Coating processes – With cutting – holding – severing – or abrading the base
Reexamination Certificate
1999-01-22
2001-07-10
Pianalto, Bernard (Department: 1762)
Coating processes
With cutting, holding, severing, or abrading the base
C427S356000, C427S358000
Reexamination Certificate
active
06258410
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method and apparatus for manufacturing a sensitized printing plate, and more particularly to a method and apparatus for cutting a sensitized printing plate, which can improve a printed matter, and the sensitized printing plate which is cut in the above-mentioned method and apparatus.
2. Description of Related Art
A sensitized printing plate is widely used as a pre-sensitized plate (PS plate). To manufacture the PS plate, surface treatment such as graining, anodic oxidation and chemical conversion coating are, singly or in combination, generally performed on the surface of a sheet-shaped or coil-shaped aluminum plate. Then, a sensitive solution is coated on the plate and the plate is dried, and the plate is cut into a desired size.
On the other hand, as an example of printing by means of the printing plate, which is made by image-sensitizing and developing the PS plate, a printing machine prints paper which is smaller than the printing plate, and paper which is wider than the printing plate as newspaper's printing. In the case of the latter, the both surfaces of the printing plate are used to be printed. For this reason, ink on a cut end of the printing plate is printed on the printed paper. As a result, a printed matter is ruined and its merchandise value can be lowered.
In order to prevent the printed paper from getting stained by the ink on the cut end of the printing plate, for example, Japanese Patent Publication No. 57-46754 has disclosed a method which files a corner of the end of the aluminum base plate with a file, a knife, etc., and Japanese Patent Publication No. 62-61946 has disclosed a method which coats an oil-insensitive solution on a cut surface.
In addition, Japanese Patent Provisional Publication No. 62-19315 has disclosed a method which prevents a burr from forming on the printing surface because the burr makes stains on the printed paper. Furthermore, Japanese Patent Provisional Publication No. 7-32758 has proposed that the cut end is bent to the reverse side of the printing surface, and Japanese Patent Application No. 8-192079 has disclosed a method which hangs the surface of the cut end on the reverse side of the printing surface, and roughs the side surface so as to decrease the stain of the printed paper.
However, the above-mentioned method, which shaves the corner of the end of the base plate with a file or a knife, is not suitable for a mass production. Moreover, a burr is cut, the ink may be put on the filed part, and thereby the ink can stain the printed paper. The method which coats the oil-insensitive solution on the cut surface also has a disadvantage because the printing plates stick to one another and the development cannot be satisfactorily carried out.
Even if the burr is prevented from forming on the printed paper during cutting, the surface is stained under some conditions. Although the stain on the cut end which is bent down (to the reverse side of the printing surface) can be decreased, it may get stuck while it is transferred in a printing machine which exposes an image.
Magenta ink, etc. can stain a sample a long time after the cutting. If a shear droop is formed on the cut end surface so as to prevent the stain caused by the ink, a surface layer extends, and a crack is generated on a sensitized layer and the surface of the sensitized printing plate.
Japanese Patent Provisional Publication No. 5-104872 discloses that the crack on a surface treatment layer causes the stain; however, the Patent Provisional Publication does not disclose about decreasing the stain caused by the crack among the frame-shaped stain on the printing surface of the plate.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above-described circumstances, and has its object the provision of a sensitized printing plate and a method and apparatus for manufacturing it, which can prevent the ink on the cut end from staining the printed paper in the form of frame and which can prevent the printing surface from staining due to the crack appearing during the cutting regardless of the ink type and the time passage.
To achieve the above-mentioned object, the present invention is a sensitized printing plate in which a sensitive layer is formed on a metallic base plate provided with a hydrophilic surface, and the sensitized printing plate is characterized in that shear droops are 20 to 100 &mgr;m at the end of opposite two or four sides of the base plate, and that the average of maximum height of roughness of a cut surface is between 1.2 &mgr;m and 12 &mgr;m. The maximum height average of the roughness of the cut surface is a value, which is obtained by a summation average of the maximum height of each roughness of the two surfaces (a shearing surface sheared with a knife, and a torn surface caused by a crack which is generated) which appear on the cut surface, by the ratio of the shear ed surface and the torn surface to the cut surface at the maximum height. If the average is refereed to as S, then
S=roughness of sheared surface×(sheared surface/cut surface)+roughness of torn surface×(torn surface/cut surface).
Moreover, to achieve the above-mentioned object, the present invention is the method and apparatus for cutting the sensitized printing plate in which the sensitive layer is formed on the metallic base plate provided with the hydrophilic surface, and in the method and apparatus, a clearance between an upper knife and a lower knife for cutting the sensitized printing plate in a predetermined size is set at between 30 &mgr;m and 100 &mgr;m.
In the present invention, the shear droop at the cut end of the sensitized printing plate is 30 to 100 &mgr;m high and 0.1 to 0.3 mm wide, and the burr at the bottom (the surface which is not printed) is less than 50 &mgr;m. The maximum height of the roughness of the cut surface is 1.2 to 12 &mgr;m on the average, and a hydrophilic property is improved, and the frame-shaped stain can be decreased.
As the height of the shear droop increases, the frame-shaped stain can be decreased. When the height of the burr exceeds 100 &mgr;m, the height of the burr at the bottom exceeds 50 &mgr;m. Thus, the flatness of the sensitized printing plate deteriorates when the sensitized printing gate is mounted in a rotary press. Thereby, the printing is badly effected. If the maximum height of the surface roughness of the cut surface is about 0.1 &mgr;m, the satisfactory hydrophilic property cannot be acquired, or the frame-shaped stain cannot be decreased. In order to rough the cut surface, the clearance is expanded, and the surface of a knife is roughed. If, however, the conditions are excessively changed, there are the following disadvantages. If the clearance exceeds 100 &mgr;m, the large burr may appear, and if the surface roughness of the knife is more than 3S (surface roughness value determined by JIS, which is the abbreviation for Japanese Industrial Standard), the chips may appear, or the like.
In order to obtain the satisfactory cut surface by a slitter using a rotary flat knife, the clearance in an axial direction between the upper knife and the lower knife is wider than 5 to 10% of the plate thickness, which is generally regarded as the optimum condition. For example, the clearance is between 30 &mgr;m and 100 &mgr;m, if the plate thickness is 0.3 mm. The surface of the knife is preferably finished to be about 0.4S. If a Gabel type slitter is used in which the upper knife and the lower knife are pressed by a spring and there is no clearance, the above-mentioned cut surface is obtained by providing the tool of the upper knife or lower knife with a notch of between 30 &mgr;m and 100 &mgr;m.
To achieve the above-mentioned object, the present invention is a method of manufacturing the sensitized printing plate in which the sensitive layer is formed on the metallic base plate provided with the hydrophilic surface, and in this method, the clearance between the upper knife and the lower knife fo
Annoura Yasuhiro
Aono Koichiro
Kato Tsutomu
Masuda Takanori
Fuji Photo Film Co. , Ltd.
Pianalto Bernard
Sughrue Mion Zinn Macpeak & Seas, PLLC
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