JP2000047376A - Photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lithographic printing plate which causes little contamination such as initial contamination, contamination of a blanket and contamination when the operation is stopped. SOLUTION: This photosensitive lithographic printing plate is produced by forming a photosensitive layer on a metal supporting body which is produced in at least processes of roughening and anodic oxidation. The gloss of the metal supporting body when the photosensitive layer is removed with acetone to expose the surface to air satisfies formula I and formula II. I: A85/A60=8 to 12 II: B85/B60=8 to 12 In the formulae, A and B are the glossiness of the metal supporting body when light enters in the parallel and perpendicular directions to the rolling direction of the metal supporting body, respectively, and suffixes 85, 60 represent the incident angles of the respective light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive lithographic printing plate, and more particularly to a photosensitive lithographic printing plate which causes less stain on printed matter.

[0002]

2. Description of the Related Art A photosensitive lithographic printing plate in which a photosensitive composition is applied in a thin layer on a metal plate such as an aluminum plate, that is, a so-called PS plate, is widely used for printing. The photosensitive lithographic printing plate is made into a printing plate through image exposure-development. As a printing method, an offset printing method is usually used.Ink is attached to an image of a printing plate, the ink is transferred onto a rubber blanket wound around rollers, and the ink on the blanket is further applied to paper. Printing is performed by the transfer. At this time, a fountain solution is supplied to a non-image portion of the printing plate, that is, a portion from which the photosensitive layer has been removed by image exposure and development so that ink does not adhere. In addition, in the process of producing a photosensitive lithographic printing plate, before applying the photosensitive composition, usually a metal plate is subjected to a hydrophilic treatment, so that the non-image area is moistened with water so that the ink does not easily adhere. I have.

This printing plate is excellent in the strength of the support, easy to maintain the hydrophilicity of the non-image area, and can obtain high printability. However, there is a problem that various stains are easily generated in printed matter during printing. is there. As such stains, background stains caused by blanket non-image portions (blanket stains) generated when printing hundreds of sheets and initial stains due to insufficient water retention of the non-image portions of the printing plate are conspicuous. Depending on the number of thousands of printed sheets, severe stains (ground stains) may occur in the non-image area. Further, if the operation of the printing press is stopped while the printing plate is mounted on the printing press, and then the operation is restarted, spot-like stains (stop stains) of about 0.1 to 2 mm may occur in the non-image portion. .

[0004]

Therefore, various measures have been proposed for dealing with various types of stains on the printing plate. For example, JP-A-5-24376 discloses that the linear gradient of the "pit diameter" and the "maximum depth in the direction perpendicular to the diameter" of the aluminum support subjected to electrolytic surface roughening is 0.1 linear regression analysis. It is described in detail that a rough surface shape having a pit shape of 100 or more is particularly effective in improving the stainability of a halftone portion of an image portion. Japanese Patent Application Laid-Open No. 8-67078 discloses an average diameter of 0.5.
Honeycomb pits of 10,000 to 100 μm
It is described that, by forming at a density of 000 pieces / mm ^2, a printing plate support is obtained in which ink is hardly entangled and blanket stain is hardly generated. JP-A-8-
Japanese Patent Application Publication No. 300843 and Japanese Patent Application Laid-Open No. 9-290578 describe proposals on a method for improving shadow portions and blanket contamination. Also, Japanese Patent Application Laid-Open No. 10-20506
Japanese Patent Application Laid-Open No. H11-157,199 discloses a photosensitive lithographic printing plate using an aluminum support that has been roughened and anodized, treated with an aqueous solution of polyvinylphosphonic acid, and further treated with an aqueous solution of an alkali metal silicate, using a cleaner during printing. It describes that the stain resistance of the non-image portion does not deteriorate and the printing durability is good.

