Printing – Planographic – Lithographic plate making – and processes of making or using...
Reexamination Certificate
1999-09-20
2001-05-29
Colilla, Daniel J. (Department: 2854)
Printing
Planographic
Lithographic plate making, and processes of making or using...
C101S463100, C101S467000, C430S019000, C430S302000
Reexamination Certificate
active
06237493
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer and a restoration method for a printing plate, utilized mainly in electrophotographic processes using a liquid toner.
2. Description of the Related Art
As a general printing technique, recently digitization of printing processes is progressing. There is thus a challenge to convert an image or the like into digital data by preparing an image or a script with a personal computer or reading an image by a scanner or the like, and to directly utilize the digital data for preparation of a plate used for printing. In this way, a labor-saving effect can be attained in the overall printing processes as well as making highly detailed printing possible.
As a conventional plate, a so-called PS plate is generally known. This plate has a hydrophilic non-image area made of an anodized aluminum oxide, and a hydrophobic image area formed by curing a photosensitive resin on a surface of the non-image area. Printing is performed by transferring ink attached to the hydrophobic image area onto a paper surface. This PS plate is not one which can cope with above mentioned digitization of the printing processes.
On the other hand, in addition to the above described PS plate there has been proposed another method which can cope with digitization of printing processes and make preparation of the plate easy. For example, there is known a method in which a picture line is registered by a laser beam on a PET film on which a laser absorbing layer such as carbon black has been applied and a silicon resin layer has further been applied thereon, to thereby heat the laser absorbing layer so that the silicon resin layer is burnt by the heat to thereby prepare a plate. Moreover, there is known another method in which an lipophilic laser absorbing layer is applied onto an aluminum plate, and a hydrophilic layer is applied thereon, which is then burnt by a laser beam in the same manner as described above to thereby prepare a plate.
With the related art however, there are problems as described below. First, with the PS plate, significant time and cost are required in the preparation thereof so that particularly with the printing of a small number of copies, this causes a cost increase in printing. Moreover, when the printing of one pattern has been completed and the next printing is to be performed, the plate must be replaced, and the formerly used plate discarded. Furthermore, as described above, the PS plate is not one which can cope with the digitization of printing processes. That is to say, with the PS plate, a plate cannot be directly prepared from digital data, making it impossible to realize digitization of printing processes for attaining laborsaving and highly detailed printing.
Moreover, preparation of a plate which can cope with the above described digitization, that is one using a PET film or an aluminum plate can certainly be prepared directly from digital data, but once the printing of one pattern is completed, the plate must be replaced by a new plate for printing to be possible. That means there is no difference to the above described PS plate, in terms of the circumstances that the plate once used must be discarded. That is to say, the printing cost relating to replacement of the plate increases. Furthermore, from the standpoint of global environmental protection which has recently been advocated, discarding a plate used only once is undesirable.
With an electronic editing system using digital data, then as a method for preparing a printing plate directly from the output of a terminal plotter, there is known a method in which after a toner image has been formed on a photosensitive material surface in an electrophotographic process, a non-image area is made hydrophilic using a desensitizer to thereby prepare a printing plate. Moreover, there is another method in which after a toner image has been formed, a photoconductive layer in a non-image area is removed to thereby prepare a printing plate. However, with these plate making methods using the electrophotographic process, restoration of the printing plate for repeated use as with the abovementioned PS plate, the PET film plate, the aluminum plate and the like, has not at all been considered, and a plate used once is discarded.
SUMMARY OF THE INVENTION
The present invention has been completed under this background, with the object of providing a printer and a restoration method for a printing plate which can be reused, while coping with digitization of printing processes.
The present invention utilizes the following means for solving the above described problems.
That is to say, a restoration method for a printing plate according to a first aspect of the invention is characterized in that with a printing plate where an image area is formed on a substrate serving as a hydrophilic surface having an ink repulsion property at the time of printing, by adhering and fixing directly or via an intermediate body a toner image portion formed on a photosensitive material surface, after the printing plate has been subjected to actual printing, the printing plate is restored by removing the image area on the printing plate surface through chemical treatment and/or physical treatment.
According to this method, a printing plate having an image area and a non-image area can be prepared by adhering and fixing a toner image portion formed on a photosensitive material surface on a substrate serving as a hydrophilic surface. At this time, drawing an image on the photosensitive material surface and forming a toner image portion based on the drawing can be executed by a method including exposure by means of a semiconductor laser or the like. Hence, it can be said that the present invention copes with the digitization of printing processes. Moreover, by subjecting the printing plate after completion of printing, to a chemical treatment and/or physical treatment, reuse of the printing plate becomes possible. That is to say, it becomes possible to reform the toner image portion based on a new image. The above described chemical treatment refers to a treatment in which for example a chemical substance or solution which swells and/or dissolves a toner resin for forming the toner image portion, is applied to the printing plate. Moreover, the physical treatment literally refers to a treatment for physically scraping off the toner image portion adhered and fixed onto the substrate.
A restoration method for a printing plate according to a second aspect of the invention is characterized in that the toner image portion formed on the photosensitive material surface is heated on the substrate and/or on the surface of the intermediate body to thereby adhere and fix the toner image portion onto the substrate. Moreover, the toner image portion formed on the substrate after been adhered and fixed is characterized by a third aspect of the invention in that the adhesive force has a surface peeling capability of 3.0 gf or higher.
Accordingly, adhesion and fixation of the toner image portion onto the substrate can be reliably performed, enabling an improvement in printing endurance of the printing plate. Moreover, by stipulating that the adhesive force has “a surface peeling capability of 30 gf or higher”, the above described printing endurance is reliably ensured. Frankly speaking, with this restoration method for a printing plate, it is possible to avoid a situation where the toner is peeled from the substrate during printing.
With a restoration method for a printing plate according to a fourth aspect of the invention, the toner image portion is formed from a liquid toner having at least a 50° or higher contact angle with water.
This toner image portion can demonstrate a sufficient capability as an image area of the printing plate. That is to say, with the toner image portion, ink receptivity is reliably ensured, and during printing, unevenness on the printing face or a deficiency in optical density of printed matter does not arise.
Moreover, with a restoration method for a printing plate acco
Aoki Shoichi
Suda Yasuharu
Colilla Daniel J.
Mitsubishi Heavy Industries Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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