate, the transferred silver does not drop even during long printing, and is even higher. It is considered to indicate printing durability.

The roughened and anodized aluminum plate used in the present invention is 50,000 using a scanning electron microscope.
It can be easily confirmed by the photograph of the magnification of double. The pits have a diameter of 0.03 to 0.30 .mu.m, 500 per 100 .mu.m @ 2, preferably about 1,
There are more than 000. The upper limit is preferably about 15,000. The average diameter of pits having a diameter of 0.03 to 0.30 μm is 0.05 to 0.20 μ, preferably 0.
It is 05 to 0.15 μm. The diameter of the pit is the dimension when the diameter of the pits other than the circular shape is regarded as the circular shape. The center depth of the pit is 1/3 (0.01 to 0.10 μm) or more, preferably 1/2 (0.015 to 0.15 μm) to 3 (0.
It is preferably about 0.3 to 0.90 μm).

In the above-mentioned JP-A-56-28893, a plateau (primary structure) and a pit (plateau surface) are formed on the aluminum surface by using mechanical surface roughening, chemical etching and electrolytic surface roughening in combination. Secondary structure that can be
The grain of the composite structure consisting of is described. The fine pits of the present invention preferably have a composite structure existing on large pits (plateaus) having an average diameter of 3 to 15 μm. The projected area of the small pits is preferably about 5 to 40%, and the projected area of the large pits (plateau) is 50%.
About 95% is preferable. The center line average roughness (Ra) is preferably in the range of 0.3 to 1.0 μm. The aluminum plate having such a surface shape of the present invention is mechanically roughened,
Chemical roughening treatment, electrolytic roughening treatment conditions, anodic oxidation conditions, determined by a combination of many conditions such as the alloy composition of the aluminum plate, for example, the type of acid, the concentration of acid,
It can be comparatively easily found by a method in which the electrolytic temperature, the current density, the applied voltage, etc. are adjusted, electrolytic surface roughening treatment is performed, and then anodic oxidation treatment is performed. 50 small pits
If the number is less than 0 or there is no above-mentioned minute pit and only large pits (plateau), the average diameter is 0.3.
Even when the number of 0 μ pits is 500 or more per 100 μm 2, the ink acceptability and printing durability are inferior to those of the lithographic printing plate of the present invention.

After the roughening treatment, it is necessary to perform the anodic oxidation treatment. For the anodizing treatment, a conventionally well-known method can be used. Sulfuric acid, phosphoric acid, nitric acid or a mixed solution thereof is a useful electrolytic solution.
Further, the mixed solution of sulfuric acid and phosphoric acid disclosed in JP-A-55-28400 is also useful.

In the sulfuric acid method, the treatment is usually carried out with a direct current, but it is also possible to use an alternating current. The concentration of sulfuric acid is 5
Used in 30%, 5 ~ 25 in the temperature range of 20 ~ 60 ° C
Electrolytic treatment is carried out for 0 seconds, and an oxide film of 1 to 10 g / m 2 is provided on the surface. Further, the current density at this time is 1 to 2
0 A / dm @ 2 is preferred. 5 to 5 in the case of the phosphoric acid method
Treatment is carried out at a concentration of 0% at a temperature of 30 to 60 ° C. for 10 to 300 seconds and a current density of 1 to 15 A / dm 2. The amount of anodized aluminum thus anodized can be measured by the chemical stripping method described in JIS H8680.

The amount of anodized aluminum required for the lithographic printing plate of the present invention is 1.0 g / m 2 to 10.0 g / m 2.
It is preferably 1.5 g / m2 to 5 g / m2.

Desmutting treatment is preferably performed prior to the anodizing treatment. That is, the roughened aluminum substrate is treated with 10-50% hot sulfuric acid (40-60%).
C.) or dilute alkali (sodium hydroxide, etc.) to remove the smut adhering to the surface.

Further, after the anodizing treatment, a post-treatment can be performed if necessary. For example, the method of immersion treatment in an aqueous solution of polyvinylphosphonic acid disclosed in British Patent No. 1,230,447 is used. Also,
An undercoat layer of a hydrophilic polymer may be provided if necessary, but it is selected depending on the properties of the photosensitive layer provided thereon.

