JPH0952466A - Aluminum lithographic printing plate and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithographic printing plate with which stains do not generate around a printed matter. SOLUTION: At least on end faces of opposite two sides of a lithographic printing plate having a hydrophilic layer 2 on at least one surface of an aluminum support body 1, an angular part to be formed of a surface and an end face having the hydrophilic layer 2 is formed of a protruded curved face having no bent part. A part of the protruded curved face is covered with the hydrophilic layer 2. A vertical distance of the end part of the hydrophilic layer and a flat surface 3 of the hydrophilic layer is 10-60μm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel lithographic printing plate,
And its manufacturing method. More specifically, the present invention relates to an aluminum lithographic printing plate that does not cause stains around printed matter in newspaper printing and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a plate material for offset printing, a lithographic printing plate is generally used and is widely used as a PS plate. The PS plate is generally a sheet-shaped or coil-shaped aluminum plate whose surface is roughened, anodized, and if necessary hydrophilicized, then coated with a photosensitive solution and dried, cut and packaged into a desired size, and then lithographically printed. Supplied as a edition. As the cutting method, a shearing method such as flying shear, slitter, or guillotine shear is most commonly used. On the other hand, in the case of printing, a positive or negative original image film is brought into close contact with the photosensitive layer in the plate making process, and exposed and developed. In recent years, automation has progressed, and particularly in newspaper printing, an automatic plate processing apparatus having an automatic printing plate supply function is often used, and the transportability of the printing plate has become an important quality issue of the planographic printing plate.

However, since the edges of the printing plate thus obtained are cut almost at right angles in any case, they are continuously formed into roll-shaped paper by using a rotary press like newspaper printing. When printing by printing, since the width of the printing plate is narrower than the width of the paper, the ink attached to the cutting surface of the printing plate is transferred to the paper,
There is a problem that so-called frame stains appearing as linear stains are generated at the edges of newspapers.

As a method of preventing such frame stains, a method of providing a notch with a file or the like at the corner of the end face of the printing plate as described in JP-B-57-46754 and JP-A-5-104871. As described in the official gazette, a method of subjecting the cutout portion to an anodic oxide film treatment is disclosed. But,
In each of these methods, since a bending portion is provided between the surface having the hydrophilic layer and the cutout portion, the dampening water supplied to the hydrophilic layer surface during printing is sufficient in the notch portion near the bending portion. However, there is a drawback in that it cannot be effectively prevented from being contaminated with the frame because it is not supplied to the frame. Further, the method of curving the surface of the lithographic printing plate described in JP-A-7-32758 to the lower surface side is insufficient in the effect of preventing frame smearing, and the back surface side is also bent, so that transportability is poor. There are problems such as inadequacy,
It was unsuitable as a lithographic printing plate. For this reason, in the printing conditions such as a keyless type newspaper press which has been widely used in recent years with a small supply amount of dampening water and printing conditions using fresh water, the effect is hardly seen, and improvement is required. It was being done.

[0005]

According to the present invention, in such a situation, it is possible to perform suitable printing without causing frame stains on the periphery of the printed matter and to perform plate processing without problems even in an automatic plate processor. It was made for the purpose of providing a smooth aluminum lithographic printing plate.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to develop a lithographic printing plate that does not generate frame stains, and as a result, have found that a lithographic printing plate having a hydrophilic layer on the surface of an aluminum support is used. At least along two end faces facing each other, a very small part of the hydrophilic layer side surface near the end face is pressed and bent to form a convex curved surface having no bent portion at a corner, and a part on the convex curved surface It was found that the purpose can be achieved by providing a hydrophilic layer on the above, and the present invention has been completed based on this finding.

