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
2000-10-27
2003-05-20
Ashton, Rosemary (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
C430S281100, C430S302000, C430S944000
Reexamination Certificate
active
06566035
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image recording material which can be used as a precursor for a lithographic printing plate, a color proof, a photoresist, and a color filter. Particularly, the invention relates to a negative-type image recording material which can be used as a lithographic printing plate precursor which can be used in so-called direct plate making, that is, which enables direct formation of a printing plate by scanning an infrared laser based on digital signals of a computer or the like, and also relates to a lithographic printing plate precursor which can be used in direct plate making.
2. Description of the Related Art
As systems of direct plate making from digital data of computers, there have hitherto been proposed (1) a system using an electrophotographic process, (2) a system using photopolymerization by exposure using a laser emitting blue or green light, (3) a system of laminating a silver salt layer on a photosensitive resin, (4) a system using a silver salt diffusion transfer process, and the like.
However, in the system (1) using the electrophotographic process, the processes of image formation such as charging, light exposure, development, etc., are complicated and the apparatus becomes complicated and large. Also, in the system (2) utilizing photopolymerization, since printing plates having a high sensitivity to blue or green light are used, handling of the printing plates in the dark becomes difficult. Also, in the systems (3) and (4), since silver salts are used, there are drawbacks in that processes such as a development and the like, are complicated and in that the waste liquids contain silver.
On the other hand, the recent progress of laser technology is remarkable, and in particular, high-output and small-sized solid-state lasers and semiconductor lasers emitting infrared rays having wavelengths of from 760 nm to 1200 nm have become easily available. These lasers are very useful as the recording light source used at the time of direct plate making from the digital data of computers. However, because the photosensitive wavelength of many photosensitive recording materials which are useful for practical use is in the visible light region of not longer than 760 nm, these recording materials cannot be used for the recording of images by these infrared lasers. Therefore, materials recordable by the infrared lasers have been desired.
As an image recording material recordable by such infrared lasers, there is a recording material comprising an onium salt, a phenol resin, and a spectral sensitizer described in U.S. Pat. No. 4,708,925. The image recording material is a positive-type image recording material utilizing a dissolution suppressing effect on a developer, which is generated by the onium salt and the phenol resin, and is not a negative-type image recording material as that of the present invention. On the other hand, as a negative-type image recording material, a recording material comprising an infrared absorbent, an acid generating agent, a resol resin, and a novolac resin is described in U.S. Pat. No. 5,340,699. However, such a negative-type image recording material requires a heat treatment after the laser exposure in order to form images, and thus a negative-type image recording material which does not require a heat treatment after exposure has been desired.
For example, in Japanese Patent Application Publication (JP-B) No. 7-103171, a recording material comprising a cyanine dye having a specific structure, an iodonium salt, and an addition-polymerizable compound having an ethylenically unsaturated double bond, which does not require a heat treatment after image-wise light exposure, is disclosed. However, in this image recording material, the strength of the formed image portions is low. Thus, there is a problem that when the recording material is used as a lithographic printing plate, only a small number of prints is obtained at the time of printing. Furthermore, the storage stability of the coating liquid for the image recording layer is insufficient, and when the coating liquid for the image recording layer has been stored over a long period of time and a lithographic printing plate is then prepared, stains occur in the non-image portions in the printing after forming images on the lithographic printing plate. Further, the strength of the image portions is very low, and few prints are obtained.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a negative-type image recording material which can be directly recorded from digital data of a computer or the like by recording using a solid-state laser or a semiconductor laser emitting an infrared ray, and which has excellent printing durability which enables obtaining many good prints without applying a heat treatment during image formation in the case in which the image recording material is used as a lithographic printing plate. Furthermore, the object is to provide a negative-type image recording material wherein the coating liquid for the recording layer has excellent storage stability and can be stored for a long period of time.
As the result of various investigations focusing on the constitutent components of negative-type recording materials, the present inventors have found that the above-described object can be attained by using a cyanine dye having a specific partial structure as the infrared absorbent, and the present inventors thus accomplished the present invention.
That is, the negative-type image recording material of the present invention is a negative-type image recording material for recording images thereon by the irradiation with infrared light, the image recording material comprising (a) an infrared absorbent, (b) an onium salt, (c) a radical polymerizing compound, and (d) a binder polymer, wherein a cyanine dye having the partial structure shown by following formula (I) is used as the infrared absorbent (A):
wherein X
1
represents a halogen atom or X
2
—L
1
(wherein X
2
represents an oxygen atom or a sulfur atom and L
1
represents a hydrocarbon group having from 1 to 12 carbon atoms), and R
1
and R
2
each independently represents a hydrocarbon group having from 1 to 12 carbon atoms, and R
1
and R
2
may bind together to form a ring structure.
Although the mechanism of the present invention is unclear, it is assumed that radical polymerization by the decomposition of the onium salt and the radical polymerization reaction following thereafter sufficiently proceed merely due to the heat generated by irradiation of an infrared laser because of use of this infrared absorbent having the above partial structure, which infrared absorbent exhibits an excellent exothermic property when irradiated by an infrared laser. Thus, images, which have sufficient printing durability, can be formed without carrying out a post heat treatment.
A second object of the present invention is to provide a precursor for a negative-type lithographic printing plate which enables direct recording from digital data of a computer or the like by recording using a solid-state laser or a semiconductor laser emitting an infrared ray, and further has excellent printing durability which allows many good prints to be obtained during printing.
As the result of various investigations focusing on the absorbance, with respect to infrared rays, of precursors for negative-type lithographic printing plates, the present inventors have found that by controlling the absorbance of the photosensitive layer to a definite range, the above-described object can be attained, and have accomplished the present invention.
That is, the negative-type lithographic printing plate precursor of the present invention is a negative-type lithographic printing plate precursor, comprising a support having formed thereon a photosensitive layer containing (a) an infrared absorbent, (b) an onium salt, (c) a radical polymerizing compound, and (d) a binder polymer, wherein absorbance of the photosensitive layer at a wavelength of maximum absorption
Ashton Rosemary
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
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