As the physical development nuclei of the physical development nuclei layer used in the present invention, a metal colloid such as gold or silver or a metal sulfide obtained by mixing a water-soluble salt such as silver, palladium or zinc with a sulfide can be used. The physical development nuclei used in the present invention must not contain gelatin as a protective colloid. The present inventors have found that when gelatin is used as a protective colloid for physical development nuclei, gelatin which is a protective colloid for physical development nuclei influences the formation of transferred silver by some action, so that the aluminum plate of the present invention is used as a support. Even when a lithographic printing plate having a ratio of the amount of anodized aluminum film expressed by weight to the hydrophilic binder on the lithographic printing plate of 2 or more is used, sufficient ink acceptability and printing durability can be obtained. I found nothing.

The physical development nuclei containing no gelatin as a protective colloid used in the present invention means a case where a hydrosol having no protective colloid of physical development nuclei is used or a hydrophilic polymer compound other than gelatin is used as a protective colloid. When used. Here, particularly preferable hydrophilic polymer compounds include polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, polyvinyl acetate, sulfonated polystyrene, hydroxyethyl cellulose, carboxymethyl cellulose 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, as well as hydrophilic polymer compounds such as polyvinylpyrrolidone, various starches, albumin, polyvinyl alcohol, gum arabic, and hydroxyethyl cellulose. Can be included. Examples of the hydrophilic colloid used include gelatin, gelatin derivatives, polyvinyl alcohol, polyvinylpyrrolidone and the like, but preferably a substantially hardener to facilitate the peelability of the hydrophilic colloid layer after physical development. It is desirable to use a hydrophilic colloid layer that does not contain.

The types of photosensitive silver halide emulsions used in the present invention include commonly used silver chloride, silver bromide,
It is selected from silver iodide, silver chlorobromide, silver chloroiodobromide, silver iodobromide and the like. The emulsion type may be either negative type or positive type. These silver halide emulsions can be chemically or spectrally sensitized if necessary.

The amount of the hydrophilic binder on the lithographic printing plate of the present invention is the total amount of all the binders contained in the hydrophilic colloid layers such as the photosensitive silver halide emulsion layer and the physical development nucleus layer. An intermediate layer may be provided between the photosensitive silver halide emulsion layer and the physical development nucleus layer, or an upper layer may be provided on the photosensitive silver halide layer. It is meant the total amount of all hydrophilic binders coated above.

The ratio of the weight of the anodic oxide coating to the total amount of the binder expressed by weight must be 2 or more. By setting the above ratio to 2 or more, effective transfer silver can be formed in the above-mentioned minute pits.
It was found that when it is 2 or less, an effective transferred silver image is not formed in the pits, and as a result, sufficient ink-carrying acceptability and printing durability cannot be obtained. That is, when the coating amount of the hydrophilic binder is increased, the time for the silver complex to reach the pits is delayed due to a decrease in the permeation rate of the developer and an increase in the diffusion distance of the silver complex. It is readily expected that the lower the coverage of binder, the faster the silver complex will reach the pits. In order to form a continuous and dense silver image in the fine pits, the silver complex needs to be effectively incorporated into the fine pits. However, as described above, the speed at which the silver complex reaches the pits depends on the hydrophilic binder. It is easily expected that the coating amount is greatly affected. In the lithographic printing plate like the present invention, various photosensitive emulsions are used depending on the use and the required performance quality, and the optimum hydrophilic binder coating amount exists depending on the type, but It was found that the transfer rate of the silver complex to the fine pits varies depending on the coating amount, and effective transfer silver may not be formed in some cases. The present inventors have made it possible to increase the coating amount of various hydrophilic binders by setting the ratio of the coating amount of the anodized film of the aluminum support using the fine pits to the coating amount of the hydrophilic binder to 2 or more. In order to improve the uptake rate of the silver complex into the pit by some mechanism, it is effective in the pit by increasing the coating amount of the anodic oxide coating to the coating amount of the hydrophilic binder to 2 or more as described above. I think that transfer silver may be formed.

The developers used in the present invention include developing agents such as polyhydroxybenzenes, 3-pyrazolidinones, alkaline substances such as potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium triphosphate, or amines. Addition of compounds, preservatives such as sodium sulfite, viscous agents such as carboxymethylsesulose, antifoggants such as potassium bromide, 1-phenyl-5-mercaptotetrazole, development modifiers such as polyoxyalkylene compounds. Agents etc. can be included.

