JP2000135873A - Photosensitive lithographic printing plate and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive lithographic printing plate having excellent operability and no dirt of a picture frame by a simple method and a printing plate capable of preventing a conduction fault when conducting an electric signal when conveying a printing plate or folding a gripper of the plate by bringing a positioning pin into contact with an end face of the plate and operating. SOLUTION: In the photosensitive lithographic printing plate grained at a cut surface after the plate is cut in a predetermined size by a slitter having at least one set of a pair of cutting blades, the cut surface is grained in a roughness same as a surface of a support, a centerline mean roughness (Ra) of the cut surface is 0.2 to 0.7 μm, the maximum height (Rmax) is 12 μm or below. After the surface to be cut is cut, the surfaces are immediately grained one by one or after the many laminated surfaces are cut, the cut surfaces are grained.

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 is preferably used for newspaper printing without causing stains on a peripheral portion of a printed matter. The present invention relates to a method for producing a lithographic printing plate.

[0002]

2. Description of the Related Art At present, the mainstream of a photosensitive lithographic printing plate is one in which an aluminum plate is used as a support and a photosensitive layer is provided thereon. This photosensitive lithographic printing plate, a so-called PS plate, is obtained by subjecting a sheet-like or coil-like aluminum plate to various surface treatments such as graining, anodic oxidation, and hydrophilic treatment, and then forming a photosensitive layer. When used, the original film is brought into close contact with the photosensitive layer and irradiated with actinic rays such as ultraviolet rays, and then subjected to a development treatment to form a printing plate.

When printing is performed using the printing plate obtained in this manner, the edge (the edge) of the printing plate is used as in the case of printing on paper smaller than the size of the printing plate using a normal sheet-fed printing press. There is no problem if the portion corresponding to the edge portion along the line does not become the printing surface, but for example, printing is continuously performed on roll-shaped paper using a rotary press such as newspaper printing. At this time, if the width of the printing plate is smaller than the width of the paper, the printing ink attached to the edges is transferred to the paper, and appears as linear stains on the edges of the newspaper. This stain may be referred to as edge stain (frame stain).

[0004] As a method of preventing such contamination, for example, Japanese Patent Publication No. 57-46754 discloses a method of providing a notch along a corner of an edge of an aluminum support, or Japanese Patent Application Laid-Open No. 7-32758. Has proposed a method in which the edge of an aluminum support is bent to the opposite side to the printing surface. Japanese Patent Publication No. 62-61946 discloses a method of coating an end face of an aluminum plate with a desensitizing liquid containing a hydrophilic organic polymer compound.
No. 843 discloses a method in which a hydrophilic coating layer made of a metal oxide obtained by hydrolyzing and polycondensing an organic metal compound or an inorganic compound is provided on the sides of two or four sides of the photosensitive layer facing each other. Has been proposed. Further, Japanese Patent Application Laid-Open No. 10-35130 discloses that a gap between an upper blade and a lower blade of a slitter device is set to a value of 30 to 100 microns and the slitting device is cut, and the maximum height average value of the roughness of the cut surface is set. Has been disclosed, such that is from 1.2 microns to 12 microns.

However, the above-mentioned method of providing a notch along the corner of the edge of the aluminum support or the method of making the edge of the aluminum support bent to the side opposite to the printing surface are both used. This is the processing of the edge portion, and the cut surface of the aluminum support that has been cut by the slitter is not processed at all, and it is not possible to eliminate the stain caused by the ink adhered to this portion. Also,
When a desensitizing liquid or a hydrophilic substance is applied to the end face, these desensitizing liquids and the like are washed away during the development processing, and are again insensitive with a desensitizing liquid such as an aqueous solution of gum arabic. It is greased. At this time, if the end surface, which is the cut surface, is cut cleanly and is flat like a mirror surface, the desensitizing liquid flies or runs down, and the end surface cannot be covered sufficiently. Oiliness is impaired and stains are likely to occur during printing. Furthermore,
In the method of cutting by providing a gap between the upper blade and the lower blade of the slitter, it is very difficult to set the gap between the upper blade and the lower blade in micron order, it is always unstable, and the workability is poor. This makes it difficult to produce a cut surface with a certain range of roughness, either a very flat surface or an extremely rough surface. If the cut surface is cleanly cut and flat, the surface has poor water retention and is easily stained. Conversely, if the surface is extremely rough, ink is entangled with the surface and stains are easily generated.

