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
2002-02-20
2004-12-14
Gilliam, Barbara L. (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
C430S964000
Reexamination Certificate
active
06830865
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Invention
The present invention relates to a positive-type image-forming material which enables image recording by exposure to an infrared laser and increases solubility of a recording layer of an exposed area, and a planographic printing plate precursor using the same. More specifically, it relates to an image-forming material which enables writing by heating through exposure to a near infrared region of an infrared laser or the like and which is especially appropriate for a planographic printing plate precursor for so-called direct plate-making in which plate-making can directly be conducted from digital signals of a computer or the like.
2. Description of the Related Art
In recent years, with the development of a solid state laser and a semiconductor laser having an emission region from a near infrared region to an infrared region, the use of these infrared lasers has attracted much interest as a system of direct plate-making from digital data of a computer.
A positive-type planographic printing plate precursor for an infrared laser which is used for direct plate-making is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 285,275/1995. This invention is an image recording material obtained by adding a substance which absorbs light to generate heat and a positive-type photosensitive compound such as a quinonediazide compound to an aqueous alkaline solution-soluble resin, in which an image is formed such that the positive-type photosensitive compound acts as a dissolution inhibitor to substantially decrease solubility of the aqueous alkaline solution-soluble resin in an image area whereas it does not exhibit dissolution inhibitory properties through heat decomposition and is removed by development in a non-image area. Since quinonediazide compounds are photosensitive materials, an image recording material containing the same is problematic in that, for example, discoloration tends to occur when handled under a white lamp. Meanwhile, without the addition of quinonediazide compounds, a positive image can be obtained. However, in an image recording material from which the quinonediazide compound is excluded, there arises a defect that stability of sensitivity to varying concentrations of a developing solution, namely, a development latitude, is worsened.
Generally, in a positive-type planographic printing plate material capable of recording through heating with an infrared laser, a difference between a dissolution resistance to a developing solution of an unexposed area (image area) and a solubility of an exposed area (non-image area) under various use conditions is not satisfactory, and there has been a problem that excess development or insufficient development tends to occur owing to change in use conditions. Further, there have been problems that even when the surface condition is affected by a minute change by, for example, a touch to the surface in handling, an unexposed area (image area) is caused to dissolve during development, leading to formation of a defect, and further causes a shortened press life or poor ink-receptivity.
Such problems result from a substantial difference in plate-making mechanism between a positive-type planographic printing plate material used for an infrared laser exposure and a positive-type planographic printing plate material used for plate-making through UV exposure. That is, in a positive-type planographic printing plate material used for plate-making through UV exposure, an aqueous alkaline solution-soluble binder resin and onium salts or quinonediazide compounds are included as essential components, and the onium salts or quinonediazide compounds not only act as a dissolution inhibitor through interaction with a binder resin in an unexposed area (image area) but also serve as a dissolution accelerator by generating an acid through decomposition by light in an exposed area (non-image area), thus playing two roles.
On the other hand, IR dyes and other dyes included in a positive-type planographic printing plate material used with an infrared laser merely act as a dissolution inhibitor for an unexposed area (image area), and do not act to accelerate dissolution in an exposed area (non-image area). Accordingly, in order to exhibit a difference in solubility between an unexposed area and an exposed area, a positive-type planographic printing plate material used for an infrared laser is required to employ a resin having a high solubility in an alkaline developing solution as a binder resin from the start, resulting in an unstable condition before development. As such, a positive-type planographic printing plate material has a limitation in storage conditions before recording and has a problem in improving storability with the passing of time.
With respect to improvement of a development latitude, for example, in order to increase dissolution resistance to a developing solution at an unexposed area (image area) without impairing developability of an exposed area (non-image area), JP-A No. 1-288,093 proposes a method which uses a copolymer composed of an addition-polymerizable fluoro-containing monomer having in a side chain a fluoroaliphatic group in which a hydrogen atom bonded to a carbon atom has been substituted with a fluorine atom, and EP 950517 proposes a method which uses a siloxane-based surfactant. Although these methods may contribute to improve resistance to development at an image area in the recording layer to some extent, a difference in solubility between an unexposed area and an exposed area is not large enough to form a sharp and good image considering fluctuation of activity of a developing solution.
SUMMARY OF THE PRESENT INVENTION
It is an object of the present invention to provide a positive-type image-forming material which is excellent in latitude during image-forming through development and in scratch resistance and good in storability, and also to provide a positive-type planographic printing plate precursor which has a recording layer exhibiting such excellent properties and can be used for direct plate-making using an infrared laser.
The present inventors conducted extensive researches to improve development latitude, scratch resistance and storability, and found that the foregoing objects can be attained by addition of a phenol compound having a specific structure. This finding has led to completion of the present invention.
That is, the present invention provides the following.
<1> A heat mode-compatible positive-type image-forming material including: (a) a water-insoluble, aqueous alkaline solution-soluble polymer compound (hereinafter occasionally referred to as an alkali-soluble resin), (b) a light-heat converting agent and (c) a phenol including a partial structure represented by the following formula (I) (hereinafter occasionally referred to as a specific phenol compound), the positive-type image-forming material exhibiting an increase in solubility in an aqueous alkaline solution when the positive-type image-forming material is heated:
wherein: X represents a monovalent terminal group having 2 or more carbon atoms or a linking group represented by —CY
1
Y
2
— or —CHY
1
— in which Y
1
and Y
2
each represent monovalent terminal groups having 1 or more carbon atoms; W represents a monovalent terminal group; and n represents an integer of 1 to 4.
<2> A planographic printing plate precursor in which a recording layer made of a positive-type image-forming material that includes (a) a water-insoluble, aqueous alkaline solution-soluble polymer compound, (b) a light-heat converting agent and (c) a phenol including a partial structure represented by formula (I) is formed on a substrate, the positive-type image-forming material exhibiting an increase in solubility in an aqueous alkaline solution when the positive-type image-forming material is heated.
Although the functional mechanism of the present invention is not elucidated, the compound represented by formula (I) carries a bulky substituent having a relatively high molecular weight at the
Nakamura Ippei
Oda Akio
Tsuchimura Tomotaka
Burns Doane Swecker & Mathis L.L.P.
Fuji Photo Film Co. , Ltd.
Gilliam Barbara L.
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