Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making printing plates
Reexamination Certificate
2000-07-17
2002-12-24
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making printing plates
C430S302000, C430S270100, C430S271100, C430S944000, C101S130000, C101S453000, C101S454000, C101S463100
Reexamination Certificate
active
06497989
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a planographic printing plate. More particularly, the present invention relates to a method of manufacturing a planographic printing plate which exhibits excellent uniformity of the coating thicknesses of layers such as a primer layer, a recording layer, and the like, which are provided on a support.
2. Description of the Related Art
In recent years, laser technologies have developed remarkably. In particular, high output and compact solid-state lasers and semiconductor lasers emitting infrared rays of a wavelength of 760 nm to 1200 nm (hereinafter referred to as “infrared ray lasers” upon occasion) are readily available. These infrared ray lasers are very useful as light sources for recording in the direct production of printing plates from digital computer data. Accordingly, recently, the demand has increased for image recording materials which are highly sensitive to such infrared light sources for recording, i.e., image recording materials in which a photochemical reaction or the like is caused by infrared irradiation and the solubility thereof in a developer is thereby greatly changed.
An example of such image recording materials on which images can be recorded by using an infrared ray laser is a recording material which has a recording layer containing a water-insoluble and alkaline water-soluble high molecular compound and a photothermal conversion substance such as an infrared ray absorbing agent. This image recording material is a positive-type image recording material which utilizes a dissolution suppressing effect with respect to a developer containing an alkaline aqueous solution, which effect is due to the interaction between the compounds forming the recording layer.
The energy of an infrared ray is lower than that of an ultraviolet ray, which has been conventionally used as a light source for exposure. Accordingly, there is a high possibility that non-uniformity of the recording layer may adversely affect the image formation property of a planographic printing plate.
In order to improve the adhesion between the recording layer and the support and prevent the recording layer from easily coming off from the support after exposure, this type of planographic printing plate is generally formed such that a primer layer is provided on the support and the recording layer is superposed on the primer layer. In general, a coating solution for the primer layer is applied onto the support by a bar coater or an extrusion coater so as to form the primer layer. Subsequently, a coating solution for the recording layer is applied onto the primer layer in the same way as the primer layer was applied, and is dried so as to form the recording layer. In the formation of the primer layer, if foreign matter exists on the surface of the support onto which the coating solution for the primer layer is to be applied, application of the coating solution for the primer layer onto portions of the support on which the foreign matter exists is impeded, thereby resulting in local variations (locality) in the application amount (i.e., the coating thickness) of the primer layer. These variations cause local variations in the thermal reaction and the photoreaction of the recording layer, and variations in the physical strength of the planographic printing plate and in the permeability of the developer due to the non-uniformity of the coating thickness. Therefore, drawbacks arise in that the quality and performance of the planographic printing plate deteriorate.
Foreign substances on the support are generally eliminated in the washing and drying processes. However, minute particles of foreign matter may adhere to the support during the conveying thereof, and this adhesion cannot be completely prevented.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of manufacturing a planographic printing plate which suppresses deterioration in quality and performance of the planographic printing plate due to coating defects caused by foreign matter adhering to a support, and which has stable quality such as uniform sensitivity with respect to writing by an infrared ray laser or the like and uniform developability.
The present inventors focused on the uniformity of a coating layer and achieved the present invention after learning, as a result of intensive studies, that coating defects caused by foreign matter or air bubbles can be effectively prevented by providing a plurality of primer layers.
In accordance with a first aspect of the present invention, there is provided a method of manufacturing a planographic printing plate comprising the steps of: (a) providing a support; (b) forming a plurality of primer layers on the support by applying a coating solution to the support a plurality of times; and (c) superposing a recording layer on the plurality of primer layers.
When the coating solution for the primer layer is applied plural times, a coating solution for a previous primer layer is applied, and a coating solution for a subsequent primer layer is successively applied before the coating solution for the previous primer layer has dried. This aspect is preferable in terms of the effects of the present invention.
In accordance with the manufacturing method of the present invention, in order to eliminate foreign matter adhering to the surface of the support onto which the coating solution for the primer layer is to be applied, the following processings are carried out in the application of the primer layers plural times. Namely, in a first application step or in an early stage of the steps of applying the coating solution for the primer layer, foreign matter adhering to the support is partially eliminated by application means. Thereafter, by successively applying the coating solution for the primer layer, slight local variations in the coating thickness caused by the foreign matter at the time of the first application are evened out by the time the final application step is reached, and uniform primer layers can be thereby formed. Therefore, an excellent flat surface of the primer layer can be ensured, and a uniform recording layer can be readily formed on the primer layers. As a result, problems with quality and performance of the planographic printing plate caused by a non-uniform primer layer and recording layer can be suppressed, and a planographic printing plate having stable quality can be easily manufactured.
In accordance with a second aspect of the present invention, there is provided a method of manufacturing a planographic printing plate for use in recording by an infrared ray laser, comprising the steps of: (a) providing a support; (b) forming a plurality of primer layers on the support by applying a coating solution to the support a plurality of times, wherein a total amount of material comprising the primer layers after drying is 2 to 200 mg/m
2
; and (c) superposing a recording layer on a primer layer that was formed last.
Further, in accordance with a third aspect of the present invention, there is provided a planographic printing plate comprising: (a) a support; (b) a recording layer; and (c) a plurality of primer layers disposed between the support and the recording layer, wherein the primer layers comprise coatings of a coating solution.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the structure of a planographic printing plate and a manufacturing method thereof in accordance with the present invention will be described in detail. The method of manufacturing a planographic printing plate in accordance with the present invention is characterized in that a plurality of primer layers are provided on a support.
First, a support of the planographic printing plate will be described. The support of the planographic printing plate in accordance with the present invention is not particularly limited as long as it is a dimensionally stable plate-like material. Examples of the support include paper, paper laminated with plastic (such as polyethylene,
Baxter Janet
Clarke Yvette M
Fuji Photo Film Co. , Ltd.
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