However, these methods are still insufficient for improving blanket dirt and stop dirt. In particular, in recent years, direct plate making systems combining an Ar laser, a YAG laser, a semiconductor laser, and a computer or a digital communication system have been put to practical use. Even so, the demands are becoming more and more severe, and the above-mentioned method cannot sufficiently cope. Therefore, the present invention provides a method for preventing printing stains,
In particular, it is an object of the present invention to provide a photosensitive lithographic printing plate with improved blanket stain and stop stain.

[0006]

According to the present invention, there is provided a photosensitive lithographic printing plate having a photosensitive layer on at least a surface of a metal support produced through a step of roughening and anodizing, wherein the photosensitive layer is Improving various stains during printing by using a photosensitive lithographic printing plate in which the glossiness of the metal support surface exposed by removing with acetone satisfies the following formulas (1) and / or (2). Can be. A ₈₅ / A ₆₀ = 8 to 12 (1) B ₈₅ / B ₆₀ = 8 to 12 (2) In the formula (1), A ₈₅ is incident on the surface of the metal support in parallel to the rolling direction of the metal support in the rolling direction. A ₆₀ is the gloss when light is incident at an incident angle of 60 degrees, and A ₆₀ is the gloss when light is incident at an incident angle of 60 degrees. In the formula (2), B ₈₅ is the gloss when light is incident on the surface of the metal support at a right angle to the rolling direction at an incident angle of 85 degrees, and B ₆₀ is also the light incident at an incident angle of 60 degrees. It is the glossiness when it is made to be.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As a metal support of a photosensitive lithographic printing plate according to the present invention, an aluminum plate is usually used, What laminated | stacked the aluminum plate can also be used. As aluminum, pure aluminum or other elements of up to 10% by weight of aluminum, such as silicon, iron, manganese, copper, magnesium, chromium,
It is preferable to use an aluminum alloy containing an alloy element selected from zinc, bismuth, nickel, titanium and the like.
Normally JIS A1050, 1100, 1200, 30
03, 3103, and 3005 materials are used. The thickness of the aluminum plate is arbitrary, but is usually 0.1 to 0.5.
mm. To remove rolling oil and the like adhering to the surface of the aluminum plate, the aluminum plate is subjected to a degreasing treatment of washing with a solvent, a surfactant, an alkaline aqueous solution or the like, and thereafter, is subjected to surface roughening and anodic oxidation.

[0008] As is well known, the surface roughening treatment includes surface roughening by mechanical means such as ball polishing, brush polishing, blast polishing, and buff polishing, and commercial alternating current in an aqueous solution containing an electrolyte such as hydrochloric acid or nitric acid. Electrochemical surface roughening by electrolysis with alternating or direct current of various waveforms such as high frequency alternating current, triangular alternating current,
Various methods are known, such as chemical surface roughening using a strongly alkaline aqueous solution, and surface roughening by a quantum mechanical method such as a pulsed laser beam, an electron gun, and plasma. Among these, the electrolytic lithographic printing method is preferably used for producing the photosensitive lithographic printing plate according to the present invention. Among them, an electropolishing method in which electrolysis is performed with a three-phase alternating current using an aqueous hydrochloric acid solution is preferable. The electrolytic solution preferably has a hydrochloric acid concentration of 5 to 35 g / l, an aluminum concentration of 0.1 to 10 g / l, and a solution temperature of 10 to 60 ° C.
Or a commercial three-phase AC of 60 Hz at 20 to 200 A / dm.
Preferably, it is used at a current density of ² . The photosensitive lithographic printing plate according to the present invention, the surface average roughness Ra of the metal support surface exposed by removing the photosensitive layer with acetone is 0.4 to 1.0,
It is particularly preferably 0.48 to 0.75 μm, but the surface average roughness of the metal support surface is basically determined by the degree of surface roughening in the surface roughening step. It is preferable that the surface is roughened so that the subsequent surface average roughness falls within the above range.

