Radiation imagery chemistry: process – composition – or product th – Microcapsule – process – composition – or product
Reexamination Certificate
1998-12-15
2001-06-05
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Microcapsule, process, composition, or product
C430S281100, C430S285100, C430S271100, C522S180000, C522S066000, C428S402200, C428S402210
Reexamination Certificate
active
06242149
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fast-curing photosensitive composition that remains sensitive up to the visible range and that is used in recording inks, materials encapsulated inside photocuring microcapsules for image recording, photosensitive coating compositions, and the like; and to a recording sheet obtained using microcapsules inside which the fast-curing photosensitive composition is encapsulated.
2. Related Art of the Invention
Many conventional photosensitive compositions for image recording and the like are irradiated with lasers or the like, and are cured with the light energy thus produced. Many of these compositions are comprised of photopolymerization initiators (such as aromatic carbonyl compounds) and radical-polymerizable unsaturated compounds containing ethylenic unsaturated groups.
Photosensitive recording sheets are also known. These sheets are obtained by coating supports such as paper and resin films with photosensitive compositions or photosensitive microcapsules obtained by encapsulating such photosensitive compositions inside light-transmitting microcapsules.
Such photosensitive recording sheets are irradiated with light in accordance with image information, latent images are formed by allowing solely the regions irradiated with light to undergo curing, the recording sheet containing the latent images thus formed is then pressed or otherwise mechanically worked, and the uncured microcapsules are broken up, causing the dye precursor to flow out, react with the developer, and render the images visible, completing the recording.
The range of application of conventional photosensitive compositions is, however, very limited because these photosensitive compositions have a much lower photopolymerization initiation capacity with respect to light sources in the visible range (above 400 nm) than in the ultraviolet range (400 nm and less).
A photosensitive composition with higher sensitivity in the visible range is needed for achieving faster scanning exposure with low-energy light.
Several proposals have been made concerning photosensitive compositions that are sensitive to visible light. Examples of such proposals include complex initiator systems containing dyes and aliphatic amines (Japanese Patent Publication No.44-20189); systems containing hexaarylbiimidazoles, radical-producing agents, and dyes (Japanese Patent Publication No.45-37377); systems containing hexaarylbiimidazoles and p-dialkylaminobenzylidene ketones (Japanese Patent Application Laid-open No.47-2528); systems containing cyclic cis-&agr;-dicarbonyl compounds and dyes (Japanese Patent Application Laid-open No.48-84183); systems containing carbonyl compounds and tertiary amines (Japanese Patent Application Laid-open No.52-134692); systems containing substituted triazine and merocyanine pigments (Japanese Patent Application Laid-open No.54-151024); systems containing biimidazoles and indanones (Japanese Patent Application Laid-open No.54-155292); systems containing hexaarylbiimidazoles and p-dialkylaminostylbene derivatives (Japanese Patent Application Laid-open No.57-21401); systems containing hexaarylbiimidazoles and p-dialkylaminocinnamylidene derivatives (Japanese Patent Application Laid-open No.58-19315); systems containing triazine derivatives and cyanine dyes (Japanese Patent Application Laid-open No.58-29803); systems containing triazine derivatives and thiapyrillium salts (Japanese Patent Application Laid-open No.58-40302); systems containing hexaarylbiimidazoles and n-dialkylstilbene derivatives or of p-dialkylaminophenyl butadienyl derivatives and thiol compounds (Japanese Patent Application Laid-open No.59-56403); systems containing ketone-substituted derivatives and organic peroxides (Japanese Patent Application Laid-open No.60-32801); systems containing &agr;-diketones and mercaptocarboxylic acids (Japanese Patent Application Laid-open No.61-258802); and systems containing &agr;-diketones and polysulfides (Japanese Patent Application Laid-open No.61-258803).
Photosensitive compositions containing these systems can indeed be polymerized when exposed to visible light, but they do not necessarily yield adequate cured products. A need therefore exists for photosensitive compositions highly sensitive to visible light, as is a need for photopolymerization initiators highly sensitive to visible light.
SUMMARY OF THE INVENTION
An object of the present invention, which was perfected in order to overcome the above-described shortcomings, is to provide a fast-curing photosensitive composition in which adequate curing can be achieved even with low exposure energy by improving the sensitivity of the photosensitive composition to visible light, and to provide a recording sheet on which images can be recorded with high speed and on which clear images largely devoid of fogging can be obtained by the use of microcapsules containing this fast-curing photosensitive composition.
Aimed at attaining the stated object, the present invention provide a fast-curing photosensitive composition capable of being cured by the irradiation with light, comprising a radical-polymerizable unsaturated compound, a photopolymerization initiator, and a thiol-containing compound.
The fast-curing photosensitive composition of the present invention can provide adequate curing in a short time even with low exposure energy because it contains a radical-polymerizable unsaturated compound, a photopolymerization initiator for producing free radicals, and a thiol-containing compound that functions as a chain-transfer agent and that promotes chain propagation and addition reactions.
Using this fast-curing photosensitive composition in a recording sheet or the like will therefore allow images to be recorded at a high speed, and clear images largely devoid of fogging to be obtained.
Additionally, in the fast-curing photosensitive composition, as the radical-polymerizable unsaturated compound, there is preferably used a compound having at least one ethylenic unsaturated double bond, that is, a monomer suitable for a chain propagation and addition reaction initiated by free radicals. The fast-curing photosensitive composition using such a monomer can be adequately cured in a shorter time.
Furthermore, in the fast-curing photosensitive composition, as the photopolymerization initiator, there is preferably used a metal arene complex. Accordingly the polymerization reaction can be initiated and appropriately promoted, making it possible to cure the aforementioned fast-curing photosensitive composition in a shorter time even with low exposure energy.
Moreover, the fast-curing photosensitive composition preferably contains 0.01 to 20 weight parts photopolymerization initiator and 0.1 to 30 weight parts thiol-containing compound based on 100 weight parts radical-polymerizable unsaturated compound, and can thus be cured in a short time even with low exposure energy.
In addition, in a recording sheet in which there is supported on a support the photosensitive microcapsules inside which the fast-curing photosensitive composition is encapsulated, the fast-curing photosensitive composition inside the microcapsules can be adequately cured in a short time even with low-energy light such as visible light. Therefore, images which are clear and largely devoid of fogging can be recorded on the recording sheet at a high speed.
This and other objects, features and advantages of the present invention are described in or will become apparent from the following detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described in detail.
The fast-curing photosensitive composition of the present invention capable of being cured by the irradiation with light, comprises a radical-polymerizable unsaturated compound, a photopolymerization initiator, and a thiol-containing compound.
Examples of such radical-polymerizable unsaturated compounds (hereinafter referred to as “polymerizable substances”) include compounds having at least one ethylenic unsatu
Brother Kogyo Kabushiki Kaisha
Le Hoa Van
Lee Sin J.
Oliff & Berridg,e PLC
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