Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2001-05-23
2004-06-08
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S190000, C430S191000, C430S192000, C430S193000, C430S270100, C430S302000, C430S907000
Reexamination Certificate
active
06746812
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photosensitive resin composition containing a novel fluorine-based high molecular compound (hereinafter sometimes referred to as “a fluorine-containing polymer”), in particular, to a photosensitive resin composition useful in a lithographic printing plate. The present invention further relates to a photosensitive resin composition which gives image-forming property of high contrast in a lithographic printing plate.
The present invention relates to a positive type photosensitive resin composition which is suitable for use in manufacturing a lithographic printing plate, an IC circuit and a photomask, in particular, relates to a positive type photosensitive resin composition which gives image-forming property of high sensitivity and high contrast, is excellent in antihalation, safelight tolerance and development latitude. More specifically, the present invention relates to a positive type photosensitive resin composition which exhibits image-forming property of high contrast, excellent antihalation, safelight tolerance and wide development latitude, which is obtained by adding a specific compound to a positive type photosensitive resin composition highly sensitized by a conventionally well-known method without reducing the sensitivity.
The present invention further relates to an image-recording material usable as an offset printing master, in particular, relates to a positive type photosensitive resin composition for infrared laser for a so-called direct plate-making capable of directly plate-making from digital signals of, e.g., a computer.
BACKGROUND OF THE INVENTION
A lithographic printing plate comprising a substrate having coated thereon a photosensitive resin composition is generally subjected to exposure, then the exposed area or the unexposed area is removed by alkali development, thereby an image is obtained. In succeeding printing process, the image area comprising the remaining photosensitive resin composition works as an ink-receiving area and the substrate appeared after dissolution works as a moisture-receiving area, thus a printed matter is obtained. At this time, for obtaining good printed matters, no matter whether it is a negative type lithographic printing plate or a positive type lithographic printing plate, it is preferred that the image area and the non-image area of the image obtained after exposure and development be discriminative as far as possible, i.e., high gradation (high contrast), in view of image reproducibility and scratch resistance, and also high sensitivity is required.
A photosensitive resin composition comprising an o-quinonediazide compound, which is a representative positive type lithographic printing plate, has been industrially used as a very excellent positive type photosensitive resin composition in the production of a lithographic printing plate and as a photoresist. Various methods have so far been suggested for increasing the sensitivity of o-quinonediazide-based positive type photosensitive resin composition, however, those exhibiting image-forming property of high contract, satisfactory antihalation, safelight tolerance and development latitude without reducing the sensitivity have not yet been found.
For example, when the amount of an o-quinonediazide compound is reduced, the sensitivity increases as a matter of course, but the gradation of the image becomes soft with the increase of sensitivity, and antihalation, safelight tolerance and development latitude are deteriorated. Further, when an o-quinonediazide compound is used in combination with a binder having high alkali solubility, the sensitivity increases but the gradation of the image becomes soft with the increase of sensitivity, and antihalation, safelight tolerance and development latitude are deteriorated the same as above.
On the other hand, chemical amplification series photosensitive substances having higher sensitivity than o-quinonediazide compounds in which an alkali-soluble group is protected with an acid decomposable group are suggested in U.S. Pat. No. 4,491,628 and European Patent 249139 and widely used However, even with these compounds, photosensitive resin compositions having image-forming property of high contrast and satisfactory wide development latitude have not yet been obtained.
Here, the terminology “image of soft gradation” means that the difference between the step numbers from which an image begins to remain and the stop numbers at which a film perfectly remains is large when a printing plate is exposed through a step wedge and developed. Conversely, “image of high contrast” means the difference between the step numbers from which an image begins to remain and the step numbers at which a film perfectly remains is small.
Halation is caused in consequence of a lith film being lifted due to the nitrogen gas generated as a result of the decomposition of quinonediazide and perfect contact exposure becoming impossible. In general, when clear sensitivity is the same, the higher the contrast of the image, the more easily is solved the halation.
Safelight tolerance is a criterion showing the stability of the sensitivity of an image when a printing plate is exposed to a safelight such as a fluorescent lamp and the higher the contrast of the image, the higher is the safelight tolerance. This is concerning with concerns the fact that quinonediazide is partially decomposed by a safelight. This is because if the quinonediazide is a little decomposed by a weak safelight when an image is high contrast, the image is not eluted and becomes the same with the image not exposed to a safelight.
A step wedge is a strip film the density of which changes every step, e.g., by 0.15, which is used for obtaining the relationship between the exposure amount and the remaining film amount of the photosensitive layer after exposure and development. Clear sensitivity means the sensitivity when an image begins to be formed after exposure and development.
Development latitude is a characteristic showing the degree of fluctuation of the sensitivity of an image after exposure and development when the concentration of a developing solution is changed and the smaller the fluctuation of the sensitivity, the better is the development latitude.
On the other hand, in a photopolymerization series printing plate containing a monomer having a double bond polymerizable with a photopolymerization initiator, which is a representative negative type lithographic printing plate, in particular, in a laser direct exposure type printing plate which is highly sensitive to a laser beam in a visible light region, when image exposure is carried out with an inner drum type laser plate setter comprising exposing a fixed printing plate with a mirror rotating at high speed, fog is liable to occur due to scattered light and reflected light as the gradation is constitutionally soft. If exposure is conducted with a high energy for increasing the press life, fog due to scattered light and reflected light is worsened more and more, therefore, it has not been possible to increase the exposure amount while increasing the press life. It is necessary to prevent fog due to scattered light and reflected light from generating even with high exposure amount for the purpose of increasing the press life. This problem can be solved by making the gradation high contrast. An image exposure by a laser beam is effected for the time of about 1 &mgr;sec order per dot but fog due to scattered light and reflected light is caused by exposing a photosensitive material to extremely weak light for several minutes of order, as a result the photosensitive layer is photo-set.
Therefore, if the gradation of a photosensitive material in high contrast, the material is photo-set with difficulty by a weak light and removed by development, and does not result in fog.
In a heat-sensitive type lithographic printing plate comprising imaging using an infrared laser beam, etc., as the discrimination of an image area and a non-image is low, i.e., the gradation is low (soft), there are problems
Fujita Kazuo
Kawamura Koichi
Nagashima Akira
Serikawa Takeshi
Watanabe Noriaki
Burns Doane Swecker & Mathis L.L.P.
Chu John S.
Fuji Photo Film Co. , Ltd.
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