The roughened aluminum plate is subjected to the following anodic oxidation treatment after alkali etching as required. Anodization, as is well known, sulfuric acid, phosphoric acid, oxalic acid,
Current density 5 in an aqueous solution of an acid selected from chromic acid
~60A / dm ^2, voltage 1~100V, electrolysis time of 5 seconds to
It is performed under the condition of 50 minutes. In the production of the photosensitive lithographic printing plate according to the present invention, it is preferable to perform anodic oxidation in a sulfuric acid aqueous solution having a concentration of 200 to 300 g / l, and the electrolysis conditions are such that the cell diameter of the anodic oxide film to be formed is 30 to 60 nm,
In particular, it is preferable to select the thickness to be 40 to 55 nm. The weight of the formed anodic oxide film is 5 to 50 mg.
/ Dm ² .

The anodized aluminum plate is usually subjected to a hydrophilic treatment. Hydrophilic treatment is usually an acetate such as ammonium acetate or nickel acetate, phosphoric acid, malonic acid, lactic acid, sodium silicate, surfactant, chromate,
Although it is carried out using an aqueous solution of potassium zirconium fluoride, calcium salt, phosphate or the like, it is preferred in the present invention to use an aqueous solution of ammonium acetate salt. An aqueous ammonium acetate solution of preferably 0.01 to 20% by weight, particularly 0.05 to 1% by weight, more preferably 0.05 to 0.5% by weight is heated to 30 to 100 ° C, particularly 50 to 100 ° C.
, An aluminum plate that has been subjected to anodizing treatment is immersed in the solution, and the aluminum plate is once pulled up, washed with water, and then immersed again in an aqueous solution of ammonium acetate. One immersion time may be about 10 seconds. Although the reason is unknown, it is better to repeat immersion with washing in the middle, rather than immersing continuously for several tens of seconds, when producing the photosensitive lithographic printing plate according to the present invention, the metal support It is suitable as a processing method. After the hydrophilization treatment with an aqueous ammonium acetate solution, it is preferable to subsequently perform a hydrophilization treatment by immersion in a dilute aqueous solution of carboxycellulose, starch, polyvinyl alcohol, or the like. The concentration of the aqueous solution is 1% by weight
The following is preferred, and immersion at a liquid temperature of 30 to 120 ° C. for about 0.5 to 90 seconds is preferred.

As the photosensitive composition for the photosensitive layer formed on the metal support, any composition whose solubility or swelling property with respect to a developer changes before and after ordinary exposure can be used. For example, the one described in JP-A-10-20506 may be used. The photosensitive lithographic printing plate according to the present invention can be manufactured by dissolving the photosensitive composition in an appropriate solvent, applying and drying on the metal support obtained above.

The photosensitive lithographic printing plate according to the present invention has the following features:
When the surface of the metal support is exposed by removing the photosensitive layer with acetone, the gloss of the surface of the metal support satisfies at least one of the following formulas, preferably both. The removal of the photosensitive layer by acetone is performed until the photosensitive layer is completely removed by immersing the photosensitive lithographic printing plate in a large amount of acetone at about 20 ° C., shaking for 30 seconds or more, and observing it with the naked eye.

A ₈₅ / A ₆₀ = 8 to 12, preferably 8.5 to 11.5 B ₈₅ / B ₆₀ = 8 to 12, preferably 8.5 to 11.5 In the above formula, A represents the surface of the metal support. The glossiness when light is incident parallel to the rolling direction, B is the glossiness when light is incident on the metal support surface at right angles to the rolling direction, and the subscripts 85 and 60 are Each shows the incident angle of light. If _A85 / _A60 or _B85 / _B60 is out of the above range, initial stain is likely to occur at the start of printing (usually the first 200 sheets), and background stain due to blanket stain is likely to occur. . Further, when the operation of the printing press is temporarily stopped, stop stains are likely to occur. The glossiness of this metal support surface is
The gloss ratio is determined by the conditions of the series of processes described above, and by appropriately selecting the process conditions, the gloss ratio can be set within the above range.