That is, the gist of the present invention is to provide the surface having the hydrophilic layer and the surface having the hydrophilic layer on at least two opposite end surfaces of the lithographic printing plate having the hydrophilic layer on at least one surface of the aluminum support. The corner portion formed by is composed of a convex curved surface having no bent portion, and a part of the convex curved surface is covered with the hydrophilic layer, and the hydrophilic layer end portion and the hydrophilic layer flat surface are formed. In the aluminum lithographic printing plate, the distance between and is 10 μm or more and 60 μm or less. Another feature of the present invention is that the planographic printing plate having a hydrophilic layer on the surface of an aluminum support is cut using a shearing type cutting machine in which the tip angles of upper and lower cutting blades are right angles. It exists in the method of manufacturing a printing plate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As the lithographic printing plate having a hydrophilic layer on at least one surface of the aluminum support in the present invention, any lithographic printing plate having a hydrophilic layer on its surface by the hydrophilic treatment of the aluminum support may be used. The hydrophilic layer may or may not be provided with a photosensitive layer.

In the aluminum lithographic printing plate of the present invention, the surface having the hydrophilic layer and the corner formed by the end face have a bent portion on at least two end faces of the lithographic printing plate facing each other. The convex curved surface is partially covered with a hydrophilic layer.

Referring to the drawings in more detail, FIG.
FIG. 3 is an enlarged cross-sectional view of an end portion of the aluminum lithographic printing plate of the present invention produced by a shearing type cutting machine whose cross-sectional view of a main part is shown in FIG. 2. In FIG. 1, 1 is an aluminum support, 2 is a hydrophilic layer, 3 is a surface having a hydrophilic layer (hydrophilic layer flat surface), 4 is an end face of the aluminum support (hereinafter, simply , End surface), and 5 represents a convex curved surface having no bent portion. Further, a represents a contact point between the convex curved surface and the flat surface of the hydrophilic layer, b represents a contact point between the convex curved surface and the end surface, c represents an end portion of the hydrophilic layer, and θ represents an angle formed between the end surface and the back surface. The aluminum lithographic printing plate of the present invention has a convex curved surface (5, 5) in which a corner formed by the surface 3 having the hydrophilic layer and the end surface 4 has no bent portion.
That is, it is possible to eliminate the frame stain by being configured by a curved surface from a to b) and by covering the specific area thereof with the hydrophilic layer.

The horizontal distance (x) between the contact point (a) between the convex curved surface and the surface of the hydrophilic layer and the end surface (4), and the contact point (b) between the convex curved surface and the end surface and the flat surface of the hydrophilic layer (3). Vertical distance of (y)
Is not particularly limited, but preferably each is 50 μm or more 2
It is not more than 00 μm. That is, if x and y are each less than 50 μm, it may be difficult to form a sufficient convex curved surface and the effect of preventing frame stains may be insufficient, and if it exceeds 200 μm, the convex curved surface becomes excessive and the back surface of the aluminum support may become insufficient. Burrs or bends may be generated on the side, which may cause conveyance failure in the automatic plate processing machine.

In the lithographic printing plate of the present invention, the angle (θ) formed between the end surface and the back surface is in the range of 75 ° to 115 °.
It is preferable from the viewpoint of transportability in automatic plate processing. Further, it is particularly preferable that this angle is substantially a right angle. The lithographic printing plate of the present invention has a sagging amount of the hydrophilic layer film stretched particularly on the convex curved surface, that is, perpendicular to the hydrophilic layer end (c) and the hydrophilic layer flat surface (3). Distance (h) is 10 μm or more 60
It must be in the range of μm or less. By adjusting to this range, cracks generated in the hydrophilic layer coating, particularly the hydrophilic layer coating on the convex curved surface are preferably controlled.

When h is less than 10 μm, the ink adheres to the non-hydrophilic portion on the convex curved surface, and the effect of preventing the frame from becoming dirty cannot be exhibited sufficiently. Ink sticks to the cracks, causing linear stains such as frame stains on the paper. h is preferably 20μ
It is not less than m and not more than 60 μm.