The pH of the developer is usually about 10 to 14, preferably about 12 to 14, but the conditions for pretreatment (for example, anodizing) of the aluminum support of the lithographic printing plate to be used,
Depends on the photographic element, the desired image, the type and amount of various compounds in the developer, the developing conditions, and the like.

Wash-off for removing the gelatin layer can be carried out by washing with running water at a temperature of about 20 to 30 ° C.

[0030]

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

Example 1 An aluminum plate having a thickness of 0.30 mm having the surface shape and the coating amount of the anodized film shown in Table 1 below was obtained by the difference in the conditions of the electrolytic surface roughening treatment and the anodization.

[0032]

[Table 1]

In Table 1, the number of pits is about 5 μm in average diameter.
The number of pits having a diameter of 0.03 to 0.30 .mu.m per 100 .mu.m.sup.2 existing on the plateau of FIG. The average roughness (Ra) of these aluminum plates was 0.5 to 0.6 μm. The anodized aluminum film amount Y represents the weight per 1 m 2 obtained by the chemical stripping method described in JIS H8680.

Silver sol prepared by the Carey Lea method was coated on these aluminum supports as a physical developing solution. The coating amount of the binder contained in the physical development nucleus layer was 0.01 g / m2. After drying, the silver halide emulsion layer was applied and dried to prepare a photosensitive lithographic printing plate.
The amount of binder contained in the silver halide emulsion layer is 0.7-
It changed to 2.0 g / m2.

The lithographic printing plate thus obtained was imagewise exposed, and then developed with the diffusion transfer developing solution described in Example 1 of JP-A-4-28295, and immediately after that, it was gelatinized with running water. The layers were washed off (wash off).
Before the plate surface is dry, apply the plate surface protection liquid with absorbent cotton etc. and dry. The lithographic printing plate thus prepared was placed on a printing machine AB Dick 350CD (trademark of an offset printing machine manufactured by AB Dick Co.) to evaluate ink acceptability and printing durability.

The ink acceptability was evaluated by the number of prints until a print with good image density was obtained by simultaneously starting paper feed while the ink roller was in contact with the plate surface. The printing durability was evaluated by the number of printed sheets when printing became impossible due to defective ink transfer in the image area or line skipping. The results are shown in Table 2. Here, Y represents the coating amount of the hydrophilic binder per 1 m 2, and X / Y represents the ratio of the coating amount X of the anodized aluminum to Y.

[0037]

[Table 2]

Example 2 Using the aluminum plate (E) of Example 1, to the silver sol prepared by the CareyLa method of Example 1,
Using various water-soluble polymers shown in Table 3 and gelatin as a comparison as a protective colloid, a physical development nucleus solution adjusted so that the weight ratio of silver to protective colloid was 10 was applied. Further, according to the method of Example 1, a photosensitive emulsion layer was coated so that the ratio of the amount of anodized aluminum film expressed by weight to the hydrophilic binder on the lithographic printing plate was 2.4, to prepare a photosensitive lithographic printing plate. , Exposure, development, and evaluation of ink transfer and printing durability. The results are shown in Table 3.

[0039]

[Table 3]

[0040]

EFFECTS OF THE INVENTION It is possible to obtain a lithographic printing plate that has good ink coverage and extremely high printing durability.

Claims (4)

[Claims] 1. A lithographic printing plate having physical development nuclei between a roughened and anodized aluminum support and a silver halide emulsion layer is coated with physical development nuclei which do not contain gelatin as a protective colloid, and A lithographic printing plate characterized in that the ratio of the amount of anodized aluminum film expressed by weight to the hydrophilic binder on the lithographic printing plate is 2 or more. 2. The planographic printing plate according to claim 1, wherein an aluminum plate having 500 or more pits having a diameter of 0.03 to 0.30 μm per 100 μm 2 is used as a support. 3. The average diameter of the pits is 0.05 to 0.20.
The lithographic printing plate according to claim 2, which has a thickness of μm. 4. The planographic printing plate according to claim 3, wherein the depth of the pit is 1/3 or more of the diameter.