The photosensitive lithographic printing plate according to the present invention is subjected to image exposure by a conventional method and then developed to form a printing plate. Exposure is usually carried out using a halogen lamp, and 50 mJ /
Exposure treatment is preferably performed at an exposure amount of at least 100 cm ² , especially 100 mJ / cm ² . Development can be carried out by immersing the exposed printing plate in a developer and rubbing the photosensitive layer with a sponge or the like, if desired, but by using an automatic developing machine that automatically performs the steps from development to washing and drying. Is preferred. As the developer, an alkaline aqueous solution obtained by dissolving a hydroxide such as lithium, potassium, sodium, calcium, magnesium, or a silicate in water is used. Therefore, during development, the metal support surface of the non-image area tends to be slightly affected. Therefore, it is preferable to perform development so that the glossiness of the metal support surface of the non-image area after development satisfies the following expression.

A₈₅/ A₆₀= 7-12, preferably 7.5-11.5 B₈₅/ B₆₀= 7 to 12, preferably 7.5 to 11.5 A and B are, as described above, the rolling direction of the metal support surface.
Is the gloss when light is incident parallel or perpendicular to the
Letters 85 and 60 are the incident angles of light, respectively. developing
A of the metal support surface of the non-image area of the later printing plate₈₅/ A₆₀as well as
/ Or B₈₅/ B ₆₀Is outside the above range, the
Initial stain easily occurs on the surface, resulting from blanket stain
Background dirt is also likely to occur. The printing press operation was suspended
In this case, stop dirt is also likely to occur. In addition, the generation of these stains
In addition to raw, printing durability tends to decrease. The metal support surface
To measure the gloss, wash with water and dry immediately after developing with a developer.
It shall be performed on dried ones.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention. % In Examples
And parts are parts by weight and parts by weight.

Example 1 JIS 1050 aluminum sheet (thickness 0.2
4 mm) was immersed in a 3% aqueous sodium hydroxide solution at 80 ° C. for 7 seconds to degrease, and then 15% in a 30% aqueous sulfuric acid solution.
The solution was neutralized for 2 seconds and washed well with water. Next, in a 1% hydrochloric acid aqueous solution (dissolved aluminum ion concentration: 1.0 g / 1) at 20 ° C., a current density of 100 A /
An electropolishing treatment was performed at dm ² for 10 seconds, followed by washing with water. Next, the film was immersed in a 1% aqueous sodium hydroxide solution at 70 ° C. for 3 seconds to perform an etching treatment. Further, in a 30% sulfuric acid aqueous solution at 35 ° C., anodizing treatment was performed at an electric quantity of 200 coulombs / dm ² to form an anodic oxide film of 25 mg / dm ² , and after the treatment, washed well with water. This was added at 80 ° C at 0.
After being immersed in a 2% aqueous ammonium acetate solution (PH = 6.0) for 9 seconds, washed with water, and further immersed in a 70% aqueous 0.2% ammonium acetate aqueous solution (PH = 9.0) for 5 seconds. Thereafter, the substrate was immersed in a 0.005% CMC (carboxylmethylcellulose) aqueous solution (PH = 6.5) at 90 ° C. for 7 seconds, and dried at 50 ° C. for several minutes to prepare a support. A coating solution of a photosensitive composition having the following composition is coated on the support with a wire bar, dried at 90 ° C. for 4 minutes, and has a positive photosensitive layer having a photosensitive layer thickness of 25 mg / dm ^2. Got a version.