[0006]

SUMMARY OF THE INVENTION The present invention provides a photosensitive lithographic printing plate which is excellent in workability by a simple method and does not cause frame stains under such circumstances. In some cases, an electric signal for transporting the plate or bending the edge of the plate is energized by contacting the end surface of the plate with the positioning pin to activate the plate. Is an insulating material such as an aqueous solution of gum arabic, and when completely covered, electricity is not conducted and poor conduction may occur, but a printing plate capable of preventing poor conduction is provided.

[0007]

The present invention is characterized in that a photosensitive lithographic printing plate is cut into a predetermined size by a slitter having at least one pair of cutting blades, and then the cut surface is grained. Wherein the cut surface is grained to the same roughness as the surface of the support, and the center line average roughness (Ra) of the cut surface is 0.2 to 0. 0.7 μm, maximum height (Rmax) is 12 μm
The present invention provides a photosensitive lithographic printing plate characterized in that the cut surface has water retention and prevents poor conduction. Further, the present invention provides a method for producing a photosensitive lithographic printing plate, characterized by graining one by one immediately after cutting the cut surface, or graining the cut surface after laminating many sheets. is there.

In the photosensitive printing plate of the present invention, a flat cut surface is formed by slitter cutting, and thereafter, the cut surface is grained to be as rough as the surface, such as gum coating in an automatic developing machine. It is easy to coat with a desensitizing liquid and has an end face with good water retention during printing. As a result, a photosensitive lithographic printing plate capable of providing a printing plate particularly suitable for newspaper printing without causing stains around the printed matter is provided. In the photosensitive printing plate of the present invention, since the cut surface is grained and uneven, the positioning pin is in contact with the head of the grain because the head of the grain is protruding on the application surface of the gum solution or the like. As a result, electricity is conducted, and poor conduction can be prevented.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A photosensitive lithographic printing plate according to an embodiment of the present invention will be described below with reference to the drawings. When the photosensitive lithographic printing plate is cut by a slitter, there are cases where the photosensitive lithographic printing plate is slit in a horizontal state and cases where it is slit in a vertical state. It is sectional drawing which cuts the photosensitive lithographic printing plate 1 in a horizontal state. This slitter device 2 is provided with upper and lower cutting machines 3 and 4, and the upper cutting machine 3 supports a pair of left and right upper cutting blades (upper blades) supported by a rotating shaft 3 a.
3b and 3c are provided. The rotary shaft 4a of the lower cutter 4 is provided with lower cutting blades (lower blades) 4b and 4c corresponding to the upper cutting blades 3b and 3c. The upper cutting blades 3b and 3c and the lower cutting blades 4b and 4c are rotated in opposite directions. The photosensitive lithographic printing plate 1 in which the photosensitive layer A is coated on the aluminum support 1a has an upper cutting blade 3b,
The sheet is passed between the lower cutting edge 3c and the lower cutting blades 4b and 4c and cut into a predetermined width.

The upper cutting blades 3b and 3c are connected to the lower cutting blade 4
With respect to b and 4c, when the photosensitive lithographic printing plate 1 is disposed so as to be outside the part D to be a product of the photosensitive lithographic printing plate 1, the cut surface may be cut at a right angle, or the lip on the front surface or the front and back surfaces may be crushed. In some cases, the rim has a curved surface or the rim bends in the direction of the back surface.In each case, there is almost no burr generated on the front surface, and the ink is prevented from collecting on the rim during printing. A method.