As a method for producing the aluminum lithographic printing plate of the present invention, a method in which an aluminum plate is roughened, anodized, and a hydrophilic grained stencil plate is cut, and then a photosensitive solution is applied and dried, Alternatively, there is a method in which an aluminum plate is roughened, anodized, and hydrophilically treated, and then a photosensitive solution is further applied and dried, followed by cutting and the like. It is not particularly limited as long as it is a cutting method such that the hydrophilic layer of the cut surface of the side or the four sides becomes a convex curved surface without a bent portion, in various conventionally known cutting methods, the shape of the cutting blade, the upper and lower blades The gap and the like may be adjusted as appropriate. However, guillotine shears, flying shears, slitters, etc., which are used for cutting thin materials such as lithographic printing plates and have a sharp blade edge that does not use a right-angled blade, usually have a cutting surface at a right angle. Since it is apt to generate so-called burrs and sags that are bent on both the front surface and the back surface of the lithographic printing plate, it is possible to obtain the desired end shape of the present invention. It's hard to be beaten.

In particular, as shown in the cross-sectional view of the main part in FIG. 2, a shearing force type cutting machine having cutting blades at substantially right and bottom, specifically a shearing type punching machine having such cutting blades. The use of guillotine shear or guillotine shear makes it possible to suppress the occurrence of burrs and settles to the utmost and to advantageously produce the planographic printing plate of the invention. In this case as well, the gap between the upper and lower blades (clearance) can be appropriately selected according to the thickness of the lithographic printing plate to obtain the lithographic printing plate of the present invention having a desired end shape. When the clearance between the blades is adjusted to 7% or more and 20% or less of the thickness of the lithographic printing plate, it is preferable because cracks generated in the hydrophilic layer on the convex curved surface can be suppressed as much as possible. It is also effective to insert a cushioning material such as paper or film between the aluminum plate and the lower blade for cutting, and in that case, when the gap between the upper and lower blades is in the range of 10% to 40%, the present invention Lithographic printing plates are advantageously produced. In the cutting machine shown in FIG. 2, the clearance (clearance) between the upper blade 7 and the lower blade 8 is adjusted by the clearance adjusting mechanism 10.

The aluminum plate having a hydrophilic layer on the surface is usually subjected to degreasing treatment by a known method, and then roughened by chemical polishing, mechanical polishing, electrochemical polishing or a combination thereof, and further sulfuric acid. Anodizing treatment is performed in a bath or the like to form an anodized film, and then hydrophilic treatment is applied to produce a grained board.

There is no particular limitation on the photosensitive liquid, which is generally used as the photosensitive layer of the conventional PS plate,
For example, a photosensitive liquid composed of a diazo resin and a hydrophobic resin, o-
A photosensitive solution containing a quinonediazide compound and a novolac resin, or a photosensitive solution containing an addition-polymerizable unsaturated monomer, a photopolymerization initiator, an organic polymer compound and the like can be used.

An example of the plate making method of the aluminum lithographic printing plate of the present invention will be described. First, a desired original film is vacuum-contacted to the photosensitive layer surface of the lithographic printing plate, and then active light such as ultraviolet rays is selectively applied thereto. Irradiation causes a difference in solubility in the developing solution between the irradiated portion and the non-irradiated portion, and then development processing is performed to form a relief image of the original film.
Further, if necessary, gum treatment is performed.

[0019]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Examples 1 to 4 and Comparative Examples 1 and 2 A coiled aluminum plate having a thickness of 0.3 mm is subjected to degreasing treatment, electrolytic polishing and anodizing treatment according to a conventional method to form an anodized film, and then further sealing treatment and water washing. It dried and the grain board was created.

Next, the PS plate was cut by changing the gap between the upper and lower blades using a shearing type cutting machine shown in FIG. 2 in which the upper and lower cutting blades are at right angles, and the corners of the ends shown in FIG. Samples A to E each having a convex curved surface having no bent portion and a part of which was covered with a hydrophilic layer were prepared. Further, a sample F was prepared by cutting a PET film of 50 μm sandwiched between the lower blade and the PS plate. The sample was subjected to image forming exposure and then subjected to development processing to prepare a printing plate sample, and printing evaluation was carried out by a printing machine. The results are shown in Table 1. However, the occurrence of frame stains was evaluated according to the following criteria.

[Stain Evaluation Criteria] × Thick straight line stain generation △ Thin straight line stain generation ○ Intermittent stain generation ◎ No stain generation at all

[0022]

[Table 1]

From the above results, the sagging amount of the hydrophilic layer is 10
It can be seen that the occurrence of frame stains is suppressed in the case of the printing plate having a size of from μm to 60 μm. Furthermore, such a lithographic printing plate,
When cutting with a shearing type cutting machine in which the upper and lower blades are almost right angles without inserting the cushion material, it is advantageous to achieve by setting the gap between the upper and lower blades to 7% or more and 20% or less of the thickness of the planographic printing plate. I understand that it will be done.

[0024]

INDUSTRIAL APPLICABILITY By using the aluminum lithographic printing plate of the present invention, it is possible to produce a newspaper lithographic printing plate which does not cause stains on the periphery of the printed matter and is suitable for conveyance by an automatic plate processor. Can be offered Moreover, according to the method of the present invention, it is possible to prevent stains on the surface of the printed matter with the ink attached to the cutting surface, and to provide an aluminum lithographic printing plate which has good burrs and burrs on the back surface and has good transportability in an automatic plate processor. Mass production is possible without the equipment of
Its industrial value is great.

[Brief description of drawings]

FIG. 1 is a schematic enlarged view of a cross section of an aluminum lithographic printing plate of the present invention.

FIG. 2 is a sectional view of an essential part of a cutting machine used for manufacturing the aluminum lithographic printing plate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum support 2 Hydrophilic layer 3 Surface having a hydrophilic layer (hydrophilic layer flat surface) 4 Aluminum support end face (end face) 5 Convex curved surface without bent portion a Convex curved surface and hydrophilic layer flat surface Contact point b contact point between convex curved surface and end face c hydrophilic layer edge θ angle between end face and back surface x horizontal distance between a and 4 y vertical distance between b and 3 vertical distance between h c and 3 6 upper blade 7 Lower blade 8 Clearance 9 Clearance adjustment mechanism

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[Procedure amendment]

[Submission date] June 14, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

A negative PS plate was obtained by applying a negative photosensitive solution onto the grained plate and drying it. The thickness of the negative PS plate is about 0.3
mm. Next, the PS plate was cut using a shearing type cutting machine shown in FIG. 2 in which the upper and lower cutting blades are at right angles, and the gap between the upper and lower blades was changed to cut the corners of the end portions shown in FIG. Samples A to E having a convex curved surface having no and having a part thereof covered with a hydrophilic layer were prepared. Also, lower blade and PS
Sample F was prepared by cutting with a PET film of 50 μm sandwiched between the plates. After subjecting the above sample to image formation exposure, development processing was performed to prepare a printing plate sample, and printing evaluation was performed with a printing machine. The results are shown in Table 1. However, the occurrence of frame stains was evaluated according to the following criteria.

Claims (5)

[Claims] 1. A corner portion formed by the surface having the hydrophilic layer and the end face at the end faces of at least two opposite sides of a lithographic printing plate having a hydrophilic layer on at least one surface of an aluminum support. Is formed of a convex curved surface having no bent portion, and a part of the convex curved surface is covered with the hydrophilic layer, and the vertical distance between the hydrophilic layer end and the hydrophilic layer flat surface is 10 μm. An aluminum lithographic printing plate having a thickness of 60 μm or less. 2. A lithographic printing plate having a hydrophilic layer on the surface of an aluminum support is cut using a shearing type cutting machine in which upper and lower cutting blades have a tip angle of substantially right angle. The method for producing an aluminum lithographic printing plate as described in. 3. The gap between the upper and lower cutting blades is 7% or more and 20% or less of the thickness of the planographic printing plate.
The method for producing an aluminum lithographic printing plate as described in. 4. The method for producing an aluminum lithographic printing plate according to claim 2, wherein a cushion material is inserted between the lithographic printing plate and the lower blade to cut the lithographic printing plate. 5. The method for producing an aluminum lithographic printing plate according to claim 4, wherein the gap between the upper and lower cutting blades is 10% or more and 40% or less of the thickness of the lithographic printing plate.