Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2000-06-02
2003-11-25
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S273100, C430S138000, C430S302000, C430S348000, C430S494000, C430S944000
Reexamination Certificate
active
06653042
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a direct heat-sensitive lithographic printing plate precursor for offset printing which requires no development and is excellent in press life, a negative type non-processing lithographic printing plate precursor and a method for producing the same, and a method for lithographic printing using the same. More specifically, the present invention relates to a lithographic printing plate precursor or a negative type non-processing lithographic printing plate precursor and a method for producing the same which can be produced by heat mode image recording, is capable of image-recording by scanning exposure based on digital signals, can be developed with water, or is loadable on a printer without development and printing can be performed as it is, and a method for lithographic printing.
BACKGROUND OF THE INVENTION
A lithographic printing plate generally comprises a lipophilic image area which receives an ink during printing and a hydrophilic non-image area which receives fountain solution. As such a lithographic printing plate precursor, a PS plate (presensitized plate) comprising a hydrophilic support having provided thereon a lipophilic photosensitive resin layer has so far been widely used. A plate-making method of a lithographic printing plate precursor generally comprises performing exposure through the image of a developed lith film and the like and then dissolving and removing a non-image area with a developing solution to thereby obtain a printing plate.
The conventional plate-making process of a PS plate is accompanied by the wet operation of dissolution and removal of a non-image area after exposure, and it has been desired to cease to use or simplify such a wet process. In particular in recent years, since the disposal of waste solutions which are discharged as a result of the wet process not only imposes economical load on the industry but also 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 area of a printing plate precursor can be performed in usual 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 an on-press developing 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 area by contact with the impression drum and the blanket drum in a printer can be exemplified. However, a big problem of the on-press developing 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 during the period of time until the printing plate is loaded on a printer because an image-recording layer is not fixed after exposure.
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 laser beams 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, the simplification of plate-making and the realization of dry system and non-processing system have been further strongly desired from both aspects of the above-described environmental protection and the adaptation for digitization.
Solid state lasers having high output, e.g., a semiconductor laser and a YAG laser are inexpensively available in recent years. As a result, as a 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 printing plate precursor in low to middle degree to cause the change of physical properties 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 thermal change such as the change and rupture 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. This recording system making use of heat generation by high power density exposure is generally 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 on-press developing 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 area) 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 on-press developing system, in particular, easily developed to a computer-to-plate system.
As one means of heat mode system which has been advanced as a measure against the simplification of plate-making process, a technique of microencapsulation has been considered.
Plate materials comprising a support having provided thereon a heat-sensitive recording layer comprising a microencapsulated heat-melting substance and a binder resin, wherein a heated part is converted to a lipophilic part, are disclosed in JP-A-3-108588 and JP-A-5-8575 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). However, since any of the microencapsulated heat-melting substances disclosed in these patents does not have reactivity with the medium, the diffusibility is large and satisfactory discrimination cannot be obtained. On the other hand, lithographic printing plate precursors comprising a support having a hydrophilic surface having provided thereon a recording layer containing an active hydrogen-containing binder polymer together with block isocyanate, and methods for producing the same are disclosed in JP-A-62-164596 and JP-A-62-164049. However, these printing plate materials necessitate the development process to remove a non-printing part after printing.
Further, as one direct type lithographic printing plate material, there is a direct drawing type lithographic printing plate material, wher
Akiyama Keiji
Fukino Kiyotaka
Higashi Shunsaku
Hoshi Satoshi
Baxter Janet
Fuji Photo Film Co. , Ltd.
Gilliam Barbara
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