Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making printing plates
Reexamination Certificate
2000-04-14
2002-11-19
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making printing plates
C430S273100, C430S275100
Reexamination Certificate
active
06482570
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to general printing field, especially a lithographic printing, and particularly a novel lithographic printing plate precursor capable of easily forming a printing plate. Above all, the present invention relates to a lithographic printing plate precursor capable of image recording by scanning exposure based on laser beams and also capable of being loaded on a printer as it is and printing without development.
BACKGROUND OF THE INVENTION
A lithographic printing plate generally comprises an oleophilic (ink receptive) image part which receives ink during printing and a hydrophilic (water receptive) non-image part which receives fountain solution. As such a lithographic printing plate precursor, a PS plate comprising a hydrophilic support having provided thereon an oleophilic photosensitive resin layer has so far been widely used. A plate-making method of a lithographic printing plate comprises, in general, performing exposure through the image of a lith film and the like and then dissolving and removing a non-image part with a developing solution to thereby obtain a printing plate.
The conventional plate-making process of a PS plate necessitates the operation of dissolution and removal of a non-image part after exposure, and as to the improvement of conventional techniques it has been desired to cease to use or simplify such an additional wet process. In particular in recent years, since the disposal of waste solutions which are discharged as a result of the wet process has become a great concern in the industry at large from the standpoint of global environmental protection, there is an increased demand for the improvement in this aspect.
As one simple plate-making method which meets the above demand, there has been suggested a method of using an image-recording layer by which the removal of the non-image part of a printing plate precursor can be performed in general printing process, and effecting development after exposure-on a printer, to thereby obtain a final printing plate. A system of plate-making of a lithographic printing plate by such a method is called a development-on-machine system. Specifically, for example, a method of using an image-recording layer soluble in a fountain solution and an ink solvent, and a method of conducting mechanical removal of a non-image part by contact with the impression cylinder and the blanket cylinder in a printer can be exemplified. However, a big problem of the development-on-machine system is that complicated means should be taken such that a printing plate precursor must be stored under a completely light-shielded state or under a constant temperature condition after exposure during the period of time until the printing plate is loaded on a printer because an image-recording layer is not fixed.
On the other hand, as another trend in this field, digitized techniques of electronically processing, accumulating and outputting image data using a computer have prevailed, and various image output systems corresponding to these digitized techniques have been put to practical use. As one example of such techniques, a computer-to-plate technique directly making a printing plate is attracting public attention, which comprises scanning exposing a printing plate precursor with high convergent radiant rays such as a laser beam carrying digitized image data without using a lith film. With such a tendency, it has become an important technical subject to obtain the printing plate precursor well adapted to this purpose.
Accordingly, simplification of plate-making and the realization of dry system avoiding wet process have been further strongly desired from both aspects of the above-described environmental protection and the adaptation for digitization.
As one example meeting the above demand, a method of making a printing plate is disclosed in JP-A-9-169098 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), which is a method making use of, in one of non-process type printing plate-making methods, irradiating zirconia ceramic with active light and hydrophilizing the irradiated part. However, the light sensitivity of zirconia is small and light conversion effect from hydrophobicity to hydrophilicity is insufficient, so that discriminating property of an image part from a non-image part is unsatisfactory.
Further, it has been found that the surface of titanium oxide becomes hydrophilic with the irradiation of active light, and simple application of this phenomenon to a printing plate precursor has been suggested. As methods of forming a titanium oxide film, a vapor phase method such as a vacuum deposition method, a chemical deposition method, a sputtering method, and a CVD (chemical vapor deposition) method, a liquid phase method such as a spin coating method and a dipping method, a flame spraying method, and a solid phase method utilizing a solid phase reaction are generally known. Although titanium oxide films produced by these conventionally known methods show image forming property superior to each of the above-described methods, further improvement of the discriminating property of an image part and a non-image part is desired.
Solid state lasers having high output, e.g., a semiconductor laser and a YAG laser are available inexpensively in recent years. As a result, as another producing method of a printing plate by scanning exposure which is easy to be incorporated in a digitized technique, a plate-making method using these lasers as an image-recording means is promising. In conventional plate-making methods, image-recording is performed by imagewise exposing a photosensitive precursor at low to middle degree to cause physical characteristic change of the image on the surface of the precursor by a photochemical reaction. On the other hand, in a method of using the exposure of high power density by a high output laser, a large quantity of light energy is irradiated on an exposure region convergently during a momentary exposure time, the light energy is efficiently converted to heat energy to cause a chemical change, a phase change, or a physical change such as changes of form and structure due to the heat, and that change is utilized in image-recording. That is, image data are inputted by light energy such as laser light, but image-recording is performed by the reaction due to heat energy. In general, this recording system making use of heat generation by high power density exposure is called heat mode recording and converting light energy to heat energy is called light/heat conversion.
A big advantage of a plate-making method utilizing a heat mode recording means is that a material is not sensitive to light of general illuminance level, such as room illumination, and images recorded by high illuminance exposure do not necessitate fixation. That is, when a heat mode material is: used in image-recording, the material is safe to room light before exposure and fixation of the image after exposure is not essential. Accordingly, for example, when an image-recording layer which is insolubilized or solubilized by heat mode exposure is used in a plate-making process of imagewise removing an exposed image-recording layer to make a printing plate by the development-on-machine system, it becomes possible to realize a printing system in which an image is not influenced even when the development (the removal of a non-image part) is exposed to atmospheric light in a room for a certain period of time after image exposure.
Accordingly, if heat mode recording is utilized, it is expected that it will be possible to obtain a lithographic printing plate precursor which is adapted to the development-on-machine system.
As one preferred plate-making method of a lithographic printing plate based on heat mode recording, a method which comprises heat mode exposing a hydrophobic image-recording layer provided on a hydrophilic substrate imagewise to convert the solubility/dispersibility of the hydrophobic layer, and removing a non-image part by wet development, according to necessit
Baxter Janet
Burns Doane , Swecker, Mathis LLP
Clarke Yvette M.
Fuji Photo Film Co. , Ltd.
LandOfFree
Method for producing lithographic printing plate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing lithographic printing plate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing lithographic printing plate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2985742