Coating solution for photosensitive composition • Reaction product of naphthoquinone (1,2) -diazide- (2) -5-sulfonyl chloride and pyrogallol-acetone resin (Mw (weight average molecular weight) = 2,500) (Reaction rate of hydroxyl group: 20%) 20 parts Copolycondensation resin of phenol and m-, p-mixed cresol (phenol: m-cresol: p-cresol = 5:57:38 (molar ratio)) and formaldehyde (Mw = 5,500) ... 80 parts ・ Novolak resin (Mw = 1,800) synthesized from p-tert-octylphenol and formaldehyde and naphthoquinone- (1,2) -diazide- (2) -5 Reaction product with sulfonyl chloride (reaction rate of hydroxyl group: 50%): 1 part 3,4-dimethoxybenzoic acid: 5 parts 2-trichloromethyl-5- beta-(2-benzofuryl) vinyl] -1,3, 4-oxadiazole ... 1 part Victoria Pure Blue -BOH (Hodogaya Chemical Company) ... 1 part of methyl cellosolve ... 800 parts

The resulting photosensitive lithographic printing plate was placed in acetone at 20 ° C., allowed to flow for 30 seconds to peel off the photosensitive layer, and then dried. The glossiness of the sample was measured in two directions, parallel and perpendicular to the rolling direction, at light incident angles of 60 and 85 degrees. Table 1 shows the measurement results.

The photosensitive lithographic printing plate obtained above was subjected to 300 mJ / c using a 2 kW metal halide lamp.
exposed with m ^2, and then developed using an automatic developing machine Sutaburon 900NP (Fuji Film Company). The developer is D
Using a 9-fold dilution of P-4W (Fuji Film Co., Ltd.)
Developing conditions were a standard condition of the above-mentioned automatic developing machine, a developing solution bath temperature of 30 ° C. and a developing time of 12 seconds. Normally, water at normal temperature was put into the tank of the automatic developing machine in which the rinsing solution and the gum solution were put, and the washing and drying were performed without rinsing and gum treatment. The glossiness of the sample obtained in this manner was measured using two directions, parallel and perpendicular to the rolling direction, at light incident angles of 60 ° and 8 °.
Measured at 5 degrees. Table 1 shows the measurement results. Gardner was used for measuring the glossiness.

Further, the photosensitive lithographic printing plate obtained above is
Solid, flat net and UGRA chart (Kohan products)
Was exposed at 300 mJ / cm ² using a 2 kW metal halide lamp, and then developed under standard conditions with a Stublon 900 NP. The FP-2W gum solution (Fuji Film Co., Ltd.) was placed in the tank of the automatic developing machine immediately before drying.

The printing plate obtained above was attached to a sheet-fed printing machine DAIYA 1F-2 (Mitsubishi Heavy Industries, Ltd.). The process ink HYECOO red (Toyo Ink Mfg.) Was used as the ink, and the printing blanket was used. Is S700
0 (Kinyosha's product), and Astro NO. 1
100 times diluted solution of Mark II (product of Niken Kagaku Co., Ltd.)
C., pH 5.0). The results are shown in Table 1.

Example 2 In the treatment of the aluminum sheet in Example 1,
The second treatment with an aqueous solution of ammonium acetate was performed at 60 ° C., and the next treatment with an aqueous solution of CMC was performed at 0.001%.
A metal support was prepared in the same manner as in Example 1 except that an aqueous CMC solution was used.
A photosensitive lithographic printing plate was produced in the same manner as described above. In the same manner as in Example 1, the measurement of glossiness and the test of printing performance were performed on the photosensitive lithographic printing plate. The results are shown in Table 1.

Example 3 In the treatment of the aluminum sheet in Example 1,
Etching with a 1% aqueous sodium hydroxide solution after the electropolishing treatment is performed at 80 ° C., and a first hydrophilization treatment with an aqueous ammonium acetate solution is performed using a 0.2% ammonium acetate aqueous solution (PH = 7.0) at 80 ° C. The second time was also carried out with a 0.2% ammonium acetate aqueous solution (PH = 7.0) at 80 ° C., and demineralized water (PH = 6.0) instead of the CMC aqueous solution.
A metal support was prepared in the same manner as in Example 1 except that 5) was used, and a photosensitive lithographic printing plate was manufactured in the same manner as in Example 1 using this metal support. In the same manner as in Example 1, the measurement of glossiness and the test of printing performance were performed on the photosensitive lithographic printing plate. The results are shown in Table 1.

