Printing – Planographic – Lithographic plate making – and processes of making or using...
Reexamination Certificate
2002-06-21
2004-01-27
Colilla, Daniel J. (Department: 2854)
Printing
Planographic
Lithographic plate making, and processes of making or using...
C101S454000, C101S458000
Reexamination Certificate
active
06681699
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a planographic printing plate machining device, a planographic printing plate machining method and a planographic printing plate, and more particularly, concerns a planographic printing plate capable of improving the appearance of a surface of printed paper, and a planographic printing plate machining device and planographic printing plate machining method for providing such a planographic printing plate through a machining process (in particular, machining at edge portions).
2. Description of the Related Art
In general, a photosensitive planographic printing plate (hereinafter referred to as a “PS plate” when appropriate) is manufactured through processes in which a support member, such as an aluminum plate in a sheet shape or a coil shape, is subjected to one or an appropriate combination of surface processes such as graining, anode oxidation, silicate processing and other chemical processes and the like, further subjected to coating of a photosensitive liquid and a drying process, and then cut to a desired size. This PS plate is further subjected to plate-forming processes such as exposure, development, gumming and the like, set in a printing press, and coated with ink. Thus, characters, images, etc. are printed on a surface of paper.
Printing using such a PS plate may be printing on printing paper that has a size smaller than the size of the PS plate using a general commercial printing press, and may be printing on printing paper that has a size larger than the size of the PS plate, such as, when printing newspapers and the like. In the latter case, because the entire surface of the PS plate is used as a printing surface, ink adhering to cut edges (peripheral portions) of the PS plate may be printed on the printing paper, resulting in stains and consequently reducing commercial value of printed matter.
With respect to methods for preventing such stains adhering to the surface of printing paper due to unnecessary ink on the PS plate, for example, Japanese Patent Application Publication (JP-B) No. 57-46754 discloses a method in which corners of the edges of an aluminum support member are trimmed with a file or a knife, and JP-B No. 62-61946 discloses a method in which insensitive oil is applied to cut edge surfaces.
Further, as disclosed in Japanese Patent Application Laid-Open (JP-A) No. 62-19315, burrs caused during cutting are one of the causes of such stains and thus there are methods for preventing burrs from occurring at the printing surface side. Furthermore, JP-A No. 7-32758 has proposed shaping in which the cut edges are bent toward a side opposite the printing surface and consequent improvements can be seen.
However, in the method of trimming corners of edge portions of the support member with a file or a knife, PS plates have to be taken out one by one to be trimmed. Therefore, this method is not appropriate for use in bulk processing. When there are defects, such as burrs and scratches, that cause adhesion of ink is caught at trimmed portions, and may eventually cause stains on the surface of printing paper. Further, in the method of applying an insensitive oil to the cut edge surfaces, PS plates may stick to each other, causing difficulty in handling, and development failures may occur.
Moreover, depending on printing conditions, stains may still appear if burrs are simply not caused to occur at the printing paper surface side during cutting. Furthermore, a shape in which the cut edge portions are bent downward (toward the side opposite the printing surface) tends to improve staining but may be a cause of transport failures, such as snagging problems, during transportation at a printing plate forming device that performs exposure and development.
In order to solve the above-mentioned problems, a method has been proposed in which, when a PS plate is sheared with a slitter, cutter, etc., a cutoff is effectively formed at each edge corner portion of a surface treatment layer, at the same time as shearing, by using so-called shearing drops. This method has been respectively disclosed in: JP-A No. 5-104871, JP-A No. 8-11451, JP-A No. 9-53465, JP-A No. 9-323486, JP-A No. 10-35130 and JP-A No. 10-100566 and the like.
However, if cutoffs that are effective for preventing stains on the printing paper surface are formed by shear processing using slitters, cutters and the like, large burrs may occur at a rear surface (a surface opposite the surface at which the surface treatment layer is formed). When these burrs protrude from the rear surface, problems such as, the PS plate meandering while being transported in an exposing device or the burrs falling off and becoming garbage occur. Moreover, at the time of shearing, large cracks may occur at the front surface (the surface at which the surface treatment layer is formed), which affects the printed matter.
In order to solve the above-mentioned problems, a method has been proposed in which such a machining operation is carried out in a coil manufacturing process. For example, cutoffs are formed in a step prior to formation of the surface treatment layer at the support member. However, in this manufacturing method, processing must be done after setting the coil width for each size of the PS plates. In particular, if the PS plates have a large number of sizes, it is difficult to set the coil width for each size. Moreover, pluralities of PS plates may be formed from an elongated web in a width direction thereof but the above-described method is capable of producing only one PS plate in the width direction of the web, resulting in a reduction in manufacturing efficiency.
SUMMARY OF THE INVENTION
The present invention has been devised to solve the above-described problems and its object is to provide a planographic printing plate which has smaller burrs generated at a rear face and has a cutoff portion having a sufficient size at a surface, and a planographic printing plate machining device and a planographic printing plate machining method for forming such a planographic printing plate by cutting.
In a first aspect of the present invention, the planographic printing plate machining device of the present invention is provided with a pressing member which presses and indents a planographic printing plate from the printing side surface, thereby forming a recessed section that has a sloped face which continues from the printing side surface; and a cutting member for cutting the planographic printing plate.
When a planographic printing plate is machined using this planographic printing plate machining device, first, the planographic printing plate is pressed by the pressing member from the surface, with the result that a recessed section having a sloped face which continues from the surface and slants with respect to the surface is formed. Then, the cutting member cuts the planographic printing plate along this recessed section. Therefore, one portion or the whole of the sloped face formed by the pressing member is allowed to remain at the planographic printing plate after cutting, and this remaining sloped face effectively forms a cutoff portion.
Hence, since formation of the cutoff portion and cutting of the planographic printing plate are carried out using separate respective members, it is not necessary to generate a shearing drop to form a cutoff portion at a time of cutting. Therefore, the planographic printing plate can be cut under conditions that make smaller shearing drops at the time of cutting smaller, thereby making reduction of burrs (or more preferably, elimination of burrs) possible. Moreover, because the pressing process is positively done by the pressing member, a cutoff portion having a required size can be formed easily. In particular, even in the case of a planographic printing plate covered with a surface treatment layer containing, for example, an anode oxidation layer, it is possible to form a cutoff portion having a required size.
In the present invention, “cutting” refers to cutting process that passes through a planograph
Colilla Daniel J.
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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