Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making printing plates
Reexamination Certificate
2000-06-09
2004-04-20
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making printing plates
C430S271100, C430S330000, C430S019000, C430S947000, C430S945000, C430S277100, C430S278100, C430S309000, C101S456000, C101S457000, C101S462000, C101S467000, C101S478000
Reexamination Certificate
active
06723492
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel processless lithographic printing plate precursor which provides a lithographic printing plate only by imagewise exposure without undergoing development processing and a method for the preparation of a lithographic printing plate employing the same.
BACKGROUND OF THE INVENTION
Lithographic printing plate precursors mainly employed in the field of small-scale commercial printing include (1) a direct drawing type printing plate precursor comprising a water-resistant support having provided thereon a hydrophilic image-receiving layer, (2) a printing plate precursor comprising a water-resistant support having provided thereon a oleophilic image-receiving layer containing zinc oxide, which is subjected to desensitizing treatment with a desensitizing solution after image formation to render the non-image area hydrophilic, thereby providing a printing plate, (3) a printing plate precursor of an electrophotographic light-sensitive material comprising a water-resistant support having provided thereon a photoconductive layer containing photoconductive zinc oxide, which is subjected to desensitizing treatment with a desensitizing solution after image formation to render the non-image area hydrophilic, thereby providing a printing plate, (4) a printing plate precursor of silver halide photographic material comprising a water-resistant support having provided thereon a silver halide emulsion layer, (5) a presensitized printing (PS) plate comprising an aluminum support having a hydrophilic surface having provided thereon a layer capable of forming a resin image upon exposure to an ultraviolet ray, and (6) a water-less presensitized printing (PS) plate comprising an aluminum support having provided thereon a photosensitive layer and a silicone rubber layer.
However, these printing plate precursors have problems, respectively. For instance, although printing plate precursors of type (1) are simple, they may not reach the satisfactory level in view of image qualities and background stains in the non-image areas required to prints, and printing durability (press-life). On the other hand, wet processing such as desensitizing treatment or sensitizing treatment is required in case of using lithographic printing plate precursors of type (2), (3) and (4), and treatment with an aqueous alkaline solution or an aqueous organic solvent solution is indispensable in case of using lithographic printing plate precursors (5) and (6) in order to form printing plates so that increased cost due to employing complicated and large-sized machines for the treatment and undesirable influence on environment caused by waste materials such as exhausted treating solutions are accompanied.
Recently, in the field of printing, computerization of plate-making steps has rapidly proceeded, and a plate-making system in which layout of letters, images and likes is determined on a computer and the information is directly output from an output device to a printing plate precursor draws attention.
Specifically, it is possible to directly produce a printing plate from digital data by exposure with a laser beam without using intermediate films and conventional optical printing methods. As the result, lithographic printing plate precursors which do not need wet processing such as desensitizing treatment or sensitizing treatment, development processing with an aqueous alkaline solution or an aqueous organic solvent solution and baking treatment have been proposed.
Examples thereof include a lithographic printing plate precursor having a heat-sensitive layer comprising a polymer containing heat-decomposable carboxylic ester groups associated with a compound capable of converting light to heat, which forms a printing plate by exposure with a heat laser to decompose the ester groups to generate carboxy groups, thereby rendering its surface hydrophilic, without wet processing, as described in EP-652,483, a lithographic printing plate precursor having a hydrophobic resin surface containing a compound capable of converting light to heat, which forms a printing plate by sulfonating to render its whole surface hydrophilic and exposing with a heat laser to remove the sulfonic groups by heating, thereby rendering its surface hydrophobic to form an image as described in JP-A-60-132760 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), a lithographic printing plate precursor having a layer comprising a hydrophilic crosslinked resin matrix containing a compound capable of converting light to heat and a substance decomposable with heat to convert the hydrophilic resin to oleophilic, which forms a printing plate by exposing with a heat laser, thereby rendering its surface oleophilic to form an image as described in WO 94/23954, a lithographic printing plate precursor having a photosensitive layer containing a electroconductive polymer, which forms a printing plate by scanning electochemical or electric signal, thereby converting hydrophilic-hydrophobic property of its surface as described in EP-279,066, a lithographic printing plate precursor comprising zirconia ceramic, which forms a printing plate by exposing its surface with heat laser to convert oxidation state of the oxide, thereby changing its surface property from hydrophilic to hydrophobic as described in EP-769,372, and a lithographic printing plate precursor comprising an oleophilic under layer provided thereon a thin metallic layer having a hydrophilic surface, which forms a printing plate by exposing with a heat laser to heat-melt the metallic layer, thereby revealing the oleophilic under layer to form an image as described in U.S. Pat. No. 5,632,204.
However, these lithographic printing plate precursors have one or more disadvantages which restrict practical use. For example, difference in a property between an oleophilic image portion and a hydrophilic non-image portion is not large enough in many cases and fatal defect in that background stains occur in prints or printing ink dose not sufficiently adhere on the image portion is accompanied. Also, dampening water used for printing is restricted. Further, materials contained in the printing plate precursors may cause problems due to their poor storage stability.
A lithographic printing plate precursor utilizing anatase-type titanium oxide grains which undergo polar conversion from an oleophilic condition to a hydrophilic condition upon exposure with an ultraviolet ray has also been proposed.
However, since the printing plate precursor can only respond to a radiation having a wavelength of an ultraviolet region, a conventional writing device with a laser beam of visible ray can not be used. On the other hand, development of laser beam of an ultraviolet region having a large power has been still pending. Therefore, there is a problem in that a large load is necessary for writing.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in order to overcome the many problems and restrictions in the prior art described above.
Specifically, an object of the present invention is to provide a lithographic printing plate precursor which provides a lithographic printing plate in a simple and cheap manner without undergoing wet process such as desensitizing treatment, sensitizing treatment or alkaline processing.
Another object of the present invention is to provide a method for the preparation of a lithographic printing plate only by image formation upon imagewise exposure with a visible ray.
Other objects of the present invention will become apparent from the following description.
It has been found that these objects of the present invention are accomplished by the following items (1) and (2):
(1) a lithographic printing plate precursor comprising a water-resistant support having provided thereon a light-sensitive layer containing fine titanium oxide grains doped with a metallic ion which absorb a visible ray and a complex composed of an organo-metallic polymer which is formed by a hydrolysis polymerization condensation re
Baxter Janet
Fuji Photo Film Co. , Ltd.
Lee Sin J.
Reed Smith LLP
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