Comparative Example 1 In the treatment of the aluminum sheet in Example 1,
Electropolishing is performed in a 2% nitric acid aqueous solution (dissolved aluminum concentration: 1.0 g / l), and anodizing is performed at 20 mg / d.
160 coulombs / m ² to form an anodized film of m ²
dm ² , and after anodic oxidation, well washed with water, immersed in 90 ° C. hot water (PH = 6.0) for 9 seconds, washed with water, and further with a 90 ° C. 0.2% ammonium acetate aqueous solution ( (PH = 9.0) for 5 seconds, then immersed in a 0.01% CMC aqueous solution (PH = 6.5) at 90 ° C. for 7 seconds, and then dried at 50 ° C. for several minutes. A metal lithographic printing plate was produced in the same manner as in Example 1 using this metal support. In the same manner as in Example 1, the measurement of glossiness and the test of printing performance were performed on the photosensitive lithographic printing plate. The results are shown in Table 1.

Comparative Example 2 A commercially available photosensitive lithographic printing plate was measured for glossiness and tested for printing performance in the same manner as in Example 1. The results are shown in Table 1. In Table 1, blanket stain, initial stain, and stop stain were measured as follows.

Blanket soiling: A portion corresponding to a non-image portion of each printing plate is measured on a well-cleaned blanket before printing using a Macbeth reflection densitometer. Then 50
Each time 0 sheets are printed, the same part of the blanket is measured without washing. The measurement results are shown as absolute reflection values. Initial stain: Up to 200 sheets after the start of printing, the presence or absence of stain on which ink adheres to the non-image area was visually determined. Stop stain: After printing 1000 sheets, printing is stopped for 5 minutes. Next, 100 sheets are printed. After the printing was stopped for 5 minutes, 100 sheets were printed again, and the number of spot-like stains generated in the non-image portion (3 dm ² ) of the last printed matter was visually observed.

[0028]

[Table 1]

Claims (5)

[Claims] 1. A photosensitive lithographic printing plate having a photosensitive layer on at least a surface of a metal support produced through a step of roughening and anodizing, wherein the photosensitive layer is exposed by removing the photosensitive layer with acetone. A photosensitive lithographic printing plate wherein the glossiness of the body surface satisfies the following formulas (1) and / or (2). A ₈₅ / A ₆₀ = 8 to 12 (1) B ₈₅ / B ₆₀ = 8 to 12 (2) In the formula (1), A ₈₅ is incident on the surface of the metal support in parallel to the rolling direction of the metal support in the rolling direction. A ₆₀ is the gloss when light is incident at an incident angle of 60 degrees, and A ₆₀ is the gloss when light is incident at an incident angle of 60 degrees. In the formula (2), B ₈₅ is the gloss when light is incident on the surface of the metal support at a right angle to the rolling direction at an incident angle of 85 degrees, and B ₆₀ is also the light incident at an incident angle of 60 degrees. It is the glossiness when it is made to be. 2. The photosensitive lithographic printing plate according to claim 1, wherein formulas (1) and (2) are simultaneously satisfied. 3. The photosensitive lithographic printing plate according to claim 1, wherein the metal support is an aluminum plate or a non-aluminum substrate and an aluminum plate laminated on the surface. 4. The surface average roughness Ra of the metal support surface exposed by removing the photosensitive layer with acetone is 0.4 to 1.0 μm.
The photosensitive lithographic printing plate according to any one of claims 1 to 3, wherein 5. The photosensitive lithographic printing plate according to claim 1, wherein the cell diameter of the metal support surface exposed by removing the photosensitive layer with acetone is 30 to 60 nm.