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
1998-12-22
2001-05-15
Hamilton, Cynthia (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
C430S302000
Reexamination Certificate
active
06232034
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel process less 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 an 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 ultraviolet ray, and (6) a water-less presensitized printing (PS) plate comprising an aluminum support having provided thereon a photosensitive layer containing a photosensitive resin 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 (i.e., press-life). On the other hand, wet processing such as desensitizing treatment or sensitizing treatment is required in case of using printing plate precursors of type (2), (3) and (4), and further treatment with an aqueous alkaline solution or an aqueous organic solvent solution is indispensable in case of using 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 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 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 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 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 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 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; and a 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.
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.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in order to overcome the many problems and restriction in the prior art described above.
Specifically, an object of the present invention is to provide a lithographic printing plate precursor which can form a lithographic printing plate only by image formation on ultraviolet ray exposure.
Another object of the present invention is to provide a lithographic printing plate precursor for ultraviolet ray exposure 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.
A further object of the present invention is to provide a method for the preparation of a lithographic printing plate only by imagewise exposure to ultraviolet 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 a lithographic printing plate precursor for ultraviolet ray exposure comprising a support having provided thereon a light-sensitive layer containing fine anatase-type titanium oxide grains and a resin having a siloxane bond represented by the following formula (I):
wherein A and B, which may be the same or different, each represents —O—, a hydrogen atom, a hydrocarbon group or a heterocyclic group.
The present invention also provide a method for the preparation of a lithographic printing plate comprising exposing imagewise the lithographic printing plate precursor describe above to ultraviolet ray to render the surface of the imagewise exposed area of the light-sensitive layer hydrophilic.
DETAILED DESCRIPTION OF THE INVENTION
The present invention exploits polar conversion of fine anatase-type titanium oxide grains from the oleophilic condition to the hydrophilic condition. The lithographic printing plate precursor according to the present invention is characterized by having a light-sensitive layer containing fine anatase-type titanium oxide grains and a resin having a siloxane bond and providing a lithographic printing plate only by imagewise exposure with ultraviolet ray.
The anatase-type titanium oxide grains used in the present invention have a feature in that they are photo excited upon irradiation with ultraviolet ray to render their surfaces hydrophilic. The phenomenon of changing a surface property of anatase-type titanium oxide grain to the hydrophilic condition upon irradiation with ultraviolet ray is described in detail, for examp
Kasai Seishi
Kato Eiichi
Fuji Photo Film Co. , Ltd.
Gilmore Barbara
Hamilton Cynthia
Reed Smith LLP
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