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
2000-03-31
2002-08-13
Angebranndt, Martin (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S270100
Reexamination Certificate
active
06432615
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an amplificatory acid generation technique, more specifically, the present invention relates to an acid-generating composition capable of amplifying a small amount of radical to a large amount of acid. Furthermore, the present invention relates to a novel recording material capable of obtaining an image by a simple and easy dry process.
BACKGROUND OF THE INVENTION
A large number of chemical reactions using an acid as a catalyst are known and these are important in industry. In particular, in the field of photoresist, techniques of generating an acid by light and performing precision patterning using the acid generated as a catalyst are known. These are called a chemical amplification-type resist and described in
Photopolymer Gijutsu no Shin
-
Tenkai
(
New Development of Photopolymer Technology
), Toray Research Center (1993) and the like. According to this technique, a sensitizer capable of generating an acid by light is used and an acid is generated by exposure. The acid generated thermally diffuses and causes crosslinking of polymers or decomposes the polymer side chain to vary the solubility in the developer and thereby a pattern is formed.
The acid-generating method used here has a limit in attaining higher sensitivity because at most one acid can be generated per one photon.
Also, a color image formation method using color formation by an acid is described in U.S. Pat. No. 5,441,850. In this method, an acid precursor is used, which generates an acid under heating using a superstrong acid onium salt and an acid as catalysts. The superstrong acid onium salt is photolyzed by imagewise exposure to generate an superstrong acid, and the superstrong acid which functions as the catalyst makes the acid precursor produce a large amount of acid under heating. In the final stage, an acid-sensitive color-forming dye precursor is allowed to form a color, whereby a color image is obtained.
However, this method has a problem in that for bringing out the action of a slight amount of superstrong acid generated upon exposure, a medium low in the acid receptivity must be used, but in the photosensitive material designed as such, the superstrong acid generated as a noise is readily amplified and the S/N ratio of the finally obtained image is impaired.
In order to solve this problem, if it is designed to prevent a small amount of noise from being amplified, the sensitivity is in turn reduced and this causes a new problem.
For amplifying a small amount of acid into a large amount of acid, another method is known. As described in
Journal of American Chemical Society, vol.
120, page 37 (1998), a compound which decomposes by a very small amount of acid and generates an acid is known. In this compound, the newly generated acid autocatalytically generates an acid, therefore, a large amplification ratio is expected. However, in the practical viewpoint, this compound has a problem similar to the above-described photosensitive material. More specifically, in the practical use, this acid amplification system can first exert its function when it is used in combination with a certain medium (e.g., binder or developer), but the slight amount of acid to be amplified is neutralized by the medium and a sufficiently large amplification cannot be obtained.
As a still another amplification method, a combination of cationic polymerization with an acid propagating agent has been proposed. JP-A-9-34106 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) describes a combination of a cationic addition polymerizable compound, a cationic polymerization initiator capable of generating a Br&phgr;nsted acid or Lewis acid which activates the cationic polymerization under irradiation of a chemically acting radiant ray, and a substance (acid propagating agent) capable of generating a new acid by the acid. However, this combination system used in the method where the cationic polymerization is allowed to proceed using a slight amount of acid generated upon exposure, is also readily affected by a medium such as binder or moisture in air, therefore, stable sensitivity cannot be obtained.
Furthermore, the acid-generating method referred to above has a problem in that a satisfactory method has not yet been established for generating an acid by exposure using a visible light.
With respect to the method of preparing a recording material by a simple dry processing using an acid and a substance capable of forming a color in the presence of an acid, a very large number of techniques including pressure-sensitive sheet and heat-sensitive sheet are known.
Also, techniques of preparing a photosensitive material using the same combination are known. Among these, JP-A-57-179835, JP-A-57-197538 and U.S. Pat. No. 4,842,976 describe a method for obtaining a photosensitive material having a high sensitivity by a polymerization reaction, where a microcapsule containing a photopolymerization initiator, a monomer and an acid-sensitive color-forming leuco dye is used and the microcapsules are imagewise cured by imagewise exposure and then applied with a pressure, as a result, the contents are released from uncured microcapsules and contact an acidic substance to thereby form a color. Also, JP-A-61-275472 and JP-A-61-278849 describe a method for obtaining higher sensitivity, where a microcapsule containing a silver halide, a reducing agent, a monomer and an acid-sensitive color-forming leuco dye is used and the microcapsule is imagewise cured and then applied with a pressure, as a result, the contents are released from uncured microcapsules and contact an acid substance and thereby a color is formed. According to these methods, a color image may also be obtained by a simple dry process.
Furthermore, JP-A-3-72358 describes a method where an emulsified product containing a photopolymerization initiator, an acidic moiety-containing monomer, and a heat-responding microcapsule containing an acid-sensitive color-forming leuco dye is used and by applying a heat treatment after imagewise exposure, uncured acidic moiety-containing monomers are brought into contact with a leuco dye in the heat-responding microcapsule to thereby form a color.
These methods all are a technique for positive materials which form a color in the unexposed area. However, in the case of performing- exposure by scanning a laser or the like and forming an image abounded in the white ground area, such as document, negative materials of forming a color in the exposed area are suitably used.
U.S. Pat. No. 5,395,736 describes an acid generation method where a superacid precursor is exposed to generate a superacid and the superacid is brought into contact with a secondary acid generator (e.g., oxalic acid diester) and heated together. By combining this method with, for example, an acid-sensitive color-forming leuco dye, a negative photosensitive material can be obtained. However, it is unknown how higher sensitivity can be obtained in this method (acid propagation) as compared with the method of elevating the sensitivity utilizing amplification by the polymerization.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a technique capable of generating a large amount of acid from a small amount of stimulation (information), which is free of being affected by a medium and is excellent in storage stability.
It is more advantageous in increasing the general-purpose property of the technique to enable amplificatory acid generation by a visible light.
Another object of the present invention is to provide a novel color-forming composition using a novel acid-generating method.
Still another object of the present invention is to provide a recording material using the composition, particularly a negative photosensitive material having a high sensitivity.
These objects can be attained by the following means:
(1) An acid-generating composition comprising at least one polymerizable monomer having a nucleophilic group and at least one acid-generating polymerizable monomer.
(2) An a
Ishikawa Shun-ichi
Morita Kensuke
Nakamura Koki
Angebranndt Martin
Birch & Stewart Kolasch & Birch, LLP
Fuji Photo Film Co. , Ltd.
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