The present invention is characterized in that a cut section (end face) 11 obtained by cutting the photosensitive lithographic printing plate with the above-described slitter apparatus 2 is grained (polished). When the cut surface is grained (polished), the surface of the aluminum support or even a part of the edges on both the front and back surfaces may be grained (polished). Further, when the lip is crushed as described above, or when the lip is bent in the direction of the back surface, even that portion may be polished. However, this does not impair the desired effects of the present invention. In this case, the photosensitive layer at the end of the surface may be polished and removed, but in this case, there is no problem.

In the present invention, graining (polishing) is performed by continuously graining a photosensitive lithographic printing plate with a slitter and immediately graining the sheet in a sheet-like state, or after cutting, a large number of photosensitive lithographic printing plates. There is a method of graining (polishing) the end face in a state where the sheets are stacked.

As a method and means for graining (polishing), a cut surface is a wire brush, a nylon brush, a nylon brush containing abrasive grains, a metal file, a paper file, a buff,
There are methods such as buffing with abrasives, grinding stones, grinding stone rods, etc., whose surface is rough, mechanical or manual rubbing, or etching of the end face with corrosive chemicals. Not something. In the case of graining (polishing), it is more preferable to grind the material vertically and horizontally instead of only in one direction, or to grind the cloth, since the grain becomes denser and tighter.

The photosensitive lithographic printing plate of the present invention has a photosensitive layer provided on an aluminum plate as a support, and the roughness of the grained (polished) cut surface (end face) is as follows:
In order to maintain the same water retention as the surface of the support, it is desirable that the surface has the same roughness as the surface of the support. When this roughness is represented by a method defined in JIS-B0601-1982, the center line average roughness (Ra) is preferably 0.2 to 0.7 μm, more preferably 0.3 to 0.6 μm.
m, and the maximum height (Rmax) is desirably 12 μm or less. When Ra is less than 0.2 μm, the surface becomes too flat, the coverage of the gum solution and the like and the water retention at the time of printing are deteriorated, and poor conduction tends to occur.
If it exceeds μm, the end face becomes too rough, and ink at the time of printing tends to accumulate in that portion, which is not preferable because it becomes liable to be stained. Also, when Rmax is more than 12 μm, the end face becomes too rough, and the end face becomes rather dirty.

FIG. 2 shows a slitting device 5 using four pairs of upper and lower cutting blades, slits a wide photosensitive lithographic printing plate 1 and cuts a part D to be a product into two pieces at the same time. FIG. In such a case, the unnecessary portion E is generated at the central portion and both sides.

The photosensitive lithographic printing plate of the present invention comprises an aluminum plate as a support and a photosensitive layer provided thereon. The surface of the aluminum support is subjected to a graining treatment in order to improve the adhesion to the photosensitive layer and to improve the water retention. This graining treatment is generally performed by graining (also called polishing or surface roughening) by a mechanical method or an electrical method, by chemical etching, or by combining these treatments.
At this time, the average roughness Ra of the surface of the aluminum support is generally 0.2 to 0.7 μm, and more preferably 0.3 to 0.7 μm.
It is preferable that the maximum height Rmax is 12 μm or less. When Ra is 0.2 μm or less, the water retention of the surface and the adhesion to the photosensitive layer are deteriorated.
Undesirably, the photosensitive layer tends to remain in the grains having a grain size of more than 7 μm, and background stains easily occur during printing. Also, when Rmax is equal to or greater than 12 μm, background contamination is likely to occur.

After graining as described above, anodizing treatment is performed in a sulfuric acid or phosphoric acid bath, whereby an anodized film is formed on the surface of the aluminum plate. After the anodic oxidation treatment is performed in this manner, a sealing treatment or a hydrophilic treatment is performed as necessary.

Thereafter, a photosensitive layer is applied to the aluminum plate. The photosensitive layer is not particularly limited, and is conventionally used as a photosensitive layer in a photosensitive printing plate material,
For example, a negative photosensitive composition comprising a diazo resin and a polymer compound, a positive photosensitive composition comprising an o-quinonediazide compound and a novolak resin, an addition-polymerizable unsaturated monomer, a photopolymerization initiator and a light comprising a polymer compound A negative photosensitive composition comprising a polymerizable composition or a photocrosslinkable composition containing cinnamic acid or a dimethylmaleimide group; a negative or positive photosensitive composition comprising a heat mode writing type compound as a photosensitive material; 55-161250, JP-A-4-
An electrophotographic photosensitive composition described in JP-A-100052 or a photosensitive layer utilizing a silver complex salt diffusion transfer method provided with a physical development nucleus and a silver halide emulsion layer can be used.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Example 1 and Comparative Example 1 First, a coiled aluminum plate (material 1050 according to JIS) having a thickness of 0.3 mm and a width of 500 mm is prepared.
Then, after the coiled aluminum plate is degreased with an alkali, the surface is polished with a nylon brush while applying a water suspension of permiston, and then washed well with water. Next, the surface of the coiled aluminum plate was etched at 4 g / m 2 with a caustic soda solution, and then washed with running water. Subsequently, the resultant was electropolished in a 1% by weight hydrochloric acid bath at an electric quantity of 200 coulombs / dm2, and washed with water. next,
After neutralization and washing in a 20% by weight nitric acid aqueous solution, 10% by weight
Anodizing treatment in a sulfuric acid aqueous solution is performed to obtain 2.0 g / m 2
An anodic oxide film was formed. After washing with water, Jls
An aqueous solution containing 10% by weight of No. 3 sodium silicate,
C., immersion treatment for 30 seconds, washing with water and drying.

On the thus obtained aluminum plate, a photosensitive solution having the following composition was dried to have a coating film weight of 1.8 g / m 2.
2 and dried to prepare a coiled negative photosensitive printing plate (negative PS plate). Composition of photosensitive solution 2-hydroxy-3-phenoxypropyl methacrylate / 2-hydroxyethyl methacrylate / methacrylic acid / methyl methacrylate / acrylonitrile = 30/20/5/20/25 weight ratio of copolymer 3.0 kg 4-diazo 10. 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonate of a condensate of diphenylamine and formaldehyde 0.3 kg Victoria Pure Blue BOH (manufactured by Hodogaya Chemical Industry Co., Ltd.) 0.1 kg oxalic acid 0.03 kg ethylene glycol monomethyl ether 0 kg N, N'-dimethylformamide 1.0 kg

Next, using a slitter apparatus 2 as shown in FIG. 1, the clearance (clearance) between the cutting blades 3b, 3c and 4b, 4c is set to 60 μm, and the vertical penetration (overlap) is set to 1.2 mm. And a width of 398 mm. Thereafter, the sheet was continuously cut to a length of 560 mm, and both sides having a width of 398 mm were rubbed and polished several times with a No. 600 paper file. Ra at this time
Was 0.57 μm and Rmax was 10.2 μm. It should be noted that Comparative Example 1 does not polish both cut sides.

Next, the photosensitive printing plates obtained in Example 1 and Comparative Example 1 were subjected to image forming exposure, and then 10 g of potassium silicate, 40 g of phenyl glycol, 5 g of potassium isopropylnaphthalenesulfonate, and 2 g of potassium sulfite. , Developing with a developing solution consisting of 900 g of water,
After washing with water, a gumming treatment was performed to the surface and the end face using an aqueous solution of gum arabic of 8 ° Baume.
Upon careful examination of this portion, the cut surface of Comparative Example 1 showed a lack of gum solution.

Using these plates, a newspaper ink manufactured by Nippon Shimbun Ink and a 0.5% Alky etch solution manufactured by Toyo Ink are wet-wet on a newspaper rotary press manufactured by Tokyo Kikai Seisakusho. Printing was performed under the printing conditions in which the amount of ink was larger than normal and the amount of dampening water was smaller than normal. as a result,
In the peripheral portion in the vertical direction of the newspaper printed from Example 1,
No stain was seen from the start of printing until the end of printing. On the other hand, in the vertical peripheral portion of the newspaper printed from Comparative Example 1, linear stain was partially generated from the start of printing to the end of printing.

Example 2, Comparative Example 2 In the same manner as in Example 1, a coil-shaped photosensitive printing plate having a width of 960 mm was produced. Using a slitter device 6 as shown in FIG. 2, the coil was cut into two pieces having a width of 398 mm with the clearance of the upper blade and the lower blade set at 30 μm and the overlap at 1.0 mm. Then length 110
The product was cut into 0 mm to obtain two products. 50 each
After stacking the sheet-shaped photosensitive printing plates of 0 sheet by sheet, both side portions having a width of 398 mm were polished with a No. 1000 file. The average value of Ra at this time is 0.38
μm and Rmax were 5.6 μm. In addition, the thing which did not grind both side parts cut at this time is set to the comparative example 2. When plate making and printing were performed using these plates in the same manner as in Example 1, the plate of Example 2 did not have edge stains (frame stains), but the plate of Comparative Example 2 had linear stains. Occurred.

Example 3, Comparative Example 3 A coil-shaped photosensitive printing plate having a width of 960 mm was produced in the same manner as in Example 1. Using a slitter device 6 as shown in FIG. 2, the clearance of the upper blade and the lower blade was set to 30 μm, the overlap was set to 1.0 mm, and the width was continuously 398 mm. I cut two pieces. Next, the slit cross section was polished in contact with a rotating grit buff (grade # 600), and then cut to a length of 1100 mm to obtain two products at a time. At this time, the average value of the roughness Ra of the cut surface is 0.42 μm, Rm
ax was 6.2 μm. In addition, the thing which did not grind the both-cut cross section slit at this time is set to the comparative example 3. These plates were exposed, developed and coated with a finisher gum using an automatic plate making machine FNR402II (manufactured by Fuji Photo Film Co., Ltd.), and came to the bent portion of the grip.
Due to the poor contact with the positioning pins, poor conduction occurred, and several plate accidents occurred when the plate making machine stopped. Also,
When the printing plates of Example 3 and Comparative Example 3 were printed in the same manner as in Example 1, the printing plate of Example 3 did not have stains on the peripheral portion. There has occurred.

[0026]

From the above results, in the printing plate manufactured from the photosensitive printing plate of the present invention, even when the printing conditions are severe, edge stains (frame stains) in the peripheral portion of the printing do not occur, and plate making is performed. No accidents such as poor conduction occur on the machine.

[Brief description of the drawings]

FIG. 1 is a sectional view when a photosensitive lithographic printing plate is cut in a horizontal state using a slitter apparatus.

FIG. 2 is a cross-sectional view when a photosensitive lithographic printing plate is cut using a slitter using four pairs of upper and lower cutting blades.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive lithographic printing plate 1a Aluminum support 2 Slitter 3 Cutting machine 3a Rotating shaft 3b Upper cutting blade (upper blade) 3c Upper cutting blade (upper blade) 4 Cutting machine 4a Rotating shaft 4b Lower cutting blade (lower blade) 4c Lower cutting blade (lower blade) 5 Slitter device 11 Cross section (end face) A Photosensitive layer D Product part E Unnecessary part

Continued on the front page F-term (reference) 2H025 AA00 AB03 EA01 2H096 AA06 CA03 2H114 AA04 AA14 AA23 DA04 DA06 DA10 DA59 DA73 EA02 EA06 FA01 GA03

Claims (5)

[Claims] 1. A photosensitive lithographic printing plate which has been cut into a predetermined size, the cut surface of which is roughened. 2. The photosensitive lithographic printing plate according to claim 1, wherein the roughened cut surface has the same roughness as the surface of the support of the photosensitive lithographic printing plate. 3. The roughened cut surface has a center line average roughness (Ra) of 0.2 to 0.7 μm and a maximum height (Rma).
2. The photosensitive lithographic printing plate according to claim 1, wherein x) is 12 μm or less. 4. A method for producing a photosensitive lithographic printing plate, comprising cutting a photosensitive lithographic printing plate into a predetermined size with a slitter having at least one pair of cutting blades, and graining the cut surface. 5. A photosensitive lithographic printing plate, in which a plurality of photosensitive lithographic printing plates are cut into a predetermined size by a slitter having at least one pair of cutting blades, and a plurality of the lithographic printing plates are laminated and the cut surfaces thereof are